Jacket, coolant

Figure 5. Experiences at production scale. When (B) the Jacket coolant temperature (- -) dropped due to a plant modification, the reactant flow rate (- ) was increased automatically by the PID controller and maintained the reactor temperature (- in (A)) within 1 % of the setpoint.

Consider a simple first-order exothermie reaction, A —> B, carried out in a single, constant-volume, continuous stirred-tank reactor (Fig. 3.12), with constant jacket coolant temperature, where r = - k Ca,. 

Jacket, Coolant. The metal enclosure that consists of an inner wall (liner) and an outer metal wall (outer case), with a coolant passage between them, occasionally held apart by spacers or coolant helices. Term also applied to the double metal walls of a regeneratively-cooled thrust-chamber assembly... 

Flowrate of Fluid Through the Jacket. FLOWJN is used to simulate the loss of jacket coolant or simply the size of the jacket. 

The controlled variables are the concentration of P in the reactor effluent, Cp, and the reactor temperature, T. The manipulated variables are the feed flow rate, q, and the Jacket coolant flow rate, qj. The process disturbances are the feed concentration of A, Cm, and the feed temperature, Tg. Additional information is given in Table 21.13. 

High power consumption and high SPS conversion are needed to avoid adhesions. In this process, the polymerization heat (160kcal/kg) is removed by the jacket coolant. In a larger plant reactor, a heat transfer area proportional to the reactor volume is needed. 

Fresh styrene and catalyst components are fed to the jacketed stirred tank reactor with a multi-paddle agitator (V-300). In the reactor, styrene is polymerized to SPS in the presence of catalysts. The SPS powder is discharged from the bottom of the stirred tank reactor. The polymerization heat is removed only by the jacket coolant. 

Open-Loop versus Closed-Loop Dynamics It is common in industry to manipulate coolant in a jacketed reacdor in order to control conditions in the reacdor itself. A simplified schematic diagram of such a reactor control system is shown in Fig. 8-2. Assume that the reacdor temperature is adjusted by a controller that increases the coolant flow in proportion to the difference between the desired reactor temperature and the temperature that is measured. The proportionality constant is K. If a small change in the temperature of the inlet stream occurs, then depending on the value or K, one might observe the reactor temperature responses shown in Fig. 8-3. The top plot shows the case for no control (K = 0), which is called the open loop, or the normal dynamic response of the process by itself. As increases, several effects can be noted. First, the reactor temperature responds faster and faster. Second, for the initial increases in K, the maximum deviation in the reactor temperature becomes smaller. Both of these effects are desirable so that disturbances from normal operation have... 

One such approach is called cascade control, which is routinely used in most modern computer control systems. Consider a chemical reactor, where reac tor temperature is to be controlled by coolant flow to the jacket of the reac tor (Fig. 8-34). The reac tor temperature can be influenced by changes in disturbance variables such as feed rate or feed temperature a feedback controller could be employed to compensate for such disturbances by adjusting a valve on me coolant flow to the reac tor jacket. However, suppose an increase occurs in the... 

The flow of heat across the heat-transfer surface is linear with both temperatures, leaving the primaiy loop with a constant gain. Using the coolant exit rather than inlet temperature as the secondaiy controlled variable moves the jacket dynamics from the primaiy to the secondaiy... 

Table Type This is a simple flat metal sheet with slightly upturned edges and jacketed on the underside for coolant flow. For many years this was the mainstay of food processors. Table types are still widely used when production is in small batches, when considerable batch-to-batch variation occurs, for pilot investigation, and when the cost of continuous devices is unjustifiable. Slab thicknesses are usually in the range of 13 to 25 mm (V2 to 1 in). These units are homemade, with no standards available. Initial cost is low, but operating labor is high.

Kneading Devices These are closely related to the agitated pan but differ as being primarily mixing devices with heat transfer a secondary consideration. Heat transfer is provided by jacketed construction of the main body and is effected by a coolant, hot water, or steam. These devices are applicable for the compounding of divided solids by mechanical rather than chemical action. Apphcation is largely in the pharmaceutical and food-processing industries. For a more complete description, illustrations, performance, and power requirements, refer to Sec. 19. 

FIG. 11-62 Vibratory-conveyor adaptations as indirect heat-transfer equipment, a) Heavy-duty jacketed for bqiiid coolant or high-pressure steam, (h) Jacketed for coolant spraying, (c) Light-duty jacketed construction, (d) Jacketed for air or steam in tiered arrangement, (e) Jacketed for air or steam with Mix-R-Step surface, Coutiesy of Jeffrey Mfg. Co.)... 

Specimen Location Coolant piping connections in extrusion barrel cooling jacket... 

Dewar is constructed of Pyrex according to Figure 1. For further discussion concerning this immersion well contact Joel M. Babbitt, Glassblower, Department of Chemistry, University of South Carolina, Columbia, SC 29208, The evacuated jacket permits the safe use of circulating tap water as a lamp coolant even when irradiations are conducted in a dry-ice bath. A further... 

The thermos phon circulation rate can be as high as 10 to 15 times the coolant evaporation rate. This, in turn, eliminates any significant temperature difference, and the jacket is maintained under isothermal conditions. In this case, the constant wall temperature assumption is satisfied. During starting of the thermosiphon, the bottom can be 20-30°C hotter, and the start of circulation can be established by observing that the difference between the top and bottom jacket temperature is diminishing. Figure 2.2.5 (Berty 1983) shows the vapor pressure-temperature relationship for three coolants water, tetralin, and Dowtherm A. 

Coolant Jacket Cylinder Head Spark Plug Pushrod Cylinder Block Tappet Crankcase Cam Camshaft... 

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