A domestic waste incineration treatment method and system with adjustable combustion atmosphere

Abstract

This invention provides a method and system for treating municipal solid waste with an adjustable combustion atmosphere, belonging to the field of municipal solid waste treatment technology. The invention dries the municipal solid waste; the moisture in the waste is heated to generate waste steam. This waste steam drives out air from the gaps within the waste, thereby removing nitrogen from these gaps and increasing the purity of carbon dioxide in the mixed flue gas obtained from waste combustion, eliminating the need for subsequent carbon dioxide capture processes. Furthermore, this invention fully utilizes oxygen, a byproduct of the electrolytic production of green hydrogen, which is mixed with carbon dioxide from waste combustion as the incineration atmosphere. This process does not introduce nitrogen, and the high volumetric carbon dioxide content in the mixed flue gas eliminates the need for carbon dioxide capture, reducing the cost of green methanol synthesis by approximately 20% or more. Simultaneously, this invention recycles and incinerates the remaining carbon dioxide to control the incineration atmosphere and maintain the combustion temperature, significantly reducing NO₂ levels. x Original concentration of the product.

Description

Technical Field

[0001] This invention belongs to the field of municipal solid waste treatment technology, specifically relating to a method and system for municipal solid waste incineration with an adjustable combustion atmosphere. Background Technology

[0002] Green methanol is a low-carbon methanol produced from renewable energy or biomass, with significantly lower carbon emissions throughout its life cycle compared to traditional methanol. Green methanol differs from blue, gray, and black (or brown) methanol due to its different raw materials and production methods. It is produced by electrolyzing water with green electricity generated from renewable energy sources (such as solar and wind power) to produce green hydrogen, which is then converted into green methanol using renewable carbon dioxide (biomass-derived carbon dioxide or carbon dioxide captured directly from the air). Additionally, methanol produced from biogas produced by fermenting agricultural and forestry waste, livestock manure, and other biomass is also considered green methanol.

[0003] The preparation of green methanol mainly includes three technical routes: carbon dioxide hydrogenation to methanol, biomass to methanol, and coal chemical coupled with green hydrogen to methanol. Among them, carbon dioxide hydrogenation to methanol includes steps such as carbon dioxide capture, compression, purification, hydrogenation conversion, and methanol synthesis. For example, an existing technology uses flue gas from waste incineration to capture carbon dioxide and then synthesize methanol with green hydrogen. Since the carbon dioxide content in the flue gas is only 8-10%, the cost of carbon dioxide capture is relatively high, accounting for about 30% of the total cost of green methanol synthesis, which is a drawback due to its high cost. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for treating municipal solid waste with an adjustable combustion atmosphere. This invention utilizes oxygen, a byproduct of the electrolytic production of green hydrogen, to mix with carbon dioxide from the combustion of municipal solid waste as the incineration atmosphere. This eliminates the need for carbon dioxide capture to prepare green methanol, significantly reducing the synthesis cost of green methanol.

[0005] To achieve the objectives of this invention, the following technical solutions are provided: A method for treating municipal solid waste with adjustable combustion atmosphere includes the following steps: S1. The household waste is dried and vented to obtain dried waste; the drying temperature is 120~150℃; the N2 content in the dried waste is less than 5%; S3. The dried waste is incinerated in a mixed atmosphere of oxygen and circulating carbon dioxide to obtain mixed flue gas; the volume fraction of carbon dioxide in the mixed flue gas is >90%; the oxygen is produced by electrolysis of water. S4. The mixed flue gas is purified to obtain carbon dioxide; a portion of the obtained carbon dioxide is mixed with hydrogen and subjected to a hydrogenation reaction to obtain green methanol; the hydrogen is produced by electrolysis of water. The remaining carbon dioxide in step S4 is the recycled carbon dioxide from step S3.

[0006] Preferably, the drying in step S1 is performed by heating and drying with the steam generated after incineration in step S3.

[0007] Preferably, the drying in step S1 is performed using the residual heat from the remaining carbon dioxide obtained in step S4.

[0008] Preferably, the drying and heat preservation time in step S1 is ≥0.5h.

[0009] Preferably, the volume concentration of oxygen in the oxygen and circulating carbon dioxide mixed atmosphere in step S3 is 15-30%.

[0010] Preferably, the incineration temperature in step S3 is 900~1000℃.

[0011] Preferably, in step S4, the volume ratio of some carbon dioxide to the remaining carbon dioxide is 1~2:2~6.

[0012] Preferably, the flue gas purification in step S4 includes sequential selective non-catalytic reduction, dry deacidification, bag filter dust collection, and wet deacidification.

[0013] The present invention also provides a system for preparing green methanol by incinerating municipal solid waste with adjustable combustion atmosphere, including a waste drying unit, a waste gas treatment unit, a waste incineration unit, a flue gas purification unit, a flow controller, a methanol synthesis unit, and an electrolysis hydrogen production unit.

[0014] This invention provides a method for treating municipal solid waste with an adjustable combustion atmosphere through incineration, comprising the following steps: S1, drying and venting the municipal solid waste to obtain dried waste; the drying temperature is 120-150℃; the N2 content in the dried waste is less than 5%; S3, incinerating the dried waste in a mixed atmosphere of oxygen and recycled carbon dioxide to obtain mixed flue gas; the volume fraction of carbon dioxide in the mixed flue gas is >90%; the oxygen is generated from water electrolysis; S4, purifying the mixed flue gas to obtain carbon dioxide; mixing a portion of the obtained carbon dioxide with hydrogen for a hydrogenation reaction to obtain green methanol; the hydrogen is generated from water electrolysis; the remaining carbon dioxide in step S4 is recycled carbon dioxide from step S3. This invention dries the municipal solid waste, and the moisture in the waste is heated to generate waste steam. The waste steam drives out the air in the gaps inside the waste, thereby removing nitrogen from these gaps and improving the purity of carbon dioxide in the mixed flue gas obtained from the combustion of the waste, eliminating the need for subsequent carbon dioxide capture processes. Furthermore, this invention fully utilizes oxygen, a byproduct of the electrolytic production of green hydrogen, and mixes it with recycled carbon dioxide from the combustion of municipal solid waste to create a suitable incineration atmosphere. This process does not introduce nitrogen, and the high volumetric proportion of carbon dioxide in the mixed flue gas eliminates the need for carbon dioxide capture, reducing the cost of green methanol synthesis by approximately 20% or more. Simultaneously, this invention recycles and incinerates the remaining carbon dioxide to control the incineration atmosphere, maintain the combustion temperature, and significantly reduce NO₂ levels. x Original concentration of the product. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the process for preparing green methanol by waste incineration according to the present invention. Detailed Implementation

[0017] This invention provides a method for treating municipal solid waste with an adjustable combustion atmosphere through incineration, comprising the following steps: S1. The household waste is dried and vented to obtain dried waste; the drying temperature is 120~150℃; the N2 content in the dried waste is less than 5%; S3. The dried waste is incinerated in a mixed atmosphere of oxygen and circulating carbon dioxide to obtain mixed flue gas; the volume fraction of carbon dioxide in the mixed flue gas is >90%; the oxygen is produced by electrolysis of water. S4. The mixed flue gas is purified to obtain carbon dioxide; a portion of the obtained carbon dioxide is mixed with hydrogen and subjected to a hydrogenation reaction to obtain green methanol; the hydrogen is produced by electrolysis of water. The remaining carbon dioxide in step S4 is the recycled carbon dioxide from step S3.

[0018] Unless otherwise specified, all raw materials used in this invention are commercially available products well known to those skilled in the art.

[0019] This invention dries and exhausts municipal solid waste to obtain dried municipal solid waste. The drying temperature is 120-150℃, and in specific embodiments, it can be 130, 135, or 140℃. The holding time is ≥0.5h, specifically 0.5-3h, and in specific embodiments, it can be 1h, 1.5h, or 2h. The drying process utilizes the residual heat generated by the steam after incineration in step S3, or the residual heat of the remaining carbon dioxide obtained in step S4. The drying is carried out in a rotary drying furnace. The N2 content in the dried waste is less than 5%, specifically 0.3-4.8%, and in specific embodiments, it can be 0.5, 1, 1.3, 2.8, 3.5, or 4.5%. The municipal solid waste can be municipal household waste. This invention places the municipal solid waste in a waste drying rotary furnace, which is heated by steam generated from the residual heat of the waste incinerator or purified carbon dioxide flue gas, controlling the heating temperature at 120-150℃. Inside the waste drying unit, the moisture in the municipal solid waste is heated to produce waste steam. This waste steam drives out the air trapped in the gaps between the waste particles, resulting in dried waste. After drying, nitrogen (N2 < 5%) is removed from the gaps in the waste, making it essentially air-free and increasing the purity of carbon dioxide in the mixed flue gas obtained after the waste is burned.

[0020] In this invention, the municipal solid waste is dried and then vented; the waste gas obtained from drying the municipal solid waste is passed into a waste gas treatment unit for condensation and deodorization treatment before being discharged.

[0021] This invention produces hydrogen and oxygen by electrolyzing water; there are no special limitations on the electrolysis of water for hydrogen production, and any method known to those skilled in the art can be used.

[0022] After obtaining dried waste, the present invention incinerates the dried waste in a mixed atmosphere of oxygen and recycled carbon dioxide to obtain mixed flue gas; the volume fraction of carbon dioxide in the mixed flue gas is >90%; the oxygen comes from the oxygen generated by water electrolysis; the mixed flue gas is purified to obtain carbon dioxide; a portion of the obtained carbon dioxide is mixed with hydrogen and subjected to a hydrogenation reaction to obtain green methanol; the hydrogen comes from the hydrogen generated by water electrolysis; the remaining carbon dioxide in step S4 is the recycled carbon dioxide from step S3.

[0023] In this invention, the volume concentration of oxygen in the oxygen and circulating carbon dioxide mixed atmosphere is 15-30%, and in specific embodiments it can be 17, 20, 21, 23, 25 or 27%.

[0024] This invention does not impose any special limitations on flue gas purification; any method known to those skilled in the art can be used. In specific embodiments, selective non-catalytic reduction (SNCR), dry deacidification, bag filter dust collection, and wet deacidification can be performed sequentially.

[0025] In this invention, the volume ratio of partial carbon dioxide to residual carbon dioxide in step S4 is 1~2:2.~6. In specific embodiments, it can be 1.1:2.5, 1.5:4.5, 2:2.45, or 2.05:5.85. The incineration temperature in step S3 is 900~1000℃. In specific embodiments, it can be 930, 950, or 980℃. This invention controls the circulation volume of circulating carbon dioxide (i.e., residual carbon dioxide) through a flow controller, thereby adjusting the oxygen volume concentration during incineration to 15~30% to ensure effective incineration at 900~1000℃. Specifically, in this invention, when the waste combustion temperature is below 900℃, the oxygen concentration is increased; when the waste combustion temperature is above 1000℃, the oxygen concentration is decreased. By controlling the mixing ratio of circulating carbon dioxide and oxygen in real time, the waste combustion temperature is effectively stabilized within the 900~1000℃ range, significantly reducing SO2 and NO. x It can remove pollutants such as waste and prevent coking in waste incinerators.

[0026] The present invention also provides a system for preparing green methanol by incinerating municipal solid waste with adjustable combustion atmosphere, including a waste drying unit, a waste gas treatment unit, a waste incineration unit, a flue gas purification unit, a flow controller, a methanol synthesis unit, and an electrolysis hydrogen production unit.

[0027] In this invention, the waste drying unit is a waste drying rotary kiln, and the waste incineration unit can be a waste incinerator.

[0028] In this invention, the exhaust port of the waste drying unit is connected to the waste gas treatment unit, and the discharge port of the waste unit is connected to the waste incineration unit. The waste incineration unit is connected to the flue gas purification unit; the flue gas purification unit is connected to the methanol synthesis unit; and the flue gas purification unit is connected to the waste incineration unit through a gas mixing device. The hydrogen outlet of the electrolytic hydrogen production unit is connected to the methanol synthesis unit, and the oxygen outlet of the electrolytic hydrogen production unit is connected to the waste incineration unit through a gas mixing device.

[0029] In this invention, the waste incineration unit further includes an exhaust port, which is connected to the waste drying unit; or the flue gas purification unit further includes a component connected to the waste drying unit. To further illustrate the present invention, the method and system for treating municipal solid waste with adjusted combustion atmosphere provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0030] Example 1 according to Figure 1 The process diagram illustrates the preparation of green methanol, and the specific steps are as follows: S1. 500 t of waste is placed in a waste drying rotary kiln and dried at 150℃ for 1 hour. After drying, the N2 content in the waste is approximately 3%. S2. Electrolysis of water to produce hydrogen and oxygen; S3. Place the above-mentioned dry waste in a waste incinerator and introduce 10,000 Nm³ of air. 3 / h oxygen and 24,500 Nm 3 / h of recycled carbon dioxide, incinerated at 1000℃, yields 35,000 Nm³. 3 / h of mixed flue gas, with CO2 accounting for 94% of the volume in the mixed flue gas; S4. The above mixed flue gas is purified to obtain 10,500 Nm³. 3 / h carbon dioxide and 28,300 Nm 3 / h of hydrogen is mixed and hydrogenated to prepare green methanol; the hydrogen is the hydrogen obtained in step S2.

[0031] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for treating municipal solid waste with an adjustable combustion atmosphere through incineration, characterized in that, Includes the following steps: S1. The household waste is dried and vented to obtain dried waste; the drying temperature is 120~150℃; the N2 content in the dried waste is less than 5%; S3. The dried waste is incinerated in a mixed atmosphere of oxygen and circulating carbon dioxide to obtain mixed flue gas; the volume fraction of carbon dioxide in the mixed flue gas is >90%; the oxygen is produced by electrolysis of water. S4. The mixed flue gas is purified to obtain carbon dioxide; a portion of the obtained carbon dioxide is mixed with hydrogen and subjected to a hydrogenation reaction to obtain green methanol; the hydrogen is produced by electrolysis of water. The remaining carbon dioxide in step S4 is the recycled carbon dioxide from step S3.

2. The method for treating municipal solid waste by incineration according to claim 1, characterized in that, In step S1, the drying process uses the steam generated after incineration in step S3 for heating and drying.

3. The method for treating municipal solid waste by incineration according to claim 1, characterized in that, In step S1, the drying process utilizes the residual heat from the remaining carbon dioxide obtained in step S4 for heating and drying.

4. The method for treating municipal solid waste by incineration according to any one of claims 1 to 3, characterized in that, The drying and heat preservation time in step S1 is ≥0.5h.

5. The method for treating municipal solid waste by incineration according to claim 1, characterized in that, In step S3, the volume concentration of oxygen in the mixed atmosphere of oxygen and circulating carbon dioxide is 15-30%.

6. The method for treating municipal solid waste by incineration according to claim 1 or 5, characterized in that, The incineration temperature in step S3 is 900~1000℃.

7. The method for treating municipal solid waste by incineration according to claim 1, characterized in that, In step S4, the volume ratio of some carbon dioxide to the remaining carbon dioxide is 1~2:2~6.

8. The method for treating municipal solid waste by incineration according to claim 1, characterized in that, Step S4, flue gas purification, includes sequential selective non-catalytic reduction, dry deacidification, bag filter dust collection, and wet deacidification.

9. A system for producing green methanol by incinerating municipal solid waste with an adjustable combustion atmosphere, characterized in that, It includes a waste drying unit, a waste gas treatment unit, a waste incineration unit, a flue gas purification unit, a flow controller, a methanol synthesis unit, and an electrolysis hydrogen production unit.

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