TWI779361B - Foaming suppression method and foaming suppression system - Google Patents

Abstract

In order to suppress the generation of foaming in the absorption liquid, the foaming suppression method includes a parameter value obtaining step, a first defoaming agent supply control step, and a second defoaming agent supply control step; the parameter value obtaining step is to obtain and At least one parameter value related to the foaming state of the absorbing liquid; the first defoaming agent supply amount control step is to determine that foaming has occurred in the absorbing liquid based on at least the parameter value obtained in the parameter value obtaining step, let The supply of the antifoaming agent toward the storage part is started or the supplying amount of the antifoaming agent is increased; the second step of controlling the supplying amount of the antifoaming agent is based on at least the parameter value acquired after the first step of controlling the supplying amount of the antifoaming agent On the other hand, when it is determined that the foaming of the absorbent liquid has disappeared, the supply amount of the antifoaming agent to the storage portion is reduced.

Description

Foam suppression method and foam suppression system

The present invention relates to a foaming suppressing method and a foaming suppressing system for suppressing foaming in an absorbing liquid used for desulfurizing exhaust gas in contact with exhaust gas introduced into an absorption tower.

Exhaust gas discharged from combustion equipment such as boilers contains air pollutants such as sulfur oxides (SOx), and therefore sulfur oxides are removed from the exhaust gas in an exhaust gas desulfurization device before being discharged into the atmosphere. As an exhaust gas desulfurization device, a wet type exhaust gas desulfurization device (for example, Patent Documents 1 and 2) is known, which makes the exhaust gas introduced into the absorption tower contact with an absorbing liquid (for example, limestone slurry), and makes the absorbing liquid Absorb sulfur oxides (for example, sulfurous acid gas) in the exhaust gas, by removing sulfur oxides from the exhaust gas.

In wet flue gas desulfurization equipment, the absorption liquid in the absorption tower often foams. For example, the absorbing liquid stored in the storage part may entrain the exhaust gas that it comes into contact with during the desulfurization of the exhaust gas, thereby generating fine air bubbles. Also, the absorption liquid stored in the storage part may generate air bubbles due to the action of components contained in the particulate coal dust collected from the exhaust gas and dispersed in the absorption liquid when the exhaust gas is desulfurized.

When foaming occurs in the absorption liquid in the absorption tower, various problems may arise. For example, the liquid level of the absorbing liquid stored in the storage part rises, and it may overflow from the inlet of the absorption tower (exhaust gas introduction port). Conventionally, as a countermeasure against foaming of the absorbing liquid, a method of injecting a defoaming agent into the absorbing liquid in the absorbing tower is adopted. After confirming foaming of the absorbing liquid from the outside of the absorbing tower, the defoaming agent is injected empirically. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-202204 [Patent Document 2] Japanese Patent Laid-Open No. 2003-340238

[Problem to be solved by the invention]

However, since the foaming state of the absorption liquid in the absorption tower can be grasped from the outside, there is a possibility that an appropriate amount of the antifoaming agent cannot be supplied to the absorption liquid. If the supply amount of the antifoaming agent to the absorbent liquid is insufficient, there is a possibility that the foaming state of the absorbent liquid cannot be suppressed. Also, if the supply of the antifoaming agent to the absorbing liquid is excessive, the oxidation performance of the absorbing liquid will be lowered, and therefore the desulfurization performance of the exhaust gas by the absorbing liquid may be lowered. In order to supply an appropriate amount of the antifoaming agent to the absorption liquid, it is necessary to accurately estimate the foaming state of the absorption liquid in the absorption tower.

In Patent Document 1, the power consumption of the pump used to transport the absorbent is measured, and the measured value is compared with a preset value to increase or decrease the amount of antifoaming agent added to the absorbent; The content of air bubbles in it is maintained at a certain level. In the invention described in Patent Document 1, since the antifoaming agent is added to the absorption liquid even though the power consumption of the pump is small, there is a possibility that the supply amount of the antifoaming agent to the absorption liquid is excessive.

Also in Patent Document 2, the oxidation-reduction potential of the absorbing liquid in a wet-type exhaust gas desulfurization device is measured, and the supply of oxygen-containing gas is adjusted according to the measured value of the redox potential of the absorbing liquid. When the above-mentioned measured value is as high as When the gas supply amount exceeds the adjustment range, a predetermined amount of oxidation inhibitor is supplied to the absorption liquid to adjust the oxidation-reduction potential of the absorption liquid. The problem to be solved in this patent document 2 is to reduce the COD (chemical oxygen demand) of the wastewater discharged from the wet-type exhaust gas desulfurization device, and there is no description related to the foaming state of the above-mentioned absorption liquid.

In view of the foregoing, an object of at least one embodiment of the present invention is to provide a foaming suppressing method and a foaming suppressing system capable of suppressing reduction in oxidation performance of the absorbent stored in the storage portion and suppressing foaming of the absorbent. [Technical means to solve the problem]

The foaming suppressing method of the present invention is a foaming suppressing method for suppressing the generation of foaming in the absorbing liquid for desulfurization of the exhaust gas used for contacting with the exhaust gas introduced into the absorption tower, and comprises: a parameter value obtaining step, a second 1. The control step of the supply amount of the defoamer, and the second control step of the supply amount of the defoamer; The aforementioned parameter value acquisition step is to acquire at least one parameter value related to the foaming state of the aforementioned absorption liquid; In the first antifoaming agent supply control step, at least based on the parameter values obtained in the parameter value obtaining step, it is determined whether foaming has occurred in the absorbent liquid, and when it is determined that foaming has occurred in the absorbent liquid, Start the supply of the antifoaming agent toward the storage part, or increase the supply amount of the antifoaming agent, and the storage part stores the absorption liquid after contacting the exhaust gas; The second antifoaming agent supply amount control step is to determine whether the foaming of the absorption liquid has disappeared based on at least the new parameter value obtained after the first antifoaming agent supply amount control step. When the foaming of the absorbent liquid disappears, the supply amount of the antifoaming agent to the storage portion is reduced.

The foaming suppressing system of the present invention is a foaming suppressing system for suppressing the generation of foaming of the absorbing liquid used for desulfurization of the exhaust gas in contact with the exhaust gas introduced into the absorption tower, and it is equipped with: at least one parameter value acquisition device , defoamer storage device, defoamer supply pipeline, and defoamer supply adjustment device, The aforementioned at least one parameter value acquisition device is to acquire at least one parameter value related to the foaming state of the aforementioned absorption liquid; The aforementioned defoamer storage device is to store the defoamer; The aforementioned antifoaming agent supply pipeline is to send the aforementioned antifoaming agent to the storage part from the aforementioned antifoaming agent storage device, and the aforementioned storage part is to store the aforementioned absorption liquid after contacting the aforementioned waste gas; The aforementioned antifoaming agent supply adjustment device can adjust the amount of the aforementioned antifoaming agent sent from the aforementioned antifoaming agent storage device to the aforementioned storage part through the aforementioned antifoaming agent supply line; The aforementioned antifoaming agent supply amount adjusting device is constituted as follows: It is determined at least based on the parameter value acquired by the at least one parameter value acquisition device whether foaming has occurred in the absorption liquid, and when it is determined that foaming has occurred in the absorption liquid, let the antifoaming agent toward the storage part Start the supply or increase the supply of the aforementioned antifoaming agent, In addition, it is determined whether the foaming of the absorbent liquid has disappeared based on at least the value of the parameter obtained after it is determined that the foaming of the absorbent liquid has occurred, that is, a new parameter value. When it is determined that the foaming of the absorbent liquid has disappeared , so that the supply amount of the antifoaming agent toward the aforementioned storage portion is reduced. [Effect of Invention]

According to at least one aspect of the present invention, there is provided a foam suppressing method and a foam suppressing system capable of suppressing the reduction of the oxidation performance of the absorbing liquid stored in the storage part and suppressing the foaming of the absorbing liquid.

Several embodiments of the present invention will be described below with reference to the drawings. The dimensions, materials, shapes, relative arrangements, etc. of components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial", etc., which indicate relative or absolute configurations, are not only strictly It means such an arrangement, and also means that there is a tolerance, or a state of relative displacement at an angle or distance to the extent that the same function can be obtained. Expressions such as "same", "equal", and "homogeneous" that indicate the state of equality of things not only strictly express such a state, but also indicate a state where there is a tolerance or a difference in the degree to which the same function can be obtained. For example, representations representing shapes such as quadrangular, cylindrical, etc. not only represent geometrically strictly defined quadrangular, cylindrical, etc. shapes, but also represent shapes having concavo-convex portions, chamfered portions, etc. within the range where the same effect can be obtained. On the other hand, the expression of "having", "comprising" or "having" a constituent element is not an exclusive expression that excludes the existence of other constituent elements. Also, the same symbols are assigned to the same configurations, and descriptions thereof may be omitted.

Fig. 1 is a flow chart of a method for suppressing foaming according to an embodiment of the present invention. Fig. 2 is a schematic configuration diagram schematically showing the configuration of an exhaust gas desulfurization system equipped with a foam suppression system according to an embodiment of the present invention. Hereinafter, the foaming suppression method according to several embodiments of the present invention will be described by taking the case where it is applied to a flue gas desulfurization system as shown in FIG. 2 as an example.

(exhaust gas desulfurization system) Exhaust gas desulfurization system 10, as shown in FIG. A gypsum separator 30 for dehydrating the gypsum slurry discharged from the exhaust gas desulfurization device 20 .

The flue gas desulfurization device 20 contacts the exhaust gas discharged from the combustion equipment 11 with the absorbing liquid, and allows the absorbing liquid to absorb sulfur oxides (such as sulfurous acid gas) in the exhaust gas, thereby removing sulfur oxides from the exhaust gas. For example, in the flue gas desulfurization device 20 using the lime gypsum method, a slurry containing alkaline components such as limestone slurry after dissolving (dispersing) limestone is used as the absorbing liquid, and gypsum slurry is produced as a by-product (absorbent fluid containing gypsum). Slurry is not strictly a liquid, but it is treated as a liquid for convenience in this specification.

The exhaust gas desulfurization device 20 includes an absorption tower 20A for desulfurizing the exhaust gas introduced therein. The absorption tower 20A includes an absorption tower body 22 , a waste gas inlet 23 , and a waste gas discharge port 24 . The absorption tower body 22 defines the internal space 21 inside, and the exhaust gas discharged from the combustion equipment 11 is introduced into the internal space 21; the exhaust gas inlet 23 is used to introduce the exhaust gas into the internal space 21; the exhaust gas outlet 24 is used to discharge the exhaust gas from the internal space. 21 exhaust gas is discharged. The absorption tower 20A includes: a waste gas supply line 12 for sending the waste gas from the combustion equipment 11 to the waste gas inlet 23 , and a waste gas discharge line 14 for sending the waste gas to the chimney 13 from the waste gas discharge port 24 .

The internal space 21 includes a gas-liquid contact portion 21A and a storage portion 21B. The gas-liquid contact part 21A is used to make the exhaust gas and the absorption liquid carry out gas-liquid contact; the storage part 21B is located below the gas-liquid contact part 21A, and is used to store the sulfur oxides ( Such as sulfurous acid gas) absorption liquid. The exhaust gas inlet 23 communicates with the internal space 21 below the gas-liquid contact portion 21A and above the storage portion 21B. The exhaust gas outlet 24 communicates with the internal space 21 above the gas-liquid contact portion 21A.

Exhaust gas discharged from the combustion facility 11 is introduced into the internal space 21 through the exhaust gas supply line 12 and the exhaust gas inlet 23 . The exhaust gas introduced into the internal space 21 flows while ascending in the internal space 21, and is washed by the absorbing liquid when passing through the gas-liquid contact portion 21A, whereby sulfur oxides and the like in the exhaust gas are removed. In the gas-liquid contact part 21A, the exhaust gas after removing sulfur oxides in the exhaust gas becomes purified exhaust gas, that is, purified gas, which passes through the exhaust gas discharge port 24 and the exhaust gas discharge pipeline 14, and is discharged from a place further than the exhaust gas discharge port 24. The chimney 13 on the downstream side of the flow direction of the purified gas (exhaust gas) is discharged into the atmosphere.

As shown in Figure 2, a mist remover 25 can also be arranged on the downstream side of the flow direction of the purified gas (exhaust gas) than the gas-liquid contact portion 21A. The mist remover 25 is used to remove moisture from the purified gas (exhaust gas). remove.

In the illustrated embodiment, the absorption tower 20A includes a spray device 26 disposed on the gas-liquid contact portion 21A. The spraying device 26 sprays the absorbing liquid (limestone slurry) on the exhaust gas passing through the gas-liquid contact part 21A. The absorbing liquid sprayed from the spraying device 26 contacts the exhaust gas to absorb and remove sulfur oxides (for example, sulfurous acid gas) contained in the exhaust gas.

The spray device 26 includes a spray pipe 261 extending in a direction crossing the flow direction of the exhaust gas, that is, a horizontal direction, and a plurality of spray nozzles 262 provided in the spray pipe 261 . As shown in FIG. 2 , the spray nozzle 262 has a spray port 263 that sprays the absorbing liquid toward the downstream side in the flow direction of the exhaust gas, that is, upward in the vertical direction. In some other embodiments, the spray nozzle 262 may also have a spray port for spraying the absorption liquid downward in the vertical direction.

The exhaust gas introduced into the internal space 21 is sprayed from the spray port 263 of the spray nozzle 262 to absorb and remove the sulfur oxide contained in the exhaust gas, and the absorbing liquid falls and is stored in the storage part 21B. The absorption liquid stored in the storage part 21B may contain sulfite generated from sulfur oxide absorbed from the exhaust gas, and gypsum (calcium sulfate) generated by oxidation of the sulfite.

The absorption tower body 22 is formed with absorption liquid outlets 221 and 222 and a nozzle insertion port 223 . The absorption liquid outlets 221 and 222 are used to take out the absorption liquid stored in the storage part 21B toward the outside; the nozzle insertion port 223 is used to insert the nozzle 271 from the outside of the absorption tower body 22 into the storage part 21B, and the nozzle 271 is It is used to supply an oxidizing gas (for example, air) to the absorption liquid stored in the storage part 21B. The absorption liquid extraction ports 221 and 222 and the nozzle insertion port 223 communicate with the storage part 21B, respectively. Also formed in the absorption tower body 22 is a limestone slurry supply port 224 for introducing limestone slurry. The limestone slurry supply port 224 communicates with the internal space 21 above the storage portion 21B.

The absorption tower 20A includes a gas supply device 27 for supplying an oxidation gas (for example, air) to the absorption liquid stored in the storage part 21B. In the illustrated embodiment, the gas supply device 27 includes: a cylindrical nozzle 271 inserted through the nozzle insertion port 223, a pump 272 for pressurizing and feeding the oxidizing gas to the nozzle 271, and a pump 272 for adjusting the gas flow to the nozzle. The regulating valve 273 of the oxidation gas of 271. Atmospheric air (oxidizing gas) is supplied into the nozzle 271 from one end side of the cylindrical nozzle 271 by the pump 272, and is stored in the storage part 21B from the outlet 274 formed on the other end side of the nozzle 271. The absorption liquid is diffused. Thereby, the sulfite stored in the absorption liquid in the storage part 21B is oxidized to generate gypsum.

The absorption tower 20A includes: a limestone slurry supply line 15 for supplying limestone slurry to the storage part 21B of the absorption tower 20A, and an absorption liquid circulation line 16 for sending the absorption liquid taken out from the storage part 21B to the spraying device 26 . An absorption liquid take-out line 17 for sending the absorption liquid taken out from the storage part 21B to the gypsum separator 30 . The absorption tower 20A circulates the absorption liquid in the absorption liquid circulation system, that is, the spray device 26 , the storage part 21B, and the absorption liquid circulation line 16 . The absorption liquid stored in the storage part 21B is circulated in the circulation system of the absorption liquid while being supplied with limestone as a desulfurization raw material, and is repeatedly used for cleaning the exhaust gas in the absorption tower 20A, so it is gradually accumulated in the storage part 21B. plaster. The amount of supply of this limestone absorbs and neutralizes the sulfur oxides in the exhaust gas introduced into the absorption tower 20A, and adjusts the pH of the absorbing liquid in circulation to a predetermined value.

The gypsum slurry (absorbing liquid containing gypsum) is sent to the gypsum separator 30 through the absorbing liquid take-out line 17, whereby the gypsum is taken out from the above-mentioned circulation system of the absorbing liquid, and the concentration of the gypsum slurry in the storage part 21B becomes constant. (for example, 20~30wt%) to adjust the take-out amount. In order to take into account the absorption and removal of sulfur oxides in the exhaust gas using the absorption liquid (the higher the pH, the better the efficiency), and the oxidation of sulfite in the absorption liquid (the lower the pH, the better the efficiency), the above-mentioned circulation system is used The limestone slurry is suitably supplied through the limestone slurry supply line 15 into the absorption solution so that the pH of the absorption solution is within the range of 5 to 6.

In the illustrated embodiment, the limestone slurry supply line 15 includes: a limestone slurry tank 151 arranged outside the absorption tower 20A for storing limestone slurry, one end side connected to the limestone slurry tank 151 and the other end side The limestone slurry supply pipe 152 connected to the limestone slurry supply port 224 and the valve 153 provided in the limestone slurry supply pipe 152 are. The valve 153 has a movable mechanism for opening and closing the limestone slurry supply pipe 152 , and the amount of limestone slurry supplied to the storage part 21B can be adjusted through the limestone slurry supply pipe 152 . By opening the valve 153, the limestone slurry is sent from the limestone slurry tank 151 to the storage part 21B.

In the illustrated embodiment, the absorption liquid circulation line 16 includes: an absorption liquid circulation pipe 161 connected to the absorption liquid outlet 221 at one end and a spray pipe 261 at the other end; The absorption liquid is sent from one end side of the absorption liquid circulation piping 161 to the circulation pump 162 at the other end side. The absorption liquid extraction line 17 includes: an absorption liquid extraction pipe 171 connected to the absorption liquid extraction port 222 at one end and connected to the gypsum separator 30 at the other end; One end side of the extraction pipe 171 is sent to the extraction pump 172 at the other end side.

The gypsum separator 30 dehydrates the gypsum slurry (absorption liquid containing gypsum) sent from the storage unit 21B through the absorption liquid extraction pipe 171, and separates it into gypsum and filtrate.

(foaming suppression method) The foaming suppressing method 1 of several embodiments is a method for suppressing foaming generated in an absorbing liquid used for desulfurizing the exhaust gas by contacting with the exhaust gas introduced into the absorption tower 20A. The foaming suppressing method 1 generally includes, as shown in FIG. 1 , a parameter value acquisition step S1 , a first antifoaming agent supply amount control step S2 , and a second antifoaming agent supply amount control step S3 .

The parameter value acquisition step S1 is to acquire at least one parameter value P related to the foaming state of the absorbent. Acquisition of the parameter value P is performed continuously. Also, the parameter value P may be acquired every moment, or may be acquired intermittently, for example, every predetermined period or the like.

Fig. 3 is an explanatory diagram for explaining parameter values in an embodiment of the present invention. The parameter value P fluctuates according to the foaming state of the absorbing liquid stored in the storage part 21B, and is adopted: if foaming occurs in the absorbing liquid, compared with the case where foaming does not occur in the absorbing liquid, the parameter value P will fluctuate greatly. . As shown in Figure 3, as the parameter value P, the state value PA of the absorption liquid after contacting with the waste gas, the state value PB of the absorption liquid pump 4 for transporting the absorption liquid after contact with the waste gas, and the state value of the absorption liquid The state value PC of the exhaust gas after contact.

The "absorbing liquid after contact with exhaust gas" includes the absorbing liquid stored in the storage part 21B, and the absorbing liquid existing inside the absorbing liquid circulation pipe 161 and the absorbing liquid extraction pipe 171 . The state value PA of the absorbing liquid after contacting with the exhaust gas includes the oxidation-reduction potential PA1 of the absorbing liquid, the slurry concentration PA2 of the absorbing liquid, the supply flow rate PA3 of the absorbing liquid toward the gypsum separator 30, and the overflow pipe 9 The temperature of PA4 and so on. The absorption liquid pump 4 includes the aforementioned circulation pump 162 and the aforementioned extraction pump 172 . The state value PB of the absorbent pump 4 includes a current value PB1 of the absorbent pump 4 , a discharge pressure PB2 of the absorbent pump 4 , a flow rate PB3 of the absorbent pump 4 , and the like. The state value PC of the exhaust gas includes: the concentration PC1 of sulfur oxides in the exhaust gas, the pressure difference PC2 of the exhaust gas at the inlet and outlet of the absorption tower 20A, and the like.

4 to 7 are explanatory diagrams for explaining changes in parameter values caused by foaming of the absorbing liquid, respectively. 4 to 7, the output of the combustion equipment 11 and the amount of the oxidizing gas supplied to the storage portion 21B by the gas supply device 27 are constant. The horizontal axis in each of FIGS. 4 to 7 is a time axis showing the elapse of time. The time axes in FIGS. 4 to 7 are common, and the period T1 represents the same time. Fig. 4 is an explanatory diagram showing changes in oxidation-reduction potential with the passage of time. Fig. 5 is an explanatory diagram showing changes in the slurry concentration of the absorption liquid and the supply flow rate of the absorption liquid to the gypsum separator over time. Fig. 6 is an explanatory diagram showing changes in the current value of the absorption liquid pump with the lapse of time. FIG. 7 is an explanatory diagram showing changes in the concentration of sulfur oxides in exhaust gas over time.

As shown in Fig. 4, even when an antifoaming agent is supplied to the absorption liquid at regular intervals, foaming still occurs in the absorption liquid after contact with exhaust gas, as in the case where no antifoaming agent is supplied to the absorption liquid. However, when the oxidation-reduction potential PA1 is suddenly increased (largely fluctuated). FIG. 4 shows that the oxidation-reduction potential rises sharply during the period T1. FIG. 5 shows that the value V1 of the slurry concentration PA2 of the absorbing liquid and the supply flow rate PA3 of the absorbing liquid to the gypsum separator 30 drops sharply (largely fluctuates) during the period T1. In addition, FIG. 5 schematically shows the variation ranges X1, X2, and X3 of the supply flow rate PA3. During the period T1, the variation range of the supply flow rate PA3 increases from X1 to X2. FIG. 6 shows that the value V2 of the current value PB1 of the absorption liquid pump 4 drops sharply (changes greatly) during the period T1. In addition, FIG. 6 schematically shows the variation ranges Y1 and Y2 of the current value PB1. During the period T1, the variation range of the current value PB1 increases from Y1 to Y2. Fig. 7, relative to the concentration of sulfur oxides in the exhaust gas at the entrance of the absorption tower 20A (near the exhaust gas inlet 23) during the period T1 does not change, the outlet of the absorption tower 20A (near the exhaust gas outlet 24) during the period T1 The concentration PC1 of sulfur oxides in the exhaust gas rises sharply (changes greatly). Parameter values P other than the parameter values P shown in each of FIGS. 4 to 7 also fluctuate greatly during the period T1.

In the first antifoaming agent supply amount control step S2, as shown in FIG. 1 , it is determined whether or not foaming occurs in the absorbent liquid based on at least the parameter value P obtained in the parameter value obtaining step S1 (first determination step S21), When it is determined that foaming has occurred in the absorbent liquid (YES in S21), the supply of the antifoaming agent to the storage portion 21B is started or the supply amount of the antifoaming agent is increased (the first supply amount adjustment step S22). "Increasing the supply amount of the antifoaming agent toward the storage part 21B" includes: in the absorption tower 20A, which continuously injects a predetermined amount of antifoaming agent every predetermined period, before the first supply amount adjustment step S22, Increase the supply amount of the defoamer per one time, and shorten the supply interval of the defoamer. It also includes: increasing the supply speed of the antifoaming agent toward the storage portion 21B. And when it is judged that there is no foaming in the absorption liquid (S21 is "No"), when the operation of the absorption tower 20A continues (step S41), the parameter value P is re-obtained, and the second step is performed again according to the parameter value P. 1 Judgment The judgment of step S21. The defoamer system of the present invention includes: silicon-based, grease-based, fatty acid-based, mineral oil-based, alcohol-based, amide-based, phosphate ester-based, metal soap-based defoamers.

The parameter value P acquired before the first supply amount adjustment step S22 is called an old parameter value OP, and the parameter value P acquired after the first supply amount adjustment step S22 is called a new parameter value NP. The parameter value obtaining step S1 includes: a step S1A of obtaining an old parameter value OP, and a step S1B of obtaining a new parameter value NP. In the above-mentioned first determination step S21, it is determined based on at least the old parameter value OP whether or not foaming has occurred in the absorbent liquid.

In the second antifoaming agent supply control step S3, as shown in FIG. 1 , it is determined whether or not the foaming of the absorbent has disappeared based on at least the new parameter value NP acquired in the parameter value acquisition step S1 (second determination step S31 ). When it is determined that the foaming of the absorbent has disappeared (YES in S31), the supply amount of the antifoaming agent to the storage portion 21B is decreased (second supply amount adjustment step S32). "Reducing the supply amount of the antifoaming agent toward the storage part 21B" includes: In the absorption tower 20A, which continuously injects a predetermined amount of antifoaming agent every predetermined period, after the first supply amount adjustment step S22 and the second 2. Before the supply amount adjustment step S32, the supply amount of the antifoaming agent is decreased every time, and the supply interval of the antifoaming agent is lengthened. It also includes reducing the supply speed of the antifoaming agent to the storage part 21B and stopping the supply of the antifoaming agent to the storage part 21B.

When it is determined that the foaming of the absorption liquid has not disappeared (S31 is "No"), when the operation of the absorption tower 20A continues (step S42), a new parameter value NP is obtained again, and at least based on the new parameter value NP, the The determination of the second determination step S31 is performed. After the second supply adjustment step S32 is executed, when the absorption tower 20A continues to operate (step S43), the parameter value P is re-acquired, and the first determination step S21 is determined again based on the parameter value P at least.

In the illustrated embodiment, each step of the foam suppression method 1 is performed by a foam suppression system 5 . The foam suppression system 5, as shown in FIG. 2 , generally includes: at least one parameter value acquisition device 50 , an antifoaming agent storage device 6 , an antifoaming agent supply line 7 , and an antifoaming agent supply amount adjusting device 8 . In each step of the foaming suppression method 1, devices and machines other than the devices and machines of the foaming suppression system 5 can also be used, and can also be performed manually.

The at least one parameter value obtaining means 50 is to obtain at least one parameter value P related to the foaming state of the absorbent liquid. At least one parameter value P is obtained by the parameter value obtaining device 50 (parameter value obtaining step S1).

The antifoaming agent storage device 6 (for example, the antifoaming agent storage tank) is used for storing the antifoaming agent. In the illustrated embodiment, the antifoaming agent storage device 6 is arranged outside the absorption tower 20A. The antifoaming agent supply line 7 sends the antifoaming agent from the antifoaming agent storage device 6 to the storage part 21B. In the illustrated embodiment, an antifoaming agent supply port 225 for introducing an antifoaming agent is formed in the absorption tower main body 22 . The antifoaming agent supply port 225 communicates with the internal space 21 above the storage portion 21B. The antifoamer supply line 7 includes an antifoamer supply pipe 71 , one end of the antifoamer supply pipe 71 is connected to the antifoamer storage device 6 , and the other end is connected to the antifoamer supply port 225 .

The antifoaming agent supply amount adjusting device 8 is configured to be able to adjust the amount of the antifoaming agent sent from the antifoaming agent storage device 6 to the storage part 21B through the antifoaming agent supply line 7 . The "adjustment of the amount of the antifoaming agent" includes starting and stopping the supply of the antifoaming agent. The first antifoamer supply amount control step S2 and the second antifoamer supply amount control step S3 are respectively performed by the antifoamer supply amount adjustment device 8 .

In the illustrated embodiment, the antifoaming agent supply adjustment device 8, as shown in Figure 2, includes an antifoaming agent supply adjustment unit 81 and a control device 82 (Figure 8), and the antifoaming agent supply adjustment unit 81 It has an adjustment mechanism for adjusting the amount of the antifoaming agent sent from the antifoaming agent storage device 6 to the storage part 21B; In the embodiment shown in FIG. 2 , the antifoaming agent supply amount adjustment unit 81 is constituted by a valve 81A provided on the antifoaming agent supplying pipe 71 . The valve 81A has a movable mechanism for opening and closing the defoamer supply pipe 71 , and the amount of the defoamer supplied to the reservoir 21B through the defoamer supply pipe 71 can be adjusted by this movable mechanism.

Fig. 8 is a block diagram showing the function of an antifoaming agent supply amount adjusting device according to an embodiment of the present invention. In the illustrated embodiment, the control device 82, as shown in Figure 8, generally includes: a database part 83, a judgment data generation part 84, a first judgment part 85, a second judgment part 86, an indication of the amount of defoamer supply Section 87. The database unit 83 can store the parameter value P obtained by the parameter value obtaining device 50 together with the time series information. The determination data generation unit 84 generates determination data from the information (for example, parameter value P) stored in the database unit 83 . The first judging unit 85 judges whether foaming has occurred in the absorbent liquid based on at least the old parameter value OP (parameter value P) as in the first judging step S21. The second judging unit 86 judges whether or not the foaming of the absorbent has disappeared based on at least the new parameter value NP (parameter value P) as in the second judging step S31. The antifoaming agent supply amount instruction unit 87 instructs the opening degree of the valve 81A according to the determination result of at least one of the first determination unit 85 and the second determination unit 86 . The valve 81A is electrically controlled by a signal sent from the antifoaming agent supply amount instruction unit 87, and the opening degree is set according to the signal.

When it is determined by the first determination unit 85 that foaming has occurred in the absorbent liquid, the antifoaming agent supply amount instruction unit 87 sends an instruction to increase the opening (for example, fully open) to the valve 81A (first supply amount adjustment). Step S22). The opening of the valve 81A is increased according to the instruction of the antifoaming agent supply amount instruction part 87, and the supply of the antifoaming agent to the storage part 21B is started or the supplying amount of the antifoaming agent is increased. When it is determined by the second determination unit 86 that the foaming of the absorbent liquid has disappeared, the antifoaming agent supply amount instruction unit 87 sends an instruction to decrease (for example, fully close) the opening of the valve 81A (the second supply amount Adjustment step S32). The opening of the valve 81A is reduced in accordance with the instruction of the antifoaming agent supply quantity instruction|indication part 87, and the supply quantity of the antifoaming agent to the storage part 21B is reduced. Also at this time, the valve 81A can be fully closed to stop the supply of the antifoaming agent to the storage portion 21B.

The control device 82 is an electronic control unit for controlling the supply amount of the antifoaming agent toward the storage portion 21B, and can be constituted in the form of a microcomputer including a CPU (processor), ROM, and RAM not shown. Storage devices such as memory and external storage devices, I/O interfaces, communication interfaces, etc. Furthermore, for example, the CPU can be operated (for example, data calculation, etc.) according to the command of the program downloaded to the main storage device of the above-mentioned memory, thereby realizing the above-mentioned various parts.

The foaming suppressing method 1 of several embodiments generally includes, as shown in FIG. 1 , the above-mentioned parameter value acquisition step S1, the above-mentioned first antifoaming agent supply amount control step S2, and the above-mentioned second antifoaming agent supply amount control step S3. . According to the method described above, at least one parameter value P related to the foaming state of the absorbent is obtained in the parameter value obtaining step S1. The parameter value P varies according to the state of foaming of the absorbent stored in the storage portion 21B, and the parameter value P varies greatly when foaming occurs in the absorbing liquid compared to the case where foaming does not occur in the absorbing liquid. When the parameter value P fluctuates greatly, since the possibility of foaming in the absorbent stored in the storage part 21B is high, the supply of the antifoaming agent to the storage part 21B is started or the supply amount of the antifoaming agent is increased ( In the first antifoaming agent supply control step S2), the foaming of the absorption liquid can be quickly suppressed. According to the method described above, by using the parameter value P as an estimation index of the foaming state of the absorbent, the foaming state of the absorbent stored in the storage portion 21B can be accurately estimated, and the foaming of the absorbent can be quickly suppressed.

Furthermore, according to the method described above, when the new parameter value NP returns to the value before the large change after the supply of the antifoaming agent to the storage portion 21B is started or the supply amount of the antifoaming agent is increased, it is due to the accumulation of the antifoaming agent in the storage portion. There is a high probability that the foaming of the absorbing liquid in 21B will disappear, and by reducing the supply amount of the defoamer toward the storage portion 21B (second defoamer supply amount control step S3), the subsequent defoamer can be suppressed. Therefore, the reduction of the oxidation performance of the absorption liquid can be suppressed.

The foam suppressing system 5 of several embodiments, as shown in FIG. 2 , is a foam suppressing system for suppressing the generation of foam in the absorbing liquid used for desulfurizing the waste gas that is used to contact the waste gas introduced into the absorption tower 20A. 5. It is equipped with: the above-mentioned at least one parameter value acquisition device 50, the above-mentioned defoamer storage device 6, the above-mentioned defoamer supply line 7, and the above-mentioned defoamer supply adjustment device 8. The antifoaming agent supply amount adjusting device 8 judges whether or not foaming occurs in the absorbent liquid based on at least the parameter value P (old parameter value OP) obtained by the parameter value obtaining device 50, and when it is determined that foaming occurs in the absorbent liquid The supply of the antifoaming agent to the storage part 21B is started or the amount of the antifoaming agent is increased, and at least based on the parameter value P (new parameter value NP) obtained by the parameter value obtaining device 50, it is determined whether the foaming of the absorbent liquid is When it is determined that the foaming of the absorbing liquid has disappeared, the supply amount of the antifoaming agent to the storage portion 21B is reduced.

According to the above configuration, at least one parameter value P related to the foaming state of the absorbent liquid is obtained by the at least one parameter value obtaining device 50 . The parameter value P varies according to the foaming state of the absorbent stored in the storage portion 21B. When the parameter value P fluctuates greatly, since there is a high possibility of foaming in the absorbing liquid stored in the storage part 21B, the antifoaming agent supply amount adjusting device 8 starts the supply of the antifoaming agent toward the storage part 21B or starts the defoaming The supply amount of the agent is increased, whereby the foaming of the absorption liquid can be quickly suppressed. According to the above configuration, by using the parameter value P as an estimation index of the foaming state of the absorbent, the foaming state of the absorbent stored in the storage portion 21B can be accurately estimated, and foaming of the absorbent can be quickly suppressed.

Furthermore, according to the above configuration, after the supply of the antifoaming agent to the storage part 21B is started or the supply amount of the antifoaming agent is increased, when the new parameter value NP returns to the value before the large change, because it is stored in the storage part It is highly probable that the foaming of the absorbing liquid in 21B will disappear, and the antifoaming agent supply amount adjusting device 8 reduces the supplying amount of the antifoaming agent to the storage part 21B, thereby suppressing the excess supply of the antifoaming agent, thereby suppressing absorption. The oxidation performance of the liquid is reduced.

In several embodiments, the above-mentioned at least one parameter value P includes: an oxidation-reduction potential PA1 of the absorption liquid after contacting with the exhaust gas. At least one parameter value acquisition device 50, as shown in FIG. 2, generally includes: an oxidation-reduction potentiometer (ORP meter) 51 for obtaining the oxidation-reduction potential of the absorption liquid after contacting with the exhaust gas. In the illustrated embodiment, an oxidation-reduction potentiometer 51 is provided in the absorption liquid circulation line 16 to measure the oxidation-reduction potential of the absorption liquid flowing through the absorption liquid circulation line 161 .

According to the method described above, as shown in FIG. 4 , when foaming occurs in the absorbing liquid, the oxidation-reduction potential (ORP value) PA1 of the absorbing liquid obtained in the parameter value obtaining step S1 increases sharply. By using the oxidation-reduction potential PA1 of the absorbent as the parameter value P, it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion 21B.

Fig. 9 is an explanatory diagram for explaining an example of judgment in an embodiment of the present invention. L in FIG. 9 is an estimated straight line calculated from the oxidation-reduction potential (ORP value) PA1 obtained by the oxidation-reduction potentiometer 51 .

In several embodiments, the at least one parameter value P includes: the oxidation-reduction potential PA1 of the absorption liquid after contacting with the exhaust gas. As shown in FIG. 9 , the appropriate range R1 of the oxidation-reduction potential PA1 of the absorbing liquid after contact with the exhaust gas is defined in advance by an upper limit UT1 and a lower limit LT1 . The appropriate range R1 (upper limit UT1 , lower limit LT1 ) is set in advance before the first determination step S21 and is stored in the database unit 83 . The antifoaming agent supply adjustment device 8 compares the measured value of the oxidation-reduction potential PA1 obtained by the oxidation-reduction potentiometer 51 with the appropriate range R1, and adjusts the opening of the valve 81A to adjust the antifoaming agent toward the storage part 21B. supply.

If the oxidation-reduction potential PA1 of the absorption liquid is in a peroxidized state exceeding the upper limit value UT1, peroxides may be generated in the absorption liquid. In the first determination step S21 (first determination unit 85), the measured value of the oxidation-reduction potential PA1 obtained by the oxidation-reduction potentiometer 51 is compared with the upper limit value UT1, and when the measured value reaches the upper limit value UT1 (point P1 ) or when the measured value exceeds the upper limit UT1, it is determined that foaming has occurred in the absorbent liquid. The opening degree of the valve 81A is increased to start the supply of the antifoaming agent to the storage portion 21B (first supply amount adjustment step S22 ). According to the above method, the oxidation-reduction potential PA1 of the absorption liquid is kept below the upper limit value UT1, and the generation of peroxides in the absorption liquid can be suppressed. The upper limit UT1 is preferably 100 mV to 600 mV. In a certain embodiment, the upper limit UT1 is 400 mV.

If the oxidation-reduction potential PA1 of the absorption liquid is lower than the lower limit value LT1, because the oxidation performance of the absorption liquid is greatly reduced, the desulfurization performance of the exhaust gas based on the absorption liquid is reduced, and the normal operation of the exhaust gas desulfurization device 20 (absorption tower 20A) must be maintained. There is a concern that operation may become difficult. In the second determination step S31 (the second determination unit 86), the measured value of the oxidation-reduction potential PA1 obtained by the oxidation-reduction potentiometer 51 is compared with the lower limit value LT1, and when the measured value reaches the lower limit value LT1 (point P2 ), or when the measured value is lower than the lower limit LT1, it is determined that the foaming of the absorbent has disappeared. The opening degree of the valve 81A is fully closed, and the supply of the antifoaming agent to the storage part 21B is stopped (second supply amount adjustment step S32). According to the method described above, when the oxidation-reduction potential PA1 of the absorbing liquid falls below the lower limit value LT1, the supply of the antifoaming agent to the storage portion 21B is stopped, thereby suppressing the oxidation performance of the absorbing liquid caused by the excess supply of the antifoaming agent. Therefore, the normal operation of the exhaust gas desulfurization device 20 can be maintained. The lower limit LT1 is preferably 50mV-400mV. In a certain embodiment, the lower limit value LT1 is 50 mV.

The antifoaming agent supply amount adjusting device 8 may also be configured such that when the measured value of the oxidation-reduction potential PA1 obtained by the oxidation-reduction potentiometer 51 becomes a predetermined value greater than the lower limit value LT1 after the second supply amount adjustment step S32 ( For example, when the upper limit value UT1) or exceeds a predetermined value, the supply of the antifoaming agent to the storage portion 21B is started. As a condition for starting the supply of the antifoaming agent to the storage part 21B, it may be added that the sulfurous acid concentration of the absorption liquid measured by the sulfurous acid concentration meter 18 (see FIG. 2 ) is a predetermined concentration or less. In the illustrated embodiment, the sulfurous acid concentration meter 18 is installed in the absorption liquid circulation line 16 to measure the concentration of sulfurous acid in the absorption liquid flowing through the absorption liquid circulation pipe 161 .

In several embodiments, the above-mentioned foaming suppression method 1 further includes a defoamer supply amount adjustment step S5 as shown in FIG. 1 . Before the antifoaming agent supply adjustment step S5, at least one value (intermediate value IV) between the maximum value UV1 and the minimum value UV2 of the parameter value P set according to the type of the parameter value P, and the maximum value UV1 and the minimum value UV2 is specified. , and stored in the database section 83. In the antifoaming agent supply amount adjustment step S5, when the parameter value P becomes the intermediate value IV, the adjustment of the supply amount of the antifoaming agent to the storage part 21B is performed. In the illustrated embodiment, the antifoaming agent supply amount adjusting device 8 is configured to be able to execute the antifoaming agent supply amount adjusting step S5.

In the illustrated embodiment, one of the intermediate values IV is a predetermined upper limit value UT1. In the antifoaming agent supply adjusting device 8, when the measured value of the oxidation-reduction potential PA1 obtained by the oxidation-reduction potentiometer 51 rises to the upper limit value UT1 (intermediate value IV), the measured value is lower than the upper limit value compared with the measured value. In the case of the value UT1, the supply amount of the antifoaming agent to the storage portion 21B is increased. For example, the opening degree of the valve 81A may be increased, or the valve 81A may be opened to increase the frequency of supply of the antifoaming agent.

In the illustrated embodiment, as one of the intermediate values IV, a threshold TH smaller than the upper limit UT1 and larger than the lower limit LT1 is set in advance before the antifoaming agent supply amount adjustment step S5, and is stored in the database. 83. When the measured value of the oxidation-reduction potential PA1 obtained by the redox potentiometer 51 decreases to reach the threshold TH, the supply amount of the antifoaming agent to the storage portion 21B is reduced compared to when the measured value exceeds the threshold TH. For example, the opening degree of the valve 81A may be reduced, or the valve 81A may be opened to reduce the number of times of supplying the antifoaming agent. In a certain embodiment, the threshold TH is 100 mV. Also, a plurality of intermediate values IV may be defined as in the illustrated embodiment, and the supply amount of the antifoaming agent to the storage portion 21B is adjusted every time the measured value becomes one of the plurality of intermediate values IV.

According to the above method, by adjusting the defoamer supply amount adjustment step S5, the defoamer supply amount toward the storage portion 21B is adjusted according to the parameter value P, so that the oversupply and undersupply of the antifoamer can be effectively suppressed.

For the parameter values P other than the oxidation-reduction potential PA1 of the absorbing liquid, the appropriate range (upper limit value, lower limit value) of each parameter value P can be set in advance and stored in the database unit 83 before the first determination step S21. Also, for the parameter values P other than the oxidation-reduction potential PA1 of the absorption liquid, the maximum value, the minimum value, and the intermediate value between the parameter values assumed according to the type of each parameter value P can be used as the defoamer supply amount. It is set in advance and stored in the database unit 83 before the adjustment step S5. The parameter values P other than the oxidation-reduction potential PA1 of the absorption liquid can also increase or decrease the supply amount of the antifoaming agent to the storage part 21B when each parameter value becomes an intermediate value.

Fig. 10 is an explanatory diagram for explaining an example of determination in an embodiment of the present invention. In the above-mentioned several embodiments, although the measured value of the parameter value P is used in the determination of the foaming state of the absorbent (for example, the first determination step S21 and the second determination step S31), it is also possible to use At least any one of the variation range, average value, dispersion, standard deviation, effective value, variation, variation rate, and difference of the parameter value P calculated from the measured value is used as the data for judgment. The determination data generation unit 84 is configured to generate determination data such as the average value of the parameter value P based on the measured value of the parameter value P.

For example, like the embodiment shown in FIG. 10, in the first determination step S21 (first determination unit 85), when the data for determination (in FIG. 10, the variation ΔP of the parameter value P in the predetermined period T2) becomes predetermined When it exceeds the threshold value (point P3), it can be determined that foaming has occurred in the absorbent liquid. Also in the second determination step S31 (second determination unit 86), when the data for determination is equal to or less than a predetermined threshold value, it can be determined that the foaming of the absorbent liquid has disappeared.

Fig. 11 is an explanatory diagram for explaining a method of setting a threshold value according to an embodiment of the present invention. In the above-mentioned several embodiments, the judgment criteria of the appropriate range (upper limit, lower limit) and threshold value of the parameter value P refer to the judgment of the foaming state of the absorbent liquid in the judgment (for example, the first judgment step S21, the second judgment step S31), etc., which are set in advance and stored in the database part 83, but can also be used in the judgment of the foaming state of the absorbing liquid (such as the first judgment step S21, the second judgment step S31) or the like. Before that, let the determination data generating unit 84 generate data (for example, the measured value of the parameter value P) stored in the database unit 83 .

Like the embodiment shown in FIG. 10, the determination data generation unit 84 may also generate an appropriate range R2 ( upper limit UT2, lower limit LT2). The appropriate range R2 generated by the judgment data generation unit 84 can be used as a judgment criterion in the second judgment step S31. In the second determination step S31 (the second determination unit 86 ), when the newly acquired parameter value P falls within the appropriate range R2 (point P4 ), it is determined that the foaming of the absorbent has disappeared. In several other embodiments, the judging data generating unit 84 may also generate an appropriate parameter value P that includes the parameter value P in the stable state before the time point (point P3) when it is judged that foaming occurs in the absorbent liquid. The range R2 (upper limit UT2, lower limit LT2) is used as the judgment criterion in the second judgment step S31.

Like the embodiment shown in FIG. 10 , the determination data generation unit 84 may also generate an assumption that foaming does not occur in the absorbent liquid based on at least the parameter value P (old parameter value OP) obtained in the parameter value obtaining step S1. The predicted value PV of the parameter value of the situation. The predicted value PV generated by the judgment data generation unit 84 can be used as a judgment index for each judgment (for example, the first judgment step S21, the second judgment step S31). In the first determination step S21 (first determination unit 85), when the difference D of the predicted value PV with respect to the parameter value P is equal to or greater than the first predetermined value PD1, it can be determined that foaming has occurred in the absorbent liquid. In the determination step S31 (the second determination unit 86 ), it can be determined that the foaming of the absorbent has disappeared when the difference D between the predicted value PV and the parameter value P is equal to or less than the second predetermined value PD2. Furthermore, as the predicted value PV, a value set in advance can be stored in the database unit 83 .

In other embodiments, in the first determination step S21 (first determination unit 85), when the fluctuation range of the parameter value P (for example, X1~X3 in FIG. 5, Y1, Y2 in FIG. When the predetermined variation range (for example, the predicted variation range of the parameter value assuming that no foaming occurs in the absorbent liquid) is greater than or equal to a predetermined range, it is determined that foaming has occurred in the absorbent liquid, and in the second determination step S31 (the second determination unit 86 ), when the variation range of the parameter value P is below a predetermined variation range (for example, the predicted variation range of the parameter value assuming no foaming occurs in the absorbent liquid), it is determined that the foaming of the absorbent liquid has disappeared. The predetermined fluctuation range may be stored in the database unit 83 as a preset value, or may be generated by the determination data generation unit 84 .

In several embodiments, in the above-mentioned first antifoaming agent supply amount control step S2, the predicted value is based on the parameter value P obtained in the parameter value obtaining step S1 and the parameter value assuming that no foaming occurs in the absorbent liquid. PV, to determine whether there is foaming in the absorption liquid. It is also possible to compare the fluctuation range of the parameter value P with the fluctuation range of the predicted value PV to determine whether foaming occurs in the absorption liquid.

According to the method described above, the parameter value P is changed according to the foaming state of the absorbent stored in the storage part 21B. If foaming occurs in the absorbent, its relative parameter The deviation of the predicted value PV of the value becomes large. In the case where the deviation of the parameter value P obtained in the parameter value obtaining step S1 from the predicted value PV of the parameter value becomes large, there is a high probability that the absorbing liquid stored in the storage part 21B will cause foaming. Starting the supply of the antifoaming agent or increasing the supplying amount of the antifoaming agent (first antifoaming agent supplying amount control step S2 ) can quickly suppress the foaming of the absorbent. According to the method described above, by using the predicted value PV of the parameter value as an estimation index of the foaming state of the absorbent liquid, the foaming state of the absorbent liquid stored in the storage portion 21B can be estimated with good accuracy, and the foaming state of the absorbent liquid can be quickly suppressed. Bubble.

In some embodiments, the second antifoaming agent supply amount control step S3 may be based on the parameter value P obtained in the parameter value obtaining step S1 and the parameter value assuming that no foaming occurs in the absorbent liquid. The predicted value PV. To determine whether the foaming of the absorption liquid disappears. In addition, it may be determined whether or not the foaming of the absorbent has disappeared by comparing the variation range of the parameter value P with the variation range of the predicted value PV.

According to the method described above, when the deviation of the parameter value P obtained in the parameter value obtaining step S1 from the predicted value PV of the parameter value becomes small, there is a high probability that the foaming of the absorbing liquid stored in the storage part 21B will disappear. By reducing the supply amount of the antifoaming agent to the storage part 21B (second antifoaming agent supply amount control step S3), it is possible to quickly suppress the reduction in the oxidation performance of the absorption tower.

Like the embodiment shown in FIG. 11 , the determination data generation unit 84 may be based on at least the parameters acquired before the determination of the foaming state of the absorbent (for example, the first determination step S21, the second determination step S31). The measured value of the value P calculates the frequency distribution related to the predicted value PV of the parameter value P and the deviation of each measured value relative to the predicted value PV, and generates the predicted value PV including the parameter value P according to the frequency distribution (the deviation is 0 ) in the appropriate range R3 (upper limit UT3, lower limit LT3) as a judgment criterion for each judgment (for example, the first judgment step S21, the second judgment step S31). In the first determination step S21 (first determination unit 85), when the parameter value P is outside the appropriate range R3 (the parameter value P is greater than or equal to the upper limit value UT3 or less than or equal to the lower limit value LT3), it is determined that the absorption liquid has occurred. In the second determination step S31 (second determination unit 86), when the parameter value P falls within the appropriate range R3 (the parameter value P is smaller than the upper limit value UT3 and greater than the lower limit value LT3), it is determined that it is an absorbent liquid. The blistering disappeared. For example, in the illustrated embodiment, the appropriate range R3 is set to include 80% of the measured value of the parameter value P.

In several embodiments, for example, as shown in FIG. 10 , the above-mentioned foaming suppression method 1 compares the old parameter value OP with the new parameter value NP in the supply of the antifoaming agent toward the storage part 21B, and calculates according to the difference D1 Adjust the supply amount of the antifoaming agent. The old parameter value OP is determined to be the foaming generation time point (point P3) at which the absorbent liquid has foamed, or the aforementioned absorption liquid before the foaming generation time point (point P3). The parameter value of either one of the time points when no foaming occurred. In the illustrated embodiment, the second determination unit 86 compares the old parameter value OP with the new parameter value NP, and when the difference D1 is smaller than the preset allowable value D0, the antifoaming agent directed toward the storage unit 21B is Supply decreases.

According to the above method, the new parameter value NP is compared with the old parameter value OP, and the defoamer supply is adjusted according to the difference D1, so that the above-mentioned difference D can be reduced, and the parameter value P The state before the major change. In this case, oversupply and undersupply of the antifoaming agent can be effectively suppressed.

In several embodiments, the above-mentioned at least one parameter value P includes the slurry concentration PA2 of the absorption liquid. At least one parameter value obtaining device 50, as shown in FIG. 2 , includes: a slurry concentration meter 52 for obtaining the slurry concentration PA2 of the absorption liquid after contacting with exhaust gas. In the illustrated embodiment, the slurry concentration meter 52 is installed in the absorption liquid circulation line 16 to measure the slurry concentration of the absorption liquid flowing through the absorption liquid circulation pipe 161 . In a certain embodiment, the slurry concentration meter 52 is composed of a differential pressure type slurry concentration meter, and the differential pressure type slurry concentration meter converts the pressure difference of the absorbent generated between two points into the slurry concentration . In this case, as shown in FIG. 5, if the absorption liquid foams, the value of the slurry concentration PA2 of the absorption liquid becomes smaller than that of the case where the absorption liquid does not foam, and the difference between the slurry concentration PA2 and the predicted value The deviation becomes larger. By using the slurry concentration PA2 of the absorbent as the parameter value P, it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion 21B.

The parameter value P (such as the slurry concentration PA2 of the absorption liquid) may vary depending on the operation data of the factory equipped with the absorption tower 20A. For concentration PA2, the operating data of the plant shall be taken into consideration. The operation data of the factory include: the flow rate of the exhaust gas introduced into the inner space 21 of the absorption tower 20A and the concentration of sulfurous acid gas in the exhaust gas, the amount of gypsum slurry sent to the gypsum separator 30 through the absorption liquid extraction line 17, the amount of gypsum slurry passing through the absorption tower At least one of the quantities of limestone slurry supplied by the limestone slurry supply port 224 of the main body 22 . Considering the operation data of the factory, the parameter value P of the case where the absorbent liquid does not foam at each judgment is predicted, and the difference between the predicted value PV and the obtained parameter value P is monitored, so that the storage capacity can be estimated more accurately. The state of foaming of the absorbent in the storage portion 21B.

In several embodiments, the at least one parameter value P includes at least any one of the current value PB1 of the absorption liquid pump 4 and a parameter obtained by numerically analyzing the current value PB1 . This parameter includes the variation range, standard deviation, etc. of the current value PB1 obtained from the measured value. At least one parameter value obtaining device 50, as shown in FIG. 2 , includes at least one of: an ammeter 53A for obtaining the current value of the circulation pump 162 and an ammeter 53B for obtaining the current value of the extraction pump 172 . In this case, as shown in FIG. 6, if the absorption liquid foams, the specific gravity of the absorption liquid becomes lighter, and the load applied to the absorption liquid pump 4 becomes smaller. Therefore, compared with the case where the absorption liquid does not foam, the absorption liquid pump The value of the current value PB1 of 4 becomes smaller, and the fluctuation range of the current value PB1 becomes larger. By using at least one of the current value PB1 of the absorbent pump 4 and a parameter obtained by numerically analyzing the current value PB1 as the parameter value P, the foaming state of the absorbent stored in the storage part 21B can be estimated with good accuracy. .

In several embodiments, the above-mentioned at least one parameter value P includes at least any one of the discharge pressure PB2 of the absorbent pump 4 and the variation range of the discharge pressure PB2. At least one parameter value acquisition device 50, as shown in FIG. 2, includes at least one of a pressure gauge 54A for acquiring the discharge pressure of the circulation pump 162 and a pressure gauge 54B for obtaining the discharge pressure of the extraction pump 172. In the illustrated embodiment, the pressure gauge 54A is installed on the downstream side of the absorption liquid circulation line 16 from the circulation pump 162 . The pressure gauge 54B is provided on the downstream side of the absorption liquid extraction line 17 from the extraction pump 172 . In this case, if the absorption liquid foams, compared with the case where the absorption liquid does not foam, as the value of the current value PB1 of the absorption liquid pump 4 becomes smaller and the fluctuation range of the current value PB1 becomes larger, the absorption liquid pump 4 The value of the discharge pressure PB2 becomes smaller, and the fluctuation range of the discharge pressure PB2 becomes larger. By using at least one of the discharge pressure PB2 of the absorbent pump 4 and the variation range of the discharge pressure PB2 as the parameter value P, the foaming state of the absorbent stored in the storage portion 21B can be accurately estimated.

In several embodiments, the above-mentioned at least one parameter value P includes at least any one of the flow rate PB3 of the absorption liquid pump 4 and the variation range of the flow rate PB3 . At least one parameter value obtaining device 50, as shown in FIG. 2 , includes: at least one of a flow meter 55A for obtaining the flow rate of the circulation pump 162 and a flow meter 55B for obtaining the flow rate of the extraction pump 172 . In the illustrated embodiment, the flow meter 55A is installed on the downstream side of the absorption liquid circulation line 16 from the circulation pump 162 . The flow meter 55B is provided on the downstream side of the absorption liquid extraction line 17 from the extraction pump 172 . In this case, if the absorption liquid foams, compared with the case where the absorption liquid does not foam, as the value of the current value PB1 of the absorption liquid pump 4 becomes smaller and the fluctuation range of the current value PB1 becomes larger, the absorption liquid pump 4 The value of the flow rate PB3 becomes smaller, and the fluctuation range of the flow rate PB3 becomes larger. By using at least one of the flow rate PB3 of the absorbent pump 4 and the variation range of the flow rate PB3 of the absorbent pump 4 as the parameter value P, the foaming state of the absorbent stored in the storage portion 21B can be accurately estimated.

In several embodiments, the above-mentioned at least one parameter value P includes: the supply of the absorbing liquid flowing in the pipe (absorbing liquid take-out pipe 171 ) that supplies the absorbing liquid from the storage part 21B to the gypsum separator 30 toward the gypsum separator 30 At least one of the flow rate PA3 and the variation range of the supply flow rate (PA3). At least one parameter value acquisition device 50 includes, as shown in FIG. 2 , a flow meter 56 for acquiring the supply flow rate of the absorption liquid flowing through the absorption liquid extraction pipe 171 toward the gypsum separator 30 . The flow meter 56 is provided on the downstream side of the absorption liquid circulation line 16 from the circulation pump 162 . In this case, by driving the absorption liquid pump 4 (specifically, the extraction pump 172 ), the absorption liquid is supplied to the gypsum separator 30 from the storage part 21B through the pipe 171 . According to the method described above, if the absorption liquid foams, the value of the current value PB1 of the absorption liquid pump 4 (extraction pump 172) becomes smaller and the fluctuation range of the current value (PB1) is smaller than that of the absorption liquid without foaming. As the value increases, the value of the supply flow rate PA3 of the absorption liquid flowing through the pipe 171 toward the gypsum separator 30 becomes smaller, and the fluctuation range of the supply flow rate PA3 becomes larger. By using at least one of the supply flow rate PA3 and the variation range of the supply flow rate PA3 as the parameter value P, the foaming state of the absorbent stored in the storage portion 21B can be accurately estimated.

In several embodiments, the above-mentioned at least one parameter value P includes at least any of: the concentration PC1 of sulfur oxides in the exhaust gas after contacting with the absorption liquid, and the deviation between the concentration PC1 of sulfur oxides in the exhaust gas and the expected parameter party. At least one parameter value obtaining device 50, as shown in FIG. ₂ , includes: a sulfur oxide concentration meter 57 (such as an SO2 concentration meter) for obtaining the concentration PC1 of sulfur oxides in the exhaust gas after contacting with the absorbing liquid. In the illustrated embodiment, the sulfur oxide concentration meter 57 is installed on the exhaust gas discharge line 14 . In this case, if the absorbing liquid foams, the bubble content of the absorbing liquid increases, and the amount of the absorbing liquid in contact with the exhaust gas decreases, so the desulfurization performance of the exhaust gas in the absorption tower 20A decreases. Therefore, as shown in FIG. 7 , when the absorbing liquid is foamed, the concentration PC1 of sulfur oxides in the exhaust gas deviates from the predicted value PV more than when the absorbing liquid does not foam. By using at least one of the concentration PC1 of sulfur oxides in the exhaust gas and the deviation between the concentration PC1 of sulfur oxides in the exhaust gas and the expected parameter as the above-mentioned parameter value P, it is possible to accurately estimate the amount of sulfur oxides stored in the storage part 21B. The foaming state of the absorbent liquid.

In several embodiments, the above-mentioned at least one parameter value P includes: at least one of the pressure difference PC2 between the pressure of the waste gas at the inlet of the absorption tower 20A and the pressure of the waste gas at the outlet of the absorption tower 20A, and the deviation between the pressure difference PC2 and the expected parameter. either side. At least one parameter value obtaining device 50, as shown in Figure 2, is to include: obtain the manometer 58A of the exhaust gas pressure of the inlet of absorption tower 20A, obtain the pressure gauge 58B of the exhaust gas pressure of the outlet of absorption tower 20A. In the illustrated embodiment, the pressure gauge 58A is installed near the exhaust gas inlet 23 on the exhaust gas supply line 12 , and the pressure gauge 58B is installed near the exhaust gas discharge port 24 on the exhaust gas discharge line 14 . The determination data generation unit 84 calculates the pressure difference PC2 based on the inlet pressure obtained by the pressure gauge 58A and the outlet pressure obtained by the pressure gauge 58B. In this case, if the absorption liquid foams, the circulating flow rate of the absorption liquid will fluctuate and the liquid level of the absorption liquid in the storage part 21B will become unstable. Compared with the case where the absorption liquid is not foamed, the pressure difference PC2 The fluctuation range becomes larger, and the deviation of the pressure difference PC2 from the predicted value PV becomes larger. By using at least one of the pressure difference PC2 of the exhaust gas at the inlet and outlet of the absorption tower 20A and the deviation between the pressure difference PC2 and the expected parameter as the above-mentioned parameter value P, the absorption liquid stored in the storage part 21B can be estimated with good accuracy. bubbly state.

In several embodiments, the above-mentioned at least one parameter value P includes the temperature PA4 of the overflow pipe 9 connected to the storage part 21B. The overflow pipe 9 is configured to let the absorbent flow out from the storage part 21B when the liquid level of the absorbent in the storage part 21B exceeds a predetermined liquid level. The absorption liquid flowing in from one end side of the overflow pipe 9 is discharged from the other end side of the overflow pipe 9, and is stored in the absorption liquid tank 91 for storing the absorption liquid. At least one parameter value obtaining device 50, as shown in FIG. 2 , includes: a thermometer 59 for obtaining the temperature PA4 of the overflow pipe 9 . In the illustrated embodiment, the thermometer 59 measures the temperature of the outer surface of the overflow pipe 9 protruding to the outside of the absorption tower 20A. In this case, the measurement of the temperature PA4 of the overflow pipe 9 can be performed easily.

According to the above-mentioned method, when the absorption liquid generates bubbles, the liquid level of the absorption liquid in the storage portion 21B rises, and the absorption liquid flows through the overflow pipe 9 . Therefore, when the absorption liquid foams, the temperature PA4 of the overflow pipe 9 rises compared to the case where the absorption liquid does not foam. By using the temperature PA4 of the overflow pipe 9 as the parameter value P, it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion 21B.

In some embodiments, in the parameter value acquiring step S1, a plurality of parameter values P (see FIG. 3 ) having different types of parameter values P may be acquired. Here, the different types of the parameter value P mean that, for example, the signs attached to the respective parameter values are different, such as the oxidation-reduction potential PA1 of the absorption liquid and the slurry concentration PA2 shown in FIG. 3 . In the above-mentioned first antifoaming agent supply amount control step S2, based on at least two parameter values P among the plurality of parameter values P obtained in the parameter value obtaining step S1, it is determined that foaming has occurred in the absorbent liquid, and the direction The supply of the antifoaming agent in the storage part 21B is started or the supply amount of the antifoaming agent is increased. In addition, in the above-mentioned second antifoaming agent supply amount control step S3, if it is determined that the foaming of the absorbent liquid has disappeared based on at least two parameter values P among the plurality of parameter values P obtained in the parameter value obtaining step S1, let The supply amount of the antifoaming agent toward the storage portion 21B decreases.

According to the method described above, a plurality of parameter values P of different types of parameter values P are obtained in the parameter value obtaining step S1. When at least two parameter values P among the plurality of parameter values P fluctuate greatly, compared with the case where one parameter value P fluctuates greatly, the absorbing liquid stored in the storage part 21B has a high probability of foaming. Starting the supply of the antifoaming agent in the part 21B or increasing the supplying amount of the antifoaming agent (first antifoaming agent supplying amount control step S2 ) can quickly and surely suppress the foaming of the absorbent. According to the method described above, by using a plurality of parameter values P with different types of parameter values P as an estimation index of the foaming state of the absorbent, it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion 21B, and it is possible to Quickly and surely suppress foaming of absorbent liquid.

In some embodiments, a plurality of parameter values P of different types of parameter values P are acquired in the parameter value acquisition step S1 (see FIG. 3 ). In the above-mentioned first antifoaming agent supply amount control step S2, based on at least two parameter values P among the plurality of parameter values P obtained in the parameter value obtaining step S1, it is determined that foaming has occurred in the absorbent liquid, and the direction The supply of the antifoaming agent in the storage part 21B is started or the supply amount of the antifoaming agent is increased. At least two parameter values P comprise the oxidation-reduction potential PA1 of the absorption liquid after contact with the exhaust gas.

When foaming occurs in the absorption liquid, the value of the oxidation-reduction potential PA1 of the absorption liquid obtained in the parameter value obtaining step S1 increases rapidly. Therefore, the oxidation-reduction potential PA1 of the absorbent is excellent as an index for estimating the foaming state of the absorbent. According to the method described above, by setting one of the at least two parameter values P as the oxidation-reduction potential PA1 of the absorbing liquid, it is possible to accurately estimate the foaming state of the absorbing liquid stored in the storage portion 21B, and to quickly and reliably suppress the foaming state of the absorbing liquid. Foaming of absorbent fluid. Since the oxidation-reduction potential PA1 of this absorbing liquid fluctuates according to the supply amount of the oxidizing gas supplied from the nozzle 271 to the storage portion 21B, a parameter value P (Fig. The parameter value P) other than the redox potential PA1 in 3 is used as an estimation index of the foaming state of the absorbent, and the foaming state of the absorbent stored in the storage portion 21B can be accurately estimated.

In some embodiments, the opening degree of the adjustment valve 273 may not be changed when determining the bubbling state of the absorbent (for example, the first determination step S21 and the second determination step S31). In this case, fluctuations in the oxidation-reduction potential PA1 of the absorption liquid due to fluctuations in the supply amount of the oxidizing gas can be suppressed, thereby improving the estimation accuracy of the foaming state of the absorption liquid based on the oxidation-reduction potential PA1 of the absorption liquid.

In several embodiments, in the above-mentioned parameter value acquisition step S1, a plurality of parameter values P different in the classification of the parameter value P (state value PA of the absorption liquid, state value PB of the absorption liquid pump, state value PC of the exhaust gas) are obtained. (Refer to Figure 3). In the above-mentioned first antifoaming agent supply amount control step S2, based on at least two parameter values P among the plurality of parameter values P obtained in the parameter value obtaining step S1, it is determined that foaming has occurred in the absorbent liquid, and the direction The supply of the antifoaming agent in the storage part 21B is started or the supply amount of the antifoaming agent is increased.

According to the method described above, by using a plurality of parameter values P with different classifications of parameter values P as an estimation index of the foaming state of the absorbent liquid, the foaming state of the absorbent liquid stored in the storage portion 21B can be estimated from various aspects, Therefore, it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion 21B.

The present invention is not limited to the above-mentioned embodiments, but also includes modifications to the above-mentioned embodiments and forms in which these are appropriately combined.

The contents described in the above-mentioned several embodiments can be grasped as follows, for example.

1) The foaming suppressing method (1) of at least one embodiment of the present invention is to suppress the foaming of the absorbing liquid used for desulfurization of the exhaust gas for contacting with the exhaust gas introduced into the absorption tower (20A) A suppression method comprising: a parameter value obtaining step (S1), a first defoamer supply control step (S2), and a second defoamer supply control step (S3); The aforementioned parameter value acquisition step (S1) is to acquire at least one parameter value (P) related to the foaming state of the aforementioned absorption liquid; The first antifoaming agent supply amount control step (S2) is to determine whether or not foaming has occurred in the absorbent liquid based on at least the parameter value (P) obtained in the parameter value obtaining step (S1). When foaming occurs in the absorption liquid, the supply of the defoaming agent to the storage part (21B) is started or the supply amount of the defoaming agent is increased. liquid; The aforementioned second antifoaming agent supply amount control step (S3) is at least based on the aforementioned parameter value (P) newly obtained after the aforementioned first antifoaming agent supply amount control step (S2), that is, a new parameter value (NP), It is judged whether the foaming of the absorbent liquid has disappeared, and when it is judged that the foaming of the absorbent liquid has disappeared, the supply amount of the antifoaming agent to the storage part (21B) is reduced.

According to the method of 1) above, at least one parameter value (P) related to the foaming state of the absorbent is obtained in the parameter value obtaining step (S1). The parameter value (P) varies according to the foaming state of the absorbent liquid stored in the storage part (21B). If foaming occurs in the absorbent liquid, the parameter value (P ) will vary greatly. When the parameter value (P) fluctuates greatly, since there is a high possibility of foaming in the absorption liquid stored in the storage part (21B), by starting the supply of the antifoaming agent toward the storage part (21B) or defoaming By increasing the supply amount of the antifoaming agent (the first antifoaming agent supply amount control step S2), the foaming of the absorption liquid can be quickly suppressed. According to the method of 1) above, by using the parameter value (P) as an estimation index of the foaming state of the absorbing liquid, the foaming state of the absorbing liquid stored in the storage part (21B) can be accurately estimated, and the foaming state of the absorbing liquid can be quickly suppressed. Foaming of absorbent fluid.

In addition, according to the method of 1) above, after starting the supply of the antifoaming agent to the storage part (21B) or increasing the supply amount of the antifoaming agent, when the new parameter value (NP) returns to the value before the large change In this case, since the foaming of the absorbing liquid stored in the storage part (21B) is highly likely to disappear, by reducing the supply amount of the antifoaming agent toward the storage part (21B) (the second antifoaming agent supply amount control step S3), since the excessive supply of the antifoaming agent after that can be suppressed, the reduction in the oxidation performance of the absorbent can be suppressed.

2) In some embodiments, in the foaming suppression method (1) described in the above 1), In the first antifoaming agent supply control step (S2), the parameter value (P) obtained in the parameter value obtaining step (S1) and the parameter value are estimated based on the assumption that the absorption liquid does not foam Value (PV) to determine whether foaming occurs in the aforementioned absorption liquid.

According to the method of 2) above, the parameter value (P) changes according to the foaming state of the absorbing liquid stored in the storage part (21B). In this case, the deviation of the predicted value (PV) from the parameter value becomes large. When the parameter value (P) obtained in the parameter value obtaining step (S1) deviates greatly from the predicted value (PV) of the parameter value, there is a possibility that foaming occurs in the absorbent stored in the storage part (21B). High, by starting the supply of the antifoaming agent to the storage part (21B) or increasing the supply amount of the antifoaming agent (first antifoaming agent supply amount control step S2), the foaming of the absorbent can be quickly suppressed. According to the method of 2) above, by using the predicted value (PV) of the parameter value as the judgment index of the foaming state of the absorbent, the foaming state of the absorbent liquid stored in the storage part (21B) can be estimated with good accuracy, and the Rapidly suppresses foaming of absorbent liquids.

3) In several embodiments, the method for suppressing foaming (1) described in the above 1) or 2) further includes an antifoaming agent supply amount adjustment step (S5), which is to specify the assumed aforementioned parameter value ( At least one value between the maximum value (UV1) and the minimum value (LV2) of P) is used as an intermediate value (IV), and when the aforementioned parameter value (P) becomes the aforementioned intermediate value (IV), the adjustment is directed toward the aforementioned storage portion (21B) The supply amount of the aforementioned defoamer.

According to the method of 3) above, the defoamer supply amount adjustment step (S5) adjusts the defoamer supply amount toward the storage part (21B) according to the parameter value (P), so that the defoamer can be effectively suppressed. excess supply and insufficient supply.

4) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 3), The aforementioned at least one parameter value (P) includes: the state value (PA) of the aforementioned absorbing liquid after contacting the aforementioned exhaust gas, that is, the oxidation-reduction potential (PA1) of the aforementioned absorbing liquid.

According to the method of 4) above, if the absorption liquid foams, the value of the oxidation-reduction potential (PA1) of the absorption liquid obtained in the parameter value obtaining step (S1) will increase sharply. By using the oxidation-reduction potential (PA1) of the absorbent as the parameter value (P), it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion.

5) In several embodiments, in the foaming suppression method (1) described in the above 4), The appropriate range (R1) of the oxidation-reduction potential (PA1) of the aforementioned absorbing liquid is specified in advance by an upper limit (UT1) and a lower limit (LT1), and the antifoaming agent toward the aforementioned storage portion (21B) During supply, when the oxidation-reduction potential (PA1) of the absorbing liquid reaches the lower limit value (LT1) or falls below the lower limit value (LT1), the amount of the antifoaming agent directed toward the storage part (21B) Supply stopped.

If the oxidation-reduction potential of the absorbing liquid is lower than the lower limit value, since the oxidation performance of the absorbing liquid is greatly reduced, the desulfurization performance of the exhaust gas due to the absorbing liquid is reduced, and it may become difficult to maintain the normal operation of the exhaust gas desulfurization device. According to the method of 5) above, when the oxidation-reduction potential of the absorption liquid becomes below the lower limit value, by stopping the supply of the antifoaming agent to the storage part, the oxidation of the absorption liquid caused by the excess supply of the antifoaming agent can be suppressed. The performance is reduced, so the normal operation of the flue gas desulfurization unit can be maintained.

6) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 5), In the supply of the antifoaming agent toward the aforementioned storage part (21B), the old parameter value (OP) is compared with the aforementioned new parameter value (NP), and the supply amount of the antifoaming agent is adjusted according to the difference (D1). The parameter value (OP) is the value of the aforementioned parameter at any one of the time point at which foaming is judged to have occurred in the absorbent liquid, or the time point at which foaming has not occurred in the absorbent liquid before the time point at which foaming has occurred .

According to the above 6) method, compare the new parameter value (NP) with the old parameter value (OP), and adjust the defoamer supply according to the difference, so that the above difference can be reduced, and foaming will occur close to the absorption liquid However, the state before the parameter value (P) is greatly changed. In this case, oversupply and undersupply of the antifoaming agent can be effectively suppressed.

7) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 6), The aforementioned at least one parameter value (P) includes: the state value (PA) of the aforementioned absorbing liquid after contacting the aforementioned waste gas, that is, the slurry concentration (PA2) of the aforementioned absorbing liquid.

According to the method of 7) above, if the absorption liquid produces foaming, the value of the slurry concentration (PA2) of the absorption liquid becomes smaller than that of the absorption liquid without foaming, and the difference between the slurry concentration (PA2) and the predicted value The deviation becomes larger. By adopting the slurry concentration (PA2) of the absorbent as the parameter value (P), it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion.

8) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 7), The aforementioned at least one parameter value (P) includes: the state value (PB) of the absorption liquid pump (4) used to transport the aforementioned absorption liquid, that is, the current value (PB1) and the current value (PB1) of the aforementioned absorption liquid pump (4) PB1) At least one of the parameters obtained by numerical analysis.

According to the above method 8), if the absorption liquid foams, because the specific gravity of the absorption liquid becomes lighter, the load applied to the absorption liquid pump becomes smaller. Compared with the case where the absorption liquid does not foam, the current value of the absorption liquid pump ( The value of PB1) becomes smaller, and the fluctuation range of the current value (PB1) becomes larger. By using at least one of the current value (PB1) of the absorption liquid pump and the parameter obtained by numerical analysis of the current value (PB1) as the above-mentioned parameter value (P), the amount stored in the storage part can be estimated with good accuracy. The foaming state of the absorbent liquid.

9) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 8), The aforementioned at least one parameter value (P) includes: the state value (PB) of the absorption liquid pump (4) used to transport the aforementioned absorption liquid, that is, the discharge pressure (PB2) of the aforementioned absorption liquid pump (4) and the discharge pressure ( At least one of the variation ranges of PB2).

According to the method of 9) above, if the absorption liquid foams, compared with the case where the absorption liquid does not foam, the value of the current value (PB1) of the absorption liquid pump becomes smaller and the fluctuation range of the current value (PB1) becomes smaller. Larger, the value of the discharge pressure (PB2) of the absorbent pump becomes smaller, and the fluctuation range of the discharge pressure (PB2) becomes larger. By using at least one of the discharge pressure (PB2) and the variation range of the discharge pressure (PB2) of the absorbent pump as the above-mentioned parameter value (P), it is possible to accurately estimate the foaming state of the absorbent stored in the storage part. .

10) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 9), The aforementioned at least one parameter value (P) includes: the state value (PB) of the absorption liquid pump (4) used to transport the aforementioned absorption liquid, that is, the flow rate (PB3) of the aforementioned absorption liquid pump (4) and the aforementioned flow rate (PB3) At least one of the ranges of change.

According to the method of 10) above, if the absorption liquid foams, compared with the case where the absorption liquid does not foam, as the value of the current value (PB1) of the absorption liquid pump becomes smaller and the fluctuation range of the current value (PB1) becomes smaller Larger, the value of the flow rate (PB3) of the absorption liquid pump becomes smaller, and the fluctuation range of the flow rate (PB3) becomes larger. By using at least one of the flow rate (PB3) of the absorption liquid pump and the fluctuation range of the flow rate (PB3) of the absorption liquid pump as the above-mentioned parameter value (P), the starting point of the absorption liquid stored in the storage part can be estimated with good accuracy. bubble state.

11) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 10), The aforementioned at least one parameter value (P) includes: a state value ( PA), that is, at least one of the supply flow rate (PA3) of the absorption liquid toward the gypsum separator (30) and the variation range of the supply flow rate (PA3).

By driving the absorption liquid pump (specifically, the take-out pump), the absorption liquid is supplied to the gypsum separator by flowing the absorption liquid from the storage part through the above-mentioned piping. According to the method of 11) above, if the absorption liquid foams, compared with the case where the absorption liquid does not foam, as the value of the current value (PB1) of the absorption liquid pump (extraction pump) becomes smaller and the current value (PB1) The range of fluctuation becomes larger, the value of the supply flow rate (PA3) of the absorption liquid flowing in the above-mentioned pipe toward the gypsum separator becomes smaller, and the range of fluctuation of the supply flow rate (PA3) becomes larger. By using at least one of the supply flow rate (PA3) and the variation range of the supply flow rate (PA3) as the parameter value (P), the foaming state of the absorbent stored in the storage portion can be accurately estimated.

12) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 11), The aforementioned at least one parameter value (P) includes: the state value (PC) of the aforementioned exhaust gas after contacting the aforementioned absorption liquid, that is, the concentration of sulfur oxides in the aforementioned exhaust gas after contacting the aforementioned absorption liquid (PC1) and the aforementioned exhaust gas At least one of the deviations between the concentration of sulfur oxides (PC1) and the expected parameters.

According to the method of 12) above, if the absorption liquid foams, since the bubble content rate of the absorption liquid increases, the amount of the absorption liquid in contact with the exhaust gas decreases, and the desulfurization performance of the exhaust gas in the absorption tower decreases. Therefore, when the absorbing liquid is foamed, the concentration of sulfur oxides in the exhaust gas (PC1) deviates more from the predicted value than when the absorbing liquid does not foam. By using at least one of the concentration of sulfur oxides in the exhaust gas (PC1) and the deviation between the concentration of sulfur oxides in the exhaust gas (PC1) and the expected parameter as the above-mentioned parameter value (P), the storage can be estimated with good accuracy. The foaming state of the absorbent in the reservoir.

13) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 12), Aforesaid at least one parameter value (P) system comprises: the state value (PC) of the aforementioned exhaust gas after contacting with the aforementioned absorption liquid, i.e. the pressure of the aforementioned exhaust gas at the inlet of the aforementioned absorption tower (20A) and the aforementioned exhaust gas at the outlet of the aforementioned absorption tower At least one of the pressure difference (PC2) of the pressure and the deviation of the aforementioned pressure difference (PC2) from the expected parameters.

According to the method of 13) above, if the absorption liquid foams, the liquid level in the absorption tower of the storage part (21B) becomes unstable because the circulation flow rate of the absorption liquid fluctuates. Compared with the case where the absorption liquid does not foam , the fluctuation range of the pressure difference (PC2) becomes larger, and the deviation of the pressure difference (PC2) from the predicted value becomes larger. By using at least one of the pressure difference (PC2) of the exhaust gas at the inlet and outlet of the absorption tower, and the deviation between the pressure difference (PC2) and the expected parameter as the above-mentioned parameter value (P), the storage in the storage can be estimated with good accuracy. The foaming state of the absorption liquid in the part.

14) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 13), The aforementioned at least one parameter value (P) includes: the state value (PA) of the aforementioned absorbing liquid after contacting the aforementioned waste gas, that is, the temperature (PA4) of the overflow pipe (9) connected to the aforementioned storage part (21B).

According to the method of 14) above, when the absorbing liquid bubbles, the liquid level of the absorbing liquid in the storage portion rises, and the absorbing liquid flows through the overflow pipe. Therefore, when the absorption liquid foams, the temperature of the overflow pipe rises compared to the case where the absorption liquid does not foam. By using the temperature (PA4) of the overflow pipe as the parameter value (P), it is possible to accurately estimate the foaming state of the absorbent stored in the storage part.

15) In several embodiments, in the foaming suppression method (1) described in any one of the above-mentioned 1) to 14), In the aforementioned parameter value acquisition step (S1), a plurality of parameter values (P) of different types of the aforementioned parameter values (P) are acquired, In the first antifoaming agent supply control step (S2), at least two parameter values (P) among the plurality of parameter values (P) obtained in the parameter value obtaining step (S1) are determined to be in the absorption When foaming occurs in the liquid, the supply of the antifoaming agent to the storage part (21B) is started or the supply amount of the antifoaming agent is increased.

According to the method of 15) above, a plurality of parameter values (P) of different types of parameter values (P) are obtained in the parameter value obtaining step (S1). When at least two parameter values (P) among the plurality of parameter values (P) fluctuate greatly, compared with the case where one parameter value (P) fluctuates greatly, the possibility of foaming due to the absorption liquid stored in the storage part is high. By starting the supply of the antifoaming agent to the storage portion or increasing the supply amount of the antifoaming agent (first antifoaming agent supply amount control step S2), foaming of the absorbent can be suppressed quickly and surely. According to the method of 15) above, by using a plurality of parameter values (P) with different types of parameter values (P) as an estimation index of the foaming state of the absorbent liquid, it is possible to accurately estimate the amount of the absorbent liquid stored in the storage part. foaming state, and can quickly and surely suppress the foaming of the absorbent liquid.

16) In several embodiments, in the foaming suppression method (1) described in the above 15), The aforementioned at least two parameter values (P) include: the state value (PA) of the aforementioned absorbing liquid after contacting the aforementioned exhaust gas, that is, the oxidation-reduction potential (PA1) of the aforementioned absorbing liquid.

When foaming occurs in the absorption liquid, the value of the oxidation-reduction potential (PA1) of the absorption liquid obtained in the parameter value obtaining step (S1) increases sharply. Therefore, the oxidation-reduction potential (PA1) of the absorbent is excellent as an index for estimating the foaming state of the absorbent. According to the method of 16) above, by setting one of the at least two parameter values (P) as the oxidation-reduction potential (PA1) of the absorption liquid, it is possible to accurately estimate the foaming state of the absorption liquid stored in the storage part. , and in turn, it is possible to quickly and surely suppress the foaming of the absorbent.

17) The foam suppression system (5) of at least one embodiment of the present invention is for suppressing the foaming of the absorbing liquid used for desulfurization of the exhaust gas for contacting with the exhaust gas introduced into the absorption tower (20A) Suppression system (5), which is equipped with: at least one parameter value acquisition device (50), defoamer storage device (6), defoamer supply pipeline (7), and defoamer supply adjustment device (8), The aforementioned at least one parameter value acquisition device (50) is to acquire at least one parameter value (P) related to the foaming state of the aforementioned absorption liquid; Aforesaid defoamer storage device (6) is to store defoamer; The aforementioned defoamer supply line (7) is to send the aforementioned defoamer from the aforementioned defoamer storage device (6) to the storage part (21B), and the aforementioned storage part (21B) is to store the aforementioned absorption after contacting the aforementioned exhaust gas. liquid; The aforementioned antifoaming agent supply adjustment device (8) can adjust the amount of the aforementioned antifoaming agent sent from the aforementioned antifoaming agent storage device (7) to the aforementioned storage part (21B) through the aforementioned antifoaming agent supply line (7) ; The above-mentioned antifoaming agent supply amount adjusting device (8) is constituted as follows: It is determined at least based on the parameter value (P) obtained by the at least one parameter value obtaining device (50) whether foaming has occurred in the absorbent liquid, and when it is determined that foaming has occurred in the absorbent liquid, the (21B) The supply of the aforementioned antifoaming agent is started or the supply amount of the aforementioned antifoaming agent is increased, And at least according to the aforementioned parameter value (P) obtained after it is determined that the aforementioned absorbent liquid has foamed, that is, the new parameter value (NP) to determine whether the aforementioned foaming of the aforementioned absorbent liquid has disappeared. When the foaming disappears, the supply amount of the antifoaming agent to the storage part (21B) is reduced.

According to the configuration of 17) above, at least one parameter value (P) related to the foaming state of the absorbent is obtained by the at least one parameter value obtaining means. The parameter value (P) fluctuates according to the state of foaming of the absorbent stored in the storage part. When the parameter value (P) fluctuates greatly, since there is a high probability that foaming will occur in the absorption liquid stored in the storage part, the defoamer supply amount adjustment device will start the supply of the defoamer toward the storage part, or let the defoamer The supply amount of the foaming agent is increased, whereby the foaming of the absorption liquid can be rapidly suppressed. According to the configuration of 15) above, by using the parameter value (P) as an estimation index of the foaming state of the absorbent, it is possible to accurately estimate the foaming state of the absorbent stored in the storage portion, and rapidly suppress the foaming state of the absorbent. bubbly.

Also, according to the configuration of 17) above, when the new parameter value (NP) returns to the value before the large change after starting the supply of the antifoaming agent to the storage part or increasing the supply amount of the antifoaming agent, because There is a high probability that the foaming of the absorbent liquid stored in the storage part will disappear, and the antifoaming agent supply amount adjustment device can reduce the supply amount of the antifoaming agent toward the storage part, thereby suppressing the excessive supply of the antifoaming agent. The oxidation performance of the absorption liquid is reduced.

1: Foaming suppression method 4: Absorption liquid pump 5: Foam suppression system 50: parameter value acquisition device 51: redox potentiometer 52: slurry concentration meter 53A, 53B: ammeter 54A, 54B, 58A, 58B: pressure gauge 55A, 55B, 56: flow meter 57: Sulfur oxide concentration meter 59: Thermometer 6: Defoamer storage device 7: Defoamer supply line 71: Defoamer supply piping 8: Defoamer supply adjustment device 81: Defoamer Supply Volume Adjustment Department 81A: valve 82: Control device 83: Database Department 84: Judgment data generation department 85: The first judgment department 86: The second judgment department 87: Defoamer supply volume indicator 9: overflow pipe 91: Absorption tank 10: Flue gas desulfurization system 11: Combustion equipment 12: Exhaust gas supply pipeline 13: chimney 14: Exhaust gas discharge pipeline 15: Limestone slurry supply pipeline 151: limestone slurry tank 152: Limestone slurry supply piping 153: valve 16: Absorption liquid circulation pipeline 161: Absorption liquid circulation piping 162:Circulation pump 17: Absorption liquid take-out pipeline 171: Pipe for taking out the absorption liquid 172: Take out the pump 18: Sulfurous acid concentration meter 20: Flue gas desulfurization device 20A: Absorption tower 21: Internal space 21A: gas-liquid contact part 21B: storage department 22: Absorption tower body 221,222: Absorbing liquid outlet 223: Nozzle insertion port 224: Limestone slurry supply port 225: Defoamer supply port 23: Exhaust gas inlet 24:Exhaust gas outlet 25: Fog remover 26: Spray device 261: spray pipe 262: spray nozzle 263: spray port 27: Gas supply device 271:Nozzle 272: pump 273: Adjustment valve 274: Outlet 30:Gypsum separator D0: tolerance D1: Poor LT1, LT2, LT3: lower limit value NP: new parameter value OP: old parameter value P: parameter value PA: state value of the absorption liquid PA1: Oxidation-reduction potential of the absorption solution PA2: The slurry concentration of the absorption liquid PA3: The supply flow rate of the absorption liquid towards the gypsum separator PA4: The temperature of the overflow pipe PB: Status value of the absorption liquid pump PB1: The current value of the absorption liquid pump PB2: The discharge pressure of the absorption liquid pump PB3: The flow rate of the absorption liquid pump PC: Status value of exhaust gas PC1: concentration of sulfur oxides in exhaust gas PC2: The pressure difference between the inlet and outlet of the absorption tower P1,P2,P3,P4: points R1, R2, R3: appropriate range S1, S1A, S1B: Parameter value acquisition steps S2: The first defoamer supply control step S21: the first determination step S22: The first supply amount adjustment step S3: Second defoamer supply control step S31: The second determination step S32: Second supply amount adjustment step T1: period T2: established period TH: Threshold UT1, UT2, UT3: upper limit value

[ Fig. 1 ] is a flow chart of a method for suppressing foaming according to an embodiment of the present invention. [ Fig. 2 ] is a schematic configuration diagram schematically showing the configuration of an exhaust gas desulfurization system equipped with a foam suppression system according to an embodiment of the present invention. [ Fig. 3 ] is an explanatory diagram for explaining parameter values in an embodiment of the present invention. [ Fig. 4 ] is an explanatory diagram for explaining changes in parameter values due to foaming of the absorbing liquid, and is an explanatory diagram showing changes in oxidation-reduction potential over time. [Fig. 5] is an explanatory diagram for explaining changes in parameter values caused by foaming of the absorbing liquid. It shows changes in the slurry concentration of the absorbing liquid and the flow rate of the absorbing liquid to the gypsum separator over time. Illustrating. [ Fig. 6 ] is an explanatory diagram for explaining changes in parameter values due to foaming of the absorbent, and is an explanatory diagram showing changes in the current value of the absorbent pump over time. [ Fig. 7 ] is an explanatory diagram for explaining changes in parameter values caused by bubbling of the absorbing liquid, and is an explanatory diagram showing changes in the concentration of sulfur oxides in exhaust gas over time. [FIG. 8] It is a block diagram which shows the function of the defoamer supply amount adjustment apparatus which concerns on one embodiment of this invention. [FIG. 9] It is an explanatory drawing for demonstrating an example of the judgment of one embodiment of this invention. [FIG. 10] It is an explanatory drawing for demonstrating an example of the judgment of one embodiment of this invention. [ Fig. 11 ] is an explanatory diagram for explaining a method of setting a threshold value according to an embodiment of the present invention.

1: Foaming suppression method

Claims (16)

A method for suppressing foaming is a foaming suppressing method for suppressing generation of foaming in the absorbing liquid for desulfurization of the exhaust gas used for contacting the exhaust gas introduced into the absorption tower. The foaming agent supply control step, the second defoamer supply control step, and the defoamer supply adjustment step; the parameter value obtaining step is to obtain at least one parameter value related to the foaming state of the absorption liquid; the above The first antifoaming agent supply amount control step is to determine whether or not foaming has occurred in the absorbent liquid based on at least the parameter value obtained in the parameter value obtaining step, and when it is determined that foaming has occurred in the absorbent liquid, let The supply of the defoamer to the storage part is started or the supply of the defoamer is increased, and the storage part stores the absorption liquid after contacting the exhaust gas; the second control of the supply of the defoamer is at least based on The above-mentioned parameter value obtained again after the first antifoaming agent supply amount control step, that is, a new parameter value, determines whether the foaming of the aforementioned absorbent liquid has disappeared, and when it is determined that the foaming of the aforementioned absorbent liquid has disappeared, let the direction toward The supply of the aforementioned antifoaming agent in the aforementioned storage portion is reduced; the aforementioned step of adjusting the supply of the aforementioned antifoaming agent is to specify at least one value between the maximum value and the minimum value of the assumed aforementioned parameter values as an intermediate value, when the aforementioned parameter value becomes When the above-mentioned intermediate value is reached, the supply amount of the above-mentioned antifoaming agent toward the above-mentioned storage part is adjusted. The foaming suppression method as described in Claim 1, wherein, In the first antifoaming agent supply control step, it is judged whether or not the defoaming agent is generated in the absorbent liquid based on the parameter value obtained in the parameter value obtaining step and the predicted value of the parameter value assuming that the absorbent liquid does not foam. bubbly. The method for suppressing foaming according to claim 1 or 2, wherein the at least one parameter value includes: a state value of the absorption liquid after contact with the exhaust gas, ie, an oxidation-reduction potential of the absorption liquid. The method for suppressing foaming according to claim 3, wherein an appropriate range of the oxidation-reduction potential of the absorbing liquid is specified in advance by an upper limit value and a lower limit value, and when the antifoaming agent is supplied to the storage portion In this case, when the oxidation-reduction potential of the absorbing liquid reaches the lower limit value or falls below the lower limit value, the supply of the antifoaming agent to the storage portion is stopped. The method for suppressing foaming according to claim 1 or 2, wherein the old parameter value is compared with the new parameter value in the supply of the defoamer toward the storage portion, and the supply of the defoamer is adjusted according to the difference The value of the above-mentioned old parameter is any one of the above-mentioned parameters that are determined to be at the time point when the foaming of the above-mentioned absorbent liquid occurs, or the time point when it is judged that the above-mentioned absorption liquid does not generate foam before the time point of the above-mentioned foaming generation. value. The method for suppressing foaming according to claim 1 or 2, wherein the aforementioned at least one parameter value includes: the aforementioned The state value of the absorption liquid, that is, the slurry concentration of the aforementioned absorption liquid. The method for suppressing foaming according to claim 1 or 2, wherein the at least one parameter value includes: the state value of the absorption liquid pump used to transport the absorption liquid, that is, the current value of the absorption liquid pump and the current value At least one of the parameters obtained through numerical analysis. The method for suppressing foaming according to claim 1 or 2, wherein the at least one parameter value includes: the state value of the absorption liquid pump used to transport the absorption liquid, that is, the difference between the discharge pressure of the absorption liquid pump and the discharge pressure At least one of the range of changes. The method for suppressing foaming according to claim 1 or 2, wherein the at least one parameter value includes: the state value of the absorption liquid pump used to transport the absorption liquid, that is, the flow rate of the absorption liquid pump and the variation range of the flow rate at least any one of them. The method for suppressing foaming according to claim 1 or 2, wherein the at least one parameter value includes a state value of the absorption liquid flowing through a pipe supplying the absorption liquid from the storage part to the gypsum separator, namely At least one of the supply flow rate of the absorption liquid to the gypsum separator and the variation range of the supply flow rate. The foaming suppression method as described in Claim 1 or 2, wherein, The aforementioned at least one parameter value includes: the state value of the aforementioned exhaust gas after contacting with the aforementioned absorbing liquid, that is, the concentration of sulfur oxides in the aforementioned exhaust gas after contacting with the aforementioned absorbing liquid, the concentration of sulfur oxides in the aforementioned exhaust gas, and expected parameters At least one of the deviations of . The method for suppressing foaming according to claim 1 or 2, wherein the aforementioned at least one parameter value includes: the state value of the aforementioned exhaust gas after contacting the aforementioned absorption liquid, that is, the pressure of the aforementioned exhaust gas at the inlet of the aforementioned absorption tower and the aforementioned absorption At least one of the pressure difference of the exhaust gas at the outlet of the tower and the deviation of the pressure difference from the expected parameter. The method for suppressing foaming according to claim 1 or 2, wherein the at least one parameter value includes: the state value of the absorption liquid after contacting the exhaust gas, that is, the temperature of the overflow pipe connected to the storage part. The method for suppressing foaming according to Claim 1 or 2, wherein, in the aforementioned parameter value acquisition step, a plurality of parameter values of different types of the aforementioned parameter values are acquired, and in the aforementioned first defoamer supply amount control step, based on the When at least two parameter values among the plurality of parameter values obtained in the parameter value obtaining step are determined to be foaming in the absorption liquid, the supply of the antifoaming agent to the storage portion is started or the antifoaming agent is turned on. supply increases. The method for suppressing foaming according to claim 14, wherein, The aforementioned at least two parameter values include: the state value of the aforementioned absorbing liquid after contacting the aforementioned exhaust gas, that is, the oxidation-reduction potential of the aforementioned absorbing liquid. A foam suppressing system for suppressing foaming of the absorbing liquid used for desulfurization of the waste gas used for contacting with the waste gas introduced into the absorption tower, comprising: at least one parameter value acquisition device, Foaming agent storage device, defoaming agent supply pipeline, and defoaming agent supply adjustment device, the aforementioned at least one parameter value obtaining device is to obtain at least one parameter value related to the foaming state of the aforementioned absorption liquid; the aforementioned defoaming agent storage The device is to store the defoamer; the aforementioned defoamer supply pipeline is to send the aforementioned defoamer to the storage part from the aforementioned defoamer storage device, and the aforementioned storage part is to store the aforementioned absorption liquid after contacting the aforementioned waste gas; the aforementioned defoamer The agent supply amount adjusting device can adjust the amount of the aforementioned antifoaming agent sent from the aforementioned antifoaming agent storage device to the aforementioned storage part through the aforementioned antifoaming agent supply line; At least one parameter value obtained by the parameter value acquisition device is used to determine whether foaming has occurred in the absorbent liquid, and when it is determined that foaming has occurred in the absorbent liquid, the supply of the antifoaming agent to the storage portion is started or Increase the supply of the antifoaming agent, and at least determine whether the foaming of the absorbent liquid has disappeared based on at least the value of the aforementioned parameter obtained after it is determined that the foaming of the absorbent liquid has occurred, that is, a new parameter value. In the case where the foaming of the aforementioned absorbing liquid disappears, let The supply of the antifoaming agent toward the aforementioned storage portion is reduced, and at least one value between the assumed maximum value and the minimum value of the aforementioned parameter value is specified as an intermediate value. The supply amount of the aforementioned antifoaming agent in the storage part.

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