A device utilizing heat of solvent rearrangement reaction

Abstract

The utility model relates to a device for utilizing the heat of solvent rearrangement reaction. The top of the rearrangement reaction tank is connected to an intermediate medium evaporator and a screw expander in sequence through a pipeline; the screw expander is connected to an intermediate medium condenser in sequence through a pipeline and then to an intermediate medium storage tank; the intermediate medium storage tank is connected to an intermediate medium circulation pump, an intermediate medium preheater, and an intermediate medium evaporator through a pipeline; the intermediate medium evaporator is connected to the screw expander through a pipeline to form an intermediate medium circulation system. The utility model has a simple process and low equipment investment cost. Through the mixed solution rearrangement reaction, not only the reaction heat is taken away by gasification of cyclohexane, but the high-temperature cyclohexane gas can also provide heat, which can not only reduce the amount of circulating water used in the device, but also achieve the purpose of energy saving and consumption reduction.

Description

Technical Field

[0001] The utility model relates to the field of chemical equipment, in particular to a device utilizing solvent rearrangement reaction heat. Background Art

[0002] Caprolactam (CPL) is an important organic chemical raw material, mainly used to produce polyamide 6 engineering plastics and polyamide 6 fibers. Polyamide 6 engineering plastics are mainly used as components and assemblies of automobiles, ships, electronic appliances, industrial machinery and daily consumer goods, etc. Polyamide 6 fibers can be made into textiles, industrial yarns and carpet yarns, etc. The world's industrialized caprolactam can be divided into toluene method, phenol method and benzene method according to the production process and the raw materials used. There are two main technical routes for producing caprolactam using benzene as raw material, namely cyclohexanone-hydroxylamine technical route and cyclohexanone-aminoximation technical route. In recent years, all new caprolactam units have adopted the aminoximation technical route, that is, hydrogen peroxide, liquid ammonia and cyclohexanone are used as raw materials, and cyclohexanone oxime is directly generated in one step. Cyclohexanone oxime undergoes Beckmann rearrangement reaction in the fuming sulfuric acid catalyst system. The reaction formula is as follows:

[0003]

[0004] The conversion of cyclohexanone oxime into caprolactam via the Beckmann rearrangement reaction is a highly exothermic reaction. Therefore, the caprolactam production process requires a large amount of circulating water to remove heat. Failure to recycle the reaction heat not only wastes a large amount of reaction heat, but also increases the amount of circulating water used.

[0005] A method for preparing amides by heterogeneous oximation rearrangement (CN200510032184.0) introduces the use of cyclohexanone, hydrogen peroxide and ammonia as raw materials, alkanes or cycloalkanes that are inert in the fuming sulfuric acid system, or their mixtures as inert solvents, in the presence of titanium silicon molecular sieves, and the generation of cyclohexanone oxime through heterogeneous catalytic reaction; the product is extracted by an inert solvent and then undergoes a Beckmann rearrangement reaction under the action of fuming sulfuric acid containing free SO3. Cyclohexanone oxime is dissolved in an inert solvent and fed as a mixed solution. Most of the heat in the reaction can be taken away by cyclohexane vaporization, reducing the problems of uneven mixing of the rearrangement reaction materials, high local temperatures, and many side reactions. However, the solvent needs to be condensed and recovered during the rearrangement process, and the heat of the solvent is not recovered. Summary of the invention

[0006] In view of the problems existing in the prior art, the utility model provides a device for utilizing the heat of solvent rearrangement reaction, which is suitable for a device for producing caprolactam by dissolving cyclohexanone oxime in an inert solvent cyclohexane and feeding it in the form of a mixed solution to undergo Beckmann rearrangement reaction. Not only can the heat of Beckmann rearrangement reaction be effectively utilized, but also the circulating water consumption of the caprolactam device can be reduced, and the circulating water return temperature can be lowered, thereby achieving the purpose of energy saving and consumption reduction.

[0007] The utility model is realized by the following technical solutions:

[0008] A device utilizing the heat of solvent rearrangement reaction, wherein the top of a rearrangement reaction tank is connected to an intermediate medium evaporator and a screw expander in sequence through a pipeline; the screw expander is connected to an intermediate medium condenser in sequence through a pipeline and then to an intermediate medium storage tank; the intermediate medium storage tank is connected to an intermediate medium circulation pump, an intermediate medium preheater, and an intermediate medium evaporator through a pipeline; the intermediate medium evaporator is then connected to the screw expander through a pipeline to form an intermediate medium circulation system.

[0009] Preferably, the intermediate medium evaporator outlet is connected to the intermediate medium preheater through a pipeline and then connected to the reflux tank, and the reflux tank is connected to the cyclohexane delivery pump through a line pipeline.

[0010] Preferably, the screw expander, reduction gearbox and generator form a screw expander generator set.

[0011] Preferably, the intermediate medium condenser is provided with cooling water inlet and outlet pipes.

[0012] Preferably, the rearrangement reaction tank is provided with an inlet pipe for the mixed solution of cyclohexane and cyclohexanone oxime.

[0013] The utility model has the following beneficial effects:

[0014] 1. The process is simple and the equipment investment cost is low.

[0015] 2. Through the mixed solution rearrangement reaction, not only the reaction heat is taken away by the gasification of cyclohexane, but the high-temperature cyclohexane gas can also provide heat.

[0016] 3. By utilizing the heat of high-temperature cyclohexane gas, it can not only reduce the amount of circulating water used in the device, but also achieve the goal of energy saving and consumption reduction.

[0017] 4. The heat of high-temperature cyclohexane gas is used for expansion and power generation, which can provide power for other operating equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of the utility model device;

[0019] In the figure, 1. rearrangement reaction tank, 2. intermediate medium evaporator, 3. reflux tank, 4. intermediate medium preheater, 5. cyclohexane delivery pump, 6. intermediate medium condenser, 7. intermediate medium storage tank, 8. intermediate medium circulation pump, 9. screw expander, 10. reduction box, 11. generator. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the present invention and implement it, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the embodiments are not intended to limit the present invention.

[0021] Example 1

[0022] A device utilizing heat of solvent rearrangement reaction, wherein the top of a rearrangement reaction tank 1 is connected to an intermediate medium evaporator 2 and a screw expander 9 in sequence through a pipeline; the screw expander 9 is connected to an intermediate medium condenser 6 in sequence through a pipeline and then to an intermediate medium storage tank 7; the intermediate medium storage tank 7 is connected to an intermediate medium circulation pump 8, an intermediate medium preheater 4, and an intermediate medium evaporator 2 through a pipeline; the intermediate medium evaporator 2 is further connected to the screw expander 9 through a pipeline to form an intermediate medium circulation system.

[0023] Preferably, the outlet of the intermediate medium evaporator 2 is connected to the intermediate medium preheater 4 through a pipeline and then connected to the reflux tank 3, and the reflux tank 3 is connected to the cyclohexane delivery pump 5 through a line pipeline.

[0024] Preferably, the screw expander 9, the reduction gearbox 10 and the generator 11 form a screw expander generator set.

[0025] Preferably, the intermediate medium condenser 6 is provided with cooling water inlet and outlet pipes.

[0026] Preferably, the rearrangement reaction tank 1 is provided with an inlet pipe for the mixed solution of cyclohexane and cyclohexanone oxime.

[0027] The process carried out by the above device is:

[0028] During the specific operation, the high-temperature cyclohexane gas phase from the top of the rearrangement reaction tank 1 enters the intermediate medium evaporator 2 to exchange heat with the liquid intermediate medium, and the liquid intermediate medium absorbs the heat of the high-temperature gas phase and becomes gaseous, forming high-temperature and high-pressure intermediate medium steam. At the same time, the cyclohexane steam condenses into a liquid phase and enters the intermediate medium preheater 4, and enters the reflux tank 3 after being preheated with the intermediate medium transported by the intermediate medium delivery pump, and is transported to the cyclohexane storage tank after being pressurized by the cyclohexane delivery pump 5. The high-temperature and high-pressure intermediate medium steam enters the screw expander 9, and the pressure difference between the steam entering and leaving the expander is used to drive the screw machine to expand and work, and then the reduction box 10 drives the generator to generate electricity, realizing the conversion of the pressure difference energy of the steam into electrical energy. The gaseous low-temperature and low-pressure working fluid after work is discharged from the expander 9 and enters the intermediate medium condenser 6, and is condensed into a liquid and enters the intermediate medium storage tank 7. After being pressurized by the intermediate medium circulation pump 8 in the intermediate medium storage tank 7, it is pumped into the intermediate medium preheater 4 and the intermediate medium evaporator 2 again, and the cycle is repeated in this way, and finally the low-grade heat energy in the high-temperature cyclohexane gas phase of the rearrangement reaction tank is converted into high-pressure and high-temperature intermediate medium, and finally the heat energy is converted into electrical energy output through the screw expansion generator set composed of the screw expander 9, the reduction box 10, the generator 11, etc.

[0029] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A device for utilizing heat of solvent rearrangement reaction, characterized in that: The top of the rearrangement reaction tank (1) is connected to the intermediate medium evaporator (2) and the screw expander (9) in sequence through a pipeline; the screw expander (9) is connected to the intermediate medium condenser (6) in sequence through a pipeline and then connected to the intermediate medium storage tank (7); the intermediate medium storage tank (7) is connected to the intermediate medium circulation pump (8), the intermediate medium preheater (4), and the intermediate medium evaporator (2) through a pipeline; the intermediate medium evaporator (2) is further connected to the screw expander (9) through a pipeline to form an intermediate medium circulation system.

2. The device for utilizing heat of solvent rearrangement reaction according to claim 1, characterized in that: The outlet of the intermediate medium evaporator (2) is connected to the intermediate medium preheater (4) through a pipeline and then connected to the reflux tank (3). The reflux tank (3) is connected to the cyclohexane delivery pump (5) through a line pipeline.

3. The device for utilizing heat of solvent rearrangement reaction according to claim 1, characterized in that: The screw expander (9), the reduction box (10) and the generator (11) form a screw expander generator set.

4. The device for utilizing heat of solvent rearrangement reaction according to claim 1, characterized in that: The intermediate medium condenser (6) is provided with cooling water inlet and outlet pipes.

5. The device for utilizing heat of solvent rearrangement reaction according to claim 1, characterized in that: The rearrangement reaction tank (1) is provided with an inlet pipe for the mixed solution of cyclohexane and cyclohexanone oxime.

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