A device for removing hardness and silicon from coal chemical recycling water

Abstract

The utility model relates to the technical field of coal chemical industry reuse water pretreatment, specifically relates to a kind of coal chemical industry reuse water silicon removal and hardness removal device, the utility model includes first to fifth reaction pool and sedimentation tank being set in series along wastewater treatment flow direction, each reaction pool is communicated by overflow hole, the third reaction pool, fourth reaction pool, fifth reaction pool top is provided with pool wall descaling device, and overflow hole is provided with overflow hole descaling device;The utility model realizes the all-round removal of pool wall, overflow hole scaling by pool wall descaling device and overflow hole descaling device, solves the problem of serious scaling of traditional device, guarantees the long-period smooth operation of reuse water pretreatment device, reduces the cleaning frequency of shutdown, in addition, the utility model sets up intelligent control system linkage online monitoring data, accurately adjusts reagent dosage, avoids the waste of reagent, and intelligent control system is connected with pool wall descaling device and overflow hole descaling device, improves the automation and intelligentization of descaling.

Description

Technical Field

[0001] This utility model relates to the field of coal chemical recycled water pretreatment technology, specifically to a device for removing hardness and silicon from coal chemical recycled water. Background Technology

[0002] In recent years, with the adjustment of the global energy structure and the upgrading of the chemical industry, the coal chemical industry has ushered in a period of rapid development and has become an important pillar industry for ensuring national energy security and promoting the diversification of chemical raw materials. my country has abundant coal resources and continuous breakthroughs in coal chemical technology, gradually extending from traditional coal coking and coal gasification to modern coal-to-olefins, coal-to-ethylene glycol, coal-to-natural gas and other high-end chemical products. The industry scale continues to expand and occupies an increasingly important position in the national economic system.

[0003] However, the coal chemical industry is a typical high-water-consuming and high-polluting industry, generating a large amount of wastewater during production. This wastewater comes from a wide range of sources and has a complex composition. It mainly includes wastewater from circulating water systems, concentrated water generated during desalination, treated wastewater discharged from wastewater treatment systems, and periodic wastewater discharged from boiler units. This wastewater not only has extremely high salt content but also generally exhibits significant characteristics of high hardness and high silicon content. The hardness primarily originates from calcium and magnesium ions, while the silicon mainly exists in the form of dissolved silica or silicates.

[0004] In coal chemical membrane systems for treating recycled water, membrane separation technology is widely used due to its advantages such as high separation efficiency, low energy consumption, and small footprint. However, due to the high hardness and high silicon content of the wastewater, if it directly enters the membrane system, calcium and magnesium salt deposits and silica scale are easily formed on the membrane surface, causing membrane fouling and clogging, severely shortening the service life of the membrane modules, and increasing operating costs. Therefore, strict hardness and silica removal pretreatment must be carried out before the wastewater enters the membrane system for treatment.

[0005] Currently, the commonly used industrial method for removing hardness and silicon is chemical precipitation. This involves adding reagents such as polyaluminum chloride (PAC), polyacrylamide (PAM), magnesium salts, sodium carbonate, and sodium hydroxide to different reaction tanks. This causes calcium and magnesium ions in the wastewater to combine with carbonate and hydroxide ions to form calcium carbonate and magnesium hydroxide precipitates, while silicon forms magnesium silicate precipitates under the action of magnesium salts. The precipitates are then removed through solid-liquid separation. However, this method has significant drawbacks in actual operation: the precipitates generated by the reaction easily adhere to the inner walls of the reaction tank and the inner walls of the flow passages, forming hard scale. As operating time increases, the scale gradually thickens, reducing the effective volume of the reaction tank, leading to a decrease in the cross-sectional area of ​​the flow passages or even complete blockage. This obstructs wastewater flow, forcing frequent shutdowns for manual cleaning, severely impacting the long-term stable operation of the entire wastewater treatment plant, and increasing the company's operation and maintenance costs and production risks. Utility Model Content

[0006] Addressing the shortcomings of existing methods for descaling and desiliconizing recycled water in coal chemical processes, this invention provides a device for descaling and desiliconizing recycled water in coal chemical processes. This device removes scale from the inner wall of the reaction tank and the flow holes during the descaling and desiliconizing processes, ensuring the continuous and stable operation of the pretreatment process for descaling and desiliconizing recycled water in coal chemical processes.

[0007] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows: A device for removing hardness and silica from recycled coal chemical water includes a first reaction tank, a second reaction tank, a third reaction tank, a fourth reaction tank, a fifth reaction tank, and a sedimentation tank arranged in series along the wastewater treatment flow direction. Each reaction tank is connected through a flow passage and is connected to a corresponding reagent dosing system. The device also includes a sludge discharge system and an intelligent control system connected to each reaction tank and the sedimentation tank. A tank wall descaling device is installed above the third, fourth, and fifth reaction tanks, and a flow passage descaling device is installed at the flow passage. The reagent dosing system includes a sodium hydroxide dosing unit connected to the first reaction tank, a PAC dosing unit connected to the second reaction tank, a PAM dosing unit connected to the third reaction tank, a magnesium dosing unit connected to the fourth reaction tank, and a hydrochloric acid dosing unit connected to the fifth reaction tank.

[0008] Furthermore, the first reaction tank is also connected to a sodium carbonate dosing unit and / or a carbon dioxide dosing unit.

[0009] Furthermore, the tank wall descaling device includes a scraper frame, a drive rod, a gearbox, and a drive motor. The lower part of the scraper frame is provided with an inclined scraper a that contacts the inner wall of the reaction tank. The scraper frame is connected to the gearbox via the drive rod, and the gearbox is connected to the drive motor via a rotating shaft.

[0010] Furthermore, the descaling device for the flow passage includes an annular outer shell and a scraper b disposed within the annular outer shell. The annular outer shell is provided with a toothed outer ring and an inner ring. The toothed outer ring is connected to a micro motor via a gear that is adapted to it. The inner ring includes an inner ring a and an inner ring b. Ball bearings are disposed between the toothed outer ring and the inner rings a and b. An annular ring is disposed between the inner rings a and b to connect the toothed outer ring and the scraper b. A sealing ring is disposed between the annular ring and the annular outer shell.

[0011] Furthermore, the descaling device for the flow passage is installed at the flow passage of the reaction tank, and the thickness of the descaling device for the flow passage is less than or equal to the thickness of the partition wall of the flow passage of the reaction tank.

[0012] Furthermore, the scraper a of the pool wall descaling device is made of hard alloy material and can remove scale with a thickness of ≤50mm.

[0013] Furthermore, the intelligent control system is connected to a pH meter, a silicon content monitor, a hardness monitor, a tank wall descaling device, and a flow hole descaling device.

[0014] Compared with the prior art, the beneficial effects of this utility model are: (1) This utility model sets up a tank wall descaling device in the reaction tank and a flow hole descaling device at the flow hole. The tank wall descaling device and the flow hole descaling device can achieve all-round removal of scale on the tank wall and flow hole, solve the problem of serious scale buildup in traditional devices, ensure the long-term stable operation of the recycled water pretreatment device, and reduce the number of shutdowns for cleaning. (2) The intelligent control system links online monitoring data to accurately adjust the dosage of the agent, avoiding waste of the agent. The intelligent control system is connected to the tank wall descaling device and the flow hole descaling device, which improves the automation and intelligence of descaling. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the pool wall descaling device of this utility model; Figure 2 This is a schematic diagram of the structure of the reaction tank of this utility model; Figure 3 This is a partial cross-sectional front view of the descaling device with flow holes of this utility model. Figure 4 This is a right-side structural schematic diagram of a partial cross-section of the descaling device with a flow passage of the present invention. Figure 5 This is a partial cross-sectional view of the descaling device with flow holes of this utility model, viewed from below the annular outer shell. In the diagram: 1-Drive rod; 2-Reduction gearbox; 3-Drive motor; 4-Fixed frame; 5-Scraper holder; 6-First reaction tank; 7-Second reaction tank; 8-Third reaction tank; 9-Fourth reaction tank; 10-Fifth reaction tank; 11-Sedimentation tank; 12-Annular outer shell; 13-Toothed outer ring; 14-Gear; 15-Ball bearing; 16-Inner ring a; 17-Scraper b; 18-Bolt. Detailed Implementation Example 1

[0016] refer to Figure 1-5Due to the large volumes of circulating water discharged from coal chemical production units, concentrated water generated during desalination, treated wastewater discharged from wastewater treatment systems, and periodic wastewater discharged from boiler units, these waters need to be collected, treated through membrane systems, and then recycled – a process known as water reuse. Before entering the membrane system, this water undergoes hardening and desilting to prevent clogging. However, during the hardening and desilting process, scale forms on the reaction tank walls and in the flow holes between the tanks, severely impacting the long-term stable operation of the unit and increasing maintenance workload. Therefore, this utility model provides a pretreatment device for recycled water in coal chemical industry, including a first reaction tank 6, a second reaction tank 7, a third reaction tank 8, a fourth reaction tank 9, a fifth reaction tank 10, and a sedimentation tank 11 arranged in series along the wastewater treatment flow direction. Each reaction tank is connected through a flow hole. A tank wall descaling device is installed above the third reaction tank 8, the fourth reaction tank 9, and the fifth reaction tank 10. The tank wall descaling device includes a scraper frame 5, a drive rod 1, a reduction gearbox 2, and a drive motor 3. An inclined scraper a is provided at the lower part of the scraper frame 5 to contact the inner wall of the reaction tank. The scraper frame 5 is connected to the reduction gearbox 2 through the drive rod 1. The reduction gearbox 2 is connected to the drive motor 3 through a rotating shaft. The scraper a of the tank wall descaling device is made of hard alloy material, with a contact degree with the tank wall ≥95%, and can remove scale with a thickness ≤50mm. The tank wall descaling device is installed on the upper part of the reaction tank through a fixing frame 4. During operation, the motor rotates forward, driving rod 1 moves downward, causing scraper frame 5 to move downward; the motor rotates in reverse, driving rod 1 moves upward, causing scraper frame 5 to move upward, thus achieving the removal of scale. A descaling device is installed at the flow hole. The thickness of the descaling device is less than the thickness of the partition wall of the reaction tank's flow hole. If the descaling device protrudes from the partition wall, it will affect the operation of the tank wall descaling device, preventing it from cleaning the scale on the partition wall. The descaling device with a flow passage includes an annular housing 12 and a scraper b17 disposed within the annular housing 12. The annular housing 12 contains a toothed outer ring 13 and an inner ring. The toothed outer ring 13 is connected to a micro motor via a matching gear 14. The inner ring includes an inner ring a16 and an inner ring b. Ball bearings 15 are disposed between the toothed outer ring 13 and the inner rings a16 and b. An annular ring is disposed between the inner rings a16 and b to secure the toothed outer ring 13 and the scraper b17 together with bolts 18. A sealing ring is disposed between the annular ring and the annular housing 12 to prevent wastewater from entering the descaling device and damaging the micro motor and gear 14. During operation, wastewater flows through the center of the annular housing 12 of the descaling device, and scale adhering to the inner surface of the annular housing 12 is removed by the scraper b17.

[0017] Each reaction tank is connected to a corresponding reagent dosing system, which includes a sodium hydroxide dosing unit connected to the first reaction tank 6, a PAC dosing unit connected to the second reaction tank 7, a PAM dosing unit connected to the third reaction tank 8, a magnesium dosing unit connected to the fourth reaction tank 9, and a hydrochloric acid dosing unit connected to the fifth reaction tank 10. The first reaction tank 6 is also connected to a sodium carbonate dosing unit and a carbon dioxide dosing unit. The system also includes a sludge discharge system and an intelligent control system connected to each reaction tank and the sedimentation tank 11. The intelligent control system is connected to a pH meter, a silicon content meter, a hardness meter, a tank wall descaling device, and a flow hole descaling device to monitor the operation of each reaction tank and control the tank wall descaling device and the flow hole descaling device to operate in a timed trigger mode.

[0018] A method for removing hardness and silica from recycled water in coal chemical industry, based on a device for removing hardness and silica from recycled water in coal chemical industry, includes the following: the wastewater from the coal chemical production unit includes wastewater from the circulating water unit, concentrated water generated during the desalination process, reclaimed water discharged after reaching standards from the wastewater treatment system, and wastewater periodically discharged from the boiler unit. The wastewater from the coal chemical production unit passes sequentially through a flocculation clarification tank, an ozone oxidation device, and an aerated biological filter to remove organic matter, reducing the COD to below 50 mg / L before entering the first reaction tank 6. The wastewater entering the first reaction tank 6 has a pH of 7-8, a hardness of 150 mg / L-450 mg / L, and a silica content of 50 mg / L-150 mg / L. Sodium hydroxide is added to the first reaction tank 6 to adjust the pH to 11 before entering the second reaction tank 7. PAC reagent is added to the second reaction tank 7 for reaction before entering the third reaction tank 8. After PAM reagent is added and reacted, the wastewater enters the fourth reaction tank 9. In the fourth reaction tank 9, magnesium reagent is added for silicon removal, and then the wastewater enters the fifth reaction tank 10. The dosage of PAC reagent, PAM reagent, and magnesium reagent is determined according to the hardness and silicon content of the wastewater. Hydrochloric acid is added to the fifth reaction tank 10 to adjust the pH to 7-8, and then the wastewater enters the sedimentation tank 11 for sedimentation. The supernatant from the sedimentation tank 11 flows out into the sand filter. The hardness of the supernatant flowing out of the sedimentation tank 11 is ≤100mg / L, and the silicon content is ≤20mg. The sludge from each reaction tank and sedimentation tank 11 is discharged through the sludge discharge system.

[0019] The intelligent control system adjusts the dosage of reagents based on online monitoring data and triggers the descaling devices on the tank walls and through-holes to start according to the set time, so as to remove the scale on the tank walls and through-holes of each reaction tank in a timely manner.

[0020] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for removing hardness and silicon from recycled water in coal chemical industry, characterized in that: The system includes a first reaction tank, a second reaction tank, a third reaction tank, a fourth reaction tank, a fifth reaction tank, and a sedimentation tank, arranged in series along the wastewater treatment flow direction. Each reaction tank is connected through a flow passage and is connected to a corresponding reagent dosing system. The system also includes a sludge discharge system and an intelligent control system connected to each reaction tank and sedimentation tank. The third, fourth, and fifth reaction tanks are equipped with tank wall descaling devices above them and flow passage descaling devices at the flow passages. The reagent dosing system includes a sodium hydroxide dosing unit connected to the first reaction tank, a PAC dosing unit connected to the second reaction tank, a PAM dosing unit connected to the third reaction tank, a magnesium dosing unit connected to the fourth reaction tank, and a hydrochloric acid dosing unit connected to the fifth reaction tank.

2. The apparatus for removing hardness and silicon from recycled water in coal chemical industry according to claim 1, characterized in that: The first reaction tank is also connected to a sodium carbonate dosing unit and / or a carbon dioxide dosing unit.

3. The apparatus for removing hardness and silicon from recycled water in coal chemical industry according to claim 1, characterized in that: The tank wall descaling device includes a scraper frame, a drive rod, a gearbox, and a drive motor. The lower part of the scraper frame is provided with an inclined scraper a that contacts the inner wall of the reaction tank. The scraper frame is connected to the gearbox through the drive rod, and the gearbox is connected to the drive motor through a rotating shaft.

4. The apparatus for removing hardness and silicon from recycled water in coal chemical industry according to claim 1, characterized in that: The descaling device for the flow passage includes an annular outer shell and a scraper b disposed inside the annular outer shell. The annular outer shell is provided with a toothed outer ring and an inner ring. The toothed outer ring is connected to a micro motor through a gear that is adapted to it. The inner ring includes an inner ring a and an inner ring b. Ball bearings are provided between the toothed outer ring and the inner rings a and b. An annular ring is provided between the inner rings a and b to connect the toothed outer ring and the scraper b. A sealing ring is provided between the annular ring and the annular outer shell.

5. The apparatus for removing hardness and silicon from recycled water in coal chemical industry according to claim 1, characterized in that: The descaling device for the flow passage is installed at the flow passage of the reaction tank, and the thickness of the descaling device for the flow passage is less than or equal to the thickness of the partition wall of the flow passage of the reaction tank.

6. The apparatus for removing hardness and silicon from recycled water in coal chemical industry according to claim 3, characterized in that: The scraper a of the pool wall descaling device is made of hard alloy material and can remove scale with a thickness of ≤50mm.

7. A device for removing hardness and silicon from recycled water in coal chemical industry according to any one of claims 1-6, characterized in that: The intelligent control system is connected to a pH meter, a silicon content monitor, a hardness meter, a tank wall descaling device, and a flow hole descaling device.

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