A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residues

Abstract

An adjustable circulating fluidized bed boiler for incinerating pyrolysis residues is disclosed. This invention addresses the problems of unstable bed temperature and pressure, and equipment shutdown due to excessive parameters, that commonly occur in existing circulating fluidized beds when incinerating different pyrolysis waste residues. The invention comprises a fluidized bed boiler body (6), a sub-bed air chamber (2), multiple dispersion pipes (5), and multiple high-temperature resistant gate valves (32). The sub-bed air chamber (2) is installed at the lower part of the fluidized bed boiler body (6). The upper parts of the multiple dispersion pipes (5) are connected to the fluidized bed boiler body (6) in a ring array, and the lower parts of the multiple dispersion pipes (5) are connected to the sub-bed air chamber (2). Each dispersion pipe (5) is equipped with a high-temperature resistant gate valve (32). The opening degree of the high-temperature resistant gate valve (32) is remotely adjusted through a control program to achieve bed pressure regulation of the fluidized bed without changing the combustion load and fluidizing air volume. This invention is used for the incineration of pyrolysis residues.

Description

Technical Field

[0001] This invention relates to a circulating fluidized bed boiler, specifically to a material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residues, belonging to the field of pyrolysis residue treatment technology. Background Technology

[0002] With its large population, China faces the challenge of managing waste from production and daily life, which remains a critical issue the country strives to address. Furthermore, due to the relatively developed and rapidly growing agricultural and industrial sectors, the output of various agricultural wastes (such as straw, manure, sludge, biogas residue, and animal carcasses) and industrial wastes (such as municipal sludge, oilfield sludge, fuel residue, and waste plastics and rubber) is increasing daily.

[0003] Pyrolysis is a relatively mature solid waste treatment method that has been developed in recent years and is considered one of the effective means of harmless, volume-reduced, and resource-based treatment of solid waste. However, the residue after pyrolysis often has a certain calorific value, and according to relevant standards, pyrolysis residue generally does not meet the direct emission indicators, so it often needs to be co-treated by incineration. Circulating fluidized bed boilers are widely used in the field of pyrolysis residue incineration due to their good fuel adaptability, environmental characteristics, and load regulation characteristics.

[0004] Because the sources of solid waste are often inconsistent, their composition varies greatly. This leads to significant differences in the physical properties of the residues produced by pyrolyzing different solid wastes, including their fluidization characteristics within a circulating fluidized bed. For example, the particle shape, size, and density of the pyrolysis products of biogas slag and fuel waste differ considerably. Sudden changes in the pyrolysis feedstock can drastically alter the properties of the incinerator bed material, easily exceeding the design values ​​for stable operation of traditional circulating fluidized bed boilers. This can result in fluidized bed collapse, bed overturning, and other phenomena, making stable operation difficult and, in severe cases, even necessitating boiler shutdown, significantly impacting equipment economics.

[0005] Traditional control methods typically adjust the fluidizing air volume, combustion load, and ash discharge rate. However, adjusting the first two methods leads to changes in flue gas flow rate, temperature, and velocity, placing significant pressure on subsequent flue gas treatment modules. Adjusting the ash discharge rate causes significant changes in bed temperature, which is detrimental to stable combustion in the fluidized bed. Therefore, it is necessary to develop an adjustable circulating fluidized bed boiler that can adapt to frequent material changes and operate stably for the combustion of pyrolysis residues.

[0006] In summary, existing circulating fluidized beds are prone to unstable bed temperature and pressure when incinerating different pyrolysis wastes, which is not conducive to long-term stable combustion of the fluidized bed. Summary of the Invention

[0007] The purpose of this invention is to address the problem of unstable bed temperature and pressure that easily occurs in existing circulating fluidized bed boilers when incinerating different pyrolysis waste residues. Therefore, this invention provides a material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residues.

[0008] The technical solution of the present invention is as follows: A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue includes a fluidized bed boiler body, which further includes a sub-bed air chamber, multiple dispersion pipes, and multiple high-temperature resistant gate valves. The sub-bed air chamber is installed at the lower part of the fluidized bed boiler body. The upper parts of the multiple dispersion pipes are connected to the fluidized bed boiler body in a ring array, and the lower parts of the multiple dispersion pipes are connected to the sub-bed air chamber. Each dispersion pipe is equipped with a high-temperature resistant gate valve. The valve opening of the high-temperature resistant gate valve is remotely adjusted by a control program to achieve fluidized bed pressure regulation without changing the combustion load.

[0009] Furthermore, it also includes multiple lower furnace external pipes and multiple lower bed air chamber external pipes. The upper part of each dispersion pipe is inserted into the fluidized bed boiler body at an angle downward through a lower furnace external pipe, and the angle between the inclined pipe part of the lower furnace external pipe and the horizontal is 20-60°. The lower part of each dispersion pipe is connected to the upper part of the lower bed air chamber through a lower bed air chamber external pipe.

[0010] Preferably, both the horizontal and vertical sections of the under-bed air chamber are insulated with under-bed air chamber insulation structures, wherein the under-bed air chamber insulation structure of the horizontal section has a throat structure.

[0011] Furthermore, it also includes two primary air ducts, which are symmetrically installed on both sides of the air chamber under the bed, and the outlets of both primary air ducts are inclined downwards.

[0012] Furthermore, it also includes a metal fiber burner, which is horizontally arranged and connected to the horizontal section of the under-bed air chamber.

[0013] Preferably, the metal fiber burner includes a metal fiber burner head, a burner control box, and a gas-air mixing chamber. The metal fiber burner head is horizontally inserted into the inner cavity of the under-bed air chamber insulation structure. The gas-air mixing chamber is connected to the outer end face of the horizontal section of the under-bed air chamber. The burner control box is connected to the gas-air mixing chamber.

[0014] Furthermore, it also includes an air distribution plate fixing structure, an air distribution plate casting substrate, and multiple air distribution pipe caps. The air distribution plate fixing structure is installed on the furnace insulation structure inside the fluidized bed boiler body. The air distribution plate casting substrate is cast on the air distribution plate fixing structure. Multiple air distribution pipe caps pass through the air distribution plate casting substrate and are fixedly connected to the air distribution plate fixing structure.

[0015] Preferably, among the multiple air duct caps, one air duct cap is located at the center of the circular air duct fixing structure. The air duct cap located at the center is the central air duct cap, and the other air duct caps are arranged in three layers around the outside of the central air duct cap from the inside out.

[0016] Preferably, the radii of the central circles containing the other air duct caps arranged in three layers from the inside out form a monotonically increasing arithmetic sequence.

[0017] Furthermore, it also includes a drain outlet, which is installed on the under-bed air chamber and located directly below the fluidized bed boiler body.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention employs multiple dispersion tubes 5, which can adjust the circulating fluidized bed pressure, thereby ensuring the incineration of various pyrolysis wastes. It also simplifies the adjustment method and shortens the adjustment time. When incinerating low-density pyrolysis residues, the opening of the high-temperature resistant gate valve 32 is relatively small. When the density of the pyrolysis residues suddenly increases due to changes in properties, the opening of the high-temperature resistant gate valve 32 is increased, increasing the flow rate of fluidizing air from the dispersion tubes, reducing air resistance, and preventing a significant increase in bed pressure.

[0020] 2. This invention features co-combustion in the under-bed air chamber and the fluidized bed boiler body. The under-bed air chamber incorporates a cast-in-place throat insulation structure. Based on the Venturi effect, the temperature and velocity of the combustion flue gas become more uniform. Combined with a short-flame metal fiber burner, this ensures uniform mixing of the flue gas and air under the bed.

[0021] 3. The outlet of the dispersion pipe of the present invention is inclined downward and intersects with the outlet of the air distribution plate to maintain the uniform flow field in the furnace. Since the outlet of the external air pipe 33 at the bottom of the furnace also extends into the material layer, the total amount of fluidizing air received by the material layer is not affected by the opening of the high temperature resistant slide valve 32. Therefore, the effect of adjusting the bed pressure is achieved without affecting the fluidization in the furnace.

[0022] 4. Conventional fluidized bed boilers typically regulate bed pressure by altering the primary air volume and adjusting the ash discharge rate. This invention proposes a novel method for regulating bed pressure: adding bypass dispersion pipes and adjusting the valve openings of these pipes. Multiple dispersion pipes connect the under-bed air chamber and the furnace, effectively adding multiple channels from the under-bed air chamber to the furnace to the original air supply channel of the under-bed air chamber-air distribution plate-furnace. This significantly increases the total area of ​​the air supply channel. According to the continuity equation in fluid mechanics, increasing the flow area reduces the flow velocity. Furthermore, based on the formula for calculating local resistance, this reduction in velocity effectively reduces local resistance losses. Based on this principle, this invention utilizes the reduced local resistance losses resulting from the increased air supply area to balance the bed pressure increase caused by the surge in the density of the combustion feedstock, while maintaining a constant total air volume. This invention conforms to scientific principles and has been experimentally verified to be feasible.

[0023] 5. The bed pressure adjustment method adopted in this invention can ensure the stable operation of the fluidizing air supply system (under-bed primary air fan, under-bed burner, etc.) to the greatest extent. For conventional fluidized bed incinerators, when burning pyrolysis residues with a density significantly higher than the design value, the pressure head of the fluidizing air supply system is easily too high, exceeding the equipment's operating capacity, leading to equipment failure and shutdown, and even the forced shutdown of the entire system. The fluidized bed boiler designed in this patent reduces the pressure loss of the air distribution plate by using bypass air supply when burning high-density pyrolysis residues, without changing the flow rate, ensuring that the pressure head of the fluidizing air supply system is always within the normal operating range. This effectively improves the phenomenon of forced shutdown, which is equivalent to indirectly broadening the feedstock adaptability of the incinerator, making the density range of feedstocks that the incinerator can burn wider and the adjustable range wider. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0025] Figure 2 This is a cross-sectional view of the under-bed air chamber and the lower part of the furnace of the present invention.

[0026] Figure 3 This is a schematic diagram of the external structure of the furnace of the fluidized bed boiler body 6 of the present invention.

[0027] Figure 4 This is a schematic diagram of the air distribution plate fixing structure of the present invention.

[0028] The components include: 1. Metal fiber burner; 2. Underbed air chamber; 3. Air chamber support structure; 4. Cooling slag remover; 5. Dispersion pipe; 6. Fluidized bed boiler body; 7. Expansion joint; 8. Furnace-separator horizontal flue; 9. Cyclone separator; 10. Return feeder; 11. Furnace return pipe; 12. Separator-economizer transition flue; 13. Economizer; 14. Cyclone dust collector; 15. Baghouse dust collector; 16. Feeder; 17. Furnace feed pipe; 18. Burner control box; 19. Gas-air mixing chamber; 20. Metal fiber burner head; 21. 1. Under-bed air chamber shell; 22. Under-bed air chamber insulation structure; 23. Drain outlet; 24. Primary air duct; 25. Air distribution plate fixing structure; 26. Air distribution plate casting substrate; 27. Air distribution plate hood; 28. Slag discharge chute; 29. ​​Furnace shell; 30. Furnace internal insulation structure; 31. Under-bed air chamber external connection pipe; 32. High-temperature resistant slide valve; 33. Lower furnace external connection pipe; 34. Lower furnace secondary air duct; 35. Upper furnace secondary air duct; 36. Under-bed burner interface; 37. Furnace return material interface; 38. Furnace feeding interface; 39. Central hood. Detailed Implementation

[0029] Specific implementation method one: Combining Figures 1 to 4This embodiment describes a material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residues, comprising a fluidized bed boiler body 6, an expansion joint 7, an air chamber support structure 3, and a cooling slag discharger 4. It also includes an under-bed air chamber 2, multiple dispersion pipes 5, and multiple high-temperature resistant gate valves 32.

[0030] The main system is divided into two parts: a material circulation system and a flue gas system. The remaining components include auxiliary systems such as support, slag removal, and combustion. The material circulation system includes: a feeder 16, a furnace feed pipe 17, a furnace body 6, a furnace-separator horizontal flue 8, a cyclone separator 9, a return feeder 10, and a furnace return pipe 11. The flue gas system includes: an under-bed air chamber 2, a furnace body 6, a furnace-separator horizontal flue 8, a cyclone separator 9, a separator-economizer transition flue 12, an economizer 13, a cyclone dust collector 14, a bag filter 15, and subsequent flue gas purification equipment.

[0031] The under-bed air chamber 2 is installed at the lower part of the fluidized bed boiler body 6. The upper part of multiple dispersion pipes 5 is connected to the fluidized bed boiler body 6 in a ring array, and the lower part of multiple dispersion pipes 5 is connected to the under-bed air chamber 2. Each dispersion pipe 5 is equipped with a high-temperature resistant slide valve 32. The valve opening of the high-temperature resistant slide valve 32 is remotely adjusted by the control program to achieve fluidized bed pressure regulation without changing the combustion load.

[0032] Expansion joint 7 is installed on the upper part of fluidized bed boiler body 6. The top of fluidized bed boiler body 6 is connected to cyclone separator 9 through furnace-separator horizontal flue 8. The lower part of cyclone separator 9 is connected to return feeder 10. Return feeder 10 is connected to fluidized bed boiler body 6 through furnace return pipe 11. The upper end of cyclone separator 9 is connected to economizer 13 through separator-economizer transition flue 12. The lower part of economizer 13 is connected to cyclone dust collector 14. Cyclone dust collector 14 is connected to bag filter dust collector 15.

[0033] The furnace feed pipe 17 is installed on the fluidized bed boiler body 6, and the feeder 16 is installed on the upper part of the furnace feed pipe 17 and supplies material to the furnace feed pipe 17; the wind chamber support structure 3 is supported and installed on the lower part of the fluidized bed boiler body 6 and the under-bed wind chamber 2, and the cooling slag discharger 4 is connected to the metal fiber burner 1.

[0034] In this embodiment, except for the economizer 13, all main structures involving high temperatures in the material circulation system and flue gas system are internally insulated. The insulation arrangement can maximize heat dissipation and improve energy utilization. At the same time, components such as the fluidized bed boiler body 6, furnace-separator horizontal flue 8, cyclone separator 9, return feeder 10, and furnace return pipe 11 are always at a high temperature, which is conducive to the supplementary combustion of pyrolysis residue circulating materials and enhances the combustion effect.

[0035] In this embodiment, multiple dispersion pipes 5 are arranged between the lower part of the fluidized bed boiler body 6 and the underbed air chamber 2, and a separate high-temperature resistant gate valve 32 is arranged on each dispersion pipe 5. The opening of this valve can be remotely adjusted by the control program, so as to realize the bed pressure regulation of the fluidized bed without changing the combustion load. This ensures that even if the properties of the pyrolysis residue change drastically, the boiler can adapt quickly, so as to make the system operate stably and alleviate the impact on the system caused by different incineration raw materials.

[0036] In this embodiment, the under-bed ventilation chamber 2 is shaped like the intersection of two horizontal and vertical cylinders, such as... Figure 2 The entire structure is located below the fluidized bed boiler body, divided into horizontal and vertical sections. The upper part of the vertical section is connected to the lower part of the fluidized bed boiler body via a flange, with an air distribution plate structure embedded between them. A metal fiber burner is arranged at the front end of the horizontal section of the under-bed air chamber for under-bed ignition and heating. Two primary air ducts are symmetrically arranged downwards at the rear of the under-bed air chamber, with the direction of primary air movement in the horizontal section opposing the direction of the under-bed combustion flue gas flow. Near the fluidized bed boiler body, the vertical section of the under-bed air chamber has multiple symmetrically arranged dispersion pipes along its circumference, creating two parallel pathways for the under-bed airflow: one pathway is air chamber-air distribution plate-furnace, and the other is air chamber-dispersion pipe-furnace. The under-bed airflow from these two pathways converges above the air distribution plate, forming the fluidizing air. The fluidizing air drives the bed material and pyrolysis residue in a bubbling or circulating motion within the furnace.

[0037] This embodiment uses multiple dispersion pipes connecting the under-bed air chamber and the bottom of the furnace, arranged symmetrically at equal angles along the circumference of the furnace. Each dispersion pipe consists of three parts: an outer pipe for the under-bed air chamber, a high-temperature resistant gate valve, and an outer pipe for the lower part of the furnace. Each outer pipe for the under-bed air chamber is welded from two seamless steel pipes and a right-angle elbow. Each outer pipe for the lower part of the furnace is welded from two seamless steel pipes and a non-standard elbow, with the angle between the two seamless steel pipes ranging from 20° to 60°. The seamless steel pipes must be made of high-temperature resistant and wear-resistant material. The outlet section of the outer pipe for the lower part of the furnace is embedded in the furnace's insulation structure. The spatial extension line of the outer pipe for the lower part of the furnace intersects with the center circle of the second-to-last ring of the air distribution plate's hood, ensuring a stable flow field on the upper side of the air distribution plate. A high-temperature resistant gate valve is selected to control the airflow within the dispersion pipe. The advantage of this method is that the gate valve has good linearity in opening, strong operability, and is easy to control. All high-temperature resistant gate valves are controlled collectively through a control logic; individual valves cannot be controlled independently, ensuring as uniform a speed and temperature distribution as possible across the horizontal cross-section of the furnace. The materials used for the aforementioned dispersion tubes are all high-temperature resistant steel, enabling long-term stable operation at 900℃, with the maximum operating temperature in the under-bed air chamber not exceeding 950℃.

[0038] In this embodiment, a slag discharge port connected to a cooling slag discharger is arranged close to the air distribution plate of the circulating fluidized bed to discharge the completely burned pyrolysis residue from the furnace. An electric slide valve is installed in the vertical section of the slag discharge chute to control the slag discharge switch. The slag cooler is a water-cooled spiral slag cooler, and the slag discharge speed can be controlled by both the electric slide valve and the spiral slag cooler to maintain stable bed pressure.

[0039] In this embodiment, a bed burner interface is arranged on the circulating fluidized bed body (above the return feeder outlet). The outer end of the interface connects to the combustion chamber of the bed burner, further increasing the furnace temperature and ensuring complete combustion of the remaining combustibles in the pyrolysis residue. It is important to note that the bed burner does not burn within the boiler body but is externally connected to the combustion chamber to ensure that ignition and combustion are not affected by fluidized bed particles. On the circulating fluidized bed body, two layers of secondary air are arranged above and below the bed burner, with two secondary air ducts in each layer. The outlets of the secondary air ducts are horizontally inclined downwards, and their extensions intersect the central axis of the circulating fluidized bed body cylinder. Furthermore, solid waste pyrolysis often generates a large amount of pyrolysis gas, which, if not specifically used, can be introduced near the circulating fluidized bed boiler body to save fuel.

[0040] In this embodiment, the fluidized bed boiler body 6 is provided with the following components from top to bottom: upper secondary air duct 35, bed burner interface 36, furnace return interface 37, furnace feed interface 38, and lower secondary air duct 34.

[0041] Specific Implementation Method Two: Combining Figure 2 This embodiment further includes multiple lower furnace external pipes 33 and multiple lower air chamber external pipes 31. The upper part of each dispersion pipe 5 is inserted into the fluidized bed boiler body 6 at an angle downward through a lower furnace external pipe 33, and the angle between the inclined pipe part of the lower furnace external pipe 33 and the horizontal is 20-60°. The lower part of each dispersion pipe 5 is connected to the upper part of the lower air chamber 2 through a lower air chamber external pipe 31.

[0042] With this configuration, the fluidized bed boiler body 6 has a circular cross-section, and the multiple dispersion pipes 5 are symmetrically arranged along the center of the cross-section. The inclined portion of the lower external pipe 33 is inserted into the furnace at a certain angle to the horizontal plane, ranging from 20° to 60°. This angle ensures that the fluidizing air has a certain rigidity in its vertical component, allowing the fluidizing air blown from the dispersion pipes 5 to be directed as far as possible towards the surface of the air distribution plate, ensuring that the lowest pyrolysis residue particles remain in constant motion and preventing dead zones at the bottom of the furnace. It is important to note that if the angle is too small, the vertical component of the fluidizing air will be insufficient to produce a fluidizing effect; if the angle is too large, it will produce a wall-adhering air effect, resulting in uneven flow field distribution within the furnace. Other components and connections are the same as in Specific Embodiment One.

[0043] Specific implementation method three: Combining Figure 2 In this embodiment, both the horizontal and vertical sections of the under-bed ventilation chamber 2 are constructed with under-bed ventilation chamber insulation structures 22. The horizontal section's insulation structure 22 has a throat-like structure. This design results in a distinct tapering-constriction form in the horizontal section's insulation structure, meaning the cross-sectional area at the high-temperature flue gas inlet and outlet is larger than the cross-sectional area in the middle of the flue gas passage, ensuring uniform flue gas temperature at the outlet of the horizontal section of the under-bed ventilation chamber 2. Other components and connections are the same as in specific embodiments one or two.

[0044] Specific implementation method four: Combination Figure 2 This embodiment further includes two primary air ducts 24, which are symmetrically installed on both sides of the under-bed air chamber 2, with the outlets of both ducts 24 inclined downwards. This arrangement ensures that the primary air supplied from the ducts 24 counteracts the high-temperature flue gas generated by combustion, preventing the high-temperature flue gas from impacting the wall and effectively reducing the pressure deviation in the space below the air distribution plate caused by the 90° bend in the flue gas passage. Other components and connections are the same as in specific embodiments one, two, or three.

[0045] In this embodiment, the primary air duct is arranged opposite to the outlet of the horizontal section of the under-bed air chamber and slopes downwards along the horizontal plane. This design can balance the pressure difference between the front and rear walls of the vertical section of the under-bed air chamber, ensuring a balanced pressure field in front of the air distribution plate. A drain outlet is arranged at the lowest point of the vertical section of the under-bed air chamber to discharge the condensate water generated by the combustion of the metal fiber burner.

[0046] Specific Implementation Method Five: Combining Figure 1 This embodiment describes a metal fiber burner 1, which is horizontally arranged and connected to the horizontal section of the under-bed air chamber 2.

[0047] This configuration arranges the flame circumferentially along the metal fiber burner head 20, and combined with the throat-shaped under-bed air chamber insulation structure 22, effectively balances the smoke temperature and velocity. Other components and connections are the same as in specific embodiments one, two, three, or four.

[0048] Specific Implementation Method Six: Combination Figure 2 This embodiment describes a metal fiber burner 1 comprising a metal fiber burner head 20, a burner control box 18, and a gas-air mixing chamber 19. The metal fiber burner head 20 is horizontally inserted into the inner cavity of the under-bed air chamber insulation structure 22 of the under-bed air chamber 2. The gas-air mixing chamber 19 is connected to the outer end face of the horizontal section of the under-bed air chamber 2. The burner control box 18 is connected to the gas-air mixing chamber 19.

[0049] Other components and connections are the same as in specific implementation methods one, two, three, four, or five.

[0050] In this embodiment, a metal fiber burner is selected as the under-bed ignition and hot flue gas generation device. The axial direction of the metal fiber burner head is consistent with the throat direction of the horizontal section of the under-bed air chamber. The metal fiber burner flame is extremely short and its direction is along the radial direction of the burner head. In space, the axial direction of the burner head is perpendicular. Its advantage is that, compared with traditional burners, the flame velocity and temperature deviation in the horizontal section of the under-bed air chamber are smaller, which is conducive to stabilizing the temperature and velocity distribution in front of the air distribution plate.

[0051] In this embodiment, the furnace shell 29 at the bottom of the fluidized bed boiler body 6 has a furnace insulation structure 30. The slag discharge chute 28 is inserted obliquely from bottom to top into the furnace shell 29 and the furnace insulation structure 30. The underbed air chamber 2 has an underbed air chamber shell 21 on the outside of the underbed air chamber insulation structure 22.

[0052] Specific implementation method seven: Combination Figure 2 and Figure 4 This embodiment further includes an air distribution plate fixing structure 25, an air distribution plate casting substrate 26, and multiple air distribution pipe caps 27. The air distribution plate fixing structure 25 is installed on the furnace insulation structure 30 inside the fluidized bed boiler body 6. The air distribution plate casting substrate 26 is cast on the air distribution plate fixing structure 25. The multiple air distribution pipe caps 27 pass through the air distribution plate casting substrate 26 and are fixedly connected to the air distribution plate fixing structure 25.

[0053] In this configuration, the horizontal cross-section of the air distribution plate is circular. The air distribution duct caps 27 and their connecting ducts are welded to the air distribution plate fixing structure 25, and the cast base material 26 of the air distribution plate is cylindrical. The air distribution duct caps 27 are bell-shaped, with one air distribution duct cap 27 located at the center of the flat surface of the air distribution plate, called the central cap 39. The other air distribution duct caps 27 are arranged in three layers around the central cap 39. Other components and connections are the same as in specific embodiments one, two, three, four, five, or six.

[0054] Specific implementation method eight: Combination Figure 4 In this embodiment, one of the multiple air distribution duct caps 27 is located at the center of the circular air distribution plate fixing structure 25. This central air distribution duct cap 27 is the central air cap 39. The other air distribution duct caps 27 are arranged in three layers around the central air cap 39 from the inside out. With this arrangement, for pyrolysis residue incinerators with a small combustion capacity, three layers of circumferential air caps are sufficient to achieve uniform fluidization. Too many layers would not only be difficult to process but also costly. If the combustion capacity increases, the structure and size of the air caps can be adjusted to accommodate the change. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, or seven.

[0055] Specific Implementation Method Nine: Combining Figure 4In this embodiment, the radii of the central circles of the other air distribution duct caps 27 arranged in three layers from the inside out form a monotonically increasing arithmetic sequence. With this arrangement, the number of air caps in the three layers from the inside out are 6, 16, and 24 respectively. The radii of the central circles of these three layers of air caps form a monotonically increasing arithmetic sequence, ensuring that the distances between the center of the circle and the first, second, and third layers are equal. The distance between the third layer and the inner wall of the furnace is half of the aforementioned distances, thus maximizing the homogenization of airflow distribution and optimizing material fluidization. Other components and connections are the same as in any of the specific embodiments one through eight.

[0056] Specific Implementation Method Ten: Combining Figure 1 This embodiment further includes a drain outlet 23, which is installed on the under-bed air chamber 2 and located directly below the fluidized bed boiler body 6. This arrangement ensures that condensate is discharged quickly, mitigating corrosion of the steel outer shell. Other components and connections are the same as in any of the specific embodiments one through nine.

[0057] In this invention, the under-bed air chamber, fluidized bed boiler body, furnace-separator horizontal flue, cyclone separator, return feeder, furnace return pipe, separator-economizer transition flue, and furnace feed pipe are all lined with heat-insulating materials. The reason for not lining the heating surface is to reduce heat loss, save fuel, and maintain a high furnace temperature. The heat from the flue gas is recovered through the economizer (an air preheater can be connected separately) to heat the pyrolysis materials and primary and secondary air. The flue gas is then purified through a system (which may include desulfurization, denitrification, deacidification, and dust removal processes) before being discharged into the atmosphere through a chimney.

[0058] Combination Figures 1 to 4 The working principle of this invention is as follows: When incinerating pyrolysis residue within the design parameters, the high-temperature resistant gate valve of the boiler described in this invention is in the closed state. When incinerating high-density pyrolysis residue, by opening the high-temperature resistant gate valve, some fluidizing air will be introduced into the furnace through the dispersion pipe. At this time, although the high-density pyrolysis residue will cause a significant increase in bed pressure, the opening of the dispersion pipe will significantly reduce the pressure loss generated by the air distribution plate. The two effects are balanced, which can ensure the stable operation of the bed temperature, bed pressure, and subsequent system without adjusting the air volume or changing the ash discharge speed. In addition, combined with the structure and arrangement of the external pipe outlet at the bottom of the furnace, the structure of the air distribution pipe cap, the design of the primary air pipe position, the insulation structure of the under-bed air chamber, and the combustion method of the under-bed gas, the air temperature, air velocity, and air pressure in the entire under-bed air chamber and inside the furnace are made as uniform as possible. This is not only conducive to the stable operation of the system, but also makes it easier for operators to make adjustments, extends the service life of the equipment, and maximizes the efficiency of energy utilization.

[0059] This invention discloses a material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residues. The air supply system comprises four sets of air sources: primary air, secondary air, under-bed burner self-supplied air, and above-bed burner self-supplied air. The airflow of the under-bed and above-bed burner self-supplied air varies with the burner load and cannot be individually adjusted. The primary air, located under the bed, can be individually adjusted to change the under-bed air temperature, airflow, and bed pressure. The secondary air is used for supplementary combustion and appropriate bed temperature control. When the incineration load remains constant, the under-bed air chamber temperature and furnace bed pressure and temperature can be controlled by adjusting the opening of the primary air, secondary air, and dispersion pipe valves. When the characteristics of the incinerated residue remain constant, the dispersion pipe valve opening is usually not adjusted. If the residue characteristics change drastically, the bed pressure can be stabilized by adjusting the dispersion pipe valves to avoid boiler shutdowns caused by fluidized bed collapse or overturning.

[0060] In addition, a large number of experiments were conducted to verify the technical effectiveness of the invention in practical use:

[0061] For example: The circulating fluidized bed boiler involved in this experiment has a heat load of 0.5MW, a primary air fan with frequency conversion control, and a maximum flow rate of 600m³ / h. 3 / h. The bed material used in the experiment was quartz sand with a particle size of ≤200μm and a bulk density of 1.5t / m³. 3 The material bed height in the furnace was 800 mm. This experiment compared the changes in air chamber pressure and bed pressure difference before and after the arrangement of the dispersion tubes. Detailed experimental data are as follows:

[0062]

[0063] Experiments have verified that, under the same conditions of raw materials, fluidizing air flow rate, and bed height, arranging dispersion pipes can effectively reduce the pressure in the air chamber and the bed. The experiments also verified the following industrial conditions: assuming the ultimate back pressure of the air chamber fan is 15 kPa and the required output is 500 m³ / s. 3 / h, it is difficult to achieve the above parameters without the installation of dispersion tubes; after the installation of dispersion tubes, the fluidized bed boiler can continue to operate stably.

[0064] Therefore, the above experiments have confirmed the following conclusions: 1. The present invention can effectively adjust the bed pressure to avoid downtime caused by equipment over-parameters; 2. The present invention can broaden the adaptability of fluidized bed boilers to incineration feedstocks.

[0065] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make other changes within the spirit of the invention and apply it to fields not mentioned in the invention. Of course, all such changes made in accordance with the spirit of the invention should be included within the scope of protection claimed by the invention.

Claims

1. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue, comprising a fluidized bed boiler body (6), characterized in that: It also includes a subbed air chamber (2), multiple dispersion pipes (5) and multiple high-temperature resistant gate valves (32). The subbed air chamber (2) is installed at the lower part of the fluidized bed boiler body (6). The upper part of the multiple dispersion pipes (5) is connected to the fluidized bed boiler body (6) in a ring array. The lower part of the multiple dispersion pipes (5) is connected to the subbed air chamber (2). Each dispersion pipe (5) is equipped with a high-temperature resistant gate valve (32). The valve opening of the high-temperature resistant gate valve (32) is remotely adjusted by the control program to achieve fluidized bed pressure regulation without changing the combustion load.

2. The adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 1, characterized in that: It also includes multiple furnace lower external pipes (33) and multiple bed under-air external pipes (31). The upper part of each dispersion pipe (5) is inserted into the fluidized bed boiler body (6) at an angle downward through a furnace lower external pipe (33), and the angle between the inclined pipe part of the furnace lower external pipe (33) and the horizontal plane is 20~60°. The lower part of each dispersion pipe (5) is connected to the upper part of the bed under-air chamber (2) through a bed under-air external pipe (31).

3. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 2, characterized in that: Both the horizontal and vertical sections of the under-bed air chamber (2) are filled with under-bed air chamber insulation structures (22), among which the horizontal section of the under-bed air chamber insulation structure (22) presents a throat structure.

4. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 1 or 3, characterized in that: It also includes two primary air ducts (24), which are symmetrically installed on both sides of the under-bed air chamber (2), and the outlets of the two primary air ducts (24) are inclined downwards.

5. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 4, characterized in that: It also includes a metal fiber burner (1), which is arranged horizontally and connected to the horizontal section of the under-bed air chamber (2).

6. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 5, characterized in that: The metal fiber burner (1) includes a metal fiber burner head (20), a burner control box (18), and a gas-air mixing chamber (19). The metal fiber burner head (20) is horizontally inserted into the inner cavity of the under-bed air chamber insulation structure (22) of the under-bed air chamber (2). The gas-air mixing chamber (19) is connected to the outer end face of the horizontal section of the under-bed air chamber (2). The burner control box (18) is connected to the gas-air mixing chamber (19).

7. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 1 or 6, characterized in that: It also includes a fixed structure for the air distribution plate (25), a casting substrate for the air distribution plate (26), and multiple air distribution pipe caps (27). The fixed structure for the air distribution plate (25) is installed on the furnace insulation structure (30) inside the fluidized bed boiler body (6). The casting substrate for the air distribution plate (26) is cast on the fixed structure for the air distribution plate (25). Multiple air distribution pipe caps (27) pass through the casting substrate for the air distribution plate (26) and are fixedly connected to the fixed structure for the air distribution plate (25).

8. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 7, characterized in that: Among the multiple air duct caps (27), one air duct cap (27) is located at the center of the circular air duct fixing structure (25). The air duct cap (27) located at the center is the central cap (39). The other air duct caps (27) are arranged in three layers around the central cap (39) from the inside to the outside.

9. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 8, characterized in that: The radius of the central circle of the other air duct caps (27) arranged in three layers from the inside out is a monotonically increasing arithmetic sequence.

10. A material-adjustable circulating fluidized bed boiler for incinerating pyrolysis residue according to claim 1 or 9, characterized in that: It also includes a drain outlet (23), which is installed on the under-bed air chamber (2) and is located directly below the fluidized bed boiler body (6).

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