PC10 Level measuring and calibration system_update_2019edit (1).pdf

EXPERIMENT LEVEL MEASURING AND CALIBRATION SYSTEM 6 1 7...

EXPERIMENT LEVEL MEASURING AND CALIBRATION SYSTEM 6 1 7 8 2 9 10 3 4 5 Figure 1: Unit Assembly of Level Measuring and Calibration System 1. Chart Recorder 6. Pressure Relief Valve 2. Flowmeter 7. Pressure Gauge 3. Sump Tank 8. Pressure Transmitter 4. Heater 9. Pressure Regulator 5. Pump 10. DP Transmitter 1 EXPERIMENTAL PROCEDURE Experiment 1: Calibration of the Hydrostatic Tube/Bubble Tube Level Transmitter (DPT1) and the Direct Mounted Level Transmitter (DPT2) Objective : The main objective of this section is to calibrate the direct mounting level measurement instrument, which is the Level Transmitter (DPT1 and DPT2) 1. Make sure that the equipment is in good condition and all instruments are properly connected. 2. Ensure that the level tank is empty without water at the initial. Do not TURN ON the water pumps 3. Close all valves. The level tank should be in dose tank condition. 4. Drain all possible liquid/water trapped in the DPT1 and DPT2 line by opening both valves on the transmitter. This step is important as the pressure reference; DPI 800‐P is not suitable for liquid application. 5. Attach DPI‐800P pressure reference to the DPT1 with appropriate tubing, DPI‐ 800 P and DPT1 have two connection ports, namely high (+) and low (‐) ports. Make sure that the ports are connected accordingly. 6. By taking the DPI‐800P as reference, adjust the V14 to a certain value within the range between 100 ‐1000 mmH2O and record the readings into table 1. 7. Repeat step 5 by different values of mmH20 (minimum five dissimilar values). Note: Avoid of using extremely high pressure as it will cause the pressure gauge to over‐range and eventually damaged it. 8. Plot the calibration graph of DPI‐800P reading versus DPT1 reading. 9. Repeat step 4 until step 8 for DPT2. Make sure that valve V13 is closed for DPT2 calibration. 10. Note that the DPT2 position is under the level tank. Hence, offset of 350mm have to be applied to all DPT2 readings. In another word, the value displayed on DPT2 should be corrected by +350 mmH2O. 2 Results: DPI‐800P (mmH2O) DPT1 (mmH2O) DPI‐800P (mmH2O) DPT2 (mmH2O) DPT2 Corrected (mmH2O) 3 Experiment 2: Flow Resistance Determination 1. Make sure that all main valves are dose before start the experiment. Open all valves of the sight glass (V4, V5, V11 and V12) to read the water level. 2. Drain the water inside the level tank via V6. 3. Adjusted the opening to 40 0. 4. Open V2, V3, V8, V9, V10 and V13. The level tank should be in open tank condition. 5. Open pump to pump water level tank. Use the inlet control valve to control the inlet flow. 6. Vent the high pressure side of the DPT2 to remove any air trap in the impulse line. 7. Taking DPT2 as reference for the water level, adjust the flow control valve, V8 so that the water level is maintained at 100 mmH2O. 8. Record the respective flow rate and level. 9. Repeat the above procedures with the level increment of 100 mmH2O until 900 mmH2O 10. Drain the water in the level tank by fully open V6 before start the next experiment. 11. Repeat step 4 until step 10 by adjusting V6 to 60 0. 12. Plot graph of level (mm) vs flow rate (LPM) 13. The graph should show the square root behaviour and the slope of the graph at any particular level is the flow resistance corresponding to that level. DPT2 reading Flow rate Reading, (LPM) mmH2O V6 = 40 0 V6 = 60 0 100 200 300 400 500 600 700 800 900 4 Experiment 3: Level Measurement in Open Tanks 1. Ensure that all valves are initially closed except the sight glass valves. 2. Open V2, V3, V8, V9, V10 and V13. The level tank should be in open tank condition. 3. Vent the high pressure side of the DPT2 to remove any air trap in the impulse line. 4. Set V6 opening to 40 0. 5. Bubble the hydrostatic tube with pneumatic air. The pneumatic air is a requirement in order to get the level measurement using hydrostatic method. DPT1 and PI1 will show the pressure in this line and it various corresponding to the water level. Always use a minimal air supply pressure and flow to the hydrostatic tube by controlling the air supply valve, V14. Excessive air supply will cause error in measurement. 6. Switch on the pump and let the water pump into the level tank. 7. Taking the sight glass as reference for the water level, adjust the water inlet flow to maintain the water level at approximately 0 mmH2O. 8. Record the DPT1, DPT2, sight glass level measurement as well as the flow rates reading. 9. Repeat the above procedures with an increment of 100 mmH2O until the maximum level of 900 mmH2O was reached. 10. The experiment also can be done in different type of pressure and temperature. Sight Glass DPT1 DPT2 Flow rates, (mm) (mmH2O) (mmH2O) (LPM) 100 200 300 400 500 600 700 800 900 5 Experiment 4: Level Measurement in Closed Tanks 1. Repeat the procedures in Experiment 3 but in this experiment V10 should be closed to change the installation to a closed tank. 2. This level measurement technique can only be applied on direct method only (DPT2). Always make sure that the lower side of DPT2 is vented into the upper space of the liquid. Failed in doing this will cause measurement error to the level. 3. Hydrostatic tube is not suitable for this configuration as pneumatic air will be introduced into the tank continuously and hence the tank pressure will be elevated. Sight Glass DPT2 Flow rates, (mm) (mmH2O) (LPM) 100 200 300 400 500 600 700 800 900 6 Experiment 5: First Order Tank Level Dynamics 1. Ensure that all valves are initially closed. Ignore the sight glass valves. 2. Open V2, V3, V8, V9, V10 and V13. The level tank should be in open tank condition. 3. Vent the high pressure side of the DPT2 to remove any air trap in the impulse line. 4. Set the V6 opening to 40 0 5. From table 3, determine the values of flow rates corresponding to tank level which equal to 300mm and 500mm. Let these flow rates to be equal to F1 and F2 respectively. 6. Open the pump and set the flow rate equal to F1. Let the level become at steady state. 7. Introduce a step change of the flow rate to F2 by adjusting V8. Take DPT2 as reference for water levels. 8. Record the change of the level as a function of time using the chart recorder. Red pen = DPT1; Green pen = DPT2 9. Note the initial and finish readings for both pressure and flow rate. 10.A response profile from recorder will be obtained. From the profile, determine the value gain, K and time constant, T. 11.Determine the values of the Gain, K and time constant, T as follows. i. Calculate the step change input of flow A = F2 ‐ F1 ii. Find the corresponding change in level, B iii. The gain, K can be determine by applying below formula Gain, K = B/A iv. Determine the time constant, T Where, Tx = 0.632B v. From the chart, determine the distance of Tx vi. Find the time‐constant, T Where; T = Distance of Tx / Chart recorder feed, f EQUIPMENT MAINTENANCE a) Restore the system to operating condition after any repair job. b) Only properly trained personnel shall be allowed to carry out any servicing. c) Shut down the whole operation and let the system to be cold down before servicing. 7 SAFETY AND PRECAUTION a) The unit must be operating under the supervision of trained personal. b) All the operating procedures supplied with the unit must be read and understood before operating the unit. c) Do not remove any of the temperatures sensors on the plate heat exchanger when the unit is running as it will cause harms to the operator. d) Always check and rectify and any crack or leak. e) Reference Marlin, T.E., ‘Process Control Designing Processes and Control Systems for Dynamic Performance’, 2nd Edition, McGraw Hill, 2000. Seborg, D.E., Edgar, T.F., and Mellichamp, D.A., ‘Process Dynamics and Control’, 4th Edition, John Wiley and Sons, 2017. 8