Method for Enhancing the Performance of a Catalyzed Reaction

PATENT
Method for Enhancing the Performance of a Catalyzed Reaction
Inventors:
Sun, Bing (South Barrington, IL, US)
Zimmermann, Joseph Edward (Arlington Heights, IL, US)
Vetter, Michael (Schaumburg, IL, US)
Application Number: 12/827200
Publication Date: 01/05/2012
Assignee: UOP LLC (Des Plaines, IL, US)
Abstract:
A method for improving performance of a catalyzed reaction carried out in a moving bed system having a reaction zone. A process stream is introduced into the reaction zone at a temperature, and the temperature of the catalyst introduced to the reaction zone is different from the process stream introduction temperature to increase conversion.
FIELD
The invention relates generally to a method for enhancing the performance of a catalyzed reaction system. More particularly, the invention relates to a method for enhancing system performance of a catalyzed reaction system by controlling the temperature of the catalyst.

DESCRIPTION OF RELATED ART
In many industries, like the petrochemical and chemical industries for instance, processes employ reactors in which chemical reactions are carried out in the components of one or more reaction fluids in contact with a catalyst under given temperature and pressure conditions. Most of these reactions are either exothermic or endothermic and therefore generate or absorb heat to various extents. The heating or chilling effects associated with exothermic or endothermic reactions can positively or negatively affect the operation of the reaction zone. The negative effects can include, but are not limited to, poor product production, deactivation of the catalyst, production of unwanted by-products, and, in extreme cases, damage to the reaction vessel and associated piping. More typically, the undesired effects associated with temperature changes will reduce the selectivity or yield of products from the reaction zone.

Often, catalytic reactors used in the petrochemical and chemical industries are tubular arrangements that have fixed or moving catalyst beds. Such reactors may be radial flow reactors, in which the reaction fluids flow radially through an annulus containing the catalyst. The geometry of tubular reactors poses layout constraints that require large reactors or limit throughput.

One solution to the problem has been the indirect heating of reactants, catalysts, or both, within a reaction zone with a heating or cooling medium. Increasing the temperature of the reactants by heating the reactants before the reaction zone often leads to degradation of the feedstock, such as, for example, by thermal cracking or polymerization. Such degradation also often leads to equipment fouling and malfunctions. Another solution is to introduce, as part of the process stream, a relatively significant quantity of material to act as a heat carrier. However, this approach requires larger product recovery section and energy use to heat and move the heat carrier through the system, and may entail other equipment changes.

One method for indirect heat exchange employs thin plates to define alternate channels that retain catalyst and reactants in one set of channels and a heat transfer fluid in alternate channels for indirectly heating or cooling the reactants and catalysts. Heat exchange plates in these indirect heat exchange reactors can be flat or curved and may have surface variations such as corrugations to increase heat transfer between the heat transfer fluids and the reactants and catalysts.

Most catalysts for the reaction of hydrocarbons are susceptible to deactivation over time. Deactivation may occur because of an accumulation of deposits that cause deactivation by blocking active pore sites or catalytic sites on the catalyst surface. Coke is an example of one such deposit. Also, if the catalyst contains compounds that can exist in oxidized or reduced state, typically one of these states is more active and selective to the preferred reaction product. Thus, when catalyst is deactivated, reconditioning or regenerating the catalyst to restore the activity of the catalyst is required. For example, coke normally is removed from the catalyst by contact of the coke-containing catalyst at high temperature with an oxygen-containing gas to combust or remove the coke in a regeneration process. Catalysts also can be reduced or oxidized, as required, in processes known to the skilled practitioner. The regeneration process can be carried out in situ or the catalyst may be removed from a zone in which the hydrocarbon conversion takes place and transported to a separate regeneration zone for coke removal.

Reaction zones containing a moving bed of catalyst, and arrangements for continuously or semi-continuously moving catalyst particles from one reaction zone to another or from a reaction zone to a regeneration zone and then back to a same or different reaction zone, are well known. In such systems, catalyst often is transferred out of the reaction zone under gravity flow by removing catalyst from the bottom of the reaction zone. Similarly, catalyst is transferred into the reaction zone by adding catalyst to the top of the zone.

SUMMARY OF THE INVENTION
Aspects of this invention relate to a method for enhancing the performance of a catalyzed reaction system. In particular, the invention relates to a method for indirectly controlling the temperature of catalyst in a reactor. More particularly, the invention relates to a method for indirectly heating catalyst to enhance system performance.
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