Feed-Flow Recording Controller

Instrumentation on the solvent extraction equipment will usually consist of recording flow and recording temperature controllers on the feed stream, a pressure controller on the raffinate exit line, temperature recorders on the column intercoolers, and a liquid level recording controller at the liquid-liquid interface to set the extract layer withdrawal rate. 

The reactor system is automated with a computer HP 9816 and a data acquisition and control unit HP 3497A of Hewlett Packard. The programme a.o. checks if all variables are within preset safety limits. In case of emergency the programme switches the gas feed from H2 to N2 and stops the liquid feed. The key variables are the temperatures in the catalyst bed, the gas and the liquid inlet temperatures as well as the gas and the liquid outlet temperatures and fiirther the reactor pressure, the inlet and the outlet gas flow rates and the liquid feed flow rate. They are temporarily stored in the computer memory and later transferred on floppy disk. The temperatures at all other locations are monitored and recorded with a Philips PM 8237A multipoint data recorder. 

Instruments and Controls. Liquid levels in several of the tanks are automatically controlled with pneumatic instruments. Flows of several of the process streams are controlled and some are recorded. Temperatures of the feed and melt water are automatically controlled temperatures are recorded by two 16-point potentiometer recorders. Pressures are measured at several points in the system but all are manually... 

The pilot plant is equipped with two gauges one at the membrane entrance and the other at the exit. The plant is also equipped with two flowmeters one located at the entrance to the membranes to record the pumped flow and the other in the permeate stream to measure the discharge flow. The plant has a control panel, for starting and stopping the process and for controlling the blower and pump that feeds the bioreactor. The control panel can be set to automatic and the level inside the reactor is kept constant by means of the differential control. 

The hot section (Fig. 5) is controlled by a cascade loop which is based on a selected pumping rate (150 gpm) and sterilization temperature set in the TIC. Changes in the feed temperature are monitored at TTl which will automatically override the steam supply to keep the temperature at set point. Steam flow rate is monitored (by FE) and flow is automatically compensated should a large drawdown of steam occur elsewhere in the plant. Temperature is recorded at the beginning and end of the hot section. The hot section should be well insulated and special care should be given to the pipe supports for expansion. (Instrumentation symbols used here and in Figs. 3, 5, 6 and 7, conform to the standard symbols of the Instrument Society of America.)... 

The gas control panel was used for controlling the flow rates of the feed gases to the reactor (by manual metering valves), and measurement by electronic mass flow meters (Brooks 5860). A flow totalizer measured the flow and also displayed the cumulative flow (at STP). The gas control panel and the reactor were located in a fume hood. The data from the flowmeters, pressure transducers, thermocouples, and the digital tachometer were collected by a data acquisition interface (OMEGA Multiscan 1200) and recorded on-line. 

The cooling water flow rate is continuously indicated and can be recorded at the control panel. A differential pressure transmitter is mounted across an orifice in the water line feeding the control valve. This transmitter is adjusted to have a 4-20 m.A. output over the flow range. A 150 fl resistor is placed across the output terminals to produce a corresponding voltage of 0.6-3.0 V. 

All tests were remotely controlled from a control room located approximately 800 m away from the test cell. All pressure, temperature, and flow data was recorded using a computer DAQ. A picture of the screen used to determine the LL in the tank is shown in Figure 9.7. Diodes were used in dual sense mode as temperature or liquid level sensors, as controlled on the right hand side of Figure 9.7. All data was scanned and recorded at 2 Hz. A camera was used to detect LAD breakdown, and the video feed was sent to the control room monitor to view the LAD output in real time. 

Different feed gases, such as CO, methyl bromide, O2, toluene, xylene, acetic acid, benzene and balanced N2, were supplied by feed cybnders. Water was introduced by a water pump. Flow rates of the feed stteams were regulated by flow controllers. The flows of O2, N2 and water were pre-heated and combined with VOC streams before entering the reactor. Thermocouples were located above and below the catalyst sample to record the reaction temperatures. Gas samples taken immediately before and after the catalyst were sent to a GC equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID) to measure the concentrations of CO and various hydrocarbon compounds. The test unit was also equipped with continuous O2, CO and total hydrocarbon analyzers. A schematic of the test unit is shown in Fig. 7.7. For the high pressure unit, the tests were conducted up to 150 psig total pressure. The basehne feed composition was 7,000 ppm CO, 50 ppm toluene, 50 ppm benzene, 50 ppm methyl bromide, 3% O2, 2% H2O and balanced N2. The catalyst temperature varied from 150—450°C. 

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