17WC:
BRAND NEW WATER TREATMENT SYSTEM FOR AN
EXISTING POWER PLANT. A WATER SAVING PROJECT
Mr. Karim Azat & Mr. Juan de Beristain
57951

August 30 – September 4, 2015 | San
Diego California
 Thermoelectric power plant with two combined cycles 740 MWe
 Water source: 18 deep wells with variable sulfate (SO4
-2) concentration
 Cooling towers typical make-up with 350 ppm sulfate = 760 m3/h
 Blow-down must comply with regulation of maximum 1,000 ppm sulfate
 During drought condition wells´ sulfate concentration increases
 As concentration increases, i.e. 550 ppm sulfate, make-up water must be
increased up to 1,140 m3/h to comply with blowdown quality requirement
 At this level water from wells is not enough and a solution must be found.
BACKGROUND

August 30 – September 4, 2015 | San
Diego California
BACKGROUND
Evaporation: ~ 456 m3/h
Blow-Down: ~ 684 m3/h
Total Make-Up: ~ 1140 m3/h
Insufficient water from wells

August 30 – September 4, 2015 | San
Diego California
 Initially implemented solutions
 Increase water supply from external wells
 Blow-down treatment: salinity reduction to allow disposal
 Selected solution, Make-up treatment
 Salinity reduction to increase concentration cycles & reduce blow-
down
ON THE WAY TO THE SOLUTION

August 30 – September 4, 2015 | San
Diego California
EXPECTED SCENARIO
Evaporation: ~ 456 m3/h
Blow-down: ~ 50 m3/h
RO Reject: ~ 60 m3/h
Total consumption: ~ 566 m3/h
Self-sufficient water supply.
Blow Down
Reduction 92,7%
Water Reduction
47,4%

August 30 – September 4, 2015 | San
Diego California
 Feed both cooling towers with permeate water to reduce blow-
down to a minimum
 Reverse Osmosis as water treatment technology
 Permeate water 540 m3/h
 60 m3/h of concentrate stream (maximum disposal capacity)
 Inlet flow 600 m3/h 90% recovery rate
 Permeate water conductivity less than 50 μS/cm
 Permeate water sulfate content less than 20 ppm
SOLUTION DESCRIPTION

August 30 – September 4, 2015 | San
Diego California
CHALLENGES & SOLUTIONS
 High recovery rate
 Reduced lay-out
 High flexibility & variable quality of water supply
 No new chemicals nor CIP procedures allowed inside the
complex
 Bonus challenge: replace boiler water treatment plant

August 30 – September 4, 2015 | San
Diego California
CHALLENGES & SOLUTIONS: HIGH
RECOVERY RATE REQUIRED
 90% global recovery rate on cooling water production system
 First & second stage at 80% recovery rate, third stage at 50%
recovery rate
 Third stage = Sacrifice stage
 Scaling potential bounded to the third stage
 Strict monitoring of critical parameters to trigger preventive CIP
procedures at the third stage

August 30 – September 4, 2015 | San
Diego California
CHALLENGES & SOLUTIONS: LAY-OUT
 New plant to be installed in the same area where the previous boiler
water plant used to be (Ion Exchange, 30 m3/h capacity, ~ 500 m2 useful area)
 N+1 redundancy required for all critical components (even RO trains)
 Future expansion for the new boiler water plant (+50%)
How was this achieved?
 Horizontal filters
 Operating platforms on the top of RO skids
 Intensive use of pipe trenches

August 30 – September 4, 2015 | San
Diego California
CHALLENGES & SOLUTIONS: HIGH FLEXIBILITY
& VARIABLE QUALITY OF WATER SUPPLY
 Make-up water demand is variable around the year
 Source water quality is expected to continue to change, so plant must be
able to operate under different salinity conditions
How was this achieved?
 Operating points (25%, 50%, 75%, 100%)
 Able to operate at up to 50% more pressure, from low to high pressure membranes
 Pumping groups & other components designed to face such demanding conditions

August 30 – September 4, 2015 | San
Diego California
 15 m3/h @ 18 MΩcm
 < 3 ppb Silica
 100% availability
 Zero chemical consumption
How was this achieved?
 Second pass RO fed from cooling water treatment plant (first pass)
 EDI as polisher
 Two trains of 15 m3/h each. Design allows to operate both trains simultaneously
 Inline Silica measurement at critical points
REPLACE IX BOILER WATER TREATMENT
PLANT WITH RO+EDI

August 30 – September 4, 2015 | San
Diego California
RESULTS & SUMMARY
Cooling Water Treatment Plant
 Product < 20 µS/cm
 Lack of space: SOLVED
 High recovery rate (90%)
 Low OPEX (40% lower than expected)
Cooling Towers System
 No pH correction (H2SO4) at the cooling towers
 No biocides
 No anti-scalant
And what about
water saving…?

August 30 – September 4, 2015 | San
Diego California
RESULTS & SUMMARY: COOLING WATER SYSTEM
Make Up = 350 m3/hr
Blow Down = 175 m3/hr

August 30 – September 4, 2015 | San
Diego California
RESULTS & SUMMARY: COOLING WATER SYSTEM
Make Up = 175 m3/hr
Blow Down = 0 m3/hr
50% reduction

August 30 – September 4, 2015 | San
Diego California
PICTURES

August 30 – September 4, 2015 | San
Diego California
PICTURES

August 30 – September 4, 2015 | San
Diego California
PICTURES

August 30 – September 4, 2015 | San
Diego California
THANKS FOR YOUR ATTENTION