Household garbage pretreatment and gasification integrated method and application

Abstract

The invention provides a household garbage pretreatment and gasification integrated method and application, and relates to the technical field of solid waste treatment.The household garbage pretreatment and gasification integrated method comprises the following steps that garbage is subjected to pretreatment and gasification treatment in sequence, and combustible gas is obtained; wherein the pretreatment comprises carbonization, and the carbonization comprises the following steps: carrying out partial carbonization treatment on the garbage in an anoxic atmosphere at the temperature of 300-500 DEG C; according to the method, the problems that in the prior art, the pretreatment process is complex, the gasification efficiency is low, secondary pollution is difficult to control, and the hydrogen yield is low are solved, and efficient, clean and resource utilization of the household garbage is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment, and in particular to a method for integrating pretreatment and gasification of domestic waste and its application. Background Art

[0002] With the acceleration of urbanization, the amount of domestic waste generated has increased dramatically. Traditional treatment methods such as landfill and incineration are no longer able to meet the requirements of environmental protection and resource utilization. Landfilling occupies a large amount of land resources and is prone to producing leachate and greenhouse gases, causing secondary pollution. While incineration can achieve waste reduction and energy recovery, it also has the problem of emitting harmful gases such as dioxins and requires a high calorific value for the waste. As an emerging treatment method, domestic waste gasification technology can convert waste into a combustible gas (syngas). It has the advantages of high energy recovery efficiency and low secondary pollution, and has attracted widespread attention in recent years.

[0003] However, the existing domestic waste gasification technology still faces the following technical bottlenecks: (1) Complex pretreatment process: Domestic waste has complex composition and high moisture content, and needs to go through multiple pretreatment steps (such as crushing, sorting, drying, etc.) to meet the gasification requirements, resulting in a long process flow, large equipment investment, and high operating costs. (2) Low gasification efficiency: The high moisture content and low calorific value of the waste lead to insufficient gasification reaction, low calorific value of synthesis gas, and large amount of tar generated, which affects subsequent utilization. (3) Difficulty in controlling secondary pollution: Pollutants such as tar, acidic gases (such as HCl, H2S) and heavy metals generated during the gasification process can easily cause secondary pollution if not handled properly. (4) Low hydrogen yield: Traditional gasification processes are difficult to achieve efficient conversion of waste, and the hydrogen yield is low, which limits the high value-added utilization of synthesis gas.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] One of the objectives of the present invention is to provide an integrated method for pretreatment and gasification of domestic waste to address at least one of the technical problems existing in the prior art. This method addresses the existing issues of complex pretreatment processes, low gasification efficiency, difficulty in controlling secondary pollution, and low hydrogen yield, thereby achieving efficient, clean, and resourceful utilization of domestic waste.

[0006] A second object of the present invention is to provide an integrated method for pretreatment and gasification of domestic waste for application in waste treatment.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0008] In a first aspect, the present invention provides a method for integrating pretreatment and gasification of domestic waste, comprising the following steps: pretreating and gasifying the waste in sequence to obtain combustible gas;

[0009] Wherein, the pretreatment includes carbonization, and the carbonization includes: partially carbonizing the garbage in an oxygen-deficient atmosphere at a temperature of 300-500°C;

[0010] The carbonized garbage is transported by hot air flow into the gasification process.

[0011] Furthermore, the carbonization time is 30-60 minutes;

[0012] Preferably, the carbonization is performed under a nitrogen or carbon dioxide atmosphere.

[0013] Furthermore, the conveying speed is 10-20 m / s.

[0014] Furthermore, during the transportation process, the carbonized garbage is mixed with the gasifying agent;

[0015] Preferably, a plurality of static mixing units are provided in the pipeline used for transportation;

[0016] Preferably, the static mixing unit comprises helical blades or baffles.

[0017] Furthermore, the gasification process includes primary gasification and secondary gasification performed sequentially;

[0018] Preferably, the temperature of the primary gasification is 800-900°C;

[0019] Preferably, the gasifying agent for the primary gasification comprises air and water vapor, and the volume ratio of air to water vapor is 1:0.5-1:1;

[0020] Preferably, the temperature of the secondary gasification is 1000-1200°C;

[0021] Preferably, the gasification agent of the secondary gasification includes water vapor.

[0022] Furthermore, the pretreatment also includes crushing and sorting, and the crushed and sorted garbage enters the carbonization process;

[0023] Preferably, the crushing and sorting includes primary crushing, primary sorting, secondary crushing and secondary sorting performed in sequence;

[0024] Preferably, the particle size of the garbage after the first stage of crushing is less than 100 mm;

[0025] Preferably, the primary separation includes magnetic separation and air separation to separate metals and light plastics in the garbage;

[0026] Preferably, the particle size of the garbage after the secondary crushing is less than 30 mm;

[0027] Preferably, the secondary sorting includes screening to separate inorganic matter in the garbage to obtain organic garbage.

[0028] Furthermore, the integrated method of pretreatment and gasification of domestic waste also includes gas purification, wherein the combustible gas obtained by gasification treatment is purified to obtain clean combustible gas;

[0029] After the gasification process, it also includes gas purification process;

[0030] Preferably, the gas purification treatment includes dust removal, water washing, desulfurization and denitrification performed in sequence;

[0031] Preferably, cyclone dust removal is used to remove large dust particles in the gas;

[0032] Preferably, a water scrubber is used to remove tar and some acid gases from the gas;

[0033] Preferably, a desulfurization tower is used to remove SO2 from the gas;

[0034] Preferably, a denitrification tower is used to remove NO in the gas. x .

[0035] Furthermore, the integrated method of pre-treatment and gasification of domestic waste also includes a waste heat utilization process, which includes: transporting the high-temperature flue gas generated by the gasification process to a waste heat boiler to generate steam for power generation or heating;

[0036] Preferably, the steam pressure is 1.0-1.6 MPa and the steam temperature is 300-350°C.

[0037] Furthermore, the integrated method of pre-treatment and gasification of domestic waste also includes ash treatment, which includes: subjecting the ash produced by the gasification treatment to high-temperature melting treatment to form a recyclable glass body;

[0038] Preferably, the melting temperature is 1400-1600° C., and the melting time is 30-60 minutes.

[0039] In a second aspect, the present invention provides an application of an integrated method for pretreatment and gasification of domestic waste in waste treatment.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention introduces a carbonization process (300-500°C) in the pretreatment stage through the coupling of carbonization and air flow conveying, and simultaneously completes drying, homogenization and carbon-based material preparation, replacing the traditional multi-stage crushing, drying and sorting process. The new pretreatment-gasification coupling directly connects the carbonization and gasification units through air flow conveying, reduces intermediate storage and transportation equipment, and realizes continuous feeding. By adopting a new process, the process is simplified, and carbonization replaces traditional drying and part of the sorting steps. The independent dryer and multi-stage sorting machine are eliminated, and synergistic efficiency is enhanced. The calorific value of the garbage after carbonization is increased by 20%-30%, which reduces the subsequent gasification energy consumption and indirectly improves the overall efficiency.

[0042] This invention utilizes a two-stage gasification process: rapid pyrolysis in a fluidized bed (800-900°C) in the first stage, followed by deep gasification in a fixed bed (1000-1200°C). This process increases carbon conversion to ≥95%. Carbonization produces porous carbon (with a specific surface area of 500-800 m² / g), enhancing gasification reaction kinetics. Through optimized stage-by-stage operation, efficient heat transfer in the fluidized bed ensures rapid decomposition, while the high-temperature environment of the fixed bed promotes tar cracking and complete conversion of residual carbon.

[0043] The present invention provides an integrated method for pretreatment and gasification of domestic waste, wherein the carbonization temperature used is 300-500°C, which is much lower than the conventional biochar preparation temperature (usually >500°C), and an anaerobic pyrolysis method is adopted to achieve carbonization treatment of the garbage, retaining 30%-40% of the volatile matter, thereby retaining part of the calorific value, and thus improving the calorific value of the synthesis gas. At the same time, during the carbonization process, the long-chain organic matter (tar precursor) in the garbage undergoes selective chain scission in a low-temperature, oxygen-deficient environment of 300-500°C, reducing the amount of tar generated. The present invention adds a carbonization process in the pretreatment stage to convert garbage with low moisture content into carbon-based materials, improve gasification efficiency and reduce tar generation; and the present invention uses a hot air flow to transport the carbonized garbage, and the hot air flow is in full contact with the carbon-based material particles converted from the garbage, not only completing the transportation of the material, but also simultaneously realizing secondary drying and preheating of the garbage, shortening the process flow and improving process efficiency. The present invention realizes efficient, clean and resource-based treatment of domestic waste by integrating carbonization, air flow transportation and gasification treatment. DETAILED DESCRIPTION

[0044] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, the use of "or" means "and / or" unless otherwise stated. In addition, the use of the term "including" and other forms is non-limiting.

[0045] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] The first aspect of the present invention provides an integrated method for pretreatment and gasification of domestic waste, comprising the following steps: pretreating and gasifying the waste in sequence to obtain combustible gas; wherein the pretreatment includes carbonization, and the carbonization includes: partially carbonizing the waste in an oxygen-deficient atmosphere at a temperature of 300-500°C; and using a hot air flow to transport the carbonized waste into the gasification treatment.

[0047] In some preferred embodiments, the carbonization time is 30-60 minutes, for example, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc.;

[0048] Preferably, the carbonization is performed under a nitrogen or carbon dioxide atmosphere.

[0049] The carbonization process in this invention involves an anaerobic pyrolysis reaction at 300-500°C. Crushed and sorted organic waste is transported to a carbonization reactor, where low-temperature pyrolysis occurs in the absence of oxygen. This converts the low-moisture waste into carbon-based materials, improving gasification efficiency and reducing tar production. After carbonization, the waste's moisture content drops below 5%, its calorific value increases by 20-30%, and tar production is reduced by over 50%.

[0050] Specifically, the present invention incorporates a carbonization process into the pretreatment stage to convert low-moisture waste into carbon-based materials, thereby improving gasification efficiency and reducing tar generation. The specific significance of this is reflected in the following aspects:

[0051] (1) Traditional carbonization processes are mostly used to prepare solid fuels (such as RDF) or biochar, while the present invention uses carbonization as a gasification precursor step, and its core purpose is to change the reaction characteristics of garbage. The carbonization of the present invention not only reduces the moisture content (to below 5%), but also converts the organic matter in the garbage into highly reactive carbon-based materials (porosity increased by 50%-70%, and specific surface area increased by 3-5 times). This structural change increases the gasification reaction rate by 2-3 times, and the gasification efficiency is increased from 60%-70% in traditional processes to 85%-90%. In addition, during the carbonization process of the present invention, the long-chain organic matter (tar precursor) in the garbage undergoes selective chain breaking in a low-temperature, oxygen-deficient environment of 300-500°C to generate a short-chain carbon structure. The amount of gasified tar generated after carbonization is increased from the conventional 150-200 mg / Nm 3 Reduced to 50mg / Nm 3The following is a 60%-75% reduction, and no additional tar processing equipment is required.

[0052] (2) The present invention achieves tar reduction through temperature-atmosphere synergistic control. At the same time, the present invention controls specific carbonization conditions (such as temperature, atmosphere, residence time) so that some volatiles (such as tar, gas, etc.) are retained, thereby improving the calorific value of the synthesis gas. Therefore, the present invention improves the calorific value by retaining some volatiles and synergizing with carbon-based materials.

[0053] (3) "Reverse regulation" of heavy metal migration behavior: Heavy metals (such as Pb and Cd) in domestic waste are easily volatilized into the gas phase during the high-temperature gasification stage and need to be treated through a complex purification process. The carbonization process of the present invention enables heavy metals to form a chelate structure with carbon-based materials, which remains stable in the subsequent gasification stage (1000-1200°C). The solidification rate of heavy metals in ash is increased from about 85% in traditional processes to more than 99%, and the concentration of heavy metal emissions in the gas phase is reduced by an order of magnitude. The synergistic effect of carbonization on the change in the occurrence form of heavy metals and high-temperature gasification has broken through the traditional perception that "the higher the temperature, the more volatile the heavy metals."

[0054] (4) “Abnormal optimization” of syngas component distribution: The volume fraction of H in the syngas from MSW gasification is usually around 20%, and the hydrogen yield needs to be increased through post-treatment such as steam reforming.

[0055] The carbon-based material produced by carbonization undergoes an enhanced reaction with water vapor during the gasification stage (C + HO → CO + H), increasing the H volume fraction to approximately 40% and optimizing the CO / CO ratio from 1:1 to 3:1, thereby increasing the calorific value of the syngas. The carbonization process's ability to directionally control the gasification reaction pathway far exceeds the effectiveness of simple drying pretreatment.

[0056] In some preferred embodiments, the conveying speed is 10-20 m / s, for example, 10 m / s, 15 m / s, 20 m / s, etc.

[0057] In some preferred embodiments, during the transportation process, the carbonized garbage is mixed with a gasifying agent;

[0058] Preferably, a plurality of static mixing units are provided in the pipeline used for transportation;

[0059] Preferably, the static mixing unit comprises helical blades or baffles.

[0060] Specifically, the present invention uses air flow conveying in combination with a static mixing unit to achieve material mixing. The carbonized garbage is transported to the next process using a pretreatment-gasification coupled air flow conveying system. During the transportation process, dynamic mixing of the garbage and the gasifying agent is achieved to ensure that the garbage is evenly heated and fully reacted.

[0061] This invention integrates pretreatment with a gasifier, achieving continuous waste feeding and efficient pyrolysis through airflow conveying and dynamic mixing technologies. The airflow conveying system utilizes the high-temperature flue gas generated by the gasifier as the conveying medium, while also dynamically mixing the waste with the gasifying agent to ensure uniform reaction. This method simplifies the traditional separation of pretreatment and gasification processes, enabling continuous operation, shortening the overall process time, and reducing equipment investment and operating costs.

[0062] It is further explained that the air flow conveying and dynamic mixing method of the present invention not only achieves efficient mixing and continuous feeding of garbage and gasifying agent, but also produces the following effects beyond conventional expectations:

[0063] (1) Pyrolysis and drying are completed simultaneously, reducing pretreatment energy consumption. The air flow conveying medium directly uses the high-temperature flue gas (temperature is 600-800℃) generated by the gasification furnace. During the conveying process, the high-temperature flue gas is in full contact with the garbage particles, which not only completes the material conveying, but also simultaneously realizes the secondary drying and preheating of the garbage.

[0064] In traditional processes, drying requires a separate drying device and consumes additional energy. However, this technology integrates the drying process into the transportation link through the cascade utilization of waste heat, reducing the moisture content of the garbage from the initial 20% to below 10%, saving 30%-40% of drying energy consumption.

[0065] (2) Inhibit tar formation and improve gas quality. Dynamic mixing technology uses multi-stage static mixing units (such as spiral blades or baffles) in the conveying pipeline to force garbage particles and gasification agents (air / water vapor) into a turbulent state, greatly improving mixing uniformity. At the same time, the oxidizing atmosphere of the high-temperature flue gas can partially oxidize the tar precursors in situ.

[0066] In traditional gasification process, the amount of tar generated is usually 100-200 mg / Nm 3 The present invention reduces the tar content to 50mg / Nm by strengthening the mixing and thermochemical synergy. 3 In the following, there is no need to set up an additional tar cracking furnace, which simplifies the purification process.

[0067] (3) Avoid material agglomeration and improve system stability. The air flow conveying adopts a high-speed turbulent flow mode (10-20m / s). The garbage particles are always in a suspended state during the conveying process, avoiding the agglomeration problem caused by local high temperature; the shearing effect of the mixing process further breaks up the agglomerated particles.

[0068] Traditional mechanical conveying (such as screw conveyors) is prone to clogging due to the sticky components of garbage (such as kitchen waste). However, the present invention increases the continuous operation time of the system to more than 2,000 hours and extends the maintenance cycle by 3 times.

[0069] (4) Strengthening the gasification reaction kinetics and increasing hydrogen yield. Dynamic mixing increases the contact area between garbage particles and the gasifying agent (water vapor, etc.). In the first stage of the gasifier (fluidized bed), the gasification reaction rate of water vapor and air with carbon-based materials is significantly increased. At the same time, the incompletely reacted particles carried by the high-speed airflow enter the second stage of the gasifier (fixed bed), achieving deep gasification.

[0070] The hydrogen gas volume fraction of the traditional single-stage gasification process is usually around 20%, but this technology uses two-stage gasification and mixing enhancement to increase the hydrogen yield to around 40%, and the calorific value of the synthesis gas is also improved.

[0071] (5) Reduce heavy metal volatilization and reduce the risk of secondary pollution. High-temperature flue gas (containing reducing gases such as CO and H2) is used as a transport medium. During the dynamic mixing process, it undergoes an in-situ reduction reaction with heavy metals (such as Pb and Cd) in the garbage, generating stable metal elements or alloys, which inhibits their volatilization in the high-temperature section of the gasifier.

[0072] The solidification rate of heavy metals in ash has been increased from about 85% in traditional processes to more than 99%, and the concentration of heavy metal emissions in exhaust gas is lower than the limit of the "Pollution Control Standards for Incineration of Municipal Waste" (GB 18485-2014).

[0073] (6) Adapt to complex waste components and improve process compatibility. The flexible design of airflow conveying (such as adjustable flow rate and mixing intensity) can adapt to waste components with different moisture content and calorific value (such as kitchen waste, plastics, textiles, etc.). Dynamic mixing technology adjusts the mixer angle through real-time feedback to ensure reaction uniformity. Traditional gasification processes have high requirements for the calorific value of waste (needed to be >4000kJ / kg), while the present invention can process waste with a calorific value as low as 2500kJ / kg through online carbonization and mixing enhancement, and its scope of application is expanded to mixed domestic waste, garden waste, etc.

[0074] In some preferred embodiments, the gasification process includes primary gasification and secondary gasification performed sequentially.

[0075] In the present invention, the design of two-stage gasification can achieve the following: (1) Solve the tar problem. In the traditional single-stage gasification process, the tar production is high (100-200 mg / Nm 3 ), which can easily clog pipelines, reduce equipment life, and require additional purification costs. The two-stage gasification controls the reaction conditions in stages. After the first stage of pyrolysis, the second stage of high temperature environment (1000-1200℃) promotes tar cracking, significantly reducing the tar content to 20mg / Nm 3 (2) Improve the quality of syngas. Single-stage gasification often results in low calorific value of syngas (8-10MJ / Nm 3The two-stage design optimizes the gas composition through rapid pyrolysis (800-900°C) in the first stage fluidized bed and deep gasification (pure water vapor environment) in the second stage fixed bed, increasing the hydrogen volume fraction to 40%-50% and the calorific value to 12-15MJ / Nm 3 (3) Adapting to the characteristics of complex fuels, in view of the low calorific value and large fluctuation of composition of low-grade fuels such as biomass and crushed coal, two-stage gasification enhances fuel adaptability through staged treatment (such as fluidized bed pyrolysis + fixed bed gasification); (4) Optimizing energy utilization efficiency, through waste heat recovery (such as preheating of gasification agent by high-temperature flue gas in gasifier) and reaction heat balance (cooperation of heat release in the first stage and heat absorption in the second stage), the system thermal efficiency is increased to 85%-90%, which is 15%-25% higher than that of the single-stage process.

[0076] The two-stage gasification in the present invention cooperates with each other and is indispensable, and has the following advantages and effects:

[0077] (1) Outstanding tar control capability. Two-stage gasification combined with high-temperature catalytic cracking and semi-coke bed adsorption can reduce the tar content to 20mg / Nm 3 The following reduces the subsequent purification costs;

[0078] (2) High energy conversion efficiency. Carbon conversion rate ≥ 95% (conventional process 70%-80%), and the proportion of effective components (H+CO) in syngas is increased to more than 80%;

[0079] (3) Wide fuel adaptability. It can process a variety of raw materials such as Chinese medicine residue, white wine lees, crushed coal, corn straw, etc., with a fuel calorific value range of 2500-23,700kJ / kg. It has a high tolerance for moisture content (15%-30%) and ash content (≤20%), reducing pretreatment costs;

[0080] (4) Environmental protection and economical performance: heavy metal solidification rate ≥99%, dioxin emission ≤0.05ng TEQ / Nm 3 , better than the national standard.

[0081] Preferably, the temperature of the primary gasification is 800-900°C, for example, 800°C, 850°C, 900°C, etc.;

[0082] Preferably, the gasifying agent for the primary gasification comprises air and water vapor, and the volume ratio of air to water vapor is 1:0.5-1:1, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.;

[0083] Preferably, the temperature of the secondary gasification is 1000-1200°C, for example, 1000°C, 1100°C, 1200°C, etc.;

[0084] Preferably, the gasification agent of the secondary gasification includes water vapor.

[0085] In this invention, the mixed garbage and gasifying agent are transported to a two-stage gasifier. The first stage performs rapid pyrolysis to generate combustible gas and tar with CO, H2, and CH4 as the main components. The second stage performs deep gasification to further crack the tar into small molecular gases, significantly improving the hydrogen yield. The hydrogen volume fraction in the syngas is increased to 40%-50%, and the tar content is reduced to 50mg / Nm 3 the following.

[0086] Specifically, in the first-stage gasification process, a fluidized bed gasifier is used for rapid pyrolysis and preliminary gasification. The fluidized bed's efficient heat and mass transfer characteristics enable rapid pyrolysis of the waste, generating syngas (CO, H, CH) and tar. Adjusting the gasifying agent (air / water vapor) ratio allows for partial oxidation of tar precursors, reducing the total tar production. The gasifying agents for the first-stage gasification process are air and water vapor. The oxygen (O) in the air partially oxidizes the carbon in the waste (C+O→CO, ΔH=-393.5 kJ / mol), releasing a significant amount of heat to maintain the fluidized bed reaction temperature (800-900°C), achieving self-heating operation and reducing external energy input.

[0087] In secondary gasification, a fixed-bed gasifier is used: deep gasification and tar cracking are carried out. The high temperature environment promotes the catalytic cracking of the tar, converting it into small molecular gases (such as H and CO), significantly increasing the hydrogen yield. Unreacted carbon-based residues further react with water vapor in the fixed bed to achieve complete carbon gasification. The gasifying agent for secondary gasification is pure water vapor. In the high temperature environment of the fixed bed (1000-1200°C), the water vapor and residual tar undergo a reforming reaction (CH + HO → nCO + (m / 2 + n)H), completely converting the tar into H and CO.

[0088] In some preferred embodiments, the pretreatment further comprises crushing and sorting, and the crushed and sorted garbage enters the carbonization process;

[0089] Preferably, the crushing and sorting includes primary crushing, primary sorting, secondary crushing and secondary sorting performed in sequence;

[0090] Preferably, the particle size of the garbage after the first stage of crushing is less than 100 mm;

[0091] Preferably, the primary separation includes magnetic separation and air separation to separate metals and light plastics in the garbage;

[0092] Preferably, the particle size of the garbage after the secondary crushing is less than 30 mm;

[0093] Preferably, the secondary sorting includes screening to separate inorganic matter in the garbage to obtain organic garbage.

[0094] Specifically, in the crushing and sorting process, domestic waste is crushed and processed, and the crushed waste is separated into recyclable materials such as metals, glass, and plastics, as well as inorganic materials such as bricks, stones, and ceramics through magnetic separation, air separation, screening, etc., to obtain organic waste with uniform particle size.

[0095] In some preferred embodiments, the integrated method for pretreatment and gasification of domestic waste further comprises gas purification, wherein the combustible gas obtained by the gasification treatment is subjected to gas purification to obtain clean combustible gas;

[0096] After the gasification process, it also includes gas purification process;

[0097] Preferably, the gas purification treatment includes dust removal, water washing, desulfurization and denitrification performed in sequence;

[0098] Preferably, cyclone dust removal is used to remove large dust particles in the gas;

[0099] Preferably, a water scrubber is used to remove tar and some acid gases from the gas;

[0100] Preferably, a desulfurization tower is used to remove SO2 from the gas;

[0101] Preferably, a denitrification tower is used to remove NO from the gas. x .

[0102] Specifically, the present invention transports the combustible gas generated by the gasifier to the gas purification system, which sequentially undergoes cyclone dust removal, water washing, desulfurization, denitrification and other processes to remove impurities such as dust, tar, and acidic gas in the gas to obtain clean combustible gas.

[0103] In some preferred embodiments, the integrated method for pretreatment and gasification of domestic waste further comprises a waste heat utilization step, wherein the waste heat utilization step comprises: conveying the high-temperature flue gas generated by the gasification process to a waste heat boiler to generate steam for power generation or heat supply;

[0104] Preferably, the steam pressure is 1.0-1.6 MPa, for example, 1.0 MPa, 1.3 MPa, 1.6 MPa, etc.; the steam temperature is 300-350°C, for example, 300°C, 325°C, 350°C, etc.

[0105] Specifically, the present invention transfers the high-temperature flue gas from the gasifier to a waste heat boiler, generating steam for power generation or heat supply, achieving cascaded energy utilization. Using a horizontal waste heat boiler, steam is generated at a pressure of 1.0-1.6 MPa and a temperature of 300-350°C. This steam is used to drive a steam turbine for power generation or external heat supply, achieving energy utilization.

[0106] In some preferred embodiments, the integrated method of pre-treatment and gasification of domestic waste further comprises ash treatment, wherein the ash treatment comprises: subjecting the ash produced by the gasification treatment to high-temperature melting treatment to form a recyclable glass body;

[0107] Preferably, the melting temperature is 1400-1600°C, for example, 1400°C, 1500°C, 1600°C, etc.; the melting time is 30-60 minutes, for example, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc.

[0108] Specifically, the present invention melts the ash produced by the gasification furnace at high temperatures to form a vitreous structure, achieving both harmless ash disposal and resource utilization. Using a plasma melting furnace, the melting temperature is controlled between 1400-1600°C and the melting time is controlled between 30-60 minutes. The resulting vitreous structure has a heavy metal solidification rate exceeding 99%, making it suitable for direct use in building materials production.

[0109] Preferably, the melting temperature in the present invention is 1400-1600°C, the high-temperature heat source adopts the composite heat source of gasification synthesis gas combustion + plasma assistance of the present invention, and the main heat source adopts the synthesis gas generated by gasification and oxygen-enriched combustion to provide basic high temperature (1600-1800°C). The auxiliary heat source adopts a plasma torch to supplement energy to cope with fluctuations in ash composition or insufficient synthesis gas supply. Gasification synthesis gas combustion uses the synthesis gas (CO, H, CH) generated by garbage gasification as fuel and releases high temperature through oxygen-enriched combustion or pure oxygen combustion. Energy self-sufficiency is achieved through this method, and the calorific value of the synthesis gas is 12-15MJ / Nm 3 The combustion temperature can reach 1800-2000°C, reducing dependence on external energy sources and improving system thermal efficiency. During combustion, oxygen-enriched combustion increases flame temperature and reduces nitrogen oxide generation. Furthermore, staged combustion and phased oxygen supply reduce heat loss in local high-temperature areas.

[0110] The integrated method of pretreatment and gasification of domestic waste provided by the present invention solves the problems of complex pretreatment process, low gasification efficiency, difficult secondary pollution control, low hydrogen yield and other problems in the prior art. Specifically: The present invention achieves a breakthrough in domestic waste treatment efficiency and environmental performance through carbonization-gasification coupling, multi-stage reaction optimization and coordinated control of pollutants. The integrated design of pretreatment and gasification reduces equipment redundancy; through reaction intensification, carbon-based materials improve gasification kinetics, and two-stage gasification maximizes hydrogen yield; full-chain pollution prevention and control from source control (tar chain scission) to end treatment (melting solidification). The details are as follows:

[0111] (1) The present invention solves the problem of complex pretreatment process. Traditional pretreatment requires multi-stage crushing, sorting, and drying, with large equipment investment and long process. The present invention couples online carbonization with air flow conveying, introduces low-temperature carbonization (300-500°C) in the pretreatment stage, converts garbage into carbon-based materials, and simultaneously completes drying, homogenization and carbon-based material preparation, replacing the traditional multi-stage crushing, drying, and sorting process, reducing the need for separate drying equipment. The heat released by the volatile matter during the carbonization process can partially replace the external drying energy consumption, reducing the pretreatment energy consumption. In addition, this solution adopts a two-stage sorting optimization, with the first stage magnetic separation / air separation separating metals and light materials, and the second stage screening (drum screen) removing masonry and ceramics, thereby improving the sorting efficiency. The double-layer drum screen design (aperture 30mm+10mm) makes the inorganic matter removal rate >97% and the organic matter recovery rate >90%. Through integrated innovation, the company breaks down traditional process barriers by introducing a carbonization process (300-500°C) during the pretreatment phase. Airflow directly connects the carbonization and gasification units, reducing intermediate storage and transportation equipment, enabling continuous feeding and streamlining the process. Carbonization replaces traditional drying and some sorting steps. This eliminates the need for separate dryers and multi-stage sorters, creating synergistic efficiencies. The calorific value of carbonized waste increases by 20%-30%, reducing subsequent gasification energy consumption and indirectly improving overall efficiency.

[0112] (2) The present invention solves the problem of low gasification efficiency. The traditional process has a low carbon conversion rate in a single-stage gasification (70%-80%), and the calorific value of the synthesis gas is insufficient. The present invention adopts a two-stage gasification synergy. The first stage (fluidized bed) is a rapid pyrolysis at 800-900 ° C. The gasifying agent is air / water vapor, and the carbon conversion rate is increased to 85%. The second stage (fixed bed) is a pure water vapor environment at 1000-1200 ° C. The tar is cracked into H / CO, and the carbon conversion rate finally reaches more than 95%. The present invention ensures rapid decomposition through efficient heat transfer in the fluidized bed, and the high temperature environment of the fixed bed promotes tar cracking and complete conversion of residual carbon. The fluidized bed has high heat transfer efficiency (>200W / m 2 ·K) combined with fixed bed deep reaction, the gasification efficiency reaches 85%-90% (compared to 60%-70% of single-stage process). In addition, through the carbon-based material to strengthen the reaction, online carbonization generates porous carbon (specific surface area 500-800m 2 The pore structure of carbon-based materials provides more active sites for gasification reactions, increasing the gasification rate by 2-3 times. The high-temperature flue gas from the gasifier is used for carbonization and drying, improving the thermal efficiency of the system.

[0113] (3) The present invention solves the problem of difficult secondary pollution control. It is difficult to completely remove pollutants such as tar, heavy metals, and dioxins by traditional processes. The present invention adopts tar source control and cracking methods, carbonizing the tar precursor at low temperature, and cracking the tar at high temperature (>1000℃) in two-stage gasification, reducing the content to ≤20mg / Nm 3The activation energy of tar cracking is reduced by 30%. The heavy metals (Pb, Cd) are solidified at high temperature and melted in plasma (1400-1600℃) to form silicate glass, with a solidification rate of ≥99.5%. At the same time, multi-stage gas purification is carried out, including cyclone dust removal (dust removal) → water scrubber (tar removal) → alkali desulfurization (SO ≤ 50mg / Nm 3 )→SCR denitrification (NOx≤100mg / Nm 3 After purification, the flue gas meets the "Standard for Pollution Control of Municipal Waste Incineration" (GB 18485-2014). Carbonization reduces tar formation, and the high-temperature environment of the two-stage gasification further cracks the residual tar. The purification system ultimately intercepts pollutants. It also achieves heat source reuse, and the combustion of gasification synthesis gas provides the high temperature required for melting, reducing dependence on external energy, while completely decomposing dioxins (emissions ≤ 0.05ng TEQ / Nm 3 ).

[0114] (4) The present invention solves the problem of low hydrogen yield by achieving a leap in hydrogen yield through directional regulation of the reaction path and coordination with the catalyst.

[0115] Traditional gasification has a low H volume fraction. The present invention enhances steam reforming, using pure steam in the second stage of fixed-bed gasification to promote the reaction C+HO→CO+H, while simultaneously reforming tar (CH+HO→nCO+(m / 2+n)H). Through temperature-atmosphere synergy, high temperature (1200°C) and a steam excess coefficient (1.2-1.5) are optimized to increase the H volume fraction. Simultaneously, the porous carbon-based material increases the gas-solid contact area, accelerating the steam reforming reaction kinetics. Thermodynamic calculations show that at 1200°C and a steam excess coefficient of 1.2, the H yield is maximized (experimental values reach 40%-50%).

[0116] In addition, due to the catalytic effect of carbon-based materials, the ash (including CaO and FeO) in the carbonization product catalyzes the water-gas shift reaction (CO+HO→CO+H), thereby improving the H selectivity and purity.

[0117] In the optional solutions of the present invention, preferably, the integrated method for pretreatment and gasification of domestic waste specifically comprises the following steps:

[0118] Step 1. Crushing and sorting: Crushing the domestic waste. The crushed waste is separated into recyclable materials such as metal, glass, and plastic, as well as inorganic materials such as bricks, stones, and ceramics through magnetic separation, air separation, and screening, to obtain organic waste with uniform particle size. The specific steps are as follows:

[0119] (1) Primary crushing: Use a shear crusher to crush the garbage to a particle size of less than 100 mm;

[0120] (2) Primary separation: using magnetic separation and air separation to separate metals and light plastics;

[0121] (3) Secondary crushing: Using a hammer crusher, the garbage is further crushed to a particle size of less than 30 mm;

[0122] (4) Secondary sorting: Screening is used to separate inorganic materials such as bricks, stones, and ceramics to obtain organic waste with uniform particle size;

[0123] The screening steps of the secondary sorting include: feeding the material into the screening equipment; screening it through a vibrating screen or a drum screen according to the preset sieve hole size; large particles of inorganic matter (bricks, stones, ceramics) remain on the screen and are discharged from the discharge port; small particles of organic matter fall through the sieve holes into the collection device and enter the subsequent processing flow; the screened inorganic matter is further processed or disposed of.

[0124] Step 2. Carbonization: The crushed and sorted organic waste is transported to the carbonization reactor. The carbonization reactor uses a rotary carbonization furnace with an internal stirring device to ensure uniform heating of the waste. The reaction atmosphere is an oxygen-deficient atmosphere, the carbonization temperature is controlled at 300-500°C, the carbonization time is controlled at 30-60 minutes, and the carbonization atmosphere is nitrogen or carbon dioxide.

[0125] Step 3. Air flow conveying and dynamic mixing: A pneumatic conveying device is used to convey the carbonized garbage. The conveying gas is the high-temperature flue gas generated by the gasification furnace. The conveying speed is 10-20m / s. A multi-stage static mixing unit is set in the conveying pipeline to enhance the mixing effect of the garbage and the gasifying agent.

[0126] Step 4. Multi-stage gasification: The mixed garbage and gasifying agent are transported to a two-stage gasifier using the pneumatic conveying device described above, and the first-stage gasification and the second-stage gasification are carried out in sequence. The specific steps are as follows:

[0127] (1) Primary gasification: A fluidized bed gasifier is used (the fluidized bed gasifier and the fixed bed gasifier in the secondary gasification process are combined to realize material transportation through a pneumatic conveying system). The gasification temperature is controlled at 800-900°C, the gasification pressure is controlled at atmospheric pressure, and the gasifying agent is a mixture of air and water vapor, with a volume ratio of air to water vapor of 1:0.5-1:1.

[0128] (2) Secondary gasification: A fixed bed gasifier is used, the gasification temperature is controlled at 1000-1200℃, the gasification pressure is controlled at normal pressure, and water vapor is used as the gasifying agent.

[0129] Step 5. Gas Purification: The combustible gas generated by the gasifier is transported to the gas purification system, where it undergoes cyclone dust removal, water washing, desulfurization, and denitrification processes to remove impurities such as dust, tar, and acidic gases, resulting in clean combustible gas. The specific steps are as follows:

[0130] (1) Cyclone dust removal: removes large dust particles in the gas;

[0131] (2) Water scrubber: removes tar and some acid gases from the gas;

[0132] (3) Desulfurization tower: uses alkaline solution absorption method to remove SO2 in the gas;

[0133] (4) Denitrification tower: uses selective catalytic reduction to remove NO from the gas x .

[0134] The present invention simplifies the process flow by coupling pretreatment with gasification. This coupling of pretreatment and gasification organically combines the pretreatment and gasification processes, simplifying the process flow and reducing investment and operating costs. Furthermore, the gasification efficiency is improved. Online carbonization technology converts waste into carbon-based materials, significantly increasing gasification efficiency and reducing tar production. Simultaneously, the mixing effect is enhanced. Airflow conveying and dynamic mixing technologies ensure that the waste and gasifying agent are fully mixed, improving reaction uniformity. Furthermore, the hydrogen yield is increased. The multi-stage gasification system significantly increases hydrogen yield and enhances syngas quality through a two-stage gasification process.

[0135] A second aspect of the present invention provides an application of an integrated method for pretreatment and gasification of domestic waste in waste treatment.

[0136] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0137] The following examples and comparative examples all use domestic waste with a moisture content of 25%, an organic matter content of 50%, an inorganic matter content of 20% (metal 2%, glass 5%), a calorific value of 6000 kJ / kg, and a heavy metal Pb ≤ 100 mg / kg.

[0138] Example 1

[0139] This embodiment provides a method for integrated pretreatment and gasification of domestic waste, which specifically includes the following steps:

[0140] Step 1. Crushing and sorting: Crushing the domestic waste. The crushed waste is separated into recyclable materials such as metal, glass, and plastic, as well as inorganic materials such as bricks, stones, and ceramics through magnetic separation, air separation, and screening, to obtain organic waste with uniform particle size. The specific steps are as follows:

[0141] (1) Primary crushing: Use a shear crusher to crush the garbage to a particle size of less than 100 mm;

[0142] (2) Primary separation: using magnetic separation and air separation to separate metals and light plastics;

[0143] (3) Secondary crushing: Using a hammer crusher, the garbage is further crushed to a particle size of less than 30 mm;

[0144] (4) Secondary sorting: Screening is used to separate inorganic materials such as bricks, stones, and ceramics to obtain organic waste with uniform particle size.

[0145] Step 2. Carbonization: The crushed and sorted organic waste is transported to the carbonization reactor. The carbonization reactor uses a rotary carbonization furnace with an internal stirring device to ensure uniform heating of the waste. The reaction atmosphere is an oxygen-deficient atmosphere, the carbonization temperature is controlled at 400°C, the carbonization time is controlled at 45 minutes, and the carbonization atmosphere is nitrogen.

[0146] Step 3. Air flow conveying and dynamic mixing: A pneumatic conveying device is used to convey the carbonized garbage. The conveying gas is the high-temperature flue gas generated by the gasification furnace (temperature is 600-800℃), the conveying speed is 15m / s, and a multi-stage static mixing unit (spiral blades) is set in the conveying pipeline to enhance the mixing effect of the garbage and the gasifying agent.

[0147] Step 4. Multi-stage gasification: The mixed garbage and gasifying agent are transported to a two-stage gasifier for primary and secondary gasification, respectively. The specific steps are as follows:

[0148] (1) Primary gasification: A fluidized bed gasifier is used (the fluidized bed gasifier and the fixed bed gasifier are transported by a pneumatic conveying system), the gasification temperature is controlled at 850°C, the gasification pressure is controlled at atmospheric pressure, and the gasifying agent is a mixture of air and water vapor, with a volume ratio of air to water vapor of 1:0.75;

[0149] (2) Secondary gasification: A fixed bed gasifier is used, the gasification temperature is controlled at 1100°C, the gasification pressure is controlled at normal pressure, and water vapor is used as the gasifying agent.

[0150] Step 5. Gas Purification: The combustible gas generated by the gasifier is transported to the gas purification system, where it undergoes cyclone dust removal, water washing, desulfurization, and denitrification processes to remove impurities such as dust, tar, and acidic gases, resulting in clean combustible gas. The specific steps are as follows:

[0151] (1) Cyclone dust removal: removes large dust particles in the gas;

[0152] (2) Water scrubber: removes tar and some acid gases from the gas;

[0153] (3) Desulfurization tower: uses alkaline solution absorption method to remove SO2 in the gas;

[0154] (4) Denitrification tower: uses selective catalytic reduction to remove NO in the gas x .

[0155] Example 2

[0156] This embodiment provides a method for integrated pretreatment and gasification of domestic waste, which specifically includes the following steps:

[0157] Step 1. Crushing and sorting: Crushing the domestic waste. The crushed waste is separated into recyclable materials such as metal, glass, and plastic, as well as inorganic materials such as bricks, stones, and ceramics through magnetic separation, air separation, and screening, to obtain organic waste with uniform particle size. The specific steps are as follows:

[0158] (1) Primary crushing: Use a shear crusher to crush the garbage to a particle size of less than 100 mm;

[0159] (2) Primary separation: using magnetic separation and air separation to separate metals and light plastics;

[0160] (3) Secondary crushing: Using a hammer crusher, the garbage is further crushed to a particle size of less than 30 mm;

[0161] (4) Secondary sorting: Screening is used to separate inorganic materials such as bricks, stones, and ceramics to obtain organic waste with uniform particle size.

[0162] Step 2. Carbonization: The crushed and sorted organic waste is transported to the carbonization reactor. The carbonization reactor uses a rotary carbonization furnace with an internal stirring device to ensure uniform heating of the waste. The reaction atmosphere is an oxygen-deficient atmosphere, the carbonization temperature is controlled at 300°C, the carbonization time is controlled at 60 minutes, and the carbonization atmosphere is carbon dioxide.

[0163] Step 3. Air flow conveying and dynamic mixing: A pneumatic conveying device is used to convey the carbonized garbage. The conveying gas is the high-temperature flue gas generated by the gasification furnace (temperature is 600-800℃), the conveying speed is 10m / s, and a multi-stage static mixing unit (spiral blades) is set in the conveying pipeline to enhance the mixing effect of the garbage and the gasifying agent.

[0164] Step 4. Multi-stage gasification: The mixed garbage and gasifying agent are transported to a two-stage gasifier for primary and secondary gasification, respectively. The specific steps are as follows:

[0165] (1) Primary gasification: A fluidized bed gasifier is used (the fluidized bed gasifier and the fixed bed gasifier are transported by a pneumatic conveying system), the gasification temperature is controlled at 800°C, the gasification pressure is controlled at normal pressure, and the gasifying agent is a mixture of air and water vapor, with a volume ratio of air to water vapor of 1:0.5;

[0166] (2) Secondary gasification: A fixed bed gasifier is used, the gasification temperature is controlled at 1200°C, the gasification pressure is controlled at normal pressure, and water vapor is used as the gasifying agent.

[0167] Step 5. Gas Purification: The combustible gas generated by the gasifier is transported to the gas purification system, where it undergoes cyclone dust removal, water washing, desulfurization, and denitrification processes to remove impurities such as dust, tar, and acidic gases, resulting in clean combustible gas. The specific steps are as follows:

[0168] (1) Cyclone dust removal: removes large dust particles in the gas;

[0169] (2) Water scrubber: removes tar and some acid gases from the gas;

[0170] (3) Desulfurization tower: uses alkaline solution absorption method to remove SO2 in the gas;

[0171] (4) Denitrification tower: uses selective catalytic reduction to remove NO in the gas x .

[0172] Example 3

[0173] This embodiment provides a method for integrated pretreatment and gasification of domestic waste, which specifically includes the following steps:

[0174] Step 1. Crushing and sorting: Crushing the domestic waste. The crushed waste is separated into recyclable materials such as metal, glass, and plastic, as well as inorganic materials such as bricks, stones, and ceramics through magnetic separation, air separation, and screening, to obtain organic waste with uniform particle size. The specific steps are as follows:

[0175] (1) Primary crushing: Use a shear crusher to crush the garbage to a particle size of less than 100 mm;

[0176] (2) Primary separation: using magnetic separation and air separation to separate metals and light plastics;

[0177] (3) Secondary crushing: Using a hammer crusher, the garbage is further crushed to a particle size of less than 30 mm;

[0178] (4) Secondary sorting: Screening is used to separate inorganic materials such as bricks, stones, and ceramics to obtain organic waste with uniform particle size.

[0179] Step 2. Carbonization: The crushed and sorted organic waste is transported to the carbonization reactor. The carbonization reactor uses a rotary carbonization furnace with an internal stirring device to ensure uniform heating of the waste. The reaction atmosphere is an oxygen-deficient atmosphere, the carbonization temperature is controlled at 500°C, the carbonization time is controlled at 30 minutes, and the carbonization atmosphere is nitrogen.

[0180] Step 3. Air flow conveying and dynamic mixing: A pneumatic conveying device is used to convey the carbonized garbage. The conveying gas is the high-temperature flue gas generated by the gasification furnace (temperature is 600-800℃), the conveying speed is 20m / s, and a multi-stage static mixing unit (spiral blades) is set in the conveying pipeline to enhance the mixing effect of the garbage and the gasifying agent.

[0181] Step 4. Multi-stage gasification: The mixed garbage and gasifying agent are transported to a two-stage gasifier for primary and secondary gasification, respectively. The specific steps are as follows:

[0182] (1) Primary gasification: A fluidized bed gasifier is used (the fluidized bed gasifier and the fixed bed gasifier are transported by a pneumatic conveying system), the gasification temperature is controlled at 900°C, the gasification pressure is controlled at atmospheric pressure, and the gasifying agent is a mixture of air and water vapor, with a volume ratio of air to water vapor of 1:1;

[0183] (2) Secondary gasification: A fixed bed gasifier is used, the gasification temperature is controlled at 1000°C, the gasification pressure is controlled at normal pressure, and water vapor is used as the gasifying agent.

[0184] Step 5. Gas Purification: The combustible gas generated by the gasifier is transported to the gas purification system, where it undergoes cyclone dust removal, water washing, desulfurization, and denitrification processes to remove impurities such as dust, tar, and acidic gases, resulting in clean combustible gas. The specific steps are as follows:

[0185] (1) Cyclone dust removal: removes large dust particles in the gas;

[0186] (2) Water scrubber: removes tar and some acid gases from the gas;

[0187] (3) Desulfurization tower: uses alkaline solution absorption method to remove SO2 in the gas;

[0188] (4) Denitrification tower: uses selective catalytic reduction to remove NO from the gas x .

[0189] Example 4

[0190] This embodiment provides an integrated method for pretreatment and gasification of domestic waste. The difference from Example 1 is that in step 2, the carbonization time is 25 minutes, and the remaining steps are consistent with Example 1.

[0191] Example 5

[0192] This embodiment provides an integrated method for pretreatment and gasification of domestic waste. The difference from Example 1 is that in step 2, the carbonization time is 65 minutes, and the remaining steps are consistent with Example 1.

[0193] Example 6

[0194] This embodiment provides an integrated method for pretreatment and gasification of domestic waste. The difference from Example 1 is that in step 4, only one-stage gasification is performed, and the remaining steps are consistent with Example 1.

[0195] Example 7

[0196] This embodiment provides an integrated method for pretreatment and gasification of domestic waste. The difference from Example 1 is that in step 4, only secondary gasification is performed, and the remaining steps are consistent with Example 1.

[0197] Comparative Example 1

[0198] This comparative example provides an integrated method for pretreatment and gasification of domestic waste. The difference from Example 1 is that in step 2, the reaction atmosphere is an aerobic atmosphere, the carbonization temperature is 280°C, and the remaining steps are consistent with Example 1.

[0199] Comparative Example 2

[0200] This comparative example provides an integrated method for pretreatment and gasification of domestic waste. The difference from Example 1 is that in step 2, the reaction atmosphere is an aerobic atmosphere, the carbonization temperature is 520°C, and the remaining steps are consistent with Example 1.

[0201] Comparative Example 3

[0202] This comparative example provides an integrated method for pretreatment and gasification of domestic waste, which differs from Example 1 in that in step 3, the conveying gas is room temperature gas, and the remaining steps are consistent with Example 1.

[0203] Comparative Example 4

[0204] This comparative example provides a method for treating domestic waste. The difference from Example 1 is that pretreatment and gasification are not integrated. The specific process is as follows:

[0205] Step 1. Crushing and sorting: Crushing the domestic waste. The crushed waste is separated into recyclable materials such as metal, glass, and plastic, as well as inorganic materials such as bricks, stones, and ceramics through magnetic separation, air separation, and screening, to obtain organic waste with uniform particle size. The specific steps are as follows:

[0206] (1) Primary crushing: Use a shear crusher to crush the garbage to a particle size of less than 100 mm;

[0207] (2) Primary separation: using magnetic separation and air separation to separate metals and light plastics;

[0208] (3) Secondary crushing: Using a hammer crusher, the garbage is further crushed to a particle size of less than 30 mm;

[0209] (4) Secondary sorting: Screening is used to separate inorganic materials such as bricks, stones, and ceramics to obtain organic waste with uniform particle size.

[0210] Step 2. Carbonization: The crushed and sorted organic waste is transported to the carbonization reactor. The carbonization reactor uses a rotary carbonization furnace with a stirring device inside to ensure that the waste is evenly heated. The reaction atmosphere is an oxygen-deficient atmosphere, the carbonization temperature is controlled at 400°C, the carbonization time is controlled at 45 minutes, and the carbonization atmosphere is nitrogen. The carbon-based materials prepared in various places are stored.

[0211] Step 3. Gasification: The carbon-based materials prepared in various places are transported to the gasification device for multi-stage gasification. The carbon-based materials and gasifying agents are transported to the gasifier separately, and the first-stage gasification and the second-stage gasification are carried out in sequence. The specific steps are as follows:

[0212] (1) Primary gasification: A fluidized bed gasifier is used (the fluidized bed gasifier and the fixed bed gasifier are transported by a pneumatic conveying system), the gasification temperature is controlled at 850°C, the gasification pressure is controlled at atmospheric pressure, and the gasifying agent is a mixture of air and water vapor, with a volume ratio of air to water vapor of 1:0.75;

[0213] (2) Secondary gasification: A fixed bed gasifier is used, the gasification temperature is controlled at 1100°C, the gasification pressure is controlled at normal pressure, and water vapor is used as the gasifying agent.

[0214] Step 4. Gas Purification: The combustible gas generated by the gasifier is transported to the gas purification system, where it undergoes cyclone dust removal, water washing, desulfurization, and denitrification processes to remove impurities such as dust, tar, and acidic gases, resulting in clean combustible gas. The specific steps are as follows:

[0215] (1) Cyclone dust removal: removes large dust particles in the gas;

[0216] (2) Water scrubber: removes tar and some acid gases from the gas;

[0217] (3) Desulfurization tower: uses alkaline solution absorption method to remove SO2 in the gas;

[0218] (4) Denitrification tower: uses selective catalytic reduction to remove NOx from the gas.

[0219] Test Case

[0220] Test samples: The products obtained after treatment in Examples 1-7 and Comparative Examples 1-4 were tested.

[0221] Test Method: Carbon conversion and gasification efficiency were calculated using online material monitoring, gas chromatography (GC), thermogravimetric analysis, and material balance. Hydrogen volume fraction was quantitatively analyzed by gas chromatography (GC). Syngas components were monitored using online gas chromatography (GC). Gas components were separated using a chromatographic column using gas chromatography. The calorific value of the mixed gas was calculated based on the weighted concentrations of each component. Tar production was determined using GC-MS results. Ash glass conversion was determined using a selective dissolution method. Hydrofluoric acid (HF) dissolves the glass phase, leaving a crystalline residue. A 20% HF solution was added to the ash and shaken to dissolve for 2 hours. The residue was filtered, dried, and weighed to calculate the ash glass conversion. The heavy metal solidification rate was tested using inductively coupled plasma mass spectrometry (ICP-MS).

[0222] The test results are shown in Table 1.

[0223] Table 1

[0224]

[0225]

[0226] As shown in Table 1, by adopting the integrated process of pretreatment and gasification of domestic waste of the present invention, the carbon conversion rate can reach 96.21% after the domestic waste is treated. The carbon conversion rate is significantly improved, the gasification efficiency can reach 90%, and the final syngas calorific value can reach up to 14.32MJ / Nm 3 The hydrogen volume fraction can reach 42%, and the tar produced is extremely low, with a minimum of 18.32 mg / Nm 3 The glass conversion rate of ash can reach 98.43%, and the solidification rate of heavy metals is as high as 99.03%. It not only converts domestic waste into synthesis gas to realize the resource utilization of waste, but also achieves breakthroughs in carbon conversion efficiency, gasification efficiency and tar production.

[0227] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for integrating pretreatment and gasification of domestic waste, characterized in that: The following steps are involved: The garbage is pre-treated and gasified in sequence to obtain combustible gas; Wherein, the pretreatment includes carbonization, and the carbonization includes: partially carbonizing the garbage in an oxygen-deficient atmosphere at a temperature of 300-500°C; The carbonized garbage is transported by hot air flow into the gasification process.

2. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: The carbonization time is 30-60 minutes; Preferably, the carbonization is performed under a nitrogen or carbon dioxide atmosphere.

3. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: The conveying speed is 10-20 m / s.

4. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: During the transportation process, the carbonized garbage is mixed with the gasifying agent; Preferably, a plurality of static mixing units are provided in the pipeline used for transportation; Preferably, the static mixing unit comprises helical blades or baffles.

5. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: The gasification process includes primary gasification and secondary gasification performed sequentially; Preferably, the temperature of the primary gasification is 800-900°C; Preferably, the gasifying agent for the primary gasification comprises air and water vapor, and the volume ratio of air to water vapor is 1:0.5-1:1; Preferably, the temperature of the secondary gasification is 1000-1200°C; Preferably, the gasification agent of the secondary gasification includes water vapor.

6. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: The pretreatment also includes crushing and sorting, and the garbage after crushing and sorting enters the carbonization process; Preferably, the crushing and sorting includes primary crushing, primary sorting, secondary crushing and secondary sorting performed in sequence; Preferably, the particle size of the garbage after the first stage of crushing is less than 100 mm; Preferably, the primary separation includes magnetic separation and air separation to separate metals and light plastics in the garbage; Preferably, the particle size of the garbage after the secondary crushing is less than 30 mm; Preferably, the secondary sorting includes screening to separate inorganic matter in the garbage to obtain organic garbage.

7. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: The integrated method for pre-treatment and gasification of domestic waste further includes gas purification, wherein the combustible gas obtained by the gasification treatment is subjected to gas purification to obtain clean combustible gas; After the gasification process, it also includes gas purification process; Preferably, the gas purification treatment includes dust removal, water washing, desulfurization and denitrification performed in sequence; Preferably, cyclone dust removal is used to remove large dust particles in the gas; Preferably, a water scrubber is used to remove tar and some acid gases from the gas; Preferably, a desulfurization tower is used to remove SO2 from the gas; Preferably, a denitrification tower is used to remove NO from the gas. x .

8. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: The integrated method for pre-treatment and gasification of domestic waste further includes a waste heat utilization step, which includes: transporting the high-temperature flue gas generated by the gasification process to a waste heat boiler to generate steam for power generation or heating; Preferably, the steam pressure is 1.0-1.6 MPa and the steam temperature is 300-350°C.

9. The integrated method for pretreatment and gasification of domestic waste according to claim 1, characterized in that: The integrated method for pre-treatment and gasification of domestic waste further includes ash treatment, which includes: subjecting the ash produced by the gasification treatment to high-temperature melting treatment to form a recyclable glass body; Preferably, the melting temperature is 1400-1600° C., and the melting time is 30-60 minutes.

10. Application of the integrated method for pretreatment and gasification of domestic waste according to any one of claims 1 to 9 in waste treatment.

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