Method and system for cascade pyrolysis of tobacco field waste to co-produce high-value products

Abstract

The application discloses a method and system for cascade pyrolysis of tobacco field waste for co-production of high-value products, and belongs to the technical field of agricultural solid waste resource utilization and thermochemical conversion. The three types of tobacco field waste, i.e. tobacco stems, tobacco flowers and waste mulching films, are pretreated, and then a part of the tobacco flowers is extracted to recover high-value active ingredients. The extraction residues and the remaining tobacco flowers are mixed with the tobacco stems and the waste mulching films to perform catalytic co-pyrolysis, and high-value products such as functionalized tobacco field biochar, bio-oil and combustible gas are obtained. The three-phase products are directedly used for tobacco field fertilization, baking heat supply and system self-heating, forming a green closed loop of 'from the tobacco field to the tobacco field'. In addition, the method realizes full consumption and cascade high-value utilization of the three types of tobacco field waste, and has good economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of agricultural solid waste resource utilization and thermochemical conversion technology, specifically relating to a method and system for the co-production of high-value products from the cascade pyrolysis of tobacco field waste. Background Technology

[0002] Tobacco is an important economic crop in my country, with an annual planting area of ​​approximately 11.5 million mu (667,000 hectares). The tobacco production process generates a large amount of waste, mainly including tobacco stalks, charcoal, and waste plastic film. For tobacco stalks, approximately 1,100 stalks are produced per mu (667,000 hectares) of tobacco field, with a fresh weight of about 1 ton. Currently, the main method of disposal is on-site crushing and returning the stalks to the field. However, tobacco stalks carry soil-borne pathogens such as bacterial wilt, and direct return increases the risk of disease in the next flue-cured tobacco crop. Burning, on the other hand, produces harmful gases and pollutes the environment. Preliminary practices have been implemented in preparing biochar from tobacco stalks for soil improvement in tobacco fields, but the cost remains high, and a complete industrial closed loop has not yet been formed. As for charcoal, a large amount of charcoal (inflorescences and axillary buds) is generated during the topping process of flue-cured tobacco, which is currently mostly discarded or burned indiscriminately. Furthermore, charcoal is rich in high-value active ingredients such as alkaloids (nicotine, etc.), polyphenols, and cephalothrix trienol, but these are not effectively utilized. Regarding waste plastic film, the polyethylene (PE) plastic film used to cover tobacco fields remains in the soil after the use season, causing "white pollution" and damaging the soil structure. The current recycling method mainly relies on manual cleaning and delivery to recycling companies, but the recycling rate is low due to problems such as high transportation costs and high soil and impurity content.

[0003] Pyrolysis, as a thermochemical conversion method, can convert organic matter into three-phase products—biochar, bio-oil, and combustible gas—under anaerobic or hypoxic conditions. Extensive research has been conducted on the thermochemical conversion of tobacco waste to produce biochar and bio-oil. However, existing thermochemical conversion processes for tobacco waste suffer from problems such as incomplete pyrolysis and low yields and utilization rates of high-value products.

[0004] In view of this, it is necessary to provide a method and system for the co-production of high-value products from the cascade pyrolysis of tobacco field waste, in order to overcome the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for the cascade pyrolysis of tobacco waste to co-produce high-value products. This addresses problems such as insufficient pyrolysis and low yields and utilization rates of high-value products in existing thermochemical conversion processes for tobacco waste.

[0006] In a first aspect, the present invention provides a method for the co-production of high-value products from the cascade pyrolysis of tobacco field waste, comprising the following steps: providing pretreated tobacco stalks, pretreated fireworks, and pretreated waste plastic film; taking a portion of the pretreated fireworks and sequentially performing a first extraction and a second extraction to obtain a first extract, a second extract, and fireworks residue; subjecting a mixture of the pretreated tobacco stalks, the remaining pretreated fireworks and fireworks residue, and the pretreated waste plastic film to a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment to obtain products; separating the products to obtain functionalized tobacco field biochar, bio-oil, and combustible gas; wherein the temperature of the first pyrolysis treatment is lower than the temperature of the second pyrolysis treatment.

[0007] In this invention, the inventors discovered that by pre-treating three types of tobacco field waste—tobacco stalks, fireworks, and waste plastic film—a portion of the fireworks is first extracted to recover high-value active ingredients. The extracted residue and the remaining fireworks are then mixed with tobacco stalks and waste plastic film and subjected to catalytic co-pyrolysis to obtain high-value products such as functionalized tobacco field biochar, bio-oil, and combustible gas. These three-phase products are then directionally recycled for tobacco field fertilization, baking heating, and system self-heating, forming a green closed loop of "from the tobacco field, back to the tobacco field." Furthermore, this method achieves full utilization and tiered high-value utilization of the three types of tobacco field waste, resulting in significant economic benefits.

[0008] In some implementations, in the steps of providing pretreated smoke rods, pretreated fireworks, and pretreated waste plastic film, the pretreated smoke rods have a moisture content of ≤15% and a particle size of 5-20mm; the pretreated fireworks have a moisture content of ≤15%; and the pretreated waste plastic film has a particle size of 5-15mm.

[0009] In this invention, by pre-treating the tobacco rods, fireworks, and waste plastic film, the particle size is controlled within a specific range to ensure uniform mixing of the raw materials, which facilitates efficient subsequent pyrolysis and thus yields high-quality products.

[0010] In some implementation schemes, in the step of taking a portion of pretreated fireworks and sequentially performing a first extraction and a second extraction to obtain a first extract, a second extract, and fireworks residue, the portion of pretreated fireworks accounts for 60-80% of the total mass of the pretreated fireworks; the first extraction includes supercritical CO2 extraction, which specifically includes: using supercritical CO2 as a solvent, extracting for 2-3 hours under the conditions of an extraction pressure of 25-35 MPa, an extraction temperature of 40-50℃, and a CO2 flow rate of 15-25 L / h; the first extract includes at least one of cepertrienyl glycol and volatile oil; wherein, the volatile oil includes linalool and β-damascone.

[0011] In this invention, by controlling the parameters of supercritical CO2 extraction within a specific range, high-value components such as cephalotrindiol and volatile oils from fireworks can be efficiently extracted; and the extracted cephalotrindiol and volatile oils can be used as natural flavorings from tobacco for adding flavor to cigarettes.

[0012] In some implementation schemes, after taking a portion of pretreated fireworks and sequentially performing a first extraction and a second extraction to obtain a first extract, a second extract, and fireworks residue, the second extraction includes ethanol-water extraction. Specifically, the ethanol-water extraction includes: using a 60-80% ethanol-water solution as a solvent, controlling the material-to-liquid ratio at 1g:(8-12mL), refluxing and extracting 2-3 times at a temperature of 50-60℃ for 1-2 hours each time, combining the extracts, and concentrating under reduced pressure. The second extract includes at least one of polyphenolic compounds and alkaloids; wherein the polyphenolic compounds include at least one of chlorogenic acid and rutin, and the alkaloids include nicotine.

[0013] In this invention, by controlling the parameters of ethanol-water extraction within a specific range, high-value components such as polyphenols and alkaloids in fireworks can be efficiently extracted; and the extracted polyphenols and alkaloids can be used to prepare plant-derived pesticides or pharmaceutical intermediates.

[0014] In some embodiments, in the steps of sequentially subjecting the mixture of pretreated smoke rods, the remaining pretreated fireworks and fireworks residue, and pretreated waste mulch film to a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment, the particle size of the remaining pretreated fireworks and fireworks residue is 2-10 mm; the mass ratio of the pretreated smoke rods, the remaining pretreated fireworks and fireworks residue, and the pretreated waste mulch film is (50-70):(10-25):(15-30), preferably 60:15:25; and the effective hydrogen-to-carbon ratio of the mixture is 0.8-1.4.

[0015] In this invention, by controlling the mass ratio of each raw material within a specific range, the performance of the obtained high-value product can be significantly improved, facilitating better subsequent applications.

[0016] In some embodiments, in the steps of sequentially subjecting the mixture of pretreated smoke rods, the remaining pretreated fireworks and fireworks residue, and pretreated waste mulch film to a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment, the first pyrolysis treatment specifically includes: pyrolysis at a temperature of 300-400℃ (preferably 350℃) for 10-20 minutes; the second pyrolysis treatment specifically includes: pyrolysis at a temperature of 480-560℃ (preferably 520℃) for 20-40 minutes; the post-catalytic treatment... The product of the second pyrolysis treatment is simultaneously subjected to a catalytic reaction, and the catalyst in the catalytic reaction includes a composite catalyst, which includes HZSM-5 molecular sieve, CaO and Fe2O3. The amount of composite catalyst added is 10-20% of the mass of the mixed material; wherein, the mass ratio of HZSM-5 molecular sieve, CaO and Fe2O3 is (60-80):(10-30):(5-15), preferably 70:20:10; the silicon-aluminum ratio in HZSM-5 molecular sieve is (25-50):1.

[0017] In this invention, the mixture is first subjected to a first pyrolysis at a low temperature, which preferentially decomposes low-thermal-stability components such as volatile oils and hemicellulose remaining in fireworks and fireworks residues, releasing volatile components rich in oxygen-containing compounds and terpenes. The waste plastic film (PE) has not yet completely melted and decomposed, but begins to soften, forming initial contact with the biomass surface. Then, a second pyrolysis is carried out at a high temperature, in which the cellulose and lignin in the tobacco stalks are deeply pyrolyzed, and the waste plastic film is fully decomposed to produce long-chain hydrocarbons and hydrogen free radicals. The hydrogen free radicals generated by the pyrolysis of waste plastic film have a synergistic effect with the oxygen-containing compounds generated by the pyrolysis of biomass, promoting deoxygenation and aromatization reactions, and significantly increasing the hydrocarbon content and calorific value of bio-oil. The secondary free radicals generated by co-pyrolysis can catalyze intermolecular hydrogen transfer and aromatization reactions, further improving the performance of high-value products.

[0018] Furthermore, the CaO in the composite catalyst can neutralize acidic substances (such as acetic acid) produced by pyrolysis, reducing the acidity of bio-oil; promote decarboxylation reactions, reducing oxygen-containing compounds; and adsorb CO2, increasing the calorific value of combustible gas. The Fe2O3 in the composite catalyst can lower the initial decomposition temperature of cellulose and waste plastic film, promote C / C bond breaking and hydrogen transfer reactions, and improve the selectivity of light aromatics. The HZSM-5 molecular sieve in the composite catalyst... It provides acidic sites to promote Diels-Alder reactions and aromatization reactions, converting furans and alkenes into monocyclic aromatic hydrocarbons (BTX).

[0019] In some implementation schemes, in the step of separating the products to obtain functionalized tobacco biochar, bio-oil, and combustible gas, the specific surface area of ​​the functionalized tobacco biochar is 50-200 m². 2 / g, carbon content ≥65%.

[0020] In this invention, functionalized tobacco field biochar has good performance. It is mixed with tobacco field special fertilizer at a mass ratio of (1-3):(7-9) to prepare carbon-based fertilizer. The carbon-based fertilizer is then applied to the tobacco field. The porous structure of biochar retains water and fertilizer, which can reduce the amount of chemical fertilizer used by 20-30%, resulting in good economic benefits.

[0021] In some implementation schemes, in the step of separating the products to obtain functionalized tobacco biochar, bio-oil and combustible gas, the bio-oil has an oxygen content of ≤15% and a calorific value of 28-35 MJ / kg; the bio-oil contains 40-45% monocyclic aromatic hydrocarbons; wherein the monocyclic aromatic hydrocarbons include at least one of benzene, toluene and xylene.

[0022] In this invention, the bio-oil has good performance and can be further hydrogenated and refined to be used as fuel oil for tobacco curing, replacing traditional coal and reducing curing costs and pollutant emissions; or it can be used as a chemical raw material to separate and extract BTX (benzene-toluene-xylene) and phenolic compounds.

[0023] In some implementation schemes, in the step of separating the products to obtain functionalized tobacco biochar, bio-oil, and combustible gas, the calorific value of the combustible gas is 12-18 MJ / m³. 3 Furthermore, the combustible gas includes at least one of H2, CO, CH4, and C2-C3 hydrocarbons.

[0024] In this invention, the combustible gas has good performance. After purification, it can be directly reused in the heating system of pyrolysis treatment to achieve the system's self-heating balance; or it can be used for heating tobacco curing rooms to form a closed loop of "waste pyrolysis - energy recovery - tobacco curing".

[0025] In a second aspect, the present invention provides a system for the co-production of high-value products from the cascade pyrolysis of tobacco field waste, comprising: a pretreatment unit for providing pretreated tobacco stalks, pretreated fireworks, and pretreated waste mulch film; an extraction unit for sequentially performing a first extraction and a second extraction on a portion of the pretreated fireworks to obtain a first extract, a second extract, and fireworks residue; a cascade pyrolysis reaction unit for sequentially performing a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment on a mixture of the pretreated tobacco stalks, the remaining pretreated fireworks and fireworks residue, and the pretreated waste mulch film to obtain products; and a product separation and collection unit for separating the products to obtain functionalized tobacco field biochar, bio-oil, and combustible gas.

[0026] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention pre-treats three types of tobacco field waste—tobacco stalks, fireworks, and waste plastic film—by first extracting a portion of the fireworks to recover high-value active ingredients. Then, the extracted residue and the remaining fireworks are mixed with tobacco stalks and waste plastic film and subjected to catalytic co-pyrolysis to obtain high-value products such as functionalized tobacco field biochar, bio-oil, and combustible gas. These three-phase products are then directionally recycled for tobacco field fertilization, baking heating, and system self-heating, forming a green closed loop of "from the tobacco field, back to the tobacco field." Furthermore, this method achieves full utilization and tiered high-value utilization of the three types of tobacco field waste—tobacco stalks, fireworks, and waste plastic film—resulting in significant economic benefits. Attached Figure Description

[0027] Figure 1 This is a flowchart of the method for co-producing high-value products from the cascade pyrolysis of tobacco field waste in this invention; Figure 2 This is a schematic diagram of the system structure for the co-production of high-value products from the cascade pyrolysis of tobacco field waste in this invention; The meanings of the reference numerals in the attached figures are as follows: 1: Pretreatment unit; 2: Extraction unit; 3: Cascade pyrolysis reaction unit; 4: Product separation and collection unit. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Experimental methods not specified in the examples are generally performed under conventional conditions and as described in the manual, or as recommended by the manufacturer. Unless otherwise specified, the general equipment, materials, reagents, etc. used are commercially available.

[0030] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] Please see Figure 1This is a flowchart of the method for co-producing high-value products from the cascade pyrolysis of tobacco field waste in this invention. Specifically, the method includes the following steps: providing pretreated tobacco stalks, pretreated fireworks, and pretreated waste mulch film; taking a portion of the pretreated fireworks and performing a first extraction and a second extraction sequentially to obtain a first extract, a second extract, and fireworks residue; subjecting the mixture of the pretreated tobacco stalks, the remaining pretreated fireworks and fireworks residue, and the pretreated waste mulch film to a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment sequentially to obtain products; and separating the products to obtain functionalized tobacco field biochar, bio-oil, and combustible gas.

[0032] Please continue reading. Figure 2 This is a schematic diagram of the system structure for the co-production of high-value products from the cascade pyrolysis of tobacco field waste in this invention. The system includes a pretreatment unit 1, which provides pretreated tobacco stalks, pretreated fireworks, and pretreated waste mulch film; an extraction unit 2, which sequentially performs a first extraction and a second extraction on a portion of the pretreated fireworks to obtain a first extract, a second extract, and fireworks residue; a cascade pyrolysis reaction unit 3, which sequentially performs a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment on a mixture of pretreated tobacco stalks, the remaining pretreated fireworks and fireworks residue, and pretreated waste mulch film to obtain products; and a product separation and collection unit 4, which separates the products to obtain functionalized tobacco field biochar, bio-oil, and combustible gas.

[0033] Specifically, the pretreatment unit 1 includes a cigarette stalk crusher, a fireworks drying crusher, and a plastic film washing crusher. The cigarette stalk crusher is used to pretreat cigarette stalks to obtain pretreated cigarette stalks; the fireworks drying crusher is used to pretreat fireworks to obtain pretreated fireworks; and the plastic film washing crusher is used to pretreat waste plastic film to obtain pretreated waste plastic film.

[0034] Extraction unit 2 includes a supercritical CO2 extraction device and an ethanol reflux extraction device connected in sequence, used to receive a portion of the pretreated fireworks and then perform extraction processing.

[0035] The cascade pyrolysis reaction unit 3 is a horizontal rotary kiln structure, with a low-temperature pyrolysis zone (first section) and a high-temperature pyrolysis zone (second section) arranged sequentially along the axial direction, and a temperature transition section between the two sections. The low-temperature pyrolysis zone is equipped with an independent temperature control system and a first feed inlet (used to receive pre-treated smoke rods, the remaining pre-treated fireworks and fireworks residue, and the mixture of pre-treated waste mulch film). The outlet of the high-temperature pyrolysis zone is equipped with a catalyst bed, which is filled with a composite catalyst. The inner wall of the rotary kiln is equipped with a spiral guide plate to promote the forward movement and mixing of materials. The rotary kiln speed is adjustable (1-10 rpm) to control the material residence time.

[0036] The product separation and collection unit 4 includes a cyclone separator, a condenser, and a gas purification device. The cyclone separator is used to collect functionalized tobacco biochar; the condenser is used to collect bio-oil; and the gas purification device is used to collect combustible gas.

[0037] Optionally, the gas purification device is connected to the cascade pyrolysis reaction unit 3 for supplying heat to the cascade pyrolysis reaction unit 3.

[0038] Example 1 A method for co-producing high-value products through cascade pyrolysis of tobacco field waste includes the following steps: S1. Pre-treatment of tobacco stalks: After harvesting, the tobacco stalks are air-dried naturally until the moisture content is 14%, then crushed into particles with a diameter of 10mm for later use; Pre-treatment of fireworks: Fresh fireworks collected from the top are hot-air dried at 55℃ until the moisture content is 12%, divided into two portions, one portion for active ingredient extraction (accounting for 70% of the total mass of fireworks), and the other portion is crushed into particles with a diameter of 5mm for later use as pyrolysis raw material; Pre-treatment of waste mulch film: Waste PE mulch film recovered from tobacco fields is washed with water to remove soil impurities, dried, and then crushed into fragments with a diameter of 10mm for later use; S2. The fireworks used for active ingredient extraction in step S1 are first subjected to supercritical CO2 extraction. Using supercritical CO2 as the solvent, the extraction is carried out for 2.5 hours at an extraction pressure of 30 MPa, an extraction temperature of 45℃, and a CO2 flow rate of 20 L / h, yielding 12.3 g / (kg dry fireworks) of crude cephalotrimethylenediol and 8.7 g / (kg dry fireworks) of volatile oil. Then, ethanol-water extraction is performed using 70% (volume fraction) ethanol-water solution as the solvent. The material-to-liquid ratio is controlled at 1 g:(10 mL), and the extraction is carried out three times under reflux at 55℃ for 1.5 hours each time. The extracts are combined and concentrated under reduced pressure to obtain 5.8 g / (kg dry fireworks) of chlorogenic acid and 3.2 g / (kg dry fireworks). The fireworks residue is dried and pulverized to 5 mm for later use. S3. Mix the tobacco granules obtained in step S1, the other portion of fireworks granules from step S1, the combined fireworks residue granules from step S2, and the waste PE mulch film fragments obtained in step S1 at a mass ratio of 60:15:25, and control the effective hydrogen-to-carbon ratio (H / C)eff of the mixture to be 1.12; then add the mixture to a horizontal rotary kiln (which has a low-temperature pyrolysis zone and a high-temperature pyrolysis zone along the axial direction, with a temperature transition section between the two zones; the low-temperature pyrolysis zone has an independent temperature control system and a first feed inlet (for receiving the mixture); the high-temperature pyrolysis zone has an outlet... A catalytic bed is filled with a composite catalyst (HZSM-5 molecular sieve, CaO, and Fe2O3 in a mass ratio of 70:20:10, with a silicon-to-aluminum ratio of 30:1 in the HZSM-5 molecular sieve, and the addition amount is 15% of the mass of the mixture); a spiral guide plate is provided on the inner wall of the rotary kiln to promote the forward movement and mixing of the material; the rotary kiln speed is adjustable (1-10 rpm) to control the material residence time; the temperature of the low-temperature pyrolysis zone is controlled at 350℃ with a residence time of 15 min; the temperature of the high-temperature pyrolysis zone is controlled at 520℃ with a residence time of 30 min; the product is obtained. S4. After separating the products obtained in step S3, functionalized tobacco biochar, bio-oil and combustible gas are obtained respectively.

[0039] Testing showed that the yield of functionalized tobacco biochar was 28.5% (by mass of the mixed materials), and the specific surface area was 168 m². 2 / g, with a carbon content of 72.3%. The yield of bio-oil was 36.2% (by mass of the mixture), with an oxygen content of 12.8% and a calorific value of 32.1 MJ / kg, of which monocyclic aromatic hydrocarbons accounted for 41.6% of the oil phase. The yield of combustible gas was 35.3% (by mass of the mixture), with a calorific value of 15.3 MJ / m³. 3 .

[0040] Comparative Example 1 In this comparative example, the method for co-producing high-value products by cascade pyrolysis of tobacco field waste is basically the same as in Example 1. The difference is that in step S1, all the fireworks are used for active ingredient extraction, and in step S3, the pyrolysis raw materials are only tobacco stalk particles and waste PE mulch film fragments, with a mass ratio of 75:25.

[0041] Testing showed that the yield of functionalized tobacco biochar was 31.2%, and the specific surface area was 243 m². 2 / g, with a carbon content of 74.1%. The yield of bio-oil is 32.8%, the oxygen content is 14.5%, and the calorific value is 29.6 MJ / kg, of which monocyclic aromatic hydrocarbons account for 35.2% of the oil phase. The yield of combustible gas is 36%, with a calorific value of 14.8 MJ / m³. 3 .

[0042] Comparing the results in Example 1, it can be seen that the addition of fireworks residue can improve the yield and quality of bio-oil (the proportion of monocyclic aromatic hydrocarbons increases by 6.4 percentage points). This is attributed to the Diels-Alder reaction between the terpenoids remaining in the fireworks and the olefins produced by PE cracking during pyrolysis, which promotes the formation of aromatic hydrocarbons.

[0043] Comparative Example 2 In this comparative example, the method for co-producing high-value products by cascade pyrolysis of tobacco field waste is basically the same as in Example 1. The difference is that in step S3, no composite catalyst is used, and the temperature of the high-temperature pyrolysis zone is 550°C.

[0044] Testing revealed that the yield of functionalized tobacco biochar was 25.1%. The yield of bio-oil was 28.6%, with an oxygen content of 28.3% and a calorific value of 21.4 MJ / kg, of which monocyclic aromatic hydrocarbons accounted for 12.7% of the oil phase. The yield of combustible gas was 46.3%.

[0045] Comparing the results in Example 1, it can be seen that the introduction of the composite catalyst reduced the oxygen content of bio-oil by 15.5 percentage points, increased the calorific value by 10.7 MJ / kg, and increased the proportion of monocyclic aromatic hydrocarbons by 28.9 percentage points, demonstrating a significant catalytic effect.

[0046] Comparative Example 3 In this comparative example, the method for co-producing high-value products by cascade pyrolysis of tobacco field waste is basically the same as in Example 1. The difference is that in step S3, pyrolysis at a single temperature range of 500°C for 45 minutes is directly adopted.

[0047] Testing revealed that the yield of functionalized tobacco biochar was 26.8%. The yield of bio-oil was 30.1%, with an oxygen content of 18.6% and a calorific value of 26.3 MJ / kg. The yield of combustible gas was 43.1%.

[0048] Comparing the results in Example 1, it can be seen that the stepped temperature design allows the low-boiling-point volatiles in the fireworks to be fully released in the low-temperature zone and avoids excessive decomposition at high temperatures. At the same time, the smoke rod and PE react deeply in the high-temperature zone, increasing the yield of bio-oil by 6.1 percentage points and reducing the oxygen content by 5.8 percentage points.

[0049] Comparative Example 4 In this comparative example, the method for co-producing high-value products by cascade pyrolysis of tobacco field waste is basically the same as in Example 1. The difference is that in step S1, the active ingredients of fireworks are not extracted, and all fireworks particles are used for pyrolysis treatment in step S3.

[0050] The bio-oil yield was 37.8%, the oxygen content was 17.2%, and the calorific value was 25.8 MJ / kg.

[0051] Comparing the results in Example 1, it can be seen that high-value components such as cephalotrindiol and chlorogenic acid in fireworks are decomposed during pyrolysis and cannot be recycled, resulting in resource waste. The pre-extraction strategy not only recovers high-value active components (cephalotrindiol, chlorogenic acid, etc. have economic value far higher than pyrolysis products), but also improves the quality of subsequent pyrolysis products by removing some oxygen- and nitrogen-containing components.

[0052] Application test cases The functionalized tobacco biochar prepared in Example 1 was mixed with tobacco-specific fertilizer at a ratio of 2:8 to prepare a carbon-based fertilizer. When applied to tobacco fields, the amount of chemical fertilizer used was reduced by 25%, and the incidence of tobacco aphids was reduced by 22%.

[0053] Furthermore, the bio-oil prepared in Example 1 was hydrogenated and refined for use in heating intensive tobacco curing rooms, replacing approximately 30% of coal.

[0054] Furthermore, the combustible gas prepared in Example 1 is reused for heating in a horizontal rotary kiln, achieving a system self-heating rate of over 85%.

[0055] In addition, the present invention has at least the following advantages: 1) Comprehensive Disposal and Integrated Treatment of Three Types of Waste: This invention is the first to integrate tobacco stalks, fireworks, and waste plastic film from tobacco fields into a single pyrolysis system for synergistic treatment, achieving comprehensive disposal of tobacco field waste. Existing technologies typically only process tobacco stalks or separately recycle plastic film, with fireworks generally not included in the resource recovery system. This invention overcomes the technical challenge of the significant differences in the physical properties of the three types of waste, achieving synergistic pyrolysis through stepped temperatures and optimized proportions to obtain high-value products.

[0056] 2) tiered utilization: high-value components are extracted first and then pyrolyzed: This invention pioneers a tiered utilization strategy of "pre-extraction of active components from fireworks + pyrolysis of residues." High-value active components (such as cephalotrimethylenediol, chlorogenic acid, and nicotine) abundant in fireworks but decompose upon pyrolysis are first recovered through supercritical CO2 extraction and ethanol leaching. More than 12 kg of cephalotrimethylenediol and more than 6 kg of chlorogenic acid can be recovered per ton of dry fireworks, with economic value far exceeding that of direct pyrolysis. The extracted residue is then fed into the pyrolysis system, achieving complete utilization. Furthermore, pre-extraction removes some oxygen-containing components, optimizing the distribution of subsequent pyrolysis products.

[0057] 3) Synergistic effect, significantly improving the quality of bio-oil: This invention utilizes the synergistic effect between hydrogen free radicals and olefins generated by the cracking of PE mulch film and oxygen-containing compounds generated by the pyrolysis of tobacco rods / fireworks biomass. Under the action of a composite catalyst, through Diels-Alder reaction and aromatization reaction, the oxygen content of bio-oil is reduced from more than 28% to less than 15%, the calorific value is increased from 21MJ / kg to more than 32MJ / kg, the proportion of monocyclic aromatic hydrocarbons is increased by nearly 30 percentage points, and the quality of bio-oil is significantly improved.

[0058] 4) Stepped temperature design to take into account the optimal pyrolysis conditions of different components: The present invention adopts a stepped temperature design of low temperature zone (300-400℃) + high temperature zone (480-560℃). The low temperature zone prioritizes the release of low thermal stability components in fireworks (volatile oil, hemicellulose, etc., with the main pyrolysis temperature of 250-350℃), avoiding excessive decomposition of them at high temperature to generate small molecule gases; the high temperature zone ensures the deep decomposition of cellulose, lignin and PE film in the smoke rod (cellulose pyrolysis temperature 300-400℃, PE pyrolysis temperature 440-525℃), so that both types of raw materials are in the optimal pyrolysis temperature window, which significantly improves the performance of high-value products.

[0059] 5) Closed-loop reuse to build a green cycle for tobacco fields: This invention reuses pyrolysis products in a targeted manner in the tobacco field system. Functionalized tobacco biochar is used to make charcoal base fertilizer and returned to the field (water and fertilizer retention, slow-release insecticide), bio-oil is used for heating during curing, combustible gas is reused for self-heating in the pyrolysis system, and fireworks extract is used as a natural flavoring for tobacco. This forms a complete closed loop of "from the tobacco field and back to the tobacco field", reducing the use of chemical fertilizers and pesticides by 20-30% and reducing coal consumption for curing by more than 30%, thus realizing the green, low-carbon, and circular development of tobacco fields.

[0060] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0061] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for the co-production of high-value products from the cascade pyrolysis of tobacco field waste, characterized in that, The steps include the following: Pre-treated smoke rods, pre-treated fireworks, and pre-treated waste plastic film are provided respectively; A portion of the pretreated fireworks was subjected to the first and second extractions in sequence to obtain the first extract, the second extract, and fireworks residue, respectively. The mixture of the pretreated smoke rod, the remaining pretreated fireworks and fireworks residue, and the pretreated waste plastic film is subjected to a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment in sequence to obtain the product. After separation, the products were obtained as functionalized tobacco biochar, bio-oil and combustible gas. The temperature of the first pyrolysis treatment is lower than the temperature of the second pyrolysis treatment.

2. The method according to claim 1, characterized in that, In the steps of providing pretreated smoke rods, pretreated fireworks, and pretreated waste plastic film, the pretreated smoke rods have a moisture content of ≤15% and a particle size of 5-20mm. The pretreated fireworks have a moisture content of ≤15%; the pretreated waste plastic film has a particle size of 5-15mm.

3. The method according to claim 1, characterized in that, In the step of taking a portion of pre-treated fireworks and sequentially performing the first and second extractions to obtain the first extract, the second extract, and fireworks residue, the portion of pre-treated fireworks accounts for 60-80% of the total mass of the pre-treated fireworks; The first extraction includes supercritical CO2 extraction, which specifically includes: using supercritical CO2 as a solvent, extracting for 2-3 hours under the conditions of an extraction pressure of 25-35 MPa, an extraction temperature of 40-50℃, and a CO2 flow rate of 15-25 L / h. The first extract includes at least one of cephalothrix trienyl alcohol and volatile oil; wherein the volatile oil includes linalool and β-damascone.

4. The method according to claim 1, characterized in that, In the step of taking a portion of pretreated fireworks and sequentially performing the first and second extractions to obtain the first extract, the second extract, and fireworks residue, the second extraction includes ethanol-water extraction. The ethanol-water extraction specifically includes: using 60-80% ethanol-water solution as solvent, controlling the material-to-liquid ratio at 1g:(8-12mL), reflux extraction at 50-60℃ for 2-3 times, 1-2 hours each time, combining the extracts, and concentrating under reduced pressure. The second extract includes at least one of polyphenolic compounds and alkaloids; wherein the polyphenolic compounds include at least one of chlorogenic acid and rutin, and the alkaloids include nicotine.

5. The method according to claim 1, characterized in that, In the steps of sequentially subjecting the pretreated smoke rod, the remaining pretreated fireworks and fireworks residue, and the pretreated waste mulch film to a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment, the particle size of the remaining pretreated fireworks and fireworks residue is 2-10 mm. The mass ratio of the pretreated smoke rod, the remaining pretreated fireworks and fireworks residue, and the pretreated waste plastic film is (50-70):(10-25):(15-30). The effective hydrogen-to-carbon ratio of the mixture is 0.8-1.

4.

6. The method according to claim 1, characterized in that, In the steps of sequentially subjecting the pretreated smoke rod, the remaining pretreated fireworks and fireworks residue, and the pretreated waste mulch film to a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment, the first pyrolysis treatment specifically includes: pyrolysis at a temperature of 300-400℃ for 10-20 minutes. The second pyrolysis treatment specifically includes: pyrolysis at a temperature of 480-560℃ for 20-40 minutes; The post-catalytic treatment is used to simultaneously catalyze the products of the second pyrolysis treatment, and the catalyst in the catalytic reaction includes a composite catalyst, which includes HZSM-5 molecular sieve, CaO and Fe2O3, and the amount of the composite catalyst added is 10-20% of the mass of the mixed materials; The mass ratio of the HZSM-5 molecular sieve, the CaO and the Fe2O3 is (60-80):(10-30):(5-15), and the silicon-aluminum ratio in the HZSM-5 molecular sieve is (25-50):

1.

7. The method according to claim 1, characterized in that, In the step of separating the products to obtain functionalized tobacco biochar, bio-oil, and combustible gas, the specific surface area of ​​the functionalized tobacco biochar is 50-200 m². 2 / g, carbon content ≥65%.

8. The method according to claim 1, characterized in that, In the step of separating the product to obtain functionalized tobacco biochar, bio-oil, and combustible gas, the bio-oil has an oxygen content ≤15% and a calorific value of 28-35 MJ / kg; the bio-oil contains 40-45% monocyclic aromatic hydrocarbons. The monocyclic aromatic hydrocarbon includes at least one of benzene, toluene, and xylene.

9. The method according to claim 1, characterized in that, In the step of separating the products to obtain functionalized tobacco biochar, bio-oil, and combustible gas, the calorific value of the combustible gas is 12-18 MJ / m³. 3 The combustible gas includes at least one of H2, CO, CH4, and C2-C3 hydrocarbons.

10. A system for the cascade pyrolysis of tobacco field waste to co-produce high-value products, characterized in that, include: A pretreatment unit is used to provide pretreated smoke rods, pretreated fireworks, and pretreated waste plastic film, respectively. An extraction unit is used to sequentially perform a first extraction and a second extraction on a portion of pre-treated fireworks to obtain a first extract, a second extract, and fireworks residue, respectively. A stepped pyrolysis reaction unit is used to sequentially perform a first pyrolysis treatment, a second pyrolysis treatment, and a post-catalytic treatment on the mixture of the pretreated smoke rod, the remaining pretreated fireworks and fireworks residue, and the pretreated waste mulch film to obtain the product; The product separation and collection unit is used to separate the products to obtain functionalized tobacco biochar, bio-oil and combustible gas.

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