CN209991448U

CN209991448U - Straw combustion machine

Info

Publication number: CN209991448U
Application number: CN201920895673.6U
Authority: CN
Inventors: 袁华; 钟清; 豆海峰
Original assignee: Chenzhou Huafeng Energy Technology Co Ltd
Current assignee: Chenzhou Huafeng Energy Technology Co Ltd
Priority date: 2019-06-14
Filing date: 2019-06-14
Publication date: 2020-01-24
Anticipated expiration: 2029-06-14

Abstract

The utility model relates to a straw combustion machine, which comprises a combustion furnace body, an air system device, a fire nozzle, a feeding device, a fire grate device and an ash discharging device; a cylindrical hearth is formed inside the combustion furnace body. Use the utility model discloses in the time, plant straw material passes through feed arrangement and gets into furnace of burner body from upper portion in, and plant straw material is lighted the back, and the air that the air-blower was blown in is shunted from the furnace bottom side through album bellows and is facing to the grate device direction blows in, and the flame that plant straw material burning produced is followed the burner blowout, aims at the equipment that needs the heating with the burner. The utility model discloses can alleviate the technical problem that uses plant straw to meet as fuel that exists among the prior art.

Description

Straw combustion machine

Technical Field

The utility model belongs to the technical field of combustion apparatus technique and specifically relates to a straw combustor is related to.

Background

Currently, coal-fired processing equipment used by a plurality of original agricultural product processing enterprises faces the reforming requirement due to the requirement of environmental protection policy. Because the natural gas and the electric energy are utilized, the popularization and the use in a large area in certain areas are not practical due to the restriction of installation, processing cost and the like. The use of the biomass pellet fuel can better solve the requirements of user cost and environmental protection rectification at present.

The existing biomass particle burner can not use rice straws, corn straws and the like as fuels because the plant straws have more carbon ash after being burnt, and if the plant straws cannot be discharged out of a hearth in time, the biomass particle burner can block the hearth and cannot be used.

2019, 02 and 05.2019, chinese patent application publication No. CN109307260A discloses a plant straw particle burner, which comprises a burner body, a feeding device, a grate device and an ash discharge device; a hearth is formed in the combustion furnace body, and a fire-jet hole communicated with the hearth is formed in the side wall of the combustion furnace body; the feeding device is arranged outside the combustion furnace body, and one end of the feeding device is communicated with the hearth; the grate device is arranged in the hearth and positioned below the outlet end of the feeding device, and can bear plant straw particles to move towards the direction far away from the outlet end of the feeding device; the ash discharging device is arranged below the combustion furnace body, is communicated with the hearth and is used for discharging carbon ash in the hearth. The ash discharging device below the furnace body of the plant straw particle burner can timely discharge carbon ash in the hearth, so that the carbon ash is prevented from blocking the hearth, and the plant straw with more carbon ash can be used as fuel by the plant straw particle burner.

Because the feeding device used by the feeding device has the feeding pipe arranged on one side outside the combustion furnace body, the blower directly blows plant straw particles in the feeding pipe into the hearth, and the plant straw particles with lower temperature rapidly cool the hearth, so that the hearth is easy to combust insufficiently. The flame sprayed by the flame spraying pipe device is the highest temperature flame smoke gas burnt by the hearth, but the burnt smoke gas of the hearth contains unburnt gasified biomass, so that the combustion efficiency is low. The crawler-type fire grate carries materials to move while burning, in order to ensure that plant straw particles are fully burnt, the length of the fire grate is inevitably prolonged or the moving speed of the fire grate is reduced as much as possible, the furnace body volume is directly increased due to the fact that the length of the fire grate is prolonged, the moving speed of the fire grate is reduced, and the fire grate can bear overhigh temperature to influence the service life.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a straw combustor to alleviate the technical problem that uses plant straw to meet as fuel that exists among the prior art.

The technical scheme of the utility model is that: a straw combustion machine comprises a combustion furnace body, an air system device, a burner, a feeding device, a grate device and an ash discharging device; a cylindrical hearth is formed inside the combustion furnace body;

the air system device comprises an air blower, an air collecting box, an air spraying box and a feeding induced draft fan; the blower is arranged beside the combustion furnace body, is shunted by the air collecting box and blows air from the bottom side of the hearth opposite to the grate device through the left main air duct and the right main air duct; the left main air duct and the right main air duct are respectively provided with a branch air duct; the upper part of the air collecting box is also provided with two small air pipes which are respectively connected with two air spraying air boxes on the top cover of the combustion furnace body; the two air-jet air boxes are arranged at the lower edges of two sides of the feeding hole of the top cover of the combustion furnace body in parallel, and the nozzles of the two air-jet air boxes face to be oppositely opened, so that air blown out by the two air-jet air boxes forms an air curtain below the feeding hole of the top cover of the combustion furnace body;

the fire nozzle consists of a high-temperature-resistant nozzle head, a fire nozzle outer cylinder and a water jacket inner cylinder, wherein the high-temperature-resistant nozzle head is in a cone cylinder shape, and one end of the fire nozzle outer cylinder is connected with the cone cylinder bottom of the high-temperature-resistant nozzle head; a water jacket inner cylinder is concentrically sleeved in the outer burner cylinder; a cyclone flow deflector is arranged in an annular gap between one end of the water jacket inner cylinder close to the direction of the high-temperature-resistant nozzle head and the fire nozzle outer cylinder, the other end of the water jacket inner cylinder is fixed on the outer side wall of the upper part of the hearth and communicated with the hearth, and an annular air chamber is formed among the inner wall of the fire nozzle outer cylinder, the cyclone flow deflector, the outer surface of the water jacket inner cylinder and the outer side wall of the upper part of the;

the circular wind chamber is provided with a first air inlet, a second air inlet and a third air inlet which are the same as the circular wind chamber on the circumference of the outer cylinder of the burner respectively, and the branched wind pipes on the left side and the right side are communicated with the first air inlet and the second air inlet respectively;

the feeding device comprises a hopper, a feeding pipe, a feeding induced draft fan and a feeding auger; the feeding pipe is vertically arranged, the upper end of the feeding pipe is connected with the hopper, and the lower end of the feeding pipe is arranged in the center of the top cover of the combustion furnace body; the pipe orifice at the lower end of the feeding pipe is communicated with the feeding hole of the top cover of the combustion furnace body; the feeding pipe is concentrically sleeved with a section of inner pipe with meshes which is equal to more than 70% of the length of the feeding pipe from a pipe orifice at the upper end, an annular interlayer air cavity is formed between the outer wall of the inner pipe with meshes and the inner wall of the corresponding feeding pipe, and the upper end and the lower end of the annular interlayer air cavity are sealed; the lower end of the feed pipe is not sleeved by the mesh inner pipe, and the peripheral wall of the pipe body of the feed pipe is provided with an interlayer water jacket;

the feeding auger consists of an auger driving motor, a vortex screw and an auger mounting seat; the auger driving motor is fixed on the auger mounting seat, and an output shaft of the auger driving motor is connected with the vortex screw; the auger mounting frame is arranged above the positive center of the hopper, the vortex screw rod is inserted along the central axis of the upper end of the feeding pipe, the vortex screw rod section equivalent to the height of the hopper is exposed at the position of the upper end of the feeding pipe corresponding to the position of the accommodating cavity of the hopper, and the lowest end of the vortex screw rod is inserted to the position flush with the inner pipe with the mesh;

the feeding induced draft fan is arranged on the outer side surface of the feeding pipe, an air inlet of the feeding induced draft fan is communicated with the annular interlayer air cavity, and an air outlet of the feeding induced draft fan is communicated with a third air inlet on the circumference of the outer cylinder of the burner through a feeding induced draft pipe;

the fire grate device comprises a crawler-type fire grate and a fire grate driving mechanism, the crawler-type fire grate is arranged below the cylindrical hearth, and an ash discharging device is arranged below one end of the crawler-type fire grate; the lower edge of the furnace wall of the cylindrical hearth is close to the edge of the ash discharging device, and an upper concave notch is arranged above the plane which is just opposite to the crawler-type fire grate; the grate driving mechanism is in transmission connection with the crawler-type grate; the distance between the upper opening edge of the upper concave notch on the lower edge of the furnace wall part of the hearth and the plane of the crawler-type fire grate below the corresponding position is the thickness of an oxidation layer, and the thickness is specifically 100-300 mm.

Furthermore, air volume adjusting air valves are respectively arranged on the branch air pipes and the feeding induced air pipes on the left side and the right side.

Further, a feeding conveyor belt is arranged above the hopper of the feeding device.

Technical scheme more than combining, the utility model discloses the beneficial effect who brings as follows:

when the straw combustion machine is used, plant straw materials enter a hearth of a combustion furnace body from the upper part through a feeding device, after the plant straw materials are ignited, air blown by an air blower is blown in from the bottom side of the hearth towards the direction of a grate device through a wind collecting box in a shunting manner, flame generated by combustion of the plant straw materials is sprayed out from a fire nozzle, and the fire nozzle is aligned to equipment needing to be heated. Because the plant straw materials of the utility model are preheated by the incomplete combustion waste heat smoke in the feeding pipe and then fall on the fire grate device in the hearth, the temperature stability of the hearth is ensured, and the combustion of the hearth is more sufficient; the plant straw material which participates in the reaction in the combustion furnace body is divided into a drying layer area, a thermal decomposition layer area (pyrolysis layer area), a reduction layer area and an oxidation layer area from top to bottom. The grate device drives the plant straw materials in the layered areas to move towards the ash discharging device while burning, and an upper concave notch is arranged on the lower edge of the furnace wall of the cylindrical hearth, close to the ash discharging device and opposite to the upper part of the plane of the crawler-type grate; plant straw materials above the separation oxidation layer are prevented from being retained in the hearth to be continuously combusted by utilizing the upper concave gap on the lower edge of the hearth wall; and separating carbon ash formed by combustion in the oxidation layer region into an ash discharging device, and discharging the carbon ash in the hearth out of the hearth by the ash discharging device. The utility model discloses need not extension grate length, the furnace body is small, because of the oxidation zone region direct contact crawler-type grate after the burning of plant straw material, the temperature that crawler-type grate bore is low, crawler-type grate long service life simultaneously.

Drawings

Fig. 1 is a schematic view of the structure of the present invention.

Fig. 2 is a left side view structure diagram of the present invention.

Fig. 3 is a schematic structural view of the burner of the present invention.

Fig. 4 is a schematic structural diagram of the feeding device of the present invention.

In the figure: 1, a combustion furnace body; 2, a grate device; 3, an ash discharging device; an air collecting box; 5, an air blowing box; 6 feeding an induced draft fan; 7, a main air duct; 8 branch air pipes; 9 small air pipes; 10, burning the furnace body top cover; 11, a nozzle; 12, a high-temperature resistant nozzle tip; 13 outer cylinder of burner; 14, an inner water jacket barrel; 15 cyclone flow deflectors; 16 annular air chamber; 17 a hopper; 18 a feed pipe; 19 mesh inner tube; 20 annular interlayer air cavities; 21 interlayer water jacket; 22 auger driving motor; 23, a vortex screw; 24 auger mounting seats; 25 feeding an induced draft tube; 26 is provided with a concave notch; 27 air volume adjusting air valve; 28 feed conveyor.

Detailed Description

In the description of the present invention, it should be noted that the terms "central axis", "vertical", "upper", "lower", "inner", "outer", "sleeve", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The embodiments are described in detail below with reference to the attached drawing figures: the present embodiment provides a straw combustion engine, please refer to fig. 1 to 4 in the drawings of the specification together.

As shown in fig. 1 and 4, a straw combustion machine comprises a combustion furnace body 1, an air system device, a burner, a feeding device, a grate device 2 and an ash discharging device 3; a cylindrical hearth is formed inside the combustion furnace body 1; the method is characterized in that: the air system device comprises an air blower, an air collecting box 4, an air spraying box 5 and a feeding induced draft fan 6; the blower is arranged beside the combustion furnace body 1, is divided by the air collecting box 4, and blows air from the bottom side of the hearth towards the grate device 2 through the left main air duct 7 and the right main air duct 7; the left main air duct 7 and the right main air duct 7 are respectively provided with a branch air duct 8; the upper part of the air collecting box 4 is also provided with two small air pipes 9 which are respectively connected with two air spraying air boxes 5 on a top cover 10 of the combustion furnace body; the two air-jet air boxes 5 are arranged at the lower edges of two sides of the feeding hole of the top cover 10 of the combustion furnace body in parallel, and the nozzles 11 of the two air-jet air boxes 5 face to be mutually opened, so that air blown out by the two air-jet air boxes 5 forms an air curtain below the feeding hole of the top cover 10 of the combustion furnace body;

the fire nozzle consists of a high-temperature resistant nozzle head 12, a fire nozzle outer cylinder 13 and a water jacket inner cylinder 14, wherein the high-temperature resistant nozzle head 12 is in a cone cylinder shape, and one end of the fire nozzle outer cylinder 13 is connected with the cone cylinder bottom of the high-temperature resistant nozzle head 12; a water jacket inner cylinder 14 is concentrically sleeved in the outer burner cylinder 13; a cyclone flow deflector 15 is arranged in an annular gap between one end of the water jacket inner cylinder 14 close to the direction of the high-temperature resistant nozzle head 12 and the burner outer cylinder 13, the other end of the water jacket inner cylinder 14 is fixed on the outer side wall of the upper part of the hearth and communicated with the hearth, and an annular air chamber 16 is formed among the inner wall of the burner outer cylinder 13, the cyclone flow deflector 15, the outer surface of the water jacket inner cylinder 14 and the outer side wall of the upper part of the hearth;

the annular wind chamber 16 is provided with a first air inlet, a second air inlet and a third air inlet which are the same as the first air inlet, the second air inlet and the third air inlet on the circumference of the outer burner barrel 13, and the left and right branch wind pipes 8 are respectively communicated with the first air inlet and the second air inlet;

the feeding device comprises a hopper 17, a feeding pipe 18, a feeding induced draft fan 6 and a feeding auger; the feeding pipe 18 is vertically arranged, the upper end of the feeding pipe 18 is connected with the hopper 17, and the lower end is arranged in the center of the top cover 10 of the combustion furnace body; the lower end pipe orifice of the feeding pipe 18 is communicated with the feeding hole of the top cover 10 of the combustion furnace body; a section of inner pipe 19 with meshes, which is equal to more than 70% of the length of the pipe of the feeding pipe 18, is concentrically sleeved in the feeding pipe 18 from a pipe orifice at the upper end, an annular interlayer air cavity 20 is formed between the outer wall of the inner pipe 19 with meshes and the corresponding inner wall of the feeding pipe 18, and the upper end and the lower end of the annular interlayer air cavity 20 are sealed; the lower end of the feeding pipe 18 is not sleeved by the inner pipe 19 with meshes, and the peripheral wall of the pipe body of the feeding pipe is provided with an interlayer water jacket 21;

the feeding auger consists of an auger driving motor 22, a vortex screw 23 and an auger mounting seat 24; the packing auger driving motor 22 is fixed on the packing auger mounting seat 24, and the output shaft of the packing auger driving motor 22 is connected with the vortex screw 23; the auger mounting seat 24 is erected above the right center of the hopper 17, the vortex screw 23 is inserted along the central axis of the upper end of the feed pipe 18, a vortex screw 23 section equivalent to the height of the hopper 17 is exposed at the position of the upper end of the feed pipe 18 corresponding to the cavity of the hopper 17, and the lowest end of the vortex screw 23 is inserted to be flush with the inner pipe 19 with meshes;

the feeding draught fan 6 is arranged on the outer side surface of the feeding pipe 18, an air inlet of the feeding draught fan 6 is communicated with the annular interlayer air cavity 20, and an air outlet of the feeding draught fan 6 is communicated with a third air inlet on the circumference of the burner outer cylinder 13 through a feeding induced air pipe 25;

the fire grate device 2 comprises a crawler-type fire grate and a fire grate driving mechanism, the crawler-type fire grate is arranged below the cylindrical hearth, and an ash discharging device 3 is arranged below one end of the crawler-type fire grate; an upper concave notch 26 is arranged on the lower edge of the furnace wall of the cylindrical hearth, close to the edge of the ash discharging device 3 and opposite to the upper part of the plane of the crawler-type fire grate; the grate driving mechanism is in transmission connection with the crawler-type grate; the distance from the upper opening edge of the upper concave notch 26 at the lower edge of the furnace wall part of the hearth to the crawler-type grate plane below the furnace wall part is the thickness of an oxidation layer, specifically 100-300 mm.

Furthermore, the branch air pipes 8 and the feeding induced air pipe 25 on the left and right sides are both provided with air volume adjusting air valves 27.

Further, a feeding conveyor belt 28 is arranged above the hopper 17 of the feeding device.

By combining the above technical solutions, the beneficial effects brought by this embodiment are analyzed as follows:

in the straw combustion machine provided by the embodiment, the crawler-type fire grate is used for bearing plant straw materials and driving the plant straw materials to move towards the ash discharging device 3 while burning, and an upper concave notch 26 is formed in the upper part of the crawler-type fire grate and is spaced from the lower edge of the corresponding furnace wall part of the hearth; plant straw materials above the separation oxidation layer are prevented from being retained in the hearth to be continuously combusted by utilizing the upper concave notch 26 on the lower edge of the hearth wall; the carbon ash formed by the combustion in the oxidation layer zone is separated and enters the ash discharging device 3.

In the embodiment, air volume adjusting air valves 27 are respectively arranged on the left and right branch air pipes 8 and the feeding induced air pipe 25, so that the mixing ratio of fresh air supply and incomplete combustion waste heat flue gas can be adjusted, and the optimal secondary cyclone combustion effect is achieved.

In the embodiment, the air blown out by the two air-jet air boxes 5 on the top cover 10 of the combustion furnace body forms an air curtain below the feed inlet of the top cover 10 of the combustion furnace body; the hearth flue gas can enter the feeding pipe 18 to be subjected to first dynamic blocking sealing; the thermal cycle between the furnace and the feeding device can be dynamically isolated.

An annular air chamber 16 arranged on the fire nozzle of the embodiment converges fresh air supplementary air and incompletely combusted waste heat flue gas, and by utilizing the design of a cyclone flow deflector 15, the cyclone flow deflector 15 is annularly configured at an angle of 360 degrees, and converged mixed incompletely combusted waste heat flue gas is sprayed into a high temperature resistant nozzle head 12; mixing with high-temperature flue gas sent out from a hearth to perform secondary cyclone combustion; so that the flame generates linear-cutting rotating flame along the direction of the flow guide cyclone, the incompletely combusted waste heat smoke can be fully and stably combusted, the combustion efficiency is high, and the combustion is more vigorous. The utility model discloses a water jacket inner tube 14 can reduce and require the nozzle inner tube material, can make the nozzle flame projecting temperature higher.

The feeding auger arranged in the feeding device of the embodiment utilizes the feeding conveyor belt 28 to continuously feed and fill the feeding pipe 18 and the auger to be continuously compacted and compacted, and can be matched with the two air-jet wind boxes 5 to realize the second dynamic sealing of the feeding pipe 18 to the hearth flue gas; and a small amount of incomplete combustion waste heat flue gas which permeates into the feeding pipe 18 through the plant straw material gap in the hearth is sucked into the annular interlayer air cavity 20 which has the function equivalent to that of the smoke collection box through the inner pipe 19 with meshes under the negative pressure action of the feeding draught fan 6, and then is delivered to the burner for secondary combustion through the feeding draught fan 6 through the feeding induced air pipe 25. Meanwhile, the small amount of incomplete combustion waste heat smoke permeating into the feeding pipe 18 through the gaps of the plant straw materials can also achieve the technical effect of preheating the plant straw materials.

In this embodiment, an interlayer water jacket 21 is provided on the peripheral wall of the lower end pipe body of the feed pipe 18, so as to protect the feed pipe 18 from high temperature.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention.

Claims

1. A straw combustion machine comprises a combustion furnace body (1), an air system device, a fire nozzle, a feeding device, a fire grate device (2) and an ash discharging device (3); a cylindrical hearth is formed inside the combustion furnace body (1); the method is characterized in that: the air system device comprises an air blower, an air collecting box (4), an air spraying box (5) and a feeding induced draft fan (6); the blower is arranged beside the combustion furnace body (1), is shunted by the wind collecting box (4), and blows air from the bottom side of the hearth opposite to the grate device (2) through the left main air duct and the right main air duct (7); branch air pipes (8) are respectively arranged on the left main air duct and the right main air duct (7); the upper part of the air collecting box (4) is also provided with two small air pipes (9) which are respectively connected with two air spraying air boxes (5) on a top cover (10) of the combustion furnace body; the two air-jet air boxes (5) are arranged at the lower edges of two sides of the feeding hole of the top cover (10) of the combustion furnace body in parallel, and the nozzles (11) of the two air-jet air boxes (5) face to be oppositely opened, so that air blown out by the two air-jet air boxes (5) forms an air curtain below the feeding hole of the top cover (10) of the combustion furnace body;

the burner consists of a high-temperature resistant nozzle head (12), a burner outer cylinder (13) and a water jacket inner cylinder (14), wherein the high-temperature resistant nozzle head (12) is in a cone cylinder shape, and one end of the burner outer cylinder (13) is connected with the cone cylinder bottom of the high-temperature resistant nozzle head (12); a water jacket inner cylinder (14) is concentrically sleeved in the fire nozzle outer cylinder (13); a cyclone flow deflector (15) is arranged in an annular gap between one end of the water jacket inner cylinder (14) close to the direction of the high-temperature resistant nozzle head (12) and the burner outer cylinder (13), the other end of the water jacket inner cylinder (14) is fixed on the outer side wall of the upper part of the hearth and is communicated with the hearth, and an annular air chamber (16) is formed among the inner wall of the burner outer cylinder (13), the cyclone flow deflector (15), the outer surface of the water jacket inner cylinder (14) and the outer side wall of the upper part of the hearth;

the annular air chamber (16) is provided with a first air inlet, a second air inlet and a third air inlet which are the same as the first air inlet, the second air inlet and the third air inlet on the circumference of the outer burner barrel (13), and the left and right branch air pipes (8) are respectively communicated with the first air inlet and the second air inlet;

the feeding device comprises a hopper (17), a feeding pipe (18), a feeding induced draft fan (6) and a feeding auger; the feeding pipe (18) is vertically arranged, the upper end of the feeding pipe (18) is connected with the hopper (17), and the lower end is arranged in the center of the top cover (10) of the combustion furnace body; the lower end pipe orifice of the feeding pipe (18) is communicated with the feeding hole of the top cover (10) of the combustion furnace body; the feeding pipe (18) is concentrically sleeved with a section of inner pipe (19) with meshes, which is equal to more than 70% of the length of the feeding pipe (18), from the pipe orifice at the upper end, an annular interlayer air cavity (20) is formed between the outer wall of the inner pipe (19) with meshes and the inner wall of the corresponding feeding pipe (18), and the upper end and the lower end of the annular interlayer air cavity (20) are closed; the lower end of the feeding pipe (18) is not sleeved by the inner pipe (19) with meshes, and the peripheral wall of the pipe body of the feeding pipe is provided with an interlayer water jacket (21);

the feeding auger consists of an auger driving motor (22), a vortex screw (23) and an auger mounting seat (24); the packing auger driving motor (22) is fixed on the packing auger mounting seat (24), and the output shaft of the packing auger driving motor (22) is connected with the vortex screw (23); the auger mounting seat (24) is erected above the center of the hopper (17), the vortex screw (23) is inserted along the central axis of the upper end of the feeding pipe (18), a vortex screw (23) section equivalent to the height of the hopper (17) is exposed at the position of the upper end of the feeding pipe (18) corresponding to the cavity of the hopper (17), and the lowest end of the vortex screw (23) is inserted to the position flush with the inner pipe (19) with meshes;

the feeding draught fan (6) is arranged on the outer side surface of the feeding pipe (18), an air inlet of the feeding draught fan (6) is communicated with the annular interlayer air cavity (20), and an air outlet of the feeding draught fan (6) is communicated with a third air inlet on the circumference of the burner outer cylinder (13) through a feeding induced draft pipe (25);

the fire grate device (2) comprises a crawler-type fire grate and a fire grate driving mechanism, the crawler-type fire grate is arranged below the cylindrical hearth, and an ash discharging device (3) is arranged below one end of the crawler-type fire grate; an upper concave notch (26) is arranged on the lower edge of the furnace wall of the cylindrical hearth, close to the edge of the ash discharging device (3) and opposite to the upper part of the plane of the crawler-type fire grate; the grate driving mechanism is in transmission connection with the crawler-type grate; the distance from the upper opening edge of the upper concave notch (26) at the lower edge of the furnace wall part of the hearth to the plane of the crawler-type grate below the furnace wall part is the thickness of an oxidation layer, specifically 100-300 mm.

2. The straw combustion engine as claimed in claim 1, wherein: and air volume adjusting air valves (27) are respectively arranged on the left and right branch air pipes (8) and the feeding induced draft pipe (25).

3. The straw combustion engine as claimed in claim 1, wherein: a feeding conveyor belt (28) is arranged above the hopper (17) of the feeding device.