CN110499191B - Middle part is given vent to anger downdraft biomass gasification stove - Google Patents

Abstract

The invention discloses a downdraft biomass gasifier with gas outlet in the middle. The method directly conducts gas combustion to generate high-temperature flue gas, and then uses the mixed gas of high-temperature flue gas and hot air as the gasification agent; effectively improves the drying and carbonization speed of biomass raw materials, and moves the high-temperature area in the furnace upward as a whole. Through the special furnace body structure design, the invention forms four right-angle regions by using the change from a cylindrical furnace body to a square furnace body; and then the gas is discharged from the four right-angle regions (ie, the middle of the furnace body) to form gas distributed on four sides. chemical area. On the one hand, the calcination of the lower rotary grate can be avoided, and the service life of the rotary grate can be extended;

Description

A downdraft biomass gasifier with central outlet

technical field

The invention relates to the field of biomass thermochemical conversion, and more particularly to a device for biomass pyrolysis and gasification.

Background technique

Biomass energy is a kind of renewable energy, which is the solar energy stored in the form of biomass by photosynthesis by plants. According to incomplete statistics, the energy stored in biomass through photosynthesis on the earth's surface every year is equivalent to 10 times the current human consumption. But unfortunately, the current utilization of biomass energy is still less than 1% of the new increase in biomass.

The direct combustion of biomass fuel will result in high dust content and difficult after-treatment. The current mainstream technology is to first gasify biomass fuel, and then perform secondary combustion of the syngas produced by the gasification. There are two types of fixed bed biomass gasifiers: up-draft and down-draft. Among them, the updraft biomass gasifier has high heat conversion efficiency, but the temperature of the syngas outlet is low, and the sealing requirements for the feed port are high. Otherwise, the air entering the gasifier from the feed port is prone to explosion. The downdraft biomass gasifier has low heat conversion efficiency and high outlet temperature of syngas, which easily burns out the grate system and affects the service life of the grate.

Chinese patent CN108728165A discloses a method for comprehensive utilization of carbon-based fertilizer production resources based on an updraft carbon-gas co-production furnace, which realizes comprehensive utilization of resources and improves the utilization efficiency of energy. The designed updraft carbon and gas co-production furnace is equipped with a two-stage feeding sealing system, and the feeding valve and the discharging valve of the secondary feeding bin adopt an interlocking control mechanism to ensure that one valve is open when the other valve is closed. , to prevent air from mixing into the furnace body and imploding.

Chinese patent CN109735367A discloses a downdraft gasifier. The downdraft gasifier includes a grate cover plate and a rotary drive mechanism, and the outer surface of the grate cover plate and the inner wall surface of the gasifier furnace body have an ash discharge gap. The grate cover is connected to the grate cover through a rotation driving mechanism and used to drive the grate cover to rotate. The downdraft gasifier drives the rotation of the grate cover plate through a rotary drive mechanism, so that the biomass ash is discharged through the ash discharge gap, thereby improving the operation continuity and stability of the downdraft gasifier.

Chinese patent CN 107033964B discloses a continuous slagging device for a downdraft biomass fixed bed gasifier. In order to solve the problem of high outlet temperature of downdraft biomass fixed bed gasifier, it is equipped with a water-cooled grate. The lower end of the grate is connected to the ash hopper, and the lower outlet of the ash hopper is connected to the slag discharge device. The lower part of the ash hopper and the inside of the slag discharge device are loaded with condensate, and the condensate submerges the lower part of the rotating device and the slag discharge device.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a downdraft biomass gasifier with a gas outlet in the middle in order to overcome the shortcomings of the existing downdraft biomass gasifier with low heat conversion efficiency and short service life of the grate system. The invention adopts a downdraft structure, and uses the mixed gas of high-temperature flue gas and hot air as a gasification agent, so that the raw materials can be rapidly dried and carbonized, and the heat conversion efficiency is improved. A special furnace body structure is designed so that the syngas can be drawn out in the middle of the furnace body, thus avoiding the calcination of the lower grate and ensuring the stability of the gasifier's operating conditions.

To achieve the above object, the present invention realizes through the following technical solutions:

A downdraft biomass gasifier with gas outlet from the middle, comprising: a feeding hopper, an air shutoff device, an upper furnace body, a material limiter, a middle furnace body, a rotary grate, a lower furnace body, and a slag discharger;

The feeding hopper is arranged above the air shutoff device, and is used for temporarily loading and controlling the entry of biomass raw materials into the furnace body;

The air shutoff device is arranged on the outer top of the upper furnace body to isolate the air inside the furnace body from the outside, preventing a large amount of air from entering the furnace body and causing gas explosion; in the present invention, the mixture of high temperature flue gas and hot air is used as the Gasification agent, a small amount of air entering the furnace body will not affect the stability of the work, so in actual use, a conventional star blanking device can be used as the air shutoff device.

The upper furnace body is a cylindrical cylinder body, the top is sealed and a related fan is arranged, and the bottom is hollow and communicated with the middle furnace body. The upper furnace body is used as a drying and carbonization reaction chamber for biomass raw materials;

The material limiter is a hollow pipe, which is arranged on the inner top of the upper furnace body, and is used to limit the height of the biomass raw material in the upper furnace body.

The middle furnace body is a square cylinder body, the upper end of which is communicated with the upper furnace body, and the lower end is arranged above the rotary grate; the middle furnace body is used as a combustion and gasification reaction chamber for biomass raw materials;

The biomass raw material in the feeding hopper can enter the upper furnace body through the air shutoff device and the material limiter, and be dried and carbonized in the upper furnace body;

The rotary grate is arranged between the middle furnace body and the lower furnace body, and is used for supporting biomass raw materials in the furnace body and controlling the entry of carbon slag into the lower furnace body. The rotary grate is connected with the power mechanism through chain and sprocket transmission;

The lower furnace body is an inverted cone, and the upper wide opening is connected to the rotary grate for collecting the carbon slag falling from the rotary grate;

The slag ejector is arranged below the lower furnace body and is connected with the conical opening of the lower furnace body, and is used for discharging the carbon slag from the furnace body. In form, the slag discharger can choose a water-cooled screw discharger, a water-cooled conveyor belt or a star blanker;

The upper furnace body, the middle furnace body and the lower furnace body are all provided with thermal insulation materials to ensure the temperature stability in the main furnace body.

The downdraft biomass gasifier with gas outlet from the middle of the present invention further comprises: a gas outlet, an annular gas collector, a gas pipeline, a gas fan, a gas distributor, a burner, a blower, a high-temperature flue, and an air inlet. , gas long-distance pipeline;

The gas outlet is respectively arranged at the junction of the upper furnace body and the middle furnace body; since the gas outlet is located in the middle of the whole furnace body, the present invention is called a downdraft biomass gasifier with gas outlet from the middle;

The annular gas collecting pipe surrounds the furnace body and communicates with a plurality of gas outlets respectively, and is used for collecting all the gas drawn from the furnace body;

The gas pipeline is arranged between the annular gas collecting pipe and the gas distributor, and is used for transporting the gas from the annular gas collecting pipe to the inlet of the gas distributor;

The gas fan is arranged in the middle of the gas pipeline to provide necessary power for drawing gas from the furnace body;

The gas distributor is arranged at the end of the gas pipeline, the first outlet of the gas distributor is connected to the burner, and the second outlet of the gas distributor is connected to the long-distance gas pipeline; For combustion; the other part is delivered to other gas equipment, such as gas boilers, etc. through gas long-distance pipelines;

The burner is a gas burner, and a high-temperature flue is arranged at its tail; the burner is used to provide the heat required for the pyrolysis and gasification reaction for the gasifier;

The blower is arranged at the air inlet of the burner to provide the required air for the combustion of the gas;

One end of the high-temperature flue is connected to the tail of the burner, and the other end is connected to the top or outer side of the upper furnace body for introducing the high-temperature flue gas generated by combustion into the upper furnace body.

The air inlet is arranged on the high temperature flue, and is used to provide air for the combustion and gasification reaction of biomass raw materials in the middle furnace body;

The outer parts of the annular gas collecting pipe, the gas pipeline, the gas fan and the gas long-distance pipeline are covered with thermal insulation materials to prevent condensation caused by the cooling of the gas.

The side length of the middle furnace body (square cylinder) is consistent with the diameter of the upper furnace body (cylindrical cylinder); the midpoints of the four sides of the square on the upper end face of the middle furnace body are respectively connected with the circumference of the lower end face of the upper furnace body. . In this special design, the transition from the cylindrical barrel to the square barrel brings advantages in two aspects. First, the whole furnace body is symmetrical up and down, and there is no major change in the shape; second, the square cylinder body is more convenient to cooperate and connect with the rotating grate.

The upper furnace body and the middle furnace body form four right-angled areas during the shape change of the furnace body, specifically, the midpoints of the four sides of the square on the upper end face of the middle furnace body correspond to the circumference of the lower end face of the upper furnace body respectively. After being welded together, the exposed part of the upper end face of the middle furnace body at the junction of the upper furnace body and the middle furnace body forms four right-angle areas; The combustion and gasification regions distributed on four sides are formed correspondingly at right angles inside the furnace body.

The significant difference between the patent of the present invention and the traditional downdraft gasifier and process is:

First, a mixture of high-temperature flue gas and hot air is used as a gasification agent. The invention directly conducts gas combustion to generate high temperature flue gas above 1000°C; and then mixes cold air through the air inlet to form a mixed gas of high temperature flue gas and hot air at about 800°C. Introducing this high temperature mixed gas into the upper furnace body can effectively improve the drying and carbonization speed of biomass raw materials.

Second, the gas is discharged in the middle of the furnace body. Since the present invention can realize rapid drying and carbonization of raw materials, the high temperature area in the furnace moves upward as a whole; therefore, the gas is designed to be outgassed at the joint between the upper furnace body and the middle furnace body (ie, the middle of the furnace body). In this way, the calcination of the lower rotary grate can be avoided, and the service life of the rotary grate can be prolonged.

Third, the special furnace body structure design forms the gasification zone distributed on four sides. In a traditional downdraft gasifier, the gasification zone is at the bottom of the furnace body. In the present invention, the upper furnace body (cylindrical cylinder body) and the middle furnace body (square cylinder body) form four right-angle areas during the shape change of the furnace body. Through the gas outlet, four gasification zones distributed on the sides are formed correspondingly at right angles inside the middle furnace body. This special structure makes the combustion and gasification reaction distribution in the furnace more uniform, and effectively prevents empty burning and partial burning.

It can be seen from the above that the beneficial effects of the present invention are: using the mixed gas of high temperature flue gas and hot air as a gasification agent, the drying and carbonization speed of biomass raw materials is accelerated, and the heat conversion efficiency is improved. By venting gas in the middle of the furnace body, the calcination of the lower grate system in the existing downdraft gasifier is avoided, and the service life of the rotary grate in the present invention is prolonged. The special furnace body structure design is used to form combustion and gasification areas distributed on four sides in the middle of the furnace body, which effectively prevents the hollow burning and partial burning of the existing downdraft gasifier. Compared with the prior art, the present invention has substantial features and significant progress.

Description of drawings

FIG. 1 is a three-dimensional schematic diagram of a main furnace body structure according to an embodiment of the present invention.

Fig. 2 is a schematic 45° oblique view of the reaction process area in the main furnace body according to the embodiment of the present invention.

FIG. 3 is a schematic diagram of the overall structure of an embodiment of the present invention.

The marking description of each part in the figure: 1. Feed hopper; 2. Air shutoff device; 3. Upper furnace body; 4. Material limiter; 5. Middle furnace body; 6. Rotary grate; 7. Lower furnace body; 8. Slag discharger; 9. Gas outlet; 10. Annular gas collecting pipe; 11. Gas pipeline; 12. Gas fan; 13. Gas distributor; 14. Burner; 15. Blower; 16. High temperature flue; 17. Air inlet; 18. Gas long-distance pipeline.

Detailed ways

The biomass gasifier technology and its beneficial effects provided by the present invention will be described in further detail below with reference to the accompanying drawings and preferred embodiments.

Referring to Fig. 1, a downdraft biomass gasifier with gas outlet from the middle includes: a feed hopper 1, an air shutoff device 2, an upper furnace body 3, a feed limiter 4, a middle furnace body 5, a rotary grate 6, Lower furnace body 7, slag discharger 8.

Feed hopper 1 is an inverted cone, the upper wide mouth is 1.5 meters long and 1.5 meters wide, the lower conical mouth is 0.3 meters long and 0.3 meters wide, and the total height is 1.5 meters. The feeding hopper is arranged above the air shutoff device 2, and is used to load and control the biomass raw materials entering the furnace body.

The air shut-off device 2 is a star-shaped blanking device with an opening of 300mm×300mm, which is arranged on the outer top of the upper furnace body 3 to prevent a large amount of air from entering the furnace body and causing gas explosion.

The upper furnace body 3 is a cylindrical cylinder made of stainless steel, with a diameter of 2.5 meters, a height of 4 meters, and a wall thickness of 6 mm;

The material limiter 4 is a hollow pipe made of stainless steel, with a diameter of 1.0 meters, a height of 0.8 meters, and a wall thickness of 4 mm; the material limiter 4 is arranged on the inner top of the upper furnace body 3 . As shown in FIG. 2 , the height of the biomass raw material in the upper furnace body 3 can be limited by the lower end face of the material limiter 4 , so as to ensure that the biomass raw material does not enter the high temperature flue 16 and prevent the high temperature flue 16 from being blocked. .

The biomass raw material in the above-mentioned feeding hopper 1 can enter the upper furnace body 3 through the air shutoff device 2 and the material limiter 4 and be dried and carbonized in the upper furnace body 3 .

The middle furnace body 5 is a square cylinder made of stainless steel, with a square side length of 2.5 meters, a height of 2.5 meters, and a wall thickness of 6 mm; the midpoints of the four sides of the square on the upper end face of the middle furnace body 5 and the circumference of the lower end surface of the upper furnace body 3 are welded to each other. At the same time, the middle furnace body 5 and the upper furnace body 3 communicate with each other, and the middle furnace body 5 and the upper furnace body 3 are not communicated with the outside world.

The lower end of the middle furnace body (5) is arranged above the rotary grate (6), and serves as a combustion and gasification reaction chamber for biomass raw materials. The rotary grate 6 is composed of 11 water-cooled pipes, which are evenly distributed in the middle Bottom of furnace body 5. Preferably, the 11 water-cooling tubes are connected to the power mechanism through a chain and a sprocket, and the power mechanism can drive the 11 water-cooling tubes to rotate through the chain and the sprocket, which is the prior art. The main function of the rotary grate 6 is to support the biomass raw materials in the furnace, and at the same time, the falling amount of the carbon residue can be controlled by adjusting the rotation speed of the 11 water-cooled tubes. The middle furnace body 5 and the rotary grate (6) communicate with each other and the middle furnace body 5 and the rotary grate (6) are not communicated with the outside world.

The lower furnace body 7 is an inverted cone made of stainless steel, the upper wide mouth is 2.5 meters long and 2.5 meters wide, the lower conical mouth is 0.5 meters long and 0.5 meters wide, the total height is 2.0 meters, and the wall thickness is 6 mm. The upper wide opening is connected to the rotary grate 6 for collecting the carbon slag falling from the rotary grate 6; the lower furnace body 7 is communicated with the rotary grate (6) and the lower furnace body 7 is connected to the rotary grate (6). 6) Not communicating with the outside world.

The slag discharger 8 is a water-cooled screw discharger, and its feeding port is connected to the lower cone mouth of the lower furnace body 7, and a star-shaped blanking device is set at the discharge port to control the slag discharge speed.

The outer parts of the upper furnace body 3, the middle furnace body 5 and the lower furnace body 7 are all covered with 100mm insulation cotton to be insulated from the outside of the furnace, so as to ensure the temperature stability in the main furnace body.

2 , further specifically, the upper furnace body 3 is mainly used as a drying and carbonization reaction chamber for biomass raw materials, and the middle furnace body 5 is mainly used as a combustion and gasification reaction chamber for biomass raw materials. A plurality of gas outlets 9 can be provided. In this embodiment, the middle points of the four sides of the square on the upper end face of the middle furnace body 5 are respectively welded with the corresponding parts of the circumference of the lower end face of the upper furnace body 3, and then the middle furnace body at the junction is welded together. The exposed part of the upper end of 5 facing the outside world is the upper end surface of the four right-angle areas, and there are four gas outlets 9, which are respectively arranged on the upper end surfaces of the four right-angle areas of the middle furnace body 5, so the right angle inside the middle furnace body 5 is There are four combustion and gasification zones distributed on the sides correspondingly to generate medium-temperature gas with a temperature of >600°C.

Referring to FIG. 3 , a downdraft biomass gasifier with gas outlet from the middle of the present invention further includes: an annular gas collecting pipe 10, a gas pipeline 11, a gas fan 12, a gas distributor 13, a burner 14, Blower 15, high temperature flue 16, air inlet 17, gas long-distance pipeline 18.

The annular gas collecting pipe 10 is a stainless steel annular pipe with a cross-section of 400mm×400mm; the annular gas collecting pipe 10 surrounds the upper furnace body 3 and communicates with the four gas outlets 9 respectively for collecting the four right-angle areas of the middle furnace body 5. All gas drawn in.

The gas pipeline 11 is a stainless steel pipeline with a cross-section of 400mm×400mm, and is used to transport the gas from the annular gas collecting pipe 10 to the inlet of the gas distributor 13;

The gas fan 12 selects a high-temperature stainless steel centrifugal fan with a flow rate of 10,000 cubic meters per hour, and sends the gas in the gas pipeline 11 to the inlet of the gas distributor 13 .

The gas distributor 13 is a three-way valve mechanism that can distribute the flow. The first outlet is connected to the burner 14 , and the second outlet is connected to the long-distance gas pipeline 18 .

The burner 14 is a cylindrical gas combustion furnace with a diameter of 1.5 meters and a length of 6.0 meters, and refractory bricks and thermal insulation bricks with a thickness of 300 mm are cut in the combustion furnace. The function of the burner 14 is to fully burn the gas and form high temperature flue gas at about 1050°C.

The gas pipeline 11 is arranged between the annular gas collecting pipe 10 and the gas distributor 13, and the front end of the gas pipeline 11 is communicated with the annular gas collecting pipe 10, and is used to transport the gas from the annular gas collecting pipe 10 to the inlet of the gas distributor 13; The gas fan 12 is arranged in the middle of the gas pipeline 11 to provide necessary power for drawing out the gas from the middle furnace body 5; It is sent to the inlet of the gas distributor 13; the first outlet of the gas distributor 13 is connected to the burner 14, and the second outlet of the gas distributor 13 is connected to the long-distance gas pipeline 18; the gas distributor 13 is used to divide the gas into two parts, and a part is sent to the combustion The gas burner 14 is used for combustion, and the other part is delivered to other gas equipment through the gas long-distance pipeline 18;

The blower 15 selects a centrifugal fan with a flow rate of 15,000 cubic meters per hour, and is arranged at the air inlet of the burner 14 to provide the required air for gas combustion;

The high-temperature flue 16 is a square channel with a cross-section of 800mm×800mm, and a 200mm-thick thermal insulation brick is cut inside. One end of the high-temperature flue 16 is connected to the tail of the burner 14, and the other end is connected to the high-temperature flue gas inlet opened on the outer side of the upper furnace body 3 near the top, and is used to introduce the high-temperature flue gas generated by combustion into the upper furnace body 3. .

The air inlet 17 is arranged on the high temperature flue 16, so that the air can enter the high temperature flue 16 and mix with the high temperature flue gas in a volume ratio of 1:4 to form a high temperature flue gas and hot air mixed gas at about 800°C.

The outside of the annular gas collecting pipe 10 , the gas pipeline 11 , the gas fan 12 and the gas long-distance pipeline 18 are covered with 100mm thermal insulation cotton to prevent condensation caused by the cooling of the gas.

Claims (3)

1. A downdraft biomass gasifier with gas outlet from the middle, comprising: a feeding hopper (1), an air shutoff device (2), an upper furnace body (3), a material limiter, a middle furnace body (5), The rotary grate (6), the lower furnace body (7), and the slag discharger (8) are characterized in that: The feeding hopper (1) is arranged above the air shutoff device (2), and is used for temporarily loading and controlling the entry of biomass raw materials into the furnace body; The air shutoff device (2) is arranged on the outer top of the upper furnace body (3) to prevent a large amount of air from entering the furnace body and causing gas explosion; The upper furnace body (3) is a cylindrical body, the top is sealed and a relevant fan (2) is arranged, and the bottom is hollow in communication with the middle furnace body (5), serving as a drying and carbonization reaction chamber for biomass raw materials; The material limiter (4) is a hollow pipe, which is arranged on the inner top of the upper furnace body (3) and is used to limit the height of the biomass raw material in the upper furnace body (3); The biomass raw material in the feeding hopper (1) can enter the upper furnace body (3) through the air shutoff device (2) and the material limiter (4), and be dried and carbonized in the upper furnace body (3); The middle furnace body (5) is a square cylinder body, the upper end of which is communicated with the upper furnace body (3), and the lower end thereof is arranged above the rotary grate (6) as a combustion and gasification reaction chamber for biomass raw materials; The rotary grate (6) is arranged between the middle furnace body (5) and the lower furnace body (7), and is used for supporting biomass raw materials in the furnace body and controlling the entry of carbon slag into the lower furnace body (7); The lower furnace body (7) is an inverted cone, and the upper wide opening is connected to the rotary grate (6) for collecting the carbon slag falling from the rotary grate (6); The slag ejector (8) is arranged below the lower furnace body (7), and is connected to the lower conical opening of the lower furnace body (7), for discharging the carbon slag from the furnace body; The upper furnace body (3), the middle furnace body (5) and the lower furnace body (7) are all provided with thermal insulation materials to ensure the temperature stability in the main furnace body. 2. A downdraft biomass gasifier with gas outlet from the middle part according to claim 1, characterized in that it further comprises: a gas outlet (9), an annular gas collecting pipe (10), a gas pipeline (11), a gas fan (12), a gas distributor (13), a burner (14), a blower (15), a high temperature flue (16), an air inlet (17), and a long-distance gas pipeline (18); The gas outlet (9) is respectively arranged at the connection between the upper furnace body (3) and the middle furnace body (5), and is used to lead the gas inside the middle furnace body (5) out of the middle furnace body; The annular gas collecting pipe (10) surrounds the upper furnace body and communicates with a plurality of gas outlets (9) arranged at the connection between the upper furnace body (3) and the middle furnace body (5), and is used for collecting the middle furnace body. All gas extracted from the body; The gas pipeline (11) is arranged between the annular gas collecting pipe (10) and the gas distributor (13), and the front end of the gas pipeline (11) is communicated with the annular gas collecting pipe (10), and is used for transferring the gas from the annular gas collecting pipe (10). 10) to the inlet of the gas distributor (13); The gas blower (12) is arranged in the middle of the gas pipeline (11) to provide necessary power for extracting gas from the middle furnace body (5); The gas distributor (13) is arranged at the rear end of the gas pipeline (11); the first outlet of the gas distributor (13) is connected to the burner (14), and the second outlet of the gas distributor (13) is connected to the long-distance gas pipeline (18). Because the gas is divided into two parts, one part is sent to the burner (14) for combustion, and the other part is sent to other gas equipment through the gas long-distance pipeline (18); The burner (14) is a gas burner, and a high-temperature flue (16) is arranged at the tail thereof, which is used to provide the gasifier with the heat required for the pyrolysis and gasification reaction; The blower (15) is arranged at the air inlet of the burner (14) to provide the required air for the combustion of the gas; One end of the high temperature flue (16) is connected to the tail of the burner (14), and the other end is connected to the top of the upper furnace body (3) or the high temperature flue gas inlet opened on the outer side of the top, for connecting the burner (14) The high-temperature flue gas generated by the combustion is introduced into the upper furnace body (3) to provide a heat source for the drying and carbonization reaction of biomass raw materials; The air inlet (17) is arranged on the high temperature flue (16), so that the air and the high temperature flue gas are mixed inside the high temperature flue (16). 3. the downdraft biomass gasifier of a kind of middle outlet gas according to claim 1 and 2, is characterized in that: The side length of the middle furnace body (5) in the shape of a square cylinder is consistent with the diameter of the upper furnace body (3) in the shape of a cylindrical cylinder; The circumference of the lower end face of the furnace body (3) is connected together; After the middle points of the four sides of the square on the upper end face of the middle furnace body (5) are welded together with the corresponding parts of the circumference of the lower end face of the upper furnace body (3), the upper furnace body (3) and the middle furnace body (5) are welded together. The exposed part of the upper end face of the middle furnace body (5) at the junction of the junction forms four right-angle areas; The gas outlets (9) are arranged on the upper end faces of the four right-angle regions, and correspondingly form four gasification regions distributed on the sides at the right angles inside the middle furnace body (5).

Images