Ammonium nitrate recycling structure applied to ammonium nitrate thermal decomposition process

Abstract

The ammonium nitrate recycling structure comprises a melting device and a reaction kettle, the melting device is connected with the reaction kettle through an ammonium nitrate delivery pump, a control valve is arranged between the ammonium nitrate delivery pump and the reaction kettle, and a cooling coil is arranged at a decomposed gas rising section in the reaction kettle. The liquid inlet end of the cooling coil pipe is connected with the melting device through an ammonium nitrate circulating pump, the liquid return end of the cooling coil pipe is connected back to the melting device, and an ammonium nitrate solution in the melting device is used as a cooling medium in the cooling coil pipe and exchanges heat with undecomposed ammonium nitrate steam rising along with nitrous oxide in the reaction kettle; the liquid drops formed after condensation return to the reaction kettle for continuous thermal decomposition, the utilization rate of ammonium nitrate is improved, meanwhile, the ammonium nitrate solution serving as a cooling medium in the cooling coil returns to the melting device after heat exchange and temperature rise, and the energy consumption of the melting device for preheating the ammonium nitrate solution is reduced.

Description

Technical Field

[0001] This utility model relates to the field of special industrial gas preparation technology, specifically to an ammonium nitrate recovery and utilization structure applied to the thermal decomposition process of ammonium nitrate. Background Technology

[0002] High-purity nitrous oxide is an important raw material in the electronics industry. During the manufacturing process of ICs (semiconductors) and LEDs (light-emitting diodes), the silica film generated from the chemical reaction of nitrous oxide is deposited on the silicon substrate, acting as a buffer layer to prevent the entry of harmful impurities. With the development of LEDs and semiconductors, the demand for high-purity nitrous oxide gas is constantly increasing. Industrially, the synthesis of high-purity nitrous oxide mainly originates from the decomposition of ammonium nitrate.

[0003] In the nitrous oxide synthesis process, nitrous oxide produced by the decomposition of ammonium nitrate solution in the reactor rises within the reactor and is discharged from the top. It then undergoes filtration, condensation, washing, and purification processes to finally obtain high-purity nitrous oxide. However, actual testing revealed that the decomposition rate of ammonium nitrate is not high. The rising gas in the reactor contains undecomposed ammonium nitrate vapor, which, along with the nitrous oxide produced during decomposition, enters the filter and is treated as waste liquid, significantly increasing production costs. Utility Model Content

[0004] To address the aforementioned problems, this invention proposes an ammonium nitrate recovery and utilization structure for the thermal decomposition process of ammonium nitrate. The structure utilizes the ammonium nitrate that does not enter the reactor for decomposition in the melting tank as a condensate to condense and recover the ammonium nitrate vapor that rises with nitrous oxide in the reactor.

[0005] To achieve the above objectives, the following technical solution is adopted: an ammonium nitrate recovery and utilization structure applied to the ammonium nitrate thermal decomposition process, including a melter and a reaction vessel. The melter is connected to the reaction vessel through an ammonium nitrate delivery pump. A control valve is installed between the ammonium nitrate delivery pump and the reaction vessel. A cooling coil is installed in the rising section of the decomposition gas in the reaction vessel. The liquid inlet end of the cooling coil is connected to the melter through an ammonium nitrate circulation pump, and the liquid return end of the cooling coil is connected back to the melter for heat exchange with the rising gas generated by the thermal decomposition of ammonium nitrate in the reaction vessel.

[0006] Furthermore, an emergency shut-off valve is installed at the inlet end of the ammonium nitrate circulating pump and the cooling coil.

[0007] Furthermore, the cooling coils are made of stainless steel.

[0008] The beneficial effects of this invention are as follows: This invention features a cooling coil installed in the rising section of the decomposition gas in the reactor, and forms a circulation loop with the melter through an ammonium nitrate circulation pump. The ammonium nitrate solution in the melter is used as the cooling medium in the cooling coil, which can reduce the temperature of the undecomposed ammonium nitrate vapor rising with nitrous oxide in the reactor. After heat exchange, the vapor condenses into droplets, which fall back into the reactor under gravity to continue thermal decomposition. At the same time, the ammonium nitrate solution in the cooling coil, which serves as the cooling medium, returns to the melter after heat exchange and temperature increase, thus reducing the energy consumption of the melter in preheating the ammonium nitrate solution. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the present invention;

[0010] Figure 2 This is a schematic diagram of the cooling coil.

[0011] As shown in the figure: 1. Melter; 2. Reactor; 3. Ammonium nitrate transfer pump; 4. Control valve; 5. Cooling coil; 6. Ammonium nitrate circulation pump; 7. Emergency shut-off valve. Detailed Implementation

[0012] Example 1

[0013] In traditional ammonium nitrate thermal decomposition processes, the reaction vessel is used to thermally decompose ammonium nitrate. Since the decomposition temperature within the vessel needs to reach 245°C, a melting device is typically placed before the vessel to preheat the ammonium nitrate solution. When the solution reaches 180°C, it enters the reaction vessel for thermal decomposition. Ammonium nitrate vapors within the vessel, along with the nitrous oxide produced during decomposition, exit the vessel and enter a filter.

[0014] This embodiment will be described in conjunction with the accompanying drawings, such as... Figure 1 As shown, this example provides an ammonium nitrate recovery and utilization structure applied to the ammonium nitrate thermal decomposition process, including the aforementioned melter 1 and reactor 2. The melter 1 is connected to the reactor 2 via an ammonium nitrate delivery pump 3. A control valve 4 is installed between the ammonium nitrate delivery pump 3 and the reactor 2. A stainless steel cooling coil 5 is installed in the rising section of the decomposition gas in the reactor 2. The liquid inlet end of the cooling coil 5 is connected to the melter 1 via an ammonium nitrate circulation pump 6, and the liquid return end of the cooling coil 5 is connected back to the melter 1. An emergency shut-off valve 7 is installed between the ammonium nitrate circulation pump 6 and the liquid inlet end of the cooling coil 5, and an interlock control is set with the liquid level of the melter 1 to prevent the feed to the reactor 2 from being interrupted due to the low liquid level of the melter 1, which would affect the decomposition reaction of ammonium nitrate.

[0015] In the structure proposed in this embodiment, during the thermal decomposition of ammonium nitrate, the preheated ammonium nitrate solution in the melting vessel 1 is introduced into the reaction vessel 2 via the ammonium nitrate transfer pump 3 by opening the control valve 4. The ammonium nitrate solution in the reaction vessel 2 decomposes under heat. The ammonium nitrate circulation pump 6 then pumps the remaining ammonium nitrate solution in the melting vessel 1 into the cooling coil 5 located within the reaction vessel 2. This portion of the ammonium nitrate solution serves as a cooling medium, forming a circulation. When the gas generated by the decomposition of the ammonium nitrate solution in the reaction vessel 2 rises and passes through the cooling coil 5, the undecomposed ammonium nitrate vapor carried in the gas forms droplets after heat exchange. Under the influence of gravity, these droplets fall back to the bottom of the reaction vessel 2 to continue decomposition, while nitrous oxide continues to rise, leaving the reaction vessel 2 and entering the filtration equipment. Furthermore, the cooling medium in the cooling coil 5 is heated and returned to the melting vessel 1, reducing the energy consumption of the melting vessel 1.

[0016] This utility model is not limited to this embodiment. Any equivalent concept or modification within the technical scope disclosed in this utility model shall be included in the protection scope of this utility model.

Claims

1. An ammonium nitrate recovery and utilization structure applied to an ammonium nitrate thermal decomposition process, comprising a melter (1) and a reaction vessel (2), wherein the melter (1) is connected to the reaction vessel (2) via an ammonium nitrate delivery pump (3), and a control valve (4) is provided between the ammonium nitrate delivery pump (3) and the reaction vessel, characterized in that, A cooling coil (5) is installed in the rising section of the decomposition gas in the reactor (2). The liquid inlet of the cooling coil (5) is connected to the melter (1) through the ammonium nitrate circulation pump (6), and the liquid return end of the cooling coil (5) is connected back to the melter (1) for heat exchange with the rising gas generated by the thermal decomposition of ammonium nitrate in the reactor (2).

2. The ammonium nitrate recycling structure according to claim 1, characterized in that, An emergency shut-off valve (7) is provided at the inlet end of the ammonium nitrate circulating pump (6) and the cooling coil (5).

3. The ammonium nitrate recycling structure according to claim 2, characterized in that, The cooling coil (5) is made of stainless steel.

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