Desulfurization wastewater waste heat evaporation treatment system and method

Abstract

The invention relates to a desulfurization wastewater waste heat evaporation treatment system and method.The desulfurization wastewater waste heat evaporation treatment system comprises a wastewater tank, the wastewater tank is connected with one end of a desulfurization wastewater inlet pipeline, one end of an evaporation device water return pipeline and one end of a desulfurization wastewater outlet pipeline, an electric valve is arranged on the desulfurization wastewater inlet pipeline, and a slurry pump is arranged on the desulfurization wastewater outlet pipeline; a liquid level instrument is arranged in the waste water tank, the control system is in interlocking control with the electric valve, the slurry pump and the liquid level instrument, and the other end of the evaporation device water return pipeline is connected with the waste heat evaporation device. The method is simple in process, convenient to operate, low in investment and operation cost and extremely low in failure rate, and can reduce the flue gas temperature in the flue, reduce the working condition flue gas amount and reduce the energy consumption of a desulfurization system while realizing complete evaporation of the desulfurization wastewater.

Description

Technical Field

[0001] The present invention relates to a desulfurization wastewater treatment system and method, and in particular to a desulfurization wastewater waste heat evaporation treatment system and method used in desulfurization wastewater in the aluminum industry. Background Art

[0002] Sulfur dioxide is an important atmospheric pollutant. At present, the country's requirements for environmental protection are becoming increasingly stringent, and a number of standards and regulations have been issued, which clearly stipulate that the sulfur dioxide emission concentration of Class A and Class B enterprises shall not exceed 35mg / Nm 3 Therefore, the control of sulfur dioxide in the aluminum industry is very important.

[0003] The limestone-gypsum method is a commonly used sulfur dioxide treatment method in industry. It has the advantages of high desulfurization efficiency and strong adaptability. It is widely used in sulfur dioxide flue gas treatment. This technology uses limestone slurry to directly contact the flue gas to absorb sulfur dioxide in the flue gas. In this process, pollutants such as dust and chlorine in the flue gas are transferred to the slurry. As the desulfurization process proceeds, the Cl in the slurry - The salt substances are continuously concentrated, affecting the quality of gypsum and causing slurry poisoning. This is because the salt content increases, the ionic strength in the slurry increases, the solubility of calcium sulfite and calcium sulfate increases, and the slurry is inhibited from absorbing sulfur dioxide in the flue gas. It not only affects the desulfurization efficiency, but also causes the viscosity of the slurry to increase, making it difficult to dehydrate gypsum. Therefore, in order to ensure the normal operation of the desulfurization system, the quality of the desulfurization water must be guaranteed, and the discharge of desulfurization wastewater is essential.

[0004] Desulfurization wastewater is weakly acidic and contains a lot of suspended matter (ash, inert substances, calcium carbonate, gypsum, etc.), reducing inorganic salts (sulfites, nitrites, etc.), heavy metal ions, chlorides, fluorides, etc. At present, the main treatment method for desulfurization wastewater is chemical precipitation. Its main principle is to remove various impurities and heavy metals in desulfurization wastewater through various chemicals, and the treated water can meet the discharge standards. However, this process has the problems of long process, more equipment, and more operation and maintenance work. The aluminum industry produces less desulfurization wastewater. It is too complicated to set up a chemical precipitation process to treat wastewater, the cost is high, and a large amount of chemical sludge is generated. The high concentration of chloride ions in the water is not removed, and the treated water cannot enter the desulfurization system for reuse. In addition, the treatment methods of desulfurization wastewater also include reverse osmosis crystallization and flue evaporation technology. Among them, reverse osmosis crystallization is to separate salt through a membrane osmosis unit, and then separate salt crystallization through an evaporation crystallization method. Its advantages are that standard solid salt is obtained and the ash produced can be reused. The disadvantages are that the process technology is difficult and the investment is large. The flue evaporation technology is to spray wastewater into the high-temperature flue through a nozzle. The liquid evaporates rapidly under the action of high-temperature flue gas, and the pollutants in the wastewater are collected by the dust collector. The technical transformation cost is low, but due to excessive impurities such as chlorine in the wastewater, it is easy to cause flue corrosion and blockage, affecting the normal operation of the purification system. Especially for the electrolytic flue gas purification system, since the pollutants in the wastewater return to the electrolytic cell together with the fluorine-containing alumina, the long-term accumulation of pollutants will affect the normal operation of the electrolysis process and affect the product quality.

[0005] Therefore, in view of the current problems with desulfurization wastewater, there is an urgent need for a treatment process with low investment and operation costs, simple process, and no impact on the operation of the existing system. Summary of the invention

[0006] The purpose of the present invention is to provide a desulfurization wastewater waste heat evaporation treatment system and method in order to achieve complete evaporation of desulfurization wastewater.

[0007] To achieve the above-mentioned purpose, the present invention provides a desulfurization wastewater waste heat evaporation treatment system, comprising a wastewater tank, which is connected to a desulfurization wastewater inlet pipeline, an evaporation device return pipeline and one end of a desulfurization wastewater discharge pipeline, an electric valve is provided on the desulfurization wastewater inlet pipeline, a slurry pump is provided on the desulfurization wastewater discharge pipeline, a liquid level meter is provided in the wastewater tank, a control system is interlocked with the electric valve, the slurry pump and the liquid level meter, and the other end of the evaporation device return pipeline is connected to the waste heat evaporation device.

[0008] The waste heat evaporation device is shaped like a saddle. It includes a supporting frame, partitions are arranged between the supporting frames, and end plates are respectively arranged at both ends of the supporting frames. A spray system is arranged on the saddle-shaped arc formed by the supporting frame and the partitions, and the spray system is connected to the other end of the desulfurization wastewater discharge pipe.

[0009] The arc shape formed by the saddle-shaped waste heat evaporation device is the same as the appearance of the high-temperature smoke pipe, and the partition plate, the end plate and the supporting frame are treated with anti-corrosion.

[0010] The waste heat evaporation device is clamped on the high-temperature smoke pipe, and a waste water recovery tank is arranged below the waste heat evaporation device. The other end of the return pipe of the evaporation device is connected to the waste water recovery tank, and the height of the waste water recovery tank is higher than the top height of the waste water tank.

[0011] One end of the desulfurized wastewater inlet pipe and the evaporation device return pipe is arranged at the top of the wastewater tank; one end of the desulfurized wastewater discharge pipe is arranged at the bottom of the wastewater tank.

[0012] The lower part of the waste water tank is provided with an emptying pipe, and the emptying pipe is arranged below the desulfurization waste water discharge pipe.

[0013] The slurry pump is a variable frequency pump.

[0014] A treatment method for a waste heat evaporation treatment system for desulfurized wastewater, through interlocking control of a control system with a liquid level meter, a slurry pump and an electric valve, when the liquid level is low, the electric valve is opened to open the desulfurized wastewater to enter the pipeline, so that the desulfurized wastewater enters the wastewater tank, when the liquid level is high, the electric valve is closed to close the desulfurized wastewater to enter the pipeline, when the liquid level is below a high limit, the slurry pump is normally opened to send the desulfurized wastewater in the wastewater tank to a waste heat evaporation device, in which the flue gas waste heat is evaporated and utilized, part of the desulfurized wastewater is evaporated by high-temperature waste heat, and part of the desulfurized wastewater is returned to the wastewater tank through a return pipe of the evaporation device for cyclic spraying, when the liquid level reaches below a low limit, the slurry pump is interlocked with the control system to stop working, the electric valve is opened to replenish the desulfurized wastewater, and the cycle is repeated.

[0015] The waste heat evaporation device is connected to the high-temperature flue.

[0016] The high-temperature flue has good thermal conductivity, is not covered by thermal insulation materials, and can effectively transfer the waste heat of the flue gas.

[0017] Advantages and effects of the present invention: The present invention has a simple process, convenient operation, low investment and operation cost, and extremely low failure rate. The present invention does not affect the normal operation of the existing purification system. The present invention can achieve full evaporation of desulfurization wastewater and achieve zero discharge of desulfurization wastewater. While evaporating desulfurization wastewater, the present invention reduces the flue gas temperature, thereby reducing the flue gas flow rate under the working condition, can effectively protect the purification system and equipment after the high-temperature flue, and can effectively reduce the power consumption, water consumption and other energy consumption of the desulfurization system. The present invention can realize automatic control, improve the intelligence level of the system, reduce the work intensity of personnel, and improve the equipment operation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a system flow chart of the present invention.

[0019] Figure 2 It is a schematic diagram of the waste heat evaporation device of the present invention.

[0020] In the figure: 1. Electric valve; 2. Wastewater tank; 3. Slurry pump; 4. Waste heat evaporation device; 5. Control system; 6. Desulfurization wastewater inlet pipeline; 7. Evaporation device return pipeline; 8. Desulfurization wastewater discharge pipeline; 9. Liquid level meter; 10. Support frame; 11. Partition; 12. End plate; 13. Spray pipe; 14. Wastewater recovery tank; 15. Emptying pipeline. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] As shown in the figure, a waste heat evaporation treatment system for desulfurized wastewater of the present invention comprises a wastewater tank 2, which is connected to a desulfurized wastewater inlet pipe 6, an evaporation device return pipe 7 and one end of a desulfurized wastewater discharge pipe 8, an electric valve 1 is provided on the desulfurized wastewater inlet pipe 6, a slurry pump 3 is provided on the desulfurized wastewater discharge pipe 8, a liquid level meter is provided in the wastewater tank 2, a control system 5 is interlocked with the electric valve 1, the slurry pump 3 and the liquid level meter 9, and the other end of the evaporation device return pipe 7 is connected to a waste heat evaporation device 4. The waste heat evaporation device 4 is saddle-shaped, and comprises a plurality of support frames 10, a partition 11 is provided between adjacent support frames 10, and end plates 12 are provided at both ends of the support frames 10, and three spray pipes 13 are provided on the saddle-shaped arc formed by the support frames 10 and the partition 11, and the three spray pipes 13 are connected to the other end of the desulfurized wastewater discharge pipe 8. The arc formed by the saddle-shaped waste heat evaporation device 4 is the same as the shape of the high-temperature smoke pipe, so that the inside of the waste heat evaporation device 4 fits the high-temperature smoke pipe, and can better exchange heat with the high-temperature smoke pipe. Under the action of the high-temperature flue, the desulfurization wastewater can be evaporated quickly to remove the water in the desulfurization wastewater, and there is no residual water discharge in the whole process. Since the desulfurization wastewater is weakly acidic and contains a large amount of salt substances, in order to ensure the stable operation of the system, it is necessary to set anti-corrosion on the surface of the partition, end plate, support frame, high-temperature flue and wastewater recovery tank that are in contact with the desulfurization wastewater. The anti-corrosion method includes using stainless steel or spraying with anti-corrosion materials.

[0023] The desulfurization wastewater is introduced into the spray pipe 13 through the slurry pump 3. The spray pipe 13 sprays the desulfurization wastewater on the partition 11 as much as possible through the nozzle or pipe hole to effectively exchange heat and evaporate water. The end plate 12 is used to ensure that the desulfurization wastewater will not be sprayed to the outside of the system to cause secondary pollution and other problems. The support frame 10 is used to ensure the overall stability of the waste heat evaporation device.

[0024] A wastewater recovery tank 14 is provided below the waste heat evaporation device 4, and the other end of the evaporation device return pipe 7 is connected to the wastewater recovery tank 14, and the height of the wastewater recovery tank 14 is higher than the top height of the wastewater tank 2. The desulfurization wastewater inlet pipe 6 and one end of the evaporation device return pipe 7 are provided at the top of the wastewater tank 2; one end of the desulfurization wastewater discharge pipe 8 is provided at the bottom of the wastewater tank; an emptying pipe 15 is provided at the bottom of the wastewater tank 2, and the emptying pipe 15 is provided below the desulfurization wastewater discharge pipe 8. When performing maintenance, the desulfurization wastewater is discharged from the wastewater tank 2 through the emptying pipe 15.

[0025] A treatment method for a waste heat evaporation treatment system for desulfurized wastewater, through the interlocking control of a control system 5, a liquid level meter 9, a slurry pump 3 and an electric valve 1, when the liquid level is low, the electric valve 1 is opened to open the desulfurized wastewater to enter the pipeline 6, so that the desulfurized wastewater enters the wastewater tank 2, when the liquid level is high, the electric valve 1 is closed to close the desulfurized wastewater to enter the pipeline 6, when the liquid level is below the upper limit, the slurry pump 3 is normally opened to send the desulfurized wastewater in the wastewater tank 2 to the waste heat evaporation device 4, in which the flue gas waste heat is evaporated and utilized, part of the desulfurized wastewater is evaporated by the high-temperature waste heat, and part of the desulfurized wastewater is returned to the wastewater tank 2 through the evaporation device return pipe 7 for cyclic spraying, when the liquid level reaches below the lower limit, the slurry pump 3 is interlocked by the control system 5 to stop working, and the electric valve 1 is opened to supplement the desulfurized wastewater, and the cycle is repeated. The slurry pump is a variable frequency pump, and the water volume and wastewater supply in the wastewater tank 2 can be automatically controlled by the control system 5, thereby effectively controlling the cyclic spraying desulfurized wastewater volume and evaporation volume.

[0026] The high-temperature flue has good thermal conductivity, is not covered by thermal insulation materials, and can effectively transfer the waste heat of the flue gas.

[0027] The present invention utilizes the waste heat on the outer surface of the flue gas pipe to evaporate water in the desulfurized wastewater, and the salts remaining in the waste heat evaporation device are cleaned regularly. Since the waste heat evaporation device is clamped on the high-temperature flue gas pipe, it can be easily disassembled.

[0028] For example, the high-temperature flue in this embodiment is the electrolytic flue gas collection flue before the dry adsorption dust collector, and the temperature is about 120° C. Under the action of the high-temperature flue, water can evaporate quickly.

[0029] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A desulfurization wastewater waste heat evaporation treatment system, characterized in that It includes a wastewater tank, which is connected to the desulfurization wastewater inlet pipe, the evaporation device return pipe and one end of the desulfurization wastewater discharge pipe. An electric valve is provided on the desulfurization wastewater inlet pipe, a slurry pump is provided on the desulfurization wastewater discharge pipe, a liquid level meter is provided in the wastewater tank, the control system is interlocked with the electric valve, the slurry pump and the liquid level meter, and the other end of the evaporation device return pipe is connected to the waste heat evaporation device.

2. A desulfurization wastewater waste heat evaporation treatment system according to claim 1, characterized in that The waste heat evaporation device is shaped like a saddle. It includes a supporting frame, partitions are arranged between the supporting frames, and end plates are respectively arranged at both ends of the supporting frames. A spray system is arranged on the saddle-shaped arc formed by the supporting frame and the partitions, and the spray system is connected to the other end of the desulfurization wastewater discharge pipe.

3. A desulfurization wastewater waste heat evaporation treatment system according to claim 2, characterized in that The arc formed by the saddle-shaped waste heat evaporation device is the same as the appearance of the high-temperature smoke pipe, and the partitions, end plates and supporting frames are treated with anti-corrosion.

4. A desulfurization wastewater waste heat evaporation treatment system according to any one of claims 1 to 3, characterized in that The waste heat evaporation device is clamped on the high-temperature smoke pipe. A waste water recovery tank is provided below the waste heat evaporation device. The other end of the return pipe of the evaporation device is connected to the waste water recovery tank. The height of the waste water recovery tank is higher than the top height of the waste water tank.

5. A desulfurization wastewater waste heat evaporation treatment system according to claim 1, characterized in that One end of the desulfurized wastewater inlet pipe and the evaporation device return pipe is arranged at the top of the wastewater tank; one end of the desulfurized wastewater discharge pipe is arranged at the bottom of the wastewater tank.

6. A desulfurization wastewater waste heat evaporation treatment system according to claim 1 or 5, characterized in that The lower part of the waste water tank is provided with an emptying pipe, and the emptying pipe is arranged below the desulfurization waste water discharge pipe.

7. The method for treating a desulfurization wastewater waste heat evaporation treatment system according to claim 1, characterized in that The slurry pump is a variable frequency pump.

8. A treatment method for a waste heat evaporation treatment system for desulfurization wastewater, characterized in that Through the interlocking control of the control system, the liquid level meter, the slurry pump and the electric valve, when the liquid level is low, the electric valve is opened to allow the desulfurization wastewater to enter the pipeline, so that the desulfurization wastewater enters the wastewater tank; when the liquid level is high, the electric valve is closed to close the desulfurization wastewater from entering the pipeline; when the liquid level is below the upper limit, the slurry pump is opened normally to send the desulfurization wastewater in the wastewater tank to the waste heat evaporation device, where the flue gas waste heat is evaporated and utilized; part of the desulfurization wastewater is evaporated by the high-temperature waste heat, and part of the desulfurization wastewater is returned to the wastewater tank through the return pipe of the evaporation device for circulating spraying; when the liquid level reaches below the lower limit, the slurry pump is interlocked with the control system to stop working, and the electric valve is opened to replenish the desulfurization wastewater, and the cycle is repeated.

9. The method for treating a desulfurization wastewater waste heat evaporation treatment system according to claim 8, characterized in that The waste heat evaporation device is connected to the high-temperature flue.

10. The method for treating a desulfurization wastewater waste heat evaporation treatment system according to claim 9, characterized in that The high-temperature flue has good thermal conductivity, is not covered by thermal insulation materials, and can effectively transfer the waste heat of the flue gas.

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