A styrene-refined heat pump energy-saving system

Abstract

This invention employs a first compressor, a second compressor, a first heat exchanger, a first reboiler, and a second heat exchanger to form a heat pump energy-saving system. It fully utilizes the heat energy of the top materials of the refined styrene distillation column and the crude styrene distillation column to heat the bottom materials of the refined styrene distillation column and the crude styrene distillation column. This not only effectively improves the utilization rate of the top heat of the refined styrene distillation column and the crude styrene distillation column, but also reduces the amount of circulating water used in the top condenser, effectively reducing production energy costs.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, specifically to a heat pump energy-saving system for styrene refining. Background Technology

[0002] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this utility model and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Styrene is the simplest member of unsaturated aromatic hydrocarbons and the fourth largest ethylene derivative after polyethylene, polyvinyl chloride, and ethylene glycol. It has a wide range of applications in pharmaceuticals, construction, fuels, automobiles, electronics, pesticides, and mineral processing.

[0004] Currently, the most common production method is the dehydrogenation of ethylbenzene to styrene. The dehydrogenation reaction of ethylbenzene is an endothermic reaction carried out at a relatively high water ratio (~1.3) and high temperature (~600 ℃). Separating pure styrene from the reaction products from the reactor generally requires 3-4 distillation columns. The 3-column process for styrene separation involves first separating ethylbenzene and lighter components with lower boiling points from the top of the crude styrene distillation column. Then, the ethylbenzene is separated from the lighter components in the ethylbenzene recovery column, and the ethylbenzene is recycled back to the reactor as feed. The crude styrene obtained from the bottom of the crude styrene distillation column is further distilled in the refined styrene distillation column to obtain styrene products from the top, and heavier components such as cumene, p-diethylbenzene, tert-butylcatechol, α-methylstyrene, sulfur-free polymerization inhibitors, styrene oligomers, and tar from the bottom. Because styrene can polymerize at room temperature, and the polymerization rate doubles for every 10°C increase in temperature, the distillation separation of styrene requires operation in high-vacuum, high-theoretical-plate-number distillation columns and under high reflux ratio conditions, resulting in significant energy consumption and the need for large amounts of cooling water. The crude styrene distillation column is the most energy-intensive column, accounting for 38% of the low-pressure steam consumption and 33% of the cooling water consumption in the entire styrene production unit, contributing 30% of the total energy consumption. Since the crude styrene distillation column operates under high vacuum, the heat grade at the top of the column is low, with a top temperature of only about 71°C, making it difficult to utilize. Currently, water cooling heat exchange is used, and this portion of heat is not recovered. Given the significant amount of this low-grade heat, comprehensive utilization of this thermal energy would be highly beneficial for reducing energy consumption and increasing economic efficiency in the styrene production process.

[0005] At the same time, the top of the styrene distillation column has a high heat grade, requiring a large amount of circulating condensate for cooling, which not only wastes a lot of heat energy but also increases the amount of circulating water. Utility Model Content

[0006] To address the aforementioned problems, this invention provides a styrene-refined heat pump energy-saving system.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0008] A heat pump energy-saving system for styrene refining includes: a crude styrene distillation column and a refined styrene distillation column;

[0009] The top outlet of the styrene distillation column is sequentially connected to the first compressor and the first heat exchanger;

[0010] The top outlet of the crude styrene distillation column is sequentially connected to a first heat exchanger and a second compressor; the second compressor is connected to the first reboiler.

[0011] The outlet of the styrene distillation column is connected to the first reboiler, which is connected to the inlet of the styrene distillation column; the first reboiler is connected to the second heat exchanger.

[0012] The crude styrene distillation column reboiler is equipped with a material circulation outlet, a material circulation inlet, and a crude styrene outlet;

[0013] The material circulation outlet is connected in sequence to the second heat exchanger and the material circulation inlet.

[0014] In one or more embodiments, a second reboiler is provided between the second heat exchanger and the material circulation inlet.

[0015] In one or more embodiments, the second heat exchanger is connected to the flash tank;

[0016] Preferably, the liquid outlet of the flash tank is connected to the top inlet of the crude styrene distillation column;

[0017] Preferably, the gas outlet of the flash tank is connected to the first condenser;

[0018] More preferably, the first condenser includes a first outlet and a second outlet, the first outlet being connected to the top inlet of the crude styrene distillation column; and the second outlet being connected to the ethylbenzene recovery column.

[0019] In one or more embodiments, the crude styrene outlet is connected to the inlet of the refined styrene distillation column.

[0020] In one or more embodiments, the first heat exchanger is connected to the second condenser; the second condenser is connected to the cryogenic cooler;

[0021] Preferably, both the second condenser and the cryogenic cooler are connected to the reflux tank;

[0022] More preferably, the reflux tank is provided with a reflux outlet and a product outlet; the reflux outlet is connected to the top inlet of the styrene distillation column; and the product outlet is connected to a styrene storage tank.

[0023] The beneficial effects of this utility model are as follows:

[0024] This invention employs a first compressor, a second compressor, a first heat exchanger, a first reboiler, and a second heat exchanger to form a heat pump energy-saving system. It fully utilizes the heat energy of the top materials of the refined styrene distillation column and the crude styrene distillation column to heat the bottom materials of the refined styrene distillation column and the crude styrene distillation column. This not only effectively improves the utilization rate of the top heat of the refined styrene distillation column and the crude styrene distillation column, but also reduces the amount of circulating water used in the top condenser, effectively reducing production energy costs. Attached Figure Description

[0025] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0026] Figure 1 A schematic diagram of a heat pump energy-saving system for styrene refining, wherein: 1-crude styrene distillation column, 2-refined styrene distillation column, 3-first compressor, 4-first heat exchanger, 5-second compressor, 6-first reboiler, 7-second heat exchanger, 8-second reboiler, 9-flash tank, 10-first condenser, 11-ethylbenzene recovery column, 12-second condenser, 13-deep cooler, 14-reflux tank, 15-styrene storage tank, 16-refined styrene distillation column reboiler outlet, 17-refined styrene distillation column reboiler inlet, 18-material circulation outlet, 19-material circulation inlet, 20-crude styrene outlet, 21-refined styrene distillation column mid-inlet, 22-crude styrene distillation column top outlet, 23-crude styrene distillation column top inlet, 24-crude styrene distillation column top outlet, 25-refined styrene distillation column top inlet. Detailed Implementation

[0027] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this utility model. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations.

[0030] Example 1

[0031] refer to Figure 1 A heat pump energy-saving system for styrene refining includes: crude styrene distillation column 1 and refined styrene distillation column 2;

[0032] The top outlet 24 of the styrene distillation column is sequentially connected to the first compressor 3 and the first heat exchanger 4;

[0033] The top outlet 23 of the crude styrene distillation column is connected in sequence to the first heat exchanger 4 and the second compressor 5; the second compressor 5 is connected to the first reboiler 6;

[0034] The outlet 16 of the styrene distillation column is connected to the first reboiler 6, and the first reboiler 6 is connected to the inlet 17 of the styrene distillation column; the first reboiler 6 is connected to the second heat exchanger 17.

[0035] The reboiler of crude styrene distillation column 1 is equipped with a material circulation outlet 18, a material circulation inlet 19, and a crude styrene outlet 20.

[0036] The material circulation outlet 18 is connected in sequence to the second heat exchanger 17 and the material circulation inlet 19.

[0037] In this column, the material in the bottom of the crude styrene distillation column 1 is heated in the second heat exchanger 17 and has a low temperature. In order to further increase the temperature of the material in the bottom of the crude styrene distillation column 1, a second reboiler 8 is provided between the second heat exchanger 17 and the material circulation inlet 19.

[0038] To recover the material from the top of the crude styrene distillation column 1 that participates in the heat pump energy-saving system, and to separate the light components from the material at the top of the crude styrene distillation column 1; the second heat exchanger 7 is connected to the flash tank 9; the liquid outlet of the flash tank 9 is connected to the top inlet 23 of the crude styrene distillation column; the gas outlet of the flash tank 9 is connected to the first condenser 10; the first condenser 10 includes a first outlet and a second outlet, the first outlet being connected to the top inlet 23 of the crude styrene distillation column; and the second outlet being connected to the ethylbenzene recovery column 11.

[0039] The crude styrene outlet 20 is connected to the inlet 21 of the refined styrene distillation column; the crude styrene separated from the bottom of the crude styrene distillation column 1 enters the refined styrene distillation column 2 for distillation to separate the product styrene.

[0040] To recover the material from the top of the styrene distillation column 2 that participates in the heat pump energy-saving system, and to separate the product styrene; the first heat exchanger 4 is connected to the second condenser 12; the second condenser 12 is connected to the cryogenic cooler 13; both the second condenser 12 and the cryogenic cooler 13 are connected to the reflux tank 14; the reflux tank 14 is provided with a reflux outlet and a product outlet; the reflux outlet is connected to the top inlet 25 of the styrene distillation column; and the product outlet is connected to the styrene storage tank 15.

[0041] The working process of this utility model is as follows:

[0042] The material A at the top outlet 24 of the refined styrene distillation column is compressed by the first compressor 3, and its temperature rises. It is then thermally coupled with the material B at the top outlet 23 of the crude styrene distillation column in the first heat exchanger 4 to heat the material at the top outlet 23 of the crude styrene distillation column.

[0043] After being heated, material B is compressed by the second compressor 5, heated again, and enters the first reboiler 6 to provide a heat source for the first reboiler 6, heating material C at the bottom outlet 16 of the refined styrene distillation column. The heated material C returns to the refined styrene distillation column 2 through the bottom inlet 17 of the refined styrene distillation column. After the first cooling, material B enters the second heat exchanger 17, where it is thermally coupled with material D at the material circulation outlet 18, heating material D. The temperature of material D rises, and it enters the second reboiler 8 for further heating, finally returning to the bottom of the crude styrene distillation column 1 through the material circulation inlet 19. After the second cooling, material B enters the flash tank 9 for gas-liquid separation, separating gaseous material B and liquid material B. Gaseous material B enters the first condenser 10 and is condensed, separating into two parts. One part, together with liquid material B, returns to the crude styrene distillation column 1 through the top inlet 23 of the crude styrene distillation column, while the other part enters the ethylbenzene recovery column 11 for subsequent recovery and separation.

[0044] After cooling, material A enters the second condenser 12 for the first condensation. The condensed material A is divided into two parts. One part enters the reflux tank 14 directly, and the other part enters the reflux tank 14 after being condensed again by the cryocooler 13. Part of the material in the reflux tank 14 returns to the styrene distillation column 2 through the reflux outlet and the top inlet 25 of the styrene distillation column. The other part, the product styrene, enters the styrene storage tank 15 through the product outlet.

[0045] The crude styrene separated from the bottom of crude styrene distillation column 1 enters refined styrene distillation column 2 for distillation to separate the product styrene.

[0046] This invention employs a first compressor, a second compressor, a first heat exchanger, a first reboiler, and a second heat exchanger to form a heat pump energy-saving system. It fully utilizes the heat energy of the top materials of the refined styrene distillation column and the crude styrene distillation column to heat the bottom materials of the refined styrene distillation column and the crude styrene distillation column. This not only effectively improves the utilization rate of the top heat of the refined styrene distillation column and the crude styrene distillation column, but also reduces the amount of circulating water used in the top condenser, effectively reducing production energy costs.

[0047] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of them. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A heat pump energy saving system for styrene refining, characterized by, include: Crude styrene distillation column and refined styrene distillation column; The top outlet of the refined styrene distillation column is sequentially connected to the first compressor and the first heat exchanger; The top outlet of the crude styrene distillation column is sequentially connected to a first heat exchanger and a second compressor; the second compressor is connected to the first reboiler. The outlet of the styrene distillation column is connected to the first reboiler, which is connected to the inlet of the styrene distillation column; the first reboiler is connected to the second heat exchanger. The crude styrene distillation column reboiler is equipped with a material circulation outlet, a material circulation inlet, and a crude styrene outlet; The material circulation outlet is connected in sequence to the second heat exchanger and the material circulation inlet.

2. The styrene refined heat pump energy saving system of claim 1, wherein, A second reboiler is provided between the second heat exchanger and the material circulation inlet.

3. The styrene refined heat pump energy saving system of claim 2, wherein, The second heat exchanger is connected to the flash tank.

4. The styrene refined heat pump energy saving system of claim 3, wherein, The liquid outlet of the flash tank is connected to the top inlet of the crude styrene distillation column.

5. The styrene refined heat pump energy saving system as claimed in claim 3, wherein, The gas outlet of the flash tank is connected to the first condenser.

6. The heat pump energy-saving system for styrene refining as described in claim 5, wherein the first condenser includes a first outlet and a second outlet, the first outlet being connected to the top inlet of the crude styrene distillation column; and the second outlet being connected to the ethylbenzene recovery column.

7. The styrene refined heat pump energy saving system of claim 1, wherein, The crude styrene outlet is connected to the inlet of the refined styrene distillation column.

8. The styrene refined heat pump energy saving system of claim 1, wherein, The first heat exchanger is connected to the second condenser; the second condenser is connected to the cryogenic cooler.

9. The styrene refined heat pump energy saving system as claimed in claim 8, wherein, Both the second condenser and the cryogenic cooler are connected to the reflux tank.

10. The styrene refined heat pump energy saving system as claimed in claim 9, wherein, The reflux tank is equipped with a reflux outlet and a product outlet; the reflux outlet is connected to the top inlet of the styrene distillation column; and the product outlet is connected to the styrene storage tank.

Images