Quench loop

The Chemithon falling film monotube reactor with subsequent quench loop reactor... 

To ensure exothermic heat removal from the process, we are constrained by the process design to assign two control loops. We must control reactor inlet temperature with the furnace and control reactor exit temperature with the quench flow. Only by adjusting fuel to the furnace do we allow the reactor heat to be dissipated to the cooler. And only when the quench loop works do we guarantee that the furnace is operational. Because of this design we do not need a bypass line around the process-to-process heat exchanger. 

The abrasive effects of fly ash on downstream FGD components also can be minimized by using a separate quench loop, but in conjunction with a venturi prescmbber. Alternatively, a high-efficiency particulate collection device can be used upstream of a wet FGD system. 

Conversion is virtually complete at the bottom of the film part with the remaining conversion taking place in the quench loop under mild temperature conditions. 

The pure falling-film reactors will have the shortest residence time, order of magnitude 30 seconds. The Chemithon FFR and Jet Impact Reactor, both with quench loop, could have an organic liquid residence time of about 2 to 5 minutes, depending on the liquid level in the de-gassing tank. Finally the Ballestra CSTR system shows a total residence time for the organic liquid of the order of 60 minutes. 

Residence time in the recycle quench loop of the Chemithon FFR quench loop system was found to have an influence on 1,4-dioxane levels. However, the effect was not pronounced if the quench loop temperature was maintained at the optimum value (not released in Chemithon publication). 

The use of the post-reactor quench loop was found to be beneficial for low levels of 1,4-dioxane, provided that the residence time in this part of the reactor system was not longer than approximately five minutes. The recycle loop quench temperature had a strong effect on 1,4-dioxane levels, second only to that of mole ratio. 

Chemithon concentric tube FFR with quench loop in series... 

The Double-Loop FGD process has two separate loops in a single tower a lower quench loop and an upper absorber loop. Flue gas from the particulate collector is tirst quenched in the lower quench loop with a recirculating slurry of calcium sulfite, gypsum, and fresh calcium carbonate. The quenched flue gas then flows up through a gas/liquid separator and the... 

Quench Converter. The quench converter (Fig. 7a) was the basis for the initial ICl low pressure methanol flow sheet. A portion of the mixed synthesis and recycle gas bypasses the loop interchanger, which provides the quench fractions for the iatermediate catalyst beds. The remaining feed gas is heated to the inlet temperature of the first bed. Because the beds are adiabatic, the feed gas temperature increases as the exothermic synthesis reactions proceed. The injection of quench gas between the beds serves to cool the reacting mixture and add more reactants prior to entering the next catalyst bed. Quench converters typically contain three to six catalyst beds with a gas distributor in between each bed for injecting the quench gas. A variety of gas mixing and distribution devices are employed which characterize the proprietary converter designs. 

Retrofitting features of the more efficient reactor types have been the principal thmst of older methanol plant modernization (17). Conversion of quench converters to radial flow improves mixing and distribution, while reducing pressure drop. Installing an additional converter on the synthesis loop purge or before the final stage of the synthesis gas compressor has been proposed as a debotdenecking measure. 

From there, the reaction flow either leaves the total system to be quenched or, more commonly, enters the next plate which contains a delay loop, a spiral channel [56]. Leaving that plate, the streams flow to the last structured plate containing a bifurcation-mini mixer unit. The streams are distributed in multiple streams and contacted with a likewise split water stream. This leads to fast dilution, e.g., of a concentrated sulfuric acid stream, and rapidly cools the reaction stream. The reaction is quenched more or less initially. The final plate is unstructured and acts as a cover plate with holes for liquid withdrawal (Figure 4.28). 

Introducing local recycles around quench operations that use a water spray with some indirect cooling in the recycle loop. 

The exchange-quenched solution is then injected onto the protein processing system which includes injection loops, protease column(s), a trap column, an analytical column, electronically controlled valves, and isocratic and gradient pumps. 

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