Steam wet self-condensing device and method for desulfurization wastewater zero discharge system

Abstract

The present invention discloses a steam wet self-condensing device and method for a zero-discharge system for desulfurization wastewater. The tail negative pressure steam from the multi-effect flash separation device enters the tube side of the wet air cooler for cooling. The wet air cooler uses self-circulating spray water and condensate discharged by the condensate pump to cool the heat exchange tube; and mechanical forced ventilation is used for heat exchange. The condensate is discharged from the outlet of the wet air cooler and flows downward into the condensate tank; when the condensate in the condensate tank is collected to a certain liquid level, it can be discharged to the wet air cooler as supplementary water by the condensate discharge pump for heat exchange, or a part of it can be discharged to various water points; the vacuum pump discharges the air and the water vapor that is not completely condensed in the condensate tank to maintain the negative pressure condition in the condensate tank, thereby also providing a negative pressure condition for the wet air cooler and the multi-effect flash separation system. The present invention has the effect of low energy consumption and stable operation at different ambient temperatures without the need to introduce external circulating cooling water.

Description

Technical Field

[0001] The present invention relates to the technical field of desulfurization wastewater treatment, and in particular to a steam wet self-condensing device and method for a desulfurization wastewater zero-discharge system. Background Art

[0002] In the process of flue gas desulfurization in thermal power plants, a limestone-gypsum wet desulfurization system is usually used. In order to maintain the chloride ion balance in the desulfurization system, desulfurization wastewater needs to be discharged from the desulfurization system regularly. Since this part of the wastewater contains a large amount of harmful pollutants such as dissolved salts, multi-effect evaporation technology is currently used to recycle this part of the wastewater to achieve zero discharge of desulfurization wastewater.

[0003] In the process of using multiple-effect flash evaporation technology, the tail negative pressure steam generated in the last flash evaporation process generally needs to be condensed using the existing circulating water in the power plant, so that condensate water can be produced for reuse. However, in most power plants, this part of circulating water cannot be provided due to difficulties in opening the pipeline or insufficient surplus circulating water, making it difficult to implement multiple-effect flash evaporation technology in the zero-discharge transformation project of desulfurization wastewater. Summary of the invention

[0004] According to one aspect of the present invention, a steam wet self-condensing device for a zero-discharge system for desulfurization wastewater is provided, comprising a wet air cooler, a condensate tank, a vacuum pump, a condensate discharge pump and a condensate water point outlet, the wet air cooler comprising a top spray layer, a lower water tank, a circulating pump and a system pump cooling water point, the wet air cooler is arranged upstream of the condensate tank, the wet air cooler is arranged at a position higher than the condensate tank, the condensate tank is arranged upstream of the vacuum pump and the condensate discharge pump, the downstream of the condensate discharge pump is connected to the wet air cooler, the condensate water point outlet is located at the most downstream, the condensate water point outlet is connected to each water point, the circulating pump outlet is connected to the system pump cooling water point and the spray layer, the system pump cooling water point return water is connected to the water tank, the pipe line from the wet air cooler to the condensate tank and the pipe line from the condensate tank to the suction port of the vacuum pump are a closed interconnected system.

[0005] The above-mentioned steam wet self-condensing device for the zero-discharge system of desulfurization wastewater has the beneficial effect that the tail negative pressure steam from the multi-effect flash separation device enters the tube side of the wet air cooler, and the wet air cooler uses self-circulating spray water and condensate discharged by the condensate pump to cool the heat exchange tube, and uses mechanical forced ventilation for heat exchange. After heat exchange, most of the temperature is reduced and refluxed to the water tank at the bottom of the equipment, and a small part is vaporized and volatilized and discharged with the air; the condensate is discharged from the outlet of the wet air cooler. Under the action of gravity and vacuum negative pressure, it flows downward into the condensate tank; and the wet air cooler realizes the self-circulation of water inside the wet air cooler through the circulating pump and the cooling water water points of the machine pump in the system, and uses the self-circulating spray water and the condensate discharged by the condensate pump to cool the heat exchange tube; when the condensate in the condensate tank is collected to a certain level, it can be discharged to the wet air cooler as supplementary water for heat exchange by the condensate discharge pump, or part of it can be discharged to various water points; the vacuum pump Air and water vapor that is not completely condensed are discharged to maintain negative pressure conditions in the condensate tank, thereby also providing negative pressure conditions for the wet air cooler and the multiple-effect flash separation system. Therefore, compared with the tail steam condensing device of the traditional desulfurization wastewater multiple-effect flash treatment system, the present invention does not need to introduce external circulating cooling water, which solves the problem that it is difficult for the power plant to provide this part of circulating water. There is no need for a circulating water interface between the desulfurization wastewater multiple-effect flash treatment system and the main device of the power plant, and there is no need to lay a circulating water pipeline. For the renovation project, the renovation content is small, and there is no impact on the circulating water system of the main device, which is easy to implement. The wet air cooler can be arranged on the roof of the desulfurization wastewater multiple-effect flash treatment system building, and there is no footprint. The water consumed by the wet air cooler is supplemented by the condensate generated in the device, and there is no need to supplement water from the outside. Since the condensate supplemented by the wet air cooler has a low salt content, the equipment is not prone to scaling, which is conducive to long-term stable operation. The wet air cooler has low equipment investment costs, small equipment size, and is easy to install and maintain.

[0006] In some embodiments, the steam wet self-condensing device for the zero-discharge system of desulfurization wastewater is characterized in that it also includes a recycled water discharge pump, which is connected to the bottom water tank of the wet air cooler, and the recycled water discharge pump discharges the condensed water in the steam condensing device to each water point. The beneficial effect is that the recycled water discharge pump can pump the condensed water in the bottom water tank of the wet air cooler to each water point.

[0007] In some embodiments, a condensate discharge pump is disposed downstream of the condensate tank, and is connected to the top spray layer of the wet air cooler. The beneficial effect is that the condensate discharge pump can discharge the water in the condensate tank to the spray layer for water replenishment for spray heat exchange.

[0008] In some embodiments, a condensate discharge pump is disposed downstream of the condensate tank, and the condensate discharge pump is connected to the water tank at the bottom of the wet air cooler. The beneficial effect is that the condensate discharge pump can discharge the water in the condensate tank to the water tank at the bottom of the wet air cooler for water replenishment.

[0009] In some embodiments, the condensate discharge pump is connected to each water point and the wet air cooler at the same time. The beneficial effect is that the condensate discharge pump can discharge part of the water in the condensate tank to the wet air cooler and the other part to each water point.

[0010] In some embodiments, the wet air cooler is provided with relatively arranged vents. The beneficial effect is that the vents enable the wet air cooler to adopt mechanical forced ventilation, and can operate stably with low energy consumption under different ambient temperatures; when the wet air cooler is used in areas with lower temperatures in winter, it is not necessary to use spray water.

[0011] In some embodiments, the vacuum pump is connected to the top of the condensate tank. The beneficial effect is that the vacuum pump suction port is connected from the top of the condensate tank, and the air and the water vapor that are not completely condensed in the condensate tank are discharged, so as to maintain the negative pressure condition in the condensate tank, thereby also providing a negative pressure condition for the wet air cooler and the multi-effect flash separation system.

[0012] According to another aspect of the present invention, a steam wet self-condensing method for a zero-discharge system for desulfurized wastewater is provided. The steam wet self-condensing device for a zero-discharge system for desulfurized wastewater is applied. The tail negative pressure steam from the multi-effect flash separation device enters the pipe side of the wet air cooler, exchanges heat with the spray water of the spray layer in the wet air cooler, and is gradually condensed into condensed water. After the spray water in the wet air cooler exchanges heat with the air, most of it is cooled and flows back to the water tank at the bottom of the equipment, and a small part is vaporized and volatilized and discharged with the air. The circulation power of the spray water in the wet air cooler Provided by the circulating water pump in the equipment; the condensed water is discharged from the outlet of the wet air cooler, and flows downward into the condensed water tank under the action of gravity and vacuum negative pressure; when the condensed water in the condensed water tank is collected to a certain liquid level, it is discharged to the wet air cooler by the condensed water discharge pump, and this part of water can be directly discharged into the top spray layer of the wet air cooler, and directly exchange heat with steam as spray water; it can also be discharged into the water tank at the bottom of the wet air cooler; the water discharged by the condensed water discharge pump can be discharged to the wet air cooler in its entirety, or part of it can be discharged to various water use points, and part of it can be discharged to the wet air cooler as supplementary water. The vacuum pump suction port is connected from the top of the condensed water tank, and the air and water vapor that are not completely condensed in the condensed water tank are discharged to maintain the negative pressure condition in the condensed water tank, thereby also providing a negative pressure condition for the wet air cooler and the multi-effect flash separation system. The beneficial effect is that the above reasonably and effectively realizes the steam wet self-condensation process of the desulfurization wastewater zero emission system, without the need to introduce external circulating cooling water or external water supply, and can operate stably with low energy consumption under different environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of a steam wet self-condensing device for a desulfurization wastewater zero-discharge system according to one embodiment of the present invention;

[0014] Figure 2 It is a structural schematic diagram of a steam wet self-condensing device for a desulfurization wastewater zero discharge system according to another embodiment of the present invention;

[0015] Figure 3 This is a schematic structural diagram of a steam wet self-condensing device for a desulfurization wastewater zero discharge system according to another embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0017] Figure 1 to Figure 3 A steam wet self-condensing device for a desulfurization wastewater zero discharge system according to an embodiment of the present invention is schematically shown.

[0018] The device comprises a wet air cooler 1, a condensate tank 2, a vacuum pump 3, a condensate discharge pump 4, and a recycled water discharge pump 6.

[0019] The wet air cooler 1 is arranged upstream of the condensate tank 2 and preferably arranged at a position higher than the condensate tank 2;

[0020] The wet air cooler 1 includes a top spray layer 11, a circulating pump 13 and a water point 14 for cooling water of the machine pump in the system. The outlet of the circulating pump 13 is connected to the water point 14 for cooling water of the machine pump in the system and the spray layer 11. The return water of the water point 14 for cooling water of the machine pump in the system is connected to the water tank 12. The wet air cooler 1 uses self-circulating spray water and condensed water discharged by the condensed water pump to cool the heat exchange tubes, and mechanical forced ventilation is used for heat exchange.

[0021] The condensate tank 2 is arranged upstream of the vacuum pump 3 and the condensate discharge pump 4;

[0022] The condensate tank 2 works under negative pressure and is used to collect steam condensate;

[0023] The suction port of the vacuum pump 3 is connected to the top of the condensate tank 2 to maintain the negative pressure condition of the condensate tank 2;

[0024] The pipe path of the wet air cooler 1 to the condensate tank 2 and the condensate tank 2 to the suction port of the vacuum pump 3 form a closed interconnecting system;

[0025] like Figure 1 and Figure 2 As shown, the condensate discharge pump 4 is arranged downstream of the condensate tank 2, and is used to transport the condensate to the top spray layer 11 of the wet air cooler 1 or the bottom water tank 12 of the wet air cooler 1;

[0026] like Figure 3 As shown, the water discharged by the condensate discharge pump 4 can be completely discharged to the wet air cooler 1, or a part of it can be discharged to each water point 7, and a part of it can be discharged to the wet air cooler 1 as supplementary water for the wet air cooler 1;

[0027] The recycled water discharge pump 6 is connected to the water tank 12 at the bottom of the wet air cooler 1 and is used to discharge the condensed water in the steam condensing device to each water point 7.

[0028] The steam wet self-condensing method of the desulfurization wastewater zero-discharge system of the present invention adopts the steam wet self-condensing device of the desulfurization wastewater zero-discharge system as follows:

[0029] 1. The tail negative pressure steam 9 from the multi-effect flash separation device enters the tube side of the wet air cooler 1, exchanges heat with the spray water in the wet air cooler 1, and is gradually condensed into condensed water;

[0030] 2. After the spray water in the wet air cooler 1 exchanges heat with the air, most of it cools down and flows back to the water tank 12 at the bottom of the equipment, and a small part of it is vaporized and volatilized and discharged with the air;

[0031] 3. The circulation power of the spray water in the wet air cooler 1 is provided by the circulating water pump in the equipment;

[0032] 4. The condensed water is discharged from the outlet of the wet air cooler 1 and flows downward into the condensed water tank 2 under the action of gravity and vacuum negative pressure;

[0033] 5. When the condensate in the condensate tank 2 reaches a certain liquid level, it is discharged to the wet air cooler 1 by the condensate discharge pump 4. This part of water can be directly discharged into the top spray layer 11 of the wet air cooler 1 to directly exchange heat with steam as spray water; it can also be discharged into the water tank 12 at the bottom of the wet air cooler 1;

[0034] 6. If Figure 3 As shown, the water discharged by the condensate discharge pump 4 can be completely discharged to the wet air cooler 1, or a part of it can be discharged to each water point 7, and a part of it can be discharged to the wet air cooler 1 as supplementary water.

[0035] 7. The suction port of the vacuum pump 3 is connected to the top of the condensate tank 2 to discharge the air and the water vapor that is not completely condensed in the condensate tank 2, so as to maintain the negative pressure condition in the condensate tank 2, thereby also providing the negative pressure condition for the wet air cooler 1 and the multi-effect flash separation system.

[0036] As mentioned above, compared with the tail steam condensing device of the traditional desulfurization wastewater multi-effect flash evaporation treatment system, the present invention does not need to introduce external circulating cooling water, which solves the problem that it is difficult for the power plant to provide this part of circulating water; there is no need for a circulating water interface between the desulfurization wastewater multi-effect flash evaporation treatment system and the main device of the power plant, and there is no need to lay a circulating water pipeline. For the transformation project, the transformation content is small, and there is no impact on the circulating water system of the main device, which is easy to implement; the wet air cooler 1 can adopt mechanical forced ventilation, and can operate stably with low energy consumption under different ambient temperatures; when the wet air cooler 1 is used in areas with lower temperatures in winter, there is no need to use spray water; the wet air cooler 1 can be arranged on the roof of the building of the desulfurization wastewater multi-effect flash evaporation treatment system, and there is no land occupation; the water consumed by the wet air cooler 1 is supplemented by the condensed water generated in the device, and no external water source is required; because the condensed water supplemented by the wet air cooler 1 has a low salt content, the equipment is not prone to scaling, which is conducive to long-term stable operation; the wet air cooler 1 has low equipment investment costs, small equipment size, and is easy to install and maintain;

[0037] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. Steam wet self-condensation method for zero discharge system of desulfurization wastewater, It is characterized in that Application of steam wet self-condensing device for zero discharge system of desulfurization wastewater, The steam wet self-condensing device comprises a wet air cooler (1), a condensate tank (2), a vacuum pump (3), a condensate discharge pump (4) and a condensate water outlet. The wet air cooler (1) comprises a top spray layer (11), a circulation pump (13) and a system pump cooling water outlet (14), and a water tank (12) at the bottom. The wet air cooler (1) is arranged upstream of the condensate tank (2). The position of the wet air cooler (1) is higher than that of the condensate tank (2). The condensate tank (2) is arranged between the vacuum pump (3) and the condensate discharge pump (4). The upstream of the condensate discharge pump (4) is connected to the wet air cooler (1) at the downstream, the outlet of the condensate water point is located at the most downstream, the outlet of the condensate water point is connected to each water point (7), the outlet of the circulation pump (13) is connected to the water point (14) for cooling water of the machine pump in the system and the spray layer (11), the return water of the water point (14) for cooling water of the machine pump in the system is connected to the water tank (12), and the pipe line from the wet air cooler (1) to the condensate tank (2) and the pipe line from the condensate tank (2) to the suction port of the vacuum pump (3) form a closed interconnecting system; It also includes a recycled water discharge pump (6), the recycled water discharge pump (6) being connected to a water tank (12) at the bottom of the wet air cooler (1), and the recycled water discharge pump (6) discharges condensed water in the steam condensing device to various water use points (7); The condensate discharge pump (4) is arranged downstream of the condensate tank (2), and the condensate discharge pump (4) is connected to the top spray layer (11) of the wet air cooler (1) or the bottom water tank (12) of the wet air cooler (1); The negative pressure steam at the tail enters the tube side of the wet air cooler. The wet air cooler uses self-circulating spray water and condensate discharged by the condensate pump to cool the heat exchange tubes, and uses mechanical forced ventilation for heat exchange. After heat exchange, most of the temperature drops and flows back to the water tank at the bottom of the equipment, and a small part is vaporized and volatilized and discharged with the air; the condensate is discharged from the outlet of the wet air cooler, and under the action of gravity and vacuum negative pressure, it flows downward into the condensate tank; and the wet air cooler uses the circulating pump and the system's machine pump cooling water water point , realize the self-circulation of water inside the wet air cooler, and use the self-circulating spray water and the condensate discharged by the condensate pump to cool the heat exchange tubes; when the condensate in the condensate tank collects to a certain liquid level, it is discharged to the wet air cooler as supplementary water by the condensate discharge pump for heat exchange, or a part of it is discharged to various water points; the vacuum pump discharges the air and the water vapor that is not completely condensed in the condensate tank, maintains the negative pressure condition in the condensate tank, and thus also provides negative pressure conditions for the wet air cooler and the multi-effect flash separation system; The condensate discharge pump (4) is connected to each of the water use points (7) and the wet air cooler (1) at the same time; The wet air cooler (1) is provided with ventilation openings arranged opposite to each other; The vacuum pump (3) is connected to the top of the condensate tank (2); The steam wet self-condensation method comprises the following steps: the tail negative pressure steam (9) from the multi-effect flash separation device enters the tube side of the wet air cooler (1), exchanges heat with the spray water of the spray layer (11) in the wet air cooler (1), and is gradually condensed into condensed water; After the spray water in the wet air cooler (1) exchanges heat with the air, most of the water is cooled and flows back to the water tank (12) at the bottom of the device, and a small part is vaporized and volatilized and discharged with the air; The circulation power of the spray water in the wet air cooler (1) is provided by a circulating water pump in the equipment; The condensed water is discharged from the outlet of the wet air cooler (1) and flows downward into the condensed water tank (2) under the action of gravity and vacuum negative pressure; When the condensate in the condensate tank (2) reaches a certain liquid level, the condensate is discharged to the wet air cooler (1) by the condensate discharge pump (4). This part of the water is directly discharged into the top spray layer (11) of the wet air cooler (1) to directly exchange heat with steam as spray water; or discharged into the bottom water tank (12) of the wet air cooler (1); The water discharged by the condensate discharge pump (4) is completely discharged to the wet air cooler (1), or a part of the water is discharged to each water use point (7), and a part of the water is discharged to the wet air cooler (1) as make-up water; The suction port of the vacuum pump (3) is connected to the top of the condensate tank (2), and discharges the air and water vapor that is not completely condensed in the condensate tank (2), thereby maintaining a negative pressure condition in the condensate tank (2), thereby also providing a negative pressure condition for the wet air cooler (1) and the multi-effect flash separation system.

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