A circulating fluidized bed device for inducing crystallization and removing calcium

Abstract

This utility model discloses a circulating fluidized bed device for induced crystallization and calcium removal, belonging to the field of wastewater treatment technology. It includes a tank, with several supports evenly and equidistantly fixed to the outer wall of the tank near its bottom. This circulating fluidized bed device for induced crystallization and calcium removal, by setting up a tank, a reaction center cylinder, and a flow stabilizer cylinder, allows seed crystals to be added into the reaction center cylinder through an open top of the tank during operation. Combined with the action of the inlet mechanism and circulating water, the seed crystals are in a strongly fluidized state. Wastewater overflows from the top of the reaction center cylinder into the flow stabilizer cylinder, flowing downwards within the flow stabilizer cylinder. This achieves a distribution of different flow velocities. The high flow velocity in the reaction center cylinder ensures full fluidization of the seed crystals, the medium flow velocity in the flow stabilizer cylinder facilitates the adhesion and growth of calcium carbonate onto the seed crystals, and the low flow velocity in the tank facilitates the precipitation of calcium carbonate crystals, thereby improving the calcium ion removal effect and making the entire reaction process more efficient and stable.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology, specifically a circulating fluidized bed device for inducing crystallization and removing calcium. Background Technology

[0002] In the papermaking process, on the one hand, the high recycling rate of white water leads to the continuous accumulation of calcium concentration. At the same time, calcium carbonate is added in large quantities as a filler and coating during the production process, which also introduces calcium. On the other hand, the calcium contained in the original waste paper also enters the system during the production process. Under the combined effect of these two factors, papermaking wastewater is characterized by high calcium ion content. High concentrations of calcium ions can cause problems such as pipe scaling and anaerobic granular sludge calcification, affecting the stable operation of the wastewater treatment system.

[0003] Currently, calcium removal technologies include physical, chemical, and biological methods. Physical calcium removal methods mainly face disadvantages such as low calcium removal capacity and poor selectivity. Chemical methods are the most widely used calcium removal methods, but they have problems such as large dosage of reagents, large amount of sludge, and small crystal size that makes it difficult to precipitate and remove calcium. Biological methods use microorganisms to decompose urea to produce carbonate ions, which react with calcium ions to form calcium carbonate precipitate, but biological calcium removal processes can lead to problems such as excessive ammonia nitrogen content.

[0004] Chemical crystallization granulation (induced crystallization) has significant advantages such as fast crystallization rate, complete reaction, and high product purity. By introducing seed crystals and alkaline agents (sodium hydroxide, sodium carbonate) into water containing free calcium ions, nucleation sites are provided for calcium carbonate, effectively guiding the crystallization process. 2+ and carbonate ions (CO3) 2- Heterogeneous nucleation occurs on the surface of the seed crystal, thereby inhibiting spontaneous homogeneous nucleation in the solution. As calcium carbonate continues to adhere, the seed crystal slowly grows, eventually forming large precipitates that are discharged.

[0005] Induced crystallization requires strict control of the supersaturation of calcium carbonate within the metastable region; otherwise, calcium carbonate will spontaneously nucleate in a homogeneous manner, forming tiny calcium carbonate crystals that require additional flocculation and precipitation in a separate sedimentation tank for removal.

[0006] In summary, there is an urgent need for a highly efficient device for inducing crystallization that can automatically adjust the dosage according to changes in water quality, so as to keep the supersaturation of calcium carbonate in the metastable region and cause calcium carbonate to undergo heterogeneous nucleation. Utility Model Content

[0007] To overcome the above-mentioned defects, this utility model provides a circulating fluidized bed device for induced crystallization and calcium removal, which solves the problems of low calcium removal capacity and poor selectivity in physical calcium removal methods; large amount of chemical reagents, large amount of sludge, and small crystal size that makes it difficult to precipitate and remove calcium in chemical methods; and excessive ammonia nitrogen content in biological methods.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a circulating fluidized bed device for inducing crystallization and calcium removal, comprising a tank body, wherein several supports are uniformly and equidistantly fixedly connected to the outer wall of the tank body near its bottom, a conical hopper is fixedly connected to the bottom of the tank body, a reaction center cylinder is provided in the middle of the tank body, the reaction center cylinder is a cylindrical cylinder with an open top and bottom and a smaller bottom and a larger top, a flow stabilizing cylinder is provided inside the tank body, the flow stabilizing cylinder is covered by the reaction center cylinder, the flow stabilizing cylinder is a cylindrical cylinder with an open top and bottom and a constant diameter, a water outlet weir groove is opened on the outer wall of the tank body near its top, a water inlet pipe is provided at the bottom opening of the reaction center cylinder, a water inlet mechanism is provided at the end of the water inlet pipe connected to the reaction center cylinder, the water inlet pipe is L-shaped and the bent protruding part penetrates the conical hopper, the protruding part of the water inlet pipe forms a 30-degree angle with the conical hopper.

[0009] As a further embodiment of this utility model: two circulating water inlet pipes are symmetrically fixedly installed on the outer side of the tank body, and the opposite ends of the two circulating water inlet pipes extend through the tank body into the reaction center cylinder. A circulating water outlet pipe is fixedly installed on the outer wall of the tank body above the circulating water inlet pipes.

[0010] As a further embodiment of this utility model: a number of seed sampling tubes are fixedly installed on the outer wall of the tank, with each seed sampling tube spaced 1m apart at a height, and the seed sampling tubes are connected to the flow stabilizing cylinder.

[0011] As a further embodiment of this utility model: the water inlet mechanism includes an inner nozzle, an outer nozzle is fixedly connected above the inner nozzle, the outer nozzle covers the inner nozzle, and the outer nozzle has a plurality of nozzle suction ports evenly and equidistantly opened at a position near the port of the inner nozzle.

[0012] As a further embodiment of this utility model: the outer wall of the protruding part of the water inlet pipe is provided with a NaOH dosing port, and a sodium carbonate dosing port is fixedly connected to one side of the tank body, and the sodium carbonate dosing port is connected to the reaction center cylinder.

[0013] As a further embodiment of this utility model: two calcium ion monitors are fixedly installed on the outer wall of the inlet pipe and the top of the tank, respectively; a pH meter is fixedly installed on the top of the tank on one side of the calcium ion monitors; and a turbidity meter is fixedly installed on one side of the outlet weir.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0015] 1. This circulating fluidized bed device for induced crystallization and calcium removal comprises a tank, a central reaction cylinder, and a flow stabilizer. During operation, seed crystals are added to the central reaction cylinder through an open top opening in the tank. Wastewater is pumped to the inlet mechanism by a booster pump. Due to the jet action, negative pressure is generated, drawing in external seed crystals through the nozzle inlet. After mixing with the raw water, the mixture is jetted into the central reaction cylinder. Inside the central reaction cylinder, combined with the action of the inlet mechanism and circulating water, an upward flow velocity is formed, placing the seed crystals in a strongly fluidized state. Wastewater overflows from the top of the central reaction cylinder into the flow stabilizer, where it flows downwards. During the flow, calcium carbonate adheres to the seed crystals and grows, then sinks to the bottom of the tank to form a crystal bed. Wastewater is filtered through the crystal bed at the bottom of the tank and flows upward into the effluent weir. In this way, three different flow rates are achieved. The high flow rate in the reaction center cylinder fully fluidizes the seed crystals and improves the reaction efficiency. The medium flow rate in the steady flow cylinder is conducive to the adhesion and growth of calcium carbonate to the seed crystals. The low flow rate in the tank is conducive to the precipitation of calcium carbonate crystals, avoiding the inability of calcium carbonate crystals to precipitate and separate properly, thereby improving the removal effect of calcium ions. The entire reaction process is more efficient and stable.

[0016] 2. This circulating fluidized bed device for calcium removal through induced crystallization, by setting up an inlet pipe, a circulating water inlet pipe, and a circulating water outlet pipe, allows for the transportation of calcium-containing wastewater into the device during operation. NaOH is then added through the NaOH dosing pipe to provide the necessary chemical substances for the reaction. The coordinated use of the circulating water inlet and outlet pipes enables water recycling. Circulating water is drawn from the top of the tank and enters the bottom of the reaction chamber at a specific angle and direction through the circulating water inlet pipe, mixing with the raw water. This not only increases the flow rate in the reaction chamber but also creates a vortex flow, resulting in better seed crystal fluidization. Simultaneously, negative pressure is generated, drawing in a large number of seed crystals from the crystal bed to mix with the raw water, further improving reaction efficiency. This recycling method also saves water resources and reduces operating costs. Attached Figure Description

[0017] Figure 1 This is a front view structural diagram of the present invention;

[0018] Figure 2 This is a top view of the structure of this utility model;

[0019] Figure 3 This is a front view of the water inlet mechanism of this utility model;

[0020] Figure 4 This is a top view of the water inlet mechanism of this utility model.

[0021] In the diagram: 1. Tank body; 2. Support; 3. Conical hopper; 4. Reaction center cylinder; 5. Flow stabilizing cylinder; 6. Water outlet weir; 7. Water inlet pipe; 8. Water inlet mechanism; 801. Inner nozzle; 802. Outer nozzle; 803. Nozzle suction port; 9. Circulating water inlet pipe; 10. Circulating water outlet pipe; 11. Seed crystal sampling pipe; 12. NaOH dosing port; 13. Sodium carbonate dosing port; 14. Calcium ion monitor; 15. pH meter; 16. Turbidity meter. Detailed Implementation

[0022] The technical solution of this patent will be further described in detail below with reference to specific embodiments.

[0023] like Figure 1-4 As shown, this utility model provides a technical solution: a circulating fluidized bed device for inducing crystallization and removing calcium, including a tank 1. Several supports 2 are fixedly connected evenly and at equal intervals on the outer wall of the tank 1 near its bottom. A conical hopper 3 is fixedly connected to the bottom of the tank 1. The inverted conical structure of the conical hopper 3 allows the precipitated calcium carbonate crystals to smoothly gather at the bottom of the conical hopper 3 and be discharged through a slag discharge pipe connected to the bottom of the conical hopper 3, avoiding the accumulation of calcium carbonate crystals at the bottom of the tank 1, ensuring the cleanliness of the tank 1 and the smooth progress of the reaction. A reaction center cylinder 4 is provided in the middle of the tank 1. The reaction center cylinder 4 is a cylindrical cylinder with an open top and bottom and a small bottom and a large top. A flow stabilizing cylinder 5 is provided inside the tank 1. The flow stabilizing cylinder 5 is covered by the reaction center cylinder 4. The flow stabilizing cylinder 5 is a cylindrical cylinder with an open top and bottom and a constant diameter. A water outlet weir 6 is opened on the outer wall of the tank 1 near its top.

[0024] A water inlet pipe 7 is provided at the bottom opening of the reaction center cylinder 4. A NaOH dosing port 12 is provided on the outer wall of the protruding part of the water inlet pipe 7. A sodium carbonate dosing port 13 is fixedly connected to one side of the tank body 1. The sodium carbonate dosing port 13 is connected to the reaction center cylinder 4. A water inlet mechanism 8 is provided at the end of the water inlet pipe 7 connected to the reaction center cylinder 4. The water inlet mechanism 8 includes an inner nozzle 801. An outer nozzle 802 is fixedly connected above the inner nozzle 801. The outer nozzle 802 covers the inner nozzle 801. The outer nozzle 802 is evenly and equidistantly positioned near the port of the inner nozzle 801. The system is equipped with several nozzle inlets 803. Due to the water inlet mechanism 8, this two-stage structure allows the seed crystals and raw water to mix more thoroughly. When the booster pump pumps the calcium-containing wastewater to the inner nozzle 801, the jet action generates negative pressure, and the nozzle inlet 803 of the outer nozzle 802 will draw in the external seed crystals, so that the seed crystals and raw water are fully mixed at the nozzle before being jetted into the reaction center cylinder 4, which improves the initial mixing effect of the reaction. The water inlet pipe 7 is designed in an L shape and the bent and protruding part passes through the cone hopper 3. The protruding part of the water inlet pipe 7 forms a 30-degree angle with the cone hopper 3.

[0025] Two circulating water inlet pipes 9 are symmetrically fixedly installed on the outer side of the tank body 1. The opposite ends of the two circulating water inlet pipes 9 extend through the tank body 1 into the reaction center cylinder 4. A circulating water outlet pipe 10 is fixedly installed on the outer wall of the tank body 1 above the circulating water inlet pipes 9. Through the circulating water inlet pipes 9, the circulating water can enter the bottom of the reaction center cylinder 4 at a certain angle and speed. After mixing with the raw water, it forms an upward flow velocity, which not only increases the flow velocity of the reaction center cylinder 4, but also forms a vortex flow, making the fluidization effect of the seed crystal better. At the same time, the entry of the circulating water can also generate negative pressure, which draws in a large number of seed crystals on the crystal bed and mixes with the raw water, further improving the reaction efficiency. Several seed crystal sampling pipes 11 are fixedly installed on the outer wall of the tank body 1. Each seed crystal sampling pipe 11 is spaced 1m apart at a height. The seed crystal sampling pipes 11 are connected to the flow stabilizing cylinder 5.

[0026] Two calcium ion monitors 14 are fixedly installed on the outer wall of the inlet pipe 7 and the top of the tank 1, respectively. A pH meter 15 is fixedly installed on the top of the tank 1, next to the calcium ion monitors 14, and a turbidity meter 16 is fixedly installed on one side of the outlet weir 6. With the calcium ion monitors 14, pH meter 15 and turbidity meter 16, these monitoring instruments can monitor the calcium ion concentration of the inlet and outlet water, the pH value of the reaction zone and the turbidity of the outlet water in real time, providing accurate data for the PLC control system so as to automatically adjust the dosage of NaOH and sodium carbonate, ensure that the supersaturation of calcium carbonate is in the metastable region, avoid insufficient calcium ion removal rate or excessive dosage causing spontaneous homogeneous nucleation of calcium carbonate, generating tiny calcium carbonate crystals, and achieve precise control of the reaction process.

[0027] The working principle of this utility model is as follows: Seed crystals are added from the top of the open tank 1 to the reaction center cylinder 4. The amount of seed crystals added is 1 / 3 to 1 / 2 of the height of the tank 1. The booster pump pumps the calcium-containing wastewater to the water inlet mechanism 8. Due to the jet effect, a negative pressure is generated, and the nozzle suction port 803 draws in the external seed crystals, mixes with the raw water, and then jets into the reaction center cylinder 4. The circulation pump draws water from the top of the tank 1 and enters the bottom of the reaction center cylinder 4 at a 30-degree upward tangential angle, mixing with the raw water. Combined with the water inlet mechanism 8 and the circulating water, the upward flow velocity in the reaction center cylinder 4 reaches 150-250 m / h, forming a negative pressure. Seed crystals are drawn in from the bottom of the reaction center cylinder 4 and mixed with the raw water. The seed crystals are in a strongly fluidized state. The wastewater overflows from the top of the reaction center cylinder 4 to the flow stabilizing cylinder 5. The water flows downwards in the stabilizer 5 at a velocity of 30-60 m / h. The generated calcium carbonate adheres to the seed crystals and grows, slowly sinking to the bottom of the tank 1 to form a crystal bed of a certain height. After being filtered through the crystal bed at the bottom of the tank 1, the wastewater flows upwards into the effluent weir 6. During this process, the calcium ion concentration in the influent and effluent, the pH of the reaction zone, and the turbidity of the effluent are continuously monitored. Based on the monitoring data, the PLC automatically adjusts the dosage of NaOH and sodium carbonate to stably control the supersaturation of calcium carbonate in the metastable region, avoiding insufficient calcium ion removal rate and avoiding excessive dosage that could lead to spontaneous homogeneous nucleation of calcium carbonate and the formation of tiny calcium carbonate crystals. During operation, the height of the seed crystals in the tank 1 is monitored through the seed crystal sampling tube 11, and calcium carbonate particles are quantitatively discharged.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] The preferred embodiments of this patent have been described in detail above. However, this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.

Claims

1. A circulating fluid bed apparatus for induced crystallization lime removal comprising a tank (1) characterized by: The outer wall of the tank (1) is fixedly connected with several supports (2) at equal intervals near its bottom. The bottom of the tank (1) is fixedly connected with a cone (3). The middle of the interior of the tank (1) is provided with a reaction center cylinder (4). The reaction center cylinder (4) is a cylindrical cylinder with an open top and bottom and a smaller bottom and a larger top. The interior of the tank (1) is provided with a flow stabilizing cylinder (5). The flow stabilizing cylinder (5) covers the outside of the reaction center cylinder (4). The flow stabilizing cylinder (5) is a cylindrical cylinder with an open top and bottom and the same diameter. The outer wall of the tank (1) is provided with a water outlet weir (6) near its top. The bottom opening of the reaction center cylinder (4) is provided with a water inlet pipe (7). The end of the water inlet pipe (7) connected to the reaction center cylinder (4) is provided with a water inlet mechanism (8). The water inlet pipe (7) is L-shaped and the bent protruding part passes through the cone (3). The protruding part of the water inlet pipe (7) forms a 30-degree angle with the cone (3).

2. A circulating fluid bed apparatus for induced crystallization lime removal according to claim 1, characterized in that: Two circulating water inlet pipes (9) are symmetrically fixedly installed on the outside of the tank (1). The opposite ends of the two circulating water inlet pipes (9) extend through the tank (1) into the reaction center cylinder (4). A circulating water outlet pipe (10) is fixedly installed on the outer wall of the tank (1) above the circulating water inlet pipes (9).

3. A circulating fluid bed device for induced crystallization lime removal according to claim 1, characterized in that: Several seed sampling tubes (11) are fixedly installed on the outer wall of the tank (1), with each seed sampling tube (11) spaced 1m apart at a height. The seed sampling tubes (11) are connected to the flow stabilizer (5).

4. A circulating fluid bed device for induced crystallization lime removal according to claim 1, characterized in that: The water inlet mechanism (8) includes an inner nozzle (801), and an outer nozzle (802) is fixedly connected above the inner nozzle (801). The outer nozzle (802) covers the inner nozzle (801), and a plurality of nozzle inlets (803) are evenly and equidistantly opened near the port of the inner nozzle (801).

5. A circulating fluid bed device for induced crystallization lime removal according to claim 1, characterized in that: The outer wall of the protruding part of the water inlet pipe (7) is provided with a NaOH dosing port (12), and a sodium carbonate dosing port (13) is fixedly connected to one side of the tank (1). The sodium carbonate dosing port (13) is connected to the reaction center cylinder (4).

6. A circulating fluid bed device for induced crystallization lime removal according to claim 1, characterized in that: Two calcium ion monitors (14) are fixedly installed on the outer wall of the inlet pipe (7) and the top of the tank (1), respectively. A pH meter (15) is fixedly installed on the top of the tank (1) on one side of the calcium ion monitor (14), and a turbidity meter (16) is fixedly installed on one side of the outlet weir (6).

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