Intercooling exothermic processes

Exothermic processes, widi cooling through heat transfer surfaces or cold shots. In use are shell-and-tube reactors with small-diameter tubes, or towers with internal recirculation of gases, or multiple stages with intercooling. Chlorination of methane and other hydrocarbons results in a mixture of products whose relative amounts... 

The absorption process is exothermic. To improve C3+ recovery, liquid from one or more of the middle trays is pumped through an intercooler and returned to the tray below. In some FCC units, the lean oil feed is chilled. 

Although an optimum temperature profile may be specified from theoretical calculations, it may not be possible to achieve in practice. The maximum temperature which can be used is usually determined by the materials of reactor construction or the durability of a catalyst. Also, steep axial temperature gradients cannot be realised unless heat transfer rates are high. If heat transfer is poor and the overall process is exothermic, temperature programming of a single reactor may be impossible the reactor becomes virtually adiabatic. In cases such as these, staged reactors (discussed elsewhere in this volume) with intercoolers may be used as a compromise. 

In reactive distillation, chemical reactions are assumed to occur mainly in the liquid phase. Hence the liquid holdup on the trays, or the residence time, is an important design factor for these processes. Other column design considerations, such as number of trays, feed and product tray locations, can be of particular importance in reactive distillation columns. Moreover, since chemical reactions can be exothermic or endothermic, intercoolers or heaters may be required to maintain optimum stage temperatures. Column models of reactive distillation must include chemical reaction... 

The moderately exothermic WGS reaction is limited by its thermodynamic equilibrium. The adiabatic temperature rise of the exothermic reaction requires a separation of the WGS conversion process into two consecutive steps, namely, high-temperature and low-temperature WGS in adiabatic fixed beds or monoliths. An intercooler or water injection is usually switched between both reactors. High-temperature WGS is operated between 375 and 450°C and low-temperature WGS between 200 and 300° C [4], Depending on the feed composition, the product of high-temperature WGS product contains between 2 and 3 vol.% carbon monoxide, while the product of low-temperature WGS product contains between 0.05 vol.% for the industrial scale [127], Higher values between 0.3 and 1 vol.% are common for applications of the smaller scale. 

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