Bypass flue gas evaporation system for zero emission of desulfurization wastewater

Abstract

The invention belongs to the technical field of desulfurization wastewater treatment, and particularly relates to a bypass flue gas evaporation system for zero emission of desulfurization wastewater, which comprises two units, outlet flues of a denitration system A reactor and a denitration system B reactor are both connected with a bypass high-temperature flue gas system, and the bypass high-temperature flue gas system is connected with a high-temperature flue gas three-way valve group device. The high-temperature flue gas three-way valve group device is connected with the top end of the drying tower, the bottom end of the drying tower is connected with the low-temperature flue gas three-way valve group device, the low-temperature flue gas three-way valve group device is connected with the bypass low-temperature flue gas system, outlet flues of reactors A and B of the denitration system are correspondingly connected with air preheaters A and B, and outlet flues of the air preheaters A and B are correspondingly connected with dust removers A and B; two branch pipes of the bypass low-temperature flue gas system are correspondingly connected with outlet flues of the air preheater A and the air preheater B, the structure of the other unit is the same as the connection relation of the unit, the two units share the high-temperature flue gas three-way valve set device, the low-temperature flue gas three-way valve set device and the drying tower, the system can switch flue gas operation modes, and the wastewater treatment capacity is stable.

Description

Technical Field

[0001] The invention belongs to the technical field of desulfurization wastewater treatment, and in particular relates to a bypass flue gas evaporation system for zero discharge of desulfurization wastewater. Background Art

[0002] In recent years, the flue gas drying and evaporation system for zero emission of desulfurized wastewater has been widely used in the transformation of new units or old units for zero emission of desulfurized wastewater due to its simple process, easy maintenance, no solid waste generation, and strong adaptability to the water quality of desulfurized wastewater. The working principle of this system is to extract a certain amount of high-temperature flue gas from the inlet of the boiler air preheater to the drying and evaporation tower. In the drying and evaporation tower, the desulfurized wastewater is dispersed into nano-scale droplets by a high-speed rotary atomizer and contacts with the high-temperature flue gas. The water in the wastewater is evaporated instantly and goes to the downstream electrostatic precipitator system with the high-temperature flue gas. The solid particles and salt substances in the wastewater are dried and transported to the ash storage by compressed air and mixed with fly ash for comprehensive utilization.

[0003] The traditional flue gas evaporation system for desulfurization wastewater bypass is a unit arrangement, that is, one unit and one tower. Each unit is equipped with a set of bypass flue gas evaporation system to treat desulfurization wastewater. This system has some problems in the transformation of old units, investment and operation costs, and actual operation: (1) For the same amount of wastewater, the "one unit, one tower" model occupies a large area, has high investment and operating costs, and in particular, the renovation of old units has practical problems such as limited space, difficult system layout and construction; (2) The desulfurization wastewater system is conventionally designed as a public system, that is, multiple units share a wastewater treatment system. In actual operation, when a main engine stops operating or fails, the corresponding evaporation system also stops operating, resulting in a reduction in the desulfurization wastewater treatment volume. At the same time, the wastewater treatment facilities of the unit are idle and wasted; (3) During the deep peak regulation period of the main unit, when the boiler load is low, the flue gas temperature and flow rate decrease, the corresponding bypass flue gas evaporation system operates unstably, the wastewater treatment volume is unstable, and the flue gas evaporation tower is prone to ash blockage during operation, which reduces the boiler thermal efficiency and economic performance of the main unit. Summary of the invention

[0004] The purpose of the present invention is to provide a bypass flue gas evaporation system for zero discharge of desulfurization wastewater, so as to solve the problems that the traditional model occupies a large area, has high cost, the evaporation system stops operating due to host failure, the flue gas temperature and flow rate decrease when the desulfurization wastewater treatment volume is small and the boiler load is low, the corresponding bypass flue gas evaporation system operates unstable, the wastewater treatment volume is unstable and the flue gas evaporation tower is prone to ash blockage during operation.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: A bypass flue gas evaporation system for zero discharge of desulfurized wastewater comprises two units, wherein a single unit comprises a denitration system, a bypass high-temperature flue gas system, a high-temperature flue gas three-way valve group device, a drying tower, a low-temperature flue gas three-way valve group device, a bypass low-temperature flue gas system and an air preheater, wherein the denitration system comprises a denitration system A reactor and a denitration system B reactor, wherein the air preheater comprises an A air preheater and a B air preheater, wherein the outlet flues of the denitration system A reactor and the denitration system B reactor are both connected to the bypass high-temperature flue gas system, wherein the bypass high-temperature flue gas system is connected to a branch pipeline of the high-temperature flue gas three-way valve group device, wherein the main pipeline of the high-temperature flue gas three-way valve group device is connected to the top of the drying tower, and the bottom of the drying tower is connected to the main pipeline of the low-temperature flue gas three-way valve group device A branch pipe of the low-temperature flue gas three-way valve group device is connected to the bypass low-temperature flue gas system, the outlet flue of the A reactor of the denitrification system is connected to the A air preheater, the outlet flue of the A air preheater is connected to the A dust collector, the outlet flue of the B reactor of the denitrification system is connected to the B air preheater, the outlet flue of the B air preheater is connected to the B dust collector, a branch pipe of the bypass low-temperature flue gas system is connected to the A air preheater outlet flue, another branch pipe of the bypass low-temperature flue gas system is connected to the B air preheater outlet flue, the A dust collector is connected to the A induced draft fan, the B dust collector is connected to the B induced draft fan, the structure of the other unit is the same as the connection relationship of the unit, and the two units share the high-temperature flue gas three-way valve group device, the drying tower and the low-temperature flue gas three-way valve group device.

[0006] Preferably, the high-temperature flue gas three-way valve group device and the low-temperature flue gas three-way valve group device have the same structure, both comprising a main pipeline, two branch pipelines and a guide plate, and the branch pipelines are both provided with a smoke isolation door.

[0007] Preferably, guide plates are welded at the confluence of flue gases in branch pipes of the high-temperature flue gas three-way valve assembly device and the low-temperature flue gas three-way valve assembly device. The two guide plates are arc-shaped and made of the same material as the flue. Their function is to change the direction of flue gas flow and prevent ash accumulation.

[0008] Preferably, the arc diameter of the guide plate is the radius of the branch pipe, the height of the guide plate is the diameter of the branch pipe, the arc length of the guide plate is 1 / 4 of the cross-sectional area of ​​the tee branch pipe, and the welding method of the two guide plates and the branch pipe is full welding.

[0009] Preferably, the main pipeline and the branch pipeline are connected by a feed plate, the top of the feed plate is 200 mm away from the branch pipeline, and the bottom of the feed plate is 200 mm away from the main pipeline. The material is the same as that of the flue, and the feed plate and the main pipeline are fully welded.

[0010] Preferably, the bypass high-temperature flue gas system includes a bypass high-temperature A flue, a bypass high-temperature B flue and a bypass high-temperature main pipe flue. The bypass high-temperature A flue is connected to the denitrification system A reactor, with a high-temperature flue gas damper door A provided therebetween. The bypass high-temperature B flue is connected to the denitrification system B reactor, with a high-temperature flue gas damper door B provided therebetween. The bypass high-temperature main pipe flue is connected to a branch pipe of a high-temperature flue gas three-way valve group device.

[0011] Preferably, the bypass low-temperature flue gas system includes a bypass low-temperature A flue, a bypass low-temperature B flue and a bypass low-temperature main pipe flue, the bypass low-temperature main pipe flue is connected to a branch pipe of a low-temperature flue gas three-way valve group device, the bypass low-temperature A flue is connected to an A dust collector, and a low-temperature flue gas damper door A is provided therebetween, and the bypass low-temperature B flue is connected to a B dust collector, and a low-temperature flue gas damper door B is provided therebetween.

[0012] Working principle: The zero-emission system for desulfurization wastewater also includes a low-temperature flash evaporation concentration system. The desulfurization wastewater is transported to the low-temperature flash evaporation concentration system through a wastewater feed pump. The wastewater is flash-evaporated and concentrated step by step in the first, second and third-effect heating evaporation separation system. The secondary steam generated by the flash evaporation is condensed and recovered to the desulfurization process water tank. The concentrated brine is sent to the drying tower for drying and evaporation. The bypass flue gas evaporation system with zero emission of desulfurization wastewater has only one drying tower for two units. The high-temperature flue gas is taken from two units, one for use and one for backup. The brine is atomized into nano-sized droplets by a high-speed rotary atomizer and contacts and mixes with the high-temperature hot flue gas passing through the gas distributor in the drying tower for heat and mass transfer. The water in the brine evaporates and enters the dust collector together with the flue gas. The dried salt substances in the brine are transported to the ash storage through the pneumatic ash conveying system and mixed with fly ash for comprehensive utilization.

[0013] The boiler flue gas removes nitrogen oxides in the reactor of the denitrification system and then enters the air preheater, where it exchanges heat with the primary air and secondary air required by the boiler. After the heat exchange, the boiler flue gas enters the dust collector for dust removal. The dust-removed flue gas is transported to the desulfurization system through the induced draft fan for reaction and then discharged to the chimney.

[0014] Part of the high-temperature flue gas is extracted from the outlet flue of the A and B reactors of the denitrification system of each unit. The two bypass high-temperature flue gases of each unit are combined and then sent to the inlet of the drying tower through the high-temperature flue gas three-way valve group. The high-temperature flue gas is heat exchanged and cooled with the wastewater after high-speed rotary atomization in the drying tower before it reaches the outlet of the drying tower. After passing through the two branches of the low-temperature flue gas three-way valve group, it enters the low-temperature flue gas duct of each unit respectively. After being separated into two routes, it enters the outlet flue of the AB air preheater of each unit respectively. After entering the AB dust collector of each unit, the flue gas is extracted to the desulfurization system through the induced draft fan.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The flue gas evaporation system adopts a "two-machine one-tower" configuration, with only one drying tower. The flue gas is led out from the outlet flue of the reactor of the denitrification system of the two units to the bypass high-temperature flue gas system, and then led out from the two bypass high-temperature flue gas systems to a main pipe through a three-way valve group device, and connected to the inlet flue of the drying tower. The design of two units sharing one drying tower has a small footprint, low investment and operating costs, and is particularly suitable for the renovation of old units with limited space. For treating the same amount of wastewater, the "two-machine one-tower" flue gas evaporation system has a low maintenance cost and reduces the workload of DCS system monitoring and adjustment for operators; (2) Two systems, one for backup and one for use, are used to back up each other. The operation mode of the flue gas evaporation system is selectively switched according to the load fluctuation of the main unit and the pressure difference of the air preheater. The desulfurization wastewater treatment capacity is stable, and the overall operation of the main unit is safe, economical and stable; (3) Two arc-shaped guide plates are installed in the two pipes of the three-way valve group device used at the flue confluence, which makes the flue gas flow field uniform. The wear and ash accumulation probability of the flue at the three-way confluence of the flue gases of the two units is greatly reduced, thereby improving the thermal efficiency of the boiler and stabilizing the flue gas flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a structural schematic diagram of the high-temperature flue gas three-way valve assembly device of the present invention; Figure 3 It is a structural schematic diagram of the low-temperature flue gas three-way valve group device of the present invention.

[0017] Explanation of reference numerals: 10, 1# unit denitration system; 101, 1# denitration system A reactor; 102, 1# denitration system B reactor; 11, 1# unit bypass high-temperature flue gas system; 111, 1# unit bypass high-temperature A flue; 112, 1# unit bypass high-temperature B flue; 113, 1# unit bypass high-temperature mother pipe flue; 114, 1# unit high-temperature flue gas A damper door; 115, 1# unit high-temperature flue gas B damper door; 12, 1# unit bypass low-temperature flue gas system; 121, 1# unit bypass low-temperature A flue; 122, 1# unit bypass low-temperature B flue; 123, 1# unit bypass low-temperature mother pipe flue; 124, 1# unit low-temperature flue gas A damper door; 125, 1# unit low B damper door of hot flue gas; 13, air preheater of unit 1#; 131, air preheater of unit 1#; 132, air preheater of unit 1#; 14, dust collector of unit 1#; 141, dust collector of unit 1#; 142, dust collector of unit 1#; 15, induced draft fan of unit 1#; 151, induced draft fan of unit 1#; 152, induced draft fan of unit 1#; 20, denitration system of unit 2#; 201, reactor of denitration system A of unit 2#; 202, reactor of denitration system B of unit 2#; 21, bypass high-temperature flue gas system of unit 2#; 211, bypass high-temperature flue duct A of unit 2#; 212, bypass high-temperature flue duct B of unit 2#; 213, bypass high-temperature mother pipe flue duct of unit 2#; 214, bypass high-temperature mother pipe flue duct of unit 2# 2# unit high temperature flue gas A damper door; 215, 2# unit high temperature flue gas B damper door; 22, 2# unit bypass low temperature flue gas system; 221, 2# unit bypass low temperature A flue duct; 222, 2# unit bypass low temperature B flue duct; 223, 2# unit bypass low temperature mother pipe flue duct; 224, 2# unit low temperature flue gas A damper door; 225, 2# unit low temperature flue gas B damper door; 23, 2# unit air preheater; 231, 2# unit A air preheater; 232, 2# unit B air preheater; 24, 2# unit A dust collector; 241, 2# unit A dust collector; 242, 2# unit B dust collector; 25, 2# unit induced draft fan; 251, 2# unit A induced draft fan; 252, 2# unit B induced draft fan; 3. High-temperature flue gas three-way valve assembly; 31. High-temperature flue gas main duct; 32. High-temperature flue gas isolation door of unit 1#; 33. High-temperature flue gas branch duct of unit 1#; 34. High-temperature flue gas branch duct of unit 2#; 35. High-temperature flue gas isolation door of unit 2#; 36. High-temperature flue gas three-way valve guide plate; 37. High-temperature flue gas feeding plate; 4. Drying tower; 41. Drying tower regulating door; 5. Low-temperature flue gas three-way valve assembly; 51. Low-temperature flue gas main duct, 52. Low-temperature flue gas isolation door of unit 1#; 53. Low-temperature flue gas branch duct of unit 1#; 54. Low-temperature flue gas branch duct of unit 2#; 55. Low-temperature flue gas isolation door of unit 2#; 56. Low-temperature flue gas three-way valve guide plate; 57. Low-temperature flue gas feeding plate. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings and embodiments.

[0019] like Figure 1 As shown, a bypass flue gas evaporation system for zero discharge of desulfurized wastewater includes a denitration system 10 of unit 1, a denitration system 20 of unit 2, a bypass high-temperature flue gas system 11 of unit 1, a bypass high-temperature flue gas system 21 of unit 2, a high-temperature flue gas three-way valve assembly device 3, a drying tower 4, a low-temperature flue gas three-way valve assembly device 5, a bypass low-temperature flue gas system 12 of unit 1, a bypass low-temperature flue gas system 22 of unit 2, an air preheater 13 of unit 1, an air preheater 23 of unit 2, a dust collector 14 of unit 1, a dust collector 24 of unit 2, an induced draft fan 15 of unit 1 and an induced draft fan 25 of unit 2. The denitration system 10 of unit 1 includes a 1# denitration system A reactor 101 and 1# denitration system B reactor 102, 1# unit bypass high temperature flue gas system 11 includes 1# unit bypass high temperature A flue 111, 1# unit bypass high temperature B flue 112 and 1# unit bypass high temperature mother pipe flue 113, 1# unit bypass low temperature flue gas system 12 includes 1# unit bypass low temperature A flue 121, 1# unit bypass low temperature B flue 122 and 1# unit bypass low temperature mother pipe flue 123, 1# unit air preheater 13 includes 1# unit A air preheater 131 and 1# unit B air preheater 132, 1# unit dust collector 14 includes 1# unit A dust collector 141 and 1# unit B dust collector 142; 1# unit induced draft fan 15 includes 1# unit A induced draft fan 151 and 1# unit B induced draft fan 152; the outlet flues of 1# denitration system A reactor 101 and 1# denitration system B reactor 102 are respectively connected to 1# unit bypass high temperature A flue 111 and 1# unit bypass high temperature B flue 112, and 1# unit high temperature flue gas A damper door 114 is set between 1# denitration system A reactor 101 and 1# unit bypass high temperature A flue 111, and 1# unit high temperature flue gas B damper door 115 is set between 1# denitration system B reactor 102 and 1# unit bypass high temperature B flue 112, and high temperature flue gas The three-way valve assembly device 3 includes a high-temperature flue gas main pipeline 31, and the low-temperature flue gas three-way valve assembly device 5 includes a low-temperature flue gas main pipeline 51. The high-temperature main pipe flue 113 of the bypass of the 1# unit is connected to the high-temperature flue gas branch pipeline 33 of the high-temperature flue gas three-way valve assembly device 3, and the high-temperature flue gas isolation door 32 of the 1# unit is connected in between. The high-temperature flue gas main pipeline 31 of the high-temperature flue gas three-way valve assembly device 3 is connected to the high-temperature flue gas inlet at the top of the drying tower 4, and the drying tower regulating door 41 is connected between the high-temperature flue gas main pipeline 31 and the high-temperature flue gas inlet; the high-temperature flue gas isolation door of the 1# unit is used to prevent the high-temperature flue gas of the 1# unit and the high-temperature flue gas of the 2# unit from mutual leakage, which affects the stable operation of the main unit.

[0020] The low-temperature flue gas outlet at the bottom of the drying tower 4 is connected to the low-temperature flue gas main pipeline 51 of the low-temperature flue gas three-way valve assembly device 5, the low-temperature flue gas branch pipeline 53 of the low-temperature flue gas three-way valve assembly device 5 of the 1# unit is connected to the 1# unit bypass low-temperature mother pipe flue 123 of the 1# unit bypass low-temperature flue gas system 12, and a 1# unit low-temperature flue gas isolation door 52 is arranged between the 1# unit low-temperature flue gas branch pipeline 53 and the 1# unit bypass low-temperature mother pipe flue 123, the outlet flue of the 1# denitration system A reactor 101 is connected to the 1# unit A air preheater 131, the outlet flue of the 1# unit A air preheater 131 is connected to the 1# unit A dust collector 141, the outlet flue of the 1# denitration system B reactor 102 is connected to the 1# unit B air preheater 132, the outlet flue of the 1# unit B air preheater 132 is connected to the 1# unit B dust collector 142, the 1# unit bypass low-temperature flue gas The bypass low-temperature flue 121 of the 1# unit of the system 12 is connected to the outlet flue of the 1# unit A air preheater 131. A low-temperature flue gas A damper door 124 of the 1# unit is provided between the bypass low-temperature flue 121 of the 1# unit and the outlet flue of the 1# unit A air preheater 131. The bypass low-temperature flue 122 of the 1# unit of the system 12 is connected to the outlet flue of the 1# unit B air preheater 132. A 1# unit low-temperature flue gas B damper door 125 is provided between the unit bypass low-temperature B flue 122 and the outlet flue of the 1# unit B air preheater 132. The 1# unit A dust collector 141 is connected to the 1# unit A induced draft fan 151, and the 1# unit B dust collector is connected to the 1# unit B induced draft fan 152. The 1# unit low-temperature flue gas isolation door is used to prevent the low-temperature flue gas of the 1# unit and the low-temperature flue gas of the 2# unit from mutual leakage, which would affect the stable operation of the main unit.

[0021] The 2# unit denitration system 20 includes a 2# denitration system A reactor 201 and a 2# denitration system B reactor 202, the 2# unit bypass high-temperature flue gas system 21 includes a 2# unit bypass high-temperature A flue 211, a 2# unit bypass high-temperature B flue 212 and a 2# unit bypass high-temperature mother pipe flue 213, and the 2# unit bypass low-temperature flue gas system 22 includes a 2# unit bypass low-temperature A flue 221, a 2# unit bypass low-temperature B flue 222 and a 2# unit bypass low-temperature flue 223. Bypass low temperature main pipe flue 223, 2# unit air preheater 23 includes 2# unit A air preheater 231 and 2# unit B air preheater 232, 2# unit dust collector 24 includes 2# unit A dust collector 241 and 2# unit B dust collector 242; 2# unit induced draft fan 25 includes 2# unit A induced draft fan 251 and 2# unit B induced draft fan 252; 2# denitration system A reactor 201 and 2# denitration system B reactor 202 outlet The flue ducts are connected to the bypass high-temperature flue duct A 211 and the bypass high-temperature flue duct B 212 of the 2# unit, respectively. A damper door 214 of the high-temperature flue gas A of the 2# unit is provided between the A reactor 201 of the 2# denitration system and the bypass high-temperature flue duct A 211 of the 2# unit. A damper door 215 of the high-temperature flue gas B of the 2# unit is provided between the B reactor 202 of the 2# denitration system and the bypass high-temperature flue duct B 212 of the 2# unit. The bypass high-temperature mother pipe flue duct 213 of the 2# unit is connected to the high-temperature flue duct A of the 2# unit. The high-temperature flue gas branch pipe 34 of the flue gas three-way valve group device 3 is connected to the high-temperature flue gas isolation door 35 of the 2# unit. The high-temperature flue gas main pipe 31 of the high-temperature flue gas three-way valve group device 3 is connected to the high-temperature flue gas inlet at the top of the drying tower 4, and the drying tower regulating door 41 is connected between the high-temperature flue gas main pipe 31 and the high-temperature flue gas inlet; the high-temperature flue gas isolation door of the 2# unit is used to prevent the high-temperature flue gas of the 2# unit and the high-temperature flue gas of the 1# unit from mutual leakage, which affects the stable operation of the main unit.

[0022] The low-temperature flue gas outlet at the bottom of the drying tower 4 is connected to the low-temperature flue gas main pipeline 51 of the low-temperature flue gas three-way valve assembly device 5, the low-temperature flue gas branch pipeline 54 of the low-temperature flue gas three-way valve assembly device 5 of the 2# unit is connected to the 2# unit bypass low-temperature mother pipe flue 223 of the 2# unit bypass low-temperature flue gas system 22, and a 2# unit low-temperature flue gas isolation door 55 is arranged between the 2# unit low-temperature flue gas branch pipeline 54 and the 2# unit bypass low-temperature mother pipe flue 223, the outlet flue of the 2# unit denitration system A reactor 201 is connected to the 2# unit A air preheater 231, the outlet flue of the 2# unit A air preheater 231 is connected to the 2# unit A dust collector 241, the outlet flue of the 2# denitration system B reactor 202 is connected to the 2# unit B air preheater 232, the outlet flue of the 2# unit B air preheater 232 is connected to the 2# unit B dust collector 242, the 2# unit bypass low-temperature flue gas system The 2# unit bypass low-temperature A flue 221 of the system 22 is connected to the outlet flue of the 2# unit A air preheater 231. A 2# unit low-temperature flue gas A damper door 224 is provided between the 2# unit bypass low-temperature A flue 221 and the 2# unit A air preheater 231 outlet flue. The 2# unit bypass low-temperature B flue 222 of the 2# unit bypass low-temperature flue gas system 22 is connected to the outlet flue of the 2# unit B air preheater 232. A 2# unit low-temperature flue gas B damper door 225 is provided between the bypass low-temperature B flue 222 and the outlet flue of the 2# unit B air preheater 232, the 2# unit A dust collector 241 is connected to the 2# unit A induced draft fan 251, and the 2# unit B dust collector 242 is connected to the 2# unit B induced draft fan 252; the 2# unit low-temperature flue gas isolation door is used to prevent the 2# unit low-temperature flue gas and the 1# unit low-temperature flue gas from mutual leakage, which would affect the stable operation of the main unit.

[0023] like Figure 2-3As shown, the high-temperature flue gas three-way valve assembly device 3 and the low-temperature flue gas three-way valve assembly device 5 have the same structure. The high-temperature flue gas three-way valve assembly device 3 also includes a high-temperature flue gas three-way valve guide plate 36. Two arc-shaped high-temperature flue gas three-way valve guide plates 36 are arranged at the junction of the high-temperature flue gas branch pipe 33 of the 1# unit and the high-temperature flue gas branch pipe 34 of the 2# unit in the high-temperature flue gas three-way valve assembly device 3. The material is the same as the flue material, the arc diameter is the radius of the high-temperature flue gas branch pipe, the height is the diameter of the high-temperature flue gas branch pipe, and the arc length is 1 / 4 of the cross-sectional area of ​​the high-temperature flue gas branch pipe. The two guide plates and the high-temperature flue gas branch pipe 33 of the 1# unit and the high-temperature flue gas branch pipe 34 of the 2# unit are fully welded; the low-temperature flue gas three-way valve assembly device 5 also includes a low-temperature flue gas three-way valve guide plate 56. Two arc-shaped low-temperature flue gas three-way valve guide plates 56 are arranged at the junction of the high-temperature flue gas branch pipe 53 of unit 1 and the high-temperature flue gas branch pipe 54 of unit 2 in the low-temperature flue gas three-way valve group device 5. The material is the same as the flue material, the arc diameter is the radius of the low-temperature flue gas branch pipe, the height is the diameter of the low-temperature flue gas branch pipe, and the arc length is 1 / 4 of the cross-sectional area of ​​the low-temperature flue gas branch pipe. The two guide plates and the low-temperature flue gas branch pipe 53 of unit 1 and the low-temperature flue gas branch pipe 54 of unit 2 are fully welded; the flue gas flow field is stabilized by the arc-shaped high-temperature flue gas three-way valve guide plate 36 and the low-temperature flue gas three-way valve guide plate 56, the flue gas flow velocity is accelerated, the flue gas wear and ash accumulation probability at the three-way junction of the flue gases of the two units are greatly reduced, and the stability of the flue gas flow is enhanced.

[0024] The high-temperature flue gas main duct 31 and the high-temperature flue gas branch duct 33 of unit 1 and the high-temperature flue gas branch duct 34 of unit 2 are all welded with the high-temperature flue gas feeding plate 37, and the low-temperature flue gas main duct 51 and the low-temperature flue gas branch duct 53 of unit 1 and the low-temperature flue gas branch duct 54 of unit 2 are all welded with the low-temperature flue gas feeding plate 57. The top of the feeding plate is 200mm away from the high-temperature flue gas branch duct, and the bottom of the feeding plate is 200mm away from the high-temperature flue gas main duct 31. The material is the same as that of the flue, and the feeding plate and the high-temperature flue gas branch duct are fully welded; the main duct and the branch duct are welded by the high-temperature flue gas feeding plate and the low-temperature flue gas feeding plate, and the high-temperature flue gas three-way valve group device and the low-temperature flue gas three-way valve group device are reinforced, so that the flue gas flows stably and the system stability is enhanced.

[0025] The operation switching steps of the evaporation system are as follows: Commissioning the flue gas evaporation system of Unit 1#: open Unit 1# high-temperature flue gas A damper door 114, Unit 1# high-temperature flue gas B damper door 115, Unit 1# high-temperature flue gas isolation door 32, drying tower adjustment door 41, Unit 1# low-temperature flue gas isolation door 52, Unit 1# low-temperature flue gas A damper door 124 and Unit 1# low-temperature flue gas B damper door 125; close Unit 2# high-temperature flue gas A damper door 214, Unit 2# high-temperature flue gas B damper door 215, Unit 2# high-temperature flue gas isolation door 35, Unit 2# low-temperature flue gas isolation door 55, Unit 2# low-temperature flue gas A damper door 224 and Unit 2# low-temperature flue gas B damper door 225.

[0026] Put the flue gas evaporation system of unit 2 into operation: open high-temperature flue gas A damper door 214 of unit 2, high-temperature flue gas B damper door 215 of unit 2, high-temperature flue gas isolation door 35 of unit 2, drying tower regulating door 41, low-temperature flue gas isolation door 55 of unit 2, low-temperature flue gas A damper door 224 of unit 2 and low-temperature flue gas B damper door 225 of unit 2, and close high-temperature flue gas A damper door 114 of unit 1, high-temperature flue gas B damper door 115 of unit 1, high-temperature flue gas isolation door 32 of unit 1, low-temperature flue gas isolation door 52 of unit 1, low-temperature flue gas A damper door 124 of unit 1 and low-temperature flue gas B damper door 125 of unit 1.

Claims

1. A bypass flue gas evaporation system for zero discharge of desulfurization wastewater, characterized in that: It includes two units, and each unit includes a denitration system, a bypass high-temperature flue gas system, a high-temperature flue gas three-way valve group device, a drying tower, a low-temperature flue gas three-way valve group device, a bypass low-temperature flue gas system and an air preheater. The denitration system includes a denitration system A reactor and a denitration system B reactor. The air preheater includes an A air preheater and a B air preheater. The outlet flues of the denitration system A reactor and the denitration system B reactor are both connected to the bypass high-temperature flue gas system. The bypass high-temperature flue gas system is connected to a branch pipeline of the high-temperature flue gas three-way valve group device. The main pipeline of the high-temperature flue gas three-way valve group device is connected to the top of the drying tower, and the bottom of the drying tower is connected to the main pipeline of the low-temperature flue gas three-way valve group device. The low-temperature flue gas three-way valve A branch pipe of the group device is connected to the bypass low-temperature flue gas system, the outlet flue of the A reactor of the denitrification system is connected to the A air preheater, the outlet flue of the A air preheater is connected to the A dust collector, the outlet flue of the B reactor of the denitrification system is connected to the B air preheater, the outlet flue of the B air preheater is connected to the B dust collector, a branch pipe of the bypass low-temperature flue gas system is connected to the outlet flue of the A air preheater, another branch pipe of the bypass low-temperature flue gas system is connected to the outlet flue of the B air preheater, the A dust collector is connected to the A induced draft fan, the B dust collector is connected to the B induced draft fan, the structure of the other unit is the same as the connection relationship of the unit, and the two units share the high-temperature flue gas three-way valve group device, the drying tower and the low-temperature flue gas three-way valve group device.

2. A bypass flue gas evaporation system for zero discharge of desulfurization wastewater according to claim 1, characterized in that: The high-temperature flue gas three-way valve group device and the low-temperature flue gas three-way valve group device have the same structure, both comprising a main pipeline, two branch pipelines and a guide plate, and the branch pipelines are both provided with a smoke isolation door.

3. A bypass flue gas evaporation system for zero discharge of desulfurization wastewater according to claim 2, characterized in that: Guide plates are welded at the smoke confluence points in the branch pipes of the high-temperature flue gas three-way valve group device and the low-temperature flue gas three-way valve group device. The two guide plates are in an arc shape and made of the same material as the flue.

4. A bypass flue gas evaporation system for zero discharge of desulfurization wastewater according to claim 3, characterized in that: The arc diameter of the guide plate is the radius of the branch pipe, the height of the guide plate is the diameter of the branch pipe, the arc length of the guide plate is 1 / 4 of the cross-sectional area of ​​the tee branch pipe, and the welding method of the two guide plates and the branch pipe is full welding.

5. A bypass flue gas evaporation system for zero discharge of desulfurization wastewater according to claim 4, characterized in that: The main pipeline and branch pipeline are connected by a feed plate. The top of the feed plate is 200mm away from the branch pipeline, and the bottom of the feed plate is 200mm away from the main pipeline. The material is the same as that of the flue. The feed plate and the main pipeline are fully welded.

6. A bypass flue gas evaporation system for zero discharge of desulfurization wastewater according to any one of claims 1 or 5, characterized in that: The bypass high-temperature flue gas system includes a bypass high-temperature A flue, a bypass high-temperature B flue and a bypass high-temperature main pipe flue. The bypass high-temperature A flue is connected to the denitrification system A reactor, with a high-temperature flue gas damper door A provided therebetween. The bypass high-temperature B flue is connected to the denitrification system B reactor, with a high-temperature flue gas damper door B provided therebetween. The bypass high-temperature main pipe flue is connected to a branch pipe of a high-temperature flue gas three-way valve group device.

7. A bypass flue gas evaporation system for zero discharge of desulfurization wastewater according to claim 6, characterized in that: The bypass low-temperature flue gas system includes a bypass low-temperature A flue, a bypass low-temperature B flue and a bypass low-temperature main pipe flue. The bypass low-temperature main pipe flue is connected to a branch pipe of a low-temperature flue gas three-way valve group device. The bypass low-temperature A flue is connected to an A dust collector, and a low-temperature flue gas damper door A is provided therebetween. The bypass low-temperature B flue is connected to a B dust collector, and a low-temperature flue gas damper door B is provided therebetween.

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