A short-process method for treating medical waste by in-situ pyrolysis and incineration coupled with electrocatalytic combustion

Abstract

The invention discloses a short-process method for treating medical waste by in-situ pyrolysis and incineration coupled with electrocatalytic combustion. The method comprises the following steps: the medical waste is pre-treated and crushed, and then is fed into a pyrolysis incinerator with high-frequency power supply heating by a spiral feeder, and the medical waste is sequentially passed through an incineration section, a pyrolysis section and a catalytic combustion section from bottom to top for pyrolysis and incineration, and the generated waste residue is discharged from the bottom of the pyrolysis incinerator; the combustible gas, hydrocarbon substances and the like generated in the incineration section enter the catalytic combustion section, and are fully burned and catalytically decompose tar and toxic substances under the action of an electrocatalytic filter; the flue gas temperature is then reduced to 500-550°C by a flue gas heat exchanger, and after heat exchange, the flue gas enters a venturi ejector and is mixed with alkali liquid, so that the flue gas is rapidly cooled to 150-300°C and acidic gas is removed, and then the flue gas is passed through an electrostatic precipitator to remove more than 99% of dust before reaching the emission standard, thereby realizing the short-process treatment of pyrolysis and incineration of medical waste.

Description

Technical Field

[0001] The present invention relates to the field of medical waste treatment, and in particular to a short-process method for treating medical waste by in-situ pyrolysis and incineration coupled with electrocatalytic combustion. Background Art

[0002] With the progress of the times and the development of society, the scientific management and safe disposal of medical waste occupies a pivotal position. According to my country's "Medical Waste Management Regulations", medical waste refers to waste with direct or indirect infectious, toxic and other harmful properties generated by medical and health institutions in medical, preventive, health care and other related activities. Medical waste contains a large number of pathogenic microorganisms, viruses and sharp objects, such as broken glass, discarded syringes, disposable scalpels, etc., which are mainly transmitted through the damaged skin, inner membranes of the five senses, respiratory system and digestive system of the human body. Once the human body is accidentally exposed, it may cause infection or injury. At the same time, improper disposal of medical waste will pollute water bodies and the atmosphere in many ways. For example, during the stacking process of medical waste, the volatile matter is easily decomposed under the promotion of temperature and moisture, releasing carbon oxides, nitrogen oxides and sulfur-containing gases, which seriously pollute the environment; at the same time, persistent organic pollutants such as dioxins and polycyclic aromatic hydrocarbons generated during the incineration of medical waste will cause great pollution to the atmosphere. Dioxins are typical persistent organic pollutants with stable properties, resistant to acid, alkali, photochemical degradation and hydrolysis. They can not only exist in the environment for a long time, but also migrate long distances with the atmosphere. When dioxins are released into the environment from emission sources, they will be enriched in animals and plants and transmitted to the human body through food intake and other means, posing a major threat to human health.

[0003] Nowadays, medical waste treatment methods can be divided into chemical disinfection, microwave treatment, high-pressure steam sterilization, plasma disinfection, pyrolysis incineration, etc. according to the treatment process. Among them, pyrolysis incineration has developed the fastest. Through continuous improvement, it has become an internationally recognized medical waste treatment method. The United States, Japan and the United Kingdom mainly use incineration. In my country, the main treatment technology for medical waste is pyrolysis incineration. In the 1970s and 1980s, medical waste incineration equipment was relatively backward, with high costs, low treatment effects and high risks to human health. The application of incineration was greatly limited. In the 21st century, on the basis of introducing foreign incineration disposal technology, my country has increased its investment in the research and development of medical waste incineration technology and equipment, further narrowing the gap with foreign technology, and the automation, purification efficiency and incineration performance of incineration equipment have been greatly improved.

[0004] The flue gas produced by the pyrolysis of medical waste incineration contains a certain amount of dust, toxic gases (carbon monoxide, nitrogen oxides, sulfur dioxide, hydrogen chloride, etc.), dioxins and heavy metals such as mercury, cadmium, and lead, which must be purified. The advantage of using pyrolysis incineration technology for medical waste incineration is that it can effectively reduce the hazardous waste fly ash in the incinerator, control the pollution of heavy metals and dioxin-like organic matter in the flyback, and control the thermal NO in the waste. x The production of. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a short-process method for treating medical waste by in-situ pyrolysis and incineration coupled with electrocatalytic combustion. The method is that the medical waste is crushed and then fed into a pyrolysis incinerator by a screw feeder. The inner cavity of the pyrolysis incinerator is composed of an incineration section, a pyrolysis gasification section and a catalytic combustion section from bottom to top. The pyrolysis incinerator is heated by electromagnetic synergy. Preheated air is introduced during the incineration process. As the intensity of electromagnetic heating increases, the medical waste is ignited and incinerated by an igniter arranged in the incineration section of the pyrolysis incinerator. The dust, acidic gas and dioxin-like substances generated by the incineration rise to the pyrolysis gasification section. The pyrolysis gasification decomposes the macromolecular organic matter into combustible gas. Gas, hydrocarbons, liquid fuels, coke, combustible gases and gasified liquids rise into the catalytic combustion section, preheated air is introduced into the catalytic combustion section, an electrocatalytic filter connected to a power source is arranged in the catalytic combustion section, combustible gases, liquids, ash and inert substances are further burned in the catalytic combustion section under the action of the electrocatalytic filter, and at the same time, the catalyst on the electrocatalytic filter preliminarily adsorbs volatile organic compounds, chlorides, nitrogen oxides and carbon dioxide in the combustion flue gas; the flue gas after pyrolysis and incineration enters the flue gas heat exchanger, where the flue gas temperature drops to 500-550°C, after heat exchange, the flue gas enters the venturi ejector and mixes with alkali solution, the flue gas is rapidly cooled to 150-300°C and acidic gases are absorbed by alkali solution, the mixture is separated into gas and liquid in the separator, the slurry after absorption is collected in the sewage storage tank, and the sewage is discharged after being treated with alkali and sedimentation to meet the standards; the flue gas after alkali solution treatment is discharged after dust removal by an electric filter dust collector.

[0006] The furnace body wall of the pyrolysis incinerator has two interlayers, an outer interlayer is provided with an electric heating wire, the electric heating wire is connected to a high-frequency power supply, and the temperature in the pyrolysis incinerator after heating is 900-1300°C, an electromagnetic coil connected to a power supply is provided outside the furnace body of the incineration section of the pyrolysis incinerator, the temperature of the incineration section is above 1100°C, an air duct is provided in the inner interlayer, the air duct is connected to an air inlet I and an air inlet II in the incineration section and the catalytic combustion section respectively, and an electrocatalytic filter connected to a power supply is provided in the catalytic combustion section of the pyrolysis incinerator.

[0007] The electrocatalytic filter is based on a perforated metal plate or a perforated high-temperature conductive ceramic, wherein the metal plate has holes selected from the group consisting of stainless steel, tungsten alloy, tungsten-molybdenum alloy, nickel-based ultra-high-temperature alloy, and titanium-based ultra-high-temperature alloy. The catalyst is loaded thereon, and the catalyst is selected from the group consisting of V2O5, CeO, NiO, Mn3O4, MnO2 / Al2O3, and Pd / Al2O3. The electrocatalytic filter is connected to a high-voltage AC power source and is powered by it.

[0008] The exhaust fan is connected to the flue gas heat exchanger through a flow meter. The air after heat exchange with the incineration flue gas is passed into the air duct of the inner layer of the pyrolysis incinerator for preheating again. The preheated air provides oxygen for the full combustion of medical waste, while preventing cold air from lowering the pyrolysis incineration temperature.

[0009] The electrocatalytic filter is arranged in the catalytic combustion section of the incineration pyrolysis furnace, generates plasma and free radicals under the action of high temperature and electricity, and adsorbs and decomposes aromatic compounds, tar and toxic substances generated by the incineration of medical waste.

[0010] The electromagnetic coil provides a magnetic field strength of 0.05 ~ 0.1T, and the high-frequency power supply is 380V / 50Hz ~ 80Hz.

[0011] The screw feeder delivers the pre-treated and crushed medical waste into the pyrolysis incinerator 2 at a processing capacity of 5kg / min to 8.5kg / min. The excess air coefficient in the furnace is 1.0 to 2.0, and the air flow rate is 3L / min to 7L / min.

[0012] The method of the present invention has the following beneficial effects:

[0013] 1. This method uses electromagnetic enhanced heating to make the three incineration sections in the pyrolysis incinerator work synergistically to achieve complete pyrolysis and incineration of medical waste. Compared with traditional industrial medical waste pyrolysis and incineration, it reduces a large amount of acidic and harmful gases and smoke, and has the advantages of small footprint and energy saving and emission reduction.

[0014] 2. The catalytic combustion section in the pyrolysis incinerator of this method is equipped with an electrocatalytic filter. Under the combined action of high temperature, electricity and active components of the catalyst, a large amount of plasma and free radicals will be generated, which will degrade volatile organic compounds, tar and toxic substances in the combustion flue gas, reduce the burden of subsequent flue gas purification processes, and provide the possibility for short-process treatment of medical waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process of the present invention;

[0016] Figure 2 It is a schematic diagram of the internal structure of the pyrolysis incinerator 2 in the method of the present invention;

[0017] In the figure: 1-screw feeder; 2-pyrolysis incinerator; 3-flue gas heat exchanger; 4-Venturi ejector; 5-separator; 6-wastewater storage tank; 7-electrostatic precipitator; 8-flow meter; 9-exhaust fan; 10-electrocatalytic filter; 11-air inlet I; 12-electric heating wire; 13-air inlet II; 14-electromagnetic coil; 15-slag discharge port; 16-pump; 17-alkali solution pool. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below: This embodiment is implemented on the premise of the technical solution of the present invention, but the present application is not limited to the precise structure described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The following is a detailed implementation method, and the protection scope of the present invention is not limited to the following embodiments; the components not specifically described in the embodiments are all conventional commercially available components, and are controlled and used according to conventional methods;

[0019] The device used in the following embodiments includes a screw feeder 1, a pyrolysis incinerator 2, a flue gas heat exchanger 3, a venturi ejector 4, a separator 5, a sewage storage tank 6, and an electric filter dust collector 7, wherein the furnace body wall of the pyrolysis incinerator 2 has two interlayers, an electric heating wire 12 is arranged in the outer interlayer, and the electric heating wire is connected to a high-frequency power supply. An electromagnetic coil 14 connected to the power supply is arranged outside the furnace body of the incineration section of the pyrolysis incinerator. The temperature of the incineration section is above 1100°C, and an air duct is arranged in the inner interlayer. The air duct is respectively connected to the air inlet Ⅰ11 and the air inlet Ⅱ13 in the incineration section and the catalytic combustion section. The catalytic combustion section of the pyrolysis incinerator is connected, and an electrocatalytic filter 10 is provided in the catalytic combustion section of the pyrolysis incinerator, and a slag discharge port 15 is provided at the bottom of the furnace body; the spiral feeder is connected to the pyrolysis incinerator 2, the flue gas outlet of the pyrolysis incinerator 2 is connected to the flue gas heat exchanger 3, the exhaust fan 9 is connected to the flue gas heat exchanger 3 through a flow meter 8, the flue gas heat exchanger 3 is connected to the air duct in the inner interlayer of the pyrolysis incinerator, the flue gas heat exchanger 3 is connected to the separator 5 through a venturi ejector 4, the lower end of the separator 5 is connected to a sewage storage tank 6, and the upper end is connected to an electric filter dust collector 7, and the alkali liquid pool 17 is connected to the venturi ejector through a pump 16;

[0020] Example 1: Figure 1 , 2 As shown, the crushed medical waste is fed into the pyrolysis incinerator 2 by the screw feeder 1 at a feed rate of 5kg / min, the electric heating wire 12 of the pyrolysis incinerator 2 is connected to a high-frequency power supply of 380V / 50Hz, and the temperature in the pyrolysis incinerator is 1000°C after heating. An electromagnetic coil 14 connected to the power supply is arranged outside the furnace body of the incineration section of the pyrolysis incinerator, and the electromagnetic coil 14 is powered by a 40Hz, 220V DC power supply. The magnetic drive is adjusted to 0.05T so that the temperature of the incineration section is controlled at 1100°C;

[0021] The exhaust fan 9 introduces air with an excess air coefficient of 1.0 into the flue gas heat exchanger 3 through the flow meter 8 at an air flow rate of 7L / min. After the air exchanges heat with the incineration flue gas, it is introduced into the air channel of the inner layer of the pyrolysis incinerator 2 for preheating again, and is used to provide preheated air to the incineration section and catalytic combustion section in the pyrolysis incinerator; the medical waste is ignited and incinerated by the igniter arranged in the incineration section of the pyrolysis incinerator, and the dust, acidic gas, and dioxin substances generated by the incineration rise to the pyrolysis gasification section. The pyrolysis gasification decomposes the macromolecular organic matter into combustible gas, hydrocarbon substance, liquid fuel, and coke. The combustible gas and gasified liquid rise into the catalytic combustion section, and the preheated air is introduced into the catalytic combustion section. An electrocatalytic filter 9 connected to a power supply is arranged in the catalytic combustion section. The electrocatalytic filter 10 is based on a porous tungsten-molybdenum alloy, and a V2O5 active catalyst is loaded on the substrate. The electrocatalytic filter 10 is connected to a voltage of 20kV and a frequency of 10 kHz alternating current, combustible gas, liquid, ash and inert substances are further burned in the catalytic combustion section under the action of the electrocatalytic filter, and at the same time, the catalyst on the electrocatalytic filter 10 preliminarily adsorbs volatile organic compounds, chlorides, nitrogen oxides and carbon dioxide in the combustion flue gas; the flue gas after combustion is cooled to 550°C by the flue gas heat exchanger 3, and then enters the venturi ejector to mix with the 3% NaOH solution drawn from the alkali liquid pool 17, the flue gas is rapidly cooled to 250°C and absorbs acidic gases through the alkali liquid, the mixture is separated into gas and liquid in the separator 5, and the slurry after separation flows into the sewage storage tank 6, the flue gas goes upward into the electric filter precipitator 7, the flue gas at the outlet of the electric filter precipitator 7 is tested, and the concentrations of various pollutants in the flue gas are lower than the emission standards, the flue gas dust removal rate reaches 99.4%, and the medical waste reduction rate reaches 95.2%.

[0022] Embodiment 2: The medical waste after pretreatment and crushing is fed into the pyrolysis incinerator 2 by the screw feeder 1 at a feed rate of 6kg / min. The electric heating wire 12 of the pyrolysis incinerator 2 is connected to a high-frequency power supply of 380V / 60Hz. After heating, the temperature of the pyrolysis incinerator 2 is 1100°C. The electromagnetic coil outside the furnace body of the incineration section of the pyrolysis incinerator is powered by a 40Hz, 220V DC power supply. The magnetic drive is adjusted to 0.05T so that the temperature of the incineration section is controlled at 1200°C; The fan 9 passes air with an excess air coefficient of 1.2 into the flue gas heat exchanger 3 through the flow meter 8 at an air flow rate of 6L / min. After the air exchanges heat with the incineration flue gas, it is passed into the air channel of the interlayer of the pyrolysis incinerator 2 for preheating again, and is used to provide preheated air to the incineration section and catalytic combustion section in the pyrolysis incinerator; the electrocatalytic filter 10 is based on a porous high-temperature conductive ceramic substrate, on which a Mn3O4 catalyst is loaded, and the access voltage is 50kV and the frequency is 10 kHz alternating current, the medical waste passes through the incineration section, pyrolysis section and catalytic combustion section in the furnace in turn for full pyrolysis and incineration; the flue gas after combustion is cooled to 520°C by the flue gas heat exchanger 3, and then enters the venturi ejector 4 to mix with the 10% magnesium oxide slurry drawn from the alkali liquid pool 17, the flue gas is rapidly cooled to 280°C and absorbs the acidic gas through the alkali liquid, the mixture is separated into gas and liquid in the separator 5, the slurry after separation flows into the sewage storage tank 6, the flue gas goes up into the electric filter precipitator 7, the flue gas at the outlet of the electric filter precipitator 7 is tested, the concentration of each pollutant in the flue gas is lower than the emission standard, the flue gas dust removal rate reaches 99.6%, and the medical waste reduction rate reaches 96%.

[0023] Embodiment 3: The medical waste after pretreatment and crushing is fed into the pyrolysis incinerator 2 by the spiral feeder 1 at a feed rate of 5kg / min. The electric heating wire 12 of the pyrolysis incinerator 2 is connected to a high-frequency power supply of 380V / 80Hz. After heating, the temperature of the pyrolysis incinerator 2 is 1000°C. The electromagnetic coil outside the furnace body of the incineration section of the pyrolysis incinerator is powered by a 40Hz, 220V DC power supply. The magnetic drive is adjusted to 0.1T so that the temperature of the incineration section is controlled at 1200°C; the exhaust fan 9 passes air with an excess air coefficient of 1.8 into the flue gas heat exchanger 3 through the flow meter 8 at an air flow rate of 5L / min. After the air exchanges heat with the incineration flue gas, it is passed into the air channel of the inner layer of the pyrolysis incinerator 2 for preheating again, and is used to provide preheated air to the incineration section and the catalytic combustion section in the pyrolysis incinerator; the electrocatalytic filter 10 electricity is based on a perforated stainless steel plate with a Pd / Al2O3 catalyst loaded on the base. It is connected to an alternating current with a voltage of 40kV and a frequency of 20kHz. The medical waste is fully pyrolyzed and incinerated in the furnace through the incineration section, the pyrolysis section and the catalytic combustion section in sequence. The flue gas after combustion is cooled to 530°C through the flue gas heat exchanger 3, and then enters the venturi ejector 4 to mix with the 5% mass concentration sodium hydroxide solution drawn from the alkali liquid pool 17. The flue gas is rapidly cooled to 250°C and the acid gas is absorbed by the alkali liquid. The mixture is separated into gas and liquid in the separator 5. After separation, the slurry flows into the sewage storage tank 6, and the flue gas enters the electric filter precipitator 7 upward. The flue gas at the outlet of the electric filter precipitator 7 is tested. The concentrations of various pollutants in the flue gas are lower than the emission standards, the flue gas dust removal rate is 99.1%, and the medical waste reduction rate is 96.6%.

[0024] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A short process for treating medical waste by in-situ pyrolysis and incineration coupled with electrocatalytic combustion, characterized in that: After being crushed, the medical waste is fed into a pyrolysis incinerator (2) by a screw feeder (1). The inner cavity of the pyrolysis incinerator (2) is composed of an incineration section, a pyrolysis gasification section and a catalytic combustion section from bottom to top. The pyrolysis incinerator (2) is heated by electromagnetic synergy. During the incineration process, preheated air is introduced. As the intensity of electromagnetic heating increases, the medical waste is ignited and incinerated by an igniter arranged in the incineration section of the pyrolysis incinerator. The dust, acidic gas and dioxin substances generated by the incineration rise to the pyrolysis gasification section. The pyrolysis gasification decomposes the macromolecular organic matter into combustible gas, hydrocarbon substances, liquid fuel, coke, combustible gas and gasified liquid. The body rises and enters the catalytic combustion section, where preheated air is introduced. The catalytic combustion section is provided with an electrocatalytic filter (10) connected to a power source. Under the action of the electrocatalytic filter, combustible gas, liquid, ash and inert substances are further burned in the catalytic combustion section. At the same time, the catalyst on the electrocatalytic filter preliminarily adsorbs volatile organic matter, chloride, nitrogen oxides and carbon dioxide in the combustion flue gas. The flue gas after pyrolysis and incineration enters the flue gas heat exchanger (3), where the flue gas temperature is reduced to 500-550°C. After heat exchange, the flue gas enters the venturi ejector and is mixed with alkali solution. The flue gas is rapidly cooled to 150-300°C and the acid gas is absorbed by the alkali solution. The mixture is separated into gas and liquid in the separator (5). The slurry after absorption is collected in the sewage storage tank (6). The sewage is discharged after being treated with alkali and sedimentation and meets the standards. The flue gas after alkali solution treatment is discharged after dust removal by the electric filter dust collector. The furnace body wall of the pyrolysis incinerator (2) has two interlayers, an electric heating wire is arranged in the outer interlayer, and the electric heating wire is connected to a high-frequency power supply. After heating, the temperature in the pyrolysis incinerator is 900-1300°C. An electromagnetic coil connected to the power supply is arranged outside the furnace body of the incineration section of the pyrolysis incinerator. The temperature of the incineration section is above 1100°C. An air duct is arranged in the inner interlayer. The air duct is connected to the air inlet I (11) and the air inlet II (13) in the incineration section and the catalytic combustion section respectively. An electrocatalytic filter connected to the power supply is arranged in the catalytic combustion section of the pyrolysis incinerator. A slag discharge port is arranged at the bottom of the furnace body; The electrocatalytic filter is based on a perforated metal plate or a perforated high-temperature conductive ceramic, wherein the metal plate has holes selected from the group consisting of stainless steel, tungsten alloy, tungsten-molybdenum alloy, nickel-based ultra-high temperature alloy, and titanium-based ultra-high temperature alloy. The catalyst is loaded on the metal plate, wherein the catalyst is selected from the group consisting of V2O5, CeO, NiO, Mn3O4, MnO2 / Al2O3, and Pd / Al2O3. The electrocatalytic filter is connected to a high-voltage AC power source and powered by it.

2. The short-process method for treating medical waste by in-situ pyrolysis and incineration coupled with electrocatalytic combustion according to claim 1 is characterized in that: The alkali solution is one of NaOH solution, Na2CO3 solution, limestone slurry and magnesium oxide slurry.

3. The short-process method for treating medical waste by in-situ pyrolysis and incineration coupled with electrocatalytic combustion according to claim 1 is characterized in that: The exhaust fan (9) is connected to the flue gas heat exchanger (3) via a flow meter (8). The air after heat exchange with the incineration flue gas is passed into the air duct of the inner layer of the pyrolysis incinerator and preheated again before being used to supply oxygen to the pyrolysis incinerator.

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