A method and equipment for synergistic modification of distiller's grains through drying, pyrolysis, and activation.

Abstract

This invention discloses a method and equipment for the synergistic modification of distillers' grains through drying, pyrolysis, and activation in the field of solid waste disposal technology. The method mainly includes steps such as distillers' grains pretreatment, gradient drying, precise pyrolysis, adjustment of solid activation and modification reagents, isothermal activation, and product post-treatment. The three-stage gradient drying process ensures good drying uniformity, low energy consumption, and high product quality, avoiding premature decomposition and coking of organic matter caused by localized overheating. Precise formulation of different solid activation reagents and activation parameters according to the target product application significantly improves the adsorption effect of adsorption-type modified biochar and the specific surface area and specific capacitance of energy storage electrode-type modified biochar, thereby increasing the utilization value of distillers' grains. The equipment includes six sequentially connected functional units, a control system, and a heat circulation system. By adjusting the process parameters of each unit, the targeted preparation and flexible switching of two high-value products—adsorption materials and energy storage electrodes—can be achieved within the same equipment system.

Description

Technical Field

[0001] This invention relates to the field of solid waste disposal technology, and in particular to a method and equipment for the synergistic modification of distillers' grains by drying, pyrolysis, and activation. Background Technology

[0002] Distillers' grains are a common solid byproduct of the brewing industry, rich in cellulose, lignin, protein and other components. Currently, they are mainly used for processing feed, fertilizer and other products, but they have problems such as high energy consumption, large land area required for processing, and underutilization of their high-value potential.

[0003] Pyrolysis technology can convert distiller's grains into high-value-added products such as biochar and biomass gas, but traditional processes have the following shortcomings: First, the high moisture content of distiller's grains leads to high pyrolysis energy consumption and unstable product quality; second, pyrolytic biochar has few pores and low activity, limiting its application; third, the formulation of activating reagents lacks specificity, failing to adjust modification conditions based on the physicochemical properties of distiller's grains, resulting in inconsistent modification effects; and fourth, the equipment has a single function and independent processes, failing to achieve integrated continuous production to meet the needs of various char materials, thus hindering industrial promotion.

[0004] Among the existing publicly available technologies, patent CN202310955374.8 discloses a reuse method for treating baijiu lees, which uses indirect steam heat exchange drying and segmented pyrolysis, but does not achieve the synergistic linkage of drying-pyrolysis-activation, nor does it involve activation modification to prepare high-performance adsorbent materials or energy storage electrodes; patent CN202511647364.3 discloses a green and low-carbon resource utilization and energy conversion coupling method for brewing waste, but does not involve the modification treatment of baijiu lees char; patent CN202311629468.2 discloses a method for multi-scale preparation of flower-shaped biochar balls and lignin-based carbon dots from waste baijiu lees. Although it provides a method for modifying baijiu lees char, it adopts a process route of low eutectic solvent separation + hydrothermal + co-grinding, and does not have a corresponding industrial process and special equipment, which is not conducive to the large-scale application of baijiu lees char.

[0005] Overall, existing pyrolysis technology for distiller's grains still has significant room for improvement in terms of activation regulation mechanisms, specialized equipment, pyrolysis efficiency, and integrated continuous production. Therefore, there is an urgent need to develop efficient and synergistic modification methods and supporting specialized equipment to achieve synergistic linkage and industrial application of the entire process of distiller's grains drying-pyrolysis-activation. Summary of the Invention

[0006] To overcome the shortcomings of existing methods for recycling and processing distiller's grains, the technical problem to be solved by this invention is to provide a method and equipment for the synergistic modification of distiller's grains through drying, pyrolysis, and activation, which enables efficient, continuous, and high-value-added production of distiller's grain charcoal.

[0007] The technical solution adopted by this invention to solve its technical problem is: A method for synergistic modification of distiller's grains through drying, pyrolysis, and activation includes the following steps: S1. Distillers' grains pretreatment: Remove impurities from the distillers' grains and detect the characteristics of the components of the distillers' grains, including water content, pH value, starch content, crude fiber content and crude protein content; S2. Gradient Drying: Based on the detected characteristics of the lees composition, the drying parameters are adjusted, and the lees are subjected to a three-stage drying process: preheating, constant-rate drying, and cooling. The preheating stage is conducted at a temperature of 60-80℃ for 20-30 minutes; the constant-rate stage is conducted at a temperature of 100-120℃ for 30-40 minutes; and the cooling stage is conducted at a temperature of 80-90℃ for 10-15 minutes. The final moisture content of the lees is controlled at 8%-15%. S3. Precise pyrolysis: Under inert gas protection, the temperature is increased at a rate of 5-15℃ / min to carry out two-stage pyrolysis of the lees. The first stage of pyrolysis is at a temperature of 300-400℃ and a holding time of 20-30 min. The second stage of pyrolysis is at a temperature of 500-700℃ and a holding time of 90-150 min. S4. Adjustment of Activation Modifier: Select different solid activation reagents according to the intended use of the target product. Feed the pyrolytic biochar obtained in S3 into a ball mill, add the solid activation reagent, and grind and mix for 10-40 min. When the target product is an adsorbent material, the solid activation reagent is one or a mixture of FeCl3 and K2CO3. When the target product is an energy storage electrode, the solid activation reagent is a mixture of urea and K2CO3. S5. Isothermal activation: The mixture obtained in S4 is activated under inert gas protection at an isothermal rate of 5℃ / min, with an activation temperature of 400-650℃ and an activation time of 30-100 min. S6. Product post-processing: Cool, wash until neutral and dry the product obtained in S5.

[0008] Furthermore, in step S2, adjusting the drying parameters according to the characteristics of the distillers' grains includes: when the moisture content of the distillers' grains is higher than 60%, the temperature of the preheating section should not exceed 70°C, and the drying time should be 25-30 minutes; when the starch content of the distillers' grains is higher than 12%, the temperature of the constant-speed section should not exceed 110°C to avoid starch gelatinization; when the crude fiber content of the distillers' grains is higher than 25%, the temperature of the constant-speed section should not be lower than 110°C to compensate for the low thermal conductivity of the crude fiber; when the crude protein content of the distillers' grains is higher than 20%, the temperature of the cooling section should not exceed 85°C to prevent excessive denaturation and coking of the protein.

[0009] Furthermore, in step S2, the temperature of the preheating section is 70°C and the drying time is 25 min; the temperature of the constant rate section is 110°C and the drying time is 35 min; the temperature of the cooling section is 85°C and the drying time is 12 min, ultimately controlling the moisture content of the lees at 10%.

[0010] Furthermore, in step S3, the pyrolysis heating rate is 10 ℃ / min, the pyrolysis temperature in the low-temperature section is 350℃, the holding time is 25 min, the pyrolysis temperature in the high-temperature section is 600℃, and the holding time is 120 min; the inert gas flow rate is controlled at 100-500 mL / min.

[0011] Furthermore, in step S4, the selection of different solid activating reagents according to the intended use of the target product includes: when the target product is an adsorbent material, selecting one of FeCl3 and K2CO3 or a composite reagent mixed in a mass ratio of 1:1-2:1, with a particle size of 0.1-0.5 mm, a mass ratio of solid activating reagent to biochar of 1:1-1:5, and a ball mill speed of 200-400 r / min; when the target product is an energy storage electrode, selecting a composite reagent mixed with urea and K2CO3 in a mass ratio of 1:0.5-1:2, with a particle size of 0.05-0.15 mm, a mass ratio of solid activating reagent to biochar of 1:3-1:6, and a ball mill speed of 200-300 r / min.

[0012] Furthermore, in step S5, different activation temperatures and activation times are used depending on the intended use of the target product. The adsorbent material is activated at a constant temperature of 400-650℃ for 30-100 min; the energy storage electrode is activated at a constant temperature of 400-550℃ for 30-90 min.

[0013] Furthermore, in steps S4 and S5, the solid activator selected for the adsorbent material is a composite reagent of K2CO3 and FeCl3 mixed in a mass ratio of 1:1, with a particle size of 0.2-0.3 mm. The mass ratio of the composite reagent to biochar is 1:3. The ball mill speed is 300 r / min, the grinding time is 25 min, and the activation is carried out at a constant temperature of 550℃ for 60 min. The solid activator selected for the energy storage electrode is a composite reagent of urea and K2CO3 mixed in a mass ratio of 1:1, with a particle size of 0.08-0.15 mm. The mass ratio of the composite reagent to biochar is 1:4. The ball mill speed is 250 r / min, the grinding time is 35 min, and the activation is carried out at a constant temperature of 450℃ for 60 min.

[0014] This invention also provides a compatible device for the above-mentioned synergistic modification method of lees drying, pyrolysis, and activation. It mainly includes a pretreatment unit, a gradient drying unit, a precise pyrolysis unit, an activation adjustment unit, a constant-temperature activation unit, and a product post-treatment unit connected in sequence, as well as a control system and a heat circulation system. The control system employs a programmable logic controller (PLC) to link the sensors and actuators of each unit, preset multiple sets of compatibility parameters, and control the continuous operation of each equipment unit. The pretreatment unit includes component detection equipment for detecting the moisture content, pH value, starch content, crude fiber content, and crude protein content of the lees. The component detection equipment is electrically connected to the control system and is used to feed back the detection data to the control system to automatically adjust the process parameters of each unit.

[0015] Furthermore, the gradient drying unit includes a three-section drying chamber, a conveyor belt, a gradient heating device, and a moisture content monitor; the precision pyrolysis unit includes a pyrolysis furnace and an inert gas generator; the activation and adjustment unit includes a weighing scale and a ball mill; the constant temperature activation unit includes an activation furnace, which shares an inert gas generator with the precision pyrolysis unit; the product post-processing unit includes a washing tank, a centrifuge, and a dryer; and the heat circulation system is used to recover heat from the high-temperature gas generated by the precision pyrolysis unit and to use the recovered heat in the gradient drying unit and the product post-processing unit.

[0016] Furthermore, the activation adjustment unit includes at least three solid reagent storage chambers spaced apart along the running direction of the conveyor belt. Each solid reagent storage chamber has a weighing scale at its bottom outlet, with the outlet of the weighing scale located above the conveyor belt. A mixing chamber is located at the tail end of the conveyor belt, and the outlet of the mixing chamber is connected to the ball mill.

[0017] The beneficial effects of this invention are: 1. By detecting the five components of the lees—moisture content, pH value, starch content, crude fiber content, and crude protein content—during the pretreatment stage, and dynamically adjusting the temperature and time parameters of each stage of the three-stage gradient drying process, as well as the type and ratio of activating reagents, the drying process can be precisely controlled according to the physicochemical properties of different lees. This results in high-quality pyrolytic biochar with uniform moisture content, no coking on the surface, and well-developed internal pores. This lays a uniform and consistent precursor foundation for subsequent activation and modification, achieving a precise match between raw material characteristics, process parameters, and product performance. The same equipment and process can be adapted to different lees raw materials such as strong-aroma, sauce-aroma, and light-aroma types, all yielding high-performance modified biochar products.

[0018] 2. Depending on the intended use of the target product—either as an adsorbent material or an energy storage electrode—different combinations of solid activating reagents were selected and uniformly mixed using a ball milling dry method. When the target product was an adsorbent material, the microporous etching ability of K₂CO₃ and the mesoporous catalysis and iron oxide adsorption sites of FeCl₃ were utilized to form a multi-level pore structure with micropores, mesopores, and macropores, significantly improving the adsorption effect of biochar. When the target product was an energy storage electrode, a mixture of urea and K₂CO₃ was used. The pore-forming effect of K₂CO₃ and the synergistic effect of nitrogen doping of urea significantly increased the specific surface area and specific capacitance of the biochar. These two activating reagent formulations, in conjunction with the detection data of distiller's grains components, enabled the targeted preparation and flexible switching of two high-value products—adsorbent materials and energy storage electrodes—within the same equipment system. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a circuit diagram of the distillers' grains drying-pyrolysis-activation formulation equipment of the present invention; Figure 3 This is a schematic diagram of the apparatus for mixing biochar and reagents according to the present invention.

[0020] The components in the diagram are labeled as follows: 1-Pretreatment unit, 2-Gradient drying unit, 3-Precision pyrolysis unit, 4-Heat circulation system, 5-Activation and adjustment unit, 6-Ball mill, 7-Constant temperature activation unit, 8-Product post-processing unit, 9-Solid reagent storage chamber, 10-Measuring scale, 11-Mixing chamber. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] The present invention provides a method for synergistic modification of distiller's grains through drying, pyrolysis, and activation, the specific process of which is as follows: Figure 1 As shown, it includes the following steps: S1. Distillers' grains pretreatment: Remove impurities from the distillers' grains and detect the characteristics of the components of the distillers' grains, including water content, pH value, starch content, crude fiber content and crude protein content; S2. Gradient Drying: Based on the detected characteristics of the lees composition, the drying parameters are adjusted, and the lees are subjected to a three-stage drying process: preheating, constant-rate drying, and cooling. The preheating stage is conducted at a temperature of 60-80℃ for 20-30 minutes; the constant-rate stage is conducted at a temperature of 100-120℃ for 30-40 minutes; and the cooling stage is conducted at a temperature of 80-90℃ for 10-15 minutes. The final moisture content of the lees is controlled at 8%-15%. S3. Precise pyrolysis: Under inert gas protection, the temperature is increased at a rate of 5-15℃ / min to carry out two-stage pyrolysis of the lees. The first stage of pyrolysis is at a temperature of 300-400℃ and a holding time of 20-30 min. The second stage of pyrolysis is at a temperature of 500-700℃ and a holding time of 90-150 min. S4. Adjustment of Activation Modifier: Select different solid activation reagents according to the intended use of the target product. Feed the pyrolytic biochar obtained in S3 into a ball mill, add the solid activation reagent, and grind and mix for 10-40 min. When the target product is an adsorbent material, the solid activation reagent is one or a mixture of FeCl3 and K2CO3. When the target product is an energy storage electrode, the solid activation reagent is a mixture of urea and K2CO3. S5. Isothermal activation: The mixture obtained in S4 is activated under inert gas protection at an isothermal rate of 5℃ / min, with an activation temperature of 400-650℃ and an activation time of 30-100 min. S6. Product post-processing: Cool, wash until neutral and dry the product obtained in S5.

[0023] The preferred option is: In step S2, adjusting the drying parameters according to the characteristics of the lees composition includes: when the moisture content of the lees is higher than 60%, the preheating temperature should not exceed 70℃, and the drying time should be 25-30 min; when the starch content of the lees is higher than 12%, the constant-rate temperature should not exceed 110℃ to avoid starch gelatinization; when the crude fiber content of the lees is higher than 25%, the constant-rate temperature should not be lower than 110℃ to compensate for the low thermal conductivity of crude fiber; when the crude protein content of the lees is higher than 20%, the cooling temperature should not exceed 85℃ to prevent excessive protein denaturation and coking. Therefore, the comprehensive optimized parameters can be set as follows: the preheating temperature is 70℃, and the drying time is 25 min; the constant-rate temperature is 110℃, and the drying time is 35 min; the cooling temperature is 85℃, and the drying time is 12 min, ultimately controlling the moisture content of the lees to 10%.

[0024] In step S3, the pyrolysis heating rate is 10 ℃ / min, the pyrolysis temperature in the low-temperature section is 350℃ and the holding time is 25min, the pyrolysis temperature in the high-temperature section is 600℃ and the holding time is 120min; the inert gas flow rate is controlled at 100-500 mL / min.

[0025] In step S4, the selection of different solid activating reagents according to the intended use of the target product includes: when the target product is an adsorbent material, selecting one of FeCl3 and K2CO3 or a composite reagent mixed in a mass ratio of 1:1-2:1, with a particle size of 0.1-0.5 mm, a mass ratio of solid activating reagent to biochar of 1:1-1:5, and a ball mill speed of 200-400 r / min; when the target product is an energy storage electrode, selecting a composite reagent mixed with urea and K2CO3 in a mass ratio of 1:0.5-1:2, with a particle size of 0.05-0.15 mm, a mass ratio of solid activating reagent to biochar of 1:3-1:6, and a ball mill speed of 200-300 r / min.

[0026] In step S5, different activation temperatures and activation times are used depending on the intended use of the target product. The adsorbent material is activated at a constant temperature of 400-650℃ for 30-100 min; the energy storage electrode is activated at a constant temperature of 400-550℃ for 30-90 min.

[0027] In steps S4 and S5, the comprehensive optimization parameters can be set as follows: the solid activator selected for the adsorbent material is a composite reagent of K2CO3 and FeCl3 mixed in a mass ratio of 1:1, with a particle size of 0.2-0.3 mm, a mass ratio of composite reagent to biochar of 1:3, a ball mill speed of 300 r / min, a grinding time of 25 min, and constant temperature activation at 550℃ for 60 min; the solid activator selected for the energy storage electrode is a composite reagent of urea and K2CO3 mixed in a mass ratio of 1:1, with a particle size of 0.08-0.15 mm, a mass ratio of composite reagent to biochar of 1:4, a ball mill speed of 250 r / min, a grinding time of 35 min, and constant temperature activation at 450℃ for 60 min.

[0028] The reason this invention selects different process parameters for different components of baijiu (Chinese white liquor) lees is primarily because the physicochemical properties of baijiu lees are closely related to the brewing raw materials, brewing process, and storage time. The main components of baijiu lees from different aroma types differ significantly, as shown in the table below:

[0029] The aforementioned differences in composition directly affect the selection of process parameters for each stage of drying, pyrolysis, and activation. Specifically: (1) Effect of moisture content on drying parameters The initial moisture content of distiller's grains is typically between 50% and 65%. When the moisture content is higher than 60% (such as for strong-aroma and light-aroma distiller's grains), the preheating temperature needs to be appropriately lowered (not exceeding 70℃) and the preheating time extended (25-30 minutes) to prevent excessively rapid evaporation of surface moisture, which would form a hard shell and hinder internal moisture migration. When the moisture content is lower than 55% (such as for sauce-aroma distiller's grains), the preheating temperature can be appropriately increased and the preheating time shortened. The temperature and time of the constant-rate drying section also need to be adjusted according to the moisture content: the higher the moisture content, the longer the constant-rate drying time, but the temperature should not exceed 120℃ to prevent the thermal decomposition of organic matter in the distiller's grains, which would produce off-flavor substances.

[0030] (2) Effect of starch content on drying and pyrolysis parameters The starch content of distiller's grains is typically between 8% and 12%. When the starch content exceeds 12%, gelatinization is more likely to occur during the drying process. Therefore, the temperature in the constant-rate drying stage should not exceed 110℃ to avoid localized overheating that could lead to starch gelatinization and clumping, affecting the uniformity of subsequent pyrolysis. During the pyrolysis stage, high-starch-content distiller's grains undergo pyrolysis at a low temperature of 300-400℃, producing a large amount of volatile substances. It is necessary to appropriately extend the holding time in the low-temperature stage to ensure the full release of volatiles and prevent concentrated release in the high-temperature stage, which could result in uneven product quality.

[0031] (3) Effect of crude fiber content on drying and pyrolysis parameters The crude fiber content varies significantly among different aroma types of distiller's grains (approximately 28% for strong aroma, approximately 17% for soy sauce aroma, and approximately 16% for light aroma). Crude fiber has poor thermal conductivity, resulting in slow internal heat transfer during drying of high-crude-fiber-content distiller's grains. Therefore, the constant-rate drying temperature should not be lower than 120℃ to ensure effective heat transfer to the grain particles. During the pyrolysis stage, high crude fiber content implies higher lignin and cellulose content. These substances decompose at 300-400℃ to produce hemicellulose and volatile cellulose products, and further undergo aromatization reactions at 500-700℃ to form a stable carbon skeleton. Therefore, the holding time for high-crude-fiber distiller's grains at high temperatures should be no less than 90 minutes to ensure sufficient carbon skeleton development.

[0032] (4) Effect of crude protein content on drying and activation parameters The crude protein content is approximately 14.52% in strong-aroma type distiller's grains, and as high as 24% or more in sauce-aroma and light-aroma type distiller's grains. Proteins begin to denature above 80℃. In the cooling and drying section, if the temperature is too high (>85℃) and the protein content is high, excessive denaturation and Maillard reactions will occur, leading to coking on the surface of the distiller's grain particles and affecting the uniformity of subsequent pyrolysis. Therefore, when the crude protein content is higher than 20%, the cooling temperature should not exceed 85℃. In the activation stage, a high protein content means that the distiller's grains themselves contain a relatively large amount of nitrogen. During pyrolysis, some of this nitrogen will remain in the carbon framework, forming self-doped nitrogen. Therefore, when preparing energy storage electrode materials, the proportion of added urea can be appropriately reduced (by 5%-15%), utilizing the distiller's grains' own protein as a supplementary nitrogen source, which saves costs and achieves efficient nitrogen utilization.

[0033] (5) Effect of pH value on activation parameters The pH value of distiller's grains is typically in the range of 3.6-4.0, indicating an acidic environment. When the pH value is below 3.8, the content of acidic substances (such as organic acids and lactic acid) in the distiller's grains is relatively high. These acidic substances will react with the alkaline activator during the activation process, consuming some of the activator. Therefore, when the pH value of the distiller's grains is below 3.8, the proportion of K2CO3 in the activating reagent of the adsorbent material should be increased by 10%-20% to neutralize the acidic substances and ensure the activation effect.

[0034] Current distillery waste treatment processes mostly involve simple pre-drying of the waste without precise control over moisture content, which negatively impacts subsequent pyrolysis and activation performance. To address this, this invention proposes a more precise three-stage gradient drying method. The preheating stage (60-80℃, 20-30 min) primarily aims to slowly evaporate surface moisture from the waste, preventing surface hardening caused by rapid evaporation. The constant-rate stage (100-120℃, 30-40 min) is the main drying stage, during which moisture inside the waste migrates to the surface and evaporates at a constant rate. The cooling stage (80-90℃, 10-15 min) aims to slowly lower the temperature of the waste, preventing particle breakage due to thermal stress caused by sudden temperature drops. Compared to traditional single-stage drying (which typically uses a single temperature of 100-180℃ for direct drying), three-stage gradient drying has the following technical advantages: First, it provides better drying uniformity, with a smaller fluctuation range in the moisture content of the distiller's grains (controllable within ±1%); second, it has lower energy consumption, as segmented temperature control avoids ineffective energy consumption at excessively high temperatures; and third, it produces better product quality, avoiding premature decomposition and coking of organic matter caused by localized overheating. The final moisture content is controlled at 8%-15%, preferably 10%. This moisture content range ensures the safety of subsequent pyrolysis (excessive moisture content leads to a sharp increase in pyrolysis energy consumption) while retaining an appropriate amount of moisture to participate in the water-gas reaction during pyrolysis, promoting pore formation.

[0035] The two-stage precise pyrolysis is one of the core technological innovations of this invention. The first stage of pyrolysis (300-400℃, holding time 20-30 min) primarily achieves the decomposition of hemicellulose and cellulose. Within this temperature range, hemicellulose begins to decompose at 220-315℃, and cellulose undergoes depolymerization at 300-400℃, generating intermediate products such as L-glucose, which further decomposes into volatile organic compounds and coke. The holding time in the low-temperature stage is no less than 20 min to ensure complete decomposition of hemicellulose and cellulose, preventing incompletely decomposed cellulose from rapidly decomposing in the high-temperature stage, generating a large amount of gas that could lead to carbon skeleton breakage. The second stage of pyrolysis (500-700℃, holding time 90-150 min) primarily achieves the aromatization of the carbon skeleton and pore development. Within this temperature range, the carbon material undergoes a significant graphitization transformation, with amorphous carbon transforming into an ordered carbon structure. Simultaneously, residual volatile substances are further released, promoting the development of the pore structure. The holding time in the high-temperature stage is no less than 90 min to ensure the full progress of the aromatization reaction and the stable formation of the carbon skeleton. The heating rate should be controlled between 5-15℃ / min, preferably 10℃ / min. Too fast a heating rate (>15℃ / min) will cause volatiles to be released in a concentrated manner, damaging the carbon skeleton structure; too slow a heating rate (<5℃ / min) will prolong the production cycle and reduce production efficiency.

[0036] This invention precisely combines different solid activating reagents according to the different uses of the target product, which is the key to realizing the high-value utilization of distiller's grains charcoal.

[0037] For adsorption materials, FeCl3, K2CO3, or a mixture of both are selected. K2CO3, as an alkaline activator, reacts with the carbon skeleton within a temperature range of 400-650℃. Through the decomposition reaction K2CO3→K2O+CO2 and the reduction reaction K2O+C→2K+CO, it etches micropores and mesopores in the carbon material, significantly increasing the specific surface area. FeCl3, as a metal salt activator, decomposes during pyrolysis to generate iron oxides such as Fe2O3 and Fe3O4. These iron oxides catalyze the formation of pores in the carbon material and, after acid washing, remove the iron oxides, forming additional mesopores. When FeCl3 and K2CO3 are mixed in a mass ratio of 1:1 to 2:1, they produce a synergistic effect: K2CO3 mainly contributes to the formation of micropores, while FeCl3 mainly contributes to the formation of mesopores. Their combined use can form a hierarchical porous structure with micropores, mesopores, and macropores coexisting. This hierarchical porous structure has a significant advantage in adsorbing pollutant molecules of different sizes. Meanwhile, the residual iron oxides have a strong specific adsorption capacity for anionic pollutants such as phosphates.

[0038] For the energy storage electrode, a mixture of urea and K₂CO₃ is selected. Urea decomposes at high temperatures to produce nitrogen-containing gases such as NH₃ and HNCO. These gases react with the carbon framework, introducing nitrogen atoms into the carbon material to form nitrogen-doped structures such as pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen. Nitrogen doping not only increases the pseudocapacitive contribution of the carbon material but also improves its conductivity and surface hydrophilicity. K₂CO₃ mainly plays a pore-forming role in this system, synergistically working with urea to form a nitrogen-doped hierarchical porous structure. Urea and K₂CO₃ are mixed at a mass ratio of 1:0.5–1:2, and the nitrogen doping amount can be controlled within the range of 2%–8%. Within this range, the nitrogen doping amount significantly enhances electrochemical performance without excessively consuming the carbon framework, thus preventing a decrease in specific surface area.

[0039] Furthermore, this invention employs a dry ball milling method to mix the solid activating reagent with pyrolytic biochar, unlike the traditional wet impregnation process. The technical advantages of dry ball milling are: firstly, it eliminates the need for solvents, avoiding solvent consumption and subsequent drying steps, thus simplifying the process; secondly, the mechanical force during ball milling allows the activating reagent particles to be evenly dispersed and partially embedded in the biochar surface, enhancing the contact between the two; and thirdly, ball milling can further reduce the biochar particle size and increase the specific surface area. The ball mill speed is controlled at 200-400 r / min, and the grinding time is 10-40 min. Too low a speed or too short a time will result in uneven mixing; too high a speed or too long a time will lead to over-pulverization of the biochar, affecting subsequent molding and processing.

[0040] In the activation stage, to combine with solid activation reagents and dry ball milling processes, this invention conducted a more precise study on the activation temperature. Specifically, for the composite reagent of FeCl3 and K2CO3 used in adsorption materials, the activation temperature was controlled at 400-650℃. Within the range of 400-550℃, K2CO3 slowly decomposes and reacts with the carbon framework, mainly forming microporous structures; within the range of 550-650℃, the reaction intensifies, and the micropores further widen to form mesopores. The activation time is 30-100 min; too short a time results in insufficient activation, while too long a time leads to excessive carbon ablation. For the composite reagent of urea and K2CO3 used in energy storage electrodes, the activation temperature was controlled at 400-550℃. Urea begins to decompose at 400-450℃, producing nitrogen-containing gas. 450-550℃ is the optimal temperature range for nitrogen doping and pore development; excessively high temperatures (>550℃) will lead to a large loss of nitrogen, reducing the nitrogen doping effect.

[0041] To adapt to the aforementioned drying-pyrolysis-activation synergistic modification method, this invention also provides corresponding compatibility equipment. Specifically, as follows... Figure 2 , Figure 3As shown, it mainly includes a pretreatment unit 1, a gradient drying unit 2, a precision pyrolysis unit 3, an activation adjustment unit 5, a constant temperature activation unit 7, and a product post-treatment unit 8 connected in sequence, as well as a control system and a heat circulation system 4. The control system adopts a PLC controller, which links the sensors and actuators of each unit, presets multiple sets of matching parameters, and controls the continuous operation of each equipment unit. The pretreatment unit 1 includes a component detection device for detecting the moisture content, pH value, starch content, crude fiber content, and crude protein content of the distiller's grains. The component detection device is electrically connected to the control system and is used to feed back the detection data to the control system to adjust the process parameters of each unit.

[0042] Preferably, the gradient drying unit 2 includes a three-section drying chamber, a conveyor belt, a gradient heating device, and a moisture content monitor; the precision pyrolysis unit 3 includes a pyrolysis furnace and an inert gas generator; the activation and conditioning unit 5 includes a weighing scale and a ball mill 6; the constant temperature activation unit 7 includes an activation furnace and shares the inert gas generator with the precision pyrolysis unit 3; the product post-processing unit 8 includes a washing tank, a centrifuge, and a dryer; the heat circulation system 4 is used to recover heat from the high-temperature gas generated by the precision pyrolysis unit 3 and uses the recovered heat for the gradient drying unit 2 and the product post-processing unit 8. The activation and conditioning unit 7 includes at least three solid reagent storage chambers 9 spaced apart along the running direction of the conveyor belt. Each solid reagent storage chamber 9 has a weighing scale 10 at its bottom outlet, with the outlet of the weighing scale 10 located above the conveyor belt. A mixing chamber 11 is located at the tail end of the conveyor belt, and the outlet of the mixing chamber 11 is connected to the ball mill 6.

[0043] While the aforementioned pretreatment unit 1, gradient drying unit 2, precision pyrolysis unit 3, activation regulation unit 5, isothermal activation unit 7, and product post-treatment unit 8 can each utilize existing mature equipment, this invention forms an integrated production line by sequentially sealing and connecting each unit according to the process flow. The pretreatment unit 1 is equipped with a five-component detection device for moisture content, pH value, starch content, crude fiber content, and crude protein content. This device is electrically connected to a PLC control system, enabling the control system to adjust the temperature and time parameters of each stage of the gradient drying unit 2, the type and ratio of solid activating reagents in the activation regulation unit 5, and the activation temperature and time parameters of the isothermal activation unit 7 based on the detected full-component data. The control system uses only a conventional PLC controller, without any modification to the software program algorithm or control model. This complete set of equipment can achieve automated parameter matching and continuous production based on the characteristics of the distiller's grains and the target product requirements, thereby significantly improving the utilization rate and production efficiency of the distiller's grains and realizing the high-value conversion of distiller's grains.

[0044] The present invention will be further described below with reference to embodiments.

[0045] Example 1: Adsorption-modified biochar.

[0046] Using strong-aroma baijiu lees (57.53% water content, pH 3.65, starch content 10.31%, crude fiber content 28.14%, crude protein content 14.52%) as raw material, the modification was carried out according to the method described in this invention: 1. Pretreatment: Use the impurity screening machine in the pretreatment unit to remove impurities (stones, bamboo pieces, metal, etc.), and test the full composition characteristics of the lees, such as moisture content, pH value, starch content, crude fiber content and crude protein content. 2. Gradient Drying: The pretreated lees were fed into the drying chamber of the gradient drying unit. Based on the characteristics of the lees, which had a high moisture content (57.53%), high crude fiber content (28.14%), and moderate crude protein content (14.52%), the drying parameters were set as follows: Preheating section 70℃ / 25min (high moisture content, using the middle temperature of the preheating section and appropriately extending the time), constant rate section 110℃ / 35min (high crude fiber content, using the upper-middle value of the constant rate section temperature to compensate for low thermal conductivity; starch content 10.31% < 12%, no need to lower the temperature), cooling section 85℃ / 12min (crude protein content 14.52% < 20%, using the middle value of the cooling section temperature). The moisture content was confirmed to be 10% using a moisture meter. 3. Precision Pyrolysis: The dried distiller's grains are fed into the pyrolysis furnace of the precision pyrolysis unit. Nitrogen gas is introduced through an inert gas generator (flow rate 300 mL / min), and the temperature is increased at a rate of 10 °C / min under the control of a programmed temperature controller. The temperature is held at 350 °C for 25 min (decomposing hemicellulose and cellulose) and at 600 °C for 120 min (promoting aromatization and porosity development) to obtain initial biochar. Simultaneously, the volatiles generated during pyrolysis are recovered by a volatiles recovery device for heat recycling. The specific surface area of ​​the initial biochar is 0.92-1.0 m². 2 / g, pore volume is 1.9×10^ -3 -2.2×10^ -3 cm 3 / g, with an average pore size of 10-12nm; 4. Activation and Adjustment: The pyrolytic biochar was fed into a horizontal ball mill in the activation and adjustment unit. Based on the target product being an adsorbent, a composite activating agent consisting of a 1:1 mass ratio of K₂CO₃ and FeCl₃ was selected. Since the pH of the distiller's grains was low (3.65 < 3.8), the proportion of K₂CO₃ was increased by 15% (the adjusted K₂CO₃:FeCl₃ mass ratio was approximately 1.15:1). The solid reagent was pulverized to 0.2-0.3 mm using a solid reagent pulverizer to prepare the composite reagent. The composite reagent was mixed with the initial biochar at a mass ratio of 1:3 and then fed into the ball mill. The ball mill speed was set to 300 r / min, and the mixture was ground and mixed for 25 min. 5. Constant temperature activation: The uniformly mixed material is fed into the activation furnace of the constant temperature activation unit. Nitrogen gas is continuously introduced for protection through an inert gas generator. The temperature is controlled by a temperature controller to maintain a constant temperature of 550℃ for 60 minutes. The activation exhaust gas is treated by an exhaust gas treatment device before being discharged. 6. Post-processing: After cooling, the activated product is sent to the washing tank of the product post-processing unit, washed with deionized water until neutral, separated by a centrifuge, and then sent to a dryer to dry at 90°C for 2 hours to obtain adsorption-type modified biochar.

[0047] The pore structure characteristics of biochar were analyzed using the nitrogen adsorption method (BET method), and the adsorption capacity of the char was detected using the methylene blue adsorption method. The results showed that the specific surface area of ​​the char was 800-820 m². 2 / g, pore volume is 0.37×10 -3 -0.41×10 -3 cm 3 / g, with an average pore size of 2.07-2.41nm, the modified carbon product has a large specific surface area, a rich microporous structure and a strong adsorption capacity, with a methylene blue adsorption capacity of 400-420mg / g and a phosphorus adsorption capacity of 20-23mg / g.

[0048] Example 2: Energy Storage Electrode Type Modified Biochar Using the lees of Maotai-flavor liquor (51.47% water content, pH 3.94, starch content 10.20%, crude fiber content 17.12%, crude protein content 24.58%) as raw material, the patent implementation is carried out according to the method described in this invention: 1. Pretreatment: Impurities are removed using the impurity screening machine in the pretreatment unit, and the full component characteristics of the distiller's grains are detected; 2. Gradient Drying: The pretreated lees were fed into the drying chamber of the gradient drying unit. Based on the lees' composition characteristics, the lees had a low moisture content (51.47% < 55%) and a high crude protein content (24.58% > 20%). Therefore, the drying parameters were set as follows: preheating section 70℃ / 25min (relatively low moisture content, using the middle temperature of the preheating section), constant rate section 110℃ / 35min (crude fiber content 17.12% < 25%, starch content 10.20% < 12%, using the middle temperature of the constant rate section), cooling section 82℃ / 12min (high crude protein content, using the lower limit of the cooling section to prevent excessive protein denaturation). The moisture content was confirmed to be 10% using a moisture meter. 3. Precision pyrolysis: The dried lees are fed into the pyrolysis furnace of the precision pyrolysis unit. Nitrogen gas is introduced through an inert gas generator (flow rate 300 mL / min). The temperature is increased at 10℃ / min by a programmable temperature controller. The temperature is held at 350℃ for 25 min and 600℃ for 120 min to obtain initial biochar. At the same time, non-condensable gases (residual heat) are recovered for heat recycling. 4. Activation and Adjustment: The pyrolytic biochar was fed into a horizontal ball mill in the activation and adjustment unit. Based on the target product being an energy storage electrode, a composite activating agent of urea and K₂CO₃ was selected. The crude protein content of this distiller's grains was high (24.58% > 20%), therefore the proportion of urea was reduced by 10% (the adjusted urea:K₂CO₃ mass ratio was approximately 0.9:1). Solid urea and solid K₂CO₃ were pulverized to 0.08-0.15 mm using a solid reagent pulverizer to prepare the composite reagent. The composite reagent was mixed with the initial biochar at a mass ratio of 1:4 and fed into the ball mill. The ball mill speed was set to 250 r / min, and the mixture was ground and mixed for 35 min. 5. Constant temperature activation: The uniformly mixed material is fed into the activation furnace of the constant temperature activation unit, nitrogen gas is introduced for protection, and the temperature is controlled by the temperature controller to maintain a constant temperature of 450℃ for 60 minutes. 6. Post-processing: After cooling, the activated product is sent to the washing tank of the product post-processing unit and washed until neutral. After separation by centrifuge, it is sent to the post-dryer and dried at 90°C for 2 hours to obtain energy storage electrode type modified biochar.

[0049] The material structure and electrochemical properties were tested on an electrochemical workstation using the BET method and a three-electrode system. The results showed that the specific surface area of ​​the biochar was 1050-1200 m². 2 / g, specific capacitance 420-550F / g (1A / g), capacity retention >92% after 10,000 cycles, biochar can be used as battery electrode, battery peak power density 130-160mW / cm³ 2 .

[0050] Example 3: Compatible Equipment Operation Test Using the lees drying-pyrolysis-activation equipment described in this invention, 100 kg of lees was continuously processed according to the parameters of Example 1. Test results: 1. Stable operation: The high-precision weighing scale of the activation and adjustment unit has a weighing accuracy of ±2%, the particle size error of the solid reagent pulverizer is ≤0.05mm, the grinding uniformity of the horizontal ball mill is ≥98%, and the control system links all units and controls all parameters precisely. 2. Energy consumption is 82kWh; the waste heat recovery device of the heat circulation system has a recovery efficiency of 80-86%, and energy consumption is reduced by 32-35% compared with traditional equipment. 3. Product yield: 35-40% of biochar is recovered through the product post-processing unit, the recovery rate of unreacted reagents is >85%, the resource utilization rate is >85%, the harmful gas removal rate of the tail gas treatment device is ≥95%, and there is no secondary pollution; 4. Operation of the Programmable Logic Controller in the Equipment Control System: Based on the detection results of the components of the distiller's grains (light aroma, soy sauce aroma, and strong aroma types), the equipment can directly adjust the drying temperature. It determines whether to perform pyrolysis based on the moisture content of the dried distiller's grains, then selects a preset pyrolysis program (temperature, time), and determines the subsequent operating process based on the initial pyrolysis char component detection data, including the ratio of composite reagents and the mixing ratio of char and reagents at each activation stage. This demonstrates that the equipment control system designed in this invention can not only adjust the equipment operating parameters in real time according to the components of the distiller's grains, but also make targeted adjustments based on different types of distiller's grains and the preparation purpose.

Claims

1. A method for synergistic modification of distiller's grains through drying, pyrolysis, and activation, characterized in that, Includes the following steps: S1. Distillers' grains pretreatment: Remove impurities from the distillers' grains and detect the characteristics of the components of the distillers' grains, including water content, pH value, starch content, crude fiber content and crude protein content; S2. Gradient Drying: Based on the detected characteristics of the lees composition, the drying parameters are adjusted, and the lees are subjected to a three-stage drying process: preheating, constant-rate drying, and cooling. The preheating stage is conducted at a temperature of 60-80℃ for 20-30 minutes; the constant-rate stage is conducted at a temperature of 100-120℃ for 30-40 minutes; and the cooling stage is conducted at a temperature of 80-90℃ for 10-15 minutes. The final moisture content of the lees is controlled at 8%-15%. S3. Precise pyrolysis: Under inert gas protection, the temperature is increased at a rate of 5-15℃ / min to carry out two-stage pyrolysis of the lees. The first stage of pyrolysis is at a temperature of 300-400℃ and a holding time of 20-30 min. The second stage of pyrolysis is at a temperature of 500-700℃ and a holding time of 90-150 min. S4. Adjustment of Activation Modifier: Select different solid activation reagents according to the intended use of the target product. Feed the pyrolytic biochar obtained in S3 into a ball mill, add the solid activation reagent, and grind and mix for 10-40 min. When the target product is an adsorbent material, the solid activation reagent is one or a mixture of FeCl3 and K2CO3. When the target product is an energy storage electrode, the solid activation reagent is a mixture of urea and K2CO3. S5. Isothermal activation: The mixture obtained in S4 is activated under inert gas protection at an isothermal rate of 5℃ / min, with an activation temperature of 400-650℃ and an activation time of 30-100 min. S6. Product post-processing: Cool, wash until neutral and dry the product obtained in S5.

2. The method for synergistic modification of distiller's grains through drying, pyrolysis, and activation as described in claim 1, characterized in that, In step S2, adjusting the drying parameters according to the characteristics of the distillers' grains includes: when the moisture content of the distillers' grains is higher than 60%, the temperature of the preheating section should not exceed 70°C, and the drying time should be 25-30 minutes; when the starch content of the distillers' grains is higher than 12%, the temperature of the constant-speed section should not exceed 110°C to avoid starch gelatinization; when the crude fiber content of the distillers' grains is higher than 25%, the temperature of the constant-speed section should not be lower than 110°C to compensate for the low thermal conductivity of the crude fiber; when the crude protein content of the distillers' grains is higher than 20%, the temperature of the cooling section should not exceed 85°C to prevent excessive denaturation and coking of the protein.

3. The method for synergistic modification of distiller's grains through drying, pyrolysis, and activation as described in claim 1 or 2, characterized in that... In step S2, the temperature of the preheating section is 70℃ and the drying time is 25min; the temperature of the constant rate section is 110℃ and the drying time is 35min; the temperature of the cooling section is 85℃ and the drying time is 12min, ultimately controlling the moisture content of the lees at 10%.

4. The method for synergistic modification of distiller's grains through drying, pyrolysis, and activation as described in claim 1, characterized in that... In step S3, the pyrolysis heating rate is 10 ℃ / min, the pyrolysis temperature in the low-temperature section is 350℃ and the holding time is 25 min, the pyrolysis temperature in the high-temperature section is 600℃ and the holding time is 120 min; the inert gas flow rate is controlled at 100-500 mL / min.

5. The method for synergistic modification of distiller's grains through drying, pyrolysis, and activation as described in claim 1, characterized in that... In step S4, selecting different solid activating reagents according to the intended use of the target product includes: When the target product is an adsorbent material, one of FeCl3 and K2CO3 or a composite reagent mixed in a mass ratio of 1:1-2:1 is selected, with a particle size of 0.1-0.5 mm, a mass ratio of solid activating reagent to biochar of 1:1-1:5, and a ball mill speed of 200-400 r / min. When the target product is an energy storage electrode, a composite reagent of urea and K2CO3 mixed at a mass ratio of 1:0.5-1:2 is selected, with a particle size of 0.05-0.15 mm. The mass ratio of solid activating reagent to biochar is 1:3-1:6, and the ball mill speed is 200-300 r / min.

6. The method for synergistic modification of distiller's grains through drying, pyrolysis, and activation as described in claim 5, characterized in that... In step S5, different activation temperatures and activation times are used according to the intended use of the target product. The adsorbent material is activated at a constant temperature of 400-650℃ for 30-100 min; the energy storage electrode is activated at a constant temperature of 400-550℃ for 30-90 min.

7. The method for synergistic modification of distiller's grains through drying, pyrolysis, and activation as described in claim 6, characterized in that... In steps S4 and S5, the solid activator selected for the adsorbent material is a composite reagent of K2CO3 and FeCl3 mixed in a mass ratio of 1:1, with a particle size of 0.2-0.3 mm. The mass ratio of the composite reagent to biochar is 1:

3. The ball mill speed is 300 r / min, the grinding time is 25 min, and the activation is carried out at a constant temperature of 550℃ for 60 min. The solid activator selected for the energy storage electrode is a composite reagent of urea and K2CO3 mixed in a mass ratio of 1:1, with a particle size of 0.08-0.15 mm. The mass ratio of the composite reagent to biochar is 1:

4. The ball mill speed is 250 r / min, the grinding time is 35 min, and the activation is carried out at a constant temperature of 450℃ for 60 min.

8. A compatibility device for the synergistic modification of distiller's grains through drying, pyrolysis, activation, and modification, characterized in that... The system includes a pretreatment unit, a gradient drying unit, a precision pyrolysis unit, an activation and adjustment unit, a constant temperature activation unit, and a product post-treatment unit connected in sequence, as well as a control system and a heat circulation system. The control system uses a PLC controller to link the sensors and actuators of each unit, preset multiple sets of matching parameters, and control the continuous operation of each equipment unit. The pretreatment unit includes component detection equipment for detecting the moisture content, pH value, starch content, crude fiber content, and crude protein content of the distiller's grains. The component detection equipment is electrically connected to the control system and is used to feed back the detection data to the control system to automatically adjust the process parameters of each unit.

9. The compatibility equipment for synergistic modification of distiller's grains through drying, pyrolysis, activation, and modification as described in claim 8, characterized in that, The gradient drying unit includes a three-section drying chamber, a conveyor belt, a gradient heating device, and a moisture content monitor; the precision pyrolysis unit includes a pyrolysis furnace and an inert gas generator; the activation and adjustment unit includes a weighing scale and a ball mill; the constant temperature activation unit includes an activation furnace and shares an inert gas generator with the precision pyrolysis unit; the product post-processing unit includes a washing tank, a centrifuge, and a dryer; the heat circulation system is used to recover heat from the high-temperature gas generated by the precision pyrolysis unit and to use the recovered heat in the gradient drying unit and the product post-processing unit.

10. The compatibility equipment for synergistic modification of distiller's grains through drying, pyrolysis, activation, and modification as described in claim 9, characterized in that, The activation adjustment unit includes at least three solid reagent storage chambers spaced apart along the running direction of the conveyor belt. Each solid reagent storage chamber has a weighing scale at its bottom outlet, with the outlet of the weighing scale located above the conveyor belt. A mixing chamber is located at the tail end of the conveyor belt, and the outlet of the mixing chamber is connected to the ball mill.

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