1.
Preliminary Study for Exergetic
Analysis on Sugar Production
in Tanzania
the energy-efficiency of TPC Limited, Moshi
Dar es Salaam and Moshi, Tanzania
February - May 1999
Practical Training by:
René Dijkmans Department of Chemical Engineering and Chemistry, Eindhoven
University of Technology, The Netherlands
Under Supervision of:
Dr. Mrema
Prof. Katima
Prof. Dr. Ir. Janssen
Ir. Van Schijndel
Department of Chemical and Process Engineering,
University of Dar es Salaam, Tanzania
Centre for Environmental Technology,
Department of Chemical Engineering and Chemistry,
Eindhoven University of Technology, The Netherlands

2.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
Preface
This is the report of my practical training in at Taganyika Planting Company Sugar
Estate Limited (TPC ltd.) in Moshi, Tanzania, from February to May 1999. This (first) study
on the exergetic efficiency at TPC ltd. in Moshi was conducted within the project
Environmental Engineering (EvEn), in which the Centre for Environmental Technology
(Eindhoven University of Technology) and the department of Chemical and Process
Engineering (University of Dar Es Salaam) are working together. As a part of the MHO 253
project, Nuffic (Netherlands Organisation for International Cooperation in Higher Education)
sponsored the research as well.
It offered me the opportunity to meet other cultures, both in social life and in business.
TPC was visited with regard to cleaner production and environmental protection, focussing
on the exergetic and energetic efficiency.
I would like to take the opportunity to thank to all persons, who were of assistance to
me and made the practical training possible. First of all, I would like to thank my supervisors,
Dr. Mrema and Prof. Katima of the University of Dar Es Salaam and Ir. Van Schijndel and
Prof. Janssen of the Eindhoven University of Technology.
Next, I would like to thank all of my colleagues at TPC for the big efforts they made to
help me as much as possible. Especially, I would like to express my gratitude to Mr. Makundi
and his wife, for their hospitality during my stay at the factory, and Mr. Assey for all the data
he supplied me with and all the help he gave me when I experienced problems. Also I would
like to thank Mr. Assey and Mr. Mlaki, whose office I shared, for the endless discussions
about the differences between the Tanzanian and Dutch (business-) society.
I would like to express my gratitude towards the 'Bureau Automatisering T' (Bureau of
Automation of the faculty of Chemical Engineering and Chemistry) as well, for borrowing me
a notebook computer for my stay in Tanzania. The notebook has been of big help during my
stay.
Finally, but not less important, I would like to thank all of my family and friends in the
Netherlands as well as all of my new family and friends in Tanzania, for the support they
offered me both in good and less fortunate times. Notably, I would like to thank my girlfriend
Suzanne for all the support she gave me before going to and during my stay in Tanzania.
Thanks to all these people I really had the time of my life in Tanzania. It was an
experience I will never forget and always treasure in my heart. Asante sana. Kwaheri !
Rene Dijkmans

3.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
Summary
Tanzania is striving to reach the levels of economic well being which the developed
countries have achieved. However, the industrial development as was undertaken by the first
world countries would be catastrophic for the environment. Therefore this study focussed on
how to combine economic growth with sustainable development.
Due to the bad condition in which some of the equipment at TPC was, it proved not to
be possible to map all the energetic difficulties at the factory. Though, it was possible to
address the main bottlenecks of the process and suggestions for improvement were done.
However, improving the course of the process is not sufficient to improve the sustainability of
the factory. Non-technical aspects, like behaviour of operators and management can also do
one's bit for a more reliable, time and cost efficient and less polluting factory. Of course this
will inevitably ask for investments.
Despite the fact that some well-intentioned criticism is uttered in this report, TPC
seems to have the power to survive, as it did for the past 65 years. If TPC’s new owner deals
with the factory’s bottlenecks and takes the issues dealt with in this report to hart, the future
of TPC looks promising.

4.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
Table Of Contents
1. General Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 The Country: Tanzania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 The Material: Sugar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 The Factory: Taganyika Planting Company . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 The Study: Cleaner Production and Exergetic Analysis . . . . . . . . . . . . . . . . . . 4
2. Exergy, Environment and Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 The Basics of Exergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Calculating Exergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Process Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Exergy, Environment and Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5 Exergy in Sugar Factories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3. The Manufacture of Sugar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 Simple Flowsheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 Fields and Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.3 Feeding and Extraction of the Juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.4 Clarification of the Juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.5 Thickening and Crystallisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.6 Engines and Engineers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4. The 1998/1999 Production Season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1 The Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2 The Main Production Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3 Remarks on the Production Season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.4 Planning the Future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5. Sugars™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1 Introduction to Sugars™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2 Sugars™ during this project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.3 Working with Sugars™ and Sugars™ Files . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.4 Postscript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6. Material and Heat Balances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.1 System Boundaries and Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.2 Material Balance Total System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.3 Mass Balance Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.4 Enthalpy Balance Total System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6.5 Enthalpy Balance Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7. Exergy Use in Sugar Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.1 Total Exergy Use at TPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7.2 Enthalpy and Exergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8. Cleaner Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.1 Environmental Issues in Developing Countries. . . . . . . . . . . . . . . . . . . . . . . . 26
8.2 Environmental Awareness in Tanzania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.3 Environmental Pollution in Sugar Factories . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.4 Environmental Pollution at TPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
9. Conclusion and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
10. Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.1 Condition of Engines and Engineers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.2 Care for the Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.3 Further Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
11. Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
12. List of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
A. Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.1 Contact List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.2 Process Flow Chart of TPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
A.3 Sugars™ input and output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
A.4 Season Process Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
A.5 Thermodynamic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
A.6 Material and Heat Balances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
A.7 Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
A.8 Tanzanian Emission Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
A.9 Estimated Pollution at TPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

6.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
- 1 -
1. General Introduction
1.1 The Country: Tanzania
The United Republic of Tanzania borders on the Indian Ocean to the east, and has
land borders with eight countries: anti-clockwise from the north, Kenya, Uganda, Rwanda,
Burundi, the Democratic Republic of Congo (across Lake Tanganyika), Zambia, Malawi and
Mozambique. Tanzania covers, including inland water and Zanzibar, an area of 945,234 km2
.
The country comprises several distinct zones: a fertile coastal belt, the Masai Steppe and
mountain ranges to the north, with Mt Kilimanjaro rising to 5,895m, and a high plateau in the
central and southern regions. The climate is tropical on the coast, where it is hot and humid
semi-temperate in the mountains and drier in the plateau region with considerable seasonal
variations in temperature.
According to evidence at Olduvai Gorge and in the Manonga Valley, Tanzania may be
humanity’s place of origin. Around the year 500 Bantu peoples, the ancestors of the majority
of the modern population, began entering the area. Arab coastal settlement and the
introduction of Islam took place between 800 and 900. In the late 1880s Germany took over
the area from the coast to (and including) Ruanda and Urundi, calling it the Protectorate of
German East Africa. There was rather sparse German settlement: the people objected being
‘protected’. In 1905 there was an all-out rebellion, which was put down by a strategically
engineered famine, leading to about 200,000 deaths.
Britain was, at the time, concerned with the islands of Zanzibar and Pemba, which
were declared a British Protectorate in 1890. In 1919, the League of Nations gave Britain a
mandate to administer part of German East Africa, now known as Tanganyika. In 1946, after
the second world war, Tanganyika became a United Nations trust territory. In 1954, a
schoolteacher, Julius Nyerere, founded the Tanganyikan African National Union (TANU),
which promoted African nationalism and won a large public following. The colonial authorities
responded with constitutional changes increasing the voice of the African population while
reserving seats for minority communities. However, elections were held in 1958-9 and again
in 1960. The result was overwhelming victory for TANU, which was by this period
campaigning for independence as well as majority rule.
The new government and Britain agreed at a constitutional conference to full
independence for Tanganyika in December 1961. Zanzibar achieved independence in 1963
as a separate country. Tanganyika became a republic in December 1962, one year after
achieving independence, and the direct presidential election brought TANU’s leader,
Nyerere, to the presidency.
In April 1964, after a revolution had overthrown the Sultan of Zanzibar, Tanganyika
and Zanzibar united as the United Republic of Tanzania. Tanzania came to independence
with a severely underdeveloped economy and extremely limited infrastructure. In an effort to
create socially equitable and rapid development, it became an early proponent of African
socialism, launched in 1967 with nationalisation of banking, finance, industry and large-scale
trade, marketing through boards, and the resettlement of peasants in communal ujamaa
villages created out of large estates. Tanzania was able to record progress in education and
health but, after an initial boom, the formal economic base shrank, production fell and the
parallel economy became a way of life. The Ugandan war, falls in commodity prices and
failures of the policy itself brought the country to the verge of bankruptcy by the mid-1980s.
Pressure for reform grew within Tanzania, and among international donors. The government
responded with constitutional changes, which permitted opposition parties from 1992 and so
brought in a multiparty system.

7.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
1
Charles G.M. Perk, “The Manufacture Of Sugar From Sugarcane”, Sugar Milling
Institute and the University of Natal, Pretoria, South Africa, 1973.
2
J.P. MMbaga, "Practical Training Report Kilombero Sugar Company", University of Dar
Es Salaam, Dar Es Salaam, Tanzania, 1985, p 7-8.
3
Kirk-Othmer, "Encyclopedia of Chemical Technology, volume 21", John Wiley & Sons,
New York, United States of America, 3rd
ed, 1983, p 865.
- 2 -
O
OHOH
HO
HO
HO
O
OH
OH
HO
HO
OH
+
O
OH
HO
HO
HO
O
OH
OH
HO
O
OH
-H2O
CONDENSATION
figure 1: formation of sucrose
1.2 The Material: Sugar
Sugar is the name of a large group of substances which, together with the starches
and celluloses, are know as carbohydrates. Sugars occur widely in nature and are an
important part of the food for man and animals. Various plants contain sugars in blossoms
and fruits. Sugarcane (Saccharum Officinarum L.) and sugarbeet (Beta Vulgaris) are the
main plants that produce sufficient sugar per surface and per year for extraction to be
economically feasible on a commercial scale.1
The actual 'manufacture' of sugar is done by this plants when they absorb oxygen and
water and form D-glucose and D-Fructose in the presence of light (photosynthesis).
12 12 2 122 2 6 12 6 2H O CO C H O Ohv
+  → +
The kind of sugar extracted from these plants however is sucrose, a disaccharide.
Sucrose is the common name of "-D-glucopyranosyl-$-D-fructofuranoside, the disaccharide
is formed by condensation of "-D-glucose and $-D-fructose, producing sucrose and water:
The condensation-reaction is shown in figure 1.
Sucrose (also called table sugar or saccharose) is characterised by, and consumed
for, its pure sweets taste and its appreciable nutritive value.2, 3

8.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
- 3 -
1.3 The Factory: Taganyika Planting Company
The Taganyika Planting Company Sugar Estate Limited started 1933, some kilometres
south of Moshi, Kilimanjaro region. It was founded was owned by the well-known Danish
multinational Maersk. Three years after the first cane was planted, the first bags of sugar left
the company. Thanks to the friendly relationship between Tanzania and Denmark, Maersk
succeeded in preventing the company being nationalised in 1967 and remained owner of the
Taganyika Planting Company. Late 1979, when Maersk wanted to sell the company, it was
handed over to the Tanzanian government. For the management, the ministry for Agriculture
hired an other Danish company, called Carl Bro International for ten years. In 1990, the local
people were ready to take over the management, and the company was handed over to the
Sugar Development Co-operation (SuDeCo), which is also owned by the Tanzanian
government.
Now, in 1999, there is a question of privatisation again. The contracts will most likely
be signed somewhere in May, which will place the company in the hands of Deep River
Beau Champ Limited. This company - from Port Louise on Mauritius - more than doubles its
total sugar-production with this take-over. Other activities of Deep River Beau Champ deal
with maize, groundnuts, potatoes, palm trees, ginger, vanilla, fruit trees, eucalyptus,
asparagus, fresh water prawns, deer farming, fish and poultry. After purchasing it, the new
company has intended to invest US$ 30 million in TPC.
Nowadays, the Taganyika Planting Company owns more than 10,000 hectares (100
km2
) of land. The company has about 3,600 employees working on the fields. The factory,
situated in the southern part of TPC's domain, provides work to another 400 employees. The
greatest part of the personnel lives in one of the four big villages situated on the TPC land,
which accommodate a total of about 20,000 people. The TPC villages are rather
autonomous: they have their own butchers, agricultural products, schools, post-offices,
ho(s)tels, restaurants, bars etc. To give the reader a idea about the size of the company,
some average yearly production figures are given in table 1, for a full report on the
1998/1999 production season see Appendix 5.
Table 1: Key Figures on TPC
property quantity
amount of cane crushed 450,000,000 kg
amount of sugar produced 40,000,000 kg
total fields occupied with sugar 5,000 hectare
amount of fuel oil burnt 650,000 liter
amount of bagasse burnt 150,000,000 kg
turnover 20.000.000 US$
total number of employees 4,000

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Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
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1.4 The Study: Cleaner Production and Exergetic Analysis
Development countries, like Tanzania, are striving to reach the levels of economic well
being which the developed countries have achieved. However, the industrial development as
was undertaken by the first world countries would be catastrophic for the environment. To
combine economic growth with sustainable development, the primary focus of environmental
protection must be preventive measures.
One of the matters the Centre for Environmental Technology researches is the
application of exergy analysis in various industries. Although the practical usefulness of the
analysis has yet to be proven, it can reveal process modifications and benefits towards
cleaner production and sustainable development. Often, a major environmental problem is
the inefficient use of energy. With the help of cleaner production design methodologies
engineers may be in a position of in-cooperating measures to minimise the pollution, for
instance by introducing recycling loops, by changing raw materials or by changing the
operating condition of the process, or in-cooperating treatment options. Reduction of the use
of energy is profitable for the company: in a financial as well as in an environmental point of
view.

10.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
4
T.J. Kotas, "Exergy Method of Thermal Plant Analysis", Krieger Publishing Company,
New York, United States of America, 1985.
- 5 -
2. Exergy, Environment and Economics
2.1 The Basics of Exergy
Exergy is a relatively new analysis technique in which the basis of evaluation of
thermodynamic losses follows from the Second Law of Thermodynamics. In fact, the
standard of energy quality is called exergy. The exergy balance is similar to an energy
balance but has the fundamental difference that, while the energy balance is a statement of
the law of conservation of energy, the exergy balance may be looked upon as a statement of
the law of degradation of energy. An exergy balance applied to a process or a whole plant
tells us how much of the usable work, or exergy, supplied to the system has been consumed
by the process. The loss of exergy, or irreversibility, provides a generally applicable
quantitative measure of process inefficiency. Because the exergy method is based on
thermodynamics, a review of the fundamentals of it is given here first.
The First Law: An extensive property - internal energy (U) - does exist, of which a
change in its value is defined as the difference between the heating (Q) done to the system
and the work (W) done by the system during any change of state. The change in the internal
energy (U) of the system is equal to the change in energy of the system if the system is not
in motion.
∆ ∆U E E E Q Wfinal initial= = − = −
This equation is known as the non-flow energy equation. The first law has its
limitations; it treats work and heat interactions as equivalent forms of energy in transit and
offers no indication about the possibility of a spontaneous process proceeding in a certain
direction. The second law of thermodynamics is required to establish the difference in quality
between mechanical and thermal energy and to indicate the directions of spontaneous
processes.
The Second Law: There is an extensive property of a system called entropy (S). The
entropy of an isolated system can never decrease, since in practice a system always is
irreversible. In other words, there is a production of entropy in every process. The loss is
connected to the loss of work: .4W T Slost irrev= ⋅0 ∆
The irreversible thermodynamics tells that:
∆S J Xirrev i i
i
n
= ⋅∑
where Ji are the process streams, and Xi are the associated driving forces. Which
leads to:
W T J Xlost i i
i
n
= ⋅ ⋅∑0

11.
Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
- 6 -
This indicates that the work loss, which is also called exergy loss or irreversibility of a
given process, is related to the driving forces. By decreasing these driving forces the exergy
losses of processes will also decrease; by this, the efficiency of the process will increase.
2.2 Calculating Exergy
The exergy of an amount of material is determined by the sum of its physical, chemical
and nuclear exergy. The last one will not be taken into account here.
Physical exergy is the work obtained by transferring a stream or substance via a
reversible process from the initial temperature T and pressure P tot the reference state T0
and P0:
Ex H H T S Sph = − − ⋅ −0 0 0( )
Where H is the enthalpy and S the entropy. The physical exergy has two parts, namely
a thermal and a pressure part. For a gas, the physical exergy can be calculated from:
( )ex c T T T
T
T
R T
P
P
ph p= ⋅ − − ⋅






+ ⋅ ⋅0 0
0
0
0
ln ln
With cp the specific isobaric heat capacity and R the molar gas constant. In the next
formula, for liquids and solids c is a specific heat and vm is the specific volume at T0:
( )ex c T T T
T
T
v
P
P
ph m= ⋅ − − ⋅






− ⋅0 0
0 0
ln ln
When exergy is transferred due to heat transfer, the formula of Carnot is used. This
gives the following formula on exergy transfer, in which QA is the heat transfer at
temperature T:
Ex Q
T
T
ht A= ⋅ −





1 0
Chemical exergy is the maximal amount of work available when a substance is
brought into equilibrium with the environment by processes involving heat transfer and mass
exchange only with this environment. To calculate the chemical exergy of the reference
gasses, the work for getting the components at the standard pressure from the partial
pressure of the reference state has to be determined. The following formula can be used:
ex R T
P
P
ch
part
= ⋅ ⋅0
0
ln
where Ppart is the partial pressure of the component in the reference state. To calculate
the chemical exergy of other (pure) components than the reference components the
following formula has to be used:
ex G x ex x exch i ch i
in
i
n
i ch i
out
i
n
= − − ⋅ + ⋅∑ ∑∆ 0 , ,

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Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
5
P.P.A.J. van Schijndel et al., "Exergy Analysis as a Tool for Energy Efficiency
Improvements in the Tanzanian and Zambian Industries", Eindhoven University of
Technology, Eindhoven, Netherlands, 1998.
- 7 -
If the chemical exergy of some mixture needs to be calculated one uses the following
formula:
( )ex G x ex x xch mix i ch i
in
i
n
i i i
i
n
, , ln= − − ⋅ + ⋅ ⋅∑ ∑∆ 0 γ
The activity coefficient (i equals to one for ideal solutions.5
For non-ideal solutions the
activity coefficient can be measured using the Debye-Hückel Parameter:
− =
⋅ ⋅
+ ⋅ ⋅
logγ i
i
i
A z I
a B I
2
1
A = 0.51 kg1/2
/mol1/2
for aqueous solutions at 25 EC
B = 3.287@109
kg1/2
/m@mol1/2
for aqueous solutions at 25 EC
ai = the effective diameter of the ion
I =
1
2
2
m zi i∑
As for sugar solutions, the use of the parameter mentioned above may not be
appropriate, one could estimate the activity coefficient using the boiling point rise, which is
mainly caused by the activity of the sugar as well.
2.3 Process Efficiency
As mentioned before the total exergy input, E', of a real system is always higher than
its exergy output, E'', because a certain amount of exergy is irreversibly destroyed within the
system. This amount of exergy is generally referred to as the internal exergy losses, Dint
,
directly linked to the thermodynamic irreversibilities in the system. Therefore, the total exergy
balance satisfies the relationship:
Ex Ex Dll l
= − int
There are different ways to define the exergy of a system. Fratzcher described it as
stated here:
ηex
ll
l
ext
l
Ex
Ex
D D
Ex
= = −
+
1
int
But this efficiency definition had its limitations and mistakes. It is possible that an
apparatus what, from an engineering point of view, has a poor performance does have an
excellent exergy efficiency. For example, a chemical reactor with a very low conversion rate
or a heat exchanger with very small heat duty would produce such an effect. This is,
because exergy that is not utilised by the system, but just transits through, is not taken into
account in Fratzchers formula.

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Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
6
M. Sorin et al., "Exergy Flows Analysis in Chemical Reactors", Energy Diversification
Research Laboratory, Varennes, Canada, 1998.
7
G. Wall, "Exergy and Morals", Institute of Theoretical Physics, Göteborg, Sweden,
1995.
8
G. Wall, "On Exergetics, Economics and Optimization of Technical Processes to meet
Environmental Conditions", Institute of Theoretical Physics, Göteborg, Sweden, 1997.
- 8 -
Kostenko recognised this fact first, and came up with the name transiting exergy, Extr
,
to this fraction of the exergy supplied to a system. Only part of the exergy input is consumed
by the system in order to produce new forms of utilisable exergy. On the basis of these
observations, Sorin and Brodyansky have defined a new coefficient of thermodynamic
efficiency, later named intrinsic exergy efficiency by Sorin:
ηi
p
c
ll tr
l tr
Ex
Ex
Ex Ex
Ex Ex
= =
−
−
Intrinsic exergy efficiency is the measure of the true ability of the system to produce
new exergy from a given amount of consumed exergy. However, 0i does not account for the
fact that, because of the external exergy losses, Dext
, which are determined by factors
exterior to the system itself, all of the exergy produced, Exp
, is no longer utilisable.
Therefore, an alternative exergy coefficient was introduced by Sorin, which is more
pertinent to the evaluation of practical systems performance. It is called the utilisable exergy
coefficient, 0u:
ηu
pu
c
ll ext tr u
l tr u
Ex
Ex
Ex D Ex
Ex Ex
= =
− −
−
,
,
In this formula, Expu
is the produced utilisable exergy; it constitutes part of Exp
.6
2.4 Exergy, Environment and Economics7, 8
An engineer designing or operating a system is expected to aim for the highest
possible technical efficiency at a minimum costs under the prevailing technical, economic
and legal conditions, but also with regard to ethical, ecological and social consequences. In
the world with finite natural resources and large energy demands, it becomes increasingly
important to understand the mechanisms which degrade energy and resources and to
develop systematic approaches for improving systems and thus also reducing the impact on
the environment. Exergetics combined with economics represent powerful tools for the
systematic study and optimisation of systems. Therefore, exergy analyses are needed if we
are serious in our efforts of a more equitable distribution of resources in the world and of our
concern for future generations. Exergetics offer a unique insight where losses and possible
improvements can be determined. Because it can provide this insight it is also a useful
concept in economics. In macroeconomics, exergy offers a way to evaluate the depletion of
resources and environmental destruction. In microeconomics, exergy can be combined with
cost-benefit analysis to improve the design. One could regard the system as a part of two
different environments - a physical and an economic one. The physical environment is
described by properties as pressure, temperature and chemical potential.

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9
Phil Thompson, “Energy Studies for Sugar Factories”, PD Thompson Process
Engineering, Peterborough, United Kingdom, 1999.
- 9 -
Physical
Environment
mass
energy
entropy
pressure
temperature
chemical potentials
Economic
Environment
values
constraints
information
prices
interest rates
SYSTEM
figure 2: the system and its two environments
The economic environment can be described by a set of reference prices of goods and
interest rates. Cost relations, videlicet costs as a function of physical quantities, connect
these two environments: see figure 2.
With the system embedded in the physical environment, for each component mass
and energy balances are needed to define the performance of the system, to describe the
physical behaviour of the system. If we know the cost relations, we are able to link the
physical and economic environments. In order to do so, we may link cost to exergy by
assuming a price of exergy, which we call exergy costing or thermoeconomic accounting.
Since exergy measures the physical value and costs can only be assigned to commodities of
value, exergy is a rational basis for assigning costs to the interactions that a physical system
experiences with its surrounding and to the sources of inefficiencies within it. The exergy
input is shared between output and destruction, or product and losses. Now, we are able to
form monetary balances for the total system and each component. This gives a good picture
of the monetary flows inside the total system and is a way to analyse and evaluate complex
installations economically. If a system is optimised as described, we will find the best system
due to the prevailing economic conditions and by minimising the exergy-losses, we also
minimise environmental effects.
2.5 Exergy in Sugar Factories9
The manufacture of sugar at TPC is an energy intensive process. There are two major
demands for thermal energy - heating the raw material and evaporating water. By careful
design it is possible to do a large proportion of the raw material heating in cane mills using
"waste" heat leaving the process. Similar attention to the evaporation and crystallisation
stages minimises the amount of steam needed to achieve the process objectives.
Energy is a key cost in many sugar factories, usually the 2nd or 3rd highest operating
cost after the cost of raw material. In cane mills the bagasse provides fuel but many mills
find themselves burning fossil fuels such as coal in addition to the bagasse.

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- 10 -
In some regions the energy from bagasse can be used to generate substantial
quantities of electricity for sale, in cogeneration schemes. By minimising the process steam
demand of the mill more steam is available to drive the condensing turbine of the
cogeneration system, leading to greater electricity export and hence more revenue.
As part of an energy study, management issues should also be taken into account.
Management issues can lead to significant improvements at minimal capital cost. Similarly
training of operators and engineers can be a key part of an energy improvement strategy.
Of course, technology also plays an important role, from flow meters on water
additions to the process through to evaporators for efficient heat transfer at low temperature
difference. We should also remember the utility systems - an energy efficient boiler or set of
turbines can also make a substantial improvement to fuel costs in appropriate cases.

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10
"Encyclopedia of Chemical Technology, volume 21", ibidem., p 883-903.
11
Douglas M. Considine and P.E. Glenn D. Considine, "Foods and Food Production
Encyclopedia", Van Nostrad Reinhold Company, New York, United States of America, 1982,
p 1931-1942.
12
Guilford L. Spencer and George P. Meade, "Cane Sugar Handbook", John Wiley and
Sons, New York, United States of America, 8th
ed., 1959.
- 11 -
milling
station
clarifying
station
evaporator
station
steam
boilers
vacuum
station
sugar cane
imbibition water
mixed juice clarified juice
syrup
milling
station
lime
filter press
bagasse
water steam for
stations
sugar water
water
molasses
figure 3: simple flowsheet
3. The Manufacture of Sugar10, 11, 12
3.1 Simple Flowsheet
The process of manufacturing sugar from sugarcane can be represented as a
succession of different operations namely: milling, clarifying, and thickening. The last
operations takes place in both the evaporation station and de vacuum pans. This very last
station also houses the crystallizers and centrifuges. A simple flowsheet of the sugar-factory
is shown in figure 3. A more detailed flowsheet can be seen in Appendix 2 and will be
discussed thoroughly in this chapter.

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13
Television Broadcast by ITV (Tanzania), "Azimuths - The Mauritian Sugar Industry",
United Nations Development Programme, 1999.
- 12 -
3.2 Fields and Harvesting
The TPC sugar-fields cover a total area of almost 5000 hectares. The fields are all
situated along Barabara Sukari (Sugar Road), which connects TPC with Moshi. Before the
cane is harvested it is burned. The burning is done to get rid of the leaves, which have no
use in the factory-process, and to chase off the different (sometimes dangerous) animals
living in the fields. The cane is bound and harvested manually and loaded onto road-trucks.
These trucks load their cargo onto railway-trucks on the extensive railway-system that cover
TPC land. The cane is brought to the factory with these trucks, where the amount of cane is
being weight.
3.3 Feeding and Extraction of the Juice
At the sugar factory, the cane is piled as a supply in the cane yard so that the factory,
running 24 hours a day, will always have cane to grind. The cane has to be crushed as soon
as possible, because of the possibility of inversion. This inversion, by bacteria in the cane,
causes the sucrose to turn back in glucose and fructose: an unwanted process.
After the cane is dropped of the trucks, the cane passes a leveller, which levels off the
amount of cane entering the factory per unit of time. After this, the cane passes through the
cane knives, which cut the cane into pieces of one or two decimetres length and split it up a
bit. Next, the prepared cane passes a series of mills called a milling train. The mills are
composed of massive horizontal cylinders in groups of three, one on the top and two on the
bottom in a triangle formation. There are 4 of these mills in tandem. While the bottom two
rolls are fixed, the top roll is free to move up and down. The top roll is hydraulically loaded
with a force of about 500 tonnes. These rolls turn at 2 to 5 rpm. The cane passes them with
a speed of 10 to 25 centimetres per second.
The bagasse of the first mill is transported to the next mill. Bagasse going to the final
mill is sprayed with water to extract whatever sucrose remains, the resultant juice from this
mill is then sprayed on the bagasse mat going to the third mill. Juice of the third mill is
sprayed on the bagasse of the second mill. The combination of all the juices is collected
from these first two mills. The bagasse from the last mill is burned, together with the dried
diffusion bagasse, in boilers that supply both power and steam to the factory. Normally, if the
boilers have a normal efficiency, there should be a surplus of bagasse. However, at TPC
there is a shortage of bagasse. The reasons for this fact will be discussed later in this report.
Even though TPC adds furnace-oil, it can hardly fulfil the plants energy-need. Sugar
factories working on (among others) Mauritius prove that if the energy-use is being
minimised, the surplus of steam from the bagasse can be used to generate electricity, for
commercial purposes.13
3.4 Clarification of the Juice
After leaving the mill, the sucrose is hydrolysing to glucose and fructose (inversion)
under the influence of an acid pH or a native enzyme. The first thing to do now is to stop the
inversion by raising the pH to about 7.5 and heating to nearly 100 EC to inactivate the
enzyme and stop microbiological action. Due to the low energy-efficiency, TPC is only able
to heat the flow to 90 to 95 EC during clarification.

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- 13 -
It is a lucky coincidence that the cheapest hydroxide, lime, also has the advantage that
calcium makes many insoluble salts. Sometimes phosphate is added as a flocculating agent.
The heat and high pH serve to coagulate proteins that are largely removed in clarification.
The clarified juice is dark brown. The colour is darker than raw juice because the initial
heating causes significant darkening. The clarified juice is heated to about 100 EC, before
entering the next stage of the process.
3.5 Thickening and Crystallisation
The sucrose-concentration in the juice is about 13 Brix (masspercent). The solubility of
sucrose in water is about 72 Brix, so 93 percent of the water needs to be evaporated before
crystals can start growing. This is being done using a multiple-effect evaporator. In each
succeeding effect, the vapours from the previous effect are condensed to supply the heat.
This works because each succeeding effect is operating at a lower pressure and boils at
lower temperature. The steam used is exhaust steam from the turbines driving the 2,5 MW
electrical generator. The steam has therefore already been used once and here in the
second use it is made to give fourfold duty. The evaporation is carried on to a final Brix of
about 62. The juice is called syrup after evaporation and is almost black. For the solubility of
sucrose changes rather little with temperature, the sugar must be crystallised by evaporating
water instead of by lowering the temperature. Sucrose solutions up to a supersaturation of
1.3 are quite stable. The sugar boiler evaporates water until the supersaturation is about
1.25 and then seeds the pan. The seeding consists of introducing just the right number of
powdered sugar so that, when all have grown to the desired size, the pan will be full.
Because sugar is heat-sensitive, the boiling is done under the highest practical vacuum at a
boiling point of about 65 EC.
At the end of the boiling time, the mixture of crystals and syrup, called massecuite,
must still be fluid enough to be stirred and discharged from the pan. At TPC, the boiling in
the vacuum pans still is a batch-process.
Now the massecuite is being centrifuged, to separate the mother liquor from the
crystals. The sucrose crystals are being washed, and the mother liquor, now called
molasses, is being boiled again. After boiling two first strikes, enough molasses have been
accumulated to boil a second strike. After this, a third strike is being boiled. In practice, that
is about all that one can get from cane juice. Third strike sugar, called C-sugar, is used as
seed for B-sugar (second strike sugar). The B-sugar is remelted and fed to the A-pans (1st
strike pans) as seed. The remaining molasses may contain up to 40% of sugar, but the
impurities present prevent any further formation of crystals. At this point the residue is called
blackstrap and is further treated for use in animal foodstuffs or as raw material to make
liquor.
3.6 Engines and Engineers
The raw sugar production at TPC is still fully controlled by human operators. No
process automation has taken place until now. The engineers work in three shifts of 8 hours.
Every shift the production is being recorded and samples of most process-flows and some
wastewater flows are taken, which are being analysed in the factory laboratory. Next, a daily
production-report is made. Although this production-report involves a lot of calculation, this is
also still done by hand. Using these daily production-reports, weekly reports are made and
after that monthly and yearly reports.

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14
Moses N. Kiggundu, “Managing in Organizations in Developing Countries”, Kumarian
Press, West Hartford, United Kingdom, 1989.
15
Stephen P. Robbins, "Essentials of Organizational Behavior", Prentice-Hall Inc.,
Englewood Cliffs, United States of America, 1997.
- 14 -
At TPC, the experience of the operators with computers is nil and their level of
education is rather low. Therefore, it is not to be expected or advisable that the process-
control and analysing will be computerised soon.
In contrast to this, the level of education of the higher personnel is remarkably high.
Most, if not all, of the higher personnel have completed a academic study, quite a few in
foreign countries. Unfortunately, their computer knowledge is still low, though they are all
willing to change this.
Small investment on a training programme and buying some more computers would, in
some cases, considerably cut down the time needed to complete some tasks. Per example,
the recurring calculations for daily, weekly, monthly and yearly reports could be completed in
a fraction of the time needed now, using a spreadsheet-programme. Generally, applying
computers for the higher personnel’s tasks will lessen their workload. This will cause that
they have more time to complete other, possibly new, assignments.
In addition to this, finding out the interests of the people is always beneficial to a
company. In the time that TPC was a private company, the company always was providing
their personnel with the training they would like to have. As found out in the company, the
people would like to see that changed back. Management and supervisory styles, incentives
and control systems in the organisation should be supportive and should reinforce learning
and the use of the new knowledge and behaviour for solving problems at work.
For lower personnel, learning takes place not in formal classroom settings but in
informal settings and contact with others of similar professional interests. It is important for
the employees to be motivated to share knowledge with each other. It is might be necessary
to change the incentive systems so that employees are rewarded for learning and bringing
new approaches to problem solving at work rather than to use seniority or extra-
organisational criteria for rewarding, punishing or controlling employees.
Training for strategic management tasks, however, is broader in scope, is more
intellectually demanding, and emphasises analytical and social behavioural skills. It is best
carried out away from the managers’ place of work. It does not always provide specific
solutions but articulates guidelines and provides frameworks for appropriate managerial
problem solving and decision making.14
Training of personnel is one of the (many) ways to enlarge people's jobsatisfaction. It
is proven that people who are satisfied, are more concerned with their jobs and work harder.
Next, it opens possibilities for both job-enlargement and job-rotation. Summarising,
supporting training of personnel brings a win-win situation, both for the company and the
employees.15

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- 15 -
weekly sugar production & bagging
1998/1999 season
0
250
500
750
1000
1250
1500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
production w e e k
tonne
0
250
500
750
1000
1250
1500
27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 1 2 3 4 5 6 7 8 9 10 11 12 13
calender week
tonne
sugar bagged sugar produced 5 week av. bagged 5 week av. produced
figure 4: weekly sugar production & bagging
4. The 1998/1999 Production Season
4.1 The Production
The total amount of sugar bagged during the 1998/1999 season equals 39,780 tonne,
produced out of 428,251 tonne of cane. At the factory, the sugar is packed in 50 kg bags,
which are distributed to wholesalers throughout the country. At a local - quite stable - retail
price of TSH 17,400 (US$ 25.50) per 50 kg bag of raw cane sugar, the company's turnover
totals more than TSH. 13.9 thousand million (US$ 20 million) per year.
4.2 The Main Production Problems
Due to El Niño the rain-season of 1998 was very long, this caused the season to start
two weeks later than planned. As can be seen in figure 3, the amount of sugar bagged
during each week of the season somewhat varies. The main reasons for fluctuations in the
weekly production are caused by different mill stoppages, which will be discussed next.
On January 5, the so-called Caterpillar engine broke. This engine is a diesel generator
that provides electricity for the Langasani village and the TPC offices. It took 24 hours to
repair the generator, during which the factory was stopped. Two days later one of the
rotor-blades of the turbo-alternator broke, which caused heavy vibrations in the alternator
that had to be stopped. Again, it took 24 hours to repair this turbo-alternator. Due to the lack
of electricity, the factory stopped producing during the repairment.

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cane shortages
16%
weekly maintenance
30%
holiday stoppages
4%
others
3%
processing causes
13%
technical difficulties
34%
reasons for mill stoppages
1998/1999 season
figure 5: mill stoppages
These two breakdowns were, according to the engineers, the longest of the season.
The fact that these two breakdowns - which occurred both in production week 28 - do not
show in the production-chart marks the plants time-inefficiency throughout the entire year.
The fall of production in (production-) week 7 was partly caused by a 24-hour public
holiday. Next, no cane was available at the factory. One can clearly see that production was
at its top in September and October 1998. This is a normal phenomenon, for the sucrose
content in the cane is the highest during spring.
The diminished production in week 26 and 27 was caused by the fact that TPC
stopped for christmas time.
In week 30 the first cane knife broke, which had to be repaired. Next, no cane was
available for almost 11 hours and a power-supply cable burnt (8 hours). Week 34 was
characterised by the fact that no cane was available for 9 hours and a boiler number six
water gauge leakages.
Due to heavy rainfall, the fields sometimes became very wet during the last four weeks
of the season, an harvesting of cane was not possible. Therefore the factory had to stop
from time to time because there was no cane available. The whole-season reasons for mill
stoppages are shown on the next page, in figure 4.
On the matter of the low time-efficiency, we have to say that TPC raised this efficiency
compared to previous season, when the downtime was even higher. The management
hopes to be able to raise the time-efficiency even more next season. At the end of this first
study however, the management could not explicate how the process' efficiency would be
raised.

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“Managing in Organizations in Developing Countries”, idem.
- 17 -
4.3 Remarks on the Production Season
The fact that no cane was available - which caused 16 % of the downtime - does not
mean that there was no cane to harvest. On the contrary, at the end of the season almost
22,000 tonne of cane was left on the fields, unharvested.
TPC's intended average production-time is 20 hours per day. During the 1998/1999
season, the average crushing-time was only 15.4 hours per day. At the same time, the
crushing-rate dropped from the intended 110 tonne per (crushing) hour to 107 tonne per
(crushing) hour. As shown in appendix 7, crushing the cane that was left on the fields could
have brought the company an extra sales revenue of 5 percent, yielding an extra TSH. 725
million (US$ 1 million). Next, cutting downtime and raising the crushing rate could raise the
total time efficiency with more than 19 percent, which would cause a substantial reduction of
the factories the operation-costs. It was estimated that raising the time efficiency might yield
up to TSH. 2 thousand million (US$ 3 million).
The management, chief-engineers and the new owner are aware of the fact that some
stations in the factory are extremely old and their condition is poor. Boilers 1, 2, 3, 4 and 5
per example, were installed by their manufacturer, Babcock & Wilcox Limited in 1953. In
1998, the Dutch government offered to invest US$ 15 million in order to replace the old
boilers with new ones, complying with the present standards of environmental impacts
energy- and time-efficiency. Unfortunately, TPC was not able to bring their contribution of
US$ 6 million together in time. As privatisation came in question, late 1998, The
Netherlands withdrew from the plans.
4.4 Planning the Future
The new owner of TPC, Deep River Beau Champ, launched a progressive plan for its
future. They will invest more than US$ 30 million to make the company more profitable and
reliable. Their plans include:
• raising the time-efficiency of the company, by both cutting the downtime and making
the preventive maintenance (and weekly maintenance) more efficient. Most likely, they
will start with the bottleneck of the factory: the boilers.
• raising the crushing-rate to 140 tonnes per hour, and;
• eventually raising the total amount of cane crushed to 720,000 tonnes of cane. This
will urge the new owners to purchase more land in short time notice.
As TPC was still owned by SuDeCo at the time of this research, details about the new
plans were not yet available. Considering the adroitness speaking from the plans however,
TPC seems to be in placed into very good hands with the new owner.
It must be noted that motivational problems are reaching crisis proportions in
developing countries and - unfortunately - TPC seems to be no exception to this rule.
Technological, structural and financial interventions being carried out possibly do not
contribute significantly to the development until these motivational problems are identified
and systematically addressed. Motivational problems manifest themselves in various
attitudes and behaviours including low productivity, inefficiency, corruption, industrial
sabotage, lack of will, inertia, indecision and risk-avoidance, lack of loyalty and commitment
to the organisation. Motivation is not causes by a single factor but is the result of complex
psychological, socio-cultural, economic, political and organisational processes.16

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5. Sugars™
Sugars™ is a trademark of and copyrighted by Sugars International. All rights reserved
worldwide. As, during this research, the author was an employee of TPC, the use of the
software was compliant with all terms and conditions of the licence agreement.
5.1 Introduction to Sugars™
In 1998, TPC invested more than $ 18.000 to buy and operate the computer
programme Sugars™ of Sugars International LCC. As one has to build the factory by
combining different stations himself, the usage of Sugars asks extensive knowledge of both
the factory's production process and Sugars. As the DOS based version of Sugars is not
very user-friendly, this also asks for extensive expertise on computer usage.
Sugars is a programme for calculating heat, material and colour balances and
providing simulations of processes for (beet and) cane sugar factories, regardless of the
process technique. This could help management with process decisions and operating
strategies for process optimisation.
Many mathematical relationships are used by sugars to analyse each flow stream in
the process used by a sugar factory. Calculations with Sugars provide a simulation of the
various process flows within the factory and the results give a prediction of the steam and
water consumption and the quantity and quality of the molasses and sugar. The results from
a simulation are dependent on the external flows into the factory or process, and the
performance of each station defined in the flow diagram.
5.2 Sugars™ during this project
Until the start of this research, TPC was lacking the expertise on the use of computers
needed to operate Sugars. This caused that the programme was (almost) not being used in
the factory until April 1999. During this project, Sugars was used for the first time intensively
and the engineers were trained in its use. Now, Sugars is finally being used in order to
model the factory in Moshi by the TPC engineers.
The production- and process-data used was gathered from weekly and monthly and
reports of the 1998-1999 season and mixed with actual data recorded in the first two weeks
of the survey. The season-data was not yet available at that moment. As mentioned before,
the actual production did not match the intended production. For an 'average production day'
does not exist in practice, we decided with the average data over the season.
Due the fact that the behaviour of the different unit operations were not known, the trail
and error method was often used to make the model complete and correct. After one week
of working with Sugars, the flow of the sucrose in TPC was fully modelled. The heating-flows
were not being modelled at that time. Next, due to the fact that data was not consistent,
material balances could only be calculated until the entering into the syrup tanks.
When the season-data became available, it was decided that this project would be
continued using manual calculations, as using Sugars would take too much time. In the last
week of the project the chief engineer, who is designated to work with Sugars - Mr. Assey -
was trained in its use and in the use of the flow-sheet programme 'Visio Technical'. Although
the plant was partly modelled during this project, it was decided that it was useful for Assey
to restart the modelling from scratch. He used the expertise available at that time, when he
bumped into problems. After the training, which lasted a few working days, Assey
understood the purpose of the programmes and knew how to work Sugars quite well. Assey
said that he will continue the use of Sugars after this project and try to model (and calculate)
the full plant, including the bagasse-boilers and all heat flows.

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5.3 Working with Sugars™ and Sugars™ Files
Although the programme comes with detailed directions on its use, Sugars is - as
mentioned before - not user-friendly. The manual comprises an immense quantity of
information, which is not always put together in a logical way. Achieving the ability to work
with Sugars in a satisfying way takes considerable time. Once the experience of working with
Sugars is gained, however, it can be very useful and beneficial to the company.
For someone who never worked with Sugars, reading and understanding the Sugars
files might cause some trouble. As it might be useful for further research, a brief description
of the usage of Sugars is given here. However, we have to remark that the station-numbers
in the model Assey has made later differ from the model used during this project.
Four different data files are required by Sugars to define the flow diagram of a model
and the performance of each station in the flow diagram. The four files are: a control file,
FLOWS, FLOWIN and STATIONS. If necessary a fifth file, called SUGFUGAL, is created by
Sugars for saving the input data for each centrifugal station. The control file and FLOWS file
must be created in a text editor, the other files are created by Sugars based on entries in the
FLOWS file. However, they can also be made manually, using a text editor.
First, we have to tell Sugars which files are being used. This is being done by creating
a file with the extension CNT (p.e. TPC.CNT). This file is normally copied from an other
model. The lines below the definition of the name and files are the molecular masses of the
different components and some data needed by Sugars, which need no discussion here.
As stated, we also have to create the FLOWS file, which defines the flow(s) leaving
each station. First is stated which unit the flow originates from, what kind of unit that is and
where the flow is going to and the type of flow (0 for process flow, 1 for heating flow). The
line is ended with a slash (/), but will be completed later by Sugars. For receiver number 105,
which sugar-flow is going to station 110, this line is:
105, 10, 110, 0/
After making (part of) the flows-file, one can start using Sugars itself. Sugars will ask
for a name of each station, as soon as the properties of the station are being changed for
the first time. Changing the properties of a station or flow can be done by double clicking on
the station or flow you want to change, or press the 'Enter'-key while the cursor is at that
point. In the same way, you can examine the properties of the flows entering and leaving
each station after Sugars has balanced the factory. Editing properties of flows or stations
has to be completed by pressing the 'F10'-key (Accept). If wished, external flows can be
added using the Model menu, if the station is allowed to have such flows.
For each station has their limitations, sometimes non-existing stations have to be
entered in between physical stations. Per example: separators only allow one input-flows. If
more than one flow enters a separator (which is the case for the mills), a receiver has to be
put in between.
The input and output of Sugars is being added in Appendix 4. The output is accurate
until the syrup-tanks and will sometimes be referred to in the next chapter.

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17
L. Warner Weiss, “Sugars™ for Windows - A Revolutionary Update”, Sugars
International, Englewood, United States of America, 1999.
- 20 -
5.4 Postscript17
During this practical training, Sugars International released a new, 32-bit Windows
based version of Sugars. The original program used a text-based interface that was
designed for use on IBM compatible personal computers using the DOS operating system. A
drawing was made of the process model for simulation by using a separate diagramming
program. The drawing was then used as a reference to build text files with a text editor to
describe the model for simulation by Sugars. This method worked well for users that were
familiar with personal computers, and simulations from Sugars were found to be an accurate
representation of the process. However, modern Windows based software has allowed
dramatic improvements in the user interface for computer programs and tools began to
appear that would allow integration of the drawing and model building steps.
The new version has a full graphical interface for building the factory. It seems more
flexible and user-friendly than the DOS version. In fact, Sugars has been fully integrated
with Visio Technical, the Windows based flowsheeting programme which was also supplied
with the previous version of Sugars. Models are now built using drag-and-drop techniques to
draw the flow diagram. Stencils containing shapes of stations are provided with the program
and these shapes are used to draw the flow diagram of the process. Connections are made
between shapes using a connector tool with automatic line routing and crossovers. Data for
each station and flow stream in the model is entered on dialogue screens that are displayed
by double clicking on the station shape, or flow stream. Changing a model, after it is built, is
done by simply revising the flow diagram and/or modifying the performance data for any
station. All of the data for a model is stored in a Microsoft Access database that can be
addressed by other programs. Heat, material and colour balances are quickly obtained from
simulations of the model to predict the performance results for the process. A revenue
screen shows the net process revenues generated by the process to assist with financial
decisions.
Summarising, the new Sugars for Windows computer program seems to be a major
upgrade. Due to the fact that TPC already owns the DOS version of Sugars, a discount will
be offered. Although the investment will again be considerable (some US$ 2,000), it is
sensible to think carefully about purchasing the upgrade. The new, intuitive interface will
make the modelling of the plant much easier and possible adaptations can be done in a
fraction of the time used working with the old version.

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6. Material and Heat Balances
6.1 System Boundaries and Assumptions
Material balances were being calculated using the flowsheet, which is added in
Appendix 2. Thus, the process involved in the survey starts when the cane enters the
factory, until it leaves the factory bagged.
As stated before, both manual and computerized calculations were used. The
calculations made with Sugars might slightly differ from the calculations that were made
manually, for new data was available when the last calculations were done. As it can be very
useful to be able to compare the calculations made with Sugars and the manual calculations
directly, the manual calculations use one hour as unit of time, just as Sugars does.
As can be seen in the appendix, it was chosen to presume that there was no spilling of
material and/or moisture after the clarifiers. This was done due to the fact that the system is
mainly closed after the mills (except for the vacuum filter). Although this assumption is
undoubtedly wrong, the data supplied gave no other opportunity to do so. The total
discrepancy in the amount of sugar for each station varies up to 3.03 percent. The fact that
the discrepancies in the amount of other materials were sometimes very high was
considered subordinate.
The reference state (environment) was chosen as having a average temperature of 25
EC (298.15 K) and a pressure of 1000 mbar (100 kPa). Although little information about the
steam-flows was available, it was tried to calculate the enthalpy-balance making a large
number of assumptions. However, it was found that the data concerning the steam-flows
often was obviously wrong. Therefore, though it was possible to calculate the enthalpy-
balance over the sugar-flows, it was impossible to make proper assumptions to calculate the
energy lost in each station. The problems experienced when trying to get proper enthalpy-
balances, are discussed in chapter 6.3.
All material-flows in this chapter have one (1) hour as unit of time, unless stated
otherwise. All material and heat balances are added in Appendix 6, and will be discussed
briefly below.
6.2 Material Balance Total System
Because of the fact that both the properties and the quantities of all in- and outgoing
flows - except for the water-usage - were known for TPC, first the total material-balance was
calculated. The fact that the total losses of 'other' components were some 17.5 percent
substantiated our later finding of the big discrepancy in the 'other' components material
balances. As can be seen, some 2.7 percent (0.37 tonne per hour) of the sugar is lost during
the process. This adds up to a total sucrose-loss of more than 1450 tonne per year.
Theoretically, if this could fully be converted into bagged sugar, this would yield some TSH.
500 million (US$ 700,000) extra per year. Figure 6 shows where the sucrose losses occur.
The masses named in this figure are the sucrose-masses of each flow, not the total masses.

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sugar cane
54302 tonne
100.00 %
mixed juice
47335 tonne
87.17 %
bagasse
6837 tonne
12.58 %
clarified juice
46891 tonne
86.35 %
filter cake
444 tonne
0.82 %
syrup
45901 tonne
87.41 %
production
39660 tonne
87.41 %
other losses
989 tonne
1.82 %
other losses
138 tonne
0.25 %
other losses
338 tonne
0.62 %
bagged
39422 tonne
87.41 %
other losses
238 tonne
0.44 %
final molasses
5903 tonne
10.87 %
figure 6: sucrose losses in the process
6.3 Mass Balance Stations
- milling station
Each mill separates its respective flow into bagasse and a juice. The bagasse leaving
each mill contains approximately 32.85 percent of the water, all the fibre and 43.40 percent
of the sucrose and other components of the incoming flow. The cane enters the first mill at
ambient temperature, water is added to the fourth mill at a temperature of 70 EC. This water
is heated with heath from the 3rd
evaporator. For both quality and quantity for each flow in
the milling station was known, the mass-balance could be calculated exact. It was calculated
that a considerable amount of mass, some seven percent, was lost in the milling station.
Some of this mass probably was lost after weighing the cane before entering into the actual
milling station, as a lot of cane lies on the ground of the cane yard.

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18
J.H.J. Hulskotte and A.J.C.M. Matthijsen, "Produktie van Suiker", SPIN, The Hague,
The Netherlands, 1992 (in Dutch).
- 23 -
As calculated with Sugars the outgoing temperature of the mixed juice is 31.9 EC and
that of the bagasse is 62.6 EC. The evaporation of water however, causes that the true
temperatures are 26 and some 53 EC respectively.
- clarifying station
A number of assumptions had to be adopted before being able to calculate the
material-balance over the clarifying station. First, as the amount of water added in the
vacuum-filters was not known, this was not taken into account. Also, it is presumed that the
lime consists out of pure, hydrated lime and does not contain contaminations. The mass-
percentage of the lime in the filtercake and clarified juice is the same. As can be seen, a
considerable amount of water (3 percent) gets lost in the clarifying station.
- evaporator station
In the evaporator-station, a large amount of water is removed. This causes a total
boiling-point rise of 4.5 EC. The temperature of the vapours leaving the last effect is probably
not right, as will be pointed out later, and is estimated to be some 85.3 EC. The assumption
that the amount of water is related directly to the true boiling temperature of the juice, it is
possible to estimate the amount of water evaporated in each effect.
- vacuum pans and centrifuges
The calculations for both the vacuum pans and centrifuges are based on assumptions
which were discussed before. The amount of (A) sugar produced per hour is 10 tonne. Fact
is, that error might occur in the calculations over the vacuum pans and centrifuges due to the
fact that the possibility of supersaturation of the sugar-flow was not taken into account.
Supersaturation causes the fact that brix can be over 100 percent, which was neglected
here.
6.4 Enthalpy Balance Total System
The total energy-consumption of TPC is some 64,8 GJ per tonne dry sugar produced,
which is slightly more than ten times the energy of per tonne sugar. By comparison with
sugar factories in the developed countries, this is a enormous energy consumption. The
average energy use in the Dutch sugar factories - which produce white (refined) sugar - per
example, total some 10.4 GJ per tonne sugar bagged18
. This is more than six times less
energy than TPC uses.
Over the process, the total energy efficiency is some 67 percent. However we can also
define a 'useful enthalpy efficiency':
η∆
∆
∆
H useful
sales
in
H
H
,
∑
∑
⋅100%
This useful enthalpy efficiency might seem a fiddling fact, but it will be interesting to
compare this efficiency with the different exergy-efficiencies. This useful enthalpy efficiency
is very low at TPC:only 3.4 percent, as has been calculated in the appendix.

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6.5 Enthalpy Balance Stations
As said before, calculating the enthalpy of the flows in each station caused no trouble
for the sugar-streams. These can be examined in appendix 6, together with the material-
balances. As mentioned, due to little and incorrect data over the steam-flows, calculating this
enthalpy and thus the energy-efficiency of each unit was impossible. This chapter points out
the main problems experienced over the different units and the methods tried in order to get
estimations for the enthalpy balance.
- Bagasse and Supersaturated Steam
The bagasse furnaces (number 1 to 5) at TPC are of the Ward Single-Pass type,
combined with a sterling type boiler. These were, when installed, the most modern boilers
available (Cane Sugar Handbook, 1959). Nowadays they do not meet the standards of
technology in any way. The calculated efficiency of 73 percent seems quite reasonable, but
we have to remark that this is the target for the boilers, which is often not reached. Mostly,
the real bagasse-burning temperature is lower than the requested 1200 EC, and the steam-
pressure and temperature are both lower than is wanted. During the research, pressures
below 11 bar absolute and temperatures below 400 EC were often recorded. This yields a
boiler efficiency which is more than six percent lower. It is expected that the most likely
reason for the disfunctioning of the boilers is that the amount of air fed to the combustion
chambers is too low. This results in a non-complete combustion, which causes the problems
discusses before.
Allthough it will not heighten the efficiency of the boilers, the total energy of the steam
leaving the boilers could also be heightened by drying the bagasse preliminary to the
combustion. The drying, which could be done with the latent heat of the vacuum pans, would
raise the caloric value of the bagasse considerably.
- Exhaust Steam and Measuring Equipment
After passing the plants 2.5 MW generator, the water is fed to nullify the
supersaturation of the steam and raise the amount of steam. The equipment installed to
measure the temperature and pressure of the exhaust steam after the water was fed proved
to be wrong. Steam tables learn that the recorded temperature and pressure of 110.18 EC
and 157.51 kPa would yield water. The saturation-pressure at the recorded temperature is
144.14 kPa, and the saturation-temperature at the recorded pressure is 112.85 EC. The
same problem occurred at the evaporator-station and vacuum pans. In order to get the
enthalpy-balance right it was tried both to rely on the pressure and on the temperature, but
both were proven to be wrong. In neither way it was possible to make the enthalpy-balance
correct, without making to much assumptions. For the correctness of all pressures and
temperatures involving the heating-flows were doubtful, one could not know or estimate what
the enthalpy of each separate flow was, thus leaving no possibility of calculating the energy-
efficiency.

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7. Exergy Use in Sugar Production
7.1 Total Exergy Use at TPC
As the enthalpy-balances could not be completed for most stations, calculating the
exergy-use over the stations is a impossible task. Nevertheless, the total exergy-use could
be calculated, which can be seen in appendix 6. Due to the fact that insufficient information
was available, only the Fratzcher Efficiency for the exergy-use could be calculated.
Of course the presumption that activity coefficients are equal to one all over the
process is wrong, but it at least gives a approximation of the true values - that is, if all
components are mixed. When we decide to assume that this water is not mixed with the
other components in cane, we find an efficiency of more than 30 percent. However - as
discussed in chapter 2.3 - this method for calculating the Fratzcher exergy-efficiency is
somewhat outdated and supplies a (too) flattering result. The true efficiencies, as defined by
Sorin, will lead to much more realistic and much lower values.
7.2 Enthalpy and Exergy
Although the exergy-losses are probably far more than two times as high as the
enthalpy-losses, it is remarkable that almost all of the exergy leaves the factory in sellable
products. More than 95 percent of the exergy output is being sold, either as sugar or
molasses.
Although we do not have calculations to substantiate this ideas, it is generally thought
that the biggest enthalpy-losses and, not less important, exergy-use occur in the boilers and
evaporators. Huge leaps in the Gibbs-energy take place here, which is a mainspring for
exergy-use. Lowering the Gibbs-leaps and preventing enthalpy-losses are the main
contingences for minimising the exergy-use, environmental impacts and operation-costs.

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19
Maarten Hoenders, "Cleaner Production in Tanzania and Exergy Analysis as Method
for Process Modifications", Eindhoven University of Technology, Eindhoven, The
Netherlands, 1998.
20
Adolf Mascarenhas, “Environmental Issues and Poverty Alleviation in Tanzania”,
Network for Research on Poverty Alleviation, Dar es Salaam, Tanzania, 1994.
- 26 -
8. Cleaner Production
8.1 Environmental Issues in Developing Countries.
The environment has been a matter of concern in industrialised countries. National
policies, environmental standards and guidelines have been accepted for many years, and
even have been sharpened in the last decade, as a result of global environmental
consciousness. Companies nowadays realise that environmental care is required to survive
in global competitive markets.
Developing countries, like Tanzania, are industrialising fast and go through rapid
economic growth. As industrialisation is getting off, the lessons learnt by the industrialised
countries can be applied to prevent mistakes.19
For developing countries, the issue of
poverty cannot be confined to finances only. Africa has taken too much from it land as well.
It has overdrawn from its environmental accounts, and the result for much of Africa has been
environmental bankruptcy.
Generally the state of the environment in Tanzania is presented in terms of alarm and
concern. It is impossible not to be struck by the fact that certain processes in the
environment cause loss of wealth, misery, illness and even death.
Considering four important environmental parameters can generally approach the
whole issue of environment and poverty in Tanzania. These parameters are: population,
deforestation, degradation and the use of resources. All four parameters must be looked at
dynamically as they help to give some reality of the link between environment and poverty.
Summarising, concern for the environment used to be a luxury only wealthy western
countries could afford, but in recent years environmentalism has become an increasingly
global phenomenon. It is futile to attempt to deal with (international) environmental problems
without a broader perspective that encompasses the factors underlying world poverty and
international inequality.20
8.2 Environmental Awareness in Tanzania
Nowadays, more and more people in Tanzania, as well as the government, start to
recognise that the environment is very vulnerable and that there is need to protect it from
pollution as much as possible. As environmental awareness is increasing very fast in
Tanzania, a progressive environmental programme will grow goodwill among the public.
Factories not satisfying the publics need for a healthy environment may even end up being
boycotted by the people, both on the side of the market and the labour force. Therefore, a
well-organised environmental programme will become indispensable in the future.
In December 1997, the Tanzanian government decided to revise the Tanzanian
environmental laws as soon as practically possible. Fines, imposed on companies not
complying with these laws will become much higher than they are at the present moment.

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21
Interview with Prof. C. Migiro, Cleaner Production Center of Tanzania, Dar es Salaam.
22
Alexander P. Economopoulos, “Assesssment of Sources of Air, Water, and Land
Pollution. A Guide to Rapit Source Inventory Techniques and Their Use in Formulationg
Environmental Control Strategies”, World Health Organization, Geneva, Switzerland, 1993.
- 27 -
Although the government's new environmental policy is not common knowledge yet,
factories should start examining their waste-flows to be aware of their possible problems,
before the new laws are being imposed. This urges the companies to hire the knowledge
from outside the company or educate some of the personnel on environmental issues.
During the first months of 1999, the Cleaner Production Centre of Tanzania (CPCT)
launched a training programme for companies willing to be ahead of the law. TPC was one
of companies who were offered to join the programme first.21
As TPC did not have a
environmental programme and is not intended to start one in a short period of time, they did
not participated in this training programme. However, both the TPC management and
engineers do recognise the fact that environmental issues are getting much more important
nowadays and investments to reduce the pollution are inevitable. The opportunity of being
trained at the Cleaner Production Centre seems very inviting to the (chief) engineers.
However, the management feels that the company is not polluting in such quantities that an
environmental programme is needed. They admit that the emissions from the boilers are
contaminated, but emphasise that with the planned replacement of the boilers, this will be
solved.
8.3 Environmental Pollution in Sugar Factories22
The average pollution of the worlds sugar(cane) factories, according to the World
Health Organization are given in table 2 for air pollution and table 3 for waste water pollution.
Table 2: Air Emissions
combusted material
TSP
kg/U†
SO2
kg/U
NOx
kg/U
CO
kg/U
VOC
kg/U
fuel oil 0.28 20.00 S‡
2.84 0.71 0.035
bagasse 8.00 0.00 0.60 n/a n/a
coffee husks 4.40 0.015 0.34 13.00 0.85
†
unit (U) is tonne combusted material
‡
S indicates that the figure should be taken from the quantity of sulphur in the
combusted material
Table 3: Water Emissions
material
TSS
kg/U†
BOD5
kg/U
Volume
m3
/U
waste water 75.00 2.90 3-48
†
unit (U) is tonne sugar produced

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23
"Produktie van Suiker", idem.
- 28 -
Appendix 8 shows the proposed limits for emission sources as drafted by the
Tanzanian Bureau of Standards and the National Environmental Management Council,
which probably will be basis for the new Tanzanian Environmental Laws. Of course, we have
to note that environmental laws will become more and more strict through time. And that it is
likely that the final laws will be even more rigid.
As can be seen from the mass and the caloric value of the bagasse, TPC burns far
more than 50 MW of bagasse at the moment. Next to this, it also burns more than 5 MW of
furnace oil, which implies that all the limits in the first table in appendix 8 have to be looked
after.
8.4 Environmental Pollution at TPC
Although no samples of the thick smoke leaving the TPC's chimney were taken, the
colour of the smoke tells that combustion is not complete. Consequently, carbon monoxide
and black smoke are produced in the combustion chambers. Due to the fact that the smoke
is not treated to remove polluting substances, it is hardly to doubt that the emissions are
complying to the standards at the moment. Fact is, that the boilers are more than 45 years
old now, and need to be replaced. It is expected that doing so will be one of the first
concerns of the new owner.
The wastewater leaving the factory also is not treated intensively. It passes through a
sedimation-tank before being used as irrigation-water in the fields. The wastewater
therefore, is not dumped directly. In spite of the (re)use of the wastewater, possible
contaminations do flow into the global environment in the end. If the wastewater is
contaminated, TPC is polluting its own land, which might cause accumulation of
contaminations in both the soil and the sugar-cane. In our point of view, the fact that the
wastewater does not flow into surface-water directly should not be used as an excuse for not
examining the wastewater critically.
Unfortunately, the change of weather made it impossible to get sound samples of the
wastewater. Due to heavy rains the amount of water leaving the factory was much higher
than normal. Next, due to soil erosion, the water was very contaminated with mud. However,
again it is to doubt that the emissions are complying to the standards.
During every shift, the water in the gullies is being measured in order to qualify the
amount of sugar that it contains. Regrettably, these amounts are not being quantified until
now. For the qualification rests on experience, it was not possible to do experiments in order
to quantify the amount of sugar in the wastewater. As the wastewater can be qualified on
sugar-content, suspicion rises that other contaminations can also be considerable.
Moreover, by looking at the water leaving the factory, we can obviously see that the
wastewater contains suspended particles and some liquid fuels or oils. Furthermore, the
wastewater possibly is entrusted with organic compounds23
.
Appendix 9 shows the estimated figures about the pollutant production per hour for
TPC. These figures are not measured but give an indication about the presence of
environmental harmful components in its waste-streams. Due to the fact that the total
quantity of the exhaust gasses nor waste water streams are measured, it is hard to draw a
conclusion from the figures. Therefor they are only mentioned indicative, however in our
opinion it is time to take a critical look at the waste-flows leaving the factory. The exact use
of the waste-streams or the fact that a solution for a problem might be at hand should not be
a reason to deny possible pollution or to postpone the forming of a environmental group.

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9. Conclusion and Discussion
Though the research done at TPC proved to be very useful, both for the student and
the company, not all the intended work was done. The main reason for this is the bad
condition in which some measuring equipment is. Especially the equipment involved in the
heating-flows is in abominable condition. The management seems to think about the
heating-flows as a second-class flow. This is, however, understandable as too little money
was available to take good care of all the units in the factory. Nevertheless, as more money
might come available through Deep River Beau Champ limited, TPC should think about
installing proper measuring equipment - and not only in the sugar-flow. Only if proper
measuring equipment is installed all over the factory, a good energy- and exergy-study can
be conducted. These studies could help the company minimising energy-use, environmental
impact and production-costs.
Due to the bad condition or sometimes absence of measuring-equipment, the collected
data is not reliable or had to be estimated. This causes inaccurate calculations, which could
possibly result in erroneous process-adaptions. According to the management, the pressing
difficulties of TPC at the moment are:
• lack of money
• questionable (preventive) maintenance
• considerable extra downtime
• energy inefficiency of the boilers
It looks like the last three problems can be carried back to the first problem. Lack of
money causes a omission of the weekly preventive maintenance and the delay of installation
of new apparatuses, like the new boilers. Insufficient preventive maintenance probably
causes a big part of the downtime. Next, the absence of materials to repair broken
equipment brings delay in the repairment as well as the possibility for fraud and bribes. The
new investor should try hard to deal with the mentioned problems as soon as possible.
Taking good care of them would be an investment that pays back in a very short time.
TPC could have an extra amount of sales worth some TSH. 5 thousand million (US$ 7
million), if extra cane was planted. This, when the total number of crushing days would
remain the same as the last few years, and meanwhile the factories efficiency could be
raised up to the normal 83.33 percent. However, preventive maintenance only will probably
not be enough to achieve these goals, it also asks involvement and dedication of the floor-
engineers. All the same, proper preventive maintenance will help raising the time-efficiency,
and meanwhile lowering the total upkeep-costs.
Furthermore, the energy- (and exergy) use of the factory could be cut in a great deal.
Replacement of the boiler will be a big leap in the right direction. More - much less obvious
but profitable - recommendations can possibly be done after a continued study.

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10. Recommendations
10.1 Condition of Engines and Engineers
TPC should have a close look at all of the installed equipment and aks themselves
time after time if the equipment is working properly and, if not, what the cause of the
malfunction is. Necessary equipment should be (re-)installed, replaced and well kept. This is
the only way to improve the process-control, which will lead to more a more time and cost
efficient process. Next to this - in order to raise the efficiency - the management should take
a close look to the level of training of both the operators and engineers. Where it is possible,
required and desired, training should take place.
10.2 Care for the Environment
Although the management does not recognise the need to start an environmental
programme at the moment, the fast growing environmental awareness will urge TPC to do
so in a short amount of time. Next to this, it is expected that the programme will be inevitable
in order to comply with the new environmental regulations and to avoid paying high penalties
in the very near future.
The environmental programme could consist of hiring external specialists on
environmental issues, but establishing a small environmental team seems a better option. As
mentioned before, in chapter 3.5, the workload of the engineers can - in some cases - be
reduced, yielding time for tasks like this. The team should consist out of a number of
superintendents and/or chief-engineers, from different parts of the company. At least some
of these engineers should go though an environmental training programme, to teach their
colleagues afterward. As environmental laws become more rigorous through the years,
retraining will be required from time to time.
After the establishment of the environmental team, measurements must be done, to
both qualify and quantify the amount of waste that the factory is producing. Afterward, the
team should discuss the possibilities to reduce the pollution and deliberate the reduction of
pollution compared to the investment needed. While doing this, they always have to take into
account that the laws might become more strict after an unknown time.
10.3 Further Research
Further investigation is needed in order to complete the exergy analysis at TPC. This
study was, as planned, mainly conducted while the plant was having its yearly maintenance.
For next studies will probably need more data of the different unit-operations, it is advisable
that further research takes place within the harvesting/production season. Therefor, it is
recommended to avoid the period from half of March until the end of May.
Next, it is recommended to bring good measuring equipment. As mentioned before,
some of TPC's measuring equipment is not working or does not seem to work accurate.
However, for this preliminary study was undertaken just before and in maintenance, new
equipment might be already installed.

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Preliminary Study for Exergetic Analysis on Sugar Production in Tanzania Practical Training
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11. Literature
Next to the literature named before in this report, I read some more articles about sugar,
sugar production and management in developing countries. All the literature I used, either
directly in this report or indirectly, is mentioned below.
James E. Austin, “Managing in Developing Countries”, Collier MacMillan Publishers, London,
United Kingdom, 1990.
Douglas M. Considine and P.E. Glenn D. Considine, "Foods and Food Production
Encyclopedia", Van Nostrad Reinhold Company, New York, United States of America, 1982.
Alexander P. Economopoulos, “Assesssment of Sources of Air, Water, and Land Pollution. A
Guide to Rapit Source Inventory Techniques and Their Use in Formulationg Environmental
Control Strategies”, World Health Organization, Geneva, Switzerland, 1993.
Maarten Hoenders, "Cleaner Production in Tanzania and Exergy Analysis as Method for
Process Modifications", Eindhoven University of Technology, Eindhoven, The Netherlands,
1998.
J.H.J. Hulskotte and A.J.C.M. Matthijsen, "Produktie van Suiker", SPIN, The Hague, The
Netherlands, 1992 (in Dutch).
J.H.Y. Katima, "Unit Operations Involving Heat and Mass Transfer", University of Dar es
Salaam, Dar es Salaam, Tanzania, 1996.
Kirk-Othmer, "Encyclopedia of Chemical Technology, volume 21", John Wiley & Sons, New
York, United States of America, 3rd
ed, 1983.
Moses N. Kiggundu, “Managing in Organizations in Developing Countries”, Kumarian Press,
West Hartford, United Kingdom, 1989.
T.J. Kotas, "Exergy Method of Thermal Plant Analysis", Krieger Publishing Company, United
States of America, 1985.
Adolf Mascarenhas, “Environmental Issues and Poverty Alleviation in Tanzania”, Network for
Research on Poverty Alleviation, Dar es Salaam, Tanzania, 1994.
J.P. MMbaga, "Practical Training Report Kilombero Sugar Company", University of Dar Es
Salaam, Dar Es Salaam, Tanzania, 1985.
Charles G.M. Perk, “The Manufacture Of Sugar From Sugarcane”, Sugar Milling Institute
and the University of Natal, Pretoria, South Africa, 1973.
Stephen P. Robbins, “Essentials of Organizational Behaviour”, Prentice-Hall Inc., Englewood
Cliffs, United States of America, 1997.

37.
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P.P.A.J. van Schijndel et al., "Exergy Analysis as a Tool for Energy Efficiency Improvements
in the Tanzanian and Zambian Industries", Eindhoven University of Technology, Eindhoven,
Netherlands, 1998.
M. Sorin et al., "Exergy Flows Analysis in Chemical Reactors", Energy Diversification
Research Laboratory, Varennes, Canada, 1998.
Guilford L. Spencer and George P. Meade, "Cane Sugar Handbook", John Wiley and Sons,
New York, United States of America, 8th
ed., 1959.
Phil Thompson, “Energy Studies for Sugar Factories”, PD Thompson Process Engineering,
Peterborough, United Kingdom, 1999.
L. Warner Weiss, “Sugars™ for Windows - A Revolutionary Update”, Sugars International,
Englewood, United States of America, 1999.
G. Wall, "Exergy and Morals", Institute of Theoretical Physics, Göteborg, Sweden, 1995.
G. Wall, "On exergetics, Economics and Optimization of Technical Processes to meet
Environmental Conditions", Institute of Theoretical Physics, Göteborg, Sweden, 1997.

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12. List of Abbreviations
Text:
Brix = Mass Percentage of Solids
CMT = Centre for Environmental Technology
EvEn = Environmental Engineering
Nuffic = Netherlands Organisation for International Cooperation in Higher Education
rpm = rounds per minute
Sudeco = Sugar Development Co-operation
TANU = Tanganyikan African National Union
TPC = Taganyika Planting Company Sugar Estate
TSH = Tanzanian Shilling
TSP = Total Solid Particles
TSS = Total Suspended Solids
TUE = Eindhoven University of Technology
UDSM = University of Dar es Salaam
US$ = United States Dollars
VOC = Volatile Organic Components
Formulas:
) = Change
a = diameter
c = heat capacity
D = Exergy losses
E = Internal energy, for a system not in motion
Ex = Exergy
ex = Exergetic coefficient
G = Gibbs energy
H = Enthalpy
J = Process stream
P = Pressure
Q = Heat
S = Entropy
T = Temperature
)U = Internal energy
V = Volume
W = Work
X = Driving Force
x = Molar fraction
z = Charge
( = Activity coefficient
0 = Efficiency

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Subscripts:
0 = Reference state
A = Transfer in Carnot Cycle
ch = Chemical
ex = Exergetic
i = Component indentifier
i = Intrinsic (only in 0i)
initial = Input
irrev = Irreversible
final = Output
ht = Heat transfer
lost = Lost/perished
m = Molar
p = Isobaric
part = Partial
ph = Physical
u = Utilisable
Superscripts:
c = Consumed
ext = External
in = Input
int = Internal
l = Input
ll = Output
out = Output
p = Produced
pu = Produced utilisable
tr = Transiting
u = Utilisable

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A. Appendices
A.1 Contact List
TPC Limited Mr. M. Sadiki
General Manager
P.O Box 93
Moshi
Tanzania
G: +255 55 543 89 / 90 / 91
fax: +255 55 533 91
e-mail: tpc@eoltz.com
other contacts: R.R. Kahangwa
Factory Manager
S.V. Gambalela
Chief Process Superintendent
B.M.M. Magoma
Deputy Chief Process Superintendent
M.M. Makundi
Chief Engineer (factory)
G.E.J.M. Assey
Chemical Engineer (laboratory)
Cleaner Production
Centre of Tanzania
Prof. C. Migiro
Managing Director
P.O. Box 23235
Dar Es Salaam
Tanzania
G: +255 51 66 89 79 / 81 05
fax: +255 51 66 81 47
e-mail: cpct@ud.co.tz
Sugars International L. Warner Weiss
Sugars International LLC
30 Glenmoor Drive
Englewood, CO 80110
United States of America
G: +1 303 761 84 42
fax: +1 303 761 80 48
e-mail: sugars@sugarsintl.com
web-site: http://www.sugarsintl.com/sugars
ftp-site: ftp.sugarsintl.com/FTP/sugars
other contacts: Phil Thompson (Europe)
G: +44 17 80 783 329
e-mail: phil@pdt.u-net.com
Nico Stolz (Southern Africa)
G: +27 13 790 02 64
E-mail: spies@cis.co.za

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Visio Corporation
Visio Corporation
2211 Elliott Avenue
Seattle, WA 98121-169
United States of America
G: +1 206 956 60 00
fax: +1 206 956 60 01
web-site: http://www.visio.com
United Nations Industrial
Development
Organisation (UNIDO)
Hugo J. Dekkers
Programme Officer
Matasalamat Mansion
Zanaki / Samora Avenue
P.O. Box 9182
Dar Es Salaam, Tanzania
G: + 255 51 112527
fax: + 255 51 118114
e-mail: hugo.dekkers@undp.org

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1st mill bagasse 2nd mill bagasse 3rd mill bagasse
1st
mill
3rd mill juice
4th mill juice
imbibition water (hot)
mixed juice
tank
2nd
mill
3rd
mill
4th
mill
sugarcane
liming
tank
2nd heating
clarifier
scums
pressjuice water
filterpress
preheater
1st heating
1st
evaporator
2nd
evaporator
3rd
evaporator
4th
evaporator
vacuum filter
syrup tank
syrup
A molasses tank B molasses tankremelt tank
C vacuum pansB vacuum pansA vacuum pans
A
crystallizer
B
crystallizer
C
crystallizerA centrifugal
B
centrifugal C
centrifugal
hot water
air sugar drier
wet A sugar
sugar
bins
commercial
sugar
warehouse
B sugar
B sugar
melter
hot water
(B) sugar
melter
final molasses tanks
finalmolasses
hot water
C sugar
C magma
mingler
hot water
C magma
tank
boilers
bagasse
water
turboalternator
high pressure steam
exhauststeam
hot water
to imbimitionwater heater
conde
nser
water
to furrow
condensers
for each pan
water
to furrow
commercial sugar
A.2 Process Flow Chart of TPC