An energy-saving device for liquid ammonia gasification

Abstract

The utility model relates to an energy-saving device for liquid ammonia gasification, the device comprises a reactor, the bottom of the reactor is connected to a circulation pump, a heat exchanger, a cooler, and a mixer in sequence through a pipeline, and then connected to the top of the reactor to form a circulation system, a remote thermometer is provided on the connecting pipeline between the cooler and the mixer; the liquid ammonia pipeline is connected to the chilled water preheater and then connected to the heat exchanger through a pipeline, the heat exchanger is a heat extraction component at the bottom of the ammonia evaporation tower, and the top of the ammonia evaporation tower is connected to the mixer through a line pipeline. The utility model first uses the coldness of liquid ammonia for the chilled water system, which can reduce the operating load of the chilled water unit. Then, the heat of the ammonia oximation reaction is used for the gasification of liquid ammonia, which not only reduces the amount of circulating water used in the ammonia oximation reaction device, but also reduces the amount of steam required for the gasification of liquid ammonia, thereby achieving the purpose of energy saving and consumption reduction. The gaseous ammonia can be used in the ammonia oximation reaction section and the ammonium sulfate section in the production of caprolactam.

Description

Technical Field

[0001] The utility model relates to the field of chemical equipment, in particular to an energy-saving device for gasifying liquid ammonia. Background Art

[0002] Cyclohexanone oxime is a key intermediate in the production of caprolactam. The current mainstream process is to react cyclohexanone with ammonia and hydrogen peroxide under the catalysis of titanium silicon molecular sieve to produce cyclohexanone oxime directly and highly selectively in one step. This process greatly simplifies the production process, significantly reduces equipment investment, and reduces production costs. The main reaction formula of cyclohexanone ammoximation is as follows:

[0003]

[0004] The ammoximation reaction is a highly exothermic reaction with a reaction heat of about 300 kJ / mol oxime. During normal operation, the reaction system does not require any external heat. The reaction heat can maintain the heat required for continuous production. Excess reaction heat causes the material in the kettle to heat up rapidly, so it must be removed in time. Current industrial equipment basically uses external circulation heat extraction to control the reaction temperature. The reaction temperature is stably controlled by automatically adjusting the circulating water volume of the reactor liquid cooler. Circulating water is needed to remove heat during the production process.

[0005] Ammonia is one of the four main raw materials in the production process of caprolactam. It is not only required to be added in the ammoximation reaction, but also in the subsequent ammonium sulfate neutralization process. However, gaseous ammonia is not easy to transport. In industry, liquid ammonia is stored in spherical tanks and then heated and gasified into gaseous ammonia for caprolactam production. A large amount of steam is required to provide heat during the gasification process, and the cooling capacity of liquid ammonia is not fully utilized. Summary of the invention

[0006] In view of the problems existing in the prior art, the utility model provides an energy-saving device for liquid ammonia gasification, which is suitable for a production device for producing caprolactam by ammoximation of cyclohexanone. The invention can use the heat of the cyclohexanone ammoximation reaction for liquid ammonia gasification, which not only reduces the amount of circulating water in the ammoximation reaction device, but also reduces the amount of steam required for liquid ammonia gasification, effectively utilizes the cooling capacity of liquid ammonia, and ultimately achieves the purpose of energy saving and consumption reduction.

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

[0008] An energy-saving device for liquid ammonia gasification, the device comprises a reactor, the bottom of the reactor is connected to a circulation pump, a heat exchanger, a cooler and a mixer in sequence through a pipeline, and then connected to the top of the reactor to form a circulation system, a remote thermometer is provided on the connecting pipeline between the cooler and the mixer; the liquid ammonia pipeline is connected to a chilled water preheater and then to a heat exchanger through a pipeline, the heat exchanger is a heat extraction component at the bottom of an ammonia distillation tower, and the top of the ammonia distillation tower is connected to the mixer through a line pipeline.

[0009] Preferably, the ammonia evaporation tower and the heat exchanger cylinder are of an integrated structure, the heat exchanger is of a withdrawable structure, and a pressure regulating valve is provided on the top pipeline of the ammonia evaporation tower.

[0010] Preferably, a temperature regulating valve is provided on the circulating water supply pipe of the cooler, and the remote thermometer and the temperature regulating valve form a temperature control loop through a transmitter to control the outlet temperature of the cooler.

[0011] Preferably, the top of the ammonia distillation tower is also connected to the ammonium sulfate device through a pipeline.

[0012] Preferably, the chilled water inlet and outlet pipes of the chilled water preheater are in communication with the chilled water system.

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

[0014] 1. Simple equipment and low investment cost.

[0015] 2. Using the energy of liquid ammonia in the chilled water system first can reduce the operating load of the chilled water unit.

[0016] 3. The heat from the ammoximation reaction is then used for the gasification of liquid ammonia, which not only reduces the amount of circulating water used in the ammoximation reaction device, but also reduces the amount of steam required for the gasification of liquid ammonia, thereby achieving the goal of energy saving and consumption reduction.

[0017] 4. Gaseous ammonia can be used in the ammoximation reaction section and ammonium sulfate section in caprolactam production. 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. Reactor, 2. Circulation pump, 3. Ammonia distillation tower, 4. Cooler, 5. Heat exchanger, 6. Chilled water preheater, 7. Chilled water system user, 8. Mixer, 9. Pressure regulating valve, 10. Temperature regulating valve, 11. Remote thermometer. 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] An energy-saving device for liquid ammonia gasification, the device comprises a reactor 1, the bottom of the reactor 1 is connected to a circulation pump 2, a heat exchanger 5, a cooler 4, and a mixer 8 in sequence through a pipeline, and then connected to the top of the reactor 1 to form a circulation system, a remote thermometer 11 is provided on the connecting pipeline between the cooler 4 and the mixer 8; the liquid ammonia pipeline is connected to a chilled water preheater 6 and then connected to the heat exchanger 5 through a pipeline, the heat exchanger 5 is a heat extraction component at the bottom of an ammonia distillation tower 3, and the top of the ammonia distillation tower 3 is connected to the mixer 8 through a line pipeline.

[0023] Preferably, the ammonia evaporation tower 3 and the heat exchanger 5 cylinder are of an integrated structure, the heat exchanger 5 is of a withdrawable structure, and a pressure regulating valve 9 is provided on the top pipeline of the ammonia evaporation tower 3 .

[0024] Preferably, a temperature regulating valve 10 is provided on the circulating water supply pipe of the cooler 4 , and a remote thermometer 11 and the temperature regulating valve 10 form a temperature control loop through a transmitter to control the outlet temperature of the cooler 4 .

[0025] Preferably, the top of the ammonia evaporation tower 3 is also connected to the ammonium sulfate device through a pipeline.

[0026] Preferably, the chilled water inlet and outlet pipes of the chilled water preheater 6 are in communication with the chilled water system 7 .

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

[0028] The high-temperature reaction circulating liquid in the reactor 1 is pressurized by the circulating pump 2, passes through the heat exchanger 5, the cooler 4, the mixer 8 in sequence, and then returns to the reactor 1 to form a circulation system. In this circulation system, heat is first exchanged with liquid ammonia in the heat exchanger 5, and the liquid ammonia is gasified and then the temperature is reduced to within the process index through the circulating water in the cooler 4. A remote thermometer 11 is provided on the connecting pipe between the cooler 4 and the mixer 8, and a temperature regulating valve 10 for automatically controlling the circulating water flow is provided on the circulating water supply pipe of the cooler 4 to form a temperature control loop to control the outlet temperature of the cooler 4. When the temperature is high, the opening of the temperature regulating valve is increased to increase the circulating water flow. Conversely, when the temperature is low, the opening of the temperature regulating valve is reduced.

[0029] The low-temperature liquid ammonia first exchanges heat with the chilled water outlet from the chilled water system 7 after use by the user through the chilled water preheater 6 to reduce the water temperature of the chilled water system. At the same time, the liquid ammonia temperature is preheated and then enters the ammonia still 3. It exchanges heat with the reaction circulating liquid through the heat exchanger 5 and is vaporized into gaseous ammonia in the ammonia still 3. The pressure of the gaseous ammonia is adjusted by the pressure regulating valve 9 on the outlet pipeline. The gaseous ammonia at the top of the ammonia still 3 is divided into two routes: one route is sent to the ammonium sulfate device, and the other route enters the mixer on the circulation pipeline to participate in the ammonia oximation reaction.

[0030] After the chilled water is used by the users of the chilled water system, it is cooled and sent to the users of the chilled water system for use, forming a chilled water system cycle.

[0031] 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. An energy-saving device for gasifying liquid ammonia, the device comprising a reaction kettle (1), characterized in that: The bottom of the reactor (1) is connected to a circulation pump (2), a heat exchanger (5), a cooler (4), and a mixer (8) in sequence through a pipeline, and then connected to the top of the reactor (1) to form a circulation system. A remote thermometer (11) is provided on the connecting pipeline between the cooler (4) and the mixer (8). The liquid ammonia pipeline is connected to the chilled water preheater (6) and then to the heat exchanger (5) through a pipeline. The heat exchanger (5) is a heat extraction component at the bottom of the ammonia evaporation tower (3). The top of the ammonia evaporation tower (3) is connected to the mixer (8) through a line pipeline.

2. The energy-saving device for liquid ammonia gasification according to claim 1, characterized in that: The ammonia evaporation tower (3) and the heat exchanger (5) cylinder are of an integrated structure, the heat exchanger (5) is of a removable structure, and a pressure regulating valve (9) is provided on the top pipeline of the ammonia evaporation tower (3).

3. The energy-saving device for liquid ammonia gasification according to claim 1, characterized in that: A temperature regulating valve (10) is provided on the circulating water supply pipe of the cooler (4), and a remote thermometer (11) and the temperature regulating valve (10) form a temperature control loop through a transmitter to control the outlet temperature of the cooler (4).

4. The energy-saving device for liquid ammonia gasification according to claim 1, characterized in that: The top of the ammonia distillation tower (3) is also connected to the ammonium sulfate device through a pipeline.

5. The energy-saving device for liquid ammonia gasification according to claim 1, characterized in that: The chilled water inlet and outlet pipes of the chilled water preheater (6) are in communication with the chilled water system (7).

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