Anti-crystallization SCR (Selective Catalytic Reduction) denitration agent pyrolysis tower

Abstract

The invention discloses an SCR (Selective Catalytic Reduction) denitration agent pyrolysis tower for preventing crystallization. The SCR denitration agent pyrolysis tower comprises a tower body, a return pipe and a blanking pipe, the heat exchange balls circulate between the tower body and the return pipe, so that heat can be effectively transferred to ammonium carbamate, the phenomenon of caking caused by local overheating in the pyrolysis process is avoided, and the risk of pipeline blockage is reduced. The heat exchange balls are heated through hot smoke, the heat energy utilization efficiency can be effectively improved, the requirement for an external heat source is reduced, and therefore the energy consumption cost is reduced. Ammonium carbamate is uniformly heated and decomposed in the pyrolysis section, so that the generation of ammonia gas is more stable, and the denitration efficiency of the SCR denitration system is favorably improved. According to the invention, the safety risk possibly existing in the process of preparing ammonia from urea under a high-temperature condition is avoided, and the safety of the system is improved. Compared with urea, ammonium carbamate serving as a denitration agent has the cost advantage, meanwhile, steps in the process of preparing ammonia from urea are reduced, the cost is reduced, the ammonia preparation efficiency is 5.6%-22.8% and is averagely improved by 14.20%, and the energy consumption is reduced by 40.0%-55.0%.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment in coal-fired power plants, and in particular to an SCR denitrification agent pyrolysis tower for preventing crystallization. Background Art

[0002] With growing awareness of environmental protection and the increasing demand for air pollution control, controlling NOx emissions from coal-fired power plants has become a key focus of environmental protection efforts. Selective catalytic reduction (SCR) flue gas denitrification technology is widely used in coal-fired power plants due to its proven effectiveness in controlling NOx emissions from coal-fired units. Urea, currently the most commonly used flue gas denitrification reducing agent, is a relatively mature and safe ammonia production process. However, the high temperature required to produce ammonia from urea increases the energy cost of the denitrification system.

[0003] In the related art, addressing the limitations of existing urea-ammonia production technology, the use of ammonium carbamate, an intermediate product in urea production, as the primary denitrification agent has been proposed, offering cost advantages. However, ammonium carbamate is prone to agglomeration during the selective catalytic denitrification of flue gas, leading to pipeline blockage and difficulty in decomposition. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, an embodiment of the present invention provides an SCR denitrification agent pyrolysis tower for preventing crystallization.

[0006] The SCR denitrification agent pyrolysis tower for preventing crystallization in an embodiment of the present invention includes a tower body, a reflux pipe and a discharge pipe. The tower body has a feed section, a pyrolysis section and a discharge section arranged in sequence from top to bottom, and the pyrolysis section has a mixed gas outlet; the first end of the reflux pipe is connected to the feed section, and the second end of the reflux pipe is connected to the discharge section. The reflux pipe is provided with a heat exchange ball circulating between the tower body and the reflux pipe, and the reflux pipe has a hot flue gas inlet. The hot flue gas inlet is used for hot flue gas to enter the reflux pipe and exchange heat with the heat exchange ball. After heat exchange, the heat exchange ball is used to provide heat to the pyrolysis section; the discharge pipe is provided on the tower body and one end extends into the pyrolysis section to transport ammonium carbamate powder into the pyrolysis section. The ammonium carbamate powder exchanges heat with the heat exchange ball in the pyrolysis section to undergo pyrolysis and generate a mixed gas of ammonia and carbon dioxide, which is discharged through the mixed gas outlet.

[0007] In some embodiments, the SCR denitrification agent pyrolysis tower for preventing crystallization of an embodiment of the present invention includes a solid-gas separator, which has a solid-gas inlet, a solid outlet and a gas outlet. The solid-gas inlet is connected to the first end of the reflux pipe, and the solid outlet is connected to the feed section. The hot flue gas in the reflux pipe and the heat exchange ball enter the solid-gas separator through the solid-gas inlet for separation. The separated heat exchange ball enters the feed section through the solid outlet, and the separated hot flue gas is discharged through the gas outlet.

[0008] In some embodiments, the diameter of the heat exchange ball is 0.3 mm to 2.0 mm, the temperature of the hot flue gas is 300° C. to 350° C., and the flow rate of the hot flue gas in the return pipe is 3 m / s to 6 m / s.

[0009] In some embodiments, the heat exchange ball is transported in the reflux pipe for 5s to 10s, and the temperature of the heat exchange ball rises to 260°C to 300°C after heat exchange.

[0010] In some embodiments, the hot flue gas in the reflux pipe enters the solid-gas separator at a flow rate of 25m / s to 40m / s, and the separated hot flue gas is discharged through the gas outlet after its temperature drops to 240°C to 280°C.

[0011] In some embodiments, the contact time of the heat exchange ball with the ammonium carbamate powder in the pyrolysis section is 15s to 20s, the temperature of the heat exchange ball after heat exchange in the pyrolysis section is 140°C to 180°C, a discharge pipe is provided between the discharge section and the second end of the reflux pipe, and the flow velocity of the heat exchange ball in the discharge pipe is controlled to be 0.02m / s to 0.05m / s.

[0012] In some embodiments, a distribution plate is provided between the feed section and the pyrolysis section, and a plurality of distribution holes are arranged at intervals on the distribution plate, and the diameter of the distribution holes is 60 mm to 120 mm. The discharge pipe passes through the distribution plate and the outlet end of the discharge pipe is located in the pyrolysis section.

[0013] In some embodiments, there are multiple discharge pipes, and the multiple discharge pipes are arranged on the tower body at intervals, and the inner diameter of the discharge pipe is 50 mm to 80 mm.

[0014] In some embodiments, an L-shaped partition is provided in the pyrolysis section, and the L-shaped partition includes a vertical first plate and a second plate. The first plate is provided above the mixed gas outlet and extends radially along the tower body, and the second plate is spaced apart from the tower wall of the pyrolysis section and extends downward. A gas channel for the flow of the mixed gas is defined between the L-shaped partition and the tower wall of the pyrolysis section.

[0015] In some embodiments, the height ratio of the feed section, the pyrolysis section and the discharge section is (1-2): (3-5): (1-2), and the ratio of the height to diameter of each of the feed section, the pyrolysis section and the discharge section is (3-5): 1.

[0016] In the SCR denitrification tower for preventing crystallization according to the present invention, heat exchange balls circulate between the tower body and the reflux pipe, effectively transferring heat to ammonium carbamate. This prevents localized overheating and agglomeration of ammonium carbamate during the pyrolysis process, thereby reducing the risk of pipe blockage. Using hot flue gas to heat the heat exchange balls effectively improves thermal energy utilization, reduces the need for external heat sources, and thus lowers energy costs. The uniform thermal decomposition of ammonium carbamate within the pyrolysis section ensures more stable ammonia production, which helps improve the denitrification efficiency of the SCR denitrification system. This invention avoids potential safety risks associated with high-temperature urea-to-ammonia production, thereby enhancing system safety. Ammonium carbamate, as a denitrification agent, offers cost advantages over urea, while also reducing the number of steps in the urea-to-ammonia production process, thereby lowering costs. Compared to urea-to-ammonia production, the present invention achieves ammonia production efficiency of 5.6% to 22.8%, an average improvement of 14.20%, and reduces energy consumption by 40.0% to 55.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of an SCR denitrification agent pyrolysis tower for preventing crystallization according to an embodiment of the present invention.

[0018] Figure 2 2 is a schematic structural diagram of a tower body according to an embodiment of the present invention.

[0019] Figure 3 yes Figure 1 Cross-sectional view of AA in the figure.

[0020] Figure 4 yes Figure 1 Cross-sectional view of the BB.

[0021] 1. Tower body; 101. Feed section; 102. Pyrolysis section; 1021. Mixed gas outlet; 103. Discharge section; 2. Reflux pipe; 201. Hot flue gas inlet; 3. Heat exchange ball; 4. Discharge pipe; 5. Solid-gas separator; 501. Solid-gas inlet; 502. Solid outlet; 503. Gas outlet; 6. Discharge pipe; 7. Distribution plate; 701. Distribution hole; 8. L-shaped partition; 801. First plate; 802. Second plate; 9. Gas channel. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0023] like Figures 1 to 4 As shown, the SCR denitrification agent pyrolysis tower for preventing crystallization according to an embodiment of the present invention includes a tower body 1, a reflux pipe 2, and a discharge pipe 4. The tower body 1 has a feed section 101, a pyrolysis section 102, and a discharge section 103 arranged in sequence from top to bottom. The pyrolysis section 102 has a mixed gas outlet 1021. The first end of the reflux pipe 2 is connected to the feed section 101, and the second end of the reflux pipe 2 is connected to the discharge section 103. The reflux pipe 2 is provided with a heat exchange ball 3 that circulates between the tower body 1 and the reflux pipe 2. The reflux pipe 2 has a hot flue gas inlet 201. The hot flue gas inlet 201 is used for hot flue gas to enter the reflux pipe 2 for heat exchange with the heat exchange ball 3. After heat exchange, the heat exchange ball 3 is used to provide heat to the pyrolysis section 102. The feed pipe 4 is provided on the tower body 1 and one end of the feed pipe extends into the pyrolysis section 102 to transport ammonium carbamate powder into the pyrolysis section 102. The ammonium carbamate powder exchanges heat with the heat exchange balls 3 in the pyrolysis section 102 to undergo pyrolysis and generate a mixed gas of ammonia and carbon dioxide, which is discharged through the mixed gas outlet 1021.

[0024] When the SCR denitrification agent pyrolysis tower for preventing crystallization of the embodiment of the present invention is in use, the ammonium carbamate powder is fed into the pyrolysis section 102 of the pyrolysis tower through the discharge pipe 4. The heat exchange balls 3 in the reflux pipe 2 circulate, and the hot flue gas introduced through the hot flue gas inlet 201 exchanges heat with the heat exchange balls 3, causing the heat exchange balls 3 to heat up. The heated heat exchange balls 3 enter the pyrolysis section 102 through the feed section 101, contact the ammonium carbamate powder and transfer heat, causing the ammonium carbamate to be thermally decomposed to generate a mixed gas of ammonia and carbon dioxide. The generated mixed gas is discharged from the mixed gas outlet 1021 of the pyrolysis section 102, and then further used for NOx reduction in the SCR denitrification system. The heat exchange balls 3 after heat exchange are discharged through the discharge section 103 into the reflux pipe 2 for the next heat exchange cycle.

[0025] In the SCR denitrification tower for preventing crystallization according to the present invention, heat exchange balls 3 circulate between the tower body 1 and the reflux pipe 2, effectively transferring heat to ammonium carbamate. This prevents localized overheating and agglomeration of ammonium carbamate during the pyrolysis process, thereby reducing the risk of pipe blockage. Using hot flue gas to heat the heat exchange balls 3 effectively improves thermal energy utilization, reduces the need for external heat sources, and thus lowers energy costs. Because ammonium carbamate is uniformly decomposed within the pyrolysis section 102, ammonia production is more stable, which helps improve the denitrification efficiency of the SCR denitrification system. This invention avoids potential safety risks associated with high-temperature urea-to-ammonia production, thereby enhancing system safety. Ammonium carbamate, as a denitrification agent, offers cost advantages over urea, while also reducing the number of steps in the urea-to-ammonia production process, thereby lowering costs. Compared to urea-to-ammonia production, the present invention achieves ammonia production efficiency of 5.6% to 22.8%, an average improvement of 14.20%, and reduces energy consumption by 40.0% to 55.0%.

[0026] In some embodiments, the SCR denitrification agent pyrolysis tower for preventing crystallization according to embodiments of the present invention includes a solid-gas separator 5 having a solid-gas inlet 501, a solid outlet 502, and a gas outlet 503. The solid-gas inlet 501 is connected to the first end of the reflux pipe 2, and the solid outlet 502 is connected to the feed section 101. The hot flue gas and the heat exchange balls 3 in the reflux pipe 2 enter the solid-gas separator 5 through the solid-gas inlet 501 for separation. The separated heat exchange balls 3 enter the feed section 101 through the solid outlet 502, and the separated hot flue gas is discharged through the gas outlet 503.

[0027] The solid-gas separator 5 uses physical or mechanical means (such as gravity, centrifugal force, or filtration) to separate the heat exchange balls 3 (solid) from the hot flue gas (gas). After separation, the heat exchange balls 3 are returned to the feed section 101 through the solid outlet 502, while the separated hot flue gas is discharged through the gas outlet 503. The separated heat exchange balls 3 enter the feed section 101. Due to their higher temperature, they immediately heat the ammonium carbamate powder, promoting its thermal decomposition.

[0028] Solid-gas separation prevents direct contact between the hot flue gas and ammonium carbamate, which could lead to localized overheating and energy loss. The separation of the heat exchange balls 3 from the hot flue gas reduces the potential interference of impurities in the hot flue gas with the pyrolysis process, improving system stability and reliability. The separated heat exchange balls 3 enter the feed section 101 directly, preventing agglomeration and blockage within the pyrolysis tower caused by solid particles in the hot flue gas.

[0029] Optionally, the diameter of the heat exchange ball 3 is 0.3 mm to 2.0 mm, the hot flue gas temperature is 300° C. to 350° C., and the flow rate of the hot flue gas in the return pipe 2 is 3 m / s to 6 m / s.

[0030] Diameter of heat exchange ball 3 (0.3mm~2.0mm):

[0031] Smaller diameter heat exchange balls 3 have a greater surface area to volume ratio, which contributes to faster heat exchange efficiency because more ball surface area comes into contact with the ammonium carbamate powder, accelerating heat transfer. Smaller diameter balls 3 also create turbulence in the hot flue gas, which helps improve heat transfer efficiency, but can also lead to wear and reduced separation efficiency. The upper limit of the diameter (2.0 mm) is to ensure that the heat exchange balls 3 can circulate effectively in the return line 2 and solid-gas separator 5, while avoiding the reduction of heat exchange efficiency caused by excessively large balls.

[0032] Hot flue gas temperature (300℃~350℃):

[0033] This temperature range is generally considered suitable for the thermal decomposition of ammonium carbamate. Temperatures that are too low may result in incomplete decomposition, while temperatures that are too high may cause excessive decomposition of the ammonium carbamate, generating unwanted byproducts or damaging system materials. This temperature range also takes into account the actual available temperature of the hot flue gas and the thermal tolerance of the heat exchange ball 3 material.

[0034] Flow rate of hot flue gas in return pipe 2 (3m / s~6m / s):

[0035] A flow rate within this range ensures sufficient contact time between the hot flue gas and the heat exchange balls 3 for adequate heat exchange. Low flow rates help reduce wear and improve separation efficiency, but may result in reduced heat exchange efficiency. High flow rates improve heat exchange efficiency but may increase wear of the heat exchange balls 3 and reduce separation efficiency. The flow rate selection also needs to consider the system's pressure drop. Excessively high flow rates increase system resistance, thereby increasing energy consumption.

[0036] Optionally, the heat exchange ball 3 is transported in the reflux pipe 2 for 5s to 10s, and the temperature of the heat exchange ball 3 after heat exchange rises to 260°C to 300°C.

[0037] The conveying time of the heat exchange ball 3 in the return pipe 2 (5s to 10s):

[0038] This time period is the time the heat exchange balls 3 spend flowing through the hot flue gas, exchanging heat with it. This timeframe ensures that the heat exchange balls 3 absorb sufficient heat to reach the temperature required for the decomposition of ammonium carbamate. A short transfer time may result in insufficient heat exchange balls 3 temperature, preventing effective decomposition of ammonium carbamate. Excessive transfer time, however, may reduce heat exchange efficiency and increase system energy consumption. Furthermore, the transfer time is dependent on the length of the return pipe 2 and the flow rate of the hot flue gas, requiring precise design to ensure optimal results.

[0039] Temperature of heat exchange ball 3 after heat exchange (260℃~300℃):

[0040] The heat exchange balls 3 are heated to this temperature range in the hot flue gas to provide sufficient heat for the effective decomposition of ammonium carbamate powder into ammonia and carbon dioxide in the pyrolysis section 102. The lower limit of the temperature range (260°C) ensures that the ammonium carbamate begins to pyrolyze, while the upper limit (300°C) is designed to avoid excessive pyrolysis or other unwanted chemical reactions, while also taking into account the thermal stability and service life of the heat exchange ball 3 material. This temperature range also aligns with the optimal temperature range for ammonium carbamate pyrolysis, ensuring high pyrolysis efficiency and low energy consumption.

[0041] The heat exchange balls 3 remain in the return pipe 2 long enough to absorb heat from the hot flue gas, effectively heating the ammonium carbamate powder in the pyrolysis section 102. Controlling the temperature of the heat exchange balls 3 provides optimal conditions for the pyrolysis of ammonium carbamate, ensuring a high ammonia production rate and low energy consumption. Properly controlling the transport time and temperature of the heat exchange balls 3 in the return pipe 2 helps reduce system instability and potential equipment damage caused by temperature fluctuations.

[0042] In some embodiments, the flow rate of the hot flue gas in the reflux pipe 2 entering the solid-gas separator 5 is 25m / s to 40m / s, and the separated hot flue gas is discharged through the gas outlet 503 after its temperature drops to 240°C to 280°C.

[0043] High flow rates facilitate efficient solid-gas separation within the solid-gas separator 5. Within this flow rate range, the hot flue gas generates sufficient kinetic energy to create turbulence within the separator, which helps separate the heat exchange balls 3 from the hot flue gas and reduces the amount of solid particles discharged with the gas. However, excessively high flow rates may increase wear and tear and impact forces on the heat exchange balls 3 and the solid-gas separator 5.

[0044] After the hot flue gas releases some heat within the solid-gas separator 5, its temperature drops. This temperature range is designed to ensure that the hot flue gas does not cause excessive thermal pollution to the environment before exiting the system, while also taking into account subsequent processing or discharge requirements. Lowering the temperature to 240°C to 280°C also reduces heat waste, as overheated hot flue gas removes more heat and increases system heat loss. Furthermore, this temperature range helps protect the exhaust system's materials, preventing fatigue or damage caused by high temperatures.

[0045] As a result, the high-speed flow of hot flue gas in the solid-gas separator 5 effectively separates the heat exchange balls 3 from the gas, reducing the agglomeration and wear caused by solid particles within the tower. By lowering the temperature of the hot flue gas after separation, less heat is released into the environment, helping to save energy and reduce thermal pollution in the system. Lower temperatures also help protect exhaust system equipment and extend its service life.

[0046] In some embodiments, the contact time between the heat exchange balls 3 and the ammonium carbamate powder in the pyrolysis section 102 is 15 to 20 seconds, and the temperature of the heat exchange balls 3 after heat exchange in the pyrolysis section 102 is 140°C to 180°C. A discharge pipe 6 is provided between the discharge section 103 and the second end of the reflux pipe 2, and the flow velocity of the heat exchange balls 3 in the discharge pipe 6 is controlled to be 0.02 to 0.05 m / s.

[0047] The contact time between the heat exchange balls 3 and the ammonium carbamate powder in the pyrolysis section 102 (15 to 20 seconds) is the time it takes for the heat exchange balls 3 to exchange heat with the ammonium carbamate powder, ensuring that the ammonium carbamate absorbs sufficient heat for the pyrolysis reaction. Excessive contact time may lead to excessive pyrolysis of the ammonium carbamate or uneven temperature distribution within the tower, while too short a contact time may result in incomplete pyrolysis, affecting denitrification efficiency. An appropriate contact time ensures uniform pyrolysis of the ammonium carbamate, generating the desired ammonia gas while maintaining stable system operation.

[0048] The temperature of the heat exchange balls 3 after heat exchange in the pyrolysis section 102 (140°C to 180°C) is designed to ensure efficient pyrolysis of the ammonium carbamate without causing excessive pyrolysis or other unnecessary chemical reactions. A temperature that is too low may result in a slow or incomplete pyrolysis reaction, while a temperature that is too high may damage the tower body 1 material or cause excessive decomposition of the ammonium carbamate. This temperature range also helps reduce energy consumption and maintain the efficiency of the pyrolysis process.

[0049] The flow rate of the heat exchange balls 3 within the discharge pipe 6 is controlled at a speed of 0.02 to 0.05 m / s to ensure smooth movement from the pyrolysis section 102 to the discharge section 103, while also preventing wear caused by excessive speed or inefficient discharge due to excessive speed. A low flow rate helps reduce wear and ensures sufficient cooling time for the heat exchange balls 3 within the discharge pipe 6, preventing excessive temperatures from affecting the pyrolysis of ammonium carbamate or damaging the material of the discharge pipe 6.

[0050] In some embodiments, a distribution plate 7 is provided between the feed section 101 and the pyrolysis section 102, and a plurality of distribution holes 701 are arranged at intervals on the distribution plate 7. The diameter of the distribution holes 701 is 60 mm to 120 mm. The discharge pipe 4 passes through the distribution plate 7 and the outlet end of the discharge pipe 4 is located in the pyrolysis section 102.

[0051] like Figure 1 and Figure 2 As shown, the distribution plate 7 is located between the feed section 101 and the pyrolysis section 102. Its function is to evenly distribute the heat exchange balls 3 throughout the pyrolysis section 102, preventing accumulation of the heat exchange balls 3 within the pyrolysis section 102. This helps prevent agglomeration of the ammonium carbamate powder due to local overheating, thereby improving pyrolysis efficiency and reducing the risk of pipeline blockage. Furthermore, the evenly distributed heat exchange balls 3 ensure more complete contact with the ammonium carbamate powder, helping to increase ammonia production and thus improve denitration efficiency.

[0052] Optionally, there are multiple discharge pipes 4, which are spaced apart on the tower body 1, and the inner diameter of the discharge pipe 4 is 50 mm to 80 mm.

[0053] The design of multiple feeder tubes 4 increases the feed volume per unit time, improving production efficiency. The spaced arrangement of multiple feeder tubes 4, combined with the use of distribution plates 7, ensures uniform distribution of ammonium carbamate powder within the pyrolysis section 102, preventing localized overheating and agglomeration. The design of multiple feeder tubes 4 reduces the risk of clogging of a single feeder tube 4 and improves system reliability.

[0054] In some embodiments, an L-shaped baffle 8 is provided within the pyrolysis section 102. The L-shaped baffle 8 includes a first vertical plate 801 and a second vertical plate 802. The first vertical plate 801 is provided above the mixed gas outlet 1021 and extends radially along the tower body 1. The second vertical plate 802 is spaced apart from the tower wall of the pyrolysis section 102 and extends downward. A gas channel 9 for the flow of the mixed gas is defined between the L-shaped baffle 8 and the tower wall of the pyrolysis section 102.

[0055] The gas channel 9 increases the flow path of the mixed gas generated by pyrolysis. When the mixed gas flows out of the pyrolysis section, the ammonium carbamate powder mixed in the mixed gas has sufficient time to be pyrolyzed, preventing it from being carried out of the tower body 1 by the mixed gas, thereby improving the pyrolysis efficiency and reducing the waste of ammonium carbamate powder material.

[0056] In some embodiments, the height ratio of the feed section 101, the pyrolysis section 102 and the discharge section 103 is (1-2): (3-5): (1-2), and the ratio of the height to the diameter of each of the feed section 101, the pyrolysis section 102 and the discharge section 103 is (3-5): 1.

[0057] The height ratio of the feed section 101, pyrolysis section 102, and discharge section 103 is (1-2):(3-5):(1-2) to accommodate the functional requirements and operating conditions of each section. The feed section 101 and discharge section 103 are relatively low in height because their functions are relatively simple, primarily involving the feeding and discharging of heat exchange balls 3. The pyrolysis section 102 is relatively high because it requires sufficient space to ensure adequate contact between the ammonium carbamate powder and the heat exchange balls 3 and for the pyrolysis reaction to proceed.

[0058] The height-to-diameter ratio of each of the feed section 101, pyrolysis section 102, and discharge section 103 is (3-5):1, designed to optimize the flow of gases and solids within the tower and the efficiency of heat exchange. A higher height-to-diameter ratio of the tower body 1 promotes more uniform flow and better mixing, thereby improving the efficiency of the pyrolysis reaction.

[0059] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0061] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0062] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0063] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0064] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An SCR denitrification agent pyrolysis tower for preventing crystallization, characterized in that: include: A tower body, wherein the tower body has a feeding section, a pyrolysis section and a discharge section arranged in sequence from top to bottom, and the pyrolysis section has a mixed gas outlet; a reflux pipe, wherein a first end of the reflux pipe is in communication with the feed section, and a second end of the reflux pipe is in communication with the discharge section; a heat exchange ball is provided in the reflux pipe and circulates between the tower body and the reflux pipe; the reflux pipe has a hot flue gas inlet, which is used for hot flue gas to enter the reflux pipe and exchange heat with the heat exchange ball; and the heat exchange ball after heat exchange is used to provide heat to the pyrolysis section; A feed pipe is provided on the tower body and one end of the feed pipe extends into the pyrolysis section to transport ammonium carbamate powder into the pyrolysis section. The ammonium carbamate powder exchanges heat with the heat exchange balls in the pyrolysis section to undergo pyrolysis and generate a mixed gas of ammonia and carbon dioxide, which is discharged through the mixed gas outlet.

2. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 1, characterized in that: It includes a solid-gas separator, which has a solid-gas inlet, a solid outlet and a gas outlet. The solid-gas inlet is connected to the first end of the reflux pipe, and the solid outlet is connected to the feed section. The hot flue gas in the reflux pipe and the heat exchange ball enter the solid-gas separator through the solid-gas inlet for separation. The separated heat exchange ball enters the feed section through the solid outlet, and the separated hot flue gas is discharged through the gas outlet.

3. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 2, characterized in that: The diameter of the heat exchange ball is 0.3 mm to 2.0 mm, the temperature of the hot flue gas is 300° C. to 350° C., and the flow rate of the hot flue gas in the return pipe is 3 m / s to 6 m / s.

4. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 3, characterized in that: The heat exchange ball is conveyed in the reflux pipe for 5s to 10s, and the temperature of the heat exchange ball rises to 260°C to 300°C after heat exchange.

5. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 4, characterized in that: The hot flue gas in the reflux pipe enters the solid-gas separator at a flow rate of 25m / s to 40m / s, and the separated hot flue gas is discharged through the gas outlet after its temperature drops to 240°C to 280°C.

6. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 5, characterized in that: The contact time between the heat exchange ball and the ammonium carbamate powder in the pyrolysis section is 15s to 20s, and the temperature of the heat exchange ball after heat exchange in the pyrolysis section is 140°C to 180°C. A discharge pipe is provided between the discharge section and the second end of the reflux pipe, and the flow velocity of the heat exchange ball in the discharge pipe is controlled to be 0.02m / s to 0.05m / s.

7. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 1, characterized in that: A distribution plate is provided between the feed section and the pyrolysis section. The distribution plate is provided with a plurality of distribution holes arranged at intervals. The diameter of the distribution holes is 60 mm to 120 mm. The discharge pipe passes through the distribution plate and the outlet end of the discharge pipe is located in the pyrolysis section.

8. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 1, characterized in that: There are multiple discharge pipes, which are spaced apart on the tower body. The inner diameter of each discharge pipe is 50 mm to 80 mm.

9. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 1, characterized in that: An L-shaped partition is provided in the pyrolysis section, and the L-shaped partition includes a vertical first plate and a second plate. The first plate is provided above the mixed gas outlet and extends radially along the tower body. The second plate is spaced apart from the tower wall of the pyrolysis section and extends downward. A gas channel for the flow of the mixed gas is defined between the L-shaped partition and the tower wall of the pyrolysis section.

10. The SCR denitrification agent pyrolysis tower for preventing crystallization according to claim 1, characterized in that: The height ratio of the feed section, the pyrolysis section and the discharge section is (1-2):(3-5):(1-2), and the ratio of the height to diameter of each of the feed section, the pyrolysis section and the discharge section is (3-5):1.

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