A space free fluidization combustion method driven by kinetic energy conversion

Abstract

The application provides a space free-flowing combustion method driven by kinetic energy conversion, and relates to the technical field of boiler combustion, and comprises the following steps: calculating total feeding amount according to total fuel demand of a boiler, and respectively feeding fuel to a bottom bed and a space pneumatic screening bed through a layered feeding device, and simultaneously igniting; feeding air to the bottom bed and the space pneumatic screening bed through primary air and secondary air according to total air required by the boiler combustion; adjusting the falling or rising speed of the fuel by adjusting the ratio of the primary air to the secondary air according to the particle size of the fuel; monitoring the smoke temperature in real time, and feeding the layered feeding device when the smoke temperature reaches the ignition point of the fuel; and under the action of buoyancy, gravity and suction force, the coal particles on the space pneumatic screening bed rely on the change of the kinetic energy of the coal particles. The application enables the coal particles to form microcirculation in the furnace, improves the burnout rate of the coal particles, reduces the carbon content of the ash, reduces the wear of the structure of the boiler, and prolongs the stable operation period.

Description

Technical Field

[0001] This invention relates to the field of boiler combustion technology, specifically to a spatial free-fluidization combustion method driven by kinetic energy conversion. Background Technology

[0002] Currently, medium-sized (75-300 tons of steam) high-efficiency coal-fired boilers in my country generally adopt circulating fluidized bed boiler technology, which has advantages in high thermal efficiency (average 90%), strong adaptability to coal types, low original pollutant emission values, and high in-furnace desulfurization and denitrification efficiency.

[0003] In related technologies, because fuel and bed material participate in the circulation process together during the reaction, a large amount of material is circulated at a high rate, which directly leads to high energy consumption and strong wear. Summary of the Invention

[0004] This invention provides a spatial free-flowing combustion method driven by kinetic energy conversion, which can effectively solve the problems of high energy consumption and strong wear of materials.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] Embodiments of the present invention provide a space free-flowing combustion method driven by kinetic energy conversion, comprising:

[0007] The total feed rate is calculated based on the total fuel demand of the boiler, and fuel is supplied to the bottom bed and the space pneumatic screening bed through a layered feeding device, while ignition is carried out simultaneously.

[0008] Based on the total air volume required for boiler combustion, air is supplied to the bottom bed and the spatial pneumatic screening bed through primary air and secondary air;

[0009] The rate at which the fuel descends or ascends is adjusted by regulating the ratio of primary to secondary air, depending on the fuel particle size.

[0010] Real-time monitoring of flue gas temperature; when the flue gas temperature reaches the ignition point of the fuel, the stratified feeding device is activated to feed the fuel.

[0011] Under the influence of buoyancy, gravity, and suction, the coal particles on the space pneumatic screening bed generate a free fluidization state in the space by relying on the change of their own kinetic potential energy, thereby forming a micro-circulation in the furnace.

[0012] Furthermore, the bottom bed is disposed inside the furnace, the furnace including a front wall and a rear wall, the front wall of the furnace being connected to the spatial pneumatic screening bed.

[0013] Furthermore, the spatial pneumatic screening bed is located on the upper layer of the bottom bed, and the spatial pneumatic screening bed has an n-layer bed structure, with each of the n layers connected to the front wall of the furnace.

[0014] The space pneumatic screening bed includes a first bed, a second bed, and an nth bed;

[0015] The first layer of the bed is provided with a first layer of bed surface;

[0016] The second bunk bed is equipped with a second bunk bed surface;

[0017] The nth layer of the bed is provided with an nth layer of bed surface.

[0018] Furthermore, the layered feeding device is disposed on the front wall of the furnace and is connected to the interior of the furnace;

[0019] The layered feeding device includes a bottom bed feeding device, a first layer bed feeding device, a second layer bed feeding device, and an nth layer feeding device;

[0020] The bottom bed feeding device is located on the upper layer of the bottom bed;

[0021] The first bed feeding device is located on the upper layer of the first bed;

[0022] The second bed feeding device is located on the upper layer of the second bed;

[0023] The nth layer feeding device is located on the upper layer of the nth layer bed.

[0024] Furthermore, the primary air includes primary air for the bottom bed, primary air for the first bed layer, primary air for the second bed layer, and primary air for the nth bed layer;

[0025] The primary air in the bottom bed is located below the bottom bed and is in communication with the interior of the furnace;

[0026] The primary air of the first bed is disposed on the front wall of the furnace, located below the bed surface of the first bed, and communicates with the interior of the first bed;

[0027] The second bed of primary air is disposed on the front wall of the furnace, located below the bed surface of the second bed, and communicates with the interior of the second bed;

[0028] The primary air of the nth bed is located on the front wall of the furnace, below the surface of the nth bed, and communicates with the interior of the nth bed.

[0029] Furthermore, the secondary air is disposed on the front wall of the furnace and communicates with the interior of the furnace; the secondary air includes a first bed secondary air, a second bed secondary air and an nth bed secondary air;

[0030] The secondary air of the first bed is located above the first bed feeding device;

[0031] The secondary air of the second bed is located above the feeding device of the second bed;

[0032] The secondary air of the nth bed is located above the nth feeding device.

[0033] Furthermore, the feed rate of the bottom bed is 30-40% of the total boiler fuel demand.

[0034] Furthermore, the primary air supply to the bed is 30-40% of the total air volume required for boiler combustion; the primary air supply direction to the bed is perpendicular to the bed surface, supplying air from the bottom of the bed to the bed surface.

[0035] Furthermore, the inclination angle of the bed surface of the first to nth layers of the spatial pneumatic screening bed decreases layer by layer;

[0036] The distance between the first to the nth layers of the spatial pneumatic screening bed and the rear wall of the furnace increases with each layer.

[0037] The gap between the first to the nth layers of the spatial pneumatic screening bed increases progressively.

[0038] Furthermore, the space free-flowing combustion method driven by kinetic energy conversion also includes:

[0039] The supply module is used to calculate the feed rate of the bottom bed based on the total fuel demand of the boiler, and to supply fuel to the bottom bed and the space pneumatic screening bed through the layered feeding device.

[0040] The air supply module is used to supply air to the bottom bed and the space pneumatic screening bed through primary air and secondary air according to the total air volume required for boiler combustion.

[0041] The adjustment module regulates the descent and ascent speed of the fuel by adjusting the ratio of primary air to secondary air based on the fuel particle size.

[0042] The detection module is used to monitor the flue gas temperature in real time. When the flue gas temperature reaches the ignition point of the fuel, it will cause the stratified feeding device to feed the fuel.

[0043] The above-described solution of the present invention has at least the following beneficial effects:

[0044] The spatial free-flowing combustion method driven by kinetic energy conversion described in this invention enables fuel and air to be distributed among different bed layers, reducing the power of the primary air blower in the bottom bed. Simultaneously, it achieves staged combustion of fuel and air, lowering combustion temperature and the possibility of fuel coking, and reducing the generation of nitrogen oxides. Coal particles can form a micro-circulation within the furnace, achieving fuel circulation without relying on external circulation equipment, reducing wear on the boiler structure and extending the stable operation cycle. It can reduce the power of large blowers, reduce the boiler footprint, and eliminate the need for external circulation equipment, thus reducing investment costs and system energy consumption. The free-flowing of coal particles extends their combustion path within the boiler, facilitating complete combustion, and through multi-stage bed arrangement, it can enhance the boiler's overload stable combustion capability. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the free fluidized bed arrangement involved in the embodiments of the present invention;

[0046] Figure 2 This is a schematic diagram illustrating the energy of coal particles involved in an embodiment of the present invention;

[0047] Figure 3 This is the first case of the coal particle movement trajectory involved in the embodiments of the present invention;

[0048] Figure 4 This is the second scenario regarding the coal particle trajectory in this embodiment of the invention;

[0049] Figure 5 This is the third case of coal particle movement trajectory involved in the embodiments of the present invention.

[0050] Explanation of reference numerals in the attached figures:

[0051] 1. Bottom bed; 2. Furnace chamber; 3. Spatial pneumatic screening bed; 4. Primary air; 5. Secondary air; 6. Layered feeding device; 21. Front wall of furnace chamber; 22. Rear wall of furnace chamber; 31. First layer bed; 32. Second layer bed; 33. nth layer bed; 41. Bottom bed primary air; 42. First layer bed primary air; 43. Second layer bed primary air; 44. nth layer bed primary air; 51. First layer bed secondary air; 52. Second layer bed secondary air; 53. nth layer bed secondary air; 61. Bottom bed feeding device; 62. First layer bed feeding device; 63. Second-layer bed feeding device; 64. nth-layer feeding device; 311. First-layer bed surface; 321. Second-layer bed surface; 331. nth-layer bed surface; a. Inclination angle of the first-layer bed surface; b. Inclination angle of the second-layer bed surface; c. Inclination angle of the nth-layer bed surface; d. Distance between the first-layer bed and the rear wall of the furnace; e. Distance between the second-layer bed and the rear wall of the furnace; f. Distance between the nth-layer bed and the rear wall of the furnace; dl. Coal particle size; m. Inner gap of the bed layer; m1. Inner gap of the lower bed layer; m2. Inner gap of the upper bed layer. Detailed Implementation

[0052] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0053] like Figures 1 to 5 As shown, an embodiment of the present invention provides a spatial free-flowing combustion method driven by kinetic energy conversion, characterized by comprising the following steps:

[0054] The total feed rate is calculated based on the total fuel demand of the boiler, and fuel is supplied to the bottom bed 1 and the space pneumatic screening bed 3 through the layered feeding device 6, while ignition is carried out simultaneously.

[0055] According to the total air volume required for boiler combustion, air is supplied to the bottom bed 1 and the spatial pneumatic screening bed 3 through primary air 4 and secondary air 5.

[0056] The descent or ascent speed of the fuel is adjusted by regulating the ratio of primary air 4 to secondary air 5, depending on the fuel particle size.

[0057] Real-time monitoring of flue gas temperature; when the flue gas temperature reaches the ignition point of the fuel, the stratified feeding device 6 is activated to feed the fuel.

[0058] Under the influence of buoyancy, gravity, and suction, the coal particles on the space pneumatic screening bed 3 generate a free fluidization state in the space by relying on the change of their own kinetic potential energy, thereby forming a micro-circulation in the furnace.

[0059] In this embodiment of the invention, stable combustion and turbulent combustion through bottom bed ignition provide upward flow of high-temperature flue gas; through feeding on the spatial pneumatic screening bed and the dedicated ratio of primary and secondary air, the coal particles on the spatial pneumatic screening bed achieve free-fluidization combustion; firstly, fuel enters the furnace 2 from the layered feeding device 6, falls onto the bottom bed 1 and the spatial pneumatic screening bed 5, and is ignited on the bottom bed 1; then, primary air 4 and secondary air 5 supply air to the bottom bed 1 and the spatial pneumatic screening bed 3; when the generated high-temperature flue gas moves upward onto the spatial pneumatic screening bed 3... When the flue gas temperature measuring point detects that the flue gas temperature has reached the ignition point of the coal type, a signal is given to the stratified feeding device 6 to allow feeding. When passing through the gaps on the surface of the spatial pneumatic screening bed 3, due to the small gaps, the pressure head at this point will increase, small coal particles will be suspended, and large particles will remain on the surface of the spatial pneumatic screening bed 3, forming a screening effect. In addition, due to the influence of the gravity of the large particles, when the inclination angle of the bed surface is between 20° and 40°, the large particles will roll down due to their own weight and enter the bottom bed 1 or the next layer of spatial pneumatic screening bed 3 for combustion. The secondary air 5 is arranged in the air... Above the pneumatic screening bed 3, the oxygen required for CO produced by incomplete combustion and unburned coal particles is provided. It also creates convection with the primary air and high-temperature flue gas, disturbing the movement of coal particles and the flow of flue gas, extending the combustion path, and ensuring complete combustion of coal particles. By arranging primary air 4 and secondary air 5, fuel and air are distributed, achieving staged combustion of fuel and air, reducing combustion temperature and the possibility of coking, and reducing the formation of nitrogen oxides. Within the spatial pneumatic screening bed 3, fuel can be fully suspended and dispersed, thereby achieving effective screening and grading. By controlling the primary air 4... A secondary air ratio of 5 can achieve the effect of free fluidization of coal particles; fuel circulation and bed material non-circulation are achieved without relying on external circulation equipment, reducing wear on the boiler structure and extending the stable operation cycle. The free fluidization state of the coal particles forms a micro-circulation in the furnace, which prolongs the combustion path in the boiler and is more conducive to complete combustion. This combustion method is not only suitable for the combustion of coal, but also for the combustion of other solid particles, such as solid mixed compressed fuels, coal gangue, coal slime, biomass pellets, etc. The following uses coal as an example to illustrate this combustion method.

[0060] like Figures 1 to 5 As shown, the bottom bed 1 is disposed inside the furnace 2, and the furnace 2 includes a front wall 21 and a rear wall 22. The front wall 21 is connected to the spatial pneumatic screening bed 3.

[0061] In this embodiment of the invention, the furnace is started by igniting the bottom bed 1. After the fuel in the bottom bed 1 is stably burned, high-temperature flue gas is generated and moves upward under the action of the fan and density difference, thereby ensuring that the temperature of the coal particles on the space pneumatic screening bed 3 reaches the ignition point. The feed amount of the bottom bed 1 accounts for 30%-40% of the total fuel consumption. As the amount of fuel allocated to the bottom bed 1 is reduced, the bed area and bed resistance are reduced accordingly, avoiding a large amount of fuel from accumulating in the bottom fixed bed, thereby achieving the effect of reducing the peak combustion temperature. The furnace front wall 21 and furnace rear wall 22 are integrally formed, which enhances the overall rigidity and stability of the furnace 2 and improves the durability and service life of the furnace 2.

[0062] like Figures 1 to 5 As shown, the spatial pneumatic screening bed 3 is located on the upper layer of the bottom bed 1. The spatial pneumatic screening bed 3 has an n-layer bed structure, and the n layers are respectively connected to the front wall 21 of the furnace. The spatial pneumatic screening bed 3 includes a first bed 31, a second bed 32, and an nth bed 33. A first bed surface 311 is provided on the first bed 31. A second bed surface 321 is provided on the second bed 32. An nth bed surface 331 is provided on the nth bed 33.

[0063] In this embodiment of the invention, the spatial pneumatic screening bed 3 is arranged in the space of the furnace 2. The feed rate of the spatial pneumatic screening bed 3 accounts for 60%-70% of the total fuel consumption, thereby reducing the amount of fuel allocated to the bottom bed 1. Each layer of spatial pneumatic screening bed 3 has a flue gas temperature measuring point above its surface. When the flue gas temperature reaches the ignition point of the coal particles, a signal is given to the stratified feeding device 6, allowing fuel to enter the surface of the spatial pneumatic screening bed 3. The high-temperature flue gas provides heat to dry the coal particles, causing them to volatilize and release, and bringing the coal particles to their ignition point. At the same time, the high-temperature flue gas disturbs the coal particles on the surface of the spatial pneumatic screening bed 3, causing the coal particles to mix and burn with the flue gas, and providing upward buoyancy to the coal particles. The upper spatial pneumatic screening bed 3 can over-distribute fuel, appropriately increase the fluidization velocity and primary air velocity, and allow small-diameter coal particles to burn in a suspended state in the space. Through this free fluidization combustion, the combustion path of the coal particles in the furnace is extended, which is more conducive to burnout.

[0064] like Figures 1 to 5 As shown, the layered feeding device 6 is disposed on the front wall 21 of the furnace and is connected to the interior of the furnace 1; the layered feeding device 6 includes a bottom bed feeding device 61, a first bed feeding device 62, a second bed feeding device 63, and an nth bed feeding device 64; the bottom bed feeding device 61 is located on the upper layer of the bottom bed 1; the first bed feeding device 62 is located on the upper layer of the first bed 31; the second bed feeding device 63 is located on the upper layer of the second bed 32; and the nth bed feeding device 64 is located on the upper layer of the nth bed 33.

[0065] In this embodiment of the invention, the interior of the furnace 2 is connected to the layered feeding device 6, realizing spatial graded feeding; the bottom bed 1 is fed by the bottom bed feeding device 61, and the feeding amount accounts for 30%-40% of the total fuel consumption; the first layer bed 31 is fed by the first layer bed feeding device 62; the second layer bed 32 is fed by the first layer bed feeding device 63; the nth layer bed 33 is fed by the nth layer bed feeding device 64; after successful ignition, the first layer feeding device 62 initially feeds about 10% of the material into the first layer bed 31; when the flue gas temperature at the flue gas temperature measuring point above the first layer bed 31 increases significantly in a short period of time, it is determined that the first layer bed 31 has been ignited; after the ignition is stable, the load is increased, and the feeding of the first layer bed 31 and the bottom bed 1 is increased simultaneously. After the combustion is stable, the feeding of the bottom bed 1 is gradually reduced and the feeding of other spatial pneumatic screening beds 3 is increased.

[0066] like Figures 1 to 5 As shown, the primary air 4 includes a bottom bed primary air 41, a first bed primary air 42, a second bed primary air 43, and an nth bed primary air 44; the bottom bed primary air 41 is located below the bottom bed 1 and communicates with the interior of the furnace 2; the first bed primary air 42 is disposed on the front wall 21 of the furnace, located below the first bed surface 311, and communicates with the interior of the first bed 31; the second bed primary air 43 is disposed on the front wall 21 of the furnace, located below the second bed surface 321, and communicates with the interior of the second bed 32; the nth bed primary air 44 is disposed on the front wall 21 of the furnace, located below the nth bed surface 331, and communicates with the interior of the nth bed 33.

[0067] In this embodiment of the invention, the primary air 4 provides the required air volume for the combustion of coal particles in this layer; the air supply to the bottom bed 1 is supplied by the primary air 41 of the bottom bed, accounting for 30%-40% of the total air volume required for boiler combustion; the primary air 4 supplies air to the bottom bed 1 in a direction perpendicular to the bed surface of the bottom bed 1, supplying air from the bottom of the bottom bed 1 to the bed surface of the bottom bed 1; due to the reduction in the amount of fuel allocated to the bottom bed 1, the bed area and bed resistance are reduced accordingly, reducing the pressure head of the blower of the primary air 41 of the bottom bed, thereby reducing its power; when starting the furnace, the bottom bed 1 is started first, and after the fuel in the bottom bed 1 is stably burned, high-temperature flue gas is generated, which moves upward under the action of the blower and density difference; depending on the type of fuel, the temperature range of the high-temperature flue gas is also different, ensuring that the temperature of the coal particles on the first bed 31 of the space pneumatic screening bed reaches the ignition point.

[0068] like Figures 1 to 5As shown, the secondary air 5 is disposed on the front wall 21 of the furnace and communicates with the interior of the furnace 2; the secondary air 5 includes a first bed secondary air 51, a second bed secondary air 52 and an nth bed secondary air 53; the first bed secondary air 51 is located above the first bed feeding device 62; the second bed secondary air 52 is located above the second bed feeding device 63; the nth bed secondary air 53 is located above the nth feeding device 64.

[0069] In this embodiment of the invention, the secondary air 5 is arranged above the bed surface of the spatial pneumatic screening bed 3 to provide the required oxygen for the CO produced by incomplete combustion and the unburned coal particles, and to generate convection with the primary air and high-temperature flue gas, disturbing the movement of coal particles and the flow of flue gas, prolonging the combustion path, and ensuring the burnout of coal particles.

[0070] like Figures 1 to 5 As shown, the inclination angle of the bed surface of the first to nth layers of the spatial pneumatic screening bed 3 decreases layer by layer; the distance between the first to nth layers of the spatial pneumatic screening bed 3 and the rear wall 22 of the furnace increases layer by layer; and the gap between the first to nth layers of the spatial pneumatic screening bed 3 increases layer by layer.

[0071] In this embodiment of the invention, the inclination angle a of the first layer bed surface 311 of the spatial pneumatic screening bed, the inclination angle b of the second layer bed surface 321 of the spatial pneumatic screening bed, and the inclination angle c of the nth layer bed surface 331 of the spatial pneumatic screening bed gradually decrease; the distance d between the first layer bed 31 of the spatial pneumatic screening bed and the rear wall 22 of the furnace, the distance e between the second layer bed 32 of the spatial pneumatic screening bed and the rear wall 22 of the furnace, and the distance f between the nth layer bed 33 of the spatial pneumatic screening bed and the rear wall 22 of the furnace gradually increase; the gap m1 between the lower layer bed is smaller than the gap m2 between the upper layer bed.

[0072] like Figures 1 to 5 As shown, the supply module is used to calculate the feed amount of the bottom bed 1 according to the total fuel demand of the boiler, and supply fuel to the bottom bed 1 and the spatial pneumatic screening bed 3 through the layered feeding device 6; the air supply module is used to supply air to the bottom bed 1 and the spatial pneumatic screening bed 3 through primary air 4 and secondary air 5 according to the total air volume required for boiler combustion; the adjustment module is used to adjust the descent and ascent speed of the fuel by adjusting the ratio of primary air 4 and secondary air 5 according to the particle size of the fuel; the detection module is used to monitor the flue gas temperature in real time, and when the flue gas temperature reaches the ignition point of the fuel, the layered feeding device 6 is activated to feed the fuel.

[0073] In this embodiment of the invention, ignition first involves feeding fuel into the bed 1 via the bed feeder 61, along with bed primary air 41, and then performing bed ignition. At this point, the fuel in the bed 1 accounts for approximately 50%-60% of the fuel required at full load, and the bed primary air 41 is relatively small, resulting in oxygen-deficient combustion. The generated high-temperature flue gas rises above the first bed 31, where a flue gas temperature measuring point is located. When the flue gas temperature reaches the ignition point of the coal type (generally 400℃ for lignite and 550℃ for bituminous coal), a signal is sent to the first bed feeder 62, allowing the first bed 31 to feed. The ignition point temperature setting should be based on the test results of the coal type and taken from the middle of the temperature range. At a relatively high point, the flue gas temperature at this measuring point reaches the ignition point temperature and remains there for a period of time, indicating successful ignition. After successful ignition, the bottom bed feeding device 61 initially feeds approximately 10% of the fuel into the first bed 31. When the flue gas temperature at the upper flue gas temperature measuring point increases significantly in a short period, it is determined that the first bed 31 has been ignited. At this time, the primary air 42 of the first bed is gradually increased to the air volume required for fuel combustion in this layer, ensuring continuous combustion in the first bed 31. After ignition stabilizes, the load is increased. This requires simultaneously increasing the feeding of the first bed 31 and the bottom bed 1. After combustion stabilizes, the feeding of the bottom bed is reduced, and the feeding of the other pneumatic screening beds 3 is increased. Ultimately, the fuel amount in the bottom bed is approximately 30% of the fuel required at full load. -40%; Each bed has a flue gas temperature measuring point above it, and the detection method is the same as that of the first bed 31; the above is to complete ignition and increase load; after the primary air 41 of the bottom bed forms high-temperature flue gas, the buoyancy of the coal particles on the upper bed is insufficient to support their suspension combustion. In the formation of a free fluidized state, the primary air under each bed and the high-temperature flue gas generated by the lower bed mainly provide upward force for the coal particles. The high-temperature flue gas generated by the bottom bed can only provide a small part of buoyancy, which can make extremely fine coal particles directly suspended or fluidized for combustion; the arrangement height of each bed is different, and the initial potential energy of the coal particles is also different; the coal particles fed from the layered feeding device 6 have a certain initial velocity, and the direction is horizontally downward; stable combustion During combustion, the fuel quantity in the bottom bed 1 remains relatively constant at 30%-40%. The proportion of coal particles in a free-flowing state is adjusted mainly by regulating the bed material quantity and the ratio of primary and secondary air in each bed layer. For coal particles in the same bed layer, there are particles that burn turbulently directly on the bed, particles that flow directly upwards, and particles that fall from other upper beds. Under the same primary air and environmental conditions, the degree of free flow is mainly determined by the fuel quantity, the particle size of the coal particles, and the gap in the bed surface. After the equipment is built, the two of these factors are fixed values. If the fuel quantity is too high, the primary air will not be able to penetrate the thick coal bed, thus failing to provide power. Furthermore, it will be difficult for the coal particles to come into contact with oxygen, leading to combustion stagnation.

[0074] In this embodiment, the spatial pneumatic screening bed 3 is not used as the ignition bed. During startup, ignition begins from the bottom bed 1. After stable combustion of the fuel in the bottom bed 1, high-temperature flue gas is generated and moves upwards under the action of the fan and density difference. The temperature range of the high-temperature flue gas varies depending on the type of fuel, ensuring that the coal particles on the spatial pneumatic screening bed 3 reach their ignition point. Flue gas temperature measuring points are arranged above the surface of the spatial pneumatic screening bed 3. When the flue gas temperature is detected to reach the ignition point of the coal particles, a signal is sent to the feeding device 6 to allow feeding. The high-temperature flue gas provides heat to dry the coal particles, causing them to volatilize and reach their ignition point. The first inlet 3 provides the necessary heat for the combustion of the coal particles. 60% of the required airflow is used to agitate the coal particles on the surface of the third layer of the space pneumatic screening bed, causing the coal particles to mix and burn with the flue gas, and together with the high-temperature flue gas, providing upward buoyancy. The coal particles undergo incomplete combustion in the space pneumatic screening bed surface due to oxygen deficiency, producing CO. This creates a reducing atmosphere in the space above the first layer of the space pneumatic screening bed, where N and NOx in the coal particles are continuously reduced to N2, thus inhibiting the formation of fuel nitrogen. At the same time, due to oxygen-deficient combustion and space combustion, the peak combustion temperature on the bed surface is reduced, the amount of thermal nitrogen generated is reduced, and the possibility of coking on the bed surface is also reduced. The main chemical reaction equations are as follows:

[0075] 2C + O2 = 2CO

[0076] 2NO + 2CO = N2 + 2CO2

[0077] The secondary air 51 in the first bed layer is arranged above the first bed surface 311 of the spatial pneumatic screening bed. It provides the necessary oxygen for CO produced by incomplete combustion and unburned coal particles, and creates convection with the primary air 4 and high-temperature flue gas, disturbing the movement of coal particles and the flow of flue gas, extending the combustion path and ensuring the complete combustion of coal particles. By controlling the ratio of primary air 4 and secondary air 5 on the bed layer, the effect of free fluidization of coal particles is achieved. Fuel circulation and bed material non-circulation are achieved without relying on external circulation equipment, reducing wear on the boiler structure and extending stable operation. The cycle time is shortened; due to the reduction in the power of large fans, the reduction in boiler footprint, and the elimination of the need for external circulation equipment, the investment cost and system energy consumption are reduced; by implementing fuel and air distribution gradation, system energy consumption is reduced, low-NOx combustion is achieved, and the possibility of coal particles coking on the bed is reduced; through multi-level bed arrangement, the boiler has excellent overload stable combustion capability; the upper bed can distribute fuel in excess, appropriately increase the fluidization velocity and primary air velocity, and allow small-diameter coal particles to burn in suspension in space; the free fluidization of coal particles prolongs the combustion path in the boiler, which is more conducive to burnout.

[0078] Based on the above embodiments, refer to Figure 2A schematic diagram of the energy of a coal particle; the mechanical energy of the coal particle itself consists of kinetic energy and potential energy, where the potential energy is gravitational potential energy, and the force is manifested in the downward direction; the kinetic energy is provided by the primary air and high-temperature flue gas in the bed, and the force is manifested in the upward direction.

[0079] Based on the above embodiments, refer to Figure 3 The first case of coal particle motion is when the coal particles are unburned and the overall force on the coal particles is upward. At this time, regardless of the relationship between the coal particle size dl and the gap m in the bed, the coal particles will move upward with the flue gas. During the upward movement, the gravitational potential energy increases, and the mass and velocity of the coal particles decrease until they are completely burned.

[0080] Based on the above embodiments, refer to Figure 4 The second scenario involves the motion of coal particles. The conditions are: the coal particles are unburned, the overall force on the particles is downward, and the particle size dl is smaller than the gap m2 within the upper bed. In this case, the coal particles will fall from the surface of the upper bed, resulting in two possible trajectories: First, as combustion progresses and the coal particles fall, their gravitational potential energy decreases, and they still have velocity when they reach the lower bed, where they continue to burn. Second, as combustion continues, the velocity of the coal particles drops to zero before reaching the lower bed, and they begin to move upward under the influence of an upward force.

[0081] Based on the above embodiments, refer to Figure 5 The third scenario involves the movement of coal particles. The conditions are that the coal particles are unburned, the overall force on the coal particles is downward, and the particle size dl is greater than the gap m2 within the upper bed. In this case, the coal particles will undergo turbulent combustion on the bed surface, exhibiting a disordered state. In this situation, the space-start screening bed is equivalent to a fixed bed, and the coal particles undergo reactions such as dry distillation, pyrolysis, and combustion on the bed surface.

[0082] Due to the different stress conditions and particle size dl of coal particles, the characteristic of "free" selection of fluidization state based on the conversion of kinetic potential energy is generated, forming free fluidized combustion inside furnace 2.

[0083] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A spatial free-fluidization combustion method driven by kinetic energy conversion, characterized in that, Includes the following steps: The total feed rate is calculated based on the total fuel demand of the boiler, and fuel is supplied to the bottom bed (1) and the space pneumatic screening bed (3) through the layered feeding device (6) and ignition is carried out at the same time. According to the total air volume required for boiler combustion, air is supplied to the bottom bed (1) and the space pneumatic screening bed (3) through primary air (4) and secondary air (5); The rate of descent or ascent of the fuel is adjusted by regulating the ratio of primary air (4) to secondary air (5) according to the particle size of the fuel. Real-time monitoring of flue gas temperature; when the flue gas temperature reaches the ignition point of the fuel, the stratified feeding device (6) feeds the fuel. Under the influence of buoyancy, gravity and suction, the coal particles on the space pneumatic screening bed (3) generate a free fluid state in the space by relying on the change of their own kinetic potential energy, thereby forming a micro-circulation in the furnace; The bottom bed (1) is located inside the furnace (2), and the furnace (2) includes a front wall (21) and a rear wall (22). The front wall (21) is connected to the spatial pneumatic screening bed (3). The spatial pneumatic screening bed (3) is located on the upper layer of the bottom bed (1). The spatial pneumatic screening bed (3) has an n-layer bed structure, and the n layers are respectively connected to the front wall (21) of the furnace. The space pneumatic screening bed (3) includes a first bed (31), a second bed (32) and an nth bed (33); The first bed (31) is provided with a first bed surface (311); The second bed (32) is provided with a second bed surface (321); The nth bed (33) is provided with an nth bed surface (331); The layered feeding device (6) is installed on the front wall (21) of the furnace and communicates with the interior of the furnace (2); The layered feeding device (6) includes a bottom bed feeding device (61), a first layer bed feeding device (62), a second layer bed feeding device (63), and an nth layer feeding device (64). The bottom bed feeding device (61) is located on the upper layer of the bottom bed (1); The first bed feeder (62) is located on the upper layer of the first bed (31); The second bed feeder (63) is located on the upper layer of the second bed (32); The nth layer feeding device (64) is located on the upper layer of the nth layer bed (33); The primary air (4) includes the primary air of the bottom bed (41), the primary air of the first bed layer (42), the primary air of the second bed layer (43), and the primary air of the nth bed layer (44). The primary air (41) of the bottom bed is located below the bottom bed (1) and is in communication with the interior of the furnace (2); The first bed primary air (42) is located on the front wall (21) of the furnace, below the bed surface (311) of the first bed, and communicates with the interior of the first bed (31); The second bed primary air (43) is located on the front wall (21) of the furnace, below the bed surface (321) of the second bed, and communicates with the interior of the second bed (32); The primary air (44) of the nth bed is located on the front wall (21) of the furnace, below the bed surface (331) of the nth bed, and communicates with the interior of the nth bed (33); The secondary air (5) is disposed on the front wall (21) of the furnace and communicates with the interior of the furnace (2); the secondary air (5) includes a first bed secondary air (51), a second bed secondary air (52) and an nth bed secondary air (53). The secondary air (51) of the first bed is located above the first bed feeding device (62); The secondary air (52) of the second bed is located above the feeding device (63) of the second bed; The secondary air (53) of the nth bed is located above the nth feeding device (64); The inclination angle of the first to nth layers of the spatial pneumatic screening bed (3) decreases layer by layer; The distance between the first to nth layers of the spatial pneumatic screening bed (3) and the rear wall (22) of the furnace increases layer by layer; The gap between the first to the nth layers of the spatial pneumatic screening bed (3) increases layer by layer.

2. The spatial free-flowing combustion method driven by kinetic energy conversion according to claim 1, characterized in that, The feed rate of the bottom bed (1) is 30-40% of the total fuel demand of the boiler.

3. The spatial free-flowing combustion method driven by kinetic energy conversion according to claim 2, characterized in that, The primary air (41) supplied to the bed (1) is 30-40% of the total air volume required for boiler combustion; the primary air (4) is supplied to the bed (1) in a direction perpendicular to the bed surface of the bed (1), and is supplied from the bottom of the bed (1) to the bed surface of the bed (1).

4. The spatial free-flowing combustion method driven by kinetic energy conversion according to claim 3, characterized in that, Also includes: The supply module is used to calculate the feed amount of the bottom bed (1) based on the total fuel demand of the boiler, and to supply fuel to the bottom bed (1) and the space pneumatic screening bed (3) through the layered feeding device (6). The air supply module is used to supply air to the bottom bed (1) and the space pneumatic screening bed (3) through primary air (4) and secondary air (5) according to the total air volume required for boiler combustion. The adjustment module adjusts the rate of fuel descent or ascent by adjusting the ratio of primary air (4) to secondary air (5) according to the fuel particle size. The detection module is used to monitor the flue gas temperature in real time. When the flue gas temperature reaches the ignition point of the fuel, the stratified feeding device (6) feeds the fuel.

Images