A composite combustion hearth and corresponding boiler

Abstract

The present invention relates to a composite combustion hearth and a corresponding boiler. The boiler hearth according to the present invention has a serpentine flue extending from bottom to top, and the serpentine flue is defined by a plurality of grates extending from the front wall and the rear wall of the hearth. The plurality of grates are arranged in sequence from top to bottom, and each grate extends alternately from the front wall and the rear wall of the hearth, and its tail end maintains a predetermined interval with the rear wall or the front wall of the hearth; each grate extends from the left wall of the hearth to the right wall of the hearth in the width direction, and ventilation holes are formed at the bottom of each grate. The hearth of the present invention combines the advantages of a layer-burning furnace, a chamber-burning furnace, and a circulating fluidized bed, has a wide adaptability to fuel, is easy to achieve low-temperature full combustion, and reduces sulfur and nitrogen oxide emissions. The present invention can also adapt to a wide range of load changes.

Description

Technical Field

[0001] The present invention relates to the field of combustion technology, and in particular to a composite combustion hearth and a corresponding boiler. Background Art

[0002] Currently, driven by energy conservation and emission reduction requirements, the combustion technologies commonly used in boilers fall into three main categories: First, layer-fired furnaces employing chain grates, reciprocating grates, and vibrating grates offer advantages in low investment and operating costs. However, they are incapable of burning low-quality fuels (e.g., they easily form coke when burning biomass fuels and can only burn high-calorific-value, high-quality fuels), have low thermal efficiency, and operate at high temperatures, resulting in high sulfur and nitrogen oxide emissions. Second, chamber-fired furnaces employing pulverized coal offer advantages in high combustion efficiency. However, they are subject to high energy consumption for initial fuel processing (due to the pulverization process), are flammable and explosive, emit high concentrations of smoke, and have high operating costs. Third, circulating fluidized beds employing repeated combustion offer advantages in that they can operate on both high- and low-quality fuels, have high combustion efficiency, and operate at low temperatures, effectively controlling sulfur and nitrogen oxide emissions. However, they are subject to high investment and operating costs, high energy consumption, and high concentrations of combustion dust. None of these combustion technologies and the corresponding boilers are suitable for fuels with a strong tendency to coke. In addition, the existing combustion technology can only adjust the combustion load slightly but cannot adjust the increase or decrease of the heating surface, resulting in the inability to synchronize and coordinate the combustion and heat exchange. Summary of the Invention

[0003] The present invention is dedicated to providing a boiler hearth that integrates the respective advantages of the three combustion technologies of layer combustion, chamber combustion and circulating fluidized bed, and minimizes the respective disadvantages of the three combustion technologies. It can widely adapt to various good and bad fuels including easily coked, garbage, and biomass fuels, and has high combustion efficiency and low pollutant emission concentration, and can significantly adjust the load of the combustion and heat exchange surfaces simultaneously.

[0004] The present invention also relates to a boiler comprising the boiler hearth.

[0005] According to one aspect of the present invention, a composite combustion furnace is provided, which has a serpentine flue extending from bottom to top, and the serpentine flue is defined by the front wall, rear wall, left wall, right wall of the furnace, and a plurality of grates extending from the front wall and rear wall of the furnace respectively, each grate having a head end connected to the front wall or rear wall of the furnace and a relative tail end, wherein the plurality of grates are arranged in sequence from top to bottom, and each grate extends alternately from the front wall and rear wall of the furnace toward the opposite rear wall and front wall of the furnace, and its tail end maintains a predetermined interval with the rear wall or front wall of the furnace; each grate extends from the left wall of the furnace to the right wall of the furnace in the width direction; adjacent grates are spaced from each other in the vertical direction so that there is a vertical distance between the tail end of each grate and the next grate, and each grate is configured to receive fuel from the upper grate adjacent to it, and a fuel supply device is arranged below the tail end of at least some of the plurality of grates, and the fuel supply device is used to supply fuel to be burned to the next grate.

[0006] The present invention uses a fire source grate to spread the ignited fuel to its downstream grate (which may be called the "first-stage grate") to form a "bottom fire". The tail end of the fire source grate may optionally be provided with a fuel supply device, which can spread the fuel to be burned (which may be called "raw meal") to cover the "bottom fire", thereby forming a composite fuel layer on the downstream grate (i.e., the "first-stage grate") with "ignition fuel at the bottom and fuel to be burned at the top". As a result, when the composite fuel layer moves downward along the grate, the fuel to be burned is supplied with oxygen to the burned "bottom fire" due to the high-temperature flue gas above and the air blowing from the ventilation holes of the grate below, and the high temperature is conducted upward, igniting the fuel to be burned to form "unlimited (or "unrestricted") combustion". It should be noted here that "unrestricted combustion" is also called "unlimited combustion", which means that when the direction of fuel ignition is consistent with the direction of oxygen supply and ventilation, the ignition conditions are unrestricted, forming a complete combustion state. Under the condition of "unrestricted combustion", inferior fuel can be burned at a low temperature.

[0007] Then, the composite fuel layer in the "infinite ignition / combustion" state on the first-stage grate slides down to its downstream grate (which may be called the "second-stage grate") at the tail end of the grate to form a "bottom fire". Subsequently, the "bottom fire" may be optionally covered by the fuel to be burned spread from the tail end of its upstream grate (i.e., the above-mentioned "first-stage grate"), thereby forming the aforementioned type of composite fuel layer, wherein when the composite fuel layer moves on the second grate, the fuel to be burned is also ignited and is in the "infinite ignition" state and burns fully, thereby providing the "bottom fire" to its downstream grate (which may be called the "third-stage grate"), ... repeating this combustion method, and finally discharging the slag to the burnout slag discharge grate. In the above-mentioned combustion process, the fuel runs from top to bottom and the smoke runs from bottom to top along a reciprocating "snake-like" path, the effect of which is:

[0008] 1. During the combustion process, the fuel state on each grate is roughly in an "unrestricted ignition" state with "bottom fire at the bottom, fuel to be burned at the top, and air entering from below". Therefore, the fuel has the conditions for complete combustion, making it easier to achieve continuous and complete combustion of the fuel at low temperature;

[0009] 2. There is a drop between the grates. When the fuel falls from the tail end of the grate to the downstream grate, it mixes with the upward high-temperature flue gas and burns in suspension, forming a "room combustion" furnace combustion state, which is conducive to full combustion;

[0010] 3. The fuel and combustible materials in the flue gas are repeatedly mixed in the "snake-like" curved path, so that the fuel is fully burned. It has the advantages of repeated combustion similar to that of a circulating fluidized bed, that is, the fuel burns fully and is easy to burn out, and the fuel compatibility is strong, and both good and bad fuels can be used. In addition, because the serpentine path has a long combustion path and each section is in an "unrestricted ignition" state, it can not only burn low-quality fuels, but also achieve low-temperature combustion, which helps to reduce sulfur and nitrogen oxide emissions.

[0011] 4. In addition, in the present invention, the surface of the fuel is coked by the high-temperature flue gas during its falling, suspended combustion process. This helps prevent the adhesion of fuel particles, thus preventing coking and agglomeration. Furthermore, because there is a height difference between the grates, the fuel "falls" onto the downstream grate. This "falling" process also breaks up the coke, thus promoting sufficient and sustained combustion of the fuel.

[0012] 5. In addition, the combustion chamber and flue of the present invention are both heating surfaces, making it easy to match the load with the heating surface. That is, for a given hearth, depending on the load, only some of the grates can be used to add fuel to be burned. For example, only the fuel supply device at the end of the fire source grate can be used to spread new fuel (i.e., fuel to be burned) to the first-stage grate, while the first-stage grate and subsequent grates no longer spread new fuel to be burned; or only the fire source grate and the fuel supply device at the end of the first-stage grate can be used to spread new fuel to be burned, while the second-stage grate and subsequent grates no longer spread new fuel to be burned... In other words, by selectively transporting fuel to the fire source and the number of downstream grates, the increase or decrease in combustion and heating surface can be significantly and relatively synchronously adjusted to achieve the effect of adjusting the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A non-limiting embodiment of a hearth according to the invention is schematically shown in elevation and in cross-section.

[0014] Figure 2 Schematically shows the Figure 1 View from the middle AA line.

[0015] Figure 3 Schematically shows the Figure 1View of the midline BB.

[0016] Figure 4 Schematically shows Figure 2 A solution when the inwardly protruding section is formed separately. DETAILED DESCRIPTION

[0017] Figure 1 : A vertical cutaway side view of a hearth of the present invention according to an exemplary embodiment of the present invention is shown in FIG. The hearth 1 has a serpentine flue s extending from top to bottom, and the serpentine flue s is defined by a hearth front wall 2, a hearth rear wall 4, a plurality of grates 9 extending from the hearth front and rear walls 2 and 4, and the hearth left and right side walls 7. Each grate has a head end 90 connected to the hearth front wall or rear wall and an opposite tail end 91. Each grate extends obliquely downward from the head end to the tail end to transport fuel downstream. The plurality of grates 9 are arranged in sequence from top to bottom and extend alternately from the hearth front wall 2 and the hearth rear wall 4 toward the opposite hearth rear wall 4 and the hearth front wall 2, respectively, with their tail ends 91 maintaining a spacing d from the opposite hearth rear wall 4 or the hearth front wall 2. Each grate extends from the left wall of the hearth to the right wall of the hearth in the width direction. Adjacent grates 9 are spaced apart from each other in the vertical direction so that the vertical distance between the tail end 91 of each grate and the next grate is h. Each grate 9 (which may be correspondingly referred to as the "second-stage grate", "third-stage grate", etc.) except the most upstream grate 9 (which may be referred to as the "first-stage grate") is configured to receive fuel from the grate 9 above it, the fuel including the ignited fuel b that slides down from the previous grate 9, and may also optionally include the fuel to be burned g that is scattered from below the tail end of the previous grate. Ventilation holes 16 are formed at the bottom of each grate (see Figure 2 ), used to blow air outwards.

[0018] Optionally, a fuel supply device 10 is arranged below the tail end of at least some of the multiple grates 9 , and the fuel supply device 10 is used to supply fuel g to be burned to the next grate 9 .

[0019] The hearth also includes a fire source grate 8 located at the top of the serpentine flue. This grate 8 is used to supply ignited fuel b as a fire source to the downstream grate 9 (i.e., the first-stage grate 9). The tail end of the fire source grate 8 maintains a predetermined horizontal distance from the corresponding furnace wall and a predetermined vertical distance from the first-stage grate 9 below. A fuel supply device 10 is also located below the tail end of the fire source grate 8 to supply fuel g to the grate 9 below.

[0020] According to the present invention, the ignition fuel b is spread from the fire source grate 8 to the downstream grate 9 (i.e., the first-stage grate) to form a "bottom fire." The fuel supply device 10 at the rear end of the fire source grate spreads the fuel g to be burned to cover the "bottom fire." This creates a composite fuel layer on the downstream grate (i.e., the "first-stage grate"), with the ignition fuel b at the bottom and the fuel g to be burned at the top. Furthermore, due to the airflow from below (described in detail below), an "unrestricted ignition" fuel layer is formed. As previously mentioned, "unrestricted ignition," also known as "infinite combustion," refers to the situation where the direction of fuel ignition aligns with the direction of oxygen supply and ventilation, resulting in unrestricted ignition conditions and a complete combustion state. Under "unrestricted ignition" conditions, even low-quality fuels can be burned at low temperatures.

[0021] According to the present invention, the fuel on each level of the grate is in an "unlimited ignition" state. As the "unlimited ignition" fuel layer moves downward along the grate, the fuel to be burned is ignited, and then the "unlimited ignition" fuel layer slides down the grate to the downstream grate (which can be called the "second-level grate") to form a "bottom fire". Subsequently, the "bottom fire" can be optionally covered by the fuel to be burned spread from the tail end of the upstream grate (i.e., the above-mentioned "first-level grate"), thereby continuing to form the "unlimited ignition" fuel layer in the aforementioned state, wherein the fuel to be burned is ignited when it moves on the second grate of the "unlimited ignition" fuel layer, thereby providing a "bottom fire" to the downstream grate (which can be called the "third-level grate"), ... and this combustion method is repeated until the final slag discharge grate 19 discharges the slag.

[0022] During the above combustion process, the fuel flows from top to bottom and the smoke flows from bottom to top in opposite directions, along a reciprocating "snake-like" path, so the combustion time is long and the combustion is more complete.

[0023] It's important to note that in the present invention, only some of the grates can be used to add fuel to be burned. For example, only the fuel supply device 10 at the end of the fire source grate 8 can be used to distribute new fuel to the first-stage grate 9, while the first-stage grate and subsequent grates can no longer distribute new fuel to be burned. Alternatively, only the fuel supply devices 10 at the end of the fire source grate 8 and the first-stage grate 9 can be used to distribute new fuel to be burned, while the second-stage grate and subsequent grates can no longer distribute new fuel to be burned, and so on. This design allows a given hearth to accommodate a wide range of loads, matching the load to the heating surface, and avoiding or reducing adverse conditions such as condensation.

[0024] According to the present invention, the front and rear walls 2 and 4 of the hearth can be water-cooled membrane walls. In this case, each grate 9 can be formed integrally by the inclined sections 22 of the front and rear membrane walls 2 and 4, such as Figure 1As shown. More specifically, the water-cooled membrane walls 2, 4 have a plurality of vertical segments 21 and inwardly protruding segments 20 located between each pair of adjacent vertical segments 21, each inwardly protruding segment 20 including: an inclined segment 22 extending inwardly and obliquely downwardly from the lower end of the higher vertical segment 21 among the adjacent vertical segments, and a flue-defining segment 23 connecting the lower end of the inclined segment 22 and the upper end of the lower vertical segment 21 among the adjacent vertical segments. The inclined segment 22 forms the grate 9. The flue-defining segment 23 can be horizontal or inclined to define a flue together with the grate 9 below and the front, rear, left and right walls of the hearth. In the non-limiting embodiment shown in the figure, the inclined segment 22 and the flue-defining segment 23 are connected to each other to form a roughly V-shaped structure, the apex of the V-shaped structure corresponding to the tail end of the inclined grate 9.

[0025] In this embodiment, Figure 2 As shown, the steel plate fins 15 between the tube bundles 14 forming the inclined section of the membrane wall grate 9 are machined with multiple ventilation holes 16. The ventilation holes 16 can be used for ventilation. The ventilation function is to supply oxygen to the fuel layer on the one hand, and to "slightly lift" the fuel layer on the other hand to reduce the frictional resistance of the fuel layer, allowing it to overcome friction and slide downward. The inclination angle of the grate 9 relative to the horizontal direction can be between 18 degrees and 50 degrees, preferably between 25 degrees and 45 degrees. Based on this angle, combined with the appropriate number and size of ventilation holes 16 and ventilation pressure, the fuel layer can be "slightly lifted", so that it can slide naturally under the action of its gravity.

[0026] To match the ventilation purpose of the vent holes 16, a sealed air silo 17 is provided on the bottom side of the grate 9. The air silo 17 can be formed, for example, by steel plates welded along the side edges of the grate 9. The air silo 17 can be equipped with an air inlet 18 to receive pressurized air from a blower and supply air to the grate 9 through the vent holes 16.

[0027] A fuel supply device 10 is positioned below the rear end of at least some grates 9. The fuel supply device 10 is positioned between the bottom of the wind chamber 17 and the flue-defining section 23. A fuel supply port 11 corresponding to the fuel supply device 10 is located at the end of the flue-defining section 23 and extends along the entire width of the grate. Fuel to be burned, supplied by the fuel supply device 10, is dispensed from this supply port 11 onto the next grate 9.

[0028] The fuel supply port 11 can be formed by the inter-tube bundle openings of the bare tube section of the membrane wall—that is, the section consisting of only tube bundles without the inter-tube bundle steel fins. Furthermore, the bare tubes forming the fuel supply port 11 can be coplanar, or adjacent bare tubes can be staggered along the front-to-back direction of the hearth to provide a larger fuel supply port 11.

[0029] The fuel supply device 10 may be a screw fuel supply machine arranged along the width direction of the grate (see Figure 3 The screw fuel feeder is arranged near the tail end of the grate to spread fuel along the full width of the grate. This screw fuel feeder itself is a prior art and will not be described in detail.

[0030] In another embodiment not shown, the fuel supply device 10 can be a chain-type fuel conveyor or conveyor belt arranged between the bottom of the wind bin 17 and the flue defining section 23, which transports fuel toward the fuel supply port 11 in a direction perpendicular to the width of the grate.

[0031] In another embodiment, the inwardly protruding section 20 is not formed by bending the membrane wall as a whole, but can be formed separately and then connected to the membrane wall as a whole. Figure 4 As shown, the inwardly projecting section 20 can be formed separately from the membrane wall material, optionally with an integral wind silo 17, and then welded to the front and rear membrane walls of the hearth via end headers 25, similar to headers 1, 3, 5, and 6. In this case, the flue-defining section 23 of the inwardly projecting section 20 can be formed integrally with or separately from the inclined section 22; if the two are formed separately, they can be connected integrally via headers.

[0032] In the embodiment shown in the figure, when viewed from the front wall of the hearth toward the rear wall of the hearth, the tube bundles of the membrane walls of the front and rear walls of the hearth are vertically oriented, and therefore the tube bundles forming the membrane walls of the grate 9 are also vertically oriented. Figure 2 This point should be readily understood. In another embodiment, when viewed from the hearth's front wall toward the hearth's rear wall, the tube bundles of the membrane walls of the front and rear walls of the hearth can be horizontally oriented. Accordingly, the tube bundles of the membrane walls of the grate 9 can also be horizontally oriented. The inventors have discovered that when the grate tube bundles are horizontally oriented, the shallow height difference between the steel plate fins between tube bundles does not substantially affect the downward movement of the fuel on the grate, and this difference can be compensated for by slightly changing the tilt angle or adjusting the blast pressure.

[0033] The grates above are all membrane wall fixed grates, so they can be called "water-cooled fixed grates". The inventors have also found that "non-water-cooled fixed grates" can also be used. The "non-water-cooled fixed grate" can be, for example, a "grate" type inclined grate, or a simple perforated plate inclined grate. The "grate" type grate can be composed of a plurality of grate bars arranged side by side and spaced apart. The direction of the grate bars is similar to the tube bundle of the membrane grate, either vertically or horizontally. The perforated plate grate can be a simple cast plate or steel plate formed with a plurality of ventilation holes. The "non-water-cooled grate" can be directly connected to the water-cooled membrane wall or the furnace wall without a water-cooled membrane wall. A flue defining section can be set similarly to the flue defining section 23 to close the flue.

[0034] The grates mentioned above can be called "fixed grates" or "pneumatic grates" because the fuel overcomes friction with the help of air blast and slides under the action of gravity. The present invention can also use movable grates fixed to the furnace wall, that is, traditional mechanical grates with mechanical power, such as chain grates, reciprocating grates, vibrating grates, etc. These grates are well known in the art and will not be described in detail. At this time, the gaps on the grate sheets form the aforementioned ventilation holes. When using mechanical grates, because there is mechanical power to transport fuel, the grates can be arranged horizontally or tilted. In contrast, fixed grates must be arranged tilted so that the fuel can slide down by relying on the lifting force of gravity and ventilation.

[0035] The fire source grate 8 can be a common mechanical grate such as a chain grate or a reciprocating grate, which can be arranged tilted (such as Figure 1 (as shown), it can also be arranged horizontally, its function being to supply ignited fuel to the downstream first-stage grate 9 to serve as a "primer fire." A fuel supply device 10 and a fuel supply port 11 are provided on the lower side of the rear end of the fire source grate 8, allowing the fuel to be spread onto the "primer fire." The primer and the fuel to be burned form an "unrestricted ignition" fuel layer. On the one hand, it is fully burned by the rising flue gas and the air blast from the ventilation holes 16. On the other hand, under the action of gravity and with the help of the air blast, it overcomes friction and moves along the first-stage grate 9 to the downstream second-stage grate 9. At this point, the first-stage grate 9 effectively serves as the "fire source grate" for the second-stage grate 9, supplying the "fire source" to the second-stage grate. The second-stage grate can also be equipped with a fuel supply device 10 to supply the fuel to be burned. The fuel to be burned covers the "fire source" fuel and continues to slide down to the downstream third-stage grate 9. The above combustion process is repeated for each grate 9 from top to bottom. During this process, the fuel is fully burned.

[0036] Below the last grate 9 is a slag discharge grate 19, which can be a common mechanical grate, such as a chain / chain plate mechanical grate, which receives unburned fuel from the last grate 9, burns it into slag, and then discharges it into the slag pit.

[0037] The number of inclined grates 9 can be determined according to specific circumstances.

[0038] In the case of a membrane wall, the water-cooling effect of the membrane wall not only facilitates heat exchange but also helps achieve low-temperature combustion and reduce nitrogen oxide emissions. Of course, if conditions permit, the membrane wall can be omitted, with each grate directly connected to the front or rear wall of the hearth, as well as to the left and right walls.

[0039] The present invention is not only applicable to traditional fuels such as coal, but is also particularly suitable for burning garbage and biomass fuels. Garbage and biomass fuels are easy to coke and are not easy to fully and continuously burn. In the present invention, first, the surface of the fuel will be coked due to the high-temperature flue gas during the falling and suspended combustion process, which is conducive to preventing the adhesion between the fuel particles and plays a role in preventing coking and agglomeration. At the same time, because there is a drop between the grates, the fuel "falls" onto the downstream grate, and this "falling" process plays a role in breaking up the coke, which is conducive to the full and continuous combustion of the fuel. In addition, since the present invention can achieve full combustion, when burning garbage or biomass fuels, there is no need to pulverize the garbage or biomass fuels, or at least the degree of pulverization can be reduced, thereby saving energy and reducing costs.

Claims

1. A hearth, characterized in that: The hearth has a serpentine flue extending from bottom to top, the serpentine flue being defined by a front wall, a rear wall, a left wall, a right wall of the hearth, and a plurality of grates extending from the front wall and the rear wall of the hearth respectively, each grate having a head end connected to the front wall or the rear wall of the hearth and an opposite tail end. The plurality of grates are arranged in sequence from top to bottom, and each grate extends alternately from the front wall and rear wall of the hearth toward the opposite rear wall and front wall of the hearth, and its tail end maintains a predetermined interval with the rear wall or front wall of the hearth; each grate extends from the left wall of the hearth to the right wall of the hearth in the width direction; Adjacent grates are spaced apart from each other in the vertical direction so that there is a vertical distance between the tail end of each grate and the next grate, and each grate is configured to receive fuel from the upper grate adjacent thereto. A fuel supply device is arranged under the tail end of at least some of the multiple grates, and the fuel supply device is used to supply fuel to be burned to the next grate.

2. The hearth according to claim 1, wherein The grate is a fixed grate, which extends obliquely downward from the head end to the tail end to transport fuel downstream.

3. The hearth according to claim 2, wherein: The grate is a water-cooled grate.

4. The hearth according to claim 3, wherein: The front wall or rear wall of the hearth has a water-cooled membrane wall, wherein the water-cooled membrane wall has a plurality of vertical segments and an inwardly protruding segment between each pair of adjacent vertical segments. Each inwardly protruding segment includes: an inclined segment extending inwardly and obliquely downwardly from the lower end of a higher vertical segment among the adjacent vertical segments, and a flue defining segment connecting the lower end of the inclined segment and the upper end of the lower vertical segment among the adjacent vertical segments. The inclined section forms the grate; the flue defining section is arranged horizontally or inclined to define the flue together with the grate below and the front, rear, left and right walls of the hearth.

5. The hearth according to claim 4, wherein: The inclined section and the flue defining section form a substantially V-shaped structure, and the apex of the V-shaped structure corresponds to the tail end of the grate.

6. The hearth according to claim 4, wherein: The water-cooled membrane wall of the front wall or rear wall of the hearth has tube bundles and steel plates between the tube bundles. The tube bundles are vertically or horizontally oriented, and a plurality of ventilation holes are formed on the steel plates between the tube bundles in the inclined section.

7. The hearth according to claim 4, wherein: The inwardly protruding section is formed by integrally bending the water-cooled membrane wall of the front wall or the rear wall of the hearth inwardly.

8. The hearth according to claim 4, wherein: The inwardly protruding section is formed of a water-cooled membrane wall material that is separate from the water-cooled membrane wall of the hearth front wall or rear wall and is connected to the water-cooled membrane wall of the hearth front wall or rear wall.

9. The hearth according to claim 2, wherein: The grate is a non-water-cooled grate, which is connected to the front wall or the rear wall of the hearth, and to the left and right walls of the hearth.

10. The hearth according to claim 9, wherein The grate is a "grate" type grate, which has a frame structure composed of a plurality of grate bars arranged side by side and spaced apart; when viewed from the front wall of the hearth to the rear wall of the hearth, the grate bars are oriented vertically or horizontally.

11. The hearth according to claim 9, wherein The grate is a perforated plate grate, which is a cast plate or steel plate structure with a plurality of ventilation holes formed therein.

12. The hearth according to claim 2, wherein: The grate is inclined at an angle between 18 degrees and 50 degrees relative to the horizontal direction.

13. The hearth according to claim 12, wherein: The grate is inclined at an angle between 25 degrees and 45 degrees relative to the horizontal direction.

14. The hearth according to claim 6, wherein A sealed wind silo is provided on the bottom side of each grate, which is communicated with the ventilation holes and is provided with an air inlet to receive pressurized air from a blower and supply air to the grate through the ventilation holes.

15. The hearth according to claim 4, wherein A fuel supply port is arranged near the tail end of the grate in the flue defining section. The fuel supply port extends along the entire width of the grate. The fuel to be burned supplied by the fuel supply device is scattered onto the next grate through this supply port.

16. The hearth according to claim 15, wherein The fuel supply port is formed by an opening between tube bundles of a light tube section of a membrane wall, and the light tubes forming the fuel supply port are coplanar.

17. The hearth according to claim 15, wherein: The fuel supply port is formed by an opening between tube bundles of the light tube section of the membrane wall. The light tubes forming the fuel supply port are configured so that adjacent light tubes are staggered with each other along the front-rear direction of the hearth.

18. The hearth according to claim 1, wherein: The fuel supply device is a screw fuel supply machine.

19. The hearth according to claim 1, wherein The fuel supply device is a chain-plate fuel conveyor or a conveyor belt that conveys fuel toward the fuel supply port along a direction perpendicular to the width direction of the grate.

20. The hearth according to claim 1, wherein The plurality of grates are movable grates, which extend horizontally or obliquely downward to transport the fuel downstream.

21. The hearth according to claim 20, wherein The grate is a chain grate, a reciprocating grate or a vibrating grate.

22. The hearth according to claim 1, wherein The furnace bed also includes a fire source grate located at the top of the serpentine flue, and the fire source grate is used to supply ignition fuel as a fire source to the upstreammost grate among the multiple grates. The tail end of the fire source grate maintains a predetermined horizontal distance from the opposite furnace wall and a predetermined vertical distance from the upstreammost grate. A fuel supply device is also arranged below the tail end of the fire source grate to supply fuel to be burned to the upstreammost grate.

23. The hearth according to claim 22, wherein: The fire source grate is a movable grate, which extends horizontally or obliquely downward to transport fuel downstream.

24. The hearth of claim 22, wherein: The fire source grate is a chain grate, a reciprocating grate or a vibrating grate.

25. The hearth of claim 1, wherein: The fuel is any one of the following: coal, garbage, biomass, or a mixture thereof.

26. A boiler, characterized in that: The boiler has the hearth as claimed in claim 1.

Images