Temperature control heat exchanger

The unique advantage of the plasma chemical method is the ability to collect the condensate, which can be used for raw material decomposition or even liquid-liquid extraction processes. The condensate consists of a hydrofluoric acid solution, the concentration of which can be adjusted by controlling the heat exchanger temperature according to a binary diagram of the HF - H20 system [534]. For instance, at a temperature of 80-100°C, the condensate composition corresponds to a 30-33% wt. HF solution. 

Solution There are several theoretical ways of stabilizing the reactor, but temperature control is the normal choice. The reactor in Example 5.7 was adiabatic. Some form of heat exchange must be added. Possibilities are to control the inlet temperature, to control the pressure in the vapor space thereby allowing reflux of styrene monomer at the desired temperature, or to control the jacket or external heat exchanger temperature. The following example regulates the jacket temperature. Refer to Example 5.7. The component balance on styrene is unchanged from Equation (5.29) ... 

If there are any differences it then adjusts the steam valve. If the downstream pressure changes, a correction in the control valve is made immediately, instead of waiting for a product temperature change. Should the output temperature of the process stream rise, this would cause a set point change of the steam-pressure controller, which would cause a decrease in the steam pressure in the heat exchanger. Cascade control is very useful when the variation in the quality of a utility or other manipulable stream can cause deviations from the desired output. 

Hollow-fiber (capillary)-type membrane oxygenators are the most widely used today, and comprise two main types (i) those where blood flow occurs inside the capillaries and (ii) those where there is a cross-flow of blood outside the capillaries. Although in the first type the blood flow is always laminar, the second type has been used more extensively in recent times, as the mass transfer coefficients are higher due to blood turbulence outside capillaries and hence the membrane area can be smaller. Figure 15.3 shows an example of the cross-flow type membrane oxygenator, with a built-in heat exchanger for controlling the blood temperature. 

The temperature 7 mix of the blended stream of gas from the heat exchanger and gas bypassing the heat exchanger is controlled by manipulating bypass flow-rate Fh y. 

BLSS The bioartificial hver support system is made up of a blood pump, a heat exchanger to control the blood temperature, as well as an oxygenator and a bioreactor. The hollow-fibre bioreactor generally contains 70—100 g of porcine hver cells. Initial experience with BLSS is encouraging. (92)... 

The way in which the outlet temperatures of a heat exchanger are controlled could have a profound effect on the extent of the fouling. In general one of the outlet temperatures, usually the principal process stream is required to be fixed within a narrow range. The inlet temperature of this stream for some reason may be variable. The usual way of controlling the principal process fluid temperature is to restrict or increase the flow of the other fluid. The technique is illustrated in Fig. 13.2). 

FIGURE 13.2. The conventional control of heat exchanger temperatures... 

The temperature of each process stream leaving the four process heat exchangers is controlled by manipulating the hot oil flow rate through each exchanger. 

Many other aspects of this basic system have also been developed. For example, if the heat exchange is controlled by an automatic device such that additional rates are proportional to the reactor temperature perturbations, Q, in Eq. 10.4.b-2 is modified to ... 

A heat exchanger to control the temperature of the electrolyte-sol mixture throughout the operation. 

CUl and CU4 are value-keeping controllers for the control of the outlet temperatures of the collector and of the HWS heat exchanger, respectively. Control signals are produced by the temperature sensors Tqc and Tw- Control is realized by changing the mass flow rates with one-way motor valves Vq and respectively. 

The temperature of each shutdown cooling heat exchanger inlet and return line is monitored at locations both upstream and downstream of each heat exchanger. Temperatures are indicated (at a remote location) and recorded (in the control room) for each shutdown cooling heat exchanger inlet and return line. These indications are used to provide a measurement of system performance, and provide information allowing the operator to adjust the cooldown rate. 

The SCS heat exchanger flow control valves (SI-310, 311) and the SCS bypass flow control valves (SI-312, 313) are adjusted as necessary, to maintain an RCS cooldown rate of 75°F/hour or less, until the refueling temperature of 120°F is attained. 

For liquid-cooled stacks, the coolant flow rate and the heat exchanger together control the coolant temperatures at the stack inlet and outlet. Figure 1.21 illustrates a coolant loop. A pump is the driving force that circulates the liquid coolant in the loop. It sends coolant from the coolant tank into the stack... 

The production of steam is very important to the operation of an industrial facility. Steam is used in a variety of operations, including heating and temperature control, steam turbines, steam tracing, heat exchangers, reboilers, stripping, and distillation. The energy in steam can easily be... 

The ability to run a complete performance test requires experience and preparation. For a first performance test, you should simply obtain a complete unit pressure profile. This is done with a single pressure gauge, which you move downstream from point to point. Obtain pressure drops across heat exchangers and control valves. Then, obtain a complete temperature survey. Where no thermowells exist, use a glass thermometer inserted under the pipe insulation. Next, record all flow rates. You will probably find many flow inconsistencies. Finally, obtain a complete set of samples. Learn how and where the samples are taken (see Chapter 27). 

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