Aluminum ash efficient composite combustion system and combustion method

Abstract

The invention discloses an efficient composite combustion system for aluminum ash. The efficient composite combustion system comprises a boiler, a turbulent burner and a boiling fluidized bed. The turbulent burner is installed on the side face of the lower portion of a hearth of the boiler, and an outlet faces a middle shaft of the hearth. The swirling burner comprises a natural gas channel, an aluminum ash channel, a combustion-supporting air channel and a pre-combustion chamber, natural gas and aluminum ash are mixed and combusted in the swirling burner, swirling air is formed at an outlet of the pre-combustion chamber, and a combustion state of hedging disturbance is formed in a hearth; high-pressure fluidizing air is introduced into the boiling fluidized bed, a boiling fluidizing combustion state is formed at the bottom of the hearth, secondary combustion is carried out on large-particle and flame-retardant parts left after combustion of the turbulent burner, and efficient combustion of the aluminum ash is achieved. According to the invention, the aluminum ash can be continuously, efficiently and stably combusted, combustible components in the aluminum ash can be fully combusted, harmless and resource utilization of the aluminum ash is finally realized, and meanwhile, heat generated in the combustion process can be output to heat exchange equipment such as a boiler for heat conversion application.

Description

Technical Field

[0001] The present invention belongs to the technical field of burners and systems for solid waste (including solid hazardous waste) treatment, and in particular relates to a high-efficiency composite combustion system.

[0002] Background technology Aluminum ash is a toxic and harmful solid waste produced in the production process of aluminum industry. Its main components are aluminum oxide (about 50%), aluminum nitride (about 10%), magnesium oxide (about 10%), calcium oxide (about 0.8%), ferric oxide (about 0.5%), metallic aluminum (about 3%), sulfur (about 0.2%), fluorine (about 2.5%) and other trace elements. The fine particle size is about 50-200 mesh, about 70% is fine powder, and the rest is coarse particles with poor particle size uniformity. Its lower calorific value is about 800-1300Kcal / kg, with high ignition point, not easy to ignite, and difficult to burn out.

[0003] There are two main treatment routes for aluminum ash: hydrolysis and combustion. The process route of hydrolysis treatment is relatively complex and has low economic benefits. The combustion route is mainly based on rotary kiln combustion, which has low automation, low combustion heat utilization, large heat loss, and is easy to pollute the environment. At the same time, the aluminum ash burns out for a long time, has a low burnout rate, poor combustion continuity, and large heat loss in the system during the combustion process, and the effective utilization rate of combustion heat is very low. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an aluminum ash high-efficiency composite combustion system, so that the aluminum ash can be burned continuously, efficiently and stably, and the combustible components in the aluminum ash can be fully burned, ultimately achieving the harmless treatment and resource utilization of the aluminum ash. At the same time, the heat generated during the combustion process can also be output to heat exchange equipment such as boilers for heat conversion and application, thereby realizing the resource utilization of aluminum ash and generating considerable economic benefits.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A high-efficiency composite combustion system for aluminum ash, comprising a boiler, a swirl burner and a fluidized bed; the swirl burner is installed on the lower side of the furnace of the boiler, with its outlet facing the central axis of the furnace, and the fluidized bed is arranged at the bottom of the furnace; there are multiple swirl burners, which are centrally symmetrically installed on the lower side of the furnace of the boiler, with their outlets facing the symmetric center;

[0007] The swirl burner includes a natural gas channel, an aluminum ash channel, a combustion-supporting air channel and a pre-combustion chamber. Natural gas and aluminum ash are mixed and burned in the swirl burner. A swirl wind is formed at the outlet of the pre-combustion chamber, forming a counter-disturbance combustion state in the furnace.

[0008] The boiling fluidized bed introduces high-pressure fluidizing air to form a boiling fluidized combustion state at the bottom of the furnace, and performs secondary combustion on the large particles and difficult-to-burn parts left over from the swirl burner, thereby achieving efficient combustion of aluminum ash.

[0009] In one embodiment, the swirl burner further comprises a flue ash channel, wherein the flue ash channel is used to introduce flue ash to mix with the natural gas and aluminum ash for combustion.

[0010] In one embodiment, the number of the swirl burners is four, which are installed on the same plane and divided into two pairs, and the pre-combustion chamber outlets of the two swirl burners in each pair are opposite and located in the same straight line.

[0011] In one embodiment, the vertical height of the center of the horizontal axis of the swirl burner from the bed surface of the boiling fluidized bed is 3 to 5 times the diameter of the pre-combustion chamber nozzle.

[0012] In one embodiment, the channel is connected to the aluminum ash primary fan, and a low-temperature air preheater and an aluminum ash bin are arranged on the connecting pipeline. The normal temperature air output by the aluminum ash primary fan passes through the low-temperature air preheater for heat exchange with the exhaust gas from the boiler, and outputs hot air of 100-200°C, which drives the aluminum ash falling from the aluminum ash bin and is sent into the swirl burner through the channel.

[0013] In one embodiment, the combustion-supporting air channel includes a natural gas combustion-supporting air channel, an inner secondary air channel and an outer secondary air channel. The 400-500°C combustion-supporting air that has undergone heat exchange with the boiler exhaust flue gas through a high-temperature air preheater provides the hot air required for aluminum ash combustion through the inner secondary air channel and the outer secondary air channel.

[0014] In one embodiment, the boiling fluidized bed is connected to a high-pressure fluidizing fan, and a medium-temperature air preheater is arranged on the connecting pipeline. The hot air at 280-350°C after heat exchange with the flue gas discharged from the boiler in the medium-temperature air preheater is pressurized by the high-pressure fluidizing fan and output upward from the boiling fluidized bed to form a boiling fluidized combustion state.

[0015] In one embodiment, the hot flue gas after combustion in the furnace flows to a heat conversion device for waste heat recovery, and the heat conversion device includes a low-temperature air preheater, a medium-temperature air preheater and a high-temperature air preheater.

[0016] In one embodiment, the channels included in the swirl burner are coaxially arranged, and the inlets of each channel are perpendicular to the axis. Except for the external secondary air channel, the outlets of the remaining channels are connected to the pre-combustion chamber through a swirl component. The outlet of the external secondary air channel is arranged around the outlet of the pre-combustion chamber and shrinks toward the axis.

[0017] The present invention also provides a high-efficiency composite combustion method based on the high-efficiency composite combustion system, comprising the following steps:

[0018] Aluminum ash and combustion-supporting air are mixed and ignited in the pre-combustion chamber, swirling air is formed at the outlet of the pre-combustion chamber, and a counter-disturbance combustion state is formed in the furnace;

[0019] High-pressure fluidizing air is introduced into the boiling fluidized bed to form a boiling fluidized combustion state at the bottom of the furnace, and the large particles and difficult-to-burn parts left over from the swirl burner are subjected to secondary combustion to achieve efficient combustion.

[0020] In one embodiment, the mixed and ignited material in the pre-combustion chamber may also include flue ash, wherein the designed combustion amount of flue ash accounts for 0-25% of the total fuel of the system, the designed combustion amount of aluminum ash accounts for 40-80% of the total fuel of the system, and the designed combustion amount of natural gas accounts for 20%-60% of the total fuel of the system. When the designed combustion amount of flue ash accounts for 0 of the total fuel of the system, it means that the combustion material does not contain flue ash.

[0021] In one embodiment, the aluminum ash comprises but is not limited to aluminum oxide, aluminum nitride, magnesium oxide, calcium oxide, iron oxide, metallic aluminum, sulfur, fluorine and trace elements, with a fine particle size of 50-200 mesh, 50-85% of which is fine powder with a particle size of ≤90 μm, and the rest is coarse particles with a particle size of >90 μm, and its lower calorific value is about 800-1300 Kcal / kg;

[0022] The flue ash has a fixed carbon content of 40-65%, a particle size of ≤90 μm, and a calorific value of 3000-4000 Kcal / kg.

[0023] Compared with the prior art, the present invention organically combines a solid powder swirl burner with a boiling fluidized bed, and takes advantage of the material characteristics and combustion characteristics of aluminum ash to give full play to the advantages of the swirl burner in the efficient combustion organization of solid fine powder fuel and air forced mixing, and the characteristics of the boiling fluidized bed in the fluidized combustion organization of low calorific value, high ash content and difficult to burn solid particle fuels. The two are cleverly combined according to certain technical rules to form a set of composite and efficient combustion system. The composite combustion system enables aluminum ash to burn continuously, stably, quickly and efficiently, and at the same time stably delivers high-temperature flue gas to the heat energy conversion device combined with the combustion system, so as to realize the effective utilization of the heat energy of aluminum ash combustion. The aluminum ash after combustion is transformed into general solid waste, which can be used as a refractory raw material and building material for resource utilization. While realizing the pollution-free treatment of aluminum ash, this composite combustion system can convert aluminum ash into a resource that can be efficiently utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the high-efficiency composite combustion system of the present invention.

[0025] Figure 2 It is a schematic diagram of the structure of the swirl burner of the present invention.

[0026] Figure 3 It is a schematic diagram of the combustion state of four swirl burners forming counter-impact disturbance in the furnace in an embodiment of the present invention.

[0027] Figure 4 It is a schematic diagram of the structure of each channel of the swirl burner of the present invention. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0029] In order to realize the resource and harmless utilization of aluminum ash, the present invention provides a high-efficiency composite combustion system, which can realize the efficient, continuous and stable combustion of aluminum ash, and while eliminating the hazardous waste characteristics of aluminum ash through combustion, it can release a large amount of heat energy to the outside, and provide it to subsequent heat energy conversion equipment such as boilers, so as to realize the conversion and application of the heat of aluminum ash combustion, and generate corresponding economic benefits. At the same time, after high-temperature combustion, the components with hazardous waste characteristics such as metal aluminum, aluminum nitride and fluorine in aluminum ash can be converted into oxides with stable performance, eliminating the harm to the environment and soil, and can be used as raw materials for refractory materials and building materials for resource application, and once again play an economic value.

[0030] like Figure 1 , Figure 2 and Figure 3 As shown, the aluminum ash high-efficiency composite combustion system of the present invention mainly includes three parts: a boiler, a swirl burner 4 and a boiling fluidized bed 5. The swirl burner 4 is installed on the lower side of the furnace 6 of the boiler, and the outlet is directed toward the central axis of the furnace 6 to spray the combustion flame to the middle, and the boiling fluidized bed 5 is arranged at the bottom of the furnace 6, specifically, directly below the combustion flame sprayed by the swirl burner 4.

[0031] The swirl burner 4 of the present invention is an integrated multi-mode swirl burner, that is, it has the function of inputting multiple fuels and mixing and burning them. In the present invention, it means that it can burn three combustible materials such as aluminum ash, flue ash, and natural gas separately or simultaneously. Specifically, it at least includes a natural gas channel 9-1, an aluminum ash channel 9-4, a combustion-supporting air channel, and a pre-combustion chamber 11. The natural gas channel 9-1 is used to feed natural gas, the aluminum ash channel 9-4 is used to feed aluminum ash, and the combustion-supporting air channel is used to feed combustion-supporting air. Natural gas and aluminum ash are mixed and burned in the swirl burner 4. Under the action of the combustion-supporting air, a swirl wind is formed at the outlet of the pre-combustion chamber 11. When there are multiple swirl burners 4, a counter-disturbance combustion state 12 is formed in the furnace 6.

[0032] At the same time, due to the characteristics of aluminum ash, the combustion using the swirl burner 4 alone has the problems of poor stable combustion performance and much slag. In view of this phenomenon, the boiling fluidized bed 5 at the bottom of the furnace 6 forms a boiling fluidized combustion state at the bottom of the furnace 6 by introducing high-pressure fluidized air, and the large particles and difficult-to-burn parts left by the swirl burner 4 fall down to the bottom of the furnace 6 and perform secondary combustion under the boiling fluidized combustion state. Finally, the combination of the swirl burner 4 and the boiling fluidized bed 5 achieves the effect of efficient combustion of aluminum ash.

[0033] In the present invention, natural gas is used as gas fuel, and its calorific value is about 8000Kcal / Nm 3 , and it is easy to ignite and burn, so mixing it with aluminum ash can achieve a good combustion effect. The designed combustion amount accounts for about 20% of the total system fuel, and can reach up to 60%.

[0034] Aluminum ash is the object of combustion and treatment, with a fine particle size of about 50-200 mesh, about 70% of which is fine powder (ranging from about 50 to 85%), and the rest is coarser particles > 90μm, and the particle size uniformity is poor. Its lower calorific value is about 1050Kcal / kg, generally ranging from 800 to 1300Kcal / kg, with a high ignition point, not easy to ignite, and difficult to burn out. The designed combustion volume accounts for about 40 to 80% of the total system fuel, and generally more than 70% can be selected.

[0035] In view of the above characteristics of aluminum ash, the present invention combines the combustion advantages of the fluidized bed and the swirl burner to form a composite chamber combustion mode of the swirl burner 4 and the fluidized bed 5. The fluidized bed 5 has good fuel adaptability and high combustion efficiency, and has obvious advantages in the fluidized combustion of low calorific value, high ash content, and difficult to burn solid particle fuels.

[0036] In a further embodiment of the present invention, the swirl burner 4 further includes a flue ash channel 9-3, and the flue ash channel 9-3 is used to feed in flue ash for mixing with natural gas and aluminum ash for combustion. Specifically, a flue ash primary fan 1-2 is designed, and the outlet of the flue ash bin 3-1 is set at the outlet pipeline of the flue ash primary fan 1-2. The normal temperature air output by the flue ash primary fan 1-2 drives the high temperature flue ash falling from the flue ash bin 3-1 and is transported to the flue ash channel 9-3 of the swirl burner 4 through the corresponding conveying pipeline. Similarly, an aluminum ash primary fan 1-1 is designed, and the outlet of the aluminum ash bin 2-1 is set at the outlet pipeline of the aluminum ash primary fan 1-1. The air output by the aluminum ash primary fan 1-1 drives the aluminum ash falling from the aluminum ash bin 2-1 and is transported to the aluminum ash channel 9-4 of the swirl burner 4 through the corresponding conveying pipeline.

[0037] The fixed carbon content of flue ash is about 50%, generally in the range of 40-65%. It is solid ultrafine powder with a fine particle size of about 200 mesh and a particle size of ≤90μm. The calorific value is about 3000-3600Kcal / kg, and can be as high as 4000Kcal / kg under certain conditions. It is easy to ignite and burn. The designed combustion volume accounts for about 10% of the total fuel of the system. By adding flue ash, its high calorific value and easy combustion characteristics are utilized to play a combustion-supporting role in the system.

[0038] In addition, the present invention adopts three kinds of fuels, namely "natural gas, aluminum ash, and flue ash". The integrated multi-mode swirl burner can burn natural gas fuel alone, or burn a mixture of natural gas and another or two solid fuels. The combustion ratio and thermal power of the three fuels can be specifically and finely designed according to needs.

[0039] Figure 2 The schematic diagram of the structure of the integrated multi-mode swirl burner of the present invention is shown, which mainly includes an ignition device 9-7, a natural gas channel 9-1, a natural gas combustion-supporting air channel 9-2, a flue ash channel 9-3, an aluminum ash channel 9-4, an inner secondary air channel 9-5, an outer secondary air channel 9-6, and an anti-coking pre-combustion chamber 11. In the multi-channel structure, the ignition device 9-7 is located at the center of the burner and is used for the initial ignition of the burner. After the ignition gun head is stably ignited, natural gas is introduced into the natural gas channel 9-1, and the flame of the ignition gun head ignites the natural gas in the natural gas channel 9-1. After the natural gas in the natural gas channel 9-1 is stably burned, the amount of natural gas is adjusted to a suitable amount according to the boiler heating speed and the size of the boiler, and is used for the overall heating of the boiler. While heating, the dampers of the inner secondary air channel 9-5 and the outer secondary air channel 9-6 are adjusted to suitable positions to keep the oxygen content at the furnace outlet between 5% and 10%. A small amount of air of about 1 to 3% is introduced into the flue ash channel 9-3 and the aluminum ash channel 9-4 to cool and protect the flue ash and aluminum ash channels. After the natural gas combustion continues for a period of time, observe the furnace temperature. The furnace reaches a certain high temperature and stabilizes for a period of time. Start to add a small amount of aluminum ash, observe the furnace temperature, and increase the amount slowly when the temperature rises slowly. The temperature continues to rise. In this case, add slowly until the designed amount or the actual output of the boiler is reached. The integrated multi-mode swirl burner is used together with the boiler furnace during combustion, and the furnace 6 is an integral part of the combustion system.

[0040] The natural gas combustion-supporting air channel 9-2 provides a large amount of air for burning natural gas in the initial stage of combustion. When the boiler is burning normally, the amount of natural gas combustion is reduced or stopped, and the natural gas combustion-supporting air channel 9-2 only needs to pass a small amount of cooling and anti-blocking purge air. The secondary air of the inner secondary air channel 9-5 is high-temperature air, with a temperature of 400-500°C. The inner secondary air channel 9-5 contains two channels, namely the inner secondary air direct air channel and the inner secondary air cyclone air channel. The inner secondary air direct air channel and the inner secondary air cyclone air channel adjust the diameter and length of the burning flame as needed. When the temperature of the precombustion chamber 11 and the boiler furnace is low (≤850°C), the inner secondary air direct air can be turned off and the inner secondary air cyclone can be turned on. Let the flame ignite and burn in the precombustion chamber 11 at the secondary air outlet of the burner as much as possible. When the temperature of the precombustion chamber 11 and the boiler furnace is high (≥1050°C), the inner secondary air direct air can be turned on and the inner secondary air cyclone can be turned off appropriately. Make the combustion flame longer, part of it burns in the pre-combustion chamber 11, and part of it burns in the boiler furnace. According to the combustion characteristics of not burning at lower temperatures, and fully and violently burning when the temperature reaches a certain high temperature. To ensure combustion, a certain high-temperature environment must be created. When designing the burner, the high-temperature secondary air is set at a position close to the aluminum ash channel 9-4, so that the primary air can be mixed with the secondary air after being ejected, and the combustion temperature is quickly increased to make it burn stably. At the same time, the pre-combustion chamber 11 is designed to burn at the secondary air outlet. The heat after combustion is gathered in the smaller space of the pre-combustion chamber 11, which increases the flue gas temperature in the pre-combustion chamber 11 and provides temperature guarantee for combustion. This burner is designed with an external secondary air channel 9-6. The external secondary air channel 9-6 is a high-temperature wind with a relatively low temperature. The outlet is arranged on the end face of the pre-combustion chamber 11, which is far away from the aluminum ash channel 9-4, to provide some oxygen for burning out in the boiler furnace.

[0041] In a further embodiment of the present invention, when there are multiple swirl burners 4, they are installed symmetrically on the lower side of the furnace 6 of the boiler, and each outlet faces the symmetric center, so as to offset the disturbed combustion state 12. For example, Figure 1 and Figure 3 In the structure shown, there are four swirl burners 4, two of which are installed on each of the two side walls at the bottom of the furnace 6, and a total of four on the two side walls. The four swirl burners 4 are installed on the same plane and are divided into two pairs. The outlets of the pre-combustion chamber 11 of the two swirl burners 4 in each pair are opposite and located in the same straight line, so as to offset the disturbed combustion state 12. In actual applications, the number of swirl burners 4 and the area of ​​the boiling fluidized bed 5 are adjusted according to the total amount of aluminum ash combustion design.

[0042] In a further embodiment of the present invention, the vertical height of the horizontal axis center of the swirl burner 4 from the bed surface of the boiling fluidized bed 5 is 3 to 5 times the nozzle diameter of the pre-combustion chamber 11. This height can ensure that the particles burned by the swirl burner 4 are quickly re-combusted by the boiling fluidized bed 5.

[0043] In a further embodiment of the present invention, the aluminum ash channel 9-4 is connected to the aluminum ash primary fan 1-1, and a low-temperature air preheater 7-1 and an aluminum ash bin 2-1 are arranged on the connecting pipeline. The normal temperature air output by the aluminum ash primary fan 1-1 passes through the low-temperature air preheater 7-1 for heat exchange with the exhaust flue gas from the boiler, and outputs hot air of 100-200°C, which drives the aluminum ash falling from the aluminum ash bin 2-1 and is sent into the swirl burner 4 through the aluminum ash channel 9-4.

[0044] In a further embodiment of the present invention, the combustion-supporting air channel includes a natural gas combustion-supporting air channel 9-2, an inner secondary air channel 9-5 and an outer secondary air channel 9-6. The natural gas combustion-supporting air channel 9-2 is arranged after the outlet of the natural gas channel 9-1 and before the flue ash channel 9-3 and the aluminum ash channel 9-4. The natural gas and the natural gas combustion-supporting air are mixed in the pre-combustion chamber 11 by the natural gas channel 9-1 and the natural gas combustion-supporting air channel 9-2 and ignited by the ignition device 9-7, and then the flue ash and aluminum ash (or aluminum ash alone) are ignited to start efficient combustion in the swirl burner 4. The 400-500°C combustion-supporting air that has undergone heat exchange with the exhaust flue gas of the boiler through the high-temperature air preheater 7-3 provides the hot air required for the combustion of the aluminum ash through the inner secondary air channel 9-5 and the outer secondary air channel 9-6, forming a strong swirl wind at the outlet of the pre-combustion chamber 11.

[0045] In a further embodiment of the present invention, the boiling fluidized bed 5 is connected to the high-pressure fluidizing fan 1-4, and a medium-temperature air preheater 7-2 is arranged on the connecting pipeline. The hot air of 280-350°C after heat exchange with the exhaust gas of the boiler through the medium-temperature air preheater 7-2 is pressurized by the high-pressure fluidizing fan 1-4 and output upward from the boiling fluidized bed 5 to form a boiling fluidized combustion state.

[0046] In a further embodiment of the present invention, the furnace 6 is a space for organizing the swirl burner 4 and the boiling fluidized bed 5 to intensify the combustion, and the aluminum ash is continuously and quickly burned in a high temperature environment above 1000°C, so that the aluminum ash is converted from hazardous waste to general solid waste, which can be used as a refractory and building material. In this space, the aluminum ash releases a large amount of heat energy to the outside, and the drum absorbs the heat and transports it to the application workshop, generating corresponding economic benefits. The hot flue gas after combustion in the furnace 6 flows to the heat conversion device for waste heat recovery, and then passes through the subsequent flue gas environmental protection treatment device, and finally reaches the chimney for emptying. After the aluminum ash is burned at a high temperature in the furnace 6, an oxide with stable performance is generated, which eliminates the harmfulness of the aluminum ash raw material to the environment and soil. It can be used as a raw material for refractory materials and building materials for resource recycling and continues to play an economic value.

[0047] The heat conversion device of the present invention comprises a low-temperature air preheater 7-1, a medium-temperature air preheater 7-2 and a high-temperature air preheater 7-3. The low-temperature air preheater 7-1 is installed on the outlet pipeline of the aluminum ash primary fan 1-1. The normal temperature air output by the aluminum ash primary fan 1-1 exchanges heat with the exhaust flue gas of the boiler through the low-temperature air preheater 7-1, and outputs hot air of 100-200°C, which drives the aluminum ash falling from the aluminum ash bin 2-1, on the one hand, to realize the transportation to the aluminum ash channel 9-4, and on the other hand, to realize the preheating of the aluminum ash. The present invention uses a high-pressure fluidizing fan 1-4 to transport air to the medium-temperature air preheater 7-2. The medium-temperature air preheater 7-2 forms high-temperature air of 280-350°C after heat exchange between the air and the exhaust flue gas of the boiler, and forms a boiling fluidized combustion state at the lower part of the furnace 6 of the boiler. The present invention utilizes a secondary fan 1-3 to transport air to a high-temperature air preheater 7-3, which forms hot air at 400-500°C after heat exchange between the air and the exhaust gas from the boiler. The hot air is then distributed through a secondary air distribution box 8 to be provided to the natural gas combustion-supporting air channel 9-2, the inner secondary air channel 9-5, the outer secondary air channel 9-6 and the boiler burnout air nozzle 10 in the upper middle part of the furnace 6.

[0048] The processing flow and chemical reaction formula of aluminum ash in the aluminum ash composite high-efficiency combustion system of the present invention are as follows:

[0049] The secondary aluminum ash processed or collected from the primary aluminum ash → is transported to the aluminum ash bin 2-1 in front of the boiler furnace → is pneumatically transported to the swirl burner 4 through the aluminum ash feeding equipment 2-2 at the bottom of the aluminum ash bin 2-1 and the aluminum ash primary fan 1-1 → the swirl burner 4 distributes air to organize combustion → the combustion flame and flue gas enter the furnace 6 for heat exchange → the heavy large-particle aluminum ash falls to the boiling fluidized bed 5 at the bottom of the furnace 6 for secondary combustion → the fly ash after burning is collected by the dust collector at the rear of the boiler, and the ash at the bottom of the boiler is collected by the dry slag cooler → the ash is sold to building materials companies.

[0050] Aluminum ash contains metallic aluminum (AI), aluminum nitride (AlN) and other hazardous waste components. After high-temperature combustion, the main component generated is harmless aluminum oxide (Al2O3), which can be used as a high-quality raw material for refractory materials, permeable bricks, water purifiers, calcium aluminate and other products. Some of the reaction formulas involved are as follows:

[0051] 4Al+3O2=2Al2O3

[0052] 4AlN+3O2=2Al2O3+2N2

[0053] 4Al2C3+6O2=2Al2O3+3CO2

[0054] The current aluminum ash combustion route is mainly based on the rotary kiln method. This combustion method has a low aluminum ash burnout rate, poor combustion continuity, large system heat dissipation losses during the combustion process, and a very low effective utilization rate of combustion heat.

[0055] The composite high-efficiency combustion system of the present invention is a system that combines a swirl burner with a boiling fluidized bed to achieve strong mixing, stable and efficient combustion, full utilization of waste heat, and recoverable slag. It can effectively solve the current problems of insufficient mixing of aluminum ash combustion, low combustion efficiency, and waste of waste heat.

[0056] In more embodiments of the present invention, the aluminum ash high-efficiency composite combustion system includes but is not limited to the system process and equipment configuration directly disclosed in this patent, and also includes design variations based on the system process principle disclosed in this patent. For example, the furnace 6 in this system can be a vertical structure or a horizontal structure; the swirl burner 4 can be designed and deformed into a single-mode, double-mode, and other structural forms and corresponding functions according to the type of combustible material.

Claims

1. A high-efficiency composite combustion system for aluminum ash, characterized in that: The invention comprises a boiler, a swirl burner (4) and a boiling fluidized bed (5); the swirl burner (4) is installed on the lower side of the furnace (6) of the boiler, with the outlet facing the central axis of the furnace (6); the boiling fluidized bed (5) is arranged at the bottom of the furnace (6); the swirl burner (4) is in multiple numbers and is centrally symmetrically installed on the lower side of the furnace (6) of the boiler, with the outlet facing the symmetrical center; The swirl burner (4) comprises a natural gas channel (9-1), an aluminum ash channel (9-4), a combustion-supporting air channel and a pre-combustion chamber (11); natural gas and aluminum ash are mixed and burned in the swirl burner (4); a swirl wind is formed at the outlet of the pre-combustion chamber (11), and a counter-turbulent combustion state (12) is formed in the furnace (6); The boiling fluidized bed (5) introduces high-pressure fluidized air to form a boiling fluidized combustion state at the bottom of the furnace (6), and performs secondary combustion on the large particles and difficult-to-burn parts left over from the swirl burner (4), thereby achieving efficient combustion of aluminum ash.

2. The aluminum ash high-efficiency composite combustion system according to claim 1 is characterized in that: The swirl burner (4) further comprises a flue ash channel (9-3), wherein the flue ash channel (9-3) is used to introduce flue ash for mixing with the natural gas and aluminum ash for combustion.

3. The aluminum ash high-efficiency composite combustion system according to claim 1 is characterized in that: The number of the swirl burners (4) is four, which are installed on the same plane and divided into two pairs, and the pre-combustion chamber (11) outlets of the two swirl burners (4) in each pair are opposite and located in the same straight line.

4. The aluminum ash high-efficiency composite combustion system according to claim 1, 2 or 3, characterized in that: The vertical height of the horizontal axis center of the swirl burner (4) from the bed surface of the boiling fluidized bed (5) is 3 to 5 times the nozzle diameter of the pre-combustion chamber (11).

5. The aluminum ash high-efficiency composite combustion system according to claim 1 is characterized in that: Hot flue gas after combustion in the furnace (6) flows to a heat conversion device for waste heat recovery. The heat conversion device comprises a low-temperature air preheater (7-1), a medium-temperature air preheater (7-2) and a high-temperature air preheater (7-3).

6. The aluminum ash high-efficiency composite combustion system according to claim 5, characterized in that: The aluminum ash channel (9-4) is connected to the aluminum ash primary fan (1-1), and a low-temperature air preheater (7-1) and an aluminum ash bin (2-1) are provided on the connecting pipeline. Normal-temperature air output by the aluminum ash primary fan (1-1) passes through the low-temperature air preheater (7-1) and exchanges heat with exhaust gas from the boiler, outputting hot air at 100-200°C, driving the aluminum ash falling from the aluminum ash bin (2-1) and delivering it to the swirl burner (4) through the aluminum ash channel (9-4).

7. The aluminum ash high-efficiency composite combustion system according to claim 5, characterized in that: The combustion-supporting air channel includes a natural gas combustion-supporting air channel (9-2), an inner secondary air channel (9-5) and an outer secondary air channel (9-6). The 400-500°C combustion-supporting air, which has undergone heat exchange with boiler exhaust gas through a high-temperature air preheater (7-3), provides hot air required for aluminum ash combustion through the inner secondary air channel (9-5) and the outer secondary air channel (9-6).

8. The aluminum ash high-efficiency composite combustion system according to claim 5, characterized in that: The boiling fluidized bed (5) is connected to a high-pressure fluidizing blower (1-4), and a medium-temperature air preheater (7-2) is provided on the connecting pipeline. The hot air at 280-350°C after heat exchange with the flue gas discharged from the boiler by the medium-temperature air preheater (7-2) is pressurized by the high-pressure fluidizing blower (1-4) and output upward from the boiling fluidized bed (5) to form a boiling fluidized combustion state.

9. The aluminum ash high-efficiency composite combustion system according to claim 1, characterized in that: The swirl burner (4) comprises channels arranged coaxially, the inlets of the channels being perpendicular to the axis, and the outlets of the channels, except for the external secondary air channel (9-6), being connected to the pre-combustion chamber (11) via a swirl assembly, wherein the outlet of the external secondary air channel (9-6) is arranged around the outlet of the pre-combustion chamber (11) and is contracted toward the axis.

10. A high-efficiency composite combustion method of aluminum ash based on the aluminum ash high-efficiency composite combustion system according to any one of claims 1 to 9, characterized in that: The steps include: Aluminum ash and combustion-supporting air are mixed and ignited in a pre-combustion chamber (11), swirling air is formed at the outlet of the pre-combustion chamber (11), and a counter-turbulent combustion state (12) is formed in the furnace (6); High-pressure fluidizing air is introduced into the boiling fluidized bed (5), forming a boiling fluidized combustion state at the bottom of the furnace (6), and secondary combustion is performed on the large particles and difficult-to-burn parts left over from the swirl burner (4), thereby achieving efficient combustion of aluminum ash.

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