Method for preparing carbon through organic matter pyrolysis

Abstract

The invention discloses a method for preparing carbon by pyrolyzing organic matters, which comprises the following steps: S1, wrapping organic solid wastes with a magnetic metal heating medium, and pyrolyzing to obtain a mixed product of charcoal and the magnetic metal heating medium; and the magnetic metal heat medium is utilized to assist the organic solid waste in effective pyrolysis to prepare the biochar.

Description

Technical Field

[0001] The present invention relates to the field of environmental engineering, and in particular to a method for producing carbon by pyrolysis of organic matter. Background Art

[0002] As a new type of thermochemical conversion technology, organic solid waste pyrolysis can decompose organic solid waste such as agricultural and forestry waste, restaurant waste, and municipal sludge into biochar, pyrolysis oil, and combustible gas by high-temperature heating at 300-800°C in an oxygen-free or low-oxygen environment, thereby achieving waste reduction and resource utilization.

[0003] Currently, industrial pyrolysis reactors are primarily moving beds, fixed beds, fluidized beds, and rotary kilns. Traditional pyrolysis devices, such as fluidized bed pyrolysis furnaces and rotary kiln pyrolysis furnaces, require control over parameters such as oxygen intake, pyrolysis temperature, and residence time. Their operation and management require high technical requirements. During the heating process, inert gases such as nitrogen and helium are continuously introduced to remove oxygen and other components from the air, preventing organic matter from burning upon contact with oxygen during the pyrolysis process, thereby converting pyrolytic carbon into carbon dioxide gas. This results in high energy costs and often poor pyrolysis results, resulting in a high biochar yield and a low fixed carbon content. Furthermore, these devices are difficult to miniaturize and are particularly unsuitable for small-scale organic solid waste treatment in households and residential areas. Currently, the comprehensive utilization rate of organic solid waste in my country is less than 40%, and there is an urgent need for treatment of small, dispersed sources. Summary of the Invention

[0004] Purpose of the present invention: In order to overcome the defects of the prior art, the present invention provides a method for pyrolysis and carbonization of organic matter, which utilizes magnetic metal heat media to assist in the effective pyrolysis and carbonization of organic solid waste.

[0005] The technical solution of the present invention is a method for producing carbon by pyrolysis of organic matter, comprising step S1: wrapping organic solid waste with a magnetic metal heat medium and pyrolyzing the organic solid waste to obtain a mixed product of biochar and the magnetic metal heat medium.

[0006] By adopting the above technical solution: The present invention provides a new type of pyrolysis method, which adds a magnetic metal heat medium to assist pyrolysis on the basis of traditional pyrolysis. It mainly utilizes the heat transfer and air exchange restriction functions of the magnetic metal heat medium. During the pyrolysis process, it can absorb the heat of the heating source to increase the temperature, and through its good conduction effect, it accelerates the heat transfer to the internal organic solid waste wrapped by it, and has the function of serving as a heat conduction medium; and by wrapping the magnetic metal heat medium on the outside of the organic solid waste, it restricts the air to achieve oxygen restriction, so that the organic solid waste can achieve a good pyrolysis effect in an oxygen-deficient environment. Therefore, there is no need to use inert gas, and it has the advantages of flexible operation, easy use, good safety performance, good pyrolysis effect, etc. It can be applied to common small heating devices such as muffle furnaces for heating. It is easy to apply to small household occasions such as communities and homes.

[0007] Then, the metal heat medium is separated by magnetic separation through a magnetic drum iron remover to obtain biochar.

[0008] A further configuration of the present invention includes step S2: separating the magnetic metal heat medium from the biochar in the mixed product by a magnetic drum iron remover, wherein the separated magnetic metal heat medium is reused for the pyrolysis in step S1.

[0009] With the above further configuration, the magnetic metal heat medium can be basically recovered after being separated by the magnetic drum iron remover and put into use in the next cycle of pyrolysis.

[0010] The present invention is further provided with: the magnetic metal heat medium is a metal or metal oxide having magnetism, low specific heat capacity and high thermal conductivity.

[0011] This further configuration further improves pyrolysis efficiency while maintaining the magnetic and thermal conductivity properties of the metallic heat medium. The low specific heat capacity means that during heating, these media absorb and transfer heat quickly, reducing energy consumption. The high thermal conductivity ensures even distribution of heat within the media, improving the uniformity and efficiency of the pyrolysis process.

[0012] The present invention is further provided that the magnetic metal heat medium is iron, nickel or its oxide, and its specific heat capacity ranges from 0.3 to 0.5 kJ / (kg·K) and its thermal conductivity ranges from 60 to 100 W / (m·K).

[0013] Taking the above arrangement a step further, iron, nickel, or their oxides are used as the magnetic metal heat medium. This is not only because these materials possess significant magnetic properties, facilitating subsequent magnetic separation, but also because they possess low specific heat capacity and high thermal conductivity. Furthermore, iron, nickel, and their oxides are highly stable under pyrolysis conditions and are not susceptible to chemical reactions, thus ensuring the purity and quality of the pyrolysis products.

[0014] A further configuration of the present invention is that the magnetic metal heat medium is in powder form, and its particle size is ≤10 mm.

[0015] With this further configuration, the powdered magnetic metal heat medium has a larger surface area, enabling more effective contact with the organic matter, thereby improving pyrolysis efficiency. Furthermore, the design of a particle size of ≤10mm facilitates uniform distribution in the reactor, further improving the uniformity and efficiency of pyrolysis.

[0016] The present invention is further configured as follows: Step S1: Wrapping the granular organic solid waste with a powdered magnetic metal heat medium and placing the granular organic solid waste into a pyrolysis furnace for heating and pyrolysis, wherein the pyrolysis furnace temperature is 300-500° C. and the pyrolysis time is ≥0.5 h.

[0017] By further implementing the above configuration, granular organic solid waste is wrapped with a powdered magnetic metal heat medium, ensuring full contact between the organic matter and the heat medium and promoting efficient heat transfer. At a pyrolysis furnace temperature of 300-500°C, the organic matter can be fully decomposed to produce high-quality carbon products. At the same time, the setting of a pyrolysis time of ≥0.5h ensures the full progress of the pyrolysis process and avoids incomplete pyrolysis caused by too short a time. This pyrolysis method not only improves the yield and quality of carbon products, but also effectively reduces energy consumption and production costs.

[0018] The present invention is further configured as follows: the organic solid waste raw material is dried and crushed to obtain granular organic solid waste, the particle size of which is ≤3 cm and the moisture content is ≤25%.

[0019] The above-mentioned further configuration ensures that the raw materials have an appropriate particle size and moisture content before entering the pyrolysis furnace, which is conducive to improving pyrolysis efficiency and product quality. The design of a particle size of ≤3cm ensures that the internal and external heat is evenly distributed during heating, facilitating carbonization and achieving good carbonization results.

[0020] The present invention is further configured as follows: the magnetic field region of the magnetic drum remover is formed by a magnet or an electromagnet, and the magnetic field strength thereof is ≥0.5T.

[0021] With the above further configuration, when the magnetic field strength is greater than 0.5 Tesla, a good removal effect of the magnetic heat medium can be achieved, ensuring the effective separation of magnetic impurities during the pyrolysis process and avoiding the negative impact of magnetic substances on the quality of carbon products.

[0022] The present invention is further provided with: a mass ratio of the magnetic metal heat medium to the organic solid waste is 300-800%, preferably 500%.

[0023] With the above further configuration, according to existing experimental results, for different types of organic solid waste, a good pyrolysis effect can be achieved when the mass of the added magnetic metal heat medium is 300-800% of the mass of the organic solid waste.

[0024] A further configuration of the present invention is that it can be used to wrap granular organic solid waste with powdered magnetic metal heat medium.

[0025] By adopting the above-mentioned further settings, different types of organic solid waste such as kitchen waste, garden waste, paper, discarded furniture, etc. can be processed and utilized on-site. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Comparison of biochar yield, ash content, volatile matter, and fixed carbon between Example 1 and Comparative Example 1; Figure 2Comparison of biochar yield, ash content, volatile matter, and fixed carbon between Example 2 and Comparative Example 2; Figure 3 Comparison of biochar yield, ash content, volatile matter, and fixed carbon between Example 3 and Comparative Example 3; Figure 4 Comparison chart of biochar yield, ash content, volatile matter, and fixed carbon for Examples 1, 4, and 7; Figure 5 Comparison chart of biochar yield, ash content, volatile matter, and fixed carbon for Examples 2, 5, and 8; Figure 6 Comparison chart of biochar yield, ash, volatile matter, and fixed carbon for Examples 3, 6, and 9. DETAILED DESCRIPTION

[0027] The present invention provides a method for producing carbon by pyrolysis of organic matter, comprising: Step S1: wrapping the organic solid waste with a magnetic metal heat medium and pyrolyzing it to obtain a mixed product of biochar and the magnetic metal heat medium. Specifically, the organic solid waste raw material is dried and crushed to obtain granular organic solid waste with a particle size of ≤3 cm and a moisture content of ≤25%. The granular organic solid waste is wrapped with a powdered magnetic metal heat medium and placed in a pyrolysis furnace for heating and pyrolysis. The pyrolysis furnace temperature is 300-500° C. and the pyrolysis time is ≥0.5 h. The magnetic metal heat medium is a metal or metal oxide having magnetism, low specific heat capacity and high thermal conductivity. The magnetic metal heat medium is preferably iron, nickel or its oxide, with a specific heat capacity range of 0.3-0.5 kJ / (kg·k) and a thermal conductivity of 60-100 W / (m·K). The magnetic metal heat medium is in powder form with a particle size of ≤10 mm, and the mass ratio of the magnetic metal heat medium to the organic solid waste is ≥500%. Step S2: The magnetic metal heat medium in the mixed product is separated from the biochar using a magnetic drum separator. The separated magnetic metal heat medium is reused for the pyrolysis in step S1. The magnetic drum separator is formed by a magnetic field region using magnets or electromagnets, and its magnetic field strength is ≥ 0.5 T. The magnetic drum separator is a disk made of magnets or electromagnets. The magnetic material is adsorbed on its surface by the rotation of the disk, and then forcibly removed by a separation brush, thereby separating the magnetic metal heat medium from the surface of the magnetic drum separator.

[0028] In the metal heat medium assisted biomass pyrolysis of the present invention, the metal heat medium itself covers the biomass to achieve oxygen-limited conditions. The high thermal conductivity of the metal heat medium plays a role in assisting heat transfer. By regulating the metal heat medium to more than 500% of the mass of the organic solid waste particles, the heat transfer efficiency and oxygen-limited conditions are controlled, thereby improving the production efficiency of biochar.

[0029] Example 1 (pyrolysis temperature 300°C, mass ratio of metal heat medium to organic solid waste 500%) The specific conditions are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0030] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and mix 5 g of the organic solid waste particles with 25 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 300°C at a heating rate of 5°C / min, and maintain constant temperature for 0.5h for pyrolysis. Collect the biochar after pyrolysis.

[0031] After collection and measurement, the biochar yield was 45.4%, ash: 8.6%, volatile matter: 45.7%, and fixed carbon: 45.7%.

[0032] Example 2 (pyrolysis temperature 400°C, mass ratio of metal heat medium to organic solid waste 500%) The specific conditions are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0033] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and mix 5 g of the organic solid waste particles with 25 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 400°C at a heating rate of 5°C / min, and maintain constant temperature for 0.5h for pyrolysis. Collect the biochar after pyrolysis.

[0034] After collection and measurement, the biochar yield was 31.6%, ash: 11.2%, volatile matter: 25.5%, and fixed carbon: 63.3%.

[0035] Example 3 (pyrolysis temperature 500°C, mass ratio of metal heat medium to organic solid waste 500%) The specific conditions are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0036] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and mix 5 g of the organic solid waste particles with 25 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 500°C at a heating rate of 5°C / min, and maintain the constant temperature for 0.5h for pyrolysis. Collect the biochar after the pyrolysis is completed.

[0037] After collection and measurement, the biochar yield was 27.7%, ash: 11.9%, volatile matter: 17.2%, and fixed carbon: 70.9%.

[0038] Example 4 (pyrolysis temperature 300°C, mass ratio of metal heat medium to organic solid waste 300%) The specific conditions are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0039] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and evenly mix 5 g of the organic solid waste particles with 15 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 300°C at a heating rate of 5°C / min, and maintain constant temperature for 0.5h for pyrolysis. Collect the biochar after pyrolysis.

[0040] After collection and measurement, the biochar yield was 53.2%, ash: 7.4%, volatile matter: 53.6%, and fixed carbon: 39.6%.

[0041] Example 5 (pyrolysis temperature 400°C, mass ratio of metal heat medium to organic solid waste 300%) The specific conditions are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0042] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and evenly mix 5 g of the organic solid waste particles with 15 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 400°C at a heating rate of 5°C / min, and maintain constant temperature for 0.5h for pyrolysis. Collect the biochar after pyrolysis.

[0043] After collection and measurement, the biochar yield was 33.3%, ash: 11%, volatile matter: 32.3%, and fixed carbon: 56.7%.

[0044] The specific conditions of Example 6 (pyrolysis temperature 500°C, mass ratio of metal heat medium to organic solid waste 300%) are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0045] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and evenly mix 5 g of the organic solid waste particles with 15 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 500°C at a heating rate of 5°C / min, and maintain the constant temperature for 0.5h for pyrolysis. Collect the biochar after the pyrolysis is completed.

[0046] After collection and measurement, the biochar yield was 28.7%, ash: 13.8%, volatile matter: 24.1%, and fixed carbon: 62.1%.

[0047] The specific conditions of Example 7 (pyrolysis temperature 300°C, mass ratio of metal heat medium to organic solid waste 800%) are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0048] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and evenly mix 5 g of the organic solid waste particles with 40 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 300°C at a heating rate of 5°C / min, and maintain constant temperature for 0.5h for pyrolysis. Collect the biochar after pyrolysis.

[0049] After collection and measurement, the biochar yield was 60.8%, ash: 7%, volatile matter: 63.1%, and fixed carbon: 29.9%.

[0050] Example 8 (pyrolysis temperature 400°C, mass ratio of metal heat medium to organic solid waste 800%) The specific conditions are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0051] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and mix 5 g of the organic solid waste particles with 40 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 400°C at a heating rate of 5°C / min, and maintain constant temperature for 0.5h for pyrolysis. Collect the biochar after pyrolysis.

[0052] After collection and measurement, the biochar yield was 36.4%, ash: 10.4%, volatile matter: 32.5%, and fixed carbon: 57.1%.

[0053] Example 9 (pyrolysis temperature 500°C, mass ratio of metal heat medium to organic solid waste 800%) The specific conditions are as follows: 1. Place the organic solid waste raw material in a drying oven and dry it at 105°C for 24 hours to obtain dry organic solid waste.

[0054] 2. Grind the dried organic solid waste into particles smaller than 3 cm; and mix 5 g of the organic solid waste particles with 40 g of a magnetic metal heat medium (iron powder) to obtain a mixture; 3. Place the mixture in a muffle furnace, heat the muffle furnace to 500°C at a heating rate of 5°C / min, and maintain the constant temperature for 0.5h for pyrolysis. Collect the biochar after the pyrolysis is completed.

[0055] After collection and measurement, the biochar yield was 28.3%, ash: 13.8%, volatile matter: 19.2%, and fixed carbon: 67%.

[0056] Comparative Examples 1-3 (using the traditional pyrolysis process and introducing nitrogen at a rate of 30 mL / min in the tubular furnace) Comparative Example 1 and Example 1 had the same heating rate (5°C / min), pyrolysis temperature (300°C) and residence time (0.5h); Comparative Example 2 had the same heating rate (5°C / min), pyrolysis temperature (400°C) and residence time (0.5h) as Example 2; Comparative Example 3 and Example 3 have the same heating rate (5°C / min), pyrolysis temperature (500°C) and residence time (0.5h).

[0057] Conclusion: The data from Examples 1-9 and Comparative Examples 1-3 demonstrate that when the magnetic metal heat medium is added at a mass ratio of 300-800% to the organic solid waste and the pyrolysis temperature is 300-500°C, the magnetic metal heat medium accelerates heat transfer, evens out heating, and increases feedstock conversion efficiency during the pyrolysis process. As the pyrolysis efficiency improves, the biochar yield decreases, and the three industrial analysis indicators—volatile matter decreases, ash increases, and fixed carbon—increase. The best results are achieved at a pyrolysis temperature of 500°C and a magnetic metal heat medium to organic solid waste mass ratio of 500%. The present invention demonstrates significant pyrolysis-enhancing effects, producing low biochar yields while significantly increasing fixed carbon content, achieving a high degree of carbonization, and maintaining strong stability, enabling efficient conversion of organic solid waste. Compared to traditional processes, the present invention does not require inert gases such as nitrogen and helium, reducing pyrolysis costs. Furthermore, the low biochar production rate conserves energy required during the pyrolysis process, making it suitable for small-scale production.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for producing carbon by pyrolysis of organic matter, characterized in that: The method comprises step S1: wrapping the organic solid waste with a magnetic metal thermal medium and pyrolyzing the organic solid waste to obtain a mixed product of biochar and the magnetic metal thermal medium.

2. The method for producing carbon by pyrolysis of organic matter according to claim 1, characterized in that: The method comprises step S2: separating the magnetic metal heat medium and the biochar in the mixed product by a magnetic drum iron remover, wherein the separated magnetic metal heat medium is reused for the pyrolysis in step S1.

3. The method for producing carbon by pyrolysis of organic matter according to claim 1 or 2, characterized in that: The magnetic metal heat medium is a metal or metal oxide having magnetism, low specific heat capacity and high thermal conductivity.

4. The method for producing carbon by pyrolysis of organic matter according to claim 3, characterized in that: The magnetic metal heat medium is iron, nickel or its oxides, with a specific heat capacity range of 0.3-0.5kJ / (kg·K) and a thermal conductivity of 60-100W / (m·K).

5. The method for producing carbon by pyrolysis of organic matter according to claim 1 or 2, characterized in that: The magnetic metal heat medium is in powder form, and its particle size is ≤10mm.

6. The method for producing carbon by pyrolysis of organic matter according to claim 1 or 2, characterized in that: Step S1: Wrap the granular organic solid waste with powdered magnetic metal heat medium and put it into a pyrolysis furnace for heating and pyrolysis. The pyrolysis furnace temperature is 300-500° C. and the pyrolysis time is ≥0.5 h.

7. The method for producing carbon by pyrolysis of organic matter according to claim 6, characterized in that: The organic solid waste raw material is dried and crushed to obtain granular organic solid waste with a particle size of ≤3 cm and a moisture content of ≤25%.

8. The method for producing carbon by pyrolysis of organic matter according to claim 1 or 2, characterized in that: The mass ratio of the magnetic metal heat medium to the organic solid waste is 300-800%, preferably 500%.

9. The method for producing carbon by pyrolysis of organic matter according to claim 2, characterized in that: The magnetic field region of the magnetic drum remover is formed by a magnet or an electromagnet, and the magnetic field strength thereof is ≥0.5T.

10. The method for producing carbon by pyrolysis of organic matter according to claim 1 or 2, characterized in that: It can be used to wrap granular organic solid waste with powdered magnetic metal heat medium.

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