Ammonia water concentration device in alpha-pyrrolidone preparation

Abstract

The embodiment of the utility model provides an ammonia water concentration device in alpha-pyrrolidone preparation, and relates to the technical field of alpha-pyrrolidone preparation. The ammonia water concentration device in alpha-pyrrolidone preparation comprises a flash tank, the input end of the flash tank is communicated with a reactor through a pipeline, and the tower top gas phase output end of the flash tank is connected with a negative pressure light component removal tower through a pipeline. The device can effectively ensure that high-concentration ammonia obtained after ammonia water concentration is continuously used as a raw material for reaction to be recycled; meanwhile, a cold source of the device can be cooled by high-concentration ammonia, so that the source of the cold source of the device is ensured, the introduction of public equipment in the process is simplified, and the generated high-concentration ammonia can also meet the cold source of other users; and finally, dilute ammonia water and ammonia-containing vacuum tail gas generated by the device can be conveyed to an ammonia-containing tail gas absorption tower to produce ammonia water which is sold as byproducts, so that the economic benefit of production is further expanded.

Description

Technical Field

[0001] The utility model relates to the technical field of alpha-pyrrolidone preparation, in particular to an ammonia water concentration device in the preparation of alpha-pyrrolidone. Background Art

[0002] α-Pyrrolidone is produced by the reaction of high-concentration liquid ammonia and γ-butyrolactone. The ammonia-containing tail gas produced by the reaction is usually used to prepare 2%-15% ammonia water as a by-product for sale; or sent to an incinerator for desulfurization and denitrification treatment;

[0003] Currently, while the low-concentration ammonia produced from ammonia-containing tail gas can be recycled, the resource utilization rate is low because the concentration of the resulting ammonia water is too low. Furthermore, the cooling source for the equipment itself must be generated by external equipment, and the high-concentration ammonia produced cannot be used as the cooling source for the device itself, increasing investment and further increasing the cost of use. Utility Model Content

[0004] The purpose of the utility model is to provide an ammonia water concentration device for the preparation of α-pyrrolidone. The process is simple, reliable, easy to implement, and can effectively ensure that the high-concentration ammonia obtained after the ammonia water is concentrated can continue to be used as a raw material for the reaction and recycled. In addition, the cold source of the device itself can be cooled by the high-concentration ammonia itself, thereby ensuring the source of the cold source of the device and simplifying the introduction of public works in the process. At the same time, the dilute ammonia water and ammonia-containing vacuum tail gas produced by the device can be sent to an ammonia-containing tail gas absorption tower to produce ammonia water, and the device can be sold as a by-product.

[0005] The utility model provides an ammonia concentration device for preparing α-pyrrolidone, comprising: a flash tank, wherein the input end of the flash tank is connected to a reactor through a pipeline, and the gas phase output end of the flash tank tower top is connected to a negative pressure light-removal tower through a pipeline, the output end of the negative pressure light-removal tower is provided with a pressurized concentration tower, the liquid output end of the middle section of the pressurized concentration tower is connected to a product tower through a pipeline, and the output end of the product tower bottom is connected to a product tower delivery pump through a pipeline, and at the same time, the output end of the product tower delivery pump is connected to a raw ammonia storage tank through a pipeline.

[0006] In a specific embodiment, a product column condenser for condensing the gas phase is provided at the top of the product column, and a product column reboiler for increasing the heat of the product column is provided at one end of the product column.

[0007] In a specific embodiment, the bottom output end of the pressurized concentration tower is provided with a dilute ammonia water pump for delivering the dilute ammonia water produced therein, and the output end of the raw ammonia storage tank is connected to an ammonia feed pump through a pipeline.

[0008] In a specific embodiment, the bottom output end of the negative pressure light removal tower is connected to the input end of the negative pressure light tower delivery pump through a pipeline, and the output end of the negative pressure light tower delivery pump is bidirectionally connected to the pressurized concentration tower through a pipeline.

[0009] In a specific embodiment, the top output end of the pressurized concentration tower is connected to the middle input end of the negative pressure degassing tower through a pipeline, so as to transport the small portion of the top of the pressurized concentration tower that has not been condensed to the gas phase to the negative pressure degassing tower for continued cyclic absorption.

[0010] In a specific embodiment, the product tower condenser includes a feed pipe installed at the gas phase output end of the top of the product tower, the feed pipe is connected to the gas phase input end of the product tower condenser, and a liquid storage chamber for storing water for generating steam is installed at the bottom of the product tower reboiler.

[0011] In a specific embodiment, a heat exchange tube is mounted on the surface of the feed pipe, and a heat exchange coil is wound around the inner cavity of the heat exchange tube.

[0012] In a specific embodiment, the inner cavity of the heat exchange coil is connected to a heat exchange wire for heat transfer.

[0013] In a specific embodiment, the top input end of the heat exchange tube is connected to a delivery pipe, and the bottom output end of the heat exchange tube is connected to a return pipe.

[0014] In a specific embodiment, a circulation pump is provided on the lower side of the liquid storage chamber, and the output end of the circulation pump is connected to delivery pipe 1, wherein the input end of delivery pipe 1 is connected to the output end of the liquid storage chamber, and the output end of the circulation pump is connected to delivery pipe 2 and delivery pipe 3 respectively.

[0015] The beneficial effects of the present application are: the process is simple and reliable, easy to implement, and can effectively ensure that the high-concentration ammonia obtained after the ammonia water is concentrated can continue to be used as the raw material for the reaction and recycled, thereby improving the cost-effectiveness of the by-product; at the same time, the cold source of the device itself can be cooled by the high-concentration ammonia itself, ensuring the source of the cold source of the device, simplifying the introduction of public equipment in the process, and at the same time, the high-concentration ammonia produced can also meet the cold source needs of other users; the dilute ammonia water and ammonia-containing vacuum tail gas finally produced by the device can be sent to the ammonia-containing tail gas absorption tower to produce ammonia water as a by-product for sale, further expanding the economic benefits of production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is the overall process principle diagram of an embodiment of the utility model;

[0018] Figure 2 This is a schematic diagram of the structural assembly of the product tower, product tower condenser and product tower reboiler according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic cross-sectional view of the heat exchange tube structure according to an embodiment of the present utility model;

[0020] Figure 4 This is a right-side perspective diagram of the heat exchange tube structure according to an embodiment of the present utility model;

[0021] Figure 5 For the embodiment of the utility model Figure 4 A magnified schematic diagram of the structure in the middle.

[0022] icon:

[0023] 1. Reactor; 2. Flash tank; 3. Negative pressure light-removal tower; 4. Pressurized concentration tower; 5. Product tower; 6. Product tower condenser; 61. Feed pipe; 62. Return pipe; 63. Guide pipe; 7. Product tower reboiler; 71. Liquid storage chamber; 8. Product tower delivery pump; 9. Dilute ammonia pump; 10. Raw ammonia storage tank; 11. Negative pressure light-removal tower delivery pump; 12. Ammonia feed pump; 13. Heat exchange cylinder; 131. Heat exchange coil; 132. Heat exchange wire; 14. Circulation pump; 141. Delivery pipe 1; 142. Delivery pipe 2; 143. Delivery pipe 3. DETAILED DESCRIPTION

[0024] At present, in the process of preparing low-concentration ammonia from ammonia-containing tail gas, although the low-concentration ammonia prepared from ammonia-containing tail gas can be recycled, the resource utilization rate is not high because the concentration of the prepared ammonia water is too low. In addition, the cooling source of the equipment itself needs to be generated by external preparation equipment, and the high-concentration ammonia after preparation cannot be used as the cooling source of the device itself, which increases the investment cost and further increases the cost of use. During use, the low-concentration ammonia prepared from ammonia-containing tail gas can be recycled, and the cooling source of the device itself can be cooled by the high-concentration ammonia itself, ensuring the source of the cooling source of the device. At the same time, the dilute ammonia water and ammonia-containing vacuum tail gas produced by the device can be sent to the ammonia-containing tail gas absorption tower to produce ammonia water, and the device can be sold as a by-product, thereby solving the above-mentioned defects.

[0025] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0026] Example 1

[0027] Please refer to Figures 1 to 5 The embodiment of the present invention provides an ammonia concentration device for the preparation of α-pyrrolidone, comprising a flash tank 2, the input end of the flash tank 2 being connected to a reactor 1 via a pipeline, and the gas phase output end at the top of the flash tank 2 being connected to a negative pressure light removal tower 3 via a pipeline, a pressurized concentration tower 4 being provided at the output end of the negative pressure light removal tower 3, the liquid output end of the middle section of the pressurized concentration tower 4 being connected to a product tower 5 via a pipeline, and the bottom output end of the product tower 5 being connected to a product tower delivery pump 8 via a pipeline, and at the same time, the output end of the product tower delivery pump 8 being connected to a raw ammonia storage tank 10 via a pipeline.

[0028] A product tower condenser 6 for gas phase condensation is provided at the top of the product tower 5, wherein the output end of the product tower delivery pump 8 is connected to the input end of the product tower condenser 6 through a pipeline, so that a part of the high-concentration ammonia in the product tower condenser 6 can be delivered to the raw ammonia storage tank 10 for storage through the product tower delivery pump 8, and the other part is delivered to the product tower condenser 6 as a heat exchange cold source to perform heat exchange treatment on the gas phase in the product tower 5. A product tower reboiler 7 for increasing heat is provided at one end of the product tower 5, and the input end of the product tower reboiler 7 is connected to the output end of the bottom of the product tower 5 through a pipeline, and the output end of the product tower reboiler 7 is connected to the tower side input end of the product tower 5 through a pipeline.

[0029] The bottom output end of the pressurized concentration tower 4 is provided with a dilute ammonia water pump 9 for delivering the dilute ammonia water produced therein. The dilute ammonia water produced is delivered by the dilute ammonia water pump 9 and sold as a by-product of this product. The output end of the raw ammonia storage tank 10 is connected to an ammonia feed pump 12 through a pipeline, wherein the input end of the ammonia feed pump 12 and the output end of the raw ammonia storage tank 10 are connected to each other through a pipeline. The ammonia feed pump 12 is used to transport the high-concentration ammonia stored in the raw ammonia storage tank 10, and the output end of the ammonia feed pump 12 is connected to the input end of the reactor 1 through a pipeline, so that the high-concentration ammonia produced can be used as a raw material for the reaction and recycled, thereby improving the cost-effectiveness of the by-products.

[0030] The bottom output end of the negative pressure light removal tower 3 is connected to the input end of the negative pressure light tower delivery pump 11 through a pipeline, and the output end of the negative pressure light tower delivery pump 11 is bidirectionally connected to the pressurized concentration tower 4 through a pipeline, which is used to send the kettle liquid produced in the negative pressure light removal tower 3 into the pressurized concentration tower 4 for pressurized treatment.

[0031] The top output end of the pressurized concentration tower 4 is connected to the middle input end of the negative pressure degassing tower 3 through a pipeline, so as to transport the small part of the top of the pressurized concentration tower 4 that has not been condensed to the gas phase to the negative pressure degassing tower 3 for continued circulation absorption. The output end of the product tower condenser 6 is connected to the input end of the product tower 5 and the pressurized concentration tower 4 through pipelines respectively.

[0032] The product tower condenser 6 includes a feed pipe 61 installed at the gas phase output end of the top of the product tower 5. The feed pipe 61 is connected to the gas phase input end of the product tower condenser 6 and is used to feed the gas phase in the product tower 5 into the product tower condenser 6 for condensation. The product tower condenser 6 is heated by low-pressure steam, and a liquid storage chamber 71 for storing water for generating steam is installed at the bottom of the product tower reboiler 7.

[0033] As the first implementation plan of this embodiment:

[0034] Reactor 1 is a microchannel reactor. The material in reactor 1 enters flash tank 2 through the outlet for flash dehydration and deammoniation. The liquid phase of the reactants enters the subsequent distillation section to produce qualified products. The gas phase in flash tank 2 is sent to negative pressure degassing tower 3 for dehydration and deammoniation. The top of the tower is evacuated by a vacuum system, and the bottom of the tower is heated by low-pressure steam. The reboiler on the negative pressure degassing tower 3 is integrated with the tower body, and the reboiler adopts a central circulation tube type. The bottom liquid of the negative pressure degassing tower 3 is sent to the pressure concentration tower 4 for pressurized treatment through the negative pressure tower delivery pump 11.

[0035] The top of the pressurized concentration tower 4 adopts a total reflux condenser, and the cold source adopts high-concentration ammonia for refrigeration. The refrigerated high-concentration ammonia returns to the pressurized concentration tower 4 for further distillation. The gas phase outlet at the top of the tower returns to the negative pressure light removal tower 3 for further dehydration and deammonification. The produced liquid on the side of the middle section of the tower is sent to the product tower 5 for distillation. The upper bottom of the pressurized concentration tower 4 is heated by low-pressure steam. The reboiler and the tower body are integrated, and the reboiler adopts a central circulation tube type. The bottom liquid is sent out as dilute ammonia water by the dilute ammonia water pump 9 as a by-product for sale.

[0036] The gas phase at the top of the product tower 5 enters the product tower condenser 6 for condensation. The high-concentration ammonia extracted from the tower bottom is used as the cold source for gasification and heat absorption. The liquid phase on the product tower condenser 6 is completely refluxed. The product tower reboiler 7 is heated by low-pressure steam. The tower bottom liquid is sent to the raw ammonia storage tank 10 through the product tower delivery pump 8. The high-concentration ammonia continues to be used as the raw material for the reaction and is recycled, thereby improving the cost-effectiveness of the by-product.

[0037] As the second implementation scheme of this embodiment:

[0038] The material in the reactor 1 enters the flash tank 2 through its outlet for flash evaporation. The flashed ammonia and light components such as water have a pressure of 7-8 MPa and a temperature of 150-180°C, containing 70% ammonia, 28% water, and 2% other impurities. After cooling with circulating water at the top of the tower and water supply, the circulating water has a pressure of 0.5 MPa and a temperature of ≤30°C. A small portion of the material is evacuated by the top vacuum system to maintain a top pressure of 20 kPa.a. The main content is about 250 mg / m3 of ammonia, as well as other inert gases such as H2O, N2, H2, CO, CO2, etc. The tower bottom temperature is maintained at 100°C. Due to the high temperature of the feed hot state, the tower bottom reboiler on the negative pressure light removal tower 3 is rarely used. The tower bottom liquid is sent to the pressurized concentration tower 4 through the negative pressure light tower discharge pump 11;

[0039] The pressure at the top of the pressurized concentration tower 4 is 1.3-1.5 bar, about 85 ° C. The high-concentration ammonia after passing through the top cooler enters the pressurized concentration tower 4 for recycling, and conducts mass and heat transfer with the gas phase rising from the tower bottom. Most of the ammonia in the tower is condensed into high-concentration ammonia. High-concentration liquid ammonia is extracted from the middle section of the tower, and the concentration can reach more than 99.15%. A small part of the top of the tower is not condensed and goes to the gas phase and returns to the negative pressure light removal tower 3 for continued circulation and absorption. The gaseous tail gas is mainly non-condensable gas dissolved in high-coarseness ammonia, and its main components are inert gases such as N2, H2, CO, CO2, etc. The tower bottom solution is a dilute ammonia-containing solution. Ammonia water, with a concentration of up to 5.7%, can be fed into the ammonia-containing tail gas absorption tower together with the ammonia-containing tail gas discharged from the vacuum system for ammonia tail gas absorption and sold as a by-product. The ammonia extracted from the pressurized concentration tower 4 enters the product tower 5 for pressurized absorption, and the high-concentration ammonia extracted from the tower bottom is pumped into the product tower condenser 6 through the product tower delivery pump 8 for condensation. Due to the high installation height of the product tower condenser 6, the saturated vapor pressure of the high-concentration ammonia is reduced, so that the ammonia extracted from the tower bottom can be quickly vaporized and absorb heat, thereby achieving a condensation effect. The tower top pressure is about 4-5 bar, and the tower top reflux method adopts full reflux.

[0040] The liquid phase at the bottom of the tower is high-concentration ammonia, which can reach more than 99.8%. It is sent to the raw ammonia storage tank 10 for storage through the product tower delivery pump 8, and another part is extracted and sent to the product tower condenser 6 to provide a cold source for recycling.

[0041] Example 2

[0042] When the product tower reboiler 7 is working to heat the product tower 5, it uses low-pressure steam to work in the product tower 5, which greatly increases the power consumption of the product tower reboiler 7. In order to further reduce its production cost, reference is made to Figures 2 to 5 A heat exchange tube 13 is mounted on the surface of the feed pipe 61 , and a heat exchange coil 131 is wound around the inner cavity of the heat exchange tube 13 for auxiliary heating of the steam water stored in the liquid storage chamber 71 .

[0043] Specifically, the inner cavity of the heat exchange coil 131 is connected to a heat exchange wire 132 for heat transfer, which can transfer heat to the heat exchange coil 131 when the temperature in the heat exchange tube 13 rises, thereby assisting in heating the steam water flowing through it and reducing the power consumption of the product tower reboiler 7.

[0044] Specifically, the top input end of the heat exchange tube 13 is connected to the guide pipe 63, and the bottom output end of the heat exchange tube 13 is connected to the return pipe 62. Under the joint action of the guide pipe 63, the heat exchange tube 13 and the return pipe 62, part of the high-temperature gas flowing through the feed pipe 61 can be intercepted and sent into the heat exchange tube 13. The heat exchange tube 13, the heat exchange coil 131 and the heat exchange wire 132 are used to perform auxiliary heating treatment on the steam water generated in the liquid storage chamber 71 in the product tower reboiler 7, thereby reducing the power consumption of the product tower reboiler 7.

[0045] Specifically, a circulation pump 14 is provided on the lower side of the liquid storage chamber 71, and the output end of the circulation pump 14 is connected to the delivery pipe 1 141, wherein the input end of the delivery pipe 1 141 is connected to the output end of the liquid storage chamber 71, and the output end of the circulation pump 14 is respectively connected to the delivery pipe 2 142 and the delivery pipe 3 143, wherein the other end of the delivery pipe 2 142 is connected to the liquid inlet end of the heat exchange coil 131, and the other end of the delivery pipe 3 143 is connected to the liquid outlet end of the heat exchange coil 131, so that the liquid in the liquid storage chamber 71 is delivered to the heat exchange cylinder 13 and the heat exchange coil 131 by the circulation pump 14 for heat exchange, thereby reducing the power consumption of the product tower reboiler 7.

[0046] The above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An ammonia concentration device for the preparation of α-pyrrolidone, characterized in that: It includes a flash tank, the input end of which is connected to a reactor through a pipeline, and the gas phase output end at the top of the flash tank is connected to a negative pressure light removal tower through a pipeline, the output end of the negative pressure light removal tower is provided with a pressurized concentration tower, the liquid output end of the middle section of the pressurized concentration tower is connected to a product tower through a pipeline, and the bottom output end of the product tower is connected to a product tower delivery pump through a pipeline, and at the same time, the output end of the product tower delivery pump is connected to a raw ammonia storage tank through a pipeline.

2. The ammonia concentration device for preparing α-pyrrolidone according to claim 1, characterized in that: A product tower condenser for condensing the gas phase is provided at the top of the product tower, and a product tower reboiler for increasing the heat of the product tower is provided at one end of the product tower.

3. The ammonia concentration device for preparing α-pyrrolidone according to claim 2, characterized in that: The bottom output end of the pressurized concentration tower is provided with a dilute ammonia water pump for delivering the dilute ammonia water produced therein, and the output end of the raw ammonia storage tank is connected to an ammonia feed pump through a pipeline.

4. The ammonia concentration device for preparing α-pyrrolidone according to claim 3, characterized in that: The bottom output end of the negative pressure light removal tower is connected to the input end of the negative pressure light tower delivery pump through a pipeline, and the output end of the negative pressure light tower delivery pump is bidirectionally connected to the pressurized concentration tower through a pipeline.

5. The ammonia concentration device for the preparation of α-pyrrolidone according to claim 4, characterized in that: The top output end of the pressurized concentration tower is connected to the middle input end of the negative pressure degassing tower through a pipeline, so as to transport the gas phase of the small amount of the top of the pressurized concentration tower that has not been condensed to the negative pressure degassing tower for continued circulation absorption.

6. The ammonia concentration device for the preparation of α-pyrrolidone according to claim 5, characterized in that: The product tower condenser includes a feed pipe installed at the gas phase output end of the product tower top, the feed pipe is connected to the gas phase input end of the product tower condenser, and a liquid storage chamber for storing water for generating steam is installed at the bottom of the product tower reboiler.

7. The ammonia concentration device for preparing α-pyrrolidone according to claim 6, characterized in that: A heat exchange tube is mounted on the surface of the feeding tube, and a heat exchange coil is wound around the inner cavity of the heat exchange tube.

8. The ammonia concentration device for the preparation of α-pyrrolidone according to claim 7, characterized in that: The inner cavity of the heat exchange coil is connected to a heat exchange wire for heat transfer.

9. The ammonia concentration device for preparing α-pyrrolidone according to claim 8, characterized in that: The tower top input end of the heat exchange cylinder is connected with a guide pipe, and the tower bottom output end of the heat exchange cylinder is connected with a return pipe.

10. The ammonia concentration device for the preparation of α-pyrrolidone according to claim 9, characterized in that: A circulation pump is provided on the lower side of the liquid storage chamber, and the output end of the circulation pump is connected to the delivery pipe 1, wherein the input end of the delivery pipe 1 is connected to the output end of the liquid storage chamber, and the output end of the circulation pump is connected to the delivery pipe 2 and the delivery pipe 3 respectively.

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