Multi-energy supply and collaborative heating method based on carbon recycling

Abstract

The application discloses a multi-energy combined supply and collaborative heat supply method based on carbon recycling, relates to the technical field of organic solid waste resource utilization, and is characterized in that, in the first low-temperature pyrolysis stage, the organic nitrogen in the mixed raw material is released in the form of ammonia gas by taking advantage of the characteristic that nitrogen-containing organic matter is easy to be broken to generate gaseous ammonia in this temperature range, and ammonium fertilizer is prepared by adopting acid liquid absorption through a spray absorption tower, so that the nitrogen element is completely removed from the system before entering the combustion or gasification process, the generation path of fuel nitrogen into the high-temperature zone to be converted into thermal nitrogen oxides is avoided, a complex flue gas denitration device does not need to be arranged at the rear end to realize ultra-low nitrogen emission, meanwhile, the carbon-rich coke obtained after the separation of the nitrogen element enters the second high-temperature gasification furnace for deep conversion, since the raw material does not have the interference of the nitrogen element, the high-temperature crude synthesis gas generated has high purity and few impurities, a subsequent complex ammonia removal and purification process is not needed, and the high-value recovery of the nitrogen element as a fertilizer resource is realized.

Description

Technical Field

[0001] This invention relates to the field of organic solid waste resource utilization technology, specifically a multi-energy co-generation and synergistic heating method based on carbon recycling. Background Technology

[0002] With the coordinated development of resource utilization of multi-source organic solid waste and clean heating technology, it has become a research hotspot in the fields of environmental protection and energy. How to convert these low-grade carbon resources into high-grade heat energy and realize the recycling of carbon elements is of great significance for building a circular economy system and reducing fossil energy consumption. Multi-energy combined heating, as an efficient energy supply mode that can integrate multiple energy forms and realize energy cascade utilization, provides a new technical path for the resource utilization of organic solid waste.

[0003] However, existing technologies for the energy utilization of organic solid waste still have significant shortcomings: First, when dealing with kitchen waste and municipal sludge with high nitrogen content, traditional direct incineration or single gasification processes cannot effectively remove nitrogen from the fuel. This nitrogen is easily converted into thermal nitrogen oxides under high temperature conditions, resulting in high costs for subsequent flue gas denitrification and difficulty in meeting increasingly stringent environmental emission standards.

[0004] Secondly, existing technologies typically mix carbon and nitrogen elements, which not only results in nitrogen-containing impurities such as ammonia and hydrogen cyanide in the generated syngas, reducing the calorific value and utilization quality of the fuel, but also wastes the resource potential of nitrogen as a high-value chemical raw material.

[0005] In addition, existing solid waste treatment systems and heating networks are often independent of each other, lacking deep energy coupling and material recycling, resulting in low overall system energy efficiency and failing to fully leverage the advantages of multi-energy complementarity.

[0006] Therefore, there is an urgent need to develop a synergistic heating method that can achieve targeted separation and cascade conversion of carbon and nitrogen elements at the source, and deeply integrate the solid waste treatment process with a multi-energy combined heat and power system. This method should be able to synergistically treat the different characteristics of multi-source organic solid waste, efficiently recovering heat energy while achieving high-quality carbon conversion and high-value utilization of nitrogen, thus constructing a complete carbon recycling system. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multi-energy cogeneration and synergistic heating method based on carbon recycling. This method utilizes the characteristic that nitrogen-containing organic matter easily breaks down to generate gaseous ammonia in the primary low-temperature pyrolysis stage. Organic nitrogen in the mixed raw materials is released directionally as ammonia gas, and then absorbed by acid in a spray absorption tower to produce ammonium fertilizer. This completely removes nitrogen from the system before it enters the combustion or gasification process, avoiding the path of fuel nitrogen entering the high-temperature zone and converting into thermal nitrogen oxides. Ultra-low nitrogen emissions can be achieved without the need for complex flue gas denitrification devices at the back end. Simultaneously, the carbon-rich coke obtained after nitrogen separation enters the secondary high-temperature gasifier for deep conversion. Since there is no nitrogen interference in the raw materials, the resulting high-temperature crude syngas has high purity and few impurities, eliminating the need for complex subsequent ammonia removal and purification processes. This solves the problem of high costs in nitrogen oxide pollution control and achieves high-value recovery of nitrogen as a fertilizer resource.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a multi-energy combined heat and power (CHP) co-generation method based on carbon recycling, the specific steps of which are as follows: S100, Pretreatment of multi-source organic solid waste and conditioning of carbon-nitrogen ratio: The received organic solid waste is crushed, dehydrated and homogenized to form a mixed raw material. The carbon-nitrogen ratio of the mixed raw material is monitored and controlled in real time. When the monitored carbon-nitrogen ratio is lower than the preset threshold, a high-carbon additive is added to the mixed raw material for conditioning, so that the carbon-nitrogen ratio of the conditioned mixed raw material is within the preset pyrolysis reaction range. S200, First-stage low-temperature pyrolysis and directional separation of nitrogen: The conditioned mixed raw material is fed into the first-stage low-temperature pyrolysis reactor and pyrolyzed under anaerobic conditions. The organic nitrogen in the conditioned mixed raw material is released in the form of gaseous ammonia. At the same time, ammonia-containing pyrolysis gas and carbon-rich coke are obtained. The ammonia-containing pyrolysis gas is introduced into a spray absorption tower and absorbed by acid to generate an ammonium salt solution. After concentration and crystallization, ammonium fertilizer is obtained, realizing the resource recovery of nitrogen. The purified deammonium gas after ammonia removal is stored in a gas storage tank for later use. S300, Second-stage high-temperature gasification and carbon element directional conversion: The carbon-rich coke separated from S200 is sent to the second-stage high-temperature gasifier, where steam is used as the gasifying agent to carry out a high-temperature gasification reaction, so that the fixed carbon in the carbon-rich coke is converted into high-temperature crude syngas mainly composed of carbon monoxide and hydrogen. The generated high-temperature crude syngas is introduced into the waste heat recovery unit for heat energy extraction. S400 Syngas Purification and Upgrading: The crude syngas after waste heat recovery is sequentially processed through dust removal, filtration and catalytic reforming to remove dust, tar and sulfide impurities, and obtain clean hydrogen-rich syngas. S500, Multi-energy Co-generation and Coordinated Heating: The clean hydrogen-rich syngas is distributed to the multi-energy co-generation unit to perform two energy supply methods: the first part of the syngas is sent to the gas-fired power generation equipment for power generation, and the second part of the syngas is directly used for heating and as fuel for gas-fired boilers for peak-shaving heating. S600, closed-loop carbon recycling: captures carbon dioxide from the flue gas produced by the combustion of gas-fired power generation equipment and gas-fired boilers in S500, and performs carbon recycling.

[0009] Furthermore, the various organic solid wastes in S100 include two or more of the following: agricultural straw, municipal kitchen waste, municipal sludge, organic waste residue from food processing, and livestock and poultry manure. The high-carbon additive is selected from one or more of sawdust, rice husks, or biochar produced by the S300 reaction process.

[0010] Furthermore, in S100, the carbon-to-nitrogen ratio adjustment process is as follows: The carbon-nitrogen ratio of the mixed raw materials, monitored in real time by an online elemental analyzer, was: The preset lower limit threshold for the carbon-to-nitrogen ratio in the pyrolysis reaction range is... The upper limit threshold is ; when At that time, according to Calculate the required mass of high-carbon additives. ,in, This refers to the total mass of the mixed raw materials in the current batch. Set a target carbon-to-nitrogen ratio value, which is [value to be filled in]. , The mass fraction of nitrogen in the mixed raw materials is determined in real time by an online elemental analyzer. This refers to the mass fraction of carbon in the high-carbon additive. This refers to the mass fraction of nitrogen in the high-carbon additive. By calculating and controlling the amount of additives added, the carbon-nitrogen ratio of the regulated mixed raw materials is achieved. Stabilized within the preset pyrolysis reaction range Inside.

[0011] Furthermore, the primary low-temperature pyrolysis reactor in S200 adopts an externally heated rotary kiln, and the reaction temperature is controlled at 350℃-550℃; The acid solution used in the spray absorption tower is a phosphoric acid solution or a sulfuric acid solution, and the generated ammonium salt is an ammonium phosphate salt or an ammonium sulfate salt. The purified gas consists of methane, carbon monoxide, and hydrogen.

[0012] Furthermore, the secondary high-temperature gasifier in S300 is one of a circulating fluidized bed gasifier, an entrained flow gasifier, or a fixed bed gasifier, and the gasification temperature is controlled at 900℃-1200℃; The high-temperature crude syngas has a temperature of 900℃-1000℃ before entering the waste heat recovery unit. After heat recovery, it generates high-pressure steam of over 4.2MPa for power generation and heating.

[0013] Furthermore, the catalytic reforming process in S400 is as follows: the purified desorbed gas from S200 is used as a reforming agent to carry out a catalytic reforming reaction with the high-temperature crude syngas. By adjusting the amount of purified desorbed gas introduced, the molar ratio of hydrogen to carbon monoxide in the reformed syngas is controlled to meet the energy demand of the downstream combined heat and power unit.

[0014] Furthermore, when S500 is supplying energy, it collects waste heat from the cylinder liner water and flue gas of the gas-fired power generation equipment, as well as the heat energy extracted by the waste heat recovery unit in S300. This waste heat is then extracted in stages using an absorption heat pump, forming a multi-energy complementary synergistic heating system with the peak-shaving heating of the gas-fired boiler. The real-time control process of this synergistic heating is as follows: Real-time monitoring of heat load demand in heating networks Waste heat recovery from gas-fired power generation equipment in combined energy supply units The recoverable waste heat includes cylinder liner water waste heat and flue gas waste heat; Real-time monitoring of the coefficient of performance (COP) of absorption heat pumps ,according to Determine the heat supply from the second portion of syngas used for direct heating and peak shaving of gas-fired boilers. ,in, The heat recovery efficiency of the waste heat recovery unit, with a value range of [value range missing]. ; When calculated When the waste heat recovery of the gas-fired power generation equipment has met the heat load requirements, the second part of the syngas is stored or used for power generation. When calculated At that time, according to The flow rate of the second part of the syngas entering the gas boiler is controlled to achieve a dynamic balance between supply and demand.

[0015] Furthermore, the carbon recycling process in S600 is as follows: a portion of the captured carbon dioxide is recycled as a gasifying agent in the secondary high-temperature gasification process of S300, and another portion of the carbon dioxide reacts with the ammonia recovered in S200 to synthesize carbon-containing chemicals.

[0016] Furthermore, in S600, the captured carbon dioxide is recycled for the secondary high-temperature gasification process of S300 by mixing carbon dioxide with a gasifying agent and then introducing the mixture into the secondary high-temperature gasifier to participate in the Bourdon reaction. It is used to regulate the reaction temperature in the gasifier and improve the carbon conversion rate; The carbon-containing chemical is urea or ammonium bicarbonate.

[0017] Compared with existing technologies, this multi-energy co-generation and coordinated heating method based on carbon recycling has the following advantages: This invention utilizes the characteristic that nitrogen-containing organic matter easily breaks down to generate gaseous ammonia in the primary low-temperature pyrolysis stage. Organic nitrogen in the mixed raw materials is released directionally as ammonia gas, and then absorbed by acid in a spray absorption tower to produce ammonium fertilizer. This completely removes nitrogen from the system before it enters the combustion or gasification process, avoiding the path of fuel nitrogen entering the high-temperature zone and converting into thermal nitrogen oxides. Ultra-low nitrogen emissions can be achieved without the need for complex flue gas denitrification devices at the back end. Simultaneously, the carbon-rich coke obtained after nitrogen separation enters the secondary high-temperature gasifier for deep conversion. Since there is no nitrogen interference in the raw materials, the resulting high-temperature crude syngas has high purity and few impurities, eliminating the need for subsequent complex ammonia removal and purification processes. This solves the problem of high costs in nitrogen oxide pollution control and achieves high-value recovery of nitrogen as a fertilizer resource.

[0018] This invention employs a two-stage reaction coupling method of low-temperature pyrolysis and high-temperature gasification. In the low-temperature stage, organic nitrogen is released in a directional manner as gaseous ammonia and recovered as ammonium salt products. In the high-temperature stage, carbon-rich coke is efficiently converted into high-quality syngas, achieving carbon and nitrogen element separation, conversion, and resource utilization. This method avoids the emission of nitrogen elements as pollutants, while improving the carbon conversion rate of coke and the quality of syngas, providing stable fuel for subsequent power generation and heating. Through in-situ carbon and nitrogen separation, it solves the problems of heavy nitrogen pollution and insufficient carbon utilization in traditional processes, realizing the high-value utilization of all components of organic solid waste and improving the environmental friendliness and economy of the system.

[0019] In the process of multi-energy combined heat and power supply, this invention performs cascade recovery of waste heat from power generation and high-temperature syngas, and enhances the utilization value of waste heat through absorption heat pumps. At the same time, it establishes real-time control based on heat load demand, prioritizing the use of waste heat to meet heating demand, and supplementing the insufficient portion with syngas combustion for peak shaving. This control method achieves dynamic matching of heat supply and demand, avoids energy redundancy and waste, and significantly improves the overall energy efficiency of the system. Part of the captured carbon dioxide is recycled for gasification reaction, forming an internal carbon cycle, reducing net emissions, and achieving synergistic effects of efficient energy utilization and carbon emission reduction.

[0020] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0022] Figure 1 This is a flowchart of a multi-energy combined heat and power (CHP) co-generation method based on carbon recycling in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the steps of a multi-energy combined heat and power (CHP) co-generation method based on carbon recycling. Figure 3 This is a flowchart illustrating the steps of purifying and upgrading crude syngas in an embodiment of the present invention. Detailed Implementation

[0023] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] To address the shortcomings of existing organic solid waste energy utilization technologies, such as high nitrogen oxide pollution control costs due to carbon-nitrogen co-processing, nitrogen resource waste, and low energy coupling between solid waste treatment systems and heating networks, this invention provides a multi-energy co-generation and synergistic heating method based on carbon recycling. This method aims to achieve targeted separation and cascade conversion of carbon and nitrogen in multi-source organic solid waste through a two-stage reaction coupling of primary low-temperature pyrolysis and secondary high-temperature gasification. This cuts off the path from fuel nitrogen to thermal nitrogen oxides at the source and recovers nitrogen in the form of ammonium salts. Simultaneously, the separated carbon-rich coke is efficiently converted into high-quality syngas, which is then used for power generation and synergistic heating through a multi-energy co-generation unit. The carbon dioxide produced during combustion is captured and recycled. This constructs a complete technological system encompassing solid waste pretreatment, carbon-nitrogen separation and conversion, syngas upgrading, multi-energy synergistic power supply, and a closed-loop carbon cycle. This solves the problems of heavy nitrogen pollution, insufficient carbon utilization, and low system energy efficiency in traditional processes, achieving high-value, clean, and low-carbon utilization of organic solid waste.

[0025] This invention is primarily applied in urban wastewater treatment plants, organic solid waste treatment centers, and industrial parks. Its core focus is addressing the need for the collaborative treatment and energy utilization of multi-source organic solid waste, such as municipal sludge, kitchen waste, and agricultural straw. Traditional solid waste disposal methods, such as landfill, incineration, or single gasification processes, suffer from problems including large land occupation, high risk of secondary pollution, and low energy recovery efficiency. Especially for kitchen waste and municipal sludge with high nitrogen content, direct incineration or gasification leads to a large conversion of fuel nitrogen into nitrogen oxides at high temperatures, polluting the environment, requiring expensive flue gas denitrification equipment, and failing to effectively recover nitrogen, resulting in resource waste. Simultaneously, existing solid waste treatment systems lack deep integration with district heating networks, failing to utilize waste heat generated during treatment in a cascade manner, resulting in low overall system energy efficiency. This invention constructs a multi-energy co-generation and co-generation heating system based on carbon recycling, closely integrating the solid waste treatment process with clean energy needs, achieving multiple objectives of solid waste resource utilization, clean energy supply, and minimized carbon emissions.

[0026] Specifically, such as Figure 2 As shown, a multi-energy co-generation and coordinated heating method based on carbon recycling is described, which includes the following steps: S100, Pretreatment of multi-source organic solid waste and conditioning of carbon-nitrogen ratio: The received organic solid waste is crushed, dehydrated and homogenized to form a mixed raw material. The carbon-nitrogen ratio of the mixed raw material is monitored and controlled in real time. When the monitored carbon-nitrogen ratio is lower than the preset threshold, a high-carbon additive is added to the mixed raw material for conditioning, so that the carbon-nitrogen ratio of the conditioned mixed raw material is within the preset pyrolysis reaction range. S200, First-stage low-temperature pyrolysis and nitrogen element directional separation: The conditioned mixed raw material is fed into the first-stage low-temperature pyrolysis reactor and pyrolyzes at low temperature under anaerobic conditions, so that the organic nitrogen in the conditioned mixed raw material is released in the form of gaseous ammonia. At the same time, ammonia-containing pyrolysis gas and carbon-rich coke are obtained. The ammonia-containing pyrolysis gas is introduced into the spray absorption tower and absorbed by acid to generate ammonium salt solution. After concentration and crystallization, ammonium fertilizer is obtained. The purified deammoniation gas after ammonia removal is stored in the gas storage tank for later use. S300, Second-stage high-temperature gasification and carbon element directional conversion: The carbon-rich coke separated from S200 is sent to the second-stage high-temperature gasifier, where steam is used as the gasifying agent to carry out a high-temperature gasification reaction, so that the fixed carbon in the carbon-rich coke is converted into high-temperature crude syngas mainly composed of carbon monoxide and hydrogen. The generated high-temperature crude syngas is introduced into the waste heat recovery unit for heat energy extraction. S400 Syngas Purification and Upgrading: The crude syngas after waste heat recovery is sequentially processed through dust removal, filtration and catalytic reforming to remove dust, tar and sulfide impurities, and obtain clean hydrogen-rich syngas. S500, multi-energy co-generation and coordinated heating: Clean hydrogen-rich syngas is distributed to the multi-energy co-generation unit to perform two energy supply methods: the first part of the syngas is sent to the gas-fired power generation equipment for power generation, and the second part of the syngas is directly used for heating and as fuel for gas-fired boilers for peak-shaving heating. S600, closed-loop carbon recycling: captures carbon dioxide from the flue gas produced by the combustion of gas-fired power generation equipment and gas-fired boilers in S500, and performs carbon recycling.

[0027] The following will combine, for example, Figure 1 The flowchart shown illustrates in detail the multi-energy co-generation and coordinated heating method based on carbon recycling disclosed in this invention: In the specific implementation process, the first step is to receive and pre-treat multi-source organic solid waste. In this embodiment, various organic solid wastes include municipal sludge, kitchen waste, agricultural straw, and food processing waste residue, which are mixed in a mass ratio of 3:3:3:1. After receiving the solid waste, it first enters a crusher to crush large pieces of material to a particle size of less than 20mm, which facilitates subsequent homogenization and heat transfer in the reaction. Then, it enters a screw press dewatering machine for mechanical dewatering, controlling the moisture content of the mixed raw materials to below 60%, thereby reducing the energy consumption of the subsequent pyrolysis process. The dewatered material enters a homogenization mixing chamber, where the strong mixing action of the twin-shaft stirring blades ensures that solid wastes from different sources and with different properties are fully mixed and homogeneous, forming a relatively stable mixed raw material.

[0028] Before the mixed raw materials enter the primary low-temperature pyrolysis reactor, the carbon-nitrogen ratio is monitored and precisely controlled in real time. In this embodiment, an online elemental analyzer is installed on the outlet pipe of the homogenization mixing chamber to measure the carbon mass fraction, nitrogen mass fraction, and current carbon-nitrogen ratio of the mixed raw materials in real time. The preset lower limit threshold for the carbon-to-nitrogen ratio in the pyrolysis reaction range is... The upper limit threshold is Within this range, the organic nitrogen in the mixed raw materials can be released to the maximum extent in the form of gaseous ammonia during the low-temperature pyrolysis stage, while the carbon elements are mostly retained in the coke.

[0029] When the online elemental analyzer monitors the carbon-nitrogen ratio of the current batch of mixed raw materials Below the lower threshold This indicates that the nitrogen content in the raw material is too high, requiring the addition of a high-carbon additive for conditioning. The high-carbon additive is selected from sawdust (approximately 48% carbon and 0.3% nitrogen by mass). The required mass of the high-carbon additive is calculated based on the mass balance formula. Calculate the required mass of high-carbon additives. ,in, This refers to the total mass of the mixed raw materials in the current batch. Set a target carbon-to-nitrogen ratio value, which is [value to be filled in]. , The mass fraction of nitrogen in the mixed raw materials is determined in real time by an online elemental analyzer. This refers to the mass fraction of carbon in the high-carbon additive. Based on the calculation results, the control system automatically controls the feeder of the high-carbon additive silo to accurately add wood chips into the homogenization mixing silo, and through the continuous mixing of the stirring blades, the additive and raw materials are fully integrated.

[0030] If the monitored value Above the upper limit threshold In this case, there is no need to add high-carbon additives, or to add appropriate raw materials with high nitrogen content for reverse conditioning.

[0031] When the monitored value is within the range If the raw material is not properly separated, it will proceed directly to the next process, ensuring that the raw material entering the first-stage low-temperature pyrolysis reactor is always in the optimal denitrification reaction window, laying the foundation for the efficient separation of nitrogen in the subsequent process.

[0032] After the carbon-nitrogen ratio is adjusted, the mixed raw materials are fed into the primary low-temperature pyrolysis reactor via a closed screw conveyor. In this embodiment, the primary low-temperature pyrolysis reactor is an externally heated rotary kiln with an adjustable rotation speed of 0.5-5 rpm and a residence time controlled at 45-60 minutes. The reactor uses indirect electric heating, transferring heat to the kiln interior through heating elements on the outer wall of the kiln. This avoids direct contact between flue gas and raw materials, ensuring the purity of the pyrolysis atmosphere. The reaction temperature is controlled at 450℃±20℃, and a slight negative pressure is maintained inside the kiln, with the pressure controlled between -50Pa and -100Pa. This ensures timely discharge of gaseous products and prevents external air from penetrating, maintaining an oxygen-free environment.

[0033] Under low-temperature pyrolysis conditions of 450℃, the organic nitrogen compounds in the mixed raw materials undergo chain-breaking decomposition, directionally transforming into gaseous ammonia (NH3). This gas is discharged from the kiln tail along with the pyrolysis carrier gas (a small amount of non-condensable gas generated during the pyrolysis process), forming ammonia-containing pyrolysis gas. Simultaneously, most of the carbon elements in the raw materials remain in the solid products, forming loosely structured, porous, carbon-rich coke, which is discharged from the kiln head. This achieves a physical separation of carbon and nitrogen elements, allowing nitrogen to enter the gas phase while carbon remains in the solid phase.

[0034] The ammonia-containing pyrolysis gas discharged from the primary low-temperature pyrolysis reactor first enters a cyclone dust collector to remove the small amount of fine particulate dust entrained therein. Then, it enters a spray absorption tower for nitrogen recovery. In this embodiment, the spray absorption tower adopts a three-stage counter-current spray structure, internally filled with polypropylene Pall ring packing to increase the gas-liquid contact area. The absorbent is a 20% (w / w) phosphoric acid solution (H3PO4), sprayed from the top of the tower, contacting the ammonia-containing pyrolysis gas flowing upwards in a counter-current manner, resulting in a chemical reaction: 3NH3 + H3PO4 → (NH4)3PO4, generating an ammonium phosphate solution. After the gas exiting the absorption tower passes through a demister to remove entrained droplets, the purified deammoniation gas is obtained, whose main components are methane (CH4), carbon monoxide (CO), and hydrogen (H2), with a calorific value of 12-15 MJ / m³. 3 The solution is temporarily stored in a gas storage tank for use in subsequent catalytic reforming processes. The ammonium phosphate solution discharged from the bottom of the absorption tower enters a triple-effect evaporation, concentration, and crystallization system. After concentration, cooling crystallization, centrifugal separation, and drying, solid ammonium phosphate compound fertilizer products are obtained, realizing the high-value resource recovery of nitrogen.

[0035] After nitrogen separation, the carbon-rich coke discharged from the primary low-temperature pyrolysis reactor is cooled to below 80°C using a water-cooled spiral cooler before entering the coke storage silo. This carbon-rich coke has a fixed carbon content of 60-70%, volatile matter content below 10%, and ash content of 20-25%. The carbon-rich coke is then fed into the secondary high-temperature gasifier via a screw feeder. In this embodiment, the secondary high-temperature gasifier is a circulating fluidized bed gasifier using steam as the gasifying agent. The steam temperature is controlled at 300-400°C and the pressure at 0.8-1.0 MPa, injected from the bottom distribution plate to fluidize the coke particles within the furnace. The gasification reaction temperature is controlled at 1050°C ± 50°C. Under these high-temperature conditions, the fixed carbon in the carbon-rich coke undergoes a strong gasification reaction with the steam. The main reactions include: C + H₂O → CO + H₂ (Water-gas reaction, endothermic); C + 2H₂O → CO₂ + 2H₂ (water-gas shift reaction); CO + H₂O → CO₂ + H₂ (Water-gas shift reaction, reversible); Meanwhile, the residual volatiles in the coke are further cracked and transformed, eventually generating high-temperature crude syngas mainly composed of CO and H2. A small amount of unreacted coke particles and ash are carried out by the airflow, separated by a high-temperature cyclone separator, and returned to the bottom of the furnace through a return feeder to continue participating in the reaction, realizing the cyclical transformation of carbon and improving the overall carbon conversion rate.

[0036] The high-temperature crude syngas discharged from the top of the circulating fluidized bed gasifier, with a temperature range of 900℃-1000℃, first enters the waste heat recovery unit. The waste heat recovery unit adopts a radiant + convection waste heat boiler structure. The high-temperature crude syngas first enters the radiant cooling chamber, where it is cooled to about 650℃ through radiant heat exchange with water-cooled walls. Then it enters the convection tube bundle, where it undergoes forced convection heat exchange with the boiler feedwater, further cooling it to below 200℃. At the same time, high-pressure superheated steam at 4.2MPa and 450℃ is produced as a byproduct. Part of this high-pressure steam can be used to drive a steam turbine for power generation or as industrial steam for external supply. The other part can be de-cooled and depressurized to serve as a source of gasification agent, achieving efficient cascade recovery of heat energy.

[0037] like Figure 3 As shown, the steps for syngas purification and upgrading after waste heat recovery (temperature 180-200℃) are as follows: The gas enters a baghouse dust collector, where fine dust particles are removed, reducing the dust content of the syngas to below 10 mg / Nm³. 3 ; The gas enters the tar cracking tower, which is filled with a nickel-based catalyst. Under the conditions of 800-850℃, the tar components in the syngas are catalytically cracked into small molecule combustible gases, while some sulfides are removed. The hydrogen sulfide (H2S) enters the desulfurization tower and is treated with zinc oxide desulfurizing agent to remove hydrogen sulfide (H2S) to below 1 ppm at 350-400℃. After dust removal, tar cracking, and desulfurization, the syngas contains some methane and a small amount of heavy hydrocarbons. Catalytic reforming is used to adjust its hydrogen-to-carbon ratio to meet the needs of downstream gas-fired power generation equipment.

[0038] In this embodiment, the catalytic reforming process uses the purified gas (mainly composed of CH4, CO, and H2) temporarily stored in the gas storage tank of S200 after ammonia removal as a reforming agent. It is mixed with the purified crude syngas and then fed into the reforming reactor. The reforming reactor is filled with a nickel-based reforming catalyst, and the reaction temperature is controlled at 850-900℃. The main reactions that occur are: CH4 + CO2 → 2CO + 2H2 (dry reforming) and CH4 + H2O → CO + 3H2 (wet reforming, utilizing residual water vapor in the syngas). By adjusting the amount of purified gas introduced, the molar ratio (hydrogen-carbon ratio) of H2 to CO in the reformed syngas is controlled to obtain clean hydrogen-rich syngas, which is then fed into the multi-energy cogeneration unit.

[0039] After the clean, hydrogen-rich syngas enters the combined energy supply unit, it is distributed according to energy supply and demand. The first part, accounting for 60-70% of the total syngas, is sent to a gas-fired internal combustion generator set for power generation; the second part, accounting for 30-40% of the total syngas, is used for direct heating and as fuel for peak-shaving heating in gas-fired boilers.

[0040] During the energy supply process, various types of waste heat are recovered and utilized in a tiered manner: The waste heat from the cylinder liner water of the gas generator set, the waste heat from the generator set flue gas, and the high-pressure steam heat energy extracted by the waste heat recovery unit in the S300 are collected. These medium and low temperature waste heats are uniformly introduced into the absorption heat pump for cascade extraction. After the waste heat quality is improved, it is used for external heating. At the same time, the gas boiler serves as a peak-shaving heat source to supplement heating during peak heat load periods or when waste heat is insufficient, forming a multi-energy complementary and coordinated heating pattern.

[0041] To achieve precise control of heating supply and dynamic balance between supply and demand, a real-time control mechanism based on heat load demand is established. The specific control process is as follows: The heat load demand of the heating network is monitored in real time by using calorimeters and temperature and pressure sensors installed on the heating network. Simultaneously, the operating conditions of the gas generator sets in the combined energy supply unit are monitored, and the recoverable waste heat is calculated in real time based on their power generation and efficiency curves. The recoverable waste heat includes waste heat from the cylinder liner water (approximately 25-30% of the total input heat energy) and waste heat from the flue gas (approximately 30-35% of the total input heat energy). The control system of the absorption heat pump monitors its coefficient of performance (COP) in real time. Heat recovery efficiency of waste heat recovery unit The amount of heat required by the syngas in the second part is calculated based on the energy balance formula. This formula subtracts the effective waste heat that the waste heat recovery unit can actually extract and supply to the absorption heat pump from the total heat load demand. Multiplying this by the heat pump's coefficient of performance gives the waste heat supply capacity. Subtracting the waste heat supply capacity from the total demand gives the amount of heat that needs to be supplied directly from the second part of the syngas and supplemented by peak shaving from the gas boiler.

[0042] When calculated When the waste heat recovery of the gas generator set is sufficient to meet the current heat load demand, there is no need to start the gas boiler. The second part of the syngas is switched to the gas storage equipment for storage through the regulating valve, or used for supplementary power generation by other generator sets.

[0043] When calculated When this occurs, it indicates that the waste heat supply is insufficient, and it is necessary to start the gas boiler for peak-shaving and heat supplementation. The value automatically adjusts the flow control valve of the second part of the syngas entering the gas boiler, so that the boiler burner outputs the corresponding thermal power, achieving a dynamic balance between the supply and demand of heat energy.

[0044] While achieving efficient energy utilization, this invention also constructs a closed-loop carbon recycling system. In the S500, the flue gas (CO2, N2, and small amounts of O2 and H2O) generated by the gas generator set and gas boiler combustion first enters the flue gas purification system. After denitrification (SCR, selective catalytic reduction) and dust removal (bag filter), carbon dioxide is captured. In this embodiment, carbon dioxide capture adopts a chemical absorption method, using monoethanolamine (MEA) solution as the absorbent. It comes into countercurrent contact with the flue gas in the absorption tower, selectively absorbing CO2. The rich absorbent solution enters the regeneration tower for heating and desorption to release high-purity CO2 gas (purity ≥99.5%), which is then compressed to 2.5 MPa and temporarily stored in a CO2 storage tank.

[0045] The captured carbon dioxide undergoes two recycling pathways: The first part, comprising 30-40% of the total captured carbon dioxide, is used as a gasifying agent. This mixture is then combined with steam introduced from the S300 and fed into the bottom of the secondary high-temperature gasifier. Inside the gasifier, CO2 reacts with coke in a Bourdelle reaction: C + CO2 → 2CO. This endothermic reaction effectively regulates the reaction temperature within the gasifier, preventing localized overheating. Simultaneously, the presence of CO2 promotes further carbon conversion, increasing the carbon conversion rate of coke and the yield of syngas. By adjusting the ratio of CO2 to steam, the reaction atmosphere and syngas composition within the gasifier can be controlled.

[0046] The second part, accounting for 60-70% of the total captured carbon dioxide, reacts with ammonia recovered from the spray absorption tower in S200 to synthesize carbon-containing chemicals. In this embodiment, CO2 and ammonia are introduced into a urea synthesis tower and reacted at 15-25 MPa and 180-200°C to produce urea, which is sold as a nitrogen fertilizer. Alternatively, CO2 can be introduced into an ammonium bicarbonate reactor and reacted with ammonia water to produce ammonium bicarbonate fertilizer. Through this path, the CO2 produced by combustion is converted into stable chemical products, realizing the full life cycle recycling of carbon elements from organic solid waste to energy products and then to chemical products, significantly reducing the net carbon emissions of the system.

[0047] In summary, this invention achieves the targeted separation and cascade conversion of carbon and nitrogen elements in multi-source organic solid waste. Nitrogen is recovered in the form of high-value-added ammonium salts, and carbon is converted into high-quality syngas for power generation and heating. The system's waste heat is utilized efficiently in a cascade manner, and the CO2 generated from combustion is partially recycled for gasification reactions and partially used to synthesize chemical products, thus constructing a complete material cycle and energy cascade utilization system. In specific implementation, this method ensures the efficiency of low-temperature pyrolysis denitrification through precise online control of the carbon-nitrogen ratio, achieves carbon-nitrogen separation and conversion through two-stage reaction coupling, meets the demand for multi-energy supply through syngas reforming and quality improvement, achieves supply-demand matching and energy efficiency improvement through cascade recovery of waste heat and dynamic control of heat load, and constructs a low-carbon closed loop through CO2 capture and recycling. The entire method is suitable for the dual needs of urban organic solid waste co-processing and regional clean heating, achieving ultra-low nitrogen emissions without the need for complex back-end flue gas denitrification devices; achieving efficient and stable energy supply without the need for external supplementation of large amounts of fossil fuels; and achieving carbon emission reduction without the need for additional treatment of large amounts of CO2. It can effectively support the construction of zero-waste cities and the achievement of carbon peaking and carbon neutrality goals, and significantly improve the environmental and economic benefits of the organic solid waste resource utilization industry.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A multi-energy co-generation and coordinated heating method based on carbon recycling, characterized in that, The steps of this method are as follows: S100, Pretreatment of multi-source organic solid waste and conditioning of carbon-nitrogen ratio: The received organic solid waste is crushed, dehydrated and homogenized to form a mixed raw material. The carbon-nitrogen ratio of the mixed raw material is monitored and controlled in real time. When the monitored carbon-nitrogen ratio is lower than the preset threshold, a high-carbon additive is added to the mixed raw material for conditioning, so that the carbon-nitrogen ratio of the conditioned mixed raw material is within the preset pyrolysis reaction range. S200, First-stage low-temperature pyrolysis and nitrogen element directional separation: The conditioned mixed raw material is fed into the first-stage low-temperature pyrolysis reactor and pyrolyzes at low temperature under anaerobic conditions, so that the organic nitrogen in the conditioned mixed raw material is released in the form of gaseous ammonia. At the same time, ammonia-containing pyrolysis gas and carbon-rich coke are obtained. The ammonia-containing pyrolysis gas is introduced into a spray absorption tower and absorbed by acid to generate an ammonium salt solution. After concentration and crystallization, ammonium fertilizer is obtained. The purified deammoniation gas after ammonia removal is stored in a gas storage tank for later use. S300, Second-stage high-temperature gasification and carbon element directional conversion: The carbon-rich coke separated from S200 is sent to the second-stage high-temperature gasifier, where steam is used as the gasifying agent to carry out a high-temperature gasification reaction, so that the fixed carbon in the carbon-rich coke is converted into high-temperature crude syngas mainly composed of carbon monoxide and hydrogen. The generated high-temperature crude syngas is introduced into the waste heat recovery unit for heat energy extraction. S400 Syngas Purification and Upgrading: The crude syngas after waste heat recovery is sequentially processed through dust removal, filtration and catalytic reforming to remove dust, tar and sulfide impurities, and obtain clean hydrogen-rich syngas. S500, Multi-energy Co-generation and Coordinated Heating: The clean hydrogen-rich syngas is distributed to the multi-energy co-generation unit to perform two energy supply methods: the first part of the syngas is sent to the gas-fired power generation equipment for power generation, and the second part of the syngas is directly used for heating and as fuel for gas-fired boilers for peak-shaving heating. S600, closed-loop carbon recycling: captures carbon dioxide from the flue gas produced by the combustion of gas-fired power generation equipment and gas-fired boilers in S500, and performs carbon recycling.

2. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 1, characterized in that, The various organic solid wastes in S100 include two or more of the following: agricultural straw, municipal kitchen waste, municipal sludge, organic waste residue from food processing, and livestock and poultry manure. The high-carbon additive is selected from one or more of sawdust, rice husks, or biochar produced by the S300 reaction process.

3. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 1, characterized in that, In S100, the carbon-nitrogen ratio adjustment process is as follows: The carbon-nitrogen ratio of the mixed raw materials, monitored in real time by an online elemental analyzer, was: The preset lower limit threshold for the carbon-to-nitrogen ratio in the pyrolysis reaction range is... The upper limit threshold is ; when At that time, according to Calculate the required mass of high-carbon additives. ,in, This refers to the total mass of the mixed raw materials in the current batch. Set a target carbon-to-nitrogen ratio value, which is [value to be filled in]. , The mass fraction of nitrogen in the mixed raw materials is determined in real time by an online elemental analyzer. This refers to the mass fraction of carbon in the high-carbon additive. This refers to the mass fraction of nitrogen in the high-carbon additive. By calculating and controlling the amount of additives added, the carbon-nitrogen ratio of the regulated mixed raw materials is achieved. Stabilized within the preset pyrolysis reaction range Inside.

4. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 1, characterized in that, The S200 primary low-temperature pyrolysis reactor adopts an externally heated rotary kiln, and the reaction temperature is controlled at 350℃-550℃. The acid solution used in the spray absorption tower is a phosphoric acid solution or a sulfuric acid solution, and the generated ammonium salt is an ammonium phosphate salt or an ammonium sulfate salt. The purified gas consists of methane, carbon monoxide, and hydrogen.

5. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 1, characterized in that, The secondary high-temperature gasifier in S300 is one of a circulating fluidized bed gasifier, an entrained flow gasifier, or a fixed bed gasifier, and the gasification temperature is controlled at 900℃-1200℃. The high-temperature crude syngas has a temperature of 900℃-1000℃ before entering the waste heat recovery unit. After heat recovery, it generates high-pressure steam of over 4.2MPa for power generation and heating.

6. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 1, characterized in that, The catalytic reforming process in S400 is as follows: the purified gas after ammonia removal in S200 is used as a reforming agent and reacted with high-temperature crude syngas in a catalytic reforming reaction. By adjusting the amount of purified gas introduced, the molar ratio of hydrogen to carbon monoxide in the reformed syngas is controlled to meet the energy demand of the downstream combined energy supply unit.

7. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 1, characterized in that, When supplying energy, the S500 collects waste heat from the cylinder liner water and flue gas of the gas-fired power generation equipment, as well as the heat energy extracted by the waste heat recovery unit in the S300. This waste heat is then extracted in stages via an absorption heat pump, forming a multi-energy complementary synergistic heating system with the peak-shaving heating of the gas-fired boiler. The real-time control process of this synergistic heating is as follows: Real-time monitoring of heat load demand in heating networks Waste heat recovery from gas-fired power generation equipment in combined energy supply units ; Real-time monitoring of the coefficient of performance (COP) of absorption heat pumps ,according to Determine the heat supply from the second portion of syngas used for direct heating and peak shaving of gas-fired boilers. ,in, The heat recovery efficiency of the waste heat recovery unit is given, with a value range of [value range missing]. ; When calculated When the waste heat recovery of the gas-fired power generation equipment has met the heat load requirements, the second part of the syngas is stored or used for power generation. When calculated At that time, according to The value controls the flow rate of the second part of the syngas entering the gas-fired boiler.

8. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 1, characterized in that, The carbon recycling process in S600 is as follows: a portion of the captured carbon dioxide is used as a gasifying agent and recycled in the secondary high-temperature gasification process of S300, while another portion of the carbon dioxide reacts with the ammonia recovered in S200 to synthesize carbon-containing chemicals.

9. The multi-energy co-generation and coordinated heating method based on carbon recycling according to claim 8, characterized in that, In S600, the captured carbon dioxide is recycled for the secondary high-temperature gasification process of S300 by mixing carbon dioxide with a gasifying agent and then introducing the mixture into the secondary high-temperature gasifier to participate in the Bourdon reaction. It is used to regulate the reaction temperature in the gasifier and improve the carbon conversion rate; The carbon-containing chemical is urea or ammonium bicarbonate.

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