A fuel type melting furnace system for fly ash disposal and control method thereof

Abstract

The present invention discloses a fuel-type melting furnace system for fly ash disposal, including a fuel-type melting furnace, a rising flue extending upward on one side of the top of the melting furnace, a material inlet and a spray gun socket for inserting a spray gun, and the melting furnace is arranged in a spindle configuration, that is, a configuration with a slightly smaller middle part, a trapezoidal expansion at the bottom, and an inverted trapezoidal expansion at the top. The present invention also discloses a control method for the fuel-type melting furnace system to dispose of fly ash. The melting furnace is arranged in a spindle configuration, which can improve the uniformity of the temperature field in the furnace, make the slag melt better, and the slag splashes onto the inner wall of the furnace with a trapezoidal structure and then flows down, which is easier to form slag protection, and effectively reduces the splashing height, thereby reducing the height of the furnace; the upper structure of the melting furnace is an inverted trapezoid, which can increase the combustion space to ensure the residence time of the gas, reduce the flow rate of the smoke, and be more easily captured in the molten pool, thereby reducing the generation of secondary fly ash.

Description

Technical Field

[0001] The present invention belongs to the technical field of hazardous waste disposal, and in particular relates to a fuel-type melting furnace system for fly ash disposal and a control method thereof. Background Art

[0002] Fly ash from the incineration of domestic waste refers to the bottom ash collected by the flue gas purification system of waste incineration and the bottom ash settled at the bottom of the flue and chimney. The hazardous waste code is 772-002-18. Fly ash from the incineration of domestic waste is rich in heavy metals such as Pb, Cr, and Ni, and contains highly toxic pollutants such as dioxins and polycyclic aromatic hydrocarbons. Therefore, fly ash must be collected separately and must not be mixed with domestic waste, incineration residues, etc., nor with other hazardous wastes.

[0003] At present, fly ash is usually disposed of by chelation + landfill, but this treatment method is currently unbalanced in supply and demand, has high costs, and has limited space. In addition, heavy metal pollutants in landfills will enter the leachate again, causing potential harm to the environment again. Therefore, it is imperative to develop new processes for disposal and resource utilization.

[0004] Plasma technology is also used to treat fly ash at home and abroad. This technology uses electric arc to directly melt fly ash. However, this technology consumes too much energy, has high operation and maintenance costs, is prone to generate secondary fly ash, and is inconvenient to operate.

[0005] The fuel-type melting furnace technology utilizes oxygen-enriched treatment technology. Fuel and oxygen-enriched air are sprayed in from the top spray gun, and the slag-forming reaction of fly ash is all carried out in a closed melting furnace. It has the advantages of high automation, large processing capacity, low energy consumption, small flue gas volume, and strong raw material adaptability. It is the trend of resource disposal of hazardous wastes such as fly ash from the incineration of domestic waste. Fuel-type melting is to use the spray gun gas to strongly stir the molten pool during the melting reaction, so that the material entering the furnace and the peroxidized slag in the molten pool are in full contact, providing kinetic and thermodynamic conditions for the reaction of the smelting material. At the same time, the melt splashed during the stirring process has the effect of capturing and recovering small particles newly added to the furnace. In the operation process of the melting furnace of the prior art, due to the relatively complex and unstable feed components of fly ash, the furnace temperature field and oxygen content are prone to uneven distribution, and it is easy to have a large amount of NO X The slag is generated and the properties of the slag are difficult to control. If the slag is not well controlled and cannot flow out, in serious cases, a dead furnace state may occur and the furnace cannot run smoothly.

[0006] Compared with other fly ash disposal technologies, fuel melting technology has a shorter process, faster reaction speed, simple and compact melting furnace structure, easy maintenance, overhaul and upgrading, and small footprint. However, it requires each subsystem to synchronously and evenly provide the necessary process conditions and be equipped with a reliable automatic control system.

[0007] The stable operation of the feeding system is also related to the stable operation of the melting furnace. The feed amount and composition of fly ash may fluctuate greatly, which will cause changes in the amount of air and oxygen interlocked with it and corresponding changes in the reaction atmosphere in the furnace. In severe cases, slag spraying accidents may occur. Existing melting furnaces generally use copper water jackets or steel water jackets to protect the refractory materials on the inner wall of the furnace body, but this method not only takes away a lot of heat, but also easily forms dew point corrosion; the temperature field is not easy to control evenly; and due to the complex composition of the flue gas, the induced draft fan is prone to failure, resulting in furnace shutdown. Therefore, a more stable control system is needed. Summary of the invention

[0008] In view of the shortcomings of the existing fly ash disposal technology, the present invention provides a fuel type melting furnace system and a control method thereof, so as to achieve the smooth operation of the melting furnace when processing fly ash.

[0009] To achieve the above-mentioned object, the first aspect of the present invention provides a fuel-fired melting furnace system for fly ash disposal, comprising a fuel-fired melting furnace, a top side of the melting furnace is provided with an ascending flue extending upward, a top of the melting furnace is also provided with a material inlet and a spray gun socket for inserting a spray gun, and a bottom of the melting furnace is provided with a slag outlet and a metal outlet;

[0010] The melting furnace is configured in a spindle configuration, that is, a configuration in which the middle portion is slightly smaller, the lower portion is a trapezoidal expansion, and the upper portion is an inverted trapezoidal expansion;

[0011] The inner wall of the furnace body of the melting furnace is coated with a layer of refractory material, and a coil for compressed air circulation is buried in the refractory material, and the two ends of the coil extend out of the outer wall of the furnace body, one end of which is a compressed air inlet and the other end is a hot air outlet;

[0012] The slag outlet is provided with an infrared thermometer and an auxiliary burner;

[0013] A spray gun is inserted into the spray gun socket on the top of the melting furnace, and the spray gun is externally connected to an oxygen-enriched pipeline, a fuel pipeline, and a secondary combustion air pipeline; and an oxygen content analyzer, an oxygen regulating valve, and an oxygen-enriched pipeline pressure transmitter are installed on the oxygen-enriched pipeline, and a fuel regulating valve is installed on the fuel pipeline;

[0014] The ascending flue is provided with an oxygen content analyzer and a flue gas pressure transmitter, wherein: the oxygen content analyzer is used to detect the oxygen content in the flue gas, and forms a control loop with the oxygen regulating valve on the oxygen-enriched pipeline to adjust the opening of the oxygen regulating valve according to the oxygen content in the flue gas; the flue gas pressure transmitter is used to collect the furnace top pressure of the melting furnace, and is externally connected to the induced draft fan, and forms a control loop with it, which is used to control the furnace top pressure through the induced draft fan;

[0015] A furnace body thermocouple is also provided on the upper part of the furnace body of the melting furnace for detecting the temperature in the furnace chamber and forming a control loop with the fuel regulating valve on the fuel pipeline for regulating the fuel regulating valve according to the temperature in the furnace chamber.

[0016] According to a preferred embodiment, the spray gun is also provided with a spray gun controller, which forms a control loop with the oxygen-enriched pipeline pressure transmitter on the oxygen-enriched pipeline, for regulating the insertion depth of the spray gun in the molten pool according to the pressure at the front end of the spray gun collected by the oxygen-enriched pipeline pressure transmitter.

[0017] Preferably, the induced draft fans include two fans arranged in parallel.

[0018] Preferably, the fuel-type melting furnace system of the present invention also includes a feeding system, which includes a fly ash silo, a slag-forming agent silo, and one or more additive silos arranged in parallel; the fly ash silo, the slag-forming agent silo, and the additive silo are respectively connected to the granulator through pipelines, and the finished product silo, the slag-forming agent silo and the additive silo are all provided with weighing modules, the discharge end of the granulator is provided with a feeding belt conveyor, the discharge end of the feeding belt conveyor is provided with a buffer silo, the discharge end of the buffer silo is provided with a feeding belt conveyor, and the discharge end of the feeding belt conveyor points to the material inlet of the melting furnace.

[0019] A second aspect of the present invention provides a control method for disposing fly ash using the above-mentioned fuel-type melting furnace system, comprising the following steps:

[0020] Step 1: Put a proper amount of slag-forming agent into the melting furnace, melt it first to form a molten pool, then insert the spray gun from the spray gun socket on the top of the melting furnace, and extend the front end outlet of the spray gun into the molten pool to spray oxygen-enriched air and fuel, so that the slag splashes onto the surface of the spray gun to form slag protection;

[0021] Step 2: Open the coil buried in the refractory material, and the compressed air enters from the inlet. After heat exchange with the refractory material, the hot compressed air flows out from the outlet and merges with the oxygen pipeline in the oxygen-enriched pipeline to form oxygen-enriched air;

[0022] Step 3: After granulation, fly ash and auxiliary materials enter the melting furnace from the material inlet, and oxygen-enriched air, fuel and secondary fuel wind are sprayed into the melting furnace from the spray gun; after the flue gas is burned in the furnace of the melting furnace, it is discharged from the flue outlet through the ascending flue; in the melting furnace, slag and metal are stratified due to density difference, among which, slag with low density is discharged from the slag outlet at the bottom of the furnace, quenched in the water pool to become glass slag and collected, and metal with high density is discharged from the metal outlet at the bottom of the furnace.

[0023] Preferably, the process of drossing the spray gun in step 1 includes "inserting and lifting" the spray gun into the molten pool, and repeating this process at least 3 times to ensure protection formed on the surface of the spray gun.

[0024] According to a preferred embodiment of the present invention, in step 3, the front end outlet of the spray gun is immersed below the slag liquid level, and the insertion depth of the spray gun is adjusted according to the reading of the oxygen-enriched pipeline pressure transmitter to maintain the front end outlet of the spray gun immersed 200 to 300 mm below the slag liquid level.

[0025] According to the present invention, in step 3, the flue gas discharged from the flue outlet is further discharged through the chimney through the induced draft fan after the waste heat is recovered by the waste heat boiler and purified by the flue gas purification system.

[0026] According to the present invention, in the control loop composed of the flue gas pressure transmitter and the induced draft fan, the induced draft fan is used to maintain a slight negative pressure in the melting furnace, and the frequency of the induced draft fan is adjusted according to the negative pressure collected by the flue gas pressure transmitter to maintain a stable negative pressure on the top of the melting furnace. Preferably, the slight negative pressure is -20Pa to -50Pa.

[0027] According to the present invention, in step 3, a furnace body thermocouple is used to detect the furnace temperature, and the opening of the fuel regulating valve is adjusted according to the furnace temperature to maintain a stable furnace temperature; the reading of the flue gas oxygen content analyzer is used as the operating variable to adjust the oxygen regulating valve to maintain the stability of the flue gas outlet oxygen content.

[0028] According to the present invention, in step 3, the slag temperature at the slag outlet is detected in real time by an infrared thermometer. If the slag temperature is too low, resulting in insufficient fluidity, the power of the spray gun is adjusted to adjust the air volume of the secondary air entering the furnace through the spray gun.

[0029] According to the present invention, in step 3, when slag discharge is not smooth, the auxiliary burner is started to provide heat and promote the flow of slag.

[0030] According to the present invention, in step 3, the granulation of fly ash and auxiliary materials comprises the following steps:

[0031] (1) The fly ash raw material is fed into the fly ash silo, the slag-forming agent is fed into the slag-forming agent silo, and the additive is fed into the additive silo. The amount of fly ash, slag-forming agent and additive is controlled so that the basicity K value is between 0.6 and 0.95;

[0032] (2) The prepared fly ash raw materials, slag-making agents and additives are sent to a granulator for granulation, and the particle size of the fly ash particles is 20 to 30 mm; the finished fly ash particles enter the buffer silo through a feeding belt conveyor.

[0033] The present invention has the following beneficial effects:

[0034] 1. A weighing module is set before feeding, and the amount of slag-making agent and additives can be adjusted according to the feeding situation to maintain the stability of the slag composition and ensure safe and smooth slag discharge. The fly ash is granulated before entering the furnace, which can reduce the amount of smoke and dust and reduce the generation of secondary fly ash.

[0035] 2. The melting furnace is set in a spindle configuration, which can improve the uniformity of the temperature field in the furnace and make the slag melt better. The slag splashes onto the inner wall of the trapezoidal structure of the furnace and then flows down, which is easier to form slag protection and effectively reduces the splashing height, thereby reducing the height of the furnace; the upper structure of the melting furnace is an inverted trapezoid, which can increase the combustion space to ensure the residence time of the gas, reduce the flow rate of the smoke, make it easier to be captured in the molten pool, reduce the generation of secondary fly ash, and reduce the height of the rising flue, thereby reducing the height of the furnace. The temperature field of the furnace of the melting furnace with this structure is more evenly distributed, and can also reduce the generation of NOx.

[0036] 3. Take the flue gas oxygen content and furnace temperature in the flue gas outlet as the control variables, adjust the opening of the oxygen regulating valve to maintain the stable oxygen content at the flue gas outlet.

[0037] 4. By detecting the furnace temperature through the furnace body thermocouple and adjusting the opening of the fuel regulating valve, the furnace temperature field can be kept stable, which can better save fuel and greatly reduce the generation of NOx.

[0038] 5. The present invention eliminates the setting of cooling water and relies on high-quality refractory materials and structures to reduce the heat taken away by the water jacket cooling of the traditional melting furnace design, thereby achieving design optimization and energy conservation and emission reduction of the melting furnace, and avoiding the risks brought by dew point corrosion, thereby achieving design optimization and energy conservation and emission reduction of the melting furnace.

[0039] 6. The infrared thermometer can more intuitively and reliably monitor the temperature and fluidity of the outlet slag to avoid blockage. If the slag temperature is too low, resulting in insufficient fluidity, it can be adjusted by adjusting the output energy of the spray gun, adjusting the air volume, adjusting the feed amount of additives, etc.; the slag can be kept stably discharged from the furnace to avoid blockage.

[0040] 7. Setting a buffer silo with a certain volume can cope with the fluctuation of feed volume, maintain the stability of the amount of material entering the furnace, and meet the needs of various working conditions. The silo is more suitable for the overall flow design.

[0041] 8. The induced draft fan is used to maintain the negative pressure of the entire melting furnace system during the processing process to prevent the material in the furnace from entering the working environment and causing pollution. In normal operation, the two induced draft fans are opened at the same low frequency and 50% each; if one fails, the other is adjusted to the normal frequency and operates alone. The setting of two induced draft fans effectively avoids shutdown caused by induced draft fan failure.

[0042] 9. The present invention realizes precise control of the furnace temperature, pressure and oxygen content of the melting furnace through the above control system and control method, ensures smooth slag discharge, and achieves the purpose of safe and stable disposal of fly ash by the melting furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1It is a control schematic diagram of the fuel type melting furnace system of the present invention.

[0044] Figure 2 This is the structural intention of the fuel type melting furnace of the present invention.

[0045] Figure 3 It is a schematic diagram of the process of the feeding system of the present invention.

[0046] Description of the figure number:

[0047] 100-melting furnace; 1-material inlet; 2-spray gun socket; 3-rising flue; 4-slag outlet; 5-metal outlet; 6-compressed air inlet; 7-hot air outlet; 8-refractory material; 9-spray gun; 10-auxiliary burner; 11-infrared thermometer; 12-furnace body thermocouple; 13-oxygen content analyzer; 14-flue gas pressure transmitter; 15-induced draft fan; 16-chimney; 17-oxygen enrichment pipeline; 18-fuel pipeline; 19-secondary combustion air pipeline; 20-oxygen content analyzer; 21-oxygen regulating valve; 22-oxygen enrichment pipeline pressure transmitter; 23-fuel regulating valve; 24-spray gun controller; 25-coil; 26- Waste heat boiler; 27-air purification system; 30-fly ash silo; 31-slagging agent silo; 32-additive silo; 33-granulator; 34-weighing module; 35-feeding belt conveyor; 36-buffer silo; 37-feeding belt conveyor. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is clearly and completely described below with specific embodiments in conjunction with the accompanying drawings. It should be understood that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0049] like Figure 1 and Figure 2 As shown, the fuel-fired melting furnace system for fly ash disposal of the present invention comprises a fuel-fired melting furnace 100, a rising flue 3 is extended upwardly on one side of the top of the melting furnace 100, a material inlet 1 and a spray gun socket 2 for inserting a spray gun 9 are also provided on the top of the melting furnace 100, a slag outlet 4 and a metal outlet 5 are provided on the bottom of the melting furnace 100; the melting furnace 100 is configured as a spindle, that is, the middle portion is slightly smaller, the lower portion is a trapezoidal expansion, and the upper portion is an inverted trapezoidal expansion.

[0050] The inner wall of the furnace body of the melting furnace 100 is coated with a layer of refractory material 8, and a coil 25 for compressed air circulation is buried in the refractory material 8 for heat exchange between the compressed air and the refractory material 8. The two ends of the coil 25 extend out of the outer wall of the furnace body, one end is a compressed air inlet 6, and the other end is a hot air outlet 7. Considering that fly ash contains a large amount of chloride salts, sulfides and heavy metals, which are highly corrosive in high temperature environments, in order to cope with the erosion of slag in high temperature environments, the refractory material 8 provided on the inner wall of the furnace body of the melting furnace 100 should be a high-chromium material, wherein the chromium content is preferably not less than 30%.

[0051] An infrared thermometer 11 and an auxiliary burner 10 are provided at the slag outlet 4 .

[0052] A spray gun 9 is inserted into the spray gun socket 2 at the top of the melting furnace 100, and the spray gun 9 is externally connected to an oxygen-enriched pipeline 17, a fuel pipeline 18, and a secondary combustion air pipeline 19; and, the oxygen-enriched pipeline 17 is equipped with an oxygen content analyzer 20, an oxygen regulating valve 21 and an oxygen-enriched pipeline pressure transmitter 22, and the fuel pipeline 18 is equipped with a fuel regulating valve 23.

[0053] The ascending flue 3 is provided with an oxygen content analyzer 13 and a flue gas pressure transmitter 14, wherein the oxygen content analyzer 13 is used to detect the oxygen content in the flue gas, and forms a control loop with the oxygen regulating valve 21 on the oxygen-enriched pipe 17 to adjust the opening of the oxygen regulating valve 21 according to the oxygen content in the flue gas; the flue gas pressure transmitter 14 is used to collect the furnace top pressure of the melting furnace 100, and is externally connected to the induced draft fan 15, and forms a control loop with it, which is used to control the furnace top pressure through the induced draft fan 15. In this embodiment, the induced draft fan 15 includes two induced draft fans 15 arranged in parallel. In normal operation, the two induced draft fans 15 are opened at 50% each at the same low frequency; if one fails, the other is adjusted to a normal frequency and operates alone.

[0054] The upper part of the furnace body of the melting furnace 100 is also provided with a furnace body thermocouple 12 for detecting the temperature in the furnace and forming a control loop with the fuel regulating valve 23 on the fuel pipeline 18 for adjusting the opening of the fuel regulating valve 23 according to the temperature in the furnace.

[0055] Furthermore, the spray gun 9 is also provided with a spray gun controller 24, which forms a control loop with the oxygen-enriched pipeline pressure transmitter 22 on the oxygen-enriched pipeline 17, and is used to adjust the insertion depth of the spray gun 9 in the molten pool according to the pressure at the front end of the spray gun 9 collected by the oxygen-enriched pipeline pressure transmitter 22.

[0056] Furthermore, the fuel type melting furnace system of the present invention also includes a feeding system, such as Figure 3As shown, the feeding system includes a fly ash silo 30, a slag-forming agent silo 31, and one or more additive silos 32 arranged in parallel; the fly ash silo 30, the slag-forming agent silo 31, and the additive silo 32 are respectively connected to the granulator 33 through pipelines, and the finished product silo 30, the slag-forming agent silo 31 and the additive silo 32 are all provided with a weighing module 34, and the discharging end of the granulator 33 is provided with a feeding belt conveyor 35, and the discharging end of the feeding belt conveyor 35 is provided with a buffer silo 36, and the discharging end of the buffer silo 36 is provided with a feeding belt conveyor 37, and the discharging end of the feeding belt conveyor 37 points to the material inlet 1 of the melting furnace 100.

[0057] The control method for handling fly ash in the fuel-fired melting furnace system comprises the following steps:

[0058] Step 1: Put a proper amount of slag-forming agent into the melting furnace 100, melt it first to form a molten pool, then insert the spray gun 9 from the spray gun socket 2 on the top of the melting furnace 100, and extend the front end outlet of the spray gun 9 into the molten pool to spray oxygen-enriched air and fuel, so that the slag splashes onto the surface of the spray gun 9 to form slag protection;

[0059] Step 2: Open the coil 25 buried in the refractory material 8, and the compressed air enters from the inlet 6. After heat exchange with the refractory material 8, the hot compressed air flows out from the outlet 7 and merges with the oxygen pipeline in the oxygen-enriched pipeline 17 to form oxygen-enriched air;

[0060] Step 3: After the fly ash and auxiliary materials are granulated, they enter the melting furnace 100 through the material inlet 1, and the oxygen-enriched air, fuel and secondary fuel wind are sprayed into the melting furnace 100 through the spray gun 9; after the flue gas is burned in the furnace of the melting furnace 100, it is discharged from the flue outlet through the ascending flue 3; in the melting furnace 100, the slag and the metal are stratified due to the density difference, among which the slag with low density is discharged from the slag outlet at the bottom of the furnace, quenched in the water pool to become glass slag and collected, and the metal with high density is discharged from the metal outlet at the bottom of the furnace.

[0061] Furthermore, the drossing process in step 1 includes "inserting and lifting" the spray gun 9 into the molten pool, and repeating this process at least 3 times to ensure protection formed on the surface of the spray gun.

[0062] Furthermore, when the spray gun 9 is inserted into the molten pool at different depths, the pressure change will be reflected on the oxygen-enriched pipeline pressure transmitter 22; in step 3, the front end outlet of the spray gun 9 is immersed below the slag liquid level, and the insertion depth of the spray gun 9 is adjusted according to the reading of the oxygen-enriched pipeline pressure transmitter 22 to maintain the front end outlet of the spray gun 9 immersed 200 to 300 mm below the slag liquid level.

[0063] Furthermore, in step 3, the flue gas discharged from the flue outlet is further discharged through the chimney 16 through the induced draft fan 15 after recovering waste heat by the waste heat boiler 26 and being purified by the flue gas purification system 27. The waste heat boiler 26 and the flue gas purification system 27 are both commonly used equipment in the art and will not be described in detail here.

[0064] Furthermore, in the control loop formed by the flue gas pressure transmitter 14 and the induced draft fan 15, the induced draft fan 15 is used to maintain a slight negative pressure in the melting furnace 100, preferably -20 Pa to -50 Pa. According to the negative pressure collected by the flue gas pressure transmitter 14, the frequency of the induced draft fan 15 is adjusted to maintain the negative pressure on the top of the melting furnace 100 stable.

[0065] Furthermore, in step 3, the furnace body thermocouple 12 is used to detect the furnace temperature, and the opening of the fuel regulating valve 23 is adjusted according to the furnace temperature to maintain the temperature of the furnace stable; the reading of the flue gas oxygen content analyzer 13 is used as the operating variable to adjust the oxygen regulating valve 21 to maintain the stability of the oxygen content at the flue gas outlet, so that the possibility of NOx generation is greatly reduced. Thermocouples can also be set in the refractory material 8 to detect the temperature of the refractory material. Considering the composition of the fly ash raw material and the operating cost, the oxygen-enriched air used for the melting of domestic waste fly ash preferably has an oxygen content of 55-60%, which can be adjusted according to actual working conditions and energy prices.

[0066] Preferably, in order to make the measurement more accurate, multiple furnace body thermocouples 12 and flue gas pressure transmitters 14 are provided on the furnace body of the melting furnace 100, and an average value is taken.

[0067] Furthermore, in step 3, the slag temperature at the slag mouth is detected in real time by an infrared thermometer 11. If the slag temperature is too low, resulting in insufficient fluidity, the fuel and air volume entering the furnace through the spray gun 9 are adjusted, and the feed amount of the additive is adjusted at the feed end to optimize the slag shape.

[0068] Furthermore, in step 3, when the slag discharge is not smooth, the auxiliary burner 10 is started to provide heat and promote the flow of slag; and the burner 10 can also burn the escaped furnace gas. Under the complex working conditions of the slag outlet, the detection of the infrared thermometer 11 is stable and reliable, and the detection of the overall temperature field can also be realized.

[0069] In this embodiment, in step 3, the granulation of fly ash and auxiliary materials includes the following steps:

[0070] (1) The fly ash raw material is fed into the fly ash silo 30, the slag-forming agent is fed into the slag-forming agent silo 31, and the additive is fed into the additive silo 32, and the amounts of the fly ash, the slag-forming agent and the additive are controlled so that the basicity K value is between 0.6 and 0.95;

[0071] It is generally believed that the properties of slag are directly related to the basicity K. Al2O3 and SiO2 contribute to the formation of glass, while basic oxides such as CaO contribute to reducing viscosity. When preparing slag-making agents and additives, the basicity K = (CaO + FeO + MgO + K2O + Na2O) / (Al2O3 + SiO2) should be calculated based on the mass of the components in the total feed and an appropriate value should be selected to make the slag fluidity the best and easy to form qualified glass. Generally, the K value is selected to be 0.6-0.95.

[0072] (2) The prepared fly ash raw materials, slag-forming agents and additives are sent to the granulator 33 for granulation, and the particle size of the fly ash particles is preferably 20-30 mm; the finished fly ash particles are temporarily stored in the buffer silo 36 through the feeding belt conveyor 35, and are sent to the feed port 1 of the melting furnace 100 by the feeding belt conveyor 37 when in use.

[0073] By setting a coil 25 for forced air cooling in the high-quality refractory material 8, the temperature of the cooling air is increased to a certain extent after heat exchange with the refractory material 8, and can be used as compressed air for oxygen-enriched air. Such a setting can not only protect the refractory material 8, but also recover heat, reduce energy loss, and avoid the risk of dew point corrosion caused by the traditional water jacket structure, thereby achieving design optimization and energy saving and emission reduction of the melting furnace.

[0074] The melting furnace 100 in the present invention is a spindle structure, that is, the lower structure is a trapezoid, and the upper structure is an inverted trapezoid. The lower structure of the melting furnace is set to a trapezoid, which can improve the uniform distribution of the temperature field in the furnace, which is more conducive to the melting of fly ash. The slag splashes onto the inner wall of the furnace with a trapezoidal structure and then flows down, which is easier to form slag protection for refractory materials and effectively reduces the splashing height, thereby reducing the height of the furnace; the upper structure of the melting furnace is set to an inverted trapezoid, which can increase the combustion space to ensure the residence time of the gas, reduce the flow rate of the smoke, make it easier to be captured in the molten pool, reduce the generation of secondary fly ash, and reduce the height of the rising flue, thereby reducing the height of the furnace. The temperature field of the melting furnace of this structure is more evenly distributed, and can also reduce the generation of NOx.

[0075] Therefore, the fuel type melting furnace system of the present invention has the characteristics of wide adaptability to the materials to be processed, fast reaction speed of the materials in the furnace, large processing capacity, and low smoke and dust yield.

[0076] After high-temperature melting, harmful heavy metal elements in the fly ash are solidified in a dense grid structure wrapped by Si-O bonds. The slag generated by the melting furnace 100 is a glass body, and the metal leaching toxicity test meets the standard. After being identified as qualified, the product can be used as cement auxiliary material or roadbed material.

[0077] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fuel-fired melting furnace system for fly ash disposal, comprising a fuel-fired melting furnace, a rising flue extending upwardly from one side of the top of the melting furnace, a material inlet and a spray gun socket for inserting a spray gun are also provided on the top of the melting furnace, and a slag outlet and a metal outlet are provided at the bottom of the melting furnace, characterized in that: The melting furnace is configured in a spindle configuration, that is, a configuration in which the middle portion is slightly smaller, the lower portion is a trapezoidal expansion, and the upper portion is an inverted trapezoidal expansion; The inner wall of the furnace body of the melting furnace is coated with a layer of refractory material, and a coil for compressed air circulation is buried in the refractory material, and the two ends of the coil extend out of the outer wall of the furnace body, one end of which is a compressed air inlet, and the other end is a hot air outlet, so that the compressed air enters from the inlet, and after heat exchange with the refractory material, the hot compressed air flows out from the outlet and merges with the oxygen pipeline in the oxygen-enriched pipeline to form oxygen-enriched air; The slag outlet is provided with an infrared thermometer and an auxiliary burner; A spray gun is inserted into the spray gun socket on the top of the melting furnace, and the spray gun is externally connected to an oxygen-enriched pipeline, a fuel pipeline, and a secondary combustion air pipeline; and an oxygen content analyzer, an oxygen regulating valve, and an oxygen-enriched pipeline pressure transmitter are installed on the oxygen-enriched pipeline, and a fuel regulating valve is installed on the fuel pipeline; The ascending flue is provided with an oxygen content analyzer and a flue gas pressure transmitter, wherein: the oxygen content analyzer is used to detect the oxygen content in the flue gas, and forms a control loop with the oxygen regulating valve on the oxygen-enriched pipeline to adjust the opening of the oxygen regulating valve according to the oxygen content in the flue gas; the flue gas pressure transmitter is used to collect the furnace top pressure of the melting furnace, and is externally connected to the induced draft fan, and forms a control loop with it, which is used to control the furnace top pressure through the induced draft fan; A furnace body thermocouple is also provided on the upper part of the furnace body of the melting furnace for detecting the temperature in the furnace chamber and forming a control loop with the fuel regulating valve on the fuel pipeline for regulating the fuel regulating valve according to the temperature in the furnace chamber.

2. The fuel type melting furnace system according to claim 1, characterized in that: The spray gun is also provided with a spray gun controller, which forms a control loop with the oxygen-enriched pipeline pressure transmitter on the oxygen-enriched pipeline, and is used to adjust the insertion depth of the spray gun in the molten pool according to the pressure at the front end of the spray gun collected by the oxygen-enriched pipeline pressure transmitter.

3. The fuel type melting furnace system according to claim 1, characterized in that: The induced draft fans include two fans arranged in parallel.

4. The fuel type melting furnace system according to claim 1, characterized in that: It also includes a feeding system, which includes a fly ash silo, a slag-forming agent silo, and one or more additive silos arranged in parallel; the fly ash silo, the slag-forming agent silo, and the additive silo are respectively connected to the granulator through pipelines, and the fly ash silo, the slag-forming agent silo and the additive silo are all provided with weighing modules, the discharging end of the granulator is provided with a feeding belt conveyor, the discharging end of the feeding belt conveyor is provided with a buffer silo, the discharging end of the buffer silo is provided with a feeding belt conveyor, and the discharging end of the feeding belt conveyor points to the material inlet of the melting furnace.

5. A control method for handling fly ash using a fuel-fired melting furnace system according to any one of claims 1 to 4, characterized in that The following steps are involved: Step 1: Put a proper amount of slag-forming agent into the melting furnace, melt it first to form a molten pool, then insert the spray gun from the spray gun socket on the top of the melting furnace, and extend the front end outlet of the spray gun into the molten pool to spray oxygen-enriched air and fuel, so that the slag splashes onto the surface of the spray gun to form slag protection; Step 2: Open the coil buried in the refractory material, and the compressed air enters from the inlet. After heat exchange with the refractory material, the hot compressed air flows out from the outlet and merges with the oxygen pipeline in the oxygen-enriched pipeline to form oxygen-enriched air; Step 3: After granulation, fly ash and auxiliary materials enter the melting furnace from the material inlet, and oxygen-enriched air, fuel and secondary fuel wind are sprayed into the melting furnace from the spray gun; after the flue gas is burned in the furnace of the melting furnace, it is discharged from the flue outlet through the ascending flue; in the melting furnace, slag and metal are stratified due to density difference, among which, slag with low density is discharged from the slag outlet at the bottom of the furnace, quenched in the water pool to become glass slag and collected, and metal with high density is discharged from the metal outlet at the bottom of the furnace.

6. The method according to claim 5, characterized in that The drossing process described in step 1 includes "plunging and lifting" the spray gun into the molten pool, and repeating it at least 3 times to ensure that protection is formed on the surface of the spray gun.

7. The method according to claim 5, characterized in that In step 3, the front end outlet of the spray gun is immersed below the slag liquid surface, and the insertion depth of the spray gun is adjusted according to the reading of the oxygen-enriched pipeline pressure transmitter to maintain the front end outlet of the spray gun immersed 200 to 300 mm below the slag liquid surface.

8. The method according to claim 5, characterized in that In step 3, the flue gas discharged from the flue outlet is further discharged through a chimney via an induced draft fan after waste heat recovery by a waste heat boiler and purification by a flue gas purification system.

9. The method according to claim 5, characterized in that In the control loop composed of the flue gas pressure transmitter and the induced draft fan, the induced draft fan is used to maintain a slight negative pressure in the melting furnace. According to the negative pressure collected by the flue gas pressure transmitter, the frequency of the induced draft fan is adjusted to maintain the negative pressure on the top of the melting furnace stable.

10. The method according to claim 9, characterized in that The micro-negative pressure is -20 Pa to -50 Pa.

11. The method according to claim 5, characterized in that In step 3, the furnace body thermocouple is used to detect the furnace temperature, and the opening of the fuel regulating valve is adjusted according to the furnace temperature to maintain a stable furnace temperature; the reading of the flue gas oxygen content analyzer is used as the operating variable to adjust the oxygen regulating valve to maintain the stability of the flue gas outlet oxygen content.

12. The method according to claim 5, characterized in that In step 3, the slag temperature at the slag outlet is detected in real time by an infrared thermometer. If the slag temperature is too low, resulting in insufficient fluidity, the power of the spray gun is adjusted to adjust the air volume of the secondary air entering the furnace through the spray gun.

13. The method according to claim 5, characterized in that In step 3, when slag discharge is not smooth, the auxiliary burner is started to provide heat to promote the flow of slag.

14. The method according to claim 5, characterized in that In step 3, the fly ash and auxiliary material granulation comprises the following steps: (1) The fly ash raw material is sent into the fly ash silo, the slag-forming agent is sent into the slag-forming agent silo, and the additive is sent into the additive silo. The amount of fly ash, slag-forming agent and additive is controlled so that the alkalinity K value is between 0.6 and 0.95; (2) The prepared fly ash raw materials, slag-making agents and additives are sent to the granulator for granulation. The particle size of the fly ash particles is 20-30 mm; the finished fly ash particles enter the buffer silo through the feeding belt conveyor.

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