Cold shot, cooling

Multistage Operation with Cold-Shot Cooling... 

Figure 21.11 Flow diagram and notation for three-stage FBCR with cold-shot cooling...

Note that fAoi < /a,-i- That is, the mixing of fresh feed with the effluent from stage i - 1 results in a decrease in fA as well as in T. This is a major difference between cold-shot cooling and interstage cooling, in which /A does not change between stages. 

The operating lines for an FBCR with cold-shot cooling are shown schematically and graphically on a plot of /A versus T in Figure 21.12, which corresponds to Figure... 

Figure 21.12 Conversion-temperature diagram showing operating lines for cold-shot cooling operation of FBCR for exothermic, reversible reaction...

A number of factors may influence the choice of cold-shot cooling rather than interstage cooling in adiabatic operation of an FBCR. (Some of these are explored in... 

Figure 21.13 Interpretation of AT in equation 21.5-23 for exothermic, reversible reaction with cold-shot cooling, ith stage...

For an FBCR operated with cold-shot cooling for the reaction A products, determine, from the information given below,... 

In cold-shot-cooling operation of a multistage FBCR for the exothermic reaction A products, if cP (for the flowing stream) and (-A.Hra) are constant, show that the slopes of the operating lines (Figure 21.12) are all given by equation 21.5-8 (that is, they are all the same). 

With cold shot cooling the calculation of reactor volumes by the versus curve becomes more complicated because different amounts of feed are involved in each stage. We can also cold shot cool with inert fluid. This will affect both the versus Xp and T versus Xp curves. 

Figure 19.8 Cold shot cooling eliminates interstage heat exchangers.

Two situations, one when cold shot cooling is practical, the other when it is not, are shown in Fig. 19.9. 

Figure 19.9 Situations where cold shot cooling could be helpful and where it should not be used.

Optimal adiabatic bed reactors for sulfur dioxide with cold shot cooling (with K.-Y. Lee). Ind. Eng. Chem. Proc. Des.-Dev. 2, 300-306 (1963). 

Adiabatic with Cold-Shot Cooling. Some exothermic reactions are conducted in vessels with multiple beds of catalyst, which operate adiabatically (temperature increases through the bed). At the exit of each bed, a cold stream is mixed with the hot stream leaving the bed to bring the temperature back down to the desire inlet temperature for the downstream bed. This cold stream is typically some of the feedstream that has been bypassed around the reactor feed preheating system. 

If the system consists of a series of adiabatic reactors, there are two basic configurations. The first has heat exchangers or furnaces between each of the reactors to cool or heat the reactor effluent before it enters the next reactor. The second configuration uses cold shot cooling. Some of the cold reactor feed is bypassed around the upstream reac-tor(s) and mixed with the hot effluent from the reactor to lower the inlet temperature to the downstream catalyst bed. 

MULTIPLE ADIABATIC TUBULAR REACTORS WITH COLD-SHOT COOLING 273... 

Figure 6.3 Three-stage adiabatic reactors with cold-shot cooling system.

Equipment 1-Adiabatic 3-Adiabatic Interstage HX 3-Adiabatic Cold-Shot Cooled... 

TABLE 6.5 Controller Tuning for Seven-Stage Adiabatic Reactor System with Cold-Shot Cooling... 

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