Wastewater treatment system and wastewater treatment method combining open evaporation and flue evaporation

Abstract

The invention discloses a wastewater treatment system combining open evaporation and flue evaporation and a wastewater treatment method, and relates to the technical field of wastewater treatment. Heat and mass transfer between the sewage and dry air is carried out in the concentration absorption tower, water in the sewage enters the dry air after being vaporized, moisture-carrying gas is output from the tower top of the concentration absorption tower, and water in the moisture-carrying gas enters the purified water by utilizing heat and mass transfer between the moisture-carrying gas and the purified water in the air regeneration tower. Returning gas output from the top of the air regeneration tower to the concentration absorption tower to form moisture-carrying gas circulation; the sewage output from the bottom of the concentration absorption tower is heated and then circulated to the concentration absorption tower to transfer heat and mass with the gas again, and the concentrated sewage output from the bottom of the concentration absorption tower enters the top of the atomization tower to transfer heat and mass with the flue gas input to the bottom of the atomization tower from the bypass flue, so that the concentrated sewage is evaporated to dryness to form dust. The concentration absorption tower, the air regeneration tower and the bypass flue are combined to realize zero discharge of wastewater, the energy consumption is relatively low, a steam system does not need to be transformed, and the application range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a wastewater treatment system and a wastewater treatment method combining open evaporation and flue evaporation. Background Art

[0002] At present, the zero-discharge requirements for desulfurization wastewater from power plants are becoming increasingly stringent, and desulfurization wastewater needs to be treated to a solid state. The main zero-discharge processes on the market currently have different problems, such as:

[0003] Three-effect evaporation plus crystallization technology: The main problems faced by three-effect evaporation plus crystallization technology are large investment, large amount of steam consumption during operation, and easy blockage of desulfurization wastewater near crystallization.

[0004] Open evaporation absorption plus crystallization technology: Open evaporation absorption plus crystallization technology consumes more steam. Although the heat of the steam is finally used to heat effective media such as desalted water and fresh air, it is only suitable for scenarios where the steam turbine has excess steam extraction.

[0005] In summary, the existing wastewater zero discharge processes mostly have problems such as high energy consumption and narrow scope of application.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a wastewater treatment system and a wastewater treatment method combining open evaporation and flue evaporation, aiming to reduce the energy consumption of the wastewater zero discharge system and broaden the scope of application.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides a wastewater treatment system of open evaporation and flue evaporation, comprising:

[0010] Concentrating absorption tower, the gas and the heated wastewater transfer heat and mass in the concentrating absorption tower, the wet gas is output at the top of the concentrating absorption tower, and the wastewater output at the bottom of the concentrating absorption tower is heated and circulated to the concentrating absorption tower to transfer heat and mass with the gas again;

[0011] The top of the air regeneration tower is connected with the bottom of the air regeneration tower, so that the moisture-carrying gas transfers heat and mass with the clean water in the air regeneration tower, and the water in the moisture-carrying gas enters the clean water. The top of the air regeneration tower is connected with the bottom of the concentrating absorption tower, so that the gas output from the air regeneration tower enters the concentrating absorption tower, forming a moisture-carrying gas circulation; the clean water output from the bottom of the air regeneration tower is cooled and circulated to the top of the air regeneration tower, forming a clean water circulation;

[0012] Atomizing tower: the concentrated sewage output from the bottom of the concentration absorption tower enters the top of the atomizing tower, and conducts heat and mass transfer with the flue gas entering from the bottom of the atomizing tower, so that the concentrated sewage is evaporated into dust;

[0013] The bypass flue is used to transport flue gas to the bottom of the atomizing tower.

[0014] In an optional embodiment, it also includes an air preheater, a dust collector and a wet flue gas desulfurization system. The boiler flue gas after desulfurization is divided into two paths, one path enters the bypass flue, and the other path enters the air preheater for heat exchange with fresh air. The heated fresh air is transported to the boiler, and the cooled flue gas is mixed with the flue gas output from the top of the atomizing tower and enters the dust collector for dust removal. The flue gas then enters the wet flue gas desulfurization system for desulfurization and is discharged. The desulfurization wastewater output from the wet flue gas desulfurization system enters the concentration absorption tower after heating.

[0015] In an optional embodiment, a heater for heating wastewater is further included, and the wastewater enters the concentration absorption tower after being heated by the heater;

[0016] A heat exchange coil is arranged inside the atomizing tower, and the heat exchange coil has a feed port and a discharge port; the feed port of the heat exchange coil is connected to the heat source outlet of the heater, and the discharge port of the heat exchange coil is connected to the heat source inlet of the heater, forming an intermediate hot water circulation.

[0017] In an optional embodiment, a first demister is provided at the top of the concentration absorption tower, a first spray pipeline is provided below the first demister, and the heated wastewater output by the heater enters the first spray pipeline;

[0018] A first mass transfer filler is arranged below the first spray pipeline.

[0019] In an optional embodiment, a compressed air purge pipeline is further included, and a plurality of purge gas inlets are arranged from top to bottom at positions corresponding to the heat exchange coils on the concentration absorption tower, and each purge gas inlet is connected to the compressed air purge pipeline;

[0020] The concentrated sewage output from the bottom of the concentration absorption tower is mixed with the compressed air output from the compressed air purge pipeline and then enters the top of the atomization tower.

[0021] In an optional embodiment, a spiral guide plate is provided below the heat exchange coil in the atomization tower to make the flue gas rise in a rotating manner.

[0022] In an optional embodiment, a regenerator is further included, and the waste water output from the bottom of the concentration absorption tower and the clean water output from the bottom of the air regeneration tower are heat exchanged in the regenerator, and the heated waste water enters the heater for further heating and then returns to the concentration absorption tower.

[0023] In an optional embodiment, a fresh air heater is also included. The cooled clean water output by the regenerator enters the fresh air heater for further cooling and then returns to the air regeneration tower. The heated fresh air output by the fresh air heater enters the air preheater for heat exchange with the flue gas.

[0024] In an optional embodiment, a second demister is provided at the top of the air regeneration tower, and a second spray pipeline is provided below the second demister, and the cooled purified water enters the second spray pipeline;

[0025] A second mass transfer filler is arranged below the second spray pipeline.

[0026] In a second aspect, the present invention provides a wastewater treatment method, which uses any one of the wastewater treatment systems in the aforementioned embodiments to treat wastewater.

[0027] The present invention has the following beneficial effects: the present invention conducts heat and mass transfer between sewage and dry air in the concentration absorption tower, so that water in the sewage is vaporized and enters the dry air, and the moisture-carrying gas is output at the top of the concentration absorption tower. The moisture-carrying gas is used to transfer heat and mass with clean water in the air regeneration tower, so that water in the moisture-carrying gas enters the clean water, and the gas output from the top of the air regeneration tower returns to the concentration absorption tower to form a moisture-carrying gas cycle; the sewage output at the bottom of the concentration absorption tower is heated and circulated to the concentration absorption tower to transfer heat and mass with the gas again, and the concentrated sewage output from the bottom of the concentration absorption tower enters the top of the atomization tower, and transfers heat and mass with the flue gas input to the bottom of the atomization tower through the bypass flue, so that the concentrated sewage is evaporated into dust. The present invention combines the concentration absorption tower, the air regeneration tower and the bypass flue to achieve zero wastewater discharge, with relatively low energy consumption, no need to transform the steam system, and a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 Schematic diagram of the wastewater treatment system.

[0030] Icons: 100-wastewater treatment system; 110-concentrating absorption tower; 111-heater; 112-first demister; 113-first spray pipeline; 114-first mass transfer filler; 115-regenerator; 120-air regeneration tower; 121-fresh air heater; 122-second demister; 123-second spray pipeline; 124-second mass transfer filler; 130-atomizing tower; 131-heat exchange coil; 132-compressed air purge pipeline; 133-spiral guide plate; 134-third demister; 135-third spray pipeline; 140-bypass flue; 151-air preheater; 152-dust collector; 153-wet desulfurization system; 154-chimney. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0032] like Figure 1 As shown, an embodiment of the present invention provides a wastewater treatment system 100 of open evaporation and flue evaporation, comprising: a concentration absorption tower 110, an air regeneration tower 120, an atomization tower 130 and a bypass flue 140, wherein a humidified gas circulates between the concentration absorption tower 110 and the air regeneration tower 120, the sewage is gradually concentrated in the concentration absorption tower 110, and the bypass flue 140 is used to provide flue gas to the atomization tower 130 to evaporate the concentrated sewage into dust. By combining the concentration absorption tower 110, the air regeneration tower 120, the atomization tower 130 and the bypass flue 140, zero discharge of wastewater is achieved, the energy consumption is relatively low, there is no need to modify the steam system, and the scope of application is wider.

[0033] The concentration absorption tower 110 is used for heat and mass transfer between gas (such as air) and heated wastewater (such as desulfurization wastewater) in the concentration absorption tower 110. The wet gas is output at the top of the concentration absorption tower 110. The wastewater output at the bottom of the concentration absorption tower 110 is heated and circulated to the concentration absorption tower 110 to transfer heat and mass with the gas again, and continuously concentrate to form liquid at the bottom of the tower.

[0034] The air regeneration tower 120 and the top of the concentration absorption tower 110 are connected to the bottom of the air regeneration tower 120, so that the humid gas transfers heat and mass with the clean water in the air regeneration tower 120, and the water in the humid gas cools down and enters the clean water. The clean water accumulates at the bottom of the air regeneration tower 120 to form a liquid at the bottom of the tower. The top of the air regeneration tower 120 is connected to the bottom of the concentration absorption tower 110 to allow the gas output from the air regeneration tower 120 to enter the concentration absorption tower 110, forming a humid gas circulation. That is, the air absorbs water in the concentration absorption tower 110 to produce high-temperature and high-humidity humid air, the humid air enters the air regeneration tower 120 and contacts the clean water, the water generated by condensation enters the clean water, and the drier air output from the air regeneration tower 120 returns to the concentration absorption tower 110 to continue to contact with the high-temperature sewage for heat and mass transfer.

[0035] Furthermore, the bypass flue 140 is used to transport high-temperature flue gas to the bottom of the atomizing tower 130 to provide heat to evaporate the sewage concentrate. Specifically, the concentrated sewage output from the bottom of the concentration absorption tower 110 enters the top of the atomizing tower 130, and conducts heat and mass transfer with the flue gas entering the bottom of the atomizing tower 130, so that the concentrated sewage is evaporated into dust.

[0036] Furthermore, the clean water output from the bottom of the air regeneration tower 120 is cooled and circulated to the top of the air regeneration tower 120 to form a clean water cycle. In some embodiments, the sewage output from the bottom of the concentration absorption tower 110 can be used to exchange heat with the clean water output from the bottom of the air regeneration tower 120. By setting a regenerator 115, the waste water output from the bottom of the concentration absorption tower 110 and the clean water output from the bottom of the air regeneration tower 120 exchange heat in the regenerator 115, and the heated waste water enters the heater 111 for further heating and then returns to the concentration absorption tower 110; the cooled clean water enters the fresh air heater 121 and exchanges heat with the incoming fresh air, and the clean water continues to cool and then returns to the air regeneration tower 120, and the heated fresh air output from the fresh air heater 121 enters the air preheater 151 for heat exchange with the flue gas.

[0037] Furthermore, the wastewater treatment system 100 also includes an air preheater 151, a dust collector 152 (such as a bag dust collector) and a wet desulfurization system 153. The boiler flue gas after desulfurization is divided into two paths, one path enters the bypass flue 140, and the other path enters the air preheater 151 for heat exchange with fresh air. The heated fresh air goes to the boiler, and the cooled flue gas is mixed with the flue gas output from the top of the atomizing tower 130 and enters the dust collector 152 for dust removal. The flue gas then enters the wet desulfurization system 153 for desulfurization and is discharged into the chimney 154. The desulfurized wastewater output from the wet desulfurization system 153 enters the concentration absorption tower 110 after being heated.

[0038] In some embodiments, the wastewater treatment system 100 further includes a heater 111 for heating wastewater, and the desulfurized wastewater enters the concentration absorption tower 110 after being heated by the heater 111. A heat exchange coil 131 is arranged inside the atomizing tower 130, and the heat exchange coil 131 has a feed port and a discharge port; the feed port of the heat exchange coil 131 is connected to the heat source outlet of the heater 111, and the discharge port of the heat exchange coil 131 is connected to the heat source inlet of the heater 111, forming an intermediate hot water cycle. In the atomizing tower 130, the flue gas heats the concentrated sewage on the one hand, and on the other hand, the flue gas is used to heat the circulating hot water in the heat exchange coil 131, thereby improving the utilization rate of energy.

[0039] In some embodiments, the wastewater treatment system 100 further includes a compressed air purge pipeline 132. A plurality of purge gas inlets are arranged from top to bottom at the positions corresponding to the heat exchange coils 131 on the concentration absorption tower 110. Each purge gas inlet is connected to the compressed air purge pipeline 132. The compressed air purge pipeline 132 provides compressed air for purge to purge the surface of the heat exchange coils 131 to maintain its surface smooth. The concentrated sewage output from the bottom of the concentration absorption tower 110 is mixed with the compressed air output from the compressed air purge pipeline 132 and enters the top of the atomization tower 130, and the compressed air is used to assist in atomization.

[0040] In some embodiments, a spiral guide plate 133 is provided below the heat exchange coil 131 in the atomizing tower 130, so that the flue gas is in a rotating upward shape, which is beneficial to improving the heat exchange effect. The number of spiral guide plates 133 is not limited, and multiple spiral guide plates 133 can be provided at intervals along the inner wall of the atomizing tower 130. The bottom of the atomizing tower 130 is a conical bottom for collecting dust.

[0041] It should be noted that the heat exchange coil 131 is arranged inside the atomizing tower 130, which can recover heat on the one hand, and create a larger surface area for the contact between liquid and gas on the other hand. The evaporation of liquid on the surface of the coil and the phase change can enhance heat transfer. However, this will cause the problem of ash and scarring on the surface of the coil, so compressed air purge is set. In addition, compressed air can also be mixed with the concentrated desulfurization wastewater before spraying to help it atomize.

[0042] In order to improve the effect of heat exchange and mass transfer, nozzles are used to output liquid materials at the top of the concentration absorption tower 110, the air regeneration tower 120 and the atomization tower 130:

[0043] In some embodiments, a first demister 112 is disposed at the top of the concentration absorption tower 110, and a first spray pipeline 113 is disposed below the first demister 112. The heated wastewater output by the heater 111 enters the first spray pipeline 113; a first mass transfer filler 114 is disposed below the first spray pipeline 113. The heated wastewater output by the heater 111 enters the first spray pipeline 113 and is sprayed out through a drip nozzle. The wastewater and gas transfer heat and mass in the first mass transfer filler 114, thereby improving the effect of heat and mass transfer. The high-temperature and high-humidity air is processed by the demister and then output, thereby reducing the impurity content in the high-temperature and high-humidity air and improving the quality of purified water.

[0044] In some embodiments, a second demister 122 is disposed at the top of the air regeneration tower 120, and a second spray pipeline 123 is disposed below the second demister 122. The cooled clean water enters the second spray pipeline 123; a second mass transfer filler 124 is disposed below the second spray pipeline 123. After the cooled clean water is sprayed by the drip nozzle on the second spray pipeline 123, it conducts efficient heat and mass transfer with the wet air in the second mass transfer filler 124, and the relatively dry air after cooling is processed by the second demister 122 and then output.

[0045] In some embodiments, a third demister 134 is disposed on the top of the atomizing tower 130 , and a third spray pipeline 135 is disposed below the third demister 134 . The concentrated sewage is mixed with compressed gas and then sprayed out from the atomizing nozzle of the third spray pipeline 135 .

[0046] Specifically, the types of fillers in the first mass transfer filler 114 and the second mass transfer filler 124 are not limited, and may be, for example, structured grid fillers, corrugated plate fillers, multi-faceted hollow ball fillers, and the like.

[0047] The embodiment of the present invention further provides a wastewater treatment method, which uses the wastewater treatment system provided by the embodiment of the present invention to treat wastewater. The specific working principle is described above in the specification and will not be repeated here.

[0048] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0049] Example 1

[0050] This embodiment provides a wastewater treatment system, such as Figure 1 As shown, the specific process is as follows:

[0051] ①Fresh air process:

[0052] After the fresh air is preheated to 40-50°C by the fresh air heater 121, it absorbs the heat of the purified water circulating water, and then enters the air preheater 151 for secondary heating to above 100°C before entering the boiler.

[0053] ②Boiler exhaust process

[0054] The boiler exhaust after denitration is divided into two paths. One path passes through the air preheater 151 to release heat to the fresh air; the other path passes through the atomizing tower 130, releasing part of the heat to the intermediate circulating hot water (in the heat exchange coil 131) while part of the heat is used for evaporation of the concentrated desulfurized wastewater. After that, the two flue gases are mixed in front of the dust collector 152, and after dust removal by the dust collector 152, they enter the wet desulfurization system 153, and after wet desulfurization, they enter the chimney 154 for discharge.

[0055] ③Humidity-carrying gas circulation process

[0056] The circulating air enters the lower part of the concentration absorption tower 110, and directly exchanges heat and mass with the concentrated sewage (temperature is 90°C) sprayed down, the temperature and moisture content increase, and the air is discharged (temperature is 85°C) after passing through the first demister 112 at the top of the concentration absorption tower 110. Thereafter, the air enters the lower part of the air regeneration tower 120, and after being sprayed with clean water, the temperature and moisture content decrease, and the air is discharged (temperature is 50°C) after being defogged by the second demister 122 at the top of the air regeneration tower 120, and then returns to the lower part of the concentration absorption tower 110, and the cycle repeats.

[0057] ④Desulfurization wastewater process

[0058] The desulfurized wastewater enters the sewage circulation process of the concentration absorption tower 110, and is continuously circulated and concentrated in the concentration absorption tower 110. It is heated in two stages from the bottom of the tower by the regenerator 115 and the heater 111, and then sprayed back to the bottom of the tower to form a cycle. The concentrated desulfurized wastewater (temperature is 55°C) at the bottom of the tower is sent to the atomization tower 130, mixed with compressed air to form a two-fluid atomization medium, sprayed into the interior of the atomization tower 130, and directly contacted with the flue gas (temperature is 200-300°C), and turned into dust after being evaporated. Part of the dust falls to the bottom of the atomization tower 130 and is collected, and part of the dust enters the dust collector 152 with the flue gas and is collected.

[0059] ⑤Intermediate circulating water process

[0060] The intermediate circulating water absorbs heat from the heat exchange coil 131 of the atomizing tower 130, is heated again by the standby steam heater (if necessary), enters the heater 111 to heat the desulfurized wastewater, and then returns to the heat exchange coil 131 of the atomizing tower 130, and the cycle repeats. The temperature of the circulating water entering the heat exchange coil 131 is 80°C, and the temperature of the circulating water leaving the heat exchange coil 131 is 110°C.

[0061] ⑥Water purification process

[0062] The clean water circulates continuously in the air regeneration tower 120, and after being cooled in two stages (the temperature after cooling is 45°C) by the regenerator 115 and the fresh air heater 121 at the bottom of the tower, it is sprayed back to the bottom of the tower to form a cycle. The clean water is continuously increased due to the condensation of the circulating air, and the excess clean water is returned to the desulfurization tower as the desulfurization tower makeup water.

[0063] ⑦ Compressed air process

[0064] The compressed air is divided into two paths, one path is used to purge the heat exchange coil 131 in the atomizing tower 130 to maintain its surface smooth, and the other path is used to mix with the concentrated desulfurized wastewater to form a dual-fluid spray.

[0065] Comparative Example 1

[0066] This comparative example provides a comparison of a separate flue atomization spray, where the desulfurization wastewater is directly introduced into the flue for atomization spraying.

[0067] Comparative Example 2

[0068] This comparative example provides a comparison of a single open evaporation absorption technology (CN 118579877 A), in which the desulfurization wastewater is directly introduced into the flue for atomization spraying.

[0069] According to the requirement, 10t / h of desulfurization wastewater with a solid content of 10% is subjected to zero discharge. The energy consumption of the embodiment and the comparative example is as follows:

[0070] Comparative Example 1: If the atomization spray is directly introduced into the flue normally, the heat consumed is needed to evaporate 9t / h of water. According to the evaporation of 1t / h of water, 0.7MW of heat is required, and (10-1)×0.7=6.3MW of heat is consumed. This part of heat is originally used to heat the fresh air and is not waste heat, but effective heat.

[0071] Comparative Example 2: If a single open evaporation absorption technology is used, 10t / h of desulfurized wastewater is first concentrated to 3t / h through a sewage circulation tower, consuming about 1.8MW of heat in the form of steam, and then crystallized into 1t / h of salt through a crystallizer, consuming about 1.4MW of heat. This 1.4MW of heat can be returned to the front-end concentration process in the form of secondary steam. The overall heat consumption is 1.8MW, and this 1.8MW of heat can be used to recover waste heat by heating desalted water and other media, and the overall heat consumption can be zero except for condensation loss and heat radiation loss.

[0072] According to the technical route of the embodiment of the present invention, 10t / h of water can be concentrated to 3t / h in the concentration absorption tower 110, consuming about 1.8MW of heat, which is provided by the heat exchange coil 131 in the atomization tower 130, and ultimately comes from the flue gas; in addition, 3t / h of concentrated water needs to be evaporated to 1t / h of solid in the atomization tower 130, so it needs to consume (3-1)×0.7=1.4MW of heat, and a total of 1.4+1.8=3.2MW of heat is consumed. In addition, the fresh air heater 121 can also reuse 1.8MW for fresh air, so the actual heat consumption is only 1.4MW. Compared with a simple flue atomization system, the atomization tower 130 of the embodiment of the present invention releases less heat overall (according to the above case, the atomization tower 130 needs to release about 3.2MW, which is half of the previous 6.3MW), so the required flue gas volume is also small. For some units with low flue temperature, even if all the flue gas is introduced into the bypass flue atomization tower, zero emissions cannot be achieved. The emergence of this system greatly reduces the heat that the flue needs to provide, so that units with low flue temperature can also achieve zero wastewater emissions through flue atomization.

[0073] Compared with the traditional open evaporation system with nearly zero heat consumption, this system consumes an additional 1.4MW of flue gas heat. However, the wastewater treatment system provided by the embodiment of the present invention has a simple structure, does not require the steam turbine to be modified for extraction, and has a small amount of engineering work. In addition, this system has low requirements for cold sources. Regardless of winter or summer, clean water with a minimum temperature of 45°C can be used to heat fresh air, and has higher stability. In terms of terminal treatment, flue spraying is also simpler than the crystallization system, occupies a small area, and has a low initial investment.

[0074] In summary, the present invention provides a wastewater treatment system and a wastewater treatment method combining open evaporation and flue evaporation, using open evaporation technology to concentrate and reduce desulfurized wastewater, and then spraying the concentrated desulfurized wastewater into the atomizing tower of the flue gas bypass, and the atomizing tower is also provided with a heat exchange coil to use the flue gas heat to concentrate the desulfurized wastewater. The heat discharged by the open evaporation is finally used to heat the fresh air and is not wasted. The final effective energy consumption is only the heat consumed by the evaporation of the concentrated desulfurized wastewater, the energy consumption is relatively low, and there is no need to modify the steam system, and the scope of application is wide.

[0075] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wastewater treatment system using open evaporation and flue evaporation, characterized in that: include: A concentration absorption tower, in which the gas and the heated wastewater transfer heat and mass, the moisture-carrying gas is output at the top of the concentration absorption tower, and the wastewater output at the bottom of the concentration absorption tower is heated and circulated to the concentration absorption tower to transfer heat and mass with the gas again; An air regeneration tower, wherein the top of the concentrating absorption tower is connected to the bottom of the air regeneration tower, so that the moisture-carrying gas transfers heat and mass with the clean water in the air regeneration tower, and the water in the moisture-carrying gas enters the clean water. The top of the air regeneration tower is connected to the bottom of the concentrating absorption tower, so that the gas output from the air regeneration tower enters the concentrating absorption tower, forming a moisture-carrying gas circulation; the clean water output from the bottom of the air regeneration tower is cooled and circulated to the top of the air regeneration tower, forming a clean water circulation; Atomizing tower, the concentrated sewage output from the bottom of the concentration absorption tower enters the top of the atomizing tower, and conducts heat and mass transfer with the flue gas entering from the bottom of the atomizing tower, so that the concentrated sewage is evaporated into dust; The bypass flue is used to transport flue gas to the bottom of the atomizing tower.

2. The wastewater treatment system according to claim 1, characterized in that: It also includes an air preheater, a dust collector and a wet flue gas desulfurization system. The boiler flue gas after desulfurization is divided into two paths, one path enters the bypass flue, and the other path enters the air preheater for heat exchange with fresh air. The heated fresh air is transported to the boiler, and the cooled flue gas is mixed with the flue gas output from the top of the atomizing tower and enters the dust collector for dust removal, and then enters the wet flue gas desulfurization system for desulfurization and then is discharged. The desulfurization wastewater output from the wet flue gas desulfurization system enters the concentration absorption tower after being heated.

3. The wastewater treatment system according to claim 1 or 2, characterized in that: It also includes a heater for heating wastewater, and the wastewater enters the concentration absorption tower after being heated by the heater; A heat exchange coil is arranged inside the atomizing tower, and the heat exchange coil has a feed port and a discharge port; the feed port of the heat exchange coil is connected to the heat source outlet of the heater, and the discharge port of the heat exchange coil is connected to the heat source inlet of the heater, forming an intermediate hot water circulation.

4. The wastewater treatment system according to claim 3, characterized in that: A first demister is disposed on the top of the concentration absorption tower, a first spray pipeline is disposed below the first demister, and the heated wastewater output by the heater enters the first spray pipeline; A first mass transfer filler is arranged below the first spray pipeline.

5. The wastewater treatment system according to claim 4, characterized in that: It also includes a compressed air purge pipeline, and a plurality of purge gas inlets are arranged from top to bottom on the concentration absorption tower corresponding to the position of the heat exchange coil, and each of the purge gas inlets is connected to the compressed air purge pipeline; The concentrated sewage output from the bottom of the concentration absorption tower is mixed with the compressed air output from the compressed air purge pipeline and then enters the top of the atomization tower.

6. The wastewater treatment system according to claim 3, characterized in that: A spiral guide plate is arranged below the heat exchange coil in the atomizing tower to make the smoke rise in a rotating manner.

7. The wastewater treatment system according to claim 3, characterized in that: It also includes a regenerator, in which the wastewater output from the bottom of the concentration absorption tower and the clean water output from the bottom of the air regeneration tower exchange heat, and the heated wastewater enters the heater for further heating and then returns to the concentration absorption tower.

8. The wastewater treatment system according to claim 7, characterized in that: It also includes a fresh air heater. The cooled clean water output by the regenerator enters the fresh air heater for further cooling and then returns to the air regeneration tower. The heated fresh air output by the fresh air heater enters the air preheater for heat exchange with the flue gas.

9. The wastewater treatment system according to claim 1, characterized in that: A second demister is disposed on the top of the air regeneration tower, and a second spray pipeline is disposed below the second demister, and the cooled purified water enters the second spray pipeline; A second mass transfer filler is arranged below the second spray pipeline.

10. A method for treating wastewater, characterized in that: Wastewater treatment is carried out using the wastewater treatment system described in any one of claims 1 to 9.

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