Final Control Element
Download as PPTX, PDF16 likes14,414 views
Final control elements are devices like valves and pumps that adjust the manipulated variable to control process parameters. Common parameters include pressure, flow, level, and temperature. Control valves have components like actuators, bodies, and trim. Actuators provide the force and include pneumatic, hydraulic, and electric types. Valves types are ball, butterfly, gate, and globe valves. Positioners maintain the correct valve position. Control valves can experience issues like leaks, sticking, or nonlinear flow. Troubleshooting addresses problems like deadband, overshoot, sizing errors, and nonlinear characteristics.
Final Control Element
- 1. Prepared by, Mujtaba Moosawi S.Inst Technician
- 2. ASSESSMENT Mention 3 final control elements. What is the function of final control element? What are the types of actuators? What are the types of valves?
- 3. MAIN POINTS Final Control Element: What is a final control element? Process Parameters Control valve components. Actuators & Valves: Types of actuators Types of valves Valve Accessories. Troubleshooting: Valve characteristics Control valves Challenges Control Valves Troubleshooting.
- 4. FINAL CONTROL ELEMENT the final control element is a device which adjust the value of the manipulated variable by controlling flow of the control agent. The mechanism for affecting this change may be a valve, pump, transformer, motor, variable speed drive, etc.
- 5. PROCESS PARAMETERS Parameters normally measured and controlled in a process industry are: - Pressure Flow Level Temperature Speed pH, conductivity Composition Density BS & W Dew point Oxygen content (injection water), etc.
- 6. 12PI-001 12PC-001 12PCV-001 Transmitter Control Room DCS Control Valve Control Room DCS 15LI-003 15LC-003 15LCV-003 Transmitter
- 7. CONTROL VALVE MAIN COMPONENTS Actuator Valve body Control Valve
- 10. ACTUATORS - actuator provides the force that actuates the valve. - determine the flowrate of an agent through the valve. - Means used to operate the actuator may be • mechanical, • pneumatic, • electrical, • hydraulic, or • a combination of two of these methods.
- 11. TYPES OF ACTUATORS Air to close valve Air to open valve
- 12. A CONTROL VALVE WHICH OPERATES FROM A HIGH PRESSURE TO LOW PRESSURE, WE PREFER AN AIR FAIL TO CLOSE VALVE TO AVOID OVER PRESSURIZING OF THE DOWN STREAM FACILITIES. THE LEVEL CONTROL VALVE OF THE BULK SEPARATORS WILL BE AN AIR FAIL CLOSE VALVE. THIS IS TO PROTECT SURGE TANK FROM OVER PRESSURIZING IN CASE OF A FAILURE OF THE SEPARATOR LCV. Bulk separator Surge tankLCV PRC Gas to flare Air fail close valve Air fail open valve LC PC Gas to Compressor
- 13. VALVE TYPES Ball Valve Butterfly Valve Gate Valve Globe Valve
- 14. BALL VALVE Sphere with a port in a housing, rotate to expose channel. Applications: Flow control, pressure control, shutoff, corrosive fluids, liquids, gases, high temp. Advantages – low pressure drop, low leakage, small, rapid opening Disadvantages – seat can wear if used for throttling, quick open may cause hammer
- 15. BUTTERFLY VALVE rotating disk on a shaft, in a housing. Low pressure, large diameter lines where leakage is unimportant Advantages – low pressure drop, small and light weight Disadvantages – high leakage, high actuation forces so limited to low pressures
- 16. GATE VALVE Sliding disk, perpendicular to flow Applications: Stop valves, (not throttling), high pressure and temp, not for slurries, viscous fluids Advantages – low pressure drop when fully open, tight seal when closed, free of contamination buildup Disadvantages – vibration when partially open, slow response and large actuating force
- 17. GLOBE VALVE plug moved perpendicular to flow and closes on a ring seat Throttling, general purpose flow control valve Advantages – faster than gate, seat less wear and tear, high pressure drop for pressure control Disadvantage high pressure drop, require considerable power to operate (gears and levers), heavy
- 18. ANIMATION
- 19. VALVES’ SYMBOLS
- 21. POSITIONER Positioner Input from I/P supply air output to valve - keeps the valve at the correct operating position. - Boosts the pressure and volume of the air coming out from the I/P converter before given to the valve. - Possible to reverse the output of the I/P before given to the valve diaphragm.
- 22. VALVE CHARACTERISTICS Classified by relationship between the valve stem position and the flow rate Quick Opening Used for full ON/full OFF Small motion of the stem, resulted in maximum possible flow rate Linear Flow rate varies linearly with stem position Equal Percentage Percentage change in stem position equal percentage change in flow rate
- 23. OTHER VALVES Motor operated valve Emergency Shut down valve Solenoid valve
- 24. CONTROL VALVES ISSUES Actuator: - Diaphragm rupture - Gland Packing damage - Regulator pressure setting Valve: Passing Leaking Not opening/closing
- 25. CONTROL VALVES TROUBLESHOOTING Four problems with control valves are found at a high frequency in poorly performing control loops. These are: - Dead band - Positioner overshoot - Incorrect valve sizing - Nonlinear flow characteristic
- 26. CONCLUSION Final Control Element: What is a final control element? Process Parameters Control valve components. Actuators & Valves: Types of actuators Types of valves Valve Accessories. Troubleshooting: Valve characteristics Control valves Challenges Control Valves Troubleshooting.
Editor's Notes
- #6: Now let us see the manipulated variables… What are They ?