A system for increasing ethane utilization in a styrene plant

Abstract

The utility model relates to styrene production technical field discloses a system of improving the utilization of ethane in styrene device, including ethylene cracking device, one side of ethylene cracking device is connected with mixed carbon two storage tank through pipeline, one side of mixed carbon two storage tank is provided with benzene storage tank, and the output of mixed carbon two storage tank and benzene storage tank is connected through pipeline penetration, and is connected with fixed bed reactor through pipeline, one side of fixed bed reactor is provided with separation component, and the output of separation component is connected with dehydrogenation reactor through pipeline, and another output of separation component is connected with fuel gas tank through pipeline, and first regulating valve is arranged on the pipeline between separation component and fuel gas tank, and ethylene cracking device and separation component are connected through pipeline penetration, through the ethane that originally was circulated back to the upstream ethylene cracking device, is introduced to the dehydrogenation system, is used as fuel gas to reduce the dependence on the fuel gas of the outside, realizes the resource reuse while saving energy and reducing consumption.

Description

Technical Field

[0001] This utility model relates to the field of styrene production technology, specifically a system for improving the utilization rate of ethane in styrene plants. Background Technology

[0002] Ethylbenzene (EB) is an important bulk basic organic chemical raw material in modern chemical industry. Its most distinctive feature is that it is rarely used directly, but it is an intermediate in the production of another extremely important chemical—styrene. The entire production process is roughly as follows: petroleum → ethylene + benzene → ethylbenzene → styrene → polystyrene (PS), ABS resin, styrene-butadiene rubber (SBR), and other final products. These final products have extremely wide downstream applications, such as food plastic packaging, toy plastic shells, automobile tires, shoe soles, and sealing strips. Therefore, styrene production is a crucial link supporting the automotive industry, electronics industry, building materials industry, packaging industry, and even daily consumer goods.

[0003] Therefore, the ethylbenzene production section is a crucial link in the styrene production process. The raw materials used in this section are mixed C2, mainly composed of ethylene and ethane. Ethylene is an effective raw material for producing ethylbenzene, while ethane is an inert component. Ethane does not participate in the reaction to produce ethylbenzene in the reaction system; it is merely an "observer." Changes in its content will dilute the concentration of reactants, affecting the reaction efficiency and thus affecting the yield of the intermediate product ethylbenzene to some extent.

[0004] The original method involved using a distillation column within the ethylbenzene section to separate the components based on their different boiling points. Ethane was collected as a vapor from the top of the column and ultimately recycled back to the upstream ethylene cracking unit. This method wasted the inherent fuel value of ethane and increased the load on the upstream unit. Furthermore, the unit's dehydrogenation system continuously consumed purchased fuel gas. This is a typical example of underutilized resources and energy waste, therefore, this production system with low ethane utilization urgently needs improvement. Utility Model Content

[0005] The purpose of this invention is to provide a system for improving the ethane utilization rate in a styrene plant, thereby solving the problem of low ethane utilization rate in the entire styrene production system and resulting energy waste, as mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: A system for improving the utilization rate of ethane in a styrene plant, comprising an ethylene cracking unit, wherein a mixed C2 storage tank is connected to one side of the ethylene cracking unit via a pipeline, a benzene storage tank is provided on one side of the mixed C2 storage tank, the output ends of the mixed C2 storage tank and the benzene storage tank are connected through a pipeline and connected to a fixed-bed reactor via a pipeline, a separation component is provided on one side of the fixed-bed reactor, the output end of the separation component is connected to a dehydrogenation reactor via a pipeline, the other output end of the separation component is connected to a fuel gas tank via a pipeline, a first regulating valve is provided on the pipeline between the separation component and the fuel gas tank, the ethylene cracking unit and the separation component are connected through a pipeline, and a second regulating valve is provided on the pipeline between the ethylene cracking unit and the separation component.

[0007] As a further technical solution of this utility model, the separation component includes an ethylbenzene product tower and a light component removal tower. The input end of the light component removal tower is connected to the output end of the fixed-bed reactor through a pipeline. The gas phase output end of the light component removal tower is connected to a fuel gas tank through a pipeline. The liquid phase input end of the light component removal tower is connected to the input end of the ethylbenzene product tower through a pipeline. The output end of the ethylbenzene product tower is connected to the dehydrogenation reactor through a pipeline.

[0008] As a further technical solution of this utility model, a flow meter is also installed on the pipeline between the first regulating valve and the fuel tank.

[0009] Compared with the prior art, the beneficial effects of this utility model are:

[0010] (1) By adding separation components and pipelines after the fixed-bed reactor in the ethylbenzene section, the remaining ethane after the reaction is introduced into the fuel gas tank to supply fuel for the heating furnace in the styrene section, reducing dependence on external fuel gas, forming resource reuse and energy saving. From August to October 2024, a total of about 1,600 tons of ethane was incorporated into the fuel gas system, reducing the external natural gas supplementation by about 2 million Nm³. 3 This has resulted in savings of over 7 million yuan in fuel gas costs. Meanwhile, the reduced amount of ethane returned to upstream units has led to a slight increase in the ethylene content in the mixed C2 feedstock. This not only improves the operating efficiency of the alkylation reaction but also increases daily production by approximately 20 tons. It is evident that the actual effect and economic value of incorporating ethane into fuel gas are significant. It improves resource utilization efficiency, reduces waste, and achieves refined resource management. It has now become an important part of the workshop's energy conservation and consumption reduction efforts. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the planar structure of each component of this utility model.

[0012] In the diagram: 1. Ethylene cracking unit; 2. Mixed C2 storage tank; 3. Benzene storage tank; 4. Fixed bed reactor; 5. Separation assembly; 51. Ethylbenzene product tower; 52. Light component removal tower; 6. Dehydrogenation reactor; 7. Fuel gas tank; 8. First regulating valve; 9. Second regulating valve; 10. Flow meter. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] Please see Figure 1 A system for improving ethane utilization in a styrene plant includes an ethylene cracking unit 1. Naphtha and other feedstocks are input to the ethylene cracking unit 1, where they mix with steam inside the cracking furnace and undergo a steam cracking reaction at 800°C, breaking down large hydrocarbon molecules into smaller molecules. A mixed C2 storage tank 2 is connected to one side of the ethylene cracking unit 1 via a pipeline to store the mixed C2 produced by cracking, i.e., a mixture of ethylene and ethane. A benzene storage tank 3 is located on one side of the mixed C2 storage tank 2, storing liquid benzene. The mixture is transported to a fixed-bed reactor 4 via a pipeline, with the outputs of the mixed C2 storage tank 2 and the benzene storage tank 3 connected by a pump. The mixture is then transported to a fixed-bed reactor 4, which is filled with a solid acid catalyst. Under medium temperature (200-300°C) and medium-high pressure (2-4 MPa) conditions, gaseous ethylene diffuses and dissolves into the liquid benzene phase, and ethylene and benzene molecules diffuse into the pores of the solid catalyst. Subsequently, the ethylene molecule is activated by the acidic sites on the catalyst surface, forming a positively charged "carbocation" intermediate. This activated ethylene intermediate acts as an "electrophile," attacking the electron-rich benzene ring and undergoing an alkylation reaction to generate ethylbenzene molecules.

[0015] A separation component 5 is installed on one side of the fixed-bed reactor 4. Before reaching the separation component 5, the generated mixture contains ethylbenzene, unreacted benzene, unreacted ethylene / ethane, and byproduct polyethylbenzene. The function of the separation component 5 is to separate these components. The separation component 5 includes an ethylbenzene product tower 51 and a light component removal tower 52. The input end of the light component removal tower 52 is connected to the output end of the fixed-bed reactor 4 via a pipeline. The gas phase output end of the light component removal tower 52 is connected to the fuel gas tank 7 via a pipeline. The function of the light component removal tower 52 is to collect unreacted ethane and send it to the fuel gas tank 7 for storage, to be used in the next step. The liquid phase input end of the light component removal tower 52 is connected to the input end of the ethylbenzene product tower 51 via a pipeline. High-purity ethylbenzene is collected through the ethylbenzene product tower 51. The output end of the ethylbenzene product tower 51 is connected to the dehydrogenation reactor 6 via a pipeline, and then sends this ethylbenzene to the next step of reaction to obtain styrene.

[0016] The output end of the separation component 5 is connected to the dehydrogenation reactor 6 via a pipeline, and the other output end of the separation component 5 is connected to the fuel gas tank 7 via a pipeline. This section is called the styrene section. The dehydrogenation reactor 6 has a reactor (dehydrogenation reactor) and a heating furnace. The reactor (dehydrogenation reactor) is filled with a special dehydrogenation catalyst and reacts under high temperature (about 600-650°C) and negative pressure conditions. The heating furnace provides the high temperature required for the reaction and is also the final consumption unit after the improved ethane fuel enters the fuel gas tank 7, reducing the dependence on and use of external fuel.

[0017] A first regulating valve 8 is installed on the pipeline between the separation component 5 and the fuel gas tank 7. The ethylene cracking unit 1 and the separation component 5 are connected by a pipeline. A second regulating valve 9 is installed on the pipeline between the ethylene cracking unit 1 and the separation component 5. Through the first regulating valve 8 and the second regulating valve 9, the destination of the ethane separated by the separation component 5 can be selected to return to the upstream ethylene cracking unit.

[0018] Furthermore, in order to monitor the flow rate of ethane entering the fuel tank at any time, a flow meter 10 is also installed on the pipeline between the first regulating valve 8 and the fuel tank 7.

[0019] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A system for improving the utilization rate of ethane in a styrene plant, comprising an ethylene cracking unit (1), wherein a mixed C2 storage tank (2) is connected to one side of the ethylene cracking unit (1) via a pipeline, and a benzene storage tank (3) is provided on one side of the mixed C2 storage tank (2), the output ends of the mixed C2 storage tank (2) and the benzene storage tank (3) are connected through a pipeline, and a fixed-bed reactor (4) is connected through a pipeline, characterized in that: A separation component (5) is provided on one side of the fixed bed reactor (4). The output end of the separation component (5) is connected to the dehydrogenation reactor (6) through a pipeline. The other output end of the separation component (5) is connected to the fuel gas tank (7) through a pipeline. A first regulating valve (8) is provided on the pipeline between the separation component (5) and the fuel gas tank (7). The ethylene cracking unit (1) and the separation component (5) are connected through a pipeline. A second regulating valve (9) is provided on the pipeline between the ethylene cracking unit (1) and the separation component (5).

2. The system for improving ethane utilization in a styrene plant according to claim 1, characterized in that: The separation component (5) includes an ethylbenzene product tower (51) and a light component removal tower (52). The input end of the light component removal tower (52) is connected to the output end of the fixed bed reactor (4) through a pipeline. The gas phase output end of the light component removal tower (52) is connected to the fuel gas tank (7) through a pipeline. The liquid phase input end of the light component removal tower (52) is connected to the input end of the ethylbenzene product tower (51) through a pipeline. The output end of the ethylbenzene product tower (51) is connected to the dehydrogenation reactor (6) through a pipeline.

3. The system for improving ethane utilization in a styrene plant according to claim 2, characterized in that: A flow meter (10) is also installed on the pipeline between the first regulating valve (8) and the fuel tank (7).

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