TWI787570B - Exhaust gas treatment system and exhaust gas treatment method - Google Patents

Abstract

The present invention provides an exhaust gas treatment system based on the premise of treating the recovered fly ash with a fly ash treatment agent after treating the exhaust gas generated in the incineration treatment of waste with an exhaust gas treatment agent, which can be used Eliminate the complexity of controlling the amount of fly ash treatment agent added and management of inventory, realize labor saving, and suppress stockout (out of stock) of fly ash treatment agent. The exhaust gas treatment system of the present invention includes: an exhaust gas treatment unit for treating exhaust gas; a fly ash recovery unit for separating and recovering fly ash from the treated exhaust gas; an exhaust gas treatment agent addition management unit arranged in the exhaust gas treatment unit Waste gas treatment in which the amount of acid contained in the exhaust gas is analyzed on at least one of the upstream side and the downstream side, and based on the analyzed amount of the acid, the amount of alkali contained in the fly ash is calculated to fall within a specified range agent, and instruct to supply the calculated addition amount of the exhaust gas treatment agent; the exhaust gas treatment agent supply unit supplies the exhaust gas treatment unit with the addition amount of the exhaust gas treatment agent indicated by the exhaust gas treatment agent addition management unit a fly ash processing part for receiving and processing the fly ash recovered by the fly ash recovery part; and a fly ash treating agent supply part for feeding A fly ash treatment agent having a constant mass ratio to ash is supplied to the fly ash treatment unit.

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. More specifically, it relates to a method that can make the amount of fly ash treatment agent required for the treatment of fly ash recovered from exhaust gas a certain amount, and can eliminate the need for inventory. The manager regularly confirms the exhaust gas treatment system and exhaust gas treatment method that are complicated to manage such as inventory.

The exhaust gas produced by incineration of waste is acid gas containing hydrogen chloride and sulfur oxides. Conventionally, such exhaust gas has been treated with exhaust gas treatment agents such as slaked lime and sodium bicarbonate, and then the fly ash, which is a solid substance, has been dedusted with a dust collector such as a bag filter, and then discharged from the chimney.

On the other hand, the fly ash recovered by the dust collector may contain heavy metals such as lead, cadmium, arsenic, selenium, chromium, etc. Therefore, fly ash is designated as special managed general waste by the Waste Disposal Law, and it is stipulated that it must be disposed of by landfill or the like after the removal of heavy metals.

As fly ash treatment agents for removing heavy metals, for example, Patent Document 1 discloses inorganic heavy metal fixing agents such as phosphoric acid compounds, silica compounds, iron compounds, acid neutralizers such as hydrochloric acid, sulfuric acid, and nitric acid.

This kind of fly ash treatment agent is sometimes added in a certain amount according to the batch of fly ash treatment or according to the specific amount of fly ash, but in this case, according to the ash properties of fly ash, the best fly ash treatment when dealing with fly ash Therefore, even if the addition of a certain amount of fly ash treatment agent is for the treatment of a specific amount of fly ash, it is insufficient or excessive for the harmless treatment of fly ash. Therefore, in recent years, from the standpoint of properly handling fly ash and reducing the amount of treatment agent used, the following method has been proposed: collect a part of fly ash before treatment for analysis, estimate the amount of treatment agent needed, and add the required amount of treatment agent. The stated amount of treatment agent. For example, Patent Document 2 discloses a method of collecting a part of fly ash, titrating an aqueous solution obtained by mixing the fly ash with water, and determining the amount of heavy metal immobilized as a fly ash treatment agent added to the fly ash based on the titrated amount. dose. [Prior art literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-159269 [Patent Document 2] Japanese Patent Laid-Open No. 11-76975

[Problem to be Solved by the Invention] In the treatment method described in Patent Document 2, an appropriate amount of fly ash treatment agent can be estimated for the fly ash to be treated. Quantity changes. In this processing method, from the viewpoint of preventing the stock from running out, it is necessary for the stock manager to regularly check the stock amount and order the fly ash processing agent. In particular, when the properties of the fly ash fluctuate greatly, or the capacity of the storage facility for the fly ash treatment agent is small, if the amount of the fly ash treatment agent used for the treatment of the fly ash increases rapidly, the fly ash treatment is likely to occur. Since the inventory of the agent is exhausted, the inventory manager frequently confirms the amount of the fly ash treatment agent stored in the storage tank, grasps the remaining amount, and orders the fly ash treatment agent when the remaining amount is reduced to a predetermined amount.

However, in this method, the control of the addition amount of the fly ash treatment agent and the management of the inventory of the fly ash treatment agent are complicated, and management personnel and the like are required, so it is difficult to save manpower. Moreover, in such inventory management, human error is also prone to occur. Therefore, an exhaust gas treatment system capable of stably treating fly ash by keeping the amount of the fly ash treatment agent constant without changing the addition amount is sought.

The present invention has been made in view of the above actual situation, and its object is to provide an exhaust gas treatment system that uses a fly ash treatment agent to process the exhaust gas generated in the incineration treatment of waste with an exhaust gas treatment agent. Based on the exhaust gas treatment system that treats the recovered fly ash, it can eliminate the complexity of the control of the amount of fly ash treatment agent added and the management of the inventory, realize labor saving, and suppress the stock of the treatment agent from running out (out of stock) ).

[Means to solve the problem] The inventors of the present invention have made intensive studies in order to achieve the above objects. As a result, it has been found that it is possible to provide an exhaust gas management system that, by analyzing the amount of acid contained in the exhaust gas, adjusts the amount of the exhaust gas treating agent added in accordance with the amount of the analyzed acid so that the amount of alkali contained in the fly ash falls within a specified range. Within the range, the amount of fly ash treatment agent required to process the fly ash recovered on the downstream side can be fixed, which can eliminate the complexity of the control of the amount of fly ash treatment agent added and the management of inventory, and realize labor saving, In addition, the present invention has been accomplished by suppressing the stockout (out of stock) of the fly ash treatment agent. Specifically, the present invention provides the following.

(1) An exhaust gas treatment system, comprising: an exhaust gas treatment unit for treating exhaust gas; a fly ash recovery unit for separating and recovering fly ash from the treated exhaust gas; an exhaust gas treatment agent adding management unit arranged in the exhaust gas At least one of the upstream side and the downstream side of the treatment unit analyzes the amount of acid contained in the exhaust gas, and calculates that the amount of alkali contained in the fly ash falls within a predetermined range based on the analyzed amount of the acid. the addition amount of the exhaust gas treatment agent, and instructs to supply the calculated addition amount of the exhaust gas treatment agent; the exhaust gas treatment agent supply unit supplies the exhaust gas with the addition amount instructed by the exhaust gas treatment agent addition management unit to the exhaust gas treatment unit a treatment agent; a fly ash treatment section for loading and treating the fly ash recovered by the fly ash recovery section; and a fly ash treatment agent supply section for supplying A fly ash treatment agent having a constant mass ratio to the fly ash is supplied to the fly ash treatment unit.

(2) The exhaust gas treatment system according to (1), wherein the fly ash treatment agent supplied to the fly ash treatment unit via the fly ash treatment agent supply unit is stored in a fly ash treatment agent storage unit.

(3) The exhaust gas treatment system according to (1) or (2), wherein the exhaust gas treatment agent addition management unit is arranged on both the upstream side and the downstream side of the exhaust gas treatment unit.

(4) An exhaust gas treatment method, comprising: analyzing the amount of acid contained in the exhaust gas by the exhaust gas treatment agent addition management section at least upstream of the exhaust gas treatment unit and the downstream side, and according to the analysis The step of calculating the amount of the added amount of the exhaust gas treatment agent in which the amount of the alkali contained in the fly ash falls within a predetermined range, and instructing the exhaust gas treatment agent supply unit to supply the calculated amount of the added amount of the exhaust gas treatment agent; A step in which the exhaust gas treatment agent supply unit supplies the indicated amount of the exhaust gas treatment agent to the exhaust gas treatment unit; the fly ash recovery unit separates and recovers the waste gas treated by adding the exhaust gas treatment agent a step of fly ash; and a step of supplying a fly ash treatment agent having a constant mass ratio relative to the fly ash loaded into the fly ash treatment unit to the fly ash treatment unit through a fly ash treatment agent supply unit.

[Effect of the invention] According to the present invention, an exhaust gas treatment system may be provided, comprising: an exhaust gas treatment unit for treating exhaust gas; a fly ash recovery unit for separating and recovering fly ash from the treated exhaust gas; and an exhaust gas treatment agent adding management unit arranged at At least one of the upstream side and the downstream side of the exhaust gas treatment unit analyzes the amount of acid contained in the exhaust gas, and calculates the amount of alkali contained in the fly ash based on the analyzed amount of the acid. range, and instruct to supply the calculated amount of the exhaust gas treatment agent; the exhaust gas treatment agent supply unit supplies the exhaust gas treatment unit with the addition amount instructed by the exhaust gas treatment agent addition management unit the exhaust gas treatment agent; the fly ash treatment part for loading and treating the fly ash recovered by the fly ash recovery part; and the fly ash treatment agent supply part for loading the fly ash treatment part A fly ash treatment agent with a constant mass ratio to the fly ash is supplied to the fly ash treatment unit. In particular, the amount of the waste gas treatment agent is adjusted by analyzing the amount of acid in the exhaust gas to be treated, so that By keeping the amount of alkali contained in the fly ash recovered on the downstream side within a predetermined range, the amount of the fly ash treatment agent required to treat the fly ash can be kept constant, and the control of the amount of the fly ash treatment agent added and the Complicated inventory management, labor saving, and suppression of stock run-out (out of stock) of processing agents.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments at all, and can be implemented with appropriate changes within the scope of the purpose of the present invention.

＜Exhaust gas treatment system＞ FIG. 1 shows a schematic flowchart of a construction example of an exhaust gas treatment system according to the present embodiment. Furthermore, in FIG. 1, among the lines connecting each block, the solid line represents the flow of objects, and the chain line of dots represents the flow of information.

The exhaust gas treatment system 1 of the present embodiment mainly includes an exhaust gas treatment unit 11, a fly ash recovery unit 12, an exhaust gas treatment agent addition management unit 13, an exhaust gas treatment agent supply unit 14, a fly ash treatment unit 15, a fly ash treatment agent supply unit 16 and Fly ash treatment agent storage part 19.

In such an exhaust gas treatment system 1, the exhaust gas treatment agent addition management unit 13 is arranged at least on the upstream side and the downstream side of the exhaust gas treatment unit 11, and at the position where the exhaust gas treatment agent addition management unit 13 is arranged The amount of acid in the exhaust gas is analyzed, and according to the amount of the analyzed acid, the amount of alkali contained in the fly ash is calculated to be within a specified range, and the amount of waste gas treatment agent added is specified, and the exhaust gas treatment agent supply unit 14 is instructed to supply the said Calculate the amount of exhaust gas treatment agent added. Thereby, the amount of the alkali contained in the fly ash recovered in the fly ash recovery unit 12 is substantially constant, and the required amount of the fly ash treatment agent added to treat the fly ash is also substantially constant. That is, in the fly ash treatment agent supply unit 16, the amount of the fly ash treatment agent supplied to the fly ash treatment unit 15 becomes stable, an excessive amount of the fly ash treatment agent is not added, and the analysis of the added amount of the fly ash treatment agent is not performed. And control, only supply a certain amount of fly ash treatment agent can carry out the treatment of fly ash. In addition, it is possible to eliminate the complexity of controlling the amount of addition of the fly ash treatment agent and managing the inventory, and to suppress the exhaustion of the stock of the fly ash treatment agent.

When the waste gas is generated by incinerating waste in the incinerator F, it is processed through the following path, for example. Furthermore, in the following example, the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 constituting the exhaust gas treatment agent addition management unit 13 are respectively arranged on the upstream side (the exhaust gas analysis unit 131 ) and the downstream side (the exhaust gas analysis unit 132 ) of the exhaust gas treatment unit 11 . ) case example.

The exhaust gas generated in the incinerator F is cooled by passing through a boiler and a temperature reduction tower (both not shown), and sent to the exhaust gas analysis unit 131 . With the exhaust gas analysis unit 131, for example, after analyzing the amount of acid such as acid gas concentration contained in the exhaust gas, based on the information on the amount of acid obtained by the analysis, the amount of the exhaust gas treatment agent to be added is calculated, and the calculated The exhaust gas treatment agent is added to the exhaust gas treatment part 11. Then, the fly ash is removed (recovered) by the fly ash recovery unit 12 . Thereafter, for example, the acid gas concentration is analyzed by the exhaust gas analysis unit 132, and it is discharged into the atmosphere after confirming that it is below the exhaust gas standard. Here, information on the amount of acid contained in the exhaust gas analyzed by the exhaust gas analysis unit 131 is sent to the exhaust gas treatment agent addition management unit 13 . The exhaust gas treatment agent addition management unit 13 calculates the addition amount of the exhaust gas treatment agent in which the amount of alkali contained in the fly ash downstream of the exhaust gas treatment unit 11 falls within a predetermined range based on the information on the amount of acid in the exhaust gas. Then, the exhaust gas treatment agent addition management part 13 transmits the addition amount information acquired in this way to the exhaust gas treatment agent supply part 14, and gives an instruction. In the exhaust gas treatment agent supply part 14, the exhaust gas treatment agent supplied from the exhaust gas treatment agent storage part 17 is supplied to the exhaust gas treatment part 11 according to the obtained addition amount information.

The fly ash recovered by the fly ash recovery unit 12 is temporarily stored in a fly ash storage unit (not shown) for storing the fly ash, and then supplied to the fly ash processing unit 15 via the fly ash supply unit 18 , for example. On the other hand, after the fly ash treatment agent is stored in the fly ash treatment agent storage unit 19 , it is supplied to the fly ash treatment unit 15 via the fly ash treatment agent supply unit 16 . At this time, the amount of the fly ash treatment agent can be set so as to have a constant mass ratio with respect to the fly ash charged into the fly ash treatment unit 15 . Therefore, the fly ash treatment agent supplied to the fly ash treatment unit 15 only needs to be added in an amount (a certain volume, a certain mass, etc.) Therefore, it is not necessary to determine the addition amount of the fly ash treatment agent to be supplied to the fly ash treatment unit 15 every time of supply. Furthermore, the fly ash treated in this way is disposed of by landfill or the like.

In addition, although it is not an essential structure, the exhaust gas treatment agent storage part 17 and the fly ash treatment agent storage part 19 may respectively have the exhaust gas treatment agent remaining amount meter 171 and the fly ash treatment agent remaining amount meter 191. Thereby, the remaining stock of each processing agent can be confirmed.

Each constituent element of the exhaust gas treatment system will be described in detail below.

〔Exhaust Gas Treatment Department〕 The exhaust gas processing unit 11 processes exhaust gas. As described above, since the exhaust gas is an acid gas containing hydrogen chloride and sulfur oxides, it is necessary to neutralize the acid gas before discharging it into the atmosphere to suppress discharge of harmful gas to the environment. Therefore, in the exhaust gas treatment unit 11, a treatment agent is added to the exhaust gas to neutralize it.

Details will be described later, but as the treatment agent, for example, an alkali agent is used. Such a treatment agent can neutralize the acid gas contained in the contacted exhaust gas by contacting the exhaust gas.

The exhaust gas treatment unit 11 is not particularly limited as long as the exhaust gas can be brought into contact with a solid treatment agent to react. For example, a part of the flue (gas flow path) or the like can be used as the exhaust gas treatment unit. Among them, as the flue, specifically, a part of a conveying pipe for conveying the gas to a dust collector such as a bag filter at the rear stage (hereinafter, the flue as the exhaust gas treatment unit 11 may also be referred to as "reaction tube" case). Furthermore, the exhaust gas treatment unit 11 may also include a closed container, various reaction containers, and the like that are additionally provided in the flue (gas flow path).

In addition, as exhaust gas, there are no particular limitations on its generation source and contained components, and exhaust gas generated by incineration of various wastes can be used.

The treatment of exhaust gas can be performed continuously. In addition, for example, it is also possible to carry out in a batch system using a closed container or various reaction containers for gas phase phase applications. In either case, the amount of waste gas to be treated is not particularly limited, and may be appropriately designed in consideration of the amount of waste gas generated by incineration of waste, and the like.

〔Fly Ash Recovery Department〕 The fly ash recovery unit 12 separates and recovers fly ash as a solid component from the exhaust gas treated in the exhaust gas treatment unit 11 . The fly ash removed here usually contains the unreacted exhaust gas treatment agent added in the exhaust gas treatment unit 11, but the exhaust gas treatment system of this embodiment can stably reduce the The content of unreacted exhaust gas treatment agent.

The fly ash recovery unit 12 is not particularly limited as long as it can separate gas components and solid components (fly ash) contained in the exhaust gas and recover the solid components. For example, a bag filter or the like can be used.

〔Exhaust gas treatment agent addition management department〕 The exhaust gas treatment agent addition management unit 13 has an exhaust gas analysis unit 131 disposed on at least one of the upstream side and the downstream side of the exhaust gas treatment unit 11 . In addition, the exhaust gas treatment agent addition management part 13 may have the fly ash analysis part 133. In addition, in FIG. 1, the example which has the exhaust gas analysis part 131 and the exhaust gas analysis part 132 located in the upstream side and the downstream side of the exhaust gas processing part 11 respectively is shown. In addition, although the example where the fly ash analysis part 133 is located in the fly ash recovery part 12 is shown in FIG.

In the exhaust gas treatment agent addition management unit 13, the exhaust gas treatment agent addition management unit 13 analyzes the amount of acid contained in the exhaust gas at least by the exhaust gas analysis unit 131, and calculates the amount of acid used to recover the waste gas on the downstream side of the exhaust gas treatment unit 11. The amount of the alkali contained in the ash is the required addition amount of the exhaust gas treatment agent in a predetermined range, and the supply of the calculated addition amount of the exhaust gas treatment agent is instructed. The exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 measure the amount of acid contained in the exhaust gas before and after treatment. Thereby, it can be confirmed whether or not the neutralization process of exhaust gas is performed sufficiently and appropriately. As will be described later in detail, the amount of alkali contained in the fly ash is measured by the fly ash analysis unit 133, and this value is compared with the value of the amount of acid contained in the exhaust gas measured by the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132. , The amount of the actually added exhaust gas treatment agent is analyzed correspondingly, so that the corresponding relationship between the amount of acid contained in the exhaust gas, the amount of the exhaust gas treatment agent added, and the amount of alkali contained in the fly ash can be derived. In addition, the "upstream side" and "downstream side" here refer to the upstream and downstream of the flow of exhaust gas.

As a specific method for managing the addition of the exhaust gas treatment agent, it is necessary to analyze the amount of acid contained in the exhaust gas and calculate the amount of alkali contained in the fly ash on the downstream side of the exhaust gas treatment unit 11 to fall within a predetermined range. The method for the amount of the required exhaust gas treatment agent is not particularly limited. For example, it can be cited that in the exhaust gas analysis unit 131 arranged on the upstream side of the exhaust gas treatment unit 11, the exhaust gas is analyzed for acidity, acid gas concentration, etc. The method of calculating the amount of acid contained in the exhaust gas and calculating the amount of exhaust gas treatment agent required to neutralize them (feedforward control). In addition, although the details will be described later, in the case of using the fly ash analysis unit 133 arranged on the downstream side of the exhaust gas treatment unit 11, for example, the method of combining the acidity or acidity of the exhaust gas from the exhaust gas analysis unit 131 can be mentioned. The data on the amount of acid contained in the exhaust gas, such as the gas concentration, is based on past data, that is, the amount of acid in the exhaust gas of the exhaust gas analysis unit 131, the amount of the exhaust gas treatment agent added to the exhaust gas, and the amount of the fly ash analysis unit 133. The relationship between the amount of alkali contained in fly ash is calculated by calculating the amount of exhaust gas treatment agent required to bring the amount of alkali contained in fly ash into a predetermined range in the fly ash recovery unit 12 or its downstream side.

(Exhaust Gas Analysis Department) The exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 constitute the exhaust gas treatment agent addition management unit 13 , and are arranged on the upstream side and the downstream side of the exhaust gas treatment unit 11 , respectively. That is, the properties of the exhaust gas before and after adding the exhaust gas treatment agent to the exhaust gas are analyzed.

Furthermore, as mentioned above, in FIG. 1 , an example with the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 respectively arranged on the upstream side and the downstream side of the exhaust gas treatment unit 11 is shown, but as long as the exhaust gas analysis unit is arranged at At least one of the upstream side and the downstream side of the exhaust gas treatment unit 11 is sufficient, and may be arranged on both the upstream side and the downstream side. In addition, one exhaust gas analysis unit may be arranged on the upstream side and the downstream side, or a plurality of them may be arranged.

In the exhaust gas analysis unit 131 arranged on the upstream side of the exhaust gas treatment unit 11 , the analysis is performed according to the amount of acid contained in the exhaust gas treated by the exhaust gas treatment unit 11 . For example, by analyzing the amount of acid with a gas concentration meter or the like, it is possible to calculate the amount of the exhaust gas treating agent required for neutralizing the exhaust gas. In addition, it is also possible to collect a specified volume of exhaust gas, actually add alkali compounds, and calculate the amount of exhaust gas treatment agent required for exhaust gas neutralization. And, if the amount of exhaust gas treatment agent required for the neutralization of exhaust gas can be calculated in this way, the amount of alkali contained in fly ash can be calculated by adding an excess amount of exhaust gas treatment agent to a certain amount relative to the neutralization amount. The amount becomes the addition amount of the exhaust gas treatment agent within the specified range.

In addition, in the exhaust gas analysis unit 132 arranged on the downstream side of the exhaust gas treatment unit 11, the amount of acid contained in the exhaust gas treated by the exhaust gas treatment unit 11 can be analyzed by the same method as the exhaust gas analysis unit 131 described above. . Thereby, it is possible to monitor the harmful gas and suppress the release of such gas to the outside air. In addition, it can be confirmed whether the exhaust gas treatment agent is sufficiently activated by at least the amount of the exhaust gas treatment agent calculated from the amount of acid in the exhaust gas of the exhaust gas analysis unit 131. neutralize. Furthermore, when the exhaust gas analysis unit 132 is arranged, the exhaust gas analysis unit 132 is preferably arranged on the downstream side in the positional relationship with the fly ash recovery unit 12 , but may be arranged on the upstream side.

More specifically, gas analyzers can be used as the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 , respectively. Thereby, the concentration of the acid gas contained in the exhaust gas can be calculated. Alternatively, a part of the gas may be collected, mixed with water to prepare a solution, and the amount of acid contained in the exhaust gas may be calculated using a device for measuring the pH of the solution.

Hereinafter, the method of calculating the minimum addition amount of the waste gas treatment agent required for treating waste gas from the density|concentration of the acid gas contained in waste gas concretely is demonstrated.

First, the mass W _acid [kg/h] of the acid gas processed per hour is obtained from the following formula (1). W _acid ＝(C _{acid , in} -C _{acid , out} )×V _g /10 ⁶・・(1) Here, C _{acid , in} [mg/Nm ³ ] and C _{acid , out} [mg/Nm ³ ] are respectively is the acid gas concentration before and after treatment with the exhaust gas treatment agent (for example, the exhaust gas analysis unit 131 and the exhaust gas analysis unit 132 , or the inlet and outlet of the exhaust gas). In addition, V _g [Nm ³ /h] is the treatment volume per hour of exhaust gas in terms of dry gas in a standard state (0° C., 1 atmosphere). When the flow rate of the gas to be processed becomes roughly constant, V _g can be set as a constant. In addition, when the increase or decrease of the gas flow rate is large, an exhaust gas flow meter (including the inlet or outlet) can also be installed in the flow path ( not shown) to actually measure V _g .

Next, the required amount of the treatment agent _Walkaline [kg/h] is obtained by the following formula (2). W _alkaline ＝n _acid ×W _acid ×M _{w , alkaline} /(n _alkaline ×M _{w , acid} ) ・・(2) Here, M _{w , acid} [g/mol] and M _{w , alkaline} [g/mol] are the molecular weights of the acidic compound constituting the acidic gas and the alkali constituting the treating agent, respectively, n _acid is the valence of the acid of the acidic gas, and n _alkaline is the valence of the alkali constituting the treating agent.

Here, when formula (1) is substituted into W _acid in formula (2) and rearranged, it becomes the following formula (3). W _alkaline ＝ {n _acid × (C _{acid , in} -C _{acid , out} ) × M _{w , alkaline} / (n _alkaline × M _{w , acid} )} × V _g /10 ⁶・・(3)

The amount obtained by adding a predetermined amount to the minimum addition amount _Walkaline of the exhaust gas treatment agent obtained by the above formula (3) can be obtained as the addition amount of the exhaust gas treatment agent.

In addition, what is necessary is just to measure alkalinity by mixing fly ash and water as the quantity of the alkali in fly ash, for example. As an index of alkalinity, for example, "acid consumption (pH8.3)" can be used. Here, "acid consumption (pH8.3)" means the acid consumption when acid was added and neutralized to pH8.3. In addition, the acid consumption (pH8.3) in fly ash is the value (unit: mg-CaCO3/g-fly ash) measured about the solution obtained by adding 1 L of pure water to ₁ g of fly ash.

The acid consumption (pH 8.3) of the fly ash recovered after the treatment in the exhaust gas treatment unit 11 is not particularly limited, but is preferably within a certain range. More specifically, x[mg-CaCO ₃ /g-fly ash] (hereinafter referred to as "acid consumption (pH8.3) In the case of median value"), the acid consumption (pH8.3) is preferably in the range of x±50[mg-CaCO ₃ /g-fly ash], more preferably x±40[mg-CaCO ₃ /g- fly ash], more preferably x±30 [mg-CaCO ₃ /g-fly ash], particularly preferably x±25 [mg-CaCO ₃ /g-fly ash]. However, the acid consumption (pH8.3) was set to a value of 0 or more. By setting the acid consumption (pH8.3) of the treated exhaust gas in the range of x±50[mg-CaCO ₃ /g-fly ash], the acid consumption (pH8.3) in the fly ash can be approximately Constantly, thereby, the addition amount of the fly ash treatment agent can be adjusted to be constant, and the effect of suppressing the control of the addition amount of the fly ash treatment agent and the management complexity of the inventory can be further improved.

More specifically, "x±50[mg-CaCO ₃ /g-fly ash]" about the acid consumption (pH8.3) means that when x is the median value of the acid consumption (pH8.3) For example, in the case of 100, during operation, adjust the amount of fly ash treatment agent to 100±50[mg-CaCO ₃ /g-fly ash], that is, 50[mg-CaCO ₃ /g-fly ash]～150[ mg-CaCO ₃ /g-fly ash].

In addition, the value of the central value x of the acid consumption (pH8.3) is not particularly limited, but is preferably 0 [mg-CaCO ₃ /g-fly ash] or more and 200 [mg-CaCO ₃ /g-fly ash] Below, more preferably 0 [mg-CaCO ₃ /g-fly ash] or more and 180 [mg-CaCO ₃ /g-fly ash] or less, more preferably 0 [mg-CaCO ₃ /g-fly ash] or more than 160 [ mg-CaCO ₃ /g-fly ash] or less, particularly preferably 0 [mg-CaCO ₃ /g-fly ash] or more and 150 [mg-CaCO ₃ /g-fly ash] or less. However, the acid consumption (pH8.3) was set to a value of 0 or more. That is, in the case where the acid consumption (pH8.3) is x±50 [mg-CaCO ₃ /g-fly ash] and x is less than 50 [mg-CaCO ₃ /g-fly ash], the lower limit value is set to 0 [mg-CaCO ₃ /g-fly ash] or more. For example, when x=0[mg-CaCO ₃ /g-fly ash], set it in the range of 0[mg-CaCO ₃ /g-fly ash] to 50[mg-CaCO ₃ /g-fly ash] . By making the value of x in the above formula 200 [mg-CaCO ₃ /g-fly ash] or less, excessive addition of the alkali compound can be suppressed, and superiority in terms of cost can also be secured. In addition, the value of x in the above formula is preferably at least 50 [mg-CaCO ₃ /g-fly ash], more preferably at least 100 [mg-CaCO ₃ /g-fly ash]. By making the value of x equal to or greater than 50 [mg-CaCO ₃ /g-fly ash], it is possible to ensure a sufficient amount of the alkali compound to be added, and to absorb the measurement error of the acid gas concentration in the exhaust gas analysis unit 131, the exhaust gas analysis unit 131 and the The time lag between the exhaust gas treatment units 11 can suppress the variation in the amount of alkali contained in the fly ash and the fly ash treatment agent from increasing.

(Fly Ash Analysis Department) Although it is not an essential form, the fly ash analysis unit 133 also constitutes the waste gas treatment agent addition management unit 13, and is arranged on the fly ash recovery unit 12 or its downstream side to analyze the alkali contained in the fly ash recovered by the fly ash recovery unit 12. Quantity is analyzed.

Then, the addition amount of the exhaust gas treatment agent is adjusted in the exhaust gas treatment agent addition management unit 13 so that the amount of alkali contained in the fly ash measured by the fly ash analysis unit 133 falls within a predetermined range.

In addition, if the fly ash analysis part 133 is located in the fly ash recovery part 12 or its downstream side, one may be arrange|positioned, and a plurality of may be arrange|positioned.

〔Exhaust gas treatment agent supply part〕 The exhaust gas treatment agent supply unit 14 supplies the exhaust gas treatment agent in the addition amount instructed by the exhaust gas treatment agent addition management unit 13 to the exhaust gas treatment unit 11 from the exhaust gas treatment agent storage unit 17 .

The exhaust gas treatment agent supply unit 14 is not particularly limited as long as it can supply a predetermined amount of exhaust gas treatment agent from the exhaust gas treatment agent storage unit 17 to the exhaust gas treatment unit 11. For example, it may include a quantitative feeder, a pump, a powder feeder.

(exhaust gas treatment agent) Exhaust gas treatment agent has the characteristic of neutralizing the acid gas in the exhaust gas (alkaline). The exhaust gas treatment agent is not particularly limited, and may be liquid or powder (solid), and must have a component whose amount can be calculated by analyzing the amount of acid in the exhaust gas.

As the exhaust gas treatment agent, when a powdery treatment agent is used, the average particle diameter thereof is preferably at least 1 μm, more preferably at least 2 μm, and still more preferably at least 5 μm. When the average particle diameter of the exhaust gas treatment agent is 1 μm or more, the powder can be appropriately brought into contact with the exhaust gas without scattering excessively. In addition, the average particle diameter of the exhaust gas treatment agent is preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less. When the average particle diameter of the exhaust gas treatment agent is 50 μm or less, a sufficiently large specific surface area of the exhaust gas treatment agent can be secured when the exhaust gas comes into contact.

The exhaust gas treating 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, calcium carbonate-carbonic acid Magnesium, Sodium Hydroxide, Sodium Bicarbonate, Sodium Carbonate, etc. A processing agent may be used individually by 1 type, and may use 2 or more types together.

Furthermore, the instruction related to the addition amount of the exhaust gas treatment agent sent from the exhaust gas treatment agent addition management unit 13 is transmitted to the exhaust gas treatment agent supply unit 14 such as a quantitative feeder provided on the upstream side of the exhaust gas treatment unit 11, for example, so that According to this instruction, the exhaust gas treatment agent supply unit 14 is operated, and a predetermined amount of the exhaust gas treatment agent is added to the exhaust gas treatment unit 11 .

〔Exhaust gas treatment agent storage part〕 Although not an essential configuration, the exhaust gas treatment system 1 of the present embodiment can also include the exhaust gas treatment agent storage unit 17 . The exhaust gas treatment agent storage unit 17 stores an exhaust gas treatment agent for treating exhaust gas, and supplies it to the exhaust gas treatment agent supply unit 14 as needed.

The exhaust gas treatment agent storage unit 17 is not particularly limited as long as the treatment agent can be stored, and for example, a storage tank or a silo can be used.

The storage capacity and shape of the exhaust gas treatment agent storage unit 17 are not particularly limited, and can be appropriately designed in consideration of its installation space, operation plan of exhaust gas treatment, amount of exhaust gas treatment, frequency of exhaust gas treatment, order frequency of treatment agent, etc.

〔Fly Ash Treatment Department〕 The fly ash processing unit 15 receives fly ash and processes the fly ash. As mentioned above, heavy metals such as lead, cadmium, arsenic, selenium, and chromium may be contained in fly ash. Therefore, it is necessary to immobilize and remove heavy metals contained in fly ash before landfilling the fly ash. Therefore, in the fly ash processing unit 15, heavy metals are removed by mixing and reacting the fly ash and the fly ash processing agent.

The fly ash treatment agent contains, for example, phosphate, and the details will be described later. This treatment agent can immobilize and remove heavy metals in the contacted fly ash by being mixed with the fly ash. The fly ash processing unit 15 is not particularly limited as long as the fly ash and the fly ash processing agent can be mixed and reacted. For example, various kneaders or reaction devices can be used.

In addition, as the fly ash, there are no particular limitations on its generation source and content, and fly ash produced by incineration of various wastes can be used.

The treatment of fly ash can be carried out in batch mode or in continuous mode. In any case, the processing amount of fly ash is not particularly limited, and can be appropriately designed in consideration of the amount of fly ash generated and the like.

〔Fly Ash Treatment Agent Storage Department〕 In the exhaust gas treatment system 1 of this embodiment, although the structure is not essential, the fly ash treatment agent storage part 19 may be included. The fly ash treatment agent storage unit 19 stores a fly ash treatment agent for treating fly ash, and supplies it to the fly ash treatment agent supply unit 16 as needed.

The fly ash processing agent storage unit 19 is not particularly limited as long as the processing agent can be stored, and for example, a storage tank or a silo can be used.

The storage capacity and shape of the fly ash treatment agent storage unit 19 are not particularly limited, and can be appropriately designed in consideration of its installation space, fly ash treatment operation plan, fly ash treatment amount, fly ash treatment frequency, and order frequency.

〔Fly Ash Treatment Agent Supply Department〕 The fly ash treatment agent supply unit 16 supplies the fly ash treatment agent having a constant volume ratio or mass ratio to the fly ash treatment unit 15 with respect to the fly ash charged in the fly ash treatment unit 15 .

In this way, the amount of the fly ash treatment agent supplied by the fly ash treatment agent supply unit 16 to the fly ash treatment unit 15 can be constant in volume ratio or mass ratio with respect to the fly ash to be treated. That is, the exhaust gas treatment system 1 of the present embodiment can analyze the properties of fly ash, for example, the amount of alkali such as alkalinity, and change the addition amount of the fly ash treatment agent accordingly, so that the configuration that is necessary in the conventional exhaust gas treatment system is omitted. The configuration of the fly ash treatment agent addition management department.

The fly ash treatment agent supply unit 16 is not particularly limited as long as it can supply a predetermined amount of the fly ash treatment agent from the fly ash treatment agent storage unit 19 to the fly ash treatment unit 11, and may include, for example, a quantitative feeder, Pumps, powder feeders.

(fly ash treatment agent) The fly ash treatment agent has the function of immobilizing and removing heavy metals in fly ash. The fly ash treatment agent is not particularly limited, and may be liquid or powder (solid).

As the fly ash treatment agent, for example, phosphoric acid-based compounds, silicon dioxide-based compounds, iron-containing compounds, acid neutralizers such as hydrochloric acid, sulfuric acid, and nitric acid can be used. From the viewpoints of properties, heavy metal immobilization ability, etc., it is preferable to use a chelating agent and a phosphate.

Phosphate-based compounds show a long-term immobilization effect of heavy metals in treatment plants, and are effective materials from the viewpoint of environmental protection. Phosphate compounds can react with lead as a heavy metal, for example, to form Pyromorphite (Pb ₅ (PO ₄ ) ₃ Cl) or Hydroxylpyromorphite (Pb ₅ (PO ₄ ) ₃ OH). The form of fixed lead.

As the phosphoric acid-based compound, any phosphoric acid compound can be used without particular limitation as long as it contains phosphoric acid, and it may be a phosphate or a mineral. Specific examples include orthophosphoric acid (orthophosphoric acid), polyphosphoric acid, metaphosphoric acid, hypophosphorous acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, superphosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate , potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, calcium dihydrogen phosphate, calcium hydrogen phosphate, magnesium dihydrogen phosphate, magnesium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, superphosphate, sodium tripolyphosphate , potassium tripolyphosphate, sodium hexametaphosphate, potassium hexametaphosphate, sodium pyrophosphate, potassium pyrophosphate, sodium phosphite, potassium phosphite, sodium hypophosphite, potassium hypophosphite. Among them, minerals having the form of orthophosphoric acid, dihydrogen phosphate, monohydrogen phosphate, phosphate, tripolyphosphate, hexametaphosphate, pyrophosphate, hydroxyapatite, especially apatite (apatite compounds) showed good heavy metal fixation effect.

Among heavy metals, phosphoric acid compounds are especially useful for immobilizing lead.

It is believed that the compound containing silica can obtain the following effects: the calcium component in fly ash reacts with silica to form calcium silicate mineral (3CaO·2SiO ₂ ·3H ₂ O), the effect of enclosing heavy metals in this mineral, and the effect of Silicon directly acts on heavy metals to generate insoluble heavy metal silicates (PbSiO ₃ , etc.) to fix the effect of heavy metals. The fixation of heavy metals containing silicon dioxide compounds is affected by the alkali content in fly ash. When the alkali content in fly ash is high, the required addition amount increases. Therefore, according to the present invention, the required addition amount can be significantly reduced even in the silica-containing compound.

The silicon dioxide-containing compound can be used without particular limitation as long as it has a SiO ₂ component, and it may be silicon dioxide itself, or a salt or a mineral.

Examples of silicon dioxide-containing compounds include silicates containing alkali metals such as sodium silicate and calcium silicate or alkaline earth metals, silica fume, silica gel, attapulgite, zeolite, bentonite, kaolin, hololite, and antigorite , pyrophyllite (pyrophyllite), talc, montmorillonite, saponite, vermiculite (vermiculite), muscovite, sodium mica (paragonite), illite, phlogopite, biotite, pearl mica (margarite), green brittle Mica, donbassite, sudoite, clinolite, oolitic chlorite, sepiolite, palygorskite, imogolite, allophane, and ferrosilicon Silicate minerals such as soil, etc.

Among heavy metals, silicon dioxide-containing compounds are especially useful for the immobilization of lead.

As an iron-containing compound, what is necessary is just to contain iron, and ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, polyferric sulfate, iron powder, etc. are mentioned.

Among heavy metals, iron-containing compounds are especially useful for the immobilization of hexavalent chromium, arsenic, selenium and mercury.

Acidic neutralizer has the effect of reducing the amount of heavy metal leaching. The acid neutralizer is also affected by the residual alkali in the fly ash. When the alkali content in the residual fly ash is large, the required addition amount will increase. Therefore, by means of the present invention, the required addition amount of the acid neutralizer can also be greatly reduced.

Examples of the acid neutralizer include hydrochloric acid, sulfuric acid, nitric acid, aluminum chloride, polyaluminum chloride, aluminum sulfate, and the like.

The acid neutralizer can be used alone, but it is preferably used in combination with the above-mentioned inorganic heavy metal fixing agent from the viewpoint of further suppressing the elution of heavy metals. In addition, when an inorganic heavy metal fixing agent and an acid neutralizing agent are used in combination, it is possible to reduce the usage-amount of an expensive inorganic heavy metal fixing agent, which is preferable.

When the fly ash treatment agent itself is liquid, it can be used directly, or it can be mixed with a solvent and diluted before use. In addition, when it is in powder form, it can be used as it is, and it can also be dispersed in a solvent to form a suspension, or dissolved in a solvent to form a solution.

＜Exhaust gas treatment method＞ The exhaust gas treatment method of this embodiment can be realized using, for example, the above-mentioned exhaust gas treatment system. Specifically, the exhaust gas treatment method of this embodiment is characterized in that it includes: at least one of the upstream side and the downstream side of the exhaust gas treatment unit 11, the exhaust gas treatment agent addition management unit 13 analyzes the acid contained in the exhaust gas. Calculate the amount of alkali contained in the fly ash to be the addition amount of the exhaust gas treatment agent within the specified range, and instruct the exhaust gas treatment agent supply part 14 to supply the calculated addition amount of the exhaust gas treatment agent; the exhaust gas treatment agent supply part 14. The step of supplying the indicated amount of the exhaust gas treatment agent to the exhaust gas treatment unit 11; the step of separating and recovering the fly ash from the exhaust gas treated by adding the exhaust gas treatment agent by the fly ash recovery unit 12; The ash treatment agent supply unit 16 is a step of supplying the fly ash treatment agent having a constant mass ratio to the fly ash treatment unit 15 with respect to the fly ash charged in the fly ash treatment unit 15 .

In the acid gas concentration meter 131 installed on the downstream side of the incinerator F, the amount of acid contained in the exhaust gas generated by incinerating waste in the incinerator F is measured, and then the exhaust gas is sent to In the reaction tube 11 as an exhaust gas treatment unit, an exhaust gas treatment agent is added to neutralize and remove the acid gas contained in the exhaust gas. Then, the exhaust gas collects and collects fly ash which is a solid content contained in the exhaust gas by the bag filter 12 serving as a fly ash recovery unit. Thereafter, the exhaust gas is sent to the exhaust gas analysis unit 132 , and the amount of acid contained in the exhaust gas is measured in the exhaust gas analysis unit 132 .

On the other hand, the exhaust gas treatment agent stored in the exhaust gas treatment agent storage silo 17 as the exhaust gas treatment agent storage part is added into the reaction tube 11 as the exhaust gas treatment part via the quantitative feeder 14 as the exhaust gas treatment agent supply part.

The exhaust gas treatment agent thus added to the reaction tube 11 reacts with the acid gas in the exhaust gas to neutralize the acid gas. The detoxified exhaust gas is discharged into the atmosphere after confirming that it is below the exhaust gas standard.

Furthermore, when performing such an exhaust gas neutralization process, the exhaust gas treatment agent addition management device 13 is provided with the exhaust gas analyzer 131 on the upstream side and the downstream side of the reaction tube 11, and the exhaust gas analyzer 131 on the downstream side. 132. Analyze the measurement results of the exhaust gas analyzer 131 and the exhaust gas analyzer 132 in the waste gas treatment agent addition management device 13, calculate the amount of the waste gas treatment agent that the amount of alkali contained in the fly ash becomes within the specified range, and use the quantitative feeder 14 Send instructions. The quantitative feeder 14 having received the instruction supplies the indicated amount of the exhaust gas treatment agent to the reaction tube 11 . Thereby, the amount of alkali contained in the fly ash falls within a predetermined range, that is, the alkali content in the fly ash collected by the bag filter 12 is also substantially constant.

On the other hand, the fly ash recovered by the bag filter 12 is temporarily stored in a fly ash storage silo (not shown). Furthermore, it is also possible not to go through the fly ash storage silo. Then, for example, the fly ash is cut out to a predetermined amount by the quantitative feeder 18 as the fly ash supply unit, and added to the mixer 15 as the fly ash processing unit.

In addition, the fly ash treatment agent stored in the fly ash treatment agent storage silo 19 as a fly ash treatment agent storage part is also added to the mixer 15 via the quantitative feeder 16 as a fly ash treatment agent supply part. In this way, the fly ash added to the mixing mixer 15 is mixed with the fly ash treatment agent, kneaded with humidification water, heavy metals are removed, and then carried out to the final treatment plant.

Here, as described above, the amount of the alkali contained in the fly ash is set within a predetermined range. Therefore, there is no need to change the amount of fly ash treatment agent added (addition ratio relative to the volume and mass of fly ash) according to the processing unit of the added fly ash, and the control of the amount of fly ash treatment agent added and the management of inventory can be eliminated The complexity of the fly ash treatment agent is realized to save manpower and to suppress the stockout (out of stock) of the fly ash treatment agent.

1: Exhaust gas treatment system 11: Exhaust gas treatment part (or reaction tube) 12: Fly ash recovery department (or bag filter) 13: Waste gas treatment agent addition management department (or waste gas treatment agent addition management device) 131, 132: Exhaust gas analysis department (or exhaust gas analyzer) 133: Fly ash analysis department (or fly ash analysis device) 14: Exhaust gas treatment agent supply part (or quantitative feeder) 15: Fly ash processing department (or mixing mixer) 16: Fly ash treatment agent supply part (or quantitative feeder) 17: Exhaust gas treatment agent storage department (or exhaust gas treatment agent storage silo) 171: Exhaust gas treatment agent residual meter (or liquid level gauge) 18: Fly ash supply part (or quantitative feeder) 19: Fly ash treatment agent storage department (or fly ash treatment agent storage silo) 191: Fly ash treatment agent residual measuring gauge (or liquid level gauge) F: Incinerator

FIG. 1 is a schematic flowchart of a construction example of an exhaust gas treatment system according to the present embodiment.

1: Exhaust gas treatment system

11: Exhaust gas treatment part (or reaction tube)

12: Fly ash recovery department (or bag filter)

13: Waste gas treatment agent addition management department (or waste gas treatment agent addition management device)

131, 132: Exhaust gas analysis department (or exhaust gas analyzer)

133: Fly ash analysis department (or fly ash analysis device)

14: Exhaust gas treatment agent supply part (or quantitative feeder)

15: Fly ash processing department (or mixing mixer)

16: Fly ash treatment agent supply part (or quantitative feeder)

17: Exhaust gas treatment agent storage department (or exhaust gas treatment agent storage silo)

171: Exhaust gas treatment agent residual meter (or liquid level gauge)

18: Fly ash supply part (or quantitative feeder)

19: Fly ash treatment agent storage department (or fly ash treatment agent storage silo)

191: Fly ash treatment agent residual measuring gauge (or liquid level gauge)

F: Incinerator

Claims (4)

An exhaust gas treatment system, comprising: an exhaust gas treatment unit, used to treat exhaust gas; a fly ash recovery unit, which separates and recovers fly ash from the treated exhaust gas; an exhaust gas treatment agent addition management unit, arranged in the waste gas treatment unit An exhaust gas treatment agent that analyzes the amount of acid contained in the exhaust gas on at least one of the upstream side and the downstream side, and calculates the amount of alkali contained in the fly ash to fall within a predetermined range based on the analyzed amount of the acid and instructs to supply the calculated addition amount of the exhaust gas treatment agent; the exhaust gas treatment agent supply unit supplies the exhaust gas treatment unit with the addition amount of the exhaust gas treatment agent instructed by the exhaust gas treatment agent addition management unit; a fly ash processing section for receiving and treating the fly ash recovered by the fly ash recovery section; and a fly ash treatment agent supply section for supplying A fly ash treatment agent having a constant mass ratio is repeatedly supplied to the fly ash treatment unit. The exhaust gas treatment system described in claim 1, wherein the fly ash treatment agent supplied to the fly ash treatment unit via the fly ash treatment agent supply unit is stored in a fly ash treatment agent storage unit. The exhaust gas treatment system described in claim 1 or claim 2, wherein the exhaust gas treatment agent addition management unit is arranged on both the upstream side and the downstream side of the exhaust gas treatment unit. A waste gas treatment method, comprising: At least upstream of the upstream side and the downstream side of the exhaust gas treatment unit, the amount of acid contained in the exhaust gas is analyzed by the exhaust gas treatment agent addition management unit, and the amount of acid contained in the fly ash is calculated based on the analyzed amount of the acid. The amount of the contained alkali becomes the addition amount of the exhaust gas treatment agent within a predetermined range, and instructs the exhaust gas treatment agent supply unit to supply the calculated addition amount of the exhaust gas treatment agent; the exhaust gas treatment agent supply unit supplies the exhaust gas treatment unit with A step of supplying the exhaust gas treatment agent in an indicated addition amount; a step of separating and recovering fly ash from the exhaust gas treated by adding the exhaust gas treatment agent by a fly ash recovery unit; and by using the fly ash treatment agent The supply unit repeats the step of supplying the fly ash treatment agent having a constant mass ratio to the fly ash treatment unit to the fly ash treatment unit.

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