Amir Hossein Parvardi 1

Transcription

1 Instrumentation 1 1 School of Electrical & Computer Engineering University of Tehran (ECE) October 5, / 1

2 Flowmeters (ECE) October 5, / 1

3 Flowmeters Types of Flowmeters Types of Flowmeters 29% 4% 5% 7% 8% 20% 18% 9% Differential Pressure Direct Mass Measurement Positive Displacement Turbine Ultrasonic Anemometer Vortex (ECE) October 5, / 1

4 Differential Pressure Flowmeters (ECE) October 5, / 1

5 Differential Pressure Flowmeters Figure 1: Differential Pressure Flowmeter Theory of Operation. (ECE) October 5, / 1

6 Differential Pressure Flowmeters Different Types: Orifice, Nozzle, Venturi. (ECE) October 5, / 1

7 Differential Pressure Flowmeters Different Types: Orifice, Nozzle, Venturi. Advanteges: Use on liquid, gas, or steam, Good application flexibility, Suitable for extreme temperatures and pressures, Moderate accuracy 2 5%, No moving parts, Parallel work. (ECE) October 5, / 1

8 Differential Pressure Flowmeters Different Types: Orifice, Nozzle, Venturi. Advanteges: Use on liquid, gas, or steam, Good application flexibility, Suitable for extreme temperatures and pressures, Moderate accuracy 2 5%, No moving parts, Parallel work. Disadvanteges: Expensive to install, Limited range ability 4:1, Affected by changes in density, pressure, and viscosity, Difficult maintenance. (ECE) October 5, / 1

9 Differential Pressure Flowmeters Figure 2: Differential Pressure Orifice, Venturi, Nozzle. (ECE) October 5, / 1

10 Flowmeters (ECE) October 5, / 1

11 Flowmeters Theory of Operation Faraday s Law of Induction (ECE) October 5, / 1

12 Flowmeters Theory of Operation Faraday s Law of Induction A voltage will be induced in a conductor moving in a magnetic field (E) (ECE) October 5, / 1

13 Flowmeters Theory of Operation Faraday s Law of Induction A voltage will be induced in a conductor moving in a magnetic field (E) The magnitude of the induced voltage is proportional to: (ECE) October 5, / 1

14 Flowmeters Theory of Operation Faraday s Law of Induction A voltage will be induced in a conductor moving in a magnetic field (E) The magnitude of the induced voltage is proportional to: the velocity of the conductor (V ), (ECE) October 5, / 1

15 Flowmeters Theory of Operation Faraday s Law of Induction A voltage will be induced in a conductor moving in a magnetic field (E) The magnitude of the induced voltage is proportional to: the velocity of the conductor (V ), the length of the conductor (D), (ECE) October 5, / 1

16 Flowmeters Theory of Operation Faraday s Law of Induction A voltage will be induced in a conductor moving in a magnetic field (E) The magnitude of the induced voltage is proportional to: the velocity of the conductor (V ), the length of the conductor (D), and the strength of the magnetic field (B). (ECE) October 5, / 1

17 Flowmeters Theory of Operation Faraday s Law of Induction A voltage will be induced in a conductor moving in a magnetic field (E) The magnitude of the induced voltage is proportional to: the velocity of the conductor (V ), the length of the conductor (D), and the strength of the magnetic field (B). E = k B D V (ECE) October 5, / 1

18 Flowmeters Theory of Operation Faraday s Law of Induction A voltage will be induced in a conductor moving in a magnetic field (E) The magnitude of the induced voltage is proportional to: the velocity of the conductor (V ), the length of the conductor (D), and the strength of the magnetic field (B). E = k B D V (ECE) October 5, / 1

19 Flowmeters Theory of Operation Figure 3: Magnetic Flowmeter Theory of Operation. Electrode Magnet Coil (ECE) October 5, / 1

20 Flowmeters Theory of Operation Figure 3: Magnetic Flowmeter Theory of Operation. Faradays Law of Induction E s = 1 C BVD Electrode C = Constant Magnet Coil (ECE) October 5, / 1

21 Flowmeters Theory of Operation Figure 3: Magnetic Flowmeter Theory of Operation. Faradays Law of Induction E s = 1 C BVD E s E s = The induced electrode voltage Electrode C = Constant E s Magnet Coil (ECE) October 5, / 1

22 Flowmeters Theory of Operation Figure 3: Magnetic Flowmeter Theory of Operation. Faradays Law of Induction E s = 1 C BVD E s E s = The induced electrode voltage V = Liquid velocity C = Constant V E s Electrode Magnet Coil (ECE) October 5, / 1

23 Flowmeters Theory of Operation Figure 3: Magnetic Flowmeter Theory of Operation. Faradays Law of Induction E s = 1 C BVD C = Constant E s E s = The induced electrode voltage B = Magnetic field density V = Liquid velocity V B E s Electrode Magnet Coil (ECE) October 5, / 1

24 Flowmeters Theory of Operation Figure 3: Magnetic Flowmeter Theory of Operation. Faradays Law of Induction C = Constant E s E s = The induced electrode voltage B = Magnetic field density V = Liquid velocity D = Pipe diameter V E s = 1 C BVD B E s D Electrode Magnet Coil (ECE) October 5, / 1

25 Flowmeters Theory of Operation E = k B D V }{{} Calibration Number (ECE) October 5, / 1

26 Flowmeters Theory of Operation E = V = k B D V }{{} Calibration Number E Calibration Number (ECE) October 5, / 1

27 Flowmeters Theory of Operation E = V = k B D V }{{} Calibration Number E Calibration Number Figure 4: Flow Calculation. (ECE) October 5, / 1

28 Flowmeters Theory of Operation E = V = k B D V }{{} Calibration Number E Calibration Number Figure 4: Flow Calculation. Q = V A (ECE) October 5, / 1

29 Magnetic Flowmeters Companies (ECE) October 5, / 1

30 Magnetic Flowmeters Companies Figure 5: Magnetic Flowmeters Companies Comparision. (ECE) October 5, / 1

31 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, (ECE) October 5, / 1

32 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, (ECE) October 5, / 1

33 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, (ECE) October 5, / 1

34 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, (ECE) October 5, / 1

35 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, Bi-directional flow, (ECE) October 5, / 1

36 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, Bi-directional flow, Empty pipe detection. (ECE) October 5, / 1

37 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, Bi-directional flow, Empty pipe detection. Disadvanteges: Fluid limits: No gases or steam, (ECE) October 5, / 1

38 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, Bi-directional flow, Empty pipe detection. Disadvanteges: Fluid limits: No gases or steam, Entrapped air, foam, or two-phase flow cause errors, (ECE) October 5, / 1

39 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, Bi-directional flow, Empty pipe detection. Disadvanteges: Fluid limits: No gases or steam, Entrapped air, foam, or two-phase flow cause errors, Minimum conductivity of 5µSiemens/cm 200kΩ. (ECE) October 5, / 1

40 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, Bi-directional flow, Empty pipe detection. Disadvanteges: Fluid limits: No gases or steam, Entrapped air, foam, or two-phase flow cause errors, Minimum conductivity of 5µSiemens/cm 200kΩ. Limited temperature range, (ECE) October 5, / 1

41 Magnetic Flowmeters Companies Advanteges and Disadvanteges Advanteges: No obstructions to the flow, No moving item, No maintenance, Wide range of use, Bi-directional flow, Empty pipe detection. Disadvanteges: Fluid limits: No gases or steam, Entrapped air, foam, or two-phase flow cause errors, Minimum conductivity of 5µSiemens/cm 200kΩ. Limited temperature range, High power consumption. (ECE) October 5, / 1

42 Magnetic Flowmeters Companies Installation Figure 6: Magnetic Flowmeter Installation. NO! (ECE) October 5, / 1

43 Magnetic Flowmeters Companies Installation Figure 6: Magnetic Flowmeter Installation. NO! NO! Straight Run Required (ECE) October 5, / 1

44 Magnetic Flowmeters Companies Installation Figure 6: Magnetic Flowmeter Installation. NO! BEST NO! Straight Run Required (ECE) October 5, / 1

45 Magnetic Flowmeters Companies Installation Figure 6: Magnetic Flowmeter Installation. GOOD NO! BEST Up Elbow Prefered NO! Straight Run Required (ECE) October 5, / 1

46 Magnetic Flowmeters Companies Material Selection Flowtube Liner Electrode Material Maximum Polyuret Linatex 316 Ni-Alloy Platinum Process Liquid Concentration PTFE ETFE PFA hane Neoprene Rubber SST C-276 Tantalum -20% Iridium Titanium Acetaldehyde 100% A1 A2 A1 N A2 N B4 A4 B5 A5 A1 Acetamide 100% A1 A1 A1 N A3 N B1 Acetic Acid 50% A1 A1 A1 N A4 N B3 A3 A1 A A1 Acetic Acid 75% A1 A2 A1 N A4 N N A1 A1 A A1 Acetic Acid, Glacial 100% A1 A2 A1 N N N A1 A1 A1 A A Acetic Anhydride 100% A1 A1 A1 N A5 N B1 A1 A5 A2 A1 Acetone 50% A1 A4 A1 N N N B1 A3 A3 A A3 Acetone 100% A1 A4 A1 N N N A1 A4 A1 A3 Acetophenone 100% A1 A1 A1 N N B1 B3 B5 B3 Acetonitrile 100% A1 A4 A1 B4 B5 Acetyl Chloride (dry) 100% A1 A4 A1 N N N B1 B5 A2 Acetylene 100% A1 A1 A1 A3 A5 A1 B3 B5 B5 Acetylene 100% A Tetrabromide Acetylene 100% A A2 Tetrachloride Acrylonitrile 100% A1 A4 A1 A4 A5 B3 B3 B3 A2 B3 Adipic Acid 100% A1 A1 A1 A4 A5 B3 A3 B3 A1 Alcohol & Glycerin 100% A A N N A A A A A Alcohol, 100% 2-Aminoethanol Alcohol, Allyl 100% A1 A3 A1 A5 A5 A1 B1 B1 A2 B3 Alcohol, Amyl 100% Alcohol, Butyl 100% Allyl Chloride 100% A1 A3 A1 N N A5 A2 Alum 10% A A N B B A A A Alum 100% A1 A1 A1 A3 A4 B3 B4 B5 A A3 Alumina 100% A A N N N A A A A Aluminium Fluoride 100% A A A N N N A Aluminium 100% A A A B N A A Hydroxide Aluminum 100% A1 Ammonium Sulfate Liners A = Resistant N = Not Resistant Blank =No (Corrosion Rate per Year) Temperatures Information A = Less than inches 1 = 248 F (120 C) Miscellaneous B = Less than inches 2 = 212 F (100 C) Sat = Saturated C = Less than inches 3 = 176 F (80 C) Conc = N = Greater than inches 4 = 140 F (60 C) Legend Concentrated Blank = No information 5 = 68 F (20 C) (ECE) October 5, / 1

47 Magnetic Flowmeters Companies Electrode Grounding Figure 7: Recommended Grounding for conductive pipe or conductive lined pipe with Ground electrode. (ECE) October 5, / 1

48 Magnetic Flowmeters Companies Electrode Grounding Figure 8: Recommended Grounding for conductive lined pipe with Grounding rings or Lining Protectors. (ECE) October 5, / 1

49 Magnetic Flowmeters Companies Electrode Grounding Figure 9: Recommended Grounding for Non-conductive pipe with Ground rings or Lining Protectors. (ECE) October 5, / 1

50 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter (ECE) October 5, / 1

51 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Electrode Adhesion: Figure 10: A model for the electromagnetic flowmeter with electrode fouling. (ECE) October 5, / 1

52 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Electrode Adhesion: Figure 10: A model for the electromagnetic flowmeter with electrode fouling. Dual Excited Flowmeter: Normal flowmeters excitation is only magnetic. In additional electric excitation method, there is also another electric excitation with additional higher frequency (usually under 2kHz). (ECE) October 5, / 1

53 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Simple Electrode Model Simple Electrode Model: Figure 11: A model of the electromagnetic flow-meter transducer with electrode fouling. Model (a) can be equivalent to model (b). (ECE) October 5, / 1

54 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Simple Electrode Model Relations: V out = K m E 0 R i R 01 +R 02 +R i (ECE) October 5, / 1

55 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Simple Electrode Model Relations: V out = K m E 0 R i R 01 +R 02 +R i α = R 01+R 02 R 01 +R 02 +R i 100% (ECE) October 5, / 1

56 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Simple Electrode Model Relations: V out = K m E 0 R i R 01 +R 02 +R i α = R 01+R 02 R 01 +R 02 +R i 100% α < 1% = R 01 + R 02 < R i 999 (ECE) October 5, / 1

57 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model Complete Electrode Model: Figure 12: Principle block diagram of a dual-excited electromagnetic flow-meter based on PV Cell. (ECE) October 5, / 1

58 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model Relations: E p = E a + E b, R p = R a + R b (ECE) October 5, / 1

59 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model Relations: E p = E a + E b, R p = R a + R b V out = K m R i R 01 +R 02 +R p +R i (E 0 + E p ) (ECE) October 5, / 1

60 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model Relations: E p = E a + E b, R p = R a + R b V out = K m R i R 01 +R 02 +R p +R i (E 0 + E p ) Magnetic Citation: E p = 0, E 0 = K 0 B D V = V = V out K m K 0 B D R 01+R 02 +R p +R i R i (ECE) October 5, / 1

61 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model Electric and Magnetic Excitations: Figure 13: Illustration of time share of dual excitation in one measuring cycle. t denotes the time, and V out denotes the output voltage of the measuring loop. (ECE) October 5, / 1

62 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model R i > 400MΩ, R 01, R 02 < 200kΩ Electric Citation: R i is too large = R 01, R 02 0 (ECE) October 5, / 1

63 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model R i > 400MΩ, R 01, R 02 < 200kΩ Electric Citation: R i is too large = R 01, R 02 0 Z eq = amplifier impedance = R Z C0 (ECE) October 5, / 1

64 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model R i > 400MΩ, R 01, R 02 < 200kΩ Electric Citation: R i is too large = R 01, R 02 0 Z eq = amplifier impedance = R Z C0 R 01 + R 02 = K m E p Z eq V out R p Z eq (ECE) October 5, / 1

65 Self-diagnostic Electrode Adhesion Using Dual Excited Flowmeter Complete Electrode Model Experiment Results: Figure 14: Variation of V P-P with R 01 and R 02 for simulation experiment based on resistors. (ECE) October 5, / 1

66 Electrical Electrode Cleaning (ECE) October 5, / 1

67 Electrical Electrode Cleaning The cleaning unit can be used for applications where deposits accumulate on the liner material and electrodes. Non-conductive deposits will reduce the electrode signal, while conductive deposits will partially shortcircuit the electrode signal, in both cases deteriorating the accuracy of the meter (depending on the character and thickness of the deposits). The cleaning unit is used for electrochemical cleaning of the sensor (electrodes) by applying voltage for approx. 60 seconds. Metering is resumed after another 60 seconds when cleaning is complete. During cleaning (120 seconds) mag flowmeter retains the last flow reading in the display and in the signal outputs until metering is resumed. The relay output of the signal converter determines when to clean. In the signal converter the cycle time can be set at 1 to 240 hours. If the cleaning cycle is set at e.g. 3 hours, the signal converter will clean the electrodes every three hours. (ECE) October 5, / 1

68 Electrical Electrode Cleaning AC Cleaning AC Electrode Cleaning: Figure 15: AC electrode cleaning unit of SIEMENS MAG 5000/6000 electromagnetic flowmeter. AC cleaning is used to remove greasy deposits on the electrodes arising in connection with measurement of waste water flows from abattoirs or water containing oil residues. During AC cleaning heat is generated on the electrode surface and this softens the greasy particles, causing gas bubbles which draw the deposits away from the electrode surface. (ECE) October 5, / 1

69 Electrical Electrode Cleaning DC Cleaning DC Electrode Cleaning: Figure 16: DC electrode cleaning unit of SIEMENS MAG 5000/6000 electromagnetic flowmeter. DC cleaning is used to remove conductive deposits from the meter pipe, as they can affect the meters accuracy. (ECE) October 5, / 1

70 Electrical Electrode Cleaning DC Cleaning DC Cleaning Notes: On measurement of district heating water flows, particular conductive magnetite deposits can occur, which can shortcircuit the electrode signal. This affects the meters accuracy, deteriorating the signal/noise ratio. This problem may occur if the waters conductivity is below approximately 250µ S/cm. This cleaning method involves electrolysis in which the electron flow leads the deposited particles away from the area around the electrodes. Do not apply DC cleaning to sensors with tantalum electrodes. (ECE) October 5, / 1

71 Electrical Electrode Cleaning Montage 1. Fit the SENSORPROM (2kB) memory unit on the connection board supplied with the cleaning unit. The SENSORPROM unit is delivered mounted in the terminal box of the sensor. The connection board supplied with the signal converter may not be used. 2. Mount the guide rails in the rack system as shown. Guide rails are supplied with the rack system and not with the signal converter. (ECE) October 5, / 1

72 Electrical Electrode Cleaning Montage Cable parameter Group Capacity in µf Inductance in mh Electrode IIB Coil IIB (ECE) October 5, / 1

73 Electrical Electrode Cleaning Montage 3. Mount the connection board as shown. The mounting screw must be installed just in line with the guide rails. 4. Connect the cables as shown in previous slide. 5. Select AC cleaning or DC cleaning mode at the switch located on the base of the cleaning unit. 6. Insert the cleaning unit and the signal converter in the rack system. (ECE) October 5, / 1

74 Electrical Electrode Cleaning Technical Data Technical Data: (ECE) October 5, / 1

75 Electrode Cleaning (ECE) October 5, / 1

76 Electrode Cleaning Inclined PATENIEDSEPIOIBH I Figure 17: Cleaning electordes is achieved by making the electrodes surfaces inclined to the direction of flow. f; F/6.5,. ' r "5 'ME ASURING OR CONTROL (ECE) October 5, / 1

77 Electrode Cleaning Ultrasonic Transducer Nov. 25, 1969 H. HERMANNS SELF-CLEANING ELECTRODES 3,479,873 Filed Nov. 13, Sheets-Sheet 1 a Low EF equeucv Cumm- S/GML Figure 18: The electrode having an ultrasonic transducer operatively coupled thereto to produce ultrasonic energy which is transmitted to the fluid to create cavitation effects therein acting to clean the exposed surface of the electrode. INVENTOR. Hervey?fq/va/ms (ECE) October 5, / 1 ATTOQ/YH

78 Electrode Cleaning Explosion-Proof Ultrasonic Transducer Figure 19: The same ultrasonic transducer is installed on the electrodes. But the transducer is mounted on the electrode within a protective shield to prevent high voltage applied to the transducer from reaching the electrode and producing a spark igniting an explosive fluid. (ECE) October 5, / 1