TW202138718A - Exhaust gas treatment system and exhaust gas treatment method for adding an appropriate amount of treatment agent at an appropriate timing based on early predicting the concentration changes of acid gas - Google Patents

Abstract

The present invention provides an exhaust gas treatment system that can early predict the period when the concentration of acid gas starts to increase due to the fluctuation of the oxygen concentration linked to the concentration fluctuation of the acid gas in the exhaust gas, and can add an appropriate amount of treatment agent at an appropriate timing. The exhaust gas treatment system includes: a treatment agent addition management unit 13, which has an exhaust gas analysis unit 131 and an exhaust gas analysis unit 132 that are disposed on at least one of the upstream side and the downstream side of an exhaust gas recovery unit 16 for at least analyzing the oxygen concentration in the exhaust gas, wherein the treatment agent addition management unit 13 is configured to, based on the amount of change in the oxygen concentration analyzed by the exhaust gas analysis unit 132, calculate the addition amount of the treatment agent required for treating the acid gas contained in the exhaust gas treated by an exhaust gas treatment unit 11, and to indicate the supply of the treatment agent of the calculated addition amount; and a treatment agent supply unit 14 that supplies the treatment agent of the addition amount indicated by the treatment agent addition management unit 13.

Description

Exhaust gas treatment system and exhaust gas treatment method

The invention relates to an exhaust gas treatment system and an exhaust gas treatment method.

Previously, by using a desuperheating tower to reduce the temperature of the exhaust gas discharged from the incinerator, the exhaust gas was passed through a filter-type dust collector, and the solid matter or acid gas in the exhaust gas was removed and discharged into the atmosphere from the chimney . However, only by passing the exhaust gas through the filter-type dust collector, the acid gas cannot be completely removed. At present, many domestic incineration equipment adopt the following dry exhaust treatment method: in the flue from the desuperheating tower to the filter dust collector, in order to neutralize and remove the acid gas, slaked lime is continuously blown in. For example, the following exhaust gas treatment methods and exhaust gas treatment devices are often used: non-woven fabrics and other cloths of filter-type dust collectors that purify exhaust gas discharged from gas generating sources such as self-incinerators are used to remove the exhaust gas by neutralization. The medicament of acid gas in the gas. However, exhaust gas treatment was insufficient, and acid gases such as sulfur oxides leaked. Therefore, in order to remove the acid gas in the exhaust gas, the following proposals have been made.

Patent Document 1 discloses a waste incinerator exhaust gas treatment method in which the measured value of the acid gas concentration in the exhaust gas on the outlet side or the inlet side of the filter type dust collector exceeds a predetermined value and the state of the excess continues for the predetermined value In the case of time, a sodium-based chemical in an amount set based on the measured value is supplied to the inlet side of the filter-type dust collector. In addition, Patent Document 2 discloses an exhaust gas treatment device having an upstream side acid gas concentration meter that measures the acid gas concentration of the exhaust gas, and measuring the acid gas concentration of the exhaust gas further downstream than the dust collector The downstream side acid gas concentration meter supplies a powder neutralizer to the exhaust gas between the reaction part and the dust collector to neutralize the remaining acid gas. Patent Document 3 discloses a method for controlling the addition of a desulfurizer based on the difference between the N hour moving average of the SOx concentration N hours ago and the N hour moving average of the current SOx concentration, that is, the first difference, and N hours ago The control value used in the calculation of the addition amount of the desulfurizing agent is calculated, and the control value of this time is calculated, and the addition amount of the desulfurization agent is determined based on the control value of this time.

However, in Patent Document 1 to Patent Document 3, sulfur oxides (SOx) in acid gases are analyzed. It takes a long time before the analysis results of sulfur oxides are obtained. Therefore, even if the concentration of sulfur oxides in the exhaust gas is Significant increase. Due to the time lag before the analysis results are released, the amount of the treatment agent required to treat the increased sulfur oxides cannot be added immediately. As a result, the sulfur oxides that have not been fully treated may be discharged into the atmosphere. middle. Therefore, the treatment agent for the treatment of sulfur oxides needs to be added in a certain amount more than the required addition amount, but the addition amount of the treatment agent that is more than the required addition amount is included in the separation and removal of the exhaust gas recovery section including fly ash, etc. The solid matter also contains unreacted treatment agent, so the recovery amount of solid matter will increase. When such an increase in solid matter is disposed of by landfill, etc., it is necessary to prepare additional storage space in the landfill, which is not good. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2019-070471 [Patent Document 2] Japanese Patent Laid-Open No. 2017-124348 [Patent Document 3] Japanese Patent Laid-Open No. 2017-176922

[The problem to be solved by the invention] Therefore, the present invention is made in view of the above actual situation, and the problem is to provide an exhaust gas treatment system and an exhaust gas treatment method that can early predict acidity due to changes in oxygen concentration linked to changes in the concentration of acid gases in exhaust gas. At the time when the gas concentration starts to increase, add an appropriate amount of treatment agent at an appropriate time.

[Means to solve the problem] In order to solve the above-mentioned problems, the main structure of the present invention is as follows. (1) An exhaust gas treatment system, including: an exhaust gas treatment part for treating exhaust gas; an exhaust gas recovery part for separating and removing solid components from the exhaust gas treated by the exhaust gas treatment part; a treatment agent storage part, A processing agent for processing the exhaust gas is stored; a processing agent addition management unit is provided with at least one of the upstream side and the downstream side of the exhaust gas recovery unit and analyzes at least the oxygen concentration in the exhaust gas The exhaust gas analysis unit calculates the processing required for the treatment of the acid gas contained in the exhaust gas processed by the exhaust gas processing unit based on the amount of variation in the oxygen concentration analyzed by the exhaust gas analysis unit The addition amount of the treatment agent, and instructs the supply of the treatment agent of the calculated addition amount; and the treatment agent supply part, which supplies the treatment agent of the addition amount instructed by the treatment agent addition management part from the treatment agent storage part to the Exhaust treatment department. (2) The exhaust gas treatment system according to (1), wherein the exhaust gas analysis unit is arranged on the downstream side of the exhaust gas recovery unit. (3) The exhaust gas treatment system according to (1) or (2), wherein the treatment agent has a characteristic of neutralizing acid gas in the exhaust gas. (4) The exhaust gas treatment system according to any one of (1) to (3), wherein the acid gas is a sulfur oxide gas. (5) An exhaust gas processing method, which calculates the amount of oxygen concentration processed by the exhaust gas processing unit based on the amount of variation in the oxygen concentration analyzed by the exhaust gas analysis unit having a processing agent addition management unit having the following exhaust gas analysis unit The addition amount of the treatment agent required for the treatment of the acid gas contained in the exhaust gas, and instructs the treatment agent supply unit to supply the calculated addition amount of the treatment agent, and transfers the indicated addition amount of the treatment agent from the treatment agent storage unit Supplied to the exhaust gas processing unit to process the acid gas contained in the exhaust gas, wherein the exhaust gas analysis unit is arranged to separate the gas contained in the exhaust gas from the solid matter and to recover and remove the solid matter At least one of the upstream side and the downstream side of the exhaust gas recovery part and at least analyze the oxygen concentration in the exhaust gas.

[Effects of the invention] According to the exhaust gas treatment system and the exhaust gas treatment method of the present invention, the concentration of sulfur oxides contained in the exhaust gas released into the atmosphere can be stably suppressed to be low without abruptly increasing, and the exhaust gas can be recovered The amount of unreacted treatment agent in the partially separated solid matter also decreases.

Hereinafter, embodiments of the present invention will be described. The following description is an example of the embodiment of the present invention, and does not limit the scope of the patent application.

(Exhaust gas treatment system) The exhaust gas treatment system 1 of this embodiment is the following exhaust gas treatment system, including: an exhaust gas treatment part 11 for treating exhaust gas; an exhaust gas recovery part 16 for self-use exhaust gas treatment part 11 for treatment Separation and recovery of solid components from the exhaust gas; the treatment agent storage section 12 stores the treatment agent used to treat the exhaust gas; the treatment agent addition management section 13 has the The exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 that analyze at least one side and at least the oxygen (O ₂ ) concentration in the exhaust gas are based on the change in the oxygen concentration analyzed by the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 The amount of the treatment agent required for the treatment of the acid gas contained in the exhaust gas treated by the exhaust treatment unit 11 is calculated, and the supply of the treatment agent of the calculated addition amount is instructed; and the treatment agent supply unit 14, The treatment agent of the addition amount instructed by the treatment agent addition management unit 13 is supplied from the treatment agent storage unit 12 to the exhaust treatment unit 11. Furthermore, the exhaust gas treatment system 1 is provided with an exhaust gas analysis unit 131 and an exhaust gas analysis unit 132 that analyze the oxygen concentration in the exhaust gas.

(Structure of exhaust gas treatment system) FIG. 1 is a diagram showing the structure of an exhaust gas treatment system that implements the exhaust gas treatment method of the present invention. Furthermore, in FIG. 1, among the lines connecting the blocks, the solid line represents the flow of objects, and the dash-dotted line represents the flow of information. The exhaust gas treatment system 1 of the treatment agent of this embodiment mainly includes an incinerator F, an exhaust gas treatment unit 11, a treatment agent supply unit 12, a treatment agent storage unit 14, and processes including an exhaust gas analysis unit 131 and an exhaust gas analysis unit 132. In addition to the agent addition management unit 13 and the exhaust gas recovery unit 16, a flow meter 17 and a chimney 18 are provided. Hereinafter, the structure of the exhaust gas treatment system 1 will be described in detail.

(Incinerator) Incinerator F, as an example, refers to combustion facilities such as municipal waste incinerators, industrial waste incinerators, power generation boilers, carbonization furnaces, and private factories. Generally speaking, the exhaust from municipal waste incinerators contains harmful acid gases such as hydrogen chloride (HCl), sulfur oxides (SOx), and nitrogen oxides (NOx), depending on the type of waste to be incinerated. , Solid matter (hereinafter referred to as "fly ash"). Among them, sulfur oxides are the most abundant. The exhaust gas has no particular limitation on its generation source or contained components, and it refers to the gas generated by the incineration of various wastes. "Sour gas" refers to a gas that is dissolved in a solution and exhibits acidity, for example, it refers to a gas containing hydrogen chloride or sulfur oxides.

(Exhaust Treatment Department) The exhaust treatment unit 11 performs treatment of inputting and adding a treatment agent to the exhaust gas. Since the exhaust gas is an acid gas containing sulfur oxides, it is necessary to neutralize the acid gas and suppress the discharge of harmful gases into the environment before being discharged into the atmosphere. Therefore, in the exhaust gas treatment unit 11, a neutralizing agent is added to the exhaust gas as a treatment agent to neutralize it. As the treatment agent (hereinafter, sometimes referred to as "neutralizing agent"), a neutralizing agent is used. This treatment agent can neutralize the acid gas contained in the exhaust gas by contacting the exhaust gas.

The exhaust treatment unit 11 is not particularly limited as long as it can contact and react the exhaust gas with a solid treatment agent. For example, a part of the flue (gas flow path) may be used as the exhaust gas.处理部11。 Processing section 11. However, as a flue, a part of a transfer pipe or the like for transferring the exhaust gas to the exhaust gas recovery unit 16 such as a bag filter on the downstream side may also be used. Furthermore, the exhaust treatment part 11 may include a closed container, various reaction containers, etc. additionally installed in the flue (gas flow path).

Furthermore, the acid gas contained in the exhaust gas does not need to be chemically neutralized in the exhaust treatment section 11, and may be transferred to the downstream side of the treatment agent along with the exhaust gas (for example, self-draining). The flue from the gas treatment part 11 to the exhaust gas recovery part 16) is neutralized. For example, when slaked lime is used as a treatment agent, the reaction of slaked lime with acid gas is slow, so this may happen.

In addition, the exhaust gas treatment can be performed continuously. In addition, for example, it is also possible to use a closed container or various reaction containers for gas reversal application and to perform batch type. In any case, the amount of exhaust gas to be processed is not particularly limited, and it can be appropriately designed in consideration of the amount of exhaust gas generated by incineration of waste.

(Processing agent storage department) The processing agent storage unit 14 stores a processing agent for processing exhaust gas. In the exhaust gas treatment system 1 of this embodiment, the treatment agent stored in the storage unit 14 is managed. The storage unit 14 is not particularly limited as long as it can store the treatment agent, and for example, a storage tank or a silo can be used. The capacity or shape of the storage unit 14 is not particularly limited, and it can be appropriately designed in consideration of its installation space, the operation schedule of the exhaust gas treatment, the treatment volume of the exhaust gas, the treatment frequency of the exhaust gas, and the frequency of ordering treatment agents.

(Processing agent addition management department) The treatment agent addition management unit 13 has an exhaust gas analysis unit 131 and an exhaust gas analysis unit 132 arranged on either or both of the upstream side and the downstream side of the exhaust treatment unit 11. The processing agent addition management unit 13 analyzes the exhaust gas by the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132, calculates the addition amount of the processing agent required for exhaust gas processing, and instructs the supply of the processing agent of the calculated addition amount. In this manner, the processing agent addition management unit 13 changes the addition amount of the processing agent in accordance with the variation in the analysis value based on the nature of the exhaust gas to be processed (for example, the concentration and flow rate of acid gas), the size of the exhaust processing unit 11, and the like. In addition, the "upstream side" and "downstream side" herein refer to the upstream and downstream in the flow of exhaust gas.

In addition, the instruction regarding the addition amount of the processing agent sent from the processing agent addition management unit 13 is transmitted to the processing agent supply unit 14, such as a doser provided on the upstream side of the exhaust processing unit 11. The processing agent supply unit 14 operates to add a predetermined amount of processing agent to the exhaust processing unit 11.

The treatment agent addition management unit 13 preferably has an arithmetic circuit for exhaust gas for each quantity (for example, a certain flow rate, a certain time, or a batch) when the exhaust treatment is performed in the exhaust treatment section 11. Numerically stored values are calculated when the number of times of exhaust gas treatments or when sulfur oxides and other components are reduced during treatment with a certain additive amount of treatment agent, and various values are calculated. The control method for arithmetic processing includes the method of analyzing the acid gas in the exhaust gas and calculating the amount of the treatment agent required to neutralize the gas (feedforward control), or calculating the required amount based on the acid gas in the processed exhaust gas The amount of treatment agent (feedback control).

(Exhaust Gas Analysis Department) The exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 respectively analyze the properties of the exhaust gas before and after the treatment agent is added, and can analyze the concentrations of hydrogen chloride (HCl), sulfur oxides (SOx), and nitrogen oxides (NOx) in the exhaust gas. In addition, the flow rate of exhaust gas can also be analyzed. The processing agent addition management unit 13 manages the analysis values of the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132. The exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 are preferably provided on the downstream side of the exhaust gas recovery unit 16. It may also be the upstream side of the exhaust gas recovery part 16, but the upstream side of the exhaust gas recovery part 16 contains more fly ash. Analysis accuracy of the gas. Accordingly, in the exhaust gas analysis unit 132, the analysis of the oxygen concentration is performed instead of the sulfur oxide concentration, and the result of the analysis is that after the oxygen concentration starts to decrease, the treatment agent is added according to the oxygen concentration. The oxygen concentration analysis methods include zirconia method, magnetic method, laser spectroscopy method, and electrode method. Any method can be used, but it is preferable to use a zirconia method.

In the zirconia method, porous platinum electrodes are attached to both sides of a zirconia element and heated, and gases with different oxygen partial pressures are brought into contact with the respective surfaces to produce an oxygen concentration battery. Due to the function of the battery, an electromotive force is generated between the two electrodes, and the oxygen concentration can be analyzed. In addition, by comparing the analysis results obtained from the exhaust analysis section 131 and the exhaust analysis section 132 respectively arranged on the upstream and downstream sides of the exhaust treatment section 11, the neutralization point of the exhaust gas can also be calculated more accurately. The amount of treatment agent required.

Furthermore, in order to further improve the calculation accuracy of the usage amount of the processing agent, the exhaust gas flow rate is analyzed by the exhaust gas flow meter 19. In addition, the exhaust gas volume hardly changes before and after the processing agent is added. Therefore, in FIG. 1, the exhaust gas flowmeter is arranged together with the exhaust gas analysis unit 132, but the position of the exhaust gas flowmeter is not limited to this example. By analyzing the exhaust gas volume, it is possible to calculate the absolute amount of acid gas contained in the exhaust gas in combination with the analysis value of the acid gas concentration analysis, so that the required quality of the treatment agent can be calculated more accurately.

(Processing agent supply department) The treatment agent supply unit 14 supplies the treatment agent of the addition amount instructed by the treatment agent addition management unit 13 from the supply unit 12 to the exhaust treatment unit 11. The processing agent supply unit 14 is not particularly limited as long as it can supply a predetermined amount of processing agent from the processing agent supply unit 12 to the exhaust processing unit 11, and may include, for example, a doser, a pump, and a powder supply machine.

(Treatment agent) The treatment agent has the characteristic of neutralizing the acid gas in the exhaust gas. The treatment agent may be in a liquid form or in a powder form (solid form), but it is necessary to have a component whose addition amount can be calculated by analyzing the exhaust gas.

The treatment agent is not particularly limited. For example, calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate, calcium hydroxide-magnesium hydroxide, calcium oxide-magnesium oxide, calcium carbonate-carbonic acid can be used. Magnesium, sodium hydroxide, sodium bicarbonate, sodium carbonate, etc. One kind of treatment agent may be used alone, or two or more kinds may be used in combination.

When a powdery treatment agent is used as the treatment agent, the average particle size is preferably 1 μm or more, more preferably 2 μm or more, and still more preferably 5 μm or more. When the average particle size of the treatment agent is 1 μm or more, it is possible to prevent a rise in the differential pressure of the exhaust gas recovery section 16 on the downstream side, or to prevent an increase in the acid gas concentration in the exhaust gas due to a decrease in recovery efficiency. In addition, the average particle diameter of the treatment agent is preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less. When the average particle size of the treatment agent is 50 μm or less, it is possible to ensure a sufficiently large specific surface area of the treatment agent for contact with exhaust gas.

(Exhaust Gas Recovery Department) In the exhaust gas treatment system 1, an exhaust gas recovery unit 16 such as a bag filter is provided on the downstream side of the exhaust gas treatment unit 11. The exhaust gas recovery unit 16 removes fly ash, which is a solid substance, contained in the exhaust gas. When a part of the treatment agent added to the exhaust treatment unit 11 is not used for the neutralization reaction of the exhaust treatment and remains in an unreacted state, the fly ash removed here also includes the unreacted treatment Agent. In addition, it also includes sulfur oxides that react with the treatment agent, unreacted hydrogen chloride (HCl), sulfur oxides (SOx), and nitrogen oxides (NOx). After a certain period of time has passed, the fly ash collected in the exhaust gas recovery unit 16 is recovered and discharged to the outside.

(Supply quantity meter) The treatment agent addition management unit 13 may have a supply amount meter (not shown) on the downstream side of the treatment agent supply unit 14 and on the upstream side of the exhaust gas treatment unit 11. The supply amount meter measures the amount of the treatment agent supplied from the treatment agent supply unit 14 to the exhaust treatment unit 11.

(Exhaust gas treatment method) The exhaust gas treatment method of this embodiment is based on the amount of variation in oxygen concentration analyzed by the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 of the processing agent addition management unit 13 having the following exhaust gas analysis unit 131 and the exhaust gas analysis unit 132. Calculate the addition amount of the treatment agent required for the treatment of the acid gas contained in the exhaust gas processed by the exhaust treatment unit 11, and instruct the treatment agent supply unit 14 to supply the calculated addition amount of the treatment agent, The additive amount of the treatment agent is supplied from the treatment agent storage part 12 to the exhaust treatment part 11 to process the acid gas contained in the exhaust gas. The exhaust gas analysis part 131 and the exhaust gas analysis part 132 are arranged in the exhaust The gas contained in the gas is separated from the solid matter and recovered to remove at least one of the upstream side and the downstream side of the exhaust gas recovery unit 16 that removes the solid matter, and analyzes at least the oxygen concentration in the exhaust gas.

(Operation of exhaust gas treatment system) Here, the operation in the exhaust gas treatment method of the exhaust gas treatment system 1 will be described. In the case where the exhaust gas is generated by incineration of waste in the incinerator F, for example, the exhaust gas is processed through the following route. The exhaust gas generated in the incinerator F is cooled by passing through a flue and a desuperheating tower (both not shown), and the fly ash is removed or recovered in the exhaust gas recovery part 16. After that, it passes through the exhaust gas recovery unit 16 and is transferred to the exhaust gas analysis unit 132 of the processing agent addition management unit 13. After the exhaust gas analysis unit 132 analyzes the oxygen concentration in the exhaust gas, the processing agent addition management unit 13 sends out an amount required to process the sulfur oxides contained in the exhaust gas according to the fluctuation amount of the oxygen concentration. Instructions for the treatment agent. The sulfur oxide in the exhaust gas is neutralized in the exhaust gas treatment unit 11 using the treatment agent supplied from the treatment agent supply unit 12 in accordance with an instruction from the treatment agent addition management unit 13. Next, the exhaust gas analyzer 132 analyzes the oxygen concentration, the sulfur oxide concentration, and the like, and after confirming that the sulfur oxide concentration of the exhaust gas is below the reference level, the exhaust gas passes through the chimney 18 and is discharged into the atmosphere. Furthermore, the fly ash removed by the exhaust gas recovery unit 16 is further subjected to treatments such as immobilization of heavy metals and the like, removal and landfill.

(Oxygen Concentration Behavior) In the present embodiment, the exhaust gas analysis unit 132 analyzes the oxygen (O ₂ ) concentration in the exhaust gas. Previously, in the treatment of acid gas in exhaust gas with a treatment agent, the concentration of acid gas in the exhaust gas for the purpose of neutralization, such as sulfur oxide (SO _X ), was analyzed. However, it takes a long time (for example, 4 minutes or more) before the result of the analysis of acid gas (for example, sulfur oxide SO _X ) by the exhaust gas analysis unit 132 comes out. Therefore, even if the concentration of acid gas based on the analysis result is an appropriate amount The treatment agent is added to the exhaust treatment section to treat the exhaust gas. The concentration of acid gas contained in the treated exhaust gas may fluctuate at the time when the treatment agent is added. Therefore, the amount of the treatment agent added may not necessarily be added. No more, no less, sometimes the acid gas concentration cannot be stably suppressed to a low level, and the acid gas temporarily rises and fluctuates to a high concentration. Therefore, the inventors conducted intensive research and found that there is a correlation between the acid gas concentration contained in the exhaust gas and the oxygen concentration. As the acid gas concentration starts to increase, the oxygen concentration starts to decrease. In addition, it is clarified that in the analysis of the oxygen in the exhaust gas, the time from the beginning of the analysis to the result is less than half of the analysis time of the acid gas (for example, about 2 minutes). Therefore, the oxygen concentration in the exhaust gas is analyzed to predict the oxygen concentration. After starting to decrease, the acid gas starts to rise, and the required treatment agent is immediately added to the exhaust treatment section according to the decrease ratio of the oxygen concentration. As a result, the acid gas does not temporarily increase to a high concentration and the concentration of the acid gas is stably suppressed. Low. Accordingly, in the present invention, instead of using the analysis result of the sulfur oxide concentration in the exhaust gas based on the analysis result of the oxygen concentration in the exhaust gas, an appropriate amount of the treatment agent is added at the time point when the oxygen concentration in the exhaust gas starts to decrease. , And implement the neutralization treatment of sulfur oxides in the exhaust gas, thereby preventing the acid gas from temporarily rising and changing to a high concentration, and stably suppressing the concentration of the acid gas to a low level.

The correlation between the oxygen concentration and the sulfur oxide concentration differs according to the characteristics of the device of the exhaust gas treatment system, the size of the device, the condition of the reaction generating the exhaust gas, and the like. Therefore, a calibration curve based on the relationship between the oxygen concentration and the sulfur oxide concentration of each exhaust gas treatment system is prepared in advance, and on this basis, the exhaust gas volume is considered together to determine the acid gas contained in the exhaust gas. The amount of treatment agent required for treatment.

(Analysis time of sulfur oxide concentration) In addition, the analysis of the concentration of sulfur oxides was carried out by using the light absorption in the infrared region of sulfur dioxide, which is the main component of sulfur oxides, to obtain the concentration of sulfur dioxide. Specifically, the infrared absorption of sulfur dioxide in the vicinity of 7.3 μm was analyzed, and the concentration of sulfur dioxide contained in the exhaust gas was continuously analyzed. However, although the current analysis of sulfur oxides also depends on the analysis principle, it takes several minutes before the results come out. The current situation is that the minimum time required is 4 minutes. According to this amount of time, the exhaust gas self-incinerator F flows to the chimney 18 through the exhaust gas recovery part 11. Therefore, from the beginning of the analysis to the results, the exhaust gas that has not been injected with the treatment agent flows into the atmosphere.

(Analysis time of oxygen concentration) Therefore, the exhaust gas treatment system 1 of the present embodiment does not analyze the concentration of sulfur oxides in the exhaust gas, but focuses on the oxygen in the exhaust gas, and analyzes and measures the oxygen concentration. The analysis and measurement method can be performed by using a zirconia-type oxygen concentration meter installed upstream or downstream of the exhaust gas analysis unit 132 of the exhaust gas treatment system 1. Generally, in the oxygen concentration analysis, the zirconia method can be analyzed in 2 minutes, which can be analyzed in a shorter time than the concentration analysis of sulfur oxides. Therefore, the analysis time of the oxygen concentration meter can be set to a short time after the exhaust reaches the exhaust analysis part 132. Therefore, even at the downstream side of the exhaust recovery part 16, the oxygen concentration is analyzed and the analysis value is output. The processing agent addition management unit 13 issues an instruction to the processing agent supply unit 12, whereby the processing agent supply unit 12 supplies the processing agent and the exhaust processing unit 11 performs processing. In this way, the exhaust gas that is not neutralized by the treatment agent can be reduced, and the exhaust gas that is not neutralized and leaks into the atmosphere can be reduced.

(Utilization of oxygen concentration changes) As described above, by using the time taken to analyze the oxygen concentration and sulfur oxide concentration as the analysis target in the exhaust gas analysis unit 132, and the change behavior of the oxygen concentration and sulfur oxide concentration in the exhaust gas treatment system 1 The time difference between the two can greatly reduce the exhaust gas that is not neutralized by the treatment agent, and reduce the exhaust gas that is not neutralized and leaks into the atmosphere. In this way, by minimizing the delay time that cannot correspond to the neutralization treatment of sulfur oxides, it is possible to suppress the leakage of exhaust gas containing sulfur oxides from the chimney.

(Phase addition of treatment agent) In addition, the mass of acid gas processed per hour is obtained from the exhaust gas volume and the sulfur oxide concentration, and multiplied by the amount of the treatment agent that takes into account the neutralization reaction of the unit amount of sulfur oxides to obtain the The amount of treatment agent required. On this basis, the feedforward control method or the feedback control method is used to implement the addition control of the treatment agent to the exhaust gas. Therefore, in the present embodiment, similar to the control method based on the analysis of the sulfur oxide concentration so far, the logic of controlling the addition amount of the treatment agent based on the change in the oxygen concentration analyzed by the exhaust gas analysis unit 132 is used. The embedding treatment agent addition management unit 13 controls the treatment of sulfur oxides.

However, the oxygen concentration changes slowly compared to the sulfur oxide concentration. In addition, the change in oxygen concentration indicates the start time point of adding the treatment agent, but the oxygen concentration does not completely correspond to the sulfur oxide concentration. Therefore, it is preferable not to completely correspond to the change in the oxygen concentration, but to gradually change the amount of the treatment agent added in response to the change in the oxygen concentration. For example, when the oxygen concentration is decreased, the amount of the treatment agent is not determined based on the decreased amount, and a large amount is added even for the initial addition of the treatment agent. The amount to be added stepwise with respect to the oxygen concentration is determined in advance. After that, the decreasing tendency of the oxygen concentration becomes smaller, and the amount of the treatment agent added is greatly reduced. By performing the stepwise treatment in this way, the sulfur oxide neutralization treatment can be performed corresponding to the oxygen concentration in the exhaust gas treatment system 1.

(Exhaust gas analysis section on the upstream side) In addition, the analysis value of the oxygen concentration uses the exhaust gas analysis unit 132 on the downstream side of the exhaust gas recovery unit 16, and the processing agent addition management unit 13 may also use the analysis based on the exhaust gas analysis unit 131 on the upstream side of the exhaust gas recovery unit 16. The obtained analysis value is managed. When the processing agent supply unit 12 and the position of the exhaust gas analysis are close in distance and time, the processing agent can be added to the exhaust gas immediately. [Example]

Hereinafter, the present invention will be explained in more detail based on examples. The present invention is not limited by these embodiments.

In order to neutralize the sulfur oxides in the exhaust gas and recover them by the exhaust gas recovery unit, the amount of sulfur oxides is usually analyzed after the exhaust gas recovery unit. The control of sulfur oxides is based on the results of sulfur analysis, and feedback control methods such as Proportional Integral Derivative (PID) can be used to control the addition amount of the treatment agent. So far, in most cases, the sulfur oxide concentration is analyzed on the downstream side of the exhaust gas recovery section, and based on the analysis result, the treatment agent is provided on the upstream side of the exhaust gas recovery section. In order to compare the influence of the analysis of the oxygen concentration and the sulfur oxide concentration on the downstream side of the exhaust gas recovery section, the transition of the sulfur oxide concentration when each concentration analysis is performed and the consumption of hydrated lime as a processing agent are analyzed.

(Comparative example 1) As Comparative Example 1, in a factory equipped with the exhaust gas treatment system, the same exhaust gas treatment method as before was used to analyze the concentration of sulfur oxides and perform exhaust gas treatment. Here, regardless of the change in the oxygen concentration, the change in the sulfur oxide concentration is captured, and the addition of the treatment agent is started. The transition of the sulfur oxide concentration and the addition time of the treatment agent at this time is shown in FIG. 2. In the analysis of the sulfur oxide concentration, an infrared-based sulfur oxide analyzer is used, and the response time after the exhaust reaches the analyzer is several minutes. Specifically, the response time to 90% is about 240 seconds. On the other hand, the oxygen concentration can be analyzed to 90% response in about 120 seconds using the zirconia method.

Exhaust flows into the exhaust treatment part of the exhaust treatment system shown in FIG. 1. As shown in FIG. 2, at _{the time when the concentration of sulfur dioxide (SO 2} ) as sulfur oxides starts to increase, slaked lime as a treatment agent is added . However, at the position of the exhaust gas analysis section located on the downstream side of the exhaust gas recovery section, the SO ₂ concentration starts to increase sharply. After that, after about 1 minute to 2 minutes have passed, after the SO ₂ concentration reaches its peak, the effect of the treatment agent addition begins to appear, and the SO ₂ concentration decreases. From this, it can be seen that the addition of the treatment agent into the exhaust gas treatment section fails to sufficiently treat the SO ₂ concentration contained in the exhaust gas. When the exhaust gas mixed with the treatment agent reaches the exhaust gas analysis unit, the exhaust gas containing a large amount of sulfur oxides that has not been treated by the treatment agent is discharged through the chimney and leaks into the atmosphere in 1 to 2 minutes.

(Example 1) Next, _{a change in the concentration of oxygen (O 2} ) was captured, and a treatment agent was added. The transition of the O ₂ concentration and the amount of the treatment agent at this time is shown in FIG. 3. _{In Example 1, the SO 2} concentration and the O ₂ concentration contained in the exhaust gas were analyzed in advance, and on the basis of creating a calibration curve, a program for gradually changing the addition amount of the treatment agent was introduced as follows, and set to the previous The control method is the same as the method of using high addition amount in this program. Table 1 shows the relationship between the oxygen concentration (%) and the amount of slaked lime (kg/h).

[Table 1] Oxygen concentration (%) 10.0 or more 7.0～10.0 6.0～7.0 4.5～6.0 4.5 or less Adding amount of slaked lime (kg/h) 77 150 200 250 300

As shown in Fig. 3, after 1 minute has passed through the exhaust gas, when the oxygen concentration is lower than 10%, slaked lime as a treatment agent is added. However, two minutes after the time when the oxygen concentration decreased, the exhaust gas with a high sulfur oxide concentration flows into the exhaust gas analysis section located on the downstream side of the exhaust gas recovery section. Therefore, when the exhaust gas mixed with the processing agent reaches the exhaust gas analysis unit, the exhaust gas containing a large amount of sulfur oxides that have not been neutralized is discharged to the outside. However, about 1 minute before the increase in the concentration of sulfur oxides, the addition of hydrated lime was started. Therefore, the peak of the sulfur oxide concentration is very low compared to Comparative Example 1. In addition, instead of continuously changing the amount of slaked lime added during changes in oxygen concentration, the amount of added slaked lime is changed stepwise during changes in oxygen concentration, so that although the consumption of slaked lime is large, there is no effect on sulfur oxides. Treated sulfur oxides. It means that by these treatments, exhaust gas containing a large amount of sulfur oxides that have not been treated with a treatment agent is discharged to the outside and leaks very little.

Among them, in Example 1, it can be seen that slaked lime has been added much earlier than in Comparative Example 1, and therefore the addition time is long, and the added amount of slaked lime has increased. Among them, it is also known that the neutralization treatment of sulfur oxides in the exhaust gas can be sufficiently performed by this.

Furthermore, it is clear from the slaked lime shown in Figs. 2 and 3 that in an actual exhaust gas treatment system, a certain amount of treatment agent is always added regardless of the oxygen concentration and the sulfur oxide concentration. Here, "addition of the treatment agent" means the addition of a treatment agent in a larger amount than usual addition.

1: Exhaust treatment system 11: Exhaust treatment department 12: Treatment agent storage department 13: Treatment agent addition management department 131, 132: Exhaust Analysis Department 14: Treatment agent supply department 16: Exhaust gas recovery department 17: Exhaust flow meter 18: Chimney F: Incinerator

FIG. 1 is a diagram showing the structure of an exhaust gas treatment system that implements the exhaust gas treatment method of the present invention. _{FIG. 2 is a graph showing the transition of the SO 2} concentration, the O ₂ concentration, and the input amount of slaked lime when the treatment agent is added _{based on the analysis result of the SO 2} concentration contained in the exhaust gas. _{FIG. 3 is a graph showing the transition of the SO 2} concentration, the O ₂ concentration, and the input amount of slaked lime when the treatment agent is added _{based on the analysis result of the O 2} concentration contained in the exhaust gas.

1: Exhaust treatment system

11: Exhaust treatment department

12: Treatment agent storage department

13: Treatment agent addition management department

14: Treatment agent supply department

16: Exhaust gas recovery department

17: Exhaust flow meter

18: Chimney

131, 132: Exhaust Analysis Department

F: Incinerator

Claims (5)

An exhaust gas treatment system, including: Exhaust treatment section, used to treat exhaust gas; An exhaust gas recovery unit, which separates and removes solid components from the exhaust gas processed by the exhaust gas treatment unit; A treatment agent storage part, which stores a treatment agent used to treat the exhaust gas; The treatment agent addition management unit has an exhaust gas analysis unit that is disposed on at least one of the upstream side and the downstream side of the exhaust gas recovery unit and analyzes at least the oxygen concentration in the exhaust gas. The analysis unit analyzes the variation of the oxygen concentration, calculates the addition amount of the treatment agent required for the treatment of the acid gas contained in the exhaust gas processed by the exhaust treatment unit, and indicates the calculated addition amount The supply of treatment agents; and The treatment agent supply unit supplies the treatment agent in the addition amount instructed by the treatment agent addition management unit from the treatment agent storage unit to the exhaust treatment unit. The exhaust gas treatment system according to claim 1, wherein the exhaust gas analysis unit is arranged on the downstream side of the exhaust gas recovery unit. The exhaust gas treatment system according to claim 1 or claim 2, wherein the treatment agent has a characteristic of neutralizing acid gas in the exhaust gas. The exhaust gas treatment system according to any one of claim 1 to claim 3, wherein the acid gas contains sulfur oxides. An exhaust gas processing method that calculates the amount of change in the exhaust gas processed by the exhaust gas processing unit based on the amount of variation in oxygen concentration analyzed by the exhaust gas analysis unit having a processing agent addition management unit having the following exhaust gas analysis unit The added amount of the processing agent required for the treatment of the acid gas contained therein is instructed to the processing agent supply unit for the supply of the calculated addition amount of the processing agent, and the indicated addition amount of the processing agent is supplied to the processing agent storage unit from the processing agent storage unit. The exhaust gas processing unit processes the acid gas contained in the exhaust gas, wherein the exhaust gas analysis unit is arranged to separate the gas contained in the exhaust gas from the solid matter and to recover and remove the solid matter from the exhaust gas At least one of the upstream side and the downstream side of the recovery unit analyzes at least the oxygen concentration in the exhaust gas.

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