Flue gas denitration and desulfurization system for gas-fired boiler

Abstract

The utility model discloses a flue gas denitration and desulfurization system for a gas-fired boiler. The flue gas denitration and desulfurization system comprises the gas-fired boiler, a denitration system, a boiler induced draft fan, a desulfurizing agent injection and uniform distribution system, a bag-type dust collector and a chimney, a partition plate for partitioning a flue is arranged in the flue of the gas-fired boiler, a flue gas outlet of the flue at the front end of the partition plate is communicated with a flue gas inlet of the denitration system, and a flue gas outlet of the denitration system is communicated with a flue gas inlet of the flue at the rear end of the partition plate; a flue gas outlet of the flue at the rear end of the partition plate is sequentially communicated with a boiler induced draft fan and a bag-type dust collector, and a gas outlet of the bag-type dust collector is communicated with a chimney; and an injection orifice of the desulfurizing agent injection and uniform distribution system is communicated with a process pipeline between the induced draft fan and the bag-type dust collector. The system adopts a denitration, dry desulfurization and dust removal coupling process technology, realizes flue gas denitration, desulfurization and dust removal integrated gas-solid separation and ultra-low standard emission of flue gas repurification, has the characteristics of simple and reasonable system structure and easiness in operation, and can realize flue gas denitration, desulfurization and dust removal integrated treatment.

Description

Technical Field

[0001] The utility model relates to an exhaust gas treatment system, in particular to a denitrification and desulfurization system for the flue gas of a gas boiler. Background Art

[0002] Sulfur dioxide and nitrogen oxides emitted from boiler flue gas form acid rain, which not only acidifies the soil but also causes the dissolution and flow of toxic metals, resulting in a decline in the quality and yield of agricultural products. Currently, the low-nitrogen combustion denitrification technology widely used in gas boilers is mainly achieved by combining several technologies such as flue gas recirculation, air staging combustion, fuel staging, and low NO x burners, etc. Generally, the NO x emission is reduced by 25-30%, and the removal efficiency is low; for the selective non-catalytic reduction denitrification technology, a nitrogen-containing reducing agent is sprayed into a proper fixed position in the furnace to reduce NO x in the flue gas to N2. The optimal window temperature for the non-catalytic reduction denitrification reaction is between 950°C and 1150°C. Due to the uneven temperature distribution in the furnace, it varies, increasing the difficulty of debugging and operation technology. The removal efficiency is 40-50%, and the removal efficiency is not high. To achieve a certain efficiency, an excessive amount of urea or ammonia water reducing agent needs to be sprayed, which will cause corrosion and blockage of the boiler water supply preheater and air preheater. For the circulating fluidized bed semi-dry desulfurization technology widely used in gas boilers, Ca(OH)2 desulfurizer is sprayed into the desulfurization tower together with part of the circulating ash to remove SO2 in the flue gas, and the load change has a greater impact on the desulfurization efficiency. Therefore, it is imperative to develop a denitrification and desulfurization system for flue gas with a medium-high temperature denitrification catalyst suitable for the reaction temperature window of 320-420°C at the flue gas outlet of gas boilers, so as to achieve the standard discharge of the external discharge concentration of SO2, NO x and particulate pollutants in the boiler flue gas, effectively improve the atmospheric environmental quality, reduce the losses caused by acid rain, and create good conditions for the sustainable development of the economy. Summary of the Utility Model

[0003] The technical problem to be solved by the utility model is to provide a denitrification and desulfurization system for gas boiler flue gas with good treatment effect.

[0004] To solve the above technical problem, the technical solution adopted by the utility model is: it includes a gas boiler, a denitrification system, a boiler induced draft fan, a desulfurizer injection and distribution system, a bag filter, and a chimney; a partition for separating the flue is provided in the flue of the gas boiler. The flue gas outlet at the front end of the partition is connected to the flue gas inlet of the denitrification system, and the flue gas outlet of the denitrification system is connected to the flue gas inlet of the flue at the rear end of the partition; the flue gas outlet at the rear end of the partition is sequentially connected to the boiler induced draft fan and the bag filter, and the gas outlet of the bag filter is connected to the chimney; the injection port of the desulfurizer injection and distribution system is connected to the process pipeline between the induced draft fan and the bag filter.

[0005] Furthermore, the denitration system includes a denitration tower, an ammonia water tank, an ammonia supply pump, an ammonia water evaporator, an ammonia injection device, and a compressed air package; the flue gas inlet of the denitration tower is connected to the flue gas outlet of the front flue of the partition board, and the flue gas outlet of the denitration tower is connected to the flue gas inlet of the rear flue of the partition board; the ammonia water tank is sequentially connected to the ammonia water steam inlet of the ammonia injection device through the ammonia supply pump and the ammonia water evaporator, and the compressed air inlet of the ammonia injection device is connected to the compressed air package; the injection port of the ammonia injection device is connected to the flue gas inlet pipeline of the denitration tower.

[0006] Even further, the denitration system is also provided with a soot blower; the compressed air package is connected to the soot blowing port of the denitration tower through the soot blower.

[0007] Furthermore, the desulfurizing agent injection and distribution system includes a fine desulfurizing agent bin, a conveying fan, an injection valve, and an injection and distribution device; the fine desulfurizing agent bin is connected to the injection and distribution device through the conveying fan and the injection valve, and the injection outlet of the injection and distribution device is connected to the process pipeline between the induced draft fan and the bag filter.

[0008] Even further, the desulfurizing agent injection and distribution system is also provided with a desulfurizing agent bin, a vibration motor, a discharging control valve, a mill hopper, a mixing motor, a metering screw motor, and a grinder; the lower outlet of the desulfurizing agent bin is sequentially connected to the inlet of the fine desulfurizing agent bin through the discharging control valve, the mill hopper, the metering screw motor, and the grinder; the vibration motor is arranged at the lower outlet of the desulfurizing agent bin, and the mixing motor is arranged in the mill hopper.

[0009] Furthermore, it also includes a water supply preheater and an air preheater; the water supply preheater and the air preheater are arranged between the flue gas outlet of the rear flue of the partition board and the boiler induced draft fan.

[0010] Furthermore, it also includes a damper door and a seal fan; the outlet of the boiler induced draft fan is connected to the chimney through a branch flue gas pipeline and the damper door, and the air outlet of the seal fan is connected to the branch flue gas pipeline between the outlet of the boiler induced draft fan and the damper door.

[0011] Furthermore, it also includes an ash conveying device 27 and a ton bag packing machine 28; the ash outlet of the bag filter 25 is connected to the ton bag packing machine 28 through the ash conveying device 27.

[0012] Even further, it also includes a pulse valve 26; the air inlet of the pulse valve 26 is connected to a compressed air source, and the air outlet is connected to the soot blowing port of the bag filter 25.

[0013] The beneficial effects of adopting the above technical solutions are as follows: The utility model adopts the denitration + dry desulfurization + dust removal coupling process technology, which is arranged between the gas boiler and the chimney; the denitration system removes NO in the flue gas xThe redox reaction with NH3 produces non-toxic components such as N2 and H2O; the desulfurization system sprays evenly distributed ultra-fine desulfurizer powder into the high-temperature flue gas to complete the absorption and purification of SO2 and other acidic media in the flue gas; the dust removal system uses a bag filter to carry out processes such as re-desulfurization of desulfurized flue gas, soot purification, and dust removal filtration; realizing the ultra-low standard discharge of integrated gas-solid separation and flue gas re-purification for flue gas denitrification, desulfurization, and dust removal. The utility model has the characteristics of simple, reasonable, and easy-to-operate system structure, can realize the integrated treatment of flue gas denitrification, desulfurization, and dust removal, and control the external discharge concentration of boiler flue gas within SO2 ≤ 10mg / Nm 3 、NO x ≤ 50mg / Nm 3 、 particulate dust ≤ 5mg / Nm 3 to meet the compliance discharge standards, achieving a further improvement in environmental protection benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present utility model will be further described in detail below in conjunction with the drawings and specific embodiments.

[0015] Figure 1 is a schematic structural diagram of the present utility model.

[0016] In the figure: gas boiler 1, denitration tower 2, ammonia water tank 3, ammonia supply pump 4, ammonia water evaporator 5, ammonia injection device 6, ammonia unloading pump 7, compressed air package 8, soot blower 9, partition 10, water supply preheater 11, air preheater 12, boiler induced draft fan 13, desulfurizer bin 14, vibration motor 15, discharge control valve 16, mill hopper 17, mixing motor 18, metering screw motor 19, grinder 20, fine desulfurizer bin 21, conveying fan 22, injection valve 23, injection distribution device 24, bag filter 25, pulse valve 26, ash conveying device 27, ton bag packing machine 28, booster induced draft fan 29, baffle door 30, seal fan 31, chimney 32. SPECIFIC EMBODIMENTS

[0017] Figure 1As shown in the figure, the flue gas denitrification and desulfurization system of this gas boiler includes a gas boiler 1, a denitrification system, a boiler induced draft fan 13, a desulfurizing agent injection and distribution system, a bag filter 25, and a chimney 32. A partition 10 is provided in the flue of the gas boiler 1, and the partition 10 divides the flue into a front partition flue and a rear partition flue. The flue gas outlet of the front partition flue is connected to the flue gas inlet of the denitrification system, and the flue gas outlet of the denitrification system is connected to the flue gas inlet of the rear partition flue. The denitrification system includes a denitrification tower 2, an ammonia water tank 3, an ammonia supply pump 4, an ammonia water evaporator 5, an ammonia injection device 6, and a compressed air package 8; the flue gas inlet of the denitrification tower 2 is connected to the flue gas outlet of the front partition flue, and the flue gas outlet of the denitrification tower 2 is connected to the flue gas inlet of the rear partition flue. The outlet of the ammonia water tank 3 passes through the inlet of the ammonia supply pump 4, and the outlet of the ammonia supply pump 4 is connected to the inlet of the ammonia water evaporator 5, and the ammonia water evaporator 5 is heated by high-temperature steam or electricity; the outlet of the ammonia water evaporator 5 is connected to the ammonia water steam inlet of the ammonia injection device 6, and the compressed air package 8 is connected to the compressed air inlet of the ammonia injection device 6; the injection port of the ammonia injection device 6 is connected to the flue gas inlet pipeline of the denitrification tower 2. The denitrification system is also provided with a soot blower 9; the compressed air package 8 is connected to the soot blowing port of the denitrification tower 2 through the soot blower 9. The denitrification system is also provided with an ammonia unloading pump 7; the feed port at the upper part of the ammonia water tank 3 is connected to the outlet of the ammonia unloading pump 7, and the inlet of the ammonia unloading pump 7 is connected to an external ammonia water process pipeline. In this way, the flue gas in the front partition flue enters the denitrification tower 2; the ammonia water is heated to ammonia water steam by the ammonia water evaporator 5 from the ammonia water tank 3, and is sprayed into the flue gas entering the denitrification tower 2 by the ammonia injection device 6 driven by the compressed air provided by the compressed air package 8; the flue gas and ammonia water steam pass through the catalysts of each layer of the denitrification tower 2 from top to bottom in sequence for denitrification, and enter the rear partition flue from the outlet at the lower part of the denitrification tower 2.

[0018] Figure 1As shown in the figure, the flue gas denitration and desulfurization system of this gas boiler further includes a water supply preheater 11 and an air preheater 12; the flue gas outlet of the rear-end flue of the partition plate is connected to the air inlet of the water supply preheater 11, the air outlet of the water supply preheater 11 is connected to the flue gas inlet of the air preheater 12, the flue gas outlet of the air preheater 12 is connected to the air inlet of the boiler induced draft fan 13, and the air outlet of the boiler induced draft fan 13 is connected to the air inlet of the bag filter 25 through a branch flue gas pipeline; this system also includes a booster induced draft fan 29, and the air outlet of the bag filter 25 is connected to the chimney 32 through the booster induced draft fan 29. The injection port of the desulfurization agent injection and distribution system is connected to the branch flue gas pipeline between the induced draft fan 13 and the bag filter 25. In this way, the flue gas after denitration is sequentially cooled by heat exchange through the water supply preheater 11 and the air preheater 12, and is sent into the bag filter 25 by the boiler induced draft fan 13; the desulfurization agent is injected into the flue gas through the desulfurization agent injection and distribution system, is thermally activated in the flue, the specific surface area increases rapidly, makes full contact with the flue gas, and physical and chemical reactions occur. Acidic substances such as SO2 in the flue gas are absorbed and purified, realizing full contact between the desulfurization agent and the flue gas, and making the reaction conditions reach the best; after the flue gas after desulfurization is dust-removed by the bag filter 25, it is discharged from the chimney 32 through the booster induced draft fan 29.

[0019] Figure 1 As shown in the figure, the desulfurization agent injection and distribution system of the flue gas denitration and desulfurization system of this gas boiler includes a desulfurization agent bin 14, a vibration motor 15, a discharge control valve 16, a mill small hopper 17, a mixing motor 18, a metering screw motor 19, a grinder 20, a fine desulfurization agent bin 21, a conveying fan 22, an injection valve 23, and an injection and distribution device 24. The lower outlet of the desulfurization agent bin 14 is sequentially connected to the inlet of the fine desulfurization agent bin 21 through the discharge control valve 16, the mill small hopper 17, the metering screw motor 19, and the grinder 20; the vibration motor 15 is arranged at the lower outlet of the desulfurization agent bin 14, and the mixing motor 18 is arranged in the mill small hopper 17. The fine desulfurization agent bin 21 is connected to the injection and distribution device 24 through the conveying fan 22 and the injection valve 23, and the injection outlet of the injection and distribution device 24 is connected to the branch flue gas pipeline between the induced draft fan 13 and the bag filter 25. After adopting such a structure, the desulfurization agent in the desulfurization agent bin 14 is vibrated and fed by the vibration motor 15, sent into the mill small hopper 17 through the discharge control valve 16, stirred and mixed evenly by the mixing motor 18, then metered by the metering screw motor 19 and sent into the grinder 20 and ground into fine desulfurization agent, and enters the fine desulfurization agent bin 21; the fine desulfurization agent in the fine desulfurization agent bin 21 is powered by the conveying fan 22, sprayed into the injection and distribution device 24 through the injection valve 23, and then sprayed into the flue gas by the injection and distribution device 24.

[0020] Figure 1As shown in the figure, the flue gas denitrification and desulfurization system of this gas boiler further includes a damper 30 and a seal fan 31. The outlet of the boiler induced draft fan 13 is connected to the chimney 32 through another branch flue gas pipeline, and the damper 30 is arranged on this branch flue gas pipeline. The air outlet of the seal fan 31 is connected to the branch flue gas pipeline between the outlet of the boiler induced draft fan 13 and the damper 30.

[0021] Figure 1 As shown in the figure, the flue gas denitrification and desulfurization system of this gas boiler further includes a pulse valve 26, an ash conveying device 27 and a ton bag packing machine 28. The air inlet of the pulse valve 26 is connected to the compressed air source, and the air outlet is connected to the soot blowing port of the bag filter 25; the ash outlet of the bag filter 25 is connected to the ton bag packing machine 28 through the ash conveying device 27. In this way, large-particle dust in the flue gas is captured by the bag filter 25 and falls into the bottom cone tank, and is sent into the ton bag packing machine 28 through the ash conveying device 27. The desulfurized ash after being packed by the ton bag packing machine 28 is transported out for comprehensive utilization; when the dust accumulated on the filter bag surface in the bag filter 25 reaches a certain amount, the pulse valve 26 is opened for spraying to shake off the dust on the filter bag, which falls into the bottom cone tank and is sent into the ton bag packing machine 28 through the ash conveying device 27.

[0022] Figure 1 As shown in the figure, the denitrification and desulfurization process flow of the flue gas denitrification and desulfurization system of this gas boiler is as follows:

[0023] Flue gas denitrification purification: The gas boiler 1 selects flue gas with a window temperature of 320 - 420 °C to enter the denitration tower 2. Ammonia water with a concentration of not less than 20 vol% as a reducing agent is evaporated by the ammonia supply pump 4 through the ammonia evaporator 5, and after being diluted by the compressed air from the compressed air package 8, it is sprayed into the front flue of the denitration tower 2 through the ammonia injection device 6. After the NH3 gas is fully mixed with the flue gas, it enters the 3-layer catalyst layer of the denitration tower 2 from top to bottom for denitration reaction. NO in the flue gas x completes the redox reaction with NH 3 to generate non-toxic components such as N2 and H2O; its main reactions are 4NO + 4NH3 + O2 → 4N2 + 6H2O, 2NO2 + 4NH3 + O2 → 3N2 + 6H2O; the side reactions are 4NH4OH + 3O2 → 2N2 + 10H2O, 4NH4OH + 5O2 → 4NO + 10H2O.

[0024] Flue gas desulfurization purification: After the flue gas is denitrified in the denitration tower 2 to remove NO in the flue gas xAfter that, the boiler feed water is heated by the feed water preheater 11, and then the combustion air of the boiler is heated by the air preheater 12. The denitrified flue gas is transported by the boiler induced draft fan 13 to the flue gas pipeline of the desulfurization system in front of the bag filter 25. The sodium bicarbonate powder deacidifying agent with a particle size of 20 - 50 mesh is ground into ultrafine sodium bicarbonate dry powder with D90 ≤ 20 μm by the grinder 20, and is sprayed into the flue through the spraying and distributing device 24. It is thermally activated in the flue, and its specific surface area increases rapidly. The ultrafine sodium bicarbonate powder decomposes into highly active sodium carbonate and carbon dioxide under the action of high-temperature flue gas. The highly active sodium carbonate fully contacts with SO2 and other acidic media in the flue gas and undergoes a chemical reaction, being absorbed and purified; the main chemical reactions are 2NaHCO3 + SO2 + 1 / 2O2 → Na2SO4 + 2CO2 + H2O, 2NaHCO3 + SO3 → Na2SO4 + 2CO2 + H2O; the reactions with other acidic substances are NaHCO3 + HCL → NaCl + CO2 + H2O; NaHCO3 + HF → NaF + CO2 + H2O.

[0025] Flue gas dust removal and purification: The flue gas containing powder after absorbing acidic substances such as SO2 and drying enters the bag filter 25 for gas-solid separation and flue gas re-purification, further desulfurization reaction, dust purification and dust collection by filtration. The desulfurized and dust-removed ash is transported by the ash conveying device 27 to the ton bag packing machine 28 for packing and external transportation. The flue gas after desulfurization and dust removal enters the chimney through the booster induced draft fan 29, realizing the collection of desulfurized ash and the discharge of the flue gas with the dust concentration meeting the standard.

[0026] Figure 1 As shown in the figure, the startup of the flue gas denitrification and desulfurization system of this gas boiler is carried out in the following steps:

[0027] a. Startup of the flue gas system:

[0028] (1) Before starting the boiler flue gas system, keep the baffle door 30 of the boiler flue gas bypass in the closed state;

[0029] (2) Open the electric valve in front of the booster induced draft fan 29 and the flue gas electric regulating valve behind the boiler induced draft fan 13;

[0030] (3) Start the booster induced draft fan 29, slowly increase the frequency of the fan motor, initially set it to 15 Hz, and slowly increase the operating frequency of the fan until it is stable;

[0031] (4) After starting, the boiler flue gas is discharged into the chimney through denitrification, desulfurization and dust removal.

[0032] (5) Operation adjustment. Adjust the fan output according to the outlet pressure of the booster induced draft fan 29.

[0033] b. Startup of the denitrification system:

[0034] (1) Open the inlet and outlet valves of the compressed air package 8 and the compressed air inlet valve of the ammonia injection device 6 in sequence, and adjust the compressed air pressure to be 0.3 - 0.4 Mpa.

[0035] (2) Open the inlet valve of the ammonia water pipeline of the ammonia injection device 6, the inlet and outlet valves of the ammonia water evaporator 5, and the ammonia water inlet and outlet valves of the ammonia supply pump 4 in sequence, and start the ammonia supply pump 4.

[0036] (3) According to the inlet flue gas temperature and the NO x concentration at the outlet of the denitration tower 2, adjust the frequency conversion of the ammonia supply pump 4 to control the required amount of ammonia water and meet the denitration efficiency requirements.

[0037] c. Activation of the desulfurization system:

[0038] (1) Open the outlet valve of the delivery fan 22;

[0039] (2) Start the grinder 20;

[0040] (3) Open the feeding valve of the small hopper 17 of the grinder and start the mixing motor 18;

[0041] (4) Start the vibration motor 15 of the desulfurizer bin 14 and open the discharge control valve 16;

[0042] (5) Adjust the operation of the desulfurization system;

[0043] (6) Conduct interlocked control of the feeding between the material level of the small hopper 17 of the grinder and the discharge control valve 16 under the desulfurizer bin 14; pay attention to the outlet flow of the delivery fan 22, and adjust the powder conveying screw frequency of the metering screw motor 19 equipped with the grinder system according to the SO2 concentration at the outlet of the flue gas. During the initial operation of the system, it should be ensured that there is desulfurizer in the desulfurizer bin 14.

[0044] d. Activation of the dust removal system:

[0045] (1) Adjust the injection pressure, pulse frequency, and pulse width of the bag filter 25;

[0046] (2) Start the ash conveying device 27;

[0047] (3) During operation, pay attention to the differential pressure at the inlet of the bag filter 25, the inlet flue gas temperature, and the parameters of each instrument.

[0048] An embodiment of this gas boiler flue gas denitration and desulfurization system is as follows:

[0049] 1. Flue gas denitration:

[0050] The process pipeline at the top inlet of the denitration tower 2 is connected to the flue gas outlet of the flue before the baffle of the gas-fired boiler 1 by a steel pipe with a diameter of 1200 mm. The process pipeline at the lower outlet of the denitration tower 2 is connected to the flue gas duct behind the baffle of the gas-fired boiler 1 by a steel pipe with a diameter of 1200 mm and a wall thickness of 8 mm. The outlet of the ammonia injection device 6 is connected to the process pipeline of the flue gas inlet of the denitration tower 2 by a nozzle with a diameter of 15#, 304. The process pipeline connecting the bottom inlet of the ammonia injection device 6 to the outlet of the ammonia water evaporator 5 is made of a 15# stainless steel pipe. The process pipeline connecting the side inlet of the ammonia injection device 6 to the upper outlet of the compressed air package 8 is made of a 20# stainless steel pipe. The process pipeline connecting the inlet of the ammonia water evaporator 5 to the outlet of the ammonia supply pump 4 is made of a 15# stainless steel pipe. The process pipeline connecting the inlet of the ammonia supply pump 4 to the lower outlet of the ammonia water tank 3 is made of a stainless steel pipe with a diameter of 32 mm. The process pipeline connecting the upper feed port of the ammonia water tank 3 to the outlet of the ammonia unloading pump 7 is made of a stainless steel pipe with a diameter of 32 mm. The process pipeline connecting the inlet of the ammonia unloading pump 7 to the external process pipeline is made of a stainless steel pipe with a diameter of 32 mm. The ammonia water evaporator 5 uses electric heating. The process pipeline connecting the soot blower 9 of the three catalyst layers of the denitration tower 2 to the upper outlet of the compressed air package 8 is made of 304 stainless steel with a diameter of 50 mm. The process pipeline connecting the middle inlet of the compressed air package 8 to the externally supplied compressed air (or nitrogen) is made of 304 stainless steel with a diameter of 80 mm.

[0051] The process pipeline connecting the outlet of the air preheater 12 to the inlet of the boiler induced draft fan 13 is made of a steel pipe with a diameter of 1200 mm. The process pipeline of the branch flue gas pipeline at the outlet of the boiler induced draft fan 13 connected to the inlet of the bag filter 25 is made of a steel pipe with a diameter of 1400 mm. The flue between the branch flue gas pipeline at the outlet of the boiler induced draft fan 13 and the chimney is opened and closed by a baffle door 30 with a diameter of 1400 mm. The baffle door 30 is connected to the outlet process pipeline of the seal fan 31 with a diameter of 200 mm on the side of the branch flue gas pipeline at the outlet of the boiler induced draft fan 13, serving as a partition and seal between the baffle door 30 for the direct connection between the outlet of the boiler induced draft fan 13 and the chimney.

[0052] The ammonia water tank 3 is selected with a volume of 15 m 3 ; The ammonia unloading pump 7 is selected as self-priming type, with a flow rate of 20 m 3 / h, a head of 20 m, a material of 304, and an explosion-proof grade of ExdⅡBT4; The ammonia supply pump 4 is selected with a flow rate of 0.01 - 1 m 3 / h, a head of 20 m, a material of 304, and an explosion-proof grade of ExdⅡBT4; The compressed air package 8 is selected with V = 5 m 3 、P = 1.0 MPa.

[0053] 2. Flue gas desulfurization:

[0054] The desulfurizer silo 14 is selected as a 3 m³ silo, and the vibrating motor 15 at its lower outlet is selected with a power of 25 W. The pipe connecting the bottom outlet of the desulfurizer silo 14 to the inlet of the discharge control valve 16 is made of a steel pipe with a diameter of 200 mm; the pipe connecting the outlet of the discharge control valve 16 to the inlet of the small hopper 17 of the mill is made of a steel pipe with a diameter of 200 mm; the pipe connecting the bottom outlet of the small hopper 17 of the mill to the inlet of the metering screw motor 19 is made of a steel pipe with a diameter of 150 mm; the pipe connecting the outlet of the metering screw motor 19 to the inlet of the grinder 20 for desulfurizer is made of a steel pipe with a diameter of 150 mm; the pipe connecting the outlet of the grinder 20 to the inlet of the fine desulfurizer silo 21 is made of a steel pipe with a diameter of 100 mm; the pipe connecting the outlet of the fine desulfurizer silo 21 to the inlet of the conveying fan 22 is made of a steel pipe with a diameter of 100 mm; the pipe connecting the outlet of the conveying fan 22 to the inlet of the injection valve 23 is made of a steel pipe with a diameter of 80 mm; the pipe connecting the outlet of the injection valve 23 to the inlet of the high-efficiency desulfurizer injection and distribution device 24 is made of a steel pipe with a diameter of 80 mm; the outlet of the high-efficiency desulfurizer injection and distribution device 24 is connected to the flue gas pipe at the outlet of the boiler induced draft fan 13, so that the desulfurizer can be in full contact with the flue gas in the flue through the high-efficiency desulfurizer injection and distribution device 24 to absorb and purify acidic substances such as SO₂ in the flue gas.

[0055] 3. Flue gas dust removal:

[0056] The flue gas pipe connecting the inlet of the bag filter 25 to the outlet of the boiler induced draft fan 13 is made of a steel pipe with a diameter of 1400 mm; the pipe connecting the upper outlet of the bag filter 25 to the inlet of the booster induced draft fan 29 is made of a steel pipe with a diameter of 1400 mm, and the pipe connecting the outlet of the booster induced draft fan 29 to the bottom of the chimney is made of a steel pipe with a diameter of 1400 mm. The booster induced draft fan 29 is selected with a flow rate of 8500 - 20000 Nm 3 / h and a pressure of 6000 Pa; the pipe connecting the end outlet of the ash conveying device 27 to the inlet of the ton bag packing machine 28 is made of a steel pipe with a diameter of 200 mm, and the outlet of the ton bag packing machine 28 is made of a steel pipe with a diameter of 200 mm; the pipes connecting several compressed air inlets at the top of the bag filter 25 to the outlets of the pulse valves 26 are made of steel pipes with a diameter of 50 mm, and the pipes connecting the inlets of the pulse valves 26 to the external compressed air are made of steel pipes with a diameter of 80 mm.

Claims

1. A flue gas denitrification and desulfurization system for a gas boiler, characterized in that: It includes a gas boiler (1), a denitration system, a boiler induced draft fan (13), a desulfurizing agent injection and distribution system, a bag filter (25) and a chimney (32); a partition plate (10) that separates the flue is provided in the flue of the gas boiler (1), the flue gas outlet of the flue in the front end of the partition plate is communicated with the flue gas inlet of the denitration system, and the flue gas outlet of the denitration system is communicated with the flue gas inlet of the flue in the rear end of the partition plate; the flue gas outlet of the flue in the rear end of the partition plate is successively communicated with the boiler induced draft fan (13) and the bag filter (25), and the gas outlet of the bag filter (25) is communicated with the chimney (32); the injection port of the desulfurizing agent injection and distribution system is communicated with the process pipeline between the induced draft fan (13) and the bag filter (25).

2. The denitration and desulfurization system for the flue gas of a gas boiler according to claim 1, wherein: The denitration system includes a denitration tower (2), an ammonia water tank (3), an ammonia supply pump (4), an ammonia water evaporator (5), an ammonia injection device (6) and a compressed air package (8); the flue gas inlet of the denitration tower (2) is communicated with the flue gas outlet of the flue in the front end of the partition plate, and the flue gas outlet of the denitration tower (2) is communicated with the flue gas inlet of the flue in the rear end of the partition plate; the ammonia water tank (3) is successively communicated with the ammonia water steam inlet of the ammonia injection device (6) through the ammonia supply pump (4) and the ammonia water evaporator (5), and the compressed air inlet of the ammonia injection device (6) is communicated with the compressed air package (8); the injection port of the ammonia injection device (6) is communicated with the flue gas inlet pipeline of the denitration tower (2).

3. A flue gas denitrification and desulfurization system for a gas boiler according to claim 2, characterized in that: The denitration system is also provided with a soot blower (9); the compressed air package (8) is communicated with the soot blowing port of the denitration tower (2) through the soot blower (9).

4. A flue gas denitrification and desulfurization system for a gas boiler according to claim 1, characterized in that: The desulfurizing agent injection and distribution system includes a fine desulfurizing agent bin (21), a conveying fan (22), an injection valve (23) and an injection and distribution device (24); the fine desulfurizing agent bin (21) is communicated with the injection and distribution device (24) through the conveying fan (22) and the injection valve (23), and the injection outlet of the injection and distribution device (24) is communicated with the process pipeline between the induced draft fan (13) and the bag filter (25).

5. A flue gas denitrification and desulfurization system for a gas boiler according to claim 4, characterized in that: The desulfurizing agent injection and distribution system is also provided with a desulfurizing agent bin (14), a vibration motor (15), a discharging control valve (16), a mill hopper (17), a mixing motor (18), a metering screw motor (19) and a grinder (20); the lower outlet of the desulfurizing agent bin (14) is successively communicated with the inlet of the fine desulfurizing agent bin (21) through the discharging control valve (16), the mill hopper (17), the metering screw motor (19) and the grinder (20); the vibration motor (15) is arranged at the lower outlet of the desulfurizing agent bin (14), and the mixing motor (18) is arranged in the mill hopper (17).

6. A flue gas denitrification and desulfurization system for a gas boiler according to claim 1, characterized in that: It also includes a water supply preheater (11) and an air preheater (12); the water supply preheater (11) and the air preheater (12) are arranged between the flue gas outlet of the flue in the rear end of the partition plate (10) and the boiler induced draft fan (13).

7. A denitrification and desulfurization system for the flue gas of a gas boiler according to claim 1, characterized in that: It further includes a damper door (30) and a seal fan (31); the outlet of the boiler induced draft fan (13) is communicated with the chimney (32) through a branch flue gas pipeline and the damper door (30), and the air outlet of the seal fan (31) is communicated with the branch flue gas pipeline between the outlet of the boiler induced draft fan (13) and the damper door (30).

8. A flue gas denitrification and desulfurization system for a gas boiler according to any one of claims 1-7, characterized in that: It further includes an ash conveying device (27) and a ton bag packaging machine (28); the ash outlet of the bag filter (25) is communicated with the ton bag packaging machine (28) through the ash conveying device (27).

9. A flue gas denitrification and desulfurization system for a gas boiler according to claim 8, characterized in that: It further includes a pulse valve (26); the air inlet of the pulse valve (26) is communicated with a compressed air source, and the air outlet is communicated with the soot blowing port of the bag filter (25).

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