Desulfurization wastewater zero discharge system utilizing flue gas to directly spray and concentrate

Abstract

The utility model relates to the technical field of environmental protection equipment, and provides a desulfurization wastewater zero discharge system utilizing flue gas to directly spray and concentrate, which comprises a boiler, an evaporation flue, a desulfurization tower, a sedimentation unit and a tail water treatment unit, a sprayer is arranged in the evaporation flue; the sprayer is communicated with the desulfurization tower through a water inlet pipe and is used for atomizing and spraying desulfurization wastewater in the desulfurization tower into the evaporation flue for concentration; the evaporation flue is provided with a first circulating pipe; a first pump body is arranged on the first circulating pipe; the first pump body is used for spraying desulfurization wastewater and precipitates at the bottom of the evaporation flue into the evaporation flue again for concentration. The evaporation rate is improved by specially arranging the evaporation flue and circularly spraying the desulfurization wastewater in the evaporation flue, so that the treatment capacity of the desulfurization wastewater is improved; and meanwhile, the problem of blockage caused by accumulation of solids such as crystals and salts in the evaporation flue can be solved.

Description

Technical Field

[0001] This utility model relates to the field of environmental protection equipment technology, specifically a zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas. Background Technology

[0002] In the power generation industry, coal-fired power generation still accounts for the majority. Wet flue gas desulfurization (FGD) technology has become the mainstream process for FGD in my country's coal-fired power plants due to its advantages such as high desulfurization efficiency, fast reaction speed, and high desulfurizing agent utilization. The desulfurization wastewater from the end of coal-fired power plants has high floating matter content, high salt content, high hardness, and strong corrosiveness, making it difficult to reuse directly. Therefore, how to treat desulfurization wastewater has become a top priority.

[0003] Flue gas evaporation technology refers to spraying wastewater into the flue between the air preheater and the dust collector, using the hot flue gas to completely evaporate the wastewater, and converting the pollutants in the wastewater into solids such as crystals or salts. However, if all the desulfurization wastewater is evaporated through the main flue, the purpose of complete evaporation may not be achieved.

[0004] CN113185045A discloses a device for zero-discharge flue gas evaporation of desulfurization wastewater and synergistic removal of SO3 / HCl. The device includes an SCR denitrification reactor, an air preheater, a dust collector, and a desulfurization tower connected sequentially to the main flue. It also includes a rotary atomizing dryer, a triple-unit container, a mixing tank, a wastewater lift pump, a high-level feed tank, a spraying device, and a salt recovery and treatment system. This patent simultaneously employs main flue evaporation and bypass spray drying evaporation to compensate for incomplete evaporation in the main flue. However, while this system effectively reduces the amount of desulfurization wastewater generated, it requires significant equipment investment, has a very lengthy process flow, and still suffers from problems such as main flue blockage and sprayer blockage.

[0005] Therefore, the technical problem to be solved in this case is: how to solve the problem of insufficient evaporation capacity in the main flue. Utility Model Content

[0006] To address the aforementioned technical problems, this utility model provides a zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas. By employing a specially designed evaporation flue and circulating the desulfurization wastewater within it, the evaporation rate is increased, thereby enhancing the treatment capacity of the desulfurization wastewater. Simultaneously, it also solves the problem of blockage caused by the accumulation of solids such as crystals and salts in the evaporation flue.

[0007] The technical solution of this utility model is as follows:

[0008] A zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas includes a boiler, an evaporation flue, a desulfurization tower, a settling unit, and a tailwater treatment unit; the boiler, evaporation flue, and desulfurization tower are sequentially connected through a main flue gas duct.

[0009] The evaporation flue is equipped with a sprayer; the sprayer is connected to the desulfurization tower through a water inlet pipe and is used to atomize and spray the desulfurization wastewater in the desulfurization tower into the evaporation flue for concentration.

[0010] The evaporation flue is provided with a first circulation pipe; a first pump body is provided on the first circulation pipe; one end of the first circulation pipe is connected to the bottom of the evaporation flue, and the other end of the first circulation pipe is connected to the sprayer; the first pump body is used to spray the desulfurization wastewater and sediment at the bottom of the evaporation flue back into the evaporation flue for concentration.

[0011] The settling unit is connected to the evaporation flue through a drain pipe; the drain pipe is used to transport the high-salt wastewater generated after the desulfurization wastewater in the evaporation flue is concentrated to the settling unit.

[0012] The settling unit is provided with an outlet pipe above it that is connected to the tailwater treatment unit, and a return pipe is provided below it that is connected to the inlet pipe.

[0013] In the above-mentioned zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas, the evaporation flue is also equipped with a second circulation pipe; a second pump body is installed on the second circulation pipe; one end of the second circulation pipe is connected to the bottom of the evaporation flue, and the other end of the second circulation pipe is connected to the sprayer; the second pump body is used to spray the desulfurization wastewater at the bottom of the evaporation flue back into the evaporation flue for concentration.

[0014] In the above-mentioned zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas, the sprayer includes a first spray pipe and a second spray pipe; the first spray pipe is connected to the first circulation pipe; and the second spray pipe is connected to the second circulation pipe.

[0015] In the aforementioned zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas, the first spray pipe is positioned below the flue gas duct, and the second spray pipe is positioned above the flue gas duct.

[0016] In the aforementioned zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas, the bottom of the evaporation flue gradually narrows.

[0017] In the aforementioned zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas, an inverted "V"-shaped diversion block is provided inside the evaporation flue.

[0018] In the above-mentioned zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas, the first circulation pipe and the second circulation pipe are provided on both sides of the diversion block.

[0019] In the above-mentioned zero-discharge system for desulfurization wastewater that utilizes direct spraying and concentration of flue gas, the tail gas treatment unit includes a water storage tank, a drying tower, and a dust collector connected in sequence; the water storage tank is connected to the sedimentation unit through the water outlet pipe.

[0020] In the above-mentioned zero-discharge system for desulfurization wastewater concentrated by direct spraying of flue gas, the settling unit includes a lime slurry tank and a clarification tank; the clarification tank is connected to the lime slurry tank through a feed pipe; the input end of the clarification tank is connected to the evaporation flue through the sewage pipe; the effluent pipe is provided above the clarification tank; and the sewage return pipe is provided below the clarification tank.

[0021] The aforementioned zero-discharge system for desulfurization wastewater, which utilizes direct spraying and concentration of flue gas, also includes a vacuum belt dewatering machine; the vacuum belt dewatering machine is located at the conveying path of the inlet pipe.

[0022] Compared with the prior art, the beneficial effects of this utility model are at least as follows:

[0023] 1. By atomizing desulfurization wastewater, this invention can directly utilize the heat of flue gas for evaporation and concentration, which is more energy-efficient than mechanical vapor recompression (MVR) technology.

[0024] 2. By spraying desulfurization wastewater, the flue gas is cooled simultaneously during transportation, thereby reducing the load on the desulfurization tower.

[0025] 3. The process flow is short, the equipment investment is relatively small, and the treatment capacity of desulfurization wastewater can be met at the same time. Attached Figure Description

[0026] Figure 1 This is a simplified flowchart of Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the pipe connection of the evaporation flue in Embodiment 1 of this utility model.

[0028] The correspondence between the labels in the diagram is as follows:

[0029] 1. Boiler; 2. Evaporation flue; 3. Desulfurization tower; 4. Lime slurry tank; 5. Clarifying tank; 6. Vacuum belt dewatering machine; 7. Water storage tank; 8. Drying tower; 9. Dust collector; 10. Main flue gas duct;

[0030] Water inlet pipe 101; first circulation pipe 102; second circulation pipe 103; sewage pipe 104; water outlet pipe 105; sewage return pipe 106; first pump body 110; second pump body 120; first spray pipe 201; second spray pipe 202. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] It should be noted that, in order to concisely introduce the technical solution of this utility model, detailed descriptions of some pumps are omitted below, based on techniques well known in the art.

[0033] Example 1

[0034] refer to Figure 1 A zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas includes a boiler 1, an evaporation flue 2, a desulfurization tower 3, a settling unit, and a tailwater treatment unit. The boiler 1, the evaporation flue 2, and the desulfurization tower 3 are sequentially connected through a main flue gas duct 10, so that the high-temperature flue gas of 100-150°C in the boiler 1 is directly transported to the desulfurization tower 3 through the evaporation flue 2. In other embodiments, a dust collector 9 can also be added at the rear end of the boiler 1 to remove fly ash from the flue gas.

[0035] In this embodiment, a sprayer is installed inside the evaporation flue 2; and the sprayer is connected to the desulfurization tower 3 through a water inlet pipe 101, so that the desulfurization wastewater in the desulfurization tower 3 can be atomized and sprayed into the evaporation flue 2 through the water inlet pipe 101 for concentration; preferably, in this embodiment, the sprayer includes a first spray pipe 201 and a second spray pipe 202 with multiple atomizing nozzles; the water inlet pipe 101 is connected to the first spray pipe 201;

[0036] In the conveying path of this embodiment, the evaporation flue 2 is provided with a first circulation pipe 102; a first pump body 110 is provided on the first circulation pipe 102. One end of the first circulation pipe 102 is connected to the bottom of the evaporation flue 2, and the other end of the first circulation pipe 102 is connected to the first spray pipe 201. Therefore, when high-temperature flue gas is conveyed into the evaporation flue 2, and the processing volume cannot complete the evaporation of all desulfurization wastewater by sequential spraying, the desulfurization wastewater at the bottom of the evaporation flue 2 can be sprayed back into the evaporation flue 2 for concentration under the action of the first pump body 110. Preferably, in this embodiment, the first pump body 110 is a pulse suspension pump. Therefore, the first pump body 110 also undertakes the task of avoiding the problem of a large amount of sediment at the bottom of the evaporation flue 2 under long-term use, so that the desulfurization wastewater in the evaporation flue 2 remains flowing and suspended, and does not settle.

[0037] In the conveying path of this embodiment, the evaporation flue 2 is also provided with a second circulation pipe 103; a second pump body 120 is provided on the second circulation pipe 103; one end of the second circulation pipe 103 is connected to the bottom of the evaporation flue 2, and the other end of the second circulation pipe 103 is connected to the second spray pipe 202; the second pump body 120 is used to spray the desulfurization wastewater at the bottom of the evaporation flue 2 back into the evaporation flue 2 for concentration.

[0038] The first spray pipe 201 is connected to the first circulation pipe 102; the second spray pipe 202 is connected to the second circulation pipe 103. Similarly, the function of the second circulation pipe 103 is similar to that of the first circulation pipe 102. More preferably, the first spray pipe 201 is arranged below the flue gas duct; the second spray pipe 202 is arranged above the flue gas duct. In this preferred configuration, the desulfurization wastewater is evenly dispersed throughout the evaporation flue 2, allowing the high-temperature flue gas to quickly evaporate and concentrate the desulfurization wastewater into high-salt wastewater, significantly improving evaporation efficiency and treatment capacity.

[0039] In this embodiment, the settling unit is connected to the evaporation flue 2 via a drain pipe 104; the drain pipe 104 is used to transport the high-salt wastewater generated after the desulfurization wastewater in the evaporation flue 2 is concentrated to the settling unit.

[0040] Specifically, the settling unit includes a lime slurry tank 4 and a clarifier tank 5. The clarifier tank 5 is connected to the lime slurry tank 4 via a feed pipe. The input end of the clarifier tank 5 is connected to the evaporation flue 2 via a drain pipe 104. The clarifier tank 5 has an outlet pipe 105 above it and a return pipe 106 below it. A certain amount of lime slurry is added to the clarifier tank 5 through the lime slurry tank 4 to adjust the pH value of the high-salt wastewater to a slightly acidic level. Then, under the action of the clarifier tank 5, the solids and liquids are effectively separated. Preferably, the clarifier tank 5 in this embodiment is a high-efficiency cyclone clarifier. Through the high-speed rotating vortex, under the action of centrifugal force, the larger solids are pushed against the pipe wall and deposited. They are then atomized again by the return pipe 106 and input into the evaporation flue 2, while the clean liquid is output to the tailwater treatment unit through the outlet pipe 105 above it.

[0041] More specifically, both the sewage pipe 104 and the first circulation pipe 102 are equipped with gate valves. In actual application, the system can discharge sediment into the settling unit by opening the gate valve of the sewage pipe 104 after a certain period of operation.

[0042] As a preferred embodiment, the system also includes a vacuum belt dewatering machine 6; the vacuum belt dewatering machine 6 is located at the conveying path of the inlet pipe 101; after the high-efficiency cyclone clarifier passes through the return pipe 106, it first outputs to the vacuum belt dewatering machine 6. Under the action of the vacuum belt dewatering machine 6, the gypsum slurry is separated and dewatered, and the liquid passes through the filter cloth of the vacuum belt dewatering machine 6 and enters the inlet pipe 101, while the separated desulfurized gypsum remains on the surface of the filter cloth for recycling. Similarly, in this system, the desulfurization wastewater in the desulfurization tower 3 will also first pass through the vacuum belt dewatering machine 6 before entering the inlet pipe 101, thereby avoiding damage to the sprayer caused by the presence of excessively large solid particles in the inlet pipe 101.

[0043] In this embodiment, the exhaust gas treatment unit includes a water storage tank 7, a drying tower 8, and a dust collector 9 connected in sequence; the water storage tank 7 is connected to the settling unit through the water outlet pipe 105.

[0044] Specifically, in this embodiment, the water storage tank 7 is equipped with a stirrer to prevent the accumulation of a small amount of desulfurized gypsum particles in the tailwater; then, the tailwater in the water storage tank 7 is transported to the drying tower 8 to remove water and decompose into solids such as crystals or salts, and finally removed by the dust collector 9, preferably an electrostatic dust collector 9.

[0045] In practical applications, the bottom of the evaporation flue 2 gradually narrows, that is, the bottom of the evaporation flue 2 is tilted downward to avoid the accumulation of deposits at the bottom of the evaporation flue 2.

[0046] In this embodiment, preferably, the evaporation flue 2 is provided with an inverted "V"-shaped diversion block 21. (Reference) Figure 2 More preferably, the first circulation pipe 102 and the second circulation pipe 103 are provided on both sides of the diversion block 21. In this preferred embodiment, the sediment is transported along the inclined surface of the diversion block 21 to the first circulation pipe 102 and the second circulation pipe 103 on both sides, and continuously circulated in the manner mentioned above under the action of their respective pumps, thereby further improving the evaporation efficiency and processing capacity.

[0047] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements or modifications can be made without departing from the principle of the present utility model, and these improvements or modifications should also be considered within the protection scope of the present utility model.

Claims

1. A zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas, characterized in that, It includes a boiler, an evaporation flue, a desulfurization tower, a settling unit, and a tailwater treatment unit; the boiler, evaporation flue, and desulfurization tower are connected in sequence through a main flue gas duct; The evaporation flue is equipped with a sprayer; the sprayer is connected to the desulfurization tower through a water inlet pipe and is used to atomize and spray the desulfurization wastewater in the desulfurization tower into the evaporation flue for concentration. The evaporation flue is provided with a first circulation pipe; a first pump body is provided on the first circulation pipe; one end of the first circulation pipe is connected to the bottom of the evaporation flue, and the other end of the first circulation pipe is connected to the sprayer; the first pump body is used to spray the desulfurization wastewater and sediment at the bottom of the evaporation flue back into the evaporation flue for concentration. The settling unit is connected to the evaporation flue through a drain pipe; the drain pipe is used to transport the high-salt wastewater generated after the desulfurization wastewater in the evaporation flue is concentrated to the settling unit. The settling unit is provided with an outlet pipe above it that is connected to the tailwater treatment unit, and a return pipe is provided below it that is connected to the inlet pipe.

2. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas as described in claim 1, characterized in that, The evaporation flue is also equipped with a second circulation pipe; a second pump body is installed on the second circulation pipe; one end of the second circulation pipe is connected to the bottom of the evaporation flue, and the other end of the second circulation pipe is connected to the sprayer; the second pump body is used to spray the desulfurization wastewater at the bottom of the evaporation flue back into the evaporation flue for concentration.

3. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 2, characterized in that, The sprayer includes a first spray pipe and a second spray pipe; the first spray pipe is connected to the first circulation pipe; and the second spray pipe is connected to the second circulation pipe.

4. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 3, characterized in that, The first spray pipe is arranged below the flue gas duct; the second spray pipe is arranged above the flue gas duct.

5. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 2, characterized in that, The bottom of the evaporation flue gradually narrows.

6. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 5, characterized in that, The evaporation flue is equipped with an inverted "V" shaped diversion block.

7. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 6, characterized in that, The first circulation pipe and the second circulation pipe are provided on both sides of the diversion block.

8. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 1, characterized in that, The wastewater treatment unit includes a water storage tank, a drying tower, and a dust collector connected in sequence; the water storage tank is connected to the sedimentation unit through the water outlet pipe.

9. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 1, characterized in that, The settling unit includes a lime slurry tank and a clarification tank; the clarification tank is connected to the lime slurry tank through a feed pipe; the input end of the clarification tank is connected to the evaporation flue through the drain pipe; the effluent pipe is provided above the clarification tank; and the wastewater return pipe is provided below the clarification tank.

10. The zero-discharge system for desulfurization wastewater using direct spraying and concentration of flue gas according to claim 1, characterized in that, It also includes a vacuum belt dewatering machine; the vacuum belt dewatering machine is located at the conveying path of the water inlet pipe.

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