CN-117181126-B - Reactor reordered dehydrogenation process and system

CN117181126BCN 117181126 BCN117181126 BCN 117181126BCN-117181126-B

Abstract

A dehydrogenation system includes a plurality of dehydrogenation reactors valve controlled by a plurality of valves to operate in alternating dehydrogenation and regeneration modes in a timed sequence in a system cycle, a digital programmable controller connected to the plurality of valves for sequencing the reactors, and means for determining a productivity characteristic of each reactor in the system cycle. The digital controller is operable to reorder the reactors to reduce peak productivity or productivity delta within an initial system cycle. After reordering, the throughput may be increased and the productivity profile of the reordered system more uniform without exceeding system limitations, such as without exceeding compressor operation limitations.

Inventors

JOSEPH G. DUFF
David S. Hagrid
Gilbert D. Waldz
Joseph A. Como
Michael O. Knight

Assignees

TPC集团有限责任公司

Dates

Publication Date: 20260508
Application Date: 20200430
Priority Date: 20190930

Claims (9)

1. A method of operating a dehydrogenation system having a plurality of dehydrogenation reactors alternating in a timed sequence between a dehydrogenation mode and a regeneration mode in a repeating system cycle, the method comprising: (a) Operating the plurality of dehydrogenation reactors in an initial system sequence having an initial characteristic peak productivity during a system cycle; (b) Determining a productivity characteristic of each of the dehydrogenation reactors; (c) Reordering the reactors to operate in a second system sequence having a reordered characteristic peak productivity that is lower than the initial characteristic peak productivity, and (D) The reordered characteristic peak productivity is increased to a reordered operating level to thereby increase system productivity within a system cycle as compared to operation in the initial system sequence.
2. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors alternating between a dehydrogenation mode and a regeneration mode in a timed sequence in a repeated system cycle according to claim 1 wherein peak productivity is determined by the yield of dehydrogenation product.
3. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors alternating between a dehydrogenation mode and a regeneration mode in a timed sequence in a repeating system cycle according to claim 1 wherein the characteristic productivity differential of the reordered reactors is lower than the characteristic productivity differential of the initial system sequence.
4. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors alternating in a timed sequence between a dehydrogenation mode and a regeneration mode in a repeated system cycle according to claim 3 wherein the characteristic productivity delta is determined by a difference in yields of the products.
5. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors alternating between a dehydrogenation mode and a regeneration mode in a repeating system cycle according to claim 1 wherein the step of increasing the re-ordered characteristic peak productivity to a re-ordered operating level comprises (i) increasing the temperature of regeneration air or (ii) increasing the temperature of a hydrocarbon feed or (iii) increasing the feed rate of the hydrocarbon feed to the dehydrogenation system or (iv) decreasing the inlet pressure to the dehydrogenation system or (v) a combination of two or more of items (i) through (iv).
6. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors alternating in a timed sequence between a dehydrogenation mode and a regeneration mode in a repeated system cycle according to claim 1 wherein the dehydrogenation system has 5 to 10 reactors.
7. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors alternating between a dehydrogenation mode and a regeneration mode in a repeating system cycle in a timed sequence, wherein the hydrocarbon feed to the reactors comprises isobutane.
8. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors that alternate between a dehydrogenation mode and a regeneration mode in a timed sequence in a repeating system cycle according to claim 1 wherein the reactors contain a fixed bed of catalyst selected from the group consisting of supported chromium catalysts, supported platinum-tin catalysts, and supported gallium-containing metal catalysts.
9. The method of operating a dehydrogenation system having a plurality of dehydrogenation reactors that alternate between a dehydrogenation mode and a regeneration mode in a timed sequence in a repeated system cycle according to claim 8 wherein the catalyst support is selected from the group consisting of alumina, zrO 2 、ZnAl 2 O 4 , and MgAl 2 O 4 .

Description

Reactor reordered dehydrogenation process and system The application relates to a dehydrogenation process and a dehydrogenation system for reordering reactors, which are applied separately, wherein the application number of the prior application is CN202080050920.8, the application date is 2020, and the application name is 30. Priority claiming The present application is based on U.S. patent application Ser. No. 16/587,161, filed on publication No. 9/30, 2019, which has the same title. U.S. patent application Ser. No. 16/587,161 was filed on the basis of month 7, day 26 of 2019 and is also entitled U.S. provisional application No. 62/878,864. The priority of the foregoing application is hereby claimed and the disclosure of which is incorporated herein by reference. Technical Field The present invention relates generally to cyclic dehydrogenation processes and systems having a plurality of dehydrogenation reactors operating in alternating and synchronized production/regeneration modes. These processes include the dehydrogenation of alkanes over a fixed bed of a catalyst such as supported chromium, gallium or platinum/tin. The present invention relates to sequencing or re-sequencing reactors to reduce fluctuations in throughput rate within a system cycle, thereby improving productivity. Background Hydrocarbon dehydrogenation processes are typically implemented with systems having compressors and absorbers that service a plurality of sequenced reactors that are operated in alternating production/regeneration modes in a system recycle. For example, in GB 794,089 a process is shown for carrying out catalytic dehydrogenation of hydrocarbons, in which a catalyst is alternately contacted with a hydrocarbon feed (hydrocarbon charge) and regenerated by combustion of carbonaceous deposits produced by dehydrogenation of the hydrocarbon feed. Each operation is carried out in a set of reactors operating in a timed sequence with substantially equal duration of hydrocarbon conversion and catalyst regeneration. The sequence of operation of each reactor is (1) hydrocarbon dehydrogenation, (2) steam purge to remove the catalyst and hydrocarbon product from the reaction vessel, (3) catalyst regeneration in an oxygen-containing gas, (4) evacuation and (5) reduction of the oxidation catalyst in a hydrogen-containing gas. An example form of dehydrogenation system is shown in figure 2 of GB 794,089. As shown, the system comprises five reactors R operating in one cycle, such that two reactors are operated simultaneously for catalytic dehydrogenation, two reactors are subjected to catalyst regeneration therein, and one reactor is at a stage involving operations such as evacuation, steam purge, hydrogen reduction, or valve replacement. The diagram in figure 3 of GB 794,089 shows how the reactor operates with a cycle of approximately 22.5 minutes. Another multi-reactor dehydrogenation system is shown in GB 823,626. According to GB 823,626 specification, two or more 3-reactor banks (3-reactor banks) are used. An exemplary dehydrogenation system is shown in figure 2 of GB 823,626. As shown, the system comprises six reactors R arranged in two groups of three reactors each and operated in a sequence such that two reactors (i.e. one reactor per group) are operated simultaneously for catalytic dehydrogenation, two reactors are subjected to catalyst regeneration therein, and two reactors are in a stage involving operations such as evacuation, steam purge, hydrogen reduction or valve replacement. The graph in figure 3 of GB 823,626 shows how the reactor operates in a 15 minute repeated cycle. Looking at the cycle diagram of figure 3 of GB 823,626 it can be noted that reactors 1 and 4, 2 and 5 and 3 and 6 are always in the same phase of one cycle. The desirability of such an arrangement according to the specification of GB 823,626 is determined by the fact that pairs of reactors are opposed to each other, as shown in figure 2 of GB 823,626. Thus, the gaseous material charged into the paired reactors and the gaseous material discharged from the reactors will travel an equal distance to the trunk line where the gases are introduced into and discharged from the units. GB 823,626 specification further states that staggered cycle times may be desirable in terms of reducing the need for associated ancillary equipment such as pumps, compressors, etc., since only one reactor is transitioning at a time. Other dehydrogenation systems with programmable controllers are seen in U.S. patent nos. 4,581,339 and 7,271,307 and WO 2018/203233. It is understood from the prior art that a plurality of alternating reactors in a dehydrogenation system are in a fixed operating sequence, that is, the reactors are always operated in the same continuous sequence. This is based in part on the assumption that the performance of the reactor in terms of conversion is equal in a reactor of the same configuration with the same catalyst, feed and operating conditions. However,