An anti-corrosion method for urea hydrolysis ammonia production equipment and urea hydrolysis ammonia production equipment

Abstract

The present application discloses an anti-corrosion method for a urea hydrolysis ammonia production device and a urea hydrolysis ammonia production device, belonging to the technical field of flue gas denitrification in thermal power plants. The method includes: introducing hot dilution air into the tracing pipeline to heat the finished gas pipeline; when the temperature of the finished gas pipeline reaches a preset temperature, allowing the hot dilution air to enter the finished gas pipeline and mix with the finished gas; the finished gas is the finished gas that is produced in a urea ammonia hydrolysis device and then introduced into the finished gas pipeline; after mixing, allowing the hot dilution air and the finished gas to enter a selective catalytic reduction reactor through the finished gas pipeline, and distributing the oxygen in the hot dilution air throughout the finished gas pipeline, so that an oxide film covers the inner wall of the finished gas pipeline. Compared with the traditional tracing process, the present application can avoid the blockage of the tracing pipeline caused by steam tracing drainage, thereby improving the tracing effect; it can promote the formation of an oxide film on the surface of the stainless steel finished gas pipeline, thereby enhancing the anti-corrosion effect of the urea hydrolysis ammonia production device.

Description

Technical Field

[0001] The present application relates to the technical field of flue gas denitrification in thermal power plants, and particularly relates to an anti-corrosion method for urea hydrolysis ammonia production equipment and urea hydrolysis ammonia production equipment. Background Art

[0002] In a denitrification system based on the Selective Catalytic Reduction (SCR) technology, urea hydrolysis process is usually adopted to prepare the reducing agent ammonia. After the urea hydrolysis reaction generates a product mixed gas containing ammonia, it will be transported to the SCR reactor through the finished gas pipeline. If the pipeline temperature is too low during transportation, the product mixed gas will condense into methylammonium solution, and the methylammonium will damage the oxide film on the surface of the stainless steel metal pipeline, causing pipeline corrosion; further, when the methylammonium solution is supersaturated, crystals will precipitate, causing pipeline blockage. Therefore, it is necessary to strictly control the temperature of the transportation pipeline and clean the pipeline after shutdown to ensure the pipeline is clean. However, the existing heat tracing and purging processes of urea hydrolysis ammonia production equipment both use high-pressure steam, and high-pressure steam will generate condensate. In winter, the condensate pipeline often freezes and blocks, greatly reducing the steam heat tracing effect; during the process of purging the pipeline with steam, there will also be some condensate remaining in the pipeline, and the remaining condensate will instead promote the corrosion inside the pipeline. Therefore, how to enhance the anti-corrosion effect of urea hydrolysis ammonia production equipment is a technical problem that those skilled in the art need to solve currently. Summary of the Invention

[0003] The purpose of the present application is to provide an anti-corrosion method for urea hydrolysis ammonia production equipment and urea hydrolysis ammonia production equipment, so as to enhance the anti-corrosion effect of urea hydrolysis ammonia production equipment.

[0004] To achieve the above purpose, the present application provides an anti-corrosion method for urea hydrolysis ammonia production equipment, including:

[0005] Introduce hot dilution air into the heat tracing pipeline to heat the finished gas pipeline.

[0006] When the temperature of the finished gas pipeline reaches a preset temperature, make the hot dilution air enter the finished gas pipeline to mix with the finished gas; the finished gas is the finished gas generated in the urea ammonia hydrolysis device and then introduced into the finished gas pipeline.

[0007] After mixing, make the hot dilution air and the finished gas enter the Selective Catalytic Reduction reactor through the finished gas pipeline, and make the oxygen in the hot dilution air distributed everywhere in the finished gas pipeline, so that an oxide film is covered on the inner wall of the finished gas pipeline.

[0008] Optionally, after the hot dilution air and the finished gas enter the Selective Catalytic Reduction reactor through the finished gas pipeline, it further includes:

[0009] When the urea ammonia hydrolysis device stops running, close the valve between the finished gas pipeline and the urea ammonia hydrolysis device, so that the hot dilution air enters the finished gas pipeline to clean the finished gas pipeline. Then, the hot dilution air and the remaining finished gas enter the selective catalytic reduction reactor, and the oxygen in the hot dilution air is distributed everywhere in the finished gas pipeline, so that the inner wall of the finished gas pipeline is covered with an oxide film.

[0010] Optionally, after the hot dilution air and the finished gas enter the selective catalytic reduction reactor through the finished gas pipeline, it further includes:

[0011] When the urea ammonia hydrolysis device stops running, close the valve between the finished gas pipeline and the selective catalytic reduction reactor, so that the hot dilution air enters the urea ammonia hydrolysis device to clean the urea ammonia hydrolysis device. Then, the hot dilution air and the residual components in the urea ammonia hydrolysis device are discharged from the blowdown port of the urea ammonia hydrolysis device, and the oxygen in the hot dilution air is distributed everywhere in the urea ammonia hydrolysis device, so that the inner wall of the urea ammonia hydrolysis device is covered with an oxide film.

[0012] Optionally, the step of heating the finished gas pipeline by introducing hot dilution air into the heat tracing pipeline includes:

[0013] Introduce the hot dilution air into the heat tracing pipeline, and control the amount of hot dilution air entering the heat tracing pipeline through the first regulating valve and the second regulating valve to heat the finished gas pipeline. The first regulating valve is a valve arranged between the first output end and the input end of the heat tracing pipeline, and the second regulating valve is a valve arranged between the second output end and the input end of the heat tracing pipeline.

[0014] Optionally, the step of heating the finished gas pipeline by introducing hot dilution air into the heat tracing pipeline includes:

[0015] Introduce the hot dilution air into the heat tracing pipeline, and monitor the temperature of the hot dilution air in the heat tracing pipeline through a thermocouple to heat the finished gas pipeline.

[0016] Optionally, the step of making the hot dilution air enter the finished gas pipeline to mix with the finished gas includes:

[0017] Pressurize the heat tracing pipeline through a hot dilution air booster pump, so that the hot dilution air enters the finished gas pipeline to mix with the finished gas.

[0018] To achieve the above object, the present application further provides a urea hydrolysis ammonia production device, including: a urea hydrolysis ammonia production reactor, a finished gas pipeline, a hot dilution air pipeline, a dilution blower, a dilution air heat exchanger, and a selective catalytic reduction reactor; the hot dilution air pipeline includes an inlet pipeline and a tracing pipeline;

[0019] The output end of the urea hydrolysis ammonia production reactor is communicated with the input end of the finished gas pipeline, and is used for generating finished gas and then introducing the finished gas into the finished gas pipeline;

[0020] The dilution blower is communicated with the input end of the inlet pipeline, and is used for introducing dilution air into the hot dilution air pipeline;

[0021] One end of the dilution air heat exchanger is communicated with the output end of the inlet pipeline, and the other end of the dilution air heat exchanger is communicated with the input end of the tracing pipeline, and is used for heating the dilution air to form hot dilution air;

[0022] The tracing pipeline is used for heating the finished gas pipeline;

[0023] The first output end of the tracing pipeline is communicated with the input end of the finished gas pipeline, and the output end of the finished gas pipeline is communicated with the selective catalytic reduction reactor, and is used for when the temperature of the finished gas pipeline reaches a preset temperature, enabling the hot dilution air to enter the finished gas pipeline and mix with the finished gas; after mixing, enabling the hot dilution air and the finished gas to enter the selective catalytic reduction reactor through the finished gas pipeline, and enabling the oxygen in the hot dilution air to be distributed everywhere in the finished gas pipeline, so that an oxide film covers the inner wall of the finished gas pipeline.

[0024] Optionally, the tracing pipeline further includes a second output end; the second output end is communicated with an ammonia-air mixer; the ammonia-air mixer is communicated with the finished gas pipeline on one side close to the output end of the finished gas pipeline;

[0025] A first regulating valve is arranged between the first output end of the tracing pipeline and the input end of the tracing pipeline; a second regulating valve is arranged between the second output end of the tracing pipeline and the input end of the tracing pipeline; the first regulating valve and the second regulating valve are used for controlling the amount of the hot dilution air entering the tracing pipeline.

[0026] Optionally, the urea hydrolysis ammonia production device further includes: a thermocouple; the thermocouple is used for monitoring the temperature of the hot dilution air in the tracing pipeline.

[0027] Optionally, the urea hydrolysis ammonia production equipment further includes: a hot dilution air pressurizing pump; the hot dilution air pressurizing pump is communicated with the tracing pipeline and is used to pressurize the tracing pipeline so that the hot dilution air enters the finished gas pipeline and mixes with the finished gas.

[0028] Obviously, compared with the traditional tracing process, for an anti-corrosion method of urea hydrolysis ammonia production equipment provided by the present application, by introducing hot dilution air into the tracing pipeline and using the hot dilution air to trace the finished gas pipeline, it can avoid the blockage of the tracing pipeline caused by steam tracing and draining, thereby improving the tracing effect; after the tracing is completed, the hot dilution air is introduced into the finished gas pipeline. During the process of transporting the finished gas and the hot dilution air, the oxygen in the hot dilution air is evenly distributed throughout the finished gas pipeline, providing an oxidation atmosphere for the finished gas pipeline, protecting the oxide film on the surface of the stainless steel finished gas pipeline from being damaged, and promoting the formation of the oxide film on the surface of the stainless steel finished gas pipeline, thereby enhancing the anti-corrosion effect of the urea hydrolysis ammonia production equipment, extending the service life of the urea hydrolysis ammonia production equipment, and maintaining the stable and safe operation of the equipment. The present application also provides a urea hydrolysis ammonia production equipment with the above beneficial effects. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0030] Figure 1 It is a flowchart of an anti-corrosion method of a urea hydrolysis ammonia production equipment provided by an embodiment of the present application;

[0031] Figure 2 It is a flowchart of another anti-corrosion method of a urea hydrolysis ammonia production equipment provided by an embodiment of the present application;

[0032] Figure 3 It is a structural schematic diagram of a urea hydrolysis ammonia production equipment provided by an embodiment of the present application.

[0033] The descriptions of the reference numerals are as follows:

[0034] 1 - Urea ammonia hydrolysis device; 2 - Feed port valve; 3 - Drain port valve; 4 - Valve between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1; 5 - First switch valve; 6 - Thermal dilution air pressurizing pump; 7 - Thermocouple; 8 - First regulating valve; 9 - Second switch valve; 10 - Tracer pipeline; 11 - Finished gas pipeline; 12 - Valve between the finished gas pipeline 11 and the selective catalytic reduction reactor 18; 13 - Ammonia-air mixer 13; 14 - Second regulating valve; 15 - Thermal dilution air pipeline; 16 - Dilution blower; 17 - Dilution air heat exchanger; 18 - Selective catalytic reduction reactor. Detailed implementation mode

[0035] To make the objectives, technical solutions and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0036] Due to its high denitrification efficiency, the SCR technology has been widely promoted in the domestic and international power industries. The principle of the SCR technology is to use ammonia as a reducing agent under the action of a catalyst to react with Nox (nitrogen oxides) in the flue gas to generate nitrogen and water, thereby achieving the purpose of denitrification. In the SCR technology, the reducing agent ammonia can be prepared by various processes such as liquid ammonia gasification, urea hydrolysis and pyrolysis. Among them, urea hydrolysis to ammonia has received extensive attention and is increasingly used due to its high safety and low operating cost.

[0037] The product mixture gas generated by the urea hydrolysis reaction contains three substances: NH3 (ammonia), CO2 (carbon dioxide), and H2O (water). During the process of transporting the product mixture gas through the finished gas pipeline to the SCR reactor, when the pipeline temperature is lower than the dew point temperature of the mixture gas, the product mixture gas will condense into methylammonium solution. When the pipeline temperature further drops and the methylammonium solution becomes supersaturated, methylammonium will precipitate and crystallize. Since there is no oxidizing atmosphere in the pipeline, the methylammonium solution destroys the oxide film on the surface of the stainless steel metal pipeline and has strong corrosiveness to the metal. The methylammonium crystal will cause pipeline blockage. Therefore, it is necessary to strictly control the temperature of the transport pipeline and clean the finished gas pipeline after shutdown to ensure that the pipeline is clean.

[0038] Currently, the urea ammonia hydrolysis equipment takes steam tracing measures for the finished gas pipeline, and steam is also used for purging after the unit shuts down. However, when using steam pipeline tracing, a certain amount of condensate will be generated in the steam pipeline. In winter, the condensate is prone to freezing and blocking the steam pipeline, resulting in a significant reduction in the steam tracing effect and an increase in steam consumption. When using the steam in the steam pipeline to flush the finished gas pipeline, a certain amount of condensate will be generated in the finished gas pipeline, which will instead easily promote the formation of methylamine and cause corrosion of the finished gas pipeline. Therefore, the present application provides an anti-corrosion method for urea hydrolysis ammonia production equipment and urea hydrolysis ammonia production equipment. By using the diluted air after heating to trace the finished gas pipeline and introducing the hot diluted air into the finished gas pipeline after tracing, it is not only possible to avoid the adverse effects caused by the generation of condensate by steam, improve the tracing effect, and reduce steam consumption, but also to use the oxygen in the hot diluted air to keep the inside of the stainless steel finished gas pipeline in an oxidized state, forming a dense oxide film, greatly reducing the corrosion rate of the stainless steel finished gas pipeline, extending the service life of the urea ammonia hydrolysis equipment, and maintaining the stable and safe operation of the equipment.

[0039] Please refer to Figure 1 , Figure 1 FIG. is a flowchart of an anti-corrosion method for urea hydrolysis ammonia production equipment provided by an embodiment of the present application. The method may include:

[0040] S101: Introduce hot diluted air into the tracing pipeline 10 to heat the finished gas pipeline 11.

[0041] This embodiment does not limit the specific method of heating the finished gas pipeline 11. The specific method of heating the finished gas pipeline 11 can be determined according to the specific installation method of the tracing pipeline 10. For example, when the tracing pipeline 10 is arranged in parallel with the finished gas pipeline 11, hot diluted air can be introduced into the tracing pipeline 10, and the finished gas pipeline 11 can be heated in the form of tracing by a companion pipe. When the tracing pipeline 10 is wrapped around the periphery of the finished gas pipeline 11, hot diluted air can be introduced into the tracing pipeline 10, and the finished gas pipeline 11 can be heated in the form of tracing by a jacketed pipe.

[0042] Further, in order to prevent the excessive thermal dilution air volume in the tracing pipe 10 and facilitate the regulation of the temperature of the thermal dilution air in the tracing pipe 10, in this embodiment, thermal dilution air can be introduced into the tracing pipe 10, and the thermal dilution air volume entering the tracing pipe 10 can be controlled by the first regulating valve 8 and the second regulating valve 14 to heat the finished gas pipeline 11; the first regulating valve 8 is a valve arranged between the first output end and the input end of the tracing pipe 10, and the second regulating valve 14 is a valve arranged between the second output end and the input end of the tracing pipe 10. This embodiment does not limit the specific types of the first regulating valve 8 and the second regulating valve 14, as long as it can ensure the control of the thermal dilution air volume entering the tracing pipe 10, for example, it can be an electric first regulating valve 8 and an electric second regulating valve 14, or a manual regulating valve can also be used.

[0043] Further, in order to accurately regulate the temperature of the thermal dilution air in the tracing pipe 10, in this embodiment, thermal dilution air can be introduced into the tracing pipe 10, and the temperature of the thermal dilution air in the tracing pipe 10 can be monitored by the thermocouple 7 to heat the finished gas pipeline 11. In addition to the thermocouple 7, other temperature monitoring devices can also be used in this embodiment. It should be noted that according to the temperature of the thermal dilution air monitored by the thermocouple 7, through the coordinated regulation of the first regulating valve 8 and the second regulating valve 14, the thermal dilution air volume entering the tracing pipe 10 can be accurately controlled to ensure that the temperature of the thermal dilution air in the tracing pipe 10 is not lower than 150 °C. Generally, the proportion of the thermal dilution air introduced into the tracing pipe 10 in the total dilution air is 5% - 12%.

[0044] S102: When the temperature of the finished gas pipeline 11 reaches the preset temperature, make the thermal dilution air enter the finished gas pipeline 11 to mix with the finished gas; the finished gas is the finished gas generated in the urea-to-ammonia hydrolyzer 1 and then introduced into the finished gas pipeline 11.

[0045] This embodiment does not limit the specific way of making the thermal dilution air enter the finished gas pipeline 11, as long as it can ensure that the thermal dilution air can enter the finished gas pipeline 11. For example, the tracing pipe 10 can be pressurized by the thermal dilution air pressure pump 6 to make the thermal dilution air enter the finished gas pipeline 11 to mix with the finished gas. In addition to the thermal dilution air pressure pump 6, other pressurizing devices can also be used in this embodiment.

[0046] S103: After mixing, make the thermal dilution air and the finished gas enter the selective catalytic reduction reactor 18 through the finished gas pipeline 11, and make the oxygen in the thermal dilution air be distributed everywhere in the finished gas pipeline 11 so that the inner wall of the finished gas pipeline 11 is covered with an oxide film.

[0047] It should be noted that after the heat dilution air in the heat tracing pipeline 10 completes the heat tracing of the finished gas pipeline 11, it enters the inlet end of the finished gas pipeline 11. The heat dilution air is mixed with the finished gas and then enters the ammonia-air mixer 13 together, and finally enters the selective catalytic reduction reactor 18 (i.e., the SCR reactor 18). During this process, the oxygen in the heat dilution air is evenly distributed throughout the finished gas pipeline 11, providing an oxidation atmosphere for the finished gas pipeline 11 to protect the oxide film on the surface of the stainless steel finished gas pipeline 11 from being damaged and promoting the formation of the oxide film on the surface of the stainless steel finished gas pipeline 11.

[0048] Furthermore, in order to avoid corrosion of the finished gas pipeline 11 during the cleaning process of the finished gas pipeline 11, in this embodiment, after the heat dilution air and the finished gas enter the selective catalytic reduction reactor 18 through the finished gas pipeline 11, when the urea-to-ammonia hydrolyzer 1 stops operating, the valve 4 between the finished gas pipeline 11 and the urea-to-ammonia hydrolyzer 1 can be closed to allow the heat dilution air to enter the finished gas pipeline 11, clean the finished gas pipeline 11, and enable the heat dilution air and the remaining finished gas to enter the selective catalytic reduction reactor 18, and the oxygen in the heat dilution air is distributed throughout the finished gas pipeline 11 so that the inner wall of the finished gas pipeline 11 is covered with an oxide film. Further, in order to control the cleaning rate, in this embodiment, the heat dilution air can also be made to enter the finished gas pipeline 11, and the amount of heat dilution air entering the heat tracing pipeline 10 can be controlled by the first regulating valve 8 and the second regulating valve 14 to clean the finished gas pipeline 11. It should be noted that the larger the opening of the first regulating valve 8, the smaller the opening of the second regulating valve 14, and the larger the dilution air volume of the heat tracing pipeline 10 accordingly. Therefore, by increasing the opening of the first regulating valve 8 and decreasing the opening of the second regulating valve 14, the dilution air volume of the heat tracing pipeline 10 can be increased. In addition, the specific cleaning time is not limited in this embodiment, as long as there is no residual finished gas in the finished gas pipeline 11. For example, the cleaning time can be 12 hours or more.

[0049] Further, in order to avoid corrosion of the urea ammonia hydrolyzer 1 during the cleaning process, in this embodiment, after the hot dilution air and the finished gas enter the selective catalytic reduction reactor 18 through the finished gas pipeline 11, when the urea ammonia hydrolyzer 1 stops running, the valve 12 between the finished gas pipeline 11 and the selective catalytic reduction reactor 18 can be closed to allow the hot dilution air to enter the urea ammonia hydrolyzer 1 to clean the urea ammonia hydrolyzer 1, so that the hot dilution air and the residual components in the urea ammonia hydrolyzer 1 are discharged from the sewage outlet of the urea ammonia hydrolyzer 1, and the oxygen in the hot dilution air is distributed in various parts of the urea ammonia hydrolyzer 1, so that the inner wall of the urea ammonia hydrolyzer 1 is covered with an oxide film. Further, in order to control the cleaning rate, in this embodiment, the hot dilution air can also enter the urea ammonia hydrolyzer 1, and the hot dilution air volume entering the heating pipeline 10 is controlled by the first regulating valve 8 and the second regulating valve 14 to clean the urea ammonia hydrolyzer 1. It should be noted that the larger the opening of the first regulating valve 8, the smaller the opening of the second regulating valve 14, and the larger the dilution air volume of the corresponding heating pipeline 10. Therefore, by increasing the opening of the first regulating valve 8 and reducing the opening of the second regulating valve 14, the dilution air volume of the heating pipeline 10 can be increased. In addition, the specific time of the purge is not limited in this embodiment, as long as there is no residual component in the urea to ammonia hydrolyzer 1, for example, the purge time can be 12 hours or more.

[0050] It should be noted that, since the urea hydrolysis ammonia production equipment is in an oxygen-free environment whether in the operation stage or in the shutdown maintenance stage, the stainless steel in the urea hydrolysis ammonia production equipment 1 and the finished gas pipeline 11 (including the hydrolysis equipment shell, heat exchanger, valve, pipeline and other components) is in an activated corrosion state. Over time, the consequences of corrosion will cause the shell and pipeline of the urea hydrolysis ammonia production equipment 1 to become thinner, the pressure bearing capacity to be weakened, the valve to be not closed tightly, and the regulating valve line position to be inaccurate. If enough oxygen can be added to the urea hydrolysis ammonia production equipment to make the stainless steel in an oxidized state and form a dense oxide film, the corrosion rate can be greatly reduced, and the stable and safe operation of the urea hydrolysis ammonia production equipment can be achieved.

[0051] Therefore, in this embodiment, the heated dilution air is utilized. On the one hand, it can heat the finished gas pipeline 11. On the other hand, after tracing heat, the hot dilution air is introduced into the finished gas pipeline 11 from the inlet end of the finished gas pipeline 11, so that the oxygen in the hot dilution air can cover the surface of the stainless steel material in contact with the finished gas. Since oxygen atoms are strong oxidants (which play a passivating role), an anti-corrosion passivation film is formed on the stainless steel surface, which can achieve the purpose of extending the service life of the finished gas pipeline 11. In addition, after the urea-to-ammonia hydrolyzer 1 stops operating, the hot dilution air can also be used to purge the finished gas pipeline 11 and the urea-to-ammonia hydrolyzer 1. It can not only purge the corrosive substances such as residual urea and methylamine in the urea-to-ammonia hydrolyzer 1 and the finished gas pipeline 11, but also provide an oxidation atmosphere for the urea hydrolysis to ammonia equipment, promote the formation of the oxide film of stainless steel, and ensure that the equipment plays an anti-corrosion role during the shutdown stage.

[0052] Based on the above embodiment, compared with the traditional tracing heat process, in the tracing heat pipeline 10, hot dilution air is introduced, and the hot dilution air is used to trace heat the finished gas pipeline 11, which can avoid the blockage of the tracing heat pipeline 10 caused by steam tracing heat drainage, thereby improving the tracing heat effect; after completing the tracing heat, the hot dilution air is introduced into the finished gas pipeline 11. During the process of transporting the finished gas and the hot dilution air, the oxygen in the hot dilution air is evenly distributed throughout the finished gas pipeline 11, providing an oxidation atmosphere for the finished gas pipeline 11, protecting the oxide film on the surface of the stainless steel finished gas pipeline 11 from being damaged, promoting the formation of the oxide film on the surface of the stainless steel finished gas pipeline 11, thereby enhancing the anti-corrosion effect of the urea hydrolysis to ammonia equipment, extending the service life of the urea-to-ammonia hydrolysis equipment and maintaining the stable and safe operation of the equipment.

[0053] Please refer to Figure 2 , Figure 2 which is a flowchart of another anti-corrosion method for the urea hydrolysis to ammonia equipment provided by the embodiment of the present application. The method may include:

[0054] S201: Introduce hot dilution air into the tracing heat pipeline 10, monitor the temperature of the hot dilution air in the tracing heat pipeline 10 through the thermocouple 7, and control the amount of hot dilution air entering the tracing heat pipeline 10 through the first regulating valve 8 and the second regulating valve 14 to heat the finished gas pipeline 11; the first regulating valve 8 is a valve arranged between the first output end and the input end of the tracing heat pipeline 10, and the second regulating valve 14 is a valve arranged between the second output end and the input end of the tracing heat pipeline 10.

[0055] S202: When the temperature of the finished gas pipeline 11 reaches the preset temperature, pressurize the tracing heat pipeline 10 through the hot dilution air pressure pump 6 to make the hot dilution air enter the finished gas pipeline 11 and mix with the finished gas; the finished gas is the finished gas generated in the urea-to-ammonia hydrolyzer 1 and then introduced into the finished gas pipeline 11.

[0056] S203: After mixing, allow the hot dilution air and the finished gas to enter the selective catalytic reduction reactor 18 through the finished gas pipeline 11, and distribute the oxygen in the hot dilution air throughout the finished gas pipeline 11 so that an oxide film covers the inner wall of the finished gas pipeline 11.

[0057] S204: When the urea-to-ammonia hydrolyzer 1 stops operating, close the valve 4 between the finished gas pipeline 11 and the urea-to-ammonia hydrolyzer 1, allow the hot dilution air to enter the finished gas pipeline 11, and by increasing the opening degree of the first regulating valve 8, decreasing the opening degree of the second regulating valve 14, and increasing the dilution air volume of the tracing pipeline 10, clean the finished gas pipeline 11, so that the hot dilution air and the residual finished gas enter the selective catalytic reduction reactor 18, and distribute the oxygen in the hot dilution air throughout the finished gas pipeline 11 so that an oxide film covers the inner wall of the finished gas pipeline 11.

[0058] S205: When the urea-to-ammonia hydrolyzer 1 stops operating, close the valve 12 between the finished gas pipeline 11 and the selective catalytic reduction reactor 18, allow the hot dilution air to enter the urea-to-ammonia hydrolyzer 1, and by increasing the opening degree of the first regulating valve 8, decreasing the opening degree of the second regulating valve 14, and increasing the dilution air volume of the tracing pipeline 10, clean the urea-to-ammonia hydrolyzer 1, so that the hot dilution air and the residual components in the urea-to-ammonia hydrolyzer 1 are discharged from the blowdown port of the urea-to-ammonia hydrolyzer 1, and distribute the oxygen in the hot dilution air throughout the urea-to-ammonia hydrolyzer 1 so that an oxide film covers the inner wall of the urea-to-ammonia hydrolyzer 1.

[0059] Based on the above embodiments, the present application introduces hot dilution air into the tracing pipeline 10, uses the hot dilution air to heat the finished gas pipeline 11, and cooperatively controls the hot dilution air volume in the tracing pipeline 10 through the first regulating valve 8 and the second regulating valve 14; after the heating is completed, the hot dilution air in the tracing pipeline 10 is pressurized by the hot dilution air booster pump 6 and enters the inlet end of the finished gas pipeline 11, and the hot dilution air enters the selective catalytic reduction reactor 18 together with the finished gas; when the urea-to-ammonia hydrolyzer 1 stops operating, the hot dilution air in the tracing pipeline 10 can be used to purge the finished gas pipeline 11 and the urea-to-ammonia hydrolyzer 1. Compared with the traditional heating process and purging process, using hot dilution air for heating can not only achieve the purpose of heating the product gas pipeline, but also does not need to consider the adverse effects caused by steam heating condensation. Moreover, the oxygen in the hot dilution air can be evenly distributed at each position of the equipment during the operation and shutdown stages of the equipment, providing an oxidation environment for the stainless steel material of the urea hydrolysis to ammonia equipment, promoting the passivation of stainless steel, and generating an anti-corrosion passivation film. Finally, it achieves the purpose of extending the service life of the urea hydrolysis to ammonia equipment and ensuring the stable and safe operation of the urea hydrolysis to ammonia equipment.

[0060] Please refer to Figure 3 ,Figure 3 Figure 3 is a schematic structural diagram of an ammonia production device by urea hydrolysis provided by an embodiment of the present application. The ammonia production device by urea hydrolysis may include: a urea hydrolysis reactor 1, a finished gas pipeline 11, a hot dilution air pipeline 15, a dilution fan 16, a dilution air heat exchanger 17, and a selective catalytic reduction reactor 18; the hot dilution air pipeline 15 includes an inlet pipeline and a tracing pipeline 10;

[0061] The output end of the urea hydrolysis reactor 1 is communicated with the input end of the finished gas pipeline 11, and is used for generating finished gas and then introducing the finished gas into the finished gas pipeline 11;

[0062] The dilution fan 16 is communicated with the input end of the inlet pipeline, and is used for introducing dilution air into the hot dilution air pipeline 15;

[0063] One end of the dilution air heat exchanger 17 is communicated with the output end of the inlet pipeline, and the other end of the dilution air heat exchanger 17 is communicated with the input end of the tracing pipeline 10, and is used for heating the dilution air to form hot dilution air;

[0064] The tracing pipeline 10 is used for heating the finished gas pipeline 11;

[0065] The first output end of the tracing pipeline 10 is communicated with the input end of the finished gas pipeline 11, and the output end of the finished gas pipeline 11 is communicated with the selective catalytic reduction reactor 18, and is used for when the temperature of the finished gas pipeline 11 reaches a preset temperature, enabling the hot dilution air to enter the finished gas pipeline 11 to be mixed with the finished gas; after mixing, enabling the hot dilution air and the finished gas to enter the selective catalytic reduction reactor 18 through the finished gas pipeline 11, and enabling the oxygen in the hot dilution air to be distributed everywhere in the finished gas pipeline 11, so that an oxide film is covered on the inner wall of the finished gas pipeline 11.

[0066] This embodiment does not limit the specific installation manner of the tracing pipeline 10. For example, the tracing pipeline 10 may be arranged in parallel with the finished gas pipeline 11; or the tracing pipeline 10 may be wrapped around the periphery of the finished gas pipeline 11.

[0067] Further, in order to facilitate the regulation of the amount of hot dilution air in the tracing pipeline 10, the tracing pipeline 10 in this embodiment further includes a second output end; the second output end is communicated with an ammonia-air mixer 13; the ammonia-air mixer 13 is communicated with the finished gas pipeline 11 on one side close to the output end of the finished gas pipeline 11; a first regulating valve 8 is arranged between the first output end and the input end of the tracing pipeline 10; a second regulating valve 14 is arranged between the second output end and the input end of the tracing pipeline 10; the first regulating valve 8 and the second regulating valve 14 are used for controlling the amount of hot dilution air entering the tracing pipeline 10. It should be noted that the larger the opening degree of the first regulating valve 8, the smaller the opening degree of the second regulating valve 14, and the corresponding larger the dilution air volume of the tracing pipeline 10.

[0068] Further, in order to accurately control the temperature of the heat dilution air in the heat tracing pipe 10, the urea hydrolysis ammonia production device of this embodiment may further include: a thermocouple 7; the thermocouple 7 is used to monitor the temperature of the heat dilution air in the heat tracing pipe 10. In addition to the thermocouple 7, other temperature monitoring devices may also be used in this embodiment. The specific position of the thermocouple 7 is not limited in this embodiment, as long as it can ensure the temperature of the heat dilution air in the heat tracing pipe 10 can be monitored. For example, the thermocouple 7 can be arranged at a position on the heat tracing pipe 10 close to the first output end of the heat tracing pipe 10. It should be noted that according to the temperature of the heat dilution air monitored by the thermocouple 7, through the coordinated adjustment of the first regulating valve 8 and the second regulating valve 14, the amount of heat dilution air entering the heat tracing pipe 10 can be accurately controlled to ensure that the temperature of the heat dilution air in the heat tracing pipe 10 is not lower than 150°C. Generally, the proportion of the heat dilution air introduced into the heat tracing pipe 10 in the total dilution air is 5% - 12%.

[0069] Further, in order to make the heat dilution air easier to enter the finished gas pipe, the urea hydrolysis ammonia production device of this embodiment may further include: a heat dilution air booster pump 6; the heat dilution air booster pump 6 is connected to the dilution air heat tracing pipe 10, and is used to pressurize the dilution air heat tracing pipe 10 to make the heat dilution air enter the finished gas pipe 11 and mix with the finished gas. In addition to the heat dilution air booster pump 6, other pressurizing devices may also be used in this embodiment. The specific position of the heat dilution air booster pump 6 is not limited in this embodiment, as long as it can ensure that the heat dilution air can enter the finished gas pipe 11. For example, the heat dilution air booster pump 6 can be arranged at a position on the heat tracing pipe 10 close to the first output end of the heat tracing pipe 10.

[0070] Further, in order to be able to purge the finished gas pipeline 11 and the urea ammonia hydrolysis device 1 separately, the urea hydrolysis ammonia production device of this embodiment may further include: a valve 4 provided between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1; a valve 12 provided between the finished gas pipeline 11 and the selective catalytic reduction reactor 18. This embodiment does not limit the specific types of the valve 4 between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1 and the valve 12 between the finished gas pipeline 11 and the selective catalytic reduction reactor 18, as long as it can ensure the conduction or closing of the pipeline. For example, the valve 4 between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1 can be an electric valve or a manual valve; the valve 12 between the finished gas pipeline 11 and the selective catalytic reduction reactor 18 can be an electric valve or a manual valve. It should be noted that when purging the finished gas pipeline 11, the valve 4 between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1 is in the closed state, and the valve 12 between the finished gas pipeline 11 and the selective catalytic reduction reactor 18 is in the open state; when purging the urea ammonia hydrolysis device 1, the valve 4 between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1 is in the open state, and the valve 12 between the finished gas pipeline 11 and the selective catalytic reduction reactor 18 is in the closed state. It should also be noted that when purging the finished gas pipeline 11 and the urea ammonia hydrolysis device 1, the dilution fan 16 still operates continuously, and the dilution air heat exchanger 17 still heats the dilution air.

[0071] It should be noted that the urea ammonia hydrolysis device 1 is provided with a feed inlet and a blowdown port. A feed inlet valve 2 is also provided at the feed inlet, and the feed inlet valve 2 is used to control the opening or closing of the feed inlet; a blowdown port valve 3 is also provided at the blowdown port, and the blowdown port valve 3 is used to control the opening or closing of the blowdown port. A first switch valve 5 and a second switch valve 9 may also be provided on the tracing pipeline 10 to control the conduction or closing of the tracing pipeline 10. This embodiment does not limit the specific types of the feed inlet valve 2, the blowdown port valve 3, the first switch valve 5, and the second switch valve 9. For example, they can be an electric feed inlet valve 2, an electric blowdown port valve 3, an electric first switch valve 5, and an electric second switch valve 9, or manual valves can also be used.

[0072] Based on the above embodiments, by using the urea hydrolysis ammonia production equipment provided in the present application, hot dilution air is introduced into the tracing pipeline 10, and the finished gas pipeline 11 is traced with the hot dilution air, which can avoid the blockage of the tracing pipeline 10 caused by steam tracing and drainage, thereby improving the tracing effect; after the tracing is completed, the hot dilution air is introduced into the finished gas pipeline 11. During the process of transporting the finished gas and the hot dilution air, the oxygen in the hot dilution air is evenly distributed throughout the finished gas pipeline 11, providing an oxidation atmosphere for the finished gas pipeline 11, protecting the oxide film on the surface of the stainless steel finished gas pipeline 11 from being damaged, promoting the formation of the oxide film on the surface of the stainless steel finished gas pipeline 11, thereby enhancing the anti-corrosion effect of the urea hydrolysis ammonia production equipment, extending the service life of the urea hydrolysis ammonia production equipment and maintaining the stable and safe operation of the equipment.

[0073] To make the present application easier to understand, the working process of the above urea hydrolysis ammonia production equipment will be described in detail below with specific examples.

[0074] On the hot dilution air pipeline 15, the tracing pipeline 10 is connected after the dilution air heat exchanger 17, the electric first switch valve 5 is opened, and the electric second switch valve 9 is opened. The proportion of the hot dilution air introduced into the tracing pipeline 10 in the total dilution air is 5% - 12%. According to the temperature of the hot dilution air monitored by the thermocouple 7, the electric first regulating valve 8 and the electric second regulating valve 14 are coordinated to regulate to control the amount of hot dilution air entering the tracing pipeline 10, ensuring that the temperature of the hot dilution air monitored by the thermocouple 7 is not lower than 150°C. After the hot dilution air in the tracing pipeline 10 finishes tracing the finished gas pipeline 11, it is pressurized by the hot dilution air booster pump 6 and enters the inlet end of the finished gas pipeline 11. The hot dilution air is mixed with the finished gas and enters the ammonia-air mixer 13 together, and finally enters the SCR reactor 18.

[0075] When the urea hydrolysis ammonia production equipment stops running, the dilution blower 16 continues to operate, and the dilution air heat exchanger 17 still heats the dilution air. First, close the electric valve 4 between the finished gas pipeline 11 and the urea hydrolysis ammonia production device 1. Increase the opening of the electric first regulating valve 8 and decrease the opening of the electric second regulating valve 14 to increase the amount of hot dilution air in the tracing pipeline 10 and clean the finished gas pipeline 11. The blown hot dilution air and the remaining finished gas are blown into the SCR reactor 18. If the urea hydrolysis ammonia production device 1 needs to be shut down cold, open the electric blowdown valve 3 to drain the urea solution in the urea hydrolysis ammonia production device 1. Then close the electric valve 12 between the finished gas pipeline 11 and the SCR reactor 18, and open the electric valve 4 between the finished gas pipeline 11 and the urea hydrolysis ammonia production device 1 to clean the urea hydrolysis ammonia production device 1. The blown hot dilution air and the remaining components are discharged together from the electric blowdown valve 3. The purging time needs to reach more than 12 hours to ensure that there are no other substances remaining in the urea hydrolysis ammonia production device 1 and the finished gas pipeline 11. During the purging process using hot dilution air, the oxygen in the hot dilution air further contacts the stainless steel to form an oxidation passivation film, achieving an anti-corrosion effect.

[0076] Experimental Example 1

[0077] The denitration device of a 300MW thermal power unit adopts the SCR process, and the reducing agent ammonia is prepared by the urea hydrolysis process. The ammonia production capacity of a single hydrolyzer is 300kg / h. A urea mixed solution with a concentration of about 50% is transported to the urea hydrolyzer, and a mixed gas with an ammonia concentration of about 37.5% is generated through hydrolysis reaction under the conditions of a pressure of about 0.4MPa - 0.6MPa and a temperature of about 130°C - 160°C. After being separated by the steam-water separator at the upper part of the hydrolysis reactor, the mixed gas enters the finished gas pipeline that supplies the finished ammonia-containing gas to 2 boilers respectively. Each path of the finished ammonia-containing gas is mixed and diluted with the hot dilution air in the ammonia-air mixer 13 through flow control and regulation until the ammonia concentration is below 5%, and finally enters the SCR reactor 18 through the ammonia injection grid for denitration.

[0078] When the thermal power unit is operating in summer with a load of 300MW and the ambient atmospheric temperature is 32°C. The diameter of the finished gas pipeline 11 is DN250 (i.e., the nominal diameter is 250mm), and the diameter of the tracing pipeline 10 is DN50. Open the electric first switch valve 5 and the electric second switch valve 9 to introduce the hot dilution air into the tracing pipeline 10. Through the coordinated adjustment of the electric first regulating valve 8 and the electric second regulating valve 14, control the amount of dilution air entering the tracing pipeline 10. The opening of the electric first regulating valve 8 is 50%, and the opening of the electric second regulating valve 14 is 78%. The temperature monitored by the thermocouple 7 at the end of the tracing pipeline 10 is 163°C. This temperature can meet the requirement that the finished gas tracing temperature is not lower than 150°C.

[0079] When the thermal power unit is operating in winter with an operating load of 145 MW and an atmospheric environmental temperature of -22°C. The diameter of the finished gas pipeline 1111 is DN250, and the diameter of the tracing pipeline 1010 is DN50. Open the first electric switch valve 5 and the second electric switch valve 9, and introduce the hot dilution air into the tracing pipeline 10. Through the coordinated adjustment of the first electric regulating valve 8 and the second electric regulating valve 14, control the dilution air volume entering the tracing pipeline 1010. The opening degree of the first electric regulating valve 8 is 90%, and the opening degree of the second electric regulating valve 14 is 57%. The temperature monitored by the thermocouple 7 at the end of the tracing pipeline 10 is 154°C. This temperature can meet the requirement that the tracing temperature of the finished gas is not lower than 150°C.

[0080] Experimental Example 2

[0081] The denitration device of a 600 MW thermal power unit adopts the SCR process, and the reducing agent ammonia is prepared by the urea hydrolysis process. The ammonia production capacity of a single hydrolyzer is 480 kg / h, and the urea mixed solution with a concentration of about 50% is transported to the urea hydrolyzer, where a hydrolysis reaction occurs at a pressure of about 0.4 MPa - 0.6 MPa and a temperature of about 130°C - 160°C to generate a mixed gas with an ammonia concentration of about 37.5%. After being separated by the steam-water separator at the upper part of the hydrolysis reactor, the mixed gas enters the finished gas pipeline that supplies the finished gas containing ammonia to 2 boilers respectively. Each path of the finished gas containing ammonia is adjusted by flow control and then mixed with the hot dilution air in the ammonia-air mixer 13 and diluted to an ammonia concentration below 5%, and finally enters the SCR reactor 18 through the ammonia injection grid for denitration.

[0082] When the unit is operating in summer with an operating load of 500 MW and an atmospheric environmental temperature of 31°C. The diameter of the finished gas pipeline 11 is DN300, and the diameter of the tracing pipeline 10 is DN65. Open the first electric switch valve 5 and the second electric switch valve 9. The opening degree of the first electric regulating valve 8 is 45%, and the opening degree of the second electric regulating valve 14 is 80%. The temperature monitored by the thermocouple 7 at the end of the tracing pipeline 10 is 161°C. The hot dilution air in the tracing pipeline 10 is pressurized to 0.6 Mpa by the hot dilution air booster pump 6, which is higher than the pressure of the finished gas in the finished gas pipeline 11, so that the hot dilution air can smoothly enter the finished gas pipeline 11 to be mixed with the finished gas, then enter the ammonia-air mixer 13, and finally enter the SCR reactor 18.

[0083] When the unit is scheduled to shut down, the unit is disconnected from the power grid, the denitration system of the unit is taken out of operation, and the urea hydrolysis system needs to be maintained in cold shutdown. The dilution fan 16 continues to operate. Since there is still residual heat in the boiler, the dilution air heat exchanger 17 still heats the dilution air. Close the electric valve 4 between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1. Increase the opening of the electric first regulating valve 8 and decrease the opening of the electric second regulating valve 14 to increase the hot dilution air volume of the tracing pipeline 10 and clean the finished gas pipeline 11. The residual finished gas in the finished gas pipeline 11 is blown away from the finished gas pipeline 11 by the hot dilution air and enters the SCR reactor 18. Close the electric valve 12 between the finished gas pipeline 11 and the SCR reactor 18, open the electric blowdown valve 3 and the electric valve 4 between the finished gas pipeline 11 and the urea ammonia hydrolysis device 1. Increase the opening of the electric regulating valve 8 and decrease the opening of the electric regulating valve 14 to increase the hot dilution air volume of the tracing pipeline 10 and clean the urea ammonia hydrolysis device 1. The hot dilution air will blow out the residual components in the urea ammonia hydrolysis device 1. The purging time needs to reach 12 hours until there are no residual components in the urea ammonia hydrolysis device 1. During the purging process using the hot dilution air, the oxygen in the hot dilution air further contacts the stainless steel to form an oxidation passivation film, achieving an anti-corrosion effect.

[0084] In this text, specific examples are used to elaborate on the principles and implementation manners of this application, and there is a progressive relationship between each embodiment. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. The description of the above embodiments is only used to help understand the method and its core idea of this application. For those of ordinary skill in the art in this technical field, without departing from the principle of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0085] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the element defined by the statement "including a..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

Claims

1. An anti-corrosion method for urea hydrolysis ammonia production equipment, characterized in that, Including: Passing hot dilution air into the traced pipeline to heat the finished gas pipeline; When the temperature of the finished gas pipeline reaches a preset temperature, allowing the hot dilution air to enter the finished gas pipeline and mix with the finished gas; the finished gas is the finished gas generated in the urea-to-ammonia hydrolyzer and then introduced into the finished gas pipeline; After mixing, allowing the hot dilution air and the finished gas to enter the selective catalytic reduction reactor through the finished gas pipeline, and distributing the oxygen in the hot dilution air throughout the finished gas pipeline, so that an oxide film covers the inner wall of the finished gas pipeline.

2. The anti-corrosion method for urea hydrolysis ammonia production equipment according to claim 1, characterized in that, After allowing the hot dilution air and the finished gas to enter the selective catalytic reduction reactor through the finished gas pipeline, it further includes: When the urea-to-ammonia hydrolyzer stops operating, closing the valve between the finished gas pipeline and the urea-to-ammonia hydrolyzer, allowing the hot dilution air to enter the finished gas pipeline, cleaning the finished gas pipeline, allowing the hot dilution air and the remaining finished gas to enter the selective catalytic reduction reactor, and distributing the oxygen in the hot dilution air throughout the finished gas pipeline, so that an oxide film covers the inner wall of the finished gas pipeline.

3. The anti-corrosion method for urea hydrolysis ammonia production equipment according to claim 1, characterized in that, After allowing the hot dilution air and the finished gas to enter the selective catalytic reduction reactor through the finished gas pipeline, it further includes: When the urea-to-ammonia hydrolyzer stops operating, closing the valve between the finished gas pipeline and the selective catalytic reduction reactor, allowing the hot dilution air to enter the urea-to-ammonia hydrolyzer, cleaning the urea-to-ammonia hydrolyzer, allowing the hot dilution air and the residual components in the urea-to-ammonia hydrolyzer to be discharged from the blowdown port of the urea-to-ammonia hydrolyzer, and distributing the oxygen in the hot dilution air throughout the urea-to-ammonia hydrolyzer, so that an oxide film covers the inner wall of the urea-to-ammonia hydrolyzer.

4. The anti-corrosion method for urea hydrolysis ammonia production equipment according to claim 1, characterized in that, The step of passing hot dilution air into the traced pipeline to heat the finished gas pipeline includes: Passing the hot dilution air into the traced pipeline, and controlling the amount of hot dilution air entering the traced pipeline through the first regulating valve and the second regulating valve to heat the finished gas pipeline; the first regulating valve is a valve provided between the first output end and the input end of the traced pipeline, and the second regulating valve is a valve provided between the second output end and the input end of the traced pipeline.

5. The anti-corrosion method for urea hydrolysis ammonia production equipment according to claim 1, characterized in that, The step of passing hot dilution air into the traced pipeline to heat the finished gas pipeline includes: Passing the hot dilution air into the traced pipeline, and monitoring the temperature of the hot dilution air in the traced pipeline through a thermocouple to heat the finished gas pipeline.

6. The anti-corrosion method for urea hydrolysis ammonia production equipment according to claim 1, characterized in that, The step of allowing the hot dilution air to enter the finished gas pipeline and mix with the finished gas includes: Pressurizing the traced pipeline through a hot dilution air booster pump to allow the hot dilution air to enter the finished gas pipeline and mix with the finished gas.

7. A urea hydrolysis ammonia production equipment, characterized in that, Including: A urea-to-ammonia hydrolyzer, a finished gas pipeline, a hot dilution air pipeline, a dilution blower, a dilution air heat exchanger, and a selective catalytic reduction reactor; the hot dilution air pipeline includes an inlet pipeline and a traced pipeline. The output end of the urea-to-ammonia hydrolyzer is communicated with the input end of the finished gas pipeline, and is used to generate finished gas and then introduce the finished gas into the finished gas pipeline; The dilution blower is communicated with the input end of the inlet pipeline, and is used to introduce dilution air into the hot dilution air pipeline; One end of the dilution air heat exchanger is communicated with the output end of the inlet pipeline, and the other end of the dilution air heat exchanger is communicated with the input end of the tracing pipeline, and is used to heat the dilution air to form hot dilution air; The tracing pipeline is used to heat the finished gas pipeline; The first output end of the tracing pipeline is communicated with the input end of the finished gas pipeline, and the output end of the finished gas pipeline is communicated with the selective catalytic reduction reactor, and is used to make the hot dilution air enter the finished gas pipeline to be mixed with the finished gas when the temperature of the finished gas pipeline reaches a preset temperature; after mixing, make the hot dilution air and the finished gas enter the selective catalytic reduction reactor through the finished gas pipeline, and make the oxygen in the hot dilution air be distributed everywhere in the finished gas pipeline, so that the inner wall of the finished gas pipeline is covered with an oxide film.

8. The urea hydrolysis ammonia production equipment according to claim 7, characterized in that, The tracing pipeline further includes a second output end; the second output end is communicated with an ammonia-air mixer; the ammonia-air mixer is communicated with the finished gas pipeline on one side close to the output end of the finished gas pipeline; A first regulating valve is arranged between the first output end and the input end of the tracing pipeline; a second regulating valve is arranged between the second output end and the input end of the tracing pipeline; the first regulating valve and the second regulating valve are used to control the amount of the hot dilution air entering the tracing pipeline.

9. The urea hydrolysis ammonia production equipment according to claim 7, characterized in that, Further included: A thermocouple; the thermocouple is used to monitor the temperature of the hot dilution air in the tracing pipeline.

10. The urea hydrolysis ammonia production equipment according to claim 7, characterized in that, Further included: A hot dilution air booster pump; the hot dilution air booster pump is communicated with the tracing pipeline, and is used to pressurize the tracing pipeline to make the hot dilution air enter the finished gas pipeline to be mixed with the finished gas.

Images