A circulating fluidized bed fly ash heating furnace coupled fly ash melting device and method

Abstract

A circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device and method belongs to the field of harmless and resource-based treatment of fly ash from waste incineration. The flue gas outlet of the circulating fluidized bed combustion chamber is connected to a high-efficiency cyclone separator 1, the discharge port of which is connected to a return valve. The outlet on one side of the return valve is connected to the combustion chamber, while the outlet on the other side of the return valve is connected to a high-temperature melting furnace. The flue gas outlet of the high-efficiency cyclone separator 1 is connected to the second combustion chamber and the first waste heat boiler. The flue gas outlet of the high-temperature melting furnace is connected to the second waste heat boiler, which is connected to the second waste heat boiler. The flue gas outlet of the first waste heat boiler and the second waste heat boiler is connected to the second high-efficiency cyclone separator. The flue gas outlets of the first waste heat boiler and the second high-efficiency cyclone separator are connected to a quenching tower. The quenching tower flue gas outlet is connected to a bag filter, the flue gas cooling side of a flue gas-flue gas heater, a wet scrubber, the flue gas heating side of a flue gas-flue gas heater, a steam-flue gas heater, an SCR denitrification device, and the flue gas inlet of an economizer. The present invention is used for high-temperature melting of fly ash.

Description

Technical Field

[0001] The present invention belongs to the field of harmless and resourceful treatment of fly ash from garbage incineration, and particularly relates to a circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device and method. Background Art

[0002] According to statistics, by 2023, the number of municipal solid waste incineration plants nationwide exceeded 900, with a daily incineration capacity of 861,800 tons. 220 million tons of waste were incinerated annually, and 240 million tons were projected for incineration in 2024. Fly ash generated from incineration accounts for 3-5% of the total waste volume, or 9.6 million tons annually at a 4% rate. Fly ash, captured by the flue gas purification systems of incineration plants, contains organic pollutants such as heavy metals (Pb, Zn, Cr, Ni, Cu, Cd, and Hg), soluble salts (primarily chlorides of Ca, Na, and K, accounting for 20-30% of the fly ash weight), and dioxins (0.8-6.7 ngTEQ / g), making it a hazardous waste. Currently, the primary method for disposing of fly ash is chelation pretreatment followed by landfill. However, landfilling requires significant land resources, requires high construction investment, is difficult to operate and maintain, and still presents significant environmental risks. With the shortage of landfill land and increasing environmental protection requirements, the reduction, harmlessness and resource utilization of fly ash will become the hot spots and difficulties in the development of the industry.

[0003] The fly ash disposal industry is currently promoting a diverse range of fly ash disposal methods, including low-temperature thermal decomposition, high-temperature sintering, and high-temperature melting. The first two methods are currently in pilot stages and suffer from incomplete treatment. High-temperature melting, which typically utilizes electrothermal melting (graphite electrodes and plasma), suffers from short refractory and plasma gun lifespans and high operating costs. The fly ash must be washed to remove chloride salts, dried, and then electrothermally melted. Operating costs are reportedly as high as 4,000 yuan per ton of fly ash. Therefore, innovative high-temperature fly ash melting technologies are needed to address refractory lifespan issues while significantly reducing operating costs. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of short refractory life and high operating costs in the current high-temperature melting method for fly ash disposal, and to propose a circulating fluidized bed fly ash heating furnace coupled fly ash melting device and method.

[0005] Experimental studies have found that fly ash can reduce its weight by 20-25% when thermally decomposed at 900-1000°C, including some crystalline water and volatile chloride salts (NaCl, KCl, PbCl2, ZnCl2, Fe2Cl3, etc.), and the fly ash aggregates into small particles after heating, with a particle size of 50-200μm. Therefore, it is proposed to first subject the fly ash to high-temperature heat treatment (relative to water washing dechlorination, this method is simply referred to as hot washing dechlorination) to remove most of the chloride salts, and then enter the high-temperature melting furnace for treatment. This can greatly increase the life of the refractory material, thereby reducing the operating costs of fly ash disposal. To this end, a circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device and method is proposed. Laboratory verification has found that it can greatly increase the life of the refractory material. At the same time, the circulating fluidized bed and the melting furnace use biomass as auxiliary fuel, which greatly reduces operating costs.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device, the melting device comprising a circulating fluidized bed, a return valve, a primary fan, a secondary combustion chamber, a high-temperature melting furnace, a quenching tower, a bag filter, a fly ash water washing device, a flue gas-flue gas heater, a wet scrubber, a steam-flue gas heater, an SCR denitrification device, an economizer, two high-efficiency cyclone separators, and two waste heat boilers; the two high-efficiency cyclone separators are high-efficiency cyclone separator 1 and high-efficiency cyclone separator 2, and the two waste heat boilers are waste heat boiler 1 and waste heat boiler 2;

[0008] The side wall of the circulating fluidized bed is provided with a fly ash port, a biomass port, a conditioning agent port and a secondary air port, which are all corresponding to the circulating fluidized bed combustion chamber, and the primary fan outlet is connected to the wind chamber at the bottom of the circulating fluidized bed combustion chamber; the flue gas outlet at the top of the circulating fluidized bed combustion chamber is connected to the flue gas inlet of the high-efficiency cyclone separator, and the discharge port at the lower end of the high-efficiency cyclone separator is connected to the return valve, and the outlet on one side of the return valve is connected to the return port of the circulating fluidized bed combustion chamber, and the outlet on the other side of the return valve is connected to the inlet of the high-temperature melting furnace through the high-temperature fly ash inlet pipe of the melting furnace; the flue gas outlet at the top of the high-efficiency cyclone separator is connected to the secondary combustion chamber in turn. The flue gas outlet of the high-temperature melting furnace is connected with the flue gas inlet of the waste heat boiler 2, and the flue gas outlet of the waste heat boiler 2 is connected with the high-efficiency cyclone separator 2; the flue gas outlet of the waste heat boiler 1 and the flue gas outlet of the high-efficiency cyclone separator 2 are both connected with the flue gas inlet of the quenching tower, and the flue gas outlet of the quenching tower is connected with the flue gas cooling side of the flue gas-flue gas heater, the wet scrubber, the flue gas heating side of the flue gas-flue gas heater, the steam-flue gas heater, the SCR denitrification device and the flue gas inlet of the economizer in sequence; the ash discharge port at the bottom of the quenching tower and the ash discharge port at the bottom of the bag dust collector are both connected with the ash inlet of the fly ash water washing device.

[0009] Furthermore, a regulating valve is installed at the outlet on the other side of the return valve.

[0010] Furthermore, the fly ash port on the side wall of the circulating fluidized bed combustion chamber is connected to the outlet of the fly ash bin through a first screw feeder; the biomass port on the side wall of the circulating fluidized bed combustion chamber is connected to the outlet of the biomass bin through a second screw feeder; and the conditioning agent port on the side wall of the circulating fluidized bed combustion chamber is connected to the outlet of the conditioning agent bin through a third screw feeder.

[0011] Furthermore, the high-temperature fly ash inlet pipe of the melting furnace is connected to the outlet of the biomass powder bin through a screw feeder 4.

[0012] Furthermore, the secondary air inlet on the side wall of the circulating fluidized bed combustion chamber is connected to the outlet of the secondary air fan.

[0013] Furthermore, the bottom end of the secondary air outlet is 3-5m away from the air distribution plate of the circulating fluidized bed.

[0014] A circulating fluidized bed fly ash heating furnace coupled fly ash melting method, the method comprising the following steps:

[0015] Step 1: Primary air is introduced into the wind chamber at the bottom of the circulating fluidized bed combustion chamber. At the same time, fly ash, biomass and conditioning agent are respectively sent into the circulating fluidized bed combustion chamber for combustion, and secondary air is sent into the circulating fluidized bed from the secondary air port. The circulating fluidized bed is an adiabatic furnace with a furnace temperature of 900-1000°C. The high-temperature flue gas discharged through the flue gas outlet at the upper end of the circulating fluidized bed combustion chamber enters the high-efficiency cyclone separator 1. Urea or ammonia water is sprayed into the high-temperature flue gas before entering the high-efficiency cyclone separator 1 for SNCR denitrification; the high-efficiency cyclone separator 1 separates the fly ash carried in the high-temperature flue gas and sends it into the circulating fluidized bed from one side outlet of the bottom return valve of the high-efficiency cyclone separator 1 to form a fly ash circulation; the outlet on the other side of the return valve sends part of the fly ash into the high-temperature melting furnace through a regulating valve, and the burner 2 of the high-temperature melting furnace heats the fly ash entering the high-temperature melting furnace to 1300-1400°C to achieve fly ash melting;

[0016] Step 2: The high-temperature flue gas of 900-1000℃ discharged from the flue gas outlet at the top of the high-efficiency cyclone separator 1 enters the secondary combustion chamber. The flue gas temperature is heated to 1100℃ under the support of the burner 1 in the secondary combustion chamber. The residence time is greater than 2s. After that, it enters the waste heat boiler 1. The flue gas temperature drops to 500-550℃ before entering the quenching tower.

[0017] Step 3: Flue gas discharged from the flue gas outlet of the high-temperature melting furnace enters the second waste heat boiler. Urea or ammonia water is sprayed into the 1000-1050°C range of the second waste heat boiler for SNCR denitrification. After the flue gas cools to 500-550°C in the second waste heat boiler, it enters the second high-efficiency cyclone separator. The separated fly ash is sent back to the fly ash bin in front of the furnace. The clean flue gas enters the quenching tower from the upper outlet of the second high-efficiency cyclone separator.

[0018] Step 4: The two flue gases merge in a quenching tower and are cooled to 200°C before entering a bag-type dust collector. Activated carbon is sprayed into the flue gas connecting the bag-type dust collector and the quenching tower to adsorb heavy metals and dioxins in the flue gas. The flue gas then enters a flue gas heater, where the flue gas temperature drops to 105°C. The flue gas then enters a wet scrubber, where NaOH is used to neutralize HCl, SO2, and HF in the flue gas. The concentrated brine discharged from the bottom of the wet scrubber serves as cooling water for the quenching tower. The ash discharged from the bottom of the quenching tower merges with the ash captured by the bag-type dust collector and enters the fly ash washing device to separate the miscellaneous salts and fly ash. The fly ash is then dried and sent to the pre-furnace fly ash silo. The 62°C clean flue gas discharged from the wet scrubber is heated to 157°C by a flue gas heater and then to 170-210°C by a steam-type flue gas heater before entering the SCR denitrification device. It is then cooled to 130-150°C by an economizer and discharged into the atmosphere.

[0019] Furthermore, in step 1, the mass ratio of the fly ash, biomass and conditioning agent is 100:20-30:20-30.

[0020] Furthermore, in step one, the burner two uses biomass powder as fuel, requiring the biomass powder to have a particle size less than 0.5 mm, a moisture content less than 10%, and a calorific value greater than 3500 Kcal / kg, and heats the fly ash entering the high-temperature melting furnace to 1300-1400° C. to achieve fly ash melting.

[0021] The beneficial effects of the present invention relative to the prior art are:

[0022] The present invention adopts a circulating fluidized bed to heat fly ash to 900-1000℃ and uses biomass as auxiliary fuel, which significantly reduces operating costs. Due to the "hot washing" process, most of the volatile chloride salts in the fly ash enter the flue gas of the circulating fluidized bed, which significantly reduces the chloride salt content in the fly ash entering the melting furnace, thereby greatly slowing down the corrosion rate of the high-temperature melting furnace refractory materials and significantly increasing the service life. The fly ash collected by the tail bag dust collector only accounts for about 30% of the original fly ash. This part of the fly ash only needs to be washed with water (the obtained miscellaneous salts are recovered and the fly ash is then sent to the fly ash bin in front of the furnace). Compared with the existing process (first washing all the fly ash with water), the operating cost is greatly reduced. Wet washing, bag dust removal and SNCR+SCR denitrification process are adopted to achieve ultra-low tail gas emissions (the SCR denitrification device reduces the NOx concentration in the flue gas to less than 50mg / Nm 3, O2=11%; with the previous bag dust removal and wet scrubbing, the NOx in the exhaust gas is ≤50mg / Nm 3 、SO2≤35mg / Nm 3 , dust ≤ 10mg / Nm 3 , corresponding to O2 = 11%). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device according to the present invention.

[0024] Figure 1 The names and reference numerals of the components are as follows:

[0025] Circulating fluidized bed 1, high-efficiency cyclone separator 2, regulating valve 3, return valve 4, primary fan 5, secondary fan 6, fly ash bin 7-1, screw feeder 1 7-2, biomass bin 8-1, screw feeder 2 8-2, conditioning agent bin 9-1, screw feeder 3 9-2, SNCR port 10, burner 1 11, secondary combustion chamber 12, waste heat boiler 1 13, burner 2 14, high-temperature melting furnace 15, water quenching and slagging Machine 16, SNCR port 2 17, waste heat boiler 2 18, high-efficiency cyclone separator 2 19, quenching tower 20, bag dust collector 21, fly ash washing device 22, flue gas-flue gas heater 23, wet scrubber 24, steam-flue gas heater 25, SCR denitrification device 26, economizer 27, induced draft fan 28, melting furnace high-temperature fly ash inlet pipe 29, biomass powder silo 29-1, screw feeder 4 29-2. DETAILED DESCRIPTION

[0026] Specific implementation method 1: Figure 1 As shown, this embodiment discloses a circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device, the melting device comprising a circulating fluidized bed 1, a return valve 4, a primary fan 5, a secondary combustion chamber 12, a high-temperature melting furnace 15, a quenching tower 20, a bag filter 21, a fly ash water washing device 22, a flue gas-flue gas heater 23, a wet scrubber 24, a steam-flue gas heater 25, an SCR denitrification device 26, an economizer 27, two high-efficiency cyclone separators, and two waste heat boilers; the two high-efficiency cyclone separators are high-efficiency cyclone separator 1 2 and high-efficiency cyclone separator 2 19, and the two waste heat boilers are waste heat boiler 1 13 and waste heat boiler 2 18;

[0027] The side wall of the circulating fluidized bed 1 is provided with a fly ash port, a biomass port, a conditioning agent port and a secondary air port. The fly ash port, the biomass port, the conditioning agent port and the secondary air port are all corresponding to the combustion chamber of the circulating fluidized bed 1. The outlet of the primary fan 5 is connected to the wind chamber at the bottom of the combustion chamber of the circulating fluidized bed 1; the flue gas outlet at the top of the combustion chamber of the circulating fluidized bed 1 is connected to the flue gas inlet of the high-efficiency cyclone separator 2, and the discharge port at the lower end of the high-efficiency cyclone separator 2 is connected to the return valve 4. The outlet on one side of the return valve 4 is connected to the return port of the combustion chamber of the circulating fluidized bed 1, and the outlet on the other side of the return valve 4 is connected to the inlet of the high-temperature melting furnace 15 through the high-temperature fly ash inlet pipe 29 of the melting furnace; the flue gas outlet at the top of the high-efficiency cyclone separator 2 is connected to the inlet of the secondary combustion chamber 12 and the waste heat boiler 13 in turn. The flue gas outlet of the high-temperature melting furnace 15 is connected with the flue gas inlet of the waste heat boiler 18, and the flue gas outlet of the waste heat boiler 18 is connected with the high-efficiency cyclone separator 19; the flue gas outlet of the waste heat boiler 13 and the flue gas outlet of the high-efficiency cyclone separator 19 are both connected with the flue gas inlet of the quenching tower 20, and the flue gas outlet of the quenching tower 20 is connected with the flue gas cooling side of the flue gas-flue gas heater 23, the wet scrubber 24, the flue gas heating side of the flue gas-flue gas heater 23, the steam-flue gas heater (SGH) 25, the SCR denitrification device 26 and the flue gas inlet of the economizer 27 in sequence; the ash discharge port at the lower part of the quenching tower 20 and the ash discharge port at the lower part of the bag dust collector 21 are both connected with the ash inlet of the fly ash water washing device 22.

[0028] Furthermore, a regulating valve 3 is installed at the outlet on the other side of the return valve 4 for regulating the amount of fly ash entering the high-temperature melting furnace 15 .

[0029] Furthermore, the fly ash port on the side wall of the combustion chamber of the circulating fluidized bed 1 is connected to the outlet of the fly ash bin 7-1 through a screw feeder 7-2; the biomass port on the side wall of the combustion chamber of the circulating fluidized bed 1 is connected to the outlet of the biomass bin 8-1 through a screw feeder 8-2; the conditioning agent port on the side wall of the combustion chamber of the circulating fluidized bed 1 is connected to the outlet of the conditioning agent bin 9-1 through a screw feeder 9-2.

[0030] Furthermore, the high-temperature fly ash inlet pipe 29 of the melting furnace is connected to the outlet of the biomass powder bin 29-1 through the screw feeder 29-2 (the biomass powder is fed into the high-temperature fly ash inlet pipe 29 of the melting furnace. The biomass powder is violently pyrolyzed under the heating of the high-temperature fly ash to produce a large amount of combustible gas, which enters the burner 2 14 of the high-temperature melting furnace 15).

[0031] Furthermore, the secondary air inlet on the side wall of the combustion chamber of the circulating fluidized bed 1 is connected to the outlet of the secondary air fan 6.

[0032] Furthermore, the bottom end of the secondary air outlet is 3-5 m away from the air distribution plate of the circulating fluidized bed 1 .

[0033] Specific implementation method 2: Figure 1 As shown, this embodiment discloses a method for coupling fly ash melting with a circulating fluidized bed fly ash heating furnace. The method is implemented using the circulating fluidized bed fly ash heating furnace coupled with the fly ash melting device described in the first embodiment. The method comprises the following steps:

[0034] Step 1: Primary air (accounting for 50-70% of the total air volume) is introduced into the wind chamber at the bottom of the circulating fluidized bed 1 combustion chamber. At the same time, fly ash, biomass and conditioning agent (rich in silicon and aluminum minerals) are respectively fed into the circulating fluidized bed 1 combustion chamber (through screw feeder 1 7-2, screw feeder 2 8-2 and screw feeder 3 9-2) for combustion. Secondary air (accounting for 30-50% of the total air volume) is fed into the circulating fluidized bed 1 from the secondary air port. The circulating fluidized bed 1 is an adiabatic furnace with a temperature of 900-1000°C. The high-temperature flue gas discharged from the flue gas outlet at the upper end of the circulating fluidized bed 1 combustion chamber enters the high-efficiency cyclone separator 2. Urea or ammonia water is sprayed into the high-temperature flue gas before entering the high-efficiency cyclone separator 2 for SNCR denitrification (the flue gas outlet at the upper end of the combustion chamber is heated to 1000°C). An SNCR port 10 is provided on the side wall of the outlet. Urea or ammonia water is sprayed into the high-temperature flue gas through the SNCR port 10 for SNCR denitrification, which can remove 70-80% of NOx. A high-efficiency cyclone separator 2 separates fly ash carried in the high-temperature flue gas and feeds it into a circulating fluidized bed 1 through an outlet on one side of a return valve 4 at the bottom of the high-efficiency cyclone separator 2, forming a fly ash circulation. A portion of the fly ash is fed into a high-temperature melting furnace 15 through a regulating valve 3 through an outlet on the other side of the return valve 4. The burner 2 14 of the high-temperature melting furnace 15 (using biomass powder as fuel, with a particle size of less than 0.5 mm, a moisture content of less than 10%, and a calorific value greater than 3500 Kcal / kg) heats the fly ash entering the high-temperature melting furnace 15 to 1300-1400°C, thereby melting the fly ash.

[0035] The purpose of using a circulating fluidized bed 1 is to make the fly ash stay in the furnace for 3-5 minutes, so that most of the chloride salts in the fly ash can be volatilized; the bubbling fluidized bed has a residence time of only 3-5 seconds, which cannot achieve this goal;

[0036] Step 2: The high-temperature flue gas of 900-1000°C discharged from the flue gas outlet at the top of the high-efficiency cyclone separator 2 enters the secondary combustion chamber 12. The flue gas is heated to 1100°C by the burner 11 (using light oil or natural gas as fuel) in the secondary combustion chamber 12, and the residence time is greater than 2 seconds (to eliminate dioxins that may be present in the flue gas). After that, the flue gas enters the waste heat boiler 13, where the flue gas temperature drops to 500-550°C before entering the quenching tower 20.

[0037] Step 3: Flue gas discharged from the flue gas outlet of the high-temperature melting furnace 15 enters the second waste heat boiler 18. Urea or aqueous ammonia is sprayed into the 1000-1050°C region of the second waste heat boiler 18 for SNCR denitrification (an SNCR port 17 is provided on the side wall of the second waste heat boiler 18. Urea or aqueous ammonia is sprayed into the 1000-1050°C region of the second waste heat boiler 18 through the second SNCR port 17, which can remove 40-50% of NOx). After cooling the flue gas to 500-550°C in the second waste heat boiler 18, it enters the second high-efficiency cyclone separator 19. The separated fly ash is returned to the pre-furnace fly ash bin 7-1. The clean flue gas enters the quenching tower 20 from the upper outlet of the second high-efficiency cyclone separator 19.

[0038] The high-temperature slag discharged from the high-temperature melting furnace 15 is cooled by water quenching in a water quenching slag discharger 16 and then discharged.

[0039] Step 4: The two flue gases merge in the quenching tower 20 and are cooled to 200°C (the flue gas temperature is reduced to 200°C after water quenching, and dioxins are controlled to be resynthesized between 200-500°C). The flue gases then enter the bag filter 21, and activated carbon is sprayed into the flue gas connecting the bag filter 21 and the quenching tower 20 to adsorb heavy metals and dioxins in the flue gas. The flue gases then enter the flue gas heater 23, and the flue gas temperature is reduced to 105°C. The flue gases then enter the wet scrubber 24, and NaOH is used to neutralize HCl, SO2 and HF in the flue gas. The concentrated brine (i.e., the salt-containing concentrated waste water) discharged from the bottom of the wet scrubber 24 is used to remove the HCl, SO2 and HF in the flue gas. Water) is used as cooling water for the quenching tower 20. The ash discharged from the lower part of the quenching tower 20 is combined with the ash captured by the bag dust collector 21 and enters the fly ash washing device 22 (mature technology) together to separate the impurities and fly ash. The fly ash is dried and then sent to the fly ash bin 7-1 in front of the furnace. The clean flue gas (62°C) discharged from the wet scrubber 24 is heated to 157°C by the flue gas-flue gas heater 23, and then heated to 170-210°C by the steam-flue gas heater 25. It enters the SCR denitrification device 26 (existing mature technology), and then is cooled to 130-150°C by the economizer 27 (via the induced draft fan 28) and discharged into the atmosphere.

[0040] Furthermore, in step 1, the mass ratio of the fly ash, biomass and conditioning agent is 100:20-30:20-30.

[0041] Biomass mainly refers to biomass molded fuel (calorific value greater than or equal to 3500Kcal / kg), and the conditioning agent is existing products such as SiO2, Al2O3, kaolin, bauxite, fly ash and a combination of these materials.

[0042] Furthermore, in step one, the burner 2 14 uses biomass powder as fuel, requiring the biomass powder to have a particle size less than 0.5 mm, a moisture content less than 10%, and a calorific value greater than 3500 Kcal / kg, and heats the fly ash entering the high-temperature melting furnace 15 to 1300-1400° C. to achieve fly ash melting.

[0043] The present invention uses biomass as an auxiliary fuel, heating fly ash to 900-1000°C in a circulating fluidized bed (1), removing 20-25% of the crystal water and volatile chloride salts. The "hot-washed" fly ash is then fed through a high-efficiency cyclone separator (2) into a high-temperature melting furnace (15), where it is heated to 1300-1400°C using biomass powder as an auxiliary fuel, achieving ash melting. Because the vast majority of the chloride salts have been "hot-washed," refractory corrosion in the high-temperature melting furnace (15) is significantly reduced, resulting in a service life of over two years, far exceeding the six months of current electric melting furnaces.

[0044] In the present invention, in addition to using biomass as auxiliary fuel, light oil, natural gas, coal or semi-coke can also be selected as auxiliary fuel according to local environmental protection requirements.

[0045] The equipment used in the present invention is all existing equipment.

[0046] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device, characterized by: The melting device comprises a circulating fluidized bed (1), a return valve (4), a primary fan (5), a secondary combustion chamber (12), a high-temperature melting furnace (15), a quenching tower (20), a bag filter (21), a fly ash water washing device (22), a flue gas-flue gas heater (23), a wet scrubber (24), a steam-flue gas heater (25), an SCR denitrification device (26), a coal economizer (27), two high-efficiency cyclone separators and two waste heat boilers; the two high-efficiency cyclone separators are respectively a high-efficiency cyclone separator 1 (2) and a high-efficiency cyclone separator 2 (19), and the two waste heat boilers are respectively a waste heat boiler 1 (13) and a waste heat boiler 2 (18); The side wall of the circulating fluidized bed (1) is provided with a fly ash port, a biomass port, a conditioning agent port and a secondary air port. The fly ash port, the biomass port, the conditioning agent port and the secondary air port are all corresponding to the combustion chamber of the circulating fluidized bed (1). The conditioning agent port is used to introduce a conditioning agent, which is SiO2, Al2O3, kaolin, bauxite, fly ash and a combination of these materials; the outlet of the primary fan (5) is connected to the wind chamber at the bottom of the combustion chamber of the circulating fluidized bed (1); the top of the combustion chamber of the circulating fluidized bed (1) is connected to the air chamber at the bottom of the combustion chamber of the circulating fluidized bed (1). The flue gas outlet at the top is connected to the flue gas inlet of the high-efficiency cyclone separator (2), the discharge port at the lower end of the high-efficiency cyclone separator (2) is connected to the return valve (4), one side outlet of the return valve (4) is connected to the return port of the circulating fluidized bed (1) combustion chamber, and the other side outlet of the return valve (4) is connected to the inlet of the high-temperature melting furnace (15) through the high-temperature fly ash inlet pipe (29) of the melting furnace; the flue gas outlet at the top of the high-efficiency cyclone separator (2) is connected to the secondary combustion chamber (12) and the secondary combustion chamber (15) in turn. and the inlet of the waste heat boiler 1 (13); the flue gas outlet of the high temperature melting furnace (15) is connected to the flue gas inlet of the waste heat boiler 2 (18), and the flue gas outlet of the waste heat boiler 2 (18) is connected to the high efficiency cyclone separator 2 (19); the flue gas outlet of the waste heat boiler 1 (13) and the flue gas outlet of the high efficiency cyclone separator 2 (19) are both connected to the flue gas inlet of the quenching tower (20), and the flue gas outlet of the quenching tower (20) is connected to the bag dust collector (21), the flue gas-flue gas The flue gas cooling side of the heater (23), the wet scrubber (24), the flue gas heating side of the flue gas-flue gas heater (23), the steam-flue gas heater (25), the SCR denitrification device (26), and the flue gas inlet of the economizer (27) are connected; the ash discharge port at the bottom of the quenching tower (20) and the ash discharge port at the bottom of the bag filter (21) are both connected to the ash inlet of the fly ash washing device (22); and a regulating valve (3) is installed at the outlet on the other side of the return valve (4).

2. The circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device according to claim 1, characterized in that: The fly ash port on the side wall of the combustion chamber of the circulating fluidized bed (1) is connected to the outlet of the fly ash bin (7-1) through a first screw feeder (7-2); the biomass port on the side wall of the combustion chamber of the circulating fluidized bed (1) is connected to the outlet of the biomass bin (8-1) through a second screw feeder (8-2); and the conditioning agent port on the side wall of the combustion chamber of the circulating fluidized bed (1) is connected to the outlet of the conditioning agent bin (9-1) through a third screw feeder (9-2).

3. The circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device according to claim 1, characterized in that: The high-temperature fly ash inlet pipe (29) of the melting furnace is connected to the outlet of the biomass powder bin (29-1) through a screw feeder four (29-2).

4. The circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device according to claim 2, characterized in that: The secondary air port on the side wall of the combustion chamber of the circulating fluidized bed (1) is connected to the outlet of the secondary air fan (6).

5. The circulating fluidized bed fly ash heating furnace coupled with a fly ash melting device according to claim 4, characterized in that: The bottom end of the secondary air outlet is 3-5m away from the air distribution plate of the circulating fluidized bed (1).

6. A circulating fluidized bed fly ash heating furnace coupled fly ash melting method, characterized by: The method is implemented by using the circulating fluidized bed fly ash heating furnace coupled with the fly ash melting device according to any one of claims 2 to 5; the method comprises the following steps: Step 1: Primary air is introduced into the air chamber at the bottom of the circulating fluidized bed (1) combustion chamber. At the same time, fly ash, biomass and conditioning agent are respectively sent into the circulating fluidized bed (1) combustion chamber for combustion. Secondary air is sent into the circulating fluidized bed (1) from the secondary air port. The circulating fluidized bed (1) is an insulated furnace. The temperature in the furnace reaches 900-1000℃. The high-temperature flue gas discharged from the flue gas outlet at the upper end of the circulating fluidized bed (1) combustion chamber enters the high-efficiency cyclone separator (2). Urea is sprayed into the high-temperature flue gas before entering the high-efficiency cyclone separator (2). SNCR denitrification is carried out by using chlorine or ammonia water; the high-efficiency cyclone separator (2) separates the fly ash carried in the high-temperature flue gas and sends it to the circulating fluidized bed (1) from the outlet of the return valve (4) at the bottom of the high-efficiency cyclone separator (2) to form a fly ash circulation; the outlet of the return valve (4) at the other side sends a part of the fly ash to the high-temperature melting furnace (15) through the regulating valve (3); the burner (14) of the high-temperature melting furnace (15) heats the fly ash entering the high-temperature melting furnace (15) to 1300-1400°C to achieve fly ash melting; Step 2: The high-temperature flue gas of 900-1000°C discharged from the flue gas outlet at the top of the high-efficiency cyclone separator (2) enters the secondary combustion chamber (12), and is heated to 1100°C by the combustion of the burner (11) of the secondary combustion chamber (12), with a residence time of more than 2 seconds, and then enters the waste heat boiler (13). After the flue gas temperature drops to 500-550°C, it enters the quenching tower (20); Step 3: The flue gas discharged from the flue gas outlet of the high-temperature melting furnace (15) enters the waste heat boiler (18) No. 2, and urea or ammonia water is sprayed into the 1000-1050°C region of the waste heat boiler (18) to perform SNCR denitrification. After the flue gas is cooled to 500-550°C in the waste heat boiler (18), it enters the high-efficiency cyclone separator (19) No. 2, and the separated fly ash is sent back to the fly ash bin (7-1) in front of the furnace. The clean flue gas enters the quenching tower (20) from the upper outlet of the high-efficiency cyclone separator (19); Step 4: The two flue gases converge in the quenching tower (20) and are cooled to 200°C. They then enter the bag filter (21). Activated carbon is sprayed into the flue gas connecting the bag filter (21) and the quenching tower (20) to adsorb heavy metals and dioxins in the flue gas. The flue gas then enters the flue gas heater (23). The flue gas temperature drops to 105°C. The flue gas then enters the wet scrubber (24). NaOH is used to neutralize HCl, SO2 and HF in the flue gas. The concentrated brine discharged from the bottom of the wet scrubber (24) is used as the quenching tower (20). The ash discharged from the lower part of the cooling tower (20) is combined with the ash collected by the bag dust collector (21) and enters the fly ash washing device (22) to separate the impurities and fly ash. The fly ash is dried and then sent to the fly ash bin (7-1) in front of the furnace. The clean flue gas discharged from the wet scrubber (24) is heated to 157°C by the flue gas-flue gas heater (23), and then heated to 170-210°C by the steam-flue gas heater (25) and enters the SCR denitrification device (26). It is then cooled to 130-150°C by the economizer (27) and discharged into the atmosphere.

7. The method for coupling fly ash melting with a circulating fluidized bed fly ash heating furnace according to claim 6, characterized in that: In step 1, the mass ratio of the fly ash, biomass and conditioning agent is 100:20-30:20-30.

8. The method for coupling fly ash melting with a circulating fluidized bed fly ash heating furnace according to claim 6, characterized in that: In step 1, the burner 2 (14) uses biomass powder as fuel, which is required to have a particle size of less than 0.5 mm, a moisture content of less than 10%, and a calorific value of more than 3500 Kcal / kg, and heats the fly ash entering the high-temperature melting furnace (15) to 1300-1400°C to achieve fly ash melting.

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