Fly ash melting device and method

Abstract

The invention discloses a fly ash melting device, which belongs to the field of fly ash melting, and comprises a furnace body, a Joule heat generating device and a control device fixed on the furnace body. The furnace body is also provided with a nitrate water overflow port, a feeding device and a material channel discharge device; the feeding device comprises a main feeding pipe, a plurality of distribution pipes connected to the main feeding pipe, a driving device for driving the main feeding pipe to rotate, and a feeder; a liquid level meter, a thermometer and an auxiliary electrode are fixed on the material channel discharge device. The invention also discloses a preparation method for fly ash melting, wherein 10 parts of fly ash and 1.5 to 10 parts of auxiliary materials containing silicon oxide are weighed, mixed, added to the furnace body, and the fly ash is melted by electricity, and the temperature in the furnace body is controlled between 800 and 1500°C; when discharging, the temperature in the material channel discharge device is maintained at 800 to 1300°C. The invention does not generate secondary pollution, has good sealing performance during feeding, and evenly spreads materials. The fly ash is melted by electricity, and the heat loss is small, and heavy metals are easily discharged, and is suitable for the melting of all fly ashes.

Description

Technical Field

[0001] The invention belongs to the field of fly ash melting, relates to a fly ash melting device and also relates to a fly ash melting method. Background Art

[0002] In recent years, the scale of my country's waste incineration power generation industry has continued to expand. In the process of waste incineration power generation, the flue gas carries low-boiling-point heavy metals, dioxins, furans and other harmful substances. At present, most of them use the method of spraying activated carbon to adsorb these harmful substances. The activated carbon after adsorption and the solid particles carried in the flue gas are captured by bag filters or other flue gas purification equipment to form waste incineration fly ash. Harmful substances such as heavy metals, dioxins and furans in fly ash have great harm to the environment.

[0003] In the prior art, the best method for melting fly ash is the plasma fly ash melting method. Graphite rod electrodes are installed in the furnace, and plasma is directly generated in the furnace through the discharge of the electrodes, and the fly ash is heated by the plasma to melt it. However, the disadvantages of this melting method are: the thermal efficiency of melting is not high, the electrode consumption is fast, and the temperature distribution in the furnace is high at the top and low at the bottom. Fly ash contains a large amount of chlorides and sulfates. After the fly ash is melted, the chlorides and fly ash form nitrate water. The local high temperature in the upper part of the furnace promotes the volatilization of the low-boiling nitrate water in the slag to form secondary fly ash, which pollutes the environment; while the temperature in the lower part of the furnace is low, which makes the bottom slag poor in fluidity and easily blocks the slag outlet. At the same time, the furnace must have an opening to throw the fly ash in, but the opening cannot be sealed in time, and harmful substances evaporate into the air, causing secondary pollution. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a fly ash melting device to achieve the purpose of uniform feeding, strong sealing of the feeding port and no secondary pollution.

[0005] Another technical problem to be solved by the present invention is to provide a method for melting fly ash so as to achieve a complete reaction in the preparation process without causing secondary pollution.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: a fly ash melting device, comprising a furnace body with an inner cavity, a Joule heat generating device and a control device fixed on the furnace body, the furnace body is also provided with a nitrate water overflow port, a feeding device, and a material channel discharge device for the fly ash melt to flow out;

[0007] The feeding device includes a main feeding pipe extending from the inner cavity of the furnace body to the outside, a plurality of distribution pipes connected to the main feeding pipe, a driving device for driving the main feeding pipe to rotate, and a feeder with one end located above the main feeding pipe and the other end connected to the material tank, wherein the distribution pipe is arranged in the inner cavity of the furnace body;

[0008] The material channel discharge device is provided with a liquid level meter, a thermometer and an auxiliary electrode for controlling the feeding amount of the feeder;

[0009] The driving device, the Joule heat generating device, the auxiliary electrode, the thermometer, the feeder, the liquid level meter and the control device form a closed loop.

[0010] As a limitation of the present invention: the bottom of the furnace body is a cone, and a bottom liquid discharge outlet is provided on the bottom cone, a molybdenum discharger is fixedly provided on the bottom liquid discharge outlet, a temperature control electrode is fixedly provided on the discharger, and a nitrogen generator for introducing nitrogen into the discharger is fixedly provided on the outside of the discharger.

[0011] As a further limitation of the present invention: the interior of the furnace body is made of high temperature resistant material, and the exterior is made of heat insulation material.

[0012] As another limitation of the present invention: the nitrate water overflow port and the material channel discharge device are both provided with silicon carbon rods for controlling the temperature to be constant.

[0013] As a further limitation of the present invention: a funnel-shaped transition bin is fixedly provided at one end of the main feed pipe connected to the feeder, and the distribution pipes are radially arranged around the circumference of the main feed pipe.

[0014] A fly ash melting method is carried out in the following steps:

[0015] Step 1: weigh 10 parts of fly ash and 1.5 to 10 parts of auxiliary materials containing silicon oxide, and mix them to form a raw material;

[0016] Step 2: The raw materials are layered into the inner cavity of the furnace body through the feeding device, and then the fly ash is melted by electricity through the Joule heat generating device;

[0017] Step 3: adjusting the control device to load current to the Joule heat generating device, so that the temperature of the fly ash melting in the inner cavity of the furnace body is controlled between 800 and 1500° C., and the temperature of the upper part of the inner cavity of the furnace body covering the raw materials is less than or equal to 200° C.;

[0018] Step 4: When discharging the material, load the auxiliary electrode in the material channel discharge device with current to keep the temperature in the material channel discharge device at 800-1300°C.

[0019] As a limitation to the fly ash melting method: the auxiliary material is any one of quartz sand or glass powder, or a mixture of the two.

[0020] As another limitation of the fly ash melting method: in the step 4, when discharging, current is applied to the temperature control electrode on the discharger to keep the temperature in the discharger at 800-1300°C, and the nitrogen generator is turned on at the same time.

[0021] As a further limitation of the fly ash melting method: a silicon carbon rod is fixed in the nitrate water overflow port, and current is applied to the silicon carbon rod at the nitrate water overflow port to keep the temperature at the nitrate water overflow port at 600-1400°C.

[0022] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0023] (1) The furnace body of the present invention is provided with a nitrate overflow port. When the fly ash is melted by electricity, since the furnace body is operated with a cold top, the raw materials for melting are covered layer by layer in the inner cavity through the feeding device. Since the bottom temperature of the furnace body is relatively high, the upper surface of the fly ash melt is continuously covered with new raw materials for melting the fly ash, forming a temperature insulation layer, so that the temperature of the upper part of the inner cavity of the furnace body is relatively low, which is much lower than the volatilization temperature of the nitrate, and no secondary pollution is generated. In addition, since the viscosity of the nitrate is very low, it flows like water, and the fly ash floating in the furnace body is not easily oxidized. On the ash melt, nitrate water automatically flows out from the nitrate water overflow port, and the temperature in the furnace body gradually increases from top to bottom. The fly ash melt at the bottom of the pool is in a high temperature state and has strong fluidity, which is convenient for discharge from the bottom of the furnace body or through the material channel discharge device. A feeding device that can rotate 360 ​​degrees is provided on the furnace body. The main feeding pipe of the feeding device extends into the furnace body. When feeding, there is no need to open the lid back and forth, which increases the sealing of the furnace body, can effectively prevent the volatilization of pollutants, can reduce the heat loss in the furnace body, and has high thermal efficiency.

[0024] (2) The bottom of the furnace body of the present invention is a cone. The heavy metals in the fly ash melting process accumulate on the cone at the bottom of the furnace body, which is conducive to the discharge of heavy metals from the discharger along with the fly ash melt. When discharging, the fly ash melt in the discharger is heated by the temperature control electrode to reduce the viscosity of the fly ash melt, which is convenient for outflow. The discharge speed is adjusted by controlling the current applied to the temperature control electrode. A nitrogen generator is provided on the discharger. Because the discharger is made of molybdenum, nitrogen is continuously passed into the discharger to form a nitrogen curtain, which seals the hole, prevents air from entering, and protects the discharger from oxidation.

[0025] (3) In order to prevent the nitrate water from solidifying at the nitrate water overflow port during the outflow process, the nitrate water overflow port is provided with a silicon carbon rod for heating, and the temperature is controlled between 600 and 1400° C., so that the nitrate water can be quickly collected;

[0026] (4) The material channel discharge device of the present invention is provided with a silicon carbon rod and an auxiliary electrode, so that the fly ash melt can maintain a constant temperature during the discharge process;

[0027] (5) A funnel-shaped transition bin is fixedly provided at one end of the main feed pipe of the present invention which is connected to the feeder, so that the feeder can throw all the raw materials into the main feed pipe without scattering them to the outside. The distribution pipes are arranged radially around the circumference of the main feed pipe, so that the raw materials can be evenly scattered into the inner cavity of the furnace body.

[0028] In summary, the present invention will not generate secondary pollution during the fly ash melting process, has good sealing performance during the feeding process, and evenly spreads the material. It can automatically replenish raw materials according to the liquid level in the furnace body. It uses electricity to melt the fly ash, has low heat loss and high efficiency, and heavy metals are easy to discharge. It is suitable for the melting of all fly ashes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 It is a cross-sectional structural schematic diagram of embodiment 1 of the present invention;

[0031] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of AA;

[0032] Figure 3 It is a schematic structural diagram of the discharger 10.

[0033] In the figure: 1-furnace body, 2-Joule heat generating device, 3-feeding device, 31-main feeding pipe, 32-distributing pipe, 33-driving device, 331-motor, 332-first gear, 333-second gear, 4-feeder, 5-silicon carbon rod, 6-channel discharge device, 61-lower horizontal channel, 62-rising channel, 63-upper horizontal channel, 7-auxiliary electrode, 8-liquid level meter, 9-thermometer, 10-discharger, 11-nitrogen generator, 12-material tank, 13-nitrogen water overflow port, 14-transition bin, 15-temperature control electrode. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the fly ash melting device and method described herein are preferred embodiments, which are only used to illustrate and explain the present invention and do not constitute a limitation to the present invention.

[0035] Example 1 Fly ash melting device

[0036] In this embodiment, Figure 1 , Figure 2 , Figure 3 As shown, a fly ash melting device comprises a furnace body 1 with an inner cavity, the bottom of the furnace body 1 is a cone, and a bottom liquid discharge port is provided on the bottom cone, and the bottom liquid discharge port is a stepped port, that is, the upper part ( Figure 1 The upper part) has a large diameter, and the lower part ( Figure 1 The diameter of the discharger 10 is small, and a molybdenum discharger 10 is fixedly arranged on the bottom liquid discharge outlet, and the shape of the discharger 10 fits the shape of the stepped mouth. A temperature control electrode 15 is fixedly arranged on the discharger 10, and the temperature in the discharger 10 is controlled by loading current to the temperature control electrode 15. When the temperature in the discharger 10 is high, the viscosity of the fly ash melt decreases, the fluidity becomes better, and it can flow out of the discharger 10 quickly; when the temperature in the discharger 10 is low, the viscosity of the fly ash melt increases, the fluidity becomes worse, and the speed of flowing out of the discharger 10 becomes slower. A nitrogen generator 11 is fixedly arranged on the outside of the discharger 10 to prevent air from entering the discharger 10. The nitrogen generator 11 of this embodiment adopts the existing technology. Because the discharger 10 is made of molybdenum, nitrogen is continuously passed into the discharger 10 to form a nitrogen curtain, which seals the hole, prevents air from entering, and protects the discharger 10 from being oxidized. The part of the inner cavity of the furnace body 1 used for the fly ash melting reaction is made of high temperature resistant material, and the outside is made of heat insulation material.

[0037] The furnace body 1 is provided with a Joule heat generating device 2. The Joule heat generating device 2 of the present embodiment includes a plurality of AC electrodes for main melting. Six AC electrodes for main melting are evenly provided around the circumference of the furnace body 1 and close to the bottom of the furnace body 1. The electrodes are used to heat the bottom of the fly ash melt so that the temperature of the fly ash melt increases from bottom to top ( Figure 1 The temperature of the furnace body 1 is gradually increased from bottom to top to ensure that the temperature of the upper part of the inner cavity of the furnace body 1 is relatively low, so that the nitrate water is not easy to volatilize and flows out smoothly from the nitrate water overflow port 13.

[0038] The furnace body 1 is provided with a nitrate water overflow port 13, which first extends horizontally to the outside and then extends downward along the furnace body 1 to form a channel for liquid circulation. The nitrate water overflow port 13 is fixedly arranged at the upper part of the furnace body 1, and is substantially flush with the surface of the fly ash melt. During the fly ash melting process, the nitrate water floats on the upper surface of the fly ash melt. Therefore, when nitrate water is generated, it can flow out quickly along the nitrate water overflow port 13. At the same time, in order to allow the nitrate water to flow out smoothly, silicon carbon rods 5 for controlling constant temperature are fixedly arranged in the channel extending horizontally and downwardly from the nitrate water overflow port 13 to ensure that the temperature at the nitrate water overflow port 13 is constant.

[0039] The upper part of the furnace body 1 ( Figure 1The upper part) is rotatably connected to a feeding device 3 through a bearing, and the feeding device 3 includes a main feeding pipe 31, and the main feeding pipe 31 extends from the inner cavity of the furnace body 1 to the outside. The main feeding pipe 31 is located at one end of the inner cavity of the furnace body 1, and a plurality of distribution pipes 32 are fixedly provided. The distribution pipes 32 are connected to the main feeding pipe 31, and are arranged radially around the circumference of the main feeding pipe 31, so that the end of the distribution pipe 32 not connected to the main feeding pipe 31 is basically flush with the nitrate overflow port 13, and in the process of spreading the material, the raw materials can be evenly spread into the inner cavity of the furnace body 1. The main feeding pipe 31 is located at one end of the outside of the furnace body 1. The transition bin 14 is connected to the feeder 4, and the feeder 4 adopts the existing technology. The feeder 4 can quantitatively feed the raw materials in the material tank 12 into the funnel-shaped transition bin 14 on the main feeding pipe 31. The main feed pipe 31 is provided with a driving device 33 for driving the main feed pipe 31 to rotate. The driving device 33 of this embodiment includes a first gear 332 fixed on the main feed pipe 31, and a second gear 333 connected to the first gear 332 through a chain. The motor 331 drives the second gear 333 to rotate, and finally the main feed pipe 31 rotates continuously 360 degrees.

[0040] The furnace body 1 is provided with a channel discharge device 6 for the outflow of the fly ash melt, and the channel discharge device 6 includes a lower horizontal channel 61, a vertically arranged ascending channel 62 and an upper horizontal channel 63, and the lower horizontal channel 61 is connected to the bottom cone of the furnace body 1. Auxiliary electrodes 7 are provided in the lower horizontal channel 61, the ascending channel 62 and the upper horizontal channel 63 to ensure the constant temperature of the fly ash melt during the outflow process. A plurality of silicon carbon rods 5 are provided in the upper horizontal channel 63, and the temperature in the channel discharge device 6 is ensured to be constant through thermocouple temperature measurement feedback. A liquid level meter 8 for controlling the feed amount of the feeder 4 is provided on the upper horizontal channel 63, and a thermometer 9 is also provided.

[0041] This embodiment also includes a control device, and the motor 331 of the drive device 33, the main melting AC electrode, the auxiliary electrode 7, the thermometer 9, the feeder 4, the liquid level meter 8 and the control device form a closed loop. The feeder 4 feeds materials into the main feed pipe 31 in a quantitative manner according to the detection data of the liquid level meter 8.

[0042] Example 2 Fly ash melting method

[0043] This embodiment is a method for melting fly ash. 100 kg of fly ash, 20 kg of quartz sand, and 46 kg of glass powder are weighed respectively. After stirring and mixing, raw materials for melting are formed. The raw materials are put into the material tank 12, and the material tank 12 is connected to the feeder 4. The feeder 4 supplies the corresponding raw materials to the feeding device 3 according to the detection data of the liquid level meter 8 on the material channel discharge device 6. The raw materials are evenly sprinkled into the inner cavity of the furnace body 1 by the rotating distribution pipe 32. The Joule heat generating device 2 of this embodiment is the main melting AC electrode, that is, current is loaded on the main melting AC electrode, so that the heat generated on the main melting AC electrode heats the fly ash to 1400°C to form a fly ash melt.

[0044] During discharge, the auxiliary electrode 7 in the material channel discharge device 6 is loaded with current, and the temperature in the material channel discharge device 6 is adjusted to 1200°C, so that the fly ash melt can flow out of the furnace body 1 smoothly. At the same time, the silicon carbon rod 5 at the material channel discharge device 6 is loaded with current, and it works together with the auxiliary electrode 7 to make the temperature control at the material channel discharge device 6 more accurate. Because the heavy metals in the fly ash melting process will accumulate at the bottom of the furnace body 1, the heavy metals will flow out with the discharger 10 arranged on the bottom cone of the furnace body 1. During discharge, the temperature control electrode 15 on the discharger 10 is loaded with current, and the temperature in the discharger 10 is adjusted to 1200°C. When the discharge process needs to be accelerated, the current on the temperature control electrode 15 is increased, the temperature in the discharger 10 increases, the viscosity of the fly ash melt decreases, and the fluidity increases; when the discharge process needs to be slowed down, the current on the temperature control electrode 15 is reduced, the temperature in the discharger 10 decreases, the viscosity of the fly ash melt increases, and the fluidity deteriorates. While discharging the material, the nitrogen generator 11 is turned on to pass nitrogen into the discharger 10 to prevent the discharger 10 from being oxidized by air.

[0045] During the melting process of fly ash, nitric acid water with low boiling point will be produced. The nitric acid water floats on the surface of the fly ash melt and flows out from the nitric acid water overflow port 13. In order to prevent the nitric acid water from solidifying during the overflow process, the silicon carbon rod 5 at the nitric acid water overflow port 13 is loaded with current to keep the temperature in the nitric acid water overflow port 13 at 1240°C.

[0046] Example 3-7 Fly ash melting method

[0047] The method for melting fly ash in this embodiment is basically the same as the method for melting fly ash in Example 2, and the only difference is that the conditions are controlled differently during the melting of fly ash, as shown in Table 1:

[0048] Table 1 Control of conditions during fly ash melting

[0049]

[0050] Examples 1-7 are only preferred embodiments of the present invention and are not other forms of limitation on the present invention. Any technician familiar with the profession cannot use the above technical content as inspiration to change or modify it into an equivalent embodiment with equivalent changes. However, as long as it does not deviate from the technical essence of the claims of the present invention, simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of protection of the claims of the present invention.

Claims

1. A fly ash melting device, comprising a furnace body with an inner cavity, a Joule heat generating device fixedly mounted on the furnace body, and a control device, characterized in that: The furnace body is also provided with a nitrate water overflow port, a feeding device, and a material channel discharge device for the fly ash melt to flow out; The feeding device includes a main feeding pipe extending from the inner cavity of the furnace body to the outside, a plurality of distribution pipes connected to the main feeding pipe, a driving device for driving the main feeding pipe to rotate, and a feeder with one end located above the main feeding pipe and the other end connected to the material tank, wherein the distribution pipe is arranged in the inner cavity of the furnace body; The material channel discharge device is provided with a liquid level meter, a thermometer and an auxiliary electrode for controlling the feeding amount of the feeder; The driving device, the Joule heat generating device, the auxiliary electrode, the thermometer, the feeder, the liquid level meter and the control device form a closed loop; The distribution pipes are arranged radially around the circumference of the main feed pipe, so that the end of the distribution pipe not connected to the main feed pipe is flush with the nitrate water overflow port; A silicon carbon rod is fixed inside the nitrate water overflow port to control the constant temperature.

2. The fly ash melting device according to claim 1, characterized in that: The bottom of the furnace body is a cone, and a bottom liquid discharge port is provided on the bottom cone, a molybdenum discharger is fixedly provided on the bottom liquid discharge port, a temperature control electrode is fixedly provided on the discharger, and a nitrogen generator for introducing nitrogen into the discharger is fixedly provided on the outside of the discharger.

3. The fly ash melting device according to claim 2, characterized in that: The interior of the furnace body is made of high temperature resistant material, and the exterior is made of heat insulation material.

4. The fly ash melting device according to any one of claims 1 to 3, characterized in that: The material channel discharge device is fixed with a silicon carbon rod for controlling a constant temperature.

5. The fly ash melting device according to claim 4, characterized in that: A funnel-shaped transition bin is fixedly arranged at one end of the main feed pipe connected to the feeder.

6. A method for melting fly ash using the fly ash melting device according to any one of claims 1 to 5, characterized in that: Follow these steps in order: Step 1: weigh 10 parts of fly ash and 1.5 to 10 parts of auxiliary materials containing silicon oxide, and mix them to form a raw material; Step 2: The raw materials are layered into the inner cavity of the furnace body through the feeding device, and then the fly ash is melted by electricity through the Joule heat generating device; Step 3: adjusting the control device to load current to the Joule heat generating device, so that the temperature of the fly ash melting in the inner cavity of the furnace body is controlled between 800 and 1500° C., and the temperature of the upper part of the inner cavity of the furnace body covering the raw materials is less than or equal to 200° C.; Step 4: When discharging the material, load the auxiliary electrode in the material channel discharge device with current to keep the temperature in the material channel discharge device at 800-1300°C.

7. The fly ash melting method according to claim 6, characterized in that: The auxiliary material is any one of quartz sand or glass powder, or a mixture of the two.

8. The fly ash melting method according to claim 6 or 7, characterized in that: In the step 4, when discharging the material, current is applied to the temperature control electrode on the discharger to keep the temperature inside the discharger at 800-1300° C., and the nitrogen generator is turned on at the same time.

9. The fly ash melting method according to claim 8, characterized in that: A silicon carbon rod is fixed in the nitre water overflow port, and current is applied to the silicon carbon rod at the nitre water overflow port to keep the temperature at the nitre water overflow port at 600-1400°C.

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