Biomass charcoal fuel low-temperature baking method and device

Abstract

The invention provides a biomass charcoal fuel low-temperature baking method and device, and the method comprises the following steps: in an oxygen-free atmosphere or an oxygen volume content of less than 5%, under an air pressure of 0.01-0.1 MPa, a biomass raw material and a hot carrier gas are contacted from top to bottom in the same direction to carry out a segmented pyrolytic reaction so as to obtain a pyrolytic gas and a biomass charcoal fuel; the temperature of the segmented pyrolysis reaction is 240 to 300 DEG C. The method is uniform in reaction temperature and easy to control, and the produced biomass briquette fuel is high in energy density and high in energy utilization rate. In addition, pyrolysis tail gas is low in tar and ash content, long-time stable operation can be achieved, and the carbon yield is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass charcoal fuel preparation, and in particular relates to a method and device for low-temperature baking of biomass charcoal fuel. Background Art

[0002] Processing straw into molded fuel can increase the density of straw, facilitate transportation, storage and application, and solve the bottleneck of large-scale application of biomass. It also improves the combustion performance of straw and promotes the energy utilization of straw.

[0003] Biomass carbonization technology involves heating biomass materials to a certain temperature, causing them to undergo a pyrolysis reaction to produce biochar and other byproducts. Current biomass carbonization technology faces a series of challenges, including difficulty controlling the carbonization process, discontinuous production, waste of residual carbonized products, and low charcoal yields, which urgently require improvement.

[0004] CN102703099A discloses a vertical moving bed rice husk carbonization furnace and a method for carbonizing rice husks. The carbonization furnace includes a particle system, a fuel gas system, an operating gas system, and a control system, forming a vertical moving bed in which the rice husks fall. The operating gas system is a working unit that generates the operating gas, and the rice husks undergo countercurrent heat exchange with the operating gas within the vertical moving bed. This method achieves temperature-controlled continuous carbonization of rice husks on a production scale, but the carbonization temperature is too high, resulting in the resulting products of activated carbonized rice husks, light wood tar, and combustible gas. The activated carbon material has a low energy density and energy yield, making it unusable as a fuel.

[0005] CN110079337A discloses a low-temperature baking vertical moving bed carbonization process and a method for carbonizing corn straw. However, it uses an upper gas outlet vertical furnace, which leads to high requirements on the size of the raw materials. At the same time, the high content of tar and dust in the reaction tail gas is very easy to clog the pipeline, resulting in the system being unable to operate stably for a long time; secondly, the tar from the reaction pyrolysis in the upper gas outlet vertical furnace cannot be fully adsorbed on the biomass and the carbon layer, thereby resulting in a decrease in energy yield; thirdly, the upper gas outlet reactor is prone to channeling, resulting in uneven heating of the material in the reactor. Summary of the Invention

[0006] In view of this, an object of the present invention is to provide a method for low-temperature baking of biomass charcoal fuel, wherein the biomass charcoal fuel prepared by the method has high energy density and high energy utilization rate.

[0007] The present invention provides a method for low-temperature baking of biomass charcoal fuel, comprising the following steps:

[0008] In an atmosphere without oxygen or with an oxygen volume content of less than 5% and a pressure of 0.01 to 0.1 MPa, the biomass raw material and the hot carrier gas are contacted from top to bottom in the same direction to perform a staged pyrolysis reaction to obtain pyrolysis gas and biomass charcoal fuel;

[0009] The temperature of the staged pyrolysis reaction is 240-300°C.

[0010] Preferably, the bulk density of the biomass raw material is 0.25-1.0 g / cm 3 , moisture content <20%, particle size <150mm.

[0011] Preferably, the volume ratio of the biomass raw material to the hot carrier gas entering the reaction system per unit time is (1:2000) to (1:6000).

[0012] Preferably, the staged pyrolysis reaction time is 1 to 6 hours.

[0013] Preferably, the main components of the hot carrier gas include N2 and CO2, the volume ratio of N2 to CO2 is (2:3) to (3:3), and the volume content of oxygen is <5%.

[0014] Preferably, the biomass raw material is selected from one or more of waste corn stalks, waste cotton stalks and waste wood chips.

[0015] Preferably, the staged pyrolysis reaction is carried out in a biomass continuous staged pyrolysis furnace;

[0016] The biomass continuous segmented pyrolysis furnace includes a drying section, a pyrolysis and volatilization section, a constant temperature pyrolysis section and a cooling section;

[0017] The temperature of the drying section is 105-115°C, the temperature of the pyrolysis and volatilization section is 210-230°C, the temperature of the constant temperature pyrolysis section is 240-300°C, and the temperature of the cooling section is 55-65°C.

[0018] The present invention provides a low-temperature baking device for biomass charcoal fuel, comprising a feeding unit, a biomass continuous segmented pyrolysis furnace, a separation unit, a cooling unit, a graded temperature control unit and an exhaust gas circulation unit;

[0019] The feeding unit comprises a feeding auger (1), a receiving hopper (2) and a feeding hopper (3);

[0020] The biomass continuous segmented pyrolysis furnace (4) is a continuous graded temperature-controlled biomass low-temperature baking furnace; the biomass raw material and the hot carrier gas contact from top to bottom in the same direction to carry out segmented pyrolysis reaction in the segmented pyrolysis furnace.

[0021] Preferably, the hierarchical temperature control unit includes a high-temperature catalytic oxidation reactor (13) and a low-temperature catalytic oxidation reactor (14);

[0022] The temperature difference between the hot carrier gas in the high-temperature catalytic oxidation reactor (13) and the low-temperature catalytic oxidation reactor (14) is 50 to 200° C.; and the flow ratio of the high-temperature hot carrier gas to the low-temperature hot carrier gas is 0.5 to 4:1.

[0023] Preferably, it further comprises a biomass charcoal cooling and storage chamber (5), a spiral discharge cooler (6) and a product storage chamber (7) connected in sequence to the staged pyrolysis furnace (5);

[0024] The discharge amount is adjusted by adjusting the frequency of the spiral discharge cooler (6), thereby controlling the reaction time.

[0025] The present invention provides a method for low-temperature baking of biomass charcoal fuel, comprising the following steps: in an atmosphere without oxygen or with an oxygen volume content of less than 5% and an air pressure of 0.01 to 0.1 MPa, the biomass raw material and the hot carrier gas are contacted in the same direction from top to bottom to carry out a segmented pyrolysis reaction to obtain pyrolysis gas and biomass charcoal fuel; the temperature of the segmented pyrolysis reaction is 240 to 300°C. The reaction temperature of this method is uniform and easy to control, and the biomass molded fuel produced by it has high energy density and high energy utilization rate. In addition, the pyrolysis tail gas has low tar and ash content, can operate stably for a long time, and has a high charcoal yield. The experimental results show that under the same experimental conditions, the tail gas particles are 703mg / m 3 Reduced to 215 mg / m 3 ; The mass yield is 70.02~77.7%; the energy yield is 83.12~92.18%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the process flow of the device for preparing biochar fuel according to the present invention; wherein, (1) is a feed auger, (2) is a receiving hopper, (3) is a feed hopper, (4) is a biomass continuous staged pyrolysis furnace, (5) is a biochar cooling storage chamber, (6) is a spiral discharge cooler, (7) is a product storage chamber, (8) is a cyclone dust collector, (9) is a water cooling unit, (10) is an exhaust gas filter, (11) is a constant pressure valve, (12 ) is a circulating compressor, (13) is a high-temperature catalytic oxidizer, (14) is a low-temperature catalytic oxidizer, (1-1) is a raw material plug-in valve, (2-1) is a receiving hopper cyclone, (2-2) is an intermediate plug-in valve, (3-1) is a feed plug-in valve, (3-2) is a feed air shut-off valve, (9-1) is a primary water cooling, (9-2) is a secondary water cooling, (9-3) is a primary condensation storage tank, and (9-4) is a secondary condensation storage tank;

[0027] Figure 2 Schematic diagram of the overall structure of the biomass continuous staged pyrolysis furnace used in the embodiment of the present invention; 300, reaction furnace body; 301, first stage reaction furnace body; 302, second stage reaction furnace body;

[0028] Figure 3Schematic diagram of the structure of the reaction furnace body used in the embodiment of the present invention; wherein, 3021, inner cylinder; 3022, outer cylinder; 3023, gas channel; 303, first hot carrier gas inlet mechanism; 3031, first hot carrier gas inlet pipe; 3032, first level guide cone; 304, second hot carrier gas inlet mechanism; 3041, second hot carrier gas inlet pipe; 3042, second level guide cone; 305, third hot carrier gas inlet mechanism; 306, thermocouple; 3061, first Thermocouple; 3062, second thermocouple; 3063, third thermocouple; 3064, fourth thermocouple; 3065, fifth thermocouple; 3066, sixth thermocouple; 3067, seventh thermocouple; 307, air lock; 308, ventilation furnace wall; 3081, first screen; 3082, second screen; 3083, reinforcing rib plate; 3083a, through hole; 309, pyrolysis gas outlet; 310, material level meter; 311, flange; 312, arch breaker;

[0029] Figure 4 A schematic structural diagram of the arch-breaking plate used in an embodiment of the present invention;

[0030] Figure 5 A schematic structural diagram of a first hot carrier gas inlet mechanism used in an embodiment of the present invention;

[0031] Figure 6 A schematic structural diagram of a second hot carrier gas inlet mechanism used in an embodiment of the present invention;

[0032] Figure 7 A schematic structural diagram of a third hot carrier gas inlet mechanism employed in an embodiment of the present invention;

[0033] Figure 8 This is a schematic structural diagram of the ventilation furnace wall used in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The present invention provides a method for low-temperature baking of biomass charcoal fuel, comprising the following steps:

[0035] In an atmosphere without oxygen or with an oxygen volume content of less than 5% and a pressure of 0.01 to 0.1 MPa, the biomass raw material and the hot carrier gas are contacted from top to bottom in the same direction to perform a staged pyrolysis reaction to obtain pyrolysis gas and biomass charcoal fuel;

[0036] The temperature of the staged pyrolysis reaction is 240-300°C.

[0037] In the present invention, the biomass raw material is selected from one or more of waste corn stalks, waste cotton stalks and waste wood chips. The bulk density of the biomass raw material in the present invention is 0.25-1.0 g / cm 3 , moisture content <20%, particle size <150mm.

[0038] The hot carrier gas in the present invention mainly includes N2 and CO2, and the volume content of oxygen is less than 5%. The hot carrier gas is the reaction pyrolysis tail gas after being dusted and de-liquidated by a separation unit (including a cyclone dust collector (8), a water cooling unit (9) and a tail gas filter (10)), and then heated and pressurized. The separation unit in the present invention includes a cyclone dust collector (8), that is, the hot carrier gas is the reaction pyrolysis tail gas after being dusted and de-liquidated by a cyclone dust collector (8), a water cooling unit (9) and a tail gas filter (10), and then passing through a high-temperature oxidation reactor (13) and a low-temperature oxidation reactor (14), oxidizing methane and CO2 in the reaction pyrolysis gas and then releasing heat and increasing the temperature (that is, the tail gas after biomass pyrolysis is burned and releases heat), and then passing through a circulation compressor (12) to increase the pressure of the reaction pyrolysis tail gas.

[0039] In the present invention, the staged pyrolysis reaction is carried out in a staged pyrolysis furnace; the temperature of different stages is achieved by gas flow at different temperatures. The staged pyrolysis furnace includes a drying section, a pyrolysis volatilization section, a constant temperature pyrolysis section and a cooling section; the temperature of the drying section is 105-115°C, specifically 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, 114°C or 115°C; the temperature of the pyrolysis volatilization section is 210-230°C, specifically 210°C, 212°C, 214°C, 216°C, 218°C, 220°C, 222°C, 224°C, 226°C, 228°C or 230°C; the temperature of the constant temperature pyrolysis section is 240-300°C , specifically it can be 240℃, 242℃, 244℃, 246℃, 248℃, 250℃, 252℃, 254℃, 256℃, 258℃, 260℃, 262℃, 264℃, 266℃, 268℃, 270℃, 272℃, 274℃, 276℃, 278℃, 280℃, 282℃, 284℃, 286℃, 288℃, 290℃, 292℃, 294℃, 296℃, 298℃ or 300℃; the temperature of the cooling section is 55-65℃, specifically it can be 55℃, 56℃, 57℃, 58℃, 59℃ or 60℃.

[0040] The present invention adjusts the discharge amount by adjusting the frequency of the spiral discharge cooler (6), thereby controlling the reaction time; the time of the staged pyrolysis reaction is 1 to 6 hours, specifically 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4.0 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours.

[0041] The present invention provides a low-temperature baking device for biomass charcoal fuel, comprising a feeding unit, a segmented pyrolysis furnace, a separation unit, a cooling unit, a graded temperature control unit and an exhaust gas circulation unit.

[0042] Figure 1This is a schematic diagram of the process of the device for preparing biomass charcoal fuel according to the present invention;

[0043] The feeding unit of the present invention comprises a feeding auger (1), a receiving hopper (2) and a feeding hopper (3);

[0044] The feeding auger (1), receiving hopper (2), feeding hopper (3), (4) biomass continuous segmented pyrolysis furnace, (5) biochar cooling storage chamber and (6) spiral discharge cooler in the present invention form a continuous graded temperature-controlled biomass low-temperature baking furnace, wherein the biomass continuous segmented pyrolysis furnace (4) is the main body of the continuous graded temperature-controlled biomass low-temperature baking furnace; the biomass raw material and the hot carrier gas contact in the same direction from top to bottom to carry out segmented pyrolysis reaction in the biomass continuous segmented pyrolysis furnace (4).

[0045] The feeding unit in the present invention comprises a feeding auger (1), a receiving hopper (2) and a feeding hopper (3); a raw material plug valve (1-1) is provided between the feeding auger (1) and the receiving hopper (2); an intermediate plug valve (2-2) is provided between the receiving hopper (2) and the feeding hopper (3); a feeding plug valve (3-1) and an air shut-off device (3-2) are provided between the feeding hopper (3) and the segmented pyrolysis furnace; the feeding hopper (3) is provided with a pressure balancing pipeline connected to the gas phase outlet pipeline of the cyclone dust collector (8), and part of the high-temperature pyrolysis gas after separation and dust removal enters the feeding hopper (3) to preheat the raw material and filter part of the tar at the same time.

[0046] The biomass continuous segmented pyrolysis furnace (4) is a main body of a continuous graded temperature-controlled biomass low-temperature baking furnace; the reaction bed height of the biomass continuous segmented pyrolysis furnace (4) is adjusted by adjusting the frequency of the air lock (3-2), and the material level filling height is 2 / 3 of the total furnace height.

[0047] In the present invention, the hierarchical temperature control unit includes a high-temperature catalytic oxidation reactor (13) and a low-temperature catalytic oxidation reactor (14) and corresponding mixing pipelines and control valves; the reaction pyrolysis tail gas enters the high / low temperature oxidation reactors respectively to be heated to generate two hot carrier gases at different temperatures; the temperature difference between the high-temperature hot carrier gas and the low-temperature hot carrier gas is 50 to 200°C, and the flow ratio of the high-temperature hot carrier gas to the low-temperature hot carrier gas is 0.5 to 4. The present invention configures hot carrier gases of different temperatures by adjusting the flow rate and temperature difference of the high and low temperature pyrolysis gases, and enters the baking furnace through different hot carrier gas inlet pipes.

[0048] The device provided by the present invention also includes a biomass charcoal cooling storage chamber (5), a spiral discharge cooler (6) and a product storage chamber (7) connected in sequence to the staged pyrolysis furnace (5); the discharge amount is adjusted by adjusting the frequency of the spiral discharge cooler (6), thereby controlling the reaction time.

[0049] The device provided by the present invention further comprises a water cooling unit (9) connected to the cyclone separator (8) via a pipeline, wherein the water cooling unit (9) comprises a primary water cooling unit (9-1) and a secondary water cooling unit (9-2); a primary condensation storage tank (9-3) connected to the primary water cooling unit (9-1), and a secondary condensation storage tank (9-4) connected to the secondary water cooling unit.

[0050] The device provided by the present invention also includes an exhaust filter (10) connected to the water cooling unit (9). The liquid phase material after cooling and separation by the water cooling system (9) enters the liquid phase material storage tank (9-3 and 9-4), and the pyrolysis gas enters the exhaust filter (10) for filtration. After filtration, a small amount of pyrolysis gas is burned and then discharged to maintain the system pressure. A large amount of pyrolysis gas is respectively sent into the high-temperature catalytic oxidation reactor (13) and the low-temperature catalytic oxidation reactor (14) as hot carrier gas for oxidation and heating. The heated hot carrier gas is configured with hot carrier gas of different temperatures by adjusting the flow rate and temperature difference, and is sent into the baking furnace through different hot carrier gas inlet pipes to circulate heat for the reaction system.

[0051] The device provided by the present invention also includes a constant pressure valve (11) connected to the tail gas filter (10). A small amount of pyrolysis gas is released through the constant pressure valve (11) to maintain the system pressure stable; the remaining pyrolysis gas enters the circulation compressor (12) for pressure boosting, and the pressurized pyrolysis gas is transported to the high catalytic oxidation reactor (13) and the low-temperature catalytic oxidation reactor (14) through pipelines.

[0052] The method for low-temperature baking of biomass charcoal fuel in the present invention specifically comprises: the biomass raw material is lifted to the top of the low-temperature baking furnace by a feed hoist, and is added to the receiving hopper (2) through a feed auger (1), the raw material plug valve (1-1) is closed, and the hot carrier gas from the low-temperature catalytic oxidation reactor (14) is used to pressurize the receiving hopper. After the pressure of the receiving hopper reaches the system pressure, the middle plug valve (2-2) is opened, and the material enters the feed hopper (3) under the action of gravity. After the feeding is completed, the middle plug valve (2-2) is closed. The intermediate plug valve (2-2) is opened, and the receiving hopper (2) is relieved to normal pressure through the receiving hopper pressure relief pipeline. The raw material plug valve (1-1) is opened to start the feeding auger (1) to fill the hopper for standby use. The raw materials entering the feeding hopper (3) are fully contacted with the pyrolysis gas after the cyclone dust removal (8) for heat exchange, and part of the tar is filtered and adsorbed. The raw materials after heat exchange are sent to the segmented pyrolysis furnace (4) at a set flow rate through the air lock (3-2). The material level of the segmented pyrolysis furnace (4) is measured by the radar level meter on the furnace top. The frequency of the air lock is adjusted to control the material level filling height to 2 / 3 of the total height of the furnace body. After the material completes the pyrolysis reaction in the segmented pyrolysis furnace (4), the solid product is cooled in the biochar cooling storage chamber (5) and then sent to the product storage chamber (7) through the spiral discharge cooler (6); after the reaction pyrolysis gas passes through the cyclone separator (8), a part of it directly enters the water cooling system (9) for condensation and cooling, and the other part is sent to the feed hopper (3) for heat exchange with the raw material and then enters the water cooling system (9). After the water cooling system (9) The liquid phase material after cooling and separation enters the liquid phase material storage tank (9-3 and 9-4), and the pyrolysis gas enters the tail gas filter (10) for filtration. After filtration, the pyrolysis gas is burned in small quantities and then discharged to maintain the system pressure. A large amount of pyrolysis gas is sent as hot carrier gas to high and low temperature catalytic oxidation reactors (13 / 14) for oxidation and heating. The heated hot carrier gas is configured with hot carrier gas of different temperatures by adjusting the flow rate and temperature difference, and is sent to the baking furnace through different hot carrier gas inlet pipes to circulate heat for the reaction system.

[0053] The method provided by the present invention adopts a device that detects the material level height according to a radar level meter inside a biomass continuous segmented pyrolysis furnace (4). Once the detected material level is insufficient, the air lock (3-2) of the feed hopper (3) is adjusted through a PLC automatic control system, and raw materials are quantitatively fed into the furnace. The pressure of the feed hopper (3) is maintained by the reaction pyrolysis tail gas from the cyclone dust collector (8); when the material level of the feed hopper (3) is low, the receiving hopper (2) starts to pressurize. After the pressure is completed, the middle plug valve (2-2) is opened, and the raw materials enter the feed hopper (3) from the receiving hopper (2); when the feed hopper (3) completes feeding, the middle plug valve (2-2) is closed, and the receiving hopper (2) starts to release pressure. After the pressure release is completed, the raw material plug valve (1-1) is opened, and the raw materials are added to the receiving hopper for standby use; at the same time, an air lock is installed at the bottom of the biomass continuous segmented pyrolysis furnace (4) to maintain the stable discharge of the system, and the discharge speed can be controlled by adjusting the speed of the air lock. The automatic feeding and discharging are controlled by the PLC automatic control system to achieve the continuity of equipment operation.

[0054] In the device used in the method provided by the present invention, a circulating gas heater is provided in front of the catalytic oxidation reactor. After the reaction pyrolysis gas and the combustion-supporting gas (air) are mixed and heated to a suitable reaction temperature of 120-200°C by the circulating gas heater, they enter the catalytic oxidation reactor for oxidation and are heated to 240-350°C, thereby significantly reducing the energy consumption of the system. The amount of combustion-supporting gas (air) added is automatically controlled according to the flow signal of the pyrolysis gas to ensure the normal progress of the oxidation reaction.

[0055] The pressure of the device used in the method provided by the present invention is automatically controlled by a PLC automatic control system, and a portion of tail gas is discharged in order to maintain the stability of the furnace pressure.

[0056] During the operation of the device used in this process, the biomass molded fuel generated by the reaction is output from the bottom of the low-temperature baking furnace, and the hot carrier gas and the pyrolysis gas generated by the reaction penetrate through the reaction bed and are discharged from the bottom of the furnace. During this process, the hot carrier gas and the pyrolysis gas generated by the reaction are filtered and purified through the carbonization layer, reducing the dust and tar content in the pyrolysis gas. Therefore, the system separation process load is greatly reduced, and the process stability is greatly improved.

[0057] The reaction pyrolysis tail gas of the device is subjected to dust removal, condensation, and purification, and then enters the catalytic oxidation reactor for oxidation reaction to generate a hot air flow as a reaction hot carrier gas to provide heat for the reaction cycle. The condensation is carried out using cooling water, and the temperature of the gas before condensation is 180-105°C, and the temperature of the gas after condensation is 40-50°C. The main component of the product obtained by condensation is wood vinegar. The reaction pyrolysis tail gas is subjected to dust removal, condensation, and purification, and then undergoes an oxidation reaction to generate a hot air flow as a heat source for the carbonization furnace, thereby realizing energy recycling. The dust removal described here is carried out using a cyclone dust collector to remove solid impurities such as carbon particles and dust carried by the combustible gas, reduce the content of solid impurities in the gas entering the condenser, avoid scaling inside the condenser, reduce the content of solid impurities in the condensed liquid, and improve the quality of the condensed product.

[0058] At the start of the reaction, the device uses N2 as a hot carrier gas and begins to purge and replace the reaction system with N2 to ensure that the low-temperature baking furnace is an oxygen-free or low-oxygen environment. The biomass raw material level is then added to 2 / 3 of the height of the segmented pyrolysis furnace body. The auxiliary heating system is initially used to heat the hot carrier gas as a starting heat source to provide heat for the reaction. The hot carrier gas is fed into the segmented pyrolysis furnace from each segment of the hot carrier gas inlet pipe. By adjusting the temperature and flow of each segment of the hot carrier gas, a pyrolysis temperature field that matches the raw material is established. After the temperature field is established, the spiral discharging system is turned on, and the segmented pyrolysis furnace level control system is put into use to maintain a stable bed height. The hot carrier gas inlet flow and temperature of each segment are coordinated to maintain a stable pyrolysis temperature field. The biomass raw material passes through each set temperature field in turn during its movement from top to bottom in the furnace, thereby generating biomass briquette fuel at the bottom of the furnace and outputting it from the bottom of the furnace to achieve the preparation of biomass briquette fuel. During the preparation process, the raw material particles are in direct contact with the hot air flow, which has high heat utilization efficiency; the carbonization temperature is low, which reduces the production of tar; the mass yield of the obtained biomass charcoal fuel is >70%, and the energy yield is >85%, with high energy yield; the obtained biomass charcoal has a high energy density and can be used as fuel, which expands the use of the product and provides a new way for the recycling of waste biomass.

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Please refer to Figures 2 to 8 .

[0060] As one example, please refer to Figure 2The feeding mechanism disclosed in the embodiment of the present invention includes a feeding hopper and a feeding auger. The outlet of the feeding hopper is connected to the inlet of the feeding auger, and the outlet of the feeding auger is connected to the inlet of the reaction furnace body 300.

[0061] As a further example, please refer to Figure 2 The reactor body 300 of the staged pyrolysis furnace used in the embodiment of the present invention includes at least a first-stage reactor body 301 and a second-stage reactor body 302 that are connected to each other, wherein the first-stage reactor body 301 and the second-stage reactor body 302 are arranged in sequence along the vertical direction, the first-stage reactor body 301 is connected to the feeding mechanism, and the second-stage reactor body 302 is connected to the discharging mechanism.

[0062] The first stage reaction furnace body 301 and the second stage reaction furnace body 302 are both provided with at least one hot carrier gas inlet mechanism. In this way, heating by the hot carrier gas mechanism can make different temperature fields at different height stages of the reaction furnace.

[0063] As a specific embodiment, the hot carrier gas intake mechanism disclosed in the embodiment of the present invention includes a first hot carrier gas intake mechanism 303, a second hot carrier gas intake mechanism 304 and a third hot carrier gas intake mechanism 305, wherein the first hot carrier gas intake mechanism 303 is arranged in the first stage reaction furnace body 301, the second hot carrier gas intake mechanism 304 and the third hot carrier gas intake mechanism 305 are both arranged in the second stage reaction furnace body 302, and the third hot carrier gas intake mechanism is arranged at the lower part of the second hot carrier gas intake mechanism 304.

[0064] Different temperature fields can be established by the first hot carrier gas inlet mechanism 303 , the second hot carrier gas inlet mechanism 304 and the third hot carrier gas inlet mechanism 305 .

[0065] The embodiment of the present invention does not limit the specific structure of the first hot carrier gas inlet mechanism 303. As long as the use requirements of the present invention are met, it is within the protection scope of the present invention.

[0066] As one example, please refer to Figure 5 The first hot carrier gas inlet mechanism 303 disclosed in the embodiment of the present invention includes a first hot carrier gas inlet pipe 3031 and a first-level guide cone 3032. The first hot carrier gas inlet pipe 3031 includes a first inlet end and a first outlet end. The first inlet end extends into the interior of a first-stage reaction furnace body 301, and the first outlet end is placed outside the first-stage reaction furnace body 301.

[0067] The first gas outlet is provided with a first-stage guide cone 3032, and the gas outlet of the first-stage guide cone 3032 is arranged toward the feed auger (1). In this arrangement, the hot carrier gas entering from the first hot carrier gas inlet pipe 3031 is ejected upward.

[0068] As a further example, the outlet of the primary guide cone 3032 disclosed in the embodiment of the present invention is arranged on the central axis of the reactor body 300, wherein the cone angle of the primary guide cone 3032 is 30°-45°. This arrangement allows the airflow to be ejected from the central axis of the reactor body 300, reducing the unevenness of the flow field distribution within the furnace. The setting of the cone angle can also make the impact force of the airflow on the cone surface more evenly distributed, further reducing the risk of damage to the cone surface due to excessive local stress.

[0069] The embodiment of the present invention does not limit the specific structure of the second hot carrier gas inlet mechanism 304. As long as the structure meets the use requirements of the present invention, it falls within the protection scope of the present invention.

[0070] As one example, please refer to Figure 6 The second hot carrier gas inlet mechanism 304 disclosed in the embodiment of the present invention includes a second hot carrier gas inlet pipe 3041 and a secondary guide cone 3042. The second hot carrier gas inlet pipe 3041 includes a second inlet end and a second outlet end. The second inlet end extends into the interior of the second-stage reaction furnace body 302, and the second outlet end is placed outside the second-stage reaction furnace body 302.

[0071] The second air outlet end is provided with a secondary guide cone 3042, and the air outlet of the secondary guide cone 3042 is arranged toward the feed auger (1).

[0072] As a further embodiment, the air outlet of the secondary guide cone 3042 disclosed in the embodiment of the present invention is arranged on the central axis of the reactor body 300. With this arrangement, the air flow is ejected from the central axis of the reactor body 300, which can reduce the unevenness of the flow field distribution in the furnace.

[0073] As a further embodiment, the cone angle of the secondary guide cone 3042 disclosed in the embodiment of the present invention is 30°-45°. This configuration can make the impact force of the airflow on the cone surface more evenly distributed, further reducing the risk of damage to the cone surface due to excessive local stress.

[0074] The embodiment of the present invention does not limit the specific structure of the third hot carrier gas inlet mechanism 305. As long as the structure meets the use requirements of the present invention, it is within the protection scope of the present invention.

[0075] As one example, please refer to Figure 7The third hot carrier gas inlet mechanism 305 disclosed in the embodiment of the present invention is a third hot carrier gas inlet pipe, which includes a third inlet end and a third outlet end. The third inlet end extends into the interior of the second-stage reactor body 302, and the third outlet end is placed outside the second-stage reactor body 302. The outlet of the third outlet end is arranged on the central axis of the reactor body 300, and the outlet of the third outlet end is arranged toward the discharge mechanism. With such an arrangement, the downward directional force of the airflow can directly push the biomass molded fuel in the second-stage reactor body 302 to move toward the discharge mechanism. Since the biomass molded fuel may change in density and decrease in fluidity after the reaction, it is easy to accumulate before discharge, and the directional thrust of the hot carrier gas can ensure that the material enters the discharge mechanism continuously and smoothly.

[0076] There is a preset distance between the third hot carrier gas inlet pipe and the second hot carrier gas inlet pipe 3041 in the height direction of the reaction furnace body 300 .

[0077] As a further embodiment, the biomass continuous segmented baking furnace disclosed in the embodiment of the present invention also includes multiple thermocouples 306, which are arranged on the furnace wall of the reactor body 300 along the height direction of the reactor body 300, wherein the detection end of the thermocouple 306 is placed inside the reactor body 300.

[0078] The thermocouple 306 is arranged opposite to the hot carrier gas inlet mechanism.

[0079] As a specific embodiment, the thermocouple 306 disclosed in the embodiment of the present invention includes a first thermocouple 3061, a second thermocouple 3062, a third thermocouple 3063, a fourth thermocouple 3064, a fifth thermocouple 3065, a sixth thermocouple 3066 and a seventh thermocouple 3067, wherein the first thermocouple 3061 and the second thermocouple 3062 are arranged on a section of the reaction furnace body 301, the height of the first thermocouple 3061 is higher than the first hot carrier gas inlet pipe 3031, and the height of the second thermocouple 3062 is lower than the first hot carrier gas inlet pipe 3031. Such an arrangement can monitor the temperature at different heights of a section of the reaction furnace body 301.

[0080] The third thermocouple 3063, the fourth thermocouple 3064, the fifth thermocouple 3065, the sixth thermocouple 3066, and the seventh thermocouple 3067 are all disposed on the second-stage reactor body 302 and are sequentially arranged along the height of the second-stage reactor body 302. This arrangement allows the temperature at different heights of the second-stage reactor body 302 to be monitored.

[0081] The monitoring point of thermocouple 306 directly faces the area where the hot carrier gas is applied. This structure more accurately captures the impact of the hot carrier gas entering the furnace on the local temperature, providing a more effective basis for hot carrier gas control. For example, if the first thermocouple 3061 detects a temperature anomaly, the inlet status of the first hot carrier gas inlet pipe 3031 (such as excessively high / low hot carrier temperature or unstable flow) can be directly pinpointed, eliminating the need to investigate unrelated areas and shortening debugging and troubleshooting time.

[0082] The embodiment of the present invention does not limit the specific structures of the first-stage reaction furnace body 301 and the second-stage reaction furnace body 302. As long as the structures meet the use requirements of the present invention, they are within the protection scope of the present invention.

[0083] As one of the examples, please refer to Figure 3 The first-stage reactor body 301 disclosed in the embodiment of the present invention is a single-tube structure, while the second-stage reactor body 302 comprises an inner tube 3021 and an outer tube 3022. The outer tube 3022 is sleeved onto the inner tube 3021, with a gas channel 3023 provided between the inner tube 3021 and the outer tube 3022. This arrangement allows the pyrolysis gas channel to completely enclose the second-stage reactor body 302, forming a pyrolysis gas insulation layer.

[0084] As a further embodiment, the reactor body 300 disclosed in the embodiment of the present invention further includes a ventilation furnace wall 308 , wherein the ventilation furnace wall 308 is disposed in the second-stage reactor body 302 , and the ventilation furnace wall 308 is communicated with the gas channel 3023 .

[0085] The outer cylinder 3022 is further provided with a pyrolysis gas outlet 309 , which is communicated with the gas channel 3023 .

[0086] With this arrangement, the pyrolysis gas can enter the gas channel 3023 through the ventilation furnace wall 308 and be discharged through the pyrolysis gas outlet 309.

[0087] As a specific example, please refer to Figure 8 The ventilation furnace wall 308 disclosed in the embodiment of the present invention includes a first screen 3081, a reinforcing rib plate 3083, and a second screen 3082. The reinforcing rib plate 3083 is disposed between the first screen 3081 and the second screen 3082, and the first screen 3081, the reinforcing rib plate 3083, and the second screen 3082 are bonded together. The reinforcing rib plate has a plurality of through holes 3083a formed therein to communicate with the first screen 3081 and the second screen 3082.

[0088] It should be noted that the first-stage reaction furnace body 301 and the second-stage reaction furnace body 302 are connected via a flange 311 . This arrangement can effectively improve the connection strength of the entire reaction furnace body 300 .

[0089] The distance from the flange 311 to the second hot carrier gas inlet pipe 3041 is 1 / 4 of the distance from the first flange 311 to the ventilation furnace wall 308, and the distance from the flange 311 to the third hot carrier gas inlet pipe 305 is 1 / 2 of the distance from the first flange 311 to the ventilation furnace wall 308. This arrangement can form different temperature fields.

[0090] As a further example, please refer to Figure 4 , the embodiment of the present invention discloses a biomass continuous staged pyrolysis furnace, the second stage reaction furnace body 302 is further provided with a broken arch plate 312, the broken arch plate 312 is staggered on the inner wall of the second stage reaction furnace body 302.

[0091] The included angle between the arch-breaking plate 312 and the central axis of the reaction furnace body 300 is 30°-45°.

[0092] Because biomass raw materials (such as straw, wood chips, etc.) are prone to form "bridges" (materials support each other to form a suspended structure, with voids appearing below) or local accumulation in the furnace body due to their own shape (fibrous, irregular particles), humidity or mutual adsorption force during the falling or moving process, resulting in interruption of material transportation and discontinuous reaction.

[0093] The staggered arch-breaking plates can break the stable supporting structure that may be formed by the materials and prevent the "bridging" phenomenon from occurring. When the materials fall, they will collide with and be diverted by the inclined arch-breaking plates (at an angle of 30°-45°), thus dispersing the agglomerated materials and avoiding local accumulation, ensuring that the materials fall evenly and guaranteeing the continuity of the entire baking process.

[0094] Specifically, the vertical distance between two adjacent arch-breaking plates 312 is 3-5 times the length of the biomass feedstock. This arrangement allows the material to change its path multiple times during its fall (similar to a "zigzag motion") due to the obstruction of the arch-breaking plates, thereby extending its residence time within the second-stage reactor body 302 and ensuring sufficient time for the material to complete the pyrolysis reaction.

[0095] It should be noted that the reactor body 300 disclosed in the embodiment of the present invention also includes an air lock 307, wherein the air lock 307 is arranged at the lower part of the second-stage reactor body 302. The air lock 307 uses the intermittent sealing structure of its rotating impeller (or blade) to briefly open the channel when the biomass molded fuel formed after the reaction passes through, and quickly closes the channel after the material is discharged, which can effectively block the exchange of internal and external airflows, prevent external air from infiltrating or internal high-temperature gas / volatiles from leaking, and ensure the stability of the pressure and atmosphere required for the reaction.

[0096] The embodiment of the present invention does not limit the specific structure of the discharge mechanism. As long as the structure meets the use requirements of the present invention, it is within the protection scope of the present invention.

[0097] To further illustrate the present invention, a method and apparatus for low-temperature baking of biochar fuel provided by the present invention are described in detail below with reference to the following examples, but they should not be construed as limiting the scope of protection of the present invention.

[0098] Example 1

[0099] First, the reaction system is purged and replaced with N2 to ensure that the system is in an oxygen-free or low-oxygen environment, and then the biomass raw material level is added to 2 / 3 of the height of the segmented pyrolysis furnace body; the system pressure is increased to 0.1MPa; the auxiliary heating system is initially used to heat the hot carrier gas as the starting heat source to provide heat for the reaction; the hot carrier gas is sent into the segmented pyrolysis furnace from the hot carrier gas inlet pipe of each section respectively, and by adjusting the temperature and flow of each section of the hot carrier gas, the segmented pyrolysis furnace is divided into four pyrolysis temperature fields: drying (110℃), pyrolysis volatilization (220℃), constant temperature pyrolysis (270℃), and cooling (60℃). After the temperature field is established, the spiral discharging system is turned on, and the segmented pyrolysis furnace level control system is put into use to maintain the stability of the bed height. The hot carrier gas inlet flow rate and temperature of each section are coordinated to maintain the stability of the pyrolysis temperature field. The biomass raw materials pass through each set temperature field in turn during the movement from top to bottom in the furnace, and stay in the constant temperature pyrolysis section for 1 hour, thereby generating biomass molded fuel at the bottom of the furnace and outputting it from the bottom of the furnace to realize the preparation of biomass molded fuel.

[0100] A temperature gradient is maintained in the segmented pyrolysis furnace, so that the straw moves from top to bottom in the furnace and successively undergoes drying, pyrolysis volatilization, constant-temperature pyrolysis, and cooling stages, thereby generating biomass molded fuel at the bottom of the furnace and outputting it from the bottom of the furnace; at the same time, the reaction pyrolysis gas passes from top to bottom through the pyrolysis volatilization and constant-temperature pyrolysis section reaction bed layers. In this process, the tar and ash particles generated in the exhaust gas are adsorbed on the biomass and charcoal layers, and some liquid pyrolysis products are subjected to secondary pyrolysis.

[0101] The comparative example adopts the updraft carbonization furnace process, and the reaction conditions are the same as those in Example 1. The comparative example implementation process is as follows:

[0102] During the reaction process in an updraft carbonization furnace, the raw materials and the hot carrier gas flow in opposite directions in the vertical plane. The hot carrier gas rises from the bottom of the reactor to the top, while the biomass raw materials fall from the top to the bottom of the reactor. A temperature gradient is maintained in the reactor, and the furnace is filled with raw materials. As the raw materials gradually fall from the top to the bottom of the reactor, they are first dried, releasing the moisture contained in the raw materials. The raw materials continue to fall and gradually pass through higher temperature areas, where pyrolysis (cracking) reactions occur and "pyrolysis gases" (main components CO, CO2 and other light organic matter gases) are released. When the raw materials fall to the bottom area of ​​the furnace body, the raw materials undergo baking and pyrolysis reactions. At the same time, the pyrolysis gases continue to rise to the top of the furnace body, and after drying, condensation and purification, they are divided into two paths. Most of the pyrolysis gases are sent to the catalytic oxidizer for oxidation and heating. After the pyrolysis gases are pressurized, they enter the baking furnace from the bottom of the reactor to heat the raw materials and maintain the baking process of the raw materials.

[0103] Examples 2 to 7

[0104] The technical parameters of the preparation process of biomass charcoal fuel are shown in Table 1, and the rest are the same as in Example 1.

[0105] Table 1 Modulation reaction conditions of Examples 2 to 7

[0106]

[0107]

[0108] The analysis and evaluation indicators of the embodiment are as follows:

[0109] Thermogravimetric analysis: The analysis was performed using a PerkinElmer TGA4000 instrument.

[0110] Calorific value determination: HY-A9 calorimeter produced by Zhengzhou Hengya Instrument Co., Ltd. was used.

[0111] Exhaust gas particle concentration determination: HJ93-2013 standard was used for analysis.

[0112] Mass yield η m and energy yield η e The calculation formula is as follows:

[0113] η m =m2 / m1×100%;η e =η m ×(Q2 / Q1)

[0114] Where: m1 and Q1 represent the raw material mass and low calorific value, respectively; m2 and Q2 represent the biochar fuel mass and low calorific value, respectively.

[0115] The process parameters of Examples 2 to 7 are shown in Table 2. By comparing the reaction data of the comparative examples with those of Example 1 under the same experimental conditions, it can be seen that the biomass molded fuel preparation process of the present invention is higher than the updraft low-temperature carbonization process in terms of calorific value, mass yield, and energy yield; at the same time, the exhaust gas particle concentration is much lower than that of the updraft low-temperature carbonization process.

[0116] As shown in Table 2, compared with corn straw raw materials, the biomass briquette fuel of the present invention has a higher energy density, that is, a lower calorific value on an air-dried basis; during the low-temperature pyrolysis and carbonization process of the raw material particles, the pyrolysis gas produced takes away a portion of the energy, but the biomass charcoal fuel retains most of the energy of the corn straw raw material, and has a higher mass yield and energy yield (the ratio of the heat content of the main product (solid product of the process) to the heat content of the raw material).

[0117] (GB / T15224.3-2010), the biochar fuel of the present invention is equivalent to medium-low calorific value coal. Compared with the "Technical Specifications for Biomass Solid Briquette Fuels" (NY / T 1878-2010), the calorific value of the biochar fuel of the present invention is higher than that of grass-based biomass solid briquettes.

[0118] Table 2 Process parameters of Examples and Comparative Examples

[0119]

[0120]

[0121] As can be seen from the above examples, the production process provided by the present invention can be divided into six links as a whole: a feeding system, a staged pyrolysis furnace, a separation system, a cooling system, a graded temperature control system, and an exhaust gas circulation system. The main route is to produce charcoal by staged pyrolysis of biomass, and integrate processes such as heat recovery from catalytic oxidation of pyrolysis gas and secondary pyrolysis of wood tar to lighten the weight. This can achieve the co-production of charcoal, oil, and gas, as well as the removal of tar and efficient energy utilization. The process includes the following steps: in an atmosphere without oxygen or with an oxygen content of less than 5% by volume and at a pressure of 0.01 to 0.1 MPa, the biomass raw material and the hot carrier gas are brought into parallel contact to undergo a staged pyrolysis reaction to obtain pyrolysis gas and biochar fuel; the temperature of the parallel contact reaction is 240 to 300°C. In this method, the biomass raw material and the hot carrier gas are fully contacted and reacted in the reactor, and the biomass fuel is discharged from the bottom of the staged pyrolysis furnace after the reaction; the hot carrier gas and the pyrolysis gas generated by the reaction pass through the reaction bed in a permeation manner and are discharged from the bottom of the staged pyrolysis furnace. During this process, the hot carrier gas and the pyrolysis gas generated by the reaction are filtered and purified by the carbonization layer, and the filtered heavy tar is secondary pyrolyzed on the reaction bed to generate small molecular products and coke, thereby reducing the dust and heavy tar content in the pyrolysis gas, greatly reducing the system separation process load, and thus greatly improving the process stability; the biochar fuel produced by this process has a high energy density, a fixed carbon content, and excellent combustion performance.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for low-temperature baking of biomass charcoal fuel, comprising the following steps: In an atmosphere without oxygen or with an oxygen volume content of less than 5% and a pressure of 0.01 to 0.1 MPa, the biomass raw material and the hot carrier gas are contacted from top to bottom in the same direction to perform a staged pyrolysis reaction to obtain pyrolysis gas and biomass charcoal fuel; The temperature of the staged pyrolysis reaction is 240-300°C.

2. The method according to claim 1, characterized in that The bulk density of the biomass raw material is 0.25-1.0 g / cm 3 , moisture content <20%, particle size <150mm.

3. The method according to claim 1, characterized in that The volume ratio of the biomass raw material to the hot carrier gas entering the reaction system per unit time is (1:2000) to (1:6000).

4. The method according to claim 1, wherein The time of the staged pyrolysis reaction is 1 to 6 hours.

5. The method according to claim 1, characterized in that The main components of the hot carrier gas include N2 and CO2, the volume ratio of N2 to CO2 is (2:3) to (3:3), and the volume content of oxygen is less than 5%.

6. The method according to claim 1, wherein The biomass raw material is selected from one or more of waste corn stalks, waste cotton stalks and waste wood chips.

7. The method according to claim 1, characterized in that The staged pyrolysis reaction is carried out in a biomass continuous staged pyrolysis furnace; The biomass continuous segmented pyrolysis furnace includes a drying section, a pyrolysis and volatilization section, a constant temperature pyrolysis section and a cooling section; The temperature of the drying section is 105-115°C, the temperature of the pyrolysis and volatilization section is 210-230°C, the temperature of the constant temperature pyrolysis section is 240-300°C, and the temperature of the cooling section is 55-65°C.

8. A low-temperature baking device for biomass charcoal fuel, comprising a feeding unit, a biomass continuous staged pyrolysis furnace, a separation unit, a cooling unit, a graded temperature control unit, and an exhaust gas circulation unit; The feeding unit comprises a feeding auger (1), a receiving hopper (2) and a feeding hopper (3); The biomass continuous segmented pyrolysis furnace (4) is a continuous graded temperature-controlled biomass low-temperature baking furnace; the biomass raw material and the hot carrier gas contact from top to bottom in the same direction to carry out segmented pyrolysis reaction in the segmented pyrolysis furnace.

9. The device according to claim 8, characterized in that The hierarchical temperature control unit includes a high-temperature catalytic oxidation reactor (13) and a low-temperature catalytic oxidation reactor (14); The temperature difference between the hot carrier gas in the high-temperature catalytic oxidation reactor (13) and the low-temperature catalytic oxidation reactor (14) is 50 to 200° C.; and the flow ratio of the high-temperature hot carrier gas to the low-temperature hot carrier gas is 0.5 to 4:

1.

10. The device according to claim 8, characterized in that It also includes a biomass charcoal cooling and storage chamber (5), a spiral discharge cooler (6), and a product storage chamber (7) connected in sequence to the staged pyrolysis furnace (5); The discharge amount is adjusted by adjusting the frequency of the spiral discharge cooler (6), thereby controlling the reaction time.

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