flow assignment

8/9/2019 Flow Assignment

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PHYS327

Assignment #2:

Flow Measurement

Thomas Bolstad, ystein Bachmann Strand

March 30, 2011

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1 introduction

This assignment is meant to serve as an introduction of how various flow mea-surement devices work, and what the limitations of these flow measurementdevices are. and carrying out simple experiments. Because of this, the as-signment is split into several smaller parts which in this text will be treatedindividually initially, and will be followed by a discussion about the sum of allthese exercises. The sections and their respective lengths will vary dependingon the nature of the different exercises.

2 Equipment

In this experiment, we will be using the flow rig, The flow rig consists of thepipe systems, a pressure valve and a flow valve, and several meters. The dif-

ferent meters are listed below in the equipment section, and will be referencethroughout this text.

Pressure transmitter : Wika Tronic 891.13.500

Gamma densitometer : Ronan Density Gauge X96 Process Computer

Orifice meter, gas P/I converter : Holta & Haland, customer specificationFuji Electronics FCX-A/C II Series

Turbine meter : Daniel 1401 1P

f/l converter : PR Electronics PR5225

Coriolis meter : Micromotion DS150S RFT9712

Orifice meter, Fluid P/I Converter : Daniel 2 Simplex Fuji ElectronicsFCX-A/C II Series

Vortex meter : Yewflo YF104-ALSE4D-S3S3C

Ultrasound meter : Danfoss Sonoflo SONO1000/1200

Signal converter : Sonoflo SONO 1100

Temperature sensor : Thermoelektro AS Pt-100 INOR Pt100 TRS22-2

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3 Exercise 2-a: Flow rig control panel

3.1 IntroductionIn this exercise, the student will

Make a user friendly panel in labVIEW which may be used to operatethe flow rig and present the measurements from the various sensors, whileusing the following conditions for the VI:

The sampling frequency should be as high as possible

Measurements should be presented numerically as well as in horizon-tal bar diagrams with different colors for the different instruments.

All measurements should also be plotted in a trend diagram with thesame colors as used in the bar diagrams.

Drive signals to the pump and the gas injection valve are to be rep-resented as percent of full drive signal.

Investigate to what degree it is appropriate to smooth the measurementsusing averaging.

Test the system under various conditions

investigate if different flow regimes for vertical gas/liquid flow can be de-termined.

3.2 Results

During our exercise, we attempted to average results, vs taking reults as wegot them. Some of the instruments gave output that fluctuated significantlywhen we took the results live. This was something we did not experience asmuch while doing averaging; the results ended up much smoother than withoutaveraging. So it seems reasonable to use averaging to achieve measurementswhich seems more coherent than the alternative.

Due to the high speed involved in getting the flow going, it was hard toexactly determine the different types of flow beyond determining that therewere usually a mixture of bubble flow and slug flow, but not being able to reallydetermine how much it was of each.

3.3 LabVIEW

First the input and output is initialized and started. Then the while loop isentered. The while loop has two sections. One of them reads the input andtranslates the voltages to actual measurement numbers. And then representsthem in bar diagrams and in graphs. The other reads input, and transformthem to voltages and then send them out to the pump and gas injection. The

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Figure 1: An image of the working VIs block diagram

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Figure 2: An image of the working VIs front panel

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4 exercise 2-b: Characterization of the orifice

meter (M5)4.1 introduction

In this exercise, the student will

Determine the opening in the orifice meter through:

Measuring the pressure drop across the orifice when water with aflow rate of 0 - 20 m3/h flows through the rig

Take about 20 measurements (each averaging about 1000 instrumentreadins), where the flow rates from the Coriolis, vortex, ultrasoundand turbine meters are also recorded.

assuming these instruments represent 4 different true flow rates,determine the orifice opening by linear regression using these truevalues.

Comment on how the results compare to the actual orifice opening,and which of the results is the most reliable one.

Determine a turndown ratio for the orifice at 10% accuracy when usingthe turbine meter as a calibration instrument.

Plot the relationship between measured flow rate from the orifice meterand the turbine meter as a function of percent of the measurement range.

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4.2 Results

Flow[h3/m] Pressure Drop[mbar] Vortexmeter Turbinemeter Coriolismeter Ultrasound1 0.4767 0.0016 0.0220 1.6560 0.91662 5.6294 0.9529 1.8759 0.3113 2.02323 13.5346 2.9530 2.9661 1.4475 3.03544 25.3421 4.0466 4.0545 2.6103 4.14055 42.3022 5.1269 5.1922 3.7762 5.20946 62.4608 6.2807 6.3055 4.9735 6.33697 88.0553 7.3449 7.4661 6.1706 7.46178 115.8287 8.4660 8.6041 7.3438 8.52299 150.0807 9.6370 9.7508 8.5717 9.628410 184.0597 10.6481 10.8101 9.5913 10.748711 225.7741 11.8037 11.9792 10.7681 11.9463

12 270.0141 12.8393 13.0621 11.9077 12.904113 325.2744 13.9973 14.3078 13.0835 14.146914 374.5250 15.1182 15.3269 14.0614 15.255115 433.5971 16.2296 16.5746 15.2306 16.417016 497.7981 17.3407 17.7166 16.3847 17.395417 565.5332 18.4990 18.8019 17.4199 18.627018 637.0284 19.6825 19.9629 18.5075 19.809219 716.0472 20.7999 21.1930 19.6629 20.823220 795.9602 21.9239 22.2884 20.7011 21.9232

Table 1: The results obtained with the different meters at q going from 0 to 20m3/h

The equation for flow rate calculated through pressure drop in an orifice meter,is given by

q= C Am

21 (d/D)4

2P

(1)

where q is the flow ratio, C is the discharge coeffecient (constant depending onthe instrument),Am2 =(

d2

)2, is the area of the opening of the hole in the orificemeter. d is the diameter of the opening in the orifice meter, D is the diameter ofthe pipe, P is the pressure drop over the orifice meter. And is the density ofthe fluid going through the pipe. Since were trying to find the orifice opening,we rearrange the equation to give us an expression for d:

d= (1

8

C22P

q2 +

1

D4)4 (2)

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measurement # Vortex [mm] Turbine [mm] Coriolis [mm] Ultrasound [mm]1 578.10 155.91 22.45 26.46

2 44.35 32.45 76.91 31.423 32.24 32.18 44.79 31.864 32.22 32.19 39.28 31.915 32.49 32.32 37.27 32.276 32.38 32.32 35.92 32.267 32.59 32.36 35.21 32.378 32.52 32.30 34.63 32.439 32.52 32.36 34.24 32.5410 32.55 32.34 34.08 32.4211 32.54 32.34 33.88 32.3712 32.62 32.38 33.71 32.5513 32.71 32.40 33.70 32.56

14 32.62 32.43 33.67 32.4915 32.65 32.36 33.57 32.4916 32.69 32.39 33.51 32.6517 32.68 32.45 33.55 32.5818 32.65 32.45 33.54 32.5519 32.69 32.43 33.51 32.6820 32.70 32.46 33.53 32.70

Table 2: The table above, gives us the following values of the diameter of theopening in the orifice meter when we calculate d, the diameter of the orificeopening using the different flow ratios for the different instruments in equation(2).

Disregarding the first two or three measurements (depending on the instru-ment) which are taken before there is enough flow through the meters, theturbine meter is the meter that has the least variance in its caluclated diam-eter. Some of which most likely stems from variations in the orifice metersmeasurements. So it seems reasonable to trust the turbine meter compared tothe other meters.

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Orifice Meter [m3/h] Turbine Meter [m3/h] deviation[%]0.5332 0.022 2523.63

1.8326 1.8759 2.302.8415 2.9661 4.203.8883 4.0545 4.095.0236 5.1922 3.246.1043 6.3055 3.197.2479 7.4661 2.928.3127 8.6041 3.389.4623 9.7508 2.9510.4789 10.8101 3.0611.6058 11.9792 3.1112.6920 13.0621 2.8313.9304 14.3078 2.63

14.9478 15.3269 2.4716.0835 16.5746 2.9617.2331 17.7166 2.7218.3682 18.8019 2.3019.4947 19.9629 2.3420.6685 21.193 2.4721.7913 22.2884 2.23

Table 3: Using the values obtained for the orifice meter, and using the diam-eter given in the experiment sheet (30.5mm), we obtain the following valuesbetween the orifice meter and the turbine meter. As we can see from the table,, the turndown ratio (within 10%) seems to a bit lower than 1.87 m3/h to

21.79m3

/h. We investigated this a bit further, by experimenting with the flowon the rig, and found that when we had the flow at approximatly 1.7 m3/h, theerror between the two, didnt seem to go beyond 10%

4.3 LabVIEW

The VI in this section is almost identical to the one in section 3. The biggestnotable differences are that the data are written to a file, and that the input isautomized.

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5 exercise 2-c: Characterization of the gas in-

jection valveIn this exercise, the student will

Make a LabVIEW VI to determine the characteristics of the gas injectionvalve(V1/U1). That is, the void fraction g is to be plotted as a functionof the dive signal to the valve.

Have the pump provide a constant flow rate of 15m3 throughout the ex-ercise.

Record the valve characteristics as the valve drive signal goes from 0% to40%, and then from 40% to 0%

Record two characteristis; one where the gamma densitometer is used tomeasure the void fraction, and one where the void fraction is determinedbased on velocity measurements from the gas orifice meter.

Demonstrate the valves dead band and hysteresis in one (the same) plot,and comment on the results.

The Gas valve goes from 3psi to 15 psi. This means that doing the exercise from0 % to 40%, we go from 3 psi to 7.8 psi. Since the pressure from the gas valvedirectly affects the flow of the mixed water and gas, we automatically adjust tothat by using the turbine meter as a feedback. Through the experiment, thepump would fluctuate by up to 2 m3/h due to the steps were taking with thegas valve. Also of note, is that at 7.8 psi, we only took one measurement

the equation for the gas fraction, is given by:

l= qgas

qgas+ qwater(3)

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Gas pressure[psi] Water density[%] Orifice Gas Meter[am3/h]Going Up Going Down Diff. Going Up Going Down Diff.

3.000 0.90117 0.96609 0.06492 0.077 0.061 0.0163.240 0.96293 0.98916 0.02623 0.053 0.047 0.0063.480 0.96457 0.98664 0.02207 0.074 0.067 0.0073.720 0.97779 0.98046 0.00267 0.081 0.078 0.0033.960 0.96759 0.99193 0.02434 0.073 0.071 0.0024.200 0.97749 0.97620 0.00129 0.059 0.065 0.0064.440 0.97553 0.95273 0.0228 0.069 0.049 0.024.680 0.98157 0.86414 0.11743 0.065 0.070 0.0054.920 0.97977 0.74490 0.23487 0.082 0.082 0.1645.160 0.98414 0.58660 0.39754 0.053 4.770 4.8235.400 0.98072 0.50296 0.47776 0.064 7.942 8.0065.640 0.98350 0.35626 0.62724 0.047 11.176 11.223

5.880 0.76318 0.22072 0.54246 3.516 14.282 10.7666.120 0.59243 0.19301 0.39942 6.816 17.398 10.5826.360 0.46697 0.14997 0.317 10.437 20.198 9.7616.600 0.33710 0.13330 0.2038 13.975 22.705 8.736.840 0.19675 0.12655 0.0702 17.661 24.714 7.0537.080 0.16355 0.12048 0.04307 20.948 26.455 5.5077.320 0.12234 0.11267 0.00967 24.139 26.707 2.5687.560 0.10983 0.10936 0.00047 26.292 27.218 0.9267.800 0.10813 0.10813 N/A 27.966 27.966 N/A

Table 4: Measurements of the water fraction and gas flow with a continiouswaterflow of 15 m3/hand rising and sinking gas pressure, going from 3.0 psi to

7.8 psi.

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Figure 4: Gas fraction going up(red) and down(green) from the gamma densit-ometer.

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Figure 5: Gas fraction going up (red) and down (green) calculated from thedata obtained by the orifice gas meter.

As we can see from the above table, the gas fraction is obviously wrong.After communicating with the other groups this seems to be common for allthe groups. So the logical conclusion seems to be that there either is somethingwrong with the implementation of equation 3, something wrong with the flow(water going into the gas orifice meter when it shouldnt), something wrongwith the meter itself or a combination.

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5.1 LabVIEW

This LabVIEW VI starts by initializing input and output. The input is thencalculated for the relevant values to the actual measurement variables fromvoltages. For the output, the gas pressure is increased stepwise, and the TurbineMeter value is used as a feedback in the loop to adjust the water pump pressureclose to the value measured by the turbine meter being 15 m3/h. Everything isautomated in this VI. And it continiously writes averaged values to a file, anddisplays them in charts, bars and numerical values.

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6 exercise 2-d: Injection of gas in the rig

In this exercise, the student will

investigate the ability of the ultrasound, fuid orifice, vortex and coriolismeters to handle small quantities of gas in the fluid flow.

plot the deviation from true flow rate (the flow rate measured by theturbine meter) for each instrument as a function of void fraction.

use about 10 void fractions in the range 0% to 20%, and let the systemstabilize before taking measurements.

Do this for two different liquid flow rates. For example 5 m3/h and 15m3/h

6.1 Results

Through experimenting, we found it hard to get 10 different void fractionsbetween 0% and 20% using the gamma densitometer as a point of reference.There seems to be a point where the void fraction is at about 90% where if youraise the gas pressure, it seems to jump almost immedialty to 80%. So we endedup using 7 void fractions at 5 m3/h and 5 void fractions at 15 m3/h

Flow rate 5 m3/hTurbine Gamma Coriolis Orifice (Fluid) Vortex Ultrasound5.119 0.976 3.506 5.237 5.290 11.8085.013 0.957 3.356 4.991 5.178 -12.5025.013 0.952 3.439 5.028 5.035 -12.5054.951 0.922 1.945 4.956 3.420 -12.5034.939 0.918 0.861 4.921 2.404 -12.5034.625 0.854 0.278 4.624 0.093 -12.5004.611 0.828 0.267 4.643 0.002 -12.501

Flow rate 15 m3/hTurbine Gamma Coriolis Orifice (Fluid) Vortex Ultrasound16.218 0.936 14.802 16.968 16.321 -12.49916.204 0.935 14.783 16.960 16.728 -12.50316.218 0.935 14.845 16.988 16.726 -12.504

16.197 0.932 14.774 16.957 16.720 -12.50615.758 0.862 7.950 16.212 17.366 -12.504

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Figure 7: Deviation of the different meters at flow rate of water at about 5 m3/has a function of the water fraction. Compared to the turbine meter, the red line

is the deviation of the ultrasound meter, the green line is the deviation of theOrifice Meter, the yellow line is the deviation of the coriolis meter and the blueline is the deviation of the vortex meter

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Figure 8: Deviation of the different meters at flow rate of water at about 15m3/h. as a function of the water fraction. Compared to the turbine meter, the

red line is the deviation of the ultrasound meter, the green line is the deviationof the Orifice Meter, the yellow line is the deviation of the coriolis meter andthe blue line is the deviation of the vortex meter

6.2 LabVIEW

This LabVIEW VI is pretty similair to the one in section 5. The main difference,is that there are more meters involved in the measurement, and that insteadof using feedback from the turbine meter as in 5, we use set values which werefound by trial and error as the input to the gas valve.

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flow assignment

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