Coagulation system with built-in calcium fluoride crystallizer

Abstract

The invention discloses a coagulation system with a built-in calcium fluoride crystallizer. A first-stage coagulation tank is communicated with the bottom of a second-stage coagulation tank, wherein a water outlet is formed in the side wall of the upper end of the second-stage coagulation tank; the calcium fluoride crystallizer comprises an outer guide cylinder fixed in the primary coagulating basin, an inner guide cylinder inserted in the outer guide cylinder, a water inlet pipe inserted in the inner guide cylinder from top to bottom and a chemical inlet pipe inserted between the outer guide cylinder and the inner guide cylinder, the upper edge of the outer guide cylinder is higher than the liquid level of the primary coagulating basin, and the lower end of the inner guide cylinder extends out of the outer guide cylinder; the height of a circle of water passing holes formed in the side wall of the upper end of the inner guide cylinder is lower than the height of the liquid level of the first-stage coagulating basin, wastewater flows along the inner guide cylinder from top to bottom, and the wastewater in the first-stage coagulating basin flows into an annular gap between the inner guide cylinder and the outer guide cylinder from bottom to top; according to the invention, the existing coagulating basin can be transformed with high efficiency and low cost, and the crystallization rate of calcium fluoride is greatly improved.

Description

Technical Field

[0001] This invention relates to a wastewater treatment technology, and more particularly to a coagulation system with a built-in calcium fluoride crystallizer. Background Technology

[0002] In the field of fluoride-containing wastewater treatment, chemical precipitation is one of the most widely used technologies for defluorination, with coagulation tanks being widely employed due to their stable structure and ease of construction. However, traditional chemical precipitation methods for defluorination in wastewater have the following significant drawbacks:

[0003] (1) The calcium fluoride crystals generated by traditional chemical precipitation methods are mostly smaller than 20 μm. Small calcium fluoride crystals have poor sedimentation performance, resulting in low solid-liquid separation efficiency.

[0004] (2) The crystallization process of calcium fluoride in the coagulation tank lacks a controllable growth environment, and the crystallization rate is generally less than 65%, which will result in waste of the reagent.

[0005] (3) If the existing crystallization strengthening device is installed in the coagulation tank, although it can increase the crystal particle size, due to its large size, it is mostly necessary to destroy the existing coagulation tank structure when installing it in the existing coagulation tank. In particular, for existing coagulation tanks with top plates, the closed top structure restricts the hoisting of large equipment, making the modification difficult and costly, about 40-60% of the new construction cost.

[0006] (4) Using a fluidized bed crystallizer to enhance crystallization can increase the crystal particle size. However, existing crystallizers require changes to the water flow pattern and must be equipped with structures such as guide walls, which results in existing crystallizers occupying more than 30% of the effective tank volume of the coagulation tank. Summary of the Invention

[0007] To overcome the above-mentioned defects, the present invention provides a coagulation system with a built-in calcium fluoride crystallizer. This coagulation system with a built-in calcium fluoride crystallizer can be easily modified from the existing coagulation tank in the plant area without breaking the top plate or tank wall, which greatly improves the crystallization rate of wastewater in the coagulation tank.

[0008] The technical solution adopted by this invention to solve its technical problem is as follows: A coagulation system with a built-in calcium fluoride crystallizer, comprising a primary coagulation tank and a secondary coagulation tank, the bottoms of which are connected by a water outlet (the shape of which includes, but is not limited to, rectangles, squares, etc.). An outlet (the cross-section of which can be rectangular or circular) is provided on the upper sidewall of the secondary coagulation tank. A calcium fluoride crystallizer is provided inside the primary coagulation tank. The calcium fluoride crystallizer includes an inner guide tube, an outer guide tube, an inlet pipe, and a chemical inlet pipe. The outer guide tube is fixedly installed inside the primary coagulation tank, with its upper edge higher than the liquid level in the primary coagulation tank. The inner guide tube is coaxially and fixedly inserted inside the outer guide tube, with its lower end extending beyond the outer guide tube. The lower outer side of the inner guide tube has a set length, and a ring of water passage holes is opened on the upper side wall of the inner guide tube. The height of the water passage holes on the upper side wall of the inner guide tube is lower than the liquid level of the primary coagulation tank. The inlet pipe is inserted into the inner side of the inner guide tube from top to bottom. Wastewater entering from the inlet pipe flows downward along the inner guide tube from top to bottom. Wastewater in the primary coagulation tank can flow upward into the annular gap between the inner and outer guide tubes from bottom to top. The chemical inlet pipe is inserted into the annular gap formed between the outer and inner guide tubes. The chemical inlet pipe can deliver the chemical into the annular gap between the inner and outer guide tubes. The mixture in the annular gap between the inner and outer guide tubes can enter the inner guide tube through the water passage holes.

[0009] As a further improvement of the present invention, an air-lift device is also fixedly installed in the secondary coagulation tank. The air-lift device includes a crystal outlet pipe and an air inlet pipe. The lower end of the crystal outlet pipe extends into the bottom of the secondary coagulation tank and forms a set gap with the bottom surface of the secondary coagulation tank. The upper end of the crystal outlet pipe is bent to form a crystal discharge port to discharge crystals to a designated position. An inclined downward-extending air nozzle is provided on the side wall of the lower end of the crystal outlet pipe. The air nozzle is connected to the air inlet pipe to allow compressed gas to enter the crystal outlet pipe from bottom to top. The crystal precipitate deposited at the bottom of the secondary coagulation tank can enter the crystal outlet pipe from the lower end under the action of negative pressure suction and flow upward with the high-pressure gas.

[0010] As a further improvement of the present invention, the air stripping device further includes an annular branch pipe, which is fixedly installed at the bottom of the secondary coagulation tank. The lower side of the annular branch pipe is provided with a plurality of openings at intervals, and a set gap is formed between the lower side of the annular branch pipe and the bottom surface of the secondary coagulation tank. The lower end of the crystal outlet pipe is connected to the annular branch pipe.

[0011] As a further improvement of the present invention, the annular branch pipe is a single-ring structure or a multi-ring interconnected structure, and there is a distance of 10 to 30 cm between the lower side of the annular branch pipe and the bottom surface of the secondary coagulation tank.

[0012] As a further improvement of the present invention, at least one propeller or stirring device is installed in the inner guide tube of the calcium fluoride crystallizer. The stirring center of the propeller or stirring device always coincides with the axis of the inner guide tube. The propeller or stirring device can agitate the water flow in the inner guide tube and push the water flow downward.

[0013] As a further improvement of the present invention, a plurality of the aforementioned propellers or stirring devices are evenly installed in the inner guide tube in a manner from top to bottom.

[0014] As a further improvement of the present invention, the water outlet section of the inlet pipe of the calcium fluoride crystallizer extends vertically from top to bottom and is inserted into the inner guide tube. The drug outlet section of the drug inlet pipe first extends downward from top to bottom to the outer side of the lower section of the outer guide tube, and then bends horizontally and is inserted into the annular gap between the inner guide tube and the outer guide tube. The height of the water outlet of the inlet pipe is lower than the height of the water passage hole of the inner guide tube.

[0015] As a further improvement of the present invention, the water passage holes on the inner guide tube are arranged in a ring array distribution pattern with uniform intervals along the circumference and axial direction of the inner guide tube, and the lowest point of the outlet of the secondary coagulation tank is higher than the lowest point of the ring of water passage holes on the inner guide tube.

[0016] As a further improvement of the present invention, both the primary coagulation tank and the secondary coagulation tank are fixedly covered with a grid structure top plate, and the top plate is provided with a maintenance entrance for maintenance personnel to enter and exit. The water inlet pipe and the chemical inlet pipe of the calcium fluoride crystallizer are inserted through the maintenance entrance above the primary coagulation tank, and the crystal outlet pipe and the air inlet pipe of the air stripping device are inserted through the maintenance entrance above the secondary coagulation tank.

[0017] As a further improvement of the present invention, the inner and outer guide tubes of the calcium fluoride crystallizer are made of corrosion-resistant materials (PP, PVC, stainless steel, etc.), and the distance between the inner and outer guide tubes is 10cm to 300cm (selected according to the size of the maintenance entrance on the top plate). The double-layer concentric cylindrical structure formed by the inner and outer guide tubes of the calcium fluoride crystallizer is installed directly below the maintenance entrance. The double-layer concentric cylindrical structure formed by the inner and outer guide tubes is fixedly installed in the primary coagulation tank by means of iron chain hoisting or screw locking.

[0018] The beneficial effects of this invention are as follows: The calcium fluoride crystallizer and air-lift device of this invention adopt a modular design structure, and its slender structure can be easily implanted in the existing coagulation tank in the plant area, occupying less space in the coagulation tank. The process of modifying the existing coagulation tank does not require breaking the top plate or tank wall, resulting in high modification efficiency and low modification cost. It does not affect the normal coagulation and sedimentation treatment of wastewater in the existing coagulation tank. The outer guide tube and inner guide tube of the calcium fluoride crystallizer of this invention form a gradient flow field, which makes the added reagent more fully mixed with the influent, greatly improving the calcium fluoride crystallization rate. This is conducive to the rapid growth of calcium fluoride crystals into large-particle calcium fluoride crystals. The large-particle calcium fluoride crystals have excellent settling performance and can quickly settle to the bottom of the tank in the secondary coagulation tank. The gas device removes the crystals by air pressure. The annular branch pipe at the lower end of the air-lift device can fully absorb the calcium fluoride crystals at all positions at the bottom of the secondary coagulation tank, ensuring that the calcium fluoride crystals are quickly and fully discharged, and achieving efficient solid-liquid separation. Attached Figure Description

[0019] Figure 1 This is a perspective view of the present invention;

[0020] Figure 2 This is the front view of the present invention;

[0021] Figure 3 This is a front view of the primary coagulation tank of the present invention;

[0022] Figure 4 This is a top view of the primary coagulation tank of the present invention;

[0023] Figure 5 This is a front view of the secondary coagulation tank of the present invention;

[0024] Figure 6 This is a top view of the secondary coagulation tank of the present invention;

[0025] Figure 7 This is a perspective view of the calcium fluoride crystallizer of the present invention;

[0026] Figure 8 This is a top view of the calcium fluoride crystallizer of the present invention;

[0027] Figure 9 This is a perspective view of the air-lift device of the present invention;

[0028] Figure 10 This is a front view of the air-lift device of the present invention. Detailed Implementation

[0029] Example: A coagulation system with a built-in calcium fluoride crystallizer 300, comprising a primary coagulation tank 100 and a secondary coagulation tank 200, the bottoms of the primary coagulation tank 100 and the secondary coagulation tank 200 being connected by a water inlet 170 (the shape of the water inlet 170 includes, but is not limited to, rectangles, squares, etc.), and an outlet 210 (the cross-section of the outlet 210 can be rectangular or circular) is provided on the upper side wall of the secondary coagulation tank 200, characterized in that: the primary coagulation tank 100... A calcium fluoride crystallizer 300 is installed inside the coagulation tank 100. The calcium fluoride crystallizer 300 includes an inner guide tube 110, an outer guide tube 120, an inlet pipe 140, and a chemical inlet pipe 150. The outer guide tube 120 is fixedly installed inside the primary coagulation tank 100, with its upper edge higher than the liquid level of the primary coagulation tank 100. The inner guide tube 110 is coaxially and fixedly inserted inside the outer guide tube 120, with its lower end extending out of the outer guide tube 120. The lower outer side is of a set length. A ring of water passage holes 111 is formed on the upper side wall of the inner guide tube 110. The height of the water passage holes 111 on the upper side wall of the inner guide tube 110 is lower than the liquid level of the primary coagulation tank 100. The inlet pipe 140 is inserted into the inner side of the inner guide tube 110 from top to bottom. Wastewater entering from the inlet pipe 140 flows downward along the inner guide tube 110 from top to bottom. Wastewater in the primary coagulation tank 100 can flow upward from bottom to top into the inner guide tube 110. Within the annular gap between the inner guide tube 110 and the outer guide tube 120, the drug inlet tube 150 is inserted into the annular gap formed between the outer guide tube 120 and the inner guide tube 110. The drug inlet tube 150 can deliver the drug into the annular gap between the inner guide tube 110 and the outer guide tube 120. The mixture in the annular gap between the inner guide tube 110 and the outer guide tube 120 can enter the inner guide tube 110 through the water passage 111.

[0030] The calcium fluoride crystallizer 300 forms a double-layer concentric cylindrical structure. Fluorine-containing influent is added into the inner guide tube 110 and flows downwards along the inner guide tube 110, eventually flowing out of the inner guide tube 110 and into the primary coagulation tank 100. At this time, a negative pressure is formed between the inner guide tube 110 and the outer guide tube 120, drawing the solution from the primary coagulation tank 100 into the annular cavity between the inner guide tube 110 and the outer guide tube 120. The inner guide tube 110 is slightly longer than the outer guide tube 120, and its lower end extends beyond the lower end of the outer guide tube 120 to prevent the solution in the primary coagulation tank 100 from flowing into the inner guide tube 110. During the upward movement of the solution within the annular cavity between the inner guide tube 110 and the outer guide tube 120, it interacts with the solution passing through the inlet pipe 150. The added reagent is mixed in the annular cavity, and then enters the inner guide tube 110 through the water passage 111 on the upper side wall of the inner guide tube 110 to mix again with the fluoride-containing influent. It then continues to flow downward into the coagulation tank. A gradient flow field is formed between the outer guide tube 120 and the inner guide tube 110, which makes the reagent and the fluoride-containing influent mix more thoroughly, greatly improving the calcium fluoride crystallization rate. The mixture that has fully reacted in the primary coagulation tank 100 flows to the secondary coagulation tank 200 through the water passage 170 at the lower end of the wall shared by the primary coagulation tank 100 and the secondary coagulation tank 200. The calcium fluoride crystals settle rapidly in the secondary coagulation tank 200. The defluorinated water is discharged from the outlet 210 of the secondary coagulation tank 200. The calcium fluoride crystals deposited at the bottom of the secondary coagulation tank 200 can be removed periodically.

[0031] An air-lift device is also fixedly installed inside the secondary coagulation tank 200. The air-lift device includes a crystal outlet pipe 430 and an air inlet pipe. The lower end of the crystal outlet pipe 430 extends into the bottom of the secondary coagulation tank 200 and forms a set gap with the bottom surface of the secondary coagulation tank 200. The upper end of the crystal outlet pipe 430 is bent to form a crystal discharge port to discharge crystals to a designated position. An inclined downward-extending air nozzle 420 is provided on the lower side wall of the crystal outlet pipe 430. The air nozzle 420 is connected to the air inlet pipe to allow compressed gas to enter the crystal outlet pipe 430 from bottom to top. The crystal precipitate deposited at the bottom of the secondary coagulation tank 200 can enter the crystal outlet pipe 430 from the lower end under the action of negative pressure suction and flow upward with the high-pressure gas. A slanted tee can be installed at the lower end of the crystal outlet tube 430. A gas nozzle 420 is installed on a channel extending downwards from the top of the slanted tee. Gas enters the crystal outlet tube 430 from the gas nozzle 420 and moves upwards along the tube wall of the crystal outlet tube 430, forming a negative pressure that drives the lower opening of the crystal outlet tube 430 to draw in the mixed liquid containing crystals from the bottom of the coagulation tank. The mixed liquid with a large amount of crystals flows out from the crystal outlet tube 430 and is collected. Subsequently, it can be dehydrated by a dehydration device to collect high-purity large-particle calcium fluoride crystals.

[0032] The air-lift device also includes an annular branch pipe 410, which is fixedly installed at the bottom of the secondary coagulation tank 200. The lower side of the annular branch pipe 410 has several openings 411 spaced apart, forming a predetermined gap between the lower side of the annular branch pipe 410 and the bottom surface of the secondary coagulation tank 200. The lower end of the crystal outlet pipe 430 communicates with the annular branch pipe 410. The shape of the annular branch pipe 410 can match the shape of the secondary coagulation tank 200, allowing it to fully absorb the crystals deposited at the bottom of the secondary coagulation tank 200.

[0033] The annular branch pipe 410 has a single-ring structure or a multi-ring interconnected structure, and there is a distance of 10-30 cm between the lower side of the annular branch pipe 410 and the bottom surface of the secondary coagulation tank 200. The annular branch pipe 410 can be set into multiple rings according to the area of ​​the secondary coagulation tank 200, and is evenly distributed at the bottom of the secondary coagulation tank 200. The height of the annular branch pipe 410 from the bottom of the tank is 10-30 cm to ensure effective absorption of crystals at the bottom of the secondary coagulation tank 200.

[0034] At least one agitator or stirring device 130 is installed in the inner guide tube 110 of the calcium fluoride crystallizer 300. The stirring center of the agitator or stirring device 130 always coincides with the axis of the inner guide tube 110. The agitator or stirring device 130 can agitate the water flow in the inner guide tube 110 and push the water flow downward. The agitator or stirring device 130 can agitate the water flow in the inner guide tube 110 and push it downward, so that the fluoride-containing water flows out of the inner guide tube 110 quickly, thereby forming a large negative pressure between the inner guide tube 110 and the outer guide tube 120.

[0035] Multiple propellers or stirring devices are evenly installed in the inner guide tube 110 from top to bottom.

[0036] The water outlet section of the inlet pipe 140 of the calcium fluoride crystallizer 300 extends vertically from top to bottom and is inserted into the inner guide tube 110. The drug outlet section of the drug inlet pipe 150 first extends downward from top to bottom to the outer side of the lower section of the outer guide tube 120, and then bends horizontally before being inserted into the annular gap between the inner guide tube 110 and the outer guide tube 120. The height of the outlet 210 of the inlet pipe 140 is lower than the height of the water passage hole 111 of the inner guide tube 110. The inlet pipe 140 extends vertically within the inner guide tube 110, allowing the fluoride-containing inlet water to flow rapidly downwards. The lower end of the inlet pipe 140 is ideally lower than the height of the water passage 111 in the inner guide tube 110 to prevent interference with the entry of the mixed liquid in the annular cavity into the inner guide tube 110 through the water passage 111. The chemical inlet pipe 150 extends from above into the coagulation tank and then bends through the wall of the outer guide tube 120, directly adding the chemical between the outer guide tube 120 and the inner guide tube 110. The optimal position for the chemical inlet pipe 150 through the outer guide tube 120 is in the lower middle part of the outer guide tube 120, ensuring that the solution in the primary coagulation tank 100 quickly mixes with the chemical after entering the annular cavity between the inner guide tube 110 and the outer guide tube 120, preventing the chemical from entering the inner guide tube 110 without sufficient mixing.

[0037] The water passage holes 111 on the inner guide tube 110 are evenly spaced along the circumference and axial direction of the inner guide tube 110 to form a ring array distribution pattern. The lowest point of the outlet 210 of the secondary coagulation tank 200 is higher than the lowest point of the ring of water passage holes 111 on the inner guide tube 110. The evenly distributed ring of water passage holes 111 allows the mixed liquid in the annular cavity to enter the inner guide tube 110 evenly along the water passage holes 111. The height of the outlet 210 of the secondary coagulation tank 200 is higher than the height of the water passage holes 111 on the upper side wall of the inner guide tube 110, ensuring that the mixed liquid in the annular cavity flows into the secondary coagulation tank 200 without entering the inner guide tube 110.

[0038] Both the primary coagulation tank 100 and the secondary coagulation tank 200 are fixedly covered with a grid-structured top plate 180. The top plate 180 is provided with a maintenance entrance 160 for maintenance personnel to enter and exit. The water inlet pipe 140 and the chemical inlet pipe 150 of the calcium fluoride crystallizer 300 are inserted through the maintenance entrance 160 above the primary coagulation tank 100. The crystal outlet pipe 430 and the air inlet pipe of the air stripping device are inserted through the maintenance entrance 160 above the secondary coagulation tank 200.

[0039] The inner guide cylinder 110 and outer guide cylinder 120 of the calcium fluoride crystallizer 300 are fixedly connected to form a double-layer concentric cylindrical structure. The installation position is directly below the maintenance inlet 160, and its radial dimension is smaller than that of the maintenance inlet 160, so that it can be smoothly hoisted into the primary coagulation tank 100 through the maintenance inlet 160. When the calcium fluoride crystallizer 300 and the air-lift device are installed in the primary coagulation tank 100 and the secondary coagulation tank 200, the calcium fluoride crystallizer 300 is hoisted to the maintenance inlet 160 of the primary coagulation tank 100 using hoisting equipment, and then enters the primary coagulation tank 100 through the maintenance inlet 160. Workers enter the primary coagulation tank 100 at a designated depth via maintenance inlet 160 and fix the calcium fluoride crystallizer 300 inside. The pipeline of the air-lift device is installed into the secondary coagulation tank 200 via maintenance inlet 160. Workers then enter the secondary coagulation tank 200 via maintenance inlet 160 to arrange and install the pipeline of the air-lift device at the bottom of the secondary coagulation tank 200. The entire installation process does not require damage to the existing top plate 180 and tank wall of the coagulation tank, making the installation convenient and quick.

[0040] The inner guide tube 110 and outer guide tube 120 of the calcium fluoride crystallizer 300 are made of corrosion-resistant materials (PP, PVC, stainless steel, etc.). The distance between the inner and outer guide tubes 120 is 10cm to 300cm (selected according to the size of the maintenance inlet 160 on the top plate 180). The double-layer concentric cylindrical structure formed by the inner guide tube 110 and outer guide tube 120 of the calcium fluoride crystallizer 300 is installed directly below the maintenance inlet 160. The double-layer concentric cylindrical structure formed by the inner guide tube 110 and outer guide tube 120 is fixedly installed in the primary coagulation tank 100 by means of iron chain hoisting or screw locking.

Claims

1. A coagulation system with a built-in calcium fluoride crystallizer, comprising a primary coagulation tank (100) and a secondary coagulation tank (200), the bottoms of the primary and secondary coagulation tanks being connected via an inlet (170), and an outlet (210) being provided on the upper sidewall of the secondary coagulation tank, characterized in that: The primary coagulation tank is equipped with a calcium fluoride crystallizer (300). The calcium fluoride crystallizer includes an inner guide tube (110), an outer guide tube (120), an inlet pipe (140), and a chemical inlet pipe (150). The outer guide tube is fixedly installed inside the primary coagulation tank, with its upper edge higher than the liquid level in the primary coagulation tank. The inner guide tube is coaxially fixedly inserted inside the outer guide tube, with its lower end extending a predetermined length beyond the lower end of the outer guide tube. A ring of water passage holes (111) is formed on the upper sidewall of the inner guide tube, and the height of the water passage holes on the upper sidewall of the inner guide tube is lower than... The liquid level in the primary coagulation tank is such that the inlet pipe is inserted from top to bottom inside the inner guide tube. Wastewater entering from the inlet pipe flows downward along the inner guide tube from top to bottom. Wastewater in the primary coagulation tank can flow from bottom to top into the annular gap between the inner and outer guide tubes. The chemical inlet pipe is inserted into the annular gap formed between the outer and inner guide tubes. The chemical inlet pipe can deliver the chemical into the annular gap between the inner and outer guide tubes. The mixed liquid in the annular gap between the inner and outer guide tubes can enter the inner guide tube through the water passage hole.

2. The coagulation system with a built-in calcium fluoride crystallizer according to claim 1, characterized in that: The secondary coagulation tank is also fixedly installed with an air-lift device, which includes a crystal outlet pipe (430) and an air inlet pipe. The lower end of the crystal outlet pipe extends into the bottom of the secondary coagulation tank and forms a set gap with the bottom surface of the secondary coagulation tank. The upper end of the crystal outlet pipe is bent to form a crystal discharge port to discharge crystals to a designated position. The lower end of the crystal outlet pipe is provided with an inclined downward-extending air nozzle (420). The air nozzle is connected to the air inlet pipe to allow compressed gas to enter the crystal outlet pipe from bottom to top. The crystal precipitate deposited at the bottom of the secondary coagulation tank can enter the crystal outlet pipe from the lower end under the action of negative pressure suction and flow upward with the high-pressure gas.

3. The coagulation system with a built-in calcium fluoride crystallizer according to claim 2, characterized in that: The air-lift device also includes an annular branch pipe (410), which is fixedly installed at the bottom of the secondary coagulation tank. Several openings (411) are provided at intervals on the lower side of the annular branch pipe. A set gap is formed between the lower side of the annular branch pipe and the bottom surface of the secondary coagulation tank. The lower end of the crystal outlet pipe is connected to the annular branch pipe.

4. The coagulation system with a built-in calcium fluoride crystallizer according to claim 3, characterized in that: The annular branch pipe has a single-ring structure or a multi-ring interconnected structure, and there is a distance of 10 to 30 cm between the lower side of the annular branch pipe and the bottom surface of the secondary coagulation tank.

5. The coagulation system with a built-in calcium fluoride crystallizer according to claim 1, characterized in that: At least one propeller or stirring device (130) is installed in the inner guide tube of the calcium fluoride crystallizer. The stirring center of the propeller or stirring device always coincides with the axis of the inner guide tube. The propeller or stirring device can agitate the water flow in the inner guide tube and push the water flow downward.

6. The coagulation system with a built-in calcium fluoride crystallizer according to claim 3, characterized in that: Multiple of the aforementioned propellers or stirring devices are evenly installed in the inner guide tube from top to bottom.

7. The coagulation system with a built-in calcium fluoride crystallizer according to claim 1, characterized in that: The water outlet section of the inlet pipe of the calcium fluoride crystallizer extends vertically from top to bottom and is inserted into the inner guide tube. The drug outlet section of the drug inlet pipe first extends downward from top to bottom to the outer side of the lower section of the outer guide tube, and then bends horizontally before being inserted into the annular gap between the inner and outer guide tubes. The height of the water outlet of the inlet pipe is lower than the height of the water passage hole of the inner guide tube.

8. The coagulation system with a built-in calcium fluoride crystallizer according to claim 1 or 7, characterized in that: The water passage holes on the inner guide tube are evenly spaced along the circumference and axial direction of the inner guide tube to form a ring array distribution pattern. The lowest point of the outlet of the secondary coagulation tank is higher than the lowest point of the ring of water passage holes on the inner guide tube.

9. The coagulation system with a built-in calcium fluoride crystallizer according to claim 2, characterized in that: Both the primary coagulation tank and the secondary coagulation tank are fixedly covered with a grid structure top plate (180). The top plate is provided with a maintenance entrance (160) for maintenance personnel to enter and exit. The water inlet pipe and the chemical inlet pipe of the calcium fluoride crystallizer are inserted through the maintenance entrance above the primary coagulation tank, and the crystal outlet pipe and the air inlet pipe of the air stripping device are inserted through the maintenance entrance above the secondary coagulation tank.

10. The coagulation system with a built-in calcium fluoride crystallizer according to claim 9, characterized in that: The inner and outer guide tubes of the calcium fluoride crystallizer are made of corrosion-resistant material. The distance between the inner and outer guide tubes is 10cm to 300cm. The double-layer concentric cylindrical structure formed by the inner and outer guide tubes of the calcium fluoride crystallizer is installed directly below the maintenance inlet. The double-layer concentric cylindrical structure formed by the inner and outer guide tubes is fixedly installed in the primary coagulation tank by means of iron chain hoisting or screw locking.

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