A rapid urea-ammonia production system and its control method

Abstract

This invention discloses a rapid urea-to-ammonia system for clearing blockages, comprising: a pyrolysis furnace body, a urea solution supply system, a boiler system, a high-temperature dilution air system, a high-temperature and high-pressure demineralized water system, a wastewater discharge pipe, and an SCR denitrification system. The urea solution supply system and the high-temperature dilution air system are connected to the top of the pyrolysis furnace body, while the high-temperature and high-pressure demineralized water system, wastewater discharge pipe, and SCR denitrification system are connected to the bottom of the pyrolysis furnace body. The boiler system is connected to both the high-temperature dilution air system and the high-temperature and high-pressure demineralized water system. A thermocouple and a pressure gauge are also installed at the bottom of the pyrolysis furnace body. The pyrolysis furnace body is connected to the high-temperature and high-pressure demineralized water system. After being heated and pressurized, the demineralized water system can remove dust and crystals from the bottom of the pyrolysis furnace, achieving rapid cleaning and ensuring the normal operation of the pyrolysis furnace body, thereby providing sufficient ammonia for the SCR denitrification system.

Description

Technical fields:

[0001] This invention belongs to the field of urea pyrolysis ammonia production technology, and specifically relates to a rapid urea ammonia production system for clearing blockages and its control method. Background technology:

[0002] Liquid ammonia was once widely used as a reducing agent in the SCR denitrification process of coal-fired power plants. However, the use of liquid ammonia has many side effects. When ammonia is inhaled, it can cause neurotoxicity to the brain and necrosis of body tissues. Liquid ammonia also pollutes the environment.

[0003] There are two main methods for producing ammonia from urea: one is the decomposition of urea in the form of an aqueous solution, called urea hydrolysis; the other is the rapid heating of the atomized urea solution, called urea pyrolysis. The urea hydrolysis method requires high-pressure steam equipment and suffers from problems such as high product gas content at the hydrolyzer outlet and insufficient pipeline heating temperature, easily leading to equipment and catalyst blockage. Urea pyrolysis, with its advantages of lower investment, less likelihood of intermediate polymer formation, and more complete reaction, has become the mainstream denitrification reducing agent in coal-fired power plants. Although the urea pyrolysis process is widely used, in actual production, incomplete urea pyrolysis, blockage of the pyrolysis furnace and ammonia injection grid still exist, leading to insufficient ammonia supply. This, in turn, causes uneven SCR ammonia injection, high NOx concentration at the furnace outlet, and a series of other problems, affecting the operation of the entire system.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention:

[0005] The purpose of this invention is to provide a rapid urea-ammonia production system and its control method for clearing blockages, thereby overcoming the defects in the prior art.

[0006] To achieve the above objectives, the present invention provides a rapid urea-to-ammonia production system for unclogging blockages, comprising: a pyrolysis furnace body, a urea solution supply system, a boiler system, a high-temperature dilution air system, a high-temperature and high-pressure demineralized water system, a wastewater discharge pipe, and an SCR denitrification system. The urea solution supply system and the high-temperature dilution air system are respectively connected to the top of the pyrolysis furnace body, and the high-temperature and high-pressure demineralized water system, the wastewater discharge pipe, and the SCR denitrification system are respectively connected to the bottom of the pyrolysis furnace body. The boiler system is connected to the high-temperature dilution air system and the high-temperature and high-pressure demineralized water system. A thermocouple and a pressure measuring device are also provided at the bottom of the pyrolysis furnace body.

[0007] Furthermore, as a preferred embodiment, a urea solution spray gun is also provided at the top of the pyrolysis furnace body, and the urea solution spray gun is connected to the urea solution supply system.

[0008] Furthermore, as a preferred embodiment, the urea solution supply system includes a urea dissolving tank and a solution storage tank, which are connected by a delivery pipeline. A delivery pump is provided on the delivery pipeline, and the solution storage tank is connected to a urea solution spray gun via a supply pipeline.

[0009] Furthermore, as a preferred embodiment, the supply pipeline is also equipped with a metering and distribution module.

[0010] Furthermore, as a preferred embodiment, the pyrolysis furnace body is also equipped with a high-temperature and high-pressure demineralized water spray gun, which is connected to the high-temperature and high-pressure demineralized water system.

[0011] Furthermore, as a preferred embodiment, the SCR denitrification system is connected to the deheating furnace body via a denitrification pipeline, and the denitrification pipeline is also equipped with an ammonia injection grid.

[0012] This invention also provides a control method for rapidly clearing blockages in a urea-to-ammonia system, comprising the following steps:

[0013] S1: The urea solution is sent to the urea solution supply system. The amount of urea solution is determined by the amount of ammonia used. The urea solution is then sprayed into the decomposition furnace body for decomposition.

[0014] S2: The boiler system generates hot steam during operation. Part of the hot steam flows to the high-temperature dilution air system. The high-temperature dilution air system introduces hot steam into the top of the pyrolysis furnace body to provide the required temperature field and flow field for the pyrolysis of the urea solution introduced into the pyrolysis furnace body.

[0015] S3: The urea solution is pyrolyzed into the required ammonia gas in the pyrolysis furnace body. The ammonia gas enters the SCR denitrification system, and the wastewater is discharged from the wastewater discharge pipe.

[0016] S4: The thermocouple inside the deheating furnace measures the temperature T inside the furnace in real time, and the pressure measuring device measures the pressure P inside the furnace in real time. When the temperature T is less than the preset value and the pressure P is higher than the preset value, it is determined that there is crystallization and dust blockage at the bottom of the deheating furnace body.

[0017] S5: The boiler system generates hot steam during operation. Another part of the hot steam flows into the high-temperature and high-pressure demineralized water system to heat the demineralized water. After the high-temperature and high-pressure demineralized water system completes the storage of demineralized water, it sprays high-temperature demineralized water into the bottom of the pyrolysis furnace body. The dust and crystals at the bottom of the pyrolysis furnace body dissolve in the high-temperature demineralized water and are discharged into the wastewater discharge pipe.

[0018] S6: The thermocouple inside the deheating furnace continues to measure the temperature T inside the furnace in real time, and the pressure measuring device continues to measure the pressure P inside the furnace in real time. When the temperature T is greater than the preset value and the pressure P is lower than the preset value, it indicates that the unblocking process is over.

[0019] Furthermore, as a preferred embodiment, the high-temperature and high-pressure demineralized water system operates for 30 minutes, then pauses for 5 minutes, restarts for 30 minutes, and then pauses for 5 minutes again, repeating this process until the temperature T inside the furnace is greater than the preset value and the pressure P is lower than the preset value.

[0020] Compared with the prior art, one aspect of the present invention has the following beneficial effects:

[0021] (1) The present invention is equipped with a high-temperature dilution air system and a high-temperature and high-pressure demineralized water system. The high-temperature dilution air system can provide the required temperature field and flow field for the pyrolysis of urea solution, which is helpful for the pyrolysis of urea solution.

[0022] (2) During the pyrolysis of urea solution, the temperature and pressure inside the furnace are monitored in real time by thermocouples and pressure measuring instruments. This allows for accurate determination of whether there is a blockage at the bottom of the furnace. The blockage can then be cleared quickly by a high-temperature and high-pressure demineralized water system, which can effectively solve problems such as incomplete urea decomposition, severe ash accumulation at the bottom of the pyrolysis furnace, and blockage by crystals. Attached image description:

[0023] Figure 1 This is a schematic diagram of a rapid urea-to-ammonia system for clearing blockages according to the present invention;

[0024] Attached reference numerals: 1-Pyrolysis furnace body, 2-Urea solution supply system, 21-Urea dissolving tank, 22-Solution storage tank, 23-Transfer pipeline, 24-Transfer pump, 25-Supply pipeline, 26-Metering and distribution module, 3-Boiler system, 4-High temperature dilution air system, 5-High temperature and high pressure demineralized water system, 6-Wastewater discharge pipe, 7-SCR denitrification system, 8-Thermocouple, 9-Pressure measuring instrument, 10-Urea solution spray gun, 11-High temperature and high pressure demineralized water spray gun, 12-Denitrification pipeline, 13-Ammonia spraying grid. Detailed implementation method:

[0025] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0026] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0027] Example 1:

[0028] like Figure 1As shown, a rapid urea-to-ammonia production system includes: a pyrolysis furnace body 1, a urea solution supply system 2, a boiler system 3, a high-temperature dilution air system 4, a high-temperature and high-pressure demineralized water system 5, a wastewater discharge pipe 6, and an SCR denitrification system 7. The urea solution supply system 2 and the high-temperature dilution air system 4 are respectively connected to the top of the pyrolysis furnace body 1. The high-temperature and high-pressure demineralized water system 5, the wastewater discharge pipe 6, and the SCR denitrification system 7 are respectively connected to the bottom of the pyrolysis furnace body 1. The boiler system 3 is connected to the high-temperature dilution air system 4 and the high-temperature and high-pressure demineralized water system 5. A thermocouple 8 and a pressure measuring device 9 are also provided at the bottom of the pyrolysis furnace body 1.

[0029] In this embodiment, a urea solution spray gun 10 is also provided at the top of the pyrolysis furnace body 1, and the urea solution spray gun 10 is connected to the urea solution supply system 2. The urea solution in the urea solution supply system 2 is sprayed onto the pyrolysis furnace body 1 by the urea solution spray gun 10, which further facilitates the pyrolysis reaction of the urea solution.

[0030] In this embodiment, the urea solution supply system 2 includes a urea dissolving tank 21 and a solution storage tank 22. The urea dissolving tank 21 and the solution storage tank 22 are connected by a delivery pipeline 23. A delivery pump 24 is installed on the delivery pipeline 23. The solution storage tank 22 is connected to the urea solution spray gun 10 through a supply pipeline 25. Urea is dissolved into a urea solution in the urea dissolving tank 21. The urea solution is transported to the solution storage tank 22 by the delivery pipeline 23, and then the delivery pump 24 transports the urea solution to the urea solution spray gun 10 inside the pyrolysis furnace body 1, where it is sprayed into the pyrolysis furnace body 1.

[0031] In this embodiment, the supply pipeline 25 is also provided with a metering and distribution module 26. The metering and distribution module 26 adjusts the amount of urea solution injected into the pyrolysis furnace body 1 according to the metered amount of ammonia used, so as to accurately control the amount of urea solution injected.

[0032] In this embodiment, the pyrolysis furnace body 1 is further equipped with a high-temperature and high-pressure demineralized water spray gun 11, which is connected to the high-temperature and high-pressure demineralized water system 5. When the bottom of the pyrolysis furnace body 1 is clogged with crystals and dust and needs to be cleared, the high-temperature demineralized water in the high-temperature and high-pressure demineralized water system 5 is sprayed onto the bottom of the pyrolysis furnace body 1 through the high-temperature and high-pressure demineralized water spray gun 11 to clean the crystals and dust clogged at the bottom, thereby achieving the purpose of clearing the clog. The high-temperature and high-pressure demineralized water system 5 is a device for storing demineralized water and can heat and pressurize the demineralized water inside to form high-temperature and high-pressure demineralized water, which is then sprayed onto the bottom of the pyrolysis furnace body 1 by the high-temperature and high-pressure demineralized water spray gun 11.

[0033] In this embodiment, the SCR denitrification system 7 is connected to the pyrolysis furnace body 1 via a denitrification pipeline 12, which is also equipped with an ammonia injection grid 13. The ammonia gas generated by pyrolysis in the pyrolysis furnace body 1 enters the SCR denitrification system for reaction through the ammonia injection grid 13. The use of the ammonia injection grid 13 helps the ammonia gas to react uniformly in the SCR denitrification system.

[0034] The above-mentioned control method for rapidly clearing blockages in a urea-to-ammonia system includes the following steps:

[0035] S1: The urea solution is sent to the urea solution supply system 2. The amount of urea solution is determined by the amount of ammonia used. The urea solution is sprayed into the decomposition furnace body 1 for decomposition.

[0036] S2: The boiler system 3 generates hot steam during operation. Part of the hot steam flows to the high-temperature dilution air system 4. The high-temperature dilution air system 4 introduces hot steam into the top of the pyrolysis furnace body 1 to provide the required temperature field and flow field for the pyrolysis of the urea solution introduced into the pyrolysis furnace body 1.

[0037] S3: The urea solution is pyrolyzed into the required ammonia gas in the pyrolysis furnace body 1. The ammonia gas enters the SCR denitrification system 7, and the wastewater is discharged from the wastewater discharge pipe 6.

[0038] S4: The thermocouple 8 inside the deheating furnace body 1 measures the temperature T inside the furnace body in real time, and the pressure measuring device measures the pressure P inside the furnace body in real time. When the temperature T is less than the preset value and the pressure P is higher than the preset value, it is determined that there is crystallization and dust blockage at the bottom of the deheating furnace body 1.

[0039] S5: Boiler system 3 generates hot steam during operation. Another part of the hot steam flows into high temperature and high pressure demineralized water system 5 to heat the demineralized water. After the high temperature and high pressure demineralized water system 4 completes the storage of demineralized water, it sprays high temperature demineralized water into the bottom of the pyrolysis furnace body 1. The dust and crystals at the bottom of the pyrolysis furnace body 1 dissolve in the high temperature demineralized water and are discharged into the wastewater discharge pipe 6.

[0040] S6: The thermocouple 8 inside the deheating furnace body 1 continues to measure the temperature T inside the furnace body in real time, and the pressure measuring device continues to measure the pressure P inside the furnace body in real time. When the temperature T is greater than the preset value and the pressure P is lower than the preset value, it indicates that the unblocking process is over.

[0041] The pyrolysis furnace body of the present invention is connected to a high-temperature and high-pressure demineralized water system. When a blockage occurs in the pyrolysis furnace body, abnormal temperature or pressure will be observed. At this time, the demineralized water is heated by the boiler system. After being heated and pressurized, the demineralized water can remove the dust and crystals at the bottom of the pyrolysis furnace, achieving a rapid cleaning effect and ensuring the normal operation of the pyrolysis furnace body, thereby providing sufficient ammonia for the SCR denitrification system.

[0042] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A rapid urea-to-ammonia production system for clearing blockages, characterized in that, include: The pyrolysis furnace body comprises a urea solution supply system, a boiler system, a high-temperature dilution air system, a high-temperature and high-pressure demineralized water system, a wastewater discharge pipe, and an SCR denitrification system. The urea solution supply system and the high-temperature dilution air system are connected to the top of the pyrolysis furnace body, while the high-temperature and high-pressure demineralized water system, wastewater discharge pipe, and SCR denitrification system are connected to the bottom of the pyrolysis furnace body. The boiler system is connected to the high-temperature dilution air system and the high-temperature and high-pressure demineralized water system. A thermocouple and a pressure measuring device are also installed at the bottom of the pyrolysis furnace body. The control method of the system includes the following steps: S1: The urea solution is sent to the urea solution supply system. The amount of urea solution is determined by the amount of ammonia used. The urea solution is then sprayed into the pyrolysis furnace body for decomposition. S2: The boiler system generates hot steam during operation. Part of the hot steam flows to the high-temperature dilution air system. The high-temperature dilution air system introduces hot steam into the top of the pyrolysis furnace body to provide the required temperature field and flow field for the pyrolysis of the urea solution introduced into the pyrolysis furnace body. S3: The urea solution is pyrolyzed into the required ammonia gas in the pyrolysis furnace body. The ammonia gas enters the SCR denitrification system, and the wastewater is discharged from the wastewater discharge pipe. S4: The thermocouple inside the pyrolysis furnace measures the temperature T inside the furnace in real time, and the pressure measuring device measures the pressure P inside the furnace in real time. When the temperature T is less than the preset value and the pressure P is higher than the preset value, it is determined that there is crystallization and dust blockage at the bottom of the pyrolysis furnace body. S5: The boiler system generates hot steam during operation. Another part of the hot steam flows into the high-temperature and high-pressure demineralized water system to heat the demineralized water. After the high-temperature and high-pressure demineralized water system completes the storage of demineralized water, it sprays high-temperature demineralized water into the bottom of the pyrolysis furnace body. The dust and crystals at the bottom of the pyrolysis furnace body dissolve in the high-temperature demineralized water and are discharged into the wastewater discharge pipe. S6: The thermocouple inside the pyrolysis furnace continues to measure the temperature T inside the furnace in real time, and the pressure measuring device continues to measure the pressure P inside the furnace in real time. When the temperature T is greater than the preset value and the pressure P is lower than the preset value, it indicates that the unblocking process is over. When the bottom of the pyrolysis furnace body is blocked by crystals and dust and needs to be cleared, the high-temperature demineralized water in the high-temperature and high-pressure demineralized water system is sprayed onto the bottom of the pyrolysis furnace body through a high-temperature and high-pressure demineralized water spray gun to clean the crystals and dust blockage at the bottom, thereby achieving the purpose of clearing the blockage.

2. The rapid urea-to-ammonia production system according to claim 1, characterized in that, The top of the pyrolysis furnace body is also equipped with a urea solution spray gun, which is connected to the urea solution supply system.

3. The rapid urea-to-ammonia system for clearing blockages according to claim 2, characterized in that, The urea solution supply system includes a urea dissolving tank and a solution storage tank, which are connected by a delivery pipeline. A delivery pump is installed on the delivery pipeline, and the solution storage tank is connected to a urea solution spray gun through a supply pipeline.

4. The rapid urea-to-ammonia production system according to claim 3, characterized in that, The supply pipeline is also equipped with a metering and distribution module.

5. The rapid urea-to-ammonia production system according to claim 1, characterized in that, The pyrolysis furnace body is also equipped with a high-temperature and high-pressure demineralized water spray gun, which is connected to the high-temperature and high-pressure demineralized water system.

6. The rapid urea-to-ammonia system for clearing blockages according to claim 1, characterized in that, The SCR denitrification system is connected to the pyrolysis furnace body through a denitrification pipeline, and the denitrification pipeline is also equipped with an ammonia injection grid.

7. The rapid urea-to-ammonia production system according to claim 1, characterized in that: The high-temperature and high-pressure demineralized water system operates for 30 minutes, then pauses for 5 minutes, restarts for 30 minutes, and then pauses for 5 minutes again. This process is repeated until the temperature T inside the furnace is greater than the preset value and the pressure P is lower than the preset value.

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