Device for enhancing removal of water in styrene rectifying tower by using auxiliary nitrogen
By using auxiliary nitrogen gas to enhance the removal of moisture in the styrene distillation tower, the problem of difficulty in removing moisture in styrene production is solved, and the effect of effectively reducing moisture and improving product quality is achieved.
Patent Information
- Application Number
- CN202421770372.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-25
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-07-25
AI Technical Summary
During the styrene production process, moisture cannot be effectively removed through simple distillation, resulting in problems such as lower downstream product yields and catalyst poisoning.
The device that assists nitrogen to enhance the styrene distillation tower is used to discharge moisture from the exhaust gas through nitrogen entrainment, reducing the moisture in the condensate liquid phase product.
Effectively reduce moisture in styrene products and improve product quality. It has simple processes, small investment, low operating costs, high degree of automation and simple operation.
Smart Images
Figure CN222983740U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of styrene production, and particularly relates to a device for using auxiliary nitrogen to enhance the removal of moisture in a styrene rectification column. More specifically, it relates to a device that discharges the moisture in the rectification column from the tail gas of the rectification column through nitrogen entrainment, thereby reducing the moisture in the condensate liquid product. Background Technique
[0002] Styrene (SM) is an important petrochemical raw material. Its most important use is as a monomer for synthetic rubber and plastics, used to produce styrene-butadiene rubber, polystyrene, and expanded polystyrene. It is also used to copolymerize with other monomers to manufacture various engineering plastics with different uses. For example, copolymerizing with acrylonitrile and butadiene to obtain ABS resin, which is widely used in various household appliances and industries; copolymerizing with acrylonitrile to obtain SAN, which is an impact-resistant and brightly colored resin; copolymerizing with butadiene to obtain SBS, which is a thermoplastic rubber and is widely used as a modifier for polyvinyl chloride and polypropylene, etc. The demand for styrene products in China is increasing continuously. At present, the main production methods of styrene are the chlorohydrin method and the co-oxidation method. High moisture content in styrene will reduce the yield of downstream products, cause catalyst poisoning, etc. Moreover, in the current highly competitive environment of the styrene market, high moisture content in styrene will affect the marketing reputation. Therefore, it is imperative to reduce the moisture content in styrene.
[0003] During the styrene production process, moisture cannot be effectively removed through simple rectification. Using complex rectification has problems such as complex processes, large equipment investment, and high control requirements. The device adopted in the utility model uses auxiliary nitrogen to enhance the effect of the styrene rectification column, with a simple process, small investment, low operating costs, simple operation, high automation, and sensitive control, and can effectively reduce the moisture in the styrene product. Content of the Utility Model
[0004] The purpose of the utility model is to provide a device for using auxiliary nitrogen to enhance the removal of moisture in a styrene rectification column. This device can effectively reduce the moisture in the styrene product, is simple, practical, and has obvious effects, and has minimal impact on the normal operation of the styrene rectification column.
[0005] A device for assisting in removing moisture from a styrene distillation column using auxiliary nitrogen according to the present utility model is composed of a distillation column (5), a reboiler (10), a condenser (6), a reflux drum (7) and a nitrogen dosing device; the bottom of the side wall of the distillation column (5) is provided with a gas phase inlet and a nitrogen inlet, the middle of the side wall is provided with a liquid phase inlet, the top is provided with a gas phase outlet, and the bottom is provided with a liquid phase outlet; the top of the reboiler (10) is provided with a gas phase outlet, and the bottom is provided with a liquid phase inlet; the liquid phase inlet of the reboiler (10) is connected to the liquid phase outlet of the distillation column (5), and the gas phase outlet of the reboiler (10) is connected to the gas phase inlet of the distillation column (5); the liquid phase feed from the styrene distillation column is added to the distillation column (5) through the liquid phase inlet to separate light components and heavy components; the nitrogen dosing device is composed of a nitrogen analyzer (1), a flow meter (2), a regulating valve (3) and a check valve (4), and nitrogen enters the distillation column (5) through the nitrogen inlet at the bottom of the side wall of the distillation column (5); the reflux drum (7) is connected to the styrene product storage tank through a withdrawal pipeline, and a moisture meter (8) is arranged on the withdrawal pipeline; the reflux drum (7) is provided with a tail gas discharge pipeline (9); the distillation column (5), the condenser (6) and the reflux drum (7) are sequentially connected through pipelines. In the reboiler (10), the heavy component material in the liquid phase feed flows through the tube side, and the steam at 0.5 Mpa and 155 - 160 °C flows through the shell side; in the condenser (6), the light components in the liquid phase feed exchange heat with the circulating water at 30 - 35 °C.
[0006] The liquid-phase feedstock with a water content of about 80 - 200 ppm (containing crude styrene, acetophenone, methylbenzyl alcohol, etc.) from the styrene rectification column is fed into the middle part of the side wall of the rectification column (5), and enters the reboiler (10) through the liquid-phase outlet of the rectification column (5) and the liquid-phase inlet of the reboiler (10); inside the reboiler (10), the liquid-phase feedstock flows through the tube side, and the steam at 0.5 Mpa and 155 - 160 °C flows through the shell side, continuously providing heat for the reboiler (10); the reboiler vaporizes the liquid-phase feedstock, and then returns it to the rectification column (5) through the gas-phase outlet of the reboiler (10) and the gas-phase inlet of the rectification column (5), so that the temperature of the rectification column (5) is between 113 - 119 °C and the pressure is between 4 - 8 KPaA; in the rectification column (5), due to the different boiling points of each component, the separation of light components (styrene, water, etc.) and heavy components (acetophenone, methylbenzyl alcohol, etc.) is carried out; the light components move towards the top of the column driven by nitrogen in the rectification column (5) and are discharged from the gas-phase outlet at the top of the rectification column (5); in the condenser (6), the light components flow through the tube side, and the circulating water at 30 - 35 °C flows through the shell side; after the light components exchange heat with the circulating water at 30 - 35 °C in the condenser (6), they are condensed into a liquid phase and collected in the reflux drum (7), and nitrogen, as non-condensable gas, entraining most of the water is discharged from the tail gas discharge pipeline (9) of the reflux drum (7), and the styrene product with most of the water removed is sent to the styrene product storage tank through the extraction pipeline; the moisture meter (8) is used to on-line monitor the water content in the styrene product with most of the water removed; the heavy components move towards the bottom of the rectification column (5), enter the reboiler (10) through the liquid-phase outlet of the rectification column (5) and the liquid-phase inlet of the reboiler (10), are vaporized by heating inside the reboiler (10), and then return to the rectification column (5) through the gas-phase outlet of the reboiler (10) and the gas-phase inlet of the rectification column (5) for the next cycle; the light components vaporized by the reboiler (10) return to the rectification column (5) through the gas-phase inlet of the rectification column (5) and move upward, and the un-vaporized heavy components return to the rectification column (5) through the gas-phase outlet of the reboiler (10) and the gas-phase inlet of the rectification column (5) and then move towards the bottom kettle of the rectification column (5), and finally are pumped out by the heavy oil extraction pump (11) and sent to the heavy oil storage tank.
[0007] Nitrogen is added to the rectification column (5) under the control of the regulating valve (3), which does not chemically react with the crude styrene material, etc., and only increases the flow rate of the styrene gas-phase material.
[0008] The beneficial effects of the present utility model are:
[0009] 1. Sensitively control the amount of pure nitrogen introduced, reduce the water content of the styrene product, and improve the product quality;
[0010] 2. High degree of automation, simple operation, and low operation cost. Description of the Drawings
[0011] Figure 1 : Schematic structural diagram of the device of the present utility model;
[0012] As Figure 1 shown, the names of each part are: nitrogen analyzer 1, flow meter 2, regulating valve 3, check valve 4, rectifying column 5, reboiler 10, condenser 6, reflux drum 7, moisture analyzer 8, tail gas discharge pipeline 9, heavy oil extraction pump 11.
[0013] Nitrogen analyzer: Analyze the purity of nitrogen by applying the electrochemical method; Flow meter: Adopt an orifice plate flow meter; Regulating valve: Adopt a pneumatic regulating valve; Check valve: Adopt a conventional lift check valve; Rectifying column: Adopt a random saddle ring packing rectifying column; Reboiler: Adopt a vertical thermosyphon shell and tube reboiler; Condenser: Adopt a conventional horizontal condenser; Reflux drum: Adopt a conventional vertical reflux drum; Moisture analyzer: Adopt an infrared moisture analyzer. Specific embodiments
[0014] Embodiment 1
[0015] The present utility model will be further described below with reference to the accompanying drawings:
[0016] In Figure 1Among them, the nitrogen analyzer (1) on the nitrogen pipeline detects the nitrogen purity (≥96%), controls the nitrogen input amount through the flow meter (2) and the regulating valve (3), uses the check valve (4) to prevent the material gas in the rectification column (5) from flowing back to the nitrogen pipeline network, and the nitrogen filling device is connected to the bottom of the side wall of the rectification column (5). The liquid-phase feed with a water content of about 80 - 200 ppm (containing crude styrene, acetophenone, methyl benzyl alcohol, etc.) is fed into the middle of the side wall of the rectification column (5), and enters the reboiler (10) through the liquid-phase outlet of the rectification column (5) and the liquid-phase inlet of the reboiler (10); in the reboiler (10), the liquid-phase material passes through the tube side, and the steam at 0.5 Mpa and 158 °C passes through the shell side, continuously providing heat for the reboiler (10); the reboiler vaporizes the liquid-phase feed, and then returns to the rectification column (5) through the vapor-phase outlet of the reboiler (10) and the vapor-phase inlet of the rectification column (5), so that the temperature of the rectification column (5) is 116 °C and the pressure is 6 KPaA; in the rectification column (5), due to the different boiling points of each component, the separation of light components (styrene, water, etc.) and heavy components (acetophenone, methyl benzyl alcohol, etc.) is carried out; the light components move towards the top of the column driven by nitrogen in the rectification column (5) and are discharged from the vapor-phase outlet at the top of the rectification column (5); in the condenser (6), the light components pass through the tube side, and the circulating water at 30 - 35 °C passes through the shell side; after the light components exchange heat with the circulating water at 32 °C in the condenser (6), they are condensed into a liquid phase and collected in the reflux tank (7), and nitrogen, as non-condensable gas, entraining most of the water is discharged through the tail gas discharge pipeline (9) of the reflux tank (7), and the styrene product with most of the water removed is sent to the styrene product storage tank through the extraction pipeline; the moisture meter (8) is used to on-line monitor the water content in the styrene product with most of the water removed; the heavy components move towards the bottom of the rectification column (5), enter the reboiler (10) through the liquid-phase outlet of the rectification column (5) and the liquid-phase inlet of the reboiler (10), are vaporized by heating in the reboiler (10), and then return to the rectification column (5) through the vapor-phase outlet of the reboiler (10) and the vapor-phase inlet of the rectification column (5) for the next cycle; the unvaporized heavy components are pumped out through the heavy oil extraction pump (11) at the liquid-phase outlet of the bottom of the rectification column (5) and sent to the heavy oil storage tank.
[0017] An automatic control loop is formed among the flow meter (2), the regulating valve (3) and the moisture meter (8), and the nitrogen amount filled into the rectification column (5) is automatically controlled according to the moisture value of the styrene product, and the nitrogen input amount is controlled at 0.5 - 1 m 3 / h, so as to stably maintain the water content of the styrene product at about 50 ppm. The statistical data of the experimental moisture for 30 batches are shown in Table 1.
[0018] Table 1: Statistical Table of Water Content in Finished Styrene
[0019]
[0020]
[0021] As can be seen from Table 1, even though there are significant differences in the water content of the feedstock in different batches, the device described in the present utility model can effectively reduce the water content of the styrene finished product and stably maintain it at about 50 ppm.
Claims
1. A device for enhancing the removal of moisture from a styrene distillation tower using auxiliary nitrogen, characterized in that: The distillation tower (5) is composed of a distillation tower (5), a reboiler (10), a condenser (6), a reflux tank (7) and a nitrogen dosing device; the distillation tower (5) has a gas phase inlet and a nitrogen inlet at the bottom of the side wall, a liquid phase inlet in the middle of the side wall, a gas phase outlet at the top, and a liquid phase outlet at the bottom; The reboiler (10) has a gas phase outlet at the top and a liquid phase inlet at the bottom; the liquid phase inlet of the reboiler (10) is connected to the liquid phase outlet of the distillation tower (5), and the gas phase outlet of the reboiler (10) is connected to the gas phase inlet of the distillation tower (5); The liquid phase feed from the styrene distillation tower is added to the distillation tower (5) through the liquid phase inlet to separate the light component and the heavy component; The nitrogen dosing device is composed of a nitrogen analyzer (1), a flow meter (2), a regulating valve (3) and a check valve (4); the nitrogen enters the distillation tower (5) through a nitrogen inlet at the bottom of the side wall of the distillation tower (5); the reflux tank (7) is connected to a styrene product storage tank through a production pipeline, and a moisture meter (8) is arranged on the production pipeline; the reflux tank (7) is provided with a tail gas discharge pipeline (9); the distillation tower (5), the condenser (6) and the reflux tank (7) are connected in sequence through pipelines.
2. The device for enhancing the removal of moisture from a styrene distillation tower using auxiliary nitrogen as claimed in claim 1, characterized in that: In the reboiler (10), the heavy component materials in the liquid phase feed flow through the tube side, and the steam at 0.5 MPa and 155-160° C. flows through the shell side.
3. The device for enhancing the removal of moisture from a styrene distillation tower using auxiliary nitrogen as claimed in claim 1, characterized in that: In the condenser (6), the light component flows through the tube side, and the circulating water at 30 to 35°C flows through the shell side.
4. The device for enhancing the removal of moisture from a styrene distillation tower using auxiliary nitrogen as claimed in claim 1, characterized in that: An automatic control loop is formed between the flow meter (2), the regulating valve (3) and the moisture meter (8), and the amount of nitrogen charged into the distillation tower (5) is automatically controlled according to the moisture value of the styrene product.