A high-salt wastewater multi-effect evaporation system with secondary steam condensation coupled with waste heat utilization

Abstract

The application discloses a high-salinity wastewater multi-effect evaporation system terminal secondary steam condensation coupled waste heat utilization system, a secondary steam outlet of a last-effect flash tank in the high-salinity wastewater multi-effect evaporation system is communicated with a steam inlet of a finned condensing pipe in an air-cooled condenser, and an air outlet of the air-cooled condenser is communicated with an inlet at the bottom side of an air humidifying spray tower; an air outlet is arranged at the top of the air humidifying spray tower, a spraying device and a filler layer are sequentially arranged in the air humidifying spray tower from top to bottom, a wastewater discharge port at the bottom of the air humidifying spray tower is communicated with a top inlet of a flash tank in the high-salinity wastewater multi-effect evaporation system, and a high-salinity wastewater pipeline is communicated with the spraying device; the system can realize secondary steam condensation and utilize the heat of the secondary steam to pre-concentrate high-salinity wastewater, and the energy consumption of high-salinity wastewater multi-effect evaporation concentration is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of zero discharge of high-salt wastewater, and relates to a secondary steam condensation coupled waste heat utilization system at the end of a high-salt wastewater multi-effect evaporation system. Background Art

[0002] The multi-effect evaporation system is a relatively common technology in the zero-discharge treatment process of high-salt wastewater. This technology connects multiple evaporators in series, and the secondary steam of the previous evaporator is used as the heating steam for the next evaporator. The heating chamber of the next evaporator is the condenser of the previous evaporator, thereby achieving the purpose of saving raw steam and energy. However, the last-effect secondary steam of the multi-effect evaporation system still contains a large amount of heat. Direct condensation, on the one hand, brings about a huge waste of the heat of the secondary steam itself. On the other hand, the condensation process also consumes a large amount of cooling water and increases the power consumption of the centrifugal pump motor. Since the direct use of the last-effect secondary steam to preheat high-salt and high-hardness wastewater can easily lead to scaling of the heat exchanger, how to reasonably utilize the waste heat of the last-effect secondary steam is of great significance to reducing the energy consumption of multi-effect evaporation and concentration of high-salt wastewater. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a secondary steam condensation coupled waste heat utilization system at the end of a high-salt wastewater multi-effect evaporation system. The system can realize secondary steam condensation and use its heat to pre-concentrate high-salt wastewater, thereby reducing the energy consumption of multi-effect evaporation and concentration of high-salt wastewater.

[0004] To achieve the above-mentioned purpose, the high-salt wastewater multi-effect evaporation system of the present invention comprises a final-effect secondary steam condensation coupled waste heat utilization system comprising an air-cooled condenser, an air humidification spray tower and a high-salt wastewater pipeline;

[0005] The secondary steam outlet of the last-effect flash tank in the high-salt wastewater multi-effect evaporation system is connected to the steam inlet of the finned condenser tube in the air-cooled condenser, and the air outlet of the air-cooled condenser is connected to the inlet on the bottom side of the air humidification spray tower;

[0006] An air outlet is provided at the top of the air humidification spray tower, and a spray device and a packing layer are arranged in sequence from top to bottom in the air humidification spray tower. The wastewater discharge port at the bottom of the air humidification spray tower is connected to the top inlet of the flash tank in the high-salt wastewater multi-effect evaporation system, and the high-salt wastewater pipeline is connected to the spray device.

[0007] The secondary steam outlet of the last-effect flash tank in the high-salinity wastewater multi-effect evaporation system is connected to the steam inlet of the finned condenser in the air-cooled condenser through a pipeline.

[0008] It also includes a water-cooled condenser, and the steam outlet of the finned condenser tube in the air-cooled condenser is connected to the steam inlet of the water-cooled condenser.

[0009] The air outlet of the air-cooled condenser is connected with the air inlet of the bottom side of the air humidification spray tower through a communication air duct.

[0010] A fan is arranged at the air outlet of the top of the air-cooled condenser.

[0011] A demister is arranged at the air outlet of the top of the air humidification spray tower.

[0012] In operation, cold air enters the air-cooled condenser from the air inlet of the bottom of the air-cooled condenser, and sweeps over the surface of the finned condensing tube, in the process, the secondary steam is condensed in the finned condensing tube, and the cold air is heated to form dry unsaturated air.

[0013] In operation, the unsaturated air enters the air humidification spray tower, and is in countercurrent contact with the high-salinity wastewater at the filler layer for heat and mass transfer, so that the moisture in the high-salinity wastewater evaporates into the air and is carried away, thereby pre-concentrating the high-salinity wastewater.

[0014] The present application has the following beneficial effects:

[0015] In the operation of the high-salinity wastewater multi-effect evaporation system terminal secondary steam condensation coupled waste heat utilization system, the secondary steam of the last effect is used to indirectly heat air to become dry unsaturated air, and the dry unsaturated air is used to directly contact and exchange heat with the high-salinity wastewater, so that the high-salinity wastewater is pre-concentrated, thereby effectively utilizing the low-grade waste heat of the secondary steam, directly reducing the energy consumption and operating cost of the subsequent evaporation and concentration system; at the same time, after pre-condensation by the air-cooled condenser, the cooling water required for condensation of the secondary steam of the last effect and the power of the motor of the corresponding pump are greatly reduced, having an energy-saving effect. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present application.

[0017] Among them, 1 is an air humidification spray tower, 2 is a spraying device, 3 is a demister, 4 is a filler layer, 5 is a finned condensing tube, 6 is an air-cooled condenser, 7 is a fan, 8 is a water-cooled condenser, and 9 is a last-effect flash tank. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0019] The accompanying drawings illustrate schematic diagrams of the structures of the disclosed embodiments of the present invention. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0020] refer to Figure 1 The high-salt wastewater multiple-effect evaporation system of the present invention comprises a high-salt wastewater multiple-effect evaporation system including a final-effect flash tank 9, an air-cooled condenser 6, a finned condenser tube 5, a fan 7, a water-cooled condenser 8, a spray device 2, a demister 3, a packing layer 4 and an air humidification spray tower 1;

[0021] The secondary steam outlet of the final flash tank 9 is connected to the steam inlet of the finned condenser tube 5 in the air-cooled condenser 6 through a pipeline, and the steam outlet of the finned condenser tube 5 in the air-cooled condenser 6 is connected to the steam inlet of the water-cooled condenser 8.

[0022] In order to enhance the heat exchange between the secondary steam and the air, a fan 7 is provided at the air outlet on the top of the air-cooled condenser 6; the air outlet of the air-cooled condenser 6 is connected to the inlet on the bottom side of the air humidifying spray tower 1 through a connecting air duct.

[0023] An air outlet is provided at the top of the air humidifying spray tower 1. A demister 3, a spray device 2 and a packing layer 4 are sequentially provided in the air humidifying spray tower 1 from top to bottom. The wastewater discharge port at the bottom of the air humidifying spray tower 1 is connected to the top inlet of the flash tank, and the high-salt wastewater pipeline is connected to the spray device 2. The high-salt wastewater is sprayed onto the packing layer 4 through the spray device 2, and directly contacts the heated unsaturated air in countercurrent to evaporate, thereby concentrating. The pre-concentrated high-salt wastewater is discharged from the bottom of the air humidifying spray tower 1 and sent to the flash tank in the desulfurization wastewater multi-effect evaporation system.

[0024] The specific working process of the present invention is:

[0025] The secondary steam generated by the last-effect flash tank 9 enters the finned condenser tube 5 in the air-cooled condenser 6 under the action of the pressure difference. Under the suction action of the fan 7, the cold air enters the air-cooled condenser 6 from the air inlet at the bottom of the air-cooled condenser 6 and passes over the surface of the finned condenser tube 5. In this process, the secondary steam condenses in the finned condenser tube 5, and the cold air is heated to form dry unsaturated air; the remaining uncooled secondary steam enters the water-cooled condenser 8 and is further condensed. The unsaturated air heated by the secondary steam enters the air humidification spray tower 1 and contacts the high-salt wastewater in countercurrent at the packing layer 4 for heat and mass transfer, so that the moisture in the high-salt wastewater evaporates into the air and is carried away, thereby pre-concentrating the wastewater. On the one hand, it realizes the utilization of the waste heat of the last-effect second-effect steam, and on the other hand, it reduces the amount of cooling water required for the condensation of the last-effect secondary steam, thereby achieving energy saving of the system.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A high-salt wastewater multi-effect evaporation system with secondary steam condensation coupled with waste heat utilization system, characterized in that: It includes an air-cooled condenser (6), an air humidification spray tower (1) and a high-salt wastewater pipeline; The secondary steam outlet of the final-effect flash tank (9) in the high-salt wastewater multi-effect evaporation system is connected to the steam inlet of the finned condenser tube (5) in the air-cooled condenser (6), and the air outlet of the air-cooled condenser (6) is connected to the inlet on the bottom side of the air humidification spray tower (1); An air outlet is provided at the top of the air humidification spray tower (1), a spray device (2) and a packing layer (4) are sequentially provided in the air humidification spray tower (1) from top to bottom, a wastewater discharge port at the bottom of the air humidification spray tower (1) is connected to the top inlet of a flash tank in a high-salt wastewater multi-effect evaporation system, and a high-salt wastewater pipeline is connected to the spray device (2); During operation, cold air enters the air-cooled condenser (6) from the air inlet at the bottom of the air-cooled condenser (6) and passes over the surface of the finned condenser tube (5). During this process, secondary steam condenses in the finned condenser tube (5), and the cold air is heated to form dry unsaturated air. During operation, unsaturated air enters the air humidification spray tower (1) and contacts the high-salt wastewater in countercurrent at the packing layer (4) to transfer heat and mass, so that the water in the high-salt wastewater evaporates into the air and is carried away, thereby pre-concentrating the high-salt wastewater.

2. The high-salt wastewater multi-effect evaporation system according to claim 1, characterized in that: The secondary steam outlet of the last-effect flash tank (9) in the high-salinity wastewater multi-effect evaporation system is connected to the steam inlet of the finned condenser tube (5) in the air-cooled condenser (6) through a pipeline.

3. The high-salt wastewater multi-effect evaporation system according to claim 1, characterized in that: It also includes a water-cooled condenser (8), and the steam outlet of the finned condenser tube (5) in the air-cooled condenser (6) is connected to the steam inlet of the water-cooled condenser (8).

4. The high-salt wastewater multi-effect evaporation system according to claim 1, characterized in that: The air outlet of the air-cooled condenser (6) is connected to the inlet on the bottom side of the air humidifying spray tower (1) through the connecting air duct.

5. The high-salt wastewater multi-effect evaporation system and the final secondary steam condensation coupled waste heat utilization system according to claim 1 are characterized in that: A fan (7) is provided at the air outlet on the top of the air-cooled condenser (6).

6. The high-salt wastewater multi-effect evaporation system and the coupled waste heat utilization system of the final effect secondary steam condensation according to claim 1 are characterized in that: A demister (3) is provided at the top air outlet of the air humidification spray tower (1).

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