A method for melting and vitrifying waste incineration fly ash

Abstract

This invention discloses a method for vitrifying and melting fly ash from waste incineration, comprising the following steps: coal-containing fuel is pneumatically conveyed to a high-temperature, low-oxygen environment within a melting furnace for flameless combustion; fly ash is pneumatically conveyed to the melting furnace for melting; the molten inorganic residue from coal combustion is mixed and fused with the molten fly ash, and then water-quenched to form a glassy substance. This invention efficiently integrates high-temperature, low-oxygen flameless combustion technology and cyclone melting technology for coal-containing fuel. The flame volume of the flameless combustion is several times larger than that of traditional glossy combustion, eliminating localized high-temperature, high-oxygen zones and ensuring a highly uniform temperature field distribution, thus guaranteeing complete combustion of the coal-containing fuel and complete melting of the remaining inorganic residue. The inexpensive coal-containing fuel not only provides the main heat for fly ash melting but also increases the content of acidic oxides in the remaining inorganic residue compared to fly ash, which is beneficial for increasing the Si-O crystal structure and improving the vitrification rate of the slag.

Description

Technical Field

[0001] This invention relates to the field of waste incineration fly ash treatment technology, specifically to a method for melting and vitrifying waste incineration fly ash. Background Technology

[0002] This section provides only background information relevant to this disclosure and does not necessarily constitute prior art.

[0003] Waste incineration fly ash is a secondary pollutant produced during the incineration of municipal solid waste for power generation. It is rich in harmful substances such as heavy metals, dioxins, and chlorides, and is classified as hazardous waste. The high-temperature melting and vitrification treatment technology for waste incineration fly ash achieves high volume reduction and a dioxin decomposition rate of 99.99%. Heavy metals are solidified within the Si-O lattice structure of the glass, completely eliminating environmental risks.

[0004] Currently, most high-temperature melting and vitrification treatments of fly ash from waste incineration use natural gas, electric furnaces, or plasma melting furnaces. These methods generally suffer from uneven temperature fields, low vitrification rates, and high energy consumption and processing costs. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the current high-temperature melting and vitrification treatment technology for waste incineration fly ash, such as uneven temperature field, low vitrification rate and high treatment cost, and thus provide a method for melting and vitrifying waste incineration fly ash.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for vitrifying and melting fly ash from waste incineration includes the following steps:

[0008] Coal-containing fuel is pneumatically transported to a high-temperature, low-oxygen environment in a melting furnace for flameless combustion. Fly ash is pneumatically transported to the melting furnace for melting. The molten inorganic residue from the combustion of coal-containing fuel is mixed and fused with the molten fly ash, and then water-quenched to form a glassy substance.

[0009] The technical solution is further optimized so that the high-temperature environment in the high-temperature and low-oxygen environment is generated by the combustion of gaseous fuels when the furnace is started, and is generated by the combustion of gaseous fuels and coal-containing fuels during normal operation.

[0010] Further optimization of the technical solution is needed, wherein the gaseous fuel includes gaseous fossil fuels and green gaseous fuels.

[0011] To further optimize the technical solution, the melting furnace is divided into a primary cyclone melting zone and a secondary cyclone melting zone from top to bottom. The working temperature of the primary cyclone melting zone is 1200-1350℃, and the working temperature of the secondary cyclone melting zone is 1350-1500℃.

[0012] To further optimize the technical solution, the low-oxygen environment in the high-temperature low-oxygen environment is defined as the oxygen content of the combustion air containing coal fuel being less than 15%, which is generated by controlling the air volume of primary air, secondary air, and the circulation volume of high-temperature flue gas.

[0013] The technical solution is further optimized in that the fly ash is conveyed to the melting furnace by tertiary air, and the gaseous fuel and tertiary air are injected into the melting furnace respectively.

[0014] To further optimize the technical solution, the primary air, secondary air, tertiary air and quaternary air are hot air after the cold air exchanges heat with the high-temperature flue gas discharged from the melting furnace, and the temperature of the primary air, secondary air, tertiary air and quaternary air is 400-600℃.

[0015] The technical solution is further optimized so that the primary, secondary, tertiary and quaternary air flows in the same direction to generate an outer swirling flow in the melting furnace. The molten inorganic matter remaining from the combustion of coal fuel and the molten fly ash are pushed against the furnace wall by centrifugal force as they spiral downward with the outer swirling flow, achieving solid-gas separation and liquid-gas separation. The outer swirling flow forms an inner swirling flow with the same direction of rotation in the lower conical part of the melting furnace. The high-temperature flue gas is drawn into the inner swirling flow and transported to the air preheating system through the high-temperature flue gas duct.

[0016] To further optimize the technical solution, the high-temperature flue gas generated by the combustion of coal-containing fuel and gaseous fuel is partially recycled and mixed with primary air and coal-containing fuel before being fed back into the melting furnace;

[0017] The high-temperature flue gas partial recirculation generated by the combustion of coal-containing fuels and gaseous fuels involves drawing a portion of the high-temperature flue gas from the high-temperature flue gas duct and inputting it into the swirl channel for high-temperature flue gas circulation.

[0018] Further optimize the technical solution, wherein the coal-containing fuel includes, but is not limited to, pulverized coal or coal gangue powder.

[0019] The technical solution of this invention has the following advantages:

[0020] 1. This invention provides a method for vitrification treatment of waste incineration fly ash, which efficiently integrates high-temperature, low-oxygen flameless combustion technology with coal-containing fuel and cyclone melting technology. The inexpensive coal-containing fuel not only provides the main heat for fly ash melting (accounting for over 70%), but also increases the content of acidic oxides SiO2 and Al2O3 in the inorganic residues after coal combustion by several times compared to the fly ash itself. This is beneficial for increasing the Si-O crystal structure and improving the vitrification rate of the slag. The flameless combustion flame volume is several times larger than that of traditional glossy combustion, eliminating localized high-temperature, high-oxygen zones and ensuring a very uniform temperature field distribution, guaranteeing complete combustion of the coal-containing fuel and complete melting of the remaining inorganic residues. The reduction in peak flame temperature and oxygen volume concentration in the combustion zone both contribute to lower NO levels.x The generation of [something] is greatly reduced.

[0021] 2. This invention provides a method for vitrifying and melting fly ash from waste incineration. The high-temperature conditions required for flameless combustion of coal-containing fuels are generated during start-up by the combustion of gaseous fuels, and during normal operation by the combined combustion of gaseous fuels and coal-containing fuels. By utilizing the high temperature generated during melting to simultaneously construct a high-temperature, low-oxygen flameless combustion environment for coal-containing fuels, this method not only eliminates the need for complex and expensive regenerative burners but also fundamentally overcomes the defect of continuous flame flickering during regenerative flameless combustion reversal, resulting in more stable flameless combustion.

[0022] 3. The present invention provides a method for vitrification treatment of fly ash from waste incineration, wherein the coal-containing fuel includes pulverized coal or coal gangue powder.

[0023] Using pulverized coal as fuel has the following advantages: Pulverized coal undergoes low-oxygen, flameless combustion in the primary cyclone melting zone, significantly reducing air consumption and thus substantially minimizing heat loss carried away by the exhaust gas, and reducing NO... X Production volume is significantly reduced. Pulverized coal is inexpensive, and its combustion provides the main heat required for melting in the melting furnace, accounting for over 70% of the total heat required, thus significantly reducing production costs. The acidic oxide content (SiO2) in the inorganic residue after pulverized coal combustion is 50-60%, and the Al2O3 content is 15-20%, which is several times higher than that of waste incineration fly ash (SiO2 content ~25%, Al2O3 content ~7.5%). This can compensate for the lower acidic oxide content of waste incineration fly ash, significantly increasing the water-quenched glass content and resulting in more thorough vitrification.

[0024] Coal gangue is a major industrial solid waste. In areas rich in coal gangue resources, using coal gangue powder that meets the calorific value requirements as the main fuel can not only significantly reduce production costs, but also process the coal gangue at the same time.

[0025] 4. This invention provides a method for vitrifying and melting fly ash from waste incineration, in which a portion of the high-temperature flue gas generated from the combustion of coal-containing and gaseous fuels is recycled, mixed with primary air, and then reintroduced into the melting furnace. This high-temperature flue gas recirculation not only reduces air consumption and improves system thermal efficiency but also reduces NOx emissions. X It increases the production volume and can also raise the mixing temperature of primary air and coal-containing fuel, so that after the primary air carrying coal powder is injected into the first-stage cyclone melting zone of the 1200-1350℃ high-temperature melting furnace, it can quickly rise to more than 900℃ and reach the temperature conditions for flameless combustion.

[0026] 5. The present invention provides a method for vitrification treatment of fly ash from waste incineration, which adopts a two-stage combustion melting and a four-stage air distribution scheme. The two-stage combustion makes the temperature field distribution in the melting furnace more uniform and reasonable, and the four-stage air distribution strengthens the airflow rotation and enhances the disturbance, which is conducive to the flameless combustion of pulverized coal and the rapid heat absorption and melting of fly ash. The two-stage cyclone melting zones have clear functions and support each other, which greatly improves the melting efficiency and the thermal efficiency of the melting furnace. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 The present invention provides a structural diagram of a waste incineration fly ash melting and vitrification treatment system.

[0029] Figure label:

[0030] 1. Fly ash melting system; 11. Swirl channel; 12. Swirl blades; 13. Ash spraying pipe; 14. Burner; 15. High-temperature flue gas duct.

[0031] 2. Melt water quenching system; 21. Water quenching tank; 22. Steam outlet; 23. Slag discharge port; 24. Glass body;

[0032] 3. Air preheating system; 30. Cold air; 31. Primary air; 32. Secondary air; 33. Tertiary air; 34. Quaternary air; 35. Circulating high-temperature flue gas; 36. Exhaust gas; 37. Air coil.

[0033] 4. Coal-containing fuel;

[0034] 5. Gaseous fuels;

[0035] 6. Fly ash. Detailed Implementation

[0036] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure 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 disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0037] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a," "an," and "comprising" as used herein may also mean including the plural forms. The terms "comprising," "including," and "having" are inclusive and therefore indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0038] Although terms such as "first," "second," etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Furthermore, in the description of this invention, unless otherwise expressly specified and limited, the terms "set up" and "connected" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a direct connection or an indirect connection via an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "front," "rear," "center," "inner," "longitudinal," "lateral," "side," "vertical," "outer," etc. Such spatial relative terms are intended to include different orientations of the mechanism in use or operation, in addition to those depicted in the figure. For example, if the mechanism in the figure is flipped, then an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The mechanism may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0040] Waste incineration fly ash contains high concentrations of dioxins and heavy metals, posing a great threat to human health and the ecological environment. The National Hazardous Waste List clearly stipulates that waste incineration fly ash is classified as hazardous waste (No. HW18).

[0041] my country generates approximately 10 million tons of fly ash from waste incineration annually. Currently, apart from a small portion being disposed of in cement kilns, most of this fly ash is treated through stabilization and landfill, posing significant environmental risks.

[0042] The national standard "Technical Requirements for Vitrification Products of Solid Waste" (GB / T 41015-2021) came into effect on July 1, 2022. The standard stipulates that the vitrification content of solid waste products should not be less than 85% and the acid loss rate should not be greater than 3%.

[0043] The high-temperature melting and vitrification treatment technology for fly ash from waste incineration has significant technical advantages, including high volume reduction rate, dioxin decomposition rate of 99.99%, and heavy metals are solidified in the Si-O lattice structure of the glass, completely eliminating environmental risks.

[0044] Currently, most high-temperature melting and vitrification treatments of fly ash from waste incineration use natural gas, electric furnaces, or plasma melting furnaces. These methods generally suffer from uneven temperature fields, low vitrification rates, and high energy consumption and processing costs.

[0045] In summary, the limitations of existing high-temperature melting and vitrification technology for fly ash make it impossible to reliably and economically process waste incineration fly ash.

[0046] To address the aforementioned technical problems, this invention employs a low-oxygen flameless combustion scheme where coal-containing fuel is transported to a high-temperature environment via a low-oxygen gas. This results in a uniform temperature field distribution within the melting furnace, a significantly expanded melting working space, and a substantial increase in melting efficiency and furnace thermal efficiency, while also significantly reducing nitrogen oxide emissions and production costs.

[0047] The specific embodiments of the present invention are described in detail below with reference to the waste incineration fly ash melting and vitrification treatment method of the present invention.

[0048] like Figure 1 As shown, this embodiment discloses a method for vitrifying and melting fly ash from waste incineration. The fly ash 6 is treated using a melting furnace. The furnace body includes a cylinder on top and a cone on the bottom. The top of the cylinder is connected to an air preheating system 3 via a high-temperature flue gas duct 15, and the bottom of the cone is connected to a melt water quenching system. The treatment method includes the following steps: coal-containing fuel 4 is pneumatically conveyed to the high-temperature, low-oxygen environment inside the melting furnace for flameless combustion; fly ash 6 is pneumatically conveyed to the melting furnace for melting; the molten inorganic residue from the combustion of coal-containing fuel 4 is mixed and fused with the molten fly ash 6, and then water quenched to form a glassy substance.

[0049] In this embodiment, high-temperature, low-oxygen flameless combustion technology and cyclone melting technology for coal-containing fuel are efficiently integrated. The high-temperature, low-oxygen flameless combustion of coal-containing fuel complements the high-temperature melting of coal-containing fuel and fly ash. After coal-containing fuel 4, primary air 31, and circulating high-temperature flue gas 35 are introduced into the high-temperature environment of the melting furnace, the pulverized coal rapidly heats up above its ignition point and spontaneously combusts, achieving stable and complete combustion in a low-oxygen atmosphere. The flameless combustion flame volume is several times larger than that of traditional glow flame combustion, eliminating localized high-temperature, high-oxygen zones. The temperature field distribution is wider and more uniform, ensuring complete combustion of the coal-containing fuel and complete melting of the remaining inorganic matter. The reduction in peak flame temperature and oxygen volume concentration in the combustion zone both contribute to the reduction of NO. x The formation of [something] is greatly reduced. Inexpensive coal-containing fuel 4 not only provides the main heat for the melting of fly ash (accounting for more than 70%), but also the content of acidic oxides SiO2 and Al2O3 in the inorganic matter remaining after the combustion of coal-containing fuel 4 is several times higher than that in fly ash, which is conducive to increasing the Si-O lattice structure and improving the glass transition rate of slag.

[0050] It should be noted that after the combustion of coal-containing fuel 4, the remaining inorganic matter melts to form a high-silicon-aluminum liquid melt, and the fly ash melts to form a low-silicon-aluminum liquid melt. The two are then combined, fused, and water-quenched to form a glassy substance.

[0051] The coal-containing fuel 4 is pulverized coal or coal gangue powder. Other coal-containing materials, such as gasification slag, may also be used. The specific composition of these materials is not limited here.

[0052] The use of pulverized coal as fuel 4 has the following advantages: 1. Pulverized coal undergoes low-oxygen, flameless combustion in the primary cyclone melting zone, significantly reducing air consumption and thus significantly minimizing heat loss carried away by the exhaust gas, resulting in lower NO content. X 1. Production volume is significantly reduced. 2. Pulverized coal is inexpensive, and its combustion provides the main heat required for melting in the furnace, accounting for more than 70% of the heat required for melting, thus significantly reducing production costs.

[0053] Coal gangue is a major industrial solid waste. In areas rich in coal gangue resources, using coal gangue powder that meets the calorific value requirements as the main fuel can not only significantly reduce production costs, but also process the coal gangue at the same time.

[0054] In some embodiments, the high-temperature environment in the high-temperature and low-oxygen environment is generated by the combustion of gaseous fuel 5 when the furnace is started, and by the combined combustion of gaseous fuel 5 and coal-containing fuel 4 during normal operation.

[0055] High-temperature air refers to air with a temperature above 900℃ that supports the combustion of coal-containing fuels. Low oxygen refers to the oxygen content in the combustion air being below 15%. Flameless combustion refers to the extended reaction time and multiplied flame volume when coal-containing fuels burn in a high-temperature, low-oxygen atmosphere, without forming a distinct glowing flame.

[0056] The low-oxygen environment in the high-temperature, low-oxygen environment is defined as the oxygen content of the combustion air containing coal fuel 4 being below 15%, achieved by controlling the airflow of primary air 31 and secondary air 32, as well as the recirculation rate of high-temperature flue gas. The combustion air containing coal fuel 4 includes a portion of the recirculated high-temperature flue gas 35, primary air 31, and secondary air 32. Specifically, in a high-temperature environment, the oxygen content of the mixture of primary air 31, secondary air 32, and recirculated high-temperature flue gas 35 is below 15%, thus achieving a low-oxygen atmosphere for the coal fuel. The oxygen content in the recirculated high-temperature flue gas 35 is very low. When the recirculated high-temperature flue gas 35 is introduced into the high-temperature environment and mixed with primary air 31 and secondary air 32, the oxygen content in the mixed gas is reduced. Furthermore, the total amount of primary air 31 and secondary air 32 input into the high-temperature environment can be controlled to further reduce the oxygen content.

[0057] The fly ash melting system 1 includes a melting furnace, which is divided into a primary cyclone melting zone and a secondary cyclone melting zone from top to bottom. The operating temperature of the primary cyclone melting zone is 1200-1350℃. The high-temperature environment of the primary cyclone melting zone is generated by the combustion of gaseous fuel during furnace start-up, and by the combined combustion of gaseous fuel and coal-containing fuel during normal operation. In this embodiment, before the coal-containing fuel is introduced, the high-temperature environment is formed by the combustion of gaseous fuel 5 under the combined action of tertiary air 34. After the coal-containing fuel 4 is spirally introduced through the cyclone channel 11 and under the action of the cyclone blades 12, and the fly ash 6 is pneumatically conveyed and introduced through the tertiary air 33, the high-temperature environment is formed by the combustion of coal-containing fuel 4 and gaseous fuel 5 under the combined action of a portion of circulating high-temperature flue gas, primary air 31, secondary air 32, tertiary air 33, and tertiary air 34. The melting of the residual inorganic matter in the coal-containing fuel 4 takes place in the high-temperature environment after the coal-containing fuel 4 is introduced, and the melting of fly ash 6 takes place in the high-temperature environment after the coal-containing fuel 4 and fly ash 6 are introduced.

[0058] This embodiment utilizes the high temperature generated by melting to simultaneously construct a high-temperature environment for high-temperature, low-oxygen, flameless combustion of coal-containing fuel 4. This not only eliminates the need for complex and expensive regenerative burners, but also fundamentally overcomes the defect of continuous flame jumping during regenerative flameless combustion reversal, resulting in more stable flameless combustion.

[0059] In some embodiments, fly ash is pneumatically conveyed to the melting furnace via the ash spray pipe 13 and the tertiary air 33. In this embodiment, on the one hand, the tertiary air 33 is used to push the fly ash 6, making it easier for it to enter the high-temperature environment; on the other hand, the mixing of the tertiary air 33 and the fly ash 6 can increase the temperature of the fly ash, accelerate its heating to the melting temperature, and save the heat required for melting.

[0060] The operating temperature of the secondary cyclone melting zone is 1350–1500℃. This high-temperature environment is formed by the combustion of coal-containing fuel 4 and gaseous fuel 5 under the combined action of a portion of the circulating high-temperature flue gas 35, primary air 31, secondary air 32, tertiary air 33, and quaternary air 34. Fly ash 6 melts in this high-temperature environment, forming a liquid melt. The heat generated by the combustion of coal-containing fuel 4 and gaseous fuel 5 simultaneously provides heat for the melting of fly ash 6. The high-temperature environment of the secondary cyclone melting zone supports the high-temperature environment of the primary cyclone melting zone, while also creating the high-temperature environment required for the flameless combustion of coal-containing fuel 4.

[0061] In some embodiments, the gaseous fuel 5 includes gaseous fossil fuels and green gaseous fuels. The gaseous fossil fuel can be natural gas. The green gaseous fuel is hydrogen, hydrogen-oxygen, or other green gaseous fuels.

[0062] In some embodiments, primary air 31, secondary air 32, tertiary air 33, and quaternary air 34 are hot air resulting from heat exchange between cold air 30 and the high-temperature flue gas discharged from the melting furnace. The temperature of primary air 31, secondary air 32, tertiary air 33, and quaternary air 34 is 400-600°C, and they rotate in the same direction, repeatedly enhancing the airflow rotation and turbulence to facilitate the low-oxygen flameless combustion of coal-containing fuel 4 while it is suspended in the high-temperature air, and to enable the fly ash 6 to rapidly heat up and melt while suspended in the high-temperature air.

[0063] Furthermore, the primary air 31, secondary air 32, tertiary air 33, and quaternary air 34 rotate in the same direction, generating an external swirling flow within the melting furnace. The molten inorganic residue from the combustion of coal fuel 4 and the molten fly ash 6, moving downwards in a spiral motion with the external swirling flow, are pushed against the furnace wall under centrifugal force, achieving solid-gas separation and liquid-gas separation. Upon reaching the cone, the descending external swirling airflow converges towards the center of the swirling cylinder due to its conical contraction structure. Based on the principle of constant rotational distance, its tangential velocity continuously increases. When the fluid reaches a certain position at the lower end of the cone, it reverses direction from bottom to top in the same direction of rotation from the center of the swirling cylinder, continuing its spiral motion to form an internal swirling airflow. High-temperature flue gas is drawn into the internal swirling flow and transported to the air preheating system via the high-temperature flue gas duct 15.

[0064] In some embodiments, the high-temperature flue gas generated from the combustion of coal-containing fuel 4 and gaseous fuel 5 is partially recirculated and mixed with primary air 31 and coal-containing fuel before being reintroduced into the melting furnace. This high-temperature flue gas recirculation not only reduces air consumption and improves system thermal efficiency but also reduces NOx emissions. X It can increase the production volume and also raise the mixing temperature of primary air 31 and coal-containing fuel 4, so that after the primary air carrying coal-containing fuel 4 is injected into the first-stage cyclone melting zone of the 1200-1350℃ high-temperature melting furnace, it can quickly rise to more than 900℃ and reach the temperature conditions for flameless combustion.

[0065] More specifically, the high-temperature flue gas generated from the combustion of coal-containing fuel 4 and gaseous fuel 5 is partially recirculated by drawing a portion of the high-temperature flue gas from the high-temperature flue gas duct 15 and inputting it into the swirl channel 11 for high-temperature flue gas circulation. In this embodiment, the high-temperature flue gas duct 15 is the connection between the melting furnace and the air preheating system 3. The high-temperature flue gas that has not exchanged heat with the cold air within the high-temperature flue gas duct 15 can be drawn through the high-temperature flue gas circulation pipe, ensuring that the high-temperature flue gas returning to the swirl channel 11 has a high temperature, so as to rapidly heat up the coal-containing fuel 4.

[0066] In some embodiments, the air preheating system 3 includes a heat exchanger shell and an air coil 37. The bottom of the heat exchanger shell is connected to the top of the melting furnace. A cold air inlet 30, a heat-exchanged gas outlet, and a tail gas outlet 36 are sequentially arranged on two opposite side walls of the heat exchanger shell. Cold air 30 to be preheated is introduced into the air coil 37. The cold air 30 exchanges heat with the high-temperature flue gas inside the heat exchanger shell. The tail gas 36, cooled by the heat exchange, is discharged through the tail gas outlet. The heat-exchanged hot air forms primary air 31, secondary air 32, tertiary air 33, and quaternary air 34, which are respectively introduced into different locations within the melting furnace.

[0067] In some embodiments, the melt water quenching system 2 includes a water quenching tank 21, a steam outlet 22, and a slag discharge port 23. The water quenching tank 21 is arranged at the bottom of the cone-shaped part of the melting furnace and contains liquid water. The steam outlet 22 is located on the upper part of the side wall of the water quenching tank and is adapted to discharge the steam generated during water quenching. The slag discharge port 23 is located on the lower part of the side wall of the water quenching tank 21 and is adapted to discharge the glassy substance 24 generated during water quenching.

[0068] Taking coal-containing fuel 4 as an example, the specific treatment method of the above-mentioned waste incineration fly ash melting and vitrification treatment method is as follows:

[0069] First, gaseous fuel 5 is injected into the melting furnace through burner 14 for combustion. At the same time, secondary air 34 is injected into the melting furnace to assist combustion and raise the temperature of the melting furnace. Meanwhile, primary air 31 and circulating high-temperature flue gas 35 are introduced into the top of the furnace body, and secondary air 32 is introduced into the primary cyclone melting zone, raising the furnace temperature of the primary cyclone melting zone of the melting furnace to 1200℃-1350℃, achieving the working temperature and low-oxygen flameless combustion of pulverized coal.

[0070] Then, pulverized coal, driven by the primary air 31 supplied by the air preheating system 3, and a portion of the circulating high-temperature flue gas 35, is injected into the furnace from the top of the melting furnace. At this time, the oxygen content of the mixture of primary air 31, secondary air 32, and the portion of circulating high-temperature flue gas 35 is less than 15%. The primary air 31 and the portion of circulating high-temperature flue gas 35, mixed with pulverized coal, enter the melting furnace and rapidly heat up to above 900°C. Low-oxygen flameless combustion occurs in the swirling flow, maintaining the working temperature of the first-stage cyclone melting zone at 1200-1350°C. Heat is provided to the second-stage cyclone melting zone through furnace wall thermal radiation and swirling flow thermal conduction. The inorganic matter remaining after pulverized coal combustion is melted in the cyclone and pushed towards the furnace wall under centrifugal force. The high-silicon aluminum liquid melt forms a molten film on the furnace wall. A small amount of pulverized coal that has not been completely burned in the cyclone continues to burn on the molten film, melting the inorganic matter. The high-silicon aluminum liquid melt flows down the furnace wall under gravity.

[0071] The gaseous fuel 5 burns in the secondary cyclone melting zone, and the heat generated by the combustion of pulverized coal works together to make the working temperature of the secondary cyclone melting zone reach 1350-1500℃.

[0072] Next, the waste incineration fly ash, after pretreatment by water washing and desalination, enters the secondary cyclone melting zone in the melting furnace under the influence of tertiary air 33. The fly ash 6 rapidly heats up in the cyclone and is pushed against the furnace wall by centrifugal force, melting to form a low-silicon-alumina liquid melt, which flows down the furnace wall under gravity. The high-silicon-alumina liquid melt produced by the melting of inorganic residues from pulverized coal combustion and the low-silicon-alumina liquid melt produced by the melting of waste incineration fly ash converge on the furnace wall. During the process of flowing down the cylindrical furnace wall and the conical tapered constriction tube at the bottom of the melting furnace, they overlap, compound, and fuse, becoming homogenized before entering the water quenching system.

[0073] Finally, the homogenized liquid melt is fed into the water quenching tank 21 and quenched into a glass body 24. The glass body 24 is discharged through the slag discharge port 23, and the water vapor generated during water quenching is discharged through the water vapor outlet 22.

[0074] In the melting furnace, the high-temperature flue gas generated by fuel combustion in the primary and secondary cyclone melting zones is drawn up by the internal cyclone airflow. Part of it is extracted into the primary air cyclone channel in the high-temperature flue gas duct 15, and the rest enters the air preheating system 3 for full heat exchange, so that the air preheating temperature reaches 400-600℃. At the same time, the combustion exhaust gas temperature is reduced to below 900℃, and after treatment by the conventional exhaust gas system, it meets the emission standards.

[0075] It should be noted that the melt water quenching system 2, the air preheating system 3, and the exhaust gas treatment with the temperature reduced to below 900°C are all mature technologies and need no further explanation. This embodiment only provides the simplest description.

[0076] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for vitrifying and melting fly ash from waste incineration, characterized in that, Includes the following steps: The coal-containing fuel is pneumatically transported to the high-temperature, low-oxygen environment of the melting furnace for flameless combustion. The fly ash is pneumatically transported to the melting furnace for melting. The molten inorganic matter remaining after the coal-containing fuel combustion is mixed and fused with the molten fly ash, and then water-quenched to form a glassy substance. The high-temperature environment in the high-temperature and low-oxygen environment is generated by the combustion of gaseous fuels when the furnace is started, and by the combined combustion of gaseous fuels and coal-containing fuels during normal operation. The melting furnace is divided into a primary cyclone melting zone and a secondary cyclone melting zone from top to bottom. The working temperature of the primary cyclone melting zone is 1200-1350℃, and the working temperature of the secondary cyclone melting zone is 1350-1500℃. The low-oxygen environment in the high-temperature low-oxygen environment refers to the oxygen content of the combustion air containing coal fuel being less than 15%, which is generated by controlling the air volume of primary air, secondary air, and the circulation volume of high-temperature flue gas.

2. The method for vitrification treatment of waste incineration fly ash according to claim 1, characterized in that, The gaseous fuels include gaseous fossil fuels and green gaseous fuels.

3. The method for vitrification treatment of waste incineration fly ash according to claim 1, characterized in that, The fly ash is conveyed to the melting furnace by tertiary air, and gaseous fuel and tertiary air are injected into the melting furnace respectively.

4. The method for vitrification treatment of waste incineration fly ash according to claim 3, characterized in that, The primary, secondary, tertiary, and quaternary air are hot air produced after cold air exchanges heat with the high-temperature flue gas discharged from the molten furnace, and the temperature of the primary, secondary, tertiary, and quaternary air is 400-600℃.

5. The method for vitrification treatment of waste incineration fly ash according to claim 4, characterized in that, The primary, secondary, tertiary, and quaternary air flows in the same direction to create an outer swirling flow within the melting furnace. As the molten inorganic residue from coal combustion and the molten fly ash spiral downwards with the outer swirling flow, they are pushed against the furnace wall by centrifugal force, achieving solid-gas separation and liquid-gas separation. The outer swirling flow forms an inner swirling flow with the same direction of rotation in the lower conical section of the melting furnace. High-temperature flue gas is drawn into the inner swirling flow and transported to the air preheating system through a high-temperature flue gas duct.

6. The method for vitrification treatment of waste incineration fly ash according to claim 1 or 2, characterized in that, The high-temperature flue gas generated from the combustion of coal-containing fuel and gaseous fuel is partially recycled and mixed with primary air and coal-containing fuel before being fed back into the melting furnace. The high-temperature flue gas partial recirculation generated by the combustion of coal-containing fuels and gaseous fuels involves drawing a portion of the high-temperature flue gas from the high-temperature flue gas duct and inputting it into the swirl channel for high-temperature flue gas circulation.

7. The method for vitrification treatment of waste incineration fly ash according to claim 1 or 2, characterized in that, The coal-containing fuel includes pulverized coal or coal gangue powder.

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