JP2021166976A - Exhaust gas treatment system and exhaust gas treatment method - Google Patents

Abstract

To provide an exhaust gas treatment system which enables: early prediction of time when a concentration of an acidic gas begins to increase due to a variation of oxygen concentration linked with a concentration variation of an acidic gas in an exhaust gas; and addition of a proper amount of a treatment agent at a proper timing.SOLUTION: An exhaust gas treatment system includes: exhaust gas analysis parts 131 and 132 which are disposed at least on one side of the upstream side and downstream side of an exhaust gas recovery part 16 and at least analyze oxygen gas concentration in an exhaust gas; a treatment agent addition control part 13 which calculates an addition amount of a treatment agent required to treat an acidic gas contained in the exhaust gas to be treated in an exhaust gas treatment part 11 based on a variation amount of oxygen gas concentration analyzed by the exhaust gas analysis part 132 and instructs supply of the treatment agent of a calculated addition amount; and a treatment agent supply part 14 which supplies the treatment agent of an addition amount instructed by the treatment agent addition control part 13.SELECTED DRAWING: Figure 1

Description

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

Conventionally, the exhaust gas discharged from the incinerator is cooled by a temperature reducing tower, and then the exhaust gas is passed through a filtration type dust collector to remove solids and acid gas in the exhaust gas, and then from the chimney to the atmosphere. I am trying to discharge it.
However, acid gas cannot be completely removed only by passing the exhaust gas through a filtration type dust collector. Currently, many incineration plants in Japan have adopted a dry exhaust gas treatment method in which slaked lime is continuously blown into the flue from the temperature reduction tower to the filtration type dust collector to neutralize and remove acid gas. ing. For example, an exhaust gas treatment method in which a chemical for removing acid gas in the exhaust gas by a neutralizing action is added to a cloth such as a non-woven fabric of a filtration type dust collector that purifies the exhaust gas discharged from a gas generation source such as an incinerator. , And exhaust gas treatment equipment are often used. However, the treatment of exhaust gas is insufficient, and acid gas such as sulfur oxide is leaking. Therefore, the following proposals have been made to remove acid gas in the exhaust gas.

In Patent Document 1, when the measured value of the acid gas concentration in the exhaust gas on the outlet side or the inlet side of the filtration type dust collector exceeds a predetermined value and the excess state continues for a predetermined time, the measured value A method for treating exhaust gas from a waste incinerator that supplies an amount of sodium-based chemicals set according to the above to the inlet side of a filtration type dust collector is disclosed. Further, Patent Document 2 has an upstream acid gas concentration meter for measuring the acid gas concentration of exhaust gas and a downstream acid gas concentration meter for measuring the acid gas concentration of exhaust gas on the downstream side of the dust collector. An exhaust gas treatment device that supplies a powder neutralizer to the exhaust gas between the reaction unit and the dust collector to neutralize the balance of the acid gas is disclosed. In Patent Document 3, the first difference, which is the difference between the N-time moving average value of the SOx concentration N hours ago and the N-time moving average value of the current SOx concentration, and the calculation of the amount of the desulfurizing agent added N hours ago. A desulfurizing agent addition control method for calculating the current control value based on the control value used in the above and determining the addition amount of the desulfurizing agent based on the current control value is disclosed.

However, in Patent Documents 1 to 3, all of them analyze sulfur oxides (SOx) in acidic gas, and it takes a considerable amount of time to obtain the analysis results of sulfur oxides, so that they are contained in exhaust gas. Even if the concentration of sulfur oxides in Sulfur oxides increases significantly, the amount of treatment agent required to treat the increased sulfur oxides cannot be added immediately due to the time lag until the analysis results are obtained. As a result, sulfur oxides that cannot be sufficiently treated may be discharged into the atmosphere. Therefore, the treatment agent for treating sulfur oxides needs to be added in an amount somewhat larger than the required addition amount, but adding a treatment agent in an addition amount larger than the required addition amount is an exhaust gas recovery unit. Since the unreacted treatment agent is also contained in the solid matter containing fly ash and the like that is separated and removed in (1), the amount of the solid matter recovered is increased. When the solid matter increased in this way is disposed of by landfill or the like, it is not preferable because it is necessary to prepare an extra storage space for the landfill.

Japanese Unexamined Patent Publication No. 2019-070741 JP-A-2017-124348 JP-A-2017-176922

Therefore, the present invention has been made in view of the above circumstances, and it is possible to predict at an early stage the time when the acid gas concentration starts to increase due to the fluctuation of the oxygen gas concentration linked to the fluctuation of the acid gas concentration in the exhaust gas. An object of the present invention is to provide an exhaust gas treatment system and an exhaust gas treatment method capable of adding a treatment agent in an appropriate amount at an appropriate timing.

In order to solve the above problems, the gist structure of the present invention is as follows.
(1) An exhaust gas treatment unit for treating exhaust gas, an exhaust gas recovery unit for separating and removing solids from the exhaust gas treated by the exhaust gas treatment unit, and a treatment agent storage unit for storing a treatment agent for treating the exhaust gas. And the exhaust gas analysis unit, which is arranged on at least one of the upstream side and the downstream side of the exhaust gas recovery unit and analyzes at least the oxygen gas concentration in the exhaust gas, and is analyzed by the exhaust gas analysis unit. Based on the fluctuation amount of the oxygen gas concentration, the addition amount of the treatment agent required for the treatment of the acidic gas contained in the exhaust gas to be treated by the exhaust gas treatment unit is calculated, and the supply of the treatment agent of the calculated addition amount is instructed. An exhaust gas treatment system including a treatment agent addition control unit and a treatment agent supply unit that supplies a treatment agent in an amount specified by the treatment agent addition control unit from the treatment agent storage unit to the exhaust gas treatment unit.
(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 property of neutralizing an 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) The oxygen gas concentration in the exhaust gas is arranged on at least one of the upstream side and the downstream side of the exhaust gas recovery unit that separates the gas and the solid matter contained in the exhaust gas and recovers and removes the solid matter. Based on the fluctuation amount of the oxygen gas concentration analyzed by the exhaust gas analysis unit of the treatment agent addition control unit having an exhaust gas analysis unit that analyzes at least The required amount of the treatment agent is calculated, the calculated amount of the treatment agent is instructed to be supplied to the treatment agent supply unit, and the instructed amount of the treatment agent is supplied from the treatment agent storage unit to the exhaust gas treatment unit. An exhaust gas treatment method for treating the acidic gas contained in the exhaust gas.

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 a low level without suddenly increasing, and the exhaust gas recovery unit. The amount of unreacted treatment agent in the solid matter separated and removed by is also reduced.

It is a figure which shows the structure of the exhaust gas treatment system which carries out the exhaust gas treatment method of this invention. It is a graph which shows 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 concentration of _{SO 2} contained in the exhaust gas. It is a graph which shows 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 concentration of _{O 2} contained in the exhaust gas.

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

(Exhaust gas treatment system)
The exhaust gas treatment system 1 according to the present embodiment treats the exhaust gas, the exhaust gas treatment unit 11 for treating the exhaust gas, the exhaust gas recovery unit 16 for separating and recovering the solid content from the exhaust gas treated by the exhaust gas treatment unit 11. The treatment agent storage unit 12 for storing the treatment agent for the purpose and the exhaust gas recovery unit 16 are arranged on at least one of the upstream side and the downstream side, and at least analyze _{the oxygen gas (O 2) concentration in the exhaust gas.} A treatment agent having exhaust gas analysis units 131 and 132 and required for processing acidic gas contained in the exhaust gas to be processed by the exhaust gas treatment unit 11 based on the fluctuation amount of the oxygen gas concentration analyzed by the exhaust gas analysis units 131 and 132. The treatment agent addition control unit 13 that calculates the addition amount of It is an exhaust gas treatment system including a treatment agent supply unit 14 for supplying the exhaust gas treatment unit 11. Further, the exhaust gas treatment system 1 is provided with exhaust gas analysis units 131 and 132 for analyzing the oxygen gas concentration in the exhaust gas.

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

(Incinerator)
The incinerator F, for example, refers to a combustion facility such as an urban waste incinerator, an industrial waste incinerator, a power generation boiler, a carbonization furnace, and a private factory. Generally, the exhaust gas discharged from the municipal waste incinerator has harmful acidity such as hydrogen chloride (HCl), sulfur oxide (SOx), and nitrogen oxide (NOx) depending on the type of waste to be incinerated. Gas and solid matter (hereinafter referred to as "flying ash") are included. Of these, sulfur oxides are the most abundant. The exhaust gas is not particularly limited in terms of its source and contained components, and refers to gas generated by incinerator of various wastes. The "acid gas" refers to a gas that dissolves in a solution and exhibits acidity, for example, a gas containing hydrogen chloride, sulfur oxide, or the like.

(Exhaust gas treatment section)
The exhaust gas treatment unit 11 applies and adds 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 to suppress the emission of harmful gas to the environment prior to the emission to the atmosphere. Therefore, the exhaust gas treatment unit 11 neutralizes the exhaust gas by adding a neutralizing agent as a treatment agent.
A neutralizing agent is used as the treating agent (hereinafter, may be referred to as "neutralizing agent"). Such a treatment agent can neutralize the acid gas contained in the exhaust gas by bringing it into contact with the exhaust gas.

The exhaust gas treatment unit 11 is not particularly limited as long as it can bring the exhaust gas into contact with a solid treatment agent to cause a reaction. Can be. Of these, as the 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 be used. Further, the exhaust gas treatment unit 11 can also be composed of a closed container additionally provided in the flue (gas flow path), various reaction containers, and the like.

It is not necessary to chemically neutralize the entire amount of the acidic gas contained in the exhaust gas in the exhaust gas treatment unit 11, and as the treatment agent is transferred together with the exhaust gas, the exhaust gas is discharged from the downstream side (for example, the exhaust gas treatment unit 11). It may be neutralized by the flue up to the recovery unit 16. For example, when slaked lime is used as a treatment agent, this can occur because slaked lime reacts slowly with acid gas.

In addition, the exhaust gas can be treated continuously. Further, for example, a closed container or various reaction containers for vapor phase reaction may be used, and the batch method may be used. In any case, the amount of exhaust gas to be treated is not particularly limited, and the amount of exhaust gas generated by incineration of waste can be appropriately designed.

(Treatment agent storage)
The treatment agent storage unit 14 stores the treatment agent for treating the exhaust gas. The exhaust gas treatment system 1 in the present embodiment manages the treatment agent stored in the storage unit 14. 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 and shape of the storage unit 14 are not particularly limited, and may be appropriately designed in consideration of the installation space, the operation plan of exhaust gas treatment, the amount of exhaust gas treated, the frequency of treating exhaust gas, the frequency of ordering treatment agents, and the like. can.

(Treatment agent addition control department)
The treatment agent addition control unit 13 has exhaust gas analysis units 131 and 132 arranged on both the upstream side and / or the downstream side of the exhaust gas treatment unit 11. The treatment agent addition management unit 13 analyzes the exhaust gas by the exhaust gas analysis units 131 and 132, calculates the addition amount of the treatment agent required for the treatment of the exhaust gas, and instructs the supply of the treatment agent in the calculated addition amount. .. In this way, the treatment agent addition control unit 13 processes according to the fluctuation amount of the analysis value according to the nature of the exhaust gas to be treated (for example, the concentration and flow rate of the acid gas), the size of the exhaust gas treatment unit 11, and the like. The amount of the agent added is varied. The "upstream side" and "downstream side" here mean upstream and downstream in the flow of exhaust gas.

The instruction regarding the amount of the treatment agent added, which is transmitted from the treatment agent addition control unit 13, is transmitted to the treatment agent supply unit 14 such as a quantitative feeder provided on the upstream side of the exhaust gas treatment unit 11, and processing is performed based on the instruction. The agent supply unit 14 can be operated to add a predetermined amount of the treatment agent to the exhaust gas treatment unit 11.

When the exhaust gas treatment unit 11 performs the treatment of the exhaust gas, the treatment agent addition control unit 13 treats the exhaust gas with a certain amount of the treatment agent per a certain amount (for example, a constant flow rate, a certain time, or one batch) of the exhaust gas. It is preferable to have an arithmetic circuit for calculating various numerical values by using the numerical values stored in the numerical values when each component such as sulfur oxide decreases with the number of treatments and the treatment time of the exhaust gas in the case of the above. The control method for arithmetic processing is a method of analyzing the acid gas in the exhaust gas and calculating the amount of treatment agent required to neutralize them (feedback control), or the acid gas in the exhaust gas after treatment. There is a method (feedback control) for calculating the required amount of the treatment agent based on the method.

(Exhaust gas analysis department)
The exhaust gas analysis units 131 and 132 analyze the properties of the exhaust gas before and after the addition of the treatment agent, respectively, and analyze the concentrations of hydrogen chloride (HCl), sulfur oxide (SOx), and nitrogen oxide (NOx) in the exhaust gas. be able to. The flow rate of the exhaust gas can also be analyzed. The processing agent addition management unit 13 manages the analysis values of the exhaust gas analysis units 131 and 132.
The exhaust gas analysis units 131 and 132 are preferably provided on the downstream side of the exhaust gas recovery unit 16. The upstream side of the exhaust gas recovery unit 16 may be used, but the upstream side of the exhaust gas recovery unit 16 has a large amount of fly ash, and the exhaust gas analysis unit 132 analyzes the exhaust gas obtained by filtering and recovering the fly ash to improve the analysis accuracy of the exhaust gas. Can be made to. For this reason, the exhaust gas analysis unit 132 analyzes the oxygen gas concentration instead of the sulfur oxide concentration, and when the oxygen gas concentration starts to decrease as a result of the analysis, a treatment agent is added according to the oxygen gas concentration. .. The oxygen gas concentration analysis method includes a zirconia method, a magnetic method, a laser spectroscopy method, and an electrode method. Any method can be used, but preferably the zirconia method is used.

In the zirconia method, porous platinum electrodes are attached to both sides of the zirconia element and heated, and when gases with different oxygen gas partial pressures are brought into contact with each surface, an oxygen concentration cell is generated. By the action of this battery, an electromotive force is generated between both electrodes, and the oxygen gas concentration can be analyzed. Further, by comparing the analysis results obtained from the exhaust gas analysis units 131 and 132 arranged on the upstream side and the downstream side of the exhaust gas treatment unit 11 with each other, the amount of the treatment agent required for neutralizing the exhaust gas can be more accurate. It can also be calculated in.

Further, in order to further improve the calculation accuracy of the amount of the treatment agent used, the amount of exhaust gas is analyzed from the exhaust gas flow meter 19. Since the amount of exhaust gas hardly changes before and after the addition of the treatment agent, the exhaust gas flow meter is arranged together with the exhaust gas analysis unit 132 in FIG. 1, but the position of the exhaust gas flow meter is not limited to this example. By analyzing the amount of exhaust gas, the absolute amount of acid gas contained in the exhaust gas can be calculated together with the analysis value of the analysis of the acid gas concentration, and the required mass of the treatment agent can be calculated more accurately. can.

(Treatment agent supply unit)
The treatment agent supply unit 14 supplies the treatment agent in the amount of the treatment agent instructed by the treatment agent addition control unit 13 from the supply unit 12 to the exhaust gas treatment unit 11.
The treatment agent supply unit 14 may have a configuration in which a predetermined amount of the treatment agent can be supplied from the treatment agent supply unit 12 to the exhaust gas treatment unit 11, and is not particularly limited. For example, a quantitative feeder, a pump, or a powder feeder may be used. Can be configured.

(Processing agent)
The treatment agent has the property of neutralizing the acid gas in the exhaust gas. The treatment agent may be in the form of a liquid or a powder (solid state), 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, and for example, calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate, calcium hydroxide-magnesium hydroxide, calcium oxide-magnesium oxide, carbon dioxide. Calcium-magnesium carbonate, sodium hydroxide, sodium hydrogen carbonate, sodium carbonate and the like can be used. One type of treatment agent may be used alone, or two or more types may be used in combination.

When a powdery treatment agent is used, the average particle size thereof is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 5 μm or more. When the average particle size of the treatment agent is 1 μm or more, it is possible to prevent an increase in the differential pressure in the exhaust gas recovery unit 16 on the downstream side and prevent an increase in the acid gas concentration in the exhaust gas due to a decrease in the recovery efficiency. The average particle size of the treatment agent is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. When the average particle size of the treatment agent is 50 μm or less, it is possible to secure a large specific surface area of the treatment agent that is sufficiently large for the exhaust gas to come into contact with the treatment agent.

(Exhaust gas recovery department)
The exhaust gas treatment system 1 is provided with an exhaust gas recovery unit 16 such as a bag filter 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. In the fly ash removed here, when a part of the treatment agent added to the exhaust gas treatment unit 11 is not used for the neutralization reaction of the exhaust gas treatment and remains unreacted, this unreacted treatment The agent is also included. In addition, sulfur oxides that have reacted with the treatment agent, unreacted hydrogen chloride (HCl), sulfur oxides (SOx), and nitrogen oxides (NOx) are also included. After a certain period of time, the fly ash collected in the exhaust gas recovery unit 16 is recovered and discharged to the outside.

(Supply meter)
The treatment agent addition control unit 13 may have a supply amount measuring 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 measuring meter measures the amount of the treatment agent supplied from the treatment agent supply unit 14 to the exhaust gas treatment unit 11.

(Exhaust gas treatment method)
The exhaust gas treatment method according to the present embodiment is arranged on at least one of the upstream side and the downstream side of the exhaust gas recovery unit 16 that separates the gas and the solid matter contained in the exhaust gas and recovers and removes the solid matter. The exhaust gas treatment unit 11 is based on the fluctuation amount of the oxygen gas concentration analyzed by the exhaust gas analysis units 131 and 132 of the treatment agent addition control unit 13 having the exhaust gas analysis units 131 and 132 for at least analyzing the oxygen gas concentration in the exhaust gas. The amount of the treatment agent added for treating the acidic gas contained in the exhaust gas to be treated in step 1 is calculated, and the treatment agent supply unit 14 is instructed to supply the calculated amount of the treatment agent, and the treatment of the instructed addition amount is performed. The agent is supplied from the treatment agent storage unit 12 to the exhaust gas treatment unit 11 to treat the acidic gas contained in the exhaust gas.

(Operation of exhaust gas treatment system)
Here, the operation of the exhaust gas treatment system 1 in the exhaust gas treatment method will be described.
When the exhaust gas is generated by incinerating waste in the incinerator F, it is treated, for example, through the following route. The exhaust gas generated in the incinerator F is cooled by passing through a flue and a temperature reducing tower (neither is shown), and fly ash is removed or recovered by the exhaust gas recovery unit 16. After that, it is transferred to the exhaust gas analysis unit 132 of the treatment agent addition control unit 13 via the exhaust gas recovery unit 16. After the exhaust gas analysis unit 132 analyzes the oxygen gas concentration in the exhaust gas, the amount required to process the sulfur oxide contained in the exhaust gas from the treatment agent addition control unit 13 according to the fluctuation amount of the oxygen gas concentration. Instructions are given to add the treatment agent. Sulfur oxides in the exhaust gas are neutralized in the exhaust gas treatment unit 11 with the treatment agent supplied from the treatment agent supply unit 12 according to the instruction from the treatment agent addition control unit 13. Next, the exhaust gas analysis unit 132 analyzes the oxygen gas concentration, the sulfur oxide concentration, and the like, confirms that the sulfur oxide concentration of the exhaust gas is equal to or less than the standard, and then discharges the exhaust gas into the atmosphere through the chimney 18. The fly ash removed by the exhaust gas recovery unit 16 is further fixed and removed from heavy metals and the like, and is subjected to a treatment such as landfill.

(Behavior of oxygen gas concentration)
In this embodiment, the exhaust gas analysis unit 132 analyzes the oxygen gas (O ₂ ) concentration in the exhaust gas. Conventionally, treatment with a treatment agent for an acid gas in an exhaust gas has analyzed the concentration of an acid gas for neutralization, for example, sulfur oxide (SO _{X) in the exhaust gas.} However, because it takes considerable time to in the exhaust gas analyzer 132 until the results by analyzing the acid gases (e.g. sulfur oxide SO _X) exits (e.g. over 4 minutes), the concentration of the analysis acid gas Even if an appropriate amount of treatment agent is added to the exhaust gas treatment unit to treat the exhaust gas based on the above, the concentration of acid gas contained in the treated exhaust gas may fluctuate at the time of adding the treatment agent. Therefore, it cannot be said that the amount of the added treatment agent is not always excessive or insufficient, the concentration of the acid gas cannot be stably suppressed to a low level, and the acid gas temporarily rises to a high concentration. There was a case.
Therefore, as a result of diligent studies by the present inventor, there is a correlation between the acid gas concentration and the oxygen gas concentration contained in the exhaust gas, and the acid gas concentration begins to increase and at the same time the oxygen gas concentration begins to decrease. I found that. In addition, in the analysis of oxygen gas in exhaust gas, the time from analysis to the result is shorter than half of the analysis time of acid gas (for example, about 2 minutes), so the oxygen gas concentration in exhaust gas When the oxygen gas concentration started to decrease, it was predicted that the acid gas would start to increase, and when the necessary treatment agent was immediately added to the exhaust gas treatment unit according to the rate of decrease in the oxygen gas concentration, the acid gas temporarily disappeared. It was clarified that the concentration of acid gas can be stably suppressed to a low level without increasing to a high concentration. Therefore, in the present invention, instead of using the analysis result of the sulfur oxide concentration in the exhaust gas, an appropriate amount is obtained when the oxygen gas concentration in the exhaust gas starts to decrease based on the analysis result of the oxygen gas concentration in the exhaust gas. By adding the treatment agent of the above to neutralize the sulfur oxides in the exhaust gas, the acid gas concentration is stably suppressed to a low level without temporarily rising and fluctuating to a high concentration. be able to.

The correlation between the oxygen gas concentration and the sulfur oxide concentration differs depending on the characteristics of the device of the exhaust gas treatment system, the size of the device, the state of the reaction in which the exhaust gas is generated, and the like. Therefore, by creating a calibration curve in advance to investigate the relationship between the oxygen gas concentration and the sulfur oxide concentration of each exhaust gas treatment system and then considering it together with the exhaust gas amount, the acidity contained in the exhaust gas is contained. The amount of treatment agent added required for gas treatment can be determined.

(Sulfur oxide concentration analysis time)
Further, the analysis of the sulfur oxide concentration was carried out by a method of obtaining the sulfur dioxide concentration by utilizing the light absorption in the infrared region of sulfur dioxide, which is the main component of the sulfur oxide. Specifically, the amount of infrared rays absorbed in the vicinity of 7.3 μm of sulfur dioxide was analyzed, and the concentration of sulfur dioxide contained in the exhaust gas was continuously analyzed. However, the current analysis of sulfur oxides, depending on the analytical principle, took several minutes to produce results, at least four minutes at present. Exhaust gas is flowing from the incinerator F to the chimney 18 through the exhaust gas recovery unit 11 according to the time. Therefore, the exhaust gas without the treatment agent was flowing into the atmosphere between the start of the analysis and the result.

(Analysis time of oxygen gas concentration)
Therefore, the exhaust gas treatment system 1 of the present embodiment does not analyze the sulfur oxide concentration in the exhaust gas, but focuses on the oxygen gas in the exhaust gas and analyzes and measures the oxygen gas concentration. The analysis / measurement method is an oxygen concentration meter using a zirconia method, which can be provided upstream or downstream of the exhaust gas analysis unit 132 of the exhaust gas treatment system 1 for analysis. Normally, in the oxygen gas concentration analysis, the zirconia method can be analyzed in 2 minutes, and the analysis can be performed in a shorter time than the sulfur oxide concentration analysis. Therefore, the analysis time of the oxygen concentration meter can be shortened after the exhaust gas reaches the exhaust gas analysis unit 132, so that the oxygen gas concentration is analyzed and the analysis value is output even on the downstream side of the exhaust gas recovery unit 16. Then, the treatment agent addition control unit 13 can issue an instruction to the treatment agent supply unit 12 in a short time, so that the treatment agent supply unit 12 supplies the treatment agent and the exhaust gas treatment unit 11 processes the treatment. This makes it possible to 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.

(Use of changes in oxygen gas concentration)
As described above, the time difference between the time required for the analysis of the oxygen gas concentration and the sulfur oxide concentration to be analyzed by the exhaust gas analysis unit 132 and the behavior of the change in the oxygen gas concentration and the sulfur oxide concentration in the exhaust gas treatment system 1 By using both of these, the exhaust gas that is not neutralized by the treatment agent can be greatly reduced, and the exhaust gas that is not neutralized and leaks into the atmosphere can be reduced. In this way, by minimizing the delay time that cannot correspond to the neutralization treatment of sulfur oxides, it was possible to suppress the leakage of exhaust gas containing sulfur oxides from the chimney.

(Stepwise addition of treatment agent)
In addition, the amount of acid gas to be treated per hour is calculated from the amount of exhaust gas and the concentration of sulfur oxides, and the amount of treatment agent required is multiplied by the amount of treatment agent considering the neutralization reaction to the unit amount of sulfur oxides. I was looking for. Then, the addition of the treatment agent to the exhaust gas was controlled by the feedforward control method or the feedback control method. Therefore, in the present embodiment, the logic for controlling the addition amount of the treatment agent is based on the numerical value of the change in the oxygen gas concentration analyzed by the exhaust gas analysis unit 132, as in the control method based on the analysis of the sulfur oxide concentration so far. Is incorporated into the treatment agent addition control unit 13 to control the treatment of sulfur oxides.

However, the change in oxygen gas concentration is slower than the change in sulfur oxide concentration. Further, although the change in the oxygen gas concentration indicates the start time of adding the treatment agent, the oxygen gas concentration and the sulfur oxide concentration do not completely correspond to each other. Therefore, it is preferable to change the addition amount of the treatment agent stepwise in response to the change in oxygen gas concentration, instead of completely responding to the change in oxygen gas concentration. For example, when the oxygen gas concentration decreases, the amount of the treatment agent is not determined according to the decrease, but a large amount is added even when the first treatment agent is added. Determine the amount to be added stepwise with respect to the oxygen gas concentration. After that, when the decreasing tendency of the oxygen gas concentration becomes small, 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 carried out in accordance with the oxygen gas concentration in the exhaust gas treatment system 1.

(Exhaust gas analysis department on the upstream side)
Further, as the analysis value of the oxygen gas concentration, the exhaust gas analysis unit 132 on the downstream side of the exhaust gas recovery unit 16 was used. It may be managed by 13. When the treatment agent supply unit 12 and the position where the exhaust gas is analyzed are closer in terms of distance and time, the treatment agent can be added quickly to the exhaust gas.

Hereinafter, the present invention will be described in more detail based on Examples. The present invention is not limited to these examples.

In order to neutralize the sulfur oxides in the exhaust gas and recover them in the exhaust gas recovery unit, the amount of sulfur oxides is usually analyzed after the exhaust gas recovery unit. For the control of sulfur oxides, a feedback control method such as PID is used based on the sulfur analysis result, and the amount of the treatment agent added is controlled. So far, in many cases, the sulfur oxide concentration has been analyzed on the downstream side of the exhaust gas recovery unit, and the treatment agent has been provided on the upstream side of the exhaust gas recovery unit based on the analysis result. In order to compare the effects of the analysis of oxygen gas concentration and sulfur oxide concentration on the downstream side of the exhaust gas recovery section, the transition of sulfur oxide concentration and the consumption of slaked lime, which is a treatment agent, when each concentration analysis was performed. The situation was analyzed.

(Comparative Example 1)
As Comparative Example 1, in a factory equipped with the above-mentioned exhaust gas treatment system, the sulfur oxide concentration was analyzed by the same exhaust gas treatment method as before, and the exhaust gas treatment was carried out.
Here, regardless of the change in the oxygen gas concentration, the change in the sulfur oxide concentration was caught and the addition of the treatment agent was started. At this time, the transition of the sulfur oxide concentration and the time of addition of the treatment agent is shown in FIG. The sulfur oxide concentration is analyzed by a sulfur oxide analyzer using an infrared method, and the response time after the exhaust gas reaches the analyzer is several minutes, specifically, about 240 seconds until a 90% response. On the other hand, the oxygen gas concentration can be analyzed by the zirconia method in about 120 seconds until a 90% response.

Exhaust gas is passed through the exhaust gas treatment section of the exhaust gas treatment system shown in FIG. 1, and as shown in FIG. 2, when the _{concentration of sulfur dioxide (SO 2} ), which is a sulfur oxide, begins to increase, limestone, which is a treatment agent, is added. bottom. However, at the position of the exhaust gas analysis section on the downstream side of the exhaust gas recovery section, the SO ₂ concentration began to increase sharply. _{After that, after the SO 2} concentration reaches its peak when about 1 to 2 minutes have passed, the effect of adding the treatment agent 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 unit does not sufficiently treat the _{SO 2 concentration contained in the exhaust gas.} When the exhaust gas mixed with the treatment agent came to the exhaust gas analysis section, the exhaust gas containing a large amount of sulfur oxides that had not been treated with the treatment agent was discharged and leaked into the atmosphere through the chimney within 1 to 2 minutes. Become.

(Example 1)
Next, the change in oxygen gas (O ₂ ) concentration was detected, 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.
_{In Example 1, after analyzing the SO 2} concentration and the O ₂ concentration contained in the exhaust gas in advance and creating a calibration curve, a program for gradually changing the amount of the treatment agent added is introduced as follows. The conventional control method and the method that adopts a value with a high addition amount in this program are adopted. Table 1 shows the relationship between the oxygen gas concentration (%) and the amount of slaked lime to be added (kg / h).

As shown in FIG. 3, 1 minute after the exhaust gas was allowed to flow, when the oxygen concentration became lower than 10%, slaked lime as a treatment agent was added. However, exhaust gas having a high sulfur oxide concentration flowed into the exhaust gas analysis unit on the downstream side of the exhaust gas recovery unit two minutes after the oxygen gas concentration decreased. Therefore, 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 neutralized is discharged to the outside. However, the addition of slaked lime started about 1 minute before the increase in sulfur oxide concentration. Therefore, the peak of the sulfur oxide concentration is very low as compared with Comparative Example 1. In addition, instead of continuously changing the amount of slaked lime added to the change in oxygen gas concentration, by changing the amount of slaked lime added step by step according to the change in oxygen gas concentration, a large amount of slaked lime is consumed, but sulfur oxides. However, untreated sulfur oxides are prevented from being generated. It is shown that these treatments cause very little emission / leakage to the outside of the exhaust gas containing a large amount of sulfur oxides to which the treatment agent has not been added.

However, in Example 1, since slaked lime was added earlier than in Comparative Example 1, it can be seen that the addition time was long and the amount of slaked lime added was large. However, it can be seen from this that the neutralization treatment of sulfur oxides in the exhaust gas has been sufficiently carried out.

As is clear from the slaked lime shown in FIGS. 2 and 3, in an actual exhaust gas treatment system, a constant amount of treatment agent is always added regardless of the oxygen and sulfur oxide concentrations. Here, "addition of a treatment agent" means adding a large amount of treatment agent from a normal addition.

1 Exhaust gas treatment system 11 Exhaust gas treatment unit 12 Treatment agent storage unit 13 Treatment agent addition control unit 131, 132 Exhaust gas analysis unit 14 Exhaust gas supply unit 16 Exhaust gas recovery unit 17 Exhaust gas flow meter 18 Chimney F incinerator

In order to solve the above problems, the gist structure of the present invention is as follows.
(1) An exhaust gas treatment unit for treating exhaust gas, an exhaust gas recovery unit for separating and removing solids from the exhaust gas treated by the exhaust gas treatment unit, and a treatment agent storage unit for storing a treatment agent for treating the exhaust gas. And, which is arranged on the downstream side of the exhaust gas recovery unit and has an exhaust gas analysis unit that at least analyzes the oxygen gas concentration in the exhaust gas, the exhaust gas analysis unit analyzes the fluctuation amount of the oxygen gas concentration. The treatment agent addition management unit that calculates the addition amount of the treatment agent required for the treatment of the acidic gas contained in the exhaust gas to be treated by the exhaust gas treatment unit and instructs the supply of the treatment agent in the calculated addition amount, and the treatment agent. An exhaust gas treatment system including a treatment agent supply unit that supplies a treatment agent in an amount of addition instructed by the addition control unit from the treatment agent storage unit to the exhaust gas treatment unit.
(2) The exhaust gas analysis unit analyzes the oxygen gas concentration in the exhaust gas with an oxygen concentration meter using a zirconia method, and the treatment agent addition control unit instructs the supply of the treatment agent when the oxygen gas concentration starts to decrease. The exhaust gas treatment system according to (1) , wherein the exhaust gas treatment unit treats an exhaust gas containing an acid gas with a treatment agent.
(3) The exhaust gas treatment system according to (1) or (2), wherein the treatment agent has a property of neutralizing an 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) A process having an exhaust gas analysis unit that is arranged on the downstream side of the exhaust gas recovery unit that separates the gas and solid matter contained in the exhaust gas and collects and removes the solid matter, and at least analyzes the oxygen gas concentration in the exhaust gas. Based on the fluctuation amount of the oxygen gas concentration analyzed by the exhaust gas analysis unit of the agent addition control unit, the amount of the treatment agent added for treating the acidic gas contained in the exhaust gas to be treated by the exhaust gas treatment unit is calculated. , The calculated amount of the treatment agent is instructed to be supplied to the treatment agent supply unit, and the instructed amount of the treatment agent is supplied from the treatment agent storage unit to the exhaust gas treatment unit to supply the acidity contained in the exhaust gas. An exhaust gas treatment method that treats gas.

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

(Treatment agent storage)
The treatment agent storage unit 12 stores the treatment agent for treating the exhaust gas. The exhaust gas treatment system 1 in the present embodiment manages the treatment agent stored in the storage unit 12. The storage unit 12 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 and shape of the storage unit 12 are not particularly limited, and may be appropriately designed in consideration of the installation space, the operation plan of exhaust gas treatment, the amount of exhaust gas treated, the frequency of treating exhaust gas, the frequency of ordering treatment agents, and the like. can

(Treatment agent supply unit)
The treatment agent supply unit 14 supplies the treatment agent in the amount of the treatment agent instructed by the treatment agent addition control unit 13 from the supply unit 12 to the exhaust gas treatment unit 11.
The treatment agent supply unit 14 may have a configuration in which a predetermined amount of the treatment agent can be supplied from the treatment agent storage unit 12 to the exhaust gas treatment unit 11, and is not particularly limited. For example, a quantitative feeder, a pump, or a powder feeder may be used. Can be configured.

(Operation of exhaust gas treatment system)
Here, the operation of the exhaust gas treatment system 1 in the exhaust gas treatment method will be described.
When the exhaust gas is generated by incinerating waste in the incinerator F, it is treated, for example, through the following route. The exhaust gas generated in the incinerator F is cooled by passing through a flue and a temperature reducing tower (neither is shown), and fly ash is removed or recovered by the exhaust gas recovery unit 16. After that, it is transferred to the exhaust gas analysis unit 132 of the treatment agent addition control unit 13 via the exhaust gas recovery unit 16. After the exhaust gas analysis unit 132 analyzes the oxygen gas concentration in the exhaust gas, the amount required to process the sulfur oxide contained in the exhaust gas from the treatment agent addition control unit 13 according to the fluctuation amount of the oxygen gas concentration. Instructions are given to add the treatment agent. Sulfur oxides in the exhaust gas are neutralized in the exhaust gas treatment unit 11 with the treatment agent supplied from the treatment agent supply unit 14 according to the instruction from the treatment agent addition control unit 13. Next, the exhaust gas analysis unit 132 analyzes the oxygen gas concentration, the sulfur oxide concentration, and the like, confirms that the sulfur oxide concentration of the exhaust gas is equal to or less than the standard, and then discharges the exhaust gas into the atmosphere through the chimney 18. The fly ash removed by the exhaust gas recovery unit 16 is further fixed and removed from heavy metals and the like, and is subjected to a treatment such as landfill.

(Analysis time of oxygen gas concentration)
Therefore, the exhaust gas treatment system 1 of the present embodiment does not analyze the sulfur oxide concentration in the exhaust gas, but focuses on the oxygen gas in the exhaust gas and analyzes and measures the oxygen gas concentration. The analysis / measurement method is an oxygen concentration meter using a zirconia method, and can be provided upstream or downstream of the exhaust gas analysis unit 132 of the exhaust gas treatment system 1 for analysis. Normally, in the oxygen gas concentration analysis, the zirconia method can be analyzed in 2 minutes, and the analysis can be performed in a shorter time than the sulfur oxide concentration analysis. Therefore, the analysis time of the oxygen concentration meter can be shortened after the exhaust gas reaches the exhaust gas analysis unit 132, so that the oxygen gas concentration is analyzed and the analysis value is output even on the downstream side of the exhaust gas recovery unit 16. Then, the treatment agent addition control unit 13 can issue an instruction to the treatment agent supply unit 14 in a short time, so that the treatment agent supply unit 14 supplies the treatment agent and the exhaust gas treatment unit 11 processes the treatment. This makes it possible to 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.

(Exhaust gas analysis department on the upstream side)
Further, as the analysis value of the oxygen gas concentration, the exhaust gas analysis unit 132 on the downstream side of the exhaust gas recovery unit 16 was used. It may be managed by 13. When the treatment agent supply unit 14 and the position where the exhaust gas is analyzed are closer in distance and time, the treatment agent can be added quickly to the exhaust gas.

Claims (5)

Exhaust gas treatment unit for treating exhaust gas and
An exhaust gas recovery unit that separates and removes solids from the exhaust gas treated by the exhaust gas treatment unit,
A treatment agent storage unit that stores the treatment agent for treating the exhaust gas,
The oxygen gas is arranged on at least one of the upstream side and the downstream side of the exhaust gas recovery unit, has an exhaust gas analysis unit that at least analyzes the oxygen gas concentration in the exhaust gas, and is analyzed by the exhaust gas analysis unit. Based on the amount of fluctuation in concentration, the amount of the treatment agent added for treating the acid gas contained in the exhaust gas to be treated by the exhaust gas treatment unit is calculated, and the treatment agent instructing the supply of the calculated addition amount of the treatment agent. Addition control department and
A treatment agent supply unit that supplies an amount of treatment agent instructed by the treatment agent addition control unit from the treatment agent storage unit to the exhaust gas treatment unit.
Exhaust gas treatment system equipped with. 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 2, wherein the treatment agent has a property of neutralizing an acid gas in the exhaust gas. The exhaust gas treatment system according to any one of claims 1 to 3, wherein the acid gas contains sulfur oxides. It is arranged on at least one of the upstream side and the downstream side of the exhaust gas recovery unit that separates the gas and the solid matter contained in the exhaust gas and recovers and removes the solid matter, and at least analyzes the oxygen gas concentration in the exhaust gas. It is necessary to treat the acidic gas contained in the exhaust gas to be treated by the exhaust gas treatment unit based on the fluctuation amount of the oxygen gas concentration analyzed by the exhaust gas analysis unit of the treatment agent addition control unit having the exhaust gas analysis unit. The amount of the treatment agent added is calculated, the supply of the calculated amount of the treatment agent is instructed to the treatment agent supply unit, and the specified amount of the treatment agent is supplied from the treatment agent storage unit to the exhaust gas treatment unit. , An exhaust gas treatment method for treating an acidic gas contained in the exhaust gas.

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