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Centrifugal antisurge system manual
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NEW ANTISURGE SYSTEM MANUAL
K‐421
L
Modified HP and LP Servomotor Control
Modified Trip Oil Circuit
I‐15OST
Redundant SOVs
3‐way Cock Valve(12.01)
Drain Drain Drain
P‐422
Main Oil Filters
Oil Tank
All Drains
IH
IH
Drain
DrainExistingOil Filter(17.02.1)
Duplex Oil Filter (New)
Drain
Drain
Electronic Speed
Governor
SIC251
PIC251
HP ESV Actuator (1.01.2)
LP ESV Actuator (1.02.2)
Seal Steam Controller04‐PCV‐252 (5.03)
Drain
Drain
Drain
2.5 – 4.5 kg/cm²
1.5 – 3.0 kg/cm²
4‐20mAHP Servomotor
(17.26)
LP Servomotor(17.27)
Remove connection to CVCM
Remove connection to Micro Filter / Speed
Governor
Orifice(13.16)
Adjustable Orifice
Stop Valve(14.21)
SOV(11.31)
(14.16.2)
(14.16.1)
Throttle Valves
(13.21)
Stop Valve(14.15)
Remove connection to Secondary Steam
Controller
New SOV
DRAWN BY
MUDASSIR MEHMOOD
TITLE
TK‐421 Control Oil CircuitDESCRIPTION
Control Oil circuit for TK‐421 Electronic Speed Governor
DATED
TK‐421 Control Oil Circuit
Legend
Hydraulic Signal
Instrument Signal
Modification
Existing Equipment
New Equipment
1. Fine Filter (17.02.2)2. Speed Governor (17.31)3. CVCM (11.62)4. Pressure Transducer (11.05)5. Isolation Valves (14.23)
6. Isolation Valve (14.15)7. Orifice (13.15)8. Secondary Steam Controller (17.28)9. Lube Oil Pressure Security (11.36)10. Overspeed Trip Security (11.57)
Items removed from the circuit
Oct 7, 2009
Twin Filter
LP Steam Valve
HP Steam Valve
Drain Assembly
1" tube to G¾“ male x 8
ball valve 1 inch NPTF x 4
2 inch pipe
2 inch flanges
1.5 inch pipe
1 inch tube
Pipe Tee1.5" x 1" x 1"
NPTF
Pipe Tee1" x 1" x 1"
NPTF
1" tube to ¾” BSPP male
1" tube to 1" NPTF male x 14
1" tube to ¾” BSPP male
1" male to 6mm tube
1" male to 6mm tube
6mm tube to ½” NPTM
Nipple ½” NPTM
Tx
½” NPTF
6mm tube to ½” NPTM
Nipple ½” NPTM
Tx
½” NPTF
2" pipe 1" socket x 4
2" socket
BILL OF QUANTITIES# Item Description Qty (ea)1. 2" pipe flanges 22. Pipe tee 1.5" x 1" x 1" NPTF 13. Pipe tee 1" x 1" x 1" 24. Full-bore ball valve 1" NPTF 45. Connector 1" tube to 1" NPTF 146. Connector 1" tube to ¾” BSPP male 27. Connector 1" tube to G¾” male 88. Connector 1" male to 6mm tube 29. Connector 6mm tube to ½” NPTM 210.Two way manifold ½” NPTF 211.Nipple ½” NPTM 212. 1" socket 413. 2" socket 114. 1" tube 1 lot15. 1" pipe 1 lot16. 1.5" pipe 1 lot17. 2" pipe 1 lot
1" pipe
K-421 Control Oil Circuit Sketch
I/H convertor adapter plate
ISNTRUMENTS FOR K‐421 ANTISURGE SYSTEM
Sr No.
Tag No. Description Service JB No.Installation
Drawing No.Range
Pressure Transmitter Kg/cm2
1 04‐PI‐1 Suction pressure of the compressor Air 04‐E‐14 INST‐PS‐04‐02 ‐0.13‐0.13
2 04‐PI‐3 Discharge pressure of the compressor Air 04‐E‐13 INST‐PS‐04‐02 0‐603 04‐PI‐4 Extraction Pressure Air 04‐E‐13 INST‐PS‐04‐02 0‐12.5
4 04‐PI‐31 Pressure for mass flow control Air 02‐E‐2 INST‐PS‐04‐02 0‐45
04‐PIC‐251 LS Prsessure Control Steam 04‐E‐14 INST‐PS‐04‐01 0‐5Flow Transmitter mmWC
1 04‐FI‐1A Air 04‐E‐13 INST‐PS‐04‐04 0‐20002 04‐FI‐1B Air 04‐E‐13 INST‐PS‐04‐04 0‐20003 04‐FI‐2A Air 04‐E‐13 INST‐PS‐04‐04 0‐12504 04‐FI‐2B Air 04‐E‐13 INST‐PS‐04‐04 0‐12505 04‐FI‐31 DP across Orifice 02‐FE‐31 Air 02‐E‐1 INST‐PS‐04‐03 0‐3700
Temperature Transmitter oC1 04‐TI‐1‐20 Suction temperature of comprssor Air 04‐E‐14 INST‐PS‐04‐05/06 0‐1002 04‐TI‐1‐21 Extraction air temperature Air 04‐E‐13 INST‐PS‐04‐05/06 0‐1003 04‐TI‐1‐22 Discharge temperature of comprssor Air 04‐E‐13 INST‐PS‐04‐05/06 0‐2504 02‐TI‐31 Temperature for mass flow control Air 02‐E‐2 INST‐PS‐04‐05/06 0‐250
DP across nozzle 04‐FE‐1 in the discharge of compressorDP across Orifice 04‐FE‐2 in the air extraction line
SYSTEM OVERVIEW K‐421
Project Overview The project consists of replacing the current control system with the CCC Series 5 Duplex Vanguard integrated control system, which will provide
1. Antisurge Control, 2. Performance Control, 3. Speed Control, 4. Steam Induction Control 5. Overspeed Prevention.
The Series 5 hardware will be interfaced with hardwired I/O, the customer DCS through serial communication and with one PC through Ethernet communication. The PC will be running Compressor Controls Corporation’s TRAINVIEW operator interface software. The Guardian overspeed prevention system will be interface with hardwired I/O and the Guardian front face keypad. The CCC Series 5 Vanguard hardware and Guardian will be mounted in a control panel provided by FFC and will be located in the control room. FFC provides 110VAC 50Hz source from a UPS which powers the Series 5 control system.
Control System Description The Series 5 Vanguard Control System Rack 1 architecture is identified in the following table:
System Description 1.4.1 Primary Control Objectives The following is a list of the primary control objectives of the Compressor Controls Corporation control system.
Antisurge control for the compressor Mass flow control
Steam turbine speed control Steam turbine induction steam control Overspeed prevention
1.4.2 Secondary Control Objectives The following is a list of the secondary control objectives of the Compressor Controls Corporation control system.
Compressor discharge pressure limiting control 1.4.3 Control System Features The following is a list of the control system features as implemented in the initial Systems Engineering design. These features may or may not be implemented in the final control system configuration. Please refer to the CCC Control Application User Manuals for a detailed description of these features.
Transmitter out of range detection (transmitter failed) Fallback control strategies for failed transmitters Set point high and low clamps Output high and low clamps Redundant antisurge, speed, performance, and logic control loops Bumpless transfer between controlling the primary and secondary(limited) process
variable Serial communications for data and alarm transfer to the DCS
1.4.3.1 Antisurge Control System Features The antisurge control loop modulates an antisurge valve. The antisurge valve tends to open when the DEViation of the operating point is negative. The antisurge valve tends to close when deviation of the operating point is positive. The antisurge control algorithm calculates the operating point’s deviation using the surge control line as a reference value of 0.0. The three primary antisurge control loop components are:
Proportional + Integral response increases the blow‐off rate any time the operating point moves left of the Surge Control Line (SCL) by opening the antisurge valve.
The Recycle Trip open‐loop response ratchets the antisurge valve open when the operating point moves left of the Recycle Trip Line (RTL) using a stepped response.
The Safety On response moves the Surge Control Line to the right if the operating point moves to the left of the Safety On Line (SOL).
Other antisurge control features are:
Emergency shutdown response Normal shutdown response Manual operation while in STOP Manual override (automatic transition to auto) for compressor protection
1.4.3.2 Performance Control System Features Set point high and low clamps Override of manual when limiting control actions are necessary Tracking compressor speed Bumpless transfer when the speed governor’s set point source is switched from
local to remote control 1.4.3.3 Speed Control System Features
Median select between three magnetic pickups High select among two magnetic pickups Single select among one magnetic pickup Shutdown on loss of all magnetic pickups Critical speed range avoidance Secondary Overspeed prevention Recording the turbine’ s highest attained speed after a shutdown Coordinated start / stop / shutdown sequencing with steam turbine induction
controller 1.4.3.4 Steam Induction Control System Features
LS Steam Header pressure control Coordinated start / stop / shutdown sequencing with speed controller
1.4.3.5 Overspeed Prevention System Features Primary overspeed prevention Three independent speed modules for two‐out‐of‐three voting Supervisor module with alphanumeric display Four DPDT trip relays and one DPDT alarm relay Redundant power supply modules Reset discrete input from Vanguard logic control Start discrete input from Vanguard logic control
Automatic Load and Unload (StartUp and Shutdown) Since human response times are relatively slow, it is generally much smoother and safer to bring compressors on‐line under automated control rather than manual control. Under manual control, opportunities exist for erratic operation and surge damage to the compressor. With a suitable automated control algorithm/sequence, compressor loading and unloading are smooth and repeatable processes. Normal Operation StartUp Sequencing 1.5.1.1 Resetting Reset the speed controller and overspeed prevention system by pressing the RESET command from the DCS or via Trainview Reset button. Reset any alarms by accepting all alarms from the Alarm Screen in TrainView. The speed controller will enter the Ready To Run state (assuming the ESD and Start Permissive discrete inputs are healthy).
1.5.1.2 Speed Controller Note: The following commands can be given to the Speed Controller via discrete inputs from the Local Control Panel, DCS, Trainview PC or Modbus communications. If the speed controller is not already reset at this time, the speed controller must be reset as described above. The START command is given and the speed controller will ramp open the governor valve to control turbine speed to a configurable Idle1 speed(1000RPM). The START command is also sent to the overspeed prevention system to start the fail safe timer. Note: The speed controller and overspeed prevention system is configured with a fail safe timer, which requires the turbine speed to reach at least 200 RPM within 60 seconds of asserting the speed controller Start discrete. If the turbine speed does not reach 200 RPM within 60 seconds, the speed controller and overspeed prevention system will self initiate a shutdown. This fail safe timer function insures that the speed controller or overspeed prevention system will self initiate a shutdown in the event that turbine shaft speed sensors do not provide valid speed signals upon start sequencing of the turbine. After the turbine has warmed up at the Idle 1 speed (1000 RPM) , the Idle 2 speed (2200 RPM) command is given and the speed set point will increase automatically to a configurable Idle 2 speed. After the turbine has warmed up at the Idle 2 speed, the Idle 3 speed (4400 RPM) command is given and the speed set point will increase automatically to a configurable Idle 3 speed. After the turbine has warmed up at the Idle 3 speed, the Rated speed command is given and the speed set point will increase automatically to CCC Rated speed. Automatic speed sequencing to any idle speed or CCC Rated speed may be interrupted at any time by asserting either the Speed Lower/Raise commands or Idle speed commands. Once the speed sequencing is interrupted, the Lower/Raise/Idle commands can be used to manually decrease or increase the speed set point as required for continued start‐up of the turbine. If the ramp is interrupted within a critical speed band, the speed set point will be set to either the low or high end of the critical band (depending upon the speed set point ramp direction). When the turbine speed reaches the CCC Rated speed, the Speed Lower/Raise commands can be used to further adjust the turbine speed set point. The following speed control mode selections are available to the operator through the TrainView PC, discrete inputs or DCS Modbus serial communications. Reset – If the ESD signal is absent and the Start Permissive signal is present when the Reset button is pressed the controller will transfer to the Ready state. Start – The controller will ramp the steam valve open in an open loop response until either the minimum speed is detected by the pickups or the maximum start level is reached by the steam valve. Once the minimum control speed is detected by the pickups the controller will transfer to the accelerate mode and the steam valve will be controlled by the speed PID control block and the set point will ramp to the Idle 1 level. Idle 1 – The speed control set point will be set equal to the Idle 1 speed level. Note: the speed controller will stay at the selected idle level until the operator selects another Idle or Rated speed level.
Idle 2 – The speed controller set point will be set equal to the Idle 2 speed level. Note: the speed controller will stay at the selected idle level until the operator selects another Idle or Rated speed level. Idle 3 – The speed controller set point will be set equal to the Idle 3 speed level. Note: the speed controller will stay at the selected idle level until the operator selects the Rated speed level. Rated – The speed controller set point will be set equal to the Rated level. Stop – The speed controller will enter the Local set point mode and ramp the set point down to zero rpm. ESD – This command is used to trip the unit. The output of the speed controller will immediately go to 4 mA and close the steam valve. The compressor anti surge valve will immediately open. Remote/Local – This command is used to select the source of the speed set point. When in Local the set point is selected either automatically by the speed controller during periods of Startup / shutdown or by the operator through the use of the Raise and Lower buttons. When in the Remote set point mode the speed controller set point is controlled by the output of the CCC performance controller or the analog remote set point from the DCS. When the speed controller is in the Local set point mode, the CCC performance controller and DCS will be in the Tracking mode. Analog Set point – This command is used to select an analog input as the remote set point to the speed controller from the DCS. The remote set point is only valid when the speed controller is running in the normal operating speed range between minimum and maximum governor. Raise – This command is used to increase the speed set point while the speed controller is in the Local set point mode. Lower – This command is used to decrease the speed set point while the speed controller is in the Local set point mode. 1.5.1.3 Antisurge Controller From the STOP state, the Antisurge Controller begins automatic control when the following conditions are satisfied:
the rotational speed N rises above a configurable Run/Stop threshold (typically set slightly above or below minimum governor speed)
the Run/Stop discrete input is closed Once all the above conditions are met, the controller begins ramping its output
towards the fully closed position. The controller will then transition to the RUN state
1.5.1.4 Performance Controller The Performance controller requires no startup sequencing as it is always in Run mode and the speed controller will only respond to the performance controller output when the speed controller is switched from Local Setpoint mode to Remote Setpoint (cascade) mode.
1.5.1.5 Steam Induction Controller Sequencing The induction controller output will remain at zero through the speed control start‐up sequencing. Induction control is disabled (idle) when the turbine speed is below minimum governor. Automatic induction control is enabled (run) via Modbus serial communications and is enabled after the turbine speed is at or above minimum governor (5393 RPM). Once induction control is enabled, the induction controller ramps up its output to the induction steam valve until induction pressure set point is satisfied. 1.5.2 Normal Stop 1.5.2.1 Steam Induction Controller Sequencing Induction pressure control is disabled (idle) by any of the following: • Modbus serial communications, • the companion speed controller indicating a STOP condition; • the companion speed controller speed signal dropping below minimum governor. When the induction pressure controller switches to the disabled (idle) state, it ramps closed the induction steam valve. 1.5.2.2 Performance Controller The performance controller remains in the Auto/Run state. 1.5.2.3 Speed Controller The turbine is sequenced off‐line using the Speed Controller functions Idle or Stop. Requesting Idle or Stop will transition the Speed Controller to Local Set point Mode. Selecting Stop causes the following to occur: • the speed controller ramps down the speed set point
• when the speed set point reaches the configured minimum control speed (approximately 200 rpm), the speed set point and control output are set to 00.0 and the controller enters the Shutdown state The stop sequencing may be interrupted at any time by asserting either the speed Lower/Raise commands. Once the speed sequencing is interrupted, the Lower/Raise/Idle/Rated commands can be used to manually decrease or increase the speed set point as required for continued sequencing of the turbine. If the ramp is interrupted within a critical speed band, the speed set point will be set to either the low or high end of the critical band (depending upon the speed set point ramp direction). 1.5.2.4 Antisurge Controller The antisurge controller unloads the compressor by ramping open the antisurge valve. The antisurge controller is signaled to the Stop state by: • the speed controller indicating a Stop condition • the Run/Stop discrete input is opened • the speed controller speed signal dropping below a configurable Run/Stop threshold (typically set slightly above or below minimum governor speed) When the antisurge controller switches to the Stop state, it ramps open the antisurge valve. The ramp rate is configurable.
1.5.3 Emergency Shutdown (ESD) The following emergency shutdown descriptions are limited to the CCC ESD control actions. 1.5.3.1 Speed Controller ESD control actions are initiated by: • Speed controller initiated ESD due to loss of all speed sensors or speed controller secondary electronic overspeed trip detection • selecting ESD from the TrainView HMI speed controller faceplate. • Total Trip discrete input from PLC opens • ESD discrete input from the LCP opens ESD control actions are: • speed set point and output immediately set to 00.0; • Vanguard Shutdown discrete outputs to PLC open 1.5.3.2 Overspeed Prevention System ESD control actions are initiated by:
• two‐out‐of‐three voting overspeed detection; • loss of two‐out‐of‐three speed sensors; • two‐out‐of‐three speed modules fault; ESD control actions are: • Guardian Trip discrete outputs open to solenoid valves and PLC. 1.6 Control System Interface 1.6.1 TRAINVIEW Workstation Interface The TrainView Workstation consists of a PC loaded with software interface tools to configure and display the Series 5 Vanguard control system. The PC connects to the Series 5 Vanguard control system using Ethernet communications. The Series 5 Configurator software package is used to read and write control system parameter configuration files. The Series 5 TrainView software package serves as the HMI and provides graphic display screens, which are used as an operator interface to the control system. The real time graphic display screens provide process monitoring and control of the process using control system diagrams, controller faceplates, controller trends, alarms and archive events. The graphic displays allow the operator to read and write values to Series 5 Vanguard control system variables such as controller set points, manual outputs, start/stop sequencing commands and acknowledging/clearing of system alarms.
COMMISSIONING K‐421
Compressor Start
Turbinedriven Compressors a. Connect a PC to controller(s) that has CCC’s high‐speed recording tools installed. b. When started for the first time under CCC control, the following should apply: • The Performance controller should be in Manual Mode with output corresponding to minimum governor speed. • The Antisurge controller should be in Manual Mode with output corresponding to full opening of the recycle valve.
Surge Testing Machines with Variable Speed or Guide Vanes Test Guidelines Normally, three surge points at minimum are required to adequately describe surge curve. k‐factor tends to increase with increasing speed or opening of guide vanes (Slope of the Surge Line decreases). It is desirable to perform surge tests on gas that is most similar to gas used during normal process, since location of SLL (SURGE LIMIT LINE) can shift due to changes in gas composition. Recommended procedure involves closing the recycle valve by gradually lowering k‐setting in the Antisurge controller until compressor surges. In a correctly designed system, response of RT algorithm should take compressor out of surge within the first surge cycle, while SO algorithm should not allow surge cycle to repeat. In order to minimize process disturbance during surge testing, it is desirable to isolate compressor from the process.
1. Ensure that the Antisurge controller receives all necessary signals. Check signals either against calculations or other indicators (such as gauges mounted in the piping) to ensure that they appear to be correct.
2. If high frequency noise on the flow signal is excessive (DEV swings more than approximately +/‐.05), slightly (usually less than 1/4 of the damping adjustment range) increase transmitter damping. However, extreme caution should be taken so as not to filter out frequencies comparable to surge frequency (1‐2Hz). Controller filter time constant can be increased, but should remain below 00.5 seconds.
3. With the Antisurge controller in Manual Mode and recycle valve fully open, adjust antisurge controller settings so that DEV is slightly positive (around .10). Enter conservative settings for PID parameters.
4. With PC and CCC’s high‐speed recording tools running, put controller into Automatic Mode. Monitor response as controller brings DEV to zero. Make any necessary adjustments based on speed of response.
5. Bring margin of safety to zero (if not already zero) by small increments. Adjust PI tuning based on response.
6. Test RT response. Measure delay between movement of controller output and flow response. Set Recycle Trip time delay accordingly. Normally, measure it as time between initiation of RT response and 1/3 of full change in S.
7. Reduce k‐factor by small increments. Monitor any available indication, such as vibration monitor, for signs of approaching surge. If excessive vibration appears, stop current test and use high vibration point as the surge point.
8. Reduce k until compressor surges. Note the k‐factor at which surge occurred. Save PC recording file.
9. Increase k by about 50%; reset SO. Increase speed (guide vane position) to next testing speed and repeat surge test.
10. Increase k by about 50%; reset SO and repeat test at maximum speed (guide position).
11. Perform calculations for the appropriate characterizer. Characterizer should normally be monotonic and as smooth as possible.
12. Surge test records are contained in the PC using CCC’s recording tools. These files are placed on the network under appropriate project number.
Compressor Performance Tuning Control System Tuning
1. Establish tuning for antisurge protection. Turn off derivative response. Induce disturbances. Obtain Proportional Gain and Integral Reset for fastest response without overshoot. Induce Recycle Trip. Turn on and adjust derivative response.
2. Establish tuning for Performance control. Induce disturbances by changing set point. Obtain Proportional Gain and Integral Reset for approximately 1/4 decay ratio (Ziegler‐Nichols method).
3. Establish decoupling coefficients between controllers. 4. Induce disturbance, such as Recycle Trip, and monitor system response. Make
any fine tuning adjustments.
Load Sharing Systems. The Master controller supplies "S" set points to each Load Sharing controller. The Main control action takes place through the feedforward signal from the Master to each Load Sharing controller. Use the following procedure to set up a Load Sharing system:
1. Configure Master controller for Load Sharing. 2. Set correct control loop directions. 3. Set preliminary PID tuning parameters in the Master. 4. Configure Load Sharing controllers. 5. Set preliminary PID parameters in the Load Sharing controllers. Large filters could be
used to further slow down response to "S" changes. Use the following procedure to tune the system once compressors have been started:
1. Adjust PID parameters of the Master controller by inducing set point changes so as to obtain as near to critically damped response as possible (do not overshoot).
2. If compressors react differently (i.e. equal changes in master's output produce different changes in the PV of the Load Sharing controllers), adjust gain coefficients.
3. If power consumption appears to be unequal, adjust appropriate coefficients in the Load Sharing controllers.
Speed Controller Commissioning Checkout of a Simplex Steam Turbine System
1. A point‐to‐point wiring check of the whole system shall be accomplished. 2. Check power to controller. 3. Power up controller. 4. Check analog outputs.
Check controller configuration. • correct output is being used 4‐20mA, 0‐200mA, or BI‐Polar correct function is
being used Output shall be checked all the way to the end device (i.e. I/P, I/H, etc.). Check actuator connection.
• stroke actuator before connecting to linkage • determine if actuator stroke is correct (adjust as needed) • connect and inspect linkage (linkage shall be non‐binding and free), stroke
actuator • correct stroke as needed
5. Check of discrete inputs. Check controller configuration.
• correct function assignment • correct contact assignment
Ensure each discrete input is reaching the controller, by operating the end device (pushbutton, limit switches, etc.).
6. Check of analog inputs. Check controller configuration. Check field input module configuration (make any needed adjustments). Check incoming analog signal. Check controller display to ensure controller is interpreting signal correctly.
7. Check of discrete outputs. Check controller configuration.
• relay configuration • contacts used • functional assignment
Check field output module configuration. • check power being used (controller power and customer power) • cycle relay, if possible, to assure that end device works
8. Check frequency inputs. Check controller configuration.
• frequency channels being used • number of teeth on signal gear • ratio of signal gear rotation to turbine shaft rotation
Check signal gear and magnetic pickups. • gap between pickups and signal gear • number of teeth on signal gear • ratio of signal gear rotation to turbine shaft rotation
When starting turbine, ensure controller is receiving correct frequency input on each channel.
9. Check speed values configured in controller. 10. These shall be verified with customer. 11. Check communication.
To/from controllers. To/from computer system.
12. Check turbine overspeed trip system. 13. Check and confirm all other parameters not mentioned in above text.
SYSTEM CHECK LIST K‐421
SYSTEM CHECK OUT PROCEDURES 1. Inspection of the Controllers and Panel
a. Measure supply voltage to the controllers to verify that it is within appropriate range.
b. Check continuity between Safety Ground Bar and AC power ground in the panel.
c. Visually inspect controllers for any damage that might have occurred during shipping or installation.
d. Power up the controllers and insure all is normal. e. Check that temperature inside the panel complies with CCC specifications. f. If any damage or functionality problems are encountered, do the following:
• Investigate cause of damage/failure. • Determine if damage/failure is covered under CCC warranty. • Notify Des Moines office of the failure. • Obtain replacement unit or component either from Des Moines or from
customer spare parts stock. 2. Controller Setup
a. Ensure that controllers have correct software/firmware. • If software/firmware needs to be updated, install or download.
3. Field Checks a. Piping layout • Check the location of the recycle line relative to compressor discharge and
suction. Large distances/volumes could imply slower response by the control system.
• Check valve should be located downstream of the recycle line take‐off point. b. Flow measuring device • Check that the flow measuring device is installed in sufficiently long straight
run of pipe. • Ensure that taps are placed correctly. Flow transmitter should be installed
above the taps. c. Recycle valve • Inspect impulse piping, making sure that supply tubing and tubing connected
directly to the actuator is of sufficient diameter (larger than 1/2"). Boosters should have either internal or external adjustable bypasses. Quick exhausts are not desirable. Quick exhaust in series with a booster is also not desirable. Distance between I/P and valve positioner should not exceed 2‐3 feet.
• Connect portable current source to the valve I/P. Test speed of stroke by stepping output from 4mA to 20mA and back. Opening time should be 2 seconds or less. Closing time is not as critical, but should also be approximately 2 seconds to maximize controller PID loop speed of response. Check for correct calibration of the I/P unit.
• Slowly change control signal and make sure that valve position follows smoothly. Check hysterisis by noting control signal and corresponding valve position while moving signal in opposite directions. Check dead zone. Change control signal by a step (approximately 20% magnitude). Note overshoot, any oscillations, and settling time.
• Overshoot in response to a step change should be less than roughly 25% of the magnitude of a step. There should not be any oscillations. If valve hunts, open bypass around booster until hunting stops. Note that under working conditions (with a pressure differential) valve operation tends to be less stable.
NOTE: Briefly, there can be the following problems: 1. Valve stem may be "sticking" resulting in large dead zones. 2. Booster/quick exhaust combination can result in large dead zones and hysterisis. 3. Valve positioner can be poorly adjusted or malfunctioning. 4. Supply pressure is not within specifications. 5. Bypass around boosters is opened either too much (slow stroking), or too little
(hunting). 6. Excessive vibration while in service can cause erratic movement of the valve. 7. Dead zones at both ends of the stroke should be minimized. It is particularly important
to minimize dead zone at 20mA for an antisurge valve. This ensures that the valve begins to open as soon as required by the control signal. Adjusting calibration of the I/P unit and positioner can minimize dead zones.
d. Physical location of all transmitters Generally, transmitters should be installed so as to avoid any condensation in the impulse piping. This means that transmitters should be mounted above the taps. Condensation usually occurs as high pressure gas cools off. If condensation is determined to be a problem, then transmitter should either be relocated, impulse piping heat traced, and/or condensation traps installed. Length of impulse piping should be minimized (not more than 10 ft). 4. Wiring Loop Check
1. All input signals must be checked for continuity and other possible problems. In conjunction, it is desirable to verify calibration of all transmitters. Compare panel wiring diagrams to CCC drawings for any inconsistencies. Any discrepancies must be resolved prior to start‐up.
2. If transmitters have not been calibrated connect pneumatic calibrator to the transmitter. Vary input pressure (minimum, midpoint, maximum of the span). Read corresponding channel. For temperature inputs a thermocouple/RTD simulating device can be connected to the temperature transmitter. For smart transmitters calibration check can be performed with the hand‐held terminal. Ensure that calibration ranges correspond to those specified in CCC Engineering Manual prepared for the project. Alternatively, if calibration check is not possible to perform, use a portable current source to inject a current signal into each loop at the transmitter itself. Check for corresponding reading at the controller.
3. "Ground Loop" problems in CCC control systems can occur. Usually problems occur when transmitters are powered by different power supplies, each with its own potential, or when one of the transmitters is connected to some ground. Ensure Ground Loops problems are not present.
4. Verify operation of all discrete I/O. This includes correct set up of the controller relays and correct response to any discrete signals provided by the customer.
5. Verify operation of analog outputs. Make sure that the output display on the front panel corresponds to the measured current (i.e. 50% on the output = 12mA). Move the antisurge valve from the Antisurge Controller. Move any throttling valves from the Performance Controller. In case of controlling speed, ensure that the Performance controller output provides desired set point to the speed governor system.
6. Verify Serial Communications between the controllers and host computer or DCS system.
5. Document any changes from project Engineering Manual. Document all errors. Collect any relevant information as to the intended operation of the system. Submit changes/errors report and relevant information in the Field Engineering Field Service Report. Refer to System Commissioning
Procedure, TQAP400, for content of the Field Service Report.
GOVERNOR (I/H CONVERTOR) K‐421
Functional Description
I/H CONVERTOR
Fig. 3.1.1
1 – Control magnet VRM Pin ‐ Input pressure
2 – Tappet for power transmission PA ‐ Output signal pressure
3 ‐ Potentiometer X0 und X1
4 – Manual operation knob T1 ‐ Tank return line
5 – Electric connection T2 ‐ Tank return line with int. leakage
6 – Control housing FMag ‐ Magnetic force
7 – Control piston with damping piston FHyd ‐ Hydraulic force
8 ‐ Cover FFed ‐ Spring force
9 ‐ Control spring
Operating characteristics
(see fig. 3.1.1)
A set signal w = 4...20 mA generates a magnetic force FMag in the VRM, the limits of which
can be adjusted by means of the X0 and X1 potentiometers and which is then transmitted
onto the control piston via tappet. The hydraulic force FHyd being proportional to the output
signal pressure PA acts against this force. In the case of the two forces being equal, the
control piston is positioned in the “hydraulic center” as shown in fig. 3.1.1 and the output
signal pressure PA corresponds to the set signal. In the “hydraulic center“ position the
control piston performs minimum oscillating movements in the area of the guiding edges P
PA and PA T , in order to keep the output pressure PA on the value set by FMag.
When increasing the set signal and thus FMag from this condition, the control piston position
changes and thus connects the output pressure PA to the feed pressure P and blocks PA
towards the tank return line T1 and T2. Now the pressure PA will increase until the control
piston returns to the ”hydraulic center“ and PA corresponds to the new set signal. The
spring force FFed of the control spring generates a force‐offset in order to guarantee the I/H
converter function for output pressures of approx. 0 bar, too. The damping piston provides
hydraulic damping independent of the installation position. The internal leakage is
additionally fed back into tank return pipe T2.
Function of manual operation knob
The control magnet of the I/H converter is provided with a manual operation knob, by
means of which an adjustable spring force can be set instead of the magnetic force FMag .
This spring force affects the control piston via magnet armature and tappet. The hydraulic
force FHyd , being proportional to the output signal pressure PA also acts against this spring
force here. Thus adjustment of output pressure is possible without electric connection.
Commissioning
The I/H converter was adjusted and tested at Voith Turbo’s works by means of the
potentiometers X0 and X1. The test result is documented in an attached test certificate.
The potentiometers are provided with a protective cap to avoid unintentional
maladjustment and impurities.
6.1 Test run
Make sure that pipe lines and hydraulic system are cleaned prior to performing a test run.
The operating fluid has to be in accordance with the purity class as indicated in chapter 1.
Do not flush or clean the pressure fluid with the I/H converter being hydraulically
connected. Operation of the I/H converter with contaminated pressure fluid is not
permitted, the I/H converter may be damaged. _ Check the line mounting, connection and
flow direction to and on the I/H converter.
_ Check the electric connection.
_ Switch on the 24 VDC power supply.
_ Switch on the oil supply and check input pressure.
The minimum input pressure has to be 1.5 bar more than the maximum output pressure
required at 20 mA.
_ Set the signal w = 4.. 20mA and check output pressure.
During the test run, check all hydraulic connections for leakages. In case of leakage,
immediately switch off the hydraulic supply and eliminate leakages.
6.2 Parameter setting
Due to unintentional maladjustment of the parameters or changed operating conditions,
new setting of one or both parameters may become necessary. We recommend to
document adjustment of the parameters as well as the set values. The parameters are
adjusted by means of potentiometers X0 and X1. Please refer to chapter 10 for the position
of the potentiometers.
Potentiometer effects:
X0 ‐ With help of potentiometer X0 the minimum output pressure PA min is adjusted at a
setpoint of 4 mA Pressure increase by turning the potentiometer clockwise.
X1 ‐ With help of potentiometer X1 the maximum output pressurePA max is adjusted at a
setpoint of 20 mA.Pressure increase by turning the potentiometer clockwise
X1 should be adjusted before X0.
The X1‐ adjustment influences the adjustment of X0.
Manufacturerprovided adjustments:
At the works, the I/H converter has been adjusted as indicated in the order.
7. Operation
7.1 Operation with manual knob
Operation with manually controlled rotary knob is possible without electric energy. On
operation with manually actuated rotary knob, uncontrolled stroke movements of the
hydraulic components controlled by the I/H converter output might occur due to the
increase in the output signal pressure. Manual operation is only possible when the circlip is
removed from the manual operation knob. On completion of operation with manual
operation knob, move the manual operation knob in its final position by turning it counter
clockwise and pushing in the circlip to its final position.
_ Remove the circlip.
_ Slowly turn the manual operation knob clockwise and observe the output pressure
Direction of control action: Output pressure increase by clockwiserotation.
Operation with set signal
When the supply voltage is switched on, the output signal pressure can be adjusted
continuously by the set signal 4...20 mA within the limits set by the potentiometers X0 und
X1.
7.3 Trouble shooting and remedial action
Prior to all works, make sure that the I/H converter was commissioned according to
chapters 5 and 6.
Malfunction: Pressure variations
The output signal pressure PA may vary now and then or periodically with low or high
frequency and amplitude.
Cause:
1. air inclusions in the hydraulic component
2. low or considerably varying input pressure.
3. dirt particles in the hydraulic component
4. pressure on return line
Remedy:
1. On first commissioning or after longer periods of stand still air inclusions in the
hydraulic component may cause pressure variations. Automatic ventilation grants
sufficient hydraulic damping due to the damping piston within seconds.
2. Under load and in particular in case of higher output signal pressure, a lower input
pressure may lead to pressure variations. Increase and / or stabilize the input pressure by
taking appropriate measures (e.g. accumulator). See also chapter 1.
2. Contaminated pressure fluid results in increased friction at the control piston, thus
causing hysteresis and pressure variations. Open hydraulic component and clean the inner
elements. In case of damaged surfaces and guiding edges replace the I/H converter.
3. The dimensions of the return line have to be sufficient. In case of additional consumers of
the output pressure connected to this line, make sure they do not create
any pressure in the return line. See also chapter 5.2.
Malfunction: Output pressure PA _ 0 bar or _ P (input pressure)
Due to a defective control valve VRM or blockage of the control piston the output pressure
may fall to 0 bar or increase to the input pressure.
Remedy:
In case of a disturbance in the electrical part of the VRM or a short defect in the supply
voltage, the integrated supervising will switch off the magnetic force and the output
pressure PA will fall to 0 bar. The “OK‐signal” signals response of the supervising system.
See wiring diagram in chapter 10.
If reset is not possible despite correct supply voltage, the VRM is defective and needs to be
replaced. The function of the hydraulic components can be checked using the manually
controlled knob with the supply voltage being switched off. See chapter 7.1.
If the output pressure cannot be adjusted, the control piston, e.g., may be blocked by
particles. Open hydraulic component and clean inner parts.
If the surfaces and guiding lines are damaged, exchange the I/H converter.
Repairs on the control magnet VRM are not allowed; otherwise explosion protection is no
longer guaranteed.
Replace any defective I/H converter completely.
Shutdown
If the I/H converter is switched off for reasons of repair, inspection or unit shutdown,
switch off the oil supply system and relieve all pressure reservoirs, if effective. Switch off
the 24 VDC supply voltage and remove the lines as well as piping and hose connections.
Doing so, a considerable oil quantity may leak out. Collect the oil in a suitable container and
deposit it properly. Close all holes. Now clean and pack the I/H converter.