A system and method for controlling liquid level of absorption tower

Abstract

The present invention relates to the field of environmental protection equipment related to a wet flue gas desulfurization absorption tower, and specifically to a system and method for controlling the liquid level of an absorption tower. The system of the present invention comprises an isolation settling pipe group installed in the absorption tower slurry pool and an external tower collecting pipe arranged outside the absorption tower; the isolation settling pipe group comprises a plurality of isolation settling pipes; the isolation settling pipes are evenly arranged along the circumference of the absorption tower slurry pool, and each isolation settling pipe is obliquely inserted into the absorption tower slurry pool, and after being inserted into the absorption tower, it is vertically bent to the bottom of the absorption tower, and the top extending out of the absorption tower is connected to the external tower collecting pipe. The present invention arranges an isolation settling pipe group in the absorption tower slurry pool area, utilizes the isolation effect of each isolation settling pipe itself, and realizes the solid-liquid separation of part of the absorption tower slurry through the natural sedimentation effect of the slurry inside the isolation settling pipe. The separated supernatant is automatically discharged from the absorption tower, which can effectively control the liquid level and water balance of the absorption tower, and avoids the increase in operating costs caused by increasing the discharge of desulfurization wastewater to control the liquid level of the absorption tower.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection equipment related to a wet desulfurization absorption tower, and in particular to a system and method for controlling the liquid level of an absorption tower. Background Art

[0002] In recent years, as environmental protection policies in various regions have become increasingly stringent, all coal-fired boilers that are eligible for transformation are required to strive to achieve ultra-low emissions. For example, the thermal power industry requires that under the condition of a baseline oxygen content of 6%, the emission concentrations of smoke, sulfur dioxide, and nitrogen oxides are not higher than 10, 35, and 50 mg / m3, respectively. For dust control, some coal-fired power plants use low-temperature electrostatic precipitators and absorption towers to achieve ultra-low dust emissions. This technology requires the addition of a low-temperature economizer in front of the electrostatic precipitator to reduce the flue gas temperature in front of the electrostatic precipitator and improve the operation effect of the electrostatic precipitator, and the installation of a multi-stage demisting and dust removal device in the absorption tower to reduce the carryover of flue gas droplets and dust in the tower.

[0003] In the above process, there are two problems: on the one hand, the use of low-temperature economizers causes the temperature of flue gas at the inlet of the absorption tower to decrease, resulting in a decrease in the evaporation volume in the absorption tower, and the liquid level and water balance of the absorption tower are difficult to control; on the other hand, in order to ensure the operation effect of the multi-stage high-efficiency coordinated demisting and dust removal device in the absorption tower, a large amount of process water is inevitably used for flushing. A large amount of flushing process water eventually enters the absorption tower slurry pool, which will further aggravate the uncontrollable liquid level and water balance of the absorption tower. At present, in order to ensure that the liquid level and water balance of the absorption tower can be controlled during the operation of the desulfurization system, the method of blindly reducing the flushing frequency of the high-efficiency demisting and dust removal device and increasing the discharge of desulfurization wastewater is often adopted. However, reducing flushing will bring safety hazards to the operation of the high-efficiency coordinated demisting and dust removal device, and increasing the discharge of desulfurization wastewater will cause a significant increase in operating costs. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a system and method for controlling the liquid level of an absorption tower, which can effectively separate the solid-liquid of part of the slurry in the slurry pool of the absorption tower, thereby effectively controlling the liquid level and water balance of the absorption tower, effectively saving water, low cost, and being safe and reliable.

[0005] The present invention is achieved through the following technical solutions:

[0006] A system for controlling the liquid level of an absorption tower, comprising an isolation settling pipe group installed in a slurry pool of the absorption tower and an external collecting pipe arranged outside the absorption tower;

[0007] The isolation sedimentation pipe group includes a plurality of isolation sedimentation pipes; the isolation sedimentation pipes are evenly arranged along the circumference of the absorption tower slurry pool, each isolation sedimentation pipe is obliquely inserted into the absorption tower slurry pool, and after being inserted into the absorption tower, it is vertically bent to the bottom of the absorption tower, and the top end extending outside the absorption tower is connected with the collection pipe outside the tower.

[0008] Furthermore, the top of the isolation settling pipe and the height of the external collecting pipe are both lower than the designed liquid level of the absorption tower.

[0009] Furthermore, the insertion point of each isolation settling pipe into the absorber slurry pool is 1.5m-2.0m away from the designed liquid level of the absorber, and the bottom end of each isolation settling pipe is 1.0m-2.0m away from the bottom of the absorber.

[0010] Furthermore, the isolation sedimentation tube group includes 8-16 isolation sedimentation tubes.

[0011] Furthermore, the nominal diameter of a single pipe of the isolation sedimentation pipe ranges from 0.15m to 0.5m.

[0012] Furthermore, it also includes a collection pit arranged outside the absorption tower; the input end of the collection pit is connected to the collection pipe outside the tower.

[0013] Furthermore, the output end of the collection pit is connected to the input end of the flushing water system of the demisting and dust removal device through a pump group.

[0014] A method for controlling the liquid level of an absorption tower, comprising:

[0015] When the isolation settling tube group is inserted into the absorption tower, the slurry inside the isolation settling tube group will be isolated by the isolation settling tube group itself and cannot flow;

[0016] The slurry with a high solid content naturally settles in the isolation settling pipe group and sinks to the bottom of the isolation settling pipe group until it flows out of the isolation settling pipe group;

[0017] The supernatant will remain on the upper part of the isolation sedimentation tube group and utilize the height difference between the absorption tower liquid level and the isolation sedimentation tube group to automatically discharge the supernatant out of the absorption tower; the absorption tower liquid level and water balance are controlled by controlling the supernatant discharge amount.

[0018] Furthermore, the supernatant discharged from the absorption tower is led out through the collection pipe outside the tower and flows into the collection pit, and the supernatant is pumped into the flushing water system of the demisting and dust removal device through the pump group for flushing the demisting and dust removal device.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The present invention arranges an isolation settling pipe group in the slurry pool area of ​​the absorption tower, utilizes the isolation effect of each isolation settling pipe itself, and realizes the solid-liquid separation of part of the absorption tower slurry through the natural sedimentation effect of the slurry inside the isolation settling pipe. The separated supernatant is automatically discharged from the absorption tower, which can effectively control the liquid level and water balance of the absorption tower, thereby avoiding the increase in operating costs caused by increasing the discharge of desulfurization wastewater in order to control the liquid level of the absorption tower. At the same time, the discharged supernatant is collected and reused. Considering that the solid content of the supernatant is low and meets the requirement of flushing water for the demisting and dust removal device, it is used to replace process water, thereby avoiding the consumption of this part of water and having a certain water-saving effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structural installation in an embodiment of the present invention.

[0022] In the figure: 1 is the absorption tower slurry pool, 2 is the side-entry agitator, 3 is the demisting and dust removal device, 4 is the isolation sedimentation pipe group, 5 is the external collecting pipe of the tower, 6 is the collecting pit, 7 is the pump group, and 8 is the demisting and dust removal device flushing water system. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0024] The present invention provides a system for controlling the liquid level of an absorption tower, such as Figure 1 As shown, it includes an isolation sedimentation pipe group 4, an external collection pipe 5, a collection pit 6, a pump group 7 and a demisting and dust removal device flushing water system 8; wherein the isolation sedimentation pipe group 4 includes 8-16 isolation sedimentation pipes, and the nominal diameter of a single isolation sedimentation pipe is 0.15m-0.5m, preferably 0.2m-0.4m; the isolation sedimentation pipe group 4 is obliquely inserted into the absorption tower slurry pool 1; the external collection pipe 5 is connected to the external part of the isolation sedimentation pipe group 4 to introduce the collected liquid into the collection pit 6; the pump group 7 pumps the supernatant collected in the collection pit 6 into the demisting and dust removal device flushing water system 8.

[0025] Among them, in this preferred embodiment, the isolation settling pipe group contains 8-16 pipes, and the nominal diameter of a single pipe is 0.15m-0.4m. They are evenly arranged along the circumference of the absorber in the slurry pool 1 area of ​​the absorber. Each isolation settling pipe is obliquely inserted into the slurry pool area 1 of the absorber, and the distance between the insertion point and the design liquid level of the absorber is d1, d1 = 1.5-2.0m. After the isolation settling pipe is inserted into the absorber, it is vertically bent to the bottom of the absorber, and the distance from the bottom of the absorber is d2, d2 = 1.0-2.0m;

[0026] Among them, the solid content of the slurry in the absorption tower slurry pool 1 is generally about 10-25%. Under the action of the absorption tower side-entry agitator 2, all the slurries are in a uniform flow state in the tower, and no natural sedimentation occurs. When multiple isolation sedimentation pipes are inserted into the absorption tower slurry pool, the slurry inside the isolation sedimentation pipe will be isolated by the pipe itself and cannot flow. The slurry with a higher solid content will naturally settle in the isolation sedimentation pipe. The solids in the slurry will sink to the bottom of the isolation sedimentation pipe until it flows out of the isolation sedimentation pipe, and the supernatant will remain in the upper part of the isolation sedimentation pipe; at the same time, due to the height difference between the absorption tower liquid level and the isolation sedimentation pipe, the supernatant can be automatically discharged from the absorption tower, thereby controlling the absorption tower liquid level and water balance by controlling the supernatant discharge amount.

[0027] Among them, the outer collecting pipe 5 for collecting the supernatant outside the absorption tower is reasonably arranged (the installation position is kept below the liquid level of the absorption tower), and the supernatant discharged from the absorption tower can be led out through the outer collecting pipe 5 and then flow into the collection pit 6. Considering that the water quality of this part of the supernatant meets the requirements for the flushing water quality of the demisting and dust removal device 3, a pump group 7 is set to pump it into the demisting and dust removal device flushing water system 8 for flushing the demisting and dust removal device 3.

[0028] The specific working process of the present invention is:

[0029] refer to Figure 1 The lower area of ​​the absorption tower is the absorption tower slurry pool 1, the solid content of the slurry inside it is about 10%-25%, and it is in a uniform flow state under the action of the side-entry agitator 2 and will not undergo natural sedimentation. The isolation sedimentation pipe group 4 composed of 8-16 isolation sedimentation pipes with a nominal diameter of 0.15m-0.4m is evenly arranged circumferentially and obliquely inserted into the absorption tower slurry pool 1. The vertical distance between the insertion point and the design liquid level of the absorption tower is d1 (d1=1.5m-2.0m). After being inserted into the absorption tower, each isolation sedimentation pipe is vertically bent to the bottom of the absorption tower, and the distance from the bottom of the absorption tower is d2 (d2=1.0m-2.0m). The slurry inside each isolation settling pipe will be unable to flow due to the isolation effect of the pipe itself and will settle naturally. After settling, the solids in the slurry will sink to the lower part of the isolation settling pipe until flowing out of the isolation settling pipe. The supernatant will remain in the upper part of the isolation settling pipe and can be automatically discharged out of the absorption tower under the pressure generated by the height difference between the absorption tower liquid level and the isolation settling pipe. The supernatant flowing out of the absorption tower can realize the decrease of the liquid level of the absorption tower slurry pool 1, which is beneficial to the control of the water balance of the absorption tower.

[0030] The external collecting pipe 5 is connected to the isolation sedimentation pipe group 4 outside the absorption tower. The supernatant of the isolation sedimentation pipe group 4 can be led out of the absorption tower through the external collecting pipe 5. Considering that the solid content of the supernatant is relatively low and meets the requirements of the demisting and dust removal device 3 for flushing water quality, a new collecting pit 6 is built to collect the supernatant. At the same time, a pump group 7 is set to pump it into the demisting and dust removal device flushing water system 8 for flushing the demisting and dust removal device 3, which is used for flushing the demisting and dust removal device 3 to replace process water flushing.

[0031] Based on the above system, the present invention also provides a method for controlling the liquid level of an absorption tower, comprising the following steps:

[0032] When the isolation settling tube group 4 is inserted into the absorption tower, the slurry inside the isolation settling tube group 4 will be isolated by the isolation settling tube group 4 itself and cannot flow;

[0033] The slurry with a high solid content naturally settles in the isolation settling pipe group 4 and sinks to the bottom of the isolation settling pipe group 4 until it flows out of the isolation settling pipe group 4;

[0034] The supernatant will remain on the upper part of the isolation settling tube group 4 and will be automatically discharged from the absorption tower by utilizing the height difference between the absorption tower liquid level and the isolation settling tube group 4; the absorption tower liquid level and water balance are controlled by controlling the supernatant discharge amount.

[0035] The supernatant discharged from the absorption tower is led out through the external collecting pipe 5 and flows into the collecting pit 6 , and the supernatant is pumped into the mist removal and dust removal device flushing water system 8 through the pump group 7 for flushing the mist removal and dust removal device 3 .

[0036] The present invention is suitable for wet flue gas desulfurization, and can effectively separate the solid and liquid of part of the slurry in the absorption tower slurry pool 1. The separated supernatant can be discharged from the absorption tower in time for secondary utilization, which can effectively control the liquid level and water balance of the absorption tower, thereby avoiding the increase in operating costs caused by increasing the discharge of desulfurization wastewater in order to control the liquid level and water balance of the absorption tower. At the same time, the supernatant is collected to replace the process water for flushing the demisting and dust removal device 3, thereby replacing the consumption of this part of the process water, and has a certain water-saving effect.

Claims

1. A system for controlling the liquid level of an absorption tower, characterized in that: It comprises an isolation settling pipe group (4) installed in a slurry pool (1) of an absorption tower and an external collecting pipe (5) arranged outside the absorption tower; The isolation settling pipe group (4) comprises a plurality of isolation settling pipes; the isolation settling pipes are evenly arranged along the circumference of the absorber slurry pool (1); each isolation settling pipe is obliquely inserted into the absorber slurry pool (1), and after being inserted into the absorber, it is vertically bent toward the bottom of the absorber, and the top end extending outside the absorber is connected to the outer collecting pipe (5); The top of the isolation settling pipe and the height of the external collecting pipe (5) are both lower than the designed liquid level of the absorption tower.

2. A system for controlling the liquid level of an absorption tower according to claim 1, characterized in that: The distance between the insertion point of each isolation settling pipe into the absorption tower slurry pool (1) and the designed liquid level of the absorption tower is 1.5m-2.0m, and the distance between the bottom end of each isolation settling pipe and the bottom of the absorption tower is 1.0m-2.0m.

3. A system for controlling the liquid level of an absorption tower according to claim 1, characterized in that: The isolation sedimentation tube group (4) comprises 8 to 16 isolation sedimentation tubes.

4. A system for controlling the liquid level of an absorption tower according to claim 1, characterized in that: The nominal diameter of a single pipe of the isolation sedimentation pipe is in the range of 0.15m-0.5m.

5. A system for controlling the liquid level of an absorption tower according to claim 1, characterized in that: It also includes a collection pit (6) arranged outside the absorption tower; the input end of the collection pit (6) is connected to the collection pipe (5) outside the tower.

6. A system for controlling the liquid level of an absorption tower according to claim 5, characterized in that: The output end of the collection pit (6) is connected to the input end of the mist removal and dust removal device flushing water system (8) through a pump group (7).

7. A method for controlling the liquid level of an absorption tower, characterized in that: The system according to any one of claims 1 to 6 above comprises: When the isolation settling pipe group (4) is inserted into the absorption tower, the slurry inside the isolation settling pipe group (4) will be isolated by the isolation settling pipe group (4) itself and will not be able to flow; The slurry with a high solid content naturally settles in the isolation settling pipe group (4) and sinks to the bottom of the isolation settling pipe group (4) until it flows out of the isolation settling pipe group (4); The supernatant will remain on the upper part of the isolation settling pipe group (4) and will be automatically discharged from the absorption tower by utilizing the height difference between the absorption tower liquid level and the isolation settling pipe group (4); the absorption tower liquid level and water balance are controlled by controlling the supernatant discharge amount.

8. A method for controlling the liquid level of an absorption tower according to claim 7, characterized in that: The supernatant liquid discharged from the absorption tower is led out through the external collection pipe (5) and flows into the collection pit (6). The supernatant liquid is pumped into the demisting and dust removal device flushing water system (8) through the pump group (7) for flushing the demisting and dust removal device (3).

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