Pyrolysis device and method for reducing agent for denitration and application

Abstract

The invention discloses a pyrolysis device and method for a reducing agent for denitration and application, the pyrolysis device comprises a first shell, a feeding unit, a second shell and a reboiler, the feeding unit comprises a heat exchange chamber and a feeding pipe, the heat exchange chamber is connected with a superheated steam pipeline, and the bottom of the heat exchange chamber is open; a feeding pipe is arranged in the heat exchange chamber, and the top of the feeding pipe extends out of the heat exchange chamber to be connected with an under-pressure hot air pipeline and a feeder for conveying ammonium carbamate; the second shell is arranged at the upper part in the first shell, and an interlayer space is formed between the outer surface of the second shell and the inner surface of the first shell; the top of the second shell communicates with the bottom of the heat exchange chamber and the bottom of the feeding pipe; a plurality of baffle plates are arranged in the second shell; the reboiler is arranged in the first shell and located below the second shell. According to the pyrolysis device of the reducing agent for denitration, full pyrolysis of amino acid ammonium formate can be achieved, and the problems that ammonium carbamate is prone to caking when meeting water and the like, subsequent pipelines are blocked, and decomposition is not prone to occurring are solved.

Description

Technical Field

[0001] The present application belongs to the field of flue gas treatment technology, and in particular relates to a pyrolysis device, method and application of a reducing agent for denitrification. Background Art

[0002] NOx emissions from coal-fired power plants x It is NO in the atmosphere x Selective catalytic reduction (SCR) flue gas denitrification technology has become a major source of NOx in coal-fired units due to its mature and efficient characteristics. x Selective catalytic reduction of flue gas denitrification is a process in which ammonia, a reducing agent, is injected into the flue gas at a temperature of about 280℃ to 420℃ under the action of a catalyst to reduce NO x Reduction to N2 and H2O. As the largest consumable in the denitrification reaction, the choice of reducing agent is crucial. Currently, urea is the most commonly used reducing agent for flue gas denitrification. Urea is produced from ammonia primarily through high-temperature pyrolysis and low-temperature hydrolysis. Overall, urea-based ammonia production technology is relatively mature and highly safe. However, the process requires high temperatures, requiring energy-intensive equipment and processes to maintain the appropriate reaction temperature, which increases the energy cost of the entire denitrification system.

[0003] Related art uses ammonium carbamate as a reducing agent for denitration reactions. Compared to urea, ammonium carbamate is an intermediate product in urea production and has a better cost advantage. However, the inventors have discovered that using ammonium carbamate as a reducing agent for denitration reactions has the following drawbacks:

[0004] (1) It is easy to agglomerate in the presence of water, in an environment with a temperature close to or exceeding 25°C, in an environment with low temperature and high humidity, or in an environment with drastic temperature fluctuations, causing subsequent pipeline blockage and difficult decomposition engineering problems;

[0005] (2) There are problems such as low stability at room temperature and metal corrosion, and it cannot meet the requirements of existing urea storage, transportation and dissolution processes. Summary of the Invention

[0006] The present application aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] One purpose of the present application is to provide a pyrolysis device for a reducing agent for denitrification, which can achieve sufficient pyrolysis of amino acid ammonium formate through the synergistic effect of a feed unit, a baffle, a reboiler, etc. with a partition heat exchange function, improve the efficiency of ammonia production, and maximize the use of the ammonia generated by the pyrolysis, thereby avoiding the problem that ammonium formate is prone to agglomeration when it comes into contact with water, causing subsequent pipeline blockage and difficulty in decomposition.

[0008] Another object of the present application is to provide a method for pyrolyzing ammonium carbamate.

[0009] Another object of the present application is to provide a selective catalytic reduction denitrification system for flue gas in a coal-fired power plant.

[0010] Another object of the present application is to provide a selective catalytic reduction denitrification process for flue gas from a coal-fired power plant.

[0011] To achieve the above objectives, the first aspect of the present application provides a denitrification reducing agent pyrolysis device, comprising:

[0012] a first shell having a discharge port for discharging pyrolysis gas products;

[0013] A feeding unit comprising a heat exchange chamber and a feeding pipe, wherein the heat exchange chamber is connected to a superheated steam pipeline and has an open bottom; the feeding pipe is provided in the heat exchange chamber, the top of the feeding pipe extends out of the heat exchange chamber to connect to a pressurized hot air pipeline and a feeder for conveying ammonium carbamate;

[0014] a second shell, the second shell being arranged above the first shell, and the outer surface of the second shell forming a sandwich space with the inner surface of the first shell, the sandwich space being connected to the discharge port; the bottom of the second shell is open, and the top is connected to the bottom of the heat exchange chamber and the bottom of the feed pipe; a plurality of baffles are provided in the second shell;

[0015] a reboiler, the reboiler being disposed in the first shell and located below the second shell;

[0016] A water tank is disposed below the first shell and connected to the first shell.

[0017] In some embodiments, the discharge port is located above the second shell.

[0018] In some embodiments, the pressurized hot air pipeline is arranged perpendicular to the feed pipe.

[0019] In some embodiments, the plurality of baffles are alternately arranged at a certain interval from top to bottom on two opposite sides of the second shell.

[0020] In some embodiments, the plurality of baffles are arranged perpendicular to the feeding direction of the feeding pipe.

[0021] A second aspect of the present application provides a method for pyrolyzing ammonium carbamate, which is performed using the pyrolysis device for the denitrification reducing agent described in the present application, comprising:

[0022] The hot air with a first pressure from the pressurized hot air pipeline carries the ammonium carbamate powder from the feeder into the feed pipe, performs a heat exchange with the superheated steam from the superheated steam pipeline, and partially decomposes the ammonium carbamate powder into carbon dioxide and ammonia;

[0023] The remaining ammonium carbamate powder enters the second shell and directly contacts with the hot air and the superheated steam after the primary heat exchange to undergo secondary heat exchange and decompose into carbon dioxide and ammonia;

[0024] The superheated steam after the secondary heat exchange is converted into condensed water, and the condensed water forms a water seal under the heating effect of the reboiler.

[0025] In some embodiments, the time of the heat exchange is 3-5 s.

[0026] In some embodiments, the condensed water is heated to 60-80° C. by the reboiler.

[0027] In some embodiments, the secondary heat exchange decomposition time is 3.0-5.0 min.

[0028] In some embodiments, the temperature of the carbon dioxide and ammonia produced by the secondary heat exchange decomposition is 60-80°C.

[0029] In some embodiments, the first pressure is 0.05-0.2 MPa, and the temperature of the hot air is 50-60°C.

[0030] In some embodiments, the superheated steam from the superheated steam line has a temperature of 240-320° C. and a pressure of 0.05-0.1 MPa.

[0031] The third aspect of the present application proposes a selective catalytic reduction denitrification system for flue gas in a coal-fired power plant, comprising: a pyrolysis unit, a pressure stabilization unit, a drying unit, a filtration unit and a catalytic denitrification unit connected in sequence, wherein the pyrolysis unit is a pyrolysis device for the reducing agent for denitrification described in the present application.

[0032] In some embodiments, the drying unit comprises a drying bed; the drying bed comprises:

[0033] a third housing, wherein a plurality of buffer plates are provided in the third housing, the third housing having a desiccant inlet, a mixed gas inlet, and a dry mixed gas outlet; and the bottom of the third housing is open;

[0034] a fourth housing, the fourth housing being installed below the third housing and communicating with the third housing, the fourth housing having a desiccant outlet;

[0035] A material discharge unit is installed on the fourth shell; the material discharge unit includes a scraper, a material distribution plate and a transmission mechanism for driving the scraper and the material distribution plate to rotate; the scraper and the material distribution plate are installed at one end of the transmission mechanism, the scraper is located in the fourth shell, and the material distribution plate is located in the fourth shell, and a distance is left between the two; the scraper is located at the bottom of the second shell, and the scraper has a plurality of material holes; the material distribution plate is a U-shaped structure, and the edge is located on the periphery of the scraper edge.

[0036] In some embodiments, the dry mixed gas outlet, the desiccant inlet, the mixed gas inlet and the fourth shell are arranged in sequence from top to bottom.

[0037] In some embodiments, the desiccant outlet is provided at the bottom of the fourth shell and is a slide pipe structure.

[0038] In some embodiments, the drying unit also includes a regeneration bed; the regeneration bed includes a fifth shell, the fifth shell having a regeneration discharge port for discharging hot flue gas and desiccant, a regeneration feed port for entering the desiccant to be regenerated, and a hot flue gas inlet; the fifth shell is provided with a first cavity, an air distribution plate, and a second cavity that are interconnected from top to bottom; the size of the upper end of the first cavity is smaller than the size of the lower end, and the first cavity is connected to the regeneration discharge port and the regeneration feed port; the second cavity is connected to the hot flue gas inlet.

[0039] In some embodiments, the pressure stabilization unit includes a buffer tank.

[0040] In some embodiments, the filtration unit comprises a filter.

[0041] In some embodiments, the catalytic denitration unit includes an SCR reactor.

[0042] In some embodiments, the coal-fired power plant flue gas selective catalytic reduction denitrification system also includes a conveying unit, the conveying unit includes a raw material bin and the feeder, the raw material bin includes a first silo and a second silo connected in sequence, and the feeder is installed at the discharge port of the second silo.

[0043] The fourth aspect of the present application provides a coal-fired power plant flue gas selective catalytic reduction denitrification process, which is applied to the coal-fired power plant flue gas selective catalytic reduction denitrification system described in the present application, comprising:

[0044] Pyrolyzing the ammonium carbamate powder according to the method for pyrolyzing ammonium carbamate described in this application;

[0045] The mixture of ammonia, carbon dioxide and hot air from the pyrolysis unit is sent to the pressure stabilization unit for flow stabilization and preliminary cooling of water, followed by drying and filtration, and then undergoes selective catalytic reduction reaction with the hot flue gas from the coal-fired boiler to obtain denitrified hot flue gas.

[0046] In some embodiments, the process further comprises the step of regenerating and reusing the dried desiccant.

[0047] The denitrification reducing agent pyrolysis device described in this application can at least bring the following beneficial effects:

[0048] Through the synergistic effect of the feed unit, baffles, and reboiler with partition heat exchange function, the amino acid ammonium formate can be fully pyrolyzed, the ammonia production efficiency can be improved, and the ammonia generated by the pyrolysis can be utilized to the maximum extent, avoiding the problem of ammonium formate easily agglomerating when it comes into contact with water, causing subsequent pipeline blockage and difficulty in decomposition. Specifically:

[0049] (1) The heat exchange chamber and the feed pipe form a partition heat exchange structure, and the superheated steam in the heat exchange chamber can be used to heat the ammonium carbamate powder from the feed pipe to cause initial pyrolysis; the undecomposed ammonium carbamate powder enters the first shell and directly contacts with the hot air as the carrier gas of ammonium carbamate and the superheated steam cooled after heat exchange with the partition wall for pyrolysis. During this process, the multiple baffles arranged in the first shell can increase the residence time of the hot air in the first shell, making it easier for the ammonium carbamate powder to directly contact with the hot air and superheated steam for heat exchange, thereby improving the pyrolysis decomposition rate of ammonium carbamate.

[0050] (2) The condensed water from the superheated steam heat exchange process enters the bottom of the first shell and is heated by the reboiler to form a water seal, while reducing the solubility of ammonia and carbon dioxide in hot water, thereby maximizing the utilization of the mixed gas containing ammonia generated by the thermal decomposition of ammonium carbamate powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic structural diagram of a pyrolysis device for a reducing agent for denitrification shown in an exemplary embodiment of the present application.

[0052] Figure 2 It is a structural schematic diagram of a selective catalytic reduction denitrification system for flue gas in a coal-fired power plant shown in an exemplary embodiment of the present application.

[0053] Figure 3 yes Figure 2 FIG. 1 is a schematic structural diagram of a drying bed in a drying unit shown in an exemplary embodiment.

[0054] Figure 4 yes Figure 2 FIG. 1 is a schematic diagram of the structure of a regeneration bed in a drying unit shown in an exemplary embodiment.

[0055] Figure 5 The figure is a flow chart of a selective catalytic reduction denitrification process for flue gas in a coal-fired power plant, showing an exemplary embodiment of the present application.

[0056] Reference numerals:

[0057] 1-first shell; 2-heat exchange chamber; 3-feed pipe; 4-pressurized hot air pipeline; 5-second shell; 6-interlayer space; 7-baffle; 8-reboiler; 9-water tank; 10-discharge port; 100-pyrolysis unit; 200-pressure stabilizing unit; 201-drain valve; 300-drying unit; 301-drying bed; 3010-desiccant inlet; 3011-third shell; 3012-buffer plate; 3013-fourth shell; 3014-scraper; 3015-distributing plate; 3016-transmission mechanism; 3017 - material hole; 3018 - mixed gas inlet; 3019 - dry mixed gas outlet; 3020 - desiccant outlet; 302 - regeneration bed; 3021 - fifth shell; 3022 - regeneration outlet; 3023 - regeneration feed inlet; 3024 - hot flue gas inlet; 3025 - first cavity; 3026 - air distribution plate; 3027 - second cavity; 303 - separator; 400 - filtering unit; 500 - catalytic denitrification unit; 600 - conveying unit; 601 - first silo; 602 - second silo; 603 - feeder. DETAILED DESCRIPTION

[0058] The embodiments of the present application 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 application, but should not be understood as limiting the present application.

[0059] Throughout this application, the disclosure of numerical ranges includes disclosure of all values ​​within the entire range and further subdivided ranges, including the endpoints and subranges given within those ranges.

[0060] In this application, the raw materials, equipment, etc. involved, unless otherwise specified, are all raw materials and equipment that can be obtained through commercial channels or known methods; the methods involved, unless otherwise specified, are all conventional methods.

[0061] The term "and / or," when used in conjunction with a list of two or more items, means that any of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression "A and / or B" is intended to mean A or B or A and B, that is, only A, only B, or a combination of A and B.

[0062] In this application, normal temperature refers to 20-30°C.

[0063] Figure 1It is a schematic structural diagram of a pyrolysis device for a reducing agent for denitrification shown in an exemplary embodiment of the present application.

[0064] like Figure 1 As shown, the reducing agent pyrolysis device for denitrification according to an embodiment of the present application includes a first shell 1, a feed unit, a second shell 5, a reboiler 8, and a water tank 9. The first shell 1 has a discharge port 10 for discharging pyrolysis gaseous products. The feed unit includes a heat exchange chamber 2 and a feed pipe 3. The heat exchange chamber 2 is connected to a superheated steam pipeline and has an open bottom. The feed pipe 3 is provided in the heat exchange chamber 2. The top of the feed pipe 3 extends out of the heat exchange chamber 2 to connect to a pressurized hot air pipeline 4 and a feeder 603 for conveying ammonium carbamate. The second shell 5 is provided above the first shell 1, and its outer surface forms an interlayer space 6 with the inner surface of the first shell 1. The interlayer space 6 is connected to the discharge port 10. The second shell 5 is open at the bottom, and its top is connected to the bottom of the heat exchange chamber 2 and the bottom of the feed pipe 3. A plurality of baffles 7 are provided in the second shell 5. The reboiler 8 is provided in the first shell 1 and is located below the second shell 5. The water tank 9 is disposed below the first shell 1 and connected to the first shell 1 .

[0065] It can be understood that in the embodiments of the present application, the reducing agent for denitrification is amino acid amine formate, so its pyrolysis gas phase products are mainly ammonia and carbon dioxide.

[0066] The denitrification reducing agent pyrolysis device of the present application embodiment, through the synergistic effect of the feed unit, baffles, and reboiler with partition heat exchange function, can achieve full pyrolysis of amino acid ammonium formate, improve ammonia production efficiency, and maximize the utilization of the ammonia generated by the pyrolysis, thereby avoiding the problem of ammonium formate easily agglomerating when exposed to water, causing subsequent pipeline blockage and difficulty in decomposition. Specifically:

[0067] (1) The heat exchange chamber and the feed pipe form a partition heat exchange structure, and the superheated steam in the heat exchange chamber can be used to heat the ammonium carbamate powder from the feed pipe to cause initial pyrolysis; the undecomposed ammonium carbamate powder enters the first shell and directly contacts with the hot air as the carrier gas of ammonium carbamate and the superheated steam cooled after heat exchange with the partition wall for pyrolysis. During this process, the multiple baffles arranged in the first shell can increase the residence time of the hot air in the first shell, making it easier for the ammonium carbamate powder to directly contact with the hot air and superheated steam for heat exchange, thereby improving the pyrolysis decomposition rate of ammonium carbamate.

[0068] (2) The condensed water from the superheated steam heat exchange process enters the bottom of the first shell and is heated by the reboiler to form a water seal, while reducing the solubility of ammonia and carbon dioxide in hot water, thereby maximizing the utilization of the mixed gas containing ammonia generated by the thermal decomposition of ammonium carbamate powder.

[0069] In some embodiments, the discharge port 10 is located above the second shell 5 .

[0070] In some embodiments, the pressurized hot air pipeline 4 is arranged perpendicular to the feed pipe 3 .

[0071] In some embodiments, the plurality of baffles 7 are alternately arranged at regular intervals from top to bottom on opposite sides of the second shell 5. This arrangement ensures that the material (hot air, undecomposed ammonium carbamate, etc.) from the feed pipe and the superheated steam from the heat exchange chamber have as long a flow path as possible within the second shell, achieving as long a residence time as possible, increasing the direct contact time between the undecomposed ammonium carbamate and the hot air and superheated steam, and ultimately improving the pyrolysis efficiency.

[0072] As an optional example, all the baffles adjacent to the center end of the second shell extend at least to the position where the feed pipe drops vertically in the second shell, which is more conducive to extending the above-mentioned residence time and improving pyrolysis efficiency.

[0073] In some embodiments, the plurality of baffles 7 are arranged perpendicular to the feeding direction of the feeding pipe 3 .

[0074] It should be noted that in the embodiments of the present application, there is no limitation on the specific structure of the baffle, which may be a flat plate or a corrugated plate, etc.

[0075] As an optional example, the total number of baffles 7 is 3-8, including but not limited to 4, 5, 6 or 7, etc. When multiple baffles are arranged perpendicular to the feeding direction of the feeding pipe, each baffle can be regarded as a layer of baffles.

[0076] In addition, one or more superheated steam pipelines of the present application can be provided. When multiple superheated steam pipelines are provided, the multiple superheated steam pipelines can be evenly distributed around the heat exchange chamber.

[0077] In the embodiments of the present application, there is no limitation on the structure of the heat exchange chamber, which may be a hollow shell mounted outside the feed pipe or a pipe with one end closed.

[0078] The pyrolysis device for the denitrification reducing agent of the embodiment of the present application can be used to pyrolyze ammonium carbamate. The specific pyrolysis method includes the following steps:

[0079] S101. The hot air with a first pressure from the pressurized hot air pipeline carries the ammonium carbamate powder from the feeder 603 into the feed pipe 3, and performs a heat exchange with the superheated steam from the superheated steam pipeline. Part of the ammonium carbamate powder is thermally decomposed into carbon dioxide and ammonia.

[0080] In some embodiments, the ammonium carbamate powder is a dry ammonium carbamate powder at 20-30°C.

[0081] In some embodiments, the primary heat exchange time is 3-5 seconds, such as 4 seconds, etc. The primary heat exchange time can also be understood as the residence time of the ammonium carbamate powder carried by hot air into the feed pipe located in the heat exchange chamber and heated by superheated steam.

[0082] In some embodiments, the first pressure is 0.05-0.2 MPa, such as 0.1 MPa or 0.15 MPa.

[0083] In some embodiments, the temperature of the hot air is 50-60°C, such as 55°C.

[0084] Based on the first pressure and the temperature of the hot air, the hot air in the present application can be regarded as low-pressure hot air.

[0085] In some embodiments, the temperature of the superheated steam from the superheated steam line is 240-320°C, including but not limited to 270°C or 300°C.

[0086] In some embodiments, the pressure of the superheated steam from the superheated steam pipeline is 0.05-0.1 MPa, including but not limited to 0.07 MPa or 0.09 MPa.

[0087] S102, the remaining ammonium carbamate powder enters the second shell 5 and directly contacts with the hot air and the superheated steam obtained through the primary heat exchange to undergo secondary heat exchange and decompose into carbon dioxide and ammonia.

[0088] In some embodiments, the secondary heat exchange decomposition time is 3.0-5.0 min, such as 4 min.

[0089] In some embodiments, the temperature of the carbon dioxide and ammonia produced by the secondary heat exchange decomposition is 60-80°C, such as 65°C or 70°C.

[0090] S103 , the superheated steam after the secondary heat exchange is converted into condensed water, and the condensed water forms a water seal under the heating effect of the reboiler 8 .

[0091] In some embodiments, the condensed water is heated to 60-80° C., such as 65° C. or 70° C., by the action of the reboiler 8 .

[0092] In the embodiments of the present application, the condensed water not only acts as a water seal under the heating action of the reboiler, but also reduces the solubility of ammonia and carbon dioxide in hot water, thereby maximizing the utilization of the mixture of ammonia, carbon dioxide and hot air produced by the thermal decomposition of ammonium carbamate powder.

[0093] It should be noted that in the embodiments of the present application, the ammonia and carbon dioxide produced by the thermal decomposition of ammonium carbamate powder contain some water, and the mixed gas formed by them and the hot air has a temperature of 60-80°C.

[0094] In some embodiments, in the mixture of ammonia, carbon dioxide and hot air generated by the pyrolysis of ammonium carbamate powder, the volume proportion of hot air is 10-30%, including but not limited to 15%, 20% or 25%.

[0095] In some embodiments, the mixed gas of carbon dioxide, ammonia and hot air generated by pyrolysis is discharged from the first shell, that is, discharged from the pyrolysis device, through the interlayer space 6 and the discharge port 10.

[0096] As an optional example, a method for pyrolyzing ammonium carbamate using a pyrolysis device for a denitrification reducing agent according to an embodiment of the present application includes:

[0097] The ammonium carbamate powder carried by the low-pressure hot air undergoes initial thermal decomposition under the conditions of superheated steam partition heating. The ammonium carbamate powder resides in the superheated steam jacket partition for 3-5 seconds. Unreacted ammonium carbamate powder continues to exchange heat with the hot air and superheated steam in the first shell. The latent heat released during the condensation of the superheated steam in the first shell provides energy for the thermal decomposition of the ammonium carbamate powder, producing ammonia and carbon dioxide. The condensed water from the superheated steam heat exchange process enters the bottom of the first shell directly. The condensed water at the bottom of the first shell is heated to 60-80°C in the reboiler. The heated condensed water not only acts as a water seal in the first shell, but also reduces the solubility of ammonia and carbon dioxide in the hot water, maximizing the utilization of the mixed gas produced by the thermal decomposition of the ammonium carbamate powder. 3-8 layers of baffles are set in the first shell to ensure that the hot air and superheated steam are in full direct contact with the unreacted ammonium carbamate powder for heat exchange. The pyrolysis time of the ammonium carbamate powder in the first shell is controlled at 3.0-5.0 minutes. The mixture of ammonia and carbon dioxide (containing some water) with a temperature of 60-80°C and hot air is discharged from the first shell through the water seal at the bottom of the first shell through the interlayer space 6 and the discharge port 10 for subsequent processing, such as entering the pressure stabilizing unit later in this application.

[0098] Figure 2 It is a structural schematic diagram of a selective catalytic reduction denitrification system for flue gas in a coal-fired power plant shown in an exemplary embodiment of the present application.

[0099] like Figure 2 The selective catalytic reduction denitrification system for flue gas from a coal-fired power plant according to the embodiment of the present application includes: a pyrolysis unit 100, a voltage stabilization unit 200, a drying unit 300, a filtration unit 400, and a catalytic denitrification unit 500 connected in sequence. The pyrolysis unit 100 is a pyrolysis device for the reducing agent for denitrification according to the embodiment of the present application.

[0100] In some embodiments, the pressure stabilizing unit 200 includes a buffer tank.

[0101] In some embodiments, the buffer tank has a condensed water outlet.

[0102] In some embodiments, the pressure stabilizing unit 200 further includes a steam trap 201 , which is installed at the condensate outlet of the buffer tank.

[0103] In the embodiment of the present application, the operating temperature in the pressure stabilizing unit is room temperature, and the temperature of the mixed gas of ammonia, carbon dioxide (containing some water) and hot air from the pyrolysis unit is 60-80°C. After the mixed gas enters the pressure stabilizing unit, it cools down and produces condensed water, which can be discharged from the above-mentioned condensed water outlet equipped with a steam trap.

[0104] In some embodiments, the drying unit 300 includes a drying bed 301 .

[0105] In some other embodiments, the drying unit 300 further includes a regeneration bed 302 .

[0106] In the embodiments of the present application, the specific structure of the drying unit is not limited, and can be any structure known in the art that can be used for drying a mixture of ammonia and carbon dioxide (including some water) and hot air, or the structure designed by the present application including Figure 3-4 The structure including the drying bed and regeneration bed is shown.

[0107] Figure 3 yes Figure 2 FIG. 1 is a schematic structural diagram of a drying bed in a drying unit shown in an exemplary embodiment.

[0108] like Figure 3 As shown, the drying bed 301 includes a third shell 3011, a fourth shell 3013 and a material discharge unit.

[0109] The third shell 3011 is provided with a plurality of buffer plates 3012. The third shell 3011 has a desiccant inlet 3010, a mixed gas inlet 3018, and a dry mixed gas outlet 3019. The bottom of the third shell 3011 is open. The fourth shell 3013 is installed below the third shell 3011 and is connected to the third shell 3011. The fourth shell 3013 has a desiccant outlet 3020. The unloading unit is installed on the fourth shell 3013. The unloading unit includes a scraper 3014, a distribution plate 3015, and a material distribution plate 3016. and a transmission mechanism 3016 for driving the scraper 3014 and the distribution plate 3015 to rotate; the scraper 3014 and the distribution plate 3015 are installed at one end of the transmission mechanism 3016, the scraper 3014 is located in the fourth shell 3013, and the distribution plate 3015 is located therebetween, with a distance left between them; the scraper 3014 is located at the bottom of the second shell 5, and the scraper 3014 has a plurality of material holes 3017; the distribution plate 3015 is a U-shaped structure, and the edge is located outside the edge of the scraper 3014.

[0110] It can be understood that a gap is formed between the edge of the distribution plate 3015 and the edge of the scraper 3014 for the movement of the desiccant.

[0111] In some embodiments, the dry mixed gas outlet 3019 , the desiccant inlet 3010 , the mixed gas inlet 3018 and the fourth shell 3013 are arranged in sequence from top to bottom.

[0112] As an optional example, the dry mixed gas outlet 3019 is arranged at the top of the third shell 3011, the desiccant inlet 3010 is arranged at the upper end of the third shell 3011, and the mixed gas inlet 3018 is arranged at a position at the lower end of the third shell 3011 adjacent to the fourth shell 3013, and the fourth shell 3013 is arranged at the lower end of the third shell 3011 and extends to below the bottom of the third shell 3011.

[0113] In some embodiments, the desiccant outlet 3020 is provided at the bottom of the fourth shell and is a slide pipe structure.

[0114] In other embodiments, the desiccant outlet 3020 is provided at the bottom of the fourth housing, and a return device is provided at the desiccant outlet 3020. For example, the return device includes but is not limited to an L-shaped valve, a U-shaped valve, and a J-shaped valve.

[0115] In some embodiments, the desiccant used in the drying bed 301 includes but is not limited to at least one of silica gel, montmorillonite, calcium chloride, and the like.

[0116] In some embodiments, the transmission mechanism 3016 includes a motor and a rotating shaft driven by the motor. The motor is installed at the bottom of the fourth shell 3013. The scraper 3014 and the distribution plate 3015 are installed at one end of the rotating shaft extending into the fourth shell.

[0117] In some embodiments, the distribution plate 3015 is a cylindrical groove, preferably a cylindrical groove with multiple through holes on the side walls and the bottom.

[0118] During use, the transmission mechanism 3016 drives the scraper 3014 and the distribution plate 3015 to rotate. Under the action of the rotating scraper 3014 and the distribution plate 3015, the dried desiccant flows out from the multiple material holes provided on the scraper 3014 from top to bottom, and then enters the distribution plate 2015 to evenly distribute the material, and then gradually enters the regeneration bed through the gap between the distribution plate 3015 and the edge of the scraper 3014 or the gap and the multiple through holes provided on the distribution plate 3015 through the chute structure or the return device.

[0119] Figure 4 yes Figure 2 FIG. 1 is a schematic diagram of the structure of a regeneration bed in a drying unit shown in an exemplary embodiment.

[0120] like Figure 4 As shown, the regeneration bed 302 includes a fifth shell 3021, and the fifth shell 3021 has a regeneration discharge port 3022 for discharging hot flue gas and desiccant, a regeneration feed port 3023 for entering the desiccant to be regenerated, and a hot flue gas inlet 3024; the fifth shell 3021 is provided with a first cavity 3025, an air distribution plate 3026 and a second cavity 3027 which are interconnected from top to bottom; the size of the upper end of the first cavity 3025 is smaller than the size of the lower end, and the first cavity 3025 is connected to the regeneration discharge port 3022 and the regeneration feed port 3023; the second cavity 3027 is connected to the hot flue gas inlet 3024.

[0121] In some embodiments, the fifth shell 3021 is made of refractory material, such as high-alumina bricks or amorphous refractory castables.

[0122] In some embodiments, the first cavity 3025 and the second cavity 3027 form a stepped hole structure.

[0123] In some embodiments, the first cavity 3025 is truncated cone-shaped.

[0124] In the embodiment of the present application, the size of the upper end of the first cavity 3025 is smaller than that of the lower end, that is, the first cavity 3025 has a structure that is thin at the top and thick at the bottom. This setting is mainly considered to consider the change in the operating air velocity in the bed caused by the change in the hot flue gas temperature.

[0125] Exemplarily, the operating air velocity in the regeneration bed is controlled at 3-5 m / s, and the hot flue gas enters the first cavity 3025 through the second cavity 3027 and the air distribution plate 3026.

[0126] For example, the opening rate of the air distribution plate 3026 is 3-5%, and the air velocity of the small holes is 30-40 m / s.

[0127] In some embodiments, the drying unit further includes a separator 303, the inlet of the separator 303 is connected to the regeneration discharge port 3022, the solid phase outlet of the separator 303 is connected to the desiccant inlet 3010, and the gas phase outlet of the separator 303 is used to discharge the cold and hot flue gases from the regeneration bed.

[0128] In some embodiments, the filtration unit 400 includes a filter.

[0129] As an optional example, the filter mainly adopts filter materials such as membrane filter cartridge and polyester filter cartridge.

[0130] In some embodiments, the filter has multiple layers of filter material built in, and the mixed gas is filtered through the multiple layers of filter material in sequence.

[0131] In some embodiments, the catalytic denitration unit 500 includes an SCR reactor (ie, a selective catalytic denitration reactor).

[0132] In some embodiments, the catalytic denitration unit has 2-4 catalyst beds built in.

[0133] In some embodiments, the aspect ratio of the SCR reactor is controlled to be 5:1 to 8:1, including but not limited to 6:1 or 7:1.

[0134] In the embodiments of the present application, the specific structural designs of the separator, filter, and SCR reactor are prior art and will not be described in detail here.

[0135] In some embodiments, the catalytic denitration unit 500 uses a vanadium-titanium catalyst with TiO2 as a main carrier, V2O5 as a main active component, and WO3 and MoO3 as auxiliary components for anti-oxidation and anti-poisoning.

[0136] As an optional example, the vanadium-titanium catalyst used in the catalytic denitration unit 500 includes an active component, V2O5, having a mass content of 0.3-1.5%, and auxiliary components, WO3 and / or MoO3, having a mass content of 3.0-5.0%. When the auxiliary components include both WO3 and MoO3, the mass ratio of WO3 to MoO3 is 1:(1.0-2.0).

[0137] For example, in the vanadium-titanium catalyst used in the catalytic denitration unit 500, the mass content of the active component V2O5 includes, but is not limited to, 0.5% or 1%, and the mass content of the auxiliary components WO3 and / or MoO3 includes, but is not limited to, 3.5% or 4%. When the auxiliary components include both WO3 and MoO3, the mass ratio of WO3 to MoO3 includes, but is not limited to, 1:1.25, 1:5, or 1:1.75.

[0138] In some embodiments, the selective catalytic reduction and denitrification system for flue gas in a coal-fired power plant further includes a conveying unit 600, which includes a raw material bin and the feeder 603. The raw material bin includes a first bin 601 and a second bin 602 that are connected in sequence, and the feeder 603 is installed at the discharge port of the second bin 602.

[0139] In the embodiment of the present application, the raw material bin is mainly used to store dry ammonium carbamate powder, and a hollow wall layer is provided on the inner wall of the raw material bin for independently storing a desiccant (the desiccant here can be the same as the desiccant involved in the above-mentioned drying unit) to ensure that the raw materials are always kept dry in the bin.

[0140] Exemplarily, the first silo 601 is located above the second silo 602 .

[0141] In an embodiment of the present application, the ammonium carbamate powder stored in the first silo 601 is fed into the second silo 602 according to the material level feedback of the second silo 602, and the second silo 602 controls the amount of ammonium carbamate powder entering the feed pipe through the speed control of the feeder 603.

[0142] The process for performing denitrification using the selective catalytic reduction denitrification system for flue gas from a coal-fired power plant according to the embodiment of the present application mainly includes the following steps:

[0143] Pyrolyzing the ammonium carbamate powder according to the method for pyrolyzing ammonium carbamate described in this application;

[0144] The mixed gas of ammonia, carbon dioxide and hot air from the pyrolysis unit 100 is sent to the pressure stabilizing unit 200 for flow stabilization and preliminary cooling and water discharge, and then dried and filtered, and then subjected to selective catalytic reduction reaction with the hot flue gas from the coal-fired boiler to obtain denitrified hot flue gas.

[0145] In some embodiments, the process further comprises the step of regenerating and reusing the dried desiccant.

[0146] More specifically, the conveying unit 600 conveys the dry ammonium carbamate powder with a temperature controlled at 20-30°C into the feed pipe through the first silo 601, the second silo 602 and the feed valve 603, and is simultaneously conveyed to the pyrolysis unit 100 by pressurized hot air (50-60°C); the ammonium carbamate powder enters the first shell under the influence of the pressurized hot air, and the superheated steam (temperature 240-320°C, pressure 0.05-0.1MPa) heats the ammonium carbamate powder carried by the pressurized hot air through the partition heat exchange method before entering the first shell (that is, the superheated steam in the heat exchange chamber heats the ammonium carbamate powder carried by the pressurized air in the feed pipe), causing the ammonium carbamate powder to be initially pyrolyzed, and then the unpyrolyzed ammonium carbamate powder is thermally decomposed in the first shell under the combined action of the superheated steam and hot air to generate ammonia and carbon dioxide; The ammonia and carbon dioxide (containing some water) generated by the thermal decomposition of ammonium formate powder enter the pressure stabilizing unit 200 together with the hot air for flow stabilization and preliminary cooling and water removal. The pressure stabilization can ensure that the pressure of the mixed gas is in an appropriate range to avoid the influence of pressure fluctuation on subsequent operations; the mixed gas after pressure stabilization and preliminary cooling then enters the drying unit 300 to contact with the desiccant for drying the mixed gas, thereby reducing the adverse effect of moisture in the mixed gas on selective catalytic reduction (SCR) denitrification; the dried mixed gas passes through the filtering unit 400 to remove solid impurities such as desiccant powder mixed in the mixed gas to avoid these solid impurities affecting the flue gas denitrification process; the filtered mixed gas enters the catalytic denitrification unit 500 and undergoes selective catalytic reduction (SCR) denitrification with the hot flue gas of the coal-fired boiler, and then enters the subsequent flue gas waste heat recovery system (such as Figure 5 shown).

[0147] As an alternative example, Figure 2 and Figure 5 As shown, the denitrification process of the coal-fired power plant flue gas selective catalytic reduction denitrification system according to the embodiment of the present application includes:

[0148] The conveying unit 600 conveys the dry ammonium carbamate powder controlled at 20-30°C into the feed pipe through the first silo 601, the second silo 602 and the feed valve 603, and is simultaneously conveyed to the pyrolysis unit 100 by pressurized hot air (50-60°C).

[0149] The ammonium carbamate powder carried by the pressurized hot air undergoes initial thermal decomposition under the conditions of superheated steam partition heating. The ammonium carbamate powder resides in the superheated steam jacket partition for 3-5 seconds. Unreacted ammonium carbamate powder continues to exchange heat with the hot air and superheated steam in the first shell. The latent heat released during the condensation of the superheated steam in the first shell provides energy for the thermal decomposition of the ammonium carbamate powder, producing ammonia and carbon dioxide. The condensed water from the superheated steam heat exchange process enters the bottom of the first shell directly. The condensed water at the bottom of the first shell is heated to 60-80°C in the reboiler. The heated condensed water not only acts as a water seal in the first shell, but also reduces the solubility of ammonia and carbon dioxide in the hot water, maximizing the utilization of the mixed gas produced by the thermal decomposition of the ammonium carbamate powder. 3-8 layers of baffles are set in the first shell to ensure that the hot air and superheated steam are in sufficient direct contact and heat exchange with the unreacted ammonium carbamate powder. The thermal decomposition time of the ammonium carbamate powder in the first shell is controlled at 3.0-5.0 minutes. The mixture of ammonia and carbon dioxide (containing some water) with a temperature of 60-80°C and hot air is discharged from the first shell through the water seal at the bottom of the first shell through the interlayer space 6 and the discharge port 10 and enters the pressure stabilizing unit 200.

[0150] The mixed gas at 60-80°C from the pyrolysis unit stays in the pressure stabilizing unit for 3-5 minutes. After cooling to 20-30°C in the pressure stabilizing unit, the mixed gas enters the drying unit 300. The condensed water generated by the cooling of the mixed gas is discharged through the steam trap below the pressure stabilizing unit 200.

[0151] The mixed gas from the pressure stabilizing unit 200 enters the drying unit 300 for drying. The mixed gas drying process mainly takes place between the drying bed and the regeneration bed. The desiccant particles (such as silica gel, montmorillonite, calcium chloride, etc.) in the drying bed flow downward along the axial direction of the top of the drying bed from top to bottom, and perform a countercurrent drying and fluidization operation with the mixed gas from the bottom of the drying bed. The residence time of the mixed gas in the drying bed is controlled to be 30-60 seconds. The temperature of the desiccant in the drying bed gradually decreases along the axial direction from top to bottom (from 110-130℃ to 20-25℃), and the temperature of the mixed gas gradually increases along the axial direction from bottom to top (from 20-30℃ to 105-120℃). The desiccant particles in the drying bed return the desiccant that has dried the mixed gas (i.e., the desiccant to be regenerated) to the regeneration bed through a return device (such as an L-valve, U-valve, and J-shaped valve, etc.) or a chute. The regeneration process of the desiccant particles to be regenerated mainly relies on the hot flue gas at 150-180°C from the exhaust duct of the coal-fired unit to provide a heat source for the regeneration of the desiccant particles to be regenerated. The residence time of the desiccant particles to be regenerated in the regeneration bed is 20-30s. The desiccant to be regenerated is dried during the lifting process of the hot flue gas in the regeneration bed. The hot flue gas carries the regenerated desiccant and is separated in the separator and then enters the top of the drying bed. The hot flue gas carrying water vapor is cooled to 110-130°C and connected to the exhaust system of the coal-fired boiler.

[0152] The dried mixed gas enters the catalytic denitration unit 500 after removing the desiccant particles that may be carried by it in the filter unit 400. The filter unit 400 has multiple layers of filter materials built in, and the mixed gas is filtered through the multiple layers of filter materials in sequence.

[0153] Under the action of a denitration catalyst (e.g., a vanadium-titanium catalyst with TiO2 as the main carrier, V2O5 as the main active ingredient, and WO3 and MoO3 as auxiliary antioxidants and anti-poisoning ingredients) and the presence of oxygen, NH3 in the mixed gas from the filtration unit 400 preferentially undergoes a reduction reaction with NOx in the hot flue gas in the flue gas duct of the coal-fired unit, rather than undergoing an oxidation reaction with oxygen in the flue gas. The catalytic denitration reaction temperature is controlled at 300-400°C. The catalytic denitration unit is equipped with 2-4 layers of catalyst beds, the aspect ratio of the selective catalytic denitration reactor is controlled at 5:1-8:1, the flue gas flow rate is controlled at 10-12 m / s, and the residence time in the denitration reactor is 1.0-1.5 s, which can achieve high-efficiency denitration (NOx emissions <50 mg / Nm 3 ) and control operating costs.

[0154] In summary, the process of denitrification using the selective catalytic reduction (SCR) denitrification system for flue gas from a coal-fired power plant according to the embodiment of the present application uses ammonium carbamate as the main denitrification agent component (specifically a reducing agent). From a process perspective, it not only solves the problem of low stability and easy agglomeration of ammonium carbamate at room temperature, but also effectively reduces the adverse effects of ammonia gas produced by ammonium carbamate during pyrolysis, dehydration, and filtration, which carries moisture and dust on the catalyst denitrification process in the subsequent selective catalytic reduction reactor. Compared with urea ammonia production, the efficiency of ammonium carbamate to produce ammonia using hot air and superheated steam pyrolysis is higher than that of urea ammonia production. Under full load conditions, the ammonia production efficiency of ammonium carbamate in the present application is increased by 4.8-23.2% compared with urea, an average increase of more than 14%, and the energy consumption of pyrolysis ammonia production is reduced by about 50-55%. The selective catalytic reduction denitrification system and process for flue gas from a coal-fired power plant according to the embodiment of the present application have important theoretical and practical significance for achieving economic improvement, energy consumption reduction, and comprehensive cost reduction in denitrification of coal-fired power plants.

[0155] In the description of the present application, 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 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 application and simplifying the description, and do not indicate or imply 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 a limitation on the present application.

[0156] 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 of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0157] In this application, 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 this application based on specific circumstances.

[0158] In this application, 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 the first and second features are in indirect contact through an intermediate medium. 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.

[0159] In this application, 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 application. In this specification, the schematic representations 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.

[0160] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A pyrolysis device for a reducing agent for denitrification, characterized in that: include: a first shell having a discharge port for discharging pyrolysis gas products; A feeding unit comprising a heat exchange chamber and a feeding pipe, wherein the heat exchange chamber is connected to a superheated steam pipeline and has an open bottom; the feeding pipe is provided in the heat exchange chamber, the top of the feeding pipe extends out of the heat exchange chamber to connect to a pressurized hot air pipeline and a feeder for conveying ammonium carbamate; a second shell, the second shell being arranged above the first shell, and the outer surface of the second shell forming a sandwich space with the inner surface of the first shell, the sandwich space being connected to the discharge port; the bottom of the second shell is open, and the top is connected to the bottom of the heat exchange chamber and the bottom of the feed pipe; a plurality of baffles are provided in the second shell; a reboiler, the reboiler being disposed in the first shell and located below the second shell; A water tank is disposed below the first shell and connected to the first shell.

2. The pyrolysis device according to claim 1, characterized in that The pressurized hot air pipeline is arranged perpendicular to the feed pipe.

3. The pyrolysis device according to claim 1, characterized in that The plurality of baffles are alternately arranged at opposite sides of the second shell at a certain interval from top to bottom.

4. The pyrolysis device according to claim 1, characterized in that The multiple baffles are all arranged perpendicular to the feeding direction of the feeding pipe; And / or, the discharge port is arranged above the second shell.

5. A method for pyrolyzing ammonium carbamate using the pyrolysis device according to any one of claims 1 to 4, characterized in that: include: The hot air with a first pressure from the pressurized hot air pipeline carries the ammonium carbamate powder from the feeder into the feed pipe, performs a heat exchange with the superheated steam from the superheated steam pipeline, and partially decomposes the ammonium carbamate powder into carbon dioxide and ammonia; The remaining ammonium carbamate powder enters the second shell and directly contacts with the hot air and the superheated steam after the primary heat exchange to undergo secondary heat exchange and decompose into carbon dioxide and ammonia; The superheated steam after the secondary heat exchange is converted into condensed water, and the condensed water forms a water seal under the heating effect of the reboiler.

6. The method according to claim 5, characterized in that The time of the primary heat exchange is 3-5s; and / or, the condensed water is heated to 60-80° C. under the action of the reboiler; And / or, the secondary heat exchange decomposition time is 3.0-5.0 min; And / or, the temperature of the carbon dioxide and ammonia produced by the secondary heat exchange decomposition is 60-80°C; and / or, the first pressure is 0.05-0.2 MPa, and the temperature of the hot air is 50-60° C.; And / or, the temperature of the superheated steam from the superheated steam pipeline is 240-320° C., and the pressure is 0.05-0.1 MPa.

7. A coal-fired power plant flue gas selective catalytic reduction denitrification system, characterized in that: include: A pyrolysis unit, a pressure stabilization unit, a drying unit, a filtering unit and a catalytic denitration unit are connected in sequence, and the pyrolysis unit is the pyrolysis device according to any one of claims 1 to 4.

8. The selective catalytic reduction denitrification system for flue gas in a coal-fired power plant according to claim 7, characterized in that: The drying unit includes a drying bed; the drying bed includes: a third housing, wherein a plurality of buffer plates are provided in the third housing, the third housing having a desiccant inlet, a mixed gas inlet, and a dry mixed gas outlet; and the bottom of the third housing is open; a fourth housing, the fourth housing being installed below the third housing and communicating with the third housing, the fourth housing having a desiccant outlet; A material discharge unit is mounted on the fourth housing; the material discharge unit includes a scraper, a material distribution plate, and a transmission mechanism for driving the scraper and the material distribution plate to rotate; the scraper and the material distribution plate are mounted on one end of the transmission mechanism, the scraper and the material distribution plate are both located within the fourth housing, with a gap between them; the scraper is located at the bottom of the second housing and has a plurality of material holes; the material distribution plate is a U-shaped structure, with its edge located outside the edge of the scraper; And / or, the pressure stabilizing unit includes a buffer tank; and / or, the filtration unit comprises a filter; and / or, the catalytic denitration unit comprises an SCR reactor; And / or, the coal-fired power plant flue gas selective catalytic reduction denitrification system also includes a conveying unit, the conveying unit includes a raw material bin and the feeder, the raw material bin includes a first silo and a second silo connected in sequence, and the feeder is installed at the discharge port of the second silo.

9. The selective catalytic reduction denitrification system for flue gas in a coal-fired power plant according to claim 8, characterized in that: The dry mixed gas outlet, the desiccant inlet, the mixed gas inlet and the fourth shell are arranged in sequence from top to bottom; And / or, the desiccant outlet is provided at the bottom of the fourth shell and is a slide pipe structure; And / or, the drying unit also includes a regeneration bed; the regeneration bed includes a fifth shell, the fifth shell has a regeneration discharge port for discharging hot flue gas and desiccant, a regeneration feed port for entering the desiccant to be regenerated, and a hot flue gas inlet; the fifth shell is provided with a first cavity, an air distribution plate and a second cavity that are interconnected from top to bottom; the size of the upper end of the first cavity is smaller than the size of the lower end, and the first cavity is connected to the regeneration discharge port and the regeneration feed port; the second cavity is connected to the hot flue gas inlet.

10. A selective catalytic reduction denitrification process for flue gas from a coal-fired power plant, applied to the selective catalytic reduction denitrification system for flue gas from a coal-fired power plant according to any one of claims 7 to 9, characterized in that: include: Pyrolyzing the ammonium carbamate powder according to the method of claim 5 or 6; The mixture of ammonia, carbon dioxide and hot air from the pyrolysis unit is sent to the pressure stabilization unit for flow stabilization and preliminary cooling of water, followed by drying and filtration, and then undergoes selective catalytic reduction reaction with hot flue gas from the coal-fired boiler to obtain denitrified hot flue gas; Preferably, the process further comprises the step of regenerating and reusing the dried desiccant.

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