A low calorific value biomass semi-fluidized bed composite grate combustion furnace

Abstract

The invention discloses a low calorific value biomass semi-fluidized bed composite grate combustion furnace, and its technical key points are: a feeding mechanism is arranged in the middle of a main bed combustion chamber; a water-cooled furnace bed is arranged in the lower part of the main bed combustion chamber, a high-pressure fan with an air outlet facing upward is arranged in the lower part of the water-cooled furnace bed, and the water-cooled furnace bed is connected to the slag grate at its rear end; an ash pushing mechanism fixed on the outer furnace wall of the main bed combustion chamber and a combustion chamber gas seal are arranged at the front end of the water-cooled furnace bed, and an ash pushing plate that moves to the upper surface of the water-cooled furnace bed is arranged on the ash pushing mechanism; the invention solves the ignition and combustion problems of low calorific value biomass by drying and igniting the fuel by high-temperature flue gas during the descending process and falling on the fire bed above the water-cooled furnace bed, and then using high-pressure wind to blow up the falling material for secondary ignition, and forming a new fire bed after ignition.

Description

Technical Field

[0001] The invention belongs to the technical field of combustion furnaces, and in particular relates to a low calorific value biomass semi-fluidized bed composite grate combustion furnace. Background Art

[0002] The existing combustion furnaces are generally divided into three categories: the first is the biomass fluidized bed boiler, which has the advantage of being able to burn low calorific value biomass with high efficiency; the disadvantage is that it cannot burn biomass with low ash melting point and has poor variable load capacity. The second is the biomass layer-fired reciprocating grate boiler, which has the advantage of being able to burn biomass with low ash melting point and can be stopped at any time; the disadvantage is that it cannot burn biomass with low calorific value and the furnace efficiency is generally low. The third is the vibrating water-cooled hearth furnace, which has the advantage of being able to burn biomass with low calorific value and low ash melting point; the disadvantage is that it is expensive, inefficient, and cannot be miniaturized.

[0003] In actual production, low calorific value biomass is very common and low cost, such as corn stalks, fruit tree prunings, edible fungus waste, furfural residue, etc. The purpose of our research and development of the biomass semi-fluidized bed composite grate combustion furnace is to solve the problem of burning low calorific value biomass, improve combustion efficiency, and increase the variable load capacity of the furnace. Summary of the invention

[0004] In order to make up for the deficiencies of the prior art, the present invention provides a low calorific value biomass semi-fluidized bed composite grate combustion furnace to solve the problem of burning low calorific value biomass with high combustion efficiency.

[0005] The present invention is realized through the following technical scheme: a low calorific value biomass semi-fluidized bed composite grate combustion furnace, comprising an auxiliary combustion chamber with a slag grate, a slag arch and a slag discharge pit, a main bed combustion chamber connected to the auxiliary combustion chamber, a heat exchange chamber connected to the main bed combustion chamber, a smoke outlet arranged on the outer wall of the heat exchange chamber, a water-cooled furnace bed arranged inside the main bed combustion chamber, a wind chamber arranged below the water-cooled furnace bed, a feeding mechanism fixed on the outer furnace wall of the main bed combustion chamber, and a combustion material of low calorific value biomass. The technical key points are: the feeding mechanism The mechanism is arranged in the middle of the main bed combustion chamber; the water-cooled furnace bed is inclinedly arranged at the lower part of the main bed combustion chamber, and a high-pressure fan with an air outlet facing upward is arranged at the lower part of the water-cooled furnace bed, and the water-cooled furnace bed is connected to the slag grate at its rear end; an ash pushing mechanism is arranged on the outer furnace wall of the main bed combustion chamber at the front end of the water-cooled furnace bed, and the ash pushing mechanism is provided with an ash pushing plate that moves to the upper surface of the water-cooled furnace bed; a combustion chamber gas seal is connected to the upper part of the ash pushing mechanism; a main combustion chamber flue gas outlet connected to the heat exchange chamber is arranged at the upper part of the main bed combustion chamber.

[0006] Furthermore, the ash pushing plate is a rectangular parallelepiped, and a water cooling pipe is arranged inside the rectangular parallelepiped.

[0007] Furthermore, the combustion chamber gas seal includes a sealed high-pressure fan disposed therein, the air outlet of which is connected to the main bed combustion chamber on the upper part of the water-cooled furnace bed.

[0008] Furthermore, the slag grate is a chain grate, a reciprocating grate or a water-cooled grate.

[0009] Furthermore, the water-cooled furnace bed includes water-cooling pipes arranged side by side inside it, connecting headers arranged transversely at its upper and lower ends, and connecting plates arranged between the water-cooling pipes; the air outlet of the high-pressure fan is arranged on the connecting plate.

[0010] Furthermore, the low calorific value biomass material is corn stalks, fruit tree prunings, edible fungus waste or furfural residue.

[0011] The beneficial effects of the present invention are:

[0012] The furnace bed adopts water-cooled furnace bed high-pressure air combustion, the wind cap on the top of the furnace bed is cancelled, and the water-cooled furnace bed is adopted to avoid the loss of the wind cap after the furnace is stopped, and the furnace can be stopped at any time; an ash pusher plate with water cooling that can be moved to the outside is used to prevent the ash pusher plate from burning at high temperature in the main bed; no base material is added to the fire bed, and the fuel is directly added to the fire bed, and a new fire bed is formed after ignition; the feed amount and high-pressure air distribution are adjusted according to load changes to ensure efficient combustion rate under low load conditions; low calorific value biomass such as corn stalks, fruit tree prunings, edible fungus waste, furfural residue, etc. are selected as combustion materials, which are very common and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the elevation structure of the present invention.

[0014] Explanation of the main component numbers in the figure: 1. Water-cooled furnace bed; 2. Ash pushing plate; 3. Ash pushing mechanism; 4. Combustion chamber gas seal; 5. Main bed combustion chamber outer furnace wall; 6. Feeding mechanism; 7. Feed hopper; 8. Main bed combustion chamber; 9. Main combustion chamber flue gas outlet; 10. Main bed combustion chamber furnace wall; 11. Heat exchange chamber; 12. Smoke outlet; 13. Slag rear furnace wall; 14. Slag arch; 15. Slag pit; 16. Slag grate; 17. Auxiliary combustion chamber; 18. Wind chamber.

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. DETAILED DESCRIPTION

[0016] The following combination Figure 1 , the contents of the present invention are described in detail through specific embodiments. Example

[0017] The low calorific value biomass semi-fluidized bed composite grate combustion furnace comprises an auxiliary combustion chamber 17 with a slag grate 16, a slag arch 14 and a slag discharge pit 15, a main bed combustion chamber 8 connected to the auxiliary combustion chamber, a heat exchange chamber 11 connected to the main bed combustion chamber, a smoke outlet 12 arranged on the outer wall of the heat exchange chamber, a water-cooled furnace bed 1 arranged inside the main bed combustion chamber, a wind chamber 18 arranged below the water-cooled furnace bed, a feeding mechanism 6 fixed on the furnace wall outside the main bed combustion chamber, and a combustion material of low calorific value biomass, wherein: The feeding mechanism of the hopper 7 is arranged in the middle of the main bed combustion chamber; the water-cooled furnace bed is arranged obliquely at the lower part of the main bed combustion chamber, and the water-cooled furnace bed includes water-cooled pipes arranged side by side inside it, connecting headers arranged horizontally at its upper and lower ends, and connecting plates arranged between the water-cooled pipes; a high-pressure fan with an air outlet upward is arranged at the lower part of the water-cooled furnace bed, and the air outlet of the high-pressure fan is arranged on the connecting plate; the water-cooled furnace bed is connected to the slag grate at its rear end, and the slag grate is a chain grate, a reciprocating grate or a water-cooled grate, and the slag grate is connected to the slag grate. The lower part of the rear end of the slag grate is a slag discharge pit; an ash pushing mechanism 3 is arranged on the outer furnace wall of the main bed combustion chamber at the front end of the water-cooled furnace bed, and the ash pushing mechanism is provided with an ash pushing plate 2 that moves to the upper surface of the water-cooled furnace bed. The ash pushing plate is a rectangular parallelepiped, and can move to the inside of the main bed combustion chamber when pushing ash to push the ash on the water-cooled furnace bed to move toward the slag grate; when not pushing ash, it retreats to the outside of the main bed combustion chamber. In order to prevent the ash pushing plate from being burned at high temperature inside the main bed combustion chamber, a water cooling pipe is arranged inside the ash pushing plate, and water cooling is adopted for cooling; in the ash pushing mechanism The upper part is connected with a combustion chamber gas seal 4, which includes a sealed high-pressure fan arranged inside it, and the air outlet of the sealed high-pressure fan is connected with the main bed combustion chamber on the upper part of the water-cooled furnace bed. The combustion chamber gas seal mainly prevents the gas of the main bed combustion chamber from leaking out; a main combustion chamber flue gas outlet 9 connected with the heat exchange chamber is arranged on the main bed combustion chamber inner furnace wall 10 at the upper part of the main bed combustion chamber; the combustion materials of low calorific value biomass are corn stalks, fruit tree prunings, edible fungus waste or furfural residue.

[0018] The workflow of the present invention;

[0019] During ignition, the feed hopper 7 is fed with low calorific value biomass combustion materials, which are transported to the main bed combustion chamber 8 through the feeding mechanism 6 and fall onto the water-cooled furnace bed 1, and then ignited. When the furnace temperature reaches about 900°C, the feeding mechanism feeds the materials, and the materials are dried, ignited, and burned in contact with the high-temperature flame during the falling process. After the fuel falls onto the fire bed, the drying, ignition, and combustion process continue, and a new fire bed is formed after combustion. High-pressure wind is supplied from the lower part of the water-cooled furnace bed to penetrate the fire bed and the newly added combustion materials on the upper part, and the ashes, small particles of ash, and unburned small particles of fuel in the fire bed are blown into the main bed combustion chamber to burn together with the falling fuel, forming a combustion state of strong wind and strong fire. Ashes burned on the water-cooled furnace bed are pushed to the slag grate 16 of the auxiliary combustion chamber 17 by the ash pusher plate 2 for regular slagging. After slagging, the ash pusher plate is pushed to the slag discharge pit 15. When pushing ash, the ash pusher plate can move to the inside of the main combustion chamber to push the ash on the water-cooled furnace bed to the slag grate; when not pushing ash, it retreats to the outside of the main combustion chamber. The burning high-temperature flames pass through the main combustion chamber smoke outlet 9 to the heat exchange chamber 11, and are discharged through the smoke outlet 12 after heat exchange.

[0020] Working principle of the present invention:

[0021] The combustion materials used are low calorific value biomass, such as corn stalks, fruit tree prunings, edible fungus waste, furfural residue, etc.

[0022] Different from the combustion method of fluidized bed combustion technology, the semi-fluidized bed composite grate combustion technology does not add base material to the fire bed. The fuel is directly added to the fire bed and ignited to form a new fire bed. The newly added fuel to the furnace comes into contact with the burning high-temperature flue gas during the falling process and is quickly dried and ignited, forming air volume combustion. The high-pressure wind is arranged in zones, and the air volume is adjusted by frequency conversion control of multiple high-pressure fans. The high-pressure wind does not throw all the materials on the bed into the air for fluidized combustion like the fluidized bed, but only penetrates the fire bed and fuel, and only throws the unburned ash, small particles of carbon, and small-sized biomass fuel on the fire bed into the air for fluidized combustion, forming a combustion state of high wind and high fire with the falling material.

[0023] The wind cap on the furnace bed is removed, and a water-cooled furnace bed with an inclined fixed arrangement is used to prevent the wind cap from burning when the furnace is stopped. The furnace bed is equipped with a high-pressure air outlet; an ash pushing mechanism and a seal are provided on the front side of the furnace bed. The ash pushing mechanism is connected to an ash pushing plate. The movement direction of the ash pushing plate is parallel to the inclined surface of the water-cooled furnace bed and is located on the surface of the furnace bed. When pushing ash, the ash pushing plate can move to the inside of the main bed combustion chamber to push the ash on the furnace bed to move toward the slag grate; when not pushing ash, it retreats to the outside of the main bed combustion chamber. In order to prevent the ash pushing plate from burning at high temperature in the main bed combustion chamber, water cooling is used inside the ash pushing plate. The burned biomass is pushed to the slag grate by the ash pushing mechanism to slag, and after burning, it is sent to the slag pit by the slag grate. The combustion chamber gas seal prevents the main combustion chamber gas from leaking out.

[0024] The furnace bed adopts water-cooled furnace bed high-pressure air combustion, which reduces the combustion temperature on the bed, solves the problem of low melting point of biomass ash blocking the wind hood and burning the wind hood when the furnace is shut down, and the furnace can be shut down at any time; at the same time, the feed amount and air distribution can be adjusted according to load changes, solving the problem of low combustion efficiency under low load conditions.

[0025] The biomass semi-fluidized bed composite grate combustion technology of the present invention can not only efficiently burn low calorific value biomass fuel, but also can be stopped at any time, with a fast temperature increase speed, and is particularly suitable for occasions with relatively large load changes. The present invention can also be applied to the combustion of solid waste.

Claims

1. A low calorific value biomass semi-fluidized bed composite grate combustion furnace, comprising an auxiliary combustion chamber with a slag grate, a slag arch and a slag discharge pit, a main bed combustion chamber connected to the auxiliary combustion chamber, a heat exchange chamber connected to the main bed combustion chamber, a smoke outlet arranged on the outer wall of the heat exchange chamber, a water-cooled furnace bed arranged inside the main bed combustion chamber, a wind chamber arranged below the water-cooled furnace bed, a feeding mechanism fixed on the outer furnace wall of the main bed combustion chamber, and low calorific value biomass combustion materials, characterized in that: The feeding mechanism is arranged in the middle of the main bed combustion chamber; the water-cooled furnace bed is arranged obliquely at the lower part of the main bed combustion chamber, and a high-pressure fan with an air outlet facing upward is arranged at the lower part of the water-cooled furnace bed, and the water-cooled furnace bed is connected to the slag grate at the rear end thereof; the water-cooled furnace bed includes water-cooling pipes arranged side by side inside it, connecting headers arranged horizontally at its upper and lower ends, and a connecting plate arranged between the water-cooling pipes; the air outlet of the high-pressure fan is arranged on the connecting plate; an ash pushing mechanism is arranged on the furnace wall outside the main bed combustion chamber at the front end of the water-cooled furnace bed, and the ash pushing mechanism is provided with an ash pushing mechanism which moves to the upper surface of the water-cooled furnace bed. plate; a combustion chamber gas seal is connected to the upper part of the ash pushing mechanism; the combustion chamber gas seal includes a sealed high-pressure fan arranged inside it, and the air outlet of the sealed high-pressure fan is connected to the main bed combustion chamber on the upper part of the water-cooled furnace bed; a main combustion chamber flue gas outlet connected to the heat exchange chamber is arranged on the upper part of the main bed combustion chamber; the furnace temperature of the main bed combustion chamber is 900°C; the high-pressure wind does not throw all the materials on the bed into the air for fluidized combustion like a fluidized bed, but only penetrates the fire bed and fuel, and only throws the unburned ash, small-particle carbon and small-sized biomass fuel on the fire bed into the air for fluidized combustion.

2. The low calorific value biomass semi-fluidized bed composite grate combustion furnace according to claim 1, characterized in that: The ash pushing plate is a rectangular parallelepiped, and a water cooling pipe is arranged inside the rectangular parallelepiped.

3. The low calorific value biomass semi-fluidized bed composite grate combustion furnace according to claim 1, characterized in that: The slag grate is a chain grate, a reciprocating grate or a water-cooled grate.

4. The low calorific value biomass semi-fluidized bed composite grate combustion furnace according to claim 1, characterized in that: The low calorific value biomass material is corn stalks, fruit tree prunings, edible fungus waste or furfural residue.

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