A method and associated apparatus for treating waste salts containing inorganic ash and organic matter

Abstract

The application discloses a treatment method and related treatment device for waste salt containing inorganic ash and organic matter. The disclosed method comprises: under the condition that the temperature is greater than or equal to 1300 DEG C and 50-100 DEG C higher than the melting flow temperature of inorganic ash in the waste salt, the waste salt containing inorganic ash and organic matter is subjected to melting gasification treatment, so that the organic matter in the waste salt is decomposed to generate high-temperature flue gas, the salt is gasified into the high-temperature flue gas, and the inorganic ash is melted to generate molten slag; the high-temperature flue gas is cooled and settled to recover the salt therein, and the molten slag is cooled to be converted into a glass body. The disclosed device comprises a melting furnace and a cooling and settling device; the waste salt is heated and melted and gasified in the melting furnace, and the generated high-temperature flue gas is cooled and collected in the cooling and settling device. Efficient oxidation and decomposition of the organic matter are realized, the inorganic matter such as ash and salt are automatically separated, and complete resource disposal of the waste salt is realized.

Description

Technical Field

[0001] This invention belongs to the field of industrial waste salt treatment technology, and relates to a treatment method and related treatment device for waste salt containing inorganic ash and organic matter. Background Technology

[0002] Industrial waste salt contains a certain amount of organic matter, heavy metals, and other inorganic ash, which can easily pollute soil and water bodies, necessitating harmless and resource-based treatment. Current main methods include landfilling, advanced oxidation processes, pyrolysis, incineration, and melting.

[0003] Landfilling is currently the most common disposal method, but it requires a large amount of land and lacks sustainable development prospects. Advanced oxidation processes are mainly for waste salts with simple compositions and low organic content, but their adaptability to different materials is poor. Pyrolysis and incineration are prone to localized melting of waste salts due to uneven furnace temperatures, leading to equipment fouling and blockage. Furthermore, for waste salts with high organic content, it is difficult to meet the total organic carbon standards of the pyrolysis products. For waste salts with high organic content and high ash content, melting treatment causes insufficient oxygen contact, leading to carbonization of organic matter and easy ash deposition at the furnace bottom, requiring periodic shutdowns for manual cleaning, affecting the long-term operation of the system. Moreover, pyrolysis, incineration, and melting methods all require subsequent waste salt refining processes to filter out ash and other impurities.

[0004] It is evident that melting is currently the most feasible method for treating waste salts with high ash and organic content. However, melting also has its own drawbacks.

[0005] Therefore, this invention addresses the problem of the lack of suitable technologies for the disposal of waste salt with high ash and high organic matter content by proposing a gasification recovery method and treatment device for waste salt. Summary of the Invention

[0006] In view of the defects or deficiencies of the prior art, the present invention provides a method for treating waste salt containing inorganic ash and organic matter.

[0007] Therefore, the waste salt treatment method containing inorganic ash and organic matter provided by the present invention includes: melting and gasifying the waste salt containing inorganic ash and organic matter at a temperature ≥1300℃, which is 50-100℃ higher than the melting flow temperature of inorganic ash in the waste salt, so that the organic matter in the waste salt decomposes to generate high-temperature flue gas, the salt gasifies and enters the high-temperature flue gas, and the inorganic ash melts to generate slag; the high-temperature flue gas is cooled and settled to recover the salt therein, and the slag is cooled and converted into a glassy substance. Optionally, the high-temperature flue gas is cooled to 100-150℃ lower than the melting flow temperature of the salt to recover the salt therein.

[0008] The present invention also provides a waste salt treatment device containing inorganic ash and organic matter. The provided device includes a melting furnace for melting and gasifying waste salt to generate high-temperature flue gas and molten slag; the melting furnace is provided with a high-temperature flue gas outlet at the top and a molten slag discharge outlet at the bottom;

[0009] The waste salt gasification and recovery device also includes a high-temperature flue gas cooling and settling device. The high-temperature flue gas cooling and settling device includes a tower body. The top of the tower body is provided with a high-temperature flue gas inlet and the bottom is provided with a solid discharge outlet. The tower body is provided with a cooling zone and a settling zone, and the cooling zone is located above the settling zone.

[0010] The cooling zone is equipped with a cooling device;

[0011] Multiple baffles are provided along the top to bottom of the tower body within the settlement zone. Each baffle has one end installed on the inner wall of the tower body and the other end is a free end, which is inclined towards the bottom of the tower body.

[0012] The settling zone is equipped with a flue gas outlet, which is located above the solid waste emission outlet.

[0013] The high-temperature flue gas inlet of the high-temperature flue gas cooling and settling device is connected to the high-temperature flue gas outlet.

[0014] Alternatively, the cooling device may be a cooling medium nozzle or a cooling medium spraying device.

[0015] An alternative solution is to include a cooling structure within the partition.

[0016] Alternatively, the other end of the partition extends to or near the central axis of the tower body, and the multiple partitions are staggered inside the tower.

[0017] An alternative approach is to have the inner diameter of the cooling zone smaller than the inner diameter of the settling zone.

[0018] An alternative is that the solid discharge port has an inverted cone shape.

[0019] An alternative is that the melting furnace includes a horizontal furnace body, which includes a furnace head, a furnace body, and a furnace tail arranged sequentially along the axial direction. The furnace head and furnace tail are fixedly arranged, and the two ends of the furnace body are respectively sealed and rotatably connected to the furnace head and furnace tail.

[0020] The furnace head has a feed inlet on its furnace wall and a first heating device installed on its furnace wall. The top of the furnace tail has a high-temperature flue gas outlet and the bottom has a slag discharge outlet. The furnace tail has a second heating device installed on its furnace wall.

[0021] A further alternative is that the cooling and settling device is located at the tail end of the melting furnace, and the axial direction of the melting furnace is perpendicular to the vertical direction of the cooling and settling device. The high-temperature flue gas outlet and the high-temperature flue gas inlet of the cooling and settling device are connected through a flue.

[0022] Alternatively, the flue is inclined upwards, with the high-temperature flue gas outlet located at the lower end of the flue and the high-temperature flue gas inlet located at the upper end of the flue.

[0023] A further embodiment involves connecting a heat exchanger and a dust collector sequentially to the flue gas outlet. The flue gas discharged from the cooling and settling device undergoes waste heat recovery and salt recovery via the subsequent heat exchanger, while the dust collector collects the salt entrained in the flue gas once more. Furthermore, the heat exchanger is connected to the first heating device, and the combustion-supporting gas required by the first heating device exchanges heat through the heat exchanger and the flue gas discharged from the cooling and settling device.

[0024] This invention utilizes waste salt gasification and high-temperature flue gas cooling and settling to remove organic matter from the waste salt at high temperatures. The gasified salt is then recovered in solid form through cooling and settling. Ash and other inorganic substances are melted at high temperatures to form a harmless vitreous substance. The device of this invention achieves efficient oxidative decomposition of organic matter in waste salt, automatic separation of ash and other inorganic substances from the salt, and complete resource recovery of waste salt. For waste salt with a single component, the recovered solid salt does not require refining processes such as dissolution, filtration, evaporation, or crystallization, fully meeting the required specifications and simplifying the treatment process.

[0025] This invention solves the problems existing in the prior art where organic matter is easily carbonized due to insufficient oxygen and inorganic matter such as ash is easily deposited at the bottom of the furnace during the melting and disposal of such waste salt, which affects the long-term continuous operation of the system. Attached Figure Description

[0026] Figure 1 This is a structural diagram of a waste salt treatment device containing inorganic ash and organic matter in an embodiment of the present invention.

[0027] Figure 2 This is a flow chart of the waste salt treatment process containing inorganic ash and organic matter in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the material inside the molten pool as described in an embodiment of the present invention. Detailed Implementation

[0029] Unless otherwise specified, the scientific and technical terms used in this article are intended for understanding by those skilled in the art.

[0030] The waste salt containing inorganic ash and organic matter mentioned in this article refers to industrial waste salt containing inorganic ash, such as organic matter and heavy metals. Examples include waste salt from industries such as pesticides and chemicals.

[0031] The processing method of the present invention mainly involves melting and gasifying waste salt containing inorganic ash and organic matter at a temperature ≥1300℃, which is 50-100℃ higher than the melting flow temperature of inorganic ash in the waste salt. This process causes the organic matter in the waste salt to decompose and generate high-temperature flue gas, the salt in the waste salt to gasify and enter the high-temperature flue gas, and the inorganic ash to melt and generate slag. The high-temperature flue gas is cooled to recover the salt, and the slag is cooled to transform into a glassy substance.

[0032] In specific solutions, if the ash content in the waste salt to be treated does not meet the vitrification requirements, the waste salt can be mixed with a co-solvent. The quantitative indicators corresponding to the vitrification requirements are based on the national standard GB / T41015-2021 "Technical Requirements for Vitrification Treatment Products of Solid Waste", which stipulates that the glass content after ash melting must reach more than 85%.

[0033] Example 1:

[0034] The apparatus for implementing the process of the present invention includes a melting furnace 1 and a high-temperature flue gas cooling and settling device 3. The melting furnace can be an existing industrial waste salt treatment melting furnace. The waste salt is heated and degraded in the melting furnace. The organic matter in the waste salt decomposes to generate high-temperature flue gas, the salt in the waste salt is gasified and enters the high-temperature flue gas, and the inorganic ash is melted to generate slag.

[0035] High-temperature cooling and settling devices are used to cool and reduce dust in high-temperature flue gas and collect salts from it. For a specific example of a high-temperature cooling and settling device, see [link to example]. Figure 1 As shown, the tower includes a tower body 13, which has a high-temperature flue gas inlet at the top and a solid discharge outlet 17 at the bottom. The tower body has a cooling zone B1 and a settling zone B2, with the cooling zone located above the settling zone. The cooling zone is equipped with a cooling device 15 (such as a cooling medium nozzle or a cooling medium spray pipe, etc., and the cooling medium can be water-cooled or air-cooled). The settling zone has multiple baffles 16 arranged from the top to the bottom of the tower body. Each baffle has one end installed on the inner wall of the tower body and the other end is a free end, which is inclined towards the bottom of the tower body.

[0036] The settling zone is provided with a flue gas outlet 18, which is located above the solid emission outlet 17.

[0037] After industrial waste salt is fed into the melting furnace, it is melted and gasified at a temperature ≥1300℃, which is 50-100℃ higher than the melting flow temperature of inorganic ash in the waste salt. This process causes the organic matter in the waste salt to decompose and generate high-temperature flue gas, the salt in the waste salt to gasify and enter the high-temperature flue gas, and the inorganic ash to melt and generate slag.

[0038] Afterwards, the slag is cooled by water and transformed into a glassy substance. The high-temperature flue gas is sent into the cooling and settling device tower through the high-temperature flue gas inlet. First, the flue gas is cooled by the cooling device in the cooling zone, so that the flue gas temperature is 100-150°C lower than the melting flow temperature of the salt, causing the salt to turn into solid particles. The flue gas carrying the solid particles descends to the settling zone (where the flue gas velocity is reduced to below 2 m / s). Under the action of the baffle, the flue gas flow direction is changed, and a reflux zone is formed near the baffle, which promotes the natural settling of the waste salt. Thus, the salt particles are separated from the flue gas under the action of gravity and inertial force and collected through the solid discharge port at the bottom. The remaining flue gas is discharged through the flue gas outlet.

[0039] In the preferred scheme, the distribution of multiple baffles in the settlement zone is optimized. One preferred example is as follows: Figure 1 As shown, one end of each baffle is installed inside the tower body, and the other end extends to or near the central axis inside the tower body. Multiple baffles are staggered inside the tower body, so that the flue gas can be changed in direction during the descent process.

[0040] In specific designs, the baffles can be made of high-temperature resistant non-metallic materials. In some preferred designs, each baffle can be a metal cooling wall structure with internal water or air cooling, such as an internal cooling medium interlayer or channel, so that the surface of the baffle is in a low-temperature environment, further cooling the flue gas and fully recovering the salts therein.

[0041] Considering that the cooling zone should generate a strong heat transfer and mass transfer effect in a small area in a short time, and the settling zone should reduce the flow velocity by using a large inner diameter to separate solids from flue gas, in some schemes the inner diameter of the cooling zone is smaller than that of the settling zone.

[0042] In some other designs, the solid discharge port at the bottom of the tower is an inverted cone shape to accelerate the recovery of settled particles.

[0043] In the specific design, the structure of the cooling and settling device tower wall can be composed of a tower wall shell 13 and a refractory lining 14.

[0044] Example 2:

[0045] In a further design, the structure of the melting furnace (or waste salt gasification furnace) can be optimized to ensure sufficient contact between the waste salt and oxygen during the melting process, thereby ensuring the complete degradation of organic matter. A preferred melting furnace structure is as follows: Figure 1As shown, the melting furnace is a horizontal structure, which includes a furnace head A1, a furnace body A2, and a furnace tail A3 arranged sequentially along the furnace axis. The furnace head and furnace tail are fixedly arranged, and the two ends of the furnace body are rotatably and sealed to the furnace head and furnace tail, respectively. The furnace head has a feed inlet 6 on its furnace wall, and a first heating device 7 (such as a pure oxygen or oxygen-enriched burner) is installed on the furnace wall of the furnace head. The furnace tail has a high-temperature flue gas outlet 12 at the top and a slag discharge outlet 9 at the bottom. A second heating device 8 (such as a pure oxygen or oxygen-enriched burner) is installed on the furnace wall of the furnace tail.

[0046] After the waste salt enters the melting furnace, it rotates under the action of the intermediate furnace body rotation drive device 10. During the rotation, the waste salt comes into full contact with the oxygen in the air, so that the organic matter in the waste salt is completely oxidized and burned off. During the process, the first and second heating devices provide the required heat to the furnace, so that the waste salt is degraded, melted and gasified. The material moves from the furnace head A1 area to the furnace tail A3 area under the action of rotation. The molten slag is discharged through the molten slag discharge port 9 and becomes a glassy substance after water cooling. The high-temperature flue gas enters the cooling and settling device (or cooling and settling chamber) through the flue gas discharge port at the top of the furnace tail.

[0047] In the specific design, each section of the furnace wall of the melting furnace can be composed of a shell 4 and a refractory lining 5.

[0048] In a more preferred embodiment, it is possible to Figure 1 The melting furnace shown is positioned relative to the cooling and settling device of the present invention, as follows: Figure 1 As shown, the cooling and settling device is located at the tail end of the melting furnace, and the axis of the melting furnace is perpendicular to the vertical direction of the cooling and settling device. The high-temperature flue gas outlet and the high-temperature flue gas inlet of the cooling and settling device are connected through flue 2. In a specific embodiment, the flue wall can be composed of a flue shell 11 and a flue refractory lining 12. More preferably, the flue is inclined upward (e.g., the inclination angle is greater than or equal to 60°), forming a "V"-shaped structure, with the high-temperature flue gas outlet located at the lower end of the flue and the high-temperature flue gas inlet located at the upper end of the flue. This allows some of the vaporized salt to cool and turn into liquid after colliding with the inner wall of the connecting flue, returning to the gasification furnace along the inclined flue. During the descent, this portion of salt is re-vaporized.

[0049] Example 3:

[0050] As attached Figure 2 As shown, in a further embodiment, the cooling and settling device is sequentially connected to a heat exchanger, a dust collector, an alkaline scrubbing tower, and an emission system. The flue gas discharged from the cooling and settling device undergoes waste heat recovery and salt recovery through the subsequent heat exchanger, the dust collector collects the salt entrained in the flue gas again, and the alkaline scrubbing tower removes the acidic components from the flue gas before it is discharged through the emission system to meet emission standards.

[0051] In a further preferred embodiment, the combustion-supporting gas used in the first heating device exchanges heat with the flue gas discharged through a heat exchanger and a cooling settling device, thereby increasing the temperature of the combustion-supporting gas, saving some natural gas and other fuels, and reducing the energy consumption of the system; at the same time, it can further recover the waste salt in the flue gas.

[0052] Example 4:

[0053] This embodiment utilizes conventional waste salt molten pool furnaces for conventional melting treatment and... Figure 1 The gasification and melting device of the present invention is shown to process a certain waste salt as shown in Table 1.

[0054] Table 1

[0055] project unit content Sodium chloride ％ 92.1 Moisture ％ 5.74 calcium ions ％ 0.01 magnesium ions ％ 0.01 sulfate ions ％ 0.06 silicon ％ 2.08 Total organic carbon mg / kg 16500

[0056] When using a conventional waste salt molten pool furnace for conventional melting and disposal, it is necessary to periodically shut down the furnace to clean the sediment at the bottom of the furnace. Figure 3 As shown, the material in the molten pool will form layers. The upper layer is a single-component salt with NaCl as the main component, and the lower layer is a black carbide containing fixed carbon, inorganic ash (silicon, magnesium, calcium, etc.) and some salt.

[0057] pass Figure 1 The device shown (waste salt gasification furnace with dimensions φ2*8m, one furnace head and one furnace tail each equipped with natural gas and 50% oxygen-enriched air combustion, the oxygen-enriched air is heated to 450℃ after being heated by a heat exchanger) is used for treatment, the temperature inside the horizontal melting furnace is about 1400℃; the cooling and settling device cools down by spraying water, and the flue gas temperature is 700℃ after being cooled in the cooling zone.

[0058] After the solid salt at the bottom of the cooling sedimentation device was discharged, its composition and total organic carbon were tested, and the results are shown in Table 2 below.

[0059] Table 2

[0060] NaCl / % Total organic carbon (mg / kg) numerical values 99.4 20

[0061] After water quenching, the ash and other inorganic slag products formed a glassy slag. The glass content and acid dissolution rate were tested, and the results are shown in Table 3 below.

[0062] Table 3

[0063] Vitreous content / % Acid loss rate / % numerical values 95 1.0

[0064] It can be seen that the total organic carbon content in the solid salt meets the requirements for raw materials in the chlor-alkali industry, and the glass content and acid loss rate in the vitrified slag also meet the national standard "Technical Requirements for Vitrification Products of Solid Waste". This achieves complete resource utilization of waste salt.

Claims

1. A method for treating waste salt containing inorganic ash and organic matter, characterized by, The method comprises: under the condition that the temperature is greater than or equal to 1300 DEG C and 50-100 DEG C higher than the melting flow temperature of inorganic ash in waste salt, the waste salt containing inorganic ash and organic matter is subjected to a melting gasification treatment, so that the organic matter in the waste salt is decomposed to generate high-temperature flue gas, the salt is gasified into the high-temperature flue gas, and the inorganic ash is melted to generate molten slag; the high-temperature flue gas is cooled and settled to recover the salt therein, and the molten slag is cooled to be converted into a glass body; and the high-temperature flue gas is cooled to 100-150 DEG C lower than the melting flow temperature of the salt to recover the salt therein. The melting furnace is used for the melting gasification treatment of the waste salt, and the melting furnace comprises a horizontal furnace body, the furnace body comprises a furnace head, a furnace body and a furnace tail arranged in sequence along the axial direction, the furnace head and the furnace tail are fixedly arranged, and the two ends of the furnace body in the axial direction are respectively and sealingly rotatably connected with the furnace head and the furnace tail. A feeding port is arranged on the furnace wall of the furnace head, a first heating device is arranged on the furnace wall of the furnace head, a high-temperature flue gas outlet is arranged at the top of the furnace tail, a molten slag discharge port is arranged at the bottom of the furnace tail, and a second heating device is arranged on the furnace wall of the furnace tail. The intermediate section of the furnace body rotates under the action of a rotating driving device, so that the waste salt and oxygen in the air are fully contacted in the rotating process, and the organic matter in the waste salt is completely oxidized and incinerated. The high-temperature flue gas is treated by using a high-temperature flue gas cooling and settling device, the high-temperature flue gas cooling and settling device comprises a tower body, a high-temperature flue gas inlet is arranged at the top of the tower body, and a solid material discharge port is arranged at the bottom of the tower body, a cooling zone and a settling zone are arranged in the tower body, and the cooling zone is located above the settling zone. The cooling zone is provided with a cooling device. A plurality of partitions are arranged in the settling zone from the top to the bottom of the tower body, one end of each partition is arranged on the inner wall of the tower body, the other end is a free end, and the other end is inclined to the bottom of the tower body. The settling zone is provided with a flue gas outlet, and the flue gas outlet is located above the solid material discharge port. The high-temperature flue gas inlet of the high-temperature flue gas cooling and settling device is connected with the high-temperature flue gas outlet.

2. The inorganic ash and organic-containing waste salt treatment method according to claim 1, characterized by, The cooling device is a cooling medium nozzle or a cooling medium spraying device.

3. The inorganic ash and organic-containing waste salt treatment method according to claim 1, characterized by, The partition is provided with a cooling structure.

4. The inorganic ash and organic-containing waste salt treatment method according to claim 1, characterized by, The other end of the partition extends to the central axis or the vicinity of the central axis in the tower body, and the plurality of partitions are staggered in the tower body.

5. The inorganic-ash-and-organic-containing waste salt treatment method according to claim 1, characterized by, The inner diameter of the cooling zone is smaller than the inner diameter of the settling zone.

6. The inorganic-ash-and-organic-containing waste salt treatment method according to claim 1, characterized by, The solid material discharge port is a reverse conical structure.

7. The inorganic-ash-and-organic-containing waste salt treatment method according to claim 1, characterized by, The high-temperature flue gas cooling and settling device is located at the tail end of the melting furnace, the axial direction of the melting furnace is perpendicular to the up-down direction of the high-temperature flue gas cooling and settling device, and the high-temperature flue gas outlet is in communication with the high-temperature flue gas inlet of the high-temperature flue gas cooling and settling device through a flue.

8. The method for treating waste salt containing inorganic ash and organic matter according to claim 7, characterized by, The flue is inclined upward, the high-temperature flue gas outlet is located at the low end of the flue, and the high-temperature flue gas inlet is located at the high end of the flue.

9. The inorganic-ash-and-organic-containing waste salt treatment method according to claim 1, characterized by, The flue gas outlet is sequentially connected with a heat exchanger and a dust collector; the flue gas discharged from the high-temperature flue gas cooling and settling device is subjected to waste heat recovery and salt recovery by the subsequent heat exchanger, and the dust collector collects the flue gas and salt again.

10. The method for treating waste salt containing inorganic ash and organic matter according to claim 9, characterized by, The heat exchanger is connected with the first heating device, and the combustion-supporting gas required by the first heating device is exchanged with the flue gas discharged from the high-temperature flue gas cooling and settling device.

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