Device for reducing hardness of wastewater

Abstract

The utility model relates to a device for reducing hardness of wastewater, which comprises a reaction device, an outlet of the reaction device is connected with a reaction and separation integrated device, the reaction and separation integrated device comprises a reaction cylinder arranged at the bottom and a scum hopper arranged at the top, and a water distribution cylinder arranged above the reaction cylinder is communicated with the reaction cylinder in a sleeving manner; the bottom of the reaction cylinder is communicated with a water distribution pipeline system, the water distribution pipeline system is used for inputting different materials into the reaction cylinder, and a material outlet is formed in the top of the reaction and separation integrated device; and the material outlet is connected with an inlet of the water producing pool. By means of the low-hardness wastewater treatment device, the hardness of high-hardness wastewater can be stably reduced to 20-30 mg / L, and the treatment cost is low.

Description

Technical Field

[0001] The utility model relates to a water treatment device, in particular to a device for reducing the hardness of wastewater. Background Art

[0002] In the process of water treatment, water contains calcium and magnesium scale-forming ions, and the hardness of water is measured by "hardness". High-hardness water will cause scaling of equipment and pipelines. As the scale accumulates day by day, it will also cause pipeline blockage, reduced flow rate, and decreased heating efficiency of equipment. Especially in the reverse osmosis, evaporation crystallization devices, etc. in the zero liquid discharge process of wastewater, there are strict requirements for the hardness of the influent water. Ca2+ and Mg2+ ions in water constitute the hardness of water. Once these ions enter the concentration reduction or evaporation crystallization equipment, they will form scale and adhere to the membrane or the tube wall of the column, reducing the water production efficiency of the membrane and evaporation, and even blocking the membrane pores, pipelines or devices, affecting the operation of the equipment.

[0003] There are various methods to reduce the hardness of water. These methods vary according to the type of water hardness (temporary hardness or permanent hardness) and the application scenario (household, industrial, etc.), mainly including:

[0004] I. Boiling method, which is mainly applicable to temporary hard water, that is, water containing calcium bicarbonate and magnesium bicarbonate. By heating and boiling, calcium bicarbonate and magnesium bicarbonate decompose to form insoluble calcium carbonate and magnesium hydroxide precipitates, thereby reducing the hardness of water. This method can significantly reduce the hardness of temporary hard water, but has limited effect on permanent hard water (such as water containing calcium sulfate, calcium chloride, etc.).

[0005] II. Ion exchange method, which uses a specific cation exchange resin to replace calcium and magnesium ions in water with sodium ions (or other ions), thereby reducing the hardness of water. The effect of this method is stable and accurate, and the process is mature. It is widely used in household and industrial fields. In particular, most household water purifiers adopt this method. The softening water equipment (water softener) generally used is also called "ion exchanger".

[0006] III. Lime method (lime-soda method), adding lime (calcium hydroxide) to water to convert calcium bicarbonate and magnesium bicarbonate in water into calcium carbonate and magnesium hydroxide precipitates, thereby reducing the hardness of water. For non-carbonate hardness, soda ash (sodium carbonate) can be further added for treatment. It is mainly used to treat high-hardness water with large flow rates and is usually used as a pretreatment means. The lime-soda softening and hardness removal method generates a large amount of waste residue and has a high operating cost. And in order to control the operating cost, usually the cold method (i.e., the raw water temperature, not the warm method or the hot method) is adopted in engineering practice, and the actual effluent hardness is above 150mg / L, and it is difficult to achieve the effect of significantly reducing the hardness. Summary of the Utility Model

[0007] In view of the above problems, the present utility model provides a device for reducing the hardness of wastewater.

[0008] To solve this technical problem, the present utility model adopts the following solutions:

[0009] A device for reducing the hardness of wastewater, including a reaction device, the outlet of the reaction device is connected to a reaction-separation integrated device.

[0010] The reaction-separation integrated device includes a reaction cylinder arranged at the bottom and a scum hopper arranged at the top. A water distribution cylinder arranged above the reaction cylinder is sleeved and communicated with the reaction cylinder; the bottom of the reaction cylinder is communicated with a water distribution pipeline system, and the water distribution pipeline system is used to input different materials into the reaction cylinder. A material outlet is arranged at the top of the reaction-separation integrated device; the material outlet is connected to the inlet of a production water tank.

[0011] The outlet of the production water tank is connected to the suction port of a gas-liquid mixing pump. A gas suction nozzle is installed at the suction port of the gas-liquid mixing pump. A gas flowmeter is installed at the front end of the gas suction nozzle. The end of the gas suction nozzle is used to be connected to the steel plant flue gas. The steel plant flue gas is introduced into the gas-liquid mixing pump through the gas suction nozzle to form dissolved air water.

[0012] The outlet of the gas-liquid mixing pump is connected to the inlet of a gas-liquid separation tank, and the liquid phase outlet of the gas-liquid separation tank is connected to the water distribution pipeline system.

[0013] Further, the gas-liquid separation tank is a closed tank body, including a water inlet, an exhaust port arranged on the opposite side of the water inlet, and a water outlet arranged on the side wall of the tank body. An automatic exhaust valve is installed at the exhaust port.

[0014] Further, the upper end of the reaction cylinder is cylindrical and the lower end is conical. Then the water distribution pipeline system includes at least one vertical pipe arranged at the conical bottom of the reaction cylinder, and the opening of the vertical pipe faces upward.

[0015] Further, the length of the vertical pipe is 1 - 10 cm.

[0016] Further, the reaction cylinder is rectangular, and a dissolved air chamber is arranged in the reaction cylinder. Then the water distribution pipeline system includes at least one straight pipe horizontally arranged in the dissolved air chamber.

[0017] Further, the length of the straight pipe is 1 - 10 cm, the end of the straight pipe is connected to an elbow, and the elbow opens upward relative to the dissolved air chamber.

[0018] Further, the caliber of the elbow is 4 - 15 cm.

[0019] Further, the length of the straight pipe is greater than 10 cm, and holes with a diameter of 10-15 mm are drilled on the straight pipe every 20-30 cm.

[0020] Further, the water distribution pipeline system includes a assembled pipe formed by splicing 2 straight pipes into an H shape, and multiple holes are opened on the assembled pipe.

[0021] Further, holes with a diameter of 10-15 mm are opened on the assembled pipe every 20-30 cm.

[0022] By adopting the foregoing technical solutions, compared with the prior art, the present utility model can utilize CO2 in the steel plant flue gas as the main hardness removal agent, and at the same time utilize the waste heat of the flue gas as a heat source to increase the reaction temperature, improve the reaction efficiency, and combine with a gas-liquid mixing pump to dissolve CO2 into the wastewater to form dissolved gas (high-content CO2) water, which has a remarkable effect of reducing hardness.

[0023] Further, the CO2 bubbles in the dissolved gas (high-content CO2) water have tiny particle sizes, increasing the contact reaction area, greatly reducing the operating cost, and significantly improving the treatment effect of reducing the hardness of the wastewater. Finally, the hardness of the wastewater can be stably reduced to 20-30 mg / L.

[0024] Furthermore, the present utility model optimizes the water distribution pipeline system for realizing uniform water distribution, which is very important for promoting the full reaction of the dissolved gas water and the wastewater. Through 3 optimized water distribution pipeline designs, chemical reactions occur efficiently in the reaction cylinder, achieving the effect of stably reducing the hardness of the wastewater. Description of the Drawings

[0025] Figure 1 is a schematic structural diagram of the device for reducing the hardness of wastewater provided by the embodiment of the present utility model;

[0026] Figure 2 is a schematic structural diagram of the reaction and separation integrated device provided by the embodiment of the present utility model. Detailed Embodiments

[0027] The technical solutions of the present utility model will be clearly and completely described below in conjunction with the drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present utility model, rather than all embodiments, and are only used to illustrate the present utility model and should not be construed as limiting the scope of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified in the manufacturer are all conventional products that can be obtained through commercial purchase.

[0028] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0029] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] Embodiment 1:

[0031] Reference Figure 1 , the device for reducing the hardness of wastewater includes a reaction device 1, the reaction device 1 is connected to a stirring device 2, and the outlet of the reaction device 1 is connected to a reaction and separation integrated device 3.

[0032] For the specific structure of the reaction and separation integrated device 3, refer to Figure 2 , the reaction and separation integrated device 3 includes a reaction cylinder 31 arranged at the bottom and a scum hopper 33 arranged at the top. A water distribution cylinder 32 arranged above the reaction cylinder 31 is sleeved and communicated with the reaction cylinder 31; the bottom of the reaction cylinder 31 is communicated with a water distribution pipeline system 34, and the water distribution pipeline system 34 is used to input different materials into the reaction cylinder 31. A material outlet is arranged at the top of the reaction and separation integrated device 3; the material outlet is connected to the inlet of a production water tank 4;

[0033] The outlet of the production water tank 4 is connected to the suction port of a gas-liquid mixing pump 5. A gas suction nozzle is installed at the suction port of the gas-liquid mixing pump 5, a gas flow meter is installed at the front end of the gas suction nozzle, and the end of the gas suction nozzle is used to be connected to the steel plant flue gas. The steel plant flue gas is introduced into the gas-liquid mixing pump through the gas suction nozzle to form dissolved air water;

[0034] The outlet of the gas-liquid mixing pump 5 is connected to the inlet of a gas-liquid separation tank 6, and the liquid phase outlet of the gas-liquid separation tank 6 is connected to the water distribution pipeline system 34.

[0035] Embodiment 2:

[0036] Based on Embodiment 1, this embodiment introduces the specific operation method of the device as follows:

[0037] The water quality indexes of the comprehensive wastewater of a certain iron and steel enterprise are shown in Table 1. It can be seen that the hardness of the wastewater is as high as 800 mg / l, which is high-hardness wastewater.

[0038] Table 1 Wastewater Quality Index Table

[0039] Serial number Item Unit Index Remarks 1 pH 6～9 2 SS mg / l 300 3 <![CDATA[COD cr > mg / l 60～150 4 <![CDATA[BOD5]]> mg / l 10～30 5 Oil mg / l ≤20 6 Total hardness mg / l 800 <![CDATA[Calculated as CaCO3]]> 7 Temporary hardness mg / l 60 <![CDATA[Calculated as CaCO3 <!-- 3 -->]]> 8 Total alkalinity mg / l 250 <![CDATA[Calculated as CaCO3]]> 9 Salt content mg / l 2000 10 <![CDATA[Cl - > mg / l 450

[0040] The device in Embodiment 1 is used for wastewater treatment, including the following steps:

[0041] 1) Discharge the above-mentioned high-hardness wastewater into the reaction device, add calcium hydroxide to control the pH at about 10.0, and simultaneously add 25 mg / L of PAC (polyaluminum chloride) and 1.0 mg / L of PAM (polyacrylamide). After stirring, a mixed liquid of CaCO3, Mg(OH)2, CaCl2 and water is generated by reaction.

[0042] The main reaction equations are as follows:

[0043]

[0044] 2) The mixed liquid is fed into the reaction and separation integrated device. After the mixed liquid and the materials from the water distribution pipeline system are mixed in the reaction cylinder and the reaction is completed, the floating slag is removed through the floating slag hopper, and the separated liquid phase enters the production water tank.

[0045] 3) A part of the wastewater (flow rate Q) in the production water tank is discharged up to standard or enters the next process, and another part (flow rate 0.5Q) enters the gas-liquid mixing pump. A gas suction nozzle is installed at the suction port of the gas-liquid mixing pump, and a gas flow meter is installed in front of the gas suction nozzle to adjust and control the gas suction volume. The end of the gas suction nozzle is connected to the steel plant flue gas. The gas suction nozzle introduces the steel plant flue gas rich in CO2 near the impeller of the pump, and the impeller is used to introduce the gas into the blades of the pump for pressurized mixing, which can ensure the efficient mixing and dissolution of the steel plant flue gas rich in CO2 and the wastewater (flow rate 0.5Q) at the inlet of the gas-liquid mixing pump. At the same time, the high temperature (about 200 °C) of the flue gas raises the temperature of the wastewater. Through this series of processes, the outlet of the gas-liquid mixing pump obtains dissolved gas (CO2) water with a water temperature of about 55 °C and a pressure of about 0.4 MPa.

[0046] 4) Among the gases injected into the gas-liquid mixing pump, the undissolved part will form air cavities before the pressure is released, which will affect the dissolved gas effect. Therefore, a gas-liquid separation tank needs to be installed in the outlet pipeline of the gas-liquid mixing pump, and an automatic exhaust valve needs to be installed on the gas-liquid separation tank to discharge the undissolved part of the gas to avoid the formation of air cavities and affect the dissolved gas effect.

[0047] The dissolved gas (CO2) water in step 3) has a water temperature of about 55°C, and reacts with step 1) to form CaCO 3、 Mg(OH) 2、 The mixed liquid of CaCl2 and water enters the reaction and separation integrated device in step 2) together.

[0048] The bottom of the reaction and separation integrated device is a water distribution pipeline system, which reacts the dissolved gas (CO2) water with a water temperature of about 55°C in step 3) with step 1) to generate CaCO 3、 Mg(OH) 2、 The mixed liquid of CaCl2 and water is fully mixed and evenly distributed. The water distribution pipeline system needs to be designed according to the shape of the reaction cylinder. In this example, the reaction and separation integrated device adopts a cylindrical shape. The water distribution pipeline system adopts a vertical pipe directly installed at the conical bottom of the cylindrical reaction cylinder. The vertical pipe should be as short as possible, the pipe diameter should be larger than the diameter of the drainage pipe, and the vertical pipe mouth should face upward.

[0049] In the reaction tube of the reaction-separation integrated device, the dissolved gas (CO2) water with a water temperature of about 55°C in step 3) reacts with step 1) to generate a mixed liquid of CaCO3, Mg(OH)2, CaCl2 and water, which is fully mixed and evenly distributed through the water distribution pipeline system. The dissolved gas (CO2) water with a pressure of about 0.4MPa is released from the water distribution pipeline system and the pressure drops to a normal level. The CO2 gas dissolved in this process will be released in the form of many tiny bubbles (bubble diameter is about 20-30 microns). The CO2 bubbles have a small particle size, which greatly increases the contact reaction area and improves the reaction efficiency. The following reactions will occur efficiently in the reaction tube:

[0050]

[0051]

[0052] In addition, the introduction of 55°C dissolved air (CO2) water can increase the water temperature in the reaction tube to about 40°C. The increase in water temperature also greatly increases the reaction efficiency and reduces the hardness of the final water output.

[0053] Due to the weak acidity of carbonic acid, + 、CO3 2- When it is continuously consumed, the carbon dioxide dissolved in water can continue to produce CO3 2- , achieving almost the same effect as Na2CO3 softening.

[0054] In addition to the above chemical reactions taking place in the reaction tube, the CaCO generated in step 1) 3、Mg(OH)2, and fine sediments such as CaCO3 produced in the reaction tube in this step adhere to the surface of tiny bubbles (bubble diameter is about 20-30 microns). These fine sediments will float to the water surface with the tiny bubbles to form scum. The scum is discharged through the scum bucket in the reaction and separation integrated device and finally sent to the sludge dewatering device.

[0055] In summary, in the reaction and separation integrated device, efficient reaction is achieved, and solid (CaCO3, Mg(OH)2 precipitates and suspended solids in wastewater, etc.) and liquid separation are simultaneously achieved. After reaction and separation, the hardness of the wastewater can be stably reduced to less than 20 mg / L, and the inlet and outlet water quality indicators are shown in Table 2 below.

[0056] Table 2 Comprehensive wastewater index table of the whole plant before and after treatment

[0057] Serial number Item Unit Influent water quality index Influent water quality index Remarks 1 pH 6～9 7～9 2 SS mg / l 300 ≤3 3 <![CDATA[COD cr > mg / l 60～150 ≤40 4 <![CDATA[BOD5]]> mg / l 10～30 ≤10 5 Oil mg / l ≤20 ≤2 6 Total hardness mg / l 800 ≤20 <![CDATA[Calculated as CaCO3]]> 7 Total alkalinity mg / l 250 ≤10 <![CDATA[Calculated as CaCO3]]>

[0058] Example 3

[0059] This embodiment introduces a specific device operation method based on embodiment 1, as follows:

[0060] The device in Example 1 is used to treat wastewater. The wastewater comes from the comprehensive wastewater of a steel enterprise. The total hardness of the wastewater is 500 mg / l in terms of CaCO3, the pH of the wastewater is 7-9, the SS is 200 mg / l, the COD is 60 mg / l, the BOD is 10 mg / l, the total alkalinity is 100 mg / l in terms of CaCO3, the salt content is 1000 mg / l, and the Cl content is 100 mg / l. The process specifically includes the following steps:

[0061] 1) The high-hardness wastewater is discharged into the reaction device, and calcium hydroxide is added to control the pH at 10.5. PAC (polyaluminium chloride) 10 mg / L and PAM (polyacrylamide) 0.5 mg / L are added simultaneously. After stirring, the mixture of CaCO3, Mg(OH)2, CaCl2 and water is reacted.

[0062] 2) The mixed liquid is sent to the reaction and separation integrated device. After the mixed liquid and the material from the water distribution pipeline system are mixed in the reaction cylinder to complete the reaction, the scum is removed by the scum bucket, and the separated liquid phase enters the water production pool.

[0063] 3) A portion of the wastewater in the production water tank (flow rate Q) meets the standards and is discharged externally or enters the next process. Another portion (flow rate 0.15Q) enters the gas-liquid mixing pump. A gas suction nozzle is installed at the suction port of the gas-liquid mixing pump, and a gas flow meter is installed in front of the gas suction nozzle to adjust and control the gas intake. The end of the gas suction nozzle is connected to the steel plant flue gas. The gas suction nozzle introduces the steel plant flue gas rich in CO2 near the impeller of the pump, and with the help of the impeller, the gas is introduced into the blades of the pump for pressurized mixing, which can ensure the efficient mixing and dissolution of the steel plant flue gas rich in CO2 with the wastewater (flow rate 0.15Q) at the inlet of the gas-liquid mixing pump. At the same time, the high temperature of the flue gas (about 200 °C) raises the temperature of the wastewater. Through this series of processes, the gas-liquid mixing pump outputs dissolved gas (CO2) water with a water temperature of about 60 °C and a pressure of about 0.5 MPa.

[0064] 4) Among the gases injected into the gas-liquid mixing pump, the undissolved part will form gas pockets before the pressure is released, affecting the gas dissolution effect. Therefore, a gas-liquid separation tank needs to be installed in the outlet pipeline of the gas-liquid mixing pump, and an automatic exhaust valve needs to be installed on the gas-liquid separation tank to discharge the undissolved part of the gas to avoid the formation of gas pockets and affecting the gas dissolution effect.

[0065] The dissolved gas (CO2) water with a water temperature of about 60 °C in step 3), reacts with the CaCO 3、 Mg(OH) 2、 The mixture of CaCl2 and water, enters the reaction and separation integrated device in step 2) together.

[0066] The bottom of the reaction and separation integrated device is a water distribution pipeline system, which mixes the dissolved gas (CO2) water in step 3) with the mixture of CaCO 3、 Mg(OH) 2、 CaCl2 and water from the reaction in step 1) fully and evenly distributes the water. The water distribution pipeline system needs to be designed according to the shape of the reaction cylinder. In this example, the reaction and separation integrated device is rectangular, so horizontal straight pipes are placed in the gas dissolution chamber of the reaction cylinder. The length of the straight pipe is 5 cm, and an elbow is installed at the end of the straight pipe. The diameter of the elbow is 10 cm, and the elbow opens upward relative to the gas dissolution chamber of the reaction cylinder to directly discharge the dissolved gas water and wastewater.

[0067] In the reaction cylinder of the reaction and separation integrated device, the dissolved gas (CO2) water in step 3), reacts with the mixture of CaCO3, Mg(OH)2, CaCl2 and water from the reaction in step 1). Through the water distribution pipeline system, they are fully mixed and evenly distributed. After the dissolved gas (CO2) water is released from the water distribution pipeline system, the pressure drops to the normal level. Before this process, the dissolved CO2 gas will be released in the form of many tiny bubbles (bubble diameter about 20 - 30 microns). Due to the tiny particle size of the CO2 bubbles, the contact reaction area is greatly increased, improving the reaction efficiency.

[0068] In addition, the introduction of dissolved air (CO2) water can increase the water temperature in the reaction tube to about 45°C. The increase in water temperature also greatly increases the reaction efficiency and reduces the hardness of the final water output.

[0069] Due to the weak acidity of carbonic acid, + 、CO3 2- When it is continuously consumed, the carbon dioxide dissolved in water can continue to produce CO3 2- , achieving almost the same effect as Na2CO3 softening.

[0070] In addition to the above chemical reactions taking place in the reaction tube, the CaCO generated in step 1) 3、 Mg(OH)2, and fine sediments such as CaCO3 produced in the reaction tube in this step adhere to the surface of tiny bubbles (bubble diameter is about 20-30 microns). These fine sediments will float to the water surface with the tiny bubbles to form scum. The scum is discharged through the scum bucket in the reaction and separation integrated device and finally sent to the sludge dewatering device.

[0071] In summary, in the reaction and separation integrated device, efficient reaction is achieved, and solid (CaCO3, Mg(OH)2 precipitates and suspended solids in wastewater, etc.) and liquid separation are simultaneously achieved. After reaction and separation, the hardness of the wastewater can be stably reduced to less than 20 mg / L.

[0072] Example 4

[0073] This embodiment introduces a specific device operation method based on embodiment 1, as follows:

[0074] The device in Example 1 is used to treat wastewater. The wastewater comes from the comprehensive wastewater of a steel enterprise. The total hardness of the wastewater is 900 mg / l in terms of CaCO3, the pH of the wastewater is 6-7, the SS is 600 mg / l, the COD is 150 mg / l, the BOD is 30 mg / l, the total alkalinity is 300 mg / l in terms of CaCO3, the salt content is 2000 mg / l, and the Cl content is 500 mg / l. The following steps are specifically included:

[0075] 1) The high-hardness wastewater is discharged into the reaction device, and calcium hydroxide is added to control the pH at 9.0. PAC (polyaluminium chloride) 30 mg / L and PAM (polyacrylamide) 3.0 mg / L are added simultaneously. After stirring, the mixture of CaCO3, Mg(OH)2, CaCl2 and water is reacted to generate a mixed liquid.

[0076] 2) The mixed material liquid is fed into the reaction and separation integrated device. After the mixed material liquid and the material from the water distribution pipeline are mixed in the reaction cylinder to complete the reaction, the floating slag is removed through the floating slag hopper, and the separated liquid phase enters the production water tank.

[0077] 3) A part of the wastewater (flow rate Q) in the production water tank meets the standards and is discharged externally or enters the next process, and another part (flow rate 0.4Q) enters the gas-liquid mixing pump. A gas suction nozzle is installed at the suction port of the gas-liquid mixing pump, and a gas flowmeter is installed in front of the gas suction nozzle to adjust and control the gas suction volume. The end of the gas suction nozzle is connected to the steel plant flue gas. The gas suction nozzle introduces the steel plant flue gas rich in CO2 near the impeller of the pump, and with the help of the impeller, the gas is introduced into the blades of the pump for pressurized mixing, which can ensure the efficient mixing and dissolution of the steel plant flue gas rich in CO2 and the wastewater (flow rate 0.5Q) at the inlet of the gas-liquid mixing pump. At the same time, the high temperature (about 200 °C) of the flue gas raises the temperature of the wastewater. Through this series of processes, the dissolved gas (CO2) water with a water temperature of about 50 °C and a pressure of about 0.3 MPa is obtained at the outlet of the gas-liquid mixing pump.

[0078] 4) Among the gases injected into the gas-liquid mixing pump, the undissolved part will form air pockets before the pressure is released, affecting the dissolved gas effect. Therefore, a gas-liquid separation tank needs to be installed in the outlet pipeline of the gas-liquid mixing pump, and an automatic exhaust valve needs to be installed on the gas-liquid separation tank to discharge the undissolved part of the gas to avoid the formation of air pockets and affecting the dissolved gas effect.

[0079] The dissolved gas (CO2) water in step 3) reacts with the CaCO generated in step 1) 3、 Mg(OH) 2、 The mixed material liquid of CaCl2 and water enters the reaction and separation integrated device in step 2) together.

[0080] The bottom of the reaction and separation integrated device is a water distribution pipeline system, which mixes the dissolved gas (CO2) water in step 3) with the CaCO generated in step 1) 3、 Mg(OH) 2、 The mixed material liquid of CaCl2 and water is fully mixed and evenly distributed. The water distribution pipeline system needs to be designed according to the shape of the reaction cylinder. In this example, the reaction and separation integrated device uses a reaction cylinder with a large area for discharging the dissolved gas water, and the water distribution pipeline uses an assembled pipe formed by splicing 2 straight pipes into an H shape. The assembled pipe is drilled with holes with a diameter of 10 - 15 mm every 20 - 30 cm to discharge the dissolved gas water and wastewater.

[0081] In the reaction cylinder of the reaction-separation integrated device, the dissolved gas (CO2) water in step 3) reacts with step 1) to generate a mixed liquid of CaCO3, Mg(OH)2, CaCl2 and water, which is fully mixed and evenly distributed through the water distribution pipeline system. After the dissolved gas (CO2) water is released from the water distribution pipeline system, the pressure drops to a normal level. The CO2 gas dissolved before this process will be released in the form of many tiny bubbles (bubble diameter is about 20-30 microns). The CO2 bubbles have a small particle size, which greatly increases the contact reaction area and improves the reaction efficiency.

[0082] In addition, the introduction of dissolved air (CO2) water can increase the water temperature in the reaction tube to about 40°C. The increase in water temperature also greatly increases the reaction efficiency and reduces the hardness of the final water output.

[0083] Due to the weak acidity of carbonic acid, + 、CO3 2- When it is continuously consumed, the carbon dioxide dissolved in water can continue to produce CO3 2- , achieving almost the same effect as Na2CO3 softening.

[0084] In addition to the above chemical reactions taking place in the reaction tube, the CaCO generated in step 1) 3、 Mg(OH)2, and fine sediments such as CaCO3 produced in the reaction tube in this step adhere to the surface of tiny bubbles (bubble diameter is about 20-30 microns). These fine sediments will float to the water surface with the tiny bubbles to form scum. The scum is discharged through the scum bucket in the reaction and separation integrated device and finally sent to the sludge dewatering device.

[0085] In summary, in the reaction and separation integrated device, efficient reaction is achieved, and solid (CaCO3, Mg(OH)2 precipitates and suspended solids in wastewater, etc.) and liquid separation are simultaneously achieved. After reaction and separation, the hardness of the wastewater can be stably reduced to less than 20 mg / L.

[0086] Comparative Example 1

[0087] A reaction and separation integrated device, compared with Example 1, differs in that it does not contain a water distribution pipeline system, specifically, it includes a reaction cylinder arranged at the bottom of the reaction and separation integrated device and a scum bucket arranged at the top, a water distribution cylinder arranged above the reaction cylinder is sleeve-connected and communicated with the reaction cylinder; the bottom of the reaction cylinder is connected to a water inlet pipeline (a circular tube with a diameter of 2 cm), and the water inlet pipeline is used to input different materials into the reaction cylinder, and a material outlet is arranged at the top of the reaction and separation integrated device.

[0088] Furthermore, the device for reducing the hardness of wastewater includes a reaction device, the above-mentioned reaction and separation integrated device, a water production pool, a gas-liquid mixing pump, and a gas-liquid separation tank, wherein:

[0089] The reaction device is connected to a stirring device, and the material outlet of the reaction device is connected to the reaction-separation integrated device. After the materials react in the reaction-separation integrated device, the materials that have completed the reaction pass through a scum hopper to remove the scum and then enter the production water tank.

[0090] The water outlet of the production water tank is connected to the gas-liquid mixing pump. A gas suction nozzle is installed at the suction inlet of the gas-liquid mixing pump. A gas flow meter is installed at the front end of the gas suction nozzle. The end of the gas suction nozzle is connected to the steel plant flue gas. The outlet of the gas-liquid mixing pump is connected to the gas-liquid separation tank. The liquid phase outlet of the gas-liquid separation tank is connected to the water inlet pipeline, and the dissolved air water is directly sent into the reaction cylinder through the water inlet pipeline.

[0091] Using the above device to treat the wastewater according to the method in Example 2, and finally detecting a part of the water outlet of the production water tank, it is found that the effect of reducing the hardness is general, and the hardness of the water outlet quality is 150 mg / L.

[0092] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principle and purpose of the present invention.

Claims

1. A device for reducing the hardness of wastewater, characterized in that: It includes a reaction device, and the outlet of the reaction device is connected to a reaction-separation integrated device. The reaction-separation integrated device includes a reaction cylinder arranged at the bottom and a scum hopper arranged at the top. A water distribution cylinder arranged above the reaction cylinder is sleeved and communicated with the reaction cylinder. The bottom of the reaction cylinder is communicated with a water distribution pipeline system, and the water distribution pipeline system is used to input different materials into the reaction cylinder. A material outlet is arranged at the top of the reaction-separation integrated device. The material outlet is connected to the inlet of a production water tank. The outlet of the production water tank is connected to the suction port of a gas-liquid mixing pump. A gas suction nozzle is installed at the suction port of the gas-liquid mixing pump. A gas flowmeter is installed at the front end of the gas suction nozzle. The end of the gas suction nozzle is used to be connected to the flue gas of a steel mill. The flue gas of the steel mill is introduced into the gas-liquid mixing pump through the gas suction nozzle to form dissolved air water. The outlet of the gas-liquid mixing pump is connected to the inlet of a gas-liquid separation tank, and the liquid phase outlet of the gas-liquid separation tank is connected to the water distribution pipeline system.

2. The device for reducing the hardness of wastewater according to claim 1, wherein: The gas-liquid separation tank is a closed tank body, including a water inlet, an exhaust port arranged on the opposite side of the water inlet, and a water outlet arranged on the side wall of the tank body. An automatic exhaust valve is installed at the exhaust port.

3. The device for reducing the hardness of wastewater according to claim 1 or 2, characterized in that: The upper end of the reaction cylinder is cylindrical, and the lower end is conical. Then the water distribution pipeline system includes at least one riser pipe arranged at the conical bottom of the reaction cylinder, and the opening of the riser pipe faces upward.

4. The device for reducing the hardness of wastewater according to claim 3, characterized in that: The length of the riser pipe is 1-10 cm.

5. The device for reducing the hardness of wastewater according to claim 1 or 2, characterized in that: The reaction cylinder is rectangular, and a dissolved air chamber is arranged in the reaction cylinder. Then the water distribution pipeline system includes at least one straight pipe horizontally arranged in the dissolved air chamber.

6. The device for reducing the hardness of wastewater according to claim 5, characterized in that: The length of the straight pipe is 1-10 cm, and the end of the straight pipe is connected to an elbow, and the elbow opens upward relative to the dissolved air chamber.

7. The device for reducing the hardness of wastewater according to claim 6, characterized in that: The diameter of the elbow is 4-15 cm.

8. The device for reducing the hardness of wastewater according to claim 5, characterized in that: The length of the straight pipe is greater than 10 cm, and holes with a diameter of 10-15 mm are drilled every 20-30 cm on the straight pipe.

9. The device for reducing the hardness of wastewater according to claim 1 or 2, characterized in that: The water distribution pipeline system includes a splicing pipe formed by splicing 2 straight pipes into an H shape, and multiple holes are opened on the splicing pipe.

10. The device for reducing the hardness of wastewater according to claim 9, characterized in that: Holes with a diameter of 10-15 mm are opened every 20-30 cm on the splicing pipe.

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