Method for removing pollutants by high-temperature pyrolysis gasification-low nitrogen combustion coupled with dry electrofiltration of medical waste

Abstract

The invention discloses a method for high-temperature pyrolysis gasification-low-nitrogen combustion coupled dry electrofiltration to remove pollutants from medical waste. The method comprises the following steps: feeding medical waste into a pyrolysis incinerator through a feeder, cracking organic matter in the medical waste into a combustible mixed gas at 850-1600° C. in the absence of oxygen or in the absence of oxygen; the cracked gas enters a secondary combustion chamber and burns under oxygen-rich conditions; the high-temperature flue gas after combustion enters a partition heating chamber of the pyrolysis incinerator through a pipeline; a heat exchanger is connected to the partition heating chamber of the pyrolysis incinerator; the high-temperature tail gas is heat-exchanged with blown oxygen in the heat exchanger; the heated oxygen is passed into the secondary combustion chamber; the tail gas discharged from the heat exchanger enters a venturi mixer, is mixed with alkaline nanoparticles, and then enters a dry reactor and an electrofiltration reactor; the purified gas is led to a chimney by an induced draft fan and discharged into the atmosphere; the organic matter removal rate of the invention reaches 99%, the generation of harmful substances such as dioxins is reduced, and harmless treatment of waste is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of medical waste treatment, and in particular to a method for medical waste high-temperature pyrolysis gasification-low-nitrogen combustion coupled dry-type electric filtration to remove pollutants. Background Art

[0002] Medical waste refers to wastes with direct or indirect infectious, toxic and other harmful properties generated by medical institutions in medical treatment, prevention, health care and other related activities, including infectious, pathological, damaging, pharmaceutical and chemical wastes. These wastes contain a large number of bacterial viruses. If they are not handled properly, they will cause serious pollution to the environment and may also become the source of epidemics. After nearly 20 years of development, incineration disposal technology with rotary kilns and fixed beds as the core and non-incineration treatment technology of medical waste with high-temperature steam, chemistry, microwave, high-temperature dry heat as the core have been widely used. Incineration is basically used for the treatment of medical waste at home and abroad. Although the incineration method can achieve the harmless, reduced and resource-based treatment of garbage at the fastest speed, and has the advantage of occupying less land resources, the waste gas and residues generated by the incineration process have a particularly large impact on the environment, and will also produce a more serious dioxin problem, causing serious secondary pollution to the environment. Additional production lines need to be invested to purify gaseous pollutants, so technical innovation is needed to solve specific problems. Summary of the invention

[0003] In order to overcome the defects of the prior art that medical waste pollutes the environment more and more seriously and cannot achieve harmless, reduced and resource-based treatment of medical waste, the present invention provides a medical waste treatment method, which achieves a high cracking rate by optimizing the structure and parameters of a pyrolysis incinerator, and the entire furnace body is strictly sealed to achieve anaerobic cracking and maximize gas production. Due to the high pyrolysis temperature, the complete incineration process, the high volume reduction of solid particles, and the organic matter removal rate of 99%, the subsequent treatment cost effect is greatly reduced, and the high-temperature flue gas from the secondary combustion chamber is transported to the pyrolysis incinerator as a heat source to maintain the furnace temperature, thereby reducing the use of fuel and reducing costs; the incineration tail gas is recovered by a heat exchanger and then treated by dry reaction and electric filtration technology to meet the emission standards, and will not cause secondary pollution to the environment.

[0004] The method of the invention comprises the following steps: feeding medical waste into a pyrolysis incinerator through a feeder, cracking organic matter in the medical waste into a combustible mixed gas in the absence of oxygen or at 850-1600°C, wherein the pyrolysis incinerator comprises a pyrolysis chamber and a partition heating chamber surrounding the pyrolysis chamber; the cracked gas enters a secondary combustion chamber and burns under oxygen-rich conditions, and the high-temperature flue gas after combustion enters the partition heating chamber of the pyrolysis incinerator through a pipeline; a heat exchanger is connected to a high-temperature tail gas outlet of the partition heating chamber of the pyrolysis incinerator, and the high-temperature tail gas exchanges heat with oxygen blown in by an air compressor in the heat exchanger, and the heated oxygen is passed into the secondary combustion chamber; the tail gas discharged from the heat exchanger enters a venturi mixer, is mixed with alkaline nanoparticles, and then enters a dry reactor to remove sulfide in the tail gas and perform preliminary dust removal, and finally the tail gas enters an electric filter reactor to remove fine dust and pollutants retained in the tail gas, and the purified gas is led to a chimney by an induced draft fan and discharged into the atmosphere.

[0005] An electromagnetic heating coil is arranged on the lower outer wall of the pyrolysis chamber of the pyrolysis incinerator to provide the energy required for starting the pyrolysis. After the high-temperature reaction is started, the circulating flue gas introduced into the partition heating chamber can continuously provide heat for the pyrolysis process. A pyrolysis chamber flue gas outlet is arranged at the upper part of the pyrolysis chamber and is connected with the secondary combustion chamber flue gas inlet of the secondary combustion chamber. An arc igniter is arranged at the secondary combustion chamber flue gas inlet of the secondary combustion chamber. A fuel gas compensation port is arranged at the bottom of the secondary combustion chamber to supplement fuel gas when the flue gas output is reduced to ensure that the flue gas combustion has sufficient temperature. An oxygen inlet is arranged at the lower part of the secondary combustion chamber and the air intake of the oxygen inlet is tangential air intake. A secondary combustion chamber high-temperature flue gas outlet is arranged at the upper part of the secondary combustion chamber.

[0006] The garbage in the pyrolysis incinerator moves from top to bottom by gravity, and forms a drying layer, a pyrolysis layer, and a slag layer from top to bottom in the furnace. The medical garbage is preheated and dried in the pyrolysis incinerator, and pyrolysis and gasification are used to form ash and slag; pyrolysis and gasification are decomposed into combustibles such as carbon monoxide and gaseous hydrocarbons to form a combustible mixed flue gas. The garbage that then enters the pyrolysis incinerator is dried by the rising flue gas from pyrolysis in the upper part of the pyrolysis incinerator, and the moisture therein evaporates. As the temperature continues to rise, the garbage forms ash and slag at the bottom of the furnace. The cracking rate of organic components in the medical garbage reaches more than 99%, and the reduction effect is good. At the same time, the air entrained by the garbage feed and its own humidity are reacted with the water vapor and CO2 generated in the cracking process with the hot carbon layer to form water gas, so that the gas output of the whole process is large.

[0007] The combustible mixed gas generated by the pyrolysis of garbage enters the secondary combustion chamber through the flue gas inlet of the secondary combustion chamber and controls the combustion temperature to be no less than 1100℃, which reduces the generation of dioxins. The tangential and uniform air intake of the oxygen inlet can make the flue gas generate strong turbulence in the secondary combustion chamber and have sufficient residence time. The high-temperature flue gas is introduced into the partition heating chamber of the pyrolysis incinerator through the high-temperature flue gas outlet of the secondary combustion chamber. On the one hand, it provides heat energy for the pyrolysis furnace to achieve the recycling of the added calorific value. On the other hand, it burns the unburned gas in the combustible gas again to further reduce the generation of pollutants.

[0008] The dry reactor is a conventional commercially available reactor, which is used to remove sulfides from tail gas and perform preliminary dust removal.

[0009] The electrofiltration reactor is used to remove fine dust retained in the exhaust gas and various pollutants in the flue gas to meet the prescribed flue gas emission standards and reduce environmental pollution; the reactor is a technology disclosed by the inventor, with specific reference to patents CN201410368552.8, CN202010853319.4, CN201810351642.4, CN201910212368.7, etc.

[0010] The electromagnetic heating device installed on the outer wall of the pyrolysis chamber of the pyrolysis furnace is used to provide the energy supply required for the start of pyrolysis. After the high-temperature reaction is started, the circulating flue gas introduced into the partition heating chamber can continuously provide heat for the pyrolysis section. During the whole process, no additional combustion-supporting substances need to be added to the pyrolysis chamber. The waste is dried, heated, and pyrolyzed in the furnace to achieve the high-temperature pyrolysis and maintain the reaction temperature at 850-1600°C. The pyrolysis furnace can crack macromolecular substances into combustible low-molecular substances such as hydrogen, methane, and carbon monoxide, as well as liquid products such as tar and solvent oil, at high temperatures under oxygen-deficient or oxygen-free conditions, which can greatly reduce Cr, which is more harmful to the human body. 2+ and NO x Gas production, reducing the content of harmful components in the gas.

[0011] Alkaline nanoparticles include sodium bicarbonate, lime powder, calcium hydroxide, etc. The acidic substances in the flue gas undergo a neutralization reaction when passing through this area.

[0012] The beneficial effects of the present invention are:

[0013] 1. The present invention treats medical waste by high-temperature pyrolysis, converts organic matter in the waste into combustible mixed gas, realizes complete cracking of medical waste, has a high combustible gas conversion rate, has the characteristics of high reduction degree and low secondary pollution;

[0014] 2. The present invention uses a high-temperature pyrolysis treatment method, which pyrolyzes and gasifies medical waste in an oxygen-free or oxygen-deficient environment. The dioxin content of the flue gas produced is extremely low, which greatly reduces the generation of harmful gases and achieves harmlessness of the flue gas;

[0015] 3. Use high-temperature pyrolysis technology to treat medical waste, recycle high-temperature flue gas to heat the furnace body, provide heat for the pyrolysis of medical waste, improve the thermal utilization efficiency of the pyrolysis furnace, and reduce energy consumption;

[0016] 4. The auxiliary desulfurization tail gas purification, dry reaction and electric filtration treatment facilities of the present invention can make the medical waste incineration process free of secondary pollutants;

[0017] The technical solution of the present invention is easy to implement, convenient to couple with an intelligent control system, has a low initial investment, and is conducive to market promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process route of the present invention;

[0019] In the figure: 1-feeder; 2-pyrolysis incinerator; 3-secondary combustion chamber; 4-heat exchanger; 5-venturi mixer; 6-dry reactor; 7-electric filter reactor; 8-induced draft fan; 9-chimney; 10-air compressor; 11-oxygen inlet; 12-fuel compensation port; 13-secondary combustion chamber flue gas inlet; 14-arc igniter; 15-secondary combustion chamber high-temperature flue gas outlet; 16-partition heating chamber; 17-electromagnetic heating coil; 18-pyrolysis chamber; 19-pyrolysis chamber flue gas outlet; 20-partition heating chamber high-temperature exhaust gas outlet. DETAILED DESCRIPTION

[0020] The process of the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Figure 1As shown, the device used in the following embodiments includes a feeder 1, a pyrolysis incinerator 2, a secondary combustion chamber 3, a heat exchanger 4, a venturi mixer 5, a dry reactor 6, and an electric filter reactor 7. The feeder 1 is connected to the feed port at the top of the pyrolysis incinerator 2. The pyrolysis incinerator 2 includes a pyrolysis chamber 18 and a partition heating chamber 16 surrounding the outside of the pyrolysis chamber. A pyrolysis chamber flue gas outlet 19 is opened at the top of the pyrolysis incinerator and is connected to the pyrolysis chamber 18. A partition heating chamber high-temperature exhaust gas outlet 20 is opened at the top of the pyrolysis incinerator and is connected to the partition heating chamber 16. An ash outlet is opened at the bottom of the pyrolysis incinerator 2 and is connected to the pyrolysis chamber. An electromagnetic heating coil 17 connected to a power supply is wound on the lower outer wall of the pyrolysis chamber 18. The pyrolysis chamber flue gas outlet 19 is connected to the secondary combustion chamber through a pipeline. 3 is connected to the secondary combustion chamber flue gas inlet 13, the high-temperature exhaust gas outlet 20 of the partition heating chamber is connected to the exhaust gas inlet of the heat exchanger 4 through a pipeline, the exhaust gas outlet of the heat exchanger 4 is connected to the dry reactor 6 through the Venturi mixer 5, the oxygen inlet of the heat exchanger 4 is connected to the air compressor 10, the oxygen outlet of the heat exchanger 4 is connected to the oxygen inlet 11 of the secondary combustion chamber, the air intake of the oxygen inlet 11 is tangential intake, an arc igniter 14 is provided on one side of the secondary combustion chamber flue gas inlet 13 of the secondary combustion chamber and is located in the secondary combustion chamber, a fuel compensation port 12 is provided at the lower part of the secondary combustion chamber, a secondary combustion chamber high-temperature flue gas outlet 15 is opened at the upper part of the secondary combustion chamber, the secondary combustion chamber high-temperature flue gas outlet 15 is connected to the partition heating chamber 16 through a pipeline, and the electric filter reactor 7 is connected to the chimney 9 through the induced draft fan 8;

[0021] Embodiment 1:

[0022] In this embodiment, the above-mentioned device is used to process medical waste. The medical waste is evenly and quantitatively fed into the pyrolysis incinerator 2 through the spiral feeder 1. The waste entering the pyrolysis incinerator 2 moves from top to bottom by gravity. The electromagnetic heating coil 17 is turned on to provide the required heat for the start of pyrolysis. The waste in the pyrolysis chamber 18 is in an anaerobic environment or under anoxic conditions. The temperature is controlled to be not less than 1100°C. As the temperature rises, the organic matter in the waste is decomposed to form a combustible mixed flue gas. The combustible mixed gas is discharged through the pyrolysis chamber flue gas outlet 19 and enters the secondary combustion chamber 3 through the secondary combustion chamber flue gas inlet 13 for combustion. The temperature is also controlled to be not less than 1100°C. The high-temperature flue gas after combustion The gas is transported to the partition heating chamber 16 through the high-temperature flue gas outlet 15 of the secondary combustion chamber to provide heat for the pyrolysis process. The recycled high-temperature tail gas is discharged from the high-temperature tail gas outlet 20 of the partition heating chamber and enters the heat exchanger 4 for waste heat recovery. After the high-temperature tail gas exchanges heat with oxygen, the heated oxygen is introduced into the secondary combustion chamber 3 through the oxygen inlet 11. After the heat exchange, the tail gas enters the venturi mixer 5 to add sodium bicarbonate, and then enters the dry reactor 6. The acidic substances in the flue gas react with the sodium bicarbonate and enter the electric filter reactor 7 after preliminary dust removal to remove the fine dust retained in the tail gas and various pollutants in the flue gas; after purification, the induced draft fan 8 leads it to the chimney 9 and discharges it into the atmosphere;

[0023] In this embodiment, medical waste is dried, heated, pyrolyzed and gasified from top to bottom in the pyrolysis incinerator 2. In the pyrolysis incinerator, the waste passes through the drying layer, pyrolysis layer and slag layer in sequence, that is, the incoming waste is dried by the flue gas rising from the pyrolysis layer, the moisture therein is volatilized, and then pyrolyzed and gasified to decompose into combustibles such as carbon monoxide and gaseous hydrocarbons to form a combustible mixed flue gas. As the temperature continues to rise, the waste forms ash and slag at the bottom of the furnace; at the same time, the air entrained by the waste feed and its own humidity are reacted with the water vapor and CO2 generated in the cracking process with the hot carbon layer to generate water gas, so that the gas production of the whole process is large.

[0024] In this embodiment, the oxygen inlet 11 of the secondary combustion chamber 3 supplies oxygen tangentially and evenly, which can make the flue gas generate strong turbulence in the secondary combustion chamber 3 and have sufficient residence time to effectively remove dioxins; the fuel compensation port 12 supplements fuel gas when the flue gas output decreases to ensure that the flue gas combustion has sufficient temperature.

[0025] After the above process treatment, the volume of the waste residue produced is 5% of the total volume of the medical waste before the reaction, and the volume reduction rate of the medical waste reaches 95%.

[0026] The high-temperature pyrolysis incinerator consists of a pyrolysis chamber in the middle and a partition heating chamber surrounding the outside. The induced draft fan is set at the last section of the equipment. The various systems are connected by pipelines. The induced draft fan draws air at the rear end so that the flue gas passes through each unit from front to back. The inner chamber is heated and cracked by electromagnetic heating and self-heating of the combustible mixed gas combustion (the heating temperature is between 850-1600℃). The garbage is cracked during the heating process to produce a combustible mixed gas, which is introduced into the secondary combustion chamber for high-temperature combustion (the combustion temperature is not less than 1100℃). The secondary combustion chamber is equipped with an air guide system to evenly supplement oxygen and has sufficient volume, so that the combustible gas can be vortex-burned in the secondary combustion chamber, thereby increasing the residence time of the flue gas, which is greater than 2 seconds. Alkaline nanoparticles are added to the exhaust gas purification section by a venturi mixer. The component is mixed into the reactor and reacts with the acidic components in the flue gas to remove the acid gas at a higher temperature. The exhaust gas does not need to be further cooled. The electric filtration purifies multiple pollutants to ensure that there will be no secondary pollution to the environment.

[0027] The main component of medical waste is organic matter. The pyrolysis of medical waste produces combustible gas with self-heating calorific value, which not only realizes the harmless treatment of medical waste, but also greatly improves the cracking rate due to the optimization of the cracking and incineration design. At the same time, the air entrained by the waste feed and its own humidity in the cracking process will react with the water vapor and CO2 produced by the hot carbon layer to generate water gas, so as to maximize the gas production of medical waste pyrolysis gasification. The tail gas generated by the incineration of medical waste is discharged after desulfurization, dust removal and electric filtration to remove multiple pollutants. There is no secondary pollutant in the entire treatment process that causes new pollution to the environment.

[0028] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for removing pollutants by high-temperature pyrolysis and gasification of medical waste and low-nitrogen combustion coupled with dry electrofiltration, characterized in that: Medical waste is fed into a pyrolysis incinerator through a feeder, and organic matter in the medical waste is cracked into a combustible mixed gas at 850-1600°C in the absence of oxygen or in the absence of oxygen, wherein the pyrolysis incinerator includes a pyrolysis chamber and a partition heating chamber surrounding the pyrolysis chamber; the cracked gas enters the secondary combustion chamber and burns under oxygen-rich conditions, and the high-temperature flue gas after combustion enters the partition heating chamber of the pyrolysis incinerator through a pipeline, and a heat exchanger is connected to the high-temperature tail gas outlet of the partition heating chamber of the pyrolysis incinerator, and the high-temperature tail gas exchanges heat with oxygen blown in by an air compressor in the heat exchanger, and the heated oxygen is passed into the secondary combustion chamber; the tail gas discharged from the heat exchanger enters a venturi mixer, is mixed with alkaline nanoparticles, and then enters a dry reactor to remove sulfides and preliminary dust removal in the tail gas, and finally the tail gas enters an electrofiltration reactor to remove fine dust and pollutants retained in the tail gas, and the purified gas is led to a chimney by an induced draft fan and discharged into the atmosphere; An electromagnetic heating device is arranged on the lower outer wall of the pyrolysis chamber of the pyrolysis incinerator, a pyrolysis chamber smoke outlet is arranged on the upper part of the pyrolysis chamber and is connected to the smoke inlet of the secondary combustion chamber, an arc igniter is arranged at the smoke inlet of the secondary combustion chamber, a fuel compensation port is arranged at the bottom of the secondary combustion chamber, which is used to supplement fuel when the smoke output is reduced to ensure that the smoke combustion has sufficient temperature, an oxygen inlet is arranged at the lower part of the secondary combustion chamber and the air intake of the oxygen inlet is tangential air intake, and a secondary combustion chamber high-temperature smoke outlet is arranged at the upper part of the secondary combustion chamber; Alkaline nanoparticles include sodium bicarbonate, lime powder, and calcium hydroxide; The combustion temperature in the secondary combustion chamber is not less than 1100°C.

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