CN114857588B

CN114857588B - Waste pyrolysis treatment system and method

Info

Publication number: CN114857588B
Application number: CN202210696309.3A
Authority: CN
Inventors: 张瑞亮; 高德辉; 吕静; 崔瑶瑶; 吴若晗; 邹佳成; 高术恩; 杨琨; 崔晓伟
Original assignee: Qingdao Derui Huifeng Environmental Protection Technology Co ltd
Current assignee: Qingdao Derui Huifeng Environmental Protection Technology Co ltd
Priority date: 2022-06-20
Filing date: 2022-06-20
Publication date: 2023-05-09
Anticipated expiration: 2042-06-20
Also published as: CN114857588A

Abstract

The invention provides a waste pyrolysis treatment system and a waste pyrolysis treatment method, which are characterized in that: comprises a pretreatment device, a pyrolysis device, a heat recovery device and a flue gas purification device which are connected in sequence. The proportion of plastic rubber products in medical waste is very high, and a large amount of dioxin cancerogenic pollutants are easily generated in the treatment process. And plastic rubber products are easy to form hard coking on the wall of the reactor, so that the energy consumption of the pyrolysis device is increased, and the safe operation of the pyrolysis device is threatened. The invention utilizes the waste heat of flue gas to generate superheated steam, and leads the superheated steam into the pyrolysis reactor in a low-temperature anaerobic state, so that medical waste can be rapidly treated at 350 ℃, coking phenomenon can not occur, the generation of dioxin in the treatment process is more effectively restrained, and the energy consumption is greatly reduced.

Description

Waste pyrolysis treatment system and method

Technical Field

The invention belongs to the technical field of heat energy, and particularly relates to a medical waste steam pyrolysis treatment system and a method.

Background

The medical waste has tens of times or hundreds of times of the virus hazard of the common domestic waste, has the characteristics of space pollution, acute infection, latent infection and the like, is very easy to become a source of virus transmission if being managed or disposed improperly, and is easy to cause pollution of soil, water, air and the like. Medical waste is classified as HW01 in the national hazardous waste directory, and the disposal of the medical waste is strictly regulated.

Since 2011, the amount of medical waste generated has been increasing year by year. Medical waste in China is mainly divided into outpatient medical waste and medical waste in hospitalization department, wherein the waste in hospitalization department occupies main body. The data show that the medical waste output of China is increased from 192 ten thousand tons to 226 ten thousand tons in 2016-2019. The medical waste production in 2020 is increased by 25% under the influence of new crown epidemic situation, and the total yield reaches 283 ten thousand tons.

From the condition of 293 ground markets nationwide, about half of the medical waste disposal capacity of the ground markets basically meets the daily requirements, more than 80 ground markets basically can cope with sudden epidemic situations, and about 50 ground markets have insufficient disposal capacity. Medical waste disposal capability generally meets daily requirements in a national aspect, but the problems of unbalanced disposal capability area distribution, unqualified environmental protection emission of partial facilities, unreasonable process selection of partial facility technology, insufficient emergency disposal capability and the like still exist.

The technical pain points of the disposal means of medical waste currently on the market limit its development:

1. high temperature incineration: the cost is high, the air pollution is serious, severe toxic substances such as dioxin, polycyclic aromatic compounds, polychlorinated biphenyl and the like and harmful gases such as hydrogen chloride, hydrogen fluoride, sulfur dioxide and the like are easy to generate, a perfect tail gas purification system is required to be configured, and bottom slag and fly ash are harmful.

2. Pressure steam sterilization: the volume and the appearance are not changed basically, air pollutants can be discharged, odor is easy to generate, and formaldehyde, phenol, mercury and other substances cannot be treated.

3. Electromagnetic wave sterilization method: the construction and operation cost is not low, the weight reducing effect after treatment is not good, odor is generated, and the method is not suitable for treating blood and dangerous chemical substances.

4. Traditional pyrolysis method: the heat energy recovery and utilization rate is low, and the energy consumption is relatively high; the coking of the pyrolysis reactor is serious, the stable operation of the system is affected, and the coking needs to be cleaned regularly.

Disclosure of Invention

The invention provides a medical waste steam pyrolysis treatment system and a method thereof, which aim at market demands and pain points in the prior art, and the invention recovers high-temperature flue gas as a heating source, and the running cost of the system is greatly lower than that of a conventional incineration method. In addition, the invention utilizes high-temperature flue gas to generate superheated steam, and the superheated steam is poured into the pyrolysis reactor, so that the instability of equipment caused by coking of plastic rubber and the like on the reactor in the traditional pyrolysis process is avoided. The steam pyrolysis method utilizes high-temperature steam to realize an anaerobic state and remove acid gases such as chlorine and the like, thereby inhibiting the generation of dioxin; the invention has wide application range, medical wastes do not need to be classified, and therefore, the invention has no obvious selectivity to the treated wastes. The aim is achieved by the following technical scheme: a medical waste steam pyrolysis treatment system comprises a pretreatment device, a pyrolysis device, a heat recovery device and a smoke purification device which are connected in sequence.

The pretreatment device comprises a lifting machine, a negative pressure bin, a pulverizer, a blending machine and a screw conveyor. The negative pressure bin is provided with a hydraulically driven sealing door. An extraction opening and an extraction pipeline are arranged above the negative pressure bin. The crusher is arranged below the negative pressure bin, and the blender is arranged below the crusher. The adulterant machine is connected with an inclined screw conveyor. The discharge port of the screw conveyor is connected with the feed inlet of the pyrolysis device.

The pyrolysis device comprises a feeding mechanism, a pyrolysis reactor, a slag extractor, an ash box, a front exhaust chamber, a rear exhaust chamber, a water vapor pipeline, a volatile gas pipeline, an external heating furnace, a flue gas pipeline a and an air supply mechanism. A certain number of atomizing nozzles are arranged in the ash box. The steam pipe is connected with the front exhaust chamber, and a flow regulator a is arranged on the steam pipe. The volatile gas pipeline is connected with the rear exhaust chamber. The air supply mechanism is connected with an air extraction opening above the negative pressure bin through an air extraction pipeline.

The heat recovery device comprises a combustor, a gas dispersion chamber, an incineration chamber, a steam generation chamber, a liquid level adjusting water tank, a flue gas pipeline b and a superheated steam generator. The heat recovery device is connected with the external heating furnace through a pipeline. The gas dispersion chamber is connected with a water vapor pipeline and a volatile gas pipeline, a gas flow regulator b is arranged on a flue gas pipeline b, and the flue gas pipeline b is connected with a superheated steam generator.

The flue gas purification device comprises a flue gas washing tower, an activated carbon adsorption box and a chimney.

The pyrolysis reactor is of a horizontal cylindrical structure, and three spiral blades with different specifications and a steam disturbance mechanism are arranged in the cylinder. The steam disturbance mechanism is composed of an odd number of steam spray pipes which are arranged along the circumferential direction, and the number of the steam spray pipes is increased along with the increase of the material flow or the heat value.

The steam spray pipe is provided with a plurality of steam spray nozzles, and the number of the steam spray nozzles is increased along with the increase of the reaction temperature.

The steam nozzle is arranged in a reaction zone at 200-350 ℃, and the distribution density or the increasing amplitude of the steam nozzle increases with the increase of the reaction temperature.

The gas dispersion chamber surrounds at 1/5 of the front end of the incineration chamber, and a plurality of gas nozzles are uniformly distributed along the circumference between the gas dispersion chamber and the incineration chamber.

The number of gas nozzles increases with increasing material flow or heating value.

The steam generation chamber surrounds the middle 3/5 of the incineration chamber and is connected with the superheated steam generator through a pipeline, and the superheated steam generator is connected with the pyrolysis reactor through a pipeline.

A method of the above medical waste steam pyrolysis treatment system comprising the steps of:

(1) The garbage bin with medical waste is conveyed to the inlet of the negative pressure bin by the lifter, the hydraulic driving sealing door of the negative pressure bin is opened, and the dumping mechanism of the lifter pushes the garbage bin to pour the medical waste into the negative pressure bin. Medical waste is crushed into particles with the particle size less than or equal to 30mm by a crusher below the negative pressure bin. The blender mixes CaO particles with the particle size less than or equal to 30mm into the material. The mixed materials are sent to an inlet of a pyrolysis system through a screw conveyor.

The process comprises the following steps: the air extraction opening above the negative pressure bin is connected with the air supply mechanism through an air extraction pipeline, and polluted air in the bin is sucked into the incineration chamber by the air supply mechanism for high-temperature incineration and sterilization. The inside of the bin is always kept in a negative pressure state, so that polluted air is prevented from leaking out to pollute the environment.

The process comprises the following steps: the blender is used for mixing CaO particles into the raw materials according to the content of chlorine in the raw materials so as to remove HCL gas generated in the reaction process and inhibit the generation of dioxin. The CL/Ca value is from 2 to 4, preferably 3.

(2) The pyrolysis device receives material from the pretreatment device. The vibrator and the stirrer are arranged in the feeding mechanism of the pyrolysis device, so that the blockage of materials is avoided. The material is evenly distributed into the two pyrolysis reactors. The material in the pyrolysis reactor is moved forward by the driving of the helical blades and gradually heated.

The process comprises the following steps: the rotational speed of the pyrolysis reactor is set according to the compositions of water, combustible components and ash entering the materials, so that the materials with different components are ensured to fully react in the reactor.

(3) The materials are indirectly heated by the high-temperature flue gas in the outer hot furnace chamber in a low-temperature area below 200 ℃ in the pyrolysis reactor. The materials are directly heated by the superheated steam of 500-600 ℃ in a high temperature region of 200-350 ℃ in the pyrolysis reactor, and are indirectly heated by the high temperature flue gas of the external hot furnace chamber. The temperature of the material in the pyrolysis reactor gradually rises during the forward movement, and the following reaction occurs:

volatilizing free water in the materials at 100-150 ℃;

volatilizing the water of the material at 150-200 ℃ and volatilizing a small amount of organic matters;

and volatilizing and separating out organic matters in the materials at 200-350 ℃ to obtain a final ash product.

The process comprises the following steps: the superheated steam is led into the pyrolysis reactor to heat the materials efficiently and uniformly, and the reaction can be completed at about 350 ℃, so that the treatment time is shortened greatly. Compared with the conventional pyrolysis process, the method can save 1/2-3/4 of treatment time.

The process comprises the following steps: introducing superheated steam into the pyrolysis reactor ensures an oxygen-free state in the pyrolysis reactor, and the superheated steam enhances the effect of absorbing HCL by CaO and inhibits the generation of dioxin.

The process comprises the following steps: a steam disturbance mechanism is arranged in the pyrolysis reactor, and coking on the cylinder wall is removed by utilizing the principle of thermal expansion and cold contraction under the action of superheated steam; meanwhile, the superheated steam is utilized to assist in heating materials, so that the heat transfer efficiency of the reactor is improved.

(4) The slag extractor receives the high-temperature slag product from the pyrolysis reactor, cools the high-temperature slag product and sends the cooled high-temperature slag product into a slag box.

The process comprises the following steps: the slag extractor jacket structure is provided with flowing cooling water for cooling high-temperature pyrolysis products, so that the temperature of the pyrolysis products discharged out of the system is lower than 60 ℃; the atomizing nozzle arranged in the ash box sprays water mist to prevent ash from generating a large amount of dust.

(5) Most of water vapor generated in the reaction stage of the pyrolysis reactor at 100-150 ℃ enters the front exhaust chamber, and most of volatile combustible gas generated when the material is heated to 200-350 ℃ enters the rear exhaust chamber. The gas in the front exhaust chamber enters the steam pipeline, the gas in the rear exhaust chamber enters the volatile gas pipeline, and the gas is collected and then sent into the heat recovery device.

The process comprises the following steps: the opening of the flow regulator a arranged on the steam pipeline is regulated according to the moisture content of the original material, so that the volatile combustible gas discharged from the rear exhaust chamber is reduced as much as possible, and the volatile combustible gas is thoroughly decomposed in the high-temperature stage of the pyrolysis reactor. The opening degree of the flow regulator a is adjusted as follows:

the water content is less than 10%, and the flow regulator a is closed;

the water content is 10-20%, and the flow regulator a is opened by 50%;

the water content is 20-30%, and the flow regulator a is opened by 80%;

the water content is more than 30%, and the flow regulator a is opened by 100%.

(6) The heat recovery device receives the exhaust gas from the pyrolysis device. The exhaust gas is injected into the combustion chamber uniformly along the circumference after entering the gas dispersion chamber. The harmful components of the exhaust gas are completely decomposed under the high temperature atmosphere of the incineration chamber. The high-temperature flue gas after complete combustion is led into an external heating furnace of the pyrolysis device through a flue gas pipeline b to serve as a heat source.

The process comprises the following steps: the gas nozzles in the gas dispersion chamber are arranged along the circumferential tangential direction, and the waste gas enters the incineration chamber through the gas nozzles to form a vortex effect, so that the waste gas is combusted more fully, and harmful components in the waste gas are decomposed more thoroughly.

The process comprises the following steps: the temperature in the incineration chamber is regulated by the burner, the high-temperature atmosphere of 850-900 ℃ in the incineration chamber is maintained, and the effective volume of the high-temperature atmosphere ensures that the waste gas stays in the incineration chamber for more than 2S, so that harmful substances in the waste gas are more fully decomposed.

(7) The steam generating chamber of the heat recovery device utilizes the heat energy of the incineration chamber to generate normal pressure saturated steam at 100 ℃.2/3 of steam enters the flue gas pipeline a through a pipeline, and the high-temperature flue gas is rapidly cooled to below 200 ℃ to inhibit the generation of harmful substances such as dioxin. The remaining 1/3 of the steam enters a superheated steam generator through a pipeline and is heated to 500-600 ℃ by high-temperature flue gas with the temperature of 850 ℃. Superheated steam is introduced into the pyrolysis reactor through a pipe to heat the material.

(8) The pyrolysis device receives the high-temperature flue gas from the heat recovery device and indirectly heats the pyrolysis reactor. The external heating furnace is provided with two burners for adjusting the high-temperature atmosphere with the temperature of 400-600 ℃ of the external heating furnace. The high-temperature flue gas heated up by the pyrolysis reactor is led into a flue gas purifying device.

The process comprises the following steps: and adjusting the opening of the flow regulator b arranged on the flue gas pipeline b according to the temperature of the external heating furnace, and increasing the opening of the flow regulator b when the temperature of the external heating furnace exceeds the set temperature.

The processes of the process (7) and the process (8) are set to save energy by 30% compared with the traditional pyrolysis system or process.

(9) The flue gas cleaning device receives flue gas from the pyrolysis device. An alkali liquor circulating spraying mechanism is arranged in the flue gas washing tower, and acid gas and dust are removed from flue gas under the action of alkali liquor. The flue gas enters an activated carbon adsorption box, and the activated carbon can adsorb heavy metal elements possibly existing in the flue gas. The purified flue gas is discharged into the atmosphere through a chimney.

Compared with the prior art, the invention has the following advantages and positive effects:

1. the invention fully utilizes the waste heat of the flue gas as a heating source, has high heat energy utilization rate, and reduces the energy consumption by 30 percent compared with the traditional pyrolysis process.

2. According to the invention, the superheated steam is introduced into the pyrolysis reactor, so that the superheated steam can efficiently and uniformly heat materials, and the reaction can be completed at about 350 ℃, thereby greatly shortening the treatment time. Compared with the conventional pyrolysis process, the method can save 1/2-3/4 of treatment time.

3. According to the invention, caO particles are doped into the material according to the CL/Ca ratio of 2-4 for removing HCL gas generated in the reaction process. Under the action of the superheated steam, the effect of absorbing HCL by CaO is enhanced, and the generation of dioxin is inhibited.

4. The reactor is internally provided with a steam disturbance mechanism, and coking on the cylinder wall is removed by utilizing the principle of thermal expansion and cold contraction under the action of superheated steam; meanwhile, the superheated steam is used for assisting in heating materials, so that the heat transfer efficiency of the reactor is improved. The system structure is more compact. The equivalent treatment scale and the small occupied area are only 1/4 of the prior art equipment.

5. Medical waste treated by the present invention does not need to be sorted and therefore has no obvious selectivity to the treated waste.

Drawings

Fig. 1 is a schematic diagram of a medical waste steam pyrolysis treatment system according to the present invention.

Fig. 2 is a schematic view of a pretreatment device of a medical waste steam pyrolysis treatment system according to the present invention.

Fig. 3 is a front view of a pyrolysis device and a heat recovery device in a medical waste steam pyrolysis treatment system according to the present invention.

Fig. 4 is a top view of fig. 3.

Fig. 5 is a rear view of fig. 3.

Fig. 6 is a schematic view of a flue gas cleaning device in a medical waste steam pyrolysis treatment system according to the present invention.

FIG. 7 is a schematic diagram showing the connection of a steam perturbation mechanism and a reactor in a medical waste steam pyrolysis treatment system according to the present invention.

Fig. 8 is a schematic diagram of a main body of a heat recovery device in a medical waste steam pyrolysis treatment system according to the present invention.

Fig. 9 is a left side view of fig. 8.

Fig. 10 is a schematic view of a superheated steam generator in a medical waste steam pyrolysis treatment system of the present invention.

Detailed Description

Referring to fig. 1 to 10, for an embodiment of a medical waste steam pyrolysis treatment system of the present invention, as shown in fig. 1, the system includes a pretreatment device 10, a pyrolysis device 20, a heat recovery device 30, and a smoke purification device 40, which are sequentially connected.

As shown in fig. 2, the pretreatment device 10 includes a lifter 101, a negative pressure hopper 102, a pulverizer 103, a blender 104, and a screw conveyor 105. The negative pressure reservoir 102 is provided with a hydraulically driven sealing door. An extraction opening and an extraction pipeline are arranged above the negative pressure bin 102. Below the negative pressure bin 102 is a pulverizer 103, and below the pulverizer 103 is a blender 104. The spike machine 104 is connected to an inclined screw conveyor 105. The discharge port of the screw conveyor 105 is connected with the feed port of the pyrolysis device 20.

The garbage can filled with medical wastes is conveyed to the inlet of the negative pressure bin 102 by the lifter 101, the hydraulic driving sealing door of the negative pressure bin 102 is opened, and the dumping mechanism of the lifter pushes the garbage can to pour the medical wastes into the negative pressure bin 102. The medical waste is crushed into particles with the particle size less than or equal to 30mm by a crusher 103 below the negative pressure bin 102. The blender 104 blends CaO particles with the particle size less than or equal to 30mm into the material. The mixed material is fed to the inlet of pyrolysis apparatus 20 via screw conveyor 105.

As shown in fig. 3-5, the pyrolysis apparatus 20 includes a feeding mechanism 201, a pyrolysis reactor 202, a slag extractor 203, a slag box 204, a front exhaust chamber 205, a rear exhaust chamber 206, a steam pipe 207, a volatile gas pipe 208, an external heating furnace 209, a flue gas pipe a210, and an air supply mechanism 211, the external heating furnace 209 surrounds the pyrolysis reactor 202, and the flue gas pipe a210 is disposed at an upper portion of the external heating furnace 209.

The material is evenly distributed through the feed mechanism 201 to the two pyrolysis reactors 202. The material in the pyrolysis reactor 202 is moved forward by the drive of the helical blades and gradually heated. The material in the front stage of the pyrolysis reactor is heated to about 150 ℃, and free water in the material becomes water vapor and enters the front exhaust chamber 205. The organic matter in the latter half of the pyrolysis reactor 202 is decomposed into small molecules of volatile gas and carbide residues, and the volatile gas enters the rear exhaust chamber 206. The carbide residue enters the slag extractor 203, which pushes the residue into the ash bin 204 for storage.

A certain number of atomizing nozzles are arranged in the ash box 204, and the atomizing nozzles are connected with a water pipe to generate water mist to reduce tiny dust generated by ash. The steam pipe 207 is connected to the front exhaust chamber 205, and a flow regulator a212 is provided in the steam pipe 207. A volatile gas line 208 is connected to the rear exhaust chamber 206. The air supply mechanism 211 is connected with an air extraction opening above the negative pressure bin 102 through an air extraction pipeline.

The heat recovery device 30 comprises a burner 301, a gas dispersion chamber 302, an incineration chamber 303, a steam generation chamber 304, a liquid level adjusting water tank 305, a flue gas pipeline b306 and a superheated steam generator 308, as shown in fig. 8. A liquid level adjustment tank 305 is located above the steam generation chamber 304 for adjusting the liquid level of the steam generation chamber 304. The superheated steam generator 308 is arranged above the external heating furnace 209 and is connected with the incineration chamber 303 through a branch pipe of the flue gas pipeline b 306. The incineration chamber 303 is connected with the external heating furnace 209 through a branch pipe of a flue gas pipeline b 306. The gas dispersion chamber 302 is connected to the steam pipe 207 and the volatile gas pipe 208, the gas flow regulator b307 is provided on the flue gas pipe b306, and the flue gas pipe b306 is connected to the superheated steam generator 308.

The gas dispersion chamber 302 surrounds the incineration chamber 303 and is connected to the incineration chamber 303 through a nozzle. The volatile gas enters the gas dispersion chamber 302 and is evenly distributed into the incineration chamber 303 through the nozzle, the combustor 301 generates high temperature by combusting natural gas and ignites the entering volatile gas, and the temperature of the incineration chamber 303 is maintained above 850 ℃, so that harmful substances in the volatile gas are thoroughly decomposed.

As shown in fig. 10, the superheated steam generator 308 is composed of an inner tube array and an outer case. The high temperature flue gas generated from the incineration chamber 303 flows in the tube array, the saturated steam generated from the steam generation chamber 304 flows in the housing, and the steam is heated to 500-600 ℃ by indirect heat exchange.

The flue gas cleaning device 40 comprises a flue gas washing tower 401, an activated carbon adsorption box 402 and a chimney 403 which are connected in sequence. The flue gas enters a flue gas washing tower 401 to remove acid gas and dust under the action of alkali liquor, and then enters an activated carbon adsorption box 402, and activated carbon can adsorb heavy metal elements possibly existing in the flue gas. The cleaned flue gas is vented to the atmosphere through stack 403.

The pyrolysis reactor 202 is of a horizontal cylindrical structure, three helical blades with different radial heights are arranged in the cylinder, the radial heights of the helical blades gradually decrease along the axial direction of the cylinder from the front end to the rear end, and the screw pitch is reduced. The volume of the material is reduced along with the increase of the temperature, the pitch of the blade is reduced by reducing the height of the blade so as to reduce the advancing speed of the material, and the contact area and the contact time of the material and the blade are increased at the same time, so that the heat transfer is enhanced. The rear end of the barrel is provided with a steam perturbation mechanism 213, the arrangement of the helical blades and the steam perturbation mechanism is shown in figure 7. The steam perturbation mechanism 213 is composed of an odd number of steam spouts arranged in the circumferential direction, the number of steam spouts is designed according to the maximum amount and heat value of the item-processed material, and increases as the amount and heat value of the material increases.

The steam spray pipe is provided with a plurality of steam spray nozzles, the temperature of the reactor from the front end to the rear end is gradually increased, and the number of the spray nozzles is increased along with the increase of the reaction temperature. The increase of the number of the nozzles can spray more steam, so that more heat is brought, and the steam can penetrate through the surface layer of the material to accelerate the reaction speed of the material.

The steam nozzle is arranged in a reaction zone at 200-350 ℃, and the distribution density or the increasing amplitude of the nozzle increases with the increase of the reaction temperature.

The gas dispersion chamber 302 surrounds the front end 1/5 of the incineration chamber 303 as shown in fig. 8. A plurality of volatile gas nozzles are uniformly distributed along the circumference between the gas dispersion chamber 302 and the incineration chamber 303.

The number of gas nozzles increases as the flow rate or heating value of the material increases, and the increase in the amount of material processed per unit time requires an increase in the number of nozzles at the time of design. The heat value of the material is the heat value of the material per unit mass, the heat values of the medical wastes in different regions are different, and the number of the nozzles is required to be increased when the heat value is higher than the average value of the medical wastes in China.

The steam generating chamber 304 is surrounded at 3/5 of the middle of the incineration chamber 303, and generates steam by heating water using high-temperature heat dissipation generated by the incineration chamber. As shown in fig. 8. Is connected to the superheated steam generator 308 by a pipe, and the superheated steam generator 308 is connected to the pyrolysis reactor 202 by a pipe.

(1) The garbage can filled with medical wastes is conveyed to the inlet of the negative pressure bin 102 by the lifter 101, the hydraulic driving sealing door of the negative pressure bin 102 is opened, and the dumping mechanism of the lifter pushes the garbage can to pour the medical wastes into the negative pressure bin 102. The medical waste is crushed into particles with the particle size less than or equal to 30mm by a crusher 103 below the negative pressure bin 102. The blender 104 blends CaO particles with the particle size less than or equal to 30mm into the material. The mixed material is fed to the inlet of pyrolysis apparatus 20 via screw conveyor 105.

The process comprises the following steps: the air extraction opening above the negative pressure bin 102 is connected with an air supply mechanism 211 through an air extraction pipeline, and polluted air in the bin is sucked into the incineration chamber by the air supply mechanism 211 for high-temperature incineration and sterilization. The inside of the bin is always kept in a negative pressure state, so that polluted air is prevented from leaking out to pollute the environment.

The process comprises the following steps: the adulterant 104 is used for doping CaO particles into the raw materials according to the content of chlorine elements in the raw materials so as to remove HCL gas generated in the reaction process and inhibit the generation of dioxin. The CL/Ca value is from 2 to 4, preferably 3.

(2) Pyrolysis unit 20 receives material from pretreatment unit 10. A vibrator and a stirrer are arranged in the feeding mechanism 201 of the pyrolysis device 20, so that blockage of materials is avoided. The material is evenly distributed into the two pyrolysis reactors 202. The material in the pyrolysis reactor 202 is moved forward by the drive of the helical blades and gradually heated.

The process comprises the following steps: the rotational speed of the pyrolysis reactor 202 is set according to the moisture, combustible fraction and ash composition of the incoming material, and the rotational speed is reduced by increasing the moisture, whereas the rotational speed is increased. Ensure that materials with different components fully react in the reactor.

(3) The materials are indirectly heated by the high-temperature flue gas of the cavity of the external heating furnace 209 in the low-temperature region below 200 ℃ in the pyrolysis reactor 202. The external furnace is a separate component and encloses the pyrolysis reactor. The high-temperature flue gas after combustion in the combustion chamber enters an external heating furnace and is used for heating the pyrolysis reactor. The materials are directly heated by the superheated steam of 500-600 ℃ in the high temperature region of 200-350 ℃ in the pyrolysis reactor 202, and are indirectly heated by the high temperature flue gas of the cavity of the external heating furnace 209. The temperature in the reactor is gradually increased from the front end to the rear end, and the heat source is from an external heating furnace. The material in the pyrolysis reactor 202 gradually increases in temperature during the forward movement and the following reaction occurs:

volatilizing free water in the materials at 100-150 ℃;

The process comprises the following steps: the introduction of superheated steam into pyrolysis reactor 202 may provide efficient and uniform heating of the materials, and the reaction may be completed at about 350 c, thereby greatly reducing the processing time. Compared with the conventional pyrolysis process, the method can save 1/2-3/4 of treatment time.

The process comprises the following steps: the introduction of superheated steam into the pyrolysis reactor 202 ensures an oxygen-free state within the pyrolysis reactor 202, while the superheated steam enhances the effect of CaO to absorb HCL, inhibiting the production of dioxin.

The process comprises the following steps: a steam disturbance mechanism 213 is arranged in the pyrolysis reactor 202, and coking on the cylinder wall is removed by utilizing the principle of thermal expansion and cold contraction under the action of superheated steam; meanwhile, the superheated steam is utilized to assist in heating materials, so that the heat transfer efficiency of the reactor is improved.

The process flow is obtained by the inventor through a plurality of experiments.

(4) The slag extractor 203 receives the high temperature ash products from the pyrolysis reactor 202, cools them and feeds the ash bin 204.

The process comprises the following steps: the slag extractor 203 is provided with a jacket structure in which flowing cooling water is used for cooling high-temperature pyrolysis products, so that the pyrolysis products of the discharge system are at a temperature lower than 60 ℃; the heated cooling water portion enters the steam generating chamber 304. The atomizing nozzle provided in the ash box 204 discharges water mist to prevent ash from producing a large amount of dust.

(5) Most of water vapor generated during the reaction stage of the materials in the pyrolysis reactor 202 at 100-150 ℃ enters the front exhaust chamber 205, most of volatile combustible gas generated when the materials are heated to 200-350 ℃ enters the rear exhaust chamber 206, the flow of the gas is regulated by regulating the pressure of a pipeline through a flow regulator, steam is generated at the front end of the reactor near the front exhaust chamber, and the volatile combustible gas is generated at the rear end of the reactor near the rear exhaust chamber. The gas in the front exhaust chamber 205 enters the steam pipe 207, the gas in the rear exhaust chamber 206 enters the volatile gas pipe 208, and the gas is collected and sent to the heat recovery device 30.

The process comprises the following steps: the lower the water content, the faster the material is heated in the reactor, the closer the volatile combustible gas is generated to the front end of the reactor, and the easier the volatile combustible gas is discharged from the front exhaust chamber. The time of the gas in the pyrolysis reactor is relatively short, which is unfavorable for the decomposition of the organic macromolecules. The opening of a flow regulator a212 arranged on the water vapor pipeline 207 is regulated according to the moisture content of the raw material. The pyrolysis reactor is of a cylindrical structure, and the front end of the pyrolysis reactor is connected with the front exhaust chamber, and the rear end of the pyrolysis reactor is connected with the rear exhaust chamber. The initial reaction of the material is completed at the front end of the pyrolysis reactor, and is close to the front exhaust chamber, and the middle and later reaction is completed at the rear end of the pyrolysis reactor, and is close to the rear exhaust chamber. The gas generated by the initial reaction is mainly steam and is discharged from the front exhaust chamber. The middle reaction generates macromolecular gas, and the macromolecular gas is required to be continuously heated to finish the later reaction so as to be decomposed, and is discharged from a rear exhaust chamber. The lower the water content of the material, the faster the intermediate reaction proceeds, and the closer to the front exhaust chamber, the easier the macromolecule gas which can be generated can enter the front exhaust chamber, resulting in incomplete reaction. The flow regulator a primarily regulates the amount of gas entering the front exhaust plenum in order to minimize the emission of volatile combustible gases from the front exhaust plenum 205. Such that the volatile combustible gas undergoes thorough decomposition during the high temperature phase of the pyrolysis reactor 202. The opening degree of the flow regulator a212 is adjusted as follows:

the water content is less than 10%, and the flow regulator a is closed;

the water content is 10-20%, and the flow regulator a is opened by 50%;

the water content is 20-30%, and the flow regulator a is opened by 80%;

the water content is more than 30%, and the flow regulator a is opened by 100%.

The process flow is obtained by the inventor through a plurality of experiments. The pyrolysis reactor is of a cylindrical structure, and the front end of the pyrolysis reactor is connected with the front exhaust chamber, and the rear end of the pyrolysis reactor is connected with the rear exhaust chamber. The initial reaction of the material is completed at the front end of the pyrolysis reactor, and is close to the front exhaust chamber, and the middle and later reaction is completed at the rear end of the pyrolysis reactor, and is close to the rear exhaust chamber. The gas generated by the initial reaction is mainly steam and is discharged from the front exhaust chamber. The middle reaction generates macromolecular gas, and the macromolecular gas is required to be continuously heated to finish the later reaction so as to be decomposed, and is discharged from a rear exhaust chamber. The lower the water content of the material, the faster the intermediate reaction proceeds, and the closer to the front exhaust chamber, the easier the macromolecule gas which can be generated can enter the front exhaust chamber, resulting in incomplete reaction. The control and adjustment can ensure the sufficient reaction of materials, and is an invention point of the application.

(6) The heat recovery device 30 receives the exhaust gas from the pyrolysis device 20. The exhaust gas is injected into the incineration chamber 303 uniformly along the circumference after entering the gas dispersion chamber 302. The harmful components of the exhaust gas are completely decomposed under the high temperature atmosphere of the incineration chamber. The completely combusted high-temperature flue gas is led into an external heating furnace of the pyrolysis device through a flue gas pipeline b306 to serve as a heat source.

The process comprises the following steps: the gas nozzles in the gas dispersion chamber 302 are arranged along the circumferential tangential direction, and the waste gas enters the incineration chamber through the gas nozzles to form a vortex effect, so that the waste gas is combusted more fully, and harmful components in the waste gas are decomposed more thoroughly.

The process comprises the following steps: the temperature in the incineration chamber 303 is regulated by the burner 301, a high-temperature atmosphere of 850-900 ℃ in the incineration chamber 303 is maintained, and the effective volume of the high-temperature atmosphere ensures that the waste gas stays in the incineration chamber for more than 2S, so that harmful substances in the waste gas are more fully decomposed.

(7) The steam generation chamber 304 of the heat recovery device 30 generates normal pressure saturated steam at 100 c by using the heat energy of the incineration chamber 303. 2/3 of the steam enters the flue gas pipeline a210 through a pipeline, the high-temperature flue gas is rapidly cooled to below 200 ℃, and the generation of harmful substances such as dioxin is inhibited. The remaining 1/3 of the steam enters the superheated steam generator 308 through a pipe and is heated to 500-600 ℃ by the high-temperature flue gas from the incineration chamber 850 ℃. Superheated steam is introduced into pyrolysis reactor 202 through piping to heat the material.

(8) Pyrolysis unit 20 receives high temperature flue gas from heat recovery unit 30 and indirectly heats pyrolysis reactor 202. The external heating furnace is provided with two burners for adjusting the high-temperature atmosphere with the temperature of 400-600 ℃ of the external heating furnace. The high temperature flue gas heated up by the pyrolysis reactor 202 is introduced into the flue gas cleaning device 40.

The process comprises the following steps: the opening of the flow regulator b307 arranged on the flue gas pipeline b306 is regulated according to the temperature of the external heating furnace, and when the temperature of the external heating furnace exceeds the set temperature, the opening of the flow regulator b307 is increased. Excessive flue gas is prevented from entering the external heating furnace, and the excessive flue gas is discharged into the steam superheater.

(9) The flue gas cleaning device 40 receives flue gas from the pyrolysis device 20. An alkali liquor circulating spraying mechanism is arranged in the flue gas washing tower 401, and acid gas and dust are removed from flue gas under the action of alkali liquor. The flue gas enters an activated carbon adsorption box 402, and activated carbon can adsorb heavy metal elements possibly existing in the flue gas. The cleaned flue gas is vented to the atmosphere through stack 403.

4. A steam disturbance mechanism is arranged in the pyrolysis reactor, and coking on the cylinder wall is removed by utilizing the principle of thermal expansion and cold contraction under the action of superheated steam. The temperature at the point where the material is in direct contact with the reactor wall is up to 800 ℃, and the plastic rubber easily adheres to the wall to form hard coking. The temperature of steam after penetrating the material is only 400-500 ℃, the coking on the wall of the contactor can be quickly cooled and coked, and the coked, cooled and crushed can be automatically peeled off. Meanwhile, the superheated steam is used for assisting in heating materials, so that the heat transfer efficiency of the reactor is improved. The system structure is more compact. The equivalent treatment scale and the small occupied area are only 1/4 of the prior art equipment.

It should be understood that the above description is not intended to limit the invention to the particular embodiments disclosed, but to limit the invention to the particular embodiments disclosed, and that various changes, modifications, additions and substitutions can be made without departing from the spirit and scope of the invention.

Claims

1. The waste pyrolysis treatment system is characterized by comprising a pretreatment device, a pyrolysis device, a heat recovery device and a flue gas purification device which are connected in sequence;

the pretreatment device comprises a lifting machine, a negative pressure bin, a pulverizer, a blending machine and a screw conveyor, wherein the negative pressure bin is provided with a hydraulic driving sealing door, an extraction opening and an extraction pipeline are arranged above the negative pressure bin, the pulverizer is arranged below the negative pressure bin, the blending machine is arranged below the pulverizer, the blending machine is connected with the screw conveyor which is obliquely arranged, and a discharge opening of the screw conveyor is connected with a feed inlet of the pyrolysis device;

the pyrolysis device comprises a feeding mechanism, a pyrolysis reactor, a slag extractor, a slag box, a front exhaust chamber, a rear exhaust chamber, a steam pipeline, a volatile gas pipeline, an external heating furnace, a flue gas pipeline a and an air supply mechanism, wherein a certain number of atomizing nozzles are arranged in the slag box, the steam pipeline is connected with the front exhaust chamber, a flow regulator a is arranged on the steam pipeline, the volatile gas pipeline is connected with the rear exhaust chamber, and the air supply mechanism is connected with an air extraction opening above the negative pressure bin through an air extraction pipeline;

the heat recovery device comprises a combustor, a gas dispersion chamber, an incineration chamber, a steam generation chamber, a liquid level adjusting water tank, a flue gas pipeline b and a superheated steam generator, wherein the heat recovery device is connected with an external heating furnace through a pipeline, the gas dispersion chamber is connected with a steam pipeline and a volatile gas pipeline, a gas flow regulator b is arranged on the flue gas pipeline b, and the flue gas pipeline b is connected with the superheated steam generator;

the flue gas purifying device comprises a flue gas washing tower, an activated carbon adsorption box and a chimney;

2. The waste pyrolysis treatment system as claimed in claim 1, wherein the pyrolysis reactor is of a horizontal cylindrical structure, three kinds of spiral blades of different specifications and a steam disturbance mechanism are arranged in the cylinder, the steam disturbance mechanism is composed of an odd number of steam spray pipes arranged along the circumferential direction, and the number of the steam spray pipes increases with the increase of the flow rate or the heat value of the material.

3. A waste pyrolysis treatment system according to claim 2 wherein the steam nozzle is provided with a number of steam nozzles, the number of steam nozzles increasing with increasing reaction temperature.

4. A waste pyrolysis treatment system according to claim 3 wherein the steam nozzles are arranged in a reaction zone at 200 ℃ to 350 ℃ and the steam nozzle distribution density or increase in amplitude increases with increasing reaction temperature.

5. A waste pyrolysis treatment system according to claim 4 wherein the number of gas nozzles increases with increasing material flow or heating value.

6. A waste pyrolysis treatment system as claimed in claim 1 wherein the steam generating chamber is surrounded by a central 3/5 of the incineration chamber and is connected by piping to a superheated steam generator which is connected by piping to the pyrolysis reactor.

7. A method of using a waste pyrolysis treatment system according to claim 1 comprising the steps of:

(1) The garbage bin filled with medical waste is conveyed to the inlet of the negative pressure bin by the lifter, the hydraulic driving sealing door of the negative pressure bin is opened, the dumping mechanism of the lifter pushes the garbage bin to pour the medical waste into the negative pressure bin, the medical waste is crushed into particles with the particle size less than or equal to 30mm by the crusher below the negative pressure bin, caO particles with the particle size less than or equal to 30mm are doped into materials by the doping machine, and the mixed materials are conveyed to the inlet of the pyrolysis device by the screw conveyor;

the process comprises the following steps: the air extraction opening above the negative pressure bin is connected with the air supply mechanism through an air extraction pipeline, polluted air in the bin is sucked into the waste gas incineration chamber by the air supply mechanism to be subjected to high-temperature incineration and sterilization, and the inside of the bin is always kept in a negative pressure state, so that the polluted air is prevented from leaking out to pollute the environment;

the process comprises the following steps: the material doping machine is used for doping CaO particles into the material according to the content of chlorine element in the original material so as to remove HCl gas generated in the reaction process, and simultaneously inhibit the generation of dioxin, wherein the Cl/Ca value is 2-4;

(2) The pyrolysis device receives the materials from the pretreatment device, a vibrator and a stirrer are arranged in a feeding mechanism of the pyrolysis device, the materials are prevented from being blocked, the materials are uniformly distributed into two pyrolysis reactors, and the materials in the pyrolysis reactors move forwards and are gradually heated under the driving of the spiral blades;

the process comprises the following steps: the rotating speed of the pyrolysis reactor is set according to the compositions of water, combustible components and ash content of the materials, so that the materials with different components are ensured to fully react in the reactor;

(3) The materials are indirectly heated by the high-temperature flue gas of the external hot furnace chamber in a low-temperature area below 200 ℃ in the pyrolysis reactor, the materials are directly heated by the superheated steam of 500-600 ℃ in the high-temperature area of 200-350 ℃ in the pyrolysis reactor, and simultaneously are indirectly heated by the high-temperature flue gas of the external hot furnace chamber, the temperature of the materials in the pyrolysis reactor is gradually increased in the forward moving process, and the following reactions occur:

volatilizing free water in the materials at 100-150 ℃;

volatile separation of organic matters in the materials at 200-350 ℃ to obtain a final ash product;

the process comprises the following steps: the superheated steam is led into the pyrolysis reactor to heat the materials efficiently and uniformly, and the reaction can be completed at about 350 ℃, so that the treatment time is greatly shortened, and the treatment time is saved by 1/2-3/4 compared with the conventional pyrolysis process;

the process comprises the following steps: introducing superheated steam into the pyrolysis reactor ensures the anaerobic state in the pyrolysis reactor, and meanwhile, the superheated steam enhances the effect of absorbing HCl by CaO and inhibits the generation of dioxin;

the process comprises the following steps: a steam disturbance mechanism is arranged in the pyrolysis reactor, and coking on the cylinder wall is removed by utilizing the principle of thermal expansion and cold contraction under the action of superheated steam; meanwhile, the superheated steam is utilized to assist in heating materials, so that the heat transfer efficiency of the reactor is improved;

(4) The slag extractor receives the high-temperature ash products from the pyrolysis reactor, cools the high-temperature ash products and sends the cooled high-temperature ash products into an ash box;

the process comprises the following steps: the slag extractor jacket structure is provided with flowing cooling water for cooling high-temperature pyrolysis products, so that the temperature of the pyrolysis products discharged out of the system is lower than 60 ℃; an atomization nozzle arranged in the ash box sprays water mist to prevent ash from generating a large amount of dust;

(5) The most of water vapor generated in the reaction stage of the materials in the pyrolysis reactor at 100-150 ℃ enters a front exhaust chamber, most of volatile combustible gas generated when the materials are heated to 200-350 ℃ enters a rear exhaust chamber, gas in the front exhaust chamber enters a water vapor pipeline, gas in the rear exhaust chamber enters a volatile gas pipeline, and the gas is collected and then sent into a heat recovery device;

the process comprises the following steps: according to the moisture content of the original materials, the opening of a flow regulator a arranged on a water vapor pipeline is regulated, so that the volatile combustible gas discharged from a rear exhaust chamber is reduced as much as possible, and the volatile combustible gas is thoroughly decomposed in a high-temperature stage of a pyrolysis reactor; the opening degree of the flow regulator a is adjusted as follows:

the water content is less than 10%, and the flow regulator a is closed;

the water content is 10-20%, and the flow regulator a is opened by 50%;

the water content is 20-30%, and the flow regulator a is opened by 80%;

the water content is more than 30%, and the flow regulator a is started for 100%;

(6) The heat recovery device receives the waste gas generated by the pyrolysis device, the waste gas enters the gas dispersion chamber and is uniformly sprayed into the incineration chamber along the circumference, harmful components of the waste gas are completely decomposed under the high-temperature atmosphere of the incineration chamber, and the completely combusted high-temperature flue gas is introduced into an external heat furnace of the pyrolysis device through a flue gas pipeline b to serve as a heat source;

the process comprises the following steps: the gas nozzles in the gas dispersion chamber are arranged along the circumferential tangential direction, and the waste gas enters the incineration chamber through the gas nozzles to form a vortex effect, so that the waste gas is combusted more fully, and harmful components in the waste gas are decomposed more thoroughly;

the process comprises the following steps: the temperature in the incineration chamber is regulated by the burner, the high-temperature atmosphere of 850-900 ℃ in the incineration chamber is maintained, and the effective volume of the high-temperature atmosphere ensures that the waste gas stays in the incineration chamber for more than 2S so as to fully decompose harmful substances in the waste gas;

(7) The heat recovery device steam generation chamber generates normal pressure saturated steam at 100 ℃ by utilizing the heat energy of the incineration chamber, 2/3 of the steam enters a flue gas pipeline a through a pipeline, the high-temperature flue gas is rapidly cooled to below 200 ℃ to inhibit the generation of harmful substances such as dioxin, the remaining 1/3 of the steam enters a superheated steam generator through a pipeline, the superheated steam is heated to 500-600 ℃ by the high-temperature flue gas at 850 ℃, and the superheated steam is introduced into a pyrolysis reactor through a pipeline to heat materials;

(8) The pyrolysis device receives high-temperature flue gas from the heat recovery device, indirectly heats the pyrolysis reactor, and the external heat furnace is provided with two burners for adjusting the high-temperature atmosphere with the temperature of 400-600 ℃ of the external heat furnace, and the high-temperature flue gas heated by the pyrolysis reactor is led into the flue gas purification device;

the process comprises the following steps: the opening of a flow regulator b arranged on a flue gas pipeline b is regulated according to the temperature of the external heating furnace, and the opening of the flow regulator b is increased when the temperature of the external heating furnace exceeds the set temperature;

the processes of the process (7) and the process (8) are set, and compared with the traditional pyrolysis system or process, the energy is saved by 30%;

(9) The flue gas purification device receives flue gas from the pyrolysis device, an alkali liquor circulating spraying mechanism is arranged in the flue gas washing tower, acid gas and dust are removed from the flue gas under the action of alkali liquor, the flue gas enters the activated carbon adsorption box, activated carbon can adsorb heavy metal elements possibly existing in the flue gas, and the purified flue gas is discharged into the atmosphere through a chimney.