CN110748908A

CN110748908A - Flue gas heating device and system

Info

Publication number: CN110748908A
Application number: CN201911151451.4A
Authority: CN
Inventors: 刘晓敏; 刘国锋; 林学良; 李转丽
Original assignee: Beijing ZHTD Environmental Protection Technology Co Ltd
Current assignee: Beijing ZHTD Environmental Protection Technology Co Ltd
Priority date: 2019-11-21
Filing date: 2019-11-21
Publication date: 2020-02-04

Abstract

The invention discloses a flue gas heating device, comprising: the heating furnace is arranged beside the flue, the hot air mixing pipe is arranged in the flue, one end of the hot air mixing pipe extends out of the flue and is connected with the heating furnace, and holes which are uniformly distributed are formed in the part, located in the flue, of the hot air mixing pipe. The invention also discloses a flue gas heating system which comprises the flue gas heating device, two heating furnaces and a hot air mixing pipe, wherein the two heating furnaces are oppositely arranged on two sides of the flue, and the hot air mixing pipe penetrates through two sides of the flue and is connected with the two heating furnaces; the combustion gas source and the combustion-supporting fan are matched, and the matched pipeline comprises a combustion-supporting air pipe and a combustion gas pipeline; and a computer control system for real-time monitoring. This flue gas heating device and system can realize effective burning through the ratio of rational design combustible gas and air, and the heat transfer that will burn the production gives the flue gas heating fast in waiting to carry out the flue gas that SCR denitration was handled in the flue, realizes catalyst regeneration simultaneously.

Description

Flue gas heating device and system

Technical Field

The application relates to the field of removing nitrogen oxides in flue gas treatment in high pollution industries such as electric power, metallurgy, coking, cement and the like, in particular to a flue gas heating device and a system; the heating system and the device are particularly suitable for heating flue gas and regenerating a catalyst when a Selective Catalytic Reduction (SCR) technology denitration method is adopted.

Background

The Selective Catalytic Reduction (SCR) technology is the most widely used flue gas nitrogen oxide removal technology at present. The method has the advantages of high denitration efficiency, relatively low price and wide application range, and is applied to domestic and foreign projects to become a mainstream technology for flue gas denitration. In the SCR denitration scheme, the market application of the medium-low temperature SCR denitration technology is more and more extensive. The selection of the medium-low temperature catalyst directly influences the denitration effect. The lowest reaction temperature window of the medium-low temperature catalyst which is mature to be applied in the market at present is 180 ℃. In order to meet the requirement of the optimal reaction temperature of the medium-low temperature catalyst, the flue gas needs to be heated by a heating mode under the condition that the temperature of the flue gas is too low.

Meanwhile, the investment of the catalyst accounts for a large proportion of the investment of the whole system, and after the catalyst is operated for a period of time, the activity and the selectivity of the catalyst are obviously reduced compared with those of a fresh catalyst, namely the catalyst is inactivated. The most common reason is the sulfur dioxide SO in the flue gas after adding the catalyst₂Under aerobic conditions, sulfur trioxide SO₃The generated amount of the ammonia is greatly increased, and the ammonia and the excessive ammonia gas generate ammonium bisulfate; ammonium bisulfate, however, is corrosive and sticky, and can cause blockage of catalyst pores and reduction of catalytic action. At this time, a regeneration process for restoring the catalyst activity is arranged. On the premise of not changing the chemical property of the catalyst, the catalyst is directly activated at high temperature, so that the regeneration of the catalyst can be effectively realized, and the service life of the catalyst is prolonged.

Therefore, it is necessary to provide a heating device which is not sufficient for the above prior art to achieve the goal of heating the flue gas to a suitable denitration temperature while achieving catalyst regeneration.

Disclosure of Invention

The invention aims to provide a flue gas heating device and a flue gas heating system, which can realize effective combustion by reasonably designing the ratio of combustible gas to air, transfer heat generated by combustion to flue gas to be subjected to SCR denitration treatment in a flue, quickly heat the flue gas and realize catalyst regeneration.

In order to achieve the above object, the present invention provides the following technical solutions:

a flue gas heating apparatus comprising: the heating furnace is arranged beside the flue and used for providing a heat source for heating the flue gas through combustion; the hot air mixing pipe is arranged in the flue, one end of the hot air mixing pipe extends out of the flue and is connected with the heating furnace, and holes which are uniformly distributed are formed in the part, located in the flue, of the hot air mixing pipe.

As a preferred embodiment, the above flue gas heating apparatus includes: a heating furnace body; the heating furnace body is a fire-resistant heat-insulating closed cavity; the heating furnace body is provided with a combustion burner and a hot air mixing pipe interface, and the combustion burner is used for spraying combustion gas and combustion-supporting air into the heating furnace body for combustion;

preferably, the heating furnace body is provided with two combustion burners;

preferably, six hot air mixing pipe connectors are arranged at the joint of the heating furnace body and the flue and are divided into an upper row and a lower row, the three hot air mixing pipe connectors are arranged on the upper row and the lower row, and the hot air mixing pipe connectors on the upper row and the lower row are arranged evenly in a left-right staggered mode.

As a preferred embodiment, the heating furnace body is a square structure formed by enclosing a casing and a refractory lining, and comprises an open box body and a cover matched with the open box body to form a closed space.

In the above flue gas heating apparatus, as a preferred embodiment, the heating furnace body is provided with an observation window.

As a preferred embodiment, the heating furnace body is connected with the flue through a connecting rectangular pipe, and the connecting rectangular pipe is sleeved outside the hot air mixing pipe.

As a preferred embodiment, the above flue gas heating device is provided with one heating furnace on each side of the flue; preferably, the two heating furnaces are symmetrically arranged on the left side and the right side of the flue, and the hot air mixing pipe penetrates through flue wall plates on the two sides of the flue and is connected with the two heating furnaces.

In the above flue gas heating apparatus, as a preferred embodiment, the hot air mixing pipe is a circular pipe, and three or four rows of holes are arranged on the outer surface of the hot air mixing pipe in a manner parallel to the axial direction, and the holes are uniformly distributed along the axial direction and the circumferential direction of the hot air mixing pipe;

preferably, four rows of holes are arranged on the outer surface of the hot air mixing pipe in a manner of being parallel to the axial direction, the holes of adjacent rows are aligned in the circumferential direction, and the opening direction of each row of holes is respectively located in the directions of 1:30, 4:30, 7:30 and 10:30 of the clock when viewed from the circumferential direction of the hot air mixing pipe.

A flue gas heating system comprising:

the flue gas heating device comprises two heating furnaces oppositely arranged on two sides of a flue and a hot air mixing pipe which penetrates through two sides of the flue and is connected with the two heating furnaces; a thermocouple is also arranged in the heating furnace and is used for measuring the temperature in the hearth;

a combustion gas source connected to a fuel inlet of a combustion burner of the heating furnace;

the combustion-supporting fan is connected with an air inlet of a combustion burner of the heating furnace;

the matched pipeline comprises a combustion-supporting air pipe and a combustion gas pipeline, wherein the combustion-supporting air pipe and the combustion gas pipeline are respectively provided with an adjusting valve, a flow pore plate and a transmitter and are used for monitoring the flow of fluid in the combustion-supporting air pipe and the combustion gas pipeline; the combustion gas pipeline is provided with a stop valve for cutting off and opening the combustion gas pipeline;

a computer control system comprising a PLC and HMI interconnected; the PLC is respectively connected with a thermocouple in the heating furnace, a smoke detection thermal resistor in the flue, a cut-off valve, a regulating valve and a transmitter, and is used for receiving and processing the transmitted information and then transmitting the information to the HMI; the HMI is used for carrying out data communication with the PLC, monitoring the running state of the heating furnace and the site temperature, pressure, flow real-time and historical information in real time through the HMI, and simultaneously carrying out remote operation of the stop valve, the regulating valve and the combustion fan.

Above-mentioned flue gas heating system, as a preferred embodiment, the trip valve is pneumatic trip valve, the governing valve is pneumatic control valve, flue gas heating system still includes compressed air source and compressed air pipeline, compressed air source passes through the compressed air pipeline respectively with pneumatic trip valve with pneumatic control valve connects for provide the compressed air as power.

In the above flue gas heating system, as a preferred embodiment, the PLC is further connected to a differential pressure detection device disposed on a catalyst layer in the SCR denitration device, and receives a signal detected by the differential pressure detection device, and if the signal is found to be abnormal, controls the flue gas heating device to adjust the heating degree of the flue gas to be subjected to SCR denitration.

Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:

1) the lowest reaction temperature window of the medium-low temperature catalyst which is mature and applied in the current market is 165-180 ℃. In flue gas system a bit, can't provide such flue gas temperature, consequently need heat up the flue gas to satisfy the system demand, utilize the heating device that this application provided to heat up the flue gas fast, thereby solve the flue gas temperature effectively and hang down the problem that leads to can't satisfying the best reaction temperature of low temperature catalyst.

2) Under the aerobic condition, the generation amount of sulfur trioxide is greatly increased, and the sulfur dioxide and excessive ammonia gas generate ammonium bisulfate, and the ammonium bisulfate has corrosivity and viscosity and can adsorb fly ash in flue gas, so that the pore of a catalyst is easily blocked, and the catalytic action is reduced. In order to remove the influence of ammonium bisulfate on the catalyst bed, a high-temperature heating method can be adopted to realize the chemical decomposition of the ammonium bisulfate, and the specific principle is as follows: when ammonium bisulfate is heated slightly (200 ℃ or higher), the following decomposition reaction proceeds:

NH₄HSO₄＝NH₃↑+H₂SO₄

decomposition reaction which occurs when the temperature is continuously raised to above 345 ℃:

H₂SO₄＝H₂O+SO₃

in the operation process of the denitration reactor, for example, the designed resistance value of the catalyst layer is less than 1000Pa, and when the resistance value of the catalyst layer is detected to exceed 80-90% of the designed resistance value (namely 800-900Pa), the heating device provided by the application can be used for heating the flue gas in the flue under the condition of not stopping the SCR denitration system, and the hot flue gas can enable ammonium bisulfate to generate the chemical reaction after passing through the catalyst bed layer, so that the regeneration of the catalyst is realized, and the replacement period of the whole catalyst layer is prolonged.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.

Fig. 1 is a schematic front view of a heating furnace according to an embodiment of the present invention;

FIG. 2 is a schematic top view of the heating furnace of FIG. 1;

fig. 3 is a schematic front view of a flue gas heating device according to an embodiment of the present invention;

FIG. 4 is a schematic top view of the flue gas heating apparatus of FIG. 3;

FIG. 5 is a schematic front view of a hot air mixing tube;

FIG. 6 is a cross-sectional view taken along line A-A of FIG. 5;

fig. 7 is a schematic structural flow chart of a flue gas heating system according to an embodiment of the present invention.

In the figure: 1. heating furnace; 11. a heating furnace body; 12. a combustion burner; 13. a hot air mixing pipe interface; 14. an observation window; 15. a thermocouple; 2. a hot air mixing pipe; 21-holes; 3. connecting the rectangular pipes; 4. a flue; 41. a flue wall plate; 5. a combustion-supporting air duct; 51. a combustion fan; 6. a combustion gas conduit; 61. a source of combustion gas; 7-compressed air pipeline; 71. a source of compressed air; 81. a pressure transmitter; 82. a flow orifice plate; 83. a differential pressure transmitter; 91-pneumatic quick-cut valve; 92-pneumatic regulating valve.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are for convenience of description of the present invention only and do not require that the present invention must be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. The terms "connected" and "connected" used herein should be interpreted broadly, and may include, for example, a fixed connection or a detachable connection; they may be directly connected or indirectly connected through intermediate members, and specific meanings of the above terms will be understood by those skilled in the art as appropriate.

According to an embodiment of the present invention, as shown in fig. 1 to 4, the present invention provides a flue gas heating apparatus, including: a heating furnace 1 and a hot air mixing pipe 2. The above components and their connections will be described below.

Heating furnace 1 sets up by the flue for the flue gas heating provides the heat source through the burning, heating furnace 1 includes: the heating furnace comprises a heating furnace body 11, a combustion burner 12 and a hot air mixing pipe interface 13; wherein, the heating furnace body 11 is a fire-resistant heat-insulating closed cavity; the heating furnace body 11 is provided with a combustion burner 12 and a hot air mixing pipe interface 13, and the combustion burner 12 is used for distributing input combustion gas and combustion-supporting air and spraying the combustion gas and the combustion-supporting air into the heating furnace body 11 for combustion in a certain mode; the combustion burner 12 has a fuel inlet connected to the combustion gas duct 6 for inputting combustion gas, an air inlet connected to the combustion air duct 5 for inputting combustion air, and an ejection hole. When in use, the combustion gas in the combustion gas pipeline 6 is sent into the combustion burner 12 through the fuel inlet, and the air for supporting combustion in the combustion air pipe 5 enters the combustion burner 12 through the air inlet; the mixture of the two gases is injected into the heating furnace body 11 through the spouting holes to be burned to generate heat. The hot air mixing pipe interface 13 arranged on the heating furnace body 11 is used for connecting an external hot air mixing pipe 2 to output heat generated by combustion, in other words, the hot air mixing pipe interface 13 is reserved at the interface of the heating furnace body 11 and the flue.

Specifically, the heating furnace body is a square structure formed by surrounding an outer shell and a refractory material lining, in the specific embodiment of the invention, the outer shell of the heating furnace body 11 is a steel plate made of carbon steel, the lining is a complete furnace wall formed by using refractory bricks through a special masonry method, and a stable and firm masonry structure is formed after the heating furnace is dried; including open-ended box and the lid of cooperating with it in order to form airtight space, during operation (during the heating), the box forms airtight space with the lid cooperation, and can open the lid and make things convenient for the staff to get into the operation in the box when needs are installed and are overhauld nozzle and inside refractory material. The combustion burner 12 can be connected with the heating furnace body 11 through a flange, and a plurality of combustion burners 12 can be arranged on one heating furnace to meet different requirements and enhance the applicability of the heating furnace 1; similarly, a plurality of hot air mixing pipe connectors 13 can be provided to meet different requirements and enhance the applicability of the heating furnace 1, in the specific embodiment of the invention, six hot air mixing pipe connectors 13 are provided, which are divided into two rows, namely, an upper row, a lower row, a third row and a second row, and the hot air mixing pipe connectors 13 in the two rows are arranged in a left-right staggered manner. The heating furnace 1 provided by the application has the advantages that the combustion burner 12, the heating furnace body 11, related pipelines and valve assemblies can be integrally assembled in a factory and then installed on site, and any secondary processing is not needed on site.

Preferably, a viewing window 14 is designed on the furnace body 11 for viewing the combustion situation in situ.

The hot air mixing pipe 2 is arranged in the flue, the hot air mixing pipe 2 is provided with holes 21, one end of the hot air mixing pipe 2 extends out of the flue and is connected with the heating furnace 1, and the hot air mixing pipe is used for inputting high-temperature flue gas generated by combustion of the heating furnace 1 into the flue to be mixed with the flue gas in the flue, so that heat of the high-temperature flue gas is transferred to the flue gas in the flue, and the hot air mixing pipe is shown in fig. 3, 5 and 6. Specifically, one end of the hot air mixing pipe 2 is connected with the hot air mixing pipe interface 13, the other end of the hot air mixing pipe extends into the flue, and holes 21 which are uniformly distributed are formed in the surface of the extending part, so that high-temperature flue gas generated by sufficient combustion in the heating furnace 1 can properly enter the flue through the holes 21 to be mixed with original flue gas (flue gas to be subjected to SCR denitration) in the flue, heat of the high-temperature flue gas is transferred to original flue gas in the flue, and therefore the original low-temperature flue gas in the flue is heated. Preferably, the holes 21 are uniformly distributed on the surface of the hot air mixing pipe 2; more preferably, the hot air mixing pipe 2 is a circular pipe, three or four rows of holes are arranged on the outer surface of the hot air mixing pipe in a manner of being parallel to the axial direction, and the holes 21 are uniformly distributed along the axial direction and the circumferential direction of the hot air mixing pipe (see fig. 5 and 6); the outer surface of the hot air mixing pipe 2 in the specific embodiment of the application is uniformly provided with four rows of holes in a mode of being 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 respectively positioned in the directions of 1:30, 4:30, 7:30 and 10:30 of the clock when viewed from the cross section (see fig. 6); so can guarantee more that hot-blast mixing tube 2 keeps sufficient intensity simultaneously the mixed wind is effectual. The hot air mixing pipe of this application is rationally distributed, simultaneously through seting up evenly distributed's hole 21 on the hot air mixing pipe, makes hot-blast and each part abundant contact of flue gas in whole flue cross-section, under the condition of not excessively increasing flue gas resistance, can furthest's the even heating demand of satisfying the flue gas.

Preferably, the heating furnace body 11 and the flue are connected together through a connecting rectangular pipe 3; specifically, the heating furnace body 11 and the flue wall plate 41 are connected together through a connecting rectangular pipe 3, and the connecting rectangular pipe 3 is sleeved outside the hot air mixing pipe 2; the connecting rectangular pipe 3 not only has the function of facilitating the connection of the heating furnace body 11 and the flue, but also has the functions of sealing and heat preservation.

Preferably, one heating furnace 1 is arranged on each side of the flue. Specifically, the two heating furnaces 1 are respectively arranged on the left side and the right side of the flue wall plate 41 and connected through the hot air mixing pipe 1; the hot air mixing pipe 1 penetrates through the wall plates of the flues at the two sides, and the part of the hot air mixing pipe 2 in the flue is provided with uniform distribution holes. The number of the hot air mixing pipes 1 may be set according to circumstances, and the present invention is not limited thereto.

In the application, the combustion burner 12 preferably adopts a low-NOx temperature-adjusting gas burner, for example, the model of the product of Beijing Xingda Chi thermotechnical control equipment Limited company is BSTN1500 coke oven gas burner, and the burner is designed by adopting a staged mixed combustion principle, and has the advantages of large adjusting ratio, good flame stability, low NOx emission and the like; the combustion medium can be coke oven gas or blast furnace gas. The burner has the following functions, and the working state of the burner can be displayed in real time through a computer: 1) automatic ignition: the gas burner enables high-reliability ignition to be possible by configuring a reliable built-in ignition device and a special high-voltage ignition transformer; 2) flame detection and flameout protection: the gas burner is provided with an ultraviolet flame detection device or an ionization flame detection device, and is matched with a burner controller for use, so that flameout protection of the burner is realized; 3) multistage combustion technology: the application of the air flow guider enables the gas and the combustion air to realize multi-stage mixing, a local gas-rich area and oxygen-poor combustion are formed, and the emission of NOx products is greatly reduced; 4) controlling the spraying temperature of the flue gas: under the condition of given primary air supply, the secondary air supply amount is adjusted, so that the spraying temperature of the high-temperature flue gas can be adjusted to be reduced to a temperature close to the preset flue gas temperature, and overheating and overburning are prevented and avoided.

As shown in fig. 7, the present invention also provides a chimney heating system comprising: the flue gas heating device comprises a combustion fan, a combustion gas source, a matched pipeline, a valve and an instrument, and a computer control system for monitoring the running state of the system in real time.

Specifically, above-mentioned flue gas heating system includes:

the flue gas heating device comprises two heating furnaces 1 which are oppositely arranged on two sides of a flue, and a hot air mixing pipe 2 which penetrates through two sides of the flue and is connected with the two heating furnaces 1; a thermocouple is also arranged in the heating furnace 1 and is used for measuring the temperature in the hearth;

a combustion gas source 61 connected to a fuel inlet of the combustion burner 12 of the heating furnace 1;

a combustion fan 51 connected to an air inlet of the combustion burner 12 of the heating furnace 1;

the matched pipelines comprise a combustion-supporting air pipe 5 and a combustion gas pipeline 6, wherein the combustion-supporting air pipe 5 and the combustion gas pipeline 6 are respectively provided with an adjusting valve, flow pore plates 82 and 83 and a transmitter for monitoring the flow of fluid in the combustion-supporting air pipe 5 and the combustion gas pipeline 6; a cut-off valve is arranged on the combustion gas pipeline 6 and is used for cutting off and opening the combustion gas pipeline 6;

a computer control system including a Programmable Logic Controller (PLC) and a Human Machine Interface (HMI) connected to each other; the PLC is respectively connected to a thermocouple 15 in the heating furnace 1, a smoke detection thermal resistor (not shown in fig. 7) in the flue, valves (such as a pneumatic quick-cutting valve 91 and a pneumatic regulating valve 92) on the pipeline, and transmitters (such as a pressure transmitter 81 and a differential pressure transmitter 83) for receiving and processing the transmitted information, and then transmitting the information to the HMI; the HMI and the PLC are in data communication, the HMI monitors the running state of each device (such as a combustion burner, a valve, a detection device of each measuring point, a combustion fan and the like) and real-time and historical information such as field temperature, pressure, flow and the like in real time, and meanwhile, the HMI carries out remote operation on the field devices (such as the combustion burner, the valve, the combustion fan and the like).

As a preferred embodiment, the cut-off valve is a pneumatic quick-cutting valve 91, the regulating valve is a pneumatic regulating valve 92, two pneumatic quick-cutting valves 91 are adjacently arranged on a main pipe of the combustion gas pipeline 6, each branch pipe of the combustion gas pipeline 6 is provided with one pneumatic quick-cutting valve 91, and the main pipes of the combustion gas pipeline 6 and the combustion air pipe 5 are provided with one pneumatic regulating valve 92; the flue gas heating system also comprises a compressed air source 71 and a compressed air pipeline 7, wherein the compressed air source 71 is respectively connected with the pneumatic regulating valve 92 and the pneumatic quick-cutting valve 91 through the compressed air pipeline 7 and is used for providing compressed air as power.

In the preferred embodiment of the invention, the computer control system adopts a set of German SIEMENSS7-300 series PLC control system, a control cabinet is required to be arranged for establishing the computer control system, the PLC is installed in the control cabinet, an HMI is arranged on the control cabinet, data communication is carried out between the HMI and the PLC, an operator can monitor the running state of each device of the heating system and various real-time and historical information such as site temperature, pressure, flow and the like in real time through the HMI, and meanwhile, remote operation of the site device can be carried out through the HMI.

In the preferred embodiment of the invention, two heating furnaces 1 are symmetrically arranged at two sides of a flue 4 of the whole heating system, and a set of hot air mixing pipes 2 (total 6 pipes) penetrate through two sides of the flue 4 and are connected with the two heating furnaces 1; each heating furnace 1 is provided with two combustion burners 12. The combustion gas pipeline 6 comprises a main pipe and four branch pipes which are respectively connected with four combustion burners, wherein a manual ball valve, a blind plate valve, two adjacent pneumatic quick-cutting valves 91, a pressure transmitter 81, a flow orifice plate 82, a differential pressure transmitter 83 and a pneumatic regulating valve 92 are sequentially arranged on the main pipe according to the fluid flowing direction, the pneumatic quick-cutting valves 91 are respectively arranged on the four branch pipes, and the front and the back of each pneumatic quick-cutting valve 91 are respectively provided with the manual ball valve; the combustion-supporting air duct 5 also comprises a main duct and four branch ducts respectively connected with the four combustion burners 12, the main duct is respectively provided with a pneumatic control valve 92, the main duct is provided with a pneumatic control valve 92, and each branch duct is provided with a manual control valve. For safety and automatic control considerations, the embodiment employs a pneumatic quick-cut valve 91 to open and close the combustion gas conduit 6, a pneumatic regulator valve 92 to regulate the gas flow, and a pressure transmitter 81, an orifice plate 82, and a differential pressure transmitter 83 to measure the flow of fluid in the conduit. Each combustion nozzle 12 is provided with a local ignition control system, which is convenient for local ignition debugging and maintenance, a thermocouple 15 is arranged in each heating furnace 1 for measuring the temperature of a hearth, a smoke discharge detection thermal resistor is arranged on a flue, the combustion nozzle 12 adopts a direct open flame heating mode to heat the flue gas temperature to the working temperature, such as 250 ℃, the thermocouple 15 and the thermal resistor immediately transmit the detected flue gas temperature value to a PLC (programmable logic controller), the PLC receives the detected flue gas temperature value and compares the detected flue gas temperature value with a set flue gas temperature value, and then the flow of combustion air and gas conveyed to the heating furnace 2 is continuously regulated according to a certain proportion according to the deviation of the detected flue gas temperature value and the set flue gas temperature value, namely, the computer control system calculates and adjusts the flow of the gas and the combustion air, and the air-fuel ratio is subjected to amplitude.

As a preferred embodiment, the PLC is further connected to a differential pressure detection device disposed on a catalyst layer in the SCR denitration device, and receives a signal detected by the differential pressure detection device, and if the signal is found to be abnormal, that is, a value corresponding to the signal exceeds a preset threshold, the PLC controls the flue gas heating device to adjust the heating degree of the flue gas to be subjected to SCR denitration. If the signal transmitted by the differential pressure detection device is abnormal, the resistance of the catalyst layer is increased and the catalyst layer is seriously blocked, and at the moment, the computer control system is required to control the flue gas heating device to heat the flue gas to a higher temperature so as to enable the ammonium bisulfate attached to the catalyst to generate decomposition reaction, thereby enabling the catalyst to realize online regeneration. The differential pressure detection device is used for detecting the resistance of the catalyst layer to the flue gas, and can be a differential pressure transmitter or two pressure transmitters which are respectively arranged at the upstream of the catalyst layer and the downstream of the catalyst layer.

In short, the main process flow for treating the flue gas to be subjected to SCR denitration by using the flue gas heating system is as follows: after the combustible gas supplied by a factory and the air introduced by the combustion fan are reasonably proportioned, the combustible gas is fully combusted in the heating furnace 1 through the combustion burner 12; the heat generated by combustion heats the flue gas through the holes uniformly distributed on the hot air mixing pipe 2, thereby realizing the purpose of heating the flue gas. The combustion of the heating furnace 1 is monitored in real time through a whole set of computer control system, so that the stability of the combustion system is ensured, and the requirement of the temperature change of the flue gas on the heating capacity of the heating device can be met.

In summary, the flue gas heating device and the flue gas heating system provided by the invention can rapidly heat the flue gas when the flue gas temperature of the denitration system is lower than the optimal reaction temperature requirement of the catalyst, so as to meet the system requirement; meanwhile, the catalyst is regenerated under the condition that the normal operation of the denitration system is not influenced, namely, the online regeneration is carried out.

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

1. the heating furnace adopts an integrated design, and is convenient and rapid to install;

2. the low-nitrogen combustion technology is adopted, and meanwhile, the accurate control of a combustion system is realized by combining a computer system;

3. the design of the hot air mixing pipeline realizes uniform heating;

4. the online regeneration of the catalyst can be realized; the following target requirements for the regenerated catalyst can be met: (1) the physical blockage of the regenerated catalyst is less than 5 percent; (2) physical and chemical properties are restored to the level close to that of a new catalyst; (3) mechanical strength to withstand transport and expected service life of the catalyst; (4) denitration rate, SO₂/SO₃The conversion rate, the ammonia escape rate and the pressure drop are ensured.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A flue gas heating apparatus, characterized in that the flue gas heating apparatus comprises: the heating furnace is arranged beside the flue and used for providing a heat source for heating the flue gas through combustion; the hot air mixing pipe is arranged in the flue, one end of the hot air mixing pipe extends out of the flue and is connected with the heating furnace, and holes which are uniformly distributed are formed in the part, located in the flue, of the hot air mixing pipe.

2. The flue gas heating apparatus according to claim 1, wherein the heating furnace comprises: a heating furnace body; the heating furnace body is a fire-resistant heat-insulating closed cavity; the heating furnace body is provided with a combustion burner and a hot air mixing pipe interface, and the combustion burner is used for spraying combustion gas and combustion-supporting air into the heating furnace body for combustion;

preferably, the heating furnace body is provided with two combustion burners;

3. The fume heating device according to claim 2, wherein said furnace body is a square structure formed by surrounding an outer shell and a refractory lining, and comprises an open box body and a cover cooperating therewith to form a closed space.

4. The fume heating device according to any one of claims 1 to 3, wherein an observation window is provided on said heating furnace body.

5. The flue gas heating device according to any one of claims 1 to 3, wherein the heating furnace body is connected with the flue through a connecting rectangular pipe, and the connecting rectangular pipe is sleeved outside the hot air mixing pipe.

6. A flue gas heating apparatus according to any one of claims 1 to 3, wherein one heating furnace is arranged on each side of the flue; preferably, the two heating furnaces are symmetrically arranged on the left side and the right side of the flue, and the hot air mixing pipe penetrates through flue wall plates on the two sides of the flue and is connected with the two heating furnaces.

7. The flue gas heating device according to any one of claims 1 to 3, wherein the hot air mixing pipe is a circular pipe, three or four rows of holes are arranged on the outer surface of the hot air mixing pipe in a manner parallel to the axial direction, and the holes are uniformly distributed along the axial direction and the circumferential direction of the hot air mixing pipe;

8. A flue gas heating system, comprising:

the flue gas heating device according to any one of claims 1 to 7, comprising two heating furnaces oppositely arranged at two sides of the flue, and a hot air mixing pipe penetrating through two sides of the flue and connecting the two heating furnaces; a thermocouple is also arranged in the heating furnace and is used for measuring the temperature in the hearth;

9. The fume heating system of claim 8,

the trip valve is pneumatic trip valve, the governing valve is pneumatic governing valve, flue gas heating system still includes compressed air source and compressed air pipeline, compressed air source passes through the compressed air pipeline respectively with pneumatic trip valve with pneumatic governing valve connects for provide the compressed air as power.

10. The fume heating system according to claim 8 or 9,

the PLC is also connected with a differential pressure detection device arranged on a catalyst layer in the SCR denitration device, receives signals detected by the differential pressure detection device, and controls the flue gas heating device to adjust the heating degree of the flue gas to be subjected to SCR denitration if the signals are found to be abnormal.