A method and apparatus for producing a high-value combustible gas

Abstract

This invention provides a method and apparatus for preparing high-value combustible gas. The method includes: heating and dehydrating straw under negative pressure using an electromagnetic induction heating device to obtain primary char; extruding the primary char into rods and then pyrolyzing it in a microwave pyrolysis device to release pyrolysis gas and obtain secondary char; introducing the pyrolysis gas into an electromagnetic induction heating device for deep pyrolysis to convert it into combustible gas. This invention combines electromagnetic induction heating and microwave heating technologies, specifically comprising three stages: in the first stage, after negative pressure electromagnetic induction heating, the slightly carbonized straw is extruded into rods; in the second stage, the rod-shaped char is pyrolyzed using microwave technology; and finally, in the third stage, the generated pyrolysis gas is subjected to electromagnetic induction high-temperature deep pyrolysis, thereby improving the calorific value and cleanliness of the combustible gas while reducing tar formation, and obtaining high-quality combustible gas based on multi-stage refined control.

Description

Technical Field

[0001] This invention relates to the field of biomass energy technology, and in particular to a method and apparatus for preparing high-value combustible gas. Background Technology

[0002] With the increasing demand for renewable energy, the efficient conversion and comprehensive utilization of biomass resources are receiving growing attention. Straw, a common biomass raw material, is often subjected to single-heating processes (such as direct combustion furnaces) in traditional pyrolysis or gasification, resulting in low heating efficiency, high tar production, and poor combustible gas quality. Electromagnetic induction heating and microwave heating (microwave pyrolysis) each have their advantages: the former can rapidly convert electrical energy into heat energy and achieve efficient heat transfer under negative pressure; the latter allows for simultaneous heating of the material's interior, with rapid temperature rise and a controllable process.

[0003] If electromagnetic induction heating and microwave heating technologies could be combined, it would be possible to produce high-quality combustible gas; however, there is currently no solution for combining electromagnetic induction heating and microwave heating technologies to produce high-quality combustible gas. Summary of the Invention

[0004] The present invention aims to provide a method and apparatus for preparing high-value combustible gas. The method involves extruding slightly carbonized straw into rods after a first stage of negative pressure electromagnetic induction heating, then using microwave technology to pyrolyze the rod-shaped charcoal in a second stage, and finally performing electromagnetic induction high-temperature deep pyrolysis on the generated pyrolysis gas in a third stage, thereby improving the calorific value and cleanliness of the combustible gas while reducing tar formation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing high-value natural gas, comprising the following steps:

[0007] S1. Under negative pressure conditions, the straw is heated, dehydrated, and lightly carbonized using an electromagnetic induction heating device to obtain primary charcoal.

[0008] S2. After the primary carbon is extruded into shape, it is placed in a microwave pyrolysis device for pyrolysis to release pyrolysis gas and obtain secondary carbon.

[0009] S3. The pyrolysis gas is introduced into an electromagnetic induction heating device for deep pyrolysis and converted into combustible gas.

[0010] Preferably, the straw is heated to 200-300°C using a magnetic induction heating device and kept under a negative pressure of -0.005MPa to -0.08MPa for 10-50 minutes to heat, dehydrate, and lightly carbonize the straw to obtain primary charcoal.

[0011] The magnetic induction heating device has a power of 10–30 kW, a frequency of 40–100 kHz, and a current of 10–30 A.

[0012] Preferably, the primary char is extruded into rods or blocks with a diameter of 10-30 mm, placed in a microwave pyrolysis device, and pyrolyzed at 400-800°C for 2-10 min to release volatiles and obtain secondary char.

[0013] The microwave power of the microwave pyrolysis device is 3 to 10 kW, and the microwave frequency is 2000 to 3000 MHz.

[0014] Preferably, the pyrolysis gas is introduced into an electromagnetic induction heating device and pyrolyzed at 600-800°C for 5-20 minutes to convert it into combustible gas.

[0015] Preferably, the process also includes cooling, dust removal, and / or deacidification of the obtained combustible gas.

[0016] Secondly, the present invention also provides an apparatus for preparing high-value combustible gas for carrying out the method, comprising:

[0017] The negative pressure electromagnetic induction heating unit is used to heat and dehydrate straw under negative pressure conditions and lightly carbonize it to obtain primary char.

[0018] An extrusion molding unit is used to extrude primary carbon into shape;

[0019] The microwave pyrolysis unit is used to microwave pyrolyze the primary carbon after it has been extruded and shaped.

[0020] The electromagnetic induction deep pyrolysis unit is used to perform deep pyrolysis of the pyrolysis gas generated during microwave pyrolysis.

[0021] Preferably, the negative pressure electromagnetic induction heating unit includes:

[0022] The electromagnetic induction heating chamber has a straw inlet at one end and a primary charcoal outlet at the other end.

[0023] A first electromagnetic induction coil is disposed on the electromagnetic induction heating cavity;

[0024] The first electromagnetic induction control unit is disposed on the electromagnetic induction heating cavity and is used to control the operation of the first electromagnetic induction coil.

[0025] A negative pressure pump, located on the electromagnetic induction heating chamber, is used to evacuate the electromagnetic induction heating chamber.

[0026] The extrusion molding unit has a primary carbon feed inlet and a molding outlet, and the primary carbon feed inlet and the primary carbon outlet are connected.

[0027] The microwave pyrolysis unit includes:

[0028] A microwave pyrolysis chamber is provided with a pyrolysis feed inlet and a pyrolysis gas outlet, wherein the pyrolysis feed inlet is connected to the forming outlet.

[0029] A microwave generator is mounted on the microwave pyrolysis cavity;

[0030] The microwave control unit, which is located on the microwave pyrolysis cavity, is used to control the operation of the microwave generator;

[0031] The electromagnetic induction depth fragmentation unit includes:

[0032] An electromagnetic induction deep pyrolysis chamber is provided with a pyrolysis gas inlet, which is connected to a pyrolysis gas outlet.

[0033] A second electromagnetic induction coil is disposed on the electromagnetic induction depth pyrolysis cavity;

[0034] The second electromagnetic induction control unit is disposed on the electromagnetic induction depth pyrolysis cavity and is used to control the operation of the second electromagnetic induction coil.

[0035] Preferably, it further includes a gas processing unit, the gas processing unit comprising:

[0036] The gas purification system has a combustible gas outlet at one end of the electromagnetic induction deep pyrolysis chamber away from the pyrolysis gas inlet. The combustible gas outlet is connected to the gas purification system for purifying the combustible gas.

[0037] A gas collection tank, which is connected to the gas purification system.

[0038] Preferably, the electromagnetic induction deep pyrolysis unit further includes:

[0039] A condenser, the feed end of which is connected to the pyrolysis gas outlet;

[0040] An oil storage tank, one end of which is connected to the discharge end of the condenser and the other end of which is connected to the pyrolysis gas inlet.

[0041] Preferably, the negative pressure electromagnetic induction heating unit further includes:

[0042] The screw feed rod is located inside the electromagnetic induction heating chamber;

[0043] A feeding motor is mounted on the electromagnetic induction heating chamber, and the feeding motor shaft is connected to the screw feed rod to drive the screw feed rod to rotate.

[0044] The microwave pyrolysis cavity is also equipped with a stirrer;

[0045] The microwave pyrolysis chamber is also equipped with a secondary carbon discharge port.

[0046] The method and apparatus for preparing high-value combustible gas of the present invention have the following advantages over the prior art:

[0047] The present invention provides a method for preparing high-value combustible gas by combining electromagnetic induction heating and microwave heating technologies. Specifically, it includes three stages: in the first stage, after negative pressure electromagnetic induction heating, slightly carbonized straw is compressed into rods; in the second stage, microwave technology is used to pyrolyze the rod-shaped charcoal; and finally, in the third stage, the generated pyrolysis gas is subjected to electromagnetic induction high-temperature deep pyrolysis, thereby improving the calorific value and cleanliness of the combustible gas while reducing tar formation. High-quality combustible gas is obtained based on multi-stage refined control. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This invention relates to an apparatus for preparing high-value combustible gas. Detailed Implementation

[0050] 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 a part of the embodiments of the present invention, and not all of the 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.

[0051] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms such as "above" is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use, or the orientation or positional relationship in which those skilled in the art are usually understood. It is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0052] The order in which the embodiments are described below is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0053] This application provides a method for preparing high-value combustible gas, including the following steps:

[0054] S1. Under negative pressure conditions, the straw is heated, dehydrated, and lightly carbonized using an electromagnetic induction heating device to obtain primary charcoal.

[0055] S2. After the primary carbon is extruded into shape, it is placed in a microwave pyrolysis device for pyrolysis to release pyrolysis gas and obtain secondary carbon.

[0056] S3. The pyrolysis gas is introduced into an electromagnetic induction heating device for deep pyrolysis and converted into combustible gas.

[0057] The method for preparing high-value combustible gas of the present invention combines electromagnetic induction heating and microwave heating technologies. Specifically, it includes three stages. In the first stage, after negative pressure electromagnetic induction heating, the slightly carbonized straw is squeezed into rods. In the second stage, microwave technology is used to pyrolyze the rod-shaped charcoal. Finally, in the third stage, the generated volatiles are subjected to electromagnetic induction high-temperature deep pyrolysis, thereby improving the calorific value and cleanliness of the combustible gas, while reducing tar formation. High-quality combustible gas is obtained based on multi-stage fine control.

[0058] Specifically, the straw is heated and dehydrated under negative pressure using an electromagnetic induction heating device. Due to the negative pressure environment, the efficiency of dehydration and volatile matter release can be effectively improved. The lightly carbonized char (primary char) obtained above is extruded into rods or other desired shapes in an extrusion device to obtain a more uniform internal temperature distribution during subsequent microwave heating. The forming process can be optimized and adjusted according to parameters such as the length and density of the rod char. After the primary char is extruded and formed, it is transported to a microwave pyrolysis device. The microwave device uniformly heats the charcoal within a set temperature range (e.g., 400℃~800℃), causing its internal temperature to rise rapidly and volatiles to be generated. This process yields secondary charcoal and pyrolysis gas containing tar, condensable organic matter, etc. The pyrolysis gas is then introduced into an electromagnetic induction heating device for deep pyrolysis at higher temperatures (e.g., 600℃~800℃), converting large-molecule tar or other organic components into small-molecule combustible gases (CO, H2, CH4, etc.). After cooling, dust removal, and necessary purification, the combustible gas produced after pyrolysis can be used for gas-fired power generation, industrial heating, or other gas-consuming systems.

[0059] The method for preparing high-value combustible gas of the present invention has the following advantages:

[0060] Segmented and refined control: The straw processing is divided into three main steps: electromagnetic induction dehydration and light carbonization, extrusion into rods followed by microwave pyrolysis, and electromagnetic induction deep pyrolysis. This allows for optimal control of the physical and chemical properties at different stages.

[0061] The molding process improves the pyrolysis effect: extruding the primary carbon before microwave heating is beneficial to the uniformity of heating in the microwave field and reduces local overheating or underheating.

[0062] High-efficiency heating mode: Combining electromagnetic induction and microwave heating to achieve rapid and uniform heating, avoiding the problem of low efficiency of traditional external heating;

[0063] Negative pressure operation: The first stage of negative pressure environment helps to quickly dehydrate and reduce oxygen content, enhance safety and reduce the generation of by-products;

[0064] High-quality combustible gas: The third-stage deep pyrolysis significantly reduces tar content and increases the proportion and calorific value of small molecular components in combustible gas.

[0065] In some embodiments, a magnetic induction heating device is used to heat the straw to 200-300°C and maintain it under a negative pressure environment of -0.005MPa to -0.08MPa for 10-50 minutes to heat, dehydrate, and lightly carbonize the straw, obtaining primary charcoal. The magnetic induction heating device has a power of 10-30kW, a frequency of 40-100kHz, and a current of 10-30A. Specifically, the crushed straw (particle size of about 5-10mm) is heated to 200-300°C under a negative pressure environment of -0.005MPa to -0.08MPa by turning on the electromagnetic induction coil. During this process, most of the moisture and some low-boiling-point organic components are removed, obtaining pre-carbonized charcoal (primary charcoal).

[0066] In some embodiments, primary char is fed into an extruder and subjected to appropriate pressure, such as 5–20 MPa, to be extruded into rods or blocks. The diameter of the rods or blocks can be in the range of 10–30 mm, and the length can be matched according to the size of the subsequent microwave device. The rod-shaped char is more easily heated uniformly in the microwave field. The extruded primary char is placed in a microwave pyrolysis device and pyrolyzed at 400–800°C for 2–10 min. The microwave power of the microwave pyrolysis device is 3–10 kW, and the microwave frequency is 2000–3000 MHz. Pyrolysis gas is released, and secondary char is obtained. During the microwave pyrolysis process, the moisture and tar components inside the char rapidly volatilize and are drawn out to the separation unit, forming secondary char and pyrolysis gas. The pyrolysis gas released in this stage contains tar droplets, light organic matter, etc., which need to be further cracked or purified in the third stage. Specifically, the pyrolysis gas contains condensable components (tar) and non-condensable components. The condensable components, after being collected by a condenser, become tar. The non-condensable components in the pyrolysis gas are introduced into an electromagnetic induction heating device for pyrolysis to obtain combustible gas. In some embodiments, the pyrolysis gas is introduced into the electromagnetic induction heating device and pyrolyzed at 600–800°C for 5–20 minutes, converting it into combustible gas. The pyrolysis gas and any tar components it may carry are introduced into the electromagnetic induction heating device and pyrolyzed at a high temperature of 600–800°C. At this high temperature, large organic molecules are further pyrolyzed to generate small-molecule combustible gas, the main components of which include CO, H2, CH4, etc. The combustible gas is then purified through cooling, dust removal, or deacidification to meet the quality requirements for direct use.

[0067] In some embodiments, the obtained combustible gas is further subjected to cooling, dust removal, and / or deacidification treatment.

[0068] In some embodiments, straw includes corn straw, wheat straw, rice straw, sorghum straw, etc.

[0069] This invention, through a three-stage process combined with an extrusion molding step, can produce combustible gas with high calorific value and low tar content, reaching 15–25 MJ / Nm³. 3Or even higher; compared with traditional single-stage pyrolysis or direct gasification, the process of this invention effectively improves gas production efficiency and reduces the generation of tar by-products.

[0070] Specifically, the calorific value of combustible gas refers to the calorific value per unit volume (usually in standard cubic meters, i.e., Nm³). 3 The heat released when a combustible gas is completely burned.

[0071] Based on the same inventive concept, the present invention also provides an apparatus for preparing high-value combustible gas for implementing the above-described method, comprising:

[0072] The negative pressure electromagnetic induction heating unit is used to heat and dehydrate straw under negative pressure conditions and lightly carbonize it to obtain primary char.

[0073] An extrusion molding unit is used to extrude primary carbon into shape;

[0074] The microwave pyrolysis unit is used to microwave pyrolyze the primary carbon after it has been extruded and shaped.

[0075] The electromagnetic induction deep pyrolysis unit is used to perform deep pyrolysis of the pyrolysis gas generated during microwave pyrolysis.

[0076] In some embodiments, the negative pressure electromagnetic induction heating unit includes:

[0077] The electromagnetic induction heating chamber 1 has a straw inlet 11 at one end and a primary char outlet 12 at the other end.

[0078] The first electromagnetic induction coil 13 is disposed on the electromagnetic induction heating cavity 1;

[0079] The first electromagnetic induction control unit 14 is disposed on the electromagnetic induction heating cavity 1 and is used to control the operation of the first electromagnetic induction coil 13.

[0080] The negative pressure pump 15 is located on the electromagnetic induction heating chamber 1 and is used to evacuate the electromagnetic induction heating chamber 1.

[0081] The extrusion molding unit 2 has a primary carbon feed inlet 21 and a molding outlet 22, with the primary carbon feed inlet 21 connected to the primary carbon outlet 12.

[0082] The microwave pyrolysis unit includes:

[0083] The microwave pyrolysis chamber 3 is provided with a pyrolysis feed inlet 31 and a pyrolysis gas outlet 32. The pyrolysis feed inlet 31 is connected to the forming outlet 22.

[0084] A microwave generator 33 is mounted on the microwave pyrolysis cavity 3;

[0085] The microwave control unit 37 is mounted on the microwave pyrolysis cavity 3 and is used to control the operation of the microwave generator 33.

[0086] The electromagnetic induction deep pyrolysis unit includes:

[0087] The electromagnetic induction deep pyrolysis chamber 4 is provided with a pyrolysis gas inlet 41, which is connected to the pyrolysis gas outlet 32.

[0088] The second electromagnetic induction coil 42 is disposed on the electromagnetic induction depth pyrolysis cavity 4.

[0089] The second electromagnetic induction control unit 43 is disposed on the electromagnetic induction depth pyrolysis cavity 4 and is used to control the operation of the second electromagnetic induction coil 42.

[0090] In some embodiments, a gas processing unit is further included, the gas processing unit comprising:

[0091] The gas purification system 5 has a combustible gas outlet 44 at the end of the electromagnetic induction deep pyrolysis chamber away from the pyrolysis gas inlet. The combustible gas outlet 44 is connected to the gas purification system 5 and is used to purify the combustible gas.

[0092] Gas collection tank 6 is connected to gas purification system 5.

[0093] In some embodiments, the electromagnetic induction depth splitting unit further includes:

[0094] The condenser 45 has its inlet end connected to the pyrolysis gas outlet 32;

[0095] The oil storage tank 46 has one end connected to the condenser outlet and the other end connected to the pyrolysis gas inlet 41.

[0096] Specifically, the working principle of the high-value combustible gas preparation device of the present invention is as follows: Straw raw material enters the electromagnetic induction heating chamber 1 through the straw inlet 11. A vacuum is created in the electromagnetic induction heating chamber 1 by a negative pressure pump 15 to form a negative pressure environment. The first electromagnetic induction control unit 14 controls the first electromagnetic induction coil 13 to operate, causing the electromagnetic induction heating chamber 1 to reach the set temperature. Under negative pressure conditions, the straw is dehydrated and lightly carbonized by electromagnetic induction heating to obtain primary char. The primary char enters the extrusion molding unit 2 through the primary char outlet 12 and the primary char inlet 21 for extrusion molding. The extruded primary char enters the microwave pyrolysis chamber 3 through the molding outlet 22 and the pyrolysis inlet 31. Inside, the microwave generator 33 is controlled by the microwave control unit 37 to reach the set temperature in the microwave pyrolysis chamber 3, and the primary carbon after extrusion is pyrolyzed by microwave. The pyrolysis gas generated by pyrolysis enters the condenser 45 through the pyrolysis gas outlet 32. A portion of the pyrolysis gas is condensed and stored in the oil storage tank 46, while the uncondensed pyrolysis gas enters the electromagnetic induction deep pyrolysis chamber 4 through the volatile matter inlet 41. The second electromagnetic induction control unit 43 controls the second electromagnetic induction coil 42 to reach the set temperature in the electromagnetic induction deep pyrolysis chamber 4, and the pyrolysis gas undergoes deep pyrolysis and is converted into combustible gas. The combustible gas enters the gas purification system 5 through the combustible gas outlet 44 for purification and is finally collected in the gas collection tank 6.

[0097] In some embodiments, the negative pressure electromagnetic induction heating unit further includes:

[0098] The spiral feed rod 16 is located inside the electromagnetic induction heating chamber 1;

[0099] The feeding motor 17 is mounted on the electromagnetic induction heating chamber. The feeding motor shaft is connected to the screw feed rod 16 to drive the screw feed rod to rotate.

[0100] In some embodiments, the extrusion molding unit is a hydraulic or mechanical extrusion device.

[0101] In the above embodiment, a screw feed rod 16 and a feed motor 17 are also provided to facilitate straw feeding. The feed motor rotates to drive the screw feed rod 16 to rotate, thereby realizing straw feeding.

[0102] In some embodiments, a stirrer 34 is also provided inside the microwave pyrolysis chamber 3. The stirrer 34 is connected to the shaft of the stirring motor 36 provided outside the microwave pyrolysis chamber 3. During the microwave pyrolysis process, the stirring motor 36 rotates to drive the stirrer 34 to rotate, thereby stirring the extruded primary carbon.

[0103] In some embodiments, the microwave pyrolysis chamber 3 is further provided with a secondary carbon outlet 35. The secondary carbon obtained after microwave pyrolysis is completed is discharged through the secondary carbon outlet 35, while the released pyrolysis gas enters the electromagnetic induction deep pyrolysis chamber 4 for high-temperature pyrolysis.

[0104] In some embodiments, the microwave pyrolysis cavity 3 is further provided with a microwave absorption device 38.

[0105] The following detailed embodiments further illustrate the method and apparatus for preparing high-value combustible gas according to this application. This section further explains the invention in conjunction with specific embodiments, but should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in the art.

[0106] Example 1

[0107] This embodiment provides a method for preparing high-value combustible gas, including the following steps:

[0108] S1. Crush rice straw to 3mm, then heat the straw to 300℃ using a magnetic induction heating device, and maintain it under a negative pressure environment of -20kPa for 20min to heat, dehydrate, and lightly carbonize the straw to obtain primary charcoal; wherein, the power of the magnetic induction heating device is 20kW, the frequency is 50kHz, and the current is 10A.

[0109] S2. The primary char is fed into an extruder and extruded into rods at 10 MPa. The rods of primary char have a diameter of 20 mm and a length of 80 ± 10 mm. The extruded primary char is placed in a microwave pyrolysis device and pyrolyzed at 500 °C for 5 min to release pyrolysis gas and obtain secondary char (i.e., biochar). The microwave power is 5 kW and the microwave frequency is 2450 MHz.

[0110] S3. The condensable components in the pyrolysis gas are collected by a condenser to obtain tar. The non-condensable components in the pyrolysis gas are introduced into an electromagnetic induction heating device and decomposed at 800℃ for 10 minutes to convert them into combustible gas.

[0111] Understandable, acceptable Figure 1 The apparatus shown is used to prepare high-value combustible gas according to the process parameters in Example 1.

[0112] Combustible gas was prepared according to the method in Example 1, wherein the biochar yield was 55%, the fixed carbon content in the biochar was 60%, and the calorific value of the combustible gas was 24 MJ / Nm³. 3 .

[0113] Comparative Example 1

[0114] This comparative example provides a method for preparing combustible gas, including the following steps:

[0115] S1. Crush rice straw to 3mm, then heat the straw to 300℃ using a magnetic induction heating device, and maintain it under a negative pressure environment of -20kPa for 20min to heat, dehydrate, and lightly carbonize the straw, obtaining primary char and some pyrolysis gas; wherein, the power of the magnetic induction heating device is 20kW, the frequency is 50kHz, and the current is 10A.

[0116] S2. Introduce some of the non-condensable components in the pyrolysis gas into an electromagnetic induction heating device, and decompose them at 800℃ for 10 minutes to convert them into combustible gas.

[0117] Following the method in Comparative Example 1, the yield of primary charcoal was 65%, the fixed carbon content in the primary charcoal was 35%, and the calorific value of the combustible gas was 15 MJ / Nm³. 3 .

[0118] Comparative Example 2

[0119] This comparative example provides a method for preparing combustible gas, including the following steps:

[0120] S1. Crush rice straw to 3mm, then heat the straw to 300℃ using a magnetic induction heating device, and maintain it under a negative pressure environment of -20kPa for 20min to heat, dehydrate, and lightly carbonize the straw to obtain primary charcoal; wherein, the power of the magnetic induction heating device is 20kW, the frequency is 50kHz, and the current is 10A.

[0121] S2. The primary char is fed into an extruder and extruded into rods at 10 MPa. The rods of primary char have a diameter of 20 mm and a length of 80 ± 10 mm. The extruded primary char is placed in a microwave pyrolysis device and pyrolyzed at 500°C for 5 min to release pyrolysis gas and obtain secondary char (i.e., biochar). The microwave power is 5 kW and the microwave frequency is 2450 MHz. The pyrolysis gas contains a condensable portion (tar) and a non-condensable portion (combustible gas). The combustible gas is obtained after the pyrolysis gas has been condensed (after cooling down and collecting the oil). The collected non-condensable gas is the combustible gas.

[0122] Following the method in Comparative Example 2, the biochar yield was 55%, the fixed carbon content in the biochar was 60%, and the calorific value of the combustible gas was 18 MJ / Nm³. 3 .

[0123] 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 should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-value combustible gas, characterized in that, Includes the following steps: S1. Under negative pressure conditions, the straw is heated, dehydrated, and lightly carbonized using an electromagnetic induction heating device to obtain primary charcoal. S2. After the primary carbon is extruded into shape, it is placed in a microwave pyrolysis device for pyrolysis to release pyrolysis gas and obtain secondary carbon. S3. The pyrolysis gas is introduced into an electromagnetic induction heating device for deep pyrolysis and converted into combustible gas. The straw is heated to 200~300℃ using an electromagnetic induction heating device and kept under a negative pressure environment of -0.005MPa~-0.08MPa for 10~50min to heat, dehydrate, and lightly carbonize the straw to obtain primary charcoal. The electromagnetic induction heating device has a power of 10~30 kW, a frequency of 40~100 kHz, and a current of 10~30A. The primary carbon is extruded into rods or blocks with a diameter of 10-30 mm, placed in a microwave pyrolysis device and pyrolyzed at 400-800°C for 2-10 min to release pyrolysis gas and obtain secondary carbon. The microwave power of the microwave pyrolysis device is 3~10 kW, and the microwave frequency is 2000~3000 MHz; The pyrolysis gas is introduced into an electromagnetic induction heating device and pyrolyzed at 600~800℃ for 5~20 minutes to convert it into combustible gas.

2. The method for preparing high-value combustible gas as described in claim 1, characterized in that, It also includes cooling, dust removal, and / or deacidification of the obtained combustible gas.

3. An apparatus for preparing high-value combustible gas for implementing the method of any one of claims 1 to 2, characterized in that, include: The negative pressure electromagnetic induction heating unit is used to heat and dehydrate straw under negative pressure conditions and lightly carbonize it to obtain primary char. An extrusion molding unit is used to extrude primary carbon into shape; The microwave pyrolysis unit is used to microwave pyrolyze the primary carbon after it has been extruded and shaped. Electromagnetic induction deep pyrolysis unit is used to deeply pyrolyze the pyrolysis gas generated during microwave pyrolysis. The negative pressure electromagnetic induction heating unit includes: The electromagnetic induction heating chamber has a straw inlet at one end and a primary charcoal outlet at the other end. A first electromagnetic induction coil is disposed on the electromagnetic induction heating cavity; The first electromagnetic induction control unit is disposed on the electromagnetic induction heating cavity and is used to control the operation of the first electromagnetic induction coil. A negative pressure pump, located on the electromagnetic induction heating chamber, is used to evacuate the electromagnetic induction heating chamber. The extrusion molding unit has a primary carbon feed inlet and a molding outlet, and the primary carbon feed inlet and the primary carbon outlet are connected. The microwave pyrolysis unit includes: A microwave pyrolysis chamber is provided with a pyrolysis inlet and a volatile matter outlet, wherein the pyrolysis inlet is connected to the forming outlet; A microwave generator is mounted on the microwave pyrolysis cavity; The microwave control unit, which is located on the microwave pyrolysis cavity, is used to control the operation of the microwave generator; The electromagnetic induction depth fragmentation unit includes: An electromagnetic induction deep pyrolysis chamber is provided with a pyrolysis gas inlet, which is connected to the volatile matter outlet. A second electromagnetic induction coil is disposed on the electromagnetic induction depth pyrolysis cavity; The second electromagnetic induction control unit is disposed on the electromagnetic induction depth pyrolysis cavity and is used to control the operation of the second electromagnetic induction coil.

4. The apparatus for preparing high-value combustible gas as described in claim 3, characterized in that, It also includes a gas processing unit, which comprises: The gas purification system has a combustible gas outlet at one end of the electromagnetic induction deep pyrolysis chamber away from the pyrolysis gas inlet. The combustible gas outlet is connected to the gas purification system for purifying the combustible gas. A gas collection tank, which is connected to the gas purification system.

5. The apparatus for preparing high-value combustible gas as described in claim 3, characterized in that, The electromagnetic induction depth fragmentation unit further includes: The condenser has its feed end connected to the volatile discharge port; An oil storage tank, one end of which is connected to the discharge end of the condenser and the other end of which is connected to the pyrolysis gas inlet.

6. The apparatus for preparing high-value combustible gas as described in claim 3, characterized in that, The negative pressure electromagnetic induction heating unit also includes: The screw feed rod is located inside the electromagnetic induction heating chamber; A feeding motor is mounted on the electromagnetic induction heating chamber, and the feeding motor shaft is connected to the screw feed rod to drive the screw feed rod to rotate. The microwave pyrolysis cavity is also equipped with a stirrer; The microwave pyrolysis chamber is also equipped with a secondary carbon discharge port.

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