Biomass boiler with hearth and evaporation box supported by pipelines and design verification method of biomass boiler

Abstract

The invention discloses a biomass boiler with a hearth and an evaporation box supported by pipelines and a design verification method of the biomass boiler. The biomass boiler comprises a combustion fire grate, the hearth, an evaporator, a lower header, an upper header, a first downcomer, a second downcomer, an ascending pipe and a hearth water cooling wall. A hearth and an evaporator are connected through a first descending pipe, a second descending pipe, an ascending pipe and a hearth water cooling wall to form an integrated structure, the hearth and the evaporator are supported through pipelines, meanwhile, a geometric model of the boiler is constructed, constraint is set, a combustion simulation solver is arranged, and therefore finite element analysis is conducted on the biomass boiler. The constraint comprises uniform distribution of internal pipe wall pressure surface load and set temperature, and the stress, strain and displacement of the biomass boiler under the high-temperature operation working condition can be accurately simulated. According to the design, the hearth and the evaporator can be supported through all the pipelines, the biomass boiler can be large, and the operation condition of the biomass boiler under the high-temperature operation working condition can be accurately simulated.

Description

TECHNICAL FIELD

[0001] The present application relates to a biomass boiler, in particular to a biomass boiler with a pipeline supporting furnace and evaporation box and a design verification method thereof. BACKGROUND

[0002] With increasing concerns about dependence on fossil energy and environmental problems, biomass energy as a renewable clean energy, its utilization technology has been widely valued. Biomass boiler as a core equipment for converting biomass energy has been applied to industrial heating, regional heating, power generation and domestic hot water supply and other fields.

[0003] Biomass boiler as a device for generating heat or steam using renewable biomass fuel (such as wood chips, straw, particles, etc.), is increasingly widely used in the field of heating, industrial processing, etc. Its core components usually include a combustion furnace and an evaporation box arranged on a steel frame.

[0004] In the traditional design of biomass boiler, the furnace is the core high-temperature area for fuel combustion, and the evaporation box is the key pressure-bearing component of the water circulation system. The huge self-weight, internal working fluid weight and thermal stress, vibration and wind load / seismic load generated during operation usually need to rely on additional, independent steel structure frames or support systems to bear the self-weight, internal working fluid weight and thermal stress generated during operation. Such support structures are usually welded or bolted by section steel (such as I-beam, channel steel).

[0005] Although such biomass boilers have good carbon neutrality and environmental protection, they still have the following defects:

[0006] 1. The supporting steel frame occupies a certain peripheral space, limiting the large-scale of the biomass boiler.

[0007] 2. The biomass boiler has a high temperature during use, and the stress state is quite different from that at room temperature. The traditional support structure does not fully consider the high-temperature operating condition, resulting in thermal stress concentration, structural instability and accelerated material failure, etc. Systematic risks, poor safety.

[0008] The information disclosed in this BACKGROUND section is only intended to increase an understanding of the general background of the application and should not be construed as recognition or admission that this information is prior art to the application. SUMMARY

[0009] The purpose of the present application is to overcome the shortcomings of the prior art, such as difficult to large-scale and poor safety, and to provide a biomass boiler with a pipeline supporting furnace and evaporation box, which can be large-scale and has high safety, and a design verification method thereof.

[0010] To achieve the above object, the technical solution of the present application is:

[0011] A biomass boiler supporting a furnace and an evaporation box, the boiler comprising: a combustion grate, a furnace, an evaporator, a lower header, an upper header, a first downcomer, a second downcomer, a riser and a furnace water wall;

[0012] The combustion grate, the lower header, the furnace, the upper header and the evaporator are sequentially arranged from bottom to top;

[0013] The furnace is a membrane wall furnace, the lower header, the upper header and the first downcomer form a cuboid tube frame of integral structure, the cuboid tube frame is arranged on the outside of the furnace, and the furnace water wall is arranged on the inside of the furnace;

[0014] One end of the second downcomer and the riser is fixedly connected with the evaporator, the other end of the second downcomer and the riser is fixedly connected with the upper header, and the inside of the evaporator is in communication with the inside of the upper header through the second downcomer and the riser;

[0015] One end of the first downcomer and the furnace water wall is fixedly connected with the upper header, the other end of the first downcomer and the furnace water wall is fixedly connected with the lower header, and the inside of the upper header is in communication with the inside of the lower header through the first downcomer and the furnace water wall.

[0016] The lower header is connected with the upper header through at least four first downcomers to form an integral structure;

[0017] The lower header comprises two lower longitudinal headers and two lower transverse headers, and the two lower longitudinal headers and the two lower transverse headers form four edges of the bottom of the cuboid tube frame;

[0018] The upper header comprises two upper longitudinal headers and two upper transverse headers, and the two upper longitudinal headers and the two upper transverse headers form four edges of the top of the cuboid tube frame;

[0019] One end of the four first downcomers is fixedly connected with two ends of the two lower longitudinal headers respectively, and the other end of the four first downcomers is fixedly connected with two ends of the two upper longitudinal headers respectively.

[0020] The boiler comprises five furnace water walls, four of which form four side walls of the cuboid tube frame respectively, and the other furnace water wall is arranged in the middle of the furnace in the vertical direction;

[0021] The liquid inlets of the five furnace water walls are in communication with the lower header, and the liquid outlets of the five furnace water walls are in communication with the upper header.

[0022] A design verification method for a biomass boiler with pipe-supported furnace and evaporator, the design verification method comprising the following steps:

[0023] S1. Construct a boiler geometric model by importing the 3D drawings of the boiler furnace into the simulation software for simplification, defining material properties for the model, and then generating a meshed boiler geometric model.

[0024] S2. Establish constraints on the boiler geometric model and apply external loads simultaneously;

[0025] S3. Set up a combustion simulation solver and conduct multiple combustion experiments in the combustion environment of the biomass fuel simulation boiler. Collect relevant combustion experimental data during the experiment, analyze the experimental results, and set combustion and static stress analysis data in the simulation software based on the analysis results.

[0026] S4. Perform finite element analysis on the model. Use the solver generated in S3 to solve the boiler geometric model and calculate the mechanical properties of the model, including stress and strain. In terms of model selection, models involved in biomass boiler combustion include thermal effects and models for calculating free body forces. After setting, integrate the data in the software to form a solver.

[0027] S5. Post-process and analyze the results of S4, including checking the stress, strain cloud diagrams, and displacement cloud diagrams, and determine the optimal combination of the first downcomer, the second downcomer, and the riser. At the same time, evaluate the above combination to determine whether the stress and strain of the boiler geometric model meet the mechanical performance requirements of the equipment. If not, return to S1 to further improve and optimize the boiler geometric model by adjusting the position of each pipe or increasing the number of pipes. Then, verify again in S4 until the simulation results meet the mechanical performance requirements. At this point, the simulation design is complete.

[0028] In S1, the main parts used for simulation analysis include the biomass fuel combustion zone and the furnace zone;

[0029] The simplified processing steps include retaining the main load-bearing components of the biomass boiler while omitting the furnace water-cooled wall;

[0030] The meshing step includes first dividing the boiler geometric model into tetrahedral meshes, then converting the tetrahedral meshes into hexahedral meshes, and then densifying the welding nodes within the boiler geometric model.

[0031] In S3, the constraints include: water is installed inside the evaporator, lower header, upper header, first downcomer, second downcomer, riser and furnace water-cooled wall in the boiler geometric model; and insulation material is installed in the evaporator, lower header, upper header, first downcomer, second downcomer and riser.

[0032] The external loads include applying a uniformly distributed pressure surface load to the inner wall of the boiler geometry model, applying a set temperature to the structural components of the boiler geometry model, and applying the weight of water to the pipes and internal structures.

[0033] The uniformly distributed internal pipe wall pressure surface load is 0.8 to 2.5 MPa, and the set temperature is 175 to 226 °C.

[0034] In S5, four of the first downcomers are respectively installed at the front and rear of the biomass boiler. When the displacement cloud diagram shows that the overall stress value exceeds the design allowable value or the maximum displacement of the pipe exceeds the design allowable value, another row of first downcomers is added in the middle of the boiler.

[0035] When the stress diagram shows that the local stress peak exceeds the design allowable value, the wall thickness of the corresponding local structure and related pipelines should be increased.

[0036] The overall stress value does not exceed the allowable stress of the material, and the allowable value of the local stress peak value is 3 times the allowable stress.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. In this invention, a biomass boiler with a pipe-supported furnace and evaporator is constructed by interconnecting the furnace and evaporator via a first downcomer, a second downcomer, a riser, and a water-cooled furnace wall to form an integrated structure. The furnace and evaporator are supported by various pipes, eliminating the need for an additional supporting steel frame and allowing for larger-scale biomass boilers. Therefore, this design enables the furnace and evaporator to be supported by various pipes, allowing for larger-scale biomass boilers.

[0039] 2. In the design verification method of a biomass boiler with pipe-supported furnace and evaporator of the present invention, a finite element analysis of the biomass boiler is performed by constructing a boiler geometric model and setting constraints, and then setting a combustion simulation solver. The constraints include uniformly distributed internal pipe wall pressure surface load and set temperature, which can accurately simulate the stress, strain and displacement of the biomass boiler under high-temperature operating conditions. Therefore, this design can accurately simulate the operating conditions of a biomass boiler under high-temperature operating conditions.

[0040] 3. In the design verification method of a biomass boiler with pipe-supported furnace and evaporator of the present invention, after obtaining the stress, strain and displacement of the biomass boiler under high-temperature operating conditions, the boiler geometric model can be further improved and optimized by adjusting the position of each pipe or increasing the number of pipes. Therefore, this design can further improve and optimize the boiler geometric model, effectively improving safety. Attached Figure Description

[0041] Figure 1 This is the front view of the present invention.

[0042] Figure 2 This is a side view of the present invention.

[0043] Figure 3 This is a perspective view of the present invention.

[0044] Figure 4 This is a simplified schematic diagram of the present invention.

[0045] Figure 5 This is a schematic diagram of the solid mesh of the boiler geometric model in the method described in this invention.

[0046] Figure 6 This is a schematic diagram of static displacement in the method described in this invention.

[0047] Figure 7 This is a schematic diagram of static strain in the method described in this invention.

[0048] In the diagram: 1. Combustion grate; 2. Furnace chamber; 3. Evaporator; 4. Lower header; 41. Lower longitudinal header; 42. Lower transverse header; 5. Upper header; 51. Upper longitudinal header; 52. Upper transverse header; 6. First downcomer; 7. Second downcomer; 8. Ascending pipe; 9. Furnace water-cooled wall; 10. Rectangular tube rack; 9. Furnace water-cooled wall. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] Example 1:

[0051] See Figures 1 to 4 A biomass boiler with a pipe-supported furnace and evaporator, the boiler comprising: a combustion grate 1, a furnace 2, an evaporator 3, a lower header 4, an upper header 5, a first downcomer 6, a second downcomer 7, an ascender 8, and a furnace water-cooled wall 9.

[0052] The combustion grate 1, lower header 4, furnace 2, upper header 5, and evaporator 3 are arranged sequentially from bottom to top;

[0053] The furnace chamber 2 is a membrane furnace chamber. The lower header 4, the upper header 5 and the first downcomer 6 form an integral rectangular tube frame 10. The rectangular tube frame 10 is located on the outside of the furnace chamber 2, and the furnace water-cooled wall 9 is located on the inside of the furnace chamber 2.

[0054] One end of the second downpipe 7 and the riser 8 is fixedly connected to the evaporator 3, and the other end of the second downpipe 7 and the riser 8 is fixedly connected to the upper header 5. The interior of the evaporator 3 is connected to the interior of the upper header 5 through the second downpipe 7 and the riser 8.

[0055] One end of the first downcomer 6 and the furnace water-cooled wall 9 is fixedly connected to the upper header 5, and the other end of the first downcomer 6 and the furnace water-cooled wall 9 is fixedly connected to the lower header 4. The interior of the upper header 5 is connected to the interior of the lower header 4 through the first downcomer 6 and the furnace water-cooled wall 9.

[0056] With this structure, the boiler no longer needs an additional steel frame to support the weight, reducing the size and floor space of the boiler. At the same time, within the same space, the furnace 2 in this embodiment has a larger space than the prior art, and is more adaptable to different types of biomass fuels and agricultural and forestry waste.

[0057] The lower header 4 is connected to the upper header 5 through at least four first downcomers 6 to form an integral structure;

[0058] The lower header 4 includes two lower longitudinal headers 41 and two lower transverse headers 42, and the two lower longitudinal headers 41 and the two lower transverse headers 42 form the four sides of the bottom of the rectangular tube frame 10.

[0059] The upper header 5 includes two upper longitudinal headers 51 and two upper transverse headers 52, and the two upper longitudinal headers 51 and the two upper transverse headers 52 form the four sides of the top of the rectangular tube frame 10.

[0060] One end of each of the four first downcomer tubes 6 is fixedly connected to both ends of the two lower longitudinal collection boxes 41, and the other end of each of the four first downcomer tubes 6 is fixedly connected to both ends of the two upper longitudinal collection boxes 51.

[0061] The boiler includes five furnace water-cooled walls 9, four of which form the four side walls of the rectangular tube frame 10, and the other furnace water-cooled wall 9 is arranged vertically in the middle of the furnace 2.

[0062] The liquid inlets of the five furnace water-cooled walls 9 are all connected to the lower header 4, and the liquid outlets of the five furnace water-cooled walls 9 are all connected to the upper header 5.

[0063] When the boiler is in use, the water in the furnace water-cooled wall 9 is heated and transformed into a steam-water mixture with bubbles. The water density in the first downcomer 6 and the second downcomer 7 is greater than that of the steam-water mixture, causing the steam-water mixture to flow upward into the first downcomer 6 and the second downcomer 7. At the same time, the water flows downward into the furnace water-cooled wall 9. After entering the first downcomer 6 and the second downcomer 7, the steam-water mixture begins to cool. After cooling, the steam-water mixture turns into water. At the same time, the water enters the furnace water-cooled wall 9 and is heated and transformed into a steam-water mixture with bubbles, forming a natural water circulation system. In turn, by absorbing the heat generated by the boiler combustion, a complete natural water circulation system is formed.

[0064] Example 2:

[0065] A design verification method for a biomass boiler with pipe-supported furnace and evaporator, the design verification method comprising the following steps:

[0066] S1, see also Figure 5 To construct a boiler geometric model, the three-dimensional drawings of the boiler furnace are imported into the simulation software for simplification. Material properties are defined for the model, and then a meshed boiler geometric model is generated.

[0067] S2. Establish constraints on the boiler geometric model and apply external loads simultaneously;

[0068] S3. Set up a combustion simulation solver and conduct multiple combustion experiments in the combustion environment of the biomass fuel simulation boiler. Collect relevant combustion experimental data during the experiment, analyze the experimental results, and set combustion and static stress analysis data in the simulation software based on the analysis results.

[0069] S4. Perform finite element analysis on the model. Use the solver generated in S3 to solve the boiler geometric model and calculate the mechanical properties of the model, including stress and strain. In terms of model selection, models involved in biomass boiler combustion include thermal effects and models for calculating free body forces. After setting, integrate the data in the software to form a solver.

[0070] S5, see also Figures 6 to 7 The results of S4 are post-processed and analyzed, including viewing stress, strain cloud diagrams, and displacement cloud diagrams to determine the optimal combination of the first downcomer 6, the second downcomer 7, and the riser 8. At the same time, the above combination is evaluated to determine whether the stress and strain of the boiler geometric model meet the mechanical performance requirements of the equipment. If not, the process returns to S1 to further improve and optimize the boiler geometric model by adjusting the position of each pipe or increasing the number of pipes. The simulation is then verified again in S4 until the simulation results meet the mechanical performance requirements. At this point, the simulation design is complete.

[0071] This model is a stress structure under heating conditions. The stress-bearing component is a steel pipe, which is subjected to the pressure of the internal medium. At the same time, the medium is continuously heated until the design pressure and design temperature are reached. All stresses are connected and a reasonable water circulation ensures that the stress-bearing components are under synchronous temperature changes. In this way, the thermal expansion and contraction of the stress-bearing components due to temperature changes are also synchronous, and thermal stress will not be generated.

[0072] In S1, the main parts used for simulation analysis include the biomass fuel combustion zone and the furnace zone;

[0073] The simplified processing steps include retaining the main load-bearing components of the biomass boiler while omitting the furnace water-cooled wall 9.

[0074] See Figure 5 The meshing step includes first dividing the boiler geometric model into tetrahedral meshes, then converting the tetrahedral meshes into hexahedral meshes, and then densifying the welding nodes within the boiler geometric model.

[0075] In S3, the constraints include: water is installed inside the evaporator 3, lower header 4, upper header 5, first downcomer 6, second downcomer 7, riser 8 and furnace water-cooled wall 9 in the boiler geometric model; and insulation material is installed in the evaporator 3, lower header 4, upper header 5, first downcomer 6, second downcomer 7 and riser 8.

[0076] The external loads include applying a uniformly distributed pressure surface load to the inner wall of the boiler geometry model, applying a set temperature to the structural components of the boiler geometry model, and applying the weight of water to the pipes and internal structures.

[0077] See Figures 6 to 7 In S5, four of the first downcomer pipes 6 are respectively installed at the front and rear of the biomass boiler. When the displacement cloud diagram shows that the overall stress value exceeds the design allowable value or the maximum displacement of the pipe exceeds the design allowable value, another row of first downcomer pipes 6 is added in the middle of the boiler.

[0078] When the stress diagram shows that the local stress peak exceeds the design allowable value, the wall thickness of the corresponding local structure and related pipelines should be increased.

[0079] The material properties of the model include that the lower header 4, upper header 5, first downcomer 6, second downcomer 7, riser 8 and furnace water-cooled wall 9 are made of 20 / GB / T3087, and the evaporator 3 is made of Q345R / GB / 713.

[0080] The uniformly distributed internal pipe wall pressure surface load can be any one of 0.8MPa, 1.0MPa, 1.25MPa, 1.6MPa or 2.5MPa;

[0081] The set temperature can be any one of 175℃, 184℃, 193℃, 204℃ or 226℃;

[0082] The uniformly distributed internal pipe wall pressure surface load is 0.8 to 2.5 MPa, and the set temperature is 175 to 226 °C.

[0083] The overall stress value does not exceed the allowable stress of the material, and the allowable value of the local stress peak value is 3 times the allowable stress;

[0084]

[0085]

[0086] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A biomass boiler with pipe-supported furnace and evaporator, characterized in that, The boiler includes: a combustion grate (1), a furnace (2), an evaporator (3), a lower header (4), an upper header (5), a first downcomer (6), a second downcomer (7), an upcomer (8), and a furnace water-cooled wall (9); The combustion grate (1), lower header (4), furnace (2), upper header (5), and evaporator (3) are arranged sequentially from bottom to top; The furnace (2) is a membrane furnace. The lower header (4), upper header (5) and first downcomer (6) form an integral rectangular tube frame (10). The rectangular tube frame (10) is located on the outside of the furnace (2), and the furnace water-cooled wall (9) is located on the inside of the furnace (2). One end of the second downpipe (7) and the riser (8) is fixedly connected to the evaporator (3), and the other end of the second downpipe (7) and the riser (8) is fixedly connected to the upper header (5). The interior of the evaporator (3) is connected to the interior of the upper header (5) through the second downpipe (7) and the riser (8). One end of the first downcomer (6) and the furnace water-cooled wall (9) is fixedly connected to the upper header (5), and the other end of the first downcomer (6) and the furnace water-cooled wall (9) is fixedly connected to the lower header (4). The interior of the upper header (5) is connected to the interior of the lower header (4) through the first downcomer (6) and the furnace water-cooled wall (9).

2. A biomass boiler with pipe-supported furnace and evaporator according to claim 1, characterized in that, The lower header (4) is connected to the upper header (5) through at least four first downcomers (6) to form an integral structure; The lower header (4) includes two lower longitudinal headers (41) and two lower transverse headers (42), and the two lower longitudinal headers (41) and the two lower transverse headers (42) form the four sides of the bottom of the rectangular tube frame (10); The upper header (5) includes two upper longitudinal headers (51) and two upper transverse headers (52), and the two upper longitudinal headers (51) and the two upper transverse headers (52) form the four sides of the top of the rectangular tube frame (10). One end of each of the four first downcomers (6) is fixedly connected to the two ends of the two lower longitudinal collection boxes (41), and the other end of each of the four first downcomers (6) is fixedly connected to the two ends of the two upper longitudinal collection boxes (51).

3. A biomass boiler with pipe-supported furnace and evaporator as described in claim 1, characterized in that, The boiler includes five furnace water-cooled walls (9), four of which form the four side walls of the rectangular tube frame (10), and the other furnace water-cooled wall (9) is arranged vertically in the middle of the furnace (2). The liquid inlets of the five furnace water-cooled walls (9) are all connected to the lower header (4), and the liquid outlets of the five furnace water-cooled walls (9) are all connected to the upper header (5).

4. A design verification method for a biomass boiler with pipe-supported furnace and evaporator as described in any one of claims 1 to 3, characterized in that: The design verification method includes the following steps: S1. Construct a boiler geometric model by importing the 3D drawings of the boiler furnace into the simulation software for simplification, defining material properties for the model, and then generating a meshed boiler geometric model. S2. Establish constraints on the boiler geometric model and apply external loads simultaneously; S3. Set up a combustion simulation solver and conduct multiple combustion experiments in the combustion environment of the biomass fuel simulation boiler. Collect relevant combustion experimental data during the experiment, analyze the experimental results, and set combustion and static stress analysis data in the simulation software based on the analysis results. S4. Perform finite element analysis on the model. Use the solver generated in S3 to solve the boiler geometric model and calculate the mechanical properties of the model, including stress and strain. In terms of model selection, models involved in biomass boiler combustion include thermal effects and models for calculating free body forces. After setting, integrate the data in the software to form a solver. S5. Post-process and analyze the results of S4, including checking the stress, strain cloud diagram and displacement cloud diagram, and determine the optimal combination of the first downcomer (6), the second downcomer (7) and the riser (8). At the same time, determine whether the stress and strain of the boiler geometric model meet the mechanical performance requirements of the equipment. If not, return to S1 to further improve and optimize the boiler geometric model by adjusting the position of each pipe or increasing the number of pipes. Then, verify again in S4 until the simulation results meet the mechanical performance requirements. At this time, the simulation design is completed.

5. The design verification method for a biomass boiler with pipe-supported furnace and evaporator according to claim 4, characterized in that, In S1, the main parts used for simulation analysis include the biomass fuel combustion zone and the furnace zone; The simplified processing steps include retaining the main load-bearing components of the biomass boiler while omitting the furnace water-cooled wall (9); The meshing step includes first dividing the boiler geometric model into tetrahedral meshes, then converting the tetrahedral meshes into hexahedral meshes, and then densifying the welding nodes within the boiler geometric model.

6. The design verification method for a biomass boiler with pipe-supported furnace and evaporator according to claim 4, characterized in that, In the S3, the constraint includes that water is installed inside the evaporator (3), lower header (4), upper header (5), first downcomer (6), second downcomer (7), riser (8) and furnace water-cooled wall (9) in the boiler geometric model, and thermal insulation material is installed in the evaporator (3), lower header (4), upper header (5), first downcomer (6), second downcomer (7) and riser (8); The external loads include applying a uniformly distributed pressure surface load to the inner wall of the boiler geometry model, applying a set temperature to the structural components of the boiler geometry model, and applying the weight of water to the pipes and internal structures.

7. The design verification method for a biomass boiler with pipe-supported furnace and evaporator according to claim 6, characterized in that, The uniformly distributed internal pipe wall pressure surface load is 0.8 to 2.5 MPa, and the set temperature is 175 to 226 °C.

8. The design verification method for a biomass boiler with pipe-supported furnace and evaporator according to claim 4, characterized in that, In S5, four of the first downcomers (6) are respectively set at the front and rear of the biomass boiler. When the displacement cloud diagram shows that the overall stress value exceeds the design allowable value or the maximum displacement of the pipeline exceeds the design allowable value, another row of first downcomers (6) is added in the middle of the boiler. When the stress diagram shows that the local stress peak exceeds the design allowable value, the wall thickness of the corresponding local structure and related pipelines should be increased.

9. A design verification method for a biomass boiler with pipe-supported furnace and evaporator as described in claim 8, characterized in that, The overall stress value does not exceed the allowable stress of the material, and the allowable value of the local stress peak value is 3 times the allowable stress.

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