Coils or jackets

Internal Coil or Jacket Plus External Heat Exchange. 11-19... 

Interna] Coil or Jacket Plus External Heat Exchanger This case can be most simply handled by treating it as two separate problems. M is divided into two separate masses Mi and (M — Mi), and the appropriate equations given earlier are apphed to each part of the system. Time 0, of course, must be the same for both parts. 

Agitation of the fluid to increase heat transfer between the fluid and a coil or jacket. 

Same as the above. L is length of coil or jacket passage, ft... 

Heat transfer coefficient to fluids in a vessel using mechanical agitated coils or jacket... 

Cooling is the simplest method. It can be achieved simply by use of cooling medium (usually water) passing through a coil or jacket attached to the vessel. 

L = length of straight tube for heat transfer (or, nominal tube length), ft or, length of path, ft or, length or thickness of coil or jacket, ft or, superficial liquid mass velocity, lb/ (hr) (ft ) or, equivalent length of pipe, ft or, thickness of insulation, in. 

The choice of scale-up technique depends on the particular system. As a general guide, constant tip speed is used where suspended solids are involved, where heat is transferred to a coil or jacket, and for miscible liquids. Constant power per unit volume is used with immiscible liquids, emulsions, pastes and gas-liquid systems. Constant tip speed seems more appropriate in this case, and hence the rotor speed should be 0.66 Hz. The... 

Heat transfer is usually effected by coils or jackets, but can also be achieved by the use of external loop heat exchangers and, in certain cases, by the vaporisation of volatile material from the reactor. The treatment, here mainly concerns Jackets and coils. Other instances of heat transfer are illustrated in the simulation examples of Chapter 5. 

Here cooling of an exothermic chemical reaction, via a cooling coil or jacket, is included. 

Cohen-Coon controller settings 103, 508 Coils or jackets 132 Column hydrodynamics 195... 

This is the simplest type of industrial crystallising equipment. Crystallisation is induced by cooling the mother liquor in tanks which may be agitated and equipped with cooling coils or jackets. Tank crystallisers are operated batchwise, and are generally used for small-scale production. 

Each term refers to a control volume, which for a BR is the volume of the reacting system. The input of energy nicy be by heat transfer from a heating coil or jacket, and/or by generation by reaction. Similarly, the output of energy may be by heat transfer to a coil or jaded, and/or by loss by reaction. The accumulation is the nd result of the inputs and outputs, and may result in an increase or decrease in T of the reading system. 

The factors that can affect the rate of heat transfer within a reactor are the speed and type of agitation, the type of heat transfer surface (coil or jacket), the nature of the reaction fluids (Newtonian or non-Newtonian), and the geometry of the vessel. Baffles are essential in agitated batch or semi-batch reactors to increase turbulence which affects the heat transfer rate as well as the reaction rates. For Reynolds numbers less than 1000, the presence of baffles may increase the heat transfer rate up to 35% [180]. 

It is clear that not all possible contaminants can be tested, but sources of contamination must be considered and tests run on the reaction in the presence of the most likely occurring ones. An approach to evaluating the problem of contamination is in the setting-up of a plant material matrix [1]. An example of potential contaminants to be considered, and sometimes overlooked, includes the heat transfer fluids to evaluate the consequences of heat exchanger, coil, or jacket failures. Contaminants which are introduced by other sources, for example, air (oxygen), carbon dioxide, water, metals, lubricants, and greases must also be considered. Also, the effects of chemicals which are used elsewhere in the plant and which could be introduced by mistake should be evaluated and perhaps tested. The possible contaminants in the reactor feeds must also be considered. 

Complete suspension of solids would be satisfactory for most purposes, and the correlations developed to predict conditions for suspension have generally used this criterion. Some of these correlations are discussed here along with guidelines for scaleup. Keep in mind that these correlations give the minimum agitation condition for suspension, and that requirements for dispersion of a gas or good heat transfer to a coil or jacket may indicate higher power inputs for some cases. 

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