A device for removing hardness from desulfurization wastewater
By combining a coagulation tank, a flocculation tank, and an inclined plate sedimentation tank, and utilizing reagents and agitators, the problem of high hardness in desulfurization wastewater is solved, achieving efficient hardness removal and environmentally friendly treatment, which is suitable for chemical wastewater treatment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- XINJIANG TIANZHI CHENYE CHEM
- Filing Date
- 2025-06-30
- Publication Date
- 2026-07-10
AI Technical Summary
The high hardness of the desulfurization wastewater generated in the circulating fluidized bed boiler system leads to scaling in the system and affects stable operation.
A combined device consisting of a coagulation tank, a flocculation tank, an inclined plate sedimentation tank, and a neutralization tank is used. By adding agents such as magnesium sulfate, sodium hydroxide, sodium carbonate, coagulant aids, and flocculants, and combining them with the design of a stirrer and an inclined plate sedimentation tank, uniform mixing of the agents and sedimentation and flocculation are achieved, thereby reducing the hardness of the wastewater.
It effectively reduces the hardness of desulfurization wastewater to below 300 mg/L, uses inexpensive and non-toxic reagents, and has a simple structure that is easy to automate, reducing manual operation and avoiding environmental pollution.
Smart Images
Figure CN224478018U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of chemical wastewater treatment technology, and relates to a device for removing hardness from desulfurization wastewater. Background Technology
[0002] During the operation of a circulating fluidized bed boiler system, a certain amount of desulfurization wastewater is generated during the removal of sulfur dioxide from the flue gas. This wastewater is characterized by extremely high hardness (approximately 3000 mg / L based on calcium carbonate content). Even after treatment in a triple desulfurization wastewater treatment tank, the hardness remains largely unremoved. If this wastewater enters the biological treatment system or ammonia extraction system, it will cause scaling, preventing subsequent processes from operating stably for extended periods. Utility Model Content
[0003] To effectively solve the existing problems, this utility model provides a device for removing hardness from desulfurization wastewater that has a relatively simple structure and obvious hardness removal effect.
[0004] The objective of this utility model is achieved through the following technical solution:
[0005] An apparatus for removing hardness from desulfurization wastewater includes a coagulation tank I, a coagulation tank II, a flocculation tank, a plug flow lift tank, an inclined plate sedimentation tank, and a neutralization tank. Coagulation tank I is connected to a wastewater inlet pipeline at its bottom and to coagulation tank II at its top via an overflow outlet. The bottom of coagulation tank II is connected to the guide tube of the flocculation tank via a guide pipe, and its other bottom side is connected to the plug flow lift tank via an opening. The top of the plug flow lift tank is connected to the inclined plate sedimentation tank via an overflow outlet. The other top side of the inclined plate sedimentation tank is connected to the neutralization tank via an overflow outlet. The bottom of the neutralization tank is connected to an outer jacket via an opening, and an opening at the top of the outer jacket is connected to an effluent pipeline. A sludge collection and reuse pipeline is provided on the side of the conical thickening zone at the bottom of the inclined plate sedimentation tank and connected to the flocculation tank.
[0006] Furthermore, each of the coagulation tank I, coagulation tank II, flocculation tank, inclined plate sedimentation tank, and neutralization tank is equipped with a corresponding agitator; sludge collection pipelines are respectively installed at the bottom of the coagulation tank I, coagulation tank II, flocculation tank, plug flow lifting tank, inclined plate sedimentation tank, and neutralization tank.
[0007] Furthermore, the inclined plate sedimentation tank is equipped with an inclined tube plate at the top, which is composed of parallel tubes; the inclined plate sedimentation tank is divided into four parts: a pre-sedimentation zone, a sedimentation zone, a bottom conical concentration zone, and a top water collection zone.
[0008] Furthermore, the bottom of the inclined plate sedimentation tank is a conical slope structure, and the angle between the slope and the horizontal plane is 10° to 20°.
[0009] Furthermore, the angle between the inclined plate of the inclined plate sedimentation tank and the horizontal plane is 30° to 45°.
[0010] Furthermore, the agitators of coagulation tank I, coagulation tank II, and neutralization tank are all double agitators with the same size upper and lower blades; the agitator of the flocculation tank is a single agitator with the blade installed at the center of the guide tube, and its size is smaller than the inner diameter of the guide tube; the agitator of the inclined plate sedimentation tank is a double agitator with the upper blade installed above the bottom slope and below the inclined tube plate, and its size is larger than the inner diameter of the upper opening of the bottom conical concentration zone but smaller than the inner diameter of the inclined plate sedimentation tank; the lower blade is installed at the center of the bottom conical concentration zone, and its size is smaller than the inner diameter of the middle part of the bottom conical concentration zone.
[0011] Furthermore, the flocculation tank is equipped with a guide pipe and a guide cylinder, and is divided into two reaction units: a slow stirring reaction zone and a plugging reaction zone.
[0012] Furthermore, the guide tube inside the flocculation tank has a variable diameter shape, with the lower part being narrower and the lower part being wider. The lower part is fixed to the bottom of the flocculation tank, and the upper opening is 2 / 3 to 3 / 4 of the height of the flocculation tank. The guide pipe is installed at the bottom of the guide tube, and its outer diameter is smaller than the inner diameter of the guide tube.
[0013] Furthermore, the bottom of the push-flow lifting pool is provided with a slope, and the angle between the slope and the horizontal plane is 45° to 60°.
[0014] Furthermore, magnesium sulfate solution is added to the wastewater inlet pipe, sodium hydroxide solution and sodium carbonate solution are added to the bottom of coagulation tank I, coagulant aid is added to the top of coagulation tank II, flocculant is added to the bottom of the flocculation tank guide tube, and sulfuric acid solution is added to the top of the neutralization tank.
[0015] Compared with the prior art, the advantages of this utility model are: (1) By setting up a flocculation tank, an inclined plate sedimentation tank and its stirring device, the reagents are mixed more evenly, while the effect of sedimentation flocculation and floc separation is enhanced, the hardness removal effect is better, and the hardness of the wastewater after hardness removal can be reduced to below 300mg / L; (2) The reagents used in the treatment process are all inexpensive and non-toxic, which will not affect the effect of subsequent treatment, and will not cause environmental pollution after discharge; (3) The overall structure of the device is relatively simple, and it can realize automatic control, with less manual operation and easy to get started. Attached Figure Description
[0016] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.
[0017] Figure 1 This is a structural diagram of the device of this utility model.
[0018] Figure 2 This is a structural diagram of the flocculation tank of this utility model.
[0019] Figure 3This is a structural diagram of the inclined plate sedimentation tank of this utility model.
[0020] Figure 1 In the diagram, 1 is coagulation tank I, 2 is coagulation tank II, 3 is flocculation tank, 4 is plug flow lift tank, 5 is inclined plate sedimentation tank, 6 is neutralization tank, 7 is neutralization tank agitator, 8 is inclined plate sedimentation tank agitator, 9 is flocculation tank agitator, 10 is coagulation tank II agitator, 11 is coagulation tank I agitator, A is wastewater inlet, B is magnesium sulfate solution, C is sodium hydroxide solution, D is sodium carbonate solution, E is coagulant aid, F is flocculant, and G is sulfuric acid solution.
[0021] Figure 2 In the diagram, 3.1 is the flow guide tube, 3.2 is the slow stirring reaction zone, 3.3 is the flow propulsion reaction zone, and 3.4 is the flow guide pipe.
[0022] Figure 3 In the diagram, 5.1 is the pre-sedimentation zone, 5.2 is the bottom conical concentration zone, 5.3 is the sedimentation zone, 5.4 is the top water collection zone, and 5.5 is the inclined tube plate. Detailed Implementation
[0023] The embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Example
[0024] Reference Figure 1 This embodiment provides a device for removing hardness from desulfurization wastewater, including a coagulation tank I1, a coagulation tank II2, a flocculation tank 3, a plug flow lift tank 4, an inclined plate sedimentation tank 5, and a neutralization tank 6. The bottom of the coagulation tank I1 is connected to the wastewater inlet A pipeline. A magnesium sulfate solution B with a mass fraction of 5% to 10% is added from the wastewater inlet A pipeline. In this embodiment, a sodium hydroxide solution C with a mass fraction of 20% to 32% and a sodium carbonate solution D with a mass fraction of 15% to 20% are added from the top of the coagulation tank I1, respectively. The top of coagulation tank I1 is connected to coagulation tank II2 via an overflow outlet. A 2%–5% (w / w) solution of coagulant aid E, polymeric alumina (PAC), is added from the top of coagulation tank II2. The bottom of coagulation tank II2 is connected to the guide tube 3.1 of flocculation tank 3 via a guide pipe 3.4, and on the other side of its bottom, it is connected to the plug flow lift tank 4 via an opening. The top of plug flow lift tank 4 is connected to inclined plate sedimentation tank 5 via an overflow outlet. The other side of the top of inclined plate sedimentation tank 5 is connected to neutralization tank 6 via an overflow outlet. A 15%–20% (w / w) sulfuric acid solution G is added from the top of neutralization tank 6. The bottom of neutralization tank 6 is connected to the outer jacket via an opening, and the upper part of the outer jacket is connected to the effluent pipeline. The side of the conical concentration zone 5.2 at the bottom of inclined plate sedimentation tank 5 is equipped with a sludge collection and reuse pipeline, which is connected to flocculation tank 3.
[0025] Each of the following tanks—coagulation tank I, coagulation tank II, flocculation tank 3, plug flow lift tank 4, inclined plate sedimentation tank 5, and neutralization tank 6—is equipped with a corresponding agitator, and each has a sludge collection pipeline at its bottom. The agitators 11 in coagulation tank I, 10 in coagulation tank II, and 7 in neutralization tank are double-bladed agitators with identical upper and lower blade dimensions. The agitator 9 in the flocculation tank is a single-bladed agitator, with the blade installed at the center of the guide tube 3.1, and its size smaller than the inner diameter of the guide tube 3.1. The agitator 8 in the inclined plate sedimentation tank is a double-bladed agitator. The upper blade is installed above the bottom slope and below the inclined tube plate 5.5, and its size is larger than the inner diameter of the upper opening of the bottom conical thickening zone 5.2 but smaller than the inner diameter of the inclined plate sedimentation tank 5. The lower blade is installed at the center of the bottom conical thickening zone 5.2, and its size is smaller than the inner diameter of the middle part of the bottom conical thickening zone 5.2.
[0026] The bottom of the push-flow lifting tank 4 is provided with a slope, and the angle between the slope and the horizontal plane is 60°.
[0027] Reference Figure 2 The flocculation tank 3 is equipped with a guide pipe 3.4 and a guide cylinder 3.1, dividing the flocculation tank 3 into two reaction units: a slow-stirring reaction zone 3.2 and a plugging reaction zone 3.3. The guide cylinder 3.1 has a variable diameter shape, narrower at the top and wider at the bottom. The lower part is fixed to the bottom of the flocculation tank 3, and the upper opening is 2 / 3 to 3 / 4 of the height of the flocculation tank 3. The guide pipe 3.4 is installed at the bottom of the guide cylinder 3.1, and its outer diameter is smaller than the inner diameter of the guide cylinder 3.1. A flocculant F polyacrylamide (PAM) solution with a mass fraction of 2% to 5% is added from the bottom of the guide cylinder 3.1 in the flocculation tank 3.
[0028] Reference Figure 3 The inclined plate sedimentation tank 5 has an inclined tube plate 5.5 installed at the top, which is composed of parallel tubes. The angle between the inclined tube plate 5.5 and the horizontal plane is 45°. The inclined plate sedimentation tank 5 is divided into four parts: a pre-sedimentation zone 5.1, a sedimentation zone 5.2, a bottom conical concentration zone 5.2, and a top water collection zone 5.4. The bottom of the inclined plate sedimentation tank 5 has a conical slope structure, and the angle between the slope and the horizontal plane is 10°.
[0029] As a further improvement, the angle between the bottom conical slope of the inclined plate sedimentation tank 5 and the horizontal plane can be 15°, the angle between the inclined tube plate 5.5 of the inclined plate sedimentation tank 5 and the horizontal plane is 30°, and the angle between the bottom slope of the push flow lifting tank and the horizontal plane is 45°.
[0030] As a further improvement, the angle between the bottom conical slope of the inclined plate sedimentation tank 5 and the horizontal plane can be 20°, the angle between the inclined tube plate 5.5 of the inclined plate sedimentation tank 5 and the horizontal plane is 40°, and the angle between the bottom slope of the plug flow lifting tank and the horizontal plane is 50°.
[0031] The following section, in conjunction with the process steps and the system structure described in this utility model, elaborates on the process flow and principle of this utility model for treating desulfurization wastewater.
[0032] Magnesium sulfate solution B is added to wastewater inlet A to convert silicate ions in the wastewater into magnesium silicate precipitate. The reaction equation is as follows:
[0033]
[0034] The converted wastewater enters from the bottom of coagulation tank I1, and sufficient amounts of sodium hydroxide solution C and sodium carbonate solution D are added to raise the pH value to above 12. Under rapid stirring, the reaction proceeds fully, and calcium and magnesium ions in the wastewater are converted into magnesium hydroxide precipitate and calcium carbonate precipitate. The reaction equation is as follows:
[0035]
[0036] The converted wastewater enters coagulation tank II2 through the top overflow outlet; coagulant E is added to coagulation tank II2 and rapidly stirred to ensure thorough mixing with the wastewater, causing the sediment to coagulate into small flocs. The converted wastewater then enters the guide tube 3.1 of flocculation tank 3 through the bottom guide pipe 3.4; flocculant F and recycled sludge from subsequent processes are added from the bottom of the guide tube 3.1 of flocculation tank 3. Slow stirring generates eddies in the guide tube 3.1, causing the wastewater, flocculant F, and recycled sludge to mix evenly before flowing into the push tube outside the guide tube 3.1. The flow reaction zone 3.3 primarily utilizes a plug flow mechanism to slow down flocculation and disperse low energy to ensure the flocs become larger and denser, resulting in larger flocs. The converted wastewater enters the plug flow lift tank 4 through the bottom opening of the flocculation tank 3. In the plug flow lift tank 4, the wastewater is guided upwards along the slope, reducing floc settling. The flocs further react and enlarge during the upward flow and lift process, entering the inclined plate sedimentation tank 5 through the top overflow outlet. The inclined plate sedimentation tank 5 is designed based on the shallow pool sedimentation theory. In the high-efficiency combined sedimentation tank, in the pre-sedimentation zone 5.1, easily settled flocs quickly settle to the bottom. Small flocs that do not settle or are difficult to settle are captured by the upper inclined tube plate 5.5 and slide down to the sedimentation zone 5.3 under gravity. The slow water flow in the sedimentation zone 5.3 is highly conducive to floc settling to the bottom. The flocs accumulated at the bottom are agitated by the stirring blades and slide down the conical slope to the bottom conical concentration zone 5.2. The clear water after floc separation rises along the inclined tube plate 5.5 and flows into the top collection zone 5.4. Most of the sludge generated by the floc aggregation in the bottom conical concentration zone 5.2 is discharged from the discharge pipeline at the bottom of the cone, and a small portion is collected from the side of the cone and reused in the flocculation tank 3 to provide crystal nuclei for floc formation. The clear water in the top collection zone 5.4 enters the neutralization tank 6 through the overflow port on the other side of the top. A certain amount of sulfuric acid solution G is added to the neutralization tank 6 and stirred to neutralize the excess alkali, so that the pH value of the wastewater is maintained between 6 and 9. The neutralized wastewater enters the outer jacket through the bottom opening and is then sent to the output pipeline to the subsequent treatment section through the upper opening.
[0037] It should be noted that: (1) The sedimentation efficiency is only a function of the surface area of the sedimentation tank and is not related to the water depth. When the volume of the sedimentation tank is constant, the shallower the tank, the higher the sedimentation efficiency. Therefore, if a larger amount of wastewater needs to be treated, the number or length of the inclined tubes needs to be increased to enhance the sedimentation efficiency; (2) In order to maintain the functional effect of the inclined tube plate 5.5 during long-term operation, it is necessary to backwash it regularly.
Claims
1. An apparatus for removing hardness from desulfurization wastewater, characterized in that: It includes a coagulation tank I, a coagulation tank II, a flocculation tank, a plug flow lift tank, an inclined plate sedimentation tank, and a neutralization tank. Coagulation tank I is connected to the wastewater inlet pipeline at its bottom and to coagulation tank II at its top via an overflow outlet. The bottom of coagulation tank II is connected to the guide tube of the flocculation tank via a guide pipe, and to the plug flow lift tank via an opening on the other side of its bottom. The top of the plug flow lift tank is connected to the inclined plate sedimentation tank via an overflow outlet. The other side of the top of the inclined plate sedimentation tank is connected to the neutralization tank via an overflow outlet. The bottom of the neutralization tank is connected to the outer jacket via an opening, and the upper part of the outer jacket is connected to the effluent pipeline. The side of the conical thickening zone at the bottom of the inclined plate sedimentation tank is equipped with a sludge collection and reuse pipeline connected to the flocculation tank.
2. The apparatus for removing hardness from desulfurization wastewater according to claim 1, characterized in that: Each of the coagulation tank I, coagulation tank II, flocculation tank, inclined plate sedimentation tank, and neutralization tank is equipped with a corresponding agitator; sludge collection pipelines are respectively installed at the bottom of the coagulation tank I, coagulation tank II, flocculation tank, plug flow lifting tank, inclined plate sedimentation tank, and neutralization tank.
3. The apparatus for removing hardness from desulfurization wastewater according to claim 1, characterized in that: The inclined plate sedimentation tank is equipped with an inclined tube plate at the top, which is composed of parallel tubes. The inclined plate sedimentation tank is divided into four parts: a pre-sedimentation zone, a sedimentation zone, a bottom conical concentration zone, and a top water collection zone.
4. The apparatus for removing hardness from desulfurization wastewater according to claim 3, characterized in that: The bottom of the inclined plate sedimentation tank has a conical slope structure, and the angle between the slope and the horizontal plane is 10° to 20°.
5. The apparatus for removing hardness from desulfurization wastewater according to claim 3, characterized in that: The angle between the inclined plate of the inclined plate sedimentation tank and the horizontal plane is 30° to 45°.
6. The apparatus for removing hardness from desulfurization wastewater according to claim 2, characterized in that: The agitators of the coagulation tank I, coagulation tank II, and neutralization tank are all double agitators with the same size upper and lower blades. The agitator in the flocculation tank is a single agitator blade, with the blade installed at the center of the guide tube and its size smaller than the inner diameter of the guide tube. The agitator in the inclined plate sedimentation tank is a double agitator blade, with the upper blade installed above the bottom slope and below the inclined tube plate, its size larger than the inner diameter of the upper opening of the bottom conical concentration zone and smaller than the inner diameter of the inclined plate sedimentation tank. The lower blade is installed at the center of the bottom conical concentration zone and its size smaller than the inner diameter of the middle part of the bottom conical concentration zone.
7. The apparatus for removing hardness from desulfurization wastewater according to claim 1, characterized in that: The flocculation tank is equipped with a guide pipe and a guide cylinder, and is divided into two reaction units: a slow stirring reaction zone and a plugging reaction zone.
8. The apparatus for removing hardness from desulfurization wastewater according to claim 7, characterized in that: The guide tube inside the flocculation tank has a variable diameter shape, narrower at the top and wider at the bottom. The lower part is fixed to the bottom of the flocculation tank, and the upper opening is 2 / 3 to 3 / 4 of the height of the flocculation tank. The guide pipe is installed at the bottom of the guide tube, and its outer diameter is smaller than the inner diameter of the guide tube.
9. The apparatus for removing hardness from desulfurization wastewater according to claim 1, characterized in that: The bottom of the push-flow lifting pool is provided with a slope, and the angle between the slope and the horizontal plane is 45° to 60°.