Step-by-step push grate forced circulation coal-fired hot water boiler

Abstract

The present invention discloses a step-by-step push grate forced circulation coal-fired hot water boiler, which comprises a base and a boiler body, wherein the base is provided with a grate, the boiler body is provided above the grate, a drum is provided on the boiler body, a dust filter assembly is provided inside the boiler body, and the dust filter assembly filters dust in the flue gas. A heat dissipation layer is installed inside the boiler body, and the heat dissipation layer is provided on the inner wall of the furnace wall of the boiler body, absorbs the heat inside the boiler body, and replenishes the absorbed heat into the boiler again, reduces the absorption of heat by the furnace wall, thereby reducing the loss of heat and improving the utilization rate of heat.

Description

Technical Field

[0001] The invention relates to the technical field of coal-fired hot water boilers, in particular to a step-by-step grate-pushing forced circulation coal-fired hot water boiler. Background Art

[0002] A boiler is a device that heats water through the heat energy released by the combustion of a medium and produces water vapor or hot water with specified parameters (temperature, pressure). A coal-fired boiler is a thermal power device that uses coal as fuel. The coal is burned in the furnace (combustion chamber) to release heat, heating the heat medium water or other organic heat carrier to a certain temperature. Coal-fired boilers are classified according to their use into coal-fired boiling water boilers, coal-fired hot water boilers, coal-fired steam boilers, and coal-fired thermal oil boilers. Coal-fired hot water boilers are usually designed according to normal pressure, and an air port is provided on the top of the furnace body, so that the boiler can operate without pressure and the combustion operation is safe and reliable; it can be installed and used anywhere it is needed, and is not restricted by the numerous annual inspection procedures, so it has developed rapidly in recent years.

[0003] However, not all heat is effectively converted in coal-fired boilers, and some reactive power is consumed. In addition, current coal-fired hot water boilers generally have unreasonable internal structures. For example, a large number of flue gas pipes are installed inside the existing drum, and the flue gas pipes on the outermost side have the highest heat exchange efficiency, followed by the flue gas pipes in the middle layer. The flue gas pipes in the center exchange heat with the heated water, which makes the heat exchange efficiency of the flue gas pipes in the center low, and the heat in the center flue gas pipes cannot be effectively utilized, resulting in low heat utilization, which in turn increases the use of coal and increases costs. Problems such as non-compact layout, short flue gas flow, and small heating area result in poor heat transfer effect of the boiler, high heat carried by the flue gas, low thermal efficiency of the boiler, and high energy consumption. Summary of the invention

[0004] The object of the present invention is to provide a step-by-step grate forced circulation coal-fired hot water boiler to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a step-by-step grate forced circulation coal-fired hot water boiler, the coal-fired hot water boiler comprises a base and a boiler body, the base is provided with a grate, the boiler body is arranged above the grate, a drum is provided on the boiler body, a dust filter assembly is arranged inside the boiler body, and the dust filter assembly filters dust in the flue gas. A heat dissipation layer is installed in the boiler body, and the heat dissipation layer is arranged on the inner wall of the furnace wall of the boiler body, absorbs the heat inside the boiler body, and replenishes the absorbed heat into the boiler again, reducing the absorption of heat by the furnace wall, thereby reducing the loss of heat and improving the utilization rate of heat.

[0006] As an optimal technical solution, one end of the grate is located outside the boiler body, and the other part of the grate is located inside the boiler body; a coal hopper is arranged above the grate outside the boiler body, and a guide plate is arranged at one end inside the boiler body; the dust filter assembly includes a partition wall, which is arranged at the other end of the boiler body, and a cross wall is arranged on the side of the guide plate close to the partition wall. The coal hopper stores coal, the grate is a step-by-step push grate, which transmits the coal in the coal hopper and provides support for its combustion in the boiler body, a closed combustion space is formed inside the boiler body, and the heat generated during combustion is insulated and isolated to prevent the heat from diffusing to the outside atmosphere and prevent the internal hot air from exchanging heat with the outside, the guide plate guides the high-temperature flue gas generated by the combustion inside the boiler body, so that the flue gas flows in a certain flow direction, the partition wall separates the internal space of the boiler body, so that a combustion chamber and a burnout chamber are formed inside the boiler body, and the cross wall and the guide plate cooperate with each other to prevent the high temperature generated during coal combustion from directly heating the drum, and guide the flue gas so that the flue gas enters the burnout chamber.

[0007] As a preferred technical solution, the dust filtering assembly includes a supporting wall, which is fixed to the internal end face of the boiler body, and the supporting wall is fixed to one end of the partition wall. A return plate is provided on the upper end face of the partition wall close to the guide plate, and a dust removal wall is provided on the end of the cross wall located above the supporting wall. A rounded corner is provided on the end face of the lower end of the dust removal wall close to the partition wall, and a separation wall is provided on the other end face of the dust removal wall, and the other end of the separation wall is in the shape of a sled. The partition wall is tiltedly arranged in the boiler body and guides the flue gas generated in the combustion chamber. The return plate blocks the smoke inlet of the burnout chamber to prevent the smoke in the burnout chamber from expanding and flowing back into the combustion chamber. The supporting wall plays the role of installation support for the partition wall. The partition wall, cross wall, return plate, supporting wall and dust removal wall cooperate with each other to form a burnout chamber. The smoke with dust is burned again in the burnout chamber, so that the temperature of the smoke rises again, and the dust obtains the kinetic energy of high-speed movement and collides with the burnout chamber. The dust is attracted to each other in the collision to form a large Dust particles, the dust removal wall blocks the flue gas expanded after combustion, so that the flue gas flows in a certain direction. The separation wall extends the flow channel of the flue gas, so that the front flue gas flows rapidly in the flow channel under the push of the rear flue gas, and increases the kinetic energy of the dust in the process of flow, so that the dust is separated from the high-temperature flue gas after flowing out of the burnout chamber. The dust removal wall does not contact the inner wall of the boiler body, and cooperates with each other to form a channel I for the vertical flow of flue gas. The upper end surface of the horizontal wall does not contact the lower end of the boiler drum, and the horizontal wall and the boiler drum cooperate with each other to form a channel II for the horizontal flow of flue gas.

[0008] As a preferred technical solution, a separation groove is provided on the upper end surface of the supporting wall, a dust removal channel is provided at the lower end of the supporting wall below the separation groove, the dust removal channel is in the shape of a trumpet, a heating layer is provided inside the supporting wall, and the separation groove is located on the outside of the partition wall. The separation groove is located below the separation wall and on the right side of the partition wall. When the accelerated dust particles move to the lower right, the dust particles move to the separation groove due to inertia, while the flue gas is a light gas and moves upward, thereby separating the dust from the flue gas. The heating layer is composed of sand, and a heating layer is also provided inside the partition wall. The partition wall transfers the absorbed heat to the supporting wall, and the sand inside the supporting wall heats the separation groove. The heating layer inside the supporting wall surrounds the outside of the separation groove and heats the lower end of the separation groove, so that the air at the lower end of the separation groove expands due to heat, and flows to the bottom of the supporting wall through the dust removal channel under the compression of the flue gas at the upper end.

[0009] As an optimal technical solution, the guide plate has a triangular cross-section, a filter layer is arranged inside the guide plate, a front smoke chamber is arranged above the guide plate, and the front smoke chamber is connected to the drum pipeline. The guide plate is hollow inside, the filter layer inside the guide plate is composed of sand, the guide plate is in contact with the combustion chamber, and the sand is heated by the high temperature generated by the combustion chamber. The sand absorbs the temperature on the guide plate through the characteristics of fast heat absorption and fast heat dissipation, and heats the air inside the guide plate and the air in the front smoke chamber above, so that the inside of the guide plate and the front smoke chamber are high-pressure spaces, and the channel II is connected to the internal space of the guide plate, and the smoke flowing out of the channel II enters the inside of the guide plate, and the smoke with trace dust enters the inside of the guide plate, and the trace dust in the smoke is filtered by the sand, and the high-temperature smoke enters the front smoke chamber, further increasing the pressure in the front smoke chamber.

[0010] As an optimal technical solution, several groups of smoke pipes are arranged inside the drum, the inner walls of several groups of the smoke pipes are corrugated, one end of several groups of the smoke pipes is connected to the front smoke chamber, the other end of several groups of the smoke pipes is connected to the rear smoke chamber, and drainage channels are arranged horizontally inside the tube walls at the lower ends of several groups of smoke pipes, the drainage channels are connected to the inside of the smoke pipes, and the drainage channels are connected to the rear smoke chamber. The smoke pipe is connected to the front smoke chamber, so that the high-temperature and high-pressure smoke in the front smoke chamber enters the smoke pipe, providing a channel for the high-temperature and high-pressure smoke to flow in the drum, the high-temperature smoke flows in the smoke pipe and exchanges heat with the water in the drum, the corrugated tube wall destroys the laminar flow of the smoke, and causes the smoke to flow disorderly in the smoke pipe, thereby improving the heat exchange efficiency between the smoke and water and improving the heat utilization rate. The flue gas exchanges heat with water, and the solution produced after condensation flows into the drainage channel and flows out of the flue pipe under the squeeze of the high-pressure flue gas in the flue pipe, preventing the solution from corroding and damaging the flue pipe.

[0011] As an optimal technical solution, the interior of the boiler drum is arranged in a ring shape with at least two layers of smoke pipes from the inside to the outside, the diameter of the smoke pipe located at the center is 3 times the diameter of several groups of smoke pipes in the outer layer, several groups of smoke pipes are provided with a booster plate inside near one end of the rear smoke chamber, an air outlet is opened at the center of the booster plate, several groups of smoke pipes in the outer layer of the smoke pipe at the center are connected to the smoke pipe at the center, and the outer sides of several groups of smoke pipes in the outer layer are connected to several groups of smoke pipes in their own outer layer. Taking the three-layer flue pipe as an example, the flue pipe at the center is connected to the flue pipe at the middle layer, and the diameter of the flue pipe at the center is three times the diameter of all the flue pipes at the outer layer, so that the flue gas content and heat in the center flue pipe increase. Through the increase in heat, the flue pipe participates in the heat exchange process with water. At the same time, the outermost flue pipe and the middle layer of flue pipe are staggered, so that the outermost and middle layers of flue pipes can exchange heat with water very well. When the heat of the smoke in the outermost and middle layers of flue pipes decreases, the internal air pressure decreases accordingly. At this time, the smoke in the central position of the flue pipe flows to the middle layer and the outermost layer through the pipe, providing heat for the outermost and middle layers of the flue pipes, reducing the condensation of the smoke in the outermost and middle layers of the flue pipes, and the booster plate blocks the flow of smoke in the smoke pipe, so that the high-temperature smoke accumulates in the smoke pipe, thereby further increasing the temperature in the smoke pipe, thereby increasing the efficiency of heat exchange.

[0012] As an optimal technical solution, a blower is provided on one side of the base, the blower is connected to the grate pipe, a water inlet pipe and a water outlet pipe are provided on the boiler drum, the water inlet pipe is connected to the water pump pipe, and the rear flue gas chamber is connected to the economizer pipe.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0014] 1. In the present invention, a heat dissipation layer is installed in the boiler body, and the heat dissipation layer is arranged on the inner wall of the furnace wall of the boiler body to absorb the heat inside the boiler body and replenish the absorbed heat into the boiler again, thereby reducing the absorption of heat by the furnace wall, thereby reducing heat loss and improving the utilization rate of heat.

[0015] 2. In the present invention, the partition wall, the transverse wall, the return plate, the supporting wall and the dust removal wall cooperate with each other to form a burnout chamber, and the smoke with dust is burned again in the burnout chamber, so that the temperature of the smoke rises again, and the dust obtains the kinetic energy of high-speed movement and collides in the burnout chamber. The dust is attracted to each other in the collision to form large dust particles. The dust removal wall blocks the smoke after combustion and expansion, so that the smoke flows in a certain flow direction. The separation wall extends the flow channel of the smoke, so that the front smoke flows rapidly in the flow channel under the push of the rear smoke, and increases the kinetic energy of the dust in the process of flow, so that the dust is separated from the high-temperature smoke after flowing out of the burnout chamber, thereby preventing the dust in the smoke from adhering to the inner wall of the smoke pipe when the smoke is cooled, thereby reducing the heat exchange between the smoke pipe and water by the dust, and improving the heat exchange efficiency between the smoke pipe and water.

[0016] 3. In the present invention, the smoke in the smoke pipe at the center position flows to the middle layer and the outermost layer through the pipe, providing heat for the smoke pipes in the outermost layer and the middle layer, reducing the condensation of the smoke in the outermost layer and the middle layer. The booster plate blocks the flow of smoke in the smoke pipe, causing the high-temperature smoke to accumulate in the smoke pipe, thereby further increasing the temperature in the smoke pipe, thereby increasing the efficiency of heat exchange.

[0017] 4. In the present invention, high-temperature flue gas flows in the flue pipe and exchanges heat with water in the boiler drum. The corrugated pipe wall destroys the laminar flow of the flue gas, causing the flue gas to flow disorderly in the flue pipe, thereby improving the heat exchange efficiency between the flue gas and water and improving the heat utilization rate. The flue gas exchanges heat with water, and the solution generated after condensation flows into the drainage channel and flows out of the flue pipe under the squeeze of the high-pressure flue gas in the flue pipe, thereby preventing the solution from corroding and damaging the flue pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 It is a schematic diagram of the position installation of the overall structure of the present invention;

[0020] Figure 2 It is a half-section schematic diagram of the overall structure of the present invention;

[0021] Figure 3 2. It is a front view half-section structure schematic diagram of the smoke pipe of the present invention;

[0022] Figure 4 is a schematic diagram of a simulation of the connection of a smoke pipe in a boiler drum of the present invention;

[0023] Figure 5It is a right side view of the flue gas pipe of the present invention.

[0024] In the figure: 1, base; 2, grate; 3, boiler body; 4, drum; 3-1, guide plate; 3-2, partition wall; 3-3, cross wall; 3-4, return plate; 3-5, dust removal wall; 3-6, separation wall; 3-7, separation trough; 4-1, flue gas pipe; 4-2, booster plate. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figure 1-5 The present invention provides a technical solution: a step-by-step grate forced circulation coal-fired hot water boiler, which includes a base 1 and a boiler body 3. A grate 2 is installed above the base 1, and a blower is installed on the right side of the base 1. The blower blows air to the grate 2 to provide a basis for the combustion of coal on the grate 2. The boiler body 3 is installed above the grate 2. At the same time, a drum 4 is fixedly installed on the upper end of the boiler body 3, and a water inlet pipe, a water outlet pipe, a pressure valve, etc. are installed on the drum 4. The water inlet pipe is connected to a water pump (not shown in the figure) pipeline. The water pump extracts purified water and injects it into the drum 4, so that the water in the drum 4 is forced to circulate. A dust filter component is installed inside the boiler body 3, and the dust filter component filters dust in the flue gas.

[0027] The left end of the grate 2 is located outside the boiler body 3, and the other parts of the grate 2 are located inside the boiler body 3. A coal hopper is installed above the grate 2 on the left side of the boiler body 3. The coal hopper adds coal to the grate 2. The grate 2 is a step-by-step push grate.

[0028] A guide plate 3-1 is fixed on the left end face inside the boiler body 3. The cross section of the guide plate 3-1 is triangular. The inside of the guide plate 3-1 is a hollow structure. Sand is stored inside the guide plate 3-1, and the sand is combined into a filter layer. The internal end face of the boiler body 3, the guide plate 3-1 and the drum 4 cooperate with each other to form a front flue gas chamber above the guide plate 3-1. The front flue gas chamber is connected to the pipeline inside the drum 4. A flue gas chimney is fixed on the right side of the boiler body 3. The right end of the flue gas chimney is connected to the economizer. The flue gas chimney forms a rear flue gas chamber outside the drum 4.

[0029] The dust filter assembly includes a supporting wall and a partition wall 3-2. The right end of the supporting wall is fixed to the right end face inside the boiler body 3, the upper end face on the left side of the supporting wall is fixed to the right end of the partition wall 3-2, and the partition wall 3-2 is installed obliquely on the supporting wall. A return plate 3-4 is obliquely fixed on the upper end face of the partition wall 3-2 on the side close to the guide plate 3-1.

[0030] A horizontal wall 3-3 is horizontally fixedly installed on the right end face of the guide plate 3-1 close to the partition wall 3-2. The upper end face of the horizontal wall 3-3 does not contact the drum 4, and the right end does not contact the right end face of the boiler body 3. A dust removal wall 3-5 is vertically fixed on the right end of the horizontal wall 3-3 located above the supporting wall. The end face of the lower end of the dust removal wall 3-5 close to the partition wall 3-2 is processed with a rounded corner. A separation wall 3-6 is fixedly installed on the right end face of the dust removal wall 3-5 at an angle downward. The separation wall 3-6 is parallel to the partition wall 3-2, and the other end of the separation wall 3-6 is in the shape of a sled.

[0031] The supporting wall, the partition wall 3-2 and the transverse wall 3-3 divide the interior of the boiler body 3 into a combustion chamber and a burnout chamber. The return plate 3-4 and the transverse wall 3-3 cooperate with each other to form a passage between the combustion chamber and the burnout chamber, that is, the smoke inlet of the burnout chamber.

[0032] The right end of the return plate 3-4 is tilted upward, and a smoke inlet with a gradually shrinking flow space is formed between the return plate 3-4 and the cross wall 3-3. Through the setting of the smoke inlet, the smoke generated in the combustion chamber is pressurized at the smoke inlet, so that the smoke pressure at the smoke inlet is greater than the pressure in the burnout chamber, thereby preventing the smoke in the burnout chamber from entering the combustion chamber.

[0033] A heating layer composed of sand is installed in the supporting wall and the partition wall 3-2. A separation groove 3-7 is provided on the upper end surface of the supporting wall located on the right side of the partition wall 3-2. A dust removal channel is provided at the lower end of the supporting wall located below the separation groove 3-7. The dust removal channel is trumpet-shaped. The heating layer inside the supporting wall heats the lower half of the separation groove 3-7.

[0034] Several groups of flue gas pipes 4 - 1 are installed inside the boiler drum 4 , and water cooling pipes are installed on both sides of the lower end of the boiler drum 4 , and the water cooling pipes are fixed to the inner wall of the boiler body 3 .

[0035] The inner walls of several groups of smoke pipes 4-1 are corrugated, one end of several groups of smoke pipes 4-1 is connected to the front smoke chamber, and the other end of several groups of smoke pipes 4-1 is connected to the rear smoke chamber. Drainage channels are horizontally opened inside the pipe walls at the lower ends of several groups of smoke pipes 4-1, and the drainage channels are connected to the inside of the smoke pipes 4-1, and the drainage channels are connected to the rear smoke chamber. A sewage pipe is installed inside the smoke pipe, and the sewage pipe is connected to the drainage channels in the several groups of smoke pipes 4-1.

[0036] The interior of the drum 4 is annular and is installed with at least two layers of smoke pipes 4-1 from the inside to the outside. In this embodiment, taking the installation of three layers of smoke pipes 4-1 as an example, the diameter of the smoke pipe 4-1 located at the center is 3 times the diameter of several groups of smoke pipes 4-1 in the outer layer. A booster plate 4-2 is fixedly installed inside the several groups of smoke pipes 4-1 near one end of the rear smoke chamber, and an air outlet is opened at the center of the booster plate 4-2.

[0037] Several groups of smoke pipes 4-1 located in the middle layer are connected to the smoke pipes 4-1 located in the center through pipe connections, the outer sides of several groups of smoke pipes 4-1 located in the middle layer are connected to several groups of smoke pipes 4-1 in the outermost layer, and two smoke pipes 4-1 in the middle layer are connected to one smoke pipe 4-1 in the outermost layer.

[0038] Working principle of the present invention:

[0039] When the water in the boiler drum 4 is heated, the grate 2 rotates and transfers the coal dropped from the coal hopper. The coal is burned in the combustion chamber driven by the grate 2 and produces high-temperature flue gas. The grate 2 discharges the dust produced by the combustion of the coal during its rotation, and the flue gas carries the coal dust into the burnout chamber.

[0040] The guide plate 3-1 and the partition wall 3-2 in the boiler body 3 guide the flue gas generated in the combustion chamber, so that the flue gas carrying coal dust enters the burnout chamber, and the fine particles of coal dust that have not yet been burned or have just been burned red are completely burned in the burnout chamber, thereby further heating the flue gas.

[0041] When the guide plate 3-1 guides the smoke in the combustion chamber, it absorbs the temperature in the combustion chamber and transfers it to the filter layer. The partition wall 3-2 separates the combustion chamber and the burnout chamber. The partition wall 3-2 absorbs the high temperature in the combustion chamber and the burnout chamber and heats the heating layer, thereby heating the heating layer in the supporting wall, thereby heating the lower half of the separation tank 3-7.

[0042] The further combustion of coal dust in the combustion chamber causes the temperature in the combustion chamber to further rise, so that the dust in the combustion chamber gains more movement speed, thereby causing the dust to collide with each other in the combustion chamber. Through the mutual coordinated collision between the dusts, the dusts are adsorbed on each other and form large dust particles, which makes it easier to filter the dust.

[0043] The flue gas that enters the combustion chamber and burns out enters channel I through the dust removal wall 3-5. When the flue gas passes through the dust removal wall 3-5, the pressure on the left side of the dust removal wall 3-5 increases due to the change in the flow channel, and the flue gas flow rate under the dust removal wall 3-5 and the separation wall 3-6 increases, thereby allowing the high-temperature dust particles to obtain greater kinetic energy. After the dust particles pass through the separation wall 3-6, they move to the lower right along the inclined direction of the partition wall 3-2, while the flue gas rises and enters channel I, thereby realizing the separation of the flue gas and dust particles.

[0044] Dust particles fall into the separation groove 3-7, and the heating layer further heats the air in the separation groove 3-7, causing the air in the separation groove 3-7 to expand due to the heat. The top of the separation groove 3-7 is squeezed by the flue gas, causing the dust particles to move to the bottom of the supporting wall driven by the expanding air, thereby separating the dust particles from the flue gas.

[0045] The flue gas enters the guide plate 3-1 along channel I and channel II, and enters the front flue gas chamber through the filtration layer, and enters the flue gas pipe 4-1 through the front flue gas chamber, so that the flue gas heats the water in the boiler drum 4 through the flue gas pipe 4-1. The inner wall of the flue gas pipe 4-1 is corrugated, so that the flue gas flows disorderly in the flue gas pipe 4-1, and then the flue gas fully exchanges heat with the water in the boiler drum 4 through the flue gas pipe.

[0046] As the smoke continues to enter and the booster plate 4-2 blocks the smoke, the pressure in the smoke pipe 4-1 increases. When the smoke in the smoke pipe 4-1 cools down and condenses, condensed water is generated in the smoke pipe 4-1 and passes through the heat part of the center smoke pipe 4-1 again, causing the pressure in the outer smoke pipe 4-1 to rise again, so that the condensed water generated in the smoke pipe 4-1 is squeezed out of the smoke pipe 4-1 through the drainage channel by high pressure.

[0047] The flue gas enters the rear flue gas chamber after the heat exchange, and enters the economizer under the attraction of the induced draft fan connected to the economizer.

[0048] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0049] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A step-by-step grate forced circulation coal-fired hot water boiler, the coal-fired hot water boiler comprising a base (1) and a boiler body (3), characterized in that: The base (1) is provided with a grate (2), the boiler body (3) is provided above the grate (2), a drum (4) is provided on the boiler body (3), and a dust filter component is provided inside the boiler body (3), wherein the dust filter component filters dust in the flue gas; One end of the grate (2) is located outside the boiler body (3), and the other part of the grate (2) is located inside the boiler body (3); a coal hopper is arranged outside the boiler body (3) and above the grate (2), and a guide plate (3-1) is arranged at one end inside the boiler body; the dust filter assembly comprises a partition wall (3-2), the partition wall (3-2) is arranged at the other end of the boiler body (3), and a transverse wall (3-3) is arranged on the side of the guide plate (3-1) close to the partition wall (3-2); The dust filter assembly comprises a supporting wall, the supporting wall is fixed to the inner end surface of the boiler body (3), the supporting wall is fixed to one end of the partition wall (3-2), a return plate (3-4) is arranged on the upper end surface of the partition wall (3-2) close to the guide plate (3-1), a dust removal wall (3-5) is arranged on the end of the cross wall (3-3) located above the supporting wall, a rounded corner is arranged on the end surface of the lower end of the dust removal wall (3-5) close to the partition wall (3-2), a separation wall (3-6) is arranged on the other end surface of the dust removal wall (3-5), and the other end of the separation wall (3-6) is sled-shaped; The upper end surface of the supporting wall is provided with a separation groove (3-7), the lower end of the supporting wall is provided with a dust removal channel below the separation groove (3-7), the dust removal channel is in a trumpet shape, a heating layer is provided inside the supporting wall, and the separation groove (3-7) is located outside the partition wall (3-2); The guide plate (3-1) has a triangular cross section, the guide plate (3-1) is hollow inside, sand is stored inside the guide plate (3-1), and the sand is combined into a filter layer. A front smoke chamber is arranged above the guide plate (3-1), and the front smoke chamber is connected to the boiler drum (4) pipeline. A plurality of groups of smoke pipes (4-1) are arranged inside the drum (4), the inner walls of the plurality of groups of smoke pipes (4-1) are corrugated, one end of the plurality of groups of smoke pipes (4-1) is connected to the front smoke chamber, the other end of the plurality of groups of smoke pipes (4-1) is connected to the rear smoke chamber, and a drainage channel is horizontally arranged inside the lower end tube wall of the plurality of groups of smoke pipes (4-1), the drainage channel is connected to the inside of the smoke pipe (4-1), and the drainage channel is connected to the rear smoke chamber; The drum (4) is annularly arranged inside with at least two layers of smoke pipes (4-1) from the inside to the outside, the diameter of the smoke pipe (4-1) located at the center is three times the diameter of the outer plurality of groups of smoke pipes (4-1), a booster plate (4-2) is arranged inside each of the plurality of groups of smoke pipes (4-1) near one end of the rear smoke chamber, an air outlet is provided at the center of the booster plate (4-2), the outer plurality of groups of smoke pipes (4-1) of the centrally arranged smoke pipe (4-1) are connected to the centrally arranged smoke pipe (4-1), and the outer sides of the outer plurality of groups of smoke pipes (4-1) are connected to the outer plurality of groups of smoke pipes (4-1); A blower is provided on one side of the base (1), and the blower is connected to the grate (2) pipeline. A water inlet pipe and a water outlet pipe are provided on the boiler drum (4), and the water inlet pipe is connected to the water pump pipeline. The rear flue gas chamber is connected to the economizer pipeline.

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