Process method for styrene dehydrogenation reaction

Abstract

The invention belongs to the field of fine chemical engineering, and particularly relates to a styrene dehydrogenation reaction process method which comprises the following steps: ethylbenzene enters an ethylbenzene feed steam generator to be heated and gasified, then enters and exits a material heat exchanger through a reactor to be subjected to heat exchange and temperature rise, and is mixed with superheated water vapor to be fed into a dehydrogenation reactor; a dehydrogenation reaction product produced by the dehydrogenation reactor enters a material heat exchanger and a raw material steam generator through the reactor for heat exchange and cooling, and then enters a post-treatment process of the dehydrogenation reaction product; reducing the ethylbenzene feeding amount in the ethylbenzene feeding steam generator, mixing a part of ethylbenzene and water, feeding the mixture into a raw material steam generator for heating gasification, feeding the obtained mixed steam into a material heat exchanger through a reactor for heat exchange and temperature rise, and feeding the mixed steam into a dehydrogenation reactor; the ethylbenzene feeding amount in the ethylbenzene feeding steam generator is gradually reduced, and the ethylbenzene feeding amount in the raw material steam generator is gradually increased, so that the energy consumption cost of the styrene dehydrogenation reaction is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and in particular relates to a process method for styrene dehydrogenation reaction. Background Art

[0002] Styrene (SM) is an important basic organic chemical raw material and the largest derivative of benzene. It is mainly used to produce polystyrene resin (PS), acrylonitrile-butadiene-styrene (ABS) resin, styrene-acrylonitrile copolymer (SAN) resin, styrene-butadiene rubber and styrene-butadiene latex (SBR / SBR latex), ion exchange resin, unsaturated polyester and styrene thermoplastic elastomer (such as SBS), etc. In addition, it is also used in the pharmaceutical, dye, pesticide and mineral processing industries, and has a wide range of uses.

[0003] At present, petrochemical refineries are all equipped with styrene units, and the styrene reaction process is a mature production technology both at home and abroad. With the development of the styrene industry, the market competition for styrene products is becoming increasingly fierce. In order to enhance product market competitiveness, improving product quality and reducing unit operating costs have become important directions for the development of the current styrene industry.

[0004] In summary, developing a styrene production process with low production energy consumption cost is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a process for the dehydrogenation of styrene, which has low energy consumption cost.

[0006] The present invention provides a process for the dehydrogenation of styrene, comprising the following steps:

[0007] Ethylbenzene enters the ethylbenzene feed steam generator for heating and gasification to obtain ethylbenzene steam; the ethylbenzene steam is heated by heat exchange in the reactor inlet and outlet material heat exchanger, and then mixed with superheated water steam and sent to the dehydrogenation reactor, where ethylbenzene is dehydrogenated to produce styrene under the action of a dehydrogenation catalyst;

[0008] The dehydrogenation reaction product produced by the dehydrogenation reactor is cooled by heat exchange in the reactor inlet and outlet material heat exchanger, and then enters the raw material steam generator as a heat source. After further cooling in the raw material steam generator, it enters the post-treatment process of the dehydrogenation reaction product;

[0009] After a heat source enters the raw steam generator, the ethylbenzene feed amount in the ethylbenzene feed steam generator is reduced; at the same time, part of the ethylbenzene is mixed with water and sent to the raw steam generator for heating and gasification to obtain a mixed steam of ethylbenzene and water; the mixed steam is heated by the reactor inlet and outlet material heat exchanger, and then sent to the dehydrogenation reactor for ethylbenzene dehydrogenation;

[0010] The ethylbenzene feed amount in the ethylbenzene feed steam generator is gradually reduced, and the ethylbenzene feed amount in the raw material steam generator is gradually increased, and finally the ethylbenzene feed amount of the ethylbenzene feed steam generator is reduced to 0, so that the raw material steam generator completely replaces the ethylbenzene feed steam generator.

[0011] Preferably, the heat source for the ethylbenzene vapor to pass through the reactor is steam or electric energy.

[0012] Preferably, in the feed of the dehydrogenation reactor, the mass ratio of water to ethylbenzene is controlled at (1-1.2):1.

[0013] Preferably, the feed temperature of the dehydrogenation reactor is 580-680°C.

[0014] Preferably, the pressure of the dehydrogenation reactor is -200 to 200 kPa.

[0015] Preferably, the temperature of the dehydrogenation reaction product after heat exchange and cooling in the material heat exchanger entering and exiting the reactor is 130-250°C.

[0016] Preferably, the superheated water steam comes from a steam superheater, and the feed of the steam superheater is low-pressure steam or boiler water.

[0017] Preferably, in the feed of the raw material steam generator, the mass ratio of water to ethylbenzene is ≤1:1.

[0018] Preferably, the mixed steam is first compressed by a feed compressor and then sent to the reactor inlet and outlet material heat exchanger for heat exchange and temperature increase.

[0019] Preferably, the post-treatment process comprises: the dehydrogenation reaction product after further cooling by the raw material steam generator enters a crude styrene settling tank for oil-water separation, and the separated crude styrene is subjected to distillation and purification.

[0020] Compared with the prior art, the present invention provides a process method for the dehydrogenation reaction of styrene. The process method provided by the present invention includes the following process: ethylbenzene enters the ethylbenzene feed steam generator for heating and gasification to obtain ethylbenzene steam; the ethylbenzene steam is heated by the reactor inlet and outlet material heat exchanger, and then mixed with superheated water steam and sent to the dehydrogenation reactor, and ethylbenzene is dehydrogenated to produce styrene under the action of a dehydrogenation catalyst; the dehydrogenation reaction product produced by the dehydrogenation reactor is cooled by the reactor inlet and outlet material heat exchanger, and then enters the raw material steam generator as a heat source, and after further cooling by the raw material steam generator, enters the post-processing process of the dehydrogenation reaction product; when the raw material steam generator has a heat source entering, After that, the ethylbenzene feed amount in the ethylbenzene feed steam generator is reduced; at the same time, part of the ethylbenzene is mixed with water and sent to the raw material steam generator for heating and gasification to obtain a mixed steam of ethylbenzene and water; the mixed steam is heated by heat exchange in the reactor inlet and outlet material heat exchanger, and then sent to the dehydrogenation reactor for ethylbenzene dehydrogenation; the ethylbenzene feed amount in the ethylbenzene feed steam generator is gradually reduced, and the ethylbenzene feed amount in the raw material steam generator is gradually increased, and finally the ethylbenzene feed amount of the ethylbenzene feed steam generator is reduced to 0, so that the raw material steam generator completely replaces the ethylbenzene feed steam generator. The present invention can reduce the heat energy consumption of the ethylbenzene feed steam generator and reduce the amount of superheated water vapor by utilizing the raw material steam generator to recover the waste heat of the dehydrogenation product, thereby effectively reducing the energy consumption cost of the styrene dehydrogenation reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 It is a process flow chart provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The present invention provides a process for the dehydrogenation of styrene, such as Figure 1 As shown, the following process is included:

[0025] In the initial stage of operation, ethylbenzene enters the ethylbenzene feed steam generator through valve 2 for heating and gasification to obtain ethylbenzene steam; at this time, valve 1 is in a closed state;

[0026] The ethylbenzene vapor passes through valves 5 and 6 and enters the reactor inlet and outlet material heat exchanger for heat exchange and temperature increase, and then exchanges with superheated water vapor (i.e. Figure 1 The superheated steam in the mixture is sent to a dehydrogenation reactor, where ethylbenzene is dehydrogenated to produce styrene under the action of a dehydrogenation catalyst;

[0027] The dehydrogenation reaction product produced by the dehydrogenation reactor is cooled by heat exchange in the reactor inlet and outlet material heat exchanger, and then enters the raw material steam generator as a heat source. After further cooling in the raw material steam generator, it enters the post-treatment process of the dehydrogenation reaction product;

[0028] After the heat source enters the raw steam generator, the openings of valves 2 and 5 are adjusted to reduce the ethylbenzene feed amount in the ethylbenzene feed steam generator; at the same time, valves 1, 3 and 4 are opened to allow part of the ethylbenzene and water to be mixed and then sent to the raw steam generator for heating and gasification to obtain a mixed steam of ethylbenzene and water; the mixed steam is heated and heated in the reactor inlet and outlet material heat exchanger, and then sent to the dehydrogenation reactor for ethylbenzene dehydrogenation;

[0029] By controlling the opening of valve 1, valve 2, valve 3, valve 4, valve 5 and valve 6, the ethylbenzene feed amount in the ethylbenzene feed steam generator is gradually reduced, and the ethylbenzene feed amount in the raw material steam generator is gradually increased, and finally the ethylbenzene feed amount of the ethylbenzene feed steam generator is reduced to 0 (i.e., valve 2 and valve 5 are completely closed), thereby realizing the complete replacement of the raw material steam generator for the ethylbenzene feed steam generator.

[0030] In the process provided by the present invention, the purity of ethylbenzene is preferably ≥99%, the sulfur content is preferably ≤2ppm, the nitrogen-based compound content is preferably ≤1ppm, and the total chlorine content is preferably ≤1ppm.

[0031] In the process provided by the present invention, the heat source for the ethylbenzene vapor passing through the reactor is preferably steam or electric energy.

[0032] In the process provided by the present invention, after the ethylbenzene vapor is heated by heat exchange in the reactor inlet and outlet material heat exchanger, it is preferably heated again by a superheater to meet the feed temperature requirement of the dehydrogenation reactor.

[0033] In the process provided by the present invention, the superheated water steam preferably comes from a steam superheater, and the feed of the steam superheater is preferably low-pressure steam or boiler water.

[0034] In the process provided by the present invention, the mass ratio of water to ethylbenzene in the feed of the dehydrogenation reactor is preferably controlled at (1-1.2):1, specifically 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1.

[0035] In the process provided by the present invention, the feed temperature of the dehydrogenation reactor is preferably 580-680°C, specifically 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C or 680°C.

[0036] In the process provided by the present invention, the pressure of the dehydrogenation reactor is preferably -200 to 200 kPa, specifically -200 kPa, -150 kPa, -100 kPa, -45 kPa, -50 kPa, 0 kPa, 50 kPa, 100 kPa, 150 kPa or 200 kPa.

[0037] In the process method provided by the present invention, the purpose of heat exchange of the dehydrogenation reaction product in the reactor inlet and outlet material heat exchanger is to recover the heat of the reaction product and reduce the temperature of the reaction product to facilitate the separation of the subsequent products; the temperature of the dehydrogenation reaction product after heat exchange and cooling in the reactor inlet and outlet material heat exchanger is preferably 130-250°C, specifically 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C.

[0038] In the process provided by the present invention, the mass ratio of water to ethylbenzene in the feed of the raw material steam generator is preferably ≤1:1, more preferably 1:(1-1.3); at the same time, the amount of superheated water steam entering the dehydrogenation reactor is reduced to ensure that the mass ratio of raw water and ethylbenzene entering the dehydrogenation reactor is preferably maintained at (1-1.2):1.

[0039] In the process provided by the present invention, it is preferred that a feed compressor is used to provide capacity for the mixed steam of ethylbenzene and water; that is, the mixed steam of ethylbenzene and water is preferably first compressed by a feed compressor and then sent to the reactor inlet and outlet material heat exchanger for heat exchange and temperature increase.

[0040] In the process provided by the present invention, after the mixed steam of ethylbenzene and water is heated by heat exchange in the reactor inlet and outlet material heat exchanger, it is preferably heated again by a superheater to meet the feed temperature requirement of the dehydrogenation reactor.

[0041] In the process method provided by the present invention, the post-treatment step preferably includes: the dehydrogenation reaction product after further cooling by the raw material steam generator enters the crude styrene settling tank for oil-water separation, the separated oil phase (crude styrene) is distilled and purified, and the separated water phase is recycled.

[0042] The method provided by the present invention can reduce the heat energy consumption of the ethylbenzene feed steam generator and the amount of superheated steam by utilizing the raw material steam generator to recover the waste heat of the dehydrogenation product, thereby effectively reducing the energy consumption cost of the styrene dehydrogenation reaction.

[0043] For the purpose of greater clarity, the invention is described in detail through the following examples.

[0044] Example 1

[0045] The present invention provides a process for the dehydrogenation of styrene, such as Figure 1 As shown, the following process is included:

[0046] Providing an ethylbenzene raw material, wherein the ethylbenzene content of the ethylbenzene raw material is ≥99wt%, the sulfur content is ≤2ppm, the nitrogen-based compound content is ≤1ppm, and the total chlorine content is ≤1ppm;

[0047] At the initial stage of operation, ethylbenzene enters the ethylbenzene feed steam generator through valve 2, and is heated and vaporized by 3.5mPa superheated steam to obtain ethylbenzene steam; at this time, valve 1 is in a closed state;

[0048] The ethylbenzene steam passes through valves 5 and 6 and enters the reactor inlet and outlet material heat exchanger for heat exchange and temperature increase. The ethylbenzene steam temperature is heated from 170°C to 260°C, and then the ethylbenzene steam is heated to 550°C by the feed superheater;

[0049] 550℃ ethylbenzene steam and superheated steam from the steam superheater (i.e. Figure 1 The superheated steam in the mixture) is mixed evenly and fed into a dehydrogenation reactor to dehydrogenate ethylbenzene to produce styrene under the action of a dehydrogenation catalyst; wherein the feed temperature of the dehydrogenation reactor is controlled at 620° C., the mass ratio of water to ethylbenzene in the feed is controlled at (1 to 1.2):1, and the dehydrogenation reaction pressure should be controlled at -45 kPa;

[0050] The dehydrogenation reaction product produced by the dehydrogenation reactor is cooled to 130-250° C. by heat exchange in the reactor inlet and outlet material heat exchanger; then, it enters the raw material steam generator as a heat source and is further cooled by the raw material steam generator; the dehydrogenation reaction product after further cooling by the raw material steam generator enters the crude styrene settling tank for oil-water separation, the separated oil phase (crude styrene) is distilled and purified, and the separated water phase is recycled;

[0051] After the heat source enters the raw steam generator, the openings of valves 2 and 5 are adjusted to reduce the amount of ethylbenzene feed in the ethylbenzene feed steam generator; at the same time, valves 1, 3 and 4 are opened to allow part of the ethylbenzene and water to be mixed and then sent to the raw steam generator for heating and gasification to obtain a mixed steam of ethylbenzene and water; the mixed steam of ethylbenzene and water is compressed by a feed compressor and sent to the reactor inlet and outlet material heat exchanger for heat exchange and temperature increase, and then heated to 550° C. by a feed superheater, and then sent to the dehydrogenation reactor for ethylbenzene dehydrogenation; during this period, the mass ratio of water to ethylbenzene in the feed of the raw steam generator is controlled at 1:(1-1.3), and at the same time, the amount of superheated water steam entering the dehydrogenation reactor is reduced to ensure that the mass ratio of raw water and ethylbenzene entering the dehydrogenation reactor is maintained at (1-1.2):1;

[0052] By controlling the opening of valve 1, valve 2, valve 3, valve 4, valve 5 and valve 6, the ethylbenzene feed amount in the ethylbenzene feed steam generator is gradually reduced, and the ethylbenzene feed amount in the raw material steam generator is gradually increased, and finally the ethylbenzene feed amount of the ethylbenzene feed steam generator is reduced to 0 (i.e., valve 2 and valve 5 are completely closed), thereby realizing the complete replacement of the raw material steam generator for the ethylbenzene feed steam generator.

[0053] According to calculation and statistics, the ethylbenzene conversion rate of the process method of this embodiment is 65%, and the styrene selectivity is more than 95%; the steam consumption per styrene is 0.75 t / t product.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A process for dehydrogenation of styrene, characterized in that: The process includes: Ethylbenzene enters the ethylbenzene feed steam generator for heating and gasification to obtain ethylbenzene steam; the ethylbenzene steam is heated by heat exchange in the reactor inlet and outlet material heat exchanger, and then mixed with superheated water steam and sent to the dehydrogenation reactor, where ethylbenzene is dehydrogenated to produce styrene under the action of a dehydrogenation catalyst; The dehydrogenation reaction product produced by the dehydrogenation reactor is cooled by heat exchange in the reactor inlet and outlet material heat exchanger, and then enters the raw material steam generator as a heat source. After further cooling in the raw material steam generator, it enters the post-treatment process of the dehydrogenation reaction product; After a heat source enters the raw steam generator, the ethylbenzene feed amount in the ethylbenzene feed steam generator is reduced; at the same time, part of the ethylbenzene is mixed with water and sent to the raw steam generator for heating and gasification to obtain a mixed steam of ethylbenzene and water; the mixed steam is heated by the reactor inlet and outlet material heat exchanger, and then sent to the dehydrogenation reactor for ethylbenzene dehydrogenation; The ethylbenzene feed amount in the ethylbenzene feed steam generator is gradually reduced, and the ethylbenzene feed amount in the raw material steam generator is gradually increased, and finally the ethylbenzene feed amount of the ethylbenzene feed steam generator is reduced to 0, so that the raw material steam generator completely replaces the ethylbenzene feed steam generator.

2. The process according to claim 1, characterized in that: The heat source of the ethylbenzene steam passing through the reactor is steam or electric energy.

3. The process according to claim 1, characterized in that: In the feed of the dehydrogenation reactor, the mass ratio of water to ethylbenzene is controlled at (1-1.2):

1.

4. The process according to claim 1, characterized in that: The feed temperature of the dehydrogenation reactor is 580-680°C.

5. The process according to claim 1, characterized in that: The pressure of the dehydrogenation reactor is -200 to 200 kPa.

6. The process according to claim 1, characterized in that: The temperature of the dehydrogenation reaction product after heat exchange and cooling in the reactor in and out of the material heat exchanger is 130-250°C.

7. The process according to claim 1, characterized in that: The superheated water steam comes from a steam superheater, and the feed of the steam superheater is low-pressure steam or boiler water.

8. The process according to claim 1, characterized in that: In the feed of the raw material steam generator, the mass ratio of water to ethylbenzene is ≤1:

1.

9. The process according to claim 1, characterized in that: The mixed steam is first compressed by a feed compressor and then sent to the reactor inlet and outlet material heat exchanger for heat exchange and temperature increase.

10. The process according to claim 1, characterized in that: The post-processing process includes: The dehydrogenation reaction product after further cooling by the raw material steam generator enters the crude styrene settling tank for oil-water separation, and the separated crude styrene is distilled and purified.

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