Flowrate measurement

Downhole flowrate measurements indicate drillstring washouts before the drillstring breaks and, consequently, avoiding expensive and dangerous fishing. 

Flowrates Measured values True values Variances... 

Flowrates Measured value Estimated value Relative error... 

Flowrates Measured values Variances Reconciled values... 

The outlined strategy has been applied to the subsystem of Example 4.4 in Chapter 4. The flow diagram, shown in Fig. 4 of Chapter 4, consists of 7 units interconnected by 15 streams. There are 8 measured flowrates and 7 unmeasured ones. The flowrate measurements with their variances are given in Table 3. In Chapter 4 we identified the subset of redundant equations. In this case it is constituted by one equation that contains the five redundant process variables. By applying the data reconciliation procedure to this reduced set of balances, we obtain the estimates of the measured variables, which are also presented in Table 3. 

True flowrate Measured True flowrate Measured True flowrate Measured... 

Flowmeters. Even after modification the pumps usually showed some long-time drift in the pumping velocity, mainly due to changes in valve operation caused by corrosion, dirt accumulation or trapped air bubbles. Thus all flowrates have to be measured at regular intervals and the pumps adjusted when needed. Various devices for flowrate measurements were tested and two were finally selected. 

For the first run, 4.5 liters of dlstllled-mllllpore water were measured Into the process tank. Twenty-five grams of PEO and 25 gms. of PVA were slowly added to the water and dissolved. A 197.2 ppm Internal standard solution of methanol In water was made In a one liter round bottom flask and set In a cool place. The gas chromatograph was started up and the calculation program was entered. When the polymer had dissolved, 500 ml of heptane were added under shear to the process tank. The contaminant solution was made In the feed tank by dissolving 10.0 ml of toluene In 18.9 liters of water. A lid was placed on this tank to limit vapor losses. The process tank was preloaded with 25.0 ml of toluene and the lid was secured. The appropriate valves were opened, and the process and feed ptimps started. The permeate was returned to the process tank until the pressure profile was established. Once this was achieved, the permeate was drawn off and Its flowrate measured. The contaminant flowrate was then set equal to the permeate rate and both were continuously monitored throughout the experiment. The temperature of the process tank was measured and the coolant temperature setpoint and flowrate were adjusted until the steady state condition was obtained. Six one-mllllllter samples were taken periodically from the feed, permeate, and process tank. The clear feed and permeate samples were capped Immediately and labelled. The mllky-whlte... 

Eq. (4) also can be used as a basis for discussion of both systematic and random errors involved in flowrate measurements using these provers. Systematic errors may be considered as characteristics of instruments ordinarily used for measurement PiAV(./At. Calibration and reading errors of the instruments, not their dynamic response errors, are summarized below ... 

The standards philosophies for flowrate measurements have been presented, briefly. The specified gas flow calibration facilities currently in operation at NBS at Gaithersburg, MD have been described. Levels of performance have been given. 

Techniques for establishing and maintaining flowrate measurement traceability have been presented. A specific scheme has been described in some detail so that realistic data, produced on a continuing basis, can be generated so that a laboratory s entire flowrate measurement process can be assessed. 

Calibrating meters in tandem errables a number of checks to be made on the flowrate measurements, see [5,6]. Besides affording the opporturrity of having a redundant result for the same flowrate, the tandem meters can produce not orrly on-hne indications of relative meter performance, but also off-line assessments of uncertainties associated with the meters themselves and the system in which they are being calibrated. 

DVS rods fall-down due to trip signal by flowrate measurement when changing over one primary pump to pony motor primary sodium flowrate measurement design of the primary flowrate measurement... 

If we know the vector Cq, it is natural to subtract this Cg from the measured vector X and reconcile the vector x -eg. This procedure (subtraction of systematic errors) is called compensation. The compensation is widely used in practice. A typical example is compensation of flowrates measured by orifices for the deviation of actual density from that supposed in the instrument design. 

Linear Flowrate F. The volumetric flowrate of the carrier gas (mobile phase) measured at column outlet and corrected to column temperature and Fa is volumetric flowrate measured at column outlet and ambient temperature ... 

The ratio of the volumetric flowrate out of the purge vent to the volumetric flowrate in the capillary column is termed the split ratio and provides an estimate of and control over the actual volume of sample entering the column. Care should be taken when using the split ratio to estimate actual injected sample volume, or when using it in comparisons between methods on different instruments. There are subtle differences between instruments and measurement techniques that may affect the measured flows. For example, the column volumetric flowrate measured by injecting a nonretained substance is the average column flowrate, not the flowrate at the inlet, while a flowmeter connected to the split purge vent measures the volumetric flowrate at the vent, not in the inlet. With newer, electronically controlled systems, the flows are measured directly at the inlet, or are calculated from the entered inlet conditions and column dimensions. 

The fluid flowrate measured for the conditions shown in Figure 18.5 is 1.1 m /min. 

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