Waste salt melting furnace and recycling treatment system for high-fluorine-content waste salt

Abstract

The utility model discloses a waste salt melting furnace and a recycling treatment system for high-fluorine-content waste salt. The disclosed waste salt melting furnace comprises a furnace body, the top of the furnace body is provided with a material inlet and a smoke outlet, the material inlet and the smoke outlet are far away from each other in the radial direction, the bottom of the furnace body is provided with a molten salt discharge port, and the molten salt discharge port is far away from the material inlet in the upward direction; a heating device is arranged in the furnace body; the inner bottom surface of the furnace body is an inclined surface, and the fused salt discharge port is positioned at the lower end of the inclined bottom surface; a cooling structure is arranged at the bottom of the furnace body. The treatment system adopts the melting furnace provided by the utility model. The waste salt is directly fused in a molten pool-free mode and is in full contact with oxygen, organic matter is converted into carbon dioxide and water after being oxidized and incinerated, and the possibility of carbonization is reduced. The molten product salt can enter a product line for cyclic utilization after being cooled, ground and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of industrial waste salt treatment and relates to a resource disposal system for high-fluorine-containing waste salt. Background Art

[0002] The waste salt generated in the production process of a new energy industry is a mixed salt with potassium chloride and potassium fluoride as the main components, and contains a relatively high concentration of organic matter (>wt10%), and the fluorine content in the organic matter is as high as more than 8%. How to safely and harmlessly dispose of such waste salt has become a difficulty for enterprises.

[0003] Conventional rigid landfill disposal methods are high in fluoride waste salt, which has high landfill costs and still poses a great threat to soil and water safety. In recent years, resource recycling has become a way to achieve green and sustainable development of such waste salt.

[0004] One means of resource disposal is through oxidation incineration, that is, in the rotary kiln equipment, at a temperature below the melting point, the organic matter of the waste salt is rapidly oxidized and decomposed, the hydrocarbon elements are converted into gaseous carbon dioxide and water, and the fluorine element is converted into hydrogen fluoride gas, which is then absorbed and neutralized by alkali solution to meet the emission standards, and the salt after disposal is recycled for resource utilization. However, if the organic matter content is too high, some organic matter will not be fully oxidized, and even oxygen-free pyrolysis will occur. At this time, the organic matter will be carbonized and exist in the product in the form of fixed carbon, affecting the quality of the product. The accumulation of waste salt in the kiln will also cause uneven heating, and local waste salt is prone to overheating and melting, causing contamination of the rotary kiln equipment. The melted fluorine element corrodes the refractory material in the form of ions, seriously affecting the disposal efficiency of the equipment. At the same time, the fluorine element in the waste salt enters the wastewater system through acid-base neutralization, resulting in a waste of resources.

[0005] Another means of resource disposal is through the method of melting in a molten pool, that is, by establishing a molten pool with a certain liquid level, the waste salt is completely melted at a temperature higher than the melting point, thereby achieving the purpose of removing organic matter. However, for high-fluorine waste salt, in the molten state, the fluorine element in the form of ions is extremely corrosive to the refractory materials of the pool wall. In addition, due to insufficient oxygen contact below the liquid surface of the molten pool, some organic matter will carbonize and deposit at the bottom of the furnace. When the deposits affect the disposal effect, the furnace must be stopped for maintenance. Utility Model Content

[0006] In view of the defects or shortcomings of the prior art, the utility model provides a waste salt melting furnace. To this end, the waste salt melting furnace provided by the utility model includes a furnace body, wherein a material inlet and a smoke outlet are arranged at the top of the furnace body in the axial direction, and the material inlet and the smoke outlet are radially far away from each other, and a molten salt discharge port is arranged at the bottom of the furnace body, and the molten salt discharge port is radially far away from the material inlet;

[0007] A heating device is provided in the furnace body;

[0008] The inner bottom surface of the furnace body is an inclined surface, and the molten salt discharge port is located at the lower end of the inclined bottom surface; at the same time, a cooling structure is provided at the bottom of the furnace body.

[0009] An optional solution is that the radial dimension of the furnace body is larger than the axial dimension.

[0010] An optional solution is that the heating device is radially close to the material inlet.

[0011] An optional solution is that the heating device is radially away from the molten salt discharge port.

[0012] An optional solution is that at least one waste salt feeding port is provided at the bottom of the furnace body.

[0013] An optional solution is that the waste salt feeding port is located at the high end of the inclined bottom surface.

[0014] An optional solution is that the cooling structure includes a cooling interlayer arranged in the bottom furnace wall, and a plurality of partitions are arranged in the cooling interlayer. The plurality of partitions are distributed in the cooling interlayer and form an S-shaped curve cooling medium passage.

[0015] An optional solution is that the molten salt discharge port is flat in shape, with its short side along the axial direction of the furnace body.

[0016] The utility model also provides a resource disposal system for high-fluorine waste salt. The disposal system includes the above-mentioned waste salt melting furnace, and the flue gas outlet of the waste salt melting furnace is connected to a dust collector, a high-temperature water washing tower, a low-temperature water washing tower and an alkali washing tower in sequence. An optional solution is that a cooling device is connected between the flue gas outlet and the dust collector.

[0017] The utility model solves the existing problems in the prior art that organic matter is not sufficiently exposed to oxygen and is easily carbonized during the treatment of high-fluorine waste salt by rotary kiln equipment, is easily melted and contaminates the equipment due to uneven heating, and the molten fluorine element corrodes the refractory material in the form of ions. In particular, during the treatment process of the molten pool melting method, the fluorine element corrodes the refractory material in the form of ions, and due to insufficient oxygen contact below the molten pool liquid level, some organic matter will be carbonized and deposited on the bottom of the furnace. Both methods will cause the fluorine element to enter the wastewater system and be lost.

[0018] The melting furnace of the utility model has no melting pool, that is, there is no melting zone with a fixed height in the furnace. After the waste salt is melted, it flows out directly along the bottom surface without staying in the furnace. It is directly melted and fully contacted with oxygen. After the organic matter is oxidized and incinerated, it is converted into carbon dioxide and water, reducing the possibility of carbonization. The melted product salt can enter the product line for recycling after cooling, grinding and other processes.

[0019] The utility model has a melting pool-free method, which can reduce the contact area between the molten salt and the refractory material of the furnace body. At the same time, a cooling device is arranged at the bottom of the melting furnace, so that the molten salt forms a cooling protection layer on the surface of the refractory material, preventing the fluorine after melting from contacting the bottom refractory material in the form of ions, thereby greatly improving the service life of the refractory material.

[0020] The treatment system of the utility model recovers hydrogen fluoride gas in the flue gas through a combination of high-temperature water washing and low-temperature water washing to form hydrofluoric acid, thereby preventing the loss of fluorine element through the wastewater system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the front view of the salt melting furnace of the utility model.

[0022] Figure 2 for Figure 1 A view of the waste salt melting furnace shown.

[0023] Figure 3 for Figure 1 A BB view of the waste salt melting furnace is shown.

[0024] Figure 4 This is an example diagram of the cooling structure at the bottom of the furnace.

[0025] Figure 5 This is a flow chart for the treatment of high-fluorine-containing waste salt in the embodiments.

[0026] Figure 6 It is an internal flow chart of the disposal system of high-fluorine-containing waste salt in the embodiment.

[0027] Figure 7 This is a structural diagram of the disposal system for high-fluorine-containing waste salt in the embodiment. DETAILED DESCRIPTION

[0028] Unless otherwise specified, the scientific and technical terms used herein are understood according to the knowledge of ordinary technicians in the relevant fields.

[0029] The axial, radial, up, down, top, bottom and other direction or orientation terms described in this article are consistent with the relevant directions or orientations in the drawings of the specification. It should be noted that the drawings of the specification are intended to explain the utility model. The equivalent schemes obtained by rotation, replacement, etc. based on the contents disclosed in this article are all within the protection scope of the utility model.

[0030] Embodiment 1:

[0031] See also Figure 1As shown, the waste salt melting furnace of the utility model comprises a furnace body 101, and along the axial direction arranged in the up-down direction, a material inlet 103 and a smoke outlet 105 are arranged at the top of the furnace body, and a molten salt discharge port 106 is arranged at the bottom. In order to ensure that the material is fully heated and processed, in the radial direction, the material inlet and the smoke outlet are far away, and the molten salt discharge port is far away from the material inlet;

[0032] At the same time, a heating device 104 is provided in the furnace body; in order to ensure smooth discharge of the molten salt, the bottom surface of the furnace body is an inclined surface, and the molten salt discharge port is located at the lower end of the inclined surface; and in order to avoid overheating of the bottom of the furnace, a cooling device 108 is provided at the bottom of the furnace body.

[0033] During operation, under the action of the heating device, the temperature in the waste salt melting furnace 1 is 50-100°C higher than the melting flow temperature of the waste salt (i.e., 600-1100°C, depending on the composition of the salt), and the waste salt is fed into the furnace from the material inlet 103 and falls near the front wall of the melting furnace. Under the action of high temperature, the waste salt melts into a liquid state and flows along the slope of the entire bottom surface of the furnace body toward the molten salt discharge port 106; during the flow process, the molten salt is spread on the bottom surface of the melting furnace in a thin layer, and the organic matter in the waste salt and the heating device are fed into the furnace. The organic matter is fully contacted with oxygen, and is rapidly oxidized and burned to generate carbon dioxide and water, which are discharged from the flue gas outlet 105 together with the flue gas generated by the heating device, and the product salt is discharged from the molten salt discharge port 106 in a molten state; at the same time, under the cooling action of the cooling device 108, a cooling protective layer is formed on the surface of the refractory material on the bottom of the furnace body at the bottom of the melting furnace, that is, a layer of condensed salt will adhere to the refractory material on the bottom of the furnace body, so that the molten salt with better fluidity in the upper layer cannot directly contact the refractory material, thereby avoiding the corrosion of the refractory material by fluoride ions.

[0034] For the furnace structure of the utility model, in the preferred embodiment, the furnace body is a horizontal furnace body, and the inner radial dimension is larger than the axial dimension, which can fully increase the thermal range of the material in the furnace.

[0035] In a specific solution, the installation position of the heating device in the furnace body can be selected and optimized to improve the utilization rate of heat energy. For example, the heating device can be close to the material inlet in the radial direction and far away from the molten salt discharge port in the radial direction.

[0036] In the preferred solution, the bottom surface inclination angle α can be optimized according to the furnace processing capacity and material characteristics to ensure smooth discharge of the solution. For example, the optional inclination angle α can be between 40 and 60 degrees.

[0037] In a preferred embodiment, the molten salt discharge port 106 is flat in shape (ie, rectangular or elliptical, etc.), with the short side along the axial height direction of the furnace body, so that the molten product salt can be cooled quickly.

[0038] In some other schemes, in order to facilitate the removal of the waste salt material accumulated in the furnace and avoid local accumulation of materials, a waste salt poke hole 107 is provided at the bottom of the furnace body. The number of the poke holes is not limited to fully remove the waste salt material in the furnace. Figure 2 In the preferred embodiment, the waste material poking opening is arranged at the high end of the inclined bottom surface.

[0039] In a specific solution, the cooling device at the bottom of the furnace body can be cooled by external cooling or furnace wall cooling to cool the bottom of the furnace body to avoid heat accumulation and damage to the refractory material 102 at the bottom of the furnace body. Figure 3 As shown in FIG. 1 , the structure is that a cold zone interlayer 1083 is arranged inside the furnace wall, a cooling medium inlet and outlet (1081, 1082) is arranged outside the cooling interlayer, and a partition 1084 is arranged inside, so that an S-shaped cooling medium passage is formed in the interlayer, see FIG. Figure 4 shown.

[0040] In some other solutions, multiple feeding ports can be evenly arranged according to the needs of material distribution. According to the needs of heating, multiple heating devices can be arranged in the furnace.

[0041] In a specific solution, a discharge chute 109 is installed at the molten salt discharge port 106 .

[0042] Embodiment 2:

[0043] This embodiment is a waste salt resource disposal system, see Figure 5 As shown, the system includes a waste salt feeding system S01, a waste salt melting and collection system S02, an acid recovery system S03, and a flue gas treatment system S04.

[0044] See also Figure 7 As shown, the waste salt feeding system S01 comprises a conveyor 22 and a feeder 23; the waste salt is sequentially fed into a subsequent disposal system through the conveyor and the feeder;

[0045] The waste salt melting and collection system S02 comprises the waste salt melting furnace 1, product salt cooling device 2, product salt grinding device 3, product salt packaging device 4, cooling fan 5, and cyclone dust collector 6 described in Example 1; in the waste salt melting furnace 1, the waste salt is heated to 600-1100° C., organic matter is burned and disposed of cleanly, and carbon dioxide and water are generated, which enter the cyclone dust collector together with the flue gas generated by the heating device; the product salt is discharged from the melting furnace in a molten state, cooled to 50-80° C. by the cooling device 2, and then ground into a uniform powder by the grinding device 3, and then packaged by the packaging device 4;

[0046] A cooling fan 5 is arranged between the waste salt melting furnace 1 and the cyclone dust collector 6;

[0047] Through the cooling effect of the cooling fan, some of the gaseous salt particles entrained in the flue gas are cooled and turned into solid state. When the flue gas passes through the cyclone dust collector, the solid salt particles and the flue gas are separated, and the solid salt particles are collected and packed into the packaging device 4, and the flue gas enters the subsequent process.

[0048] The acid recovery system S03 comprises a high-temperature water washing tower 7, a water tank at the bottom of the tower 8, a heat exchanger 9, a high-temperature water washing tower spray gun 10, a low-temperature water washing tower 11, a low-temperature water washing tower demister 12, a low-temperature water washing tower spray gun 13, a low-temperature water washing tower circulating water pump 14, and a low-temperature water washing tower to high-temperature water washing tower water supply pump 15; the flue gas from the cyclone dust collector passes through the high-temperature water washing tower 7 and is washed by the cooling water sprayed by the high-temperature water washing tower spray gun 10, reducing the flue gas temperature to 60-90°C; the ungasified cooling water in the flue gas enters the water tank at the bottom of the tower 8, and the cooling water in the water tank at the bottom of the tower 8 is washed by the cooling water sprayed by the high-temperature water washing tower spray gun 10, and the flue gas temperature is reduced to 60-90°C; the ungasified cooling water in the flue gas enters the water tank at the bottom of the tower 8, and the cooling water in the water tank at the bottom of the tower 8 is washed by the cooling water sprayed by the high-temperature water washing tower spray gun 10, and the cooling water in the high-temperature water washing ... 10, and the cooling water in the high-temperature water washing tower 10 is washed by the cooling water sprayed by the high-temperature water washing tower 10, and the cooling water in After cooling through the heat exchanger 9, the cooling water is circulated and sprayed into the high-temperature water scrubber 7 to cool the flue gas; the flue gas cooled by the high-temperature water scrubber 7 enters the low-temperature water scrubber 11, and the hydrogen fluoride gas in the flue gas is condensed under the action of the cooling water sprayed by the low-temperature water scrubber spray gun 13 to form a hydrofluoric acid aqueous solution, which enters the bottom of the low-temperature water scrubber; at the same time, the hydrofluoric acid aqueous solution at the bottom of the low-temperature water scrubber is circulated and sprayed into the tower through the low-temperature water scrubber spray gun 13 under the action of the low-temperature water scrubber circulating water pump 14, and the concentration of hydrofluoric acid in the hydrofluoric acid aqueous solution is continuously increased through continuous circulation. After the concentration reaches the requirement, the hydrofluoric acid aqueous solution is discharged and collected; the hydrofluoric acid droplets entrained in the flue gas are removed by the low-temperature water scrubber demister 12 to improve the recovery rate of hydrogen fluoride gas in the flue gas.

[0049] The flue gas treatment system S04 comprises an alkali washing tower 16, an alkali washing tower demister 17, an alkali washing tower spray gun 18, an alkali washing tower circulating water pump 19, an induced draft fan 20, and a chimney 21; the flue gas passing through the low-temperature water washing tower enters the alkali washing tower 16, and the alkali washing tower spray gun 18 continuously circulates a diluted alkali solution with a concentration of 5% to 20% by weight into the tower to remove the residual hydrogen fluoride gas in the flue gas and achieve standard emission of the flue gas; after the flue gas is defogged by the alkali washing tower demister 17, it is discharged from the alkali washing tower outlet, the induced draft fan 20, and the chimney 21 in sequence.

[0050] The working process of this system is as follows:

[0051] 1) Waste salt is fed into the waste salt melting furnace 1 through the conveyor 22 and the feeder 23. Under the condition of 600-1100°C, the waste salt is melted in the melting furnace to produce molten product salt and high-temperature flue gas;

[0052] 2) The molten product salt is recovered through the product salt cooling device 2, the product salt grinding device 3, and the product salt packaging device 4;

[0053] 3) After the high-temperature flue gas is cooled by the wind of the cooling fan 4, it enters the cyclone dust collector 6. At this time, the salt particles entrained in the flue gas are separated from the flue gas and enter the product salt packaging device 4;

[0054] 4) The flue gas at the outlet of the cyclone dust collector 4 enters the high-temperature water washing tower 7. Under the action of cooling water, the flue gas temperature is reduced to 60-90°C. The ungasified cooling water in the flue gas enters the water tank 8 at the bottom of the tower;

[0055] 5) The cooling water in the water tank 8 at the bottom of the tower is cooled by the heat exchanger 9 and then circulated and sprayed into the high-temperature water washing tower 7 to cool the flue gas;

[0056] 6) The flue gas cooled by the high-temperature water scrubber 7 enters the low-temperature water scrubber 11. Under the action of cooling water, the hydrogen fluoride gas in the flue gas is condensed to form a hydrofluoric acid aqueous solution, which enters the bottom of the low-temperature water scrubber. At the same time, the hydrofluoric acid aqueous solution at the bottom of the low-temperature water scrubber is circulated and sprayed into the tower through the low-temperature water scrubber spray gun 13. Through continuous circulation, the concentration of hydrofluoric acid in the hydrofluoric acid aqueous solution is continuously increased. After the concentration reaches the requirement, the hydrofluoric acid aqueous solution is discharged and collected;

[0057] 7) removing hydrofluoric acid droplets entrained in the flue gas through the low-temperature water scrubber demister 12, thereby improving the recovery rate of hydrogen fluoride gas in the flue gas;

[0058] 8) The flue gas passing through the low-temperature water washing tower enters the alkali washing tower 16, and the alkali washing tower spray gun 18 continuously circulates the 5-20% wt dilute alkali solution into the tower to remove the residual hydrogen fluoride gas in the flue gas and achieve the standard emission of the flue gas;

[0059] 9) The flue gas is led out from the outlet of the alkali washing tower and discharged through the induced draft fan 20 and the chimney 21 in sequence.

[0060] Embodiment 3:

[0061] This embodiment uses the waste salt disposal system of Example 2 to treat 50t / d of high-fluorine waste salt. The components of the treated waste salt are shown in Tables 1 and 2 below:

[0062] Table 1

[0063]

[0064]

[0065] Table 2 Specific components of organic matter

[0066] Element Content (wt%) C 46.4 H 3.8 O 33.5 Cl 6.2 F 10.1

[0067] It can be seen that this waste salt is a mixed salt with KCL / KF as the main components, with a high organic matter content of 15% (wt), and the F element in the organic matter accounts for 10.1% (wt), which is a high-fluorine waste salt.

[0068] use Figure 1 The waste salt melting furnace shown and Figure 5-6 The specific parameters of the waste salt melting furnace used in the disposal system shown are: the overall dimensions are 18m (length) x 3m (width) x 3m (height), the refractory material thickness is 500mm, the bottom surface of the furnace is inclined at an angle of 50°; the furnace top adopts a double feeding port, such as Figure 5 The heating device uses natural gas as fuel, the furnace temperature is 800℃; the oxygen content at the outlet of the melting furnace is controlled to be 8%. The furnace bottom cooling device uses Figure 4 The water-cooled wall structure shown, the tube diameter Material: 20G.

[0069] After the waste salt is disposed, it is ground into 500 mesh powder and packaged. After testing, it meets the production line's requirements for potassium salt composition and enters the factory production line for recycling. The product salt composition is shown in Table 3 below:

[0070] Table 3

[0071] KCl / wt% KF / wt% Total organic carbon mg / kg Numeric 70.6 29.3 90

[0072] The flue gas passes through a high-temperature water scrubber and a low-temperature water scrubber to recover the acid solution. The concentration of hydrofluoric acid in the acid solution is measured to be 17.5% (wt), and the concentration of hydrochloric acid is (10.2%), which can also be reused as a product.

Claims

1. A waste salt melting furnace, comprising a furnace body, characterized in that: Axially, a material inlet and a smoke outlet are provided at the top of the furnace body, and the material inlet and the smoke outlet are radially far away from each other, and a molten salt discharge port is provided at the bottom of the furnace body, and the molten salt discharge port is radially far away from the material inlet; A heating device is provided in the furnace body; The inner bottom surface of the furnace body is an inclined surface, and the molten salt discharge port is located at the lower end of the inclined bottom surface; at the same time, a cooling structure is provided at the bottom of the furnace body.

2. The waste salt melting furnace according to claim 1, characterized in that: The radial dimension of the furnace body is greater than the axial dimension.

3. The waste salt melting furnace according to claim 1, characterized in that: The heating device is radially close to the material inlet.

4. The waste salt melting furnace according to claim 1, characterized in that: The heating device is radially away from the molten salt discharge port.

5. The waste salt melting furnace according to claim 1, characterized in that: The bottom of the furnace body is provided with at least one waste salt feeding opening.

6. The waste salt melting furnace according to claim 5, characterized in that: The waste salt feeding port is located at the high end of the inclined bottom surface.

7. The waste salt melting furnace according to claim 1, characterized in that: The cooling structure comprises a cooling interlayer arranged in the bottom furnace wall, wherein a plurality of partitions are arranged in the cooling interlayer, and the plurality of partitions are distributed in the cooling interlayer and form an S-shaped curve cooling medium passage.

8. The waste salt melting furnace according to claim 1, characterized in that: The molten salt discharge port is flat in shape, and its short side is along the axial direction of the furnace body.

9. A resource disposal system for high-fluorine waste salt, characterized in that: It comprises the waste salt melting furnace as claimed in claim 1, wherein the flue gas outlet of the waste salt melting furnace is sequentially connected with a dust collector, a high-temperature water washing tower, a low-temperature water washing tower and an alkali washing tower.

10. The resource disposal system for high-fluorine waste salt according to claim 9, characterized in that: A cooling device is connected between the smoke outlet and the dust collector.

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