Flue gas heating device and system

Abstract

This invention discloses a flue gas heating device, comprising: a heating furnace and a hot air mixing pipe. The heating furnace is disposed beside a flue, and the hot air mixing pipe is disposed inside the flue, with one end extending out of the flue and connected to the heating furnace. The portion of the hot air mixing pipe inside the flue has evenly distributed holes. This invention also discloses a flue gas heating system, comprising the above-mentioned flue gas heating device, including two heating furnaces disposed opposite each other on both sides of a flue, and a hot air mixing pipe running through both sides of the flue and connecting the two heating furnaces; a combustion gas source, a combustion-supporting fan, and supporting pipelines including a combustion-supporting air duct and a combustion gas duct; and a computer control system for real-time monitoring. This flue gas heating device and system can achieve effective combustion by rationally designing the ratio of combustible gas to air, transferring the heat generated by combustion to the flue gas undergoing SCR denitrification treatment within the flue, rapidly heating the flue gas, and simultaneously regenerating the catalyst.

Description

Technical Field

[0001] This application relates to the field of nitrogen oxide removal in flue gas treatment of highly polluting industries such as power, metallurgy, coking, and cement. Specifically, it relates to a flue gas heating device and system. It is particularly suitable for use in the denitrification method using selective catalytic reduction (SCR) technology. The heating system and device can heat the flue gas and regenerate the catalyst at the same time. Background Technology

[0002] Selective catalytic reduction (SCR) technology is currently the most widely used flue gas nitrogen oxide removal technology. This method boasts high denitrification efficiency, relatively low cost, and a wide range of applications, making it the mainstream technology for flue gas denitrification in domestic and international engineering projects. Among SCR denitrification solutions, the market application of medium- and low-temperature SCR processes is becoming increasingly widespread. The selection of medium- and low-temperature catalysts directly affects the denitrification effect. Currently, the lowest reaction temperature window for mature medium- and low-temperature catalysts on the market is 180℃. To meet the optimal reaction temperature requirements of medium- and low-temperature catalysts, it is necessary to heat the flue gas by raising the temperature when the flue gas temperature is too low.

[0003] Meanwhile, catalyst investment accounts for a significant proportion of the total system investment. After operating for a period of time, the activity and selectivity of the catalyst will significantly decrease compared to fresh catalyst, i.e., catalyst deactivation. The most common reason is that after adding catalyst, the amount of sulfur dioxide (SO2) in the flue gas increases dramatically under aerobic conditions, generating sulfur trioxide (SO3), which then reacts with excess ammonia to form ammonium bisulfate. Ammonium bisulfate is corrosive and sticky, which can cause pore blockage of the catalyst and reduce its catalytic effect. At this point, a regeneration process to restore catalyst activity must be arranged. Without changing the chemical properties of the catalyst, direct high-temperature activation can effectively achieve catalyst regeneration and extend its service life.

[0004] Therefore, there is a need to provide a heating device that addresses the shortcomings of the existing technology, so as to achieve the goal of heating the flue gas to a suitable denitrification temperature while simultaneously regenerating the catalyst. Summary of the Invention

[0005] The purpose of this invention is to provide a flue gas heating device and system that can achieve effective combustion by rationally designing the ratio of combustible gas to air, and transfer the heat generated by combustion to the flue gas to be treated by SCR denitrification in the flue, so as to quickly heat the flue gas and regenerate the catalyst at the same time.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A flue gas heating device includes: a heating furnace and a hot air mixing pipe, wherein the heating furnace is disposed beside a flue and is used to provide a heat source for heating flue gas by combustion; the hot air mixing pipe is disposed inside the flue, with one end extending out of the flue and connected to the heating furnace, and the portion of the hot air mixing pipe located inside the flue has evenly distributed holes.

[0008] In a preferred embodiment of the above-mentioned flue gas heating device, the heating furnace includes: a heating furnace body; the heating furnace body is a fire-resistant and heat-insulating sealed cavity; the heating furnace body is provided with a combustion burner and a hot air mixing pipe interface, the combustion burner being used to inject combustion gas and combustion air into the heating furnace body for combustion;

[0009] Preferably, the heating furnace body is provided with two combustion burners;

[0010] Preferably, the heating furnace body is provided with six hot air mixing pipe interfaces at the connection with the flue, arranged in two rows, three on top and three on the bottom, with the hot air mixing pipe interfaces in the two rows arranged evenly and alternately.

[0011] In a preferred embodiment of the flue gas heating device, the heating furnace body is a square structure formed by an outer shell and a refractory lining, including an open box and a cover that cooperates with it to form a sealed space.

[0012] In a preferred embodiment, the flue gas heating device described above has an observation window on the furnace body.

[0013] In a preferred embodiment of the above-mentioned flue gas heating device, the heating furnace body and the flue are connected by a connecting rectangular tube, which is sleeved outside the hot air mixing pipe.

[0014] In a preferred embodiment of the flue gas heating device, one heating furnace is arranged on each side of the flue; preferably, the two heating furnaces are symmetrically arranged on the left and right sides of the flue, and the hot air mixing pipe passes through the flue wall panels on both sides of the flue and connects the two heating furnaces.

[0015] In a preferred embodiment of the above-mentioned flue gas heating device, the hot air mixing pipe is a circular pipe with three or four rows of holes arranged parallel to the axial direction on its outer surface. The holes are evenly distributed along both the axial and circumferential directions of the hot air mixing pipe.

[0016] Preferably, the outer surface of the hot air mixing pipe is provided with four rows of holes in a manner parallel to the axial direction, the holes in adjacent rows are aligned in the circumferential direction, and the opening direction of each row of holes is located at the clock direction of 1:30, 4:30, 7:30 and 10:30 respectively when viewed from the circumferential direction of the hot air mixing pipe.

[0017] A flue gas heating system, comprising:

[0018] The aforementioned flue gas heating device includes two heating furnaces arranged opposite each other on both sides of the flue, and a hot air mixing pipe that runs through both sides of the flue and connects the two heating furnaces; each heating furnace is also equipped with a thermocouple for measuring the temperature inside the furnace chamber;

[0019] A combustion gas source is connected to the fuel inlet of the burner in the heating furnace;

[0020] A combustion-supporting blower is connected to the air inlet of the combustion burner in the heating furnace;

[0021] The supporting pipelines include a combustion air duct and a combustion gas pipeline. The combustion air duct and the combustion gas pipeline are respectively equipped with a regulating valve, a flow orifice plate, and a transmitter to monitor the flow rate of the fluid in the combustion air duct and the combustion gas pipeline. The combustion gas pipeline is equipped with a shut-off valve to shut off and open the combustion gas pipeline.

[0022] The computer control system includes a PLC and an HMI that are interconnected. The PLC is connected to thermocouples in the heating furnace, exhaust gas detection resistors in the flue, as well as shut-off valves, regulating valves, and transmitters. It receives and processes the transmitted information and then transmits it to the HMI. The HMI communicates with the PLC to monitor the operating status of the heating furnace and the real-time and historical information of temperature, pressure, and flow rate. It also remotely operates the shut-off valves, regulating valves, and combustion fan.

[0023] In a preferred embodiment of the flue gas heating system described above, the shut-off valve is a pneumatic shut-off valve, the regulating valve is a pneumatic regulating valve, and the flue gas heating system further includes a compressed air source and a compressed air pipeline. The compressed air source is connected to the pneumatic shut-off valve and the pneumatic regulating valve respectively through the compressed air pipeline to provide compressed air as power.

[0024] In a preferred embodiment of the flue gas heating system described above, the PLC is also connected to a differential pressure detection device installed in the catalyst layer of the SCR denitrification device, and receives the signal detected by the differential pressure detection device. If an abnormal signal is detected, the PLC controls the flue gas heating device to adjust the heating degree of the flue gas to be denitrified by SCR.

[0025] Compared with the closest existing technology, the technical solution provided by the present invention has the following beneficial effects:

[0026] 1) Currently, the lowest reaction temperature window of commercially available low-temperature catalysts is 165-180℃. In some flue gas systems, such temperatures cannot be provided, thus requiring the flue gas to be heated to meet system requirements. The heating device provided in this application can rapidly heat the flue gas, effectively solving the problem of excessively low flue gas temperatures preventing the optimal reaction temperature of the low-temperature catalyst from being met.

[0027] 2) Under aerobic conditions, sulfur dioxide in the flue gas of the SCR denitrification system leads to a significant increase in sulfur trioxide formation, which reacts with excess ammonia to form ammonium bisulfate. Ammonium bisulfate is corrosive, sticky, and can adsorb fly ash from the flue gas, easily causing catalyst pore blockage and reducing catalytic activity. To eliminate the impact of ammonium bisulfate on the catalyst bed, a high-temperature heating method can be used to achieve its chemical decomposition. The specific principle is as follows: When ammonium bisulfate is slightly heated (above 200℃), the following decomposition reaction occurs:

[0028] NH4HSO4=NH3↑+H2SO4

[0029] When the temperature is continuously raised to above 345℃, the following decomposition reaction occurs:

[0030] H₂SO₄ = H₂O + SO₃

[0031] During the operation of the denitrification reactor, for example, if the design value of the catalyst bed resistance is less than 1000 Pa, and the resistance of the catalyst bed is detected to exceed 80-90% of the design value (i.e., 800-900 Pa), the heating device provided in this application can be used to heat the flue gas in the flue without stopping the SCR denitrification system. After the hot flue gas passes through the catalyst bed, ammonium bisulfate can undergo the above-mentioned chemical reaction, thereby regenerating the catalyst and extending the replacement cycle of the entire catalyst bed. Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0033] Figure 1 This is a front view structural diagram of a heating furnace provided in an embodiment of the present invention;

[0034] Figure 2 for Figure 1 A top view of the structure of the intermediate heating furnace;

[0035] Figure 3 This is a front view structural diagram of a flue gas heating device provided in an embodiment of the present invention;

[0036] Figure 4 for Figure 3 A top view of the flue gas heating device;

[0037] Figure 5 This is a front view of the hot air mixing pipe;

[0038] Figure 6 for Figure 5 Cross-sectional view at section line AA;

[0039] Figure 7 This is a schematic diagram of the structure and flow of a flue gas heating system provided in an embodiment of the present invention.

[0040] In the diagram: 1. Heating furnace; 11. Heating furnace body; 12. Combustion burner; 13. Hot air mixing pipe interface; 14. Observation window; 15. Thermocouple; 2. Hot air mixing pipe; 21. Hole; 3. Connecting rectangular pipe; 4. Flue; 41. Flue wall panel; 5. Combustion air duct; 51. Combustion air fan; 6. Combustion gas pipeline; 61. Combustion gas source; 7. Compressed air pipeline; 71. Compressed air source; 81. Pressure transmitter; 82. Flow orifice plate; 83. Differential pressure transmitter; 91. Pneumatic quick-cut valve; 92. Pneumatic regulating valve. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0042] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0043] According to specific embodiments of the present invention, such as Figures 1 to 4 As shown, the present invention provides a flue gas heating device, which includes: a heating furnace 1 and a hot air mixing pipe 2. The components and their connections are described below.

[0044] A heating furnace 1 is located beside the flue and is used to provide a heat source for heating flue gas through combustion. The heating furnace 1 includes a furnace body 11, a burner 12, and a hot air mixing pipe interface 13. The furnace body 11 is a fire-resistant and heat-insulating sealed cavity. The furnace body 11 is equipped with the burner 12 and the hot air mixing pipe interface 13. The burner 12 is used to distribute the input combustion gas and combustion air and inject them into the furnace body 11 for combustion. The burner 12 has a fuel inlet, an air inlet, and an outlet. The fuel inlet is connected to the combustion gas pipeline 6 for inputting combustion gas, while the air inlet is connected to the combustion air duct 5 for inputting combustion air. In use, the combustion gas in the combustion gas pipeline 6 is sent to the burner 12 through the fuel inlet, while the combustion air in the combustion air duct 5 enters the burner 12 through the air inlet. The mixture of the two gases is injected into the furnace body 11 through the outlet to generate heat through combustion. The hot air mixing pipe interface 13 provided on the heating furnace body 11 is used to connect to the external hot air mixing pipe 2 to output the heat generated by combustion. In other words, the hot air mixing pipe interface 13 is reserved at the interface where the heating furnace body 11 connects to the flue.

[0045] Specifically, the heating furnace body is a square structure formed by an outer shell and a refractory lining. In a specific embodiment of the present invention, the outer shell of the heating furnace body 11 is made of carbon steel plate, and the lining is a complete furnace wall formed by using refractory bricks through a special masonry method. After the furnace is baked, a stable and solid masonry structure is formed. It includes an open box and a cover that cooperates with it to form a closed space. When working (heating), the box and the cover cooperate to form a closed space. When it is necessary to install and repair the burner and the internal refractory material, the cover can be opened to facilitate the staff to enter the box for operation. The combustion burner 12 can be connected to the furnace body 11 via a flange. Several combustion burners 12 can be installed on a single furnace to meet different needs and enhance the applicability of the furnace 1. In a specific embodiment of the invention, two combustion burners 12 are provided. Similarly, several hot air mixing pipe interfaces 13 can also be provided to meet different needs and enhance the applicability of the furnace 1. In a specific embodiment of the invention, six hot air mixing pipe interfaces 13 are provided, arranged in two rows, three on top and three on the bottom, with the two rows of hot air mixing pipe interfaces 13 staggered evenly. The furnace 1 provided in this application, including its combustion burners 12, furnace body 11, and related pipe and valve components, can be assembled in the factory and installed on-site without any secondary processing.

[0046] Preferably, an observation window 14 is designed on the heating furnace body 11 to observe the combustion situation on-site.

[0047] A hot air mixing pipe 2 is installed inside the flue. The hot air mixing pipe 2 has a hole 21. One end of the hot air mixing pipe 2 extends out of the flue and connects to the heating furnace 1. It is used to input the high-temperature flue gas generated by the combustion in the heating furnace 1 into the flue and mix it with the flue gas inside the flue, thereby transferring the heat of the high-temperature flue gas to the flue gas inside the flue. See [link to relevant documentation]. Figure 3 , Figure 5 and Figure 6 Specifically, one end of the hot air mixing pipe 2 is connected to the hot air mixing pipe interface 13, and the other end extends into the flue. The surface of the extended part is provided with evenly distributed holes 21. In this way, the high-temperature flue gas generated by the full combustion in the heating furnace 1 can enter the flue through the holes 21 and mix with the original flue gas in the flue (the flue gas that will undergo SCR denitrification), transferring the heat of the high-temperature flue gas to the original flue gas in the flue, thereby heating the original low-temperature flue gas in the flue. Preferably, the holes 21 are evenly distributed on the surface of the hot air mixing pipe 2; more preferably, the hot air mixing pipe 2 is a circular pipe, and three or four rows of holes are arranged on its outer surface in a manner parallel to the axial direction. The holes 21 are evenly distributed along the axial and circumferential directions of the hot air mixing pipe (see...). Figure 5 and Figure 6 In a specific embodiment of this application, the outer surface of the hot air mixing pipe 2 is uniformly provided with four rows of holes parallel to the axial direction. The holes in adjacent rows are aligned in the circumferential direction, and the opening directions of each row of holes, viewed from the cross-section, are respectively located at the clock directions of 1:30, 4:30, 7:30, and 10:30 (see...). Figure 6 This ensures that the hot air mixing pipe 2 maintains sufficient strength while achieving good air mixing effect. The hot air mixing pipe layout of this application is reasonable. At the same time, by opening evenly distributed holes 21 on the hot air mixing pipe, the hot air and flue gas can fully contact each other in all parts of the entire flue cross section. Without excessively increasing the flue gas resistance, the uniform heating requirements of the flue gas can be met to the maximum extent.

[0048] Preferably, the furnace body 11 and the flue are connected together by a connecting rectangular tube 3; specifically, the furnace body 11 and the flue wall panel 41 are connected together by a connecting rectangular tube 3, which is sleeved outside the hot air mixing pipe 2; in addition to facilitating the connection between the furnace body 11 and the flue, the connecting rectangular tube 3 also serves to seal and insulate.

[0049] Preferably, a heating furnace 1 is arranged on each side of the flue. Specifically, the two heating furnaces 1 are respectively located on the left and right sides of the flue wall panel 41 and connected by a hot air mixing pipe 1; the hot air mixing pipe 1 penetrates through both sides of the flue wall panel, and the portion of the hot air mixing pipe 2 located inside the flue has evenly distributed holes. The number of hot air mixing pipes 1 can be set as needed, and the present invention does not limit this.

[0050] In this application, the combustion burner 12 is preferably a low-NOx temperature-regulating gas burner, such as the BSTN1500 coke oven gas burner produced by Beijing Xingdaqi Thermal Control Equipment Co., Ltd. This burner is designed based on the principle of staged mixing combustion and has the advantages of large adjustment ratio, good flame stability and low NOx emissions; the combustion medium can be coke oven gas or blast furnace gas. The burner has the following functions, and its working status can be displayed in real time via computer: 1) Automatic ignition: The gas burner is equipped with a reliable built-in ignition device and a dedicated high-voltage ignition transformer, making high-reliability ignition possible; 2) Flame detection and flameout protection: The gas burner is equipped with an ultraviolet flame detection device or an ionization flame detection device, which, in conjunction with the burner controller, will realize flameout protection; 3) Multi-stage combustion technology: The application of an air guide allows for multi-stage mixing of gas and combustion air, forming a local gas-rich zone and oxygen-deficient combustion, greatly reducing NOx emissions; 4) Control of flue gas emission temperature: Under the given primary air supply, adjusting the secondary air intake can regulate the emission temperature of high-temperature flue gas, reducing it to a temperature close to the predetermined flue gas temperature, thereby preventing and avoiding overheating and overburning.

[0051] like Figure 7 As shown, the present invention also provides a flue gas heating system, including: the above-mentioned flue gas heating device, a combustion fan, a combustion gas source, matching pipes, valves, instruments, and a computer control system for real-time monitoring of the system's operating status.

[0052] Specifically, the aforementioned flue gas heating system includes:

[0053] The flue gas heating device includes two heating furnaces 1 arranged opposite each other on both sides of the flue, and a hot air mixing pipe 2 that runs through both sides of the flue and connects the two heating furnaces 1; the heating furnace 1 is also equipped with a thermocouple for measuring the temperature inside the furnace.

[0054] The combustion gas source 61 is connected to the fuel inlet of the combustion burner 12 of the heating furnace 1;

[0055] The combustion blower 51 is connected to the air inlet of the burner 12 of the heating furnace 1;

[0056] The supporting pipelines include combustion air duct 5 and combustion gas pipeline 6. The combustion air duct 5 and combustion gas pipeline 6 are respectively equipped with regulating valves and flow orifice plates 82, 83 and transmitters to monitor the flow rate of the fluid in the combustion air duct 5 and combustion gas pipeline 6. The combustion gas pipeline 6 is equipped with a shut-off valve to shut off and open the combustion gas pipeline 6.

[0057] The computer control system includes interconnected PLCs (Programmable Logic Controllers) and HMIs (Human Machine Interfaces); the PLCs are connected to thermocouples 15 inside the heating furnace 1 and exhaust gas detection resistors (RTNs) inside the flue. Figure 7 The system connects to devices such as valves (e.g., pneumatic quick-cut valve 91, pneumatic regulating valve 92), transmitters (e.g., pressure transmitter 81, differential pressure transmitter 83), etc., on the pipeline to receive and process the transmitted information, and then transmit it to the HMI. The HMI communicates with the PLC to monitor the operating status of various devices (e.g., combustion burners, valves, detection devices at various measuring points, combustion fans, etc.) and real-time and historical information such as temperature, pressure, and flow rate. At the same time, it can remotely operate the field equipment (e.g., combustion burners, valves, combustion fans, etc.).

[0058] In a preferred embodiment of the flue gas heating system described above, the shut-off valve is a pneumatic quick-cut valve 91, the regulating valve is a pneumatic regulating valve 92, two pneumatic quick-cut valves 91 are arranged adjacently on the main pipe of the combustion gas pipeline 6, one pneumatic quick-cut valve 91 is arranged on each branch pipe of the combustion gas pipeline 6, and one pneumatic regulating valve 92 is arranged on the main pipe of the combustion gas pipeline 6 and the combustion air duct 5. The flue gas heating system also includes a compressed air source 71 and a compressed air pipeline 7. The compressed air source 71 is connected to the pneumatic regulating valve 92 and the pneumatic quick-cut valve 91 through the compressed air pipeline 7 to provide compressed air as power.

[0059] In a preferred embodiment of the present invention, the computer control system adopts a German SIEMENS S7-300 series PLC control system. To establish the above-mentioned computer control system, a control cabinet is required. The PLC is installed inside the control cabinet, and an HMI is provided on the control cabinet. The HMI communicates with the PLC. The operator can monitor the operating status of each device in the heating system and various real-time and historical information such as temperature, pressure, and flow rate in real time through the HMI. At the same time, the operator can remotely operate the field equipment through the HMI.

[0060] In a preferred embodiment of the present invention, the entire heating system has two heating furnaces 1 symmetrically arranged on both sides of the flue 4, and a set of hot air mixing pipes 2 (a total of 6 pipes) runs through both sides of the flue 4 and connects the two heating furnaces 1; each heating furnace 1 is provided with two combustion burners 12. The combustion gas pipeline 6 includes a main pipe and four branch pipes respectively connected to the four combustion burners. The main pipe is provided with a manual ball valve, a blind valve, two adjacent pneumatic quick-cut valves 91, a pressure transmitter 81, a flow orifice plate 82, a differential pressure transmitter 83 and a pneumatic regulating valve 92 in sequence according to the fluid flow direction. Each of the four branch pipes is provided with a pneumatic quick-cut valve 91 and a manual ball valve is provided before and after each pneumatic quick-cut valve 91; the combustion air duct 5 also includes a main pipe and four branch pipes respectively connected to the four combustion burners 12. Each branch pipe is provided with a pneumatic regulating valve 92 and a manual regulating valve. For safety and automatic control considerations, in this specific embodiment, a pneumatic quick-cut valve 91 is used to open and close the combustion gas pipeline 6, a pneumatic regulating valve 92 is used to regulate the gas flow, and a pressure transmitter 81, a flow orifice plate 82, and a differential pressure transmitter 83 are used to measure the flow rate of the fluid in the pipeline. Each burner 12 is equipped with a local ignition control system for easy local ignition debugging and maintenance. Each heating furnace 1 is equipped with a thermocouple 15 to measure the furnace temperature, and a flue gas detection resistance thermometer is installed on the flue. The burner 12 uses direct open flame heating to heat the flue gas temperature to the working temperature, such as 250°C. The thermocouple 15 and the resistance thermometer both transmit the flue gas temperature detection value to the PLC in real time. After receiving the flue gas temperature detection value, the PLC compares it with the flue gas temperature setpoint, and then, based on the deviation between the flue gas temperature detection value and the flue gas temperature setpoint, continuously regulates the flow rate of combustion air and gas supplied to the heating furnace 2 according to a certain ratio. That is, the computer control system calculates and regulates the flow rate of gas and combustion air, and limits the air-fuel ratio.

[0061] In a preferred embodiment of the flue gas heating system described above, the PLC is also connected to a differential pressure detection device installed on the catalyst layer within the SCR denitrification unit. The PLC receives signals detected by the differential pressure detection device. If an abnormal signal is detected, i.e., the corresponding value exceeds a preset threshold, the PLC controls the flue gas heating device to adjust the heating level of the flue gas to be denitred by the SCR. If an abnormal signal is detected from the differential pressure detection device, it indicates increased resistance and severe blockage of the catalyst layer. In this case, the computer control system needs to control the flue gas heating device to heat the flue gas to a higher temperature, causing the ammonium bisulfate adhering to the catalyst to decompose, thereby enabling online catalyst regeneration. The differential pressure detection device is used to detect the resistance of the catalyst layer to the flue gas. It can be a differential pressure transmitter, or two pressure transmitters, respectively located upstream and downstream of the catalyst layer.

[0062] In summary, the main process flow for treating the flue gas undergoing SCR denitrification using the aforementioned flue gas heating system is as follows: Combustible gas supplied by the factory is mixed with air introduced by a combustion fan in a suitable ratio and then fully combusted in the heating furnace 1 through burner 12. The heat generated by combustion raises the temperature of the flue gas through evenly distributed holes in the hot air mixing pipe 2, thus achieving the purpose of flue gas heating. The combustion in the heating furnace 1 is monitored in real time by a complete computer control system, ensuring both the stability of the combustion system and meeting the heating capacity requirements of the heating device due to flue gas temperature changes.

[0063] In summary, the flue gas heating device and system provided by the present invention can rapidly raise the temperature of the flue gas in the denitrification system when the flue gas temperature is lower than the optimal reaction temperature of the catalyst to meet the system requirements; at the same time, it can regenerate the catalyst without affecting the normal operation of the denitrification system, i.e., online regeneration.

[0064] More specifically, the flue gas heating device and system provided by the present invention have the following advantages:

[0065] 1. The heating furnace adopts an integrated design, making installation convenient and quick;

[0066] 2. Employs low-NOx combustion technology, combined with a computer system to achieve precise control of the combustion system;

[0067] 3. The design of the hot air mixing pipeline ensures uniform heating;

[0068] 4. It can realize online regeneration of catalyst; it can meet the following target requirements for regenerated catalyst: (1) the physical blockage of the regenerated catalyst is less than 5%; (2) the physical and chemical properties are restored to the level of a new catalyst; (3) the mechanical strength can withstand transportation and the catalyst can reach the expected service life; (4) the performance of denitrification rate, SO2 / SO3 conversion rate, ammonia slip rate and pressure drop is guaranteed.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flue gas heating device, characterized in that, The flue gas heating device includes a heating furnace and a hot air mixing pipe. The heating furnace is located beside the flue and is used to provide a heat source for heating the flue gas through combustion. The hot air mixing pipe is located inside the flue, with one end extending out of the flue and connected to the heating furnace. The portion of the hot air mixing pipe located inside the flue has evenly distributed holes. The heating furnace includes: a heating furnace body; the heating furnace body is a fire-resistant and heat-insulating sealed cavity; the heating furnace body is provided with a combustion burner and a hot air mixing pipe interface, the combustion burner being used to inject combustion gas and combustion air into the heating furnace body for combustion; The heating furnace body is connected to the flue via a connecting rectangular tube, which is sleeved outside the hot air mixing pipe. One heating furnace is arranged on each side of the flue; the two heating furnaces are symmetrically arranged on the left and right sides of the flue, and the hot air mixing pipe passes through the flue wall panels on both sides of the flue and connects the two heating furnaces. The hot air mixing pipe is a circular pipe with four rows of holes arranged parallel to the axial direction on its outer surface. The holes are evenly distributed along the axial and circumferential directions of the hot air mixing pipe. The holes in adjacent rows are aligned in the circumferential direction, and the opening direction of each row of holes is located at the clock direction of 1:30, 4:30, 7:30, and 10:30 respectively when viewed from the circumferential direction of the hot air mixing pipe. The heating furnace body is provided with six hot air mixing pipe interfaces at the connection with the flue, arranged in two rows, three on top and three on the bottom, with the hot air mixing pipe interfaces in the upper and lower rows evenly staggered from side to side; the hot air mixing pipe interfaces are used to connect to external hot air mixing pipes; The furnace body is a square structure formed by an outer shell and a refractory lining, including an open box and a cover that cooperates with it to form a sealed space.

2. The flue gas heating device according to claim 1, characterized in that, The heating furnace body is equipped with two combustion burners.

3. The flue gas heating device according to claim 1 or 2, characterized in that, An observation window is provided on the heating furnace body.

4. A flue gas heating system, characterized in that, include: The flue gas heating device as described in any one of claims 1-3 includes two heating furnaces disposed opposite to each other on both sides of the flue, and a hot air mixing pipe that runs through both sides of the flue and connects the two heating furnaces; the heating furnace is further provided with a thermocouple for measuring the temperature inside the furnace chamber; A combustion gas source is connected to the fuel inlet of the burner in the heating furnace; A combustion-supporting blower is connected to the air inlet of the combustion burner in the heating furnace; The supporting pipelines include a combustion air duct and a combustion gas pipeline. The combustion air duct and the combustion gas pipeline are respectively equipped with a regulating valve, a flow orifice plate, and a transmitter to monitor the flow rate of the fluid in the combustion air duct and the combustion gas pipeline. The combustion gas pipeline is equipped with a shut-off valve to shut off and open the combustion gas pipeline. The computer control system includes a PLC and an HMI connected to each other. The PLC is connected to thermocouples in the heating furnace, exhaust gas detection resistors in the flue, as well as shut-off valves, regulating valves, and transmitters. It receives and processes the transmitted information and then transmits it to the HMI. The HMI communicates with the PLC to monitor the operating status of the heating furnace and the real-time and historical information of temperature, pressure, and flow rate. It also remotely operates the shut-off valves, regulating valves, and combustion fan. The shut-off valve is a pneumatic shut-off valve, the regulating valve is a pneumatic regulating valve, and the flue gas heating system also includes a compressed air source and a compressed air pipeline. The compressed air source is connected to the pneumatic shut-off valve and the pneumatic regulating valve respectively through the compressed air pipeline to provide compressed air as power. The heating furnace body is equipped with two combustion burners; The combustion gas pipeline includes a main pipe and four branch pipes connected to four combustion burners respectively. The combustion air duct also includes a main pipe and four branch pipes connected to four combustion burners respectively.

5. The flue gas heating system as described in claim 4, characterized in that, The PLC is also connected to a differential pressure detection device installed in the catalyst layer of the SCR denitrification unit. It receives the signal detected by the differential pressure detection device. If an abnormal signal is detected, it controls the flue gas heating device to adjust the heating degree of the flue gas to be denitrified by SCR.

Images