CN111375302A

CN111375302A - Wet desulphurization energy-saving control method and system

Info

Publication number: CN111375302A
Application number: CN202010304568.8A
Authority: CN
Inventors: 罗跃彬; 李俊; 王岭; 吴文辉; 范怀强
Original assignee: Shanghai Longking Environmental Protection Co ltd
Current assignee: Shanghai Longking Environmental Protection Co ltd
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2020-07-07

Abstract

The invention discloses a wet desulphurization energy-saving control method, wherein at least one stage of a multi-stage spraying layer is provided with n partitions to form a partitioned spraying layer, and the n partitions are controlled to spray respectively; the method comprises the following steps: simulating tower-entering flue gas parameters under different working conditions in wet desulphurization treatment, calculating slurry circulation amount and slurry supply amount required under the current simulated working condition through material balance, and calculating the opening combination of each slurry circulating pump of a multistage spraying layer and each partition in a partition spraying layer according to the required slurry circulation amount to obtain an operation strategy under the current simulated working condition; different operation strategies obtained by calculation under different working conditions form a strategy library; when the absorption tower operates, screening an optimal strategy which is most matched with the current working condition from a strategy library according to tower entering flue gas parameters under the actual operating working condition; and operating according to an optimal strategy to perform flue gas treatment. The invention also provides a wet desulphurization energy-saving control system, which can reduce the running power consumption, save the cost and ensure the flue gas treatment efficiency.

Description

Wet desulphurization energy-saving control method and system

Technical Field

The invention belongs to the technical field of flue gas treatment, and relates to a wet desulphurization energy-saving control method and system.

Background

China is the biggest world coal producing country and also a big raw coal consuming country. The atmospheric pollutants generated by coal burning mainly comprise SO₂、NO_XDust, etc., wherein SO₂The emission is at the top of the world. Limestone-gypsum wet flue gas desulfurization (W-FGD) is one of the most widely used pollution gas control technologies in coal-fired power plants. Along with the development of electric power construction and the continuous increase of installed capacity of a power plant, the capacity of supporting equipment of the wet desulphurization device is gradually increased, the power consumption of the wet desulphurization device accounts for 1-1.5% of the generated energy of a unit, and the power consumption rate accounts for 20% of the plant power. The limestone-gypsum wet desulphurization device needs energy conservation, consumption reduction and intelligent operation, reduces the power consumption to the maximum extent on the premise of meeting the environmental protection requirement, and improves the economic benefit.

A flue gas desulfurization device of a 2 × 660MW power generator set of a certain inner Mongolia company adopts a limestone-gypsum wet flue gas desulfurization process, the desulfurization efficiency is more than or equal to 99 percent by arranging the limestone-gypsum wet flue gas desulfurization process in a furnace and a tower, and the process system comprises a limestone slurry preparation system, a flue gas system and an SO (sulfur oxide) system₂The absorption system, the gypsum dehydration system, the process water system, the discharge system and the wastewater treatment system are not provided with a booster fan or GHH; wherein the limestone slurry preparation system, the gypsum dehydration system, the process water system and the wastewater treatment system are shared by the two units. The statistics of the power consumption of each auxiliary machine and the public system are as follows:

	specific power consumption (two units)	Specific power consumption (one unit)
			Slurry circulating pump	76.2％	69.2％
Oxidation fan	7.4％	6.7％
			Wet ball mill	6.4％	5.8％
Public system	10％	18.3％

From the above table, under the large background of the emission requirement of "50355", the improvement of the desulfurization efficiency, the increase of the liquid-gas ratio and the increase of the number of spraying layers make the power consumption of the slurry circulating pump in the limestone-gypsum wet desulfurization device increasingly larger, and the power consumption rate reaches more than 70%. Therefore, the optimization of the spraying system and the intelligent energy conservation of the slurry circulating pump have great significance on the consumption reduction of the desulfurization device.

In view of the above technical problems, it is very necessary for those skilled in the art to provide a wet desulfurization energy-saving control method and system that can reduce the power consumption of operation, save the cost, and ensure the efficiency of flue gas treatment.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a wet desulphurization energy-saving control method and system which can reduce the power consumption of operation, save the cost and ensure the flue gas treatment efficiency.

One of the purposes of the invention is to provide a wet desulphurization energy-saving control system, which adopts the following technical scheme:

a wet desulphurization energy-saving control method comprises an absorption tower connected with a slurry supply system, wherein a demister, a multi-stage spraying layer and a slurry pool are sequentially arranged in the absorption tower from top to bottom; nozzles with downward openings are arranged on any one stage of spraying layer; the multistage spraying layers are respectively connected to the slurry tank through a circulating spraying pipeline with a slurry circulating pump; the method is characterized in that at least one stage of the multi-stage spraying layer is provided with n partitions to form a partitioned spraying layer, n is a positive integer and is not less than 2, and the n partitions are respectively communicated with a slurry tank through a circulating spraying pipeline and are used for controlling the n partitions to spray respectively;

the wet desulphurization energy-saving control method comprises the following steps:

simulating tower-entering flue gas parameters under different working conditions in wet desulphurization treatment, calculating slurry circulation amount and slurry supply amount required under the current simulated working condition through material balance, and calculating the opening combination of each slurry circulating pump of a multistage spraying layer and each partition in a partition spraying layer according to the required slurry circulation amount to obtain an operation strategy under the current simulated working condition; different operation strategies obtained by calculation under different working conditions form a strategy library;

when the absorption tower operates, screening an optimal strategy which is most matched with the current working condition from a strategy library according to tower entering flue gas parameters under the actual operating working condition;

and operating according to an optimal strategy to perform flue gas treatment.

Preferably, a slurry circulating pump on the circulating spray pipeline corresponding to the partitioned spray layer is set as a variable frequency pump, the n partitions are respectively communicated with the circulating spray pipeline with the variable frequency pump through spray branches, and partition control valves for controlling whether the corresponding partitions are sprayed or not are respectively arranged on the spray branches corresponding to the partitions; the combination of the slurry circulating pumps of the multistage spraying layer and the opening of each subarea in the subarea spraying layer is calculated according to the required slurry circulating amount: calculating the starting number of the slurry circulating pumps, the running frequency of the variable frequency pump and the starting number of the partition control valves according to the required slurry circulating amount;

preferably, the slurry circulating pump corresponding to the partition spraying layer comprises n slurry circulating branch pumps, and the n slurry circulating branch pumps are respectively communicated with the n partitions through circulating spraying pipelines; the combination of the slurry circulating pumps of the multistage spraying layer and the opening of each subarea in the subarea spraying layer is calculated according to the required slurry circulating amount: and calculating the starting number of the slurry circulating pumps and the starting number of the slurry circulating branch pumps according to the required slurry circulating amount.

Preferably, after the operation with the optimal strategy and the flue gas treatment, the method further comprises the following steps:

and when the tower outlet flue gas emission parameters exceed the standard, the strategy is replaced from the strategy library for operation.

Further, after the operation with the optimal strategy and the flue gas treatment, the method also comprises the following steps:

when the tower outlet flue gas parameters and/or slurry parameters are close to the limit values and the strategy is not changed, executing a first operation or a second operation, and correspondingly executing a third operation; the first operation is to adjust the starting number of the slurry circulating pumps and/or the running frequency of the variable frequency pumps and the starting number of the zone control valves so as to adjust the circulating amount of the slurry; the second operation is to adjust the starting number of the slurry circulating pumps and/or the starting number of the slurry circulating branch pumps so as to adjust the slurry circulating amount; the third operation is to adjust the frequency of a slurry supply pump in the slurry supply system so as to adjust the slurry supply amount; the stable standard emission of the flue gas discharged from the tower is realized by optimizing the operation strategy; and storing the optimized operation strategy into a strategy library.

Further, when the tower outlet flue gas parameter and/or the slurry parameter are close to the limit value and the strategy is not changed, executing a first operation or a second operation, and correspondingly executing a third operation; the first operation is to adjust the starting number of the slurry circulating pumps and/or the running frequency of the variable frequency pumps and the starting number of the zone control valves so as to adjust the circulating amount of the slurry; the second operation is to adjust the starting number of the slurry circulating pumps and/or the starting number of the slurry circulating branch pumps so as to adjust the slurry circulating amount; the third operation is to adjust the frequency of a slurry supply pump in the slurry supply system so as to adjust the slurry supply amount; the stable standard-reaching emission of the tower-outlet flue gas is realized by optimizing the operation strategy:

SO of flue gas as tower outlet₂When the concentration and/or the slurry PH value are close to the limit value and the strategy is not changed, the operation frequency of the variable frequency pump and the opening number of the partition control valves are adjusted, or the opening number of the slurry circulating branch pumps is adjusted to adjust the slurry circulating amount, the frequency of the slurry supply pump is correspondingly adjusted, and the adjustment of the liquid-gas ratio and the slurry supply amount is realized to reduce SO₂Concentration; when the frequency of the variable frequency pump reaches the maximum value, the SO of the flue gas discharged from the tower₂When the concentration is still close to the limit value, the number of the opened layers of the spraying layer is changed by adjusting the opening number of the slurry circulating pump, and the frequency of the slurry supply pump is correspondingly adjusted until the SO concentration is close to the limit value₂The concentration is reduced, and the tower outlet flue gas SO is realized by optimizing the operation strategy₂The concentration is stable and reaches the standard to be discharged;

and storing the optimized operation strategy into a strategy library.

The invention also provides a wet desulphurization energy-saving control system, which comprises an absorption tower connected with a variable-frequency slurry supply pump in a slurry supply system, wherein a demister, a multi-stage spraying layer and a slurry pool are sequentially arranged in the absorption tower from top to bottom; nozzles with downward openings are arranged on any one stage of spraying layer; the multistage spraying layers are respectively connected to the slurry tank through a circulating spraying pipeline with a slurry circulating pump; the method is characterized in that:

at least one stage of the multi-stage spraying layer is provided with n partitions to form a partitioned spraying layer, n is a positive integer and is more than or equal to 2, and the n partitions are respectively communicated with the slurry tank through a circulating spraying pipeline;

the wet desulphurization energy-saving control system also comprises:

a desulfurization DCS control system;

the desulfurization DCS control system comprises an instrument signal acquisition system; the instrument signal acquisition system comprises a PH meter for monitoring the parameters of the slurry in the absorption tower and a tower flue gas continuous monitoring system for monitoring the parameters of the flue gas entering and leaving the tower, wherein the parameters of the flue gas entering and leaving the tower comprise the flow rate of the flue gas and SO₂Concentration, dust concentration;

the desulfurization DCS control system is respectively and electrically connected with the plurality of slurry circulating pumps corresponding to the multistage spraying layers, is respectively in spraying control connection with the n subareas in the subarea spraying layer and is used for controlling the opening and closing of the slurry circulating pumps and/or each subarea in the subarea spraying layer; the desulfurization DCS control system is also electrically connected with a slurry supply pump and used for adjusting the slurry supply amount; the parameters of the flue gas discharged from the tower are continuously lower than the upper limit value;

an intelligent energy-saving module;

the intelligent energy-saving module is connected with the desulfurization DCS control system and used for simulating tower-entering flue gas parameters under different working conditions, calculating slurry circulation quantity and slurry supply quantity required under the current simulated working condition according to material balance, calculating the starting combination of each slurry circulating pump of the multistage spraying layer and each partition in the partition spraying layer according to the required slurry circulation quantity to obtain an operation strategy under the current simulated working condition, conveying the operation strategy to the desulfurization DCS control system, and storing different operation strategies obtained under different working conditions in a storage medium to form a strategy library;

and the system is also used for analyzing the working condition parameters of the flue gas entering the tower, and recommending the optimal strategy which is most matched with the current working condition parameters from the strategy library to the desulfurization DCS control system according to the working condition parameters.

Preferably, a slurry circulating pump on the circulating spray pipeline corresponding to the partitioned spray layer is set as a variable frequency pump, the n partitions are respectively communicated with the circulating spray pipeline with the variable frequency pump through spray branches, and partition control valves for controlling whether the corresponding partitions are sprayed or not are respectively arranged on the spray branches corresponding to the partitions; the variable frequency pump and the partition control valve are electrically connected with the desulfurization DCS control system; the intelligent energy-saving module is used for calculating the starting number of the slurry circulating pumps, the running frequency of the variable frequency pumps and the starting number of the partition control valves according to the required slurry circulating amount, and transmitting an operation instruction to the desulfurization DCS control system;

preferably, the slurry circulating pump corresponding to the partition spraying layer comprises n slurry circulating branch pumps, and the n slurry circulating branch pumps are respectively communicated with the n partitions through circulating spraying pipelines; the n slurry circulating branch pumps are all electrically connected with a desulfurization DCS control system; the intelligent energy-saving module is used for calculating the starting number of the slurry circulating pump and the slurry circulating branch pump according to the required slurry circulating amount and transmitting an operation instruction to the desulfurization DCS control system.

Preferably, the intelligent energy-saving module is further configured to replace the strategy from the strategy library of the storage medium when receiving a signal that the tower-out smoke emission of the desulfurization DCS control system exceeds the standard, and transmit the replaced strategy to the desulfurization DCS control system.

Further, the wet desulphurization energy-saving control system further comprises: a policy optimization module;

the strategy optimization module is electrically connected with the desulfurization DCS control system and is used for receiving the slurry parameters and/or the tower outlet flue gas parameters and comparing the slurry parameters and the limit values set in the desulfurization DCS control system, and if the tower outlet flue gas parameters and/or the slurry parameters are close to the limit values and the strategy is not changed, the strategy optimization module transmits an operation instruction for executing a first operation or a second operation to the desulfurization DCS control system and correspondingly executes a third operation; adjusting the starting number of the slurry circulating pumps and/or the running frequency of the variable frequency pump and the starting number of the zone control valves to adjust the circulating amount of the slurry; the second operation is to adjust the starting number of the slurry circulating pumps and/or the starting number of the slurry circulating branch pumps so as to adjust the slurry circulating amount; the third operation is to adjust the frequency of a slurry supply pump in the slurry supply system so as to adjust the slurry supply amount; the stable standard emission of the flue gas discharged from the tower is realized by optimizing the operation strategy;

the strategy optimization module is also in electric signal connection with the intelligent energy-saving module and used for storing the optimized operation strategy into a storage medium so as to update the strategy library.

Further, the continuous monitoring system for the flue gas entering and exiting the tower comprises SO₂A concentration detector;

the strategy optimization module is used for receiving the tower outlet flue gas SO₂The concentration and/or the pH value of the slurry are/is compared with the limit value set in the desulfurization DCS control system, and if the flue gas is discharged out of the tower, SO is generated₂If the concentration and/or the pH value of the slurry are close to or exceed the limit values and the strategy is not changed, transmitting instructions to a desulfurization DCS control system, controlling and adjusting the operating frequency of the variable frequency pump and the opening number of the zone control valves or adjusting the opening number of the slurry circulation branch pumps to adjust the slurry circulation amount and correspondingly adjust the slurry supply amountThe frequency of the pump realizes the adjustment of liquid-gas ratio and slurry supply amount to reduce SO₂Concentration; if the frequency of the variable frequency pump reaches the maximum value, the SO of the flue gas discharged from the tower₂If the concentration is still close to the limit value, transmitting an instruction to a desulfurization DCS control system, adjusting the starting number of the slurry circulating pumps to change the starting layer number of the spraying layer, and correspondingly adjusting the frequency of a slurry supply pump until the SO concentration is close to the limit value₂The concentration is reduced, and the tower outlet flue gas SO is realized by optimizing the operation strategy₂The concentration is stable and reaches the standard for discharge.

The invention can bring the following beneficial effects:

1) in the invention, at least 1 stage in the multi-stage spraying layer is partitioned, and the spraying control is respectively carried out on each partition, so that the spraying layer can realize the operation mode of combining the number of multi-stage commissioning layers and the number of n-stage commissioning partitions, and the electric energy of a wet desulphurization system can be saved. And a strategy library for storing a large number of strategies can be established according to different simulation working conditions, so that the closest strategy can be selected as the optimal strategy to operate according to the change of the flue gas working conditions conveniently and efficiently in actual operation, and the processing efficiency is improved.

2) The zonal spray control in the invention can adopt two setting forms, wherein n zonal control valves which are arranged in a way of distinguishing and correspond to the zonal spray layer are connected with a slurry circulating pipeline with a variable frequency pump, or slurry circulating pipelines with smaller slurry circulating sub-pumps with flow rates are respectively arranged in a way of corresponding to each zone; therefore, on the premise of meeting the requirement of standard wet flue gas treatment, the energy-saving operation of the slurry circulating pump is realized by adjusting the frequency of the variable frequency pump and controlling the start and stop of the partition control valves on each partition of the spraying layer or the starting number of the slurry circulating sub-pumps, so that the spraying layer can realize the operation mode of combining multiple commissioning layers and n-level commissioning partition numbers, the electric energy of the wet desulphurization system can be saved by about 10-15%, the use of slurry supply is reduced, and the cost is further saved.

3) In the control method, the slurry circulation amount and the slurry supply amount required under the current simulation working condition are calculated through material balance according to the simulation working condition change, and each slurry circulation pump in a multi-stage spraying layer and each subarea in a subarea spraying layer are calculated according to the required slurry circulation amountObtaining an operation strategy under the current simulation working condition; different operation strategies obtained by calculation under different working conditions form a strategy library to guide desulfurization operation; in actual operation, screening an optimal strategy which is most matched with the current working condition from a strategy library according to tower entering flue gas parameters under the actual operation working condition; operating with the optimal strategy, performing flue gas treatment after operating with the optimal strategy, because the working condition of the flue gas is constantly changed, and performing flue gas treatment by comparing the relevant parameters (which can be SO of the discharged flue gas)₂Concentration and slurry PH, etc.) such as when the parameter SO is₂When the concentration is close to the set control limit value and the strategy is not changed, the slurry circulation amount and the slurry supply amount can be adjusted by adjusting the frequency of the variable frequency pump, the opening number of the zone control valves and the frequency of the slurry supply pump, so that the liquid-gas ratio is finely adjusted; when the frequency of the variable frequency pump is adjusted to the maximum and the effect is still not good, more multi-stage spraying layers can be put into operation again to further adjust the liquid-gas ratio, SO that SO is ensured₂The concentration is discharged after reaching the standard, and the concentration is stored in a strategy library by an optimized operation strategy, so that the intelligent monitoring of the flue gas treatment, the automatic strategy analysis, adjustment, optimization and updating can be realized, and the energy-saving operation of the flue gas treatment under the premise of reaching the standard is ensured.

4) The method establishes a strategy library capable of storing a large number of strategies, and can select the closest strategy as the optimal strategy to operate according to the change of the flue gas working condition; the operating personnel can also adjust the operating strategy according to self experience, and the manual and automatic dual control modes can be realized.

Drawings

FIG. 1 is a flow chart of an embodiment of the wet desulfurization energy-saving control method of the present invention.

FIG. 2 is a flow chart of another embodiment of the wet desulphurization energy-saving control method of the present invention.

FIG. 3 is a flow chart of another embodiment of the wet desulfurization energy-saving control method of the present invention.

FIG. 4 is a schematic structural diagram (including circuit connections) of an embodiment of the wet desulphurization energy-saving control system according to the invention.

FIG. 5 is a schematic structural diagram (including circuit connections) of another embodiment of the wet desulphurization energy-saving control system according to the invention.

Fig. 6a is a schematic diagram of an embodiment of the zoned spray layer arrangement A, B zoned while spraying in accordance with the present invention.

Fig. 6b is a schematic diagram of the spraying in the partition a in fig. 6 a.

Fig. 6c is a schematic diagram of the spraying in the partition B in fig. 6 a.

Fig. 7a is a schematic diagram of another embodiment of the zoned spray layer arrangement A, B zoned while spraying in accordance with the present invention.

Fig. 7b is a schematic diagram of the spraying in the partition a in fig. 7 a.

Fig. 7c is a schematic diagram of the spraying in the partition B of fig. 7 a.

The reference numbers illustrate:

1-an absorption column; 2-an oxidation fan; 3-a slurry supply pump; 4-gypsum discharge pump; 5-a stirring device;

6-slurry circulating pump, 60-circulating spray pipeline, 6 a-variable frequency pump and 6 b-slurry circulating branch pump;

7-spraying layer, 7 a-subarea spraying layer, 7 aa-spraying main pipe, 7 ab-spraying branch pipe, 70-spraying branch pipe and 71-nozzle;

8-a zone control valve; 9-demister, 10-desulfurization DCS control system.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.

For the sake of simplicity, the drawings only schematically show the parts relevant to the present invention, and they do not represent the actual structure as a product.

One embodiment of the invention, as shown in fig. 1, is a wet desulphurization energy-saving control method, comprising an absorption tower 1 connected with a slurry supply system, wherein a demister 9, a multi-stage spray layer 7 and a slurry tank are sequentially arranged in the absorption tower 1 from top to bottom; a spray nozzle 71 with a downward opening is arranged on each stage of spraying layer 7; the slurry tank is connected to the spray layer 7 through a circulating spray pipe 60 with a slurry circulating pump 6;

at least one stage of the multi-stage spraying layer 7 is provided with n partitions to form a partitioned spraying layer 7a, n is a positive integer and is more than or equal to 2, and the n partitions are respectively communicated with the slurry tank through a circulating spraying pipeline 60 and are used for controlling the n partitions to spray respectively;

s100, simulating tower-entering flue gas parameters under different working conditions in wet desulphurization treatment, calculating slurry circulation quantity and slurry supply quantity required under the current simulated working condition through material balance, and calculating the opening combination of each slurry circulation pump of a multi-stage spraying layer and each partition in a partition spraying layer according to the required slurry circulation quantity to obtain an operation strategy under the current simulated working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

Specifically, different working conditions (flue gas flow and SO) in the wet desulphurization treatment are simulated₂Concentration variation, etc.), the slurry circulation amount and the slurry supply amount required under the current simulation working condition can be calculated according to the material balance, and the slurry circulation pumps which are arranged one by one corresponding to the multistage spraying layers and the opening combination of each subarea in the subarea spraying layers are calculated by combining the circulation flow of the actually used slurry circulation pump under the rated power and the circulation flow design parameters of each subarea, so that the circulation flow obtained by combination is equal to or very close to the required slurry circulation amount. Thereby, obtaining an operation strategy under the current simulation working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

S200, when the absorption tower runs, the optimal strategy which is most matched with the current working condition is screened from the strategy library according to the tower-entering smoke parameters under the actual running working condition.

Specifically, the tower-entering flue gas parameters under the actual operation working condition are compared with the simulated working condition flue gas parameters in the strategy library, the closest simulated working condition is screened out, and the strategy corresponding to the simulated working condition is used as the optimal strategy of the current flue gas working condition.

And S300, operating according to an optimal strategy to perform flue gas treatment.

Specifically, according to the optimal values of the slurry circulation amount and the slurry supply amount given by the strategy library, the desulfurization system is controlled to operate according to the optimal strategy.

In the embodiment, at least 1 stage of the multi-stage spraying layer is partitioned, and the spraying control is respectively carried out on each partition, so that the spraying layer can realize the operation mode of combining the number of multi-stage commissioning layers and the number of n-stage commissioning partitions, the electric energy of the wet desulphurization system can be saved by about 10-15%, and the slurry supply amount is saved. And a strategy library for storing a large number of strategies can be established according to different simulation working conditions, so that the closest strategy can be selected as the optimal strategy to operate according to the change of the flue gas working conditions conveniently and efficiently in actual operation, and the processing efficiency is improved.

As a preferable scheme, in this embodiment, 2 different partition spraying control modes for the partition spraying layer are preferably provided:

the first embodiment, as shown in fig. 4:

the slurry circulating pump on the circulating spray pipeline 60 corresponding to the partition spray layer 7a is set as a variable frequency pump 6a, the n partitions are respectively communicated with the circulating spray pipeline 60 with the variable frequency pump 6a through spray branches 70, and partition control valves 8 for controlling whether the corresponding partitions are sprayed or not are respectively arranged on the spray branches 70 corresponding to the partitions.

The control method for realizing energy conservation and wet desulphurization energy conservation adopts the frequency conversion design of the slurry circulating pump and the distinguishing design of the spraying layer, so that the proper combined starting mode of the power frequency slurry circulating pump and the distinguishing spraying can be selected according to the actual working condition in the operation, the full-power operation of the power frequency slurry circulating pump is not required, and the electric energy is saved on the premise of ensuring the treatment effect.

Correspondingly, the wet desulphurization energy-saving control method comprises the following steps:

s101, simulating tower-entering flue gas parameters under different working conditions in wet desulphurization treatment, calculating slurry circulation quantity and slurry supply quantity required under the current simulated working condition through material balance, and calculating the starting number of slurry circulating pumps, the operating frequency of a variable frequency pump and the starting number of partition control valves according to the required slurry circulation quantity to obtain an operating strategy under the current simulated working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

Specifically, parameters of flue gas entering the tower under different working conditions in wet desulphurization treatment are simulated, the circulation volume and the slurry supply volume of slurry required under the current simulated working conditions can be calculated according to material balance, the opening number of the slurry circulation pumps and the operating frequency of the variable frequency pumps and the opening number of the partition control valves are calculated by combining the circulation flow of the actually used slurry circulation pumps under rated power and the circulation flow design parameters of each partition, and the circulation flow obtained by combination is equal to or very close to the required slurry circulation volume; thereby, obtaining an operation strategy under the current simulation working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

The second embodiment, as shown in fig. 5:

the slurry circulating pump 6 corresponding to the partition spraying layer 7a comprises n slurry circulating branch pumps 6b, and the n slurry circulating branch pumps 6b are respectively communicated with the n partitions through circulating spraying pipelines 60; therefore, the circulation flow rate of the slurry circulation branch pump 6b is 1/n of the maximum slurry circulation flow rate of the subarea spraying layer.

The control method for realizing energy conservation and wet desulphurization energy conservation adopts the small chemical frequency design of the slurry circulating pump and the distinguishing design of the spraying layer, for example, when the number of the subareas is set to be 2, the corresponding 2 slurry circulating branch pumps 6b are respectively small power frequency pumps with 50 percent of circulating flow, so that a proper combined starting mode of the large-flow slurry circulating pump and the small-flow power frequency slurry circulating branch pump for subarea spraying can be selected according to the actual working condition during operation, the full-power operation of the large-flow slurry circulating pump is not required, and the electric energy is saved on the premise of ensuring the treatment effect.

s102, simulating tower-entering flue gas parameters under different working conditions in wet desulphurization treatment, calculating slurry circulation amount and slurry supply amount required under the current simulated working condition through material balance, and calculating the starting number of the slurry circulation pumps 6 and the starting number of the slurry circulation branch pumps 6b according to the required slurry circulation amount to obtain an operation strategy under the current simulated working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

Specifically, parameters of flue gas entering the tower under different working conditions in wet desulphurization treatment are simulated, the circulation volume and the slurry supply volume of slurry required under the current simulated working conditions can be calculated according to material balance, and the starting number of the slurry circulation pumps 6 and the starting number of the slurry circulation sub-pumps 6b are calculated by combining the circulation flow of the actually used slurry circulation pumps under rated power and the circulation flow design parameters of each subarea, so that the circulation flow obtained by combination is equal to or very close to the required slurry circulation volume; thereby, obtaining an operation strategy under the current simulation working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

Another embodiment of the invention, as shown in fig. 2, is a wet desulphurization energy-saving control method, comprising an absorption tower 1 connected with a slurry supply system, wherein a demister 9, a multi-stage spray layer 7 and a slurry tank are sequentially arranged in the absorption tower 1 from top to bottom; a spray nozzle 71 with a downward opening is arranged on each stage of spraying layer 7; the slurry tank is connected to the spray layer 7 through a circulating spray pipe 60 with a slurry circulating pump 6;

at least one stage of the multi-stage spraying layer 7 is provided with n partitions to form a partitioned spraying layer, n is a positive integer and is more than or equal to 2, and the n partitions are respectively communicated with the slurry tank through a circulating spraying pipeline 60 and used for controlling the n partitions to spray respectively;

Specifically, tower entering flue gas parameters under different working conditions in the wet desulphurization treatment are simulated, the slurry circulation amount and the slurry supply amount required under the current simulated working conditions can be calculated according to material balance, the opening combination of each slurry circulation pump of a multistage spraying layer and each partition in a partition spraying layer is calculated by combining the circulation flow of the actually used slurry circulation pump under the rated power and the circulation flow design parameters of each partition, the circulation flow obtained by combination is equal to or very close to the required slurry circulation amount, and the frequency of a slurry supply pump in a slurry supply system is correspondingly adjusted to provide the corresponding slurry circulation amount; thereby, obtaining an operation strategy under the current simulation working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions. As shown in fig. 3, step S100 may be implemented by any of step S101 and step S102 in the previous embodiment.

Specifically, according to the optimal values of the slurry circulation amount and the slurry supply amount given by the strategy library, the desulfurization system is controlled to operate according to the strategy.

And S400, when the tower outlet flue gas emission parameters exceed the standard, replacing the strategy from the strategy library and then operating.

In this embodiment, not only can establish the strategy storehouse of the storage a large amount of strategies to the simulation operating mode of difference to can be very convenient efficient select the closest strategy as the optimal strategy according to flue gas operating mode change and operate in actual operation, improve the treatment effeciency, can also carry out the strategy change after the operation simultaneously, in order to guarantee that the flue gas is up to standard to discharge, make the high-efficient and stable operation of desulfurization treatment.

Another embodiment of the present invention, as shown in fig. 3, is a wet desulphurization energy-saving control method, including the following steps:

S101/S102, simulating tower-entering flue gas parameters under different working conditions in wet desulphurization treatment, calculating slurry circulation amount and slurry supply amount required under the current simulated working condition through material balance, calculating the starting number of a slurry circulating pump according to the required slurry circulation amount, and calculating the starting number of a slurry circulating pump 6 and the starting number of a slurry circulating sub-pump 6b according to the operating frequency of a variable frequency pump and the starting number of a sub-zone control valve or the required slurry circulation amount to obtain an operating strategy under the current simulated working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

Specifically, tower entering flue gas parameters under different working conditions in the wet desulphurization treatment are simulated, the slurry circulation amount and the slurry supply amount required under the current simulated working conditions can be calculated according to material balance, the opening number of the slurry circulation pumps, the running frequency of the variable frequency pump and the opening number of the zone control valves are calculated by combining the circulation flow of the actually used slurry circulation pump 6 under the rated power and the circulation flow design parameters of each zone, or the opening number of the slurry circulation pumps 6 and the opening number of the slurry circulation sub-pumps 6b are calculated, so that the combined circulation flow is equal to or very close to the required slurry circulation amount, and the frequency of a slurry supply pump in a slurry supply system is correspondingly adjusted to provide the corresponding slurry circulation amount; thereby, obtaining an operation strategy under the current simulation working condition; and forming a strategy library by different operation strategies obtained by calculation under different working conditions.

S410, when the tower outlet flue gas parameter and/or the slurry parameter are close to the limit value and the strategy is not changed, executing a first operation or a second operation, and correspondingly executing a third operation; the first operation is to adjust the starting number of the slurry circulating pumps 6 and/or the running frequency of the variable frequency pump 6a and the starting number of the zone control valves 8 so as to adjust the slurry circulating amount; the second operation is to adjust the number of slurry circulation pumps 6 and/or the number of slurry circulation slave pumps 6b to adjust the slurry circulation amount; the third operation is to adjust the frequency of a slurry supply pump in the slurry supply system so as to adjust the slurry supply amount; the stable standard emission of the flue gas discharged from the tower is realized by optimizing the operation strategy; and storing the optimized operation strategy into a strategy library.

Specifically, when the parameters are close to or exceed the standard, corresponding operation is generally executed when the parameters are close to the minimum limit value exceeding the standard so as to control the outlet concentration, the liquid-gas ratio can be changed by adjusting the corresponding slurry circulation volume, and the flue gas treatment capacity is improved; based on the SO of the flue gas entering and exiting the tower₂The concentration difference value is used for correspondingly adjusting the frequency of a slurry supply pump in a slurry supply system to adjust the slurry supply amount, the slurry supply amount is adjusted under the condition of ensuring that the tower flue gas reaches the standard and is discharged, and on the basis of power saving, the limestone powder serving as the pulping raw material, specifically, the slurry supply amount and SO of the flue gas entering and exiting the tower are saved₂The concentration difference is linear, which is a common adjustment method for the pulp supply in the prior art, and is not described in detail herein.

Among them, preferred is SO in flue gas discharged from the tower₂When the concentration and/or the slurry PH value are close to the limit value and the strategy is not changed, the operation frequency of the variable frequency pump and the opening number of the partition control valves are adjusted, or the opening number of the slurry circulating branch pumps is adjusted to adjust the slurry circulating amount, the frequency of the slurry supply pump is correspondingly adjusted, and the adjustment of the liquid-gas ratio and the slurry supply amount is realized to reduce SO₂Concentration; when the frequency of the variable frequency pump reaches the maximum value, the SO of the flue gas discharged from the tower₂When the concentration is still close to the limit value, the number of the opened layers of the spraying layer is changed by adjusting the opening number of the slurry circulating pump until the SO₂The concentration is reduced, and the tower outlet flue gas SO is realized by optimizing the operation strategy₂The concentration is stable and reaches the standard to be discharged; and storing the optimized operation strategy into a strategy library.

In the preferred scheme, SO in tower flue gas can be taken out₂The concentration limit value is used as an index; setting a control limit according to the index, when the SO of the flue gas out of the tower₂When the concentration is close to the control limit, executing the first operation or the second operation, correspondingly executing the third operation to provide the actually required slurry circulation amount, and adjusting the tower outlet flue gas. Such as the maximum SO of export flue gas required by national standards₂The concentration is 35mg/Nm³Setting the control limit at 32mg/Nm³When the outlet SO is detected₂The concentration is close to 32mg/Nm³In the meantime, the liquid-gas ratio is adjusted (increased), the slurry supply is adjusted (increased), and the outlet SO is reduced by optimizing the operation strategy₂And (4) concentration.

In this embodiment, a policy library storing a large number of policies is used, a policy closest to the operating condition is selected as an optimal policy according to the variation of the flue gas, and after the operation, the operating condition of the flue gas is constantly changed, SO that the emission parameters of the flue gas discharged from the tower are such as SO₂When the concentration and the pH value of the slurry are close to or exceed the limit values, the slurry parameters in the absorption tower 1 can be dynamically adjusted, specifically, for example, the opening number of the partition control valves and the frequency of the variable frequency pump can be adjusted, or the opening number of the slurry circulating branch pumps can be adjusted, and the frequency of the slurry supply pump 3 can be correspondingly adjusted, so that the liquid-gas ratio and the slurry supply amount can be finely adjusted, and the tower outlet flue gas is ensured to be always discharged and reach the standard. And the optimized strategy can be used for updating the strategy library, so that the operation efficiency is gradually improved. Therefore, intelligent monitoring, automatic strategy analysis, adjustment, optimization and updating of flue gas treatment can be realized, and energy-saving operation of flue gas treatment on the premise of reaching the standard is ensured.

Still another embodiment of the present invention, as shown in fig. 4 and 5, is a wet desulphurization energy-saving control system, comprising an absorption tower 1 connected with a variable-frequency slurry supply pump 3 in a slurry supply system, wherein a demister 9, a multi-stage spray layer 7 and a slurry pool are sequentially arranged in the absorption tower 1 from top to bottom; a spray nozzle 71 with a downward opening is arranged on each stage of spraying layer 7; the slurry tank is connected to the spray layer 7 through a circulating spray pipe 60 with a slurry circulating pump 6;

the wet desulphurization energy-saving control system also comprises:

a desulfurization DCS control system 10;

the desulfurization DCS control system 10 comprises an instrument signal acquisition unit; the instrument signal acquisition unit comprises a PH meter for monitoring the parameters of the slurry in the absorption tower and a continuous flue gas monitoring unit for monitoring the parameters of the flue gas entering the absorption tower, wherein the instrument signal acquisition unit comprises a PH meter for monitoring the parameters of the slurry in the absorption tower and a continuous flue gas monitoring unit for monitoring the parameters of the flue gas entering the absorption towerThe parameters of the flue gas entering and exiting the tower comprise the flow rate of the flue gas and SO₂Concentration, dust concentration;

the desulfurization DCS control system 10 is respectively and electrically connected with the plurality of slurry circulating pumps 6 corresponding to the multistage spraying layers 7, is respectively in spraying control connection with n subareas in the subarea spraying layer and is used for controlling the opening and closing of the slurry circulating pumps 6 and/or each subarea in the subarea spraying layer; the desulfurization DCS control system 10 is also electrically connected with a slurry supply pump and used for adjusting the slurry supply amount; the parameters of the flue gas discharged from the tower are continuously lower than the upper limit value;

an intelligent energy-saving module;

the intelligent energy-saving module is connected with the desulfurization DCS control system 10 and used for simulating tower-entering flue gas parameters under different working conditions, calculating slurry circulation quantity and slurry supply quantity required under the current simulated working condition according to material balance, calculating the starting combination of each slurry circulation pump of the multistage spraying layer and each partition in the partition spraying layer according to the required slurry circulation quantity to obtain an operation strategy under the current simulated working condition, conveying the operation strategy to the desulfurization DCS control system, and storing different operation strategies obtained under different working conditions in a storage medium to form a strategy library;

In the embodiment, the strategy library can be established through the intelligent energy-saving module, and the optimal strategy is recommended, so that the efficient, stable and energy-saving operation of the wet desulphurization control system is facilitated, and the slurry supply amount can be saved. Wherein, the confession thick liquid system of the entry linkage of confession thick liquid pump 3 is limestone slurrying system, the export turn-on of confession thick liquid pump 3 is connected to absorption tower 1.

Specifically, the desulfurization DCS control system is an instrument control system commonly used for wet desulfurization treatment, and can adopt an ABL-PH-201 type desulfurization DCS control system; wherein, a continuous flue gas monitoring unit (CEMS) is integrated, and comprises a flue gas flow transmitter and an SO₂The concentration detector, the dust concentration monitor, the pressure transmitter, the temperature transmitter, the encoder, various relays and the like can realize the parameter of the flue gasVarious monitoring devices can also adopt other desulfurization DCS control systems which can realize the monitoring and control of the process in wet desulfurization and are provided by manufacturers of Harmonious time, Zhejiang province and Xinhua, Zhejiang province and the like, and the details are not repeated herein.

Preferably, as shown in fig. 4, the slurry circulating pump on the circulating spray pipe 60 corresponding to the partitioned spray layer 7a is a variable frequency pump 6a, n partitions are respectively communicated with the circulating spray pipe 60 with the variable frequency pump 6a through spray branches 70, and each spray branch 70 corresponding to each partition is respectively provided with a partition control valve 8 for controlling whether to spray the corresponding partition; the variable frequency pump 6a and the zone control valve 8 are electrically connected with a desulfurization DCS control system 10;

the intelligent energy-saving module is used for calculating the starting number of the slurry circulating pumps, the running frequency of the variable frequency pump and the starting number of the partition control valves according to the required slurry circulating amount, and transmitting an operation instruction to the desulfurization DCS control system 10.

Therefore, when the partition spraying control mode is combined by adopting the variable frequency pump and the partition control valve, the slurry can calculate the combined opening mode of the slurry circulating pump, the variable frequency pump and the partition control valve through the intelligent energy-saving module, and sends an instruction to the desulfurization DCS control system 10 to operate and run.

As another preferred embodiment, as shown in fig. 5, a trial test is carried out, in which the slurry circulation pump corresponding to the partition spraying layer 7a includes n slurry circulation sub-pumps 6b, and the n slurry circulation sub-pumps 6b are respectively communicated with n partitions through circulation spraying pipes 60; the n slurry circulating branch pumps 6b are all electrically connected with a desulfurization DCS control system 10;

the intelligent energy-saving module is used for calculating the starting number of the slurry circulating pumps and the starting number of the slurry circulating branch pumps according to the required slurry circulating amount and transmitting an operation instruction to the desulfurization DCS control system 10.

Therefore, when the small-flow slurry circulation branch pump is adopted in the partition spraying control mode, the intelligent energy-saving module can calculate the combined starting mode of the slurry circulation pump and the slurry circulation branch pump, and sends an instruction to the desulfurization DCS control system 10 to operate.

In another preferred embodiment, the intelligent energy-saving module is further configured to, when receiving a tower-out smoke emission standard exceeding signal of the DCS control system 10, replace the strategy from the strategy library of the storage medium, and transmit the replaced strategy to the DCS control system 10.

Therefore, strategy replacement can be performed through the intelligent energy-saving module, so that the desulfurization DCS control system 10 operates according to the replaced strategy, and the tower outlet flue gas parameters reach the standard and are discharged.

As a preferred further embodiment, the system further comprises a policy optimization module (not shown in the figure);

the strategy optimization module is electrically connected with the desulfurization DCS control system 10 and is used for receiving the slurry parameters and/or the tower outlet flue gas parameters and comparing the slurry parameters and the limit values set in the desulfurization DCS control system, and if the tower outlet flue gas parameters and/or the slurry parameters are close to or exceed the limit values and the strategy is not changed, the strategy optimization module transmits an operation instruction for executing a first operation or a second operation to the desulfurization DCS control system 10 and correspondingly executes a third operation; the first operation is to adjust the starting number of the slurry circulating pumps 6 and/or the running frequency of the variable frequency pump 6a and the starting number of the zone control valves 8 so as to adjust the slurry circulating amount; the second operation is to adjust the number of slurry circulation pumps 6 and/or the number of slurry circulation slave pumps 6b to adjust the slurry circulation amount; the third operation is to adjust the frequency of the slurry supply pump 3 in the slurry supply system to adjust the slurry supply amount; the stable standard emission of the flue gas discharged from the tower is realized by optimizing the operation strategy;

Preferably, the continuous monitoring system for the flue gas entering and exiting the tower comprises SO₂A concentration detector;

the strategy optimization module is used for receiving the tower outlet flue gas SO₂The concentration and/or the pH value of the slurry are/is compared with the limit value set in the desulfurization DCS control system, and if the flue gas is discharged out of the tower, SO is generated₂If the concentration and/or the pH value of the slurry are close to the limit values and no strategy change is caused, transmitting an instruction to a desulfurization DCS control system to control an adjustment changeThe operation frequency of the frequency pump and the opening number of the subarea control valves or the opening number of the slurry circulation branch pumps are adjusted to adjust the slurry circulation amount, the frequency of the slurry supply pump is correspondingly adjusted, and the adjustment of the liquid-gas ratio and the slurry supply amount is realized to reduce SO₂Concentration; if the frequency of the variable frequency pump reaches the maximum value, the SO of the flue gas discharged from the tower₂If the concentration is still close to the limit value, transmitting an instruction to a desulfurization DCS control system, adjusting the starting number of the slurry circulating pumps to change the starting layer number of the spraying layer, and correspondingly adjusting the frequency of a slurry supply pump to increase the slurry supply amount until the SO₂The concentration is reduced, and the tower outlet flue gas SO is realized by optimizing the operation strategy₂The concentration is stable and reaches the standard for discharge.

Thus, the policy optimization module of the present invention can analyze the export SO₂And (3) under the condition of parameters such as concentration, slurry pH value and the like, constructing desulfurization optimization strategies under different working condition variation trends, outputting slurry supply compensation values, and continuously optimizing according to the parameter conditions.

As a preferred further embodiment, the wet desulphurization control system further comprises an oxidation fan 2, a gypsum discharge pump 4, and a stirring device 5;

the outlet of the oxidation fan 2 is communicated and connected with the absorption tower 1; the inlet of the gypsum discharge pump 4 is connected with the absorption tower 1, and the outlet of the gypsum discharge pump 4 is communicated and connected to a gypsum dehydration system; and a stirring device 5 is arranged in the slurry pool at the bottom of the absorption tower 1.

As another preferred embodiment, the partitioned spray layer 7a includes n main spray pipes 7aa corresponding to n partitions disposed in the absorption tower 1, the n main spray pipes 7aa in the absorption tower 1 are arranged in parallel, and any main spray pipe 7aa is provided with a plurality of branch spray pipes 7ab at intervals along the length of the pipe; the nozzles 71 of the plurality of spraying branch pipes 7ab are arranged in a sinking type cross way; the n spraying main pipes 7aa are respectively communicated with the slurry tank through circulating spraying pipelines 60.

Another spraying setting mode can be adopted in this embodiment, specifically: the subarea spraying layer 7a comprises n symmetrical spraying main pipes 7aa which are correspondingly arranged outside the absorption tower 1, and any one spraying main pipe 7aa extends into the absorption tower 1 through a plurality of spraying branch pipes 7ab which are arranged at intervals along the length of the pipe to form n subareas; the nozzles 71 of the plurality of spraying branch pipes 7ab are arranged in a sinking type cross way; the n spraying main pipes 7aa are respectively communicated with the slurry tank through circulating spraying pipelines 60.

Therefore, the embodiment provides a specific implementation manner of the partitioned spraying, n partitions are formed by n spraying main pipes 7aa, each spraying main pipe 7aa is sprayed by combining the sunken type nozzles 71 which are arranged on the corresponding spraying branch pipes 7ab in a crossed manner through a plurality of spraying branch pipes 7ab which are spaced along the length of the spraying main pipe, so that the spraying coverage rate of each partition is higher when the partitions work simultaneously, and the flue gas treatment capacity is improved. Preferably, the spray branch pipes 7ab are uniformly arranged at intervals in the direction perpendicular to the spray main pipe 7aa, so that higher spray coverage rate is obtained.

In a preferred embodiment, the spraying coverage of any one of the subarea spraying layers 7a is more than 150%, and multiple times of spraying coverage can be obtained when each subarea works simultaneously, so as to ensure that the treated flue gas reaches the standard and is discharged.

As shown in fig. 6a, 6B, 6c or 7a, 7B, 7c, the single-stage zoned spray layer 7a is provided with two zones, zone a and zone B. In actual operation, on the premise of ensuring the coverage rate, according to the actual required slurry circulation amount, the partition operation of the single-stage partition spraying layer 7a can be opened for one partition corresponding to 50% of the slurry circulation amount, and can also be opened for 2 partitions corresponding to 100% of the slurry circulation amount. By the combination of the slurry circulating pump 6 and the opening of each subarea in the subarea spraying layer 7a, the circulating amount of the slurry reaches the required amount of material balance, the energy-saving operation is ensured, and the slurry supply amount is saved.

In addition, it should be noted that, during the flue gas treatment process, the desulfurization DCS control system 10 continuously recognizes the tower flue gas emission parameters, and may manually select an adjustment strategy from the strategy library of the intelligent energy saving module according to the parameter conditions.

Therefore, the intelligent energy-saving module is utilized to establish a strategy library capable of storing a large number of strategies, and the closest strategy can be automatically selected as the optimal strategy to operate according to the change of the working condition of the flue gas; the operating personnel can also adjust the operating strategy according to self experience, thereby realizing a manual and automatic dual-control mode.

The invention also provides an application example, taking the actual flue gas desulfurization parameters of a single 600MW unit of a certain domestic power plant as an example, the inlet flue gas volume of the engineering limestone-gypsum wet desulfurization system is 2139010Nm³H (standard, wet, actual oxygen), inlet SO₂Concentration 2415mg/Nm³Design outlet SO₂The concentration is 35mg/Nm³The desulfurization efficiency is more than or equal to 98.6 percent, the system is provided with four spraying layers corresponding to slurry circulating pumps #1 to #4, and the parameters are as follows:

serial number	Flow rate (m)³/h)	Rated power (Kw)	Shaft power (Kw)
				#1 slurry circulating pump	8300	800	670
#2 slurry circulating pump	8300	900	748
				#3 slurry circulating pump	8300	900	812
#4 slurry circulating pump	8300	1120	960

According to the control system and the control method provided by the invention, one layer of spraying system is changed into a subarea operation, taking a #4 slurry circulating pump as an example, the improved slurry circulating pump is provided with 2 subareas, the 2 subareas are respectively connected with a slurry pool by adopting 2 slurry circulating branch pumps 6B with smaller flow rate in a circulating and spraying way, and are respectively a #4 slurry circulating branch pump A and a #4 slurry circulating branch pump B, and the parameters are as follows:

serial number	Flow rate (m)³/h)	Rated power (Kw)	Shaft power (Kw)	Remarks for note
					#
4 serous fluid circulating slave cylinder A	4150	560	480	The control system of the invention
					#
4 serosity circulating slave cylinder B	4150	560	480	The control system of the invention

When the limestone-gypsum wet desulphurization system runs, the combination of slurry circulating pumps can be changed according to the change of unit load (different flue gas working conditions), the original system has four pumps, the combination can be 15, but because the flow of each pump is the same, the flow combination is 4 in total, and is integral multiple of the flow of a single slurry circulating pump; however, by using the technical scheme of the invention, 2-stage division can be performed on the corresponding spraying layer by replacing one pump with two small-flow slurry circulating branch pumps, so that the combination of the pumps is increased, and the combination of the flow rates is increased, thereby realizing 26 pump combinations and 8 flow rate combinations, which are as follows:

when the working condition of the boiler is 80% of the flue gas load, the circulation volume of the slurry required under the working condition is 28000m through material balance calculation and historical data analysis³H is greater than 24900m when three slurry circulating pumps are operated³H is less than 332000m when four pumps are running³And/h, under the working condition, only three circulation layers and a subarea (a slurry circulation pump) of the #4 circulation layer are needed to be started to meet the requirement of circulation amount, and electricity is saved by 460Kwh per hour.

By utilizing the control system and the control method, the total power consumption can be reduced by 10-15 percent and the total limestone consumption can be reduced by 10 percent.

It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A wet desulphurization energy-saving control method comprises an absorption tower connected with a slurry supply system, wherein a demister, a multi-stage spraying layer and a slurry pool are sequentially arranged in the absorption tower from top to bottom; nozzles with downward openings are arranged on any one stage of spraying layer; the multistage spraying layers are respectively connected to the slurry tank through a circulating spraying pipeline with a slurry circulating pump; the method is characterized in that at least one stage of the multi-stage spraying layer is provided with n partitions to form a partitioned spraying layer, n is a positive integer and is not less than 2, and the n partitions are respectively communicated with a slurry tank through a circulating spraying pipeline and are used for controlling the n partitions to spray respectively;

and operating according to an optimal strategy to perform flue gas treatment.

2. The wet desulphurization energy-saving control method according to claim 1, characterized in that:

a slurry circulating pump on the circulating spray pipeline corresponding to the partitioned spray layer is set as a variable frequency pump, the n partitions are respectively communicated with the circulating spray pipeline with the variable frequency pump through spray branches, and partition control valves for controlling whether the corresponding partitions are sprayed or not are respectively arranged on the spray branches corresponding to the partitions; the combination of the slurry circulating pumps of the multistage spraying layer and the opening of each subarea in the subarea spraying layer is calculated according to the required slurry circulating amount: calculating the starting number of the slurry circulating pumps, the running frequency of the variable frequency pump and the starting number of the partition control valves according to the required slurry circulating amount;

or;

the slurry circulating pump corresponding to the partition spraying layer comprises n slurry circulating branch pumps, and the n slurry circulating branch pumps are respectively communicated with the n partitions through circulating spraying pipelines; the combination of the slurry circulating pumps of the multistage spraying layer and the opening of each subarea in the subarea spraying layer is calculated according to the required slurry circulating amount: and calculating the starting number of the slurry circulating pumps and the starting number of the slurry circulating branch pumps according to the required slurry circulating amount.

3. The wet desulfurization energy-saving control method according to claim 1, further comprising the following steps after the flue gas treatment with the optimal strategy operation:

4. The wet desulfurization energy-saving control method according to claim 2, characterized in that after the flue gas treatment with the optimal strategy operation, the method further comprises the following steps:

when the tower outlet flue gas parameters and/or slurry parameters are close to the limit values and the strategy is not changed, executing a first operation or a second operation, and correspondingly executing a third operation; the first operation is to adjust the starting number of the slurry circulating pumps and/or the running frequency of the variable frequency pumps and the starting number of the zone control valves so as to adjust the circulating amount of the slurry; the second operation is to adjust the starting number of the slurry circulating pumps and/or the starting number of the slurry circulating branch pumps so as to adjust the slurry circulating amount; the third operation is to adjust the frequency of a slurry supply pump in the slurry supply system so as to adjust the slurry supply amount;

the stable standard emission of the flue gas discharged from the tower is realized by optimizing the operation strategy; and storing the optimized operation strategy into a strategy library.

5. The energy-saving control method for wet desulphurization according to claim 4, characterized in that when the tower-out flue gas parameter and/or slurry parameter approaches the limit value and no strategy change is caused, the first operation or the second operation is executed, and the third operation is executed correspondingly; the first operation is to adjust the starting number of the slurry circulating pumps and/or the running frequency of the variable frequency pumps and the starting number of the zone control valves so as to adjust the circulating amount of the slurry; the second operation is to adjust the starting number of the slurry circulating pumps and/or the starting number of the slurry circulating branch pumps so as to adjust the slurry circulating amount; the third operation is to adjust the frequency of a slurry supply pump in the slurry supply system so as to adjust the slurry supply amount; the stable standard-reaching emission of the tower-outlet flue gas is realized by optimizing the operation strategy:

and storing the optimized operation strategy into a strategy library.

6. A wet desulphurization energy-saving control system comprises an absorption tower connected with a variable-frequency slurry supply pump in a slurry supply system, wherein a demister, a multi-stage spraying layer and a slurry pool are sequentially arranged in the absorption tower from top to bottom; nozzles with downward openings are arranged on any one stage of spraying layer; the multistage spraying layers are respectively connected to the slurry tank through a circulating spraying pipeline with a slurry circulating pump; the method is characterized in that:

the wet desulphurization energy-saving control system also comprises:

a desulfurization DCS control system;

the desulfurization DCS control system comprises an instrument signal acquisition unit; the instrument signal acquisition unit comprises a PH meter for monitoring the parameters of the slurry in the absorption tower and a continuous flue gas monitoring unit for monitoring the parameters of the flue gas entering and leaving the tower, and the parameters of the flue gas entering and leaving the tower comprise the flow rate of the flue gas and SO₂Concentration, dust concentration;

an intelligent energy-saving module;

7. The wet desulfurization energy-saving control system according to claim 6, characterized in that:

a slurry circulating pump on the circulating spray pipeline corresponding to the partitioned spray layer is set as a variable frequency pump, the n partitions are respectively communicated with the circulating spray pipeline with the variable frequency pump through spray branches, and partition control valves for controlling whether the corresponding partitions are sprayed or not are respectively arranged on the spray branches corresponding to the partitions; the variable frequency pump and the partition control valve are electrically connected with the desulfurization DCS control system; the intelligent energy-saving module is used for calculating the starting number of the slurry circulating pumps, the running frequency of the variable frequency pumps and the starting number of the partition control valves according to the required slurry circulating amount, and transmitting an operation instruction to the desulfurization DCS control system;

or;

the slurry circulating pump corresponding to the partition spraying layer comprises n slurry circulating branch pumps, and the n slurry circulating branch pumps are respectively communicated with the n partitions through circulating spraying pipelines; the n slurry circulating branch pumps are all electrically connected with a desulfurization DCS control system; the intelligent energy-saving module is used for calculating the starting number of the slurry circulating pump and the slurry circulating branch pump according to the required slurry circulating amount and transmitting an operation instruction to the desulfurization DCS control system.

8. The wet desulfurization energy-saving control system according to claim 6, characterized in that:

and the intelligent energy-saving module is also used for replacing the strategy from the strategy library of the storage medium when receiving a signal that the tower-outlet smoke emission of the desulfurization DCS control system exceeds the standard, and transmitting the replaced strategy to the desulfurization DCS control system.

9. The wet desulfurization energy-saving control system according to claim 7, further comprising:

a policy optimization module;

10. The wet desulfurization energy-saving control system according to claim 9, characterized in that:

the continuous monitoring system for the flue gas entering and exiting the tower comprises SO₂A concentration detector;

the strategy optimization module is used for receiving the tower outlet flue gas SO₂The concentration and/or the pH value of the slurry are/is compared with the limit value set in the desulfurization DCS control system, and if the flue gas is discharged out of the tower, SO is generated₂If the concentration and/or the slurry PH value are close to the limit value and the strategy is not changed, transmitting an instruction to a desulfurization DCS control system, controlling and adjusting the operating frequency of the variable frequency pump and the opening number of the zone control valves or adjusting the opening number of the slurry circulation sub-pumps to adjust the slurry circulation amount and correspondingly adjust the frequency of the slurry supply pump, and realizing the adjustment of the liquid-gas ratio and the slurry supply amount to reduce SO₂Concentration; if the frequency of the variable frequency pump reaches the maximum value, the SO of the flue gas discharged from the tower₂If the concentration is still close to the limit value, transmitting an instruction to a desulfurization DCS control system, adjusting the starting number of the slurry circulating pumps to change the starting layer number of the spraying layer, and correspondingly adjusting the frequency of a slurry supply pump until the SO concentration is close to the limit value₂The concentration is reduced, and the tower outlet flue gas SO is realized by optimizing the operation strategy₂The concentration is stable and reaches the standard for discharge.