A high-efficiency desulfurization wastewater zero discharge system and method with segmented implementation of smoke water cooperation
The high-efficiency desulfurization wastewater zero-discharge system, which achieves flue gas and water synergy in stages, utilizes a two-stage evaporation and drying process involving high-temperature bypass flue gas and desulfurization wastewater. This solves the problems of high system installation space requirements and limited water volume in existing technologies, and achieves a highly efficient and stable zero-discharge effect for wastewater.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUANENG CHANGJIANG ENVIRONMENTAL PROTECTION TECH CO LTD
- Filing Date
- 2023-12-05
- Publication Date
- 2026-05-19
AI Technical Summary
Existing zero-discharge technologies for desulfurization wastewater have problems in engineering applications, such as high requirements for system installation location and space, easy scaling, corrosion, and blockage. In addition, the evaporation volume is greatly affected by the unit load, resulting in increased investment costs.
A high-efficiency desulfurization wastewater zero-discharge system that achieves flue gas and water synergy in stages is adopted. High-temperature bypass flue gas is drawn out from the boiler flue and evaporated with desulfurization wastewater sprayed from atomizing nozzles in the high-temperature flue. Then, it enters a small SCR reactor for NOx catalytic reduction and then enters an evaporator for further evaporation and drying, realizing two-stage waste heat utilization.
It achieves zero discharge of highly efficient desulfurization wastewater, improves water treatment capacity, reduces land area and investment costs, and ensures stable system operation.
Smart Images
Figure CN117645334B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of desulfurization wastewater treatment, and relates to a highly efficient desulfurization wastewater zero-discharge system and method for achieving flue gas-water synergy in stages. Background Technology
[0002] The desulfurization wastewater generated by wet flue gas desulfurization in thermal power plants is complex in quality and fluctuates greatly in volume. It is characterized by high hardness, high salinity, high turbidity, and strong corrosivity. Achieving zero discharge of desulfurization wastewater can greatly reduce the environmental pollution risk of desulfurization wastewater and has significant environmental and social benefits.
[0003] Flue gas evaporation technology for desulfurization wastewater is a crucial component of current "zero-emission" technologies for flue gas desulfurization wastewater. Direct evaporation technology for desulfurization wastewater involves atomizing desulfurization wastewater using gas-liquid two-phase flow nozzles and injecting it into the flue gas duct between the air preheater and the dust collector. The wastewater is completely evaporated using the waste heat of the flue gas, converting pollutants into crystals or salts, which are then collected by the dust collector along with fly ash. Practical engineering applications have shown that direct evaporation using the flue gas duct between the air preheater and the dust collector can effectively reduce investment costs; however, it also leads to higher requirements for installation location and space, and necessitates strict control of the downstream flue gas flow field, making it unsuitable for some power plants. Furthermore, it is prone to incomplete evaporation of desulfurization wastewater, resulting in problems such as scaling, corrosion, and blockage of the flue gas duct, making subsequent maintenance difficult. The desulfurization wastewater bypass flue evaporation technology connects a bypass flue from the air preheater inlet to the air preheater outlet flue, extracting a small amount of high-temperature flue gas (300-350℃) from before the air preheater. Within the bypass flue, the wastewater and high-temperature flue gas are directly mixed and evaporated for solidification. Because the bypass flue inlet and outlet are isolated from the main boiler flue via baffles (doors), the flexibility of the desulfurization wastewater bypass flue evaporation technology is improved, ensuring stable power plant operation. However, in practical engineering applications, the evaporation volume is significantly affected by the unit load, and the extracted flue gas volume usually needs to be controlled within 5% of the total flue gas volume. Therefore, when the power plant's desulfurization wastewater volume is large, the use of this technology is limited, necessitating the addition of a thermal concentration and volume reduction system, thus increasing investment costs. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a highly efficient desulfurization wastewater zero-discharge system and method for staged flue gas heat energy utilization to achieve zero discharge of large volume desulfurization wastewater.
[0005] To achieve the above objectives, this invention discloses a high-efficiency desulfurization wastewater zero-discharge system that achieves flue gas and water synergy in stages, including a boiler flue, a desulfurization tower, a chimney, a flue gas inlet electric valve, a high-temperature flue, an evaporator, an ash conveying device, a compressed air storage tank, and an ammonia / urea tank.
[0006] The boiler flue outlet is connected to the inlet of the chimney via the desulfurization tower. The boiler flue is equipped with a flue gas extraction port and a flue gas return port. The flue gas extraction port is connected to the flue gas inlet of the evaporator via a flue gas inlet electric valve and a high-temperature flue. The high-temperature flue is equipped with an atomizing nozzle device, a first thermocouple, an atomizing nozzle and a small SCR reactor in sequence along the flue gas flow direction.
[0007] The outlet of the slurry pool at the bottom of the desulfurization tower is connected to the inlet of the atomizing nozzle device and the inlet of the evaporator. The flue gas outlet of the evaporator is connected to the return flue gas port. The particle outlet at the bottom of the evaporator is connected to the ash conveying device. The outlet of the compressed air storage tank is divided into two paths, one of which is connected to the ash conveying device and the other is connected to the inlet of the atomizing nozzle device and the inlet of the atomizing nozzle. The outlet of the ammonia / urea tank is connected to the inlet of the atomizing nozzle.
[0008] An economizer, an SCR reactor, an air preheater, and a dust collector are sequentially installed in the boiler flue along the flue gas flow direction.
[0009] The flue gas inlet, economizer, SCR reactor, air preheater, flue gas return inlet, and dust collector are distributed sequentially along the flue gas flow direction.
[0010] It also includes a desulfurization wastewater tank, a desulfurization wastewater pump, a first spray regulating valve, a second spray regulating valve, a second thermocouple, and a flue gas outlet valve;
[0011] The outlet of the slurry pool at the bottom of the desulfurization tower is divided into two paths after passing through the desulfurization wastewater tank and the desulfurization wastewater pump. One path is connected to the inlet of the atomizing nozzle device via the first spray regulating valve, and the other path is connected to the inlet of the evaporator via the second spray regulating valve.
[0012] The flue gas outlet of the evaporator is connected to the return flue gas port via a second thermocouple and a flue gas outlet valve.
[0013] It also includes an ash conveying compressed air regulating valve, a wastewater compressed air regulating valve, and a spray compressed air regulating valve; the outlet of the compressed air storage tank is divided into two paths, one of which is connected to the ash conveying device via the ash conveying compressed air regulating valve, and the other path is connected to one end of the wastewater compressed air regulating valve and one end of the spray compressed air regulating valve. The other end of the wastewater compressed air regulating valve is connected to the atomizing nozzle device, and the other end of the spray compressed air regulating valve is connected to the inlet of the atomizing nozzle.
[0014] The outlet of the ammonia / urea tank is connected to the inlet of the atomizing nozzle via a denitrification pump and a denitrification regulating valve.
[0015] This invention discloses a highly efficient method for achieving zero discharge of desulfurization wastewater through segmented flue gas and wastewater synergy, comprising the following steps:
[0016] The high-temperature hot flue gas from the boiler enters the chimney through the boiler flue. The bypass flue gas drawn through the flue gas outlet enters the evaporator through the high-temperature flue. The bypass flue gas flows through the atomizing nozzle device through the high-temperature flue and directly contacts and exchanges heat with the atomized desulfurization wastewater sprayed by the atomizing nozzle device in the high-temperature flue, forming countercurrent / co-current spray evaporation. The wastewater is evaporated using the high-temperature bypass flue gas in the high-temperature flue.
[0017] The bypass flue gas flowing through the atomizing nozzle device then enters the inlet of the small SCR reactor, where it mixes with the liquid ammonia / urea solution sprayed into the high-temperature flue by the atomizing nozzle and flows through the catalyst layer of the small SCR reactor to carry out the catalytic reduction of NOx in the bypass flue gas; then it enters the evaporator to release heat, and then enters the boiler flue through the return flue gas port.
[0018] The desulfurization wastewater output from the desulfurization tower is sent to the mechanical atomization device at the top of the evaporator. The mechanical atomization device atomizes the wastewater into fine droplets, which then come into contact with and mix with the bypass flue gas entering the evaporator, carrying out heat and mass transfer. Some of the dried products are carried into the boiler flue along with the bypass flue gas; the other part of the dried products combine with the dust carried in the bypass flue gas to form solid products, which fall to the bottom of the evaporator and then enter the ash conveying device.
[0019] The bypass flue gas temperature entering the small SCR reactor is 300-350℃.
[0020] The flue gas temperature at the evaporator outlet is 140-180℃.
[0021] The flow rate of flue gas entering the high-temperature flue per unit time is less than or equal to 5% of the total flue gas flow rate of the boiler flue.
[0022] The present invention has the following beneficial effects:
[0023] The high-efficiency desulfurization wastewater zero-discharge system and method for segmented flue gas and water co-processing described in this invention, in specific operation, draws a high-temperature bypass flue gas from the boiler flue. First, within the high-temperature flue, partial desulfurization wastewater is evaporated and dried via two-phase flow atomization, achieving the first stage of high-temperature flue gas waste heat utilization. After the first stage of waste heat utilization, the flue gas temperature decreases, becoming suitable for the denitrification catalyst in the small SCR reactor, achieving catalytic reduction of NOx in the bypass flue gas. Subsequently, the high-temperature bypass flue gas enters the evaporator, where partial desulfurization wastewater is evaporated and dried again via mechanical atomization, achieving the second stage of high-efficiency utilization of high-temperature flue gas waste heat. After the second stage of waste heat utilization, the flue gas temperature decreases again, and finally returns to the boiler flue. Through flue gas and water co-processing, the segmented high-temperature flue gas waste heat is utilized efficiently, achieving zero discharge of desulfurization wastewater and increasing the treated water volume.
[0024] Furthermore, the design of the bypass flue inlet and outlet isolation valves achieves isolation from the main body of the power plant boiler, without affecting the daily operation of the power plant; at the same time, the bypass flue can make full use of the gaps between flues, with a small footprint and investment cost, and flexible project implementation.
[0025] Furthermore, by coordinating the opening of the flue gas inlet electric valve and the opening of the first spray regulating valve, the bypass flue gas temperature at the inlet of the small SCR reactor can be flexibly controlled to meet the requirements for continuous ammonia injection into the catalyst, avoiding low efficiency of the catalyst at low temperatures or side reactions at high temperatures, thus ensuring the stable and reliable operation of the bypass flue gas denitrification system. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the system composition of the present invention.
[0027] Among them, 1 is the boiler flue, 2 is the economizer, 3 is the SCR reactor, 3-1 is the small SCR reactor, 4 is the air preheater, 5 is the dust collector, 6 is the desulfurization tower, 7 is the chimney, 8 is the high-temperature flue, 9 is the flue gas inlet electric valve, 10 is the atomizing nozzle device, 11 is the first thermocouple, 12 is the evaporator, 13 is the second thermocouple, 14 is the flue gas outlet valve, 15 is the desulfurization wastewater tank, 16 is the desulfurization wastewater pump, 17 is the first spray regulating valve, 18 is the second spray regulating valve, 19 is the compressed air storage tank, 20 is the ammonia / urea tank, 21 is the denitrification pump, 22 is the denitrification regulating valve, 23 is the spray compressed air regulating valve, 24 is the ash conveying compressed air regulating valve, 25 is the ash conveying device, and 26 is the wastewater compressed air regulating valve. Detailed Implementation
[0028] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.
[0029] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.
[0030] refer to Figure 1 The high-efficiency desulfurization wastewater zero-discharge system for segmented flue gas and water synergy described in this invention includes a boiler flue 1, an economizer 2, an SCR reactor 3, a small SCR reactor 3-1, an air preheater 4, a dust collector 5, a desulfurization tower 6, a chimney 7, a high-temperature flue 8, a flue gas inlet electric valve 9, an atomizing nozzle device 10, a first thermocouple 11, an evaporator 12, a second thermocouple 13, a flue gas outlet valve 14, a desulfurization wastewater tank 15, a desulfurization wastewater pump 16, a first spray regulating valve 17, a second spray regulating valve 18, a compressed air storage tank 19, an ammonia / urea tank 20, a denitrification pump 21, a denitrification regulating valve 22, a spray compressed air regulating valve 23, an ash conveying compressed air regulating valve 24, an ash conveying device 25, and a wastewater compressed air regulating valve 26.
[0031] The outlet of boiler flue 1 is connected to the inlet of chimney 7 via desulfurization tower 6. Economizer 2, SCR reactor 3, air preheater 4 and dust collector 5 are arranged sequentially along the flue gas flow direction inside boiler flue 1. Flue gas extraction port and flue gas return port are provided on boiler flue 1. The flue gas extraction port, economizer 2, SCR reactor 3, air preheater 4, flue gas return port and dust collector 5 are distributed sequentially along the flue gas flow direction.
[0032] The flue gas inlet is connected to the flue gas inlet of the evaporator 12 via the flue gas inlet electric valve 9 and the high-temperature flue 8. The high-temperature flue 8 is provided with an atomizing nozzle device 10, a first thermocouple 11, an atomizing nozzle and a small SCR reactor 3-1 in sequence along the flue gas flow direction.
[0033] The outlet of the slurry pool at the bottom of the desulfurization tower 6 is divided into two paths after passing through the desulfurization wastewater tank 15 and the desulfurization wastewater pump 16. One path is connected to the inlet of the atomizing nozzle device 10 via the first spray regulating valve 17, and the other path is connected to the inlet of the evaporator 12 via the second spray regulating valve 18. The flue gas outlet of the evaporator 12 is connected to the return flue gas port via the second thermocouple 13 and the flue gas outlet valve 14.
[0034] The particle outlet at the bottom of the evaporator 12 is connected to the ash conveying device 25. The outlet of the compressed air storage tank 19 is divided into two paths. One path is connected to the ash conveying device 25 via the ash conveying compressed air regulating valve 24. The other path is connected to one end of the wastewater compressed air regulating valve 26 and one end of the spray compressed air regulating valve 23. The other end of the wastewater compressed air regulating valve 26 is connected to the atomizing nozzle device 10, and the other end of the spray compressed air regulating valve 23 is connected to the inlet of the atomizing nozzle.
[0035] The outlet of the ammonia / urea tank 20 is connected to the inlet of the atomizing nozzle via the denitrification pump 21 and the denitrification regulating valve 22.
[0036] refer to Figure 1The efficient desulfurization wastewater zero-discharge method for segmented flue gas and water synergy described in this invention includes the following steps:
[0037] The high-temperature flue gas (450-550℃) from the boiler flows sequentially through the economizer 2, SCR reactor 3, air preheater 4, dust collector 5, desulfurization tower 6 and chimney 7 via boiler flue 1, and is finally discharged through chimney 7.
[0038] The bypass flue gas drawn through the flue gas extraction port enters the evaporator 12 through the high-temperature flue 8. The flow rate of the flue gas entering the high-temperature flue 8 is controlled by adjusting the opening of the flue gas inlet electric valve 9, ensuring that the flow rate of the flue gas entering the high-temperature flue 8 per unit time does not exceed 5% of the total flue gas flow rate of the boiler flue 1. The bypass flue gas flows through the high-temperature flue 8 and passes through the atomizing nozzle device 10, where it directly contacts and exchanges heat with the atomized desulfurization wastewater sprayed by the atomizing nozzle device 10, forming countercurrent / co-current spray evaporation. The high-temperature bypass flue gas is used to evaporate the wastewater in the high-temperature flue 8, while simultaneously reducing the flue gas temperature flowing through the atomizing nozzle device 10. The flue gas temperature is controlled between 300-350℃. In this stage, the waste heat utilization of the high-temperature flue gas in the first stage and the evaporation and zero discharge of desulfurization wastewater are achieved.
[0039] The bypass flue gas flowing through the atomizing nozzle device 10 then enters the inlet of the small SCR reactor 3-1, where it mixes with the liquid ammonia / urea solution sprayed into the high-temperature flue 8 by the atomizing nozzle and flows through the catalyst layer of the small SCR reactor 3-1 for catalytic reduction of NOx in the bypass flue gas; then it enters the evaporator 12 to release heat, and then enters the boiler flue 1 through the return flue gas port.
[0040] The desulfurization wastewater is pumped by the desulfurization wastewater pump 16 into the mechanical atomization device at the top of the evaporator 12. The mechanical atomization device atomizes the wastewater into fine droplets, which then come into contact with and mix with the bypass flue gas (300-350℃) entering the evaporator 12, carrying out heat and mass transfer, i.e., evaporation and drying. Some of the dried products are carried into the boiler flue 1 by the bypass flue gas, and then enter the dust collector 5, where they are captured along with the dust. Another part of the dried products combines with the dust carried in the bypass flue gas to form solid products, which fall to the bottom of the evaporator 12 and then enter the ash conveying device 25 for treatment and discharge. In this stage, the waste heat of the high-temperature flue gas in the second stage is efficiently utilized, thereby achieving true zero discharge of desulfurization wastewater.
[0041] The inlet water flow rate into the atomizing nozzle device 10 is adjusted by controlling the opening of the first spray regulating valve 17, and the inlet water flow rate into the mechanical atomizing device at the top of the evaporator 12 is adjusted by controlling the opening of the second spray regulating valve 18. At the same time, the compressed air flow rate into the atomizing nozzle device 10 is controlled by adjusting the wastewater compressed air regulating valve 26, so as to achieve a stable atomization effect of desulfurization wastewater at the outlet of the atomizing nozzle device 10 (droplet size 15-55μm).
[0042] The bypass flue gas temperature entering the small SCR reactor 3-1 is monitored in real time by the first thermocouple 11. The flue gas flow rate in the high-temperature flue duct 8 is controlled by adjusting the opening of the flue gas inlet electric valve 9. The water flow rate of the atomizing nozzle device 10 is controlled by adjusting the opening of the first spray regulating valve 17. In this way, the bypass flue gas temperature entering the small SCR reactor 3-1 is controlled at the set temperature, which is 300-350℃.
[0043] The flue gas temperature at the outlet of the evaporator 12 is monitored in real time by the second thermocouple 13. The water flow rate into the mechanical atomizing device at the top of the evaporator 12 is adjusted by controlling the opening of the second spray regulating valve 18, thereby controlling the flue gas temperature at the outlet of the evaporator 12 to be within a set temperature, which is 140-180℃.
[0044] 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, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.
Claims
1. A highly efficient desulfurization wastewater zero-discharge system that achieves segmented flue gas-water synergy, characterized in that, Includes boiler flue (1), desulfurization tower (6), chimney (7), flue gas inlet electric valve (9), high temperature flue (8), evaporator (12), ash conveying device (25), compressed air storage tank (19) and ammonia / urea tank (20); The outlet of the boiler flue (1) is connected to the inlet of the chimney (7) via the desulfurization tower (6). The boiler flue (1) is provided with a flue gas extraction port and a flue gas return port. The flue gas extraction port is connected to the flue gas inlet of the evaporator (12) via the flue gas inlet electric valve (9) and the high-temperature flue (8). The high-temperature flue (8) is provided with an atomizing nozzle device (10), a first thermocouple (11), an atomizing nozzle and a small SCR reactor (3-1) in sequence along the flue gas flow direction. The outlet of the slurry pool at the bottom of the desulfurization tower (6) is connected to the inlet of the atomizing nozzle device (10) and the inlet of the evaporator (12). The flue gas outlet of the evaporator (12) is connected to the flue gas return port. The particle outlet at the bottom of the evaporator (12) is connected to the ash conveying device (25). The outlet of the compressed air storage tank (19) is divided into two paths, one of which is connected to the ash conveying device (25), and the other is connected to the inlet of the atomizing nozzle device (10) and the inlet of the atomizing nozzle. The outlet of the ammonia / urea tank (20) is connected to the inlet of the atomizing nozzle. An economizer (2), an SCR reactor (3), an air preheater (4), and a dust collector (5) are arranged sequentially along the flue gas flow direction inside the boiler flue (1). The flue gas inlet, economizer (2), SCR reactor (3), air preheater (4), flue gas return inlet and dust collector (5) are distributed in sequence along the flue gas flow direction.
2. The high-efficiency desulfurization wastewater zero-discharge system for segmented flue gas and water co-processing as described in claim 1, characterized in that, It also includes a desulfurization wastewater tank (15), a desulfurization wastewater pump (16), a first spray regulating valve (17), a second spray regulating valve (18), a second thermocouple (13), and a flue gas outlet valve (14). The outlet of the slurry pool at the bottom of the desulfurization tower (6) is divided into two paths after passing through the desulfurization wastewater tank (15) and the desulfurization wastewater pump (16). One path is connected to the inlet of the atomizing nozzle device (10) via the first spray regulating valve (17), and the other path is connected to the inlet of the evaporator (12) via the second spray regulating valve (18). The flue gas outlet of the evaporator (12) is connected to the return flue gas port via the second thermocouple (13) and the flue gas outlet valve (14).
3. The high-efficiency desulfurization wastewater zero-discharge system for segmented flue gas and water co-processing as described in claim 1, characterized in that, It also includes an ash conveying compressed air regulating valve (24), a wastewater compressed air regulating valve (26), and a spray compressed air regulating valve (23); the outlet of the compressed air storage tank (19) is divided into two paths, one of which is connected to the ash conveying device (25) via the ash conveying compressed air regulating valve (24), and the other path is connected to one end of the wastewater compressed air regulating valve (26) and one end of the spray compressed air regulating valve (23). The other end of the wastewater compressed air regulating valve (26) is connected to the atomizing nozzle device (10), and the other end of the spray compressed air regulating valve (23) is connected to the inlet of the atomizing nozzle.
4. The high-efficiency desulfurization wastewater zero-discharge system for segmented flue gas and water co-processing as described in claim 1, characterized in that, The outlet of the ammonia / urea tank (20) is connected to the inlet of the atomizing nozzle via the denitrification pump (21) and the denitrification regulating valve (22).
5. A highly efficient method for achieving zero discharge of desulfurization wastewater through segmented flue gas and wastewater synergy, characterized in that, The high-efficiency desulfurization wastewater zero-discharge system based on the segmented flue gas and water synergy system described in claim 1 includes the following steps: The high-temperature hot flue gas from the boiler enters the chimney (7) through the boiler flue (1). The bypass flue gas drawn through the flue gas outlet enters the evaporator (12) through the high-temperature flue (8). The bypass flue gas flows through the atomizing nozzle device (10) through the high-temperature flue (8) and directly contacts the atomized desulfurization wastewater sprayed by the atomizing nozzle device (10) in the high-temperature flue (8) to exchange heat, forming countercurrent / co-current spray evaporation. The high-temperature bypass flue gas is used to evaporate the wastewater in the high-temperature flue (8). The bypass flue gas flowing through the atomizing nozzle device (10) then enters the inlet of the small SCR reactor (3-1), mixes with the liquid ammonia / urea solution sprayed into the high-temperature flue (8) by the atomizing nozzle, and then flows through the catalyst layer of the small SCR reactor (3-1) to carry out the catalytic reduction of NOx in the bypass flue gas; then it enters the evaporator (12) to release heat, and then enters the boiler flue (1) through the return flue gas port; The desulfurization wastewater output from the desulfurization tower (6) is sent to the mechanical atomization device at the top of the evaporator (12). The mechanical atomization device atomizes the wastewater into fine droplets, which then come into contact with and mix with the bypass flue gas entering the evaporator (12) to carry out heat and mass transfer. Some of the dried products are carried into the boiler flue (1) along with the bypass flue gas. The other part of the dried products combine with the dust carried in the bypass flue gas to form solid products, which fall to the bottom of the evaporator (12) and then enter the ash conveying device (25).
6. The method for achieving efficient zero discharge of desulfurization wastewater through segmented flue gas and water co-processing according to claim 5, characterized in that, The bypass flue gas temperature entering the small SCR reactor (3-1) is 300-350℃.
7. The method for achieving efficient zero discharge of desulfurization wastewater through segmented flue gas and water co-processing according to claim 5, characterized in that, The flue gas temperature at the outlet of the evaporator (12) is 140-180℃.
8. The method for achieving efficient zero discharge of desulfurization wastewater through segmented flue gas and water co-processing according to claim 5, characterized in that, The flue gas flow rate entering the high-temperature flue (8) per unit time is less than or equal to 5% of the total flue gas flow rate of the boiler flue (1).