CN111457388B

CN111457388B - System and method for co-burning solid hazardous waste and reducing dioxin discharge of chain furnace

Info

Publication number: CN111457388B
Application number: CN202010265914.6A
Authority: CN
Inventors: 王长安; 范高峰; 刘成昌; 王超伟; 唐冠韬; 袁茂博; 车得福
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2020-04-07
Filing date: 2020-04-07
Publication date: 2022-02-18
Anticipated expiration: 2040-04-07
Also published as: CN111457388A

Abstract

The invention discloses a system and a method for co-burning solid hazardous waste and reducing dioxin discharge of a chain grate furnace. Aiming at the problems that the emission amount of solid hazardous waste combustion pollutants is high, serious environmental pollution and energy waste can be caused by direct landfill treatment, the solid hazardous waste is co-combusted in a chain furnace, a gas-phase product and a solid-phase product after pyrolysis are separated and combusted, the temperature is increased by spraying pyrolysis gas and afterburning fuel gas in a hearth to decompose dioxin in the furnace, and the dioxin is treated by spraying water, quenching, grading and the like on flue gas, so that high-risk pollution products such as the dioxin generated in the combustion process are reduced, and the high-efficiency co-combustion utilization of the solid hazardous waste is realized.

Description

System and method for co-burning solid hazardous waste and reducing dioxin discharge of chain furnace

Technical Field

The invention belongs to the field of dangerous solid hazardous waste combustion utilization and chain furnace energy-saving modification application, and particularly relates to a system and a method for co-combustion of solid hazardous waste and reduction of dioxin discharge in a chain furnace.

Background

In the development and production process of the light industry, the medicine industry and other industries in China, a large amount of hazardous waste solids such as leather, medical wastes, medicine dregs generated by microbial fermentation and the like are generated, and the products can cause environmental pollution on one hand and waste of energy on the other hand when being buried; therefore, many people propose to utilize the solid hazardous waste by combustion. However, such substances are seriously polluted in the combustion process, and particularly generate dioxin substances, so that the incineration utilization is very challenging, and therefore, the development of efficient environment-friendly solid hazardous waste combustion and low-dioxin-emission technology becomes very important.

Dioxin as a persistent organic pollutant has environmental persistence, bioaccumulation, long-distance migration capability and biohazard, can greatly damage systems of human body such as immunity, reproduction, endocrine and the like, and has carcinogenic, teratogenic and mutagenic effects. In addition, dioxins are one of the persistent organic pollutants that, once formed, can remain in the ecosystem for years, or even longer.

Disclosure of Invention

Aiming at the problems of high emission amount of combustion pollutants of solid hazardous wastes, environment pollution caused by landfill of the solid hazardous wastes, energy waste and the like, the invention aims to mix and burn the solid hazardous wastes in a chain furnace, separate and burn gas-phase products and solid-phase products after pyrolysis of the solid hazardous wastes, spray and supplement fuel gas in a hearth to improve the temperature so as to decompose the existing dioxins, spray and quench the gases in a descending flue and the like, and remove the dioxins in flue gas in a grading manner so as to reduce the emission amount of high-risk pollution products such as the dioxins generated in the combustion process, thereby realizing the combustion utilization of the solid hazardous wastes.

The invention is realized by adopting the following technical scheme:

a system for burning solid hazardous waste in a chain grate furnace and reducing the emission of dioxin comprises a chain grate, a pyrolysis reactor, a dryer, a water spraying desuperheater, an ash collector, a tail flue and a chimney; wherein, a primary air bin is arranged below the chain grate, the primary air bin is arranged in a bin-divided manner, and a pyrolysis gas nozzle, a afterburning gas nozzle and a secondary air nozzle are arranged on the side wall of the chain grate; a fuel inlet is arranged on a rear arch of the hearth, a dryer and a water spraying desuperheater are arranged in a downward flue, a dust remover is arranged in a tail flue, and an active carbon adsorption layer is arranged in the dust remover; a pyrolysis reactor is arranged between the hearth and the downward flue, a gas-solid two-phase isolation layer is arranged in the pyrolysis reactor, and the pyrolysis reactor is divided into a pyrolysis solid-phase product area and a pyrolysis gas-phase product area;

during working, preset coal is crushed and then sent into a chain grate and enters a hearth for combustion, blended solid hazardous waste fuel is dried by a dryer and then enters a pyrolysis reactor, a pyrolysis gas-phase product enters the hearth for combustion from a pyrolysis gas nozzle, a pyrolyzed solid substance enters the chain grate from a fuel inlet on a rear arch, and the pyrolyzed solid substance is rapidly combusted under the action of bottom fire; in the pyrolysis reactor, high-temperature flue gas enters a pyrolysis solid-phase product area at the bottom of the pyrolysis reactor from a high-temperature flue gas inlet, enters a pyrolysis gas-phase product area through a gas-solid two-phase isolation layer in the pyrolysis reactor, and finally is led out from a pyrolysis gas-phase product outlet to enter a hearth; after combustion, flue gas enters a descending flue, is quenched by a water spray desuperheater, then passes through a dryer, large particle dust in the flue gas falls into an ash collector after water spray desuperheating, and small particle dust flows out of a tail flue along with the flue gas and enters a dust remover, and is discharged from a chimney after pollutants are removed.

The invention has the further improvement that the pyrolysis gas nozzles and the afterburning gas nozzles on the side wall of the hearth are arranged in two layers, the lower layer is the pyrolysis gas nozzles, and the upper layer is the afterburning gas nozzles; and a secondary air nozzle is arranged above the afterburning gas nozzle.

The invention is further improved in that the coal-fired grate further comprises a fuel conveyor, and the preset coal is sent to the chain grate through the fuel conveyor after being crushed.

The invention is further improved in that conical flue baffles are arranged around the water spray desuperheater.

The invention has the further improvement that the invention also comprises an induced draft fan, and pollutants are removed and then discharged from a chimney.

A method for co-combustion of solid hazardous waste and reduction of dioxin discharge in a chain furnace is based on the system for co-combustion of solid hazardous waste and reduction of dioxin discharge in a chain furnace, and comprises the following steps:

1) presetting coal types, sending the coal types to a chain grate, and combusting under the action of primary air to form primer;

2) the injection amount of the afterburning gas is adjusted according to the preset fuel and the combustion temperature of the hearth, the gas enters the hearth through the afterburning gas nozzle to be combusted, so that the temperature of the hearth smoke is raised, and dioxin is decomposed under the condition of high-temperature smoke;

3) after the flue gas enters a descending flue, the flue gas passes through a temperature reduction water sprayer, and the temperature of the flue gas is rapidly reduced to be below 300 ℃ of the low-temperature synthesis temperature of the dioxin, so that the low-temperature synthesis temperature interval of the dioxin is avoided;

4) the dryer utilizes the waste heat of the flue gas to dry the hazardous waste solid to be pyrolyzed, and the waste heat of the flue gas is recycled;

5) granular dioxin or large granular dust attached to the large granular dust in the flue gas is deposited on the ash collector and is collected and treated, so that the workload of a subsequent dust collector is reduced; the gas-phase dioxin and the dioxin attached to the small-particle dust flow into a tail flue along with the flue gas, the dust remover removes the small-particle dust, the small-particle dust is treated by an activated carbon adsorption layer, the gas-phase dioxin is adsorbed, and the dioxin in the flue gas is removed in a grading manner, so that the removal efficiency is improved and the service life of an instrument is prolonged;

6) solid hazardous wastes are pyrolyzed into solid-phase and gas-phase products in a pyrolysis reactor, the pyrolyzed solid-phase products enter a fire grate through a fuel inlet on a rear arch for combustion, the pyrolyzed gas-phase products are sprayed into a hearth through a pyrolysis gas nozzle on a side wall for combustion, and the solid hazardous wastes are pyrolyzed and separately combusted, so that catalyst substances in the solid products can be prevented from promoting Cl elements and organic matters in a gas state to generate dioxin substances.

The invention has at least the following beneficial technical effects:

according to the invention, through the combination of technologies such as separation and combustion of gas phase and solid phase products after pyrolysis of hazardous waste solids, doping of afterburning gas into a hearth, rapid cooling of flue gas and graded removal of dioxin, preset fuel enters a furnace to be combusted on a chain grate, the doped solid hazardous waste is dried by a dryer and enters a pyrolysis reactor to be pyrolyzed under the action of high-temperature flue gas, pyrolyzed combustible gas enters the hearth to be combusted through an afterburning gas nozzle, the pyrolyzed solid products are thrown onto the chain grate, and a metal oxide catalyst, a Cl element and organic matters are separated and combusted through separation and combustion treatment of the pyrolyzed products, so that the generation of dioxin is reduced. The invention improves the temperature of the hearth smoke by spraying the afterburning gas for combustion to decompose the dioxin, reduces the synthesis of the dioxin by treatment of the quenching device of the tail flue, reduces the grading removal of the dioxin in the smoke and solves the problems of high emission of solid hazardous waste combustion pollutants, environmental pollution caused by landfill of the solid hazardous waste, energy waste and the like. In summary, the present invention has the following advantages:

1) an upper layer of gas nozzles and a lower layer of gas nozzles are arranged on the side wall of the hearth and are respectively pyrolysis gas nozzles and afterburning gas nozzles, and solid hazardous waste pyrolysis gas enters the hearth from the lower layer of pyrolysis gas nozzles; after-combustion gas enters the hearth from the upper-layer after-combustion gas nozzle, the temperature of flue gas is effectively increased, and dioxin generated by combustion or originally existing in the combustion is decomposed in a high-temperature environment.

2) Dangerous useless pyrolysis in the pyrolysis reactor, the gaseous phase product that generates sends into furnace different positions with solid phase product and burns, avoids catalyst class material in the solid phase and organic matter in the gaseous phase and Cl element contact, and the catalytic generation dioxin class material reduces the production of dioxin from the source.

3) And a fuel inlet is formed in the rear arch, the pyrolyzed solid-phase product enters the hearth from the fuel inlet on the rear arch after coming out of the pyrolysis reactor, and the specific falling position is adjusted by adjusting the angle according to the combustion condition of the grate. The solid products are combusted on the 'primer' formed by the grate.

4) A water spray desuperheater and a conical flue baffle are arranged in the down flue, and the water spray desuperheater is used for rapidly reducing the temperature of high-temperature flue gas to be below 300 ℃, so that the temperature range of the resynthesis of dioxin is avoided, and the regeneration of the dioxin is reduced; the conical flue baffle can avoid the temperature-reducing water from directly contacting with the inner wall of the flue, and meanwhile, the conical flue baffle can disturb flue gas and accelerate the mixing of the flue gas and the temperature-reducing water.

5) The dryer is arranged in the downward flue, and the waste heat in the flue gas is used for drying hazardous waste, so that the waste heat of the flue gas can be effectively recycled, and the aim of saving energy is fulfilled.

6) The tail end of the downward flue is provided with the ash collector, and large-particle dust and solid dioxin in the flue gas fall into the ash collector under the action of inertia force, so that the workload of the tail dust remover is reduced. The activated carbon adsorption layer is arranged in the dust remover, so that gas-phase and fine-particle dioxin can be captured and adsorbed, and the content of the dioxin in the flue gas is further reduced. Through the combined action of the ash collector and the dust remover, the dioxin is eliminated in a gradient manner, and the elimination rate and the service life of the tail flue gas treatment instrument are improved.

Drawings

FIG. 1 shows a system for co-burning solid hazardous waste and reducing dioxin discharge in a chain furnace according to the invention.

Fig. 2 is an enlarged view of a portion of the pyrolysis reactor of the present invention.

Description of reference numerals:

the device comprises a fuel conveyor 1, a primary air bin 2, a traveling grate 3, a rear arch 4, a fuel inlet 5, a pyrolysis gas nozzle 6, a afterburning gas nozzle 7, a hearth 8, a secondary air nozzle 9, a pyrolysis gas-phase product outlet 10, a pyrolysis reactor 11, a pyrolysis gas-phase product area 12, a gas-solid two-phase isolation layer 13, a pyrolysis solid-phase product area 14, a high-temperature flue gas inlet 15, a water spray desuperheater 16, a conical flue baffle 17, a dryer 18, an ash collector 19, a tail flue 20, a dust remover 21, an active carbon adsorption layer 22, an induced draft fan 23 and a chimney 24.

Detailed Description

The invention will be further elucidated with reference to the drawings in which:

referring to fig. 1 and 2, the system for co-combustion of solid hazardous waste and reduction of dioxin discharge in a chain furnace provided by the invention comprises a pyrolysis gas nozzle 6, a post-combustion gas nozzle 7, a pyrolysis reactor 11 and a dryer 18, water spray desuperheater 16, ash collector 19 and afterbody flue 20, chain grate 3 below is provided with primary air storehouse 2, primary air storehouse adopts the branch storehouse formula to arrange, pyrolysis gas spout 6 has been arranged on the chain grate lateral wall, afterburning gas spout 7 and overgrate air spout 9, offer on furnace's the back arch 4 and put fuel inlet 5, be provided with desicator 18 and water spray desuperheater 16 in the down flue, afterbody flue 20 is provided with dust remover 21, pyrolytic reaction ware 11 has been arranged between furnace and the down flue, be provided with the double-phase isolation layer of gas-solid 13 in the pyrolytic reaction ware 11, divide pyrolytic reaction ware 11 into pyrolysis solid phase product district 14 and pyrolysis gas phase product district 12.

The method comprises the steps that after preset fuel is crushed, the preset fuel is sent into a chain grate 3 through a fuel conveyor 1 to enter a hearth for combustion, the preset fuel is discharged from a slag falling port after being combusted, mixed solid dangerous waste fuel is dried through a dryer 18 and then enters a pyrolysis reactor 11, pyrolyzed solid matter enters the chain grate 3 through a fuel inlet 5 on a rear arch, and pyrolyzed solid-phase products are rapidly combusted under the action of bottom fire. In the pyrolysis reactor 11, high-temperature flue gas enters a pyrolysis solid-phase product area 14 at the bottom of the pyrolysis reactor 11 from a high-temperature flue gas inlet 15, passes through a gas-solid two-phase isolation layer 13 from bottom to top, and pyrolysis gas is led out from a pyrolysis gas-phase product outlet 10 and then enters a hearth 8 from a pyrolysis gas nozzle 6 for combustion. After combustion, flue gas enters a down flue and is rapidly cooled by a water spray desuperheater 16, then the flue gas passes through a dryer 18, conical flue baffles 17 are additionally arranged around the water spray desuperheater 16, the phenomenon that sprayed desuperheating water directly contacts the inner wall of the flue to cause corrosion is avoided, large particle dust in the flue gas falls into an ash collector 19 after water spray desuperheating, the small particle dust flows out of a tail flue 20 along with the flue gas and enters a dust remover 21, and pollutants such as dioxin and the like are eliminated in a gradient mode and are discharged from a chimney 24 after passing through an induced draft fan 23.

Air enters the primary air bin 2 after passing through the air feeder, and the primary air bin 2 is arranged in a separated mode, so that independent air distribution of all parts is achieved.

The desicator 18 is arranged in the down flue, utilize the dry solid danger of mixing the fever of flue gas waste heat, recycle the flue gas waste heat, the useless pyrolysis reactor 11 that gets into of solid danger after the drying, the high temperature flue gas that comes from furnace enters into the pyrolysis reactor 11 from high temperature flue gas import 15, be inert atmosphere in the pyrolysis reactor 11, the high temperature flue gas flow direction is from upwards down, the useless fuel import 5 that encircles 4 after bottom pyrolysis gets into furnace in, burn on the primer that chain grate 3 formed. The pyrolysis gas phase product flows upwards along with the pyrolysis flue gas, enters the pyrolysis gas phase product area 12 after passing through the gas-solid two-phase isolation layer 13, is led out from the pyrolysis gas phase product outlet 10 to the pyrolysis gas nozzle 6, and enters the hearth for combustion. The gas-phase product and the solid-phase product of the co-burning solid hazardous waste are separately burnt after pyrolysis, so that Cl element in the gas-phase product and organic matter and metal oxide catalyst substances in the solid-phase product can be separately burnt, and the generation of dioxin pollutants is reduced from the source.

The flue gas enters the tail flue, and the high-temperature flue gas is rapidly cooled by the water spray desuperheater 16, so that the temperature of the flue gas is rapidly reduced to be below 300 ℃, a low-temperature synthesis temperature interval of dioxin is avoided, and the synthesis amount of the dioxin at a low temperature is reduced. The conical flue baffle 17 is arranged at the water spraying temperature reduction position, so that the contact between the water spraying position and the inner wall of the flue in the descending process can be avoided, and the corrosion of the inner wall of the flue is reduced.

The ash collector 19 is arranged at the tail of the downward flue, flue gas is cooled by water spray and then flows downwards, under the action of inertia force, dust attached with dioxin and dioxin particles enter the ash collector 19, the dioxin particles and large-particle dust in the flue gas are removed, and the workload of the tail dust collector is reduced. The dioxin in the gas phase flows to a dust remover 21 in a tail flue, enters an activated carbon adsorption layer 22 after dust removal, adsorbs the dioxin in the gas phase in the flue gas, and reduces the content of dioxin pollutants in the flue gas again. The dioxin is removed in a cascade mode through the dust collector and the dust remover, so that the removal rate of the dioxin can be improved, and the service life of equipment can be prolonged.

Referring to fig. 1, the method for co-burning solid hazardous waste and reducing dioxin discharge of a chain furnace provided by the invention comprises the following steps:

1) the preset fuel high-volatile coal-based fuel is sent to the chain grate 3 and is combusted under the action of primary air to form primer;

2) the afterburning gas enters the hearth through the afterburning gas nozzle 7 to be combusted, and the combustion of the afterburning gas can enable the temperature of the flue gas in the hearth to rise above the temperature required by decomposition of the dioxin, so that the existing dioxin is decomposed at high temperature.

3) The solid hazardous waste is pyrolyzed in the pyrolysis reactor 11 under the condition of avoiding low-temperature generation of dioxin, the hazardous waste is pyrolyzed into solid-phase and gas-phase products, the pyrolyzed solid-phase products enter through a fuel inlet 5 on a rear arch and are combusted on a bottom fire formed by covering a chain grate 3, and the pyrolyzed gas-phase products are sprayed into a hearth through a pyrolysis gas nozzle 6 on a side wall to be combusted. The solid hazardous waste is pyrolyzed and separately combusted, so that catalyst substances in the solid can be prevented from promoting Cl elements and organic matters in the gas state to generate dioxin substances.

4) After the flue gas enters the descending flue, the temperature of the flue gas is rapidly reduced to below 300 ℃ after passing through the water spraying desuperheater 16, and the temperature interval of low-temperature synthesis of dioxin is rapidly avoided.

5) The conical flue baffle 17 can isolate the direct contact of the temperature-reduced water and the inner wall of the flue, and reduce the corrosion of the flue. The desiccator 18 utilizes the waste gas heat drying to treat the useless solid of danger of pyrolysis, recycle flue gas waste heat, graininess or attached to the dioxin and the large granule dust of large granule dust deposit and get off and collect the processing on ash collector 19 in the flue gas, the dioxin of gaseous phase and the dioxin attached to on the small granule dust enter the afterbody flue along with the flue gas flow, dust remover 21 adsorbs gaseous phase dioxin after the active carbon adsorption layer 22 is handled after detaching the small granule dust, realize the step desorption of dioxin in the flue gas, clean flue gas sends chimney 24 through draught fan 23 and discharges.

The above description is only for the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and other modifications or equivalent substitutions made by the technical solution of the present invention by the ordinary skilled in the art should be covered within the scope of the claims of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A system for burning solid hazardous waste in a chain furnace and reducing the emission of dioxin is characterized by comprising a chain grate (3), a pyrolysis reactor (11), a dryer (18), a water spraying desuperheater (16), an ash collector (19), a tail flue (20) and a chimney (24); wherein the content of the first and second substances,

a primary air bin (2) is arranged below the chain grate (3), the primary air bins (2) are arranged in a bin-divided mode, and a pyrolysis gas nozzle (6), a afterburning gas nozzle (7) and a secondary air nozzle (9) are arranged on the side wall of the chain grate; a fuel inlet (5) is arranged on a rear arch (4) of the hearth, a dryer (18) and a water spray desuperheater (16) are arranged in a down flue, a dust remover (21) is arranged in a tail flue (20), and an activated carbon adsorption layer (22) is arranged in the dust remover (21); a pyrolysis reactor (11) is arranged between the hearth and the downward flue, a gas-solid two-phase isolation layer (13) is arranged in the pyrolysis reactor (11), and the pyrolysis reactor (11) is divided into a pyrolysis solid-phase product area (14) and a pyrolysis gas-phase product area (12);

the pyrolysis gas nozzles (6) and the afterburning gas nozzles (7) on the side wall of the hearth are arranged in two layers, the lower layer is the pyrolysis gas nozzles (6), and the upper layer is the afterburning gas nozzles (7); a secondary air nozzle (9) is arranged above the afterburning gas nozzle (7);

conical flue baffles (17) are arranged around the water spray desuperheater (16);

during working, preset coal is crushed and then sent into the traveling grate (3) and enters a hearth for combustion, co-burned solid hazardous waste fuel is dried by the dryer (18) and then enters the pyrolysis reactor (11), a pyrolysis gas-phase product enters the hearth for combustion from the pyrolysis gas nozzle (6), a pyrolyzed solid substance enters the traveling grate (3) from the fuel inlet (5) on the rear arch (4), and the pyrolyzed solid substance is rapidly combusted under the action of primer; in a pyrolysis reactor (11), high-temperature flue gas enters a pyrolysis solid-phase product area (14) at the bottom of the pyrolysis reactor (11) from a high-temperature flue gas inlet (15), enters a pyrolysis gas-phase product area (12) through a gas-solid two-phase isolation layer (13) in the pyrolysis reactor (11), and finally is led out to enter a hearth through a pyrolysis gas-phase product outlet (10); after combustion, the flue gas enters a down flue and is quenched by a water spray desuperheater (16), then passes through a dryer (18), large particle dust in the flue gas falls into an ash collector (19) after water spray desuperheating, small particle dust flows out of a tail flue (20) along with the flue gas and enters a dust remover (21), and the flue gas is discharged from a chimney (24) after pollutants are removed;

the device also comprises a fuel conveyor (1), wherein preset coal types are sent into the chain grate (3) through the fuel conveyor (1) after being crushed;

the device also comprises an induced draft fan (23) which is discharged from a chimney (24) after pollutants are removed.

2. A method for co-combustion of solid hazardous waste and reduction of dioxin discharge in a chain furnace is based on the system for co-combustion of solid hazardous waste and reduction of dioxin discharge in a chain furnace of claim 1, and comprises the following steps:

1) presetting coal types, sending the coal types to a chain grate (3), and combusting the coal types under the action of primary air to form primer;

2) the injection amount of the afterburning gas is adjusted according to the preset fuel and the combustion temperature of the hearth, the gas enters the hearth through an afterburning gas nozzle (7) to be combusted, so that the smoke temperature of the hearth is increased, and dioxin is decomposed under the condition of high-temperature smoke;

3) when the combusted flue gas enters a down flue, the flue gas passes through a spray temperature reduction water heater (16) and then the temperature of the flue gas is rapidly reduced to be below the low-temperature synthesis temperature of the dioxin, so that the low-temperature synthesis temperature range of the dioxin is avoided;

4) the dryer (18) dries the hazardous waste solid to be pyrolyzed by using the waste heat of the flue gas, and recycles the waste heat of the flue gas;

5) granular dioxin or large granular dust attached to the large granular dust in the flue gas is deposited on the ash collector (19) and is collected and processed, so that the workload of a subsequent dust collector is reduced; the gas-phase dioxin and the dioxin attached to small-particle dust flow into a tail flue (20) along with flue gas, the dust collector (21) removes the small-particle dust, the small-particle dust is treated by an activated carbon adsorption layer (22) and then adsorbs the gas-phase dioxin, and the dioxin in the flue gas is removed in a grading manner, so that the removal efficiency is improved and the service life of an instrument is prolonged;

6) solid dangerous waste is pyrolyzed into solid-phase and gas-phase products in a pyrolysis reactor (11), the pyrolyzed solid-phase products enter a fire grate through a fuel inlet (5) on a rear arch (4) to be combusted, the pyrolyzed gas-phase products are sprayed into a hearth through pyrolysis gas nozzles (6) on a side wall to be combusted, and the solid dangerous waste is pyrolyzed and separately combusted, so that catalyst substances in the solid products can be prevented from promoting Cl elements and organic matters in a gas state to generate dioxin substances.