A flue gas extraction and mixing device and method for wastewater treatment

Abstract

The present invention discloses a flue gas extraction and mixing device and method for wastewater treatment, comprising a first extraction flue gas branch pipe, a first induced draft fan outlet flue, a second extraction flue gas branch pipe, a second induced draft fan outlet flue, a wastewater concentration tower, a wastewater concentration tower outlet flue, a desulfurization tower and a static mixer, wherein the static mixer comprises a mixing branch pipe and a mixing chamber. The device and method can effectively reduce the impact during flue gas mixing and eliminate the hidden danger of dust accumulation at the desulfurization tower inlet.

Description

Technical Field

[0001] The invention relates to a flue gas mixing device and method, and in particular to a flue gas extraction and mixing device and method for wastewater treatment. Background Art

[0002] Coal-fired power plants are large users of water and have great potential for water conservation in the face of increasingly tight water resources. In order to reduce water consumption indicators, power plants generally use water in a stepped manner to increase water recycling and reduce wastewater discharge. High-quality water is used for chemical water production. Chemical water production produces high-salt water, circulating sewage and other types of boiler wastewater as process water for wet flue gas desulfurization systems. The desulfurization system wastewater is centrifuged in a cyclone to produce desulfurization wastewater.

[0003] In order to achieve zero discharge of desulfurized wastewater, the overall technical idea for achieving zero discharge of desulfurized wastewater at this stage is: desulfurized wastewater → pretreatment → concentration and reduction → evaporation and crystallization. In the concentration and reduction stage, the low-temperature flue gas evaporation process is widely used, that is, the low-temperature flue gas between the outlet of the induced draft fan and the inlet of the desulfurization tower 16 is used as a heat source to enter the wastewater concentration tower 8, and the high-salt desulfurized wastewater is introduced into the wastewater concentration tower for atomization. The atomized wastewater is mixed with the low-temperature flue gas and evaporated, thereby achieving the purpose of wastewater concentration and reduction. After evaporation and cooling in the wastewater concentration tower, the low-temperature flue gas returns to the inlet flue 11 of the desulfurization tower 16.

[0004] Improper selection of the location for flue gas extraction and mixing after the wastewater concentration tower or improper connection of the extraction and mixing sections not only affects the power consumption of the booster fan of the wastewater concentration tower, but also has the risk of affecting the desulfurization system. The existing wastewater treatment flue gas extraction and mixing are generally selected in the straight section of the flue after the induced draft fan and before the desulfurization tower entrance. Since the space between the induced draft fan outlet and the desulfurization tower of the existing and newly built power plants is generally tight, the flue between the induced draft fan outlet and the desulfurization tower is short, resulting in the extraction point and the mixing point being too close, affecting the normal extraction quality of the flue gas of the wastewater concentration tower. The improper design of the mixing section of the flue gas at the outlet of the wastewater concentration tower and the inlet of the desulfurization tower is easy to form vortices. On the one hand, the flue gas counteraction increases the system resistance and increases the energy consumption of the system fan. On the other hand, the slurry in the desulfurization tower is brought into the flue gas inlet, which has the hidden danger of causing dust accumulation at the inlet of the desulfurization tower. In addition, the automatic control level of the existing wastewater flue gas extraction and mixing device is not high, and the operating energy consumption is high. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide a flue gas extraction and mixing device and method for wastewater treatment, which can effectively reduce the impact during flue gas mixing and eliminate the hidden danger of ash accumulation at the inlet of the desulfurization tower.

[0006] To achieve the above-mentioned object, the flue gas extraction and mixing device for wastewater treatment of the present invention comprises a first extraction flue gas branch pipe, a first induced draft fan outlet flue, a second extraction flue gas branch pipe, a second induced draft fan outlet flue, a wastewater concentration tower, a wastewater concentration tower outlet flue, a desulfurization tower and a static mixer, wherein the static mixer comprises a mixing branch pipe and a mixing chamber;

[0007] One end of the first extraction flue gas branch pipe is connected with the smoke inlet of the first induced draft fan outlet flue, one end of the second extraction flue gas branch pipe is connected with the smoke inlet of the second induced draft fan outlet flue, the other end of the first extraction flue gas branch pipe and the other end of the second extraction flue gas branch pipe are connected with the flue gas inlet of the wastewater concentration tower through a pipeline, the flue gas outlet of the wastewater concentration tower is connected with the inlet of the mixing branch pipe through the wastewater concentration tower outlet flue, the outlet of the mixing branch pipe is connected with the first inlet of the mixing chamber, the mixing branch pipe is inclinedly distributed, the outlet of the mixing chamber is connected with the inlet of the desulfurization tower, the other end of the first extraction flue gas branch pipe and the other end of the second extraction flue gas branch pipe are connected with the second inlet of the mixing chamber through a pipeline, a flue gas baffle is provided at the first inlet of the mixing chamber, and a guide plate for guiding the flue gas output from the mixing branch pipe is provided in the mixing chamber.

[0008] The first smoke extraction branch pipe and the second smoke extraction branch pipe are both provided with a first electric air damper.

[0009] The first extracted flue gas branch pipe and the second extracted flue gas branch pipe are connected through the pipeline and then communicated with the flue gas inlet of the wastewater concentration tower via the extracted flue gas merging pipe, the variable frequency booster fan and the inlet flue of the wastewater concentration tower.

[0010] A second electric air valve is provided on the flue at the outlet of the wastewater concentration tower.

[0011] The angle between the axis of the mixing branch pipe and the axis of the induced draft fan outlet merging flue is 45°-50°.

[0012] It also includes a controller, and detectors for detecting flue gas temperature, pressure and flow are arranged on the flue gas extraction junction pipe, the wastewater concentration tower, the wastewater concentration tower outlet flue and the desulfurization tower inlet flue, wherein the output end of the detector is connected to the input end of the controller, and the output end of the controller is connected to the control end of the variable frequency booster fan, the control end of the first electric air valve and the control end of the second electric air valve.

[0013] A flue gas extraction and mixing method for wastewater treatment comprises the following steps:

[0014] The flue gases extracted from the first extraction flue gas branch pipe and the second extraction flue gas branch pipe converge and enter the wastewater concentration tower to release heat. The flue gas output from the wastewater concentration tower enters the mixing branch pipe through the wastewater concentration tower outlet flue, and then enters the mixing chamber through the mixing branch pipe. At the same time, the flue gases output from the first induced draft fan outlet flue and the second induced draft fan outlet flue converge and enter the mixing chamber through the induced draft fan outlet converging flue, wherein a flue gas baffle is provided at the first inlet of the mixing chamber, and the flue gas output from the induced draft fan outlet converging flue close to the first inlet is diverted and displaced by the flue gas baffle to avoid the impact of this part of the flue gas on the flue gas output from the mixing branch pipe, and the flue gas output from the mixing chamber enters the desulfurization tower.

[0015] The present invention has the following beneficial effects:

[0016] During specific operation, the flue gas extraction and mixing device and method for wastewater treatment described in the present invention adopts a two-point flue gas extraction method through the first flue gas extraction branch pipe and the second flue gas extraction branch pipe, which has good adaptability under different on-site layout conditions, effectively increases the distance between the flue gas extraction and mixing sections, and ensures the quality of flue gas extraction. In addition, the present invention completes the mixing of flue gas through a flue gas static mixer, effectively avoiding the generation of vortexes at the inlet of the desulfurization tower, avoiding the slurry in the desulfurization tower from entering the inlet of the desulfurization tower to generate deposition, and effectively avoiding the hidden danger of ash accumulation. At the same time, after the flue gas is mixed by the static mixer, the energy consumption caused by flue gas counter-flow is avoided, which is beneficial to reducing system resistance and reducing the energy consumption of the induced draft fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a system schematic diagram of the present invention.

[0018] Among them, 1 is the induced draft fan outlet flue, 2 is the induced draft fan outlet junction flue, 3 is the first electric air valve, 4 is the flue gas extraction branch pipe, 5 is the flue gas extraction junction pipe, 6 is the variable frequency booster fan, 7 is the wastewater concentration tower inlet flue, 8 is the wastewater concentration tower, 9 is the wastewater concentration tower outlet flue, 10 is the second electric air valve, 11 is the desulfurization tower inlet flue, 12 is the flue gas static mixer, 13 is the mixing branch pipe, 14 is the flue gas baffle, 15 is the guide plate, 16 is the desulfurization tower, and 17 is the controller. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0020] refer to Figure 1The flue gas extraction and mixing device for wastewater treatment of the present invention comprises a first extraction flue gas branch pipe 4a, a first induced draft fan outlet flue 1a, a second extraction flue gas branch pipe 4b, a second induced draft fan outlet flue 1b, a wastewater concentration tower 8, a wastewater concentration tower outlet flue 9, a desulfurization tower 16 and a static mixer, wherein the static mixer comprises a mixing branch pipe 13 and a mixing chamber; one end of the first extraction flue gas branch pipe 4a is connected to the smoke inlet of the first induced draft fan outlet flue 1a, one end of the second extraction flue gas branch pipe 4b is connected to the smoke inlet of the second induced draft fan outlet flue 1b, and the other end of the first extraction flue gas branch pipe 4a and the other end of the second extraction flue gas branch pipe 4b are connected to the second induced draft fan outlet flue 1b. After being connected through pipes, it is connected with the flue gas inlet of the wastewater concentration tower 8. The flue gas outlet of the wastewater concentration tower 8 is connected with the inlet of the mixing branch pipe 13 through the wastewater concentration tower outlet flue 9. The outlet of the mixing branch pipe 13 is connected with the first inlet of the mixing chamber. The mixing branch pipe 13 is inclinedly distributed. The outlet of the mixing chamber is connected with the inlet of the desulfurization tower 16. The other end of the first extraction flue gas branch pipe 4a and the other end of the second extraction flue gas branch pipe 4b are connected with the second inlet of the mixing chamber after being connected through pipes. A flue gas baffle 14 is provided at the first inlet of the mixing chamber, and a guide plate 15 is provided in the mixing chamber for guiding the flue gas output from the mixing branch pipe 13.

[0021] The first smoke extraction branch pipe 4a and the second smoke extraction branch pipe 4b are both provided with a first electric damper 3 .

[0022] The first extracted flue gas branch pipe 4a and the second extracted flue gas branch pipe 4b are connected through the pipeline and then communicated with the flue gas inlet of the wastewater concentration tower 8 via the extracted flue gas merging pipe 5, the variable frequency booster fan 6 and the wastewater concentration tower inlet flue 7; a second electric air valve 10 is provided on the wastewater concentration tower outlet flue 9, and the angle between the axis of the mixing branch pipe 13 and the axis of the induced draft fan outlet merging flue 2 is 45°-50°.

[0023] The flue gas extraction and mixing method for wastewater treatment of the present invention comprises the following steps:

[0024] The flue gases extracted from the first extraction flue gas branch 4a and the second extraction flue gas branch 4b converge and enter the wastewater concentration tower 8 to release heat. The flue gas output from the wastewater concentration tower 8 enters the mixing branch 13 through the wastewater concentration tower outlet flue 9, and then enters the mixing chamber through the mixing branch 13. At the same time, the flue gases output from the first induced draft fan outlet flue 1a and the second induced draft fan outlet flue 1b converge and enter the mixing chamber through the induced draft fan outlet merging flue 2, wherein a flue gas baffle 14 is provided at the first inlet of the mixing chamber, and the flue gas output from the induced draft fan outlet merging flue 2 close to the first inlet is diverted and displaced by the flue gas baffle 14 to avoid the impact of this part of the flue gas on the flue gas output from the mixing branch 13, and the flue gas output from the mixing chamber enters the desulfurization tower 16.

[0025] Detectors for detecting flue gas temperature, pressure and flow are arranged on the flue gas extraction junction pipe 5, the wastewater concentration tower 8, the wastewater concentration tower outlet flue 9 and the desulfurization tower inlet flue 11, wherein the output end of the detector is connected to the input end of the controller 17, and the output end of the controller 17 is connected to the control end of the variable frequency boost fan 6, the control end of the first electric air valve 3 and the control end of the second electric air valve 10. The controller 17 feeds back the data detected by the detector to the variable frequency boost fan 6 to complete the fan variable frequency operation action, increase or decrease the amount of extracted flue gas, so as to meet the flue gas required by the wastewater concentration tower 8 in real time, ensure that the flue gas parameters entering the flue gas static mixer 12 from the wastewater concentration tower outlet flue 9 meet the requirements, and also can control the first electric air valve 3 and the second electric air valve 10 to close when the device fails or the device stops running for maintenance.

Claims

1. A flue gas extraction and mixing device for wastewater treatment, characterized in that: It comprises a first flue gas extraction branch pipe (4a), a first induced draft fan outlet flue (1a), a second flue gas extraction branch pipe (4b), a second induced draft fan outlet flue (1b), a wastewater concentration tower (8), a wastewater concentration tower outlet flue (9), a desulfurization tower (16) and a static mixer, wherein the static mixer comprises a mixing branch pipe (13) and a mixing chamber; One end of the first smoke extraction branch pipe (4a) is connected to the smoke inlet of the first induced draft fan outlet flue (1a), one end of the second smoke extraction branch pipe (4b) is connected to the smoke inlet of the second induced draft fan outlet flue (1b), the other end of the first smoke extraction branch pipe (4a) and the other end of the second smoke extraction branch pipe (4b) are connected to the smoke inlet of the wastewater concentration tower (8) through a pipeline, and the smoke outlet of the wastewater concentration tower (8) is connected to the inlet of the mixing branch pipe (13) through the wastewater concentration tower outlet flue (9). , the outlet of the mixing branch pipe (13) is connected to the first inlet of the mixing chamber, the mixing branch pipe (13) is inclinedly distributed, the outlet of the mixing chamber is connected to the inlet of the desulfurization tower (16), the other end of the first extraction flue gas branch pipe (4a) and the other end of the second extraction flue gas branch pipe (4b) are connected to the second inlet of the mixing chamber through a pipeline, a flue gas baffle (14) is provided at the first inlet of the mixing chamber, and a guide plate (15) for guiding the flue gas output from the mixing branch pipe (13) is provided in the mixing chamber; The first smoke extraction branch pipe (4a) and the second smoke extraction branch pipe (4b) are both provided with a first electric damper (3); The angle between the axis of the mixing branch pipe (13) and the axis of the exhaust fan outlet merging flue (2) is 45°-50°.

2. The flue gas extraction and mixing device for wastewater treatment according to claim 1, characterized in that: The first extracted smoke branch pipe (4a) and the second extracted smoke branch pipe (4b) are connected through a pipeline and then communicated with the smoke inlet of the wastewater concentration tower (8) via the extracted smoke merging pipe (5), the variable frequency booster fan (6) and the wastewater concentration tower inlet flue (7).

3. The flue gas extraction and mixing device for wastewater treatment according to claim 2, characterized in that: A second electric air damper (10) is provided on the flue (9) at the outlet of the wastewater concentration tower.

4. The flue gas extraction and mixing device for wastewater treatment according to claim 3, characterized in that: The invention also includes a controller (17), and detectors for detecting the temperature, pressure and flow of flue gas are arranged on the flue gas extraction confluence pipe (5), the wastewater concentration tower (8), the wastewater concentration tower outlet flue (9) and the desulfurization tower inlet flue (11), wherein the output end of the detector is connected to the input end of the controller (17), and the output end of the controller (17) is connected to the control end of the variable frequency booster fan (6), the control end of the first electric air valve (3) and the control end of the second electric air valve (10).

5. A flue gas extraction and mixing method for wastewater treatment, characterized in that: The flue gas extraction and mixing device for wastewater treatment according to any one of claims 1 to 4 comprises the following steps: The flue gases extracted from the first flue gas extraction branch pipe (4a) and the second flue gas extraction branch pipe (4b) are merged and enter the wastewater concentration tower (8) to release heat. The flue gas output from the wastewater concentration tower (8) enters the mixing branch pipe (13) through the wastewater concentration tower outlet flue (9), and then enters the mixing chamber through the mixing branch pipe (13). At the same time, the flue gases output from the first induced draft fan outlet flue (1a) and the second induced draft fan outlet flue (1b) are merged and enter the mixing chamber through the induced draft fan outlet merging flue (2). A flue gas baffle (14) is provided at the first inlet of the mixing chamber. The flue gas output from the induced draft fan outlet merging flue (2) near the first inlet is diverted and displaced by the flue gas baffle (14) to avoid the impact of this part of the flue gas on the flue gas output from the mixing branch pipe (13). The flue gas output from the mixing chamber enters the desulfurization tower (16).

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