CN113310056A

CN113310056A - Hazardous waste incineration treatment system and method

Info

Publication number: CN113310056A
Application number: CN202110510429.5A
Authority: CN
Inventors: 谢陈平; 陈齐平; 潘国栋; 王增琛; 严庆云; 代恩岩
Original assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd; CGN Power Co Ltd; Shenzhen China Guangdong Nuclear Engineering Design Co Ltd
Current assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd; CGN Power Co Ltd; Shenzhen China Guangdong Nuclear Engineering Design Co Ltd
Priority date: 2021-05-11
Filing date: 2021-05-11
Publication date: 2021-08-27

Abstract

The invention discloses a hazardous waste incineration treatment system and a method, wherein the hazardous waste incineration treatment system comprises a rotary kiln, a secondary combustion chamber, a plasma melting furnace, an ash residue transmission unit, a waste heat boiler, a quench tower, a dry deacidification tower, a dust removal unit and a wet deacidification tower; the rotary kiln and the second combustion chamber are closely connected and share a slag outlet; the ash slag transmission unit is connected between the slag outlet and the plasma melting furnace; flue gas generated in the rotary kiln and the plasma melting furnace is conveyed into the secondary combustion chamber for secondary combustion treatment; the waste heat boiler, the quench tower, the dry deacidification tower, the dust removal unit and the wet deacidification tower are sequentially connected with the second combustion chamber. The invention combines the plasma melting furnace with the rotary kiln, carries out melting treatment on the burned residues to form a vitreous body, and further treats the smoke generated by burning and melting treatment through a secondary combustion chamber, a waste heat boiler and the like, so that the smoke meets the emission standard, and the harmlessness, reduction and recycling of hazardous wastes are realized.

Description

Hazardous waste incineration treatment system and method

Technical Field

The invention relates to the technical field of hazardous waste treatment, in particular to a hazardous waste incineration treatment system and a hazardous waste incineration treatment method.

Background

According to the definition of 'national hazardous waste record' newly revised in 2016, the hazardous waste is 1) one or more hazardous characteristics such as corrosivity, toxicity, flammability, reactivity or infectivity; 2) dangerous characteristics are not excluded, and may have harmful effects on the environment or human health, which need to be managed according to dangerous wastes. The dangerous waste treatment method mainly comprises two types of recycling and harmlessness, the harmlessness is mainly incineration, at present, the main furnace types for incinerating the dangerous waste at home and abroad comprise a rotary kiln incinerator (a rotary kiln for short), a grate furnace, a liquid injection incinerator, a fluidized bed incinerator, a multi-layer bed incinerator, a pyrolysis incinerator and the like, the incineration process of the dangerous waste is complex, and the rotary kiln has the advantages of simple structure, strong adaptability to the dangerous waste, stable control, easy operation, mature technology, long operation history and the like, and the like.

However, 20% -25% of ash slag is generated after the rotary kiln is burnt, the ash slag still belongs to dangerous waste according to national regulations, the ash slag needs to be solidified and then enters a landfill site, the landfill cost is high, precious land resources are occupied, and environmental hidden troubles also exist. The liquid waste in partial areas can be blocked due to the fact that the environmental temperature is too low in winter before the liquid waste enters the rotary kiln to be incinerated, and potential safety hazards of operation exist. With the stricter and stricter emission requirements on nitrogen oxides in flue gas, the conventional flue gas treatment method cannot meet the supervision requirements on the flue gas discharged by burning the rotary kiln.

Disclosure of Invention

The invention aims to provide a hazardous waste incineration treatment system and a hazardous waste incineration treatment method for realizing harmlessness, reduction and recycling of hazardous waste.

The technical scheme adopted by the invention for solving the technical problems is as follows: the provided hazardous waste incineration treatment system comprises a rotary kiln for carrying out incineration treatment on hazardous waste, a secondary combustion chamber for carrying out secondary combustion treatment on flue gas, a plasma melting furnace for carrying out melting treatment on residues, an ash residue transmission unit, a waste heat boiler, a quench tower, a dry deacidification tower, a dust removal unit and a wet deacidification tower;

the rotary kiln and the secondary combustion chamber are closely connected and share a slag outlet; the ash conveying unit is connected between the slag outlet and the plasma melting furnace, residues generated in the rotary kiln and the secondary chamber are discharged from the slag outlet and conveyed into the plasma melting furnace through the ash conveying unit, and are melted by the plasma melting furnace to form glass bodies; flue gas generated in the rotary kiln and the plasma melting furnace is conveyed into the secondary chamber for secondary combustion treatment;

the waste heat boiler, the quench tower, the dry deacidification tower, the dedusting unit and the wet deacidification tower are sequentially connected with the secondary combustion chamber, and the high-temperature flue gas discharged from the secondary combustion chamber is sequentially subjected to cooling, adsorption purification, dedusting filtration and deacidification treatment.

Preferably, a smoke outlet of the rotary kiln is butted with a smoke inlet of the secondary combustion chamber, and smoke generated by burning in the rotary kiln enters the secondary combustion chamber through the smoke outlet and the smoke inlet;

the smoke outlet of the plasma melting furnace is connected with the secondary combustion chamber through a smoke outlet pipeline, and smoke generated by melting treatment in the plasma melting furnace is conveyed into the secondary combustion chamber through the smoke outlet pipeline.

Preferably, the ash conveying unit comprises a water-sealed scraper slag extractor for cooling the residue, and a closed belt conveying mechanism for conveying the residue;

the water seal scraper slag extractor is arranged at the slag outlet, and the belt conveying mechanism is connected between the water seal scraper slag extractor and the feed inlet of the plasma melting furnace.

Preferably, the hazardous waste incineration disposal system further comprises a bottom slag mixing device for crushing the residues and mixing the crushed residues with the fluxing agent; the bottom slag mixing device is arranged between the belt conveying mechanism and the feeding hole of the plasma melting furnace.

Preferably, the bottom slag mixing device comprises a crusher for crushing the residues, a mixer for mixing the crushed residues with a fusing promoting agent to form a mixed material, a double-roller granulator for receiving the mixed material from the mixer and preparing the mixed material into residue particles, and a vibration bin for receiving the residue particles from the double-roller granulator and feeding the residue particles into the plasma melting furnace.

Preferably, the dust removal unit comprises a cyclone dust collector and a bag type dust collector which are sequentially connected between the dry acid removal tower and the wet acid removal tower.

Preferably, the hazardous waste incineration treatment system further comprises an air preheater arranged between the bag type dust collector and the wet deacidification tower, the air preheater is used for allowing the flue gas to pass through and recovering heat of the flue gas, and the recovered heat is used as combustion-supporting air of the secondary combustion chamber after heating the air.

Preferably, the air preheater is internally provided with a flue gas channel and an air channel which are used for heat exchange; the flue gas channel is respectively communicated with the bag type dust collector and the wet method deacidification tower, the outlet of the air channel is connected with the secondary combustion chamber through a ventilating pipeline, and the air after heat exchange with the flue gas is conveyed into the secondary combustion chamber.

Preferably, the ventilation duct is provided with a filter for filtering air, a dryer for drying air, and a blower.

Preferably, the belt conveying mechanism is arranged on the ventilation pipeline, and air conveyed by the ventilation pipeline is used for heating residues.

Preferably, the hazardous waste incineration disposal system further comprises a flue gas heater; the flue gas heater is connected between a chimney and the wet acid removal tower, and heats the flue gas discharged by the wet acid removal tower and then discharges the heated flue gas to the chimney.

Preferably, the flue gas heater is connected with the waste heat boiler through a steam pipeline and a steam distribution cylinder, and steam generated by the waste heat boiler is used as a heat source.

The invention also provides a hazardous waste incineration treatment method, which adopts the hazardous waste incineration treatment system of any one of the above parts; the method for incinerating and treating hazardous wastes comprises the following steps:

s1, feeding the dangerous waste into a rotary kiln for incineration treatment;

flue gas generated by incineration is conveyed into the secondary combustion chamber, and residues generated by incineration and residues generated in the secondary combustion chamber enter the ash conveying unit through the slag outlet;

s2, cooling and drying the residues by the ash conveying unit, and then sending the residues into a plasma melting furnace for plasma melting treatment to form a vitreous body;

s3, conveying the flue gas generated by the melting treatment in the plasma melting furnace to a secondary combustion chamber, and performing secondary combustion treatment on the flue gas from the rotary kiln and the plasma melting furnace in the secondary combustion chamber to decompose harmful components including dioxin in the flue gas and output high-temperature flue gas;

s4, conveying the high-temperature flue gas into a waste heat boiler, and removing nitrogen oxides in the high-temperature flue gas through reaction with a urea solution sprayed into the waste heat boiler;

s5, conveying the cooled flue gas from the waste heat boiler to a quenching tower for heat exchange and cooling again, and simultaneously preventing the dioxin from being resynthesized;

s6, conveying the flue gas subjected to heat exchange and temperature reduction to a dry-method deacidification tower to remove acid gas in the flue gas;

s7, conveying the purified flue gas to a dust removal unit for dust removal and filtration treatment, and removing pollutants including heavy metals and dioxin in the flue gas;

s8, conveying the dedusted and filtered flue gas into a wet deacidification tower, and deacidifying the flue gas by using alkali liquor to remove HCl, HF and SO in the flue gas₂。

The invention has the beneficial effects that: the plasma melting furnace is combined with the rotary kiln, the burned residues are melted to form a vitreous body, and the smoke generated by burning and melting treatment is further treated through a secondary combustion chamber, a waste heat boiler and the like, so that the smoke meets the emission standard, and the harmlessness, reduction and recycling of hazardous wastes are realized.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a connection block diagram of a hazardous waste incineration disposal system according to an embodiment of the present invention;

FIG. 2 is a block diagram showing the connection of an ozone generating apparatus in the hazardous waste incineration disposal system according to an embodiment of the present invention.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The hazardous waste incineration treatment system is used for carrying out fusion treatment on hazardous waste, treating smoke generated by the fusion treatment, and removing harmful substances and the like in the smoke.

As shown in fig. 1, the hazardous waste incineration disposal system according to an embodiment of the present invention includes a rotary kiln 10, a secondary combustion chamber 20, a plasma melting furnace 30, an ash transfer unit 40, a bottom ash mixing device 50, a waste heat boiler 60, a quenching tower 70, a dry deacidification tower 80, a dust removal unit, and a wet deacidification tower 100.

The rotary kiln 10 is used for burning hazardous wastes, and the secondary combustion chamber 20 is used for burning the flue gas again to remove harmful components in the flue gas; the rotary kiln 10 and the second combustion chamber 20 are closely adjacent to each other and share a slag outlet. The ash transfer unit 40 is connected between the slag outlet from which the slag generated in the rotary kiln 10 and the secondary combustion chamber 20 is discharged and the plasma-melting furnace 30 through the ash transfer unit 40, and the slag is melted by the plasma-melting furnace 30 to form a glass body, and the plasma-melting furnace 30. The bottom slag mixing device 50 is arranged between the ash conveying unit 40 and the plasma melting furnace 30, and is used for crushing the residues, mixing the crushed residues with the flux promoter to form a mixed material and sending the mixed material into the plasma melting furnace 30. Flue gas generated in the rotary kiln 10 and the plasma melting furnace 30 is conveyed into the secondary combustion chamber 20 for secondary combustion treatment.

The exhaust-heat boiler 60, the quench tower 70, the dry deacidification tower 80, the dedusting unit and the wet deacidification tower 100 are sequentially connected with the secondary combustion chamber 20, and the high-temperature flue gas discharged from the secondary combustion chamber 20 is sequentially subjected to cooling, adsorption purification, dedusting filtration and deacidification treatment, so that the gas meeting the discharge standard is finally obtained.

Wherein, the rotary kiln 10 is closely connected with the second combustion chamber 20, the smoke outlet of the rotary kiln 10 is directly butted with the smoke inlet of the second combustion chamber 20, and the smoke in the rotary kiln 10 is directly sent into the second combustion chamber 20 in a closed space without leakage.

Specifically, the rotary kiln 10 includes a kiln head, a body, a kiln tail, a transmission mechanism, and the like. The kiln head mainly has the function of smoothly feeding materials (such as hazardous wastes), and an auxiliary fuel/liquid waste combined burner is arranged inside the kiln head. The lower part of the kiln head is provided with a waste collector for collecting waste leakage. The body of the rotary kiln 10 is a cylinder rolled from steel plate and lined with refractory material. The body is provided with two belt wheels and a large gear ring, the transmission mechanism drives the large gear ring on the body through a small gear, and then the rotary kiln 10 body is driven to rotate through the large gear ring. The kiln tail is a transition body which is connected with the rotary kiln 10 body and the secondary combustion chamber 20, and the main function of the kiln tail is to ensure the sealing of the kiln tail and the conveying channel of the smoke and the incineration residue.

To ensure the downward transport of hazardous waste, the rotary kiln 10 must maintain a certain inclination. The kiln tail of the rotary kiln 10 is inserted into the secondary combustion chamber and shares a slag outlet with the secondary combustion chamber 20. The slag hole is arranged at the bottom of the second combustion chamber 20 and is preferably arranged to be large-opening slag, so that large-particle slag blocks can be conveniently dropped. Meanwhile, a multi-component burner is arranged at the bottom of the secondary combustion chamber 20, so that the combustion temperature of the secondary combustion chamber 20 is ensured to be higher than 1100 ℃, and the kiln tail temperature of the rotary kiln 10 is increased.

Hazardous waste generally includes liquid waste and solid waste; the solid waste is pushed into the rotary kiln 10 through a hydraulic push rod; the liquid waste is conveyed to the head of the rotary kiln 10 through a pipeline by a conveying pump and then is sent into the body of the rotary kiln 10. The flue gas generated by burning in the rotary kiln 10 is conveyed to the secondary combustion chamber 20 for secondary combustion treatment, and the burned residues are discharged from the slag outlet.

The secondary combustion chamber 20 performs a secondary combustion treatment on the flue gas to decompose dioxin and other harmful components in the flue gas. The size of the second combustion chamber 20 is set to ensure that the residence time of the flue gas is more than 2s at the temperature of over 1100 ℃; under this condition, 99.99% of dioxin and other harmful components in the flue gas can be decomposed. The lower part of the second combustion chamber 20 is provided with a required number (such as two) of multifunctional burners, so that the temperature of the flue gas in the second combustion chamber 20 can meet the requirement, and the flue gas can be fully disturbed. The second combustion chamber 20 can be provided with a thermocouple to control the firepower of the multifunctional burner, so that the temperature of the second combustion chamber 20 is stabilized at a set value.

Before the smoke is subjected to the secondary combustion treatment, liquid waste is also input into the secondary combustion chamber 20. The liquid waste is conveyed to the multifunctional burner of the second combustion chamber 20 through a pipeline by a conveying pump and then enters the second combustion chamber 20. The rotary kiln 10 and the secondary combustion chamber 20 are respectively provided with an air inlet for respectively feeding combustion-supporting air.

Alternatively, the inner wall of the second combustion chamber 20 is a fire-resistant layer, and the outer wall is a heat-insulating layer and an outer protection plate in sequence. The internal working temperature of the second combustion chamber 20 is more than 1100 ℃, and the external surface temperature is less than or equal to 60 ℃.

The plasma melting furnace 30 is used for melting the residue discharged from the rotary kiln 10 and the secondary combustion chamber 20 to form a stable glass body. The plasma melting furnace 30 uses a plasma generator as a heating source, and the plasma generator is uniformly distributed on the plasma melting furnace 30 in a side direction and a top direction, so that the plasma melting furnace has the characteristics of high heating efficiency, uniform heating, large heat exchange amount, good activation melting effect and the like.

The highest temperature in the plasma melting furnace 30 is above 1400 ℃, the residue has enough residence time in the furnace to ensure that the residue is melted, and the heavy metal is solidified through the plasma activation reaction and then flows out of the discharge hole of the plasma melting furnace 30. A high-temperature molten pool is arranged in a hearth of the plasma melting furnace 30, so that melting of the charged residues can be accelerated to the maximum extent, and the heat utilization rate and the processing capacity are improved. Meanwhile, molten bath solution has better uniform wrapping on heavy metal, and the formed solidified body has more stable physical and chemical properties.

The residue is gradually melted and forms a molten pool under the action of high-temperature heating and melting of the plasma, and becomes uniform solidified melt. The molten liquid stays in the hearth for a certain time, so that the molten liquid is subjected to vitrification-like reaction under the action of high-temperature plasma activation, finally flows out of the discharge port and forms a glass solidified body (glass body for short) after natural cooling or water quenching cooling, and the generation of metastable and non-equilibrium combined complex components is effectively inhibited and avoided. Most of the metal elements and compounds thereof which are not easily volatilized, such as copper, in the residue enter the glass solidified body.

The vitreum leaching toxicity concentration generated by the plasma melting furnace 30 is lower than the national standard, and can be used as common waste treatment. Meanwhile, the glass solidified body after partial residue melting treatment can be recycled and used as cement ingredients, building materials, heat insulation materials or craft product materials and the like, and recycling of partial hazardous wastes is realized.

The plasma melting furnace 30 is generally designed by micro negative pressure, the furnace body has good sealing effect, no harmful gas leaks, the volatilization of useful components can be greatly reduced, only a very small amount of waste gas and flue gas is discharged, the operating environment is good, and the environmental protection condition is excellent.

The ash transfer unit 40 and the bottom slag mixing device 50 are sequentially disposed between the slag outlet and the plasma-melting furnace 30 to pre-treat the slag entering the plasma-melting furnace 30.

The ash conveying unit 40 comprises a water-sealed scraper slag extractor for cooling the residue and a closed belt conveying mechanism for conveying the residue.

The water seal scraper slag extractor is arranged at the slag outlets of the rotary kiln 10 and the secondary combustion chamber 20, and the belt conveying mechanism is connected between the water seal scraper slag extractor and the bottom slag mixing device 50. The water seal scraper slag extractor's inslot is filled with cooling water, and the slag from slag notch department exhaust enters into the inslot internal cooling, and this makes the flue gas and the slag that burn the production all not direct and external contact, reaches sealed effect. The burned residues are rapidly cooled after entering water, and are continuously output to a closed belt conveying mechanism by a water seal scraper slag extractor, and are automatically conveyed to a bottom slag mixing device 50, so that automatic slag discharging and automatic conveying are realized.

And a hopper interface is additionally arranged and is inserted into the water in the groove of the water seal scraper slag extractor by 150mm, and the water level is kept constant through automatic water supplement.

The bottom slag mixing device 50 is arranged between the belt conveying mechanism and the feed inlet of the plasma melting furnace 30, and is used for crushing the residues conveyed by the belt conveying mechanism and mixing the crushed residues with the flux promoter to prepare a mixed material; the fluxing agent acts to facilitate melting of the residue to form a stable vitreous body, which may include a silicate mixture.

As shown in fig. 2, the bottom slag mixing device 50 may include a crusher 51 for crushing the slag, a mixer 52 for mixing the crushed slag with a fusing accelerator to form a mixed material, a double roll granulator 53 for receiving the mixed material from the mixer 52 and forming slag particles, and a vibrating silo 54 for receiving the slag particles from the double roll granulator 53 and feeding the same into the plasma melting furnace 30.

Specifically, the belt conveyor first pours the residue into a hopper of the crusher 51 for crushing. A dust removal device can be arranged at the feeding port of the crusher 51 to reduce the dust content of air. The crushed residue is conveyed to a storage bin 55 through a first bucket elevator, a batching auger is arranged at the bottom of the storage bin 55, and the residue in the storage bin is conveyed to a batching scale by the batching auger. The computer batching system is weighed according to the components of the fusing agent by a batching scale, enters the buffer bin through the discharge valve, enters the second bucket elevator through the screw conveyor, and enters the to-be-mixed bin 56 through the second bucket elevator.

Meanwhile, a set of hoisting device 57 is arranged at the inlet of the third bucket elevator, and the flux promoting material bag is hoisted and transferred to the inlet of the third bucket elevator by the hoisting device 57 and enters the formula bin 58 through the third bucket elevator. The bottom of the formula bin 58 is provided with a material mixing auger which conveys the flux promoting material bag in the formula bin into a material mixing scale. The computer batching system is weighed according to the components of the fusing agent by a batching scale, enters the buffer bin through the discharge valve, enters the second bucket elevator through the screw conveyor, and enters the to-be-mixed bin 56 through the second bucket elevator.

The residue and fluxing agent enter the mixer 52 together through a discharge valve at the bottom of the bin 56 to be mixed. The mixer 52 mixes materials according to the set mixing time, after mixing, a discharge valve at the bottom of the mixer 52 is opened, the materials are discharged to a fourth bucket elevator, the mixed materials are conveyed into a hopper of a double-roller granulator 53 through the fourth bucket elevator, granulation is started, and the granularity is 6-10mm, preferably 8 mm. The prepared particles fall into a metal bucket on the connecting table. The transfer trolley transfers the metal barrel after receiving the materials to a vibration bin 54 for further treatment. When the vibrating bin 54 is used for blanking, the first pneumatic gate valve at the bottom of the vibrating bin is opened firstly, then the second high-temperature-resistant pneumatic gate valve is opened, and granules fall into the plasma melting furnace 20 for blanking. Wherein the feeding speed of the vibration silo 54 is controlled by adjusting the amplitude of the vibration motor.

The smoke outlet of the plasma melting furnace 30 is connected with the secondary combustion chamber 20 through a smoke outlet pipe 31, and the smoke generated by the melting treatment in the plasma melting furnace 30 is conveyed into the secondary combustion chamber 20 through the smoke outlet pipe 31 and is combusted again in the secondary combustion chamber 20 together with the smoke generated by the rotary kiln 10.

The second combustion chamber 20 is connected with an air inlet of the waste heat boiler 60 through a first flue 21, and conveys high-temperature flue gas formed after re-combustion to the waste heat boiler 60 for selective non-catalytic reduction (SNCR). In the exhaust-heat boiler 60, reducing agents such as urea solution and the like react with nitrogen oxides in the high-temperature flue gas, so that the aim of removing the nitrogen oxides in the flue gas is fulfilled. Through SNCR, the heat of high temperature flue gas is retrieved by exhaust-heat boiler 60, can produce a large amount of steam, and the steam that produces can supply the inside and other users in factory of production line to use, avoids flue gas calorific loss.

Specifically, urea solution is uniformly sprayed on a water-cooled wall in the range of 900-1050 ℃ of the flue gas temperature in the waste heat boiler 60, and the urea solution reacts with nitrogen oxides in the high-temperature flue gas, so that the aim of removing the nitrogen oxides in the flue gas is fulfilled. After the high-temperature flue gas is treated by the waste heat boiler 60, the temperature can be reduced to 550 ℃ or below. An air outlet of the waste heat boiler 60 is connected with the quenching tower 70 through a second flue 61, and the flue gas is output from the air outlet of the waste heat boiler 60 and is conveyed to the quenching tower 70 through the second flue 61. The fly ash generated in the exhaust heat boiler 60 is discharged from the bottom thereof for collection treatment.

Flue gas enters the quench tower 70 primarily from above it. The two-fluid nozzle is arranged in the quenching tower 70, and the sprayed atomized liquid drops exchange heat with the flue gas entering the quenching tower 70 to take away the heat of the flue gas. Under the action of compressed air, the compressed air and NaOH solution are beaten for a plurality of times in the spray head, the NaOH solution is atomized into atomized liquid drops about 0.08mm, the atomized liquid drops exchange heat with high-temperature flue gas fully, the atomized liquid drops are quickly evaporated in a short time (the evaporation time is short, 100% evaporation is ensured, the bottom is not wetted), and heat is taken away, so that the temperature of the flue gas is instantly reduced to below 200 ℃, and the water content (mass ratio) is less than 3%. The flue gas flow rate is controlled to ensure that the flue gas is inThe retention time between 200 ℃ and 500 ℃ is less than 1s, so that the re-synthesis of dioxin is prevented. In addition, as the atomized liquid drops are formed by NaOH solution, the NaOH solution and SO in the flue gas₂And neutralizing the acid gas to reach the aim of primary deacidification.

A portion of the fly ash removed from the flue gas in the quench tower 70 is removed from the bottom of the quench tower 70 for collection and disposal.

The quenched flue gas is conveyed from the quenching tower 70 to the dry deacidification tower 80 through the third flue 71 to be subjected to adsorption purification treatment. In order to meet the emission standard of waste flue gas and ensure the emission standard of heavy metals (especially Hg), dioxin and furan, the dry deacidification tower 80 adopts an auxiliary purification measure of activated carbon injection adsorption except that the incineration process and technical parameters are strictly controlled. Because the activated carbon has extremely large specific surface area, even a small amount of activated carbon can achieve high adsorption and purification efficiency as long as the activated carbon is uniformly mixed with the flue gas and the contact time is long enough.

The flue gas enters a dry-method deacidification tower 80 to be fully contacted with the mixed powder of hydrated lime, activated carbon and fly ash sprayed into the tower, and the flue gas reacts to form dust-shaped calcium salt, so that the aim of removing sulfur dioxide, hydrogen chloride and other acidic gases in the flue gas is fulfilled.

The dust-containing flue gas output from the dry deacidification tower 80 is conveyed to a dust removal unit through an air inlet pipe 81 for dust removal and filtration treatment. The dust removal unit includes a cyclone dust collector 91 and a bag type dust collector 92 which are sequentially connected between the dry acid removal tower 80 and the wet acid removal tower 100.

Flue gas gets into cyclone 91 by air-supply line 81, gets rid of the large granule dust through cyclone 91, improves dust collection efficiency. The cyclone dust collector 91 adopts a double-inlet dust collector, so that the resistance of the equipment is reduced. The outlet of the cyclone dust collector 91 is connected with a bag type dust collector 92, and the flue gas after primary dust removal and filtration is conveyed to the bag type dust collector 92 for secondary dust removal and filtration. The filter bag in the bag-type dust collector 92 is in full contact with the flue gas slowly passing through the filter bag, so that the pollutants such as heavy metal (especially Hg), dioxin, furan and the like in the flue gas are adsorbed and purified, the activated carbon adsorbing the pollutants such as heavy metal, dioxin and the like falls into the ash hopper at the bottom of the bag-type dust collector 92, and the purified flue gas enters the cleaning chamber of the bag-type dust collector 60 through the opening of the filter bag and is discharged from the outlet of the bag-type dust collector 92.

A thermometer and infrared heating equipment are arranged at the outlet of the cyclone dust collector 91, and when the detected flue gas temperature is lower than the designed value, the infrared heating equipment is started to heat the flue gas temperature to the designed value, so that the blocking probability of the bag type dust collector 92 can be reduced. The bag filter 92 uses high efficiency PTFE coated filter material to filter out the smoke and dust in the flue gas to ensure that the designed smoke and dust emission standard is met, and the collected fly ash is transported out for safe landfill.

The wet deacidification tower 100 is connected with the bag type dust collector 92 to deacidify the flue gas after dust removal and filtration.

The upper part in the wet deacidification tower 100 is provided with a spraying device, and NaOH solution is sprayed out through the spraying device. The flue gas enters the wet-method deacidification tower 100 and is mixed with the sprayed NaOH solution for contact reaction in the rising process to remove HCl, HF and SO in the flue gas₂. The inner wall of the wet deacidification tower 100 is used for glass flake corrosion prevention, so that the safety and reliability of equipment are improved, and the operation period is prolonged.

In the present invention, an air preheater 110 is further disposed between the wet acid-removing tower 100 and the bag filter 92, and is used for passing the flue gas and recovering the heat of the flue gas, and the recovered heat heats the air and then serves as the combustion-supporting air for the rotary kiln 10. The air preheater 110 is provided with a flue gas channel and an air channel for heat exchange; the flue gas channel is respectively communicated with the bag type dust collector 92 and the wet deacidification tower 100; the air channel has an inlet for receiving external cold air and an outlet connected to the second combustion chamber 20 through a ventilation duct 111. The flue gas discharged from the bag type dust collector 92 enters a flue gas channel of the air preheater 110, exchanges heat with cold air entering the air channel, and the flue gas after heat exchange and temperature reduction is output from the flue gas channel and enters the wet-process deacidification tower 100; the cold air in the air channel is heated after heat exchange to form hot air, and the hot air is conveyed into the second combustion chamber 20 through the ventilation pipeline 111 to be used as combustion-supporting air of the second combustion chamber 20, so that the combustion efficiency of the second combustion chamber 20 is improved.

In order to further utilize heat, the ventilation pipeline 111 is connected into the belt conveying mechanism, so that hot air conveyed by the ventilation pipeline 111 passes through the belt conveying mechanism, and the hot air conveyed by the ventilation pipeline 111 is used for heating residues conveyed by the residue belt conveying mechanism, so that the water content of the residues is reduced, and the treatment effect of the subsequent plasma melting furnace 30 is effectively improved.

Further, the ventilation duct 111 is provided with a filter for filtering air, a dryer 22 for drying air, and a blower 23. The filter, the dryer 22 and the blower 23 are all arranged on a pipeline section of the ventilation pipeline 111 between the second combustion chamber 20 and the belt conveying mechanism, and the hot air passing through the belt conveying mechanism is filtered, dried and the like and then enters the second combustion chamber 20.

Wherein, the blower 23 provides power to send hot air into the second combustion chamber 20. The filter may include a coarse filter 24 and a fine filter 25 with different filtering precisions, respectively filtering out particulate impurities with different particle sizes in the air. The dryer 22 is located at the rear end of the filter, and is used for drying the filtered flue gas and finally entering the second combustion chamber 20.

The temperature of the flue gas output by the wet deacidification tower 100 is about 60 ℃, and the output flue gas can be conveyed to a chimney 130 through a fourth flue 101 to be discharged. In order to avoid the "white smoke" phenomenon at the outlet of the chimney 130, the hazardous waste incineration disposal system of the invention further comprises a flue gas heater 120; the flue gas heater 120 is connected between the wet acid removal tower 100 and the chimney 130, and receives the flue gas from the wet acid removal tower 100 and heats the flue gas. The heated clean smoke is discharged from the chimney 130 under the driving of the fan 131.

The flue gas heater 120 is also connected with the waste heat boiler 60 through a steam pipeline 121, and steam generated by the waste heat boiler 60 is used as a heat source, so that external steam is not needed, and energy is saved. The steam outlet of the waste heat boiler 60 is provided with a steam distributing cylinder 61, and is connected with a steam pipeline 121 through the steam distributing cylinder 61.

The steam exchanges heat with the flue gas passing through the flue gas heater 120 in the flue gas heater 120, so that the temperature of the flue gas is raised, and the steam is condensed and discharged to a desalting water tank for subsequent treatment after the heat exchange.

In addition, in order to solve the corrosion problem of the flue gas heater 120, the heat exchange tube of the flue gas heater 120 is made of fluoroplastic steel, which is different from the conventional stainless steel heat exchange tube, so that the flue gas heater is not easy to corrode and has long service life.

The hazardous waste incineration disposal system of the present invention is used for incineration disposal of hazardous waste, and referring to fig. 1, the hazardous waste incineration disposal method may include the steps of:

and S1, sending the dangerous waste into the rotary kiln 10 for incineration treatment.

The flue gas generated by incineration is conveyed into the secondary combustion chamber 20, and the residue generated by incineration and the residue generated in the secondary combustion chamber 20 enter the ash conveying unit 40 through a shared slag outlet.

S2, the slag is cooled and dried by the slag transmission unit 40, then crushed by the bottom slag mixing device 50 and mixed with the flux promoter to prepare a mixed material, and then the mixed material is sent into the plasma melting furnace 30 for plasma melting treatment to form a vitreous body.

And S3, conveying the flue gas generated by the melting treatment in the plasma melting furnace 30 to the secondary combustion chamber 20, and performing secondary combustion treatment on the flue gas from the rotary kiln 10 and the plasma melting furnace 30 in the secondary combustion chamber 20 to decompose harmful components including dioxin in the flue gas and output high-temperature flue gas.

S4, conveying the high-temperature flue gas into the waste heat boiler 60, and removing nitrogen oxides in the high-temperature flue gas through reaction with the urea solution sprayed into the waste heat boiler 60.

And S5, conveying the cooled flue gas from the waste heat boiler 60 to the quenching tower 70 for heat exchange and cooling again, and simultaneously preventing the dioxin from being resynthesized.

After the high-temperature flue gas is treated by the waste heat boiler 60, the temperature can be reduced to 550 ℃ or below. In the quenching tower 70, liquid drops with the diameter of about 0.08mm are sprayed out through a double-fluid nozzle, the liquid drops and the flue gas exchange heat sufficiently, the liquid drops are evaporated quickly in a short time, heat is taken away, the temperature of the flue gas is instantly reduced to be below 200 ℃, and the water content (mass ratio) is less than 3%. Because the residence time of the flue gas between 200 ℃ and 500 ℃ is less than 1s, the resynthesis of dioxin is prevented.

And S6, conveying the flue gas subjected to heat exchange and temperature reduction to a dry-method deacidification tower 80 to remove acid gas in the flue gas.

The flue gas enters a dry method deacidification tower 80 andthe mixed powder of slaked lime, active carbon and fly ash sprayed into the tower is fully contacted and reacts to form dust-like calcium salt, thereby achieving the purpose of removing sulfur dioxide, hydrogen chloride and other acidic gases in the flue gas. The water content in the flue gas is Ca (OH)₂Liquid phase ion reaction occurs between the particle surface and the acid gas, and the deacidification efficiency and the utilization rate of the absorbent are obviously improved.

And S7, conveying the purified flue gas to a dust removal unit for dust removal and filtration treatment, and removing pollutants including heavy metals and dioxin in the flue gas.

The dust removal unit performs two-stage dust removal and filtration treatment on the flue gas through a cyclone dust collector 91 and a bag type dust collector 92.

S8, conveying the dedusted and filtered flue gas into a wet deacidification tower 100, and deacidifying the flue gas by using alkali liquor to remove HCl, HF and SO in the flue gas₂。

And S9, conveying the flue gas subjected to deacidification treatment to the flue gas heater 120, carrying out heat exchange between the steam discharged by the waste heat boiler 60 and the flue gas by the flue gas heater 120, heating the flue gas, and then discharging the flue gas through the chimney 130.

As the heat source of the flue gas heater 110 is provided by the steam generated by the waste heat boiler 60, the external steam supply is not needed, and the energy is saved.

The specific operation of each treatment process of the hazardous waste incineration flue gas treatment method can be referred to the system related description.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A hazardous waste incineration treatment system is characterized by comprising a rotary kiln for carrying out incineration treatment on hazardous waste, a secondary combustion chamber for carrying out secondary combustion treatment on flue gas, a plasma melting furnace for carrying out melting treatment on residues, an ash residue transmission unit, a waste heat boiler, a quench tower, a dry deacidification tower, a dust removal unit and a wet deacidification tower;

2. The hazardous waste incineration treatment system according to claim 1, wherein a smoke outlet of the rotary kiln is butted with a smoke inlet of the secondary combustion chamber, and smoke generated by incineration in the rotary kiln enters the secondary combustion chamber through the smoke outlet and the smoke inlet;

3. The hazardous waste incineration disposal system of claim 1, wherein the ash transfer unit comprises a water-sealed scraper slag extractor for cooling the residue, a closed belt conveyor mechanism for conveying the residue;

4. The hazardous waste incineration system according to claim 3, further comprising a bottom slag mixing device that crushes the residue and mixes with a flux promoter; the bottom slag mixing device is arranged between the belt conveying mechanism and the feeding hole of the plasma melting furnace.

5. The hazardous waste incineration disposal system of claim 4, wherein the bottom slag mixing device comprises a crusher to crush the residues, a blender to mix the crushed residues with the fusing agent therein to form a mixed material, a double-roller granulator to receive the mixed material from the blender and to form residue particles, and a vibrating bin to receive the residue particles from the double-roller granulator and to feed the residue particles into the plasma melting furnace.

6. The hazardous waste incineration treatment system of claim 3, wherein the dust removal unit comprises a cyclone and a bag filter sequentially connected between the dry deacidification tower and the wet deacidification tower.

7. The hazardous waste incineration processing system according to claim 6, further comprising an air preheater disposed between the bag house and the wet deacidification tower, for allowing the flue gas to pass through and recovering heat of the flue gas, wherein the recovered heat is used as combustion air for the secondary combustion chamber after heating the air.

8. The hazardous waste incineration disposal system of claim 7, wherein the air preheater has a flue gas channel and an air channel therein for heat exchange; the flue gas channel is respectively communicated with the bag type dust collector and the wet method deacidification tower, the outlet of the air channel is connected with the secondary combustion chamber through a ventilating pipeline, and the air after heat exchange with the flue gas is conveyed into the secondary combustion chamber.

9. The hazardous waste incineration system according to claim 8, wherein the ventilation duct is provided with a filter for filtering air, a dryer for drying air, and a blower.

10. The hazardous waste incineration system according to claim 8, wherein the belt transport mechanism is provided on the ventilation duct, and the residue is heated by air transported by the ventilation duct.

11. The hazardous waste incineration system of any one of claims 1 to 10, wherein the hazardous waste incineration system further comprises a flue gas heater; the flue gas heater is connected between a chimney and the wet acid removal tower, and heats the flue gas discharged by the wet acid removal tower and then discharges the heated flue gas to the chimney.

12. The hazardous waste incineration disposal system of claim 10, wherein the flue gas heater is connected to the waste heat boiler through a steam pipe and a gas-distributing cylinder, and steam generated from the waste heat boiler is used as a heat source.

13. A hazardous waste incineration disposal method, characterized by using the hazardous waste incineration disposal system according to any one of claims 1 to 12; the method for incinerating and treating hazardous wastes comprises the following steps:

s1, feeding the dangerous waste into a rotary kiln for incineration treatment;