Biogas slurry and biogas residue thermal cracking reaction device and method

Abstract

The invention discloses a biogas slurry and biogas residue thermal cracking reaction device and method. The device comprises a pretreatment unit, a core reaction and cascade heat exchange unit, a product separation unit, a gas purification unit and an intelligent control and auxiliary unit which are sequentially connected, the operation method comprises the steps of biogas slurry pretreatment, gradient preheating, thermal cracking reaction at 100-120 DEG C, reaction product gradient cooling and heat energy recovery, solid-liquid separation and waste gas purification. The treatment efficiency is extremely high, the fertilizer preparation time can be shortened from tens of days to within 6 hours, the organic matter conversion rate is high, the product fertilizer efficiency is good, safety and environment friendliness are achieved, energy consumption is greatly reduced through energy gradient recovery, and efficient and high-valued resource utilization of biogas slurry and biogas residues is achieved.

Description

Technical Field

[0001] This invention relates to a biogas slurry and biogas residue reaction device, specifically a biogas slurry and biogas residue pyrolysis reaction device and method, belonging to the technical field of biogas slurry treatment equipment. Background Technology

[0002] Biogas slurry and biogas residue, as major byproducts of biogas projects, are crucial for achieving a circular economy in agriculture. Currently, mainstream technologies for treating biogas slurry and residue include natural fermentation (traditional composting) and microbial fermentation. However, these traditional technologies have significant limitations in terms of efficiency, product quality, and environmental impact. First, regarding processing efficiency, traditional composting fermentation operates at a temperature of only 30-40℃, with a fertilizer production cycle of 30-45 days. Even with microbial fermentation technology, at 60-70℃, it still requires 20-30 days to complete. This lengthy processing cycle is not only inefficient but also requires substantial land for composting and fermentation, increasing land and time costs. Second, in terms of nutrient conversion and product quality, traditional fermentation technologies have extremely low nutrient conversion efficiency. For example, the water-soluble conversion rate of organic carbon is typically only 1-2%, with the vast majority of organic matter remaining in large molecular form, making it difficult for plants to absorb, resulting in slow fertilizer effectiveness and significant nutrient waste. The resulting traditional organic or bio-organic fertilizers have slow release of nutrients and unstable quality, making it difficult to form high-value-added commercial products. Their soil improvement effect is also very slow. Furthermore, in terms of safety and environmental protection, the low-temperature fermentation process cannot completely kill pathogens and insect eggs, and direct application poses a risk of spreading pests and diseases, threatening agricultural production safety. At the same time, the fermentation process produces foul odors, affecting the surrounding environment.

[0003] In the prior art, 1) a biogas slurry high-temperature treatment device and method disclosed in CN112010558A uses a high-temperature reactor to treat biogas slurry, aiming to shorten the treatment time and sterilize it. However, this technical solution focuses on a single high-temperature treatment stage and lacks a systematic energy recovery design. The heat of the high-temperature product is directly lost, resulting in high overall energy consumption and poor economic efficiency. At the same time, it fails to effectively solve the problems of corrosion, scaling and product quality uniformity control caused by feed impurities. 2) a biomass pyrolysis reaction system disclosed in CN108558279A emphasizes the importance of utilizing the waste heat of pyrolysis products. However, it is mainly for dry biomass raw materials and is not suitable for biogas slurry and biogas residue materials with high water content and complex composition. In particular, it lacks effective pretreatment (such as deodorization, detoxification and pH adjustment) and matching integrated process design for such materials, making it difficult to directly apply to the continuous, stable and high-quality resource utilization treatment of biogas slurry and biogas residue. Summary of the Invention

[0004] The purpose of this invention is to provide a biogas slurry and biogas residue pyrolysis reaction device and method to solve at least one of the above-mentioned technical problems. It should be able to overcome a series of problems such as long cycle, low conversion rate, poor product quality and safety hazards of traditional fermentation technology, so as to realize the rapid, efficient and safe resource utilization of biogas slurry and biogas residue.

[0005] This invention achieves the above objectives through the following technical solution: a biogas slurry and biogas residue pyrolysis reaction device, comprising a pretreatment unit, a core reaction and cascade heat exchange unit, a product separation unit, a gas purification unit, and an intelligent control and auxiliary unit. The pretreatment unit is used to oxidize and alkalize the biogas slurry; the core reaction and cascade heat exchange unit is used to perform pyrolysis on the pretreated biogas slurry and recover heat; the product separation unit is used to separate the reacted materials into solid and liquid components; the gas purification unit is used to wash and purify the generated waste gas; and the intelligent control and auxiliary unit is used to automate the operation of the entire device. The pretreatment unit includes an oxidation unit and an alkalization unit connected in sequence. The core reaction and cascade heat exchange unit includes a thermal decomposition reaction unit and heat exchange units A and B connected thereto. The product separation unit includes a vibrating screen, the inlet of which is connected to the hot side outlet of heat exchange unit B via a pipeline. The gas purification unit includes a spraying device, the gas inlet of which is connected to the exhaust ports of the oxidation unit, the alkalization unit, the vibrating screen, and the thermal decomposition reaction unit via exhaust gas collection pipelines.

[0006] As a further embodiment of the present invention: the oxidation device is an inlet treatment device for biogas slurry, which is equipped with an ozone distributor inside, and the ozone distributor is connected to an external ozone generator.

[0007] As a further embodiment of the present invention: the alkalization device is connected in series downstream of the oxidation device. The alkalization device includes a reaction tank, a pH sensor for real-time monitoring of the pH value of the biogas slurry, a metering pump for precise addition of alkali solution, and an alkali solution tank for storing alkali solution.

[0008] As a further embodiment of the present invention: the pyrolysis reactor is a sealed pressure-resistant container. The pyrolysis reactor is equipped with a stirrer and an electric heating element. The material inlet of the pyrolysis reactor is connected to the outlet of the temporary storage device through a pipeline. The material outlet of the pyrolysis reactor is connected to the hot side inlet of the heat exchange device A through a pipeline. The operating temperature range of the pyrolysis reactor is 100-120℃.

[0009] As a further embodiment of the present invention: the inlet of the temporary storage device is connected to the cold side outlet of the heat exchange device A through a pipeline, and the outlet of the temporary storage device is connected to the material inlet of the thermal decomposition reaction device through a pipeline.

[0010] As a further embodiment of the present invention: heat exchange device A is a high-temperature heat exchanger, the hot side inlet of heat exchange device A is connected to the material outlet of the thermal cracking reaction device through a pipeline, the hot side outlet of heat exchange device A is connected to the hot side inlet of heat exchange device B through a pipeline, the cold side inlet of heat exchange device A is connected to the outlet of the alkalization device through a pipeline, and the cold side outlet of heat exchange device A is connected to the inlet of the temporary storage device through a pipeline. Heat exchanger B is a low-temperature heat exchanger. The hot side inlet of heat exchanger B is connected to the hot side outlet of heat exchanger A through a pipeline. The hot side outlet of heat exchanger B is connected to the inlet of the vibrating screen through a pipeline. The cold side inlet of heat exchanger B is connected to the outlet of the oxidation unit through a pipeline. The cold side outlet of heat exchanger B is connected to the inlet of the alkalization unit through a pipeline.

[0011] As a further aspect of the present invention: the spraying device is equipped with a spray head and a packing layer, and the spraying device washes and purifies the generated waste gas by circulating spraying washing liquid.

[0012] As a further embodiment of the present invention: the intelligent control and auxiliary unit includes a central control cabinet, which contains a PLC and a human-machine interface. The central control cabinet is connected to the sensors and actuators in the device via electrical signals.

[0013] A method for operating a biogas slurry and biogas residue pyrolysis reactor, the method comprising the following steps: S1: Pump the biogas slurry into the pretreatment unit for oxidation and alkalization treatment; S2: The treated biogas slurry is preheated in stages by passing it through the cold side of heat exchanger B and the cold side of heat exchanger A in sequence. S3: The preheated biogas slurry is fed into the pyrolysis reactor and pyrolysis reaction is carried out at 100-120℃; S4: The high-temperature reaction products generated by the thermal cracking reaction of biogas slurry are sequentially cooled through the hot side of heat exchanger A and the hot side of heat exchanger B, while simultaneously achieving step-by-step preheating. S5: The cooled reaction products are subjected to solid-liquid separation to obtain liquid organic fertilizer and solid residue; S6: Collect and purify the waste gas generated during the process.

[0014] As a further embodiment of the present invention: in S1, the oxidation treatment adopts ozone oxidation, and the alkalization treatment adjusts the pH value of the biogas slurry to a set range by adding alkali solution; in S3, the thermal pyrolysis reaction time is 3-4 hours.

[0015] The beneficial effects of this invention are: This invention employs a thermal decomposition reaction at 100-120℃, resulting in extremely high processing efficiency. It shortens the fertilizer production time from a fermentation cycle of tens of days to less than 6 hours, achieving a high organic matter conversion rate, producing a product with good fertilizer efficacy, and ensuring safety and environmental protection. Furthermore, it significantly reduces energy consumption through energy cascade recovery, realizing the efficient and high-value utilization of biogas slurry and biogas residue resources. This results in an order-of-magnitude increase in processing efficiency and substantial savings in production time and space occupation. 2) This invention achieves a water-soluble conversion rate of up to 98% for organic carbon, and the resulting liquid organic fertilizer is rich in small molecule active substances that are easily absorbed by crops. The fertilizer effect is rapid and stable, and the added value of the product is significantly higher than that of traditional organic fertilizer. 3) The invention can completely kill pathogens and insect eggs in the high-temperature pyrolysis process, ensuring the safety of the product for agricultural use. At the same time, the ozone oxidation treatment at the front end and the gas purification unit at the back end effectively eliminate odor and exhaust gas pollution in the production process, making the entire production process greener and more environmentally friendly. 4) The innovative counter-current cascade heat exchange circuit of this invention utilizes the heat of high-temperature products to fully preheat the feed biogas slurry, maximizing the recovery of reaction heat and significantly reducing system operating energy consumption. Combined with the intelligent control unit, it improves the overall economic efficiency and stability of operation. 5) The design of the oxidation and alkalization pretreatment unit adopted in this invention not only improves the applicability of raw materials and the quality of products, but also effectively alleviates the corrosion and scaling problems that subsequent equipment may face, extends the service life of the equipment, and ensures the reliability of continuous and stable production. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1, as Figure 1As shown in the figure, this embodiment provides a biogas slurry and biogas residue pyrolysis reactor, including a pretreatment unit, a core reaction and cascade heat exchange unit, a product separation unit, a gas purification unit, and an intelligent control and auxiliary unit. The pretreatment unit is used to oxidize and alkalize the biogas slurry; the core reaction and cascade heat exchange unit is used to perform pyrolysis on the pretreated biogas slurry and recover heat; the product separation unit is used to separate the reacted materials into solid and liquid components; the gas purification unit is used to wash and purify the generated waste gas; and the intelligent control and auxiliary unit is used to automatically control the operation of the entire device. The pretreatment unit includes an oxidation unit and an alkalization unit connected in sequence. The core reaction and cascade heat exchange unit includes a thermal decomposition reaction unit and heat exchange units A and B connected thereto. The product separation unit includes a vibrating screen, the inlet of which is connected to the hot side outlet of heat exchange unit B through a pipeline. This screen is used to separate the reaction products after two stages of heat exchange and sufficient cooling into liquid products (i.e., high-quality liquid organic fertilizer) and solid residues. The gas purification unit includes a spraying device, the gas inlet of which is connected to the exhaust ports of the oxidation unit, alkalization unit, vibrating screen, and thermal decomposition reaction unit through exhaust gas collection pipelines.

[0019] Example 2, in addition to all the technical features in Example 1, also includes: an oxidation device as an inlet treatment device for biogas slurry, which is equipped with an ozone distributor connected to an external ozone generator. The function of the oxidation device is to oxidize the externally input biogas slurry, aiming to completely eliminate odor (using strong oxidants such as ozone to decompose odor-causing substances such as hydrogen sulfide, thiols, and volatile fatty acids in the biogas slurry), degrade harmful organic matter (generating reactive oxygen free radicals through oxidation to decompose residual antibiotics, pesticide residues, and allelochemicals with plant toxicity in the biogas slurry), decolorize and homogenize (partially degrading the dark brown humic macromolecules in the biogas slurry to adjust the product color), and kill pathogens and insect eggs (effectively eliminating pathogenic microorganisms such as E. coli and parasite eggs).

[0020] The alkalization unit is connected in series downstream of the oxidation unit. The alkalization unit includes a reaction tank, a pH sensor for real-time monitoring of the pH value of the biogas slurry, a metering pump for precise addition of alkali solution, and an alkali solution tank for storage.

[0021] The function of the alkalization device is to precisely adjust the pH value of the biogas slurry by adding alkali solution (preferably potassium hydroxide solution) to the biogas slurry in the reaction tank via a metering pump based on the feedback signal from the pH sensor. This adjustment can serve as a precondition for complexation / chelation reactions (promoting the chelation reaction between humic acid and trace elements, preventing the precipitation of trace elements), achieving precise pH control (making the pH value of the final liquid fertilizer suitable for specific crops), synergizing with "ammonia recovery" to produce high-nitrogen fertilizer, and promoting the mineralization and extraction of phosphorus (promoting the mineralization and extraction of phosphorus through crystallization under alkaline conditions).

[0022] The pyrolysis reactor is a sealed, pressure-resistant vessel. Inside, it is equipped with a stirrer and electric heating elements. The material inlet of the reactor is connected to the outlet of a temporary storage device via a pipeline, and the material outlet is connected to the hot-side inlet of heat exchanger A via a pipeline. The operating temperature range of the pyrolysis reactor is 100-120℃ to achieve efficient bio-pyrolysis of biogas slurry and biogas residue.

[0023] The inlet of the temporary storage device is connected to the cold side outlet of heat exchanger A via a pipeline, and the outlet of the temporary storage device is connected to the material inlet of the thermal cracking reactor via a pipeline.

[0024] Heat exchanger A is a high-temperature heat exchanger. The hot side inlet of heat exchanger A is connected to the material outlet of the thermal cracking reactor through a pipeline. The hot side outlet of heat exchanger A is connected to the hot side inlet of heat exchanger B through a pipeline. The cold side inlet of heat exchanger A is connected to the outlet of the alkalization device through a pipeline. The cold side outlet of heat exchanger A is connected to the inlet of the temporary storage device through a pipeline. Heat exchanger B is a low-temperature heat exchanger. The hot side inlet of heat exchanger B is connected to the hot side outlet of heat exchanger A through a pipeline. The hot side outlet of heat exchanger B is connected to the inlet of the vibrating screen through a pipeline. The cold side inlet of heat exchanger B is connected to the outlet of the oxidation unit through a pipeline. The cold side outlet of heat exchanger B is connected to the inlet of the alkalization unit through a pipeline.

[0025] Through the above connection, the core reaction and the cascade heat exchange unit form a highly efficient counter-current cascade heat exchange loop, realizing the cascade preheating of the feed by the reaction products, thereby maximizing the recovery of reaction heat and achieving high efficiency and energy saving.

[0026] The spraying device is equipped with spray heads and a packing layer. The spraying device uses a circulating spray washing liquid (such as water or weak alkaline solution) to wash and purify the generated waste gas, so as to remove malodorous gases, acidic gases and dust, and ensure that the final emission gas meets environmental protection standards.

[0027] The intelligent control and auxiliary unit includes a central control cabinet, which contains a PLC (Programmable Logic Controller) and a human-machine interface (such as a touch screen). The central control cabinet is connected to sensors (including temperature sensors, pressure sensors, liquid level sensors, pH sensors, etc.) and actuators (including various valves, water pumps, agitators, electric heaters, etc.) in the device via electrical signals to achieve automated monitoring, parameter adjustment, data recording and safety interlock protection of the entire process.

[0028] Example 3: An operation method for a biogas slurry and biogas residue pyrolysis reactor, the operation method comprising the following steps: S1: Pump the biogas slurry into the pretreatment unit for oxidation and alkalization treatment; S2: The treated biogas slurry is preheated in stages by passing it through the cold side of heat exchanger B and the cold side of heat exchanger A in sequence. S3: The preheated biogas slurry is fed into the pyrolysis reactor and pyrolysis reaction is carried out at 100-120℃; S4: The high-temperature reaction products generated by the thermal cracking reaction of biogas slurry are sequentially cooled through the hot side of heat exchanger A and the hot side of heat exchanger B, while simultaneously achieving step-by-step preheating. S5: The cooled reaction products are subjected to solid-liquid separation to obtain liquid organic fertilizer and solid residue; S6: Collect and purify the waste gas generated during the process.

[0029] Furthermore, in S1, the oxidation treatment uses ozone oxidation, and the alkalization treatment adjusts the pH value of the biogas slurry to a set range by adding alkali solution; in S3, the thermal pyrolysis reaction time is 3-4 hours.

[0030] Working Principle and Process: External biogas slurry is first pumped into the oxidation unit, where ozone supplied by an ozone distributor strongly oxidizes it, effectively eliminating odors, degrading harmful organic matter, and killing pathogens. The oxidized biogas slurry, as a cold material, enters the cold side of heat exchanger B, which acts as a low-temperature heat exchanger, undergoing initial heat exchange with hot material from upstream for preliminary preheating. After preliminary preheating, the biogas slurry enters the alkalization unit, where a pH sensor monitors its pH value in real time, and a metering pump precisely adds alkali solution (such as potassium hydroxide solution) to adjust it to the required range, facilitating subsequent nutrient stabilization and chelation. The alkalized biogas slurry then enters the cold side of heat exchanger A, which acts as a high-temperature heat exchanger, undergoing deep heat exchange with high-temperature products from the pyrolysis reactor, further increasing its temperature. The biogas slurry, after two stages of preheating, is temporarily stored in a storage unit and then sent to the pyrolysis reactor. In this unit, heat is supplemented by built-in electric heating elements, and under the action of a stirrer, the material undergoes a continuous pyrolysis reaction for several hours in a closed environment at 100-120℃, efficiently converting organic matter into small-molecule active substances. After the reaction, the high-temperature products flow sequentially through the hot side of heat exchanger A and the hot side of heat exchanger B. In this counter-current flow, they transfer their heat in stages to the newly entering cold biogas slurry, achieving efficient heat recovery while being fully cooled. The cooled products then enter a vibrating screen for solid-liquid separation, ultimately yielding high-quality liquid organic fertilizer and solid residue. Throughout the process, waste gas generated by each unit is collected and introduced into a spray system, where it is washed and purified by the spray liquid before being discharged. The entire process is automated and optimized by an intelligent control and auxiliary unit through sensor monitoring and actuator control.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A biogas slurry and biogas residue pyrolysis reactor, characterized in that: It includes a pretreatment unit, a core reaction and cascade heat exchange unit, a product separation unit, a gas purification unit, and an intelligent control and auxiliary unit; The pretreatment unit is used to oxidize and alkalize the biogas slurry; the core reaction and cascade heat exchange unit is used to perform thermal cracking reaction on the pretreated biogas slurry and recover heat; the product separation unit is used to perform solid-liquid separation on the reacted material; the gas purification unit is used to wash and purify the generated waste gas; and the intelligent control and auxiliary unit is used to automate the operation of the entire device. The pretreatment unit includes an oxidation device and an alkalization device connected in sequence. The core reaction and cascade heat exchange unit includes a thermal decomposition reaction device and heat exchange devices A and B connected thereto. The product separation unit includes a vibrating screen, the inlet of which is connected to the hot side outlet of heat exchange device B via a pipeline. The gas purification unit includes a spray device, the gas inlet of which is connected to the exhaust ports of the oxidation device, the alkalization device, the vibrating screen, and the thermal decomposition reaction device via a waste gas collection pipeline.

2. The biogas slurry and biogas residue pyrolysis reactor according to claim 1, characterized in that: The oxidation device is equipped with an ozone distributor, which is connected to an external ozone generator.

3. The biogas slurry and biogas residue pyrolysis reactor according to claim 1, characterized in that: The alkalization device is connected in series downstream of the oxidation device. The alkalization device includes a reaction tank, a pH sensor for real-time monitoring of the pH value of the biogas slurry, a metering pump for precise addition of alkali solution, and an alkali solution tank for storing the alkali solution.

4. The biogas slurry and biogas residue pyrolysis reactor according to claim 1, characterized in that: The pyrolysis reactor is a sealed pressure vessel. The pyrolysis reactor is equipped with a stirrer and an electric heating element. The material inlet of the pyrolysis reactor is connected to the outlet of the temporary storage device through a pipeline. The material outlet of the pyrolysis reactor is connected to the hot side inlet of the heat exchange device A through a pipeline. The operating temperature range of the pyrolysis reactor is 100-120℃.

5. The biogas slurry and biogas residue pyrolysis reactor according to claim 1, characterized in that: The inlet of the temporary storage device is connected to the cold side outlet of the heat exchange device A via a pipeline, and the outlet of the temporary storage device is connected to the material inlet of the thermal cracking reactor via a pipeline.

6. The biogas slurry and biogas residue pyrolysis reactor according to claim 1, characterized in that: The heat exchange device A is a high-temperature heat exchanger. The hot side inlet of the heat exchange device A is connected to the material outlet of the thermal cracking reaction device through a pipeline. The hot side outlet of the heat exchange device A is connected to the hot side inlet of the heat exchange device B through a pipeline. The cold side inlet of the heat exchange device A is connected to the outlet of the alkalization device through a pipeline. The cold side outlet of the heat exchange device A is connected to the inlet of the temporary storage device through a pipeline. The heat exchange device B is a low-temperature heat exchanger. The hot side inlet of the heat exchange device B is connected to the hot side outlet of the heat exchange device A through a pipeline. The hot side outlet of the heat exchange device B is connected to the inlet of the vibrating screen through a pipeline. The cold side inlet of the heat exchange device B is connected to the outlet of the oxidation device through a pipeline. The cold side outlet of the heat exchange device B is connected to the inlet of the alkalization device through a pipeline.

7. The biogas slurry and biogas residue pyrolysis reactor according to claim 1, characterized in that: The spraying device is equipped with spray heads and a packing layer. The spraying device uses circulating spray washing liquid to wash and purify the generated waste gas.

8. The biogas slurry and biogas residue pyrolysis reactor according to claim 1, characterized in that: The intelligent control and auxiliary unit includes a central control cabinet, which contains a PLC and a human-machine interface. The central control cabinet is connected to the sensors and actuators in the device via electrical signals.

9. A method for operating a biogas slurry and biogas residue pyrolysis reactor, comprising the biogas slurry and biogas residue pyrolysis reactor as described in any one of claims 1-8, characterized in that, The operating method includes the following steps: S1: Pump the biogas slurry into the pretreatment unit for oxidation and alkalization treatment; S2: The treated biogas slurry is preheated in stages by passing it through the cold side of heat exchanger B and the cold side of heat exchanger A in sequence. S3: The preheated biogas slurry is fed into the pyrolysis reactor and pyrolysis reaction is carried out at 100-120℃; S4: The high-temperature reaction products generated by the thermal cracking reaction of biogas slurry are sequentially cooled through the hot side of heat exchanger A and the hot side of heat exchanger B, while simultaneously achieving step-by-step preheating. S5: The cooled reaction products are subjected to solid-liquid separation to obtain liquid organic fertilizer and solid residue; S6: Collect and purify the waste gas generated during the process.

10. The operating method according to claim 9, characterized in that: In S1, the oxidation treatment uses ozone oxidation, and the alkalization treatment adjusts the pH value of the biogas slurry to a set range by adding alkali solution; in S3, the thermal pyrolysis reaction time is 3-4 hours.

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