阅读说明：本技术 一种解耦燃烧机械炉排炉及其燃烧方法 (Decoupling combustion mechanical grate furnace and combustion method thereof ) 是由 郝江平 刘新华 高士秋 张楠 韩健 于 2020-05-28 设计创作，主要内容包括：本发明提供了一种解耦燃烧机械炉排炉及其燃烧方法,所述机械炉排炉包括预燃装置和主炉体,所述主炉体包括主炉排、顶拱、后墙以及炉膛,所述后墙上设有后拱；所述主炉排上方沿运动方向依次设有第一、第二下隔墙；下隔墙上独立地设有调节风管；所述顶拱上沿气体流动方向依次设有第一、第二上隔墙,将下隔墙上方区域对应划分为气化燃烧区、过渡燃烧区和燃尽区。本发明通过将主炉体划分为不同燃烧区,设置不同隔墙与调节风,提高了炉膛内煤气、烟气与调节风的混合效果,使炉膛形成的还原性燃烧区更为稳定,组分更易控制,精确控制还原性气氛向氧化性气氛的过渡,减小燃尽区NO-(x)浓度的反弹,改善分区燃烧效果,实现低NO-(x)排放和更高的燃烧效率。(The invention provides a decoupling combustion mechanical grate furnace and a combustion method thereof, wherein the mechanical grate furnace comprises a pre-combustion device and a main furnace body, the main furnace body comprises a main grate, a top arch, a rear wall and a hearth, and the rear wall is provided with a rear arch; a first lower partition wall and a second lower partition wall are sequentially arranged above the main grate along the movement direction; the lower partition wall is independently provided with an adjusting air pipe; the top arch is sequentially provided with a first upper partition wall and a second upper partition wall along the gas flowing direction, and the upper area of the lower partition wall is correspondingly divided into a gasification combustion area, a transition combustion area and a burnout area. According to the invention, the main furnace body is divided into different combustion areas, and different partition walls and adjusting air are arranged, so that the mixing effect of coal gas, flue gas and adjusting air in the hearth is improved, the reductive combustion area formed in the hearth is more stable, the components are easier to control, the transition from the reductive atmosphere to the oxidative atmosphere is accurately controlled, and the NO of the burnout area is reduced x Rebound of concentration, improved combustion effect in different zones and low NO x Emissions and higher combustion efficiency.)

1. A decoupling combustion mechanical grate furnace is characterized in that the mechanical grate furnace comprises a pre-combustion device and a main furnace body, wherein an outlet of the pre-combustion device is connected with an inlet of the main furnace body; the main furnace body comprises a main fire grate, a top arch, a rear wall and a hearth surrounded by the main fire grate, the top arch and the rear wall, the pre-burning device is positioned above the front part of the main fire grate, the top arch is positioned above the main fire grate, the rear wall is positioned above the rear part of the main fire grate, a slag discharge port is arranged between the lower part of the rear wall and the rear part of the main fire grate, and a flue gas outlet is arranged between the upper part of the rear wall and the rear part of the top arch;

the rear wall is provided with a rear arch extending inwards the hearth, the rear part of the hearth is divided into an upper part and a lower part by the rear arch, and a slag discharge port and a flue gas outlet are separated; a first lower partition wall and a second lower partition wall are sequentially arranged above the main grate along the movement direction of the main grate, the area between the lower partition wall and the main grate is a fuel channel, and the area between the lower partition wall and the crown is a gas channel; the first lower partition wall and the second lower partition wall are independently provided with adjusting air pipes;

the crown arch is provided with a first upper partition wall and a second upper partition wall which extend to the hearth in sequence along the gas flowing direction, the upper region of the lower partition wall is correspondingly divided into a gasification combustion region, a transition combustion region and a burnout region, the transverse position of the first upper partition wall is positioned between the first lower partition wall and the second lower partition wall, and the transverse position of the second upper partition wall is positioned at the rear of the second lower partition wall.

2. The mechanical grate furnace of claim 1 wherein the forward section of the crown arch is connected to an upper portion of a precombustor means;

preferably, the first lower partition wall is arranged above the front end of the main fire grate, and an adjusting gate plate is arranged on the first lower partition wall;

preferably, the distance from the bottom of the first lower partition wall to the main grate is greater than the distance from the second lower partition wall to the main grate;

preferably, the distance between the first lower partition wall and the second lower partition wall is 50-75% of the length of the main grate.

3. The mechanical grate furnace of claim 1 or 2, wherein a first adjusting air pipe is arranged at the upper part of the first lower partition wall, and at least one first adjusting air spray pipe is connected to the first adjusting air pipe;

preferably, a second adjusting air pipe is arranged at the upper part of the second lower partition wall, and the second adjusting air pipe is connected with at least one second adjusting air spray pipe.

4. The mechanical grate furnace of any of claims 1 to 3, wherein the distance from the bottom of the first upper partition wall to the main grate is 1/3 to 2/3 of the distance from the crown to the main grate;

preferably, the distance from the bottom of the second upper partition wall to the main grate is 1/2-4/5 of the distance from the top arch to the main grate.

5. The mechanical grate furnace of any of claims 1 to 4 wherein a gasification combustion zone plenum is provided below the primary grate in a region corresponding to between the first lower partition and the second lower partition;

preferably, an air chamber of a burnout area is arranged in an area below the main grate and corresponding to the rear part of the second lower partition wall;

preferably, the burnout zone is provided with a burnout air nozzle, and the burnout air nozzle is arranged at the lower part of the crown arch, the front end of the rear arch or the side wall of the hearth.

6. A method of decoupled combustion using a mechanical grate furnace according to any of claims 1-5, characterized in that the method comprises the steps of:

(1) pre-burning the solid fuel, and pyrolyzing and gasifying the solid fuel to generate semicoke and pyrolysis and gasification coal gas;

(2) the semicoke generated in the step (1) enters the main grate and then moves along with the main grate to generate gasification combustion reaction; the pyrolysis gasification coal gas generated in the step (1) enters a gasification combustion zone, and is mixed with coal gas generated by semicoke gasification combustion to perform reductive combustion;

(3) the flue gas generated by the reductive combustion in the step (2) enters a transitional combustion zone and is mixed and combusted with coal gas generated at the rear part of a gasification combustion zone under the ventilation condition; after the semicoke passes through the second lower partition wall, fully burning the semicoke under the action of gas to obtain solid slag;

(4) and (4) fully burning the flue gas generated after the mixed combustion in the step (3) under the action of excess air, and then, leaving through a flue gas outlet.

7. The method of claim 6, wherein the solid fuel of step (1) comprises coal and/or biomass;

preferably, the pre-combustion of step (1) is carried out in a pre-combustion device;

preferably, the pre-combustion device combusts in a downward ignition mode.

8. The method of claim 6 or 7, wherein air is introduced from an air chamber of a gasification combustion zone during the semi-coke gasification combustion process of step (2);

preferably, a mixed gas consisting of air and circulating flue gas is introduced into the gasification combustion zone in the step (2);

preferably, the mixed gas is introduced through a first adjusting air pipe;

preferably, NO is generated in the reductive combustion process in the step (2)_xIs reduced to N₂；

Preferably, the excess air coefficient of the gasification combustion zone in the step (2) is 0.6-0.95.

9. The method according to any one of claims 6 to 8, wherein a mixed gas consisting of air and circulating flue gas is introduced into the transitional combustion zone in the step (3);

preferably, the mixed gas is introduced through a second adjusting air pipe;

preferably, the excess air coefficient of the transition combustion zone in the step (3) is 0.85-1.1;

preferably, the thickness of the semicoke after passing through the second lower partition wall in the step (3) is less than that of the semicoke in front of the second lower partition wall;

preferably, air is introduced from the air chamber of the burnout zone in the semi-coke burnout process in the step (3).

10. The method according to any one of claims 6 to 9, wherein the air in step (4) is introduced through a burnout zone nozzle;

preferably, the excess air coefficient of the burnout zone in the step (4) is 1.05-2.

Technical Field

The invention belongs to the technical field of combustion equipment, and relates to a decoupling combustion mechanical grate furnace and a combustion method thereof.

Background

The traditional coal-fired industrial boiler mainly adopts a layer combustion mode and is mostly a chain boiler, the problems of low combustion efficiency, high pollutant discharge amount and the like generally exist, and therefore, related emission reduction technologies need to be researched and developed to reduce NO_xThe discharge amount of the coal-fired boiler is limited by the structure and the operation mode of the coal-fired boiler, such as a low-oxygen combustion technology, a flue gas recirculation combustion technology, an air separation and combustion technology and the like, so that the combustion equipment needs to be improved while the combustion technology is improved, and the advantages of the novel combustion technology are fully exerted.

The traditional mechanical fire grate furnace is a common coal-fired boiler, and adopts an ignition mode that a hearth radiates and heats the upper part of a fuel layer, the outlet area of a high-temperature and high-oxygen hearth must be close to a fuel ignition area, the fuel conveying direction on the fire grate is opposite to the flow direction of flue gas in the hearth in a main combustion area of the hearth, so that the reduction area at the initial stage of combustion cannot be effectively realized, the subarea or staged combustion at the later stage of combustion is an oxidation area, and the deep reduction of NO cannot be realized_xDischarging of (3); the recirculated flue gas of the mechanical grate furnace is mixed with air and introduced into the lower part of the grate so as to reduce NO by reducing the oxygen content in the air_xBut this significantly reduces the ignition and burn-out rate of the fuel, thereby requiring a significant increase in grate length and furnace volume.

CN 101650025A discloses a decoupling combustion furnace and a decoupling combustion method, comprising a pyrolysis gasification chamber, and a semicoke combustion zone, a coke combustion zone and a burnout zone which are sequentially arranged below the pyrolysis gasification chamber, the decoupling combustion furnace further comprises a secondary combustion zone, at least one grate, a first air port and a second air port, wherein the grate pushes fuel to move to sequentially pass through the pyrolysis gasification chamber, the semicoke combustion zone, the coke combustion zone and the burnout zone, the lower part of the secondary combustion zone is in fluid communication with the upper part of the pyrolysis gasification chamber, the coke zone and the burnout zone to form a gas channel, the first air port is arranged in the gas channel, and the second air port is arranged in the secondary combustion zone and is used for supplementing air; although the device can solve the problem of slow pyrolysis speed to a large extent, the device shares one set of fire grate, and precombustion speed is slow, when the load improves, easily causes the precombustion area to burn and breaks off, is difficult to be applicable to large-scale combustion equipment.

CN 102563614A discloses a precombustion type mechanical grate decoupling combustion furnace and a combustion method thereof, comprising a furnace body, a main grate and a precombustion grate, wherein a combustion chamber partition wall is arranged in the furnace body and divides the internal space of the furnace body into an upstream precombustion chamber and a downstream main combustion chamber, the main grate is positioned at the lower part of the furnace body, the precombustion chamber is positioned above the front section of the main grate, the main combustion chamber is positioned above the rear section of the main grate, the precombustion chamber and the main combustion chamber are communicated through a flue gas channel above the partition wall and a coal bed channel below the partition wall, the precombustion grate is positioned in the precombustion chamber and is arranged above the main grate at a certain inclination angle so as to enable the coal bed to run onto the main grate along the precombustion grate; the device mainly improves the combustion efficiency of fire coal by arranging the precombustion chamber and the precombustion grate, but the reduction zone and the oxidation zone of combustion are not clearly divided, so that the problem of poor combustion effect still exists.

In summary, for the decoupling combustion of mechanical grate furnace, the improvement of the device is needed to clarify the division and component control of the reduction zone and the oxidation zone, so as to improve the effect of staged combustion and reduce NO_xAnd (4) discharging.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a decoupling combustion mechanical grate furnace and a combustion method thereof, wherein the mechanical grate furnace can effectively improve the diffusion mixing effect of flue gas, coal gas and adjusting air during fuel combustion through the arrangement of a combustion device and a main furnace body, particularly the arrangement of different combustion areas and partition walls in the main furnace body, control the stability of different combustion areas in a hearth and the transition of combustion atmosphere, and realize the deep staged combustion of the mechanical grate furnace.

In order to achieve the purpose, the invention adopts the following technical scheme:

in one aspect, the invention provides a decoupling combustion mechanical grate furnace, which comprises a pre-combustion device and a main furnace body, wherein an outlet of the pre-combustion device is connected with an inlet of the main furnace body; the main furnace body comprises a main fire grate, a top arch, a rear wall and a hearth surrounded by the main fire grate, the top arch and the rear wall, the pre-burning device is positioned above the front part of the main fire grate, the top arch is positioned above the main fire grate, the rear wall is positioned above the rear part of the main fire grate, a slag discharge port is arranged between the lower part of the rear wall and the rear part of the main fire grate, and a flue gas outlet is arranged between the upper part of the rear wall and the rear part of the top arch;

the rear wall is provided with a rear arch extending inwards the hearth, the rear part of the hearth is divided into an upper part and a lower part by the rear arch, and a slag discharge port and a flue gas outlet are separated; a first lower partition wall and a second lower partition wall are sequentially arranged above the main grate along the movement direction of the main grate, the area between the lower partition wall and the main grate is a fuel channel, and the area between the lower partition wall and the crown is a gas channel; the first lower partition wall and the second lower partition wall are independently provided with adjusting air pipes;

the crown arch is provided with a first upper partition wall and a second upper partition wall which extend to the hearth in sequence along the gas flowing direction, the upper region of the lower partition wall is correspondingly divided into a gasification combustion region, a transition combustion region and a burnout region, the transverse position of the first upper partition wall is positioned between the first lower partition wall and the second lower partition wall, and the transverse position of the second upper partition wall is positioned at the rear of the second lower partition wall.

According to the mechanical grate furnace, the structural design of the mechanical grate furnace is that the preliminary pyrolysis gasification of fuel is carried out by a pre-combustion device firstly, so that the fuel can start to burn at the front end of the grate, then a gas area in a main furnace body is divided into a gasification combustion area, a transition combustion area and a burnout area, then the atmosphere composition of different combustion areas is controlled through the design of different partition walls and adjusting air pipes, the diffusion mixing effect of gas, smoke and adjusting air is improved, the large-range reductive combustion area formed by a hearth is more stable in the main fuel nitrogen conversion stage, the transition of the reductive atmosphere to the oxidative atmosphere is accurately controlled, and the NO (nitric oxide) of the burnout area is reduced_xConcentration rebounding makes the zoned combustion effect more prominent.

The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.

In a preferred embodiment of the present invention, the front section of the crown is connected to an upper part of the precombustion device.

Preferably, the first lower partition wall is arranged above the front end of the main fire grate, and the first lower partition wall is provided with an adjusting gate plate.

Preferably, the distance from the bottom of the first lower partition wall to the main grate is greater than the distance from the second lower partition wall to the main grate.

In the invention, the arrangement of the adjusting flashboard on the first lower partition wall can effectively adjust the thickness of the semicoke fuel layer on the main fire grate, and ensure that the gasification combustion is carried out under proper conditions when the fuel layer reacts with air introduced from the lower part, so that the gasification combustion can be carried out on the lower part of the fuel layer to generate CO₂And the upper part of the fuel layer is gasified to generate CO.

And the distance between the second lower partition wall and the main grate is controlled, so that the thickness of a semicoke material layer entering the rear grate can be adjusted, the semicoke can be completely burnt, and excessive air passes through the semicoke layer.

Preferably, the distance between the first lower partition wall and the second lower partition wall is 50-75% of the length of the main grate, such as 50%, 55%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, etc., but not limited to the recited values, and other values not recited in the range of the values are also applicable.

As a preferable technical solution of the present invention, a first adjusting air duct is provided at an upper portion of the first lower partition wall, and the first adjusting air duct is connected to at least one first adjusting air nozzle, for example, one, two, three, or four first adjusting air nozzles.

Preferably, a second adjusting air pipe is arranged at the upper part of the second lower partition wall, and the second adjusting air pipe is connected with at least one second adjusting air spray pipe, such as one, two, three or four second adjusting air spray pipes.

According to the invention, a first adjusting air pipe is arranged on a first lower partition wall, adjusting air can be injected into a gasification combustion zone through a first adjusting air nozzle, and the reducibility of components is adjusted by adjusting the components of coal gas in a reduction zone and combustion; the angle of the first adjusting air spray pipe can be changed, so that the mixing position and the component distribution of the adjusting air and the coal gas in the gasification combustion area are changed.

Similarly, the regulating air is sprayed into the transition combustion zone through the second regulating air spray pipe, the transition from the reducing atmosphere to the oxidizing atmosphere is regulated by regulating the oxygen supply and combustion, and the NO of the burnout zone is reduced_xRebound of concentration; the angle of the second adjusting air spray pipe can be changed, so that the air flow mixing position and the component distribution of the adjusting air and the gasified coal gas flowing into the transition combustion zone from the gasification combustion zone are changed.

In a preferred embodiment of the present invention, the distance from the bottom of the first upper partition to the main grate is 1/3 to 2/3, for example, 1/3, 2/5, 1/2, 3/5, 2/3, which are the distances from the crown to the main grate.

Preferably, the distance from the bottom of the second upper partition wall to the main grate is 1/2-4/5 of the distance from the top arch to the main grate, such as 1/2, 3/5, 2/3, 7/10, 3/4 or 4/5, but the distance is not limited to the recited values, and other values not recited in the range of the values are also applicable.

According to the invention, the arrangement of the first upper partition wall and the second upper partition wall is beneficial to the division of a gas combustion area and the mixing of gas, and the distance between the first upper partition wall and the fire grate is smaller than that between the second upper partition wall and the fire grate, so that the characteristics of small front and large back of the smoke volume of the smoke discharged from the rear of the hearth can be adapted to maintain the optimal flow rate and pressure drop of the smoke in the hearth.

As a preferable technical scheme of the invention, an air chamber of a gasification combustion area is arranged below the main grate and corresponds to the area between the first lower partition wall and the second lower partition wall.

Preferably, an air chamber of a burnout zone is arranged in an area below the main grate and corresponding to the rear part of the second lower partition wall.

In the invention, the air chamber is arranged below the main grate, air required by gasification combustion or burnout can be provided for the semicoke on the main grate, and the air quantity is adjusted according to the combustion conditions of different stages; the number of the gasification combustion area air chambers and the number of the burnout area air chambers can be multiple, so that the air inlet amount of different areas on the main grate can be adjusted according to the burning condition of the semicoke.

Preferably, the burnout zone is provided with a burnout air nozzle, and the burnout air nozzle is arranged at the lower part of the crown arch, the front end of the rear arch or the side wall of the hearth.

In the invention, in order to fully burn the fuel and the flue gas in the burnout zone, a burnout air nozzle can be additionally arranged to maintain the excess air in the burnout zone.

In another aspect, the present invention provides a method for decoupled combustion using the above mechanical grate furnace, the method comprising the steps of:

(1) pre-burning the solid fuel, and pyrolyzing and gasifying the solid fuel to generate semicoke and pyrolysis and gasification coal gas;

(2) the semicoke generated in the step (1) enters the main grate and then moves along with the main grate to generate gasification combustion reaction; the pyrolysis gasification coal gas generated in the step (1) enters a gasification combustion zone, and is mixed with coal gas generated by semicoke gasification combustion to perform reductive combustion;

(3) the flue gas generated by the reductive combustion in the step (2) enters a transitional combustion zone and is mixed and combusted with coal gas generated at the rear part of a gasification combustion zone under the ventilation condition; after the semicoke passes through the second lower partition wall, fully burning the semicoke under the action of gas to obtain solid slag;

(4) and (4) fully burning the flue gas generated after the mixed combustion in the step (3) under the action of excess air, and then, leaving through a flue gas outlet.

As a preferred technical scheme of the invention, the solid fuel in the step (1) comprises coal and/or biomass.

Preferably, the pre-combustion of step (1) is performed in a pre-combustion device.

Preferably, the pre-combustion device combusts in a downward ignition mode.

According to the invention, the fuel is pre-combusted, so that preliminary pyrolysis gasification can be realized, the fuel can start to combust at the front end of the grate, a preheating ignition section on the grate is eliminated, and the utilization rate of the grate is improved; the temperature at which the fuel is preliminarily combusted is 500 to 1000 ℃, for example, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃ or 1000 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

As a preferable technical scheme of the invention, air is introduced from an air chamber of a gasification combustion area in the semi-coke gasification combustion process in the step (2).

In the invention, semicoke on the fire grate between the first lower partition wall and the second lower partition wall is gasified and combusted, the nitrogen content of the fuel is higher in the stage, the air introduction amount is controlled to ensure that the fuel is subjected to oxygen-deficient combustion, the content of generated CO is higher, and a higher reducing atmosphere is maintained to reduce the nitrogen of the fuel to NO_xThe transformation of (3); and on the rear part of the fire grate, the nitrogen content of the fuel is less, and at the moment, excessive air needs to be introduced to accelerate the complete combustion of the semicoke.

The gasification combustion mode is adopted, so that the thickness of a fuel layer which can be processed can be increased, the space chamber combustion proportion is increased, the burn-out speed of later-stage fuel is improved, and the length of a fire grate and the volume of a hearth can be reduced; a thicker fuel layer is adopted in the reduction zone, more coal gas is generated, and the stability of the atmosphere of the reduction zone of the mechanical grate furnace zoned combustion can be improved; moreover, the fuel gasification combustion is adopted, so that the adaptability of the fuel is improved, the requirements on the fuel components and the size specification of irregular fuel are reduced, and the performance of combusting biomass and garbage can be improved; the biomass volatile content is high, the main pollutants of the garbage are also in the volatile content, and smoke is discharged from the rear part of the hearth, so that the retention time of the volatile content in the high-temperature hearth can be obviously prolonged, and the burnout of the volatile matter is facilitated.

Preferably, a mixed gas consisting of air and circulating flue gas is introduced into the gasification combustion zone in the step (2).

Preferably, the mixed gas is introduced through a first adjusting air pipe.

In the invention, the mixed gas of combustion-supporting air and circulating flue gas is introduced from the adjusting air pipe, wherein the proportion of the air and the circulating flue gas can be adjusted, and the rigidity of the adjusting air can be kept when the oxygen demand is small or oxygen supplementation is not needed by changing the proportion of the air and the flue gas of the adjusting air, so that the turbulent mixing effect of the adjusting air on the air flow is realized; meanwhile, the reducing atmosphere in different areas can be more accurately adjusted by changing the incident angle of the adjusting wind; the uniformity of reducing atmosphere can be improved by mixing a proper amount of circulating flue gas with the adjusting air, so that local peroxide is avoided; the invention changes the traditional smoke recycling mode, not only can ensure the burnout speed and the burnout rate of the fuel, but also reduces the smoke recycling amount and the energy consumption increased thereby.

In the invention, the first adjusting air pipe is filled with the mixed gas, the combustion-supporting air accounts for 0-10% of the total air amount entering the hearth, and the circulating flue gas accounts for 0-10% of the total air amount entering the hearth.

Preferably, NO is generated in the reductive combustion process in the step (2)_xIs reduced to N₂。

Preferably, the gasification combustion zone of step (2) has an excess air ratio of 0.6 to 0.95, such as 0.6, 0.65, 0.7, 0.75, 0.8, 0.9, or 0.95, but not limited to the recited values, and other values not recited in this range are equally applicable.

In the present invention, the combustion temperature in the gasification combustion zone is 700 to 1100 ℃, for example 700 ℃, 800 ℃, 900 ℃, 1000 ℃ or 1100 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

As a preferable technical scheme of the invention, mixed gas consisting of air and circulating flue gas is introduced into the transitional combustion zone in the step (3).

Preferably, the mixed gas is introduced through a second adjusting air pipe.

According to the invention, the second adjusting air pipe is arranged, and the mixed gas of the combustion-supporting air and the circulating flue gas is sprayed, so that the transition from the reducing atmosphere to the oxidizing atmosphere can be accurately controlled and controlled under the action of factors such as the proportion of the combustion-supporting air and the circulating flue gas, the problem that the gasification combustion area and the burnout area are not obvious and the respective combustion effect is influenced is solved.

In the invention, the second adjusting air pipe is filled with the mixed gas, the combustion-supporting air accounts for 0-15% of the total air entering the hearth, and the circulating flue gas accounts for 0-15% of the total air entering the hearth.

Preferably, the excess air ratio in the transitional combustion zone of step (3) is 0.85 to 1.1, such as 0.85, 0.9, 0.95, 1.0, 1.05, or 1.1, but not limited to the recited values, and other unrecited values within the range are equally applicable.

In the present invention, the combustion temperature of the transition combustion zone is 800 to 1200 ℃, for example 800 ℃, 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃ or 1200 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the thickness of the semicoke after the second lower partition wall is passed through in step (3) is smaller than that of the semicoke in front of the second lower partition wall.

According to the invention, the material layer thickness of the main grate is different according to the difference of front and back combustion reactions on the main grate, and the material layer thickness between the first lower partition wall and the second lower partition wall is required to be larger than the material layer thickness behind the second lower partition wall according to requirements; overall, as the semicoke burns, the semicoke thickness generally decreases progressively along the direction of travel of the main grate.

Preferably, air is introduced from the air chamber of the burnout zone in the semi-coke burnout process in the step (3).

As a preferable technical scheme of the invention, the air in the step (4) is introduced from a nozzle of the burnout zone.

Preferably, the air excess factor of the burnout zone in step (4) is 1.05-2, such as 1.05, 1.1, 1.2, 1.4, 1.5, 1.6, 1.8, or 2, but not limited to the recited values, and other values not recited in this range are also applicable.

In the present invention, the combustion temperature of the burnout zone is 1000 to 1400 ℃, for example, 1000 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, 1300 ℃, 1350 ℃ or 1400 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Compared with the prior art, the invention has the following beneficial effects:

(1) the pre-combustion device is used for carrying out preliminary pyrolysis and gasification of the fuel, so that the fuel can start to combust at the front end of the fire grate, and the fuel flow direction of the main combustion area of the mechanical fire grate furnace is consistent with the flow direction of the flue gas;

(2) the main furnace body of the mechanical grate furnace is divided into different combustion areas, and different partition walls and adjusting air are arranged, so that the diffusion and mixing effects of coal gas, smoke and adjusting air in the furnace hearth are improved, a large-range reductive combustion area formed by the furnace hearth is more stable in the main conversion stage of fuel nitrogen, the components are easier to control, the transition from the reductive atmosphere to the oxidative atmosphere is accurately controlled, and the NO in a burnout area is reduced_xThe rebound of concentration realizes the staged and zoned combustion of the fuel, and the combustion efficiency can reach more than 90 percent;

(3) the design of the mechanical grate furnace improves the utilization rate and the combustion efficiency of the grate, enhances the fuel adaptability and reduces the smoke gas recirculation quantity and the energy consumption.

Drawings

FIG. 1 is a schematic structural diagram of a decoupled-combustion mechanical grate furnace provided in embodiment 1 of the present invention;

the device comprises a pre-combustion device 1, a first lower partition wall 2, a first adjusting air pipe 3, a first adjusting air spray pipe 4, a main fire grate 5, a crown 6, a gasification combustion zone air chamber 7, a gasification combustion zone 8, a first upper partition wall 9, a second lower partition wall 10, a second adjusting air pipe 11, a second adjusting air spray pipe 12, a transition combustion zone 13, a second upper partition wall 14, a burnout zone air chamber 15, a rear arch 16, a burnout zone 17, a flue gas outlet 18, a slag discharge port 19 and a rear wall 20.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.

The following are typical but non-limiting examples of the invention:

example 1:

the embodiment provides a decoupling combustion mechanical grate furnace, the structural schematic diagram of the mechanical grate furnace is shown in fig. 1, and the mechanical grate furnace comprises a pre-combustion device 1 and a main furnace body, wherein an outlet of the pre-combustion device 1 is connected with an inlet of the main furnace body; the main furnace body comprises a main furnace grate 5, a top arch 6, a rear wall 20 and a hearth surrounded by the main furnace grate 5, the top arch 6 and the rear wall 20, the pre-combustion device 1 is positioned above the front part of the main furnace grate 5, the top arch 6 is positioned above the main furnace grate 5, the front section of the top arch 6 is connected with the upper part of the pre-combustion device 1, the rear wall 20 is positioned above the rear part of the main furnace grate 5, a slag discharge port 19 is arranged between the lower part of the rear wall 20 and the rear part of the main furnace grate 5, and a flue gas outlet 18 is arranged between the upper part of the rear wall 20 and the rear part of the top arch 6;

the rear wall 20 is provided with a rear arch 16 extending inwards the hearth, the rear part of the hearth is divided into an upper part and a lower part by the rear arch 16, and a slag discharge port 19 is separated from a flue gas outlet 18; a first lower partition wall 2 and a second lower partition wall 10 are sequentially arranged above the main grate 5 along the movement direction of the main grate 5, the area between the lower partition wall and the main grate 5 is a fuel channel, and the area between the lower partition wall and the crown 6 is a gas channel; the first lower partition wall 2 and the second lower partition wall 10 are independently provided with adjusting air pipes;

the crown arch 6 is sequentially provided with a first upper partition wall 9 and a second upper partition wall 14 which extend towards the hearth along the gas flowing direction, the upper area of the lower partition wall is correspondingly divided into a gasification combustion area 8, a transition combustion area 13 and a burnout area 17, the transverse position of the first upper partition wall 9 is positioned between the first lower partition wall 2 and the second lower partition wall 10, and the transverse position of the second upper partition wall 14 is positioned behind the second lower partition wall 10.

The first lower partition wall 2 is arranged above the front end of the main fire grate 5, and an adjusting flashboard is arranged on the first lower partition wall 2; the distance from the bottom of the first lower partition wall 2 to the main grate 5 is greater than the distance from the second lower partition wall 10 to the main grate 5; the distance between the first lower partition wall 2 and the second lower partition wall 10 is 70% of the length of the main grate 5.

A first adjusting air pipe 3 is arranged at the upper part of the first lower partition wall 2, and the first adjusting air pipe 3 is connected with three first adjusting air spray pipes 4; and a second adjusting air pipe 11 is arranged at the upper part of the second lower partition wall 10, and the second adjusting air pipe 11 is connected with three second adjusting air spray pipes 12.

The distance from the bottom of the first upper partition wall 9 to the main grate 5 is 1/3 of the distance from the crown 6 to the main grate 5, and the distance from the bottom of the second upper partition wall 14 to the main grate 5 is 1/2 of the distance from the crown 6 to the main grate 5.

An air chamber 7 of a gasification combustion area is arranged in the area below the main grate 5 and corresponding to the space between the first lower partition wall 2 and the second lower partition wall 10; an air chamber 15 of a burnout zone is arranged in an area below the main grate 5 and corresponding to the rear part of the second lower partition wall 10.

The burnout zone 17 is provided with a burnout air nozzle which is arranged at the front end of the rear arch 16.

Example 2:

the embodiment provides a decoupling combustion mechanical grate furnace, which comprises a pre-combustion device 1 and a main furnace body, wherein an outlet of the pre-combustion device 1 is connected with an inlet of the main furnace body; the main furnace body comprises a main furnace grate 5, a top arch 6, a rear wall 20 and a hearth surrounded by the main furnace grate 5, the top arch 6 and the rear wall 20, the pre-combustion device 1 is positioned above the front part of the main furnace grate 5, the top arch 6 is positioned above the main furnace grate 5, the front section of the top arch 6 is connected with the upper part of the pre-combustion device 1, the rear wall 20 is positioned above the rear part of the main furnace grate 5, a slag discharge port 19 is arranged between the lower part of the rear wall 20 and the rear part of the main furnace grate 5, and a flue gas outlet 18 is arranged between the upper part of the rear wall 20 and the rear part of the top arch 6;

the rear wall 20 is provided with a rear arch 16 extending inwards the hearth, the rear part of the hearth is divided into an upper part and a lower part by the rear arch 16, and a slag discharge port 19 is separated from a flue gas outlet 18; a first lower partition wall 2 and a second lower partition wall 10 are sequentially arranged above the main grate 5 along the movement direction of the main grate 5, the area between the lower partition wall and the main grate 5 is a fuel channel, and the area between the lower partition wall and the crown 6 is a gas channel; the first lower partition wall 2 and the second lower partition wall 10 are independently provided with adjusting air pipes;

the crown arch 6 is sequentially provided with a first upper partition wall 9 and a second upper partition wall 14 which extend towards the hearth along the gas flowing direction, the upper area of the lower partition wall is correspondingly divided into a gasification combustion area 8, a transition combustion area 13 and a burnout area 17, the transverse position of the first upper partition wall 9 is positioned between the first lower partition wall 2 and the second lower partition wall 10, and the transverse position of the second upper partition wall 14 is positioned behind the second lower partition wall 10.

The first lower partition wall 2 is arranged above the front end of the main fire grate 5, and an adjusting flashboard is arranged on the first lower partition wall 2; the distance from the bottom of the first lower partition wall 2 to the main grate 5 is greater than the distance from the second lower partition wall 10 to the main grate 5; the distance between the first lower partition wall 2 and the second lower partition wall 10 is 50% of the length of the main grate 5.

A first adjusting air pipe 3 is arranged at the upper part of the first lower partition wall 2, and the first adjusting air pipe 3 is connected with a first adjusting air spray pipe 4; and a second adjusting air pipe 11 is arranged at the upper part of the second lower partition wall 10, and the second adjusting air pipe 11 is connected with two second adjusting air spray pipes 12.

The distance from the bottom of the first upper partition wall 9 to the main grate 5 is 2/3 of the distance from the crown 6 to the main grate 5, and the distance from the bottom of the second upper partition wall 14 to the main grate 5 is 4/5 of the distance from the crown 6 to the main grate 5.

An air chamber 7 of a gasification combustion area is arranged in the area below the main grate 5 and corresponding to the space between the first lower partition wall 2 and the second lower partition wall 10; an air chamber 15 of a burnout zone is arranged in an area below the main grate 5 and corresponding to the rear part of the second lower partition wall 10.

The burnout zone 17 is provided with a burnout air nozzle which is arranged at the lower part of the crown 6.

Example 3:

the present embodiment provides a combustion method of a decoupled-combustion mechanical grate furnace, which is performed in the mechanical grate furnace of embodiment 1, and includes the following steps:

(1) the biomass fuel enters the pre-burning device 1 for pre-burning, the pre-burning temperature is 600 ℃, and the pyrolysis gasification generates semi-coke and pyrolysis gasification coal gas;

(2) the semicoke generated in the step (1) enters the main grate 5 and then moves along with the main grate 5 to generate gasification combustion reaction, and air is introduced from an air chamber 7 of a gasification combustion area in the gasification combustion process of the semicoke; the pyrolysis gasification coal gas generated in the step (1) enters a gasification combustion zone 8, and is mixed with coal gas generated by semicoke gasification combustion for reductive combustion, the combustion temperature is 900 ℃, mixed gas consisting of air and circulating flue gas is introduced into the gasification combustion zone 8, the excess air coefficient is 0.8, and NO in the reductive combustion process_xIs reduced to N₂；

(3) The flue gas generated by the reductive combustion in the step (2) enters a transition combustion zone 13, and is mixed and combusted with the coal gas generated at the rear part of the gasification combustion zone 8 under the ventilation condition, the combustion temperature is 1000 ℃, the transition combustion zone 13 is introduced with mixed gas consisting of air and circulating flue gas, and the excess air coefficient is 1.0; after the semicoke passes through the second lower partition wall 10, fully burning the semicoke under the action of air introduced into an air chamber 15 of a burnout area to obtain solid slag, and discharging the solid slag from a slag discharge port 19;

(4) and (4) fully burning the flue gas generated after the mixed combustion in the step (3) under the action of excess air introduced from a nozzle of a burnout zone, wherein the burnout temperature is 1200 ℃, and the excess air coefficient is 1.5, and then, the flue gas leaves through a flue gas outlet 18.

In the embodiment, the mechanical grate furnace is adopted for decoupling combustion of the biomass fuel, the combustion efficiency can reach 92%, and NO in flue gas_xThe content meets the emission requirement, and no additional treatment is needed.

Example 4:

the present embodiment provides a combustion method of a decoupled-combustion mechanical grate furnace, which is performed in the mechanical grate furnace of embodiment 1, and includes the following steps:

(1) the pulverized coal fuel enters the pre-combustion device 1 for pre-combustion, the pre-combustion temperature is 800 ℃, and the pulverized coal fuel is pyrolyzed and gasified to generate semi-coke and pyrolyzed and gasified coal gas;

(2) the semicoke generated in the step (1) enters the main grate 5 and then moves along with the main grate 5 to generate gasification combustion reaction, and air is introduced from an air chamber 7 of a gasification combustion area in the gasification combustion process of the semicoke; the pyrolysis gasification coal gas generated in the step (1) enters a gasification combustion zone 8, and is mixed with coal gas generated by semicoke gasification combustion for reductive combustion, the combustion temperature is 1100 ℃, mixed gas consisting of air and circulating flue gas is introduced into the gasification combustion zone 8, the excess air coefficient is 0.6, and NO in the reductive combustion process_xIs reduced to N₂；

(3) The flue gas generated by the reductive combustion in the step (2) enters a transition combustion zone 13, and is mixed and combusted with the coal gas generated at the rear part of the gasification combustion zone 8 under the ventilation condition, the combustion temperature is 1200 ℃, the transition combustion zone 13 is introduced with mixed gas consisting of air and circulating flue gas, and the excess air coefficient is 0.85; after the semicoke passes through the second lower partition wall 10, fully burning the semicoke under the action of air introduced into an air chamber 15 of a burnout area to obtain solid slag, and discharging the solid slag from a slag discharge port 19;

(4) and (4) fully burning the flue gas generated after the mixed combustion in the step (3) under the action of excess air introduced from a nozzle of a burnout zone, wherein the burnout temperature is 1400 ℃, and the excess air coefficient is 1.8, and then, the flue gas leaves through a flue gas outlet 18.

In the embodiment, the mechanical grate furnace is adopted for decoupling combustion of pulverized coal fuel, the combustion efficiency can reach 94%, and NO in flue gas_xThe content meets the emission requirement, and no additional treatment is needed.

Example 5:

the present embodiment provides a combustion method of a decoupled-combustion mechanical grate furnace, which is performed in the mechanical grate furnace of embodiment 2, and includes the following steps:

(1) the biomass fuel enters the pre-burning device 1 for pre-burning, the pre-burning temperature is 500 ℃, and the pyrolysis and gasification are carried out to generate semi-coke and pyrolysis and gasification coal gas;

(2) the semicoke generated in the step (1) enters the main grate 5 and then moves along with the main grate 5 to generate gasification combustion reaction, and air is introduced from an air chamber 7 of a gasification combustion area in the gasification combustion process of the semicoke; the pyrolysis gasification coal gas generated in the step (1) enters a gasification combustion zone 8, is mixed with coal gas generated by semicoke gasification combustion and then is subjected to reductive combustion, the combustion temperature is 800 ℃, mixed gas consisting of air and circulating flue gas is introduced into the gasification combustion zone 8, the excess air coefficient is 0.9, and NO is generated in the reductive combustion process_xIs reduced to N₂；

(3) The flue gas generated by the reductive combustion in the step (2) enters a transitional combustion zone 13, and is mixed and combusted with the coal gas generated at the rear part of the gasification combustion zone 8 under the ventilation condition, the combustion temperature is 800 ℃, the transitional combustion zone 13 is introduced with mixed gas consisting of air and circulating flue gas, and the excess air coefficient is 1.05; after the semicoke passes through the second lower partition wall 10, fully burning the semicoke under the action of air introduced into an air chamber 15 of a burnout area to obtain solid slag, and discharging the solid slag from a slag discharge port 19;

(4) and (4) fully burning the flue gas generated after the mixed combustion in the step (3) under the action of excess air introduced from a nozzle of a burnout zone, wherein the burnout temperature is 1100 ℃, and the excess air coefficient is 1.2, and then, the flue gas leaves through a flue gas outlet 18.

In the embodiment, the mechanical grate furnace is adopted for decoupling combustion of the biomass fuel, the combustion efficiency can reach 91%, and NO in flue gas_xThe content meets the emission requirement, and no additional treatment is needed.

Comparative example 1:

this comparative example provides a decoupled combustion mechanical grate furnace whose structure is as in example 1, the only difference being: a second lower partition wall 10 and an adjusting air pipe thereof are not arranged above the main grate, a second upper partition wall 14 is not arranged on the crown 6, and a transitional combustion area 13 is not included in the division of the area above the lower partition wall.

In the comparative example, the mechanical grate furnace is not provided with the transition combustion zone, so that the transition from the reducing atmosphere to the oxidizing atmosphere in the gas-phase combustion zone is difficult to ensure, the stability of the reducing atmosphere in the reducing combustion zone is poor, and NO is generated_xThe reduction efficiency is low, the concentration of NOx is easy to rebound under oxygen enrichment in a burnout zone, and NO in smoke gas_xThe content is relatively high, and the emission can not reach the standard.

It can be seen from the above examples and comparative examples that the mechanical grate furnace of the present invention uses the pre-combustion device to perform the preliminary pyrolysis gasification of the fuel, so that the fuel can start to combust at the front end of the grate; through dividing different combustion zones in the main furnace body, setting different partition walls and adjusting air, the diffusion mixing effect of coal gas, flue gas and adjusting air in the hearth is improved, the large-range reductive combustion zone formed by the hearth is more stable in the main conversion stage of fuel nitrogen, the components are more easily controlled, the transition of the reductive atmosphere to the oxidative atmosphere is accurately controlled, and the NO of a burnout zone is reduced_xThe rebound of concentration realizes the staged and zoned combustion of the fuel, and the combustion efficiency can reach more than 90 percent; the design of the mechanical grate furnace improves the utilization rate and the combustion efficiency of the grate, enhances the fuel adaptability, and reduces the smoke gas recirculation quantity and the energy consumption。

The applicant states that the present invention is illustrated by the detailed apparatus and method of the present invention through the above embodiments, but the present invention is not limited to the above detailed apparatus and method, i.e. it is not meant to imply that the present invention must be implemented by the above detailed apparatus and method. It will be apparent to those skilled in the art that any modifications to the present invention, equivalents of the means for substitution and addition of means for carrying out the invention, selection of specific means, etc., are within the scope and disclosure of the invention.