KR20220162753A - Exhaust gas treatment system and exhaust gas treatment method - Google Patents

Abstract

The present invention is an exhaust gas capable of predicting at an early stage the timing at which the acid gas concentration starts to increase due to the oxygen concentration fluctuation linked to the acid gas concentration fluctuation in the exhaust gas, and adding an appropriate amount of the treatment agent at an appropriate timing. A gas treatment system is provided. Exhaust gas analysis units 131 and 132 disposed on at least one of the upstream side and the downstream side of the exhaust gas recovery unit 16 and at least analyzing the oxygen gas concentration in the exhaust gas are provided, and the exhaust gas analyzer ( 132), based on the amount of change in oxygen gas concentration analyzed, the addition amount of the processing agent required for the treatment of the acid gas contained in the exhaust gas treated by the exhaust gas processing unit 11 is calculated, and the supply of the processing agent of the calculated addition amount is instructed and a processing agent supply unit 14 for supplying the processing agent in the amount of addition indicated by the processing agent addition management unit 13 and the processing agent addition management unit 13 for processing.

Description

Exhaust gas treatment system and exhaust gas treatment method

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 reduced in temperature in a temperature reduction tower, and then the exhaust gas is passed through a filter type dust collector to remove solids and acid gases in the exhaust gas, and then discharged into the atmosphere from the chimney have.

However, acid gas cannot be completely removed only by passing the exhaust gas through a filtering dust collector. At present, many incineration plants in Japan adopt a dry exhaust gas treatment method in which slaked lime is continuously blown into the flue from the thermal tower to the filter type dust collector to neutralize and remove the acid gas. have. For example, an exhaust gas treatment method and exhaust gas in which a chemical for removing acid gas in exhaust gas by neutralization is injected into cloth such as a non-woven fabric of a filter type dust collector that purifies exhaust gas discharged from a gas generating source such as an incinerator. Gas treatment devices are commonly used. However, treatment of the exhaust gas is insufficient, and acidic gases such as sulfur oxides are leaking. For this reason, the following methods have been proposed in order to remove acidic gases in exhaust gas.

In Patent Document 1, when the measured value of the acid gas concentration in the exhaust gas at the outlet side or the inlet side of the filtering type dust collector exceeds a predetermined value and the exceeded state continues for a predetermined time, the measured value Disclosed is a method for treating exhaust gas from a waste incinerator in which a set amount of sodium-based chemical is supplied to an inlet side of a filtering dust collector. Further, in Patent Document 2, an upstream acid gas concentration meter for measuring the acid gas concentration of the exhaust gas and a downstream acid gas concentration meter for measuring the acid gas concentration of the exhaust gas downstream of the dust collector are provided, and the reaction unit and the dust collector are provided. Disclosed is an exhaust gas treatment device in which a powder neutralizing agent is supplied to the exhaust gas between the devices to neutralize the remainder of the acid gas. In Patent Document 3, the first order, which is the difference between the N-hour moving average value of the SOx concentration N hours ago and the N-hour moving average value of the SOx concentration at the present time, and the calculation of the addition amount of the desulfurization agent N hours ago A desulfurization agent addition control method for calculating a current control value based on a used control value and determining an addition amount of a desulfurization agent based on the current control value is disclosed.

However, Patent Literature 1 to Patent Literature 3 all analyze sulfur oxides (SOx) in acid gas, and since a considerable amount of time is required until the result of sulfur oxide analysis is obtained, the concentration of sulfur oxides in exhaust gas is significantly increased. Even if it is increased, because of the time lag until the analysis result is obtained, the added amount of the treatment agent necessary to treat the increased sulfur oxides cannot be immediately added, and as a result, sulfur oxides that have not been sufficiently treated may be discharged into the atmosphere. For this reason, it is necessary to add a treatment agent for treating sulfur oxides in an amount larger than the required addition amount to some extent, but adding a treatment agent in an amount larger than the required addition amount causes fly ash and the like to be separated and removed in the exhaust gas recovery unit. Since the unreacted treatment agent is included in the solids containing the solids, the amount of recovery of the solids increases. In the case of disposing of such increased solids by landfill or the like, it is necessary to provide an extra accommodation space in the landfill, which is undesirable.

Patent Document 1: Japanese Unexamined Patent Publication No. 2019-070471 Patent Document 2: Japanese Unexamined Patent Publication No. 2017-124348 Patent Document 3: Japanese Unexamined Patent Publication No. 2017-176922

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

In order to solve the above problems, the summary of the present invention is as follows.

(1) an exhaust gas processing unit for processing exhaust gas, an exhaust gas recovery unit for separating and removing solids from the exhaust gas processed by the exhaust gas processing unit, and a processing agent storage unit for storing a processing agent for processing the exhaust gas; , an exhaust gas analyzer disposed on at least one of an upstream side and a downstream side of the exhaust gas recovery unit and analyzing an oxygen gas concentration in at least the exhaust gas, the oxygen gas concentration analyzed by the exhaust gas analyzer A processing agent addition management unit that calculates an addition amount of a processing agent required for processing the acid gas contained in the exhaust gas treated by the exhaust gas processing unit based on the variation amount of and instructs supply of the processing agent of the calculated addition amount; and An exhaust gas treatment system comprising: a treatment agent supply unit for supplying a treatment agent of an added amount instructed by a management unit to the exhaust gas treatment unit from the treatment agent storage unit.

(2) The exhaust gas treatment system according to (1), wherein the exhaust gas analyzer is disposed downstream 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 acid gas in the exhaust gas.

(4) The exhaust gas treatment system described in any one of (1) to (3), wherein the acid gas is a sulfur oxide gas.

(5) Exhaust gas that is disposed on at least one side of the upstream side and the downstream side of an exhaust gas recovery unit that separates gas and solids contained in exhaust gas and recovers and removes solids, and analyzes the concentration of oxygen gas in at least the exhaust gas. Based on the amount of change in the oxygen gas concentration analyzed by the exhaust gas analysis unit of the processing agent addition management unit having an analyzer, the addition amount of the processing agent required for processing the acid gas contained in the exhaust gas processed by the exhaust gas processing unit is calculated and instructing the processing agent supply unit to supply the calculated addition amount of the processing agent, supplying the indicated amount of processing agent from the processing agent storage unit to the exhaust gas processing unit, and treating the acid 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 emitted into the atmosphere can be stably suppressed to a low level without a sudden increase, and also separated and removed in the exhaust gas recovery unit. The amount of the unreacted treatment agent in the solid material to be reduced.

1 is a diagram showing the configuration of an exhaust gas treatment system for implementing the exhaust gas treatment method of the present invention.
Fig. 2 is a graph showing transitions of SO ₂ concentration, O ₂ concentration, and slaked lime input amount when a treatment agent is added, based on analysis results of the SO ₂ concentration contained in exhaust gas.
Fig. 3 is a graph showing transitions of SO ₂ concentration, O ₂ concentration, and slaked lime input amount when a treatment agent is added, based on the analysis result of the O ₂ concentration contained in the exhaust gas.

EMBODIMENT OF THE INVENTION Embodiment of this invention is described below. The following description is an example of embodiment in this invention, and it does not limit the claim.

(exhaust gas treatment system)

An exhaust gas processing system 1 according to the present embodiment includes an exhaust gas processing unit 11 for processing exhaust gas, and an exhaust gas recovery unit for separating and recovering solid content from exhaust gas processed by the exhaust gas processing unit 11. 16, the processing agent storage unit 12 for storing a processing agent for processing exhaust gas, and the exhaust gas recovery unit 16 are disposed on at least one side of the upstream side and the downstream side, and at least exhaust the exhaust gas. Equipped with exhaust gas analyzers 131 and 132 that analyze the concentration of oxygen gas (O ₂ ) in the gas, and based on the variation in the oxygen gas concentration analyzed by the exhaust gas analyzers 131 and 132, the exhaust gas processing unit The processing agent addition management unit 13 which calculates the addition amount of the processing agent required for the treatment of the acid gas contained in the exhaust gas to be treated in (11) and instructs the supply of the processing agent of the calculated amount added, and the processing agent addition management unit 13 instructs An exhaust gas treatment system having a treatment agent supply unit (14) for supplying a treatment agent of the added amount from a treatment agent storage unit (12) to an exhaust gas treatment unit (11). In the exhaust gas treatment system 1, exhaust gas analyzers 131 and 132 for analyzing the concentration of oxygen gas in the exhaust gas are also disposed.

(Configuration of Exhaust Gas Treatment System)

1 is a diagram showing the configuration of an exhaust gas treatment system for implementing the exhaust gas treatment method of the present invention. In Fig. 1, among the lines connecting each block, the solid line represents the flow of objects, and the dotted line represents the flow of information.

The processing agent exhaust gas processing system 1 according to the present embodiment includes an incinerator F, an exhaust gas processing unit 11, a processing agent supply unit 12, a processing agent storage unit 14, and an exhaust gas analyzer 131, 132 It is constituted centering on the processing agent addition management unit 13 including a ) and the exhaust gas recovery unit 16, and a flow meter 17 and a chimney 18 are installed in addition to this. The configuration of the exhaust gas treatment system 1 will be described in detail below.

(incinerator)

The incinerator F refers to a combustion facility such as a municipal waste incinerator, an industrial waste incinerator, a power generation boiler, a carbonization furnace, or a private factory, for example. In general, exhaust gas discharged from municipal waste incinerators includes harmful acid gases such as hydrogen chloride (HCl), sulfur oxides (SOx), and nitrogen oxides (NOx), solids (hereinafter referred to as "fly ash") depending on the type of garbage to be incinerated. described) are included. Among them, sulfur oxides are the most abundant. Exhaust gas is not particularly limited in terms of its source or content, and refers to gas generated by incineration of various wastes. "Acid gas" refers to a gas that is dissolved in a solution and exhibits acidity, and refers to a gas containing, for example, hydrogen chloride or sulfur oxides.

(exhaust gas processing unit)

The exhaust gas processing unit 11 performs input/adding processing of a processing agent to exhaust gas. Since the exhaust gas is an acidic gas containing sulfur oxides, it is necessary to neutralize the acidic gas before discharging it into the atmosphere to suppress the emission of harmful gases to the environment. Therefore, in the exhaust gas treatment unit 11, a neutralizer is added as a treatment agent to the exhaust gas to neutralize it.

A neutralizing agent is used as the processing agent (hereinafter sometimes referred to as "neutralizing agent"). Such a treatment agent can neutralize acidic gas contained in exhaust gas by bringing it into contact with exhaust gas.

The exhaust gas processing unit 11 is not particularly limited as long as it can bring the exhaust gas and the solid processing agent into contact and react, and for example, a part of the flue (gas flow path), etc. can be done with 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. In addition, the exhaust gas processing unit 11 may be configured as a closed vessel additionally installed in a flue (gas flow path), various reaction vessels, and the like.

In addition, it is not necessary to chemically neutralize the entire acid gas contained in the exhaust gas in the exhaust gas processing unit 11, and as the processing agent is transferred together with the exhaust gas, the acid gas contained in the exhaust gas is transferred to the downstream side (for example, the exhaust gas processing unit 11). flue from to the exhaust gas recovery section 16). For example, when slaked lime is used as a treatment agent, since slaked lime reacts slowly with acid gas, it can be neutralized as described above.

In addition, the treatment of exhaust gas can be carried out continuously. Alternatively, it may be carried out in a batch manner, for example, using a closed container or various reaction containers for gas phase reactions. In either case, the processing amount of exhaust gas is not particularly limited, and can be appropriately designed in consideration of the amount of exhaust gas generated by incineration of waste.

(Treatment agent storage unit)

The treatment agent storage unit 14 stores a treatment agent for treating exhaust gas. In the exhaust gas processing system 1 in this embodiment, the processing agent stored in the processing agent storage unit 14 is managed. The processing agent storage unit 14 is not particularly limited as long as it can store the processing agent, but, for example, a storage tank or a silo can be used. The capacity or shape of the processing agent storage unit 14 is not particularly limited, and is appropriately designed in consideration of the installation space, the exhaust gas treatment operation plan, the exhaust gas processing amount, the exhaust gas processing frequency, the processing agent order frequency, and the like. can do.

(Treatment agent addition management department)

The processing agent addition management unit 13 includes an exhaust gas analyzer 131 and an exhaust gas analyzer 132 disposed on both or either one of the upstream side and the downstream side of the exhaust gas processing unit 11 . The processing agent addition management unit 13 analyzes the exhaust gas by the exhaust gas analyzers 131 and 132, calculates the amount of the processing agent required for processing the exhaust gas, and instructs supply of the processing agent of the calculated amount. In this way, the treatment agent addition management unit 13 responds to the variation of the analysis value according to the nature of the exhaust gas to be treated (eg, the concentration and flow rate of acid gas), the size of the exhaust gas treatment unit 11, and the like, change the amount added. In addition, "upstream side" and "downstream side" here refer to upstream and downstream in the flow of exhaust gas.

In addition, the instruction regarding the addition amount of the processing agent transmitted from the processing agent addition management unit 13 is transmitted to the processing agent supply unit 14, such as a fixed-quantity feeder installed upstream of the exhaust gas processing unit 11, for example. Based on the instructions, the treatment agent supply unit 14 is operated to add a predetermined amount of the treatment agent to the exhaust gas treatment unit 11 .

When the processing agent addition management unit 13 processes the exhaust gas in the exhaust gas processing unit 11, a certain amount (for example, a constant flow rate, a constant time, or one batch) of exhaust gas is constant. It is preferable to provide an arithmetic circuit that calculates various numerical values using numerical values stored at the time of reduction of each component such as sulfur oxides with respect to the number of times of treatment of exhaust gas and the treatment time in the case of treatment with an additive amount of the treatment agent. . The control method for calculating and processing is a method of analyzing the acid gas in the exhaust gas and calculating the amount of the processing agent necessary to neutralize it (feed forward control), or calculating the amount of the processing agent required based on the acid gas in the exhaust gas after the treatment There is a way (feedback control).

(Exhaust gas analysis part)

The exhaust gas analyzers 131 and 132 analyze the properties of the exhaust gas before and after adding the treatment agent, respectively, and can analyze the concentrations of hydrogen chloride (HCl), sulfur oxides (SOx), and nitrogen oxides (NOx) in the exhaust gas. have. In addition, the flow rate of the exhaust gas can be analyzed. The processing agent addition management unit 13 manages the analysis values of the exhaust gas analyzers 131 and 132 .

The exhaust gas analyzers 131 and 132 are preferably installed downstream of the exhaust gas recovery unit 16 . It may be on the upstream side of the exhaust gas recovery unit 16, but there are many fly ash on the upstream side of the exhaust gas recovery unit 16. can improve the accuracy of analysis. From this fact, the exhaust gas analyzer 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 corresponding to the oxygen gas concentration. There are zirconia method, magnetic method, laser spectroscopy method, and electrode method for analyzing the oxygen gas concentration. Although either method can be used, the zirconia method is preferably used.

In the zirconia method, when porous platinum electrodes are attached to both surfaces of a zirconia element and heated, and gases having different partial pressures of oxygen gas are brought into contact with each surface, an oxygen-rich battery is generated. Electromotive force is generated between both electrodes by the action of this battery, and the oxygen gas concentration can be analyzed. In addition, by comparing the analysis results obtained from the exhaust gas analyzer 131 and the exhaust gas analyzer 132 disposed upstream and downstream of the exhaust gas processor 11, respectively, the amount of the treatment agent required for neutralization of the exhaust gas can be calculated more accurately.

In addition, in order to further increase the calculation accuracy of the amount of treatment agent used, the amount of exhaust gas is analyzed by the exhaust gas flow meter 19. Also, since the amount of exhaust gas hardly changes before and after adding the treatment agent, the exhaust gas flow meter is arranged together with the exhaust gas analyzer 132 in FIG. 1, but the position of the exhaust gas flow meter is not limited thereto. By analyzing the exhaust gas amount, the absolute amount of the acid gas contained in the exhaust gas can be calculated together with the analysis value obtained by analyzing the acid gas concentration, so that the mass of the processing agent required can be calculated with higher accuracy.

(Treatment agent supply unit)

The processing agent supply unit 14 supplies the processing agent in the amount of addition instructed by the processing agent addition management unit 13 from the processing agent supply unit 12 to the exhaust gas processing unit 11 .

The treatment agent supply unit 14 may be configured to supply a predetermined amount of the treatment agent from the treatment agent supply unit 12 to the exhaust gas treatment unit 11, and is not particularly limited. have.

(treatment agent)

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

The treatment agent is not particularly limited, and examples thereof include calcium hydroxide, calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate, calcium hydroxide-magnesium hydroxide, calcium oxide-magnesium oxide, calcium carbonate-magnesium carbonate, sodium hydroxide, and carbonic acid. Sodium hydrogen, sodium carbonate, etc. can be used. A processing agent may be used individually by 1 type, and may use 2 or more types together.

In the case of using a powdery substance as the treatment agent, the average particle size thereof is preferably 1 µm or larger, more preferably 2 µm or larger, and still more preferably 5 µm or larger. By setting the average particle diameter of the processing agent to be 1 μm or more, it is possible to prevent an increase in differential pressure in the exhaust gas recovery section 16 on the downstream side and an increase in the acid gas concentration in the exhaust gas due to a decrease in recovery efficiency. . Moreover, as an average particle diameter of a processing agent, it is preferable that it is 50 micrometers or less, it is more preferable that it is 40 micrometers or less, and it is more preferable that it is 30 micrometers or less. By setting the average particle size of the processing agent to 50 µm or less, a processing agent having a large specific surface area sufficient for exhaust gas to contact can be secured.

(exhaust gas recovery part)

In the exhaust gas treatment system 1, an exhaust gas recovery unit 16 such as a bag filter is installed on the downstream side of the exhaust gas processing unit 11. The exhaust gas recovery unit 16 removes fly ash, which is a solid substance, contained in the exhaust gas. In the case where a part of the treatment agent added to the exhaust gas treatment unit 11 remains unreacted without being used for the neutralization reaction of the exhaust gas treatment, the fly ash removed here includes the unreacted treatment agent. In addition, sulfur oxides 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 has elapsed, the fly ash collected in the exhaust gas recovery unit 16 is collected and discharged to the outside.

(supply amount measuring system)

The processing agent addition management unit 13 may be equipped with a supply amount measuring system (not shown in the drawing) on the downstream side of the processing agent supply unit 14 and upstream of the exhaust gas processing unit 11 . The supply amount measurement system measures the amount of the processing agent supplied to the exhaust gas processing unit 11 from the processing agent supply unit 14 .

(Exhaust gas treatment method)

The exhaust gas treatment method according to the present embodiment is disposed on at least one of the upstream side and the downstream side of the exhaust gas recovery unit 16 that separates gas and solids contained in the exhaust gas and recovers and removes the solids, and at least Based on the variation in the oxygen gas concentration analyzed by the exhaust gas analyzers 131 and 132 of the treatment agent addition management unit 13 having the exhaust gas analyzers 131 and 132 for analyzing the oxygen gas concentration in the exhaust gas, The addition amount of the processing agent required for the treatment of the acid gas contained in the exhaust gas treated by the exhaust gas processing unit 11 is calculated, the supply of the processing agent of the calculated amount added is instructed to the processing agent supply unit 14, and the processing agent of the indicated addition amount is supplied. It is supplied from the processing agent storage part 12 to the exhaust gas processing part 11, and acidic gas contained in exhaust gas is processed.

(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.

When exhaust gas is generated by incinerating waste in the incinerator F, it is treated through the following path, for example. Exhaust gas generated in the incinerator F is cooled by passing through a flue and a temperature reduction tower (both not shown in the figure), and fly ash is removed or recovered in the exhaust gas recovery unit 16 . After that, it is transferred to the exhaust gas analyzer 132 of the processing agent addition management unit 13 via the exhaust gas recovery unit 16 . After the oxygen gas concentration in the exhaust gas is analyzed by the exhaust gas analyzer 132, the treatment agent addition management unit 13 responds to the amount of change in the oxygen gas concentration, and the treatment agent in an amount necessary to treat sulfur oxides contained in the exhaust gas. An instruction to add is transmitted. In the exhaust gas processing unit 11, sulfur oxides in the exhaust gas are neutralized by the processing agent supplied from the processing agent supply unit 12 according to the instructions from the processing agent addition management unit 13. Subsequently, the exhaust gas analyzer 132 analyzes the concentration of oxygen gas or the concentration of sulfur oxides, etc., and after confirming that the concentration of sulfur oxides in the exhaust gas is below the standard, it is discharged into the atmosphere through the chimney 18. In addition, the fly ash removed from the exhaust gas recovery unit 16 is further processed, such as fixing and removing heavy metals and landfilling.

(Behavior of Oxygen Gas Concentration)

In this embodiment, the exhaust gas analyzer 132 analyzes the concentration of oxygen gas (O ₂ ) in the exhaust gas. Conventionally, in the treatment of acid gas in exhaust gas with a treatment agent, the concentration of acid gas, eg, sulfur oxides (SO _X ), which is the target of neutralization, in the exhaust gas was analyzed. However, since the exhaust gas analyzer 132 analyzes the acid gas (eg, sulfur oxides (SO _X )) and takes a considerable amount of time (eg, 4 minutes or more) until the result comes out, the analysis result Even if the exhaust gas is treated by adding an appropriate amount of the treatment agent to the exhaust gas treatment unit based on the concentration of the phosphorus acid gas, there is a possibility that the concentration of the acid gas contained in the exhaust gas to be treated has fluctuated at the time of adding the treatment agent. However, it cannot be said that the amount of the treatment agent added was not necessarily added without excess or deficiency, and the concentration of the acid gas could not be stably suppressed to a low level, so there was a case where the acid gas temporarily fluctuated to a high concentration.

Then, as a result of repeated studies by the present inventors, it was found that there is a correlation between the acid gas concentration and the oxygen gas concentration contained in the exhaust gas, and that the acid gas concentration starts to increase and the oxygen gas concentration starts to decrease at the same time. In addition, in the analysis of oxygen gas in exhaust gas, since the time from the analysis to the output of the result is shorter than the acid gas analysis time by half or less (for example, about 2 minutes), the oxygen gas concentration in the exhaust gas , it is predicted that acid gas starts to rise when the oxygen gas concentration starts to decrease, and as a result of adding the necessary treatment agent to the exhaust gas treatment unit according to the rate of decrease in the oxygen gas concentration, the acid gas temporarily rises to a high concentration. It has been found that the concentration of acid gas can be stably suppressed to a low level without From this fact, in the present invention, based on the analysis result of the oxygen gas concentration in the exhaust gas instead of using the analysis result of the sulfur oxide concentration in the exhaust gas, an appropriate amount of the treatment agent is produced at the time when the oxygen gas concentration in the exhaust gas starts to decrease. In addition, by neutralizing the sulfur oxides in the exhaust gas, the concentration of the acid gas can be stably suppressed to a low level without causing the acid gas to fluctuate temporarily to a high concentration.

The correlation between the concentration of oxygen gas and the concentration of sulfur oxides varies depending on the characteristics of the device of the exhaust gas treatment system, the size of the device, the condition of the reaction in which exhaust gas is generated, and the like. Therefore, a calibration curve for examining the relationship between the concentration of oxygen gas and the concentration of sulfur oxides in each exhaust gas treatment system is prepared in advance, and the addition amount of the treatment agent required for treatment of the acid gas contained in the exhaust gas is determined by considering the amount of exhaust gas as well. can

(Analysis time of sulfur oxide concentration)

Further, in the analysis of the sulfur oxide concentration, the sulfur dioxide concentration was obtained by using light absorption in the infrared region of sulfur dioxide, which is the main component of the sulfur oxide. Specifically, the amount of absorption of infrared rays in the vicinity of 7.3 μm of sulfur dioxide was analyzed, and the concentration of sulfur dioxide contained in exhaust gas was continuously analyzed. However, the current analysis of sulfur oxides, depending on the analysis principle, required a time of several minutes, and at least 4 minutes as of now, until the results were obtained. During that time, exhaust gas flows from the incinerator F to the chimney 18 through the exhaust gas recovery unit 11. Therefore, between the start of the analysis and the output of the results, the exhaust gas to which the processing agent was not introduced flowed into the atmosphere.

(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 to analyze and measure the oxygen gas concentration. In the analysis/measurement method, an oxygen concentration meter using a zirconia method can be installed upstream or downstream of the exhaust gas analyzer 132 of the exhaust gas treatment system 1 for analysis. In normal oxygen gas concentration analysis, it can be analyzed in 2 minutes with the zirconia method, so it can be analyzed in a shorter time compared to the concentration analysis of sulfur oxides. Therefore, since the analysis time of the oxygen concentration meter can be performed in a short time after the exhaust gas reaches the exhaust gas analyzer 132, the oxygen gas concentration is analyzed even on the downstream side of the exhaust gas recovery unit 16 to calculate the analysis value. And, by issuing an instruction from the processing agent addition management unit 13 to the processing agent supply unit 12 in a short time, the processing agent supply unit 12 supplies the processing agent to be processed by the exhaust gas processing unit 11. Thereby, the exhaust gas which is not neutralized by the treatment agent can be reduced, and the exhaust gas which leaks into the air without being neutralized can be reduced.

(Use of change in oxygen gas concentration)

As described above, the time required for the analysis of the concentration of oxygen gas and the concentration of sulfur oxides to be analyzed in the exhaust gas analyzer 132 and the concentration of oxygen gas and sulfur oxides in the exhaust gas treatment system 1 By using both of the time difference appearing in the change behavior, it is possible to greatly reduce the exhaust gas that is not neutralized with the treatment agent and to reduce the exhaust gas that leaks into the air without being neutralized. In this way, by reducing the delay time that cannot cope with the neutralization treatment of sulfur oxides as much as possible, leakage of exhaust gas containing sulfur oxides from the chimney can be suppressed.

(gradual addition of treatment agent)

In addition, the mass of the acid gas to be treated per hour was determined from the amount of exhaust gas and the concentration of sulfur oxides, and the necessary amount of the treatment agent was determined by adding the amount of the treatment agent considering the neutralization reaction to the unit amount of sulfur oxides. Next, control of the addition of the processing agent to the exhaust gas was performed by the feed forward control method or the feedback control method. Therefore, in the present embodiment, similar to the control method based on the analysis of the sulfur oxide concentration so far, based on the numerical value of the change in the oxygen gas concentration analyzed by the exhaust gas analyzer 132, the logic for controlling the addition amount of the treatment agent By applying it to the processing agent addition management unit 13, processing of sulfur oxides is controlled.

However, the change in oxygen gas concentration is more gradual than the change in sulfur oxide concentration. Further, the change in the oxygen gas concentration indicates the starting point of adding the treatment agent, but the oxygen gas concentration and the sulfur oxide concentration do not completely correspond. Therefore, it is preferable to change the addition amount of the processing agent stepwise in response to the change in the oxygen gas concentration without completely responding to the change in the 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 treatment agent is added first. Determine the amount to be added step by step for the oxygen gas concentration. After that, when the tendency of the oxygen gas concentration to decrease decreases, the amount of the treatment agent added is greatly reduced and reduced. By performing the step-by-step processing in this way, it is possible to carry out the neutralization treatment of sulfur oxides in accordance with the oxygen gas concentration in the exhaust gas treatment system 1.

(upstream exhaust gas analysis unit)

In addition, for the analysis value of the oxygen gas concentration, the exhaust gas analyzer 132 on the downstream side of the exhaust gas recovery unit 16 was used, but the exhaust gas analyzer 131 on the upstream side of the exhaust gas recovery unit 16 The processing agent addition management part 13 may manage as an analysis value by analysis. The one where the treatment agent supply unit 12 and the position where the exhaust gas is analyzed are closer in terms of distance and time enable immediate addition of the treatment agent to the exhaust gas.

(Example)

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

In order to neutralize sulfur oxides in the exhaust gas and recover them in the exhaust gas recovery unit, the amount of sulfur oxides is usually analyzed next to the exhaust gas recovery unit. In the control of sulfur oxides, the control of the addition amount of the processing agent is performed by a feedback control method such as PID based on the result of sulfur analysis. Until now, in most cases, the sulfur oxide concentration was analyzed on the downstream side of the exhaust gas recovery unit, and a treatment agent was supplied to the upstream side of the exhaust gas recovery unit based on the analysis result. In order to compare the influence of the analysis of the concentration of oxygen gas and the concentration of sulfur oxides on the downstream side of the exhaust gas recovery unit, the trend of the concentration of sulfur oxides and the consumption of slaked lime as a treatment agent were analyzed when each concentration analysis was performed.

(Comparative Example 1)

As Comparative Example 1, in a factory equipped with the exhaust gas treatment system described above, exhaust gas treatment was performed by analyzing the sulfur oxide concentration using the conventional exhaust gas treatment method.

Here, regardless of the change in the oxygen gas concentration, the change in the sulfur oxide concentration was grasped and the addition of the treatment agent was started. At this time, the transition of the sulfur oxide concentration and the addition time 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 from when the exhaust gas reaches the analyzer is several minutes, specifically about 240 seconds to 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 was injected into the exhaust gas processing unit of the exhaust gas processing system shown in FIG. 1, and as shown in FIG. 2, when the concentration of sulfur dioxide (SO ₂ ), which is a sulfur oxide, began to increase, slaked lime as a treatment agent was introduced. However, at the location of the exhaust gas analyzer on the downstream side of the exhaust gas recovery unit, the SO ₂ concentration began to increase rapidly. When about 1 to 2 minutes have elapsed thereafter, after the SO ₂ concentration reaches the peak, the effect of adding the treatment agent starts to appear and the SO ₂ concentration decreases. From this fact, it can be seen that the addition of the treatment agent into the exhaust gas treatment unit could not sufficiently treat the concentration of SO ₂ contained in the exhaust gas. When the exhaust gas mixed with the treatment agent reaches the exhaust gas analyzer, the exhaust gas containing a large amount of sulfur oxides that has not been treated with the treatment agent is discharged and leaked into the atmosphere through the chimney within 1 to 2 minutes.

(Example 1)

Next, the change in oxygen gas (O ₂ ) concentration was grasped, 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, after preparing a calibration curve by analyzing the concentration of SO ₂ and O ₂ contained in exhaust gas in advance, a program for varying the addition amount of the treatment agent step by step as follows was introduced, and the addition amount between the conventional control method and this program This high value was employed in a manner. Table 1 shows the relationship between the oxygen gas concentration (%) and the amount of slaked lime to be introduced (kg/h).

As shown in Fig. 3, slaked lime as a treatment agent was injected when the oxygen concentration became lower than 10% after 1 minute had elapsed after the injection of the exhaust gas. However, exhaust gas with a high sulfur oxide concentration was injected into the exhaust gas analyzer 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 analyzer, the exhaust gas containing a large amount of sulfur oxides that has not been neutralized is discharged to the outside. However, about one minute before the sulfur oxide concentration rises, the addition of slaked lime is started. For this reason, the peak of the sulfur oxide concentration was very low compared to Comparative Example 1. In addition, by changing the addition amount of slaked lime step by step according to the change in oxygen gas concentration, rather than continuously changing the amount of slaked lime in response to the change in oxygen gas concentration, the consumption of slaked lime is somewhat large, but untreated sulfur oxides are not generated with respect to sulfur oxides, have. It has been shown that by this treatment, there is very little discharge or leakage to the outside of the exhaust gas containing a large amount of sulfur oxides in which the treatment agent is not added.

However, in Example 1, since slaked lime is added earlier than in Comparative Example 1, it can be seen that the addition time is long and the addition amount of slaked lime is large. Even this, it can be seen that the neutralization treatment of sulfur oxides in the exhaust gas is sufficiently performed.

Further, as is evident from slaked lime shown in Figs. 2 and 3, in an actual exhaust gas treatment system, a certain amount of treatment agent is always added regardless of the concentration of oxygen and sulfur oxides. Here, "addition of a processing agent" means addition of a large amount of processing agents from general addition.

1: Exhaust gas treatment system
11: Exhaust gas processing unit
12: processing agent storage unit
13: treatment agent addition management unit
131, 132: exhaust gas analysis unit
14: treatment agent supply unit
16: exhaust gas recovery unit
17: exhaust gas flow meter
18 : chimney
F : Incinerator

Claims (5)

An exhaust gas processing unit for processing exhaust gas;
An exhaust gas recovery unit that separates and removes solids from the exhaust gas treated by the exhaust gas processing unit;
a processing agent storage unit for storing a processing agent for treating the exhaust gas;
an exhaust gas analysis unit disposed on at least one of an upstream side and a downstream side of the exhaust gas recovery unit and analyzing at least an oxygen gas concentration in the exhaust gas, the oxygen analyzed by the exhaust gas analysis unit A processing agent addition management unit that calculates an addition amount of a processing agent necessary for processing the acid gas contained in the exhaust gas treated by the exhaust gas processing unit based on the variation in gas concentration, and instructs supply of the processing agent of the calculated addition amount;
A processing agent supply unit for supplying the processing agent in the amount of addition indicated by the processing agent addition management unit from the processing agent storage unit to the exhaust gas processing unit
Exhaust gas treatment system provided.
According to claim 1,
The exhaust gas treatment system according to claim 1 , wherein the exhaust gas analyzer is disposed on a downstream side of the exhaust gas recovery unit.
According to claim 1 or 2,
The exhaust gas treatment system according to claim 1 , wherein the treatment agent has a property of neutralizing an acid gas in the exhaust gas.
According to any one of claims 1 to 3,
An exhaust gas treatment system in which the acid gas contains sulfur oxides.
An exhaust gas analysis unit disposed on at least one of the upstream side and the downstream side of an exhaust gas recovery unit that separates gases and solids contained in the exhaust gas to recover and remove the solids, and analyzes the concentration of oxygen gas in at least the exhaust gas. Based on the amount of change in the oxygen gas concentration analyzed by the exhaust gas analysis unit of the processing agent addition management unit, the addition amount of the processing agent required for the treatment of the acid gas contained in the exhaust gas processed by the exhaust gas processing unit is calculated and calculated An exhaust gas treatment method comprising instructing a treatment agent supply unit to supply an additive amount of a treatment agent, and supplying the indicated treatment agent additive amount to the exhaust gas treatment unit from a treatment agent storage unit to treat acid gas contained in the exhaust gas.

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