Frame tubular low-nitrogen condensation steam generator

Abstract

The utility model belongs to the technical field of steam generators, and particularly relates to a frame tubular low-nitrogen condensation steam generator which comprises a heating chamber and a plurality of convection banks arranged in the heating chamber, the heating chamber comprises a high-temperature chamber, a medium-temperature chamber and a low-temperature chamber which are sequentially arranged from bottom to top and are separated from one another, a combustion chamber is arranged on one side of the high-temperature cavity, a first smoke guide chamber communicated with the high-temperature cavity and the medium-temperature cavity is arranged on the other side of the high-temperature cavity, the first smoke guide chamber and the combustion chamber are oppositely arranged, a second smoke guide chamber communicated with the medium-temperature cavity and the low-temperature cavity is arranged on one side of the medium-temperature cavity, and the first smoke guide chamber and the second smoke guide chamber are oppositely arranged. The convection tube bundle can effectively prevent the evaporation section of the convection tube bundle from bursting due to overhigh temperature.

Description

Technical field:

[0001] The utility model belongs to the technical field of steam generators, in particular to a frame cross-flow type low-nitrogen condensing steam generator. Background technology:

[0002] Steam generator equipment is mostly used in textile, printing and dyeing, hotels, hospitals, medicine, chemicals, cardboard, food and beverage, tobacco, wine making and other fields. It is a device that uses the thermal energy of gas fuel to heat water and boil it into steam.

[0003] In existing cross-flow steam generators, the burner is generally installed at the top or bottom. The heat absorption section and evaporation section of the heating surface tube bundle are both baked and flushed by high-temperature flames and high-temperature flue gases. When the water level control is unstable, the steam volume may fluctuate greatly, causing dry burning and tube bursting and other damages. Summary of the invention:

[0004] The utility model aims to provide a frame cross-flow type low nitrogen condensing steam generator, which can effectively prevent the evaporation section of the convection tube bundle from bursting due to excessive temperature.

[0005] The utility model is achieved in this way:

[0006] A frame cross-flow low-nitrogen condensing steam generator comprises a heating chamber and a plurality of convection tube bundles arranged in the heating chamber, wherein the heating chamber comprises a high-temperature chamber, a medium-temperature chamber and a low-temperature chamber which are arranged in sequence from bottom to top and separated, a combustion chamber is arranged on one side of the high-temperature chamber, a smoke guide chamber 1 which connects the high-temperature chamber and the medium-temperature chamber is arranged on the other side of the high-temperature chamber, and the smoke guide chamber 1 is arranged opposite to the combustion chamber, and a smoke guide chamber 2 which connects the medium-temperature chamber and the low-temperature chamber is arranged on one side of the medium-temperature chamber, and the smoke guide chamber 1 and the smoke guide chamber 2 are arranged opposite to each other.

[0007] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, outer spiral fins are provided on the periphery of the convection tube bundle, and spiral plates are provided inside the convection tube bundles located in the medium-temperature chamber and the low-temperature chamber.

[0008] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, the outer spiral fins are welded to the outer periphery of the convection tube bundle, the spiral plate is inserted into the convection tube bundle, and the spiral plate is tightly attached to the inner wall surface of the convection tube bundle to limit the spiral plate from sliding down.

[0009] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, it also includes a water supply main pipe arranged below the heating chamber and a gas collecting main pipe arranged above the heating chamber. The lower ends of each convection tube bundle are respectively connected to the water supply main pipe, and the upper ends are respectively connected to the gas collecting main pipe. A waste heat recovery chamber is provided on the side opposite to the low-temperature chamber and the smoke guide chamber. A water inlet pipe is provided in the waste heat recovery chamber. A water inlet interface is provided at one end of the water inlet pipe, and the other end is connected to the water supply main pipe through a connecting pipe.

[0010] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, the lower end of each convection tube bundle is connected to the water supply main through its own water supply branch pipe, and the upper end of each convection tube bundle is connected to the gas collecting main pipe through its own gas collecting branch pipe.

[0011] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, the water inlet pipe is arranged in a serpentine shape, a flue gas outlet is provided on the side of the waste heat recovery chamber away from the low-temperature chamber, and a water pump and a check valve are provided on the connecting pipe.

[0012] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, a water-cooling pipe for reducing the flame temperature is provided on the side of the combustion chamber away from the high-temperature chamber. The water-cooling pipe is arranged vertically, and there are multiple water-cooling pipes. The lower end of each water-cooling pipe is connected to the water supply main pipe, and the upper end is connected to the gas collecting main pipe.

[0013] In the above-mentioned frame through-flow low-nitrogen condensing steam generator, spiral plates are provided in the water-cooling pipes located in the medium-temperature chamber and the low-temperature chamber.

[0014] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, a gas mixer is provided on the side of the water-cooling pipe away from the combustion chamber, and the combustion chamber and the gas mixer are connected by a plurality of spaced-apart air intake pipes, and the fresh air inlet of the gas mixer is connected to the fan, and the gas inlet is connected to the gas pipeline.

[0015] In the above-mentioned frame-type through-flow low-nitrogen condensing steam generator, it also includes an ignition flame detector with one end extending into the combustion chamber.

[0016] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, the water-cooling tubes are arranged longitudinally, and two adjacent water-cooling tubes, the frontmost water-cooling tube and the corresponding convection tube bundle, and the rearmost water-cooling tube and the corresponding convection tube bundle are connected by connecting plates. The combustion chamber is formed between the lower end of the water-cooling tube and the lower end of the convection tube bundle, and the second smoke guide chamber is formed between the middle and upper ends of the water-cooling tube and the middle and upper ends of the convection tube bundle.

[0017] In the above-mentioned frame through-flow low-nitrogen condensing steam generator, the convection tube bundle is in a rectangular array, and the frontmost adjacent convection tube bundles and the rearmost adjacent convection tube bundles are respectively connected by connecting plates to form the heating chamber, the combustion chamber is located on the right side of the heating chamber, the smoke guide chamber 1 is located on the left side of the heating chamber, the high-temperature chamber and the medium-temperature chamber, as well as the medium-temperature chamber and the low-temperature chamber are separated by partitions, and the smoke guide chamber 1 is formed by a surrounding plate arranged around the outer periphery of the leftmost convection tube bundle.

[0018] In the above-mentioned frame through-flow low-nitrogen condensing steam generator, the bottom and top of the heating chamber are sealed by baffles respectively, the bottom of the combustion chamber and the top of the second smoke guide chamber are sealed by baffles respectively, the combustion chamber and the second smoke guide chamber are separated by a baffle, and the baffle is made of fireproof steel plate and is fixed to the corresponding convection tube bundle, water cooling tube, water supply branch pipe and gas collecting branch pipe by welding.

[0019] In the above-mentioned frame cross-flow low-nitrogen condensing steam generator, the connecting plate, the partition plate and the enclosure plate are made of fireproof steel plates and are all fixed to the corresponding convection tube bundles by welding.

[0020] The outstanding advantages of the utility model compared with the prior art are:

[0021] 1. The utility model divides the heating chamber into a high-temperature chamber, a medium-temperature chamber and a low-temperature chamber. The evaporation section of the convection tube bundle is located in the medium-temperature chamber and the low-temperature chamber. Compared with the high-temperature chamber, the medium-temperature chamber and the low-temperature chamber have lower temperatures, which effectively prevents the evaporation section of the convection tube bundle from bursting due to excessive temperature. The utility model reasonably arranges the temperature gradient according to the state of the medium in the convection tube bundle, effectively avoiding overburning and bursting accidents;

[0022] 2. The outer periphery of the convection tube bundle of the utility model is provided with external spiral fins, which has strong heat exchange capacity; spiral plates are provided inside the convection tube bundles located in the medium temperature chamber and the low temperature chamber, which has good steam dryness and high steam quality;

[0023] 3. The utility model is provided with a water cooling pipe for reducing the flame temperature on the side of the combustion chamber away from the high temperature chamber, which effectively reduces the temperature of the high temperature zone of the flame and effectively reduces the generation of nitrogen oxides. Description of the drawings:

[0024] Figure 1 It is a structural schematic diagram of the utility model;

[0025] Figure 2 It is a structural schematic diagram of the convection tube bundle of the utility model.

[0026] Figure numerals: 1. convection tube bundle; 2. high-temperature chamber; 3. medium-temperature chamber; 4. low-temperature chamber; 5. combustion chamber; 6. smoke guide chamber one; 7. smoke guide chamber two; 8. external spiral fins; 9. spiral plate; 10. water supply main pipe; 11. gas collecting main pipe; 12. waste heat recovery chamber; 13. water inlet pipe; 14. water inlet interface; 15. connecting pipe; 16. flue gas outlet; 17. water pump; 18. check valve; 19. water cooling pipe; 20. partition; 21. enclosure; 22. water supply branch pipe; 23. gas collecting branch pipe. Specific implementation method:

[0027] The present invention is further described below with reference to specific embodiments. Figure 1 —2:

[0028] A frame cross-flow low-nitrogen condensing steam generator comprises a heating chamber and a plurality of convection tube bundles 1 arranged in the heating chamber, wherein the heating chamber comprises a high-temperature chamber 2, a medium-temperature chamber 3 and a low-temperature chamber 4 which are arranged and separated from each other in sequence from bottom to top, a combustion chamber 5 is provided on one side of the high-temperature chamber 2, a smoke guide chamber 1 6 which connects the high-temperature chamber 2 and the medium-temperature chamber 3 is provided on the other side of the high-temperature chamber 2, and the smoke guide chamber 1 6 is arranged opposite to the combustion chamber 5, and a smoke guide chamber 2 7 which connects the medium-temperature chamber 3 and the low-temperature chamber 4 is provided on one side of the medium-temperature chamber 3, and the smoke guide chamber 1 6 and the smoke guide chamber 2 7 are arranged opposite to each other.

[0029] Figure 1 The arrows in the figure indicate the direction of smoke. Figure 1 Wavy line filling represents water, dot filling represents water vapor, and a mixture of wavy line filling and dot filling represents a water vapor mixed state.

[0030] Due to high temperature heating, the liquid level line is higher in actual operation than the liquid level without heating, and the liquid level line fluctuates during actual operation, not being stable. In this embodiment, the heat absorption section refers to the part below the liquid level line, and the evaporation section refers to the part above the liquid level line, wherein the liquid level line refers to the liquid level line of high temperature heating in actual operation.

[0031] The working principle of the utility model is as follows: Figure 1 As shown, after the gas is burned in the combustion chamber 5, the smoke flows through the high-temperature chamber 2 and the smoke guide chamber 1 6 to the medium-temperature chamber 3, and then flows through the smoke guide chamber 2 7 to the low-temperature chamber 4. The water in the convection tube bundle 1 absorbs a large amount of heat energy in the heat absorption section and turns into a steam-water mixture, which enters the evaporation section, continues to absorb heat and evaporates, and finally produces saturated steam.

[0032] The temperatures of the high-temperature chamber 2, the medium-temperature chamber 3 and the low-temperature chamber 4 of the utility model are relative. Since the combustion chamber 5 is arranged on the side of the high-temperature chamber 2, the temperature of the high-temperature chamber 2 is the highest; the temperature of the flue gas after heat exchange with the convection tube bundle 1 located in the high-temperature chamber 2 is reduced, so the temperature of the medium-temperature chamber 3 is lower than the temperature of the high-temperature chamber 2; the temperature of the flue gas after heat exchange with the convection tube bundle 1 located in the medium-temperature chamber 3 is further reduced, so the temperature of the low-temperature chamber 4 is lower than the temperature of the medium-temperature chamber 3.

[0033] Because the convection heat release coefficient of water is much larger than that of steam, the water in the convection tube bundle 1 of the high-temperature chamber 2 can quickly absorb the heat of the tube wall of the convection tube bundle 1, thereby ensuring that the wall temperature of the convection tube bundle 1 of the high-temperature chamber 2 will not be too high, thus avoiding overburning and damage of the convection tube bundle 1 of the high-temperature chamber 2, and ensuring the safe operation of the convection tube bundle 1 of the high-temperature chamber 2. The utility model is safe and reliable in operation.

[0034] The utility model divides the heating chamber into a high temperature chamber 2, a medium temperature chamber 3 and a low temperature chamber 4. The evaporation section of the convection tube bundle 1 is located in the medium temperature chamber 3 and the low temperature chamber 4. The medium temperature chamber 3 and the low temperature chamber 4 are lower in temperature than the high temperature chamber 2, which effectively prevents the evaporation section of the convection tube bundle 1 from bursting due to excessive temperature. The utility model reasonably arranges the temperature gradient according to the state of the medium in the convection tube bundle 1, effectively avoiding overburning and bursting accidents.

[0035] In order to increase the heat absorption area of ​​the convection tube bundle 1, that is, to increase the heat exchange area and enhance the heat exchange capacity, as Figure 2 As shown, the outer periphery of the convection tube bundle 1 is provided with outer spiral fins 8. When the same heat exchange capacity is required, the number of heat exchange tubes can be reduced, and the volume and steel consumption are both smaller than those of the existing steam generator, and the cost is low.

[0036] In order to improve the steam dryness, Figure 2 As shown, a spiral plate 9 is provided in the convection tube bundle 1 located in the medium temperature chamber 3 and the low temperature chamber 4. The steam-water mixture rotates and rises in the convection tube bundle 1, which can separate the water in the steam-water mixture to the tube wall by centrifugal force, and at the same time, the water separated from the tube wall is heated and converted into steam. As the steam-water mixture flows upward, the steam dryness becomes better and better, and the steam quality is high. At the same time, the spiral plate 9 is provided in the convection tube bundle 1, which can reduce the volume of water in the convection tube bundle 1 and improve the heat exchange efficiency between water and flue gas. In addition, the steam-water separation of the utility model is completed by the spiral plate 9, and separation is carried out while heating, without the need to set up a separate steam-water separation device, and the overall volume is small.

[0037] Connection method of the outer spiral fins 8 : the outer spiral fins 8 are welded to the outer periphery of the convection tube bundle 1 .

[0038] The spiral plate 9 is installed in the following manner: the spiral plate 9 is inserted into the convection tube bundle 1 , and the spiral plate 9 is tightly attached to the inner wall surface of the convection tube bundle 1 to limit the spiral plate 9 from sliding downward.

[0039] In order to reduce the temperature of the smoke when it is discharged and recover the waste heat at the same time, it also includes a water supply main pipe 10 arranged below the heating chamber and a gas collecting main pipe 11 arranged above the heating chamber. The lower ends of each convection tube bundle 1 are respectively connected to the water supply main pipe 10, and the upper ends are respectively connected to the gas collecting main pipe 11. A waste heat recovery chamber 12 is provided on the side of the low-temperature chamber 4 opposite to the smoke guide chamber 7. A water inlet pipe 13 is provided in the waste heat recovery chamber 12. A water inlet interface 14 is provided at one end of the water inlet pipe 13, and the other end is connected to the water supply main pipe 10 through a connecting pipe 15.

[0040] Furthermore, the lower ends of the convection tube bundles 1 are connected to the water supply main pipe 10 through their own water supply branch pipes 22 , and the upper ends of the convection tube bundles 1 are connected to the gas collecting main pipe 11 through their own gas collecting branch pipes 23 .

[0041] In order to improve the waste heat recovery efficiency and further reduce the exhaust temperature of the flue gas, the water inlet pipe 13 is arranged in a serpentine shape, and a flue gas outlet 16 is provided on the side of the waste heat recovery chamber 12 away from the low-temperature chamber 4 .

[0042] Furthermore, the connecting pipe 15 is provided with a water pump 17 and a check valve 18 to effectively prevent water from flowing back.

[0043] In this embodiment, the temperature of the flue gas discharged from the flue gas outlet 16 can be reduced to below 60° C., and the thermal efficiency can be as high as 102% or more (calculated based on the lower calorific value of the applied fuel).

[0044] Most of the existing cross-flow steam generators use metal fiber surface burners. When used, the excess air coefficient is generally greater than 1.45, and the nitrogen oxide emission can reach 30mg / Nm 3 Standards, otherwise the flue gas emissions will not meet the standards, a large amount of cold air will enter the furnace, reducing the thermal efficiency of the steam generator, and the environment requirements are high and it is easy to get dirty and clogged, so the filter needs to be cleaned frequently.

[0045] In order to reduce the temperature of the high-temperature zone of the flame, make the temperature distribution of the flame uniform, effectively reduce the generation of nitrogen oxides, and achieve low nitrogen emissions of the flue gas produced by combustion, a water-cooling pipe 19 is provided on the side of the combustion chamber 5 away from the high-temperature chamber 2 to reduce the flame temperature. The water-cooling pipe 19 is arranged vertically, and there are multiple water-cooling pipes 19. The lower end of each water-cooling pipe 19 is connected to the water supply main pipe 10, and the upper end is connected to the gas collecting main pipe 11. The water-cooling pipe 19 is used to produce steam to make full use of the heat generated by the combustion chamber 5.

[0046] The utility model effectively reduces the generation of nitrogen oxides when a large amount of cold air is not required (excess air coefficient 1.2), and the nitrogen oxide emissions are lower than 30mg / Nm 3 , there is less cold air, and the volume of the combustion chamber 5 can be reduced accordingly.

[0047] In order to improve the steam quality of the water-cooling pipe 19 , spiral plates 9 are provided in the water-cooling pipe 19 located in the medium-temperature chamber 3 and the low-temperature chamber 4 .

[0048] Water flow process: water enters the water inlet pipe 13 from the water inlet interface 14, and after absorbing heat, enters the water supply main pipe 10 from the connecting pipe 15 through the water pump 17, and then enters the convection tube bundle 1 and the water cooling pipe 19 through the water supply branch pipe 22. The generated steam enters the gas collecting main pipe 11 through the gas collecting branch pipe 23.

[0049] Furthermore, a gas mixer is provided on the side of the water-cooling pipe 19 away from the combustion chamber 5. The combustion chamber 5 and the gas mixer are connected by a plurality of spaced-apart air intake pipes. The fresh air inlet of the gas mixer is connected to the fan, and the gas inlet is connected to the gas pipe. The air intake pipes are widely spaced, and the gap on the fire outlet surface is relatively large. There is no problem of dirt and blockage, and the environmental requirements are not high, which reduces the failure rate of the burner.

[0050] After the fresh air and the fuel gas are mixed in the gas mixer, they continuously enter the combustion chamber 5 through the gap between the air intake pipe and the water cooling pipe 19.

[0051] Furthermore, it also includes an ignition fire detector with one end extending into the combustion chamber 5.

[0052] The formation structure of the combustion chamber 5 and the second smoke guide chamber 7: the water-cooling tubes 19 are arranged in the longitudinal direction, and the adjacent two water-cooling tubes 19, the frontmost water-cooling tube 19 and the corresponding convection tube bundle 1, and the rearmost water-cooling tube 19 and the corresponding convection tube bundle 1 are connected by connecting plates. The combustion chamber 5 is formed between the lower end of the water-cooling tube 19 and the lower end of the convection tube bundle 1, and the second smoke guide chamber 7 is formed between the middle and upper ends of the water-cooling tube 19 and the middle and upper ends of the convection tube bundle 1.

[0053] The formation structure of the heating chamber and the smoke guide chamber 6: the convection tube bundle 1 is in a rectangular array, and the frontmost adjacent convection tube bundles 1 and the rearmost adjacent convection tube bundles 1 are respectively connected by connecting plates to form the heating chamber, the combustion chamber 5 is located on the right side of the heating chamber, and the smoke guide chamber 6 is located on the left side of the heating chamber. The high-temperature chamber 2 and the medium-temperature chamber 3, as well as the medium-temperature chamber 3 and the low-temperature chamber 4 are separated by a partition 20, and the smoke guide chamber 6 is formed by a surrounding plate 21 arranged around the outer periphery of the leftmost convection tube bundle 1.

[0054] The utility model adopts a frame structure, does not need to set a boiler drum, has low cost and small overall volume.

[0055] Preferably, the connecting plate, the partition plate 20 and the enclosure plate 21 are made of fireproof steel plates, and are fixed to the corresponding convection tube bundle 1 and the water-cooling tube 19 by welding.

[0056] Furthermore, the bottom and top of the heating chamber are sealed by baffles respectively, the bottom of the combustion chamber 5 and the top of the smoke guide chamber 2 7 are sealed by baffles respectively, the combustion chamber 5 and the smoke guide chamber 2 7 are separated by a baffle, and the baffle is made of fireproof steel plate and fixed by welding.

[0057] The above embodiment is only one of the preferred embodiments of the present utility model, and is not intended to limit the scope of implementation of the present utility model. Therefore, any equivalent changes made based on the shape, structure, and principle of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A frame cross-flow low nitrogen condensing steam generator, characterized in that: The invention comprises a heating chamber and a plurality of convection tube bundles (1) arranged in the heating chamber, wherein the heating chamber comprises a high-temperature chamber (2), a medium-temperature chamber (3) and a low-temperature chamber (4) which are arranged in sequence from bottom to top and separated from each other, a combustion chamber (5) is arranged on one side of the high-temperature chamber (2), a smoke guide chamber (6) which connects the high-temperature chamber (2) and the medium-temperature chamber (3) is arranged on the other side of the high-temperature chamber (2), the smoke guide chamber (6) being arranged opposite to the combustion chamber (5), a smoke guide chamber (2) which connects the medium-temperature chamber (3) and the low-temperature chamber (4) is arranged on one side of the medium-temperature chamber (3), the smoke guide chamber (6) being arranged opposite to the smoke guide chamber (7).

2. A frame cross-flow low nitrogen condensing steam generator according to claim 1, characterized in that: The outer periphery of the convection tube bundle (1) is provided with external spiral fins (8), and the convection tube bundles (1) located in the medium-temperature chamber (3) and the low-temperature chamber (4) are provided with spiral plates (9).

3. A frame cross-flow low nitrogen condensing steam generator according to claim 1, characterized in that: It also includes a water supply pipe (10) arranged below the heating chamber and a gas collecting main pipe (11) arranged above the heating chamber. The lower ends of the convection tube bundles (1) are respectively connected to the water supply pipe (10), and the upper ends are respectively connected to the gas collecting main pipe (11). A waste heat recovery chamber (12) is provided on the side of the low-temperature chamber (4) opposite to the second smoke guide chamber (7). A water inlet pipe (13) is provided in the waste heat recovery chamber (12). One end of the water inlet pipe (13) is provided with a water inlet interface (14), and the other end is connected to the water supply pipe (10) through a connecting pipe (15).

4. A frame cross-flow low nitrogen condensing steam generator according to claim 3, characterized in that: The water inlet pipe (13) is arranged in a serpentine shape, and a smoke outlet (16) is provided on the side of the waste heat recovery chamber (12) away from the low-temperature chamber (4). A water pump (17) and a check valve (18) are provided on the connecting pipe (15).

5. A frame cross-flow low nitrogen condensing steam generator according to claim 3, characterized in that: A water cooling pipe (19) for reducing the flame temperature is provided on the side of the combustion chamber (5) away from the high temperature chamber (2). The water cooling pipe (19) is arranged vertically and is provided in plurality. The lower end of each water cooling pipe (19) is respectively connected to a water supply main pipe (10) and the upper end is respectively connected to a gas collecting main pipe (11).

6. A frame cross-flow low nitrogen condensing steam generator according to claim 5, characterized in that: A gas mixer is provided on the side of the water cooling pipe (19) away from the combustion chamber (5); the combustion chamber (5) and the gas mixer are connected via a plurality of air intake pipes arranged at intervals; the fresh air inlet of the gas mixer is connected to the fan, and the gas inlet is connected to the gas pipeline.

7. The frame cross-flow low nitrogen condensing steam generator according to claim 5, characterized in that: The water-cooling tubes (19) are arranged in the longitudinal direction. Two adjacent water-cooling tubes (19), the frontmost water-cooling tube (19) and the corresponding convection tube bundle (1), and the rearmost water-cooling tube (19) and the corresponding convection tube bundle (1) are connected by connecting plates. The combustion chamber (5) is formed between the lower end of the water-cooling tube (19) and the lower end of the convection tube bundle (1), and the second smoke guide chamber (7) is formed between the middle and upper ends of the water-cooling tube (19) and the middle and upper ends of the convection tube bundle (1).

8. The frame cross-flow low nitrogen condensing steam generator according to claim 1, characterized in that: The convection tube bundle (1) is in a rectangular array, and the frontmost adjacent convection tube bundles (1) and the rearmost adjacent convection tube bundles (1) are connected by connecting plates to form the heating chamber. The combustion chamber (5) is located on the right side of the heating chamber, and the smoke guide chamber (6) is located on the left side of the heating chamber. The high-temperature chamber (2) and the medium-temperature chamber (3), as well as the medium-temperature chamber (3) and the low-temperature chamber (4) are separated by a partition (20). The smoke guide chamber (6) is formed by a surrounding plate (21) arranged around the outer periphery of the leftmost convection tube bundle (1).

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