Orifice meter steam

Fluid Flow. See under Fluid Mechanics or Dynamics and die following Refs Refs 1) R.F. Steams et al, Flow Measurements eith Orifice Meters , VanNostrand, NY (1951), 384pp 2) J.R. Caddell, "Fluid... 

Steam is metered with an orifice meter in a 10-in boiler lead having an internal diameter of dp = 9.760 in. Determine the maximum rate of steam flow that can be measured with a steel orifice plate having a diameter of d0 = 5.855 in at 70°F (294 K). The upstream pressure tap is ID ahead of the orifice, and the downstream tap is 0.5D past the orifice. Steam pressure at the orifice inlet pp = 250 psig (1825 kPa) temperature is 640°F (611 K). A differential gage fitted across the orifice has a maximum range of 120 in of water. What is the steam flow rate when the observed differential pressure is 40 in of water Use the ASME Research Committee on Fluid Meters method in analyzing the meter. Atmospheric pressure is 14.696 psia. 

Determine the diameter ratio and steam density. For any orifice meter, diameter ratio = /f = meter orifice diameter, in/pipe internal diameter, in = 5.855/9.760 = 0.5999. 

Related Calculations. Use these steps and the ASME Fluid Meters or comprehensive meter engineering tables giving similar data to select or check an orifice meter used in any type of steam pipe—main, auxiliary, process, industrial, marine, heating, or commercial—conveying wet, saturated, or superheated steam. 

The flow rate can be determined by means of an orifice meter. Prior to beginning the measurement, the fan is started and the desired airflow adjusted by a throttle valve the tan-perature and moisture content of the air are controlled by means of an electric heater and a steam valve. In the next section the development of an adequate value of flow rate may be ensured by means of screens. The time-varying mass of the sample to be dried is measured continuously and recorded. 

Determine the diameter ratio and steam density. For any orifice meter, diameter ratio = =... 

The mass flow of steam may be measured with an ordinary orifice meter, but the reading must be corrected, if pressure or temperature deviate from the conditions under which calibration was specified. In the case of saturated steam, pressure and temperature are not independent of one another, so either one is capable of indicating density. It so happens, however, that pressure is a linear function of density, with an intercept of 0 psig ... 

Let us assume that column AP control is cascaded to steam flow control and that the latter, the secondary or slave loop, is tuned to be much faster than the primary loop. As in the case of level control cascaded to flow control, the flow loop must have a linear flow meter or an orifice meter followed by a square root extractor. 

Compressed air can be supplied either to the boiler tank or to the steam line via nozzle after the orifice meter on the horizontal part of the pipe, which connects the boiler and the test section. 

An equation for use with venturi meters was given by Chisholm [Br Chem. Eng., 12, 454—457 (1967)]. A procedure for determining steam quahty via pressure-drop measurement with upflow through either venturi meters or sharp-edged orifice plates was given By Colhus and Gacesa [J. Basic Eng., 93, 11-21 (1971)]. 

The two principal elements of evaporator control are evaporation rate a.ndproduct concentration. Evaporation rate in single- and multiple-effect evaporators is usually achieved by steam-flow control. Conventional-control instrumentation is used (see Sec. 22), with the added precaution that pressure drop across meter and control valve, which reduces temperature difference available for heat transfer, not be excessive when maximum capacity is desired. Capacity control of thermocompression evaporators depends on the type of compressor positive-displacement compressors can utilize speed control or variations in operating pressure level. Centrifugal machines normally utihze adjustable inlet-guide vanes. Steam jets may have an adjustable spindle in the high-pressure orifice or be arranged as multiple jets that can individually be cut out of the system. 

Pressure-reducing stations, orifice plates, pitot tubes, and steam meters may all suffer from excessive mechanical wear and may therefore malfunction. 

A liquid hydrocarbon is fed at 295 K to a heat exchanger consisting of a 25 mm diameter tube heated on the outside by condensing steam at atmospheric pressure. The flow rate of the hydrocarbon is measured by means of a 19 mm orifice fitted to the 25 nnn feed pipe. The reading on a differential manometer containing the hydrocarbon-over-water is 450 mm and the coefficient of discharge of the meter is 0.6. 

Impeller and shunt flowmeters are widely used in steam and gas flow metering. They comprise an orifice plate in the main flow line and a self-operating rotor assembly in the bypass. As gas flows through the meter body, a portion of the flow is diverted to drive the fan shaft assembly. The rotational speed of the shaft is proportional to the rate of flow at all rates within the normal range of the meter. 

Suddenly, a long-time shift operator hit on the solution The orifice taps on the reboiler steam flow meter were plugged. The taps were drilled out. The tower s control immediately reverted to its former smooth operation. An investigation revealed what had happened. 

Determining settings for the reflux drum level controller is, in this case, difficult unless a large reflux drum holdup is available. Preferably one should make 5 minutes level controller tuning will require a dynamic analysis of overall column material balance such as discussed in Chapter 14. If steam flow is metered by an orifice, it should be linearized with a square root extractor. 

Note that we assume the flow control loop to be very fast compared with other dynamics. Also, since we have a cascade system, the steam flow transmitter should have a linear relationship between flow and transmitter output. If an orifice flow meter is used, the AP transmitter should be followed by a square root extractor. 

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