Gas furnace ammonia-free low-temperature denitration device and method

Abstract

The present invention provides a gas furnace ammonia-free low-temperature denitrification device and method. The hot air after flue gas heat exchange is divided into two paths, one is sent to the gas furnace set up once, and the other is sent to the flue gas conditioning smoke box pipeline system; the present invention organically combines the pretreatment of flue gas, the conditioning of flue gas, the catalytic oxidation of nitrogen oxides in the flue gas, and the reaction and absorption of nitrogen oxides in the flue gas, and realizes the implementation steps of distributed dust removal and desulfurization pretreatment of flue gas, catalytic oxidation of nitrogen oxides, and denitrification, and has high denitrification efficiency under low temperature conditions. Since the present invention does not involve ammonia, and pre-treats dust and sulfur oxides in flue gas, it can be applied to the desulfurization and denitrification treatment of flue gas with high sulfur content and nitrogen oxide content in areas such as small gas furnaces in the petrochemical industry, and has a wide range of applications.

Description

Technical Field

[0001] The invention relates to the field of environmental protection of flue gas, and in particular to an ammonia-free low-temperature denitration device and method for a gas furnace. Background Art

[0002] As environmental emission requirements become more and more stringent, enterprises are also increasing their efforts to control pollution, and flue gas control is receiving more and more attention. At present, the mainstream denitrification process in the power industry, metallurgical industry, cement industry, etc. adopts high-temperature and high-dust flue gas denitrification. The solution is low-pore number high-temperature SCR catalytic denitrification + bag filter + wet desulfurization process for flue gas desulfurization and dust removal. For sintering machines, vertical furnaces, coke ovens and lime kilns in the steel industry, due to the low exhaust temperature, large amount of flue gas ash, and metal elements in the flue gas that are easy to cause catalyst poisoning, wet desulfurization + low-temperature SCR denitrification process is generally used for desulfurization and denitrification. At present, both of these process technology routes involve the use of ammonia, a denitrification reducing agent, and have complex process flows, high investment, large floor space, many operating equipment, and high energy consumption and other unfavorable factors.

[0003] For the operating unit area of ​​the petrochemical industry, the general emission source is a small gas furnace with a small amount of flue gas. The gas furnace is located in the area near the petrochemical unit, and the safety level requirements are very high. The reducing agent ammonia belongs to Class B explosive gas. The above-mentioned mainstream high-temperature SNCR and SCR denitrification processes, as well as the medium and low temperature SCR denitrification processes, all require the preparation and reaction of the reducing agent ammonia, which is not conducive to the denitrification layout principle in the petrochemical unit area. The new system denitrification needs to complete the removal of nitrogen oxides in the flue gas without an ammonia reducing agent. The original traditional SNCR and SCR denitrification processes do not meet the process requirements. Therefore, it is necessary to develop a new ammonia-free denitrification process to meet production requirements. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a gas furnace ammonia-free low-temperature denitration device and method.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a gas furnace ammonia-free low-temperature denitrification device, comprising a gas furnace, a heat pipe heat exchanger, a flue gas pretreatment device, a flue gas ammonia-free denitrification catalytic oxidation device, a flue gas ammonia-free denitrification absorption device, an induced draft fan and an exhaust pipe which are arranged in sequence; the gas furnace, the heat pipe heat exchanger, the flue gas pretreatment device, the flue gas ammonia-free denitrification catalytic oxidation device, the flue gas ammonia-free denitrification absorption device, the induced draft fan and the exhaust pipe which are arranged in sequence are connected by pipelines.

[0006] Preferably, the gas furnace ammonia-free low-temperature denitrification device also includes a booster fan and a flue gas conditioning smoke box pipeline system; the flue gas conditioning smoke box pipeline system includes a cold air regulating valve, a flue gas mixing regulator and a hot air regulating valve; the cold air regulating valve is connected to the booster fan; the hot air regulating valve is connected to the heat pipe heat exchanger.

[0007] Preferably, the flue gas pretreatment device includes an absorbent storage bin, an absorbent feeder, an absorbent delivery pipe, a triangular flow aid, a smoke chamber louver, an absorbent unloader, a discharge bin and a pretreatment body; the absorbent feeder is arranged between the absorbent storage bin and the absorbent delivery pipe; the absorbent delivery pipe is embedded in the upper part of the flue gas pretreatment device; the triangular flow aid is arranged in the middle part of the smoke pretreatment device; the smoke chamber louver is arranged in the lower part of the smoke pretreatment device; the absorbent unloader is connected to the discharge bin and is connected to the smoke chamber louver through the absorbent delivery pipe; the pretreatment body includes an outlet flue, a main flue cavity and an inlet flue; the outlet flue is connected to a flue gas mixing regulator; the inlet flue is connected to a heat pipe heat exchanger.

[0008] Preferably, the flue gas pretreatment device can modulate the flue gas transmitted from the flue gas conditioning smoke box pipeline system and the heat pipe heat exchanger, ensuring that the flue gas concentration is not too high during the subsequent reaction process, thereby achieving a better denitrification effect.

[0009] Preferably, the heat pipe heat exchanger includes a smoke chamber, an air chamber and a sealing partition; the smoke chamber includes a smoke chamber inlet section, a smoke chamber smoke fin heat pipe and a smoke chamber outlet section; the air chamber includes an air chamber outlet section, an air chamber smoke fin heat pipe and an air chamber inlet section; the sealing partition is arranged between the smoke chamber and the air chamber.

[0010] Preferably, the flue gas mixing regulator includes a regulating hot air interface, a hot air porous cylindrical air distributor, a baffle and a regulator box; the outlet of the flue gas mixing regulator is connected to the inlet of the flue gas ammonia-free denitrification catalytic oxidation device; one end of the flue gas mixing regulator is also connected to the flue gas pretreatment device; the regulating hot air interface is connected to the flue gas regulating smoke box pipeline system; the hot air porous cylindrical air distributor is connected to the regulating hot air interface; the baffles are staggered on both sides of the middle of the regulator box.

[0011] Preferably, the catalyst of the flue gas ammonia-free denitrification catalytic oxidation device is a drawer module unit structure; the catalyst is a honeycomb structure; the porosity of the catalyst is between 0.65-0.75.

[0012] Preferably, the flue gas ammonia-free denitrification absorption device is a drawer-filled module structure; the absorbent is in granular or thin strip form.

[0013] Preferably, a method for low-temperature denitration of a gas furnace without ammonia comprises the following specific steps:

[0014] Step 1: The gas is burned in the gas furnaces arranged in sequence to produce flue gas, which is discharged through the tail flue of the unit;

[0015] Step 2: The heat pipe heat exchanger uses the waste heat of the flue gas to heat the air. A part of the hot air enters the combustion chamber of the gas furnace arranged in sequence as hot air for combustion, and the other part of the hot air passes through the hot air regulating valve and enters the flue gas regulating smoke box pipeline system as hot air for flue gas temperature regulation;

[0016] Step 3: The flue gas is transported to the flue gas pretreatment device through a heat pipe heat exchanger. The flue gas pretreatment device is a dynamic countercurrent particle absorbent reactor. The flue gas enters the inlet flue of the pretreatment device, passes through the smoke chamber louver and enters the absorbent particles in the pretreatment body, and directly contacts and reacts with the absorbent in a countercurrent manner to remove sulfur oxides and dust. After the flue gas is pretreated, it is collected at the upper part of the pretreatment body and discharged from the outlet flue. The outlet is connected to the flue gas mixing regulator. After the particle absorbent contacts and reacts with the flue gas for a period of time and becomes ineffective, it is discharged by the absorbent unloader, and fresh absorbent particles are replenished by the absorbent feeder at the same time;

[0017] Step 4: After the normal temperature air is pressurized by the booster fan, part of it is sent to the heat pipe heat exchanger. The hot air after the flue gas heat exchange is divided into two paths; part of it is led to the flue gas conditioning smoke box pipeline system through the cold air regulating valve, mixed with part of the hot air heated by the heat pipe heat exchanger, and sent to the flue gas mixing regulator after adjusting the appropriate flue gas temperature;

[0018] Step 5: The flue gas at the outlet of the flue gas pretreatment device is mixed with the warm air at the outlet of the flue gas conditioning smoke box duct system, and connected to the inlet flue of the flue gas ammonia-free denitrification catalytic oxidation device. After the flue gas is in direct contact with the catalyst particles, most of the low-valent nitrogen oxides in the flue gas are oxidized to high-valent nitrogen oxides. The outlet of the flue gas ammonia-free denitrification catalytic oxidation device is directly connected to the inlet of the flue gas ammonia-free denitrification absorption device. The high-valent nitrogen oxides in the flue gas are adsorbed and removed by the particulate absorbent and the absorption reaction. The clean flue gas without pollutants is discharged to the exhaust pipe through the induced draft fan.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention organically combines the pretreatment of flue gas, the conditioning of flue gas, the catalytic oxidation of nitrogen oxides in flue gas and the reactive absorption of nitrogen oxides in flue gas, realizes the implementation steps of distributed dust removal and desulfurization pretreatment of flue gas, catalytic oxidation of nitrogen oxides, and denitrification, and has high denitrification efficiency under low temperature conditions. Since the present invention does not involve ammonia and pretreats dust and sulfur oxides in flue gas, it can be applied to the desulfurization and denitrification treatment of flue gas with high sulfur content and nitrogen oxide content in areas such as small gas furnaces in the petrochemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a low-temperature denitration device system without ammonia for a gas furnace;

[0021] Figure 2 It is a schematic diagram of an air heat pipe heat exchanger;

[0022] Figure 3 Schematic diagram of the pretreatment device system;

[0023] Figure 4 Schematic diagram of flue gas mixing regulator;

[0024] Figure 5 Schematic diagram of smoke conditioning smoke box duct system;

[0025] Figure 6 Schematic diagram of the ammonia-free low-temperature denitrification reactor device.

[0026] Among them: 1. Gas furnace arranged in sequence; 2. Heat pipe heat exchanger; 3. Flue gas pretreatment device; 4. Flue gas ammonia-free denitrification catalytic oxidation device; 5. Flue gas ammonia-free denitrification absorption device; 6. Induced draft fan; 7. Exhaust pipe; 8. Booster fan; 9. Flue gas conditioning smoke box pipeline system; 21. Flue gas chamber; 22. Air chamber; 23. Sealing partition; 211. Flue gas chamber inlet section; 212. Flue gas chamber flue gas fin heat pipe; 213. Flue gas chamber outlet section; 221. Air chamber outlet section; 222. Air chamber flue gas fin heat pipe; 223. Air chamber inlet Section; 31, absorbent storage bin; 32, absorbent feeder; 33, absorbent delivery pipe; 35, triangular flow aid; 37, smoke chamber shutters; 38, absorbent discharger; 39, discharge bin; 310, pretreatment body; 3101, outlet flue; 3102, main flue cavity; 3103, inlet flue; 91, cold air regulating valve; 92, flue gas mixing regulator; 93, hot air regulating valve; 921, hot air regulating interface; 922, hot air porous cylindrical air distributor; 923, baffle; 924 regulator box. DETAILED DESCRIPTION

[0027] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the following detailed description is given in conjunction with the embodiments.

[0028] Please refer to Figures 1 to 6 The present invention provides a gas furnace ammonia-free low-temperature denitration device, comprising a gas furnace 1, a heat pipe heat exchanger 2, a flue gas pretreatment device 3, a flue gas ammonia-free denitration catalytic oxidation device 4, a flue gas ammonia-free denitration absorption device 5, an induced draft fan 6 and an exhaust pipe 7 which are arranged in sequence; the gas furnace 1, the heat pipe heat exchanger 2, the flue gas pretreatment device 3, the flue gas ammonia-free denitration catalytic oxidation device 4, the flue gas ammonia-free denitration absorption device 5, the induced draft fan 6 and the exhaust pipe 7 which are arranged in sequence are connected by a pipeline.

[0029] Preferably, the gas furnace ammonia-free low-temperature denitrification device also includes a booster fan 8 and a flue gas conditioning smoke box pipeline system 9; the flue gas conditioning smoke box pipeline system 9 includes a cold air regulating valve 91, a flue gas mixing regulator 92 and a hot air regulating valve 93; the cold air regulating valve 91 is connected to the booster fan 8; the hot air regulating valve 93 is connected to the heat pipe heat exchanger 2.

[0030] Preferably, the flue gas pretreatment device 3 includes an absorbent storage bin 31, an absorbent feeder 32, an absorbent delivery pipe 33, a triangular flow aid 35, a smoke chamber shutter 37, an absorbent discharger 38, a discharge bin 39 and a pretreatment body 310; the absorbent feeder 32 is arranged between the absorbent storage bin 31 and the absorbent delivery pipe 33; the absorbent delivery pipe 33 is embedded in the upper part of the flue gas pretreatment device 3; the triangular flow aid 35 is arranged in the flue gas chamber louver ... The middle part of the flue gas pretreatment device 3; the smoke chamber louver 37 is arranged at the lower part of the flue gas pretreatment device 3; the absorbent unloader 38 is connected to the unloading bin 39 and is connected to the smoke chamber louver 37 through the absorbent delivery pipe 33; the pretreatment body 310 includes an outlet flue 3101, a main flue cavity 3102 and an inlet flue 3103; the outlet flue 3101 is connected to the flue gas mixing regulator 92; the inlet flue 3103 is connected to the heat pipe heat exchanger 2.

[0031] Preferably, the flue gas pretreatment device 3 can modulate the flue gas transmitted from the flue gas conditioning smoke box pipeline system 9 and the heat pipe heat exchanger 2, ensuring that the flue gas concentration is not too high during the subsequent reaction process, thereby achieving a better denitrification effect.

[0032] Preferably, the heat pipe heat exchanger 2 includes a smoke chamber 21, an air chamber 22 and a sealing partition 23; the smoke chamber 21 includes a smoke chamber inlet section 211, a smoke chamber smoke fin heat pipe 212 and a smoke chamber outlet section 213; the air chamber 22 includes an air chamber outlet section 221, an air chamber smoke fin heat pipe 222 and an air chamber inlet section 223; the sealing partition 23 is arranged between the smoke chamber 21 and the air chamber 22.

[0033] Preferably, the flue gas mixing regulator 92 includes a regulating hot air interface 921, a hot air porous cylindrical air distributor 922, a baffle 923 and a regulator box 924; the outlet of the flue gas mixing regulator 92 is connected to the inlet of the flue gas ammonia-free denitrification catalytic oxidation device 4; one end of the flue gas mixing regulator 92 is also connected to the flue gas pretreatment device 3; the regulating hot air interface 921 is connected to the flue gas regulating smoke box pipeline system 9; the hot air porous cylindrical air distributor 922 is connected to the regulating hot air interface 921; the baffles 923 are staggered on both sides of the middle of the regulator box 924.

[0034] Preferably, the catalyst of the flue gas ammonia-free denitrification catalytic oxidation device 4 is a drawer module unit structure; the catalyst is a honeycomb structure; the porosity of the catalyst is between 0.65-0.75.

[0035] Preferably, the flue gas ammonia-free denitrification absorption device 5 is a drawer-filled module structure; the absorbent is in granular or thin strip form.

[0036] Preferably, in the low-temperature denitration device without ammonia for the gas furnace, the combined action of the heat pipe heat exchanger 2, the flue gas pretreatment device 3, the flue gas conditioning smoke box pipeline system 9 and other devices ensures that the most important thing to achieve denitration under ammonia-free conditions is the low-temperature catalyst; because in the low-temperature denitration device without ammonia for the gas furnace, the temperature of the gas that can be provided by the gas furnace 1 set at one time is about 120 degrees Celsius, but ammonia-free desulfurization and denitration require the use of a specific low-temperature catalyst; the temperature of the low-temperature catalyst reaction is about 80 degrees Celsius, which requires the temperature of the flue gas to be adjusted; at the same time, because the low-temperature denitration device without ammonia for the gas furnace conditions the flue gas, the flue gas concentration cannot be too high during the subsequent reaction process, and the denitration effect is more prominent. By pretreating and conditioning the flue gas, the low-temperature catalyst is prevented from being poisoned and burned due to excessive flue gas concentration or temperature.

[0037] Preferably, a method for low-temperature denitration of a gas furnace without ammonia is provided, wherein the specific implementation steps are as follows.

[0038] Step 1: The fuel gas is burned in the gas furnaces 1 arranged in sequence to generate flue gas, which is discharged through the tail flue of the unit.

[0039] Step 2: The function of the heat pipe heat exchanger 2 is to use the waste heat of the flue gas to heat the air. Most of the heated air enters the combustion chamber of the gas furnace 1 arranged in sequence as hot air for combustion, and part of the hot air enters the flue gas regulating smoke box pipeline system 9 through the hot air regulating valve 93 as hot air for flue gas temperature regulation.

[0040] Step three: the flue gas after heat exchange and cooling in the heat pipe heat exchanger 2 is transported to the flue gas pretreatment device 3. The flue gas pretreatment device 3 is a dynamic countercurrent particle absorbent reaction bed, and its structure includes: an absorbent storage bin 31, an absorbent feeder 32, a pretreatment body 310, a triangular flow aid 35, a smoke chamber louver 37, an absorbent discharger 38 and a discharge bin 39. The flue gas enters the inlet flue 3103 of the pretreatment device, passes through the smoke chamber louver 37 and enters the absorbent particles in the pretreatment body 310, and directly contacts and reacts with the absorbent in a countercurrent manner to remove sulfur oxides and dust. After pretreatment, the flue gas is collected at the upper part of the pretreatment body 310 and discharged from the outlet flue 3101, and the outlet is connected to the flue gas mixing regulator 92. After the particle absorbent fails after a period of contact reaction with the flue gas, it is discharged by the absorbent discharger 38, and fresh absorbent particles are replenished by the absorbent feeder 32.

[0041] Step 4: After the air at room temperature is pressurized by the booster fan 8, a part of it is sent to the heat pipe heat exchanger 2. The hot air after the flue gas heat exchange is divided into two paths, one is sent to the gas furnace 1 installed once for combustion, and the other is sent to the flue gas regulating smoke box pipeline system 9 for air distribution; at the same time, a part of the air pressurized by the booster fan 8 is connected to the flue gas regulating smoke box pipeline system 9 through the cold air regulating valve 91, mixed with part of the hot air heated by the heat pipe heat exchanger 2, and sent to the flue gas mixing regulator 92 after adjusting the appropriate flue gas temperature.

[0042] Preferably, a flue gas mixing regulator 92 is provided to ensure that the flue gas coming out of the flue gas pretreatment device 3 passes through the flue gas mixing regulator 92 and then enters the flue gas ammonia-free denitrification device 4 with a temperature within a suitable temperature range.

[0043] Step 5: The flue gas at the outlet of the flue gas pretreatment device 3 is mixed with the warm air at the outlet of the flue gas conditioning smoke box duct system 9, and is connected to the inlet flue of the flue gas ammonia-free denitrification catalytic oxidation device 4. The catalyst in the flue gas ammonia-free denitrification catalytic oxidation device 4 is a drawer module unit structure, and the catalyst is a honeycomb structure. The porosity of the catalyst is distributed between 0.65-0.75. After the flue gas directly contacts the catalyst particles, most of the low-valent nitrogen oxides in the flue gas are oxidized to high-valent nitrogen oxides. The outlet of the flue gas ammonia-free denitrification catalytic oxidation device 4 is directly connected to the inlet of the flue gas ammonia-free denitrification absorption device 5. The flue gas ammonia-free denitrification absorption device 5 is a drawer-filled module structure, and the absorbent is granular or strip-shaped. The high-valent nitrogen oxides in the flue gas are adsorbed and removed by the granular absorbent and the absorption reaction. The clean flue gas without pollutants is discharged to the exhaust pipe 7 through the induced draft fan 6.

[0044] Preferably, the flue gas pretreatment, flue gas conditioning, catalytic oxidation of nitrogen oxides in the flue gas and reactive absorption of nitrogen oxides in the flue gas are organically combined to realize the implementation steps of distributed dust removal and desulfurization pretreatment, catalytic oxidation of nitrogen oxides and denitrification of the flue gas, with high denitrification efficiency under low temperature conditions.

[0045] The present invention has been described by the above-mentioned relevant embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, changes and modifications made without departing from the spirit and scope of the present invention are all within the scope of patent protection of the present invention.

Claims

1. A gas furnace ammonia-free low-temperature denitration device, characterized in that: The invention comprises a gas furnace (1), a heat pipe heat exchanger (2), a flue gas pretreatment device (3), a flue gas ammonia-free denitration catalytic oxidation device (4), a flue gas ammonia-free denitration absorption device (5), an induced draft fan (6) and an exhaust pipe (7) which are arranged in sequence, wherein the gas furnace (1), the heat pipe heat exchanger (2), the flue gas pretreatment device (3), the flue gas ammonia-free denitration catalytic oxidation device (4), the flue gas ammonia-free denitration absorption device (5), the induced draft fan (6) and the exhaust pipe (7) which are arranged in sequence are connected by a pipeline; the gas furnace ammonia-free low-temperature denitration device also comprises a booster fan (8) and a flue gas regulating smoke box pipeline system (9); the flue gas regulating smoke box pipeline system (9) comprises a cold air regulating valve (91), a flue gas mixing regulator (92) and a hot air regulating valve (93); the cold air regulating valve (91) is connected to the booster fan (8); the hot air regulating valve (93) is connected to the heat pipe heat exchanger (2); the flue gas ammonia-free denitration absorption device (5) is connected to the exhaust pipe (5); ) is a drawer-filled module structure; the absorbent is in granular or thin strip form; the catalyst of the flue gas ammonia-free denitrification catalytic oxidation device (4) is a drawer module unit structure; the catalyst is a honeycomb structure; the porosity of the catalyst is between 0.65 and 0.75; the flue gas mixing regulator (92) includes a regulating hot air interface (921), a hot air porous cylindrical air distributor (922), a baffle (923) and a regulator box (924); the flue gas mixing The outlet of the regulator (92) is connected to the inlet of the flue gas ammonia-free denitrification catalytic oxidation device (4); one end of the flue gas mixing regulator (92) is also connected to the flue gas pretreatment device (3); the regulating hot air interface (921) is connected to the flue gas regulating smoke box pipeline system (9); the hot air porous cylindrical air distributor (922) is connected to the regulating hot air interface (921); and the baffles (923) are staggeredly distributed on both sides of the middle of the regulator box (924).

2. The ammonia-free low-temperature denitration device for a gas furnace according to claim 1, characterized in that: The flue gas pretreatment device (3) comprises an absorbent storage bin (31), an absorbent feeder (32), an absorbent delivery pipe (33), a triangular flow aid (35), a smoke chamber shutter (37), an absorbent discharger (38), a discharge bin (39) and a pretreatment body (310); the absorbent feeder (32) is arranged between the absorbent storage bin (31) and the absorbent delivery pipe (33); the absorbent delivery pipe (33) is embedded in the upper part of the flue gas pretreatment device (3); the triangular flow aid (35) The smoke chamber louver (37) is arranged in the middle of the smoke pretreatment device (3); the smoke chamber louver (37) is arranged in the lower part of the smoke pretreatment device (3); the absorbent discharger (38) is connected to the discharge bin (39) and communicates with the smoke chamber louver (37); the pretreatment body (310) comprises an outlet flue (3101), a main flue cavity (3102) and an inlet flue (3103); the outlet flue (3101) is connected to a smoke mixing regulator (92); and the inlet flue (3103) is connected to a heat pipe heat exchanger (2).

3. The ammonia-free low-temperature denitration device for a gas furnace as claimed in claim 2, characterized in that: The heat pipe heat exchanger (2) comprises a smoke chamber (21), an air chamber (22) and a sealing baffle (23); the smoke chamber (21) comprises a smoke chamber inlet section (211), a smoke chamber smoke fin heat pipe (212) and a smoke chamber outlet section (213); the air chamber (22) comprises an air chamber outlet section (221), an air chamber smoke fin heat pipe (222) and an air chamber inlet section (223); and the sealing baffle (23) is arranged between the smoke chamber (21) and the air chamber (22).

4. A method for denitrifying a gas furnace without ammonia and at low temperature using the gas furnace without ammonia and at low temperature denitrification device according to claim 3, wherein the specific steps are as follows: Step 1: The fuel gas is burned in the gas furnaces (1) arranged in sequence to generate flue gas, which is discharged through the tail flue of the unit; Step 2: The heat pipe heat exchanger (2) uses the waste heat of the flue gas to heat the air, a portion of which enters the combustion chamber of the gas furnace (1) arranged in sequence as hot air for combustion, and the other portion of the hot air passes through the hot air regulating valve (93) and enters the flue gas regulating smoke box pipe system (9) as hot air for regulating the flue gas temperature; Step 3: The flue gas is transported to the flue gas pretreatment device (3) through the heat pipe heat exchanger (2). The flue gas pretreatment device (3) is a dynamic countercurrent particle absorbent reactor. The flue gas enters the inlet flue (3103) of the pretreatment device, passes through the smoke chamber louver (37) and enters the absorbent particles in the pretreatment body (310), and directly contacts and reacts with the absorbent in a countercurrent manner to remove sulfur oxides and dust. After the flue gas is pretreated, it is collected at the upper part of the pretreatment body (310) and discharged from the outlet flue (3101). The outlet is connected to the flue gas mixing regulator (92). After the particle absorbent contacts and reacts with the flue gas for a period of time and becomes ineffective, it is discharged from the absorbent discharger (38). At the same time, fresh absorbent particles are replenished from the absorbent feeder (32); Step 4: After the normal temperature air is pressurized by the booster fan (8), a portion of the air is sent to the heat pipe heat exchanger (2), and the hot air after the flue gas heat exchange is divided into two paths; a portion of the air is led through the cold air regulating valve (91) and sent to the flue gas regulating smoke box pipeline system (9), mixed with the portion of the hot air heated by the heat pipe heat exchanger (2), and after adjusting the flue gas temperature to a suitable level, sent to the flue gas mixing regulator (92); Step 5: The flue gas at the outlet of the flue gas pretreatment device (3) is mixed with the warm air at the outlet of the flue gas conditioning smoke box duct system (9) and connected to the inlet flue of the flue gas ammonia-free denitrification catalytic oxidation device (4). After the flue gas directly contacts the catalyst particles, most of the low-valent nitrogen oxides in the flue gas are oxidized to high-valent nitrogen oxides. The outlet of the flue gas ammonia-free denitrification catalytic oxidation device (4) is directly connected to the inlet of the flue gas ammonia-free denitrification absorption device (5). The high-valent nitrogen oxides in the flue gas are adsorbed and removed by the particle absorbent and the absorption reaction. The clean flue gas with pollutants removed is discharged to the exhaust pipe (7) through the induced draft fan (6).

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