This workshop is focussed 100% on flow from process control, tuning, flow instrumentation, control valves to fiscal metering. An introduction is given to the complete flow control system and methods of tuning flow loops followed by an examination of the different flow instruments with an emphasis on typical real-world applications. Close attention is given to special installation considerations and application limitations when selecting and installing different flow instruments. It is claimed that the majority of control valves installed have not been correctly sized and that large numbers also operate in manual mode. We thus focus on the correct method of sizing and selecting a flow control valve. The course is rounded off by an examination of fiscal metering with a simple introduction to what can be a complex but critical subject involving revenues of millions of dollars. Mathematical theory has been kept to a minimum and the focus is on practical design, installation, commissioning, troubleshooting and maintenance issues all focussed entirely on flow issues. WHO SHOULD ATTEND? Automation engineers Building service designers Chemical and mechanical engineers Consulting engineers Control technicians Control valve specialists Data systems planners and managers DCS personnel MORE INFORMATION: http://www.idc-online.com/content/practical-flow-essentials-2?id=

1. Practical Flow Essentials

2. Basic Principles of Control Systems
 Basic functions & definitions
 On/Off control
 Modulation control
 Principle of closed loop control
 PID control modes
 Exercises - #2 & #3
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3. Definitions
 PV (Process Variable) - Variable we want to control.
 MV (Manipulated Variable) – Variable to manipulate(to control the PV)
 Simple controllers – OP – controller output signal
 SP(Set Point Value) – Target / Ideal Process Variable
 Disturbances
 Other random inputs to the process may be measured and predicted
 Hysteresis
 Output reaction delays to a stimulus response based on direction of approach
 Multivariate
 Systems based on more than one PV may also have more than one
MV (OP)
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4. On/Off Control
 Good where fluctuations of PV are acceptable
 Wear/tear of controlling element is a problem
 Increase band of PV to reduce switching action
 Output of controller is a digital signal
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5. Response of a Two Positional Controller
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6. Simple on/off Control
 Enables a very simple form of temperature control
 Common form is a domestic gas-fired heater
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7. Modulating Control
 Output of the controller is an analog value
 Not digital value as in on/off control
 Can be used in open or closed loop control
 Use when more precise control of PV required
 Less hysteresis (band) of PV variation
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8. Open Loop Control
 Control action is not a direct function of PV
 No self-correction when the PV drifts
 Allows pre-emptive reaction to disturbance
 Control is based on measured disturbances
 (E.g. Feedforward control)
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9. Simple Process Block
 PV changes are a function of the control action
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10. Open Loop Control
 Control Action = Position of Accelerator
 Control result = Speed of Car
 BUT: Speed could vary with changing load
 Identify – Disturbances, PV, MV
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11. Feedforward Control
 Form of Open loop control
 Value to be controlled (PV) is not used to calculate the
control action
 Basic principle is:
 Manipulate a variable of the process block so that it
compensates for impact of any input disturbances.
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12. Feedforward Control
Feedforward block diagram
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13. Feedforward Control
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14. Feedforward Control
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15. Feedforward Control
 Objective is to keep level constant
 Manipulated variable = inlet valve position
 Control strategy: Inlet flow = Outlet flow
 If Feedforward control is the only control
 PV will drift over time
 Because of:
 Natural Evaporation
 Delay in valve positioning etc.
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16. Feed Heater Example - Analyze Components
Control object -
constant outlet
temperature
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17. Closed Loop PID
 Closed loop  Control strategy
 Measure PV
 Compare PV with SP (ERR)
 Calculate OP
Closed Loop PID has 3 Modes:
 Proportional Control
 React to the amount of ERR
 Integral Control
 Eliminate residual ERR
 Derivative Control
 Correct dynamic stability
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18. Direct or Reverse Controllers
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19. Manual Feedback Control
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20. Closed Loop Block Diagram
 PV is now part of the control action
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21. Feedforward and Feedback Combination
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22. Process Response Curve
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23. Sample and Hold Algorithms
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24. Process Response
 Response process gain
 ratio of the change in the process variable to the change in the
manipulated variable.
 Response dead time
 Response process lag
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25. Process Response
Example: Process response related to a step change of the input value
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26. DO YOU WANT TO KNOW MORE?
If you are interested in further training or information,
please visit:
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