JP2020006330A - Soot and dust treatment apparatus, incineration facility, and soot and dust treatment method - Google Patents

Abstract

To prevent lead and mercury from being eluted from a treated product of soot and dust.SOLUTION: A soot and dust treatment apparatus 14 treats soot and dust in exhaust gas generated in an incinerator. In the soot and dust treatment apparatus 14, a treatment agent containing slaked lime being an alkaline agent and aluminum hydroxide being a pH adjusting agent is supplied to a gas duct 20 according to a treatment agent supply unit 21. The soot and dust in the exhaust gas is collected by a dust collector 22. Water and a chelate agent is added to the collected dust removed from the dust collector 22, and kneaded in a kneader 243. The chelate agent is used after preventing lead from being eluted from the treated product of the soot and dust by using aluminum hydroxide, and thereby, lead and mercury can be prevented from being eluted from the treated product according to a small amount of the chelate agent.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technology for treating dust in exhaust gas.

  Conventionally, general waste such as municipal waste is incinerated by a waste incineration facility. Exhaust gas generated by incineration includes dust, hydrogen chloride (HCl), sulfur oxides (SOx), nitrogen oxides (NOx), and the like. Slaked lime powder is added to the exhaust gas to remove acid gases from the exhaust gas. Therefore, the collected dust shows strong alkalinity due to the effect of unreacted slaked lime. On the other hand, the exhaust gas also contains heavy metals such as harmful substances such as lead (Pb) and mercury (Hg). When dust is kneaded and used for landfill, if the treated material obtained from the dust is strongly alkaline, there is a problem that lead is eluted from the treated material.

  In order to prevent the elution of lead, a chelating agent has been conventionally added. However, large amounts of expensive chelating agents are required. The addition of the chelating agent also suppresses the elution of mercury from the processed product. However, when a large amount of a chelating agent is used to sufficiently suppress the elution of lead, a phenomenon occurs in which mercury is eluted again from the processed product.

In Patent Literature 1, by using a mixture of slaked lime having a specific surface area of 30 m ² / or more and aluminum hydroxide and / or activated alumina having an average particle diameter of 10 to 45 μm at a predetermined ratio, dust can be reduced with a small amount of agent. A technique for adjusting the pH and suppressing the elution of lead without using an expensive chelating agent is disclosed.

  Patent Literature 2 also adds fly ash, slaked lime, aluminum hydroxide or aluminum phosphate, and ferrous sulfate monohydrate to fly ash, thereby using lead, mercury, and cadmium without using a chelating agent. A technique for effectively suppressing the elution of hexavalent chromium has been disclosed.

Patent Document 3 discloses that in order to prevent lead elution, slaked lime having a specific surface area of 30 m ² / g or more and cements; at least one selected from sulfate, aluminum hydroxide, iron chloride, and phosphoric acid A powdered aluminum silicate having a specific surface area of 200 m ² / g or more; one or more chelating agents selected from dimethyldithiocarbamate, diethyldithiocarbamate, dibutyldithiocarbamate and tannic acid; Technology for treating exhaust gas by spraying a water glass; and a harmful metal stabilizer containing at least one selected from the group consisting of phosphates as a main component into an exhaust gas guide pipe attached to a waste incineration plant. Is disclosed.

JP-A-2003-311122 JP 2011-140597 A JP-A-09-099234

  By the way, when attention is paid to the elution of mercury from the treated dust, when aluminum hydroxide is added to the dust together with slaked lime, the elution of mercury is reduced. However, in some cases, elution of mercury cannot be suppressed to such an extent that the processed material can be used for landfill. In particular, when the amount of mercury contained in the garbage is large, the elution of mercury from the processed material becomes remarkable.

  The present invention has been made in view of the above problems, and has as its object to suppress the elution of lead and mercury from a treated dust.

  The invention according to claim 1 is a dust treatment device that treats dust in exhaust gas generated in an incinerator, a flue to which the exhaust gas is guided, a dust collector provided on the flue, and a dust collector. Also upstream, a treatment agent supply unit that supplies a treatment agent containing an alkaline agent and a pH adjuster to the flue, a chelate addition unit that adds a chelating agent to dust collected from the dust collector, A kneading machine for kneading the collected matter with water and the chelating agent.

  The invention according to claim 2 is the dust treatment apparatus according to claim 1, wherein the mercury concentration meter that measures the mercury concentration of the collected dust collected by the dust collector, and the mercury concentration meter that is acquired by the mercury concentration meter. A control unit configured to control an amount of the chelating agent added to the dust by the chelating unit based on the measured value.

  The invention according to claim 3 is the dust treatment device according to claim 1, wherein the mercury concentration meter that measures the concentration of mercury in the exhaust gas upstream or downstream of the dust collector, and the mercury concentration meter A control unit configured to control an amount of the chelating agent added to the dust collected by the chelating unit based on the acquired measurement value.

  The invention according to claim 4 is the dust treatment apparatus according to claim 2 or 3, wherein the amount of the chelating agent added to the collected dust is 2% by weight or less based on the dust. is there.

  The invention according to claim 5 is the dust treatment apparatus according to claim 4, wherein the amount of the chelating agent added to the dust collection material may be zero.

  The invention according to claim 6 is the dust treatment apparatus according to any one of claims 1 to 5, wherein a part of the dust collected by the dust collector is located upstream of the dust collector. It further comprises a dust return path for returning to the flue, and the treatment agent further includes activated carbon.

  The invention according to claim 7 is the dust treatment device according to any one of claims 1 to 6, wherein 3% by weight or less of the chelating agent is contained in the dust in the dust collection material. Added to dust.

  The invention according to claim 8 is an incinerator, wherein the incinerator and the dust treatment device according to any one of claims 1 to 6, which treat dust in exhaust gas generated in the incinerator. Is provided.

  The invention according to claim 9 is a dust treatment method for treating dust in exhaust gas generated in an incinerator, wherein an alkaline agent and a pH adjuster are provided upstream of a dust collector provided on a flue. The method includes a step of supplying a treating agent containing the agent to the flue, a step of adding a chelating agent to the dust collected from the dust collector, and a step of kneading the dust with water and the chelating agent.

  ADVANTAGE OF THE INVENTION According to this invention, the elution of lead and mercury from the processed dust can be suppressed.

It is a figure showing the composition of incineration equipment. It is a figure showing composition of a dust treatment device. It is a figure showing a flow of processing by a dust treatment device. It is a figure showing a flow of supply control of a mixed medicine. It is a figure showing other examples of a dust processing device. It is a figure showing the flow of control using a Hg concentration meter. It is a figure showing other examples of arrangement of a Hg concentration meter in a dust treatment device. It is a figure which shows another example of a dust treatment apparatus.

  FIG. 1 is a diagram showing a configuration of an incinerator 1 according to one embodiment of the present invention. The incineration facility 1 is a facility for incinerating waste such as municipal waste. The incinerator 1 includes an incinerator 11, a gas cooling chamber 12, a heat exchanger 13, a dust treatment device 14, and a chimney 15. These are connected by a flue 20 which is a flow path of exhaust gas. In the incinerator 11, refuse is burned. Exhaust gas generated from the incinerator 11 flows through the gas cooling chamber 12, the heat exchanger 13, and the dust treatment device 14 in order, and is discharged from the chimney 15 to the atmosphere.

  The gas cooling chamber 12 lowers the temperature of the exhaust gas by injecting water into the exhaust gas. In the heat exchanger 13, the flow path of the low-temperature gas and the flow path of the exhaust gas are in contact via a partition, and heat exchange is performed between the low-temperature gas and the exhaust gas through the partition. This further reduces the temperature of the exhaust gas. The dust treatment device 14 collects fly ash in the exhaust gas generated in the incinerator 11, takes out the fly ash, and processes the dust. In this specification, dust and fly ash are the same.

  The configuration of the incinerator 1 is not limited to that shown in FIG. 1, and the dust treatment device 14 described below is applicable to various types of incinerators 1. For example, when the incinerator 11 has a boiler, an economizer is provided in the flue 20, and the water supplied to the boiler is preheated by the economizer. The exhaust gas is guided from the economizer to the dust treatment device 14. The incinerator 1 may be provided with various devices other than the above. For example, a denitration device may be provided between the dust treatment device 14 and the chimney 15.

  FIG. 2 is a diagram illustrating a configuration of the dust treatment device 14. FIG. 3 is a diagram showing a flow of processing by the dust processing device 14. FIG. 3 shows the order of processing for dust, and in practice, the processing shown in FIG. 3 is performed continuously. The dust treatment device 14 includes a flue 20, a treatment agent supply unit 21, a dust collector 22, an HCl concentration meter 23, a kneading unit 24, and a control unit 25. The exhaust gas generated in the incinerator 11 is led to the flue 20. On the flue 20, a processing agent supply unit 21, a dust collector 22, and an HCl concentration meter 23 are sequentially provided along the flow direction of the exhaust gas.

  The treatment agent supply unit 21 includes a medicine storage unit 311, an activated carbon storage unit 312, fixed amount supply units 321 and 322, a pressure feeding unit 33, and a supply line 34. One end of the supply line 34 is connected to the pumping unit 33, and the other end is connected to the flue 20 on the upstream side of the dust collector 22. The pumping unit 33 is a blower, and sends air toward the flue 20 in the supply line 34.

The medicine storage unit 311 stores a mixture of powdered slaked lime (calcium hydroxide (Ca (OH) ₂ )) and aluminum hydroxide (Al (OH) ₃ ). Hereinafter, this mixture is referred to as “mixed medicine”. Slaked lime is an alkaline agent for desalination and desulfurization. Aluminum hydroxide is a pH adjuster for adjusting the pH of dust. The mixing ratio of slaked lime and aluminum hydroxide is 65:35 (weight ratio). The mixing ratio of slaked lime and aluminum hydroxide is not limited to this, and the mixing ratio is preferably 50:50 to 80:20, and more preferably 60:40 to 70:30.

  A fixed amount supply unit 321 is attached to a lower part of the medicine storage unit 311. The fixed amount supply unit 321 is, for example, a table feeder. The outlet of the table feeder is connected to the supply line 34. From the outlet of the fixed quantity supply unit 321, a set amount of the mixed medicine per unit time is taken out from the medicine storage unit 311. As a result, a fixed amount of the mixed medicine is supplied to the supply line 34 per unit time.

  Activated carbon storage section 312 stores activated carbon powder. Activated carbon is used to remove dioxins and mercury. A fixed amount supply unit 322 is attached to a lower portion of the activated carbon storage unit 312. The fixed amount supply unit 322 has the same structure as the fixed amount supply unit 321. A set amount of activated carbon per unit time is taken out of the activated carbon storage unit 312 from the outlet of the fixed quantity supply unit 322. As a result, a constant amount of activated carbon is supplied to the supply line 34 per unit time.

  Slaked lime, aluminum hydroxide, and activated carbon are supplied by the treatment agent supply unit 21 so as to blow into the flue 20 upstream of the dust collector 22 (step S11). In the following description, substances supplied to the flue 20 upstream of the dust collector 22, such as the above-mentioned mixed chemicals and activated carbon, are collectively referred to as "treatment agents". The treatment agent supply unit 21 may supply other treatment agents to the flue 20.

  The dust collector 22 is of a filtration type, for example, and removes dust contained in exhaust gas with a filter cloth. The filter cloth is also called a bag filter. The treatment agent supplied by the treatment agent supply unit 21 accumulates on the filter cloth together with the dust (step S12). When the exhaust gas passes through the filter cloth, a reaction between the harmful substance contained in the exhaust gas and the treating agent occurs, and most of the harmful substance is removed from the exhaust gas. The reaction between the exhaust gas and the treating agent also occurs in the flue 20 upstream of the dust collector 22. The harmful substances removed by the treating agent are, for example, hydrogen chloride, sulfur oxides, dioxins, mercury compounds and the like.

  In the dust collector 22, the dust and the treatment agent (including a reaction product with a harmful substance) deposited on the filter cloth are removed at regular intervals by backwashing using compressed air. Hereinafter, dust and the like collected by the dust collector 22 and taken out from the dust collector 22 will be referred to as “dust collected”. The collected dust is thrown into the kneading unit 24 from the filter cloth.

  The kneading section 24 includes a silo 241, a fixed-quantity supply section 242, a kneader 243, a chelate adding section 244, a water adding section 245, a curing conveyor 246, and a processed pit 247. Dust is accumulated in the silo 241. The fixed amount supply unit 242 is, for example, a table feeder. The outlet of the table feeder is connected to the kneader 243. The kneading machine 243 is supplied with a liquid chelating agent from a chelating unit 244 and water from a water adding unit 245. Thereby, water and a chelating agent are added to the dust collected by the kneading machine 243 (step S13). The kneading machine 243 kneads the collected matter with water and a chelating agent (step S14). The addition of the water and the chelating agent to the dust may be performed before the kneader 243.

  The chelating addition section 244 includes a tank for storing the chelating agent, and a valve for adjusting the supply amount of the chelating agent from the tank to the kneader 243. The water addition unit 245 includes a tank for storing water, and a valve for adjusting a supply amount of water from the tank to the kneading machine 243. Other structures may be adopted as the chelating unit 244 and the water adding unit 245. For example, a pump that supplies a constant amount of liquid per unit time may be used. The kneading machine 243 has a screw-shaped kneading rod and guides the collected dust in a certain direction while kneading. The processed material that is the kneaded material discharged from the kneading machine 243 is conveyed by the curing conveyor 246 and falls into the processed material pit 247. Processing objects are accumulated in the processing object pit 247.

  An HCl concentration meter 23 that measures the chlorine concentration of the exhaust gas is disposed downstream of the dust collector 22 on the flue 20. The HCl concentration meter 23 measures the concentration of hydrogen chloride in the exhaust gas (hereinafter, referred to as “HCl concentration”) using, for example, a laser beam. The HCl concentration is output to the control unit 25. The control unit 25 controls the processing agent supply unit 21 based on the HCl concentration. The control unit 25 also performs overall control of the dust treatment device 14.

  FIG. 4 is a diagram showing a flow of the supply control of the mixed medicine. When the HCl concentration in the exhaust gas is measured by the HCl concentration meter 23 (step S21), in principle, the supply amount of the mixed chemical is determined such that the higher the HCl concentration, the larger the supply amount per unit time (step S22). . As a result, control is performed so as to follow the HCl concentration that changes in accordance with the type of dust put into the incinerator 11. For example, when the HCl concentration acquired by the HCl concentration meter 23 is higher than a predetermined set value, the control unit 25 increases the supply amount of the mixed medicine, and when the HCl concentration is lower than the predetermined set value, Reduce the supply of mixed medicine.

Next, the effect of the processing by the dust processing device 14 will be described. Lead does not elute when the pH is lowered to about 10. When aluminum hydroxide is added to the dust together with slaked lime, Friedel's salt (3CaO.Al ₂ O ₃ .CaCl ₂ .10H ₂ O) is formed, so that the Ca ion concentration of the treated material is reduced. Accordingly, pH is lowered, Pb (OH) ₄ ^2- solubility decreases. Further, since Friedel's salt is a kind of cement hydrate, it is presumed that lead is immobilized with Friedel's salt in addition to the effect of pH reduction. Just as lead is solidified by Friedel's salt, it is assumed that other heavy metals such as mercury are also immobilized to some extent.

  However, with aluminum hydroxide alone, it is possible to effectively suppress the elution of lead from the treated product, but it may not be possible to sufficiently suppress the elution of mercury. In particular, when the amount of mercury contained in the garbage is large, it is difficult to keep the amount of mercury eluted within an allowable range for using the treated material for landfill.

  On the other hand, in the dust treatment device 14, by adding a small amount of the chelating agent at the time of kneading, the elution of mercury can be effectively suppressed while minimizing the amount of the expensive chelating agent used. In the dust treatment device 14, a chelating agent is added at 3% by weight or less, preferably 2% by weight or less based on the dust. From the test results described below, it is possible to add a chelating agent at 1% by weight or less based on the dust. Here, the "addition rate of the chelating agent to the dust" is the weight% of the chelating agent to the dust containing no slaked lime, aluminum hydroxide and activated carbon.

  In the dust treatment device 14, the supply amount of the mixed chemical is controlled based on the HCl concentration. Therefore, it is considered preferable to supply slaked lime and aluminum hydroxide to the flue 20 at a fixed ratio in order to set the pH of the treated product to a value at which lead does not elute. Therefore, in the dust treatment apparatus 14, a mixture of slaked lime and aluminum hydroxide is prepared in advance as a mixed agent. Of course, the supply amounts of slaked lime and aluminum hydroxide per unit time may be individually controlled.

  In the case where the elution of lead is prevented only by a chelating agent as in the past, for example, about 5 to 10% by weight of a chelating agent is added to dust in order to sufficiently suppress the elution of lead to various kinds of dust. are doing. However, the amount of the chelating agent exceeds the amount suitable for suppressing the elution of mercury, and there is a problem that mercury is re-eluted. In addition, since the chelating agent is expensive, the processing cost increases. On the other hand, in the dust treatment device 14, the elution of lead and mercury can be sufficiently suppressed with a small amount of the chelating agent, and the processing cost can be reduced.

  Next, a description will be given of a test example in which slaked lime and aluminum hydroxide are added to dust in a flue and a chelating agent is added at the time of kneading.

  Table 1 shows the measurement results of the relationship between the addition ratio of aluminum hydroxide and the elution amounts of lead and mercury for dust having a mercury content of 28 mg / kg and a lead content of 930 mg / kg contained in the dust. . The mixing ratio (weight ratio) of slaked lime and aluminum hydroxide is 65:35 (the same applies to other test examples). The test was carried out in accordance with a dissolution test according to the 13th method notified by the Environment Agency in 1973, after the kneaded material of the dust was closed and cured for 1 day, spread in a vat for 1 day and air-cured. When the lead elution standard is 0.3 mg / L, it can be seen that the lead elution standard is satisfied by adding 25% by weight or more of aluminum hydroxide. Here, the “addition ratio of aluminum hydroxide to dust” is the weight percentage of aluminum hydroxide to dust that does not contain slaked lime and activated carbon.

  Table 2 shows the measurement results of the relationship between the addition rate of the chelating agent and the elution amounts of lead and mercury in the case of adding 30% by weight of aluminum hydroxide to the above dust. When the standard for elution of mercury is 0.005 mg / L, it can be seen that the standard for elution of mercury is satisfied by adding 2% by weight or more of a chelating agent. In addition, although the test of adding 1% by weight of the chelating agent was not performed, as shown in other test results, the effect can be obtained by adding a small amount of the chelating agent by using aluminum hydroxide in combination with the chelating agent. Therefore, it is estimated that the addition of 1% by weight of the chelating agent satisfies the mercury elution standard.

  Table 3 shows the relationship between the aluminum hydroxide addition rate and the elution amounts of lead and mercury for dust having a mercury content of 13.2 mg / kg and a lead content of 1,019 mg / kg contained in the dust. The measurement results are shown. When the lead elution standard is 0.3 mg / L, it can be seen that the lead elution standard is satisfied by adding 25% by weight or more of aluminum hydroxide. In addition, since the measurement method is different from the case of Table 1, the lower limit of measurement is different from Table 1.

  Table 4 shows the measurement results of the relationship between the addition rate of the chelating agent and the elution amounts of lead and mercury in the case where 30% by weight of aluminum hydroxide was added to the above dust. When the elution standard of mercury is 0.005 mg / L, it can be understood that the elution standard of mercury is satisfied by adding 1% by weight or more of the chelating agent.

  Table 5 shows the relationship between the addition ratio of aluminum hydroxide and the elution amounts of lead and mercury for dust having a mercury content of 45.4 mg / kg and a lead content of 1,361 mg / kg contained in the dust. The measurement results are shown. When the lead elution standard is 0.3 mg / L, it can be seen that the lead elution standard is satisfied by adding 25% by weight or more of aluminum hydroxide.

  Table 6 shows the measurement results of the relationship between the addition rate of the chelating agent and the elution amounts of lead and mercury in the case of adding 30% by weight of aluminum hydroxide to the above-mentioned dust. When the elution standard of mercury is 0.005 mg / L, it can be understood that the elution standard of mercury is satisfied by adding 1% by weight or more of the chelating agent.

  In view of the above, lead and mercury from treated dust are added to various dusts by adding 25% by weight or more of aluminum hydroxide to the flue 20 and adding 2% by weight of a chelating agent during kneading. It can be seen that the elution of can be sufficiently suppressed.

  Also, even if various types of waste are considered, it is estimated that aluminum hydroxide may be added in an amount of 30% by weight or more based on the dust. Of course, the smaller the amount of addition of the chemical, the better, so that the addition ratio of aluminum hydroxide is preferably 40% by weight or less, more preferably 30% by weight or less. According to the test results, depending on the nature of the refuse, the addition ratio of aluminum hydroxide can be set to 25% by weight or less.

  The use amount of the chelating agent is preferably small, and in order to cope with the case where a large amount of mercury is contained in the refuse, the addition amount of the chelating agent is preferably 3% by weight or less based on the dust. However, based on the above test results, the addition amount of the chelating agent can be set to 2% by weight or less based on the dust, or 1% by weight or less.

  Table 7 shows the results of an investigation on the dissolution of various heavy metals other than lead. The dust used in the test had a mercury content of 14 mg / kg and a lead content of 1,700 mg / kg. 30% by weight of aluminum hydroxide was added to the dust, and 3% by weight of a chelating agent was added and kneaded. From Table 7, it can be seen that elution is sufficiently suppressed for other various heavy metals. In addition, no test has been conducted in which the content of the chelating agent is less than 3%, but it is presumed that sufficient effects can be obtained even if the content is less than 3%.

  A variety of chelating agents can be used, but if it is available for refuse incineration facilities, it is considered that there is no significant difference, so the above addition rates are those available for refuse incineration facilities. Applicable to More precisely, the chelating agent used in the above test is Ash Ace L-5100 (20) (Hitachi Zosen Corporation), and the above-mentioned addition rate is applicable to a chelating agent having the same level of performance. is there.

  FIG. 5 is a view showing another example of the dust treatment device 14, and shows only a part of the dust treatment device 14. The dust treatment device 14 in FIG. 5 is obtained by adding a mercury concentration meter (hereinafter, referred to as “Hg concentration meter”) 261 and a sampling device 262 to the one shown in FIG. The other configuration is the same as that of FIG. 2 and a part of the configuration is omitted. The sampling device 262 takes out a part of the dust before the supply of the chelating agent as a sample and supplies it to the Hg concentration meter 261. The Hg concentration meter 261 measures the concentration of mercury in the sample, that is, the concentration of mercury in the dust (hereinafter, referred to as “Hg concentration”).

  Various types can be used as the Hg concentration meter 261. The measurement method of the Hg concentration meter 261 may be a heating vaporization method or a reduction vaporization method. The measurement principle may be an atomic absorption method or an atomic fluorescence method. The sampling device 262 may be provided at any position before the chelating agent is supplied to the dust collection material. The sample collection device 262 may be provided in any of the silo 241, the quantitative supply unit 242, and the kneader 243, or may be provided between these components.

  FIG. 6 is a diagram showing a flow of control using the Hg concentration meter 261. The measurement value obtained by the Hg concentration meter 261 is input to the control unit 25 (Step S21). The control unit 25 controls the amount of the chelating agent added to the dust by the chelating unit 244 based on the measured value (step S22). Thereby, an expensive chelating agent can be used efficiently according to the amount of mercury contained in the refuse. As described above, since the elution of lead from the treated product is suppressed by aluminum hydroxide, the necessary chelating agent is small, and the amount of the chelating agent used can be reduced by controlling using the Hg concentration meter 261. It can be further reduced.

  With the control using the Hg concentration meter 261, when the amount of mercury contained in the garbage is small, the amount of the chelating agent used can be set to 2% by weight based on the dust during the normal operation. That is, in the dust treatment apparatus 14, preferably, the amount of the chelating agent added to the dust may be 2% by weight or less based on the dust. More preferably, the amount of the chelating agent added to the dust may be 1% by weight or less based on the dust. When the amount of mercury contained in the garbage is even smaller, the amount of the chelating agent used can be reduced to 0 during normal operation. That is, in the dust treatment apparatus 14, preferably, the amount of the chelating agent added to the collected dust may be zero.

  FIG. 7 is a diagram illustrating another arrangement example of the Hg concentration meter 261 in the dust treatment device 14. FIG. 7 shows only a part of the dust treatment device 14, and the Hg concentration meter 261 is provided on the flue 20 downstream of the dust collector 22. Other configurations are the same as those in FIG. A part of the exhaust gas is guided to the Hg concentration meter 261 and the mercury concentration of the exhaust gas (hereinafter, referred to as “Hg concentration”) is measured. Various devices can be used as the Hg concentration meter 261 as in the case of FIG. The Hg concentration meter 261 may be provided at any position as long as it can measure the Hg concentration of the exhaust gas, and may be provided on the flue 20 upstream of the dust collector 22. For example, the Hg concentration meter 261 is provided on the flue 20 upstream of a position where the processing agent is supplied from the processing agent supply unit 21 to the flue 20.

  The flow of control using the Hg concentration meter 261 is the same as in FIG. That is, the measured value obtained by the Hg concentration meter 261 is input to the control unit 25 (step S21), and the control unit 25 determines the amount of the chelating agent added to the dust collected by the chelate adding unit 244 based on the measured value. Is controlled (step S22). Thus, the amount of the chelating agent used can be reduced. In the case of FIG. 5, the amount of the chelating agent determined based on the Hg concentration is quickly added to the dust, but in the case of FIG. After 1-2 days, the mixture is guided to the kneader 243. Therefore, the addition amount of the chelating agent determined based on the Hg concentration is used at the time of addition of the chelating agent after the elapse of the predetermined time from the measurement. In the dust treatment apparatus 14, preferably, the amount of the chelating agent added to the collected dust may be 2% by weight or less based on the dust, more preferably 1% by weight or less, most preferably. May be 0.

  FIG. 8 is a diagram showing still another example of the dust treatment device 14. FIG. 8 shows only a part of the dust treatment device 14. The dust treatment device 14 is the same as that shown in FIG. 2 except that a dust return path 4 is added. Further, the supply control of the chelating agent using the Hg concentration meter 261 shown in FIGS. 5 and 7 may be performed.

  The dust return path 4 returns a part of the dust collected by the dust collector 22 to the flue 20 upstream of the dust collector 22. The dust return path 4 includes a storage unit 41, a fixed amount supply unit 42, a conveyor 43, and a chute unit 44. From the fixed amount supply unit 242 disposed below the silo 241, a part of the collected dust can be discharged via the opening and closing unit, and the discharged collected dust is stored in the storage unit 41. A fixed amount supply unit 42 is attached to a lower part of the storage unit 41. The fixed amount supply unit 42 is, for example, a table feeder, and extracts a set amount of collected dust per unit time from the storage unit 41. The fixed amount supply unit 42 is connected to the conveyor 43, and the dust collected from the fixed amount supply unit 42 is transported on the conveyor 43. The conveyor 43 is, for example, a flight conveyor. The conveyor 43 returns the collected dust to a position on the flue 20 between the treatment agent supply unit 21 and the dust collector 22. The chute section 44 throws the collected dust into the flue 20.

  By charging the collected dust into the flue 20, unused slaked lime and unused activated carbon in the collected dust can be used. Further, based on the measured values of the HCl concentration meter 23 and the Hg concentration meter 261, the control unit 25 controls the supply amounts of the mixed chemical, activated carbon, and dust to the flue 20. As a result, the amount of dust can be reduced and the concentration of Hg in the dust can be increased, as compared with the case where a large amount of activated carbon is used without circulating the dust. The chelating agent can be efficiently used for mercury. As a result, the amount of the chelating agent used can be further reduced.

  Various modifications are possible in the dust treatment device 14.

As the pH adjuster, aluminum phosphate (AlPO ₄ ) or the like may be used instead of aluminum hydroxide. As the alkaline agent, caustic soda (NaOH), dolomite hydroxide (Ca (OH) ₂ .Mg (OH) ₂ ) or the like may be used instead of slaked lime.

  Instead of separately supplying the mixed chemical and the activated carbon to the flue 20, a treating agent in which these are mixed in advance may be supplied to the flue 20. Another mechanism may be adopted as a mechanism for supplying a treatment agent such as a mixed chemical or activated carbon to the flue 20. For example, the treatment agent may be transported by a conveyor and supplied to the flue 20.

  The HCl concentration meter 23 can be provided on the flue 20 on the upstream side of the dust collector 22. In the dust return path 4, the collected dust may be transported to the flue 20 using a carrier gas such as air. The chelating agent need not be added to the dust at the same time as the water, but may be added separately.

  The dust treatment device 14 may be used in incineration facilities other than the incineration facility 1 that incinerates refuse.

  The configurations in the above embodiment and each modified example may be appropriately combined as long as they do not conflict with each other.

REFERENCE SIGNS LIST 1 incinerator 4 dust return path 11 incinerator 14 dust treatment device 20 flue 21 treatment agent supply unit 22 dust collector 25 control unit 243 kneader 244 chelate addition unit 261 Hg concentration meter (mercury concentration meter)
S11 to S14 Step

The invention according to claim 1 is a dust treatment device that treats dust in exhaust gas generated in an incinerator, a flue to which the exhaust gas is guided, a dust collector provided on the flue, and a dust collector. Also upstream, a treatment agent supply unit that supplies a treatment agent containing an alkaline agent and a pH adjuster to the flue, a chelate addition unit that adds a chelating agent to dust collected from the dust collector, A kneader that kneads the dust with water and the chelating agent, a mercury concentration meter that measures the mercury concentration of the dust collected by the dust collector , and based on a measurement value obtained by the mercury concentration meter. A control unit that controls the amount of the chelating agent added to the dust by the chelating unit .

The invention according to claim 2 is a dust treatment device that treats dust in exhaust gas generated in an incinerator, a flue to which the exhaust gas is guided, a dust collector provided on the flue, and a dust collector. Also upstream, a treatment agent supply unit that supplies a treatment agent containing an alkaline agent and a pH adjuster to the flue, a chelate addition unit that adds a chelating agent to dust collected from the dust collector, A kneader that kneads the dust with water and the chelating agent, a mercury concentration meter that measures the concentration of mercury in the exhaust gas upstream or downstream of the dust collector, and a measurement value obtained by the mercury concentration meter. based on, obtain Preparations and a control unit for controlling the addition amount of the chelating agent to the dust collection thereof by the chelate adding unit.

The invention according to claim 3 is the dust treatment apparatus according to claim 1 or 2 , wherein the amount of the chelating agent added to the collected dust is 2% by weight or less based on the dust. is there.

According to a fourth aspect of the present invention, there is provided the dust treatment apparatus according to the third aspect , wherein the amount of the chelating agent added to the collected dust may be zero.

The invention according to claim 5 is the dust treatment device according to any one of claims 1 to 4 , wherein a part of the dust collected by the dust collector is located upstream of the dust collector. It further comprises a dust return path for returning to the flue, and the treatment agent further includes activated carbon.

The invention according to claim 6 is the dust treatment device according to any one of claims 1 to 5 , wherein 3% by weight or less of the chelating agent is contained in the dust in the dust collection material. Added to dust.

The invention according to claim 7 is an incinerator, wherein the incinerator and the dust treatment device according to any one of claims 1 to 6 that treats dust in exhaust gas generated in the incinerator. Is provided.

The invention according to claim 8 is a dust treatment method for treating dust in exhaust gas generated in an incinerator, wherein an alkaline agent and a pH adjuster are provided upstream of a dust collector provided on a flue. Supplying a treating agent containing the chelating agent to the flue, adding a chelating agent to the dust collected from the dust collector, kneading the collected dust with water and the chelating agent , and Measuring the mercury concentration of the collected dust by a mercury concentration meter, and based on the measurement value obtained by the mercury concentration meter, based on the measured value obtained by the mercury concentration meter. Controlling the amount of the chelating agent added .
The invention according to claim 9 is a dust treatment method for treating dust in exhaust gas generated in an incinerator, wherein an alkaline agent and a pH adjuster are provided upstream of a dust collector provided on a flue. Supplying a treating agent comprising the flue gas to the flue, adding a chelating agent to the dust collected from the dust collector, kneading the dust collected together with water and the chelating agent, and A step of measuring the concentration of mercury in the exhaust gas at an upstream or downstream side with a mercury concentration meter, and based on the measurement value obtained by the mercury concentration meter, based on the measurement value obtained by the mercury concentration meter; And controlling the amount of addition.

The invention according to claim 1 is a dust treatment device that treats dust in exhaust gas generated in an incinerator that incinerates refuse, and a flue to which the exhaust gas is guided, and a dust collector provided on the flue. Upstream of the dust collector, a treatment agent supply unit for supplying a treatment agent containing an alkaline agent and a pH adjuster to the flue, and chelate addition for adding a chelating agent to the dust collected from the dust collector , A kneader for kneading the dust with water and the chelating agent, a mercury concentration meter for measuring the mercury concentration of the dust collected by the dust collector, and a measurement obtained by the mercury concentration meter A control unit that controls an amount of the chelating agent added to the dust by the chelating unit based on the value.

The invention according to claim 2 is a dust treatment device that treats dust in exhaust gas generated in an incinerator that incinerates refuse, and a flue to which the exhaust gas is guided, and a dust collector provided on the flue. Upstream of the dust collector, a treatment agent supply unit for supplying a treatment agent containing an alkaline agent and a pH adjuster to the flue, and chelate addition for adding a chelating agent to the dust collected from the dust collector Part, a kneader for kneading the dust collection material with water and the chelating agent, a mercury concentration meter for measuring the concentration of mercury in the exhaust gas upstream or downstream of the dust collector, and a mercury concentration meter obtained by the mercury concentration meter. And a control unit for controlling the amount of the chelating agent added to the dust by the chelating unit based on the measured value.

The invention according to claim 7 is an incineration facility, wherein the incinerator for incinerating waste and the dust in exhaust gas generated in the incinerator are treated. A dust treatment device.

The invention according to claim 8 is a dust treatment method for treating dust in exhaust gas generated in an incinerator for incineration of refuse, wherein an alkaline agent and a pH are set upstream of a dust collector provided on a flue. Supplying a treating agent containing a conditioning agent to the flue, adding a chelating agent to the dust collected from the dust collector, and kneading the dust with water and the chelating agent; and Measuring the mercury concentration of the dust collected by the dust collector with a mercury concentration meter, and adding the chelating agent based on the measurement value obtained by the mercury concentration meter. Controlling the amount of the chelating agent added to the product.
The invention according to claim 9 is a dust treatment method for treating dust in exhaust gas generated in an incinerator for incinerating refuse, wherein an alkaline agent and a pH are set upstream of a dust collector provided on a flue. Supplying a treating agent containing a conditioning agent to the flue, adding a chelating agent to the dust collected from the dust collector, and kneading the dust with water and the chelating agent; and Measuring the concentration of mercury in the exhaust gas with a mercury concentration meter upstream or downstream of the dust collector, and based on the measurement value obtained by the mercury concentration meter, Controlling the amount of the chelating agent to be added.

Claims (9)

A dust treatment device that treats dust in exhaust gas generated in an incinerator,
The flue from which the exhaust gas is led,
A dust collector provided on the flue,
Upstream from the dust collector, a treatment agent supply unit that supplies a treatment agent containing an alkaline agent and a pH adjuster to the flue,
A chelate addition unit for adding a chelating agent to the dust collected from the dust collector;
A kneader for kneading the collected matter with water and the chelating agent,
A dust treatment device comprising: The dust treatment device according to claim 1,
A mercury concentration meter that measures the mercury concentration of the collected dust collected by the dust collector,
A control unit that controls an addition amount of the chelating agent to the dust collected by the chelate addition unit based on a measurement value obtained by the mercury concentration meter,
A dust treatment device, further comprising: The dust treatment device according to claim 1,
A mercury concentration meter that measures the concentration of mercury in the exhaust gas upstream or downstream of the dust collector,
A control unit that controls an addition amount of the chelating agent to the dust collected by the chelate addition unit based on a measurement value obtained by the mercury concentration meter,
A dust treatment device, further comprising: The dust treatment device according to claim 2 or 3,
A dust treatment apparatus, wherein the amount of the chelating agent added to the collected dust is 2% by weight or less based on the dust. The dust treatment device according to claim 4,
A dust treatment apparatus, wherein the amount of the chelating agent added to the collected matter may become zero. It is a dust treatment device according to any one of claims 1 to 5,
A dust return path for returning a part of the dust collected by the dust collector to the flue upstream of the dust collector;
The dust treatment device, wherein the treatment agent further includes activated carbon. The dust treatment device according to any one of claims 1 to 6, wherein
A dust treatment apparatus, wherein 3% by weight or less of the chelating agent is added to the dust collected with respect to the dust in the collected dust. Incineration equipment,
An incinerator,
The dust treatment apparatus according to any one of claims 1 to 6, which treats dust in exhaust gas generated in the incinerator.
An incineration facility comprising: A dust treatment method for treating dust in exhaust gas generated in an incinerator,
Upstream of a dust collector provided on the flue, supplying a treatment agent containing an alkaline agent and a pH adjuster to the flue,
A step of adding a chelating agent to the dust collected from the dust collector;
Kneading the dust with water and the chelating agent,
A dust treatment method, comprising:

Images