CN108201784A - A kind of grate-type biomass power plant boiler flue gas purification tapping equipment and its method - Google Patents

Abstract

The invention discloses a grate type biomass power plant boiler flue gas purification and discharge device and method thereof, comprising: a biomass boiler, an oxidation mixing device, a desulfurization tower, a bag filter, and a chimney, and a primary tuyere is arranged on the biomass boiler And the secondary air outlet, the outlet of the biomass boiler is connected to the desulfurization tower through the oxidation mixing device, the outlet of the desulfurization tower is connected to the bag filter, the first branch of the outlet of the bag filter is connected to the chimney, and the second branch passes through The circulation fan is connected with the primary tuyere and the secondary tuyere of the biomass boiler to form a circulation loop; through the optimization of desulfurization, denitration and dust removal processes, ultra-low emissions of pollutants such as sulfur dioxide, nitrogen oxides and dust in the flue gas of the biomass boiler are realized. The invention has little influence on the boiler, operates flexibly according to the load and actual pollutant conditions, facilitates the operation management of the whole biomass power plant system, is flexible in operation, saves water and saves operating costs.

Description

A grate type biomass power plant boiler flue gas purification and discharge device and method thereof

technical field

The invention relates to the field of power station tail gas discharge, in particular to a grate type biomass power plant boiler flue gas purification and discharge device and method thereof.

Background technique

Biomass boilers are boilers that use biomass energy such as crop stalks (corn stalks, sorghum stalks, wheat straw, rice straw, bean stalks, and cotton stalks, etc.), agricultural processing industry waste (rice husks), etc. as fuel. Biomass energy is characterized by renewability, low pollution, wide distribution and abundant total amount. The content of sulfur dioxide and nitrogen oxides in the exhaust gas of biomass boilers is relatively low, but with the improvement of national environmental protection standards for boiler flue gas emissions, biomass boilers have not adapted to the new environmental protection requirements.

Biomass boiler flue gas has the following characteristics:

(1) The temperature in the furnace varies greatly. Biomass boilers mainly include grate furnace and circulating fluidized bed furnace. 700～760℃, 800～950℃, 850～1100℃;

(2) The moisture content of the flue gas is high. Because the hydrogen content in the biomass is high, the moisture content in the flue gas is also high, which can reach about 15% to 30%, while the moisture content of the flue gas from a coal-fired boiler will not exceed 10%. ;

(3) The amount of flue gas dust is very large, and the ash-slag ratio after biomass combustion is (10:0-8:2). Due to the small particle size of the combustion dust and the large specific resistance, the dust removal of biomass-fired boilers is only suitable For bag filter, the bulk density is generally 0.18-0.5t/m ³ . Studies have shown that the main components of particulate matter emitted by biomass combustion are K2SO4, KCl and K2CO3, and the emission concentration is generally around 200mg/m3. The content of alkali metal in the soot is high, which can reach more than 8%.

(4) The concentrations of sulfur dioxide and nitrogen oxides are low and fluctuate greatly. When burning pure biomass, the contents of sulfur dioxide and nitrogen oxides fluctuate between 100 and 250mg/m3. The content of sulfur dioxide and nitrogen oxides in the air will fluctuate between 250-600mg/m3, and it can reach more than 1000mg/m3 instantaneously;

(5) The soot in the flue gas is easy to burn again, and the combustion is easy to coke. Since biomass cannot be completely combusted in the furnace, it cannot be re-combusted in the flue due to insufficient oxygen content. The larger dust will maintain the combustion temperature due to the short heat exchange time of the flue gas. Therefore, once the oxygen condition is met, such as placed in the air will burn again. The ash after combustion contains tar and other substances. Once the temperature of the equipment drops, it may cause coking and blockage. Considering the coking and corrosion of the boiler, the exhaust gas temperature may be 160-190 °C.

(6) The types of NOx emitted by general fuel combustion can be divided into rapid NOx, thermal NOx and fuel NOx. Rapid NOx generally accounts for less than 5% of the total amount, and has little impact; fuel-type NOx mainly comes from the oxidation of nitrogen-containing compounds in the fuel, and its formation is closely related to the nitrogen content in the fuel. When the nitrogen content in the fuel exceeds 0.1 %, the amount of NOx converted from fuel nitrogen will dominate; thermal NOx is mainly formed by oxidation of N2 in the air at high temperature (>1400°C) to form NOx (NO is the main form of NOx, accounting for 90% of the total amount of NOx %above). The combustion temperature of biomass boilers is 800-1000°C, so the type of NOx produced by the combustion of biomass boilers is mainly fuel-type NOx. Studies have shown that nitrogen in biomass mainly exists in the form of organic nitrogen such as protein and free amino acids, as well as some inorganic nitrogen. Therefore, NOx produced by biomass combustion mainly comes from the oxidation reaction of organic nitrogen. According to relevant boiler test data, when the oxygen content in the boiler flue gas is 12-15%, the NOx concentration is about 330-420mg/m3.

Based on the above shortcomings, the flue gas of the biomass boiler has caused adverse effects on the environment and brought pollution to the environment.

Contents of the invention

In view of the above defects or deficiencies, the object of the present invention is to provide a grate type biomass power plant boiler flue gas purification and discharge device and its method.

For achieving above object, technical scheme of the present invention is:

A grate-type biomass power plant boiler flue gas purification and discharge device, comprising: a biomass boiler, an oxidation mixing device, a desulfurization tower, a bag filter, and a chimney, wherein the biomass boiler is provided with a primary tuyere and a secondary The outlet of the biomass boiler is connected to the desulfurization tower through an oxidation mixing device, the outlet of the desulfurization tower is connected to the bag filter, and the outlet of the bag filter is divided into two paths: the first branch is connected to the chimney, and the second branch is connected to the chimney. The two branches are connected with the primary tuyere and the secondary tuyere of the biomass boiler through the recirculation fan to form a circulation loop; the biomass boiler is equipped with a denitrification atomizing nozzle, and the denitrification atomizing nozzle passes through the metering distribution device and the denitrification agent in turn. The pump is connected with the denitration agent tank; the oxidation mixing device is connected with an ozone generator and an oxygen generator; the desulfurization tower is provided with desulfurization atomizing nozzles, and the desulfurization atomizing nozzles are connected with desulfurization slurry tanks, process water tanks and A compressed air tank, the desulfurization agent tank is connected to the desulfurization slurry tank.

The desulfurization tower is equipped with a cyclone dust collector, and the outlet of the cyclone dust collector is connected with a feeder. On the one hand, it is connected with the desulfurization ash bin, and the desulfurization ash bin collects dust through the screw feeder; It is connected with the desulfurization tower to form a loop.

An ash collecting tank is arranged below the bag filter, and the ash collecting tank is connected with the desulfurization ash bin through the unloading device.

The outlet of the desulfurizing agent bin is connected to the inlet of the desulfurizing slurry tank through a screw feeder, a weighing and measuring device and a digester in sequence, and the gas inlet of the desulfurizing agent bin is connected to a compressed air tank.

Both the digester and the desulfurization slurry tank are connected with a water source.

The desulfurization slurry tank is connected to the desulfurization atomizing nozzle through a desulfurizing agent delivery pump; the process water tank is connected to the desulfurization atomizing nozzle through a feed water pump.

An induced draft fan is installed at the outlet of the bag filter; the second branch is also connected to the inlet of the desulfurization tower through a recirculation fan.

A desulfurization ash collection tank is arranged at the outlet of the desulfurization tower.

A method for purifying and discharging flue gas from a grate type biomass power plant boiler, comprising:

1) After the SNCR denitrification treatment is carried out in the biomass boiler, the EAS-FGR treatment process is adopted, and the exhaust gas is desulfurized through the desulfurization tower;

2) After the gas desulfurized by the desulfurization tower is dedusted by the bag filter, part of the clean flue gas after desulfurization and denitrification is discharged through the chimney, and the other part is sent to the secondary tuyere by the recirculation fan and enters the furnace for secondary combustion;

3) The ozone generated by the ozone generator is sent to the oxidation mixing device for turbulent mixing with the flue gas, and the ozone and the NO in the flue gas undergo a redox reaction, and the NO is converted into NO2 that is easy to absorb and remove; the flue gas after the reaction is mixed with the flue gas The desulfurized and denitrified net flue gas discharged from the outlet of the recirculation fan is mixed to ensure the stable operation of the fluidized bed under low load and not to collapse the bed.

The desulfurization tower is connected with a desulfurization slurry tank, and the desulfurization slurry tank is prepared with a desulfurization slurry with a concentration of 10-15%. After the air pollutants are reacted, they are further dedusted by the cyclone dust collector and the bag filter, and then enter the chimney to meet the emission standards.

Compared with prior art, the beneficial effects of the present invention are:

The invention provides a grate-type biomass power plant boiler flue gas purification and discharge device and method thereof, which are used for biomass boiler flue gas purification. Ultra-low emissions of pollutants such as sulfur dioxide, nitrogen oxides and dust in boiler flue gas. The present invention has little influence on the boiler, and can operate flexibly according to the load and actual pollutant conditions, and can also carry out coordinated processing of each sub-system, which facilitates the operation and management of the entire biomass power plant system, wherein the coordinated processing of the desulfurization and denitrification system is flexible in operation, It is easy to maintain, save water, and save operating costs. It can also adopt source NOx control, SNCR denitrification, oxidation enhanced denitrification and semi-dry desulfurization and denitrification synergistic NOx control technology according to the flue gas characteristics of the biomass boiler, which solves the problem of adopting SCR denitrification process investment. High cost, easy blockage, difficult operation and maintenance, etc.; in addition, desulfurization and denitrification products can be used as a beneficial supplement of Ca, S, and N elements in biomass ash, and can be used as compound fertilizers without secondary pollution. The invention has reliable performance, flexible operation, convenient maintenance and good economic and environmental benefits.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the device of the present invention.

In the figure, 1-secondary air outlet, 2-denitration atomizing nozzle, 3-metering and distribution device, 4-denitration pump, 5-denitration agent box, 6-compressed air tank, 7-desulfurization agent warehouse, 8-screw feeding Machine, 9-weighing and metering device, 10-digester, 11-desulfurization slurry tank, 12-desulfurization agent delivery pump, 13-desulfurization atomizing nozzle, 14-desulfurization tower, 15-feed water pump, 16-process water tank, 17 -cyclone dust collector, 18-feeder, 19-circulating ash box, 20-desulfurization ash bin, 21-screw feeder, 22-ash collection tank, 23-bag dust collector, 24-induced fan, 25-recycling Circulation fan, 26-desulfurization ash collection tank, 27-oxidation mixing device, 28-ozone generator, 29-oxygen generator, 30-primary tuyere, 31-chimney; 32-biomass boiler.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings. Apparently, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1, the present invention provides a kind of grate type biomass power plant boiler flue gas purification and discharge device, comprising: biomass boiler 32, oxidation mixing device 27, desulfurization tower 14, bag filter 23, and chimney 31, Wherein, the biomass boiler 32 is provided with a primary tuyere 30 and a secondary tuyere 1, the outlet of the biomass boiler 32 is connected to the desulfurization tower 14 through an oxidation mixing device 27, and the outlet of the desulfurization tower 14 is connected to the bag filter 23 The outlet of the bag filter 23 is divided into two paths: the first branch is connected with the chimney 31, and the second branch is connected with the primary air outlet 30 and the secondary air outlet 1 of the biomass boiler 32 through the recirculation fan 25, forming circulation loop; the biomass boiler 32 is provided with a denitrification atomizing nozzle 2, and the denitrification atomizing nozzle 2 is connected to the denitrification agent tank 5 through the metering distribution device 3 and the denitration agent pump 4 in sequence; the oxidation mixing device 27 is An ozone generator 28 and an oxygen generator 29 are connected; the desulfurization tower 14 is provided with a desulfurization atomizing nozzle 13, and the desulfurization atomizing nozzle 13 is connected with a desulfurization slurry tank 11, a process water tank 16 and a compressed air tank 6. The desulfurization agent tank 7 is connected to the desulfurization slurry tank 11 . Both the digester 10 and the desulfurization slurry tank 11 are connected to a water source. Exemplarily, the water source is a water supply source of the factory area.

Wherein, the desulfurization tower 14 is provided with a cyclone dust collector 17, and the outlet of the cyclone dust collector 17 is connected with a feeder 18. On the one hand, it is connected with the desulfurization ash bin 20, and the desulfurization ash bin 20 passes through the screw feeder 21. Dust is collected; the other side is connected to the desulfurization tower 14 through the circulating ash box 19 to form a loop. The outlet of the desulfurization tower 14 is provided with a desulfurization ash collection tank 26 .

Preferably, an ash collection tank 22 is provided below the bag filter 23, and the ash collection tank 22 is connected with the desulfurization ash bin 20 through a feeding device. An induced draft fan 24 is provided at the outlet of the bag filter 23 ; the second branch is also connected to the inlet of the desulfurization tower 14 through a recirculation fan 25 .

Specifically, the outlet of the desulfurizer bin 7 is connected to the inlet of the desulfurization slurry tank 11 through a screw feeder 8, a weighing and metering device 9 and a digester 10 in sequence, and the gas inlet of the desulfurizer bin 7 is connected to the compressed air tank 6. connect.

The desulfurization slurry tank 11 is connected to the desulfurization atomization nozzle 13 through the desulfurization agent delivery pump 12 ; the process water tank 16 is connected to the desulfurization atomization nozzle 13 through the feed water pump 15 .

The present invention also provides a method for purifying and discharging flue gas from a grate type biomass power plant boiler, comprising:

1), after the SNCR denitration treatment is carried out in the biomass boiler 32, the EAS-FGR treatment process is adopted, and the exhaust gas is desulfurized through the desulfurization tower 14;

2) After the gas desulfurized by the desulfurization tower 14 is dedusted by the bag filter 23, part of the desulfurized and denitrified clean flue gas is discharged through the chimney 31, and the other part is sent into the secondary tuyere 1 through the recirculation fan 25 and enters the furnace for a second time. combustion;

3), the ozone produced by the ozone generator 28 is sent to the oxidation mixing device 27 for turbulent mixing with the flue gas, the ozone and the NO in the flue gas undergo a redox reaction, and the NO is converted into NO2 which is easy to absorb and remove; the flue gas after the reaction The gas is mixed with the desulfurized and denitrified net flue gas discharged from the outlet of the recirculation fan 25 to ensure the stable operation of the fluidized bed under low load and not to collapse the bed.

Specifically, the biomass boiler 32 adopts the EAS-FGR treatment process for low nitrogen, and about 15-40% of the net flue gas after desulfurization and denitration treatment is sent to the secondary tuyere 1 through the recirculation fan 25 and enters the furnace for secondary combustion. Flue gas NOx concentration ≤ 180mg/Nm3; denitrification adopts SNCR process in the furnace, and the denitrification agent stored in the denitrification agent box 5 is pumped into the metering distribution device 3 by the denitrification agent pump 4 and then sent to the denitrification atomizing nozzle 2 to be atomized into droplets Then it enters the boiler furnace and undergoes oxidation-reduction reaction with high-temperature flue gas, and the denitrification efficiency is not less than 45%. The NOx concentration after the synergistic treatment of the two processes is ≤100mg/Nm3, which can be flexibly operated according to the boiler load.

The desulfurized and denitrified clean smoke discharged from the outlet of the recirculation fan 25 is also sent to the oxidation mixing device 27 through the ozone generated by the ozone generator 28 for turbulent mixed oxidation with the flue gas treated by EAS-FGR and SNCR, desulfurization mist The alkaline slurry ejected from the chemical nozzle 13 further reacts with the flue gas sent to the desulfurization tower 14, and the flue gas from which most of the NOx is removed is further dedusted by the cyclone dust collector 17 and the bag filter 23, and then enters the chimney 30 and is discharged up to the standard. The ozone denitrification efficiency can reach more than 80%, and the NOx concentration in the treated flue gas is guaranteed to be ≤50mg/Nm3.

The purchased desulfurizing agent in the desulfurizing agent warehouse 7 is fed into the weighing and metering device 9 through the screw feeder 8, and then sent to the digester 10. The treated slurry is sent to the desulfurizing slurry tank 11 for further preparation into 10-15% desulfurizing slurry , through the desulfurization agent delivery pump 12 to the desulfurization atomizing nozzle 13, the atomized desulfurization slurry reacts with the flue gas pollutants in the desulfurization tower 14, and then is further dedusted by the cyclone dust collector 17 and bag filter 23, and then enters the chimney 30 to reach the standard Emission; SO2 concentration in flue gas after treatment is ≤35mg/Nm3, desulfurization efficiency is not less than 90%;

It should be noted that, according to the characteristics of the biomass boiler flue gas, the ash collected in the desulfurization tower 14, the cyclone dust collector 17 and the bag filter 23 can be used as fertilizer;

The invention can be used for flue gas purification of biomass boilers, and can realize ultra-low emission of pollutants such as sulfur dioxide, nitrogen oxides and dust in flue gas of biomass boilers through optimized design of desulfurization, denitrification, dust removal, especially denitrification processes. The invention has little influence on the boiler, can operate flexibly according to the load and actual pollutant conditions, and can also carry out coordinated processing of various sub-systems, so as to facilitate the operation and management of the whole biomass power plant system.

(1) Desulfurization and denitrification system coordinated processing, flexible operation, easy maintenance, water saving and operating cost saving;

(2) According to the flue gas characteristics of the biomass boiler, the NOx control technology of source NOx control, SNCR denitrification, oxidation enhanced denitrification and semi-dry desulfurization and denitrification is adopted to solve the high investment cost, easy blockage and difficult operation and maintenance of the SCR denitrification process And other issues;

(3) The desulfurization and denitrification products can be used as beneficial supplements of Ca, S, and N elements in biomass ash, and can be used as compound fertilizers without secondary pollution.

The invention has reliable performance, flexible operation, convenient maintenance and good economic and environmental benefits.

For those skilled in the art, it is obvious that the above-mentioned specific examples are only preferred solutions of the present invention, so those skilled in the art may make improvements and changes to some parts of the present invention, which still reflect the present invention. The principle of the present invention is still the object of the present invention, and all belong to the protection scope of the present invention.

Claims (10)

1. a kind of grate-type biomass power plant boiler flue gas purification tapping equipment, which is characterized in that including：Biomass boiler (32), oxidation mixing arrangement (27), desulfurizing tower (14), bag filter (23) and chimney (31), wherein, the biomass Primary air nozzle (30) and overfiren air port (1) are provided on boiler (32), the outlet of the biomass boiler (32) passes through oxidation Mixing arrangement (27) is connected with desulfurizing tower (14), and the outlet of desulfurizing tower (14) is connected with bag filter (23), and cloth bag removes The outlet of dirt device (23) is divided into two-way：The first branch is connected with chimney (31), the second branch by recirculation blower (25) with Biomass boiler (32) primary air nozzle (30) and overfiren air port (1) are connected, and form circulation loop；The biomass boiler (32) denitration atomizer (2) is provided on, metered dispensing unit (3) and denitration are passed sequentially through on denitration atomizer (2) Agent pump (4) is connected with denitrfying agent case (5)；Ozone generator (28) and oxygen processed are connected on the oxidation mixing arrangement (27) Machine (29)；Desulfurizing atomization nozzle (13) is provided on the desulfurizing tower (14), desulfurization slurry is connected on desulfurizing atomization nozzle (13) Liquid case (11), technique water tank (16) and compressed air cylinder (6) are connected with desulfurizing agent storehouse (7) on the desulfurization slurry case (11).

2. grate-type biomass power plant boiler flue gas purification tapping equipment according to claim 1, which is characterized in that described Cyclone dust collectors (17) are provided on desulfurizing tower (14), blanking device (18) one is connected in the outlet of the cyclone dust collectors (17) Aspect is connected with desulfurization ash cellar (20), and desulfurization ash cellar (20) collects dust by screw feeder (21)；The opposing party is by following Ring cinder box (19) is connected forming circuit with desulfurizing tower (14).

3. grate-type biomass power plant boiler flue gas purification tapping equipment according to claim 2, which is characterized in that described Ash collection slot (22) is provided with below bag filter (23), ash collection slot (22) is connected by blanking device with desulfurization ash cellar (20) It connects.

4. grate-type biomass power plant boiler flue gas purification tapping equipment according to claim 1, which is characterized in that described The outlet in desulfurizing agent storehouse (7) passes sequentially through screw(-type) feeder (8), Weighing device (9) and digester (10) and is starched with desulfurization Liquid case (11) entrance is connected, and the gas access of desulfurizing agent storehouse (7) is connected with compressed air cylinder (6).

5. grate-type biomass power plant boiler flue gas purification tapping equipment according to claim 4, which is characterized in that described Water source is respectively connected on digester (10) and desulfurization slurry case (11).

6. the grate-type biomass power plant boiler flue gas purification tapping equipment according to claim 1 or 4, which is characterized in that The desulfurization slurry case (11) is connected by desulfurizing agent delivery pump (12) with desulfurizing atomization nozzle (13)；The technique water tank (16) it is connected by feed pump (15) with desulfurizing atomization nozzle (13).

7. grate-type biomass power plant boiler flue gas purification tapping equipment according to claim 1, which is characterized in that described The exit of bag filter (23) is provided with air-introduced machine (24)；The second branch is gone back by recirculation blower (25) and desulfurizing tower (14) entrance is connected.

8. grate-type biomass power plant boiler flue gas purification tapping equipment according to claim 1, which is characterized in that described The exit of desulfurizing tower (14) is provided with Desulphurization collecting tank (26).

9. one kind is based on grate-type biomass power plant boiler flue gas purification discharge method according to claim 1, feature It is, including：

1) after, carrying out SNCR denitration processing in biomass boiler (32), using EAS-FGR treatment process, discharge gas is passed through Desulfurizing tower (14) carries out desulfurization process；

2) after, the gas after desulfurizing tower (14) desulfurization process is by bag filter (23) dedusting, treated for desulphurization denitration only A flue gas part is discharged by chimney (31), and another part is sent into overfiren air port (1) into burner hearth by recirculation blower (25) Second-time burning；

3), ozone generator (28) generate ozone send to oxidation mixing arrangement (27) with flue gas carry out turbulent closure scheme, ozone with Redox reaction occurs for the NO in flue gas, and NO is converted into the NO2 of easy absorbing and removing；Flue gas and recirculation blower after reaction (25) desulphurization denitration treated the neat stress mixing of outlet discharge ensures that the stable operation of underload fluidized bed at elevated, do not collapse bed.

10. one kind is based on grate-type biomass power plant boiler flue gas purification discharge method according to claim 9, feature It is, desulfurization slurry case (11) is connected on the desulfurizing tower (14), it is formulated with a concentration of 10 in desulfurization slurry case (11)~ 15% desulfurization slurry, desulfurization slurry by desulfurizing agent delivery pump (12) to desulfurizing atomization nozzle (13), the desulfurization slurry after atomization It is further removed through removing cyclone dust collectors (17) and bag filter (23) again after desulfurizing tower (14) is reacted with flue gas pollutant Enter chimney (30) qualified discharge after dirt.