A three-effect vacuum concentration treatment system for alkaline tail gas

Abstract

The application relates to the technical field of tail gas treatment, in particular to a three-effect vacuum concentration treatment system for alkaline tail gas. The system comprises a three-effect evaporation device, a heat exchanger, a first water circulation pipeline and a vacuum pump device. The first end of the heat exchanger is connected with the tail gas output end of the three-effect evaporation device, the second end of the heat exchanger is connected with the input end of a condensate storage device, the third end of the heat exchanger is connected with the first end of the vacuum pump device, and the first water circulation pipeline penetrates through the fourth end and the fifth end of the heat exchanger. When the three-effect evaporation device generates alkaline tail gas, the alkaline tail gas is indirectly condensed through the first water circulation pipeline, the obtained condensate is transported to the condensate storage device, and the non-condensable gas is extracted to the vacuum pump device. The second end of the vacuum pump device is connected with an atmospheric environment. When the non-condensable gas is extracted, the non-condensable gas is compressed by the vacuum pump device and then discharged to the atmosphere. The application can optimize the water quality pollution problem of the circulating water station in the process flow.

Description

Technical Field

[0001] This application relates to the technical field of exhaust gas treatment, and in particular to an alkaline exhaust gas triple-effect vacuum concentration treatment system. Background Technology

[0002] In phosphate preparation, the concentration process is the core of the production flow, and the vacuum cooling and concentration system is a key component of this system. However, traditional three-effect concentration vacuum systems have significant drawbacks: the direct contact between circulating water and secondary steam leads to severe pollution of the circulating water. The root cause is that reaction byproducts, impurities, and suspended solids carried in the secondary steam directly mix into the circulating water system, causing a significant decrease in water purity. This pollution not only reduces the efficiency of subsequent processes but also significantly increases the operating load and cost of wastewater treatment systems. Therefore, developing new solutions that combine high efficiency, economy, and reliability to address the water pollution problem in the circulating water system of phosphate concentration processes has become a crucial area for technological upgrading in the industry. Utility Model Content

[0003] To overcome the shortcomings of existing technologies, this application provides an alkaline tail gas triple-effect vacuum concentration treatment system, offering an efficient and reliable solution to address water pollution issues in the circulating water station of the process flow.

[0004] The technical solution adopted by this application to solve its technical problem is:

[0005] A triple-effect vacuum concentration treatment system for alkaline exhaust gas includes: a triple-effect evaporator, a heat exchanger, a first water circulation pipeline, and a vacuum pump device.

[0006] The first end of the heat exchanger is connected to the exhaust gas output end of the triple-effect evaporator, the second end of the heat exchanger is connected to the input end of the condensate storage device, the third end of the heat exchanger is connected to the first end of the vacuum pump device, and the first water circulation pipeline passes through the fourth and fifth ends of the heat exchanger.

[0007] When the triple-effect evaporator produces alkaline tail gas, the alkaline tail gas is indirectly condensed in the heat exchanger through the first water circulation pipeline, and the condensate obtained is transported to the condensate storage device, while the non-condensable gas is extracted to the vacuum pump device.

[0008] The second end of the vacuum pump device is connected to the atmospheric environment; when the non-condensable gas is extracted, the non-condensable gas is compressed by the vacuum pump device and then discharged into the atmosphere.

[0009] Optionally, the vacuum pump device includes a water ring vacuum pump and a second water circulation pipeline;

[0010] The first end of the water ring vacuum pump is connected to the third end of the heat exchanger, and the second end of the water ring vacuum pump is connected to the atmospheric environment. The second water circulation pipeline passes through the third and fourth ends of the vacuum pump device.

[0011] When the non-condensable gas is extracted, it is compressed in the vacuum pump device through the second water circulation pipeline and then discharged into the atmosphere.

[0012] Optionally, the heat exchanger is a wound heat exchanger.

[0013] Optionally, the process water temperature configured in the first water circulation pipeline is less than 40°C.

[0014] Optionally, the triple-effect evaporator includes a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit connected in sequence;

[0015] The output end of the triple-effect evaporator unit is connected to the first end of the heat exchanger as the exhaust gas output end.

[0016] Optionally, the single-effect evaporation unit includes a single-effect evaporator, a boiler, and a single-effect discharge device;

[0017] The first input terminal of the first-effect evaporator is connected to the boiler, the second input terminal of the first-effect evaporator is connected to the first output terminal of the first-effect discharge device, and the output terminal of the first-effect evaporator is connected to the input terminal of the second-effect evaporation unit.

[0018] When the material from the first effect of the first-effect discharge device is heated by boiler steam generated by the boiler in the first-effect evaporator to generate secondary steam, the secondary steam generated by the material from the first effect is transferred to the second-effect evaporation unit.

[0019] Optionally, the double-effect evaporation unit includes a double-effect evaporator and a double-effect discharge device;

[0020] The first input terminal of the double-effect evaporator is connected to the output terminal of the first-effect evaporator, the second input terminal of the double-effect evaporator is connected to the first output terminal of the double-effect discharge device, and the output terminal of the double-effect evaporator is connected to the input terminal of the triple-effect evaporation unit.

[0021] When the material in the second effect of the double-effect discharge device is heated by the secondary steam generated by the material in the first effect in the double-effect evaporator to generate new secondary steam, the secondary steam generated by the material in the second effect is transferred to the triple-effect evaporation unit.

[0022] Optionally, the triple-effect evaporation unit includes a triple-effect discharge device and a triple-effect evaporator;

[0023] The first input terminal of the triple-effect evaporator is connected to the output terminal of the double-effect evaporator, the second input terminal of the double-effect evaporator is connected to the first output terminal of the triple-effect discharge device, and the output terminal of the triple-effect evaporator is connected to the first terminal of the heat exchanger.

[0024] When the triple-effect material of the triple-effect discharge device is heated by the secondary steam generated by the secondary steam of the double-effect material in the triple-effect evaporator to generate new secondary steam, the secondary steam generated by the triple-effect material is transmitted to the heat exchanger as alkaline tail gas.

[0025] Optionally, the input end of the triple-effect discharge device is connected to an external feeding device, and the second output end of the triple-effect discharge device is connected to the input end of the double-effect discharge device.

[0026] The second output terminal of the dual-effect discharge device is connected to the input terminal of the single-effect discharge device.

[0027] Optionally, the first water circulation pipeline is connected to the circulating water station via the circulating water return main pipeline.

[0028] The beneficial effects of this application are as follows: The triple-effect evaporator generates tail gas containing alkaline byproducts. This tail gas undergoes indirect condensation in the heat exchanger via the first water circulation pipeline, and the condensate enters the condensate storage device. The non-condensable gases are extracted to the vacuum pump device, compressed, and then discharged into the atmosphere. In this way, the heat exchanger effectively avoids direct contact between the circulating water and the alkaline tail gas, preventing contamination of the circulating water, thereby improving the efficiency of subsequent process steps and reducing the load on the wastewater treatment system. The vacuum pump device further extracts and discharges the non-condensable gases, ensuring the normal operation of the system. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the alkaline tail gas triple-effect vacuum concentration treatment system provided in the embodiments of this application;

[0030] Figure 2 This is a schematic block diagram of the triple-effect evaporation device of the alkaline tail gas triple-effect vacuum concentration treatment system provided in the embodiments of this application;

[0031] Figure label:

[0032] 1. Triple-effect evaporator; 2. Heat exchanger; 3. First water circulation pipeline; 4. Water ring vacuum pump; 5. Condensate storage device; 6. Second water circulation pipeline; 101. First-effect evaporator; 102. Second-effect evaporator; 103. Triple-effect evaporator; 104. Boiler; 105. First-effect discharge device; 106. Second-effect material discharge device; 107. Triple-effect material discharge device; 108. Feeding device. Detailed Implementation

[0033] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0034] The following will clearly and completely describe the concept, specific structure, and resulting technical effects of this application in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of this application. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this application can be combined interactively without contradicting each other.

[0035] Reference Figure 1 , Figure 1 This is a schematic diagram of the alkaline tail gas triple-effect vacuum concentration treatment system provided in the embodiments of this application. The diagram shows the system architecture, including a triple-effect evaporator 1, a heat exchanger 2, a first water circulation pipeline 3, and a vacuum pump device. The following is a detailed description of the system. Figure 1 A detailed description of this system is provided below:

[0036] The first end of the heat exchanger 2 is connected to the exhaust gas output end of the triple-effect evaporator 1, the second end of the heat exchanger 2 is connected to the input end of the condensate storage device 5, the third end of the heat exchanger 2 is connected to the first end of the vacuum pump device, and the first water circulation pipeline 3 passes through the fourth and fifth ends of the heat exchanger 2.

[0037] The triple-effect evaporator 1 includes a first-effect evaporator unit, a second-effect evaporator unit, and a third-effect evaporator unit connected in sequence; the output end of the third-effect evaporator unit is connected to the first end of the heat exchanger 2 as the exhaust gas output end. The triple-effect evaporation system adopts a multi-stage heat energy cascade utilization structure, consisting of a first-effect evaporator unit, a second-effect evaporator unit, and a third-effect evaporator unit connected in series. In this process, the alkaline exhaust gas mainly originates from the volatile alkaline components released during the material evaporation process.

[0038] The material flow path is as follows: it first enters the triple-effect evaporation unit, undergoes preliminary concentration, and is then conveyed to the double-effect evaporation unit, finally entering the single-effect evaporation unit for deep concentration. The single-effect evaporation unit directly heats the material using boiler steam as the initial heat source, and the resulting secondary steam is used as a heat medium to indirectly heat the material in the double-effect evaporation unit and induce secondary evaporation. The secondary steam generated in the double-effect evaporation unit is further introduced into the triple-effect evaporation unit as a heat source to drive the final concentration process. The low-temperature secondary steam generated in the triple-effect evaporation unit then enters heat exchanger 2 for waste heat recovery and tail gas treatment.

[0039] More specifically, refer to Figure 2 , Figure 2 This is a schematic block diagram of the triple-effect evaporator 1 of the alkaline tail gas triple-effect vacuum concentration treatment system provided in the embodiments of this application. The following is a description of the device. Figure 2 Further explanation of triple-effect evaporator 1:

[0040] The single-effect evaporation unit includes a single-effect evaporator 101, a boiler 104, and a single-effect discharge device 105;

[0041] The first input terminal of the first-effect evaporator 101 is connected to the boiler 104, the second input terminal of the first-effect evaporator 101 is connected to the first output terminal of the first-effect discharge device 105, and the output terminal of the first-effect evaporator 101 is connected to the input terminal of the second-effect evaporation unit.

[0042] Specifically, when the material of the first effect of the first effect discharge device 105 is heated by the boiler steam generated by the boiler 104 in the first effect evaporator 101 to generate secondary steam, the secondary steam generated by the material of the first effect is transferred to the second effect evaporation unit.

[0043] More specifically, high-concentration materials are directly heated by boiler steam, causing a large amount of moisture to evaporate and output as concentrated materials.

[0044] Furthermore, the double-effect evaporation unit includes a double-effect evaporator 102 and a double-effect discharge device 106;

[0045] The first input terminal of the double-effect evaporator 102 is connected to the output terminal of the first-effect evaporator 101, the second input terminal of the double-effect evaporator 102 is connected to the first output terminal of the double-effect discharge device 106, and the output terminal of the double-effect evaporator 102 is connected to the input terminal of the triple-effect evaporation unit.

[0046] Specifically, when the secondary material of the second effect in the second effect discharge device 106 is heated by the secondary steam generated by the primary material in the second effect evaporator 102 to generate new secondary steam, the secondary steam generated by the secondary material is transferred to the third effect evaporation unit.

[0047] More specifically, the second effect is for medium-concentration materials, which are heated by the secondary steam of the first effect for further concentration and then output to the first effect discharge device 105.

[0048] Furthermore, the triple-effect evaporation unit includes a triple-effect discharge device 107 and a triple-effect evaporator 103;

[0049] The first input terminal of the triple-effect evaporator 103 is connected to the output terminal of the double-effect evaporator 102, the second input terminal of the double-effect evaporator 102 is connected to the first output terminal of the triple-effect discharge device 107, and the output terminal of the triple-effect evaporator 103 is connected to the first terminal of the heat exchanger 2.

[0050] Specifically, when the triple-effect material of the triple-effect discharge device 107 is heated by the secondary steam generated by the secondary steam of the double-effect material in the triple-effect evaporator 103 to generate new secondary steam, the secondary steam generated by the triple-effect material is transmitted to the heat exchanger 2 as alkaline tail gas.

[0051] More specifically, in the third-effect process, the low-concentration material is heated by the secondary steam of the second-effect process, evaporating some of the moisture and increasing the concentration to a medium concentration, thus becoming the second-effect material, which is then output to the second-effect discharge device 106.

[0052] Furthermore, the input end of the triple-effect discharge device 107 is connected to the external feeding device 108, and the second output end of the triple-effect discharge device 107 is connected to the input end of the double-effect discharge device 106.

[0053] The second output terminal of the dual-effect discharge device 106 is connected to the input terminal of the single-effect discharge device 105.

[0054] Specifically, the raw material is output from the feeding device 108 to the triple-effect discharge device 107, and then from the triple-effect to the second effect and then to the first effect. The first effect uses boiler steam. The secondary steam generated by the concentration of the material in the first effect heats the material in the second effect. The secondary steam generated by the heating and concentration of the material in the second effect heats the material in the triple-effect. The secondary steam generated by the heating of the material in the triple-effect enters the heat exchanger 2 below and is condensed by the circulating water in the first water circulation pipeline 3. The non-condensable gases are then drawn away by the vacuum pump, and the triple-effect system can become a vacuum system.

[0055] Its working principle is as follows: when the triple-effect evaporator 1 produces alkaline tail gas, the alkaline tail gas is indirectly condensed in the heat exchanger 2 through the first water circulation pipeline 3, and the condensate obtained is transported to the condensate storage device 5, while the non-condensable gas is extracted to the vacuum pump device.

[0056] Specifically, after the alkaline gas (such as ammonia-containing gas) enters heat exchanger 2, its temperature drops significantly due to heat exchange with the circulating cooling water (CWS). During this process, some condensable components in the gas undergo a phase change due to the temperature drop, condensing into a liquid state to form alkaline condensate, which is discharged from the bottom of heat exchanger 2 and transported to a collection tank for further treatment or recycling. After cooling by heat exchanger 2, the remaining uncondensed gas (mainly non-condensable gases, such as residual air and trace amounts of unreacted alkaline gas) is drawn away by a vacuum pump through pipelines.

[0057] More specifically, compared to commonly used exhaust gas scrubbing towers, after alkaline exhaust gas enters heat exchanger 2, the circulating water in the heat exchanger 2 will not come into direct contact with the alkaline exhaust gas because the heat exchanger 2 is equipped with a first water circulation pipeline 3, thus ensuring that the quality of the circulating water is not affected by the alkaline exhaust gas.

[0058] In this embodiment of the application, in order to reduce the footprint of the equipment to meet the space installation requirements, the heat exchanger 2 used is a wound heat exchanger 2.

[0059] In this embodiment, the process water configured in the first water circulation pipeline 3 has a temperature of less than 40°C and can be used as pump sealing water.

[0060] Furthermore, this application embodiment proposes that the circulating water in the first water circulation pipeline 3, after heat exchange in the heat exchanger 2, can be directly returned to the circulating water station via the return water main pipe, instead of being returned to the circulating water station via the circulating water tank and the circulating water pump. This optimizes the process flow, reduces the factors that may cause the concentration to be interrupted due to the failure of the circulating water pump, and also reduces the possibility of the circulating water being contaminated secondary.

[0061] Furthermore, the second end of the vacuum pump device is connected to the atmospheric environment. After the non-condensable gas is pumped away by the vacuum pump, the triple-effect evaporator 1 involved in this application also forms a vacuum environment, and finally the non-condensable gas is also discharged into the atmosphere through the second end (exhaust port) of the vacuum pump device.

[0062] Furthermore, the vacuum pump device includes a water ring vacuum pump 4 and a second water circulation pipeline 6;

[0063] The first end of the water ring vacuum pump 4 is connected to the third end of the heat exchanger 2, and the second end of the water ring vacuum pump 4 is connected to the atmospheric environment. The second water circulation pipeline 6 passes through the third and fourth ends of the vacuum pump device.

[0064] When the non-condensable gas is extracted, it is compressed in the vacuum pump device through the second water circulation pipeline 6 and then discharged into the atmosphere.

[0065] In this embodiment, the vacuum pump device mentioned can be a water ring vacuum pump 4. A water ring vacuum pump 4 is a volumetric vacuum device that uses liquid (usually water) as a working medium to form a sealed cavity and achieve gas compression. Its core principle is to drive the liquid to form a dynamic water ring by rotating the impeller. The gas is drawn in, compressed and discharged by the periodic change in volume between the water ring and the impeller, thereby establishing a vacuum environment in the system. Therefore, in this embodiment, a second water circulation pipeline 6 is also provided to pass through the third and fourth ends of the water ring vacuum pump 4.

[0066] During operation, an appropriate amount of water is injected into the pump. When the impeller rotates, the water is thrown against the inner wall of the pump body, forming a water ring concentric with the impeller. A periodically expanding sealed space is formed between the impeller blades and the water ring, generating negative pressure to draw in gas. As the impeller rotates, the sealed space gradually shrinks, and the gas is compressed to near atmospheric pressure before being discharged into the atmosphere through the second end (exhaust port) of the vacuum pump device.

[0067] On the other hand, in the original design of the III-effect vacuum concentrator system, the process flow was as follows: the secondary steam generated by the III-effect concentrator entered the concentrator tail gas condenser tower and was treated by circulating water spray washing. The condensate flowed back to the circulating water system with the circulating water, and the change in steam volume created negative pressure. This condenser tower was usually installed on the 26-meter floor of the plant, and the designed circulating water volume needed to reach 350 m³ / h and the pressure needed to be >0.4 MPa. If these standards were not met, it would directly affect the concentrator production load. After the modification, the system adopted a combination of indirect heat exchange with two heat exchangers and vacuum pump extraction of non-condensable gases. Even under conditions of low circulating water volume or pressure <0.4 MPa, the stable operation of the concentrator start-up load can still be ensured, significantly improving the overall stability of the system.

[0068] The above is a detailed description of the preferred embodiments of this application. However, the invention of this application is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A triple-effect vacuum concentration treatment system for alkaline exhaust gas, characterized in that, include: Triple-effect evaporator, heat exchanger, first water circulation pipeline and vacuum pump unit; The first end of the heat exchanger is connected to the exhaust gas output end of the triple-effect evaporator, the second end of the heat exchanger is connected to the input end of the condensate storage device, the third end of the heat exchanger is connected to the first end of the vacuum pump device, and the first water circulation pipeline passes through the fourth and fifth ends of the heat exchanger. When the triple-effect evaporator produces alkaline tail gas, the alkaline tail gas is indirectly condensed in the heat exchanger through the first water circulation pipeline, and the condensate obtained is transported to the condensate storage device, while the non-condensable gas is extracted to the vacuum pump device. The second end of the vacuum pump device is connected to the atmospheric environment; when the non-condensable gas is extracted, the non-condensable gas is compressed by the vacuum pump device and then discharged into the atmosphere.

2. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 1, characterized in that, The vacuum pump device includes a water ring vacuum pump and a second water circulation pipeline; The first end of the water ring vacuum pump is connected to the third end of the heat exchanger, and the second end of the water ring vacuum pump is connected to the atmospheric environment. The second water circulation pipeline passes through the third and fourth ends of the vacuum pump device. When the non-condensable gas is extracted, it is compressed in the vacuum pump device through the second water circulation pipeline and then discharged into the atmosphere.

3. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 1, characterized in that, The heat exchanger is a wound heat exchanger.

4. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 1, characterized in that, The process water temperature configured in the first water circulation pipeline is less than 40°C.

5. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 1, characterized in that, The triple-effect evaporator includes a first-effect evaporation unit, a second-effect evaporation unit, and a third-effect evaporation unit connected in sequence. The output end of the triple-effect evaporator unit is connected to the first end of the heat exchanger as the exhaust gas output end.

6. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 5, characterized in that, The single-effect evaporation unit includes a single-effect evaporator, a boiler, and a single-effect discharge device; The first input terminal of the first-effect evaporator is connected to the boiler, the second input terminal of the first-effect evaporator is connected to the first output terminal of the first-effect discharge device, and the output terminal of the first-effect evaporator is connected to the input terminal of the second-effect evaporation unit. When the material from the first effect of the first effect discharge device is heated by boiler steam generated by the boiler in the first effect evaporator to generate secondary steam, the secondary steam generated by the material from the first effect is transferred to the second effect evaporation unit.

7. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 6, characterized in that, The double-effect evaporation unit includes a double-effect evaporator and a double-effect discharge device; The first input terminal of the double-effect evaporator is connected to the output terminal of the first-effect evaporator, the second input terminal of the double-effect evaporator is connected to the first output terminal of the double-effect discharge device, and the output terminal of the double-effect evaporator is connected to the input terminal of the triple-effect evaporation unit. When the material in the second effect of the double-effect discharge device is heated by the secondary steam generated by the material in the first effect in the double-effect evaporator to generate new secondary steam, the secondary steam generated by the material in the second effect is transferred to the triple-effect evaporation unit.

8. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 7, characterized in that, The triple-effect evaporation unit includes a triple-effect discharge device and a triple-effect evaporator; The first input terminal of the triple-effect evaporator is connected to the output terminal of the double-effect evaporator, the second input terminal of the double-effect evaporator is connected to the first output terminal of the triple-effect discharge device, and the output terminal of the triple-effect evaporator is connected to the first terminal of the heat exchanger. When the triple-effect material of the triple-effect discharge device is heated by the secondary steam generated by the secondary steam of the double-effect material in the triple-effect evaporator to generate new secondary steam, the secondary steam generated by the triple-effect material is transmitted to the heat exchanger as alkaline tail gas.

9. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 8, characterized in that, The input end of the triple-effect discharge device is connected to an external feeding device, and the second output end of the triple-effect discharge device is connected to the input end of the double-effect discharge device. The second output terminal of the dual-effect discharge device is connected to the input terminal of the single-effect discharge device.

10. The alkaline tail gas triple-effect vacuum concentration treatment system according to claim 1, characterized in that, The first water circulation pipeline is connected to the circulating water station via the circulating water return main pipeline.

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