Intelligent control method for boiler flue gas desulfurization wastewater recovery

Abstract

The present application relates to the field of power plant desulfurization wastewater recovery method, specifically relates to an intelligent control method for boiler flue gas desulfurization wastewater recovery, obtains the working mode of the integrated equipment formed by the sedimentation tank, flocculation tank and clarifier for wastewater transmission in overflow mode, and the working mode comprises automatic mode and manual mode;When the working mode is the automatic mode, the flow value of the wastewater buffer tank to the stirring tank in front of the sedimentation tank is compared with the threshold value, when the flow value is greater than the threshold value, the stirring tank and the dosing tank are controlled to start working at the same time, and when the flow value is less than the threshold value, the dosing tank and the stirring tank are controlled to stop. The control target quantity of the present application is less, the control process is simple, and the problem of control confusion is prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power plant desulfurization wastewater recovery method, and particularly relates to an intelligent control method for boiler flue gas desulfurization wastewater recovery. BACKGROUND

[0002] During the power generation process of a coal-fired power plant, flue gas containing sulfur gas and moisture is usually discharged, which pollutes the environment greatly, so the pollutants need to be removed and the moisture needs to be recovered. The main method of pollutant removal is wet limestone-gypsum desulfurization, which is carried out in an absorption tower device. The discharge water produced after the absorption tower treatment is desulfurization wastewater. The desulfurization wastewater contains a large amount of suspended solids, supersaturated sulfite, sulfate and heavy metals and other impurities, and the desulfurization wastewater also needs to be treated and recovered.

[0003] The treatment and recovery process of the desulfurization wastewater is discharged after treatment through a wastewater tank, a wastewater lifting pump, a pH neutralized wastewater buffer tank, a sedimentation tank, a flocculation tank, a clarifier, a water outlet tank and a water outlet pump. In order to make the desulfurization wastewater treatment and recovery process more accurate, a literature "a wet desulfurization wastewater dosing system" discloses a triple tank including a neutralization tank, a reaction tank and a flocculation tank connected in sequence, the inlet of the neutralization tank is connected with the wastewater tank, and the outlet of the flocculation tank is connected with the clarifier; the dosing tank includes an organic sulfur dosing tank, a flocculant dosing tank and a coagulant dosing tank, and the dosing tank is arranged above the triple tank; the liquid outlet of the organic sulfur dosing tank is provided with a flow control valve and connected to the inlet side of the reaction tank; the liquid outlet of the flocculant dosing tank is provided with a flow control valve and connected to the outlet side of the reaction tank; the liquid outlet of the coagulant dosing tank is provided with a flow control valve and connected to the flocculation tank; the flow control valves are connected with a controller. The dosing is carried out by the self height pressure difference of the dosing tank, the metering pump is cancelled, the equipment investment and maintenance work are reduced, the efficiency is improved, and the energy consumption and investment cost are reduced.

[0004] However, the above system only controls the dosing of each tank in the triple tank and reduces the metering pump, but the dosing control of the multiple tanks included in the triple tank needs to detect parameters and control respectively, the whole control process is complex, and control confusion is easily caused. SUMMARY

[0005] The present application aims to provide an intelligent control method for boiler flue gas desulfurization wastewater recovery to solve the problems of complex dosing control process and easy control confusion.

[0006] The intelligent control method for boiler flue gas desulfurization wastewater recovery in the present application includes the following steps:

[0007] Step 1, obtain the working mode of the integrated equipment formed by the sedimentation tank, flocculation tank and clarifier for overflow wastewater conveying, the working mode includes automatic mode and manual mode;

[0008] Step 2, when the working mode is the automatic mode, compare the flow value of the wastewater buffer tank conveying wastewater to the front end of the stirring tank with the threshold value, when the flow value is greater than the threshold value, simultaneously control the stirring tank and the dosing tank to start working, when the flow value is less than the threshold value, control the dosing tank and the stirring tank to stop.

[0009] The beneficial effects of the present scheme are:

[0010] In the desulfurization wastewater treatment process, based on the working mode of the integrated equipment, the flow value of the stirring tank conveying wastewater is obtained, and the starting or stopping of the stirring tank and the dosing tank is controlled according to the relationship between the flow value and the threshold value, the control target is only the stirring tank and the dosing tank at the front end of the integrated equipment, the number of control targets is small, the control process is simple, the problem of control confusion is prevented, and the control speed is improved.

[0011] Further, in step 2, the dosing tank is arranged to add reagent to the buffer groove near the top end of the inner wall of the stirring tank, the volume of the buffer groove is set to one-eighth of the volume of the stirring tank, and the inner wall of the buffer groove is provided with a plurality of spiral arc grooves to keep the desulfurization wastewater pumped from the water inlet end of one arc groove.

[0012] The beneficial effects are: the desulfurization wastewater initially pumped into the stirring tank is guided from the spiral arc groove, which can form a spiral water flow in the small space of the buffer groove, and the flow power of the water flow can automatically mix the reagent added by the dosing tank with the desulfurization wastewater, without the need for additional stirring and mixing mechanisms, simplifying the equipment and improving the treatment effect after dosing.

[0013] Further, in step 2, when the flow value is greater than the threshold value, it is judged in real time whether the flow value increase is greater than one-half of the threshold value and less than the threshold value, when the flow value increase is greater than one-half of the threshold value and less than the threshold value, the dosing tank is controlled to increase the reagent dosage by 1.3 times, when the flow value increase is greater than the threshold value, the dosing tank is controlled to gradually increase the reagent dosage at equal time intervals based on 1.4 times and with a step size of 0.1 times.

[0014] The beneficial effects are: according to the increase of the desulfurization wastewater flow value, the reagent dosage of the dosing tank is increased by different multiples, the reagent dosage of the dosing tank is adjusted in time and quickly, the desulfurization wastewater can be stirred in a small space at the moment of dosing to mix the reagent and the desulfurization wastewater, and sufficient reagent and desulfurization wastewater are fully mixed and contacted, so that the desulfurization wastewater has a good pretreatment effect when pumped.

[0015] Further, in the step 2, when the flow value increase amount is greater than the threshold value, the designed stirring speed and the actual stirring speed of the stirring tank near the settling tank are obtained, and the speed difference is obtained by subtracting the actual stirring speed from the designed stirring speed, the stirring resistance is compared with the difference value, and when the speed difference is greater than the difference value, it is judged that the stirring resistance is large, and the dosing amount of the dosing tank is controlled to return to the initial value, and when the speed difference is greater than zero and less than the difference value, the dosing amount of the dosing tank is controlled to stop increasing.

[0016] The beneficial effect is that the stirring speed change of the stirring tank is used to judge the stirring resistance after adding the reagent, which can directly and quickly judge the formation of solid matter after adding the reagent, and then dynamically adjust the dosing amount in real time during the process of increasing the desulfurization wastewater and increasing the reagent, so that the dosing amount is more accurate, and at the same time, the blockage of the overflow channel in the integrated equipment caused by the formation of too much solid matter is prevented, and the processing smoothness and processing efficiency of the integrated treatment equipment are maintained.

[0017] Further, in the step 1, the stirring liquid level value of the stirring tank, the sludge liquid level value of the sludge tank below the integrated equipment, and the effluent liquid level value of the effluent tank behind the integrated equipment are obtained.

[0018] Further, in the step 1, the stirring liquid level value of the stirring tank, the sludge liquid level value of the sludge tank below the integrated equipment, and the effluent liquid level value of the effluent tank behind the integrated equipment are obtained.

[0019] The beneficial effect is that the liquid level of the front and rear ends of the integrated equipment is used to judge, and the working mode of the wastewater lifting pump is switched based on the liquid level of the equipment at different positions, which can prevent the sludge tank and the effluent tank from being too full and abnormal at the source of the desulfurization wastewater while keeping the dosing tank control to put the reagent in contact with the desulfurization wastewater.

[0020] Further, the parking liquid level is 2.1m, the first protection liquid level is 2.5m, and the second liquid level is 3.5m.

[0021] The beneficial effect is that by setting the limited liquid level, the flow of the whole equipment can be accurately limited, so that the reagent of only one dosing tank can be fully contacted and mixed with the desulfurization wastewater.

[0022] Further, in step 3, when the sludge liquid level value is above the first protection liquid level, or the effluent liquid level value is above the second protection liquid level, the working mode of the integrated device is switched to the manual mode, and the dosing amount of the dosing tank is restored to the initial state.

[0023] The beneficial effect is that the working mode of the integrated device is switched based on the liquid levels of the sludge tank and the effluent tank at the rear end of the desulfurization wastewater, so that the integrated device can work in the most suitable working mode, and the dosing of the dosing tank is fed back from the rear end to improve the accuracy of the desulfurization wastewater treatment.

[0024] Further, in step 2, the dosing tank adds the reagent at a preset distance from the bottom of the buffer groove on the side wall of the stirring tank, and the preset distance is 5 cm.

[0025] The beneficial effect is that the reagent is added from the buffer groove on the inner wall of the stirring tank, which can form a certain degree of spiral flow after the pump is added to the desulfurization wastewater, so that the desulfurization wastewater can be fully contacted with the reagent, preventing the reagent from adhering to the inner wall of the buffer groove and being wasted. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figure is a schematic diagram of the embodiment of the intelligent control method for boiler flue gas desulfurization wastewater recovery. DETAILED DESCRIPTION

[0027] The embodiment will be further described in detail below.

[0028] Embodiment one

[0029] To realize the intelligent control method for boiler flue gas desulfurization wastewater recovery, the embodiment also discloses a boiler flue gas desulfurization wastewater recovery system, which sequentially comprises a wastewater buffer pool, a stirring tank one, a stirring tank two, an integrated device, a sludge tank and an effluent tank according to the flow direction of the desulfurization wastewater. The wastewater buffer pool transmits the desulfurization wastewater to the buffer groove at the top end of the inner wall of the stirring tank one through a wastewater lifting pump. The volume of the buffer groove is one percent of the volume of the stirring tank one. The stirring tank one and the stirring tank two transmit the wastewater through an overflow channel from bottom to top. The integrated device comprises a settling tank, a flocculation tank and a clarifier which are sequentially arranged according to the flow direction of the wastewater. The stirring tank two and the settling tank transmit the wastewater through an overflow channel from bottom to top. The settling tank, the flocculation tank and the clarifier transmit the wastewater through an overflow channel from bottom to top. The sludge tank is arranged below the integrated device through a pipeline. The effluent tank is connected through the overflow channel near the top of the clarifier.

[0030] The intelligent control method for boiler flue gas desulfurization wastewater recovery, as shown in Figure 1 , comprises the following steps:

[0031] Step 1, obtain the working mode of the integrated equipment formed by the overflow type wastewater conveying sedimentation tank, flocculation tank and clarifier, the working mode includes automatic mode and manual mode, and the working mode of the integrated equipment is recorded by the corresponding DCS system.

[0032] Step 2, when the working mode is the automatic mode, the flow value of the wastewater buffer tank conveying wastewater to the front end of the stirring tank of the sedimentation tank is compared with the threshold value, the flow value is detected by the flow sensor in the stirring tank and recorded by the DCS system, when the flow value is greater than the threshold value, the stirring tank and the dosing tank are simultaneously controlled to start working, when the flow value is less than the threshold value, the threshold value is 5m 3 / h, the dosing tank and the stirring tank are controlled to stop.

[0033] In step 2, the dosing tank is arranged to add reagent to the buffer groove near the top of the inner wall of the stirring tank at the water inlet end, that is, the stirring tank is provided with a buffer groove, the volume of the buffer groove is set to one eighth of the volume of the stirring tank, and the inner wall of the buffer groove is provided with a plurality of spiral arc grooves to keep the desulfurization wastewater pumped from one arc groove at the water inlet end.

[0034] When the flow value is greater than the threshold value, it is judged in real time whether the flow value increase is greater than one half of the threshold value and less than the threshold value, the flow value increase is obtained by subtracting the previous flow value from the subsequent flow value, when the flow value increase is greater than one half of the threshold value and less than the threshold value, the dosing tank is controlled to increase the reagent dosage by 1.3 times, for example, the original reagent dosage is N, and the reagent dosage is increased by 1.3N, the increase of the dosing tank is realized by increasing the opening degree of the reagent inlet, when the flow value increase is greater than the threshold value, the dosing tank is controlled to gradually increase the reagent dosage at equal time intervals based on 1.4 times and with a step of 0.1 times, the equal time intervals are set according to actual needs, for example, the equal time intervals are set to 5 minutes, that is, when the flow value increase is greater than the threshold value, the reagent is first added at an increase of 1.4N, and then the reagent is added at an increase of 1.5 times after the equal time intervals.

[0035] The stirring tank is provided with two, when the flow value increase is greater than the threshold value, the design stirring speed and the actual stirring speed of the stirring tank near the sedimentation tank are obtained, and the difference between the design stirring speed and the actual stirring speed is obtained to obtain the speed difference, the speed difference is compared with the difference value and the stirring resistance is judged, the difference value is set according to actual conditions, for example, the difference value is set to 1, when the speed difference is greater than the difference value, it is judged that the stirring resistance is large, and the reagent dosage of the dosing tank is controlled to return to the initial value, when the speed difference is greater than zero and less than the difference value, the reagent dosage of the dosing tank is controlled to stop increasing.

[0036] In the desulfurization wastewater treatment process, based on the working mode of the integrated equipment, the flow value of the wastewater transmitted by the stirring tank is obtained, the starting or stopping of the stirring tank and the dosing tank is controlled according to the relationship between the flow value and the threshold value, and the increase and decrease of the flow value is judged. When the flow value increases greatly, the dosing tank increases the dosing amount by a fixed multiple, and when the flow value increases greatly, the dosing tank gradually increases the dosing amount by a fixed multiple. The appropriate amount of medicament can be dosed according to the change of the flow value to carry out reaction treatment, so that the desulfurization wastewater treatment is more timely and complete. When the flow value increases by more than the threshold value, the stirring resistance is judged based on the change of the rotating speed of the settling tank. When the stirring resistance is light, the dosing amount of the dosing tank is reduced, and when the stirring resistance is heavy, the dosing of the dosing tank is stopped, so that the desulfurization wastewater can be treated at different degrees in different equipment tanks to prevent the subsequent overflow channel from being blocked due to too much solid matter formed by dosing reaction. In the overall control process of the embodiment, the control target is only the stirring tank and the dosing tank at the front end of the integrated equipment, the number of control targets is small, the control process is simple, the problem of control confusion is prevented, the reaction speed is improved, and the desulfurization wastewater can be reacted and treated to a proper degree, thereby improving the desulfurization wastewater treatment effect.

[0037] Embodiment two

[0038] The intelligent control method for boiler flue gas desulfurization wastewater recovery is different from embodiment one in that in step 1, the stirring liquid level value of the stirring tank, the sludge liquid level value of the sludge tank below the integrated equipment, and the effluent liquid level value of the effluent tank behind the integrated equipment are obtained.

[0039] In step 2, the dosing tank adds medicament from the buffer groove at a preset distance above the bottom of the stirring tank side wall, and the preset distance is 5 cm.

[0040] Step 3 is also included, that is, the working mode of the wastewater lifting pump for transmitting desulfurization wastewater to the stirring tank is obtained. When the working mode of the wastewater lifting pump is automatic mode, it is judged in real time whether the stirring liquid level value is below the parking liquid level, whether the sludge liquid level value is above the first protection liquid level, and whether the effluent liquid level value is above the second protection liquid level. When the liquid level value is below the parking liquid level, or the sludge liquid level value is above the first protection liquid level, or the effluent liquid level value is above the second protection liquid level, the working mode of the wastewater lifting pump is switched to manual mode. The parking liquid level is 2.1 m, the first protection liquid level is 2.5 m, and the second liquid level is 3.5 m. When the sludge liquid level value is above the first protection liquid level, or the effluent liquid level value is above the second protection liquid level, the working mode of the integrated equipment is switched to manual mode, and the dosing amount of the dosing tank is restored to the initial state.

[0041] When it is judged that the wastewater lifting pump works in the automatic mode, the liquid levels of the multiple devices of the front and rear end mixing tanks, the water outlet tank and the sludge tank of the integrated device are judged, different liquid level limits are set for different devices, the working mode of the wastewater lifting pump is switched based on the liquid level conditions of the devices at different positions, the working mode of the wastewater lifting pump is accurately matched with the actual situation, and the liquid level of the sludge tank and the water outlet tank can be prevented from being too full and abnormal while the dosing tank control is kept at one place to put the medicament to fully contact the desulfurization wastewater.

[0042] The above is only an embodiment of the present application, and common knowledge such as specific structures and characteristics in the scheme is not described in detail. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should be considered as the protection scope of the present application, and these will not affect the effect and practicality of the present application. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. An intelligent control method for boiler flue gas desulfurization wastewater recovery, characterized in that, The method comprises the following steps: Step 1, obtaining the working mode of an integrated device formed by a sedimentation tank, a flocculation tank and a clarifier for wastewater delivery in an overflow manner, wherein the working mode comprises an automatic mode and a manual mode; Step 2, when the working mode is the automatic mode, comparing the flow value of the wastewater buffer tank to the front-end stirring tank of the sedimentation tank with a threshold value, when the flow value is greater than the threshold value, simultaneously controlling the stirring tank and the dosing tank to start working, when the flow value is less than the threshold value, controlling the dosing tank and the stirring tank to stop; The dosing tank is arranged to add reagent to the buffer groove near the top of the inner wall of the stirring tank, the volume of the buffer groove is set to be one-eighth of the volume of the stirring tank, and a plurality of spiral arc grooves are arranged on the inner wall of the buffer groove, so that the desulfurization wastewater is pumped from one arc groove at the water inlet end, and the dosing tank is controlled to add reagent from the buffer groove at the bottom of the side wall of the stirring tank to a preset distance upward, wherein the preset distance is 5 cm; When the flow value is greater than the threshold value, it is judged in real time whether the flow value increase is greater than one-half of the threshold value and less than the threshold value, when the flow value increase is greater than one-half of the threshold value and less than the threshold value, the dosing tank is controlled to increase the reagent dosage by 1.3 times, when the flow value increase is greater than the threshold value, the dosing tank is controlled to gradually increase the reagent dosage at equal time intervals based on 1.4 times and with a step of 0.1 times; The stirring tank is provided with two, when the flow value increase is greater than the threshold value, the design stirring speed and the actual stirring speed of the stirring tank near the sedimentation tank are obtained, and the difference between the design stirring speed and the actual stirring speed is obtained to obtain a speed difference, the speed difference is compared with a difference value and the stirring resistance is judged, when the speed difference is greater than the difference value, the reagent dosage of the dosing tank is restored to the initial value, when the speed difference is greater than zero and less than the difference value, the reagent dosage of the dosing tank is controlled to stop increasing.

2. The intelligent control method for boiler flue gas desulfurization wastewater recovery as claimed in claim 1, wherein: In step 1, the stirring liquid level value of the stirring tank, the sludge liquid level value of the sludge tank below the integrated device, and the effluent liquid level value of the effluent tank behind the integrated device are obtained; Step 3, obtaining the working mode of the wastewater lifting pump for delivering desulfurization wastewater to the stirring tank, when the working mode of the wastewater lifting pump is the automatic mode, it is judged in real time whether the stirring liquid level value is below the parking liquid level, whether the sludge liquid level value is above the first protection liquid level, and whether the effluent liquid level value is above the second protection liquid level, when the liquid level value is below the parking liquid level, or the sludge liquid level value is above the first protection liquid level, or the effluent liquid level value is above the second protection liquid level, the working mode of the wastewater lifting pump is controlled to be switched to the manual mode.

3. The intelligent control method for boiler flue gas desulfurization wastewater recovery as claimed in claim 2, wherein: The parking liquid level is 2.1 m, the first protection liquid level is 2.5 m, and the second protection liquid level is 3.5 m.

4. The intelligent control method for boiler flue gas desulfurization wastewater recovery as claimed in claim 2, wherein: In step 3, when the sludge liquid level value is above the first protection liquid level, or the effluent liquid level value is above the second protection liquid level, the working mode of the integrated device is controlled to be switched to the manual mode, and the reagent dosage of the dosing tank is controlled to be restored to the initial state.

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