Apparatus and method for the production of nitrous oxide comprising a tubular reactor

Abstract

The application provides a nitrous oxide preparation device and method containing a tubular reactor, the preparation device creatively uses a tubular reactor to perform a thermal decomposition reaction of an ammonium nitrate solution, the tubulous reactor has a large specific surface area, can effectively remove the heat released in the reaction, has accurate temperature control, low liquid holding capacity and low risk of out-of-control, and is helpful to continuously and stably obtain a nitrous oxide gas product with a purity of greater than or equal to 99.0%, and the tubular reactor module comprises at least two parallel tubular reactors, so that the production capacity can be conveniently expanded under the premise of safety, and the degree of automation is high and the device is safe and reliable.

Description

Technical Field

[0001] This invention relates to the field of nitrous oxide preparation technology, and specifically to an apparatus and method for preparing nitrous oxide containing a tubular reactor. Background Technology

[0002] Nitrous oxide, as an important industrial gas, is mainly used in the medical and electronics industries. In traditional applications, it is mainly used as an anesthetic. However, with the development of modern industry, the application of high-purity nitrous oxide in the electronics industry is becoming more and more widespread. It is an important material for the development of semiconductor technology and is mainly used in integrated circuits, liquid crystal displays and other technical fields. The demand is growing day by day. Therefore, how to prepare nitrous oxide efficiently and safely is also indispensable.

[0003] Currently, nitrous oxide is mainly produced through the thermal decomposition of ammonium nitrate at approximately 245℃~255℃. The main reaction is NH4NO3→N2O+2H2O, which is an exothermic reaction. To maintain the safety of the apparatus and the stability of the reaction, the reaction temperature should be controlled and the released heat should be removed promptly.

[0004] However, current conventional production processes use reactors, which have large volumes but small surface areas, making them prone to localized overheating and runaway reactions. Furthermore, the high liquid holdup poses significant safety risks, and the larger the scale of the equipment, the more difficult it is to ensure stable operation. For example, CN101955167A discloses a technology for the decomposition of ammonium nitrate to produce nitrous oxide. This system mainly consists of a reactor with a feed port, a cooling tower, a dryer, a distillation column, a buffer tank, a compressor, and a condenser, assembled together via connecting pipelines according to their respective functions. However, this system still belongs to the traditional ammonium nitrate decomposition device, without any significant improvement to the reactor, and the problem of temperature control remains. The subsequent equipment is only used for the purification and refining of the reaction products. CN110329999A discloses a generator and method for producing nitrous oxide by wet decomposition of ammonium nitrate, including a reaction vessel and a control system. The reaction vessel is equipped with a temperature measuring mechanism for measuring the internal temperature, a heating component for heating the reactants inside the vessel, and a cooling device for cooling the reactants. The control system includes a heating controller, a cooling controller, and a quenching controller. The heating controller, cooling controller, and quenching controller control the operation of the heating component, the material cooling heat exchanger, and the quenching heat exchanger, respectively. The coordinated operation of the heating component, the material cooling heat exchanger, and the quenching heat exchanger achieves precise control of the reaction temperature. Although this device has multiple additional components in the reaction vessel and can control the reaction temperature, the material has poor fluidity in a single reaction vessel, the reaction degree is uneven, the material quantity is large, and the temperature is not easy to adjust.

[0005] A tubular reactor is a continuous-operation reactor that employs a modular tubular structure and possesses constant flow, constant temperature, and constant pressure operating characteristics. Therefore, there is a need to develop a nitrous oxide preparation apparatus and method incorporating a tubular reactor. This tubular reactor effectively controls the reaction temperature and suppresses or promptly eliminates the generation of by-products, simplifying subsequent purification steps. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a nitrous oxide preparation device and method containing a tubular reactor. The preparation device creatively uses a tubular reactor to carry out the thermal decomposition reaction of ammonium nitrate solution. Taking advantage of the large specific surface area of ​​the tubular reactor, the heat released by the reaction can be effectively removed, the temperature is precisely controlled, the liquid hold-up is low, and the risk of runaway is low. This helps to continuously and stably obtain nitrous oxide gas products with a purity of ≥99.0%. Moreover, the tubular reactor module includes at least two tubular reactors connected in parallel, which can easily expand the production capacity under safe conditions. It has a high degree of automation and is safe and reliable.

[0007] To achieve this objective, the present invention adopts the following technical solution: One objective of this invention is to provide a nitrous oxide preparation apparatus containing a tubular reactor. The apparatus comprises: a material communication tank, a tubular reactor module, and a gas-liquid separator connected in series along the flow direction of an ammonium nitrate solution; the gas outlet of the gas-liquid separator is used to collect nitrous oxide; the liquid outlet of the gas-liquid separator is connected to the first inlet of the material communication tank for collecting ammonium nitrate recovery liquid; wherein the tubular reactor module includes at least two tubular reactors connected in parallel; each tubular reactor is independently equipped with a reactor heater, and the tubular reactor includes a cooling pipe for cooling and a shell side for the thermal decomposition reaction of ammonium nitrate; the bottom inlet of the shell side is connected to the outlet of the material communication tank; fresh ammonium nitrate solution is connected to the second inlet of the material communication tank and / or the spray inlet of the tubular reactor.

[0008] It should be noted that the preparation device described in this invention is used for a continuous process of preparing nitrous oxide. Fresh ammonium nitrate solution can be continuously added through the second inlet of the material communication tank, or it can be added by spraying through the spray inlet of each tubular reactor.

[0009] It should be noted that the material communication tank can help maintain consistent liquid levels in parallel tubular reactors, and help multiple parallel reactors operate synchronously and stably.

[0010] It should be noted that the nitrous oxide tubular reactor is preferably a horizontal nitrous oxide tubular reactor; the cooling pipe is U-shaped along the axial direction of the tubular reactor; a feed inlet is opened at the bottom of the shell side for introducing the recovered ammonium nitrate solution, and the number of feed inlets is 2-5; the number of discharge outlets is 2-5; the cross-sectional shape of the tubular reactor can be any one of circular, elliptical, oblong (a shape combining a rectangle and two semicircles) or rectangular; the reactor heater includes any one of reactor electric heater or reactor jacket heater, the reactor jacket heater forms a jacket space outside the shell side, and heating media such as hot air or heat transfer oil can be introduced according to actual conditions; along the material flow direction, the diameter of the spray holes opened on the feed pipe gradually increases, because the feed pipe is a closed pipe at one end, this setting helps to achieve a consistent spray volume of all spray holes, which is beneficial to the uniform distribution of the sprayed fresh ammonium nitrate solution along the axial direction.

[0011] The preparation apparatus of this invention creatively employs a tubular reactor for the thermal decomposition reaction of ammonium nitrate solution. Utilizing the large specific surface area of ​​the tubular reactor, the heat released during the reaction can be effectively removed, resulting in precise temperature control, low liquid holdup, and low risk of runaway. This facilitates the continuous and stable production of nitrous oxide gas with a purity ≥99.0%. Furthermore, the tubular reactor module includes at least two parallel tubular reactors, allowing for convenient expansion of production capacity while maintaining safety. It boasts a high degree of automation and is highly reliable. Moreover, if either the temperature inside the tubular reactor exceeds the ultra-high set value or the system pressure of the gas-liquid separator exceeds the ultra-high set value, it indicates that the decomposition reaction is too vigorous. In this case, the flow rate of the cooling medium in the cooling tubes needs to be increased to allow heat exchange between the medium and the reactants in the shell side, thereby reducing the temperature of the reactants and decreasing the amount of decomposition.

[0012] As a preferred technical solution of the present invention, the tubular reactor further includes a feed pipe. Along the axial direction of the tubular reactor, the feed pipe is located at the spray inlet of the tubular reactor and extends into the interior of the tubular reactor. Spray holes are uniformly opened on the feed pipe to achieve uniform distribution of fresh ammonium nitrate solution along the axial direction of the tubular reactor.

[0013] As a preferred embodiment of the present invention, each tubular reactor is independently equipped with a reactor thermometer for monitoring the reaction system temperature of the tubular reactor; a cooling water regulating valve is installed on the cooling pipe, and the reactor thermometer is electrically connected to the cooling water regulating valve and the reactor heater respectively.

[0014] As a preferred embodiment of the present invention, the material communication tank is equipped with a material communication tank level gauge, and a feed regulating valve is installed on the fresh ammonium nitrate solution flow pipeline. The material communication tank level gauge is electrically connected to the feed regulating valve.

[0015] As a preferred embodiment of the present invention, a gas-liquid separator pressure gauge is provided on the top of the gas-liquid separator for monitoring system pressure.

[0016] As a preferred embodiment of the present invention, the gas-liquid separator is also provided with an emergency outlet and connected to a safety water seal tank for depressurization in emergency situations.

[0017] As a preferred embodiment of the present invention, the preparation apparatus further includes a preheater for heat exchange between the fresh ammonium nitrate solution and the nitrous oxide gas from the gas-liquid separator.

[0018] As a preferred technical solution of the present invention, the preparation device further includes a cooler, the inlet of which is connected to the gas outlet of the preheater, for further cooling of the nitrous oxide gas from the preheater, and then entering the purification unit for refining, and the resulting condensate is treated as wastewater for harmless treatment.

[0019] A second objective of this invention is to provide a method for preparing nitrous oxide using the preparation apparatus described in the first objective, the method comprising the following steps: Ammonium nitrate solution is introduced into the shell side of at least two parallel tubular reactors, where it undergoes a decomposition reaction under the synergistic action of the reactor heater and cooling pipes. The gaseous products are then separated into nitrous oxide gas and ammonium nitrate recovery liquid. The ammonium nitrate recovery liquid is then circulated into a material communication tank. Fresh ammonium nitrate solution is continuously injected through the second inlet of the material communication tank or the spray inlet of the tubular reactor, thereby continuously producing nitrous oxide.

[0020] As a preferred embodiment of the present invention, the ammonium nitrate solution exchanges heat with nitrous oxide gas from a gas-liquid separator through a preheater. The initial temperature of the ammonium nitrate solution is 120~135℃, such as 120℃, 122℃, 125℃, 127℃, 130℃, 132℃ or 135℃, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0021] Preferably, the water content of the ammonium nitrate solution is 7-18 wt%, such as 7 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, or 18 wt%, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] In this invention, since the melting point of ammonium nitrate is related to its water content, and the melting point of pure ammonium nitrate is relatively high, while the decomposition reaction of ammonium nitrate at different temperatures is quite complex, ammonium nitrate with a certain water content is selected to lower the melting point and avoid premature decomposition during the melting process.

[0023] Preferably, the temperature of the decomposition reaction is 245~255℃, such as 245℃, 246℃, 248℃, 250℃, 252℃, 254℃ or 255℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] As a preferred embodiment of the present invention, the nitrous oxide preparation method includes the following steps: An ammonium nitrate solution at approximately 120-135°C is preheated by a preheater from outside the interface and then enters a feed buffer tank. A level gauge in the feed buffer tank monitors the liquid level and controls the opening of the feed regulating valve to maintain a stable liquid level. The feed buffer tank is connected to several horizontally arranged parallel tubular reactors via a liquid-connecting pipe, meaning the liquid level in the feed buffer tank is consistent with that in each tubular reactor. A reactor thermometer monitors the material temperature and controls the heating output power of the reactor heater to maintain a stable temperature within the range of 245°C-255°C. The ammonium nitrate liquid continuously decomposes into nitrous oxide gas and water vapor, and the liquid feedstock is continuously replenished from the feed buffer tank into the tubular reactors. The tubular reactor has a slender structure, resembling a U-shaped tubular heat exchanger, with the ammonium nitrate liquid on the shell side and cooling water on the tube side. When the reactor thermometer detects that the material temperature exceeds the set high limit, the opening of the cooling water regulating valve is controlled to introduce cooling water into the heat exchange tubes inside the tubular reactor, allowing heat exchange between the material and the material walls to remove excess heat in a timely manner. The thermal decomposition products generated in each reactor are collected through pipelines to the gas-liquid separator. After removing entrained droplets, the liquid returns to the feed buffer tank. The gaseous products are preheated in the ammonium nitrate feed via a preheater, saving electricity consumption in the reactor heater (preferably an electric reactor heater). The gaseous products then pass through a cooler, where the byproduct water vapor is condensed and discharged, while nitrous oxide gas enters the purification unit. When the pressure gauge in the gas-liquid separator detects that the system pressure exceeds the set high limit (i.e., the decomposition reaction is too vigorous), the opening of the cooling water regulating valve is controlled to introduce cooling water into the heat exchange tubes inside the tubular reactor, allowing heat exchange between the material and the material walls to lower the material temperature and reduce the amount of decomposition. In emergencies, pressure can be released through the safety water seal tank.

[0025] Compared with existing technical solutions, the present invention has at least the following beneficial effects: This invention provides a nitrous oxide preparation apparatus and method containing a tubular reactor. The preparation apparatus creatively employs a tubular reactor to perform the thermal decomposition reaction of ammonium nitrate solution. Taking advantage of the large specific surface area of ​​the tubular reactor, the heat released by the reaction can be effectively removed, the temperature control is precise, the liquid hold-up is low, and the risk of runaway is low. This helps to continuously and stably obtain nitrous oxide gas products with a purity of ≥99.0%. Moreover, the tubular reactor module includes at least two parallel tubular reactors, which can easily expand the production capacity under safe conditions. It has a high degree of automation and is safe and reliable. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the nitrous oxide preparation apparatus containing a tubular reactor as described in Embodiment 1 of the present invention.

[0027] Figure 2 This is a schematic diagram of the front view and axial section of the tubular reactor in Embodiment 1 of the present invention.

[0028] Figure 3 This is a schematic diagram of the nitrous oxide preparation apparatus containing a tubular reactor as described in Embodiment 2 of the present invention.

[0029] Figure 4 This is a schematic diagram of the front view and axial section of the tubular reactor in Embodiment 2 of the present invention.

[0030] In the diagram, 1. Safety water seal tank; 2. Gas-liquid separator pressure gauge; 3. Gas-liquid separator; 4. Feed regulating valve; 5. Preheater; 6. Cooler; 7. Material connecting tank level gauge; 8. Material connecting tank; 9. Reactor thermometer; 10. Tubular reactor; 11. Reactor heater; 12. Cooling water regulating valve; 10-1. Cooling water inlet; 10-2. Cooling water outlet; 10-3. Feed inlet; 10-4. Discharge outlet; 10-5. Thermometer port; 10-6. Cooling pipe; 10-7. Feed pipe. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows: Example 1 This embodiment provides a nitrous oxide preparation apparatus containing a tubular reactor, such as... Figure 1 As shown, the preparation apparatus includes: a material communication tank 8 and a tubular reactor module connected in series along the flow direction of the ammonium nitrate solution. Figure 1The part outlined in the dashed line), gas-liquid separator 3; the gas outlet of the gas-liquid separator 3 is used to collect nitrous oxide; the liquid outlet of the gas-liquid separator 3 is connected to the first inlet of the material communication tank 8 and is used to collect ammonium nitrate recovery liquid.

[0033] The tubular reactor module includes three parallel tubular reactors 10, each of which is independently equipped with a reactor heater 11 (reactor electric heater); the front view and axial cross-sectional schematic diagram of the tubular reactor 10 are shown below. Figure 2 As shown, the tubular reactor 10 has a circular cross-sectional shape. The tubular reactor 10 includes a cooling tube 10-6 for cooling and a shell side for the thermal decomposition reaction of ammonium nitrate. The cooling tube 10-6 includes a cooling water inlet 10-1 and a cooling water outlet 10-2. The bottom of the shell side has three feed inlets 10-3 spaced apart and connected to the outlet of the material communication tank 8. The top of the shell side has three discharge outlets 10-4 spaced apart. The lower part of the shell side has two thermometer ports 10-5 spaced apart. Fresh ammonium nitrate solution is connected to the second inlet of the material communication tank 8.

[0034] Each of the tubular reactors 10 is independently equipped with a reactor thermometer 9. The temperature probe of the reactor thermometer 9 is installed inside the shell side of the tubular reactor 10 through the thermometer port 10-5 to monitor the reaction system temperature of the tubular reactor 10. A cooling water regulating valve 12 is installed on the cooling pipe 10-6. The reactor thermometer 9 is electrically connected to the cooling water regulating valve 12 and the reactor heater 11 (reactor electric heater).

[0035] The material communication tank 8 is equipped with a material communication tank level gauge 7, and a feed regulating valve 4 is installed on the fresh ammonium nitrate solution flow pipeline. The material communication tank level gauge 7 is electrically connected to the feed regulating valve 4.

[0036] The gas-liquid separator 3 is equipped with a gas-liquid separator pressure gauge 2 on its top for monitoring system pressure.

[0037] The gas-liquid separator 3 is also equipped with an emergency outlet and is connected to the safety water seal tank 1 for depressurization in emergency situations.

[0038] The preparation apparatus further includes a preheater 5, which is used to exchange heat between the fresh ammonium nitrate solution and the nitrous oxide gas from the gas-liquid separator 3.

[0039] The preparation device further includes a cooler 6, the inlet of which is connected to the gas outlet of the preheater 5, for further cooling of the nitrous oxide gas from the preheater 5, which then enters the purification unit for refining, and the resulting condensate is treated as wastewater for harmless treatment.

[0040] Example 2 This embodiment provides a nitrous oxide preparation apparatus containing a tubular reactor, such as... Figure 3 As shown, the preparation apparatus includes: a material communication tank 8 and a tubular reactor module connected in series along the flow direction of the ammonium nitrate solution. Figure 3 The part outlined in the dashed line), gas-liquid separator 3; the gas outlet of the gas-liquid separator 3 is used to collect nitrous oxide; the liquid outlet of the gas-liquid separator 3 is connected to the first inlet of the material communication tank 8 and is used to collect ammonium nitrate recovery liquid.

[0041] The tubular reactor module includes three parallel tubular reactors 10; each tubular reactor 10 is independently equipped with a reactor heater 11 (reactor electric heater). The front view and axial cross-sectional schematic diagrams of the tubular reactor 10 are shown below. Figure 4 As shown, the tubular reactor 10 has an elongated oval cross-section. The tubular reactor 10 includes a feed pipe 10-7, a cooling pipe 10-6 for cooling, and a shell side for the thermal decomposition reaction of ammonium nitrate. The cooling pipe 10-6 includes a cooling water inlet 10-1 and a cooling water outlet 10-2. A feed inlet 10-3 is opened at the bottom of the shell side and connected to the outlet of the material communication tank 8. Three discharge outlets 10-4 are spaced apart at the top of the shell side. Two thermometer ports 10-5 are spaced apart at the bottom of the shell side. A spray inlet is opened at the top of the shell side. Along the axial direction of the tubular reactor, the feed pipe 10-7 is located at the spray inlet of the tubular reactor 10 and extends into the interior of the tubular reactor 10. Spray holes are evenly distributed on the feed pipe 10-7 to achieve uniform distribution of fresh ammonium nitrate solution along the axial direction of the tubular reactor.

[0042] Each of the tubular reactors 10 is independently equipped with a reactor thermometer 9. The temperature probe of the reactor thermometer 9 is installed inside the shell side of the tubular reactor 10 through the thermometer port 10-5 to monitor the reaction system temperature of the tubular reactor 10. A cooling water regulating valve 12 is installed on the cooling pipe 10-6. The reactor thermometer 9 is electrically connected to the cooling water regulating valve 12 and the reactor heater 11 (reactor electric heater).

[0043] The material communication tank 8 is equipped with a material communication tank level gauge 7, and a feed regulating valve 4 is installed on the fresh ammonium nitrate solution flow pipeline. The material communication tank level gauge 7 is electrically connected to the feed regulating valve 4.

[0044] The gas-liquid separator 3 is equipped with a gas-liquid separator pressure gauge 2 on its top for monitoring system pressure.

[0045] The gas-liquid separator 3 is also equipped with an emergency outlet and is connected to the safety water seal tank 1 for depressurization in emergency situations.

[0046] The preparation apparatus further includes a preheater 5, which is used to exchange heat between the fresh ammonium nitrate solution and the nitrous oxide gas from the gas-liquid separator 3.

[0047] The preparation device further includes a cooler 6, the inlet of which is connected to the gas outlet of the preheater 5, for further cooling of the nitrous oxide gas from the preheater 5, which then enters the purification unit for refining, and the resulting condensate is treated as wastewater for harmless treatment.

[0048] Example 3 This embodiment provides a method for preparing nitrous oxide, which is carried out using the preparation apparatus of Example 1, and includes the following steps: An ammonium nitrate solution with a temperature of 125°C and a water content of 10 wt% is preheated, buffered in a material communication tank, and then enters the shell side of three parallel tubular reactors. Under the synergistic action of the reactor electric heater and the cooling pipes for cooling, a decomposition reaction is carried out at a temperature of 250°C. The gaseous products enter a gas-liquid separator for gas-liquid separation. The ammonium nitrate droplets carried by the nitrous oxide gas are separated and fall, and are recovered and recycled back into the material communication tank for circulation. The nitrous oxide gas is further cooled by a cooler and then enters a purification unit for refining. The resulting condensate is treated as wastewater for harmless treatment.

[0049] In this embodiment, the above-described apparatus and method are used to prepare nitrous oxide. The temperature of the reactants can be precisely controlled, ensuring the continuous and stable operation of the apparatus. The purity of nitrous oxide in the resulting gas reaches 99.7%.

[0050] Example 4 This embodiment provides a method for preparing nitrous oxide, which is carried out using the preparation apparatus of Example 1, and includes the following steps: An ammonium nitrate solution with a temperature of 120°C and a water content of 7wt% is preheated, buffered in a material communication tank, and then enters the shell side of three parallel tubular reactors. Under the synergistic action of the reactor electric heater and the cooling pipes for cooling, a decomposition reaction takes place at a temperature of 245°C. The gaseous products enter a gas-liquid separator for gas-liquid separation. The ammonium nitrate droplets carried by the nitrous oxide gas are separated and fall, and are recovered and recycled back into the material communication tank for circulation. The nitrous oxide gas is further cooled by a cooler and then enters a purification unit for refining. The resulting condensate is treated as wastewater for harmless treatment.

[0051] In this embodiment, the above-described apparatus and method are used to prepare nitrous oxide. The temperature of the reactants can be precisely controlled, ensuring the continuous and stable operation of the apparatus. The purity of nitrous oxide in the resulting gas reaches 99.0%.

[0052] Example 5 This embodiment provides a method for preparing nitrous oxide, which is carried out using the preparation apparatus of Example 1, and includes the following steps: An ammonium nitrate solution with a temperature of 135°C and a water content of 18 wt% is preheated and buffered in a material communication tank before entering the shell side of three parallel tubular reactors. A decomposition reaction occurs under the combined action of the reactor's electric heater and cooling pipes at a temperature of 255°C. The gaseous products enter a gas-liquid separator for gas-liquid separation. Ammonium nitrate droplets carried by nitrous oxide gas are separated and fall back into the material communication tank for recycling. The nitrous oxide gas is further cooled by a cooler and then enters a purification unit for refining. The resulting condensate is treated as wastewater for harmless disposal.

[0053] In this embodiment, the above-described apparatus and method are used to prepare nitrous oxide. The temperature of the reactants can be precisely controlled, ensuring the continuous and stable operation of the apparatus. The purity of nitrous oxide in the resulting gas reaches 99.5%.

[0054] Example 6 This embodiment provides a method for preparing nitrous oxide. The method uses the preparation apparatus of Example 2 (fresh ammonium nitrate solution, sprayed in), and includes the following steps: An ammonium nitrate solution with a temperature of 125°C and a water content of 10 wt% is preheated and then fed into the shell side of three parallel tubular reactors. Specifically, the solution is sprayed into the shell side of the tubular reactors through feed pipes located inside the reactors. Under the synergistic action of the reactor's electric heater and cooling pipes, a decomposition reaction takes place at a temperature of 250°C. The gaseous products enter a gas-liquid separator for gas-liquid separation. The ammonium nitrate droplets carried by the nitrous oxide gas are separated and fall, and are then recovered and buffered in a material connecting tank before entering the shell side of the tubular reactors from the bottom. This process not only enables the recycling of the ammonium nitrate recovery liquid but also helps to maintain a consistent liquid level in the parallel tubular reactors, contributing to the stable operation of continuous nitrous oxide production. The nitrous oxide gas is further cooled by a cooler and then enters a purification unit for refining. The resulting condensate is treated as wastewater for harmless disposal.

[0055] In this embodiment, the above-described apparatus and method are used to prepare nitrous oxide. The temperature of the reactants can be precisely controlled, ensuring the continuous and stable operation of the apparatus. The purity of nitrous oxide in the resulting gas reaches 99.8%.

[0056] Example 7 This embodiment provides a method for preparing nitrous oxide. The method uses the preparation apparatus of Example 2 (fresh ammonium nitrate solution, sprayed in), and includes the following steps: An ammonium nitrate solution with a temperature of 120°C and a water content of 7wt% is preheated and then fed into the shell side of three parallel tubular reactors. Specifically, the solution is sprayed into the shell side of the tubular reactors through feed pipes located inside the reactors. Under the synergistic action of the reactor's electric heater and cooling pipes, a decomposition reaction takes place at a temperature of 245°C. The gaseous products enter a gas-liquid separator for gas-liquid separation. The ammonium nitrate droplets carried by the nitrous oxide gas are separated and fall, and are then recovered and buffered in a material connecting tank before entering the shell side of the tubular reactors from the bottom. This not only enables the recycling of the ammonium nitrate recovery liquid but also helps to maintain a consistent liquid level in the parallel tubular reactors, which is conducive to the stable operation of continuous nitrous oxide production. The nitrous oxide gas is further cooled by a cooler and then enters a purification unit for refining. The resulting condensate is treated as wastewater for harmless disposal.

[0057] In this embodiment, the above-described apparatus and method are used to prepare nitrous oxide. The temperature of the reactants can be precisely controlled, ensuring the continuous and stable operation of the apparatus. The purity of nitrous oxide in the resulting gas reaches 99.2%.

[0058] Example 8 This embodiment provides a method for preparing nitrous oxide. The method uses the preparation apparatus of Example 2 (fresh ammonium nitrate solution, sprayed in), and includes the following steps: An ammonium nitrate solution with a temperature of 135°C and a water content of 18 wt% is preheated and then fed into the shell side of three parallel tubular reactors. Specifically, the solution is sprayed into the shell side of the tubular reactors through feed pipes located inside the reactors. Under the synergistic action of the reactor's electric heater and cooling pipes, a decomposition reaction takes place at a temperature of 255°C. The gaseous products enter a gas-liquid separator for gas-liquid separation. The ammonium nitrate droplets carried by the nitrous oxide gas are separated and fall, and are then recovered and buffered in a material connecting tank before entering the shell side of the tubular reactors from the bottom. This not only enables the recycling of the ammonium nitrate recovery liquid but also helps to maintain a consistent liquid level in the parallel tubular reactors, which is conducive to the stable operation of continuous nitrous oxide production. The nitrous oxide gas is further cooled by a cooler and then enters a purification unit for refining. The resulting condensate is treated as wastewater for harmless disposal.

[0059] In this embodiment, the above-described apparatus and method are used to prepare nitrous oxide. The temperature of the reactants can be precisely controlled, ensuring the continuous and stable operation of the apparatus. The purity of nitrous oxide in the resulting gas reaches 99.6%.

[0060] Comparative Example 1 This comparative example provides a nitrous oxide preparation apparatus. Compared with the preparation apparatus described in Example 1, the tubular reactor module (three tubular reactors in parallel) is replaced with a single reaction vessel. The reaction vessel is also equipped with a reactor electric heater and a spiral cooling tube for cooling. However, the material content in the reaction vessel is large, and the spiral cooling tube cannot be densely distributed like in the tubular reactor. Therefore, the relative contact area with the material is small, and the material inside the reaction vessel cannot effectively achieve temperature uniformity.

[0061] The comparative method for preparing nitrous oxide uses the aforementioned preparation apparatus, with continuous production specifications comparable to Example 3. Specifically, it includes: preheating an ammonium nitrate solution at 125°C with a water content of 10wt%, buffering it in a material communication tank, and then directly entering a single reaction vessel. The temperature is controlled by the reactor electric heater and spiral cooling pipe to carry out the decomposition reaction. The target temperature for the decomposition reaction is controlled at 250°C. The gaseous products enter a gas-liquid separator for gas-liquid separation. The ammonium nitrate droplets carried by the nitrous oxide gas are separated and fall back into the reaction vessel. The nitrous oxide gas is further cooled by a cooler and then enters a purification unit for refining. The resulting condensate is treated as wastewater for harmless treatment.

[0062] However, although the purity of nitrous oxide gas also reached 99.4%, the comparative example used a reactor for continuous preparation of nitrous oxide, which had a large volume but a small specific surface area, making it prone to local overheating and runaway reactions. In addition, the large liquid holdup posed a significant safety risk.

[0063] In summary, this invention provides a nitrous oxide preparation apparatus and method containing a tubular reactor. The preparation apparatus creatively employs a tubular reactor to perform the thermal decomposition reaction of ammonium nitrate solution. Utilizing the advantage of the large specific surface area of ​​the tubular reactor, the heat released by the reaction can be effectively removed, resulting in precise temperature control, low liquid holdup, and low risk of runaway. This facilitates the continuous and stable production of nitrous oxide gas products with a purity ≥99.0%. Furthermore, the tubular reactor module includes at least two parallel tubular reactors, allowing for convenient expansion of production capacity under safe conditions. It also features a high degree of automation and is safe and reliable.

[0064] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0065] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0066] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0067] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A nitrous oxide preparation apparatus containing a tubular reactor, characterized in that, The preparation device includes: a material communication tank (8), a tubular reactor module, and a gas-liquid separator (3) connected in series along the flow direction of the ammonium nitrate solution; the gas outlet of the gas-liquid separator (3) is used to collect nitrous oxide; the liquid outlet of the gas-liquid separator (3) is connected to the first inlet of the material communication tank (8) for collecting ammonium nitrate recovery liquid; The tubular reactor module includes at least two parallel tubular reactors (10); each tubular reactor (10) is independently equipped with a reactor heater (11), and the tubular reactor (10) includes a cooling tube (10-6) for cooling and a shell side for the thermal decomposition reaction of ammonium nitrate; the bottom inlet of the shell side is connected to the outlet of the material communication tank (8); the fresh ammonium nitrate solution is connected to the second inlet of the material communication tank (8) or the spray inlet of the tubular reactor (10).

2. The preparation apparatus according to claim 1, characterized in that, The tubular reactor (10) also includes a feed pipe (10-7) along the axial direction of the tubular reactor. The feed pipe (10-7) is located at the spray inlet of the tubular reactor (10) and extends into the interior of the tubular reactor (10). Spray holes are uniformly opened on the feed pipe (10-7) to achieve uniform distribution of fresh ammonium nitrate solution along the axial direction of the tubular reactor.

3. The preparation apparatus according to claim 1 or 2, characterized in that, Each of the tubular reactors (10) is independently equipped with a reactor thermometer (9) to monitor the reaction system temperature of the tubular reactor (10); a cooling water regulating valve (12) is installed on the cooling pipe (10-6), and the reactor thermometer (9) is electrically connected to the cooling water regulating valve (12) and the reactor heater (11).

4. The preparation apparatus according to any one of claims 1-3, characterized in that, The material communication tank (8) is equipped with a material communication tank level gauge (7), and a feed regulating valve (4) is installed on the fresh ammonium nitrate solution flow pipeline. The material communication tank level gauge (7) is electrically connected to the feed regulating valve (4).

5. The preparation apparatus according to any one of claims 1-4, characterized in that, A gas-liquid separator pressure gauge (2) is installed on the top of the gas-liquid separator (3) to monitor the system pressure.

6. The preparation apparatus according to any one of claims 1-5, characterized in that, The gas-liquid separator (3) is also provided with an emergency outlet and connected to a safety water seal tank (1) for depressurization in emergency situations.

7. The preparation apparatus according to any one of claims 1-6, characterized in that, The preparation apparatus also includes a preheater (5) for heat exchange between the fresh ammonium nitrate solution and nitrous oxide gas from the gas-liquid separator (3).

8. The preparation apparatus according to claim 7, characterized in that, The preparation apparatus further includes a cooler (6), the inlet of which is connected to the gas outlet of the preheater (5) for further cooling of the nitrous oxide gas from the preheater (5).

9. A method for preparing nitrous oxide using the apparatus described in any one of claims 1-8, characterized in that, The method for preparing nitrous oxide includes the following steps: Ammonium nitrate solution enters the shell side of at least two parallel tubular reactors (10), and undergoes a decomposition reaction under the synergistic action of reactor heater (11) and cooling pipe (10-6) for cooling. The gaseous product enters the gas-liquid separator (3) for gas-liquid separation, and nitrous oxide gas and ammonium nitrate recovery liquid are obtained respectively. The ammonium nitrate recovery liquid enters the material communication tank (8) for circulation. Fresh ammonium nitrate solution is continuously injected through the second inlet of the material communication tank (8) or the spray inlet of the tubular reactor (10), thereby continuously preparing nitrous oxide.

10. The method for preparing nitrous oxide according to claim 9, characterized in that, The ammonium nitrate solution exchanges heat with nitrous oxide gas from the gas-liquid separator (3) through the preheater (5), and the initial temperature of the ammonium nitrate solution is 120~135℃. Preferably, the water content of the ammonium nitrate solution is 7-18 wt%; Preferably, the temperature of the decomposition reaction is 245~255℃.

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