KR101473070B1 - New reactor flowscheme for dehydrogenation of propane to propylene - Google Patents

Abstract

A process for dehydrogenating paraffins is provided. This process utilizes a fast recirculation of the dehydrogenation catalyst between the dehydrogenation reactor and the catalyst regeneration unit. The process includes preheating the combined hydrogen and paraffin hydrocarbon feed stream and transferring the combined stream to a dehydrogenation reactor. The hydrocarbon feed stream and the catalyst pass through the reactor at a rate that limits the average residence time of the catalyst in the reactor. The catalyst is circulated to the regeneration unit and passes through the regeneration unit to limit the average residence time of the catalyst in the regeneration unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a novel reactor flow for dehydrogenation reaction of propane with propylene. BACKGROUND OF THE INVENTION < RTI ID = 0.0 >

Cross-reference to related application

This application claims priority from US Application No. 12 / 728,543, filed March 22, 2010.

Technical field

The present invention relates to the production of light olefins from paraffins. Specifically, the present invention relates to the dehydrogenation of propane in the production of propylene.

In the petrochemical industry, continuous catalytic conversion proceeds. Fluidized Catalyst Cracking is an important process in the production of light hydrocarbon components and is an important process in the production of ethylene and propylene. In the flow catalytic cracking process, the fluidized catalyst is continuously circulated between the reactor and the regenerator.

Another route of propylene production can be obtained by dehydrogenation of propane through catalytic dehydrogenation. The dehydrogenation catalyst typically comprises an acidic support, such as alumina, or silica alumina, or a noble metal catalyst on zeolite. However, the reaction is a strong endothermic reaction and requires high temperature to proceed the reaction at a satisfactory rate. At the same time, the reaction needs to be controlled to limit decomposition of propane to form methane and ethylene, which can be hydrogenated by hydrogen released through the dehydrogenation of propane. In addition, the process caulks the catalyst to deactivate the catalyst. Thus, the catalyst needs to be regenerated periodically in a dehydrogenation reactor, after a relatively short time of operation or residence.

The present invention relates to a process for dehydrogenating paraffins. In particular, the present invention relates to a process for the dehydrogenation of propane for the production of propylene. The process comprises transferring the preheated propane feed stream to a dehydrogenation reactor. The reactor is operated under conditions that the fluidized catalyst and propane mix and contact to produce a product stream comprising propylene. The operation of the reactor was designed to continuously feed the catalyst at a rate that provides a residence time of the catalyst in the reactor from 15 minutes to 45 minutes and to remove the catalyst from the dehydrogenation reactor. The reactor is a fast flow reactor which provides a well mixed reactant and feed stream and provides a uniform temperature throughout the reactor. The effluent stream from the reactor is separated into a product stream comprising the spent catalyst stream and propylene. The spent catalyst is delivered to a catalyst regeneration unit, thereby producing a regenerated catalyst stream. The catalyst is treated in the regeneration unit under the condition that the average residence time in the regeneration unit is limited to 30 minutes or less. The regenerated catalyst is transferred to a dehydrogenation reactor.

The high circulation rate of the catalyst through the reactor and the regenerator increases the overall flow of the reactants and increases the productivity of the dehydrogenation reactor.

BRIEF DESCRIPTION OF THE DRAWINGS For a further purpose, embodiments of the present invention and details are provided by way of the following drawings and detailed description of the invention.

The figure schematically shows a dehydrogenation process of hydrocarbons using a high-speed flow reactor.

Dehydrogenation of hydrocarbons in the production of olefins is important. Olefins are important in various products such as polymer plastics, or in the use of olefins in the formation of alkylaryl compounds. A dehydrogenation process of propane is provided. The process comprises transferring the preheated propane feed stream to a dehydrogenation reactor. The feed stream is contacted with a fluidized catalyst in a dehydrogenation reactor, thereby producing a product stream comprising propylene. The reactor is a fast flow reactor wherein the reactor is operated in a flow regime that turbulently mixes the catalyst and the feed stream. The catalyst and product stream are carried in a reactor and separated in a separation section, wherein the product stream comprising propylene is discharged from the reactor. The spent catalyst is delivered to the catalyst regeneration unit and regenerated as a catalyst for recovery into the dehydrogenation reactor.

The process of the high-speed flow reactor is operated under the reverse mixing conditions of the catalyst and the reactants. The mixing regulates the temperature to maintain a uniform temperature during the reaction while limiting local temperature drops that adversely affect the reaction rate. The reaction conditions include the operation of the reactor at a temperature of 600 ° C to 700 ° C. It is preferred that the mixing provides a more uniform temperature and that the catalyst and the feed are thoroughly mixed to operate at a temperature of 630 ° C to 650 ° C.

The reaction conditions include the pressure at the reactor outlet in the range of from 108 kPa to 1, 5 kPa (1 to 10 psig). A preferred operation is to regulate the pressure at the reactor outlet in the range of 122 kPa to 136 kPa (3 to 5 psig). The reaction is carried out in an atmosphere containing hydrogen besides the produced hydrogen. The operation of the reactor includes a molar ratio of hydrogen to hydrocarbon at the reactor inlet of 0.2 to 1, preferably a molar ratio of hydrogen to hydrocarbon of 0.6. The feed stream of hydrogen and hydrocarbons is preheated to provide a portion of the heat required in an endothermic reaction. Hydrogen is produced in the dehydrogenation process and is recovered and recycled to the feed stream. The hydrogen is recycled to maintain the hydrogen level throughout the reactor.

The present process utilizes the relatively short residence time of the catalyst and also includes rapid regeneration of the catalyst. The process allows the average catalyst residence time in the reactor to be between 15 minutes and 45 minutes, preferably between 15 minutes and 30 minutes. The short circulation time maintains a more uniform temperature throughout the reactor to achieve better conversion and selectivity. Novel catalysts useful in this process include non-metal catalysts. The term " non-metallic catalyst " refers to a catalyst containing no metal in the base state, but is intended to denote a catalyst containing a metal oxide such as zirconia and chromia.

To this extent, the flow of the catalyst during regeneration is limited to an average residence time of less than 30 minutes. The regeneration unit is preferably a riser reactor capable of mixing the catalyst during regeneration. The regeneration operates under conditions that burn some of the carbon stored in the catalyst. Additional fuel is delivered to the regeneration unit for combustion and heating of the catalyst. The burning burns carbon accumulated in the catalyst during the dehydrogenation process.

The process is shown in the figure. The hydrocarbon feed stream 10 and the hydrogen stream 12 are transferred to a combined feed heat exchanger 20 where they are preheated to produce a combined feed stream 22. The mixed feed stream 22 is further heated in the heater 30 to become a feed stream 32 heated to the inlet temperature of the reactor 40. The feed stream 32 passes through a reactor 40 to produce a product stream 42 comprising dehydrogenated hydrocarbons. The product stream 42 is used to preheat the hydrogen 12 and the hydrocarbon feed stream 10. In the present invention, the preferred feedstock is propane, which is dehydrogenated to form a propylene product stream 42. The catalyst in the reactor flows upward through the reactor 40 and the reactor 40 is operated to provide an average catalyst residence time of 15 to 45 minutes. The catalyst exits the reactor 44 and is delivered to the regenerator 50. Fuel 46 is added to the regenerator 50 to provide the energy for burning the carbon on the catalyst and heating the catalyst. The air 48 is compressed and heated before it is mixed with the fuel 46 and then delivered to the regenerator 50. The regenerator 50 reheats the catalyst and operates through the regenerator 50 to pass the catalyst through the regenerator 50 at an average residence time of less than 30 minutes. The high temperature regenerated catalyst 52 is delivered to the dehydrogenation reactor 40.

The catalyst is circulated between the reactor 40 and the regenerator 50 at a high rate. The rapid rate of cycling of the catalyst maintains the endothermic reaction by providing a continuously heated catalyst. The fast cycling produces a small amount of coke on the catalyst, which is easily and quickly removed in the regeneration step. Also, the excess heat leaving the regenerator of the flue gas can be recovered in the steam generator (60).

The reaction flow diagram is estimated to increase the propylene production scale to a higher flow rate. Current propylene production in the reactor system is limited to around 500 KMTA. The new reaction flow diagram is estimated to increase the production to a flow rate of 100 KMTA. In this system, the catalyst is estimated to circulate at a rate of 10 to 12 million kg / hr.

While the invention has been described in connection with what is presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims .

Claims (10)

Transferring the preheated propane feed stream to a dehydrogenation reactor wherein the propane feed stream has a hydrogen to hydrocarbon mole ratio of from 0.2 to 1;
Contacting and mixing the propane feed stream with a fluidized catalyst in a dehydrogenation reactor to produce a product stream comprising propylene, the reactor being a high velocity flow reactor, the catalyst being a non-metal catalyst, Wherein the average residence time in the step (a) is from 15 minutes to 45 minutes;
Transferring spent catalyst to a catalyst regeneration unit to produce a regenerated catalyst stream; And
Transferring the regenerated catalyst stream to a dehydrogenation reactor
≪ / RTI > The method according to claim 1,
Wherein the high-velocity flow reactor is operated under conditions that back-mix the catalyst and the reactants. The method according to claim 1,
Wherein the reaction conditions include a temperature of 600 ° C to 700 ° C. The method according to claim 1,
Wherein the reaction conditions include a reactor outlet pressure in the range of from 108 kPa to 170 kPa. delete The method according to claim 1,
Wherein the regeneration unit is a riser reator and the catalyst passes through the regenerator for an average residence time of less than 30 minutes. The method according to claim 1,
Further comprising the step of delivering fuel to the regeneration unit for combustion and heating the catalyst. The method according to claim 1,
Transferring the product stream to a combined feed heat exchanger to preheat the propane feed stream and preheat the hydrogen feed stream. delete delete

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