Temperature control of autorefrigerated reactors

Autorefrigerated or evaporatively cooled chemical reactors use the heat of vaporization to remove the heat generated by exo- thermic chemical reactions. Liquid in the reactor is at its bubblepoint. The vapor boiled from the liquid is condensed in a heat exchanger and the condensate is returned to the reactor. One of the major advantages of this type of reactor is that the area for heat transfer is not limited by reactor size because the heat exchanger can be speci®ed to be any desired size. This aids in scale-up since heat-transfer area can be scaled directly with reactor volume and heat generation. Despite their widespread use in industry, little has appeared in the literature dealing with this type of reactor. This paper presents a quantitative study of temperature control of boiling-liquid reactors. The e€ects of conversion and activation energy are explored. The major contribution of this paper is a demonstration that the condenser heat-transfer area required for dynamic stability can be an order of magnitude larger than that suggested by conventional steady-state heat-transfer design heuristics.