Heat recycling device for preparing amino-capronitrile from caprolactam

Abstract

The utility model relates to the field of chemical engineering and energy recovery, and particularly provides a heat recycling device for preparing aminocapronitrile from caprolactam, which comprises a reactor, a heat exchanger, a heat exchanger, a heat exchanger, a heat exchanger and a heat exchanger, and is characterized in that one end of the reactor is provided with a process gas inlet while the other end is provided with a process gas outlet; the device further comprises a heat exchanger and a heat recoverer, the process gas outlet is connected to the heat exchanger through a pipeline and then is led out after being connected to the heat recoverer, and a heat exchange medium pipeline of the heat recoverer is connected with the expansion unit. Heat released in the cooling process of a process medium can be fully recycled, organic steam with high pressure is generated by utilizing the characteristic that the low-temperature saturated steam of an organic working medium is high in pressure, the expansion unit is driven to operate, internal energy is converted into kinetic energy, and no adverse effect is caused to the original process flow.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical industry and energy recovery, and relates to a heat recovery and utilization device for preparing aminocapronitrile from caprolactam. Background Art

[0002] The production of aminocapronitrile from caprolactam is a process currently under development in China for the production of hexamethylenediamine and, subsequently, nylon 6,6. The reaction temperature for the production of aminocapronitrile from caprolactam is high, typically controlled at 300-350°C. Throughout the entire process, the process medium must be raised to 300-350°C to initiate the reaction, then lowered to below 40°C to separate the product. This heating and cooling process consumes significant energy. While heat exchangers are currently commonly used to partially recover heat, reducing the reactor outlet temperature from 300-350°C to 120-150°C, the heat generated by cooling the process medium from 120-150°C to 75-95°C is largely used for cooling with circulating water, leaving it unused and consuming significant amounts of circulating water resources. Summary of the Invention

[0003] The utility model provides a heat recovery and utilization device for producing aminocapronitrile from caprolactam, which fully recovers the heat released during the cooling process of the process medium, utilizes the high pressure of the low-temperature saturated vapor of the organic working medium, generates relatively high-pressure organic vapor, and drives an expansion unit.

[0004] The technical solution of the utility model is to provide a heat recovery and utilization device for preparing aminocapronitrile from caprolactam, comprising a reactor, one end of which is provided with a process gas inlet, and the other end of which is provided with a process gas outlet; the device also comprises a heat exchanger and a heat recovery device, the process gas outlet is connected to the heat exchanger through a pipeline, and then connected to the heat recovery device and then led out, and the heat exchange medium pipeline of the heat recovery device is connected to the expansion unit.

[0005] Optionally, the newly added process gas is connected to the process gas inlet of the reactor after exchanging heat with the gas from the process gas outlet in the heat exchanger.

[0006] Optionally, the device is further provided with a heater, which is located between the heat exchanger and the process gas inlet of the reactor. The newly added process gas passes through the heat exchanger and is then heated by the heater before finally entering the process gas inlet of the reactor.

[0007] Optionally, a cold mass pump is installed between the heat exchange medium pipeline inlet of the heat recovery device and the discharge pipe of the expansion unit, and the heat exchange medium pipeline outlet of the heat recovery device is connected to the return pipe of the expansion unit.

[0008] Optionally, the expander unit is a screw expander or a turbine expander.

[0009] Optionally, the expansion unit is a turbine expander, and the turbine expander is single-stage or multi-stage.

[0010] Optionally, the cold and hot media used in the heat exchanger and heat recovery device for heat exchange or heat recovery are in countercurrent contact.

[0011] Optionally, a process gas inlet is provided at the top of the reactor and a process gas outlet is provided at the bottom. The gas at the process gas outlet passes through the tube side of the heat exchanger and the tube side of the heat recovery device in sequence; the newly added process gas passes through the shell side of the heat exchanger and is connected to the heater.

[0012] The utility model has the following beneficial effects:

[0013] The utility model uses a heat exchanger to cool the process gas exiting the reactor at a temperature of 300-350°C to 120-150°C with newly added process gas. The gas is then introduced into a heat recovery device to exchange heat with the organic working fluid of the expansion unit, reducing its temperature to 75-95°C. During the cooling process, a large amount of caprolactam and aminocapronitrile transform from gas to liquid, releasing a large amount of phase change heat. The heat released by the cooling of the process gas is used to heat the low-boiling-point organic working fluid, vaporizing it and driving the expansion unit to operate, converting internal energy into kinetic energy. This effectively utilizes the waste heat from the production of aminocapronitrile from caprolactam, is energy-efficient and environmentally friendly, and does not adversely affect the original process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of the present utility model. DETAILED DESCRIPTION

[0015] The embodiments of the present invention will be described in detail below with reference to the examples and drawings. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0016] like Figure 1As shown, the present invention provides a heat recovery and utilization device for producing aminocapronitrile from caprolactam. The device comprises a reactor 1 having a process gas inlet at one end and a process gas outlet at the other end. The device also comprises a heat exchanger 3 and a heat recovery unit 4. The process gas outlet is connected to the heat exchanger via a pipeline, which then connects to the heat recovery unit 4 and then leads out. The heat exchange medium pipeline of the heat recovery unit 4 is connected to an expansion unit 5. The process gas exiting the reactor exchanges heat with the process gas entering the heater through the heat exchanger. A first heat recovery process is performed, recovering the heat that has been reduced from 300-350°C to 120-150°C. The process gas exiting the heat exchanger 3 passes through the heat recovery unit 4 to heat the organic working medium, reducing the process gas temperature from 120-150°C to 75-95°C. The organic working medium temperature rises by 40-50°C to 105-130°C. The organic working medium absorbs heat, increasing its temperature and changing from a liquid to a gaseous state, resulting in a higher pressure. The organic working medium gas pushes the expansion unit to perform work, converting pressure energy into kinetic energy, which is then utilized to recover heat energy.

[0017] In some embodiments, the newly added process gas is connected to the process gas inlet of reactor 1 after exchanging heat with the gas from the process gas outlet in a heat exchanger. The 300-350°C process gas from the reactor preheats the newly added process gas, raising the temperature of the newly added process gas from 50-100°C to 150-220°C.

[0018] In a more preferred embodiment, the apparatus further comprises a heater 2, which is located between the heat exchanger and the process gas inlet of reactor 1. The newly added process gas passes through the heat exchanger and is then heated by the heater before entering the process gas inlet of reactor 1. The process gas, at a temperature of 150-220°C, is further heated in heater 2 before entering the reactor for reaction.

[0019] In some embodiments, a refrigerant pump 6 is installed between the heat exchange medium pipeline inlet of the heat recovery unit 4 and the discharge pipe of the expansion unit 5. The heat exchange medium pipeline outlet of the heat recovery unit 4 is connected to the return pipe of the expansion unit 5. The refrigerant pump 6 transports the organic working medium into the heat recovery unit 4 for heating, converting the liquid into a gas. The organic working medium can be a low-boiling-point substance such as ammonia, freon, methanol, or ethanol.

[0020] In a more preferred embodiment, the expander assembly is a screw expander or a turbine expander. Further preferably, the expander assembly is a turbine expander, and the turbine expander is single-stage or multi-stage.

[0021] In some embodiments, the cold and hot media used for heat exchange or heat recovery in the heat exchanger 3 and the heat recovery device 4 are in countercurrent contact.

[0022] In some embodiments, a process gas inlet is provided at the top of the reactor 1, and a process gas outlet is provided at the bottom. The gas at the process gas outlet passes through the tube side of the heat exchanger 3 and the tube side of the heat recovery device 4 in sequence; the newly added process gas passes through the shell side of the heat exchanger 3 and is connected to the heater to improve the heat exchange efficiency.

[0023] The device provided by the utility model can efficiently recycle the heat of the process gas at 300-350° C. produced by producing aminocapronitrile from caprolactam, separate and treat the cooled material, and obtain the target product aminocapronitrile.

[0024] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.

Claims

1. A heat recovery and utilization device for preparing aminocapronitrile from caprolactam, characterized in that: The device comprises a reactor (1) having a process gas inlet at one end and a process gas outlet at the other end; the device also comprises a heat exchanger (3) and a heat recovery device (4); the process gas outlet is connected to the heat exchanger through a pipeline, and then connected to the heat recovery device (4) and then led out; the heat exchange medium pipeline of the heat recovery device (4) is connected to the expansion unit (5).

2. The device according to claim 1, characterized in that: The newly added process gas exchanges heat with the gas from the process gas outlet in the heat exchanger and is then connected to the process gas inlet of the reactor (1).

3. The device according to claim 2, characterized in that: The device is further provided with a heater (2), which is located between the heat exchanger and the process gas inlet of the reactor (1). The newly added process gas passes through the heat exchanger and is then heated by the heater before finally entering the process gas inlet of the reactor (1).

4. The device according to claim 1, characterized in that: A cold mass pump (6) is installed between the heat exchange medium pipeline inlet of the heat recovery device (4) and the discharge pipe of the expansion unit (5), and the heat exchange medium pipeline outlet of the heat recovery device (4) is connected to the return pipe of the expansion unit (5).

5. The device according to claim 4, characterized in that: The expander unit is a screw expander or a turbine expander.

6. The device according to claim 5, characterized in that: The expansion unit is a turbine expander, and the turbine expander is single-stage or multi-stage.

7. The device according to any one of claims 1 to 6, characterized in that: The cold and hot media used in the heat exchanger (3) and the heat recovery device (4) for heat exchange or heat recovery are in countercurrent contact.

8. The device according to any one of claims 1 to 6, characterized in that: The reactor (1) is provided with a process gas inlet at the top and a process gas outlet at the bottom. The gas at the process gas outlet passes through the tube side of the heat exchanger (3) and the tube side of the heat recovery device (4) in sequence. The newly added process gas passes through the shell side of the heat exchanger (3) and is then connected to the heater.

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