Brewing waste pyrolysis method based on dynamic monitoring feedback control

Abstract

The invention relates to a wine brewing waste pyrolysis method based on dynamic monitoring feedback control, which comprises the following steps: S1, firstly carrying out double-screw low-temperature shearing treatment on fresh vinasse, then carrying out vibratory screening impurity removal and airflow crushing refining on pit mud, and then preparing a starch-based composite binder, finally, mixing the materials, granulating by a twin-screw spherical granulator, and carrying out belt drying to form composite spherical particles; s2, performing starch pyrolysis on the pretreated composite particles in a low-temperature reaction section to generate small-molecular organic matters to coat pit mud catalytic active sites, and performing complete cracking and escaping of starch residues on the particles treated by the low-temperature reaction section in a high-temperature carbonization section, and performing pore broadening by combining with water vapor, and finally, the pyrolysis product of the high-temperature carbonization section is subjected to gas-solid separation through a cyclone separator, water vapor is introduced into the separated biochar for activation treatment, the pyrolysis product is obtained, and technological parameters are dynamically adjusted through multi-parameter real-time monitoring and closed-loop control so that it can be guaranteed that the pyrolysis reaction is stable, and the product quality can reach the standard.

Description

Technical Field

[0001] This invention relates to the field of brewing waste pyrolysis technology, and in particular to a brewing waste pyrolysis method based on dynamic monitoring feedback control. Background Technology

[0002] In the field of waste resource utilization, pyrolysis technology is widely used to convert biomass waste into high-value-added biochar and bio-oil. Biochar, due to its high specific surface area, porous structure, and good adsorption properties, is an ideal material for soil improvement and wastewater treatment; bio-oil can be used as fuel or chemical raw material, possessing high economic value. The process parameters of pyrolysis technology (such as temperature, residence time, and atmosphere) have a decisive impact on product quality. Conventional pyrolysis technology is mainly designed for homogeneous organic waste (such as pure sawdust and straw), and its pyrolysis mechanism and process are relatively mature. Strong-aroma baijiu, as the mainstream aroma type of Chinese baijiu, uses mud pits for fermentation. This inevitably leads to the mixing of the fermented mash with the pit mud (mainly containing clay minerals such as montmorillonite and illite, as well as microbial residues) during fermentation, forming a complex organic and inorganic waste. This waste is unique to strong-aroma baijiu and is fundamentally different from the waste of light-aroma baijiu (fermented in earthenware jars) and sauce-aroma baijiu (fermented in stone pits). However, for complex wastes containing large amounts of clay minerals, the pyrolysis process faces unique challenges because clay minerals not only affect the pyrolysis reaction kinetics but also directly determine the structure and properties of the products, making it difficult to directly apply conventional pyrolysis technologies.

[0003] CN116809611A discloses a reuse method, particularly a reuse method for treating baijiu (Chinese liquor) lees. This invention provides a reuse method for baijiu lees that can thoroughly treat and fully recover and reuse baijiu brewing lees. The method first dries the lees, then sieves the dried baijiu lees into light waste and heavy residue. The heavy residue is then packaged and stored for other uses. The light waste is subjected to anaerobic pyrolysis to recover solid residues, gaseous and liquid products, and heat energy. Finally, the gaseous and liquid products are purified before being discharged, completing the reuse of the baijiu lees. The heat energy recovery is achieved by burning the produced non-condensable gases in an energy conversion device to produce high-temperature desalinated water at a temperature of 80℃~90℃, which is then collected and used.

[0004] The pyrolysis of waste from strong-aroma baijiu (Chinese liquor) faces three major technical challenges. First, the catalytic-adsorption dual effect of the cellar mud: clay minerals such as montmorillonite in the cellar mud act as natural catalysts, accelerating the secondary cracking of the pyrolysis products, leading to a sharp drop in bio-oil yield, significant loss of high-value components (such as phenols and esters), and increased acidity of the bio-oil, rendering it unusable as fuel. Second, clay particle agglomeration blocks biochar pores: during pyrolysis, clay particles easily agglomerate, filling the micropores of biochar and reducing its specific surface area and mesopore ratio, falling far below the standards for agricultural biochar, thus causing it to lose its adsorption function. Third, the density difference between the lees and cellar mud causes material stratification: the significant density difference between the lees and cellar mud makes stratification highly likely after mixing, resulting in temperature differences within the pyrolysis furnace reaching ±50℃, affecting the uniformity of the pyrolysis reaction and the stability of the product quality. Existing technologies mostly employ fixed-parameter pyrolysis processes, failing to consider the impact of clay properties on the pyrolysis process, and lacking effective material control methods for density differences. They rely solely on conventional methods such as mechanical stirring, which cannot fundamentally solve these problems, resulting in short equipment operating cycles, large fluctuations in product quality, and difficulty in achieving large-scale and stable industrial applications.

[0005] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for pyrolysis of brewing waste based on dynamic monitoring and feedback control to solve at least some of the above-mentioned technical problems.

[0007] This invention discloses a method for pyrolysis of brewing waste based on dynamic monitoring and feedback control, which includes the following steps: S1. Fresh distiller's grains are first subjected to twin-screw low-temperature shearing to cut their cellulose fibers into short distiller's grains fibers and squeeze out some free water. Then, the cellar mud is subjected to vibration screening to remove impurities and airflow pulverization to refine it. Then, a starch-based composite binder with corn starch as the main film-forming substance and distiller's grains hydrolysate is prepared. Finally, the pretreated short distiller's grains fibers, cellar mud clay particles and starch-based composite binder are mixed and granulated by twin-screw spherical granulator and belt drying to form composite spherical particles. S2. First, the pretreated composite particles are pyrolyzed in the low-temperature reaction section of a two-stage fluidized bed pyrolysis reactor to generate small molecule organic matter that coats the catalytic active sites of the pit mud. Then, the particles treated in the low-temperature reaction section are pyrolyzed in the high-temperature carbonization section to completely release the starch residues and expand the pores with water vapor. Finally, the pyrolysis products in the high-temperature carbonization section are subjected to gas-solid separation by a cyclone separator, and the separated biochar is activated by passing water vapor to obtain the pyrolysis products.

[0008] In step S2, the process parameters are dynamically adjusted through real-time monitoring of multiple parameters by several monitoring units and closed-loop control of the central control unit to ensure the stability of the pyrolysis reaction and the quality of the product. The data collected by the several monitoring units include temperature data, gas composition data and / or biochar characteristic data.

[0009] This invention effectively solves the core problem in the pyrolysis of waste from strong-aroma baijiu by systematically integrating the pretreatment process of distiller's grains and cellar mud, the preparation of starch-based composite binders, the granulation of composite spherical particles, and a two-stage pyrolysis process with dynamic monitoring and feedback control. The twin-screw low-temperature shearing process, conducted below the starch gelatinization temperature, achieves both shearing and refining of the cellulose fibers in the distiller's grains and avoids fiber adhesion caused by premature starch gelatinization. Simultaneously, it squeezes out some free water, providing suitable moisture conditions for subsequent mixing and granulation. The vibratory screening and airflow pulverization of the cellar mud significantly reduces the agglomeration of clay particles, making their particle size compatible with the short fibers of the distiller's grains. The starch-based composite binder, by adding distiller's grains hydrolysate, utilizes the glucose and organic acids to improve the interfacial compatibility between starch and cellar mud, preventing particle cracking after granulation. The composite particle granulation process… During the granulation process, the semi-gelatinized starch system coats the raw material particles, and the short fibers of the distiller's grains interweave in the coating layer to form an interlocking structure, effectively eliminating the density difference between the distiller's grains and the cellar mud, and ensuring uniform particle density. In the two-stage pyrolysis process, the low-temperature reaction stage causes the starch to pyrolyze and generate small molecule organic matter that coats the catalytic active sites of the cellar mud, inhibiting excessive catalysis. The high-temperature carbonization stage causes the starch residues to completely decompose and escape, and combine with water vapor to expand the pores, avoiding pore blockage. Dynamic monitoring and feedback control accurately adapts to the fluctuations in raw material composition through real-time monitoring of multiple parameters and closed-loop adjustment, ensuring the stability of the pyrolysis reaction and the consistency of product quality.

[0010] According to a preferred embodiment, in the preparation of the starch-based composite binder in step S1, corn starch is first mixed with water to form a mixed system; then, a distillers' grains hydrolysate is added to the mixed system. The preparation process of the distillers' grains hydrolysate is as follows: a portion of the fresh distillers' grains before pretreatment is taken, and a dilute sulfuric acid solution is added to carry out a hydrolysis reaction, so that the cellulose in the distillers' grains is partially hydrolyzed to generate glucose and organic acids.

[0011] The addition of distillers' grains hydrolysate enhances the interfacial compatibility between the starch-based composite binder and the clay particles in the fermentation pit. During preparation, the glucose and organic acids generated from the hydrolysis of distillers' grains with dilute sulfuric acid improve the interfacial bonding between starch and clay particles, preventing the granules from cracking due to insufficient interfacial bonding. Simultaneously, the glucose in the hydrolysate can serve as a supplementary carbon source during subsequent pyrolysis, increasing the carbon content of the biochar. This design utilizes the distillers' grains' own hydrolysate instead of adding additional compatibility modifiers, achieving resource recycling and avoiding potential contamination from additives. This improves the structural stability of the composite particles and lays the foundation for the effective functioning of starch during subsequent pyrolysis.

[0012] According to a preferred embodiment, in step S1, the pretreated short fibers of distiller's grains, clay particles of cellar mud and starch-based composite binder are mixed and then fed into a constant temperature mixing tank for stirring. The stirring temperature and stirring speed of the constant temperature mixing tank are controlled so that the mixed raw materials form a stable semi-gelatinized state after continuous stirring, and the mixed raw materials are evenly dispersed and excessive bubbles are avoided.

[0013] The stirring temperature in the constant-temperature mixing tank is controlled within the range where the starch reaches a semi-gelatinized state (60-70℃), and the stirring speed is controlled at 140-160 r / min to ensure uniform dispersion of the mixture and avoid excessive air bubbles, thus forming a stable semi-gelatinized state for the mixed raw materials, with a viscosity controlled at 500-800 mPa·s. This control of the semi-gelatinized state allows the starch-based composite binder to effectively coat the short fibers of distiller's grains and the clay particles of the cellar mud, forming structurally stable composite particles. This avoids the problems of adhesion and clumping caused by excessive starch gelatinization or insufficient particle strength caused by insufficient gelatinization, providing a uniform and stable mixture foundation for subsequent twin-screw spherical granulation.

[0014] According to a preferred embodiment, in the twin-screw spherical granulation process of step S1, the screw speed of the twin-screw spherical granulator is controlled to achieve full mixing of raw materials and the formation of spherical particles. During the granulation process, the semi-gelatinized system of starch-based composite binder coats the short fibers of distiller's grains and the clay particles of cellar mud. The short fibers of distiller's grains are interwoven in the coating layer to form an interlocking structure of distiller's grains, starch and cellar mud. This interlocking structure effectively eliminates the density difference between distiller's grains and cellar mud, ensuring the density uniformity of the spherical particles.

[0015] The screw speed of the twin-screw spherical granulator is controlled at 110~130 r / min, and the die aperture is selected at 2~4 mm. This allows the semi-gelatinized system of the starch-based composite binder to coat the short fibers of distiller's grains and the clay particles of the cellar mud. The short fibers of distiller's grains are interwoven in the coating layer, forming an interlocking structure of distiller's grains, starch, and cellar mud. This interlocking structure utilizes the porous structure of the short fibers of distiller's grains, combining the coating effect of starch with the interpenetrating characteristics of the fibers. This effectively eliminates the density difference between distiller's grains and cellar mud, resulting in uniform density of the composite particles. This ensures good fluidization of the particles in fluidized bed pyrolysis and avoids material stratification and uneven pyrolysis temperature caused by density differences.

[0016] According to a preferred embodiment, in the two-stage fluidized bed pyrolysis reactor used in step S2, the low-temperature reaction section is located at the top and the high-temperature carbonization section is located at the bottom. A flow guiding structure is set between the two sections to ensure that the composite particles smoothly enter the high-temperature carbonization section from the low-temperature reaction section. Both the low-temperature reaction section and the high-temperature carbonization section have independent temperature control systems and atmosphere control systems. The temperature control system uses electric heating or gas heating to achieve temperature regulation, and the atmosphere control system controls the type and flow rate of the incoming gas through a gas flow meter.

[0017] The two-stage fluidized bed pyrolysis reactor is designed with the low-temperature reaction section at the top and the high-temperature carbonization section at the bottom. A flow guide structure between the two sections ensures the smooth entry of composite particles. Independent temperature and atmosphere control systems for each section enable precise temperature gradient control during pyrolysis. This design avoids problems such as uneven particle heating and localized over-reaction that are common in conventional single-stage fixed-bed reactors. It ensures that the coating function of starch in the low-temperature section and the pore-forming function in the high-temperature section can be independently and fully utilized, providing a structural foundation for the subsequent high-quality formation of biochar and making the pyrolysis process more uniform and stable.

[0018] According to a preferred embodiment, in the low-temperature reaction section of step S2, the temperature of the low-temperature reaction section is controlled in a range below the temperature at which starch is completely decomposed into gaseous products, ensuring that starch pyrolysis generates small molecule organic compounds mainly composed of glucose and maltodextrin; the residence time of the low-temperature reaction section is controlled in a range that ensures that starch is fully pyrolyzed to generate small molecule organic compounds and that the organic compounds effectively coat the catalytic active sites of the pit mud; the atmosphere of the low-temperature reaction section is nitrogen, which is uniformly introduced into the reactor through an airflow distributor.

[0019] The temperature in the low-temperature reaction section is controlled at 350-450℃ to ensure that starch pyrolysis produces small-molecule organic compounds, mainly glucose and maltodextrins, rather than directly decomposing into gases such as CO and CO2. The residence time is controlled at 20-25 minutes to ensure that the starch is fully pyrolyzed to produce small-molecule organic compounds and effectively coats the catalytic active sites of the pit mud. A nitrogen atmosphere is uniformly introduced through an airflow distributor to maintain an inert environment to prevent oxidation, while simultaneously driving particle flow to ensure sufficient contact. This precise control of temperature and residence time allows the starch pyrolysis products to effectively combine with catalytic active sites such as aluminum and iron ions in the pit mud clay to form an organic coating layer. This prevents the catalytic active sites from contacting the pyrolysis products of the distiller's grains fiber, thereby inhibiting excessive catalytic cracking of bio-oil by the clay and reducing the waste of organic carbon.

[0020] According to a preferred embodiment, in the high-temperature carbonization section of step S2, the temperature of the high-temperature carbonization section is controlled in a range higher than the pyrolysis temperature of starch residues, ensuring that the starch residues are completely decomposed into gaseous products such as hydrogen, carbon monoxide, and methane and escape, while the organic components in the distillers' grains fiber are fully carbonized to form a stable carbon skeleton; the residence time of the high-temperature carbonization section is controlled in a range that ensures the complete pyrolysis of starch residues and that water vapor fully exerts its pore-expanding effect; the atmosphere of the high-temperature carbonization section is a mixture of nitrogen and water vapor.

[0021] The high-temperature carbonization section is controlled at 600-650℃ to ensure the complete decomposition of starch residues into gaseous products such as H2, CO, and CH4, which then escape. Simultaneously, the organic components of the distiller's grains fiber are fully carbonized to form a stable carbon skeleton. The residence time is controlled at 30-35 minutes to ensure complete pyrolysis of starch residues and that water vapor fully exerts its pore-expanding effect. In a mixed atmosphere of nitrogen and water vapor, the water vapor undergoes a gasification reaction with the biochar surface (C + H2O → CO + H2), forming new pores and expanding existing pores, thus increasing the pore size from the mesoporous range to a more suitable adsorption range. At the same time, the water vapor dilutes the catalytically active region around the pit mud clay, weakening its adsorption of bio-oil and indirectly increasing the bio-oil yield. This control method results in high porosity and structural stability of the biochar, preventing clay particle agglomeration and pore blockage.

[0022] According to a preferred embodiment, in the biochar activation treatment in step S2, the biochar collected by the cyclone separator is sent to a low-temperature activation machine. During the activation process, water vapor is introduced so that the water vapor reacts with the residual starch carbon residue on the surface of the biochar, converting it into gaseous products to remove the residual carbon residue. On the other hand, the water vapor further expands the pores of the biochar and improves its adsorption performance.

[0023] In the biochar activation process, steam is introduced, causing it to react with residual starch and carbon residue on the biochar surface. This reacts the residue into gaseous products, which then escape, thus removing the residual carbon residue. Simultaneously, the steam further expands the pores of the biochar, enhancing its adsorption performance. This activation process not only removes any carbon residue that may remain from the pyrolysis process but also further optimizes the pore structure of the biochar through a gasification reaction. This increases the specific surface area and mesopore ratio of the biochar, meeting the standards for agricultural biochar and enhancing its adsorption capacity.

[0024] According to a preferred embodiment, the central control unit is used to collect data collected by each monitoring unit and perform data calculation and analysis. When an abnormal scenario is determined, an adjustment command is issued to the actuator of the two-stage fluidized bed pyrolysis reactor. The monitoring unit includes a temperature monitoring unit for collecting temperature data, a gas component monitoring unit for collecting gas component data, and / or a biochar characteristic monitoring unit for collecting biochar characteristic data.

[0025] The central control unit collects and analyzes data from the temperature monitoring unit, gas composition monitoring unit, and biochar characteristic monitoring unit. When an abnormal scenario is detected, it issues adjustment commands to the actuators. This closed-loop control system, through real-time monitoring of multiple parameters, precisely adapts to fluctuations in the composition of pretreated composite particles (such as changes in pit mud content and differences in the moisture content of distiller's grains). This ensures the stable functioning of starch in low-temperature coating of catalytic sites and high-temperature in-situ pore formation during the stepwise pyrolysis process. It avoids problems such as pyrolysis reaction imbalance and substandard product quality caused by fluctuations in raw material characteristics, thus improving the stability of the pyrolysis process and the consistency of product quality.

[0026] According to a preferred embodiment, the central control unit can be configured as follows: When the ratio of carbon monoxide to carbon dioxide in the exhaust gas at the outlet of the high-temperature carbonization section exceeds the upper limit of the preset normal range and the bio-oil yield is lower than the preset standard, the first abnormal scenario of "excessive catalysis due to excessive sludge content" is determined to have occurred, and the first adjustment instruction is generated: reduce the temperature of the low-temperature reaction section and increase the nitrogen flow rate in the low-temperature reaction section. When the methane content in the exhaust gas at the outlet of the high-temperature carbonization section exceeds the upper limit of the preset normal range and the specific surface area of ​​biochar is lower than the preset standard, the second abnormal scenario of "excessive moisture in the lees leading to incomplete pyrolysis" is determined to have occurred, and a second adjustment instruction is generated: extend the residence time of the composite particles in the low-temperature reaction section and increase the temperature of the high-temperature carbonization section. When the proportion of mesopores in biochar is lower than the preset standard, the third abnormal scenario of "insufficient porosity of biochar" is determined, and the third adjustment instruction is generated: increase the volume ratio of water vapor in the mixed atmosphere of the high-temperature carbonization section and extend the residence time of composite particles in the high-temperature carbonization section. When the temperature difference at different locations within the two-stage fluidized bed pyrolysis reactor exceeds the preset normal range, the fourth abnormal scenario of "particle stratification leading to uneven pyrolysis" is identified, and a fourth adjustment instruction is generated: increase the airflow velocity in the high-temperature carbonization section and decrease the feed rate of the two-stage fluidized bed pyrolysis reactor.

[0027] The central control unit's judgment and adjustment strategies for different abnormal scenarios ensure the stability of the pyrolysis process and the consistency of product quality. When it is determined that "excessive mud content leads to over-catalysis," the pyrolysis rate of starch is slowed down by lowering the temperature of the low-temperature reaction section and increasing the nitrogen flow rate, allowing sufficient time for starch to generate small-molecule organic matter to coat the catalytic sites, while diluting the catalytically active region. When it is determined that "excessive moisture in the distiller's grains leads to incomplete pyrolysis," the residence time in the low-temperature reaction section is extended and the temperature of the high-temperature carbonization section is increased to ensure sufficient evaporation of moisture and complete decomposition of starch residues. When it is determined that "insufficient porosity of biochar" is detected, the pore-expanding effect of water vapor is enhanced by increasing the proportion of water vapor and extending the residence time. When it is determined that "particle stratification leads to uneven pyrolysis," the particle stratification state is broken up by increasing the airflow velocity and reducing the feed rate. These targeted adjustment strategies ensure that the pyrolysis process remains stable and the product quality meets standards even under fluctuating raw material conditions. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the execution process of step S1 in the pyrolysis method for brewing waste provided by the present invention; Figure 2 This is a schematic diagram of the execution process of step S2 in the pyrolysis method for brewing waste provided by the present invention; Figure 3 This is an overall execution flowchart of the brewing waste pyrolysis method provided by the present invention; Figure 4 This is a schematic diagram of the starch-based composite adhesive provided by the present invention; Figure 5 This is a segmented operation diagram of the two-stage fluidized bed pyrolysis reactor provided by the present invention; Figure 6 This is a schematic diagram of the abnormal scene judgment and adjustment instruction generation rules built into the central control unit provided by the present invention.

[0029] List of reference numerals 100: Central control unit; 200: Temperature monitoring unit; 300: Gas composition monitoring unit; 400: Biochar characteristic monitoring unit. Detailed Implementation

[0030] The following is a detailed explanation with reference to the accompanying drawings.

[0031] like Figure 1 and Figure 2As shown, this invention discloses a method for pyrolysis of brewing waste based on dynamic monitoring and feedback control, which includes the following steps: S1. Fresh distiller's grains are first subjected to twin-screw low-temperature shearing to cut their cellulose fibers into short distiller's grains fibers and squeeze out some free water. Then, the cellar mud is subjected to vibration screening to remove impurities and airflow pulverization to refine it. Then, a starch-based composite binder with corn starch as the main film-forming substance and distiller's grains hydrolysate is prepared. Finally, the pretreated short distiller's grains fibers, cellar mud clay particles and starch-based composite binder are mixed and granulated by twin-screw spherical granulator and belt drying to form composite spherical particles. S2. First, the pretreated composite particles are pyrolyzed in the low-temperature reaction section of a two-stage fluidized bed pyrolysis reactor to generate small molecule organic matter that coats the catalytic active sites of the pit mud. Then, the particles treated in the low-temperature reaction section are pyrolyzed in the high-temperature carbonization section to completely release the starch residues and expand the pores with water vapor. Finally, the pyrolysis products in the high-temperature carbonization section are subjected to gas-solid separation by a cyclone separator, and the separated biochar is activated by passing water vapor to obtain the pyrolysis products.

[0032] Figure 3 The overall execution flow diagram of the brewing waste pyrolysis method of the present invention is shown.

[0033] Preferably, step S1 eliminates the density differences, particle agglomeration differences, and compatibility differences between the lees and cellar mud in the mixed raw materials through targeted physical treatment of the lees and cellar mud, functional preparation of starch-based composite binders, and implementation of specific granulation processes. This ultimately forms composite particles with uniform density, stable structure, and suitable subsequent pyrolysis characteristics, avoiding problems such as pyrolysis temperature fluctuations, biochar pore blockage, or excessive cracking of bio-oil caused by uneven raw materials.

[0034] Preferably, specific pretreatment processes can be adopted to achieve synergistic adaptation of raw material characteristics, taking into account the inherent high moisture content and fibrous structure of distiller's grains, as well as the high density and easy agglomeration characteristics of clay particles in pit mud.

[0035] Preferably, in step S1.1, the pretreatment of the distiller's grains may include: feeding fresh distiller's grains into a twin-screw cryogenic shearing machine for fiber shearing. The operating parameters of the twin-screw cryogenic shearing machine must meet the following requirements: the shearing speed is controlled within a range that can shear the cellulose fibers of the distiller's grains into short fibers, and the shearing temperature is controlled within a range lower than the starch gelatinization temperature, so as to ensure that while achieving fiber refinement, the residual starch in the distiller's grains does not gelatinize prematurely, causing the fibers to stick together and clump. Through this shearing process, on the one hand, the cellulose fibers in the distiller's grains can be sheared into short fibers of a specific length range, retaining the porous structure of the short fibers themselves. This porous structure can provide sufficient sites for the subsequent adhesion of starch-based composite binders. On the other hand, the mechanical extrusion generated during the shearing process can squeeze out some of the free water in the distiller's grains, reducing the moisture content of the distiller's grains to a suitable range for subsequent mixing and granulation, avoiding excessive moisture causing the granules to deform easily during granulation or excessive moisture causing the fibers to become brittle and easily break.

[0036] Preferably, in step S1.2, the pretreatment of the cellar mud may include: first, sending the cellar mud (clay content not less than 80%) into a vibrating screen for impurity removal treatment, so as to effectively intercept the impurities mixed in the cellar mud, including but not limited to the clumps of lees that fall off during the brewing process, soil particles around the cellar, and other solid debris; the cellar mud after screening is then sent into an air jet mill for particle refinement treatment. The air jet mill can crush the cellar mud particles into a specific particle size range. Through crushing treatment, the agglomeration of the cellar mud clay particles can be significantly reduced, so that the particle size of the cellar mud particles is matched with the length of the short fibers of the lees after the aforementioned pretreatment, avoiding uneven particle distribution during subsequent mixing and granulation due to excessively large cellar mud particle size, or excessive dust generated during granulation due to excessively small particle size.

[0037] Preferably, in step S1.3, the present invention prepares a starch-based composite binder (such as...) that combines viscosity, compatibility with raw materials, and subsequent pyrolysis functionality. Figure 4As shown in the figure, this method aims to effectively combine the short fibers of distiller's grains with the clay particles of the cellar mud, and to provide a foundation for the function of starch in the subsequent pyrolysis process. Preferably, corn starch can be selected as the main film-forming substance of the binder. The selection is based on the characteristics of low cost and gelatinization temperature that is compatible with the temperature of the pretreatment process in this stage, which can stably form a gelatinized system during subsequent stirring. Further, corn starch and water are mixed in a specific mass ratio to form a mixed system to meet the requirements of sufficient starch dispersion and subsequent formation of a suitable viscosity. This mass ratio can be controlled at about 1:3. At the same time, distiller's grains hydrolysate is added to the above mixed system. The preparation process of distiller's grains hydrolysate is as follows: a portion of fresh distiller's grains before pretreatment is taken, a dilute sulfuric acid solution is added, and a hydrolysis reaction is carried out at a specific temperature (such as about 80°C) to partially hydrolyze the cellulose in the distiller's grains into glucose and organic acids. The addition ratio of distiller's grains hydrolysate can be controlled at 2% to 3% of the total binder raw material mass. Its function is to use the glucose and organic acids in the hydrolysate to improve the compatibility between starch and pit mud clay particles, and to avoid the particles cracking easily after granulation due to insufficient interfacial bonding between starch and clay particles. At the same time, the glucose in the hydrolysate can serve as a supplementary carbon source in the subsequent pyrolysis process to increase the carbon content of biochar.

[0038] Preferably, the mixed raw materials are fed into a constant temperature mixing tank for mixing. The mixing temperature of the constant temperature mixing tank is controlled within the range that allows the starch to reach a semi-gelatinized state (e.g., 60~70℃), and the mixing speed is controlled within the range that allows the mixed raw materials to be evenly dispersed and avoids the generation of too many air bubbles (e.g., 140~160 r / min). The mixing time needs to continue until the mixed raw materials form a stable semi-gelatinized state, and the viscosity of the mixed raw materials is controlled within a specific range (e.g., 500~800 mPa·s) to form structurally stable composite particles.

[0039] Preferably, in step S1.4, after completing the pretreatment of the lees and cellar mud and preparing the starch-based composite binder, the pretreated lees short fibers, cellar mud clay particles and starch-based composite binder can be mixed to form spherical particles with interlocking structures, thereby achieving uniform density and structural stability of the mixed raw materials. Furthermore, the raw material ratio can be determined as follows: Based on the actual fluctuations in the clay content of the fermentation pit mud, the mass ratio of pretreated distiller's grains short fibers to fermentation pit mud clay particles is dynamically adjusted. This mass ratio can be controlled within the range of 8:2 to 9:1. The adjustment is based on ensuring that the final particle density formed after mixing different batches of raw materials can remain stable within a specific range, avoiding excessively high or low particle density due to excessively high fermentation pit mud content, which would affect the fluidization effect during subsequent pyrolysis. Simultaneously, the amount of starch-based composite binder added is controlled at 10% to 12% of the total mixed raw material mass. This amount ensures that the binder can fully coat the raw material particles, while avoiding excessive starch residue affecting biochar quality during subsequent pyrolysis due to excessive addition, or insufficient particle strength due to insufficient addition.

[0040] Preferably, the raw materials mixed in the above proportions are fed into a twin-screw spherical granulator for granulation. The screw speed of the twin-screw spherical granulator is controlled within a reasonable range (e.g., 110~130 r / min) to ensure that the raw materials are fully mixed and form spherical particles. The die aperture is selected to match the fluidization requirements of the subsequent pyrolysis equipment (two-stage fluidized bed pyrolysis reactor) (e.g., 2~4 mm). Through the extrusion of the twin screws and the forming action of the die, the raw materials are formed into spherical particles. During this process, the semi-gelatinized system of the starch-based composite binder coats the short fibers of distiller's grains and the clay particles of cellar mud. The short fibers of distiller's grains are interwoven in the coating layer, forming an interlocking structure of distiller's grains fiber, starch and cellar mud clay. This structure can effectively eliminate the density difference between distiller's grains and cellar mud, ensuring the density uniformity of the spherical particles.

[0041] Preferably, after granulation, the spherical particles are fed into a belt dryer for drying. The inlet air temperature of the belt dryer is controlled within a range that can quickly remove free water from the particle surface (e.g., 110~130℃), and the outlet air temperature is controlled within a range that can avoid residual moisture inside the particles and prevent excessive carbonization of starch (e.g., 55~65℃). The drying time needs to continue until the moisture content of the particles drops to a range suitable for subsequent pyrolysis (e.g., 15%~20%). The density of the dried spherical particles can be stably maintained at 1.3~1.6 g / cm³. 3Within this density range, the particle size can ensure good fluidization effect in subsequent fluidized bed pyrolysis, avoiding particle settling due to excessive density or being carried out by airflow due to insufficient density; the particle compressive strength is not less than 15N, which can meet the mechanical strength requirements of the particles during conveying and pyrolysis feeding, avoiding particle breakage and dust generation that could lead to local blockage or temperature fluctuations in the pyrolysis furnace.

[0042] Preferably, step S2 sets a two-stage temperature gradient and works in conjunction with water vapor to enable the starch in the pretreated composite particles to achieve a step-by-step function of low-temperature coating of catalytic sites and high-temperature in-situ pore formation. This simultaneously solves the problem of excessive catalysis of bio-oil cracking and blockage of biochar pores by the pit mud clay. At the same time, the atmosphere is controlled to optimize the pore structure and surface characteristics of biochar, laying the foundation for obtaining high-quality biochar in the future.

[0043] Preferably, step S2 can use a two-stage fluidized bed pyrolysis reactor as the reaction equipment. The selection is based on the fact that this equipment can achieve uniform heating and stable fluidization of the composite particles, and can independently control the temperature and atmosphere through segmented design, adapting to the needs of the starch step-by-step reaction, unlike conventional single-stage fixed-bed reactors which are prone to problems such as uneven particle heating and localized over-reaction. Figure 5 As shown, the two-stage fluidized bed pyrolysis reactor includes a low-temperature reaction section and a high-temperature carbonization section, arranged vertically upwards and downwards, with the low-temperature reaction section at the top and the high-temperature carbonization section at the bottom. A flow guide structure is installed between the two sections to ensure that the composite particles can smoothly enter the high-temperature carbonization section from the low-temperature reaction section, avoiding particle accumulation or short-circuiting. Both the low-temperature reaction section and the high-temperature carbonization section have independent temperature control and atmosphere control systems. The temperature control system can use electric heating or gas heating to achieve precise temperature control; the atmosphere control system precisely controls the type and flow rate of the incoming gas through a gas flow meter. An airflow distributor is installed at the bottom of the high-temperature carbonization section. The airflow distributor adopts a perforated plate structure with pore size adapted to the airflow velocity to ensure uniform gas distribution and avoid local airflow that is too fast, causing particle entrainment, or too slow, causing insufficient fluidization. An interface for a gas-solid separation device is installed at the top of the reactor for connecting to the subsequent tail gas treatment system. The effective volume of a two-stage fluidized bed pyrolysis reactor can be determined based on the throughput. The effective volume of the low-temperature reaction section must meet the residence time requirements of the composite particles in this section to ensure that the starch is fully pyrolyzed into small molecule organic matter. The effective volume of the high-temperature carbonization section must meet the requirements for complete pyrolysis of starch residues and pore expansion by water vapor. Usually, the ratio of the effective volumes of the low-temperature reaction section and the high-temperature carbonization section is controlled within a range that matches the residence time of the two sections. For example, when the effective volume of the low-temperature reaction section is a specific value, the effective volume of the high-temperature carbonization section is 1.5 to 2 times that value. The specific value can be adjusted according to the actual production capacity.

[0044] Preferably, the pretreated composite particles can enter the low-temperature reaction section to execute step S2.1. Preferably, the low-temperature reaction section is used to preferentially pyrolyze the starch in the composite particles to generate small-molecule organic matter. This small-molecule organic matter coats the catalytically active sites of the cellar mud clay, inhibiting the excessive catalysis of the pyrolysis products of the distiller's grains by the clay. The temperature range of the low-temperature reaction section is set to a range that allows partial pyrolysis but not complete decomposition of the starch. The specific temperature range can be determined according to the pyrolysis characteristics of the starch, for example, controlled within a specific medium-low temperature range (e.g., 350~450℃). This temperature range is lower than the temperature at which starch completely decomposes into gaseous products, ensuring that the starch pyrolysis generates small-molecule organic matter mainly composed of glucose and maltodextrin, rather than directly decomposing into gases such as carbon monoxide and carbon dioxide. If the temperature is too high, the starch will decompose rapidly and completely, failing to generate sufficient small-molecule organic matter for coating; if the temperature is too low, the starch pyrolysis rate will be too slow, failing to complete the reaction within the set residence time. The residence time in the low-temperature reaction section is set to allow for complete pyrolysis of starch into small-molecule organic compounds that can effectively coat the catalytic sites. The specific residence time can be determined based on the starch pyrolysis rate and the flow characteristics of the composite particles within the reactor, for example, controlled within a specific time range (e.g., 20-25 min). If the residence time is too short, the starch pyrolysis will be incomplete, resulting in poor coating; if the residence time is too long, secondary decomposition of the small-molecule organic compounds will occur, reducing coating efficiency. Nitrogen gas can be used as the atmosphere in the low-temperature reaction section. Nitrogen gas is uniformly introduced into the reactor through a gas flow distributor, with the flow rate set to maintain stable fluidization of the composite particles while isolating them from air (e.g., 0.5 m³ / min). 3 / h). Nitrogen serves two main purposes: firstly, it provides an inert environment for the pyrolysis reaction, preventing oxidation of the organic components in the composite particles; secondly, it drives the composite particles through airflow, ensuring sufficient contact between the particles and the temperature field and preventing localized overheating. Under these process parameters, after the composite particles enter the low-temperature reaction section, the starch first absorbs heat and undergoes pyrolysis. The resulting small-molecule organic matter adheres to the surface of the pit mud clay particles, combining with catalytically active sites such as aluminum and iron ions in the clay to form an organic coating layer. This coating layer blocks the contact between the catalytically active sites and the pyrolysis products of the distiller's grains fiber (such as L-glucan), thereby inhibiting excessive catalytic cracking of bio-oil by the clay and reducing the waste of organic carbon.

[0045] Preferably, the composite particles treated in the low-temperature reaction section can enter the high-temperature carbonization section to execute step S2.2. Preferably, the high-temperature carbonization section is used to further decompose and release the starch residues that were not completely decomposed in the low-temperature reaction section, achieving in-situ pore formation of biochar. At the same time, the biochar pores are expanded through the synergistic effect of water vapor, inhibiting the agglomeration and blockage of pores by clay particles, and improving the adsorption performance of biochar. The temperature range of the high-temperature carbonization section is set to a range that allows the starch residues to be completely decomposed and the distillers' grains fiber to be fully carbonized. The specific temperature range can be determined according to the starch residue decomposition temperature and the biochar carbonization requirements. For example, it can be controlled within a specific medium-high temperature range (such as 600~650℃). This temperature range is higher than the starch residue decomposition temperature, ensuring that the starch residues are completely decomposed into gaseous products such as hydrogen, carbon monoxide, and methane and released. At the same time, it can fully carbonize the organic components in the distillers' grains fiber to form a stable carbon skeleton. If the temperature is too high, it will lead to over-carbonization of biochar and collapse of the pore structure; if the temperature is too low, the starch residues will not be completely decomposed and effective pores cannot be formed. The residence time in the high-temperature carbonization section is set to allow for complete pyrolysis of starch residues and sufficient pore-expanding effect of water vapor. The specific residence time can be determined based on the pyrolysis rate of starch residues and the gasification reaction rate of water vapor, for example, controlled within a specific range (e.g., 30-35 min). If the residence time is too short, starch residues will not completely escape, resulting in insufficient porosity; if the residence time is too long, it will lead to a decrease in biochar carbon yield. The atmosphere in the high-temperature carbonization section can be a mixture of nitrogen and water vapor. The volume ratio of nitrogen to water vapor is set to maintain an inert environment and ensure that water vapor exerts its pore-expanding effect (e.g., a volume ratio of 9:1). The total flow rate of the mixed gas is set to maintain stable fluidization of the composite particles and meet the requirements of the gasification reaction (e.g., 0.8 m). 3 The role of water vapor mainly includes two aspects: First, it reacts with the surface of biochar through a gasification reaction (reaction formula: C + H₂O → CO + H₂). This reaction can form new pores on the surface of biochar and expand the original pores left by the escape of starch residues, thus expanding the pore size of biochar from the mesoporous range to a more suitable adsorption range. Second, water vapor can dilute the catalytically active area around the pit mud clay, further weakening the adsorption effect of clay on bio-oil and indirectly increasing the yield of bio-oil. Under these process parameters, after the composite particles are treated in the low-temperature reaction section, they enter the high-temperature carbonization section. The starch residues are completely decomposed and escaped at high temperature, leaving a large number of uniformly sized mesopores inside the biochar. At the same time, the water vapor reacts with the surface of biochar through a gasification reaction, further optimizing the pore structure. The residual starch carbon skeleton can support the biochar structure and prevent the pit mud clay particles from agglomerating and blocking the pores at high temperature, ultimately forming a biochar intermediate with high porosity and stable structure.

[0046] Preferably, in step S2.3, the pyrolysis products (including biochar, gaseous products, and a small amount of dust) generated in the high-temperature carbonization section can enter a cyclone separator for gas-solid separation. The biochar collected by the cyclone separator can then enter a low-temperature activation machine for activation treatment; during the activation process, a specific volume fraction (e.g., about 5%) of water vapor is introduced to effectively remove residual carbon residue. The water vapor can react with the residual starch carbon residue on the surface of the biochar, converting it into gaseous products that escape, and can also slightly expand the pores, improving the adsorption performance of the biochar.

[0047] Preferably, during the pyrolysis reaction process in the two-stage fluidized bed pyrolysis reactor (i.e., step S2), multiple parameters can be monitored in real time to perform collaborative data analysis based on the monitoring data, thereby achieving dynamic adjustment of the process. In particular, by constructing a closed-loop control system, the compositional fluctuations of the pretreated composite particles (such as changes in cellar mud content, differences in the moisture content of distiller's grains, etc.) can be precisely adapted to ensure that the functions of low-temperature coating of catalytic sites and high-temperature in-situ pore formation of starch are stably performed during the step-by-step pyrolysis process, avoiding problems such as pyrolysis reaction imbalance and substandard product quality caused by fluctuations in raw material characteristics.

[0048] Preferably, a temperature monitoring unit 200 can be configured within the two-stage fluidized bed pyrolysis reactor to collect temperature data from different regions within the reactor in real time, preventing uneven pyrolysis reactions caused by localized temperature deviations. The temperature monitoring unit 200 can be a sheathed thermocouple sensor, such as a K-type sheathed thermocouple sensor, whose measurement accuracy reaches a specific range, ensuring the accuracy of the temperature data. Multiple sets of temperature monitoring units 200 are arranged in the low-temperature reaction section and the high-temperature carbonization section of the two-stage fluidized bed pyrolysis reactor, respectively. The number of temperature monitoring units 200 in each set can be determined according to the reactor's volume and temperature distribution characteristics; for example, three sets can be arranged in each section, with the three sets of temperature monitoring units 200 installed in the middle, left, and right positions of each section, respectively. The sensors can be installed using an insertion method, with the insertion depth reaching the material flow area within the reactor, ensuring direct contact with the composite particles and the pyrolysis atmosphere, and avoiding shallow installation that would result in detecting the gas phase temperature rather than the actual material temperature.

[0049] Preferably, a gas component monitoring unit 300 can be configured within the two-stage fluidized bed pyrolysis reactor to analyze in real time the content of key gas components in the tail gas exiting the high-temperature carbonization section of the reactor. The gas component ratio is used to determine the progress of the pyrolysis reaction, particularly the catalytic activity and completeness of the pyrolysis of the pit mud clay. The gas component monitoring unit 300 can be an online gas chromatograph, which must be capable of rapidly detecting gas components such as carbon monoxide, carbon dioxide, and methane, and its detection accuracy must be sufficient to capture minute changes in gas components. The online gas chromatograph can be installed on the tail gas pipeline at the outlet of the high-temperature carbonization section, with a tail gas cooling device and a gas filtration device installed before the installation location. Data such as the carbon monoxide to carbon dioxide ratio and methane content are obtained in real time using an online gas chromatograph. The carbon monoxide to carbon dioxide ratio reflects the catalytic activity of the cellar mud clay. A ratio that is too high indicates that the catalytic activity is too strong, leading to over-catalysis, while a ratio that is too low indicates that the pyrolysis reaction is incomplete. A methane content that is too high indicates that the organic components in the lees have not been fully carbonized and that the degree of pyrolysis is insufficient.

[0050] Preferably, the present invention may also be configured with a biochar characteristic monitoring unit 400 for real-time detection of key characteristic parameters of biochar generated by the pyrolysis reaction, so as to directly determine whether the biochar quality meets the standards, especially the specific surface area and mesopore ratio of biochar, which are the core indicators for measuring the adsorption performance of biochar. The biochar characteristic monitoring unit 400 may be an online porosity analyzer. The online porosity analyzer has the function of rapidly detecting the specific surface area and pore size distribution of solid materials. Its detection principle can be based on dynamic gas adsorption, and the detection accuracy is sufficient to distinguish subtle differences in biochar characteristics. The online porosity analyzer can be installed on the outlet pipe of a cyclone separator. The cyclone separator is used to separate biochar and gas in the pyrolysis products. The separated biochar will briefly remain in the outlet pipe. The online porosity analyzer obtains biochar samples through a sampling device. The sampling frequency needs to match the continuous production rhythm of the pyrolysis process to ensure real-time reflection of the changing trend of biochar quality.

[0051] Preferably, the central control unit 100 can be used to collect data from each monitoring unit and perform data analysis, thereby issuing adjustment commands to the actuators of the two-stage fluidized bed pyrolysis reactor. The central control unit 100 can be a PLC control system, whose built-in data processing program can compare the collected temperature data, gas composition data, and biochar characteristic data with preset standard ranges based on the reaction law of the pyrolysis process and the functional requirements of starch. When some data exceeds the standard range, it is automatically determined to be an abnormal scenario, and the corresponding parameter adjustment strategy is invoked to generate adjustment commands and send them to the relevant actuators.

[0052] Preferably, such as Figure 6As shown, when the gas component monitoring unit 300 detects that the ratio of carbon monoxide to carbon dioxide in the exhaust gas at the outlet of the high-temperature carbonization section exceeds the upper limit of the preset normal range (e.g., 1.2), and the bio-oil yield is lower than the preset standard (e.g., 22%), the central control unit 100 can determine it as the first abnormal scenario of "excessive catalysis due to excessive silt content". At this time, the central control unit 100 can generate a first adjustment command and issue it to the actuator of the two-stage fluidized bed pyrolysis reactor. The first adjustment command may include two commands: the first command is to adjust the temperature control system of the low-temperature reaction section, reducing the temperature of the low-temperature reaction section to near the lower limit of the preset normal temperature range (e.g., 330~350℃). By reducing the temperature, the pyrolysis rate of starch is slowed down, allowing starch more time to generate small molecule organic matter, thereby more fully coating the catalytic active sites of the silt clay; the second command is to adjust the atmosphere control system of the low-temperature reaction section, increasing the nitrogen flow rate to near the upper limit of the preset normal flow rate range (e.g., 0.7m). 3 By increasing the nitrogen flow rate ( / h), the catalytically active zone around the pit mud clay is diluted, further reducing the intensity of the catalytic reaction and preventing excessive cracking of the bio-oil.

[0053] Preferably, such as Figure 6 As shown, when the gas component monitoring unit 300 detects that the methane content in the exhaust gas at the outlet of the high-temperature carbonization section exceeds the preset upper limit of the normal range (e.g., 8%), and the online porosity analyzer detects that the specific surface area of ​​the biochar is lower than the preset standard (e.g., 150m²), the following conditions will be met: 2 When the moisture content of the lees is too high ( / g), the central control unit 100 can determine that this is the second abnormal scenario, namely "incomplete pyrolysis due to excessive moisture content in the lees". At this time, the central control unit 100 can generate a second adjustment command, which may include two adjustment commands: the first command is to adjust the material conveying system of the two-stage fluidized bed pyrolysis reactor, extending the residence time of the composite particles in the low-temperature reaction section to near the upper limit of the preset normal residence time range (e.g., 28~30 min). By extending the residence time, the moisture in the composite particles has more time to evaporate and escape, avoiding the influence of residual moisture on the subsequent carbonization reaction. The second command is to adjust the temperature control system of the high-temperature carbonization section, raising the temperature of the high-temperature carbonization section to near the upper limit of the preset normal temperature range (e.g., 650~680℃). By raising the temperature, the intensity of the pyrolysis reaction of starch residues is enhanced, ensuring that the starch residues can be completely decomposed and escaped, providing a guarantee for sufficient pores to form biochar, while promoting the further carbonization of the insufficiently carbonized organic components in the lees.

[0054] Preferably, such as Figure 6As shown, when the online porosity analyzer detects that the mesopore ratio of biochar is lower than the preset standard (e.g., 50%), the central control unit 100 can determine it as the third abnormal scenario of "insufficient biochar porosity". At this time, the central control unit 100 can generate a third adjustment command, which may include two adjustment commands: The first command is to adjust the atmosphere control system of the high-temperature carbonization section, increase the volume ratio of water vapor in the mixed atmosphere to near the upper limit of the preset normal ratio range (e.g., 15%), and enhance the intensity of the gasification reaction between water vapor and the surface of biochar by increasing the water vapor content. This reaction can form new pores on the surface of biochar and expand the original pores left by the escape of starch residues; The second command is to adjust the residence time of the composite particles in the high-temperature carbonization section, extend the residence time to near the upper limit of the preset normal residence time range (e.g., 38~40 min), and ensure that water vapor has more time to react with biochar, avoiding poor pore expansion effect due to insufficient reaction time.

[0055] Preferably, such as Figure 6 As shown, when the temperature monitoring unit 200 detects a temperature difference exceeding the preset normal range (e.g., 15°C) at different locations within the two-stage fluidized bed pyrolysis reactor, the central control unit 100 can determine it as the fourth abnormal scenario: "particle stratification leading to uneven pyrolysis." At this time, the central control unit 100 can generate a fourth adjustment command, which may include two adjustments: the first command adjusts the airflow distributor at the bottom of the high-temperature carbonization section, increasing the airflow velocity to near the upper limit of the preset normal velocity range (e.g., 1.5 m / s). This enhances the disturbance effect of the airflow on the composite particles, breaking the stratification caused by density differences and allowing the composite particles to be evenly distributed within the reactor. The second command adjusts the reactor's feeding system, reducing the feed rate to near the lower limit of the preset normal rate range (e.g., a 10% reduction). This reduces the feed amount per unit time, providing more space for the uniform distribution and sufficient heating of the composite particles within the reactor, preventing particle accumulation due to excessive feed and further exacerbating the stratification phenomenon.

[0056] It should be noted that the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this invention, and these solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and do not constitute a limitation on the claims. The scope of protection of this invention is defined by the claims and their equivalents. This specification contains multiple inventive concepts; phrases such as "preferred" or "according to a preferred embodiment" indicate that the corresponding paragraph discloses an independent concept. The applicant reserves the right to file divisional applications based on each inventive concept. Throughout the text, the feature introduced by "preferred" is only an optional mode and should not be construed as mandatory. Therefore, the applicant reserves the right to abandon or delete relevant preferred features at any time.

Claims

1. A method for pyrolysis of brewing waste based on dynamic monitoring and feedback control, characterized in that, It includes the following steps: S1. Fresh distiller's grains are first subjected to twin-screw low-temperature shearing to cut their cellulose fibers into short distiller's grains fibers and squeeze out some free water. Then, the cellar mud is subjected to vibration screening to remove impurities and airflow pulverization to refine it. Then, a starch-based composite binder with corn starch as the main film-forming substance and distiller's grains hydrolysate is prepared. Finally, the pretreated short distiller's grains fibers, cellar mud clay particles and starch-based composite binder are mixed and granulated by twin-screw spherical granulator and belt drying to form composite spherical particles. S2. First, the pretreated composite particles are pyrolyzed in the low-temperature reaction section of a two-stage fluidized bed pyrolysis reactor to generate small-molecule organic matter that coats the catalytic active sites of the pit mud. Then, the particles treated in the low-temperature reaction section are subjected to a high-temperature carbonization section to completely decompose and release the starch residues, and combine with water vapor to expand the pores. Finally, the pyrolysis products from the high-temperature carbonization section are subjected to gas-solid separation by a cyclone separator, and the separated biochar is activated by passing water vapor to obtain the pyrolysis products. In step S2, the process parameters are dynamically adjusted through multi-parameter real-time monitoring by several monitoring units and closed-loop control by the central control unit (100) to ensure the stability of the pyrolysis reaction and the quality of the product. The data collected by the several monitoring units include temperature data, gas composition data and / or biochar characteristic data.

2. The method according to claim 1, characterized in that, In the preparation of starch-based composite binder in step S1, corn starch and water are first mixed to form a mixed system; then, distillers' grains hydrolysate is added to the mixed system. The preparation process of the distillers' grains hydrolysate is as follows: take a portion of fresh distillers' grains before pretreatment, add dilute sulfuric acid solution to carry out a hydrolysis reaction, so that the cellulose in the distillers' grains is partially hydrolyzed to generate glucose and organic acids.

3. The method according to claim 1 or 2, characterized in that, In step S1, the pretreated short fibers of distiller's grains, clay particles of cellar mud and starch-based composite binder are mixed and then fed into a constant temperature mixing tank for stirring. The stirring temperature and stirring speed of the constant temperature mixing tank are controlled so that the mixed raw materials form a stable semi-gelatinized state after continuous stirring, and the mixed raw materials are evenly dispersed and excessive bubbles are avoided.

4. The method according to any one of claims 1 to 3, characterized in that, In the twin-screw spherical granulation process in step S1, the screw speed of the twin-screw spherical granulator is controlled to achieve full mixing of raw materials and the formation of spherical particles. During the granulation process, the semi-gelatinized system of starch-based composite binder coats the short fibers of distiller's grains and the clay particles of cellar mud. The short fibers of distiller's grains are interwoven in the coating layer to form an interlocking structure of distiller's grains, starch and cellar mud. This interlocking structure effectively eliminates the density difference between distiller's grains and cellar mud, ensuring the density uniformity of the spherical particles.

5. The method according to any one of claims 1 to 4, characterized in that, In the two-stage fluidized bed pyrolysis reactor used in step S2, the low-temperature reaction section is located at the top and the high-temperature carbonization section is located at the bottom. A flow guiding structure is set between the two sections to ensure that the composite particles smoothly enter the high-temperature carbonization section from the low-temperature reaction section. Both the low-temperature reaction section and the high-temperature carbonization section have independent temperature control systems and atmosphere control systems. The temperature control system uses electric heating or gas heating to achieve temperature regulation, and the atmosphere control system controls the type and flow rate of the incoming gas through a gas flow meter.

6. The method according to any one of claims 1 to 5, characterized in that, In the low-temperature reaction section of step S2, the temperature of the low-temperature reaction section is controlled below the temperature at which starch is completely decomposed into gaseous products, ensuring that starch pyrolysis generates small molecule organic compounds, mainly glucose and maltodextrin. The residence time of the low-temperature reaction section is controlled within the range that ensures that starch is fully pyrolyzed to generate small molecule organic compounds and that these organic compounds effectively coat the catalytic active sites of the pit mud. The atmosphere of the low-temperature reaction section is nitrogen, which is uniformly introduced into the reactor through an airflow distributor.

7. The method according to any one of claims 1 to 6, characterized in that, In the high-temperature carbonization section of step S2, the temperature of the high-temperature carbonization section is controlled in a range higher than the pyrolysis temperature of starch residues to ensure that the starch residues are completely decomposed into gaseous products such as hydrogen, carbon monoxide, and methane and escape, while the organic components in the distillers' grains fiber are fully carbonized to form a stable carbon skeleton; the residence time of the high-temperature carbonization section is controlled in a range that ensures the complete pyrolysis of starch residues and that water vapor fully exerts its pore-expanding effect; the atmosphere of the high-temperature carbonization section is a mixture of nitrogen and water vapor.

8. The method according to any one of claims 1 to 7, characterized in that, In the biochar activation process in step S2, the biochar collected by the cyclone separator is sent to a low-temperature activator. During the activation process, water vapor is introduced so that the water vapor reacts with the residual starch carbon residue on the surface of the biochar, converting it into gaseous products to remove the residual carbon residue. On the other hand, the water vapor further expands the pores of the biochar and improves its adsorption performance.

9. The method according to any one of claims 1 to 8, characterized in that, The central control unit (100) is used to collect data collected by each monitoring unit and perform data calculation and analysis. When an abnormal scenario is determined, it issues an adjustment command to the actuator of the two-stage fluidized bed pyrolysis reactor. The monitoring unit includes a temperature monitoring unit (200) for collecting temperature data, a gas component monitoring unit (300) for collecting gas component data, and / or a biochar characteristic monitoring unit (400) for collecting biochar characteristic data.

10. The method according to any one of claims 1 to 9, characterized in that, The central control unit (100) can be configured to: When the ratio of carbon monoxide to carbon dioxide in the exhaust gas at the outlet of the high-temperature carbonization section exceeds the upper limit of the preset normal range and the bio-oil yield is lower than the preset standard, the first abnormal scenario of "excessive sludge content leading to over-catalysis" is determined to have occurred, and the first adjustment instruction is generated: reduce the temperature of the low-temperature reaction section and increase the nitrogen flow rate in the low-temperature reaction section. When the methane content in the exhaust gas at the outlet of the high-temperature carbonization section exceeds the upper limit of the preset normal range, and the specific surface area of ​​biochar is lower than the preset standard, the second abnormal scenario of "excessive moisture in the lees leading to incomplete pyrolysis" is determined to have occurred, and a second adjustment instruction is generated: extend the residence time of the composite particles in the low-temperature reaction section and increase the temperature of the high-temperature carbonization section. When the proportion of mesopores in biochar is lower than the preset standard, the third abnormal scenario of "insufficient porosity of biochar" is determined, and the third adjustment instruction is generated: increase the volume ratio of water vapor in the mixed atmosphere of the high-temperature carbonization section and extend the residence time of composite particles in the high-temperature carbonization section. When the temperature difference at different locations within the two-stage fluidized bed pyrolysis reactor exceeds the preset normal range, the fourth abnormal scenario of "particle stratification leading to uneven pyrolysis" is determined to have occurred, and a fourth adjustment instruction is generated: increase the airflow velocity in the high-temperature carbonization section and reduce the feed rate of the two-stage fluidized bed pyrolysis reactor.

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