JP6016205B1 - Exhaust gas treatment apparatus and exhaust gas treatment method - Google Patents

Abstract

It is an object of the present invention to provide an exhaust gas treatment apparatus and method for reliably adsorbing and removing mercury in exhaust gas from a furnace and supplying activated carbon with an appropriate amount of activated carbon even when the mercury concentration in the exhaust gas fluctuates. A dust collector 4 for removing dust from the exhaust gas containing mercury from the furnace 1 is provided at a downstream position with respect to the furnace 1, and an activated carbon supply device 3 that blows activated carbon into an exhaust gas passage that guides exhaust gas from the furnace 1 to the dust collector 4. In the exhaust gas treatment apparatus provided, a mercury concentration meter 5 for measuring the mercury concentration in the exhaust gas is provided on the downstream side of the dust collector 4, and the downstream side of the dust collector 4 based on the measurement value by the mercury concentration meter 5. Is provided with a control device 7 for controlling the supply amount of the activated carbon while maintaining a predetermined minimum value so that the mercury concentration in the exhaust gas at or below is kept below the set value.

Description

  The present invention relates to a treatment apparatus and a treatment method for exhaust gas containing mercury discharged from various factories such as a waste incineration facility, a cement manufacturing factory, a thermal power plant, and a non-ferrous metal smelting factory.

  Mercury may be contained in exhaust gas discharged from cement kiln furnaces and non-ferrous metal smelting furnaces, and wastes containing mercury incinerated in waste incinerators, and are released directly into the atmosphere. It causes air pollution and becomes a problem. Therefore, it is required to remove mercury in the exhaust gas.

  Furthermore, the Minamata Convention on Mercury was adopted in 2013, and global movements to strengthen mercury management are in progress. After the convention enters into force, measures to reduce mercury emissions are being considered for facilities subject to mercury emission control. Facilities subject to mercury emission regulations include coal-fired power plants, coal-fired boilers, non-ferrous metal smelting facilities, waste incineration facilities, and cement manufacturing facilities. Under such circumstances, there is an increasing demand for a treatment method for efficiently removing mercury in exhaust gas discharged from these facilities.

  For example, as a general method for removing mercury in exhaust gas discharged from waste incinerators and boiler furnaces, bag filters that remove dust in exhaust gas, ducts that lead exhaust gas to an electric dust collector, bag filters, etc. On the other hand, Patent Documents 1 and 2 disclose a method in which powdered activated carbon is blown at an upstream position, mercury is adsorbed on the activated carbon, and the activated carbon on which the mercury is adsorbed is collected together with dust with a bag filter or the like and removed from the exhaust gas. Are known.

  Also, prepare a mixed powder in which activated carbon is mixed in advance with slaked lime to neutralize and remove the acidic gas in the exhaust gas. The mixed powder is blown into the duct on the upstream side of the bag filter, and the acidic gas and There is a case where a reaction product of slaked lime and activated carbon adsorbed with mercury are collected together with dust by a bag filter or the like and processed. Thus, after mercury in the exhaust gas is adsorbed by the activated carbon, it is collected and removed by a bag filter or the like.

  In Patent Document 2, a dust collector is provided in the middle of a flue through which exhaust gas containing mercury is circulated, and an activated carbon injection device for introducing activated carbon into the flue upstream of the dust collector is attached. A mercury removal system in exhaust gas in which a large amount of activated carbon is instantaneously charged when the mercury concentration exceeds a predetermined concentration is disclosed.

JP2010-221085 JP 2014-213308 A

  Depending on the type of waste incinerated in the incinerator and the type of raw material smelted in the cement kiln furnace or non-ferrous metal smelting furnace, fluctuations may occur that temporarily increase the mercury concentration in the exhaust gas. There is. In this case as well, in order to keep the mercury concentration in the exhaust gas discharged from the chimney low, it is necessary to constantly blow in a large amount of activated carbon to be blown into the duct, or mixed powder in which slaked lime and activated carbon are mixed in advance. When supplying into the duct, it is necessary to constantly blow a large amount of the mixed powder.

  Thus, if activated carbon or mixed powder is constantly supplied in a large amount into the duct assuming a temporarily high mercury concentration, the activated carbon and the mixed powder are excessively used in many time zones excluding the temporary time zone. As a result, the amount of activated carbon or mixed powder used is increased, and the exhaust gas treatment cost is increased, and the amount of collected dust is increased, resulting in an increase in the dust removal cost. In the mercury removal system in exhaust gas described in Patent Document 2, activated carbon is charged only when the mercury concentration in the exhaust gas exceeds a predetermined concentration, and the mercury is adsorbed and removed by depositing on the filter cloth in the dust collector. The use of useless activated carbon can be avoided, but there is a concern that the activated carbon layer cannot be sufficiently formed on the filter cloth and mercury cannot be adsorbed and removed simply by momentarily charging the activated carbon.

  In view of such circumstances, the present invention reliably adsorbs and removes mercury in exhaust gas, and even if the mercury concentration in the exhaust gas fluctuates, the exhaust gas treatment apparatus and exhaust gas treatment method supply activated carbon with an appropriate amount of activated carbon. It is an issue to provide.

  According to the present invention, the above-described problems are solved by the following exhaust gas treatment apparatus and the method thereof.

[Exhaust gas treatment equipment]
The exhaust gas treatment apparatus of the present invention is configured as in the following first invention, second invention and third invention, and the above-mentioned problems can be solved by any of them.

<First invention>
An exhaust gas treatment apparatus comprising: a dust collector that removes exhaust gas containing mercury discharged from a furnace; and an activated carbon supply device that blows the activated carbon into an exhaust gas passage that guides the exhaust gas from the furnace to the dust collector, on the downstream side of the dust collector A downstream mercury concentration meter that measures the mercury concentration in the exhaust gas and a control device that controls the activated carbon supply amount of the activated carbon supply device, the control device maintains the activated carbon supply amount above a predetermined minimum value, An exhaust gas treatment apparatus, wherein the supply amount of activated carbon is controlled so that the mercury concentration in the exhaust gas on the downstream side of the dust collector is not more than a set value based on a measured value of mercury concentration by a side mercury concentration meter.

<Second invention>
An exhaust gas treatment apparatus comprising: a dust collector that removes exhaust gas containing mercury discharged from a furnace; and an activated carbon supply device that blows activated carbon into an exhaust gas passage that guides the exhaust gas from the furnace to the dust collector. Equipped with an upstream mercury concentration meter that measures the mercury concentration in the exhaust gas upstream of the dust collector, and a control device that controls the activated carbon supply amount of the activated carbon supply device. And the activated carbon supply amount is controlled so that the mercury concentration in the exhaust gas on the downstream side of the dust collector is not more than the set value based on the mercury concentration measured by the upstream mercury concentration meter. Exhaust gas treatment equipment.

<Third invention>
An exhaust gas treatment apparatus comprising: a dust collector that removes exhaust gas containing mercury discharged from a furnace; and an activated carbon supply device that blows activated carbon into an exhaust gas passage that guides the exhaust gas from the furnace to the dust collector. An upstream mercury concentration meter that measures the mercury concentration in the exhaust gas upstream of the dust collector, a downstream mercury concentration meter that measures the mercury concentration in the exhaust gas downstream of the dust collector, and the activated carbon supply of the activated carbon supply device A control device is provided to control the amount, and the control device maintains the activated carbon supply amount above a predetermined minimum value, and also converts the mercury concentration measurement value by the upstream mercury concentration meter and the mercury concentration measurement value by the downstream mercury concentration meter. Based on the above, the exhaust gas treatment apparatus, wherein the activated carbon supply amount is controlled so that the mercury concentration in the exhaust gas on the downstream side of the dust collector is not more than a set value.

  In the first to third inventions, when the mercury concentration measurement value by the upstream mercury concentration meter or the downstream mercury concentration meter is equal to or higher than the predetermined mercury concentration, the control device maintains the activated carbon supply amount at a predetermined maximum value. It is preferable to control. Although the mercury concentration is not so high as a time average, when the mercury concentration suddenly increases temporarily, if a large amount of activated carbon is supplied in accordance with this high mercury concentration, the activated carbon will be excessively excessive over the subsequent time. The result will be to supply. Such excessive supply can be prevented by controlling the supply amount of the activated carbon so as to keep the predetermined maximum value.

  In the first aspect of the invention, the control device may measure the mercury concentration measurement value in the exhaust gas downstream of the dust collector by the downstream mercury concentration meter, with respect to the mercury concentration set value in the exhaust gas downstream of the dust collector. When the ratio is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined ratio can be determined within a range of 0.4 to 0.8. By doing so, the timing for holding the activated carbon supply amount at a predetermined maximum value is determined within the range of the predetermined ratio of 0.4 to 0.8. The reason for determining in this way is that when the predetermined ratio is smaller than 0.4, it results in supplying an excessive amount of activated carbon more than necessary, resulting in a problem of increased processing costs due to excessive use of activated carbon. In addition, when the predetermined ratio is larger than 0.8, the activated carbon supply amount is insufficient, and the mercury cannot be sufficiently removed by adsorption, which causes a problem that the mercury concentration cannot be reduced below the mercury concentration setting value. It is.

  In the second aspect of the invention, the control device may measure the mercury concentration measurement value in the exhaust gas on the upstream side of the dust collector by the upstream mercury concentration meter with respect to the mercury concentration set value in the exhaust gas on the downstream side of the dust collector. When the ratio is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined ratio can be determined within a range of 20 to 200. By doing so, the timing at which the activated carbon supply amount is held at a predetermined maximum value can be determined within the above-mentioned predetermined ratio range of 20 to 200. The reason for determining in this way is that when the predetermined ratio is smaller than 20, the result is that an excessive amount of activated carbon is supplied, and there is a problem that the processing cost increases due to excessive use of activated carbon. In addition, when the predetermined ratio is larger than 200, the activated carbon supply amount is insufficient, and the mercury cannot be sufficiently removed by adsorption, causing a problem that the mercury concentration cannot be reduced below the mercury concentration setting value.

  In the third aspect of the invention, the control device may be configured such that the mercury concentration measurement value in the exhaust gas on the downstream side of the dust collector by the downstream mercury concentration meter is downstream of the mercury concentration set value in the exhaust gas on the downstream side of the dust collector. Mercury concentration in the exhaust gas downstream of the dust collector when the mercury concentration ratio on the side is equal to or greater than a predetermined ratio, or the measured mercury concentration in the exhaust gas upstream of the dust collector by the upstream mercury concentration meter When the upstream mercury concentration ratio with respect to the set value is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined downstream mercury concentration ratio is in the range of 0.4 to 0.8. The upstream upstream mercury concentration ratio can be determined within a range of 20 to 200. By doing so, firstly, the timing at which the activated carbon supply amount is maintained at a predetermined maximum value within the range of the predetermined downstream mercury ratio of 0.4 to 0.8 can be determined. The reason for determining in this way is that when the predetermined downstream mercury concentration ratio is smaller than 0.4, the result is that a larger amount of activated carbon is supplied than necessary, and the processing cost increases due to excessive use of activated carbon. In addition, when the predetermined downstream mercury concentration ratio is larger than 0.8, the activated carbon supply amount is insufficient and the mercury cannot be sufficiently removed by adsorption, and the mercury concentration is reduced below the mercury concentration setting value. This is because the problem that it is impossible is caused. Second, the timing for holding the activated carbon supply amount at a predetermined maximum value within a range of the upstream upstream mercury concentration ratio in the range of 20 to 200 can be determined. The reason for determining in this way is that when the predetermined upstream mercury concentration ratio is smaller than 20, the result is that an excessive amount of activated carbon is supplied, and the processing cost increases due to excessive use of activated carbon. In addition, when the predetermined upstream mercury concentration ratio is larger than 200, the activated carbon supply amount is insufficient and the mercury cannot be sufficiently adsorbed and removed, and the mercury concentration cannot be reduced below the mercury concentration setting value. It will cause problems.

Furthermore, in the first to third inventions, the control device controls the predetermined minimum value of the activated carbon supply amount determined as the activated carbon blowing weight with respect to the treated exhaust gas flow rate to 10 to 200 mg / Nm ^3. Can do. Thus, when the predetermined minimum value of the activated carbon supply amount is in the range of 10 to 200 mg / Nm ³ and the mercury concentration in the exhaust gas is low, it is set to a low value in the range, and when the mercury concentration is high A high frequency value may be used. When the mercury concentration in the exhaust gas is lower than the predetermined value, the activated carbon supply amount is maintained at the predetermined minimum value, so that the activated carbon adsorption layer is always formed on the bag filter of the dust collector. Therefore, even when exhaust gas containing mercury at a concentration higher than the predetermined value is discharged, mercury is absorbed by the adsorption removal action by the adsorption layer formed in advance and the adsorption removal action by activated carbon blown at that time. Can be adsorbed and removed quickly and reliably, and the mercury concentration in the exhaust gas after dust collection is made sufficiently low. Setting the predetermined minimum value to less than 10 mg / Nm ³ is inappropriate because it is difficult to sufficiently form an adsorption layer of activated carbon on the bag filter of the dust collector, and the predetermined minimum value is set to 200 mg / Nm. Setting Nm ³ or more is not a good idea because the amount of activated carbon supplied becomes excessive and the cost increases.

Furthermore, in the first to third inventions, the control device can control by setting a predetermined maximum value of the activated carbon supply amount determined as the activated carbon blowing weight with respect to the treated exhaust gas flow rate to 300 to 1000 mg / Nm ^3. it can. Thus, when the activated carbon supply amount is within the range of 300 to 1000 mg / Nm ³ and the mercury concentration in the exhaust gas is low, it is set to a low value within the range, and when the mercury concentration is high, it is high. A range value may be used. It is unsuitable for the set maximum value to be less than 300 mg / Nm ³ because there may be a problem that activated carbon cannot absorb and remove mercury in the exhaust gas, and it is inappropriate to set the set maximum value to 1000 mg / Nm ³ or more. This is not a good idea because the activated carbon supply becomes excessive and the cost increases.

  In addition, in the first to third inventions, regarding the increase from the minimum value to the maximum value of the activated carbon supply amount, the control device determines that the measured mercury concentration value in the exhaust gas is zero or less than a measurable minimum value. In the range until the first predetermined mercury concentration is reached, activated carbon is supplied based on the predetermined minimum activated carbon supply amount, and after the mercury concentration measurement value reaches the first predetermined mercury concentration, the mercury As the concentration measurement value increases, the activated carbon supply amount is increased linearly from the predetermined minimum value, and when the mercury concentration measurement value reaches the second predetermined mercury concentration, the activated carbon supply amount is supplied to the predetermined maximum value. After the mercury concentration measurement value reaches the second predetermined mercury concentration, the activated carbon supply amount can be kept constant at the predetermined maximum value with respect to the increase in the mercury concentration measurement value.

  Furthermore, in the first to third inventions, regarding the increase from the minimum value to the maximum value of the activated carbon supply amount, the control device determines that the measured mercury concentration value in the exhaust gas is zero or less than a measurable minimum value. In the range until the first predetermined mercury concentration is reached, activated carbon is supplied based on the amount of activated carbon supplied as the first supply amount at a predetermined minimum value, and the measured mercury concentration is the above-mentioned first predetermined mercury concentration. When the concentration is reached, the activated carbon supply amount is increased stepwise to the predetermined second supply amount, and the activated carbon supply amount is increased within the range until the measured mercury concentration reaches the second predetermined mercury concentration. The mercury concentration measurement so that the activated carbon supply amount is increased to the predetermined third supply amount when the mercury concentration measurement value reaches the second predetermined mercury concentration. Increase activated carbon supply in a stepped manner Repeat and, after increasing the activated carbon supply amount to a predetermined maximum value may also be to keep the activated carbon supply amount constant at its predetermined maximum value with an increase in mercury density measurements.

  As described above, by increasing the activated carbon supply amount from the minimum value to the maximum value based on the measured value of mercury concentration in the exhaust gas, the activated carbon supply can be performed without causing any trouble in the supply amount adjustment mechanism of the activated carbon supply device. The amount can be controlled smoothly.

[Exhaust gas treatment method]
The exhaust gas treatment method according to the present invention is configured as in the following fourth, fifth and sixth inventions, and the above-described problems can be solved by any of them.

<Fourth Invention>
In an exhaust gas treatment method in which exhaust gas exhausted from a furnace is dust-removed by a dust collector and activated carbon is blown from an activated carbon supply device into an exhaust gas passage that guides the exhaust gas from the furnace to the dust collector, downstream of the dust collector The measurement process includes measuring the mercury concentration in the exhaust gas with the downstream mercury concentration meter and the control process controlling the activated carbon supply amount of the activated carbon supply device with the control device. In addition to maintaining the above, based on the mercury concentration measurement value by the downstream mercury concentration meter, the activated carbon supply amount should be controlled so that the mercury concentration in the exhaust gas downstream of the dust collector is below the set value. A featured exhaust gas treatment method.

<Fifth invention>
In an exhaust gas treatment method in which exhaust gas exhausted from a furnace is dust-removed by a dust collector and activated carbon is blown from an activated carbon supply device into an exhaust gas passage that guides the exhaust gas from the furnace to the dust collector. In addition, it has a measurement process that measures the mercury concentration in the exhaust gas with an upstream mercury concentration meter upstream of the dust collector and a control process that controls the activated carbon supply amount of the activated carbon supply apparatus with the control device. Supply the activated carbon so that the mercury concentration in the exhaust gas at the downstream side of the dust collector is below the set value based on the mercury concentration measured by the upstream mercury concentration meter while maintaining the amount above the specified minimum value. An exhaust gas treatment method characterized by controlling the amount.

<Sixth Invention>
In an exhaust gas treatment method, exhaust gas containing mercury discharged from a furnace is dust-removed by a dust collector, and activated carbon is blown from the activated carbon supply device to the exhaust gas passage that guides the exhaust gas from the furnace to the dust collector. Process of measuring the mercury concentration in the exhaust gas with the upstream mercury concentration meter downstream of the dust collector and upstream of the dust collector and measuring the mercury concentration in the exhaust gas with the downstream mercury concentration meter downstream of the dust collector And a control process for controlling the activated carbon supply amount of the activated carbon supply device by the control device. In the control process, the activated carbon supply amount is maintained at a predetermined minimum value or more, and the measured mercury concentration value by the upstream mercury concentration meter and the downstream The activated carbon supply amount is controlled so that the mercury concentration in the exhaust gas on the downstream side of the dust collector is below the set value based on the measured mercury concentration value by the side mercury concentration meter. Processing method.

  In the fourth to sixth inventions, the control step keeps the activated carbon supply amount at a predetermined maximum value when the measured mercury concentration value by the upstream mercury concentration meter or the downstream mercury concentration meter is equal to or higher than the predetermined mercury concentration. It is preferable to control. Although the mercury concentration is not so high as a time average, when the mercury concentration suddenly increases temporarily, if a large amount of activated carbon is supplied in accordance with this high mercury concentration, the activated carbon will be excessively excessive over the subsequent time. The result will be to supply. Such excessive supply can be prevented by controlling the supply amount of the activated carbon so as to keep the predetermined maximum value.

  In the fourth aspect of the invention, the control step may be configured such that the mercury concentration measurement value in the exhaust gas downstream of the dust collector by the downstream mercury concentration meter is relative to the mercury concentration set value in the exhaust gas downstream of the dust collector. When the ratio is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined ratio can be determined within a range of 0.4 to 0.8. By doing so, the timing for holding the activated carbon supply amount at a predetermined maximum value is determined within the range of the predetermined ratio of 0.4 to 0.8. The reason for determining in this way is that when the predetermined ratio is smaller than 0.4, it results in supplying an excessive amount of activated carbon more than necessary, resulting in a problem of increased processing costs due to excessive use of activated carbon. In addition, when the predetermined ratio is larger than 0.8, the activated carbon supply amount is insufficient, and the mercury cannot be sufficiently removed by adsorption, which causes a problem that the mercury concentration cannot be reduced below the mercury concentration setting value. It is.

  In the fifth aspect of the invention, the control step is for the mercury concentration measurement value in the exhaust gas upstream of the dust collector by the upstream mercury concentration meter to the mercury concentration set value in the exhaust gas downstream of the dust collector. When the ratio is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined ratio can be determined within a range of 20 to 200. By doing so, the timing at which the activated carbon supply amount is held at a predetermined maximum value can be determined within the above-mentioned predetermined ratio range of 20 to 200. The reason for determining in this way is that when the predetermined ratio is smaller than 20, the result is that an excessive amount of activated carbon is supplied, and there is a problem that the processing cost increases due to excessive use of activated carbon. In addition, when the predetermined ratio is larger than 200, the activated carbon supply amount is insufficient, and the mercury cannot be sufficiently removed by adsorption, causing a problem that the mercury concentration cannot be reduced below the mercury concentration setting value.

  In the sixth aspect of the invention, the control step includes a downstream of the measured mercury concentration value in the exhaust gas on the downstream side of the dust collector by the downstream mercury concentration meter with respect to the mercury concentration set value in the exhaust gas on the downstream side of the dust collector. Mercury concentration in the exhaust gas downstream of the dust collector when the mercury concentration ratio on the side is equal to or greater than a predetermined ratio, or the measured mercury concentration in the exhaust gas upstream of the dust collector by the upstream mercury concentration meter When the upstream mercury concentration ratio with respect to the set value is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined downstream mercury concentration ratio is in the range of 0.4 to 0.8. The upstream upstream mercury concentration ratio can be determined within a range of 20 to 200. By doing so, firstly, the timing at which the activated carbon supply amount is maintained at a predetermined maximum value within the range of the predetermined downstream mercury ratio of 0.4 to 0.8 can be determined. The reason for determining in this way is that when the predetermined downstream mercury concentration ratio is smaller than 0.4, the result is that a larger amount of activated carbon is supplied than necessary, and the processing cost increases due to excessive use of activated carbon. In addition, when the predetermined downstream mercury concentration ratio is larger than 0.8, the activated carbon supply amount is insufficient and the mercury cannot be sufficiently removed by adsorption, and the mercury concentration is reduced below the mercury concentration setting value. This is because the problem that it is impossible is caused. Second, the timing for holding the activated carbon supply amount at a predetermined maximum value within a range of the upstream upstream mercury concentration ratio in the range of 20 to 200 can be determined. The reason for determining in this way is that when the predetermined upstream mercury concentration ratio is smaller than 20, the result is that an excessive amount of activated carbon is supplied, and the processing cost increases due to excessive use of activated carbon. When the predetermined upstream mercury concentration ratio is larger than 200, the activated carbon supply amount is insufficient and the mercury cannot be sufficiently adsorbed, and the mercury concentration cannot be reduced below the mercury concentration setting value. It is because it will produce.

Furthermore, in the fourth to sixth inventions, the control step may control by setting a predetermined minimum value of the activated carbon supply amount determined as the activated carbon blowing weight with respect to the treated exhaust gas flow rate to 10 to 200 mg / Nm ^3. it can. Thus, when the predetermined minimum value of the activated carbon supply amount is in the range of 10 to 200 mg / Nm ³ and the mercury concentration in the exhaust gas is low, it is set to a low value in the range, and when the mercury concentration is high A high frequency value may be used. Thus, when the mercury concentration in the exhaust gas is lower than a predetermined value, the activated carbon supply amount is kept at a predetermined minimum value, so that an activated carbon adsorption layer is always formed on the bag filter of the dust collector. Therefore, even when exhaust gas containing high-concentration mercury with a concentration higher than the predetermined value is discharged, the adsorption removal action by the previously formed adsorption layer and the adsorption removal by the activated carbon blown at that time As a result, mercury can be adsorbed and removed quickly and reliably, and the concentration of mercury in the exhaust gas after dust collection will be sufficiently low. Setting the predetermined minimum value to less than 10 mg / Nm ³ is inappropriate because it is difficult to sufficiently form an adsorption layer of activated carbon on the bag filter of the dust collector, and the predetermined minimum value is set to 200 mg / Nm. Setting Nm ³ or more is not a good idea because the amount of activated carbon supplied becomes excessive and the cost increases.

Furthermore, in the fourth to sixth inventions, the control step controls the predetermined maximum value of the activated carbon supply amount determined as the activated carbon blowing weight with respect to the treated exhaust gas flow rate to 300 to 1000 mg / Nm ^3. be able to. Thus, when the activated carbon supply amount is within the range of 300 to 1000 mg / Nm ³ and the mercury concentration in the exhaust gas is low, it is set to a low value within the range, and when the mercury concentration is high, it is high. A range value may be used. It is unsuitable for the set maximum value to be less than 300 mg / Nm ³ because there may be a problem that activated carbon cannot absorb and remove mercury in the exhaust gas, and it is inappropriate to set the set maximum value to 1000 mg / Nm ³ or more. This is not a good idea because the activated carbon supply becomes excessive and the cost increases.

  In addition, in the fourth to sixth inventions, regarding the increase from the minimum value to the maximum value of the activated carbon supply amount, the control process starts from a value at which the measured mercury concentration in the exhaust gas is zero or less than a measurable minimum value. In the range until the first predetermined mercury concentration is reached, activated carbon is supplied based on the predetermined minimum activated carbon supply amount, and after the mercury concentration measurement value reaches the first predetermined mercury concentration, the mercury As the concentration measurement value increases, the activated carbon supply amount is increased linearly from the predetermined minimum value, and when the mercury concentration measurement value reaches the second predetermined mercury concentration, the activated carbon supply amount is supplied to the predetermined maximum value. After the mercury concentration measurement value reaches the second predetermined mercury concentration, the activated carbon supply amount can be kept constant at the predetermined maximum value with respect to the increase in the mercury concentration measurement value.

  Further, in the fourth to sixth inventions, with respect to the increase from the minimum value to the maximum value of the activated carbon supply amount, the control step is performed from the value where the mercury concentration measurement value of the exhaust gas is zero or less than the measurable minimum value, In the range until the first predetermined mercury concentration is reached, activated carbon is supplied based on the activated carbon supply amount that is the first supply amount at a predetermined minimum value, and the measured mercury concentration value is the first predetermined mercury concentration. When the activated carbon supply amount is increased to the predetermined second supply amount in a stepwise manner, the activated carbon supply amount is increased within the range until the mercury concentration measurement value reaches the second predetermined mercury concentration. Of the mercury concentration measurement value so that the activated carbon supply amount is increased to the predetermined third supply amount when the mercury concentration measurement value reaches the second predetermined mercury concentration. As the increase increases, the activated carbon supply can be increased stepwise. Repeating, after increasing the activated carbon supply amount to a predetermined maximum value may also be to keep the activated carbon supply amount constant at its predetermined maximum value with an increase in mercury density measurements.

  As described above, by increasing the activated carbon supply amount from the minimum value to the maximum value based on the mercury concentration measurement value of the exhaust gas, the activated carbon supply amount does not cause a problem for the supply amount adjustment mechanism of the activated carbon supply device. Can be controlled smoothly.

  According to the present invention, in the first invention and the fourth invention, on the downstream side of the dust collector, the actual mercury concentration in the exhaust gas after the mercury adsorption removal by activated carbon is measured by the mercury concentration meter and activated carbon is supplied. Since the amount is adjusted, the mercury concentration can be reduced to a permissible set value or less by adjusting the activated carbon supply amount without excess or deficiency.

  In the second invention and the fifth invention, the mercury concentration is measured with a mercury concentration meter downstream of the furnace and upstream of the dust collector, and the activated carbon supply amount is adjusted based on the measured value to adjust the dust collector. The mercury concentration in the exhaust gas on the downstream side is set to an allowable value or less. When the mercury concentration in the exhaust gas from the furnace fluctuates, the mercury concentration can be measured before the exhaust gas flows into the dust collector and the activated carbon supply can be quickly adjusted to an appropriate amount based on the measured value. The mercury concentration in the exhaust gas discharged from the chimney can be surely made to be an allowable set value or less without causing a delay with respect to the fluctuation of the mercury concentration.

  In the third and sixth inventions, the mercury concentration is measured with a mercury concentration meter downstream of the furnace and upstream of the dust collector, and the mercury concentration is also measured with a mercury concentration meter downstream of the dust collector. Based on these two measured values, the activated carbon supply amount is adjusted so that the mercury concentration on the downstream side of the dust collector is not more than the allowable set value. Based on the mercury concentration measurement value downstream of the furnace and upstream of the dust collector, control is performed to determine the base value of the activated carbon supply, and based on the mercury concentration measurement value downstream of the dust collector. The activated carbon supply amount is complemented and controlled so as to adjust the activated carbon supply amount to be increased or decreased with respect to the base value. By doing in this way, the mercury concentration in the exhaust gas discharged from the chimney can be more reliably reduced to an allowable setting value or less without causing a delay with respect to the fluctuation of the mercury concentration.

  In the first invention and the fourth invention, since the actual mercury concentration at the downstream side of the dust collector is measured, the mercury concentration in the exhaust gas discharged from the chimney is surely below the set value, but the exhaust gas from the furnace When the mercury concentration in the tank fluctuates, the adjustment of the activated carbon supply amount is delayed with respect to the fluctuation. On the other hand, in the second invention and the fifth invention, since the mercury concentration is measured on the upstream side of the dust collector, it is possible to quickly cope with the above fluctuation. Further, in the third and sixth inventions, the mercury concentration is measured on the upstream side of the dust collector, the mercury concentration is further measured on the downstream side of the dust collector, and the activated carbon supply amount is based on these two measured values. By adjusting the, the mercury concentration in the exhaust gas discharged from the chimney can be more reliably reduced to an allowable setting value or less without causing a delay with respect to fluctuations in the mercury concentration.

  Thus, according to the present invention, the mercury concentration in the exhaust gas is measured at a position downstream of the dust collector, or is measured upstream of the dust collector, or is measured upstream and downstream of the dust collector. The amount of activated carbon to be blown in is adjusted based on the mercury concentration measurement value while maintaining the amount of activated carbon above the predetermined minimum value, so that the mercury concentration in the exhaust gas discharged from the chimney is surely below the predetermined value, and the activated carbon Is supplied without excess and deficiency, and the amount of activated carbon used can be suppressed, and the cost of exhaust gas treatment can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS The 1st embodiment apparatus of this invention is shown, (A) is the schematic block diagram, (B) is a schematic block diagram of activated carbon supply apparatus. It is a schematic block diagram of the apparatus of 2nd embodiment of this invention. It is a schematic block diagram of the apparatus of 3rd embodiment of this invention. (A)-(H) have shown the various patterns which can be employ | adopted as a relationship between the mercury concentration in waste gas, and activated carbon supply amount. It is a figure which shows the relationship between the chimney mercury concentration used in the Example of this invention, and activated carbon supply amount. It is a figure which shows the relationship between the bag filter entrance mercury concentration used in the Example of this invention, and activated carbon supply amount.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  In the present embodiment shown below, an incinerator that incinerates waste is described as a furnace for discharging exhaust gas containing mercury. However, the present invention is not limited to this, and the present invention is not limited to this. It can be used as a treatment apparatus and treatment method for exhaust gas containing mercury discharged from various furnaces such as a furnace.

  For the exhaust gas from the incinerator that incinerates the waste, the activated carbon is blown into the exhaust gas flow path at the upstream position of the bag filter installed for dust collection, so that the mercury concentration downstream of the bag filter is extremely low. Conventionally, the mercury concentration in the exhaust gas from the incinerator fluctuates due to fluctuations in the type and amount of waste, and the mercury concentration temporarily increases downstream of the bag filter. Therefore, it is necessary to constantly blow a large amount of activated carbon, which increases the cost of exhaust gas treatment. Therefore, in the present embodiment, the mercury concentration is measured by a mercury concentration meter, and an activated carbon amount that is not excessive or insufficient is blown into the exhaust gas passage based on the measured mercury concentration. The mercury concentration meter is preferably in the form of continuous measurement.

<First embodiment>
In FIG. 1 which shows a schematic configuration of the apparatus of the present embodiment, a boiler 2 from the upstream side and a bag filter 4 as a dust collector are disposed in the exhaust gas flow path for guiding the exhaust gas from the incinerator 1 to the chimney 6. An activated carbon supply device 3 for blowing activated carbon for adsorbing and removing mercury in the exhaust gas to the exhaust gas flow path at an upstream position of the bag filter 4 and a control device 7 for controlling the activated carbon supply device 3 are provided. A mercury concentration meter 5 for measuring the mercury concentration in the exhaust gas is provided at the outlet of the bag filter 4 or the chimney 6, and the measured value of the mercury concentration meter 5 is sent as an output signal to the control device 7. A total of 5 is connected to the control device 7.

  In the apparatus of this embodiment, the mercury concentration meter 5 measures the mercury concentration in the exhaust gas on the downstream side of the bag filter 4.

  The measured value of the mercury concentration meter 5 is sent to the control device 7, and this measured value is compared with a predetermined mercury concentration value determined in advance, whereby the activated carbon supply device 3 is controlled.

  When the measured mercury concentration is higher than the predetermined mercury concentration value, the activated carbon supply amount is increased. After the activated carbon supply amount is increased, when the state where the mercury concentration is equal to or lower than the predetermined mercury concentration value is maintained, the activated carbon supply amount is controlled to be reduced.

  Specifically, the activated carbon supply device 3 includes a hopper 3A that accommodates activated carbon, a rotary-type cutting member 3B provided at a lower outlet of the hopper 3A, and a valve or damper 3C provided below the rotary member. have. In the activated carbon supply device 3, upon receiving a command signal from the control device 7, at least one of the rotation speed of the cutting member 3 </ b> B, the opening degree of the valve, and the damper 3 </ b> C is adjusted, and the activated carbon adjusts the supply amount. And supplied to the exhaust gas flow path.

<Second embodiment>
The present embodiment shown in FIG. 2 is the same as the first embodiment described above except for the arrangement position of the mercury concentration meter 5. Therefore, in FIG. 2, the same code | symbol is attached | subjected about the site | part common in the 1st embodiment of FIG. 1, and the description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 2, the mercury concentration meter 5 is downstream of the incinerator 1 and upstream of the bag filter 4, and upstream of the activated carbon blowing position by the activated carbon supply device 3. It is arranged to measure the mercury concentration in the exhaust gas at the position. In the present embodiment, the control device 7 grasps the relationship between the mercury concentration and activated carbon supply amount at the measurement position and the mercury concentration at the downstream position from the bag filter 4 based on accumulated data. Therefore, the mercury concentration upstream of the activated carbon blowing position is measured, and the mercury concentration downstream of the bag filter 4 can be estimated from the measured mercury concentration and the activated carbon supply amount. That is, the control device 7 estimates the mercury concentration downstream of the bag filter 4 based on the mercury concentration measurement value upstream of the activated carbon blowing position, and the estimated mercury concentration is equal to or less than a predetermined mercury concentration value determined in advance. The activated carbon supply amount required for the activation can be obtained, and the activated carbon supply amount of the activated carbon supply device 3 is controlled. As a result, the mercury concentration downstream of the bag filter 4 is set to a predetermined mercury concentration value or less.

  In this embodiment, when there is a change in the mercury concentration in the exhaust gas from the incinerator 1, the change in the mercury concentration is on the downstream side of the incinerator 1 and upstream of the activated carbon blowing position by the activated carbon supply device 3. Since the mercury concentration meter 5 measures and detects it at the position, it is possible to quickly adjust the supply amount of activated carbon, so there is no time lag and the mercury concentration in the exhaust gas in the chimney can be reliably maintained below the set value. it can. In the example illustrated in FIG. 2, the mercury concentration measurement position by the mercury concentration meter 5 is upstream of the activated carbon blowing position, but is not limited thereto, and is upstream of the bag filter 4. It may be downstream from the activated carbon blowing position.

<Third embodiment>
Compared with the previous second embodiment, the present embodiment shown in FIG. 3 is downstream of the bag filter 4 in addition to the first mercury concentration meter 5A disposed upstream of the activated carbon blowing position by the activated carbon supply device 3. A second mercury concentration meter 5B for measuring the mercury concentration in the exhaust gas is also provided at the outlet of the bag filter 4 on the side or the chimney 6, and the measurement value of the second mercury concentration meter 5B is sent to the control device 7 as an output signal. It is like that. Except for this point, the second embodiment is the same as the second embodiment. Therefore, in FIG. 3, the same code | symbol is attached | subjected about the site | part common in the 2nd embodiment of FIG. 2, and the description is abbreviate | omitted.

  In this embodiment, as seen in FIG. 3, in addition to the first mercury concentration meter 5A arranged upstream of the activated carbon blowing position by the activated carbon supply device 3 in the second embodiment, the bag filter 4 A second mercury concentration meter 5B is provided at the outlet. Similarly to the second embodiment, the base value of the activated carbon supply amount is controlled based on the measured value by the first mercury concentration meter 5A on the upstream side of the activated carbon blowing position by the activated carbon supply device 3, and further at the outlet of the bag filter 4. Based on the measured value by the second mercury concentration meter 5B, the control based on the measured value by the first mercury concentration meter 5A is complemented, and the activated carbon supply amount is controlled to increase or decrease.

  The outlet of the bag filter 4 is detected after a phenomenon in which the mercury concentration measured value by the first mercury concentration meter 5A on the upstream side of the activated carbon supply device 3 by the activated carbon supply device 3 increases in a short time (referred to as a measured value peak) is detected. , Until there is a time lag until the mercury concentration measurement value peak by the second mercury concentration meter 5B is detected, when the mercury concentration measurement peak upstream from the activated carbon blowing position by the activated carbon supply device 3 is sufficiently settled. However, a mercury concentration measurement peak may be detected at the outlet of the bag filter 4. Therefore, the second mercury concentration meter 5B is installed and the activated carbon supply amount is controlled based on the mercury concentration measurement value at the outlet of the bag filter 4, thereby complementing the control based on the measurement value of the first mercury concentration meter 5A, and the chimney. The mercury concentration in the exhaust gas in the inside can be more reliably lowered below the set value.

  In the embodiment of the present invention, the control device may control the activated carbon supply amount based on a predetermined correspondence between the mercury concentration measured value by the mercury concentration meter and the activated carbon supply amount. Various forms can be applied as the correspondence between the predetermined mercury concentration measurement value and the activated carbon supply amount.

  The correspondence relationship between the measured mercury concentration value and the activated carbon supply amount is determined as the activated carbon supply amount starts from a predetermined minimum value and gradually increases to a predetermined maximum value as the measured mercury concentration in the exhaust gas increases. It may be in the form of a relationship. As the predetermined minimum value of the activated carbon supply amount, during the operation in which the exhaust gas is discharged from the incinerator 1, even when the mercury concentration in the exhaust gas is extremely low, the activated carbon is always blown at the minimum supply amount. Thus, the value of the activated carbon supply amount is determined so that the mercury concentration in the exhaust gas in the chimney can be reliably maintained below the set value. As the measured value of mercury concentration in the exhaust gas increases, the activated carbon supply amount is gradually increased from a predetermined minimum value, and an appropriate amount of activated carbon is supplied with respect to the mercury concentration in the exhaust gas. In the form of the correspondence relationship in which the activated carbon supply amount is gradually increased from a predetermined minimum value, the activated carbon supply amount may be increased linearly as the mercury concentration increases, or it is increased in a stepwise manner in multiple steps. Various forms of correspondence may be employed. As a means of adjusting the supply amount of activated carbon, the rotary speed of the rotary type cutting member of the activated carbon supply device, the opening degree of the valve, the opening degree of the damper, etc. are adjusted alone or in combination. It is preferable to adopt a form of correspondence suitable for the adjustment range of the mechanism and the characteristics of the adjustment (for example, the supply amount can be increased or decreased continuously or stepwise).

  FIG. 4 shows examples of various forms of correspondence between the measured mercury concentration value and the activated carbon supply amount.

  In the form shown in FIG. 4 (A), the activated carbon supply amount of a predetermined minimum value is within a range from a measured value of the mercury concentration in exhaust gas that is zero or less than a measurable minimum minimum value to a predetermined predetermined mercury concentration. When activated carbon is supplied under the above conditions and the measured value of mercury concentration reaches the specified mercury concentration, the activated carbon supply amount is increased in steps to the specified maximum value, and further, the mercury concentration in the exhaust gas is increased. On the other hand, the activated carbon supply amount is kept constant at the predetermined maximum value. When the measured value of mercury concentration is lower than the predetermined mercury concentration, the activated carbon supply amount is set to the predetermined minimum value, and when it is higher than the predetermined mercury concentration, the activated carbon supply amount is set to the predetermined maximum value. The activated carbon supply amount can be controlled by a simple control mechanism.

  In the form shown in FIG. 4 (B), the measured value of the mercury concentration in the exhaust gas is zero or less than the measurable minimum value, and reaches the first predetermined mercury concentration. Activated carbon is supplied under the activated carbon supply amount (first supply amount), and when the measured value of the mercury concentration reaches the first predetermined mercury concentration, the activated carbon supply amount is changed in a stepped manner to the predetermined second supply amount. When the supply amount of activated carbon is kept constant at the second supply amount with respect to the increase in the mercury concentration in the exhaust gas, and when the measured value of the mercury concentration reaches the second predetermined mercury concentration, In order to increase the activated carbon supply amount to a predetermined third supply amount, the activated carbon supply amount is repeatedly increased in small steps as the mercury concentration in the exhaust gas increases, and the activated carbon supply amount is set to a predetermined maximum value. After the increase, the increase in mercury concentration in the exhaust gas As a form to maintain the activated carbon supply amount constant at a predetermined maximum value. As the mercury concentration in the exhaust gas increases, the supply amount of activated carbon is increased in a stepped manner from the predetermined minimum value to the predetermined maximum value, thereby supplying the activated carbon in a more appropriate amount with respect to the mercury concentration in the exhaust gas. Can be controlled.

  The form shown in FIG. 4C is a form in which the activated carbon supply amount is linearly increased from a predetermined minimum value as the mercury concentration in the exhaust gas increases. Further, in the form shown in FIG. 4D, activated carbon is linearly supplied from a predetermined minimum value as the mercury concentration in the exhaust gas increases until the measured value of the mercury concentration in the exhaust gas reaches the predetermined mercury concentration. The amount of activated carbon was increased to a predetermined maximum value when the measured value of the mercury concentration reached the predetermined mercury concentration in the exhaust gas, and the activated carbon supply amount was increased to the predetermined maximum value. After that, the activated carbon supply amount is kept constant at the predetermined maximum value with respect to the increase in the mercury concentration in the exhaust gas. In the forms shown in FIGS. 4C and 4D, the amount of activated carbon supplied is continuously increased from a predetermined minimum value in accordance with the increase in the concentration of mercury in the exhaust gas. Can be controlled to supply activated carbon.

  In the form shown in FIG. 4 (E), there is a predetermined minimum value in the range from the measured value of the mercury concentration in the exhaust gas being zero or less than the minimum measurable minimum value to the first predetermined mercury concentration. Activated carbon is supplied under the activated carbon supply amount, and after the measured mercury concentration reaches the first specified mercury concentration, the activated carbon supply amount is linearly increased from the predetermined minimum value as the mercury concentration in the exhaust gas increases. When the measured value of the mercury concentration reaches the second predetermined mercury concentration, the activated carbon supply amount is set to the predetermined maximum supply amount, and after the activated carbon supply amount is increased to the predetermined maximum value, The activated carbon supply amount is kept constant at the predetermined maximum value with respect to the increase in the mercury concentration in the exhaust gas. The form shown in FIG. 4E is a form in which the forms shown in FIGS. 4A and 4C are combined, and has the characteristics and effects of the respective forms.

  In the form shown in FIG. 4 (F), there is a predetermined minimum value in a range from the measured value of the mercury concentration in the exhaust gas to zero or less than the measurable minimum value to the first predetermined mercury concentration. Activated carbon is supplied under the activated carbon supply amount (first supply amount), and after the measured mercury concentration reaches the first specified mercury concentration, the first supply is performed as the mercury concentration in the exhaust gas increases. The activated carbon supply amount is increased linearly from the amount to a second supply amount corresponding to the second predetermined mercury concentration, and then the activated carbon supply amount is increased with respect to the increase in the mercury concentration in the exhaust gas. And when the third predetermined mercury concentration is reached, the activated carbon supply amount is increased linearly from the second supply amount to the third supply amount corresponding to the fourth predetermined mercury concentration. After that, the activated carbon supply amount is increased with increasing mercury concentration in the exhaust gas. After the increase of the activated carbon supply amount to a predetermined maximum value, the activated carbon supply amount is kept constant and increased with respect to such an increase in the mercury concentration in the exhaust gas. The activated carbon supply amount is kept constant at the predetermined maximum value with respect to the increase in the mercury concentration in the exhaust gas. The form shown in FIG. 4F is a form obtained by combining the forms shown in FIGS. 4B and 4D, and has the characteristics and effects of the respective forms.

  In the form shown in FIG. 4 (G), the activated carbon supply amount is linearly increased from a predetermined minimum value as the mercury concentration in the exhaust gas increases until the measured value of the mercury concentration in the exhaust gas reaches the predetermined mercury concentration. When the measured value of the mercury concentration reaches the predetermined mercury concentration, the activated carbon supply amount is increased to the predetermined maximum value in a stepwise manner, and after the activated carbon supply amount is increased to the predetermined maximum value, the exhaust gas This is a form in which the activated carbon supply amount is kept constant at the predetermined maximum value with respect to the increase in the medium mercury concentration. When the measured value of the mercury concentration in the exhaust gas is lower than a relatively medium predetermined value, the activated carbon supply amount is continuously increased from the predetermined minimum value in accordance with the increase in the mercury concentration in the exhaust gas. The activated carbon can be controlled to be supplied in an appropriate amount finely with respect to the mercury concentration, and if the measured value of the mercury concentration in the exhaust gas is higher than the predetermined moderate mercury concentration, the activated carbon supply amount is set to the predetermined maximum value. It is a correspondence relationship to be a value, and the activated carbon supply amount can be controlled with an appropriate amount by effectively using a plurality of means for adjusting the supply amount of activated carbon.

  In the form shown in FIG. 4 (H), the amount of activated carbon supplied linearly from a predetermined minimum value as the mercury concentration in the exhaust gas increases until the measured value of the mercury concentration in the exhaust gas reaches the first predetermined mercury concentration. When the measured value of mercury concentration reaches the first predetermined mercury concentration, the activated carbon supply amount is set to the predetermined first supply amount, and the measured value of mercury concentration reaches the second predetermined mercury concentration. Until the activated carbon supply amount is kept constant at the predetermined first supply amount, and when the measured value of the mercury concentration reaches the second predetermined mercury concentration, the activated carbon supply amount is set to the predetermined maximum value in steps. After the activated carbon supply amount is increased to a predetermined maximum value, the activated carbon supply amount is kept constant at the predetermined maximum value with respect to the increase in the mercury concentration in the exhaust gas. The form shown in FIG. 4 (H) is similar to the form shown in FIG. 4 (G) in a predetermined range where the measured value of the mercury concentration in the exhaust gas is relatively medium (from the first predetermined mercury concentration to the second predetermined silver concentration). Up to the above range) is a mode in which the activated carbon supply amount is kept constant at the first predetermined supply amount, and the supply of activated carbon can be controlled to be supplied in a more appropriate amount.

  In addition, when the control device controls the activated carbon supply amount based on the predetermined relationship between the mercury concentration measurement value by the mercury concentration meter and the activated carbon supply amount, the correspondence relationship between the predetermined mercury concentration measurement value and the activated carbon supply amount. If the measured mercury concentration in the exhaust gas is zero or less than the minimum limit value measurable by the mercury concentration meter or lower than a predetermined value, activated carbon is not supplied and the mercury concentration in the exhaust gas is zero or measured. When it is higher than the minimum possible limit value or a predetermined value, it may be in the form of a correspondence relationship in which the activated carbon supply amount is gradually increased as the mercury concentration in the exhaust gas increases. Moreover, when increasing the activated carbon supply amount according to the increase in the mercury concentration in the exhaust gas, it may be increased linearly or stepwise.

  Further, as another form of the above correspondence relationship, when the measured mercury concentration in the exhaust gas is zero or less than the minimum measurable limit value of the mercury concentration meter or lower than the predetermined first predetermined mercury concentration, supply of activated carbon In accordance with the increase in the mercury concentration in the exhaust gas within the range where the mercury concentration in the exhaust gas is zero or the measurable minimum limit value or higher than the predetermined first predetermined mercury concentration and lower than the predetermined second predetermined mercury concentration. The activated carbon supply amount may be gradually increased so that the activated carbon supply amount is kept constant as the predetermined supply amount in a range where the measured value of the mercury concentration in the exhaust gas is higher than the second predetermined mercury concentration. Moreover, when increasing the activated carbon supply amount according to the increase in the mercury concentration in the exhaust gas, it may be increased linearly or stepwise.

  In the present invention, when the activated carbon supply amount is controlled based on a predetermined relationship between the mercury concentration in the exhaust gas and the activated carbon supply amount, various forms can be taken for increasing the activated carbon supply amount from the minimum value to the maximum value. This is as described with reference to FIG. 4. How to determine the predetermined minimum value and the predetermined maximum value, as an example, in the case of increasing the activated carbon supply amount in the form of FIG. Explained. That is, the correspondence relationship between the measured mercury concentration value and the activated carbon supply amount is as shown below. Activated carbon is supplied based on the specified minimum activated carbon supply amount in the range from the measured value of the mercury concentration in the exhaust gas to zero or less than the measurable minimum value to the first specified mercury concentration. Then, after the measured value of the mercury concentration reaches the first predetermined mercury concentration, the activated carbon supply amount is linearly increased from the predetermined minimum value according to the increase of the mercury concentration in the exhaust gas, and the measured value of the mercury concentration is When the second predetermined mercury concentration is reached, the activated carbon supply amount is set to the predetermined maximum value, and after increasing the activated carbon supply amount to the predetermined maximum value, the increase in the mercury concentration in the exhaust gas In this mode, the activated carbon supply amount is kept constant at the predetermined maximum value.

  The inventors examined various conditions for determining the predetermined minimum value and the predetermined maximum value when processing exhaust gas containing mercury using the exhaust gas treatment apparatus shown in FIG. During the examination, the mercury concentration in the exhaust gas at the dust collector inlet (upstream side) was measured, and the ratio of this measured mercury concentration to the set value of the mercury concentration in the exhaust gas downstream of the dust collector ( For the case where the upstream mercury concentration ratio is changed within a range of 20 to 200 times, the mercury adsorption / removal process by activated carbon is simulated to obtain an appropriate range between the predetermined minimum value and the predetermined maximum value of the activated carbon supply amount. It was. The upstream mercury concentration ratio is divided into a plurality of stages between 20 times and 200 times, and sequentially changed, and an appropriate range for a predetermined minimum value and a predetermined maximum value is obtained each time in each divided range. . The results obtained are as shown in Table 1.

In Table 1, for example, when it is predicted that the exhaust gas containing mercury with the upstream mercury concentration ratio in the range of 100 times or more and less than 120 times is discharged from the furnace, it is determined as the activated carbon blowing weight with respect to the treated exhaust gas flow rate. is a predetermined minimum value of the activated carbon supply amount is set to 60~200mg / Nm ^3, to set a predetermined maximum value of the activated carbon supply amount and 300~1000mg / Nm ^3.

  In Table 1, for each of the above-mentioned upstream mercury concentration ratio division ranges, the lower limit of the predetermined minimum value is when the measured mercury concentration in the exhaust gas is low or when the mercury concentration set value on the downstream side of the dust collector is high The upper limit of the predetermined minimum value corresponds to the case where the mercury concentration measurement value in the exhaust gas is high or the mercury concentration set value downstream of the dust collector is low.

  Also, in Table 1, for each of the above-mentioned upstream mercury concentration ratio division ranges, the lower limit of the predetermined maximum value is when the measured mercury concentration value in the exhaust gas is low or the mercury concentration set value at the downstream side of the dust collector is high. The upper limit of the predetermined maximum value corresponds to the case where the mercury concentration measurement value in the exhaust gas is high or the mercury concentration set value downstream of the dust collector is low.

  In this way, by setting the predetermined minimum value of the activated carbon supply amount, the activated carbon is adhered to the bag filter of the dust collector, and the adsorption layer is sufficiently formed in advance, which contains a high concentration of mercury. When exhaust gas is discharged, mercury can be adsorbed and removed quickly by the already formed activated carbon adsorption layer and activated carbon blown at that time, and the mercury concentration can be lowered to a sufficiently low concentration.

  Further, by setting a predetermined maximum value of the activated carbon supply amount, high concentration mercury can be sufficiently adsorbed and removed without excessive supply of activated carbon.

  Examples of the present invention will be described below together with comparative examples.

[Example]
The exhaust gas discharged from the waste incinerator was subjected to mercury removal processing by the exhaust gas processing apparatus shown in FIGS. The exhaust gas discharged from the waste incinerator has an exhaust gas amount of 10,000 Nm ³ / h from the chimney, and the mercury concentration in the exhaust gas in the chimney is set to 50 μg / Nm ³ or less on average for one hour. . Furthermore, it is desired to suppress the maximum mercury concentration instantaneous value (referred to as peak measurement value) in a phenomenon in which the mercury concentration measurement value rapidly increases in a short time. The activated carbon supply amount (mg / Nm ³ ) is determined as the activated carbon blowing weight with respect to the treated exhaust gas flow rate.

  Table 2 shows the peak measurement value of mercury concentration at the bag filter inlet and the peak measurement value of mercury concentration at the chimney in Examples and Comparative Examples.

<Comparative example>
Activated carbon is blown into the exhaust gas flow path upstream of the bag filter at a constant supply amount of 50 mg / Nm ³ with respect to the exhaust gas amount (Nm ³ / h). Normally, the mercury concentration in the exhaust gas in the chimney is 5 μg / Nm. It is below ³ -dry. In some cases, the mercury concentration at the inlet of the bag filter fluctuates due to fluctuations in the waste properties supplied to the incinerator and the mercury concentration at the chimney increases. Peak measurements of mercury concentrations up to 90 μg / Nm ³ -dry were observed in the chimney.

<Example 1>
In Example 1, the exhaust gas containing mercury was treated using the exhaust gas treatment apparatus shown in FIG. The mercury concentration in the exhaust gas at the chimney was measured as the downstream side of the dust collector, and the activated carbon was supplied by determining the activated carbon supply amount using the correspondence between the chimney mercury concentration and the activated carbon supply amount shown in FIG. As shown in FIG. 5, the activated carbon supply amount, when the chimney mercury concentration is less than 10 [mu] g / Nm ³ -dry is a 50 mg / Nm ³ of a constant minimum value, chimney mercury concentration than 10 [mu] g / Nm ³ -dry When it is high and lower than 40 μg / Nm ³ -dry, it is gradually increased as the mercury concentration increases, and when the chimney mercury concentration is higher than 40 μg / Nm ³ -dry, a constant maximum value of 500 mg / Nm ³ is set. I have to.

Although the mercury concentration at the bag filter inlet fluctuates due to fluctuations in the supplied dust properties, the peak measured value of the mercury concentration at the chimney could be suppressed to 70 μg / Nm ³ -dry even in the highest case.

<Example 2>
In Example 2, the exhaust gas treatment apparatus shown in FIG. 2 was used to treat the exhaust gas containing mercury. The mercury concentration in the exhaust gas at the bag filter inlet was measured, and the activated carbon was supplied by obtaining the activated carbon supply amount using the correspondence between the bag filter inlet mercury concentration and the activated carbon supply amount shown in FIG. As shown in FIG. 6, when the mercury concentration at the bag filter inlet is lower than 100 μg / Nm ³ -dry, the activated carbon supply amount is 50 mg / Nm ³ as a certain minimum value, and the mercury concentration at the bag filter is 100 μg / Nm. ³ If higher than 700 [mu] g / Nm ³ below -dry -dry gradually increase with increasing mercury concentration, 500 mg of the maximum value constant when the bag filter inlet mercury concentration greater than 700 [mu] g / Nm ³ -dry It is as in the / Nm ^3.

Although the mercury concentration at the bag filter inlet fluctuates due to fluctuations in the supplied dust properties, the peak measurement value of the mercury concentration in the chimney could be suppressed to 25 μg / Nm ³ -dry even in the highest case.

<Example 3>
In Example 3, the exhaust gas treatment apparatus shown in FIG. 3 was used to treat the exhaust gas containing mercury. The mercury concentration in the exhaust gas at the bag filter inlet is measured, the base amount of the activated carbon supply is controlled, the mercury concentration in the exhaust gas at the chimney is measured, and the bag filter inlet mercury concentration and the activated carbon supply amount shown in FIG. The base amount of the activated carbon supply amount was controlled using the correspondence relationship, and the activated carbon supply amount was complemented and increased or decreased using the correspondence relationship between the chimney mercury concentration and the activated carbon supply amount shown in FIG.

Although the mercury concentration at the bag filter inlet fluctuates due to fluctuations in the supplied dust properties, the peak measurement value of the mercury concentration in the chimney could be suppressed to 15 μg / Nm ³ -dry even in the highest case.

1 furnace (incinerator)
2 Boiler 3 Activated carbon supply device 4 Dust collector (bug filter)
5 Mercury concentration meter 5A First mercury concentration meter 5B Second mercury concentration meter 6 Chimney 7 Controller

Claims (16)

In an exhaust gas treatment apparatus comprising: a dust collector that removes exhaust gas containing mercury discharged from a furnace; and an activated carbon supply device that blows activated carbon into an exhaust gas passage that guides the exhaust gas from the furnace to the dust collector.
An upstream mercury concentration meter that measures the mercury concentration in the exhaust gas downstream of the furnace and upstream of the dust collector, and a downstream mercury concentration meter that measures the mercury concentration in exhaust gas downstream of the dust collector; A control device that controls the amount of activated carbon supplied by the activated carbon supply device is provided.
The control device maintains the activated carbon supply amount at a predetermined minimum value or more, and on the downstream side of the dust collector based on the mercury concentration measurement value by the upstream mercury concentration meter and the mercury concentration measurement value by the downstream mercury concentration meter. An exhaust gas treatment apparatus that controls the supply amount of activated carbon so that the mercury concentration in the exhaust gas at the plant is less than a set value. The control device controls to keep the activated carbon supply amount at a predetermined maximum value when the measured mercury concentration value by the upstream mercury concentration meter or the downstream mercury concentration meter is equal to or higher than the respective predetermined mercury concentration. Item 2. An exhaust gas treatment apparatus according to Item 1. The control device predetermines the downstream mercury concentration ratio of the mercury concentration measurement value in the exhaust gas downstream of the dust collector by the downstream mercury concentration meter to the mercury concentration set value in the exhaust gas downstream of the dust collector. When the ratio is equal to or greater than the ratio, or the mercury concentration measurement value in the exhaust gas upstream of the dust collector by the upstream mercury concentration meter, the upstream mercury concentration relative to the mercury concentration set value in the exhaust gas downstream of the dust collector When the ratio is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined downstream mercury concentration ratio is determined within a range of 0.4 to 0.8, The exhaust gas processing apparatus according to claim 1 , wherein the upstream mercury concentration ratio to be determined is set within a range of 20 to 200. Controller, a predetermined minimum value of the activated carbon supply amount determined as activated carbon blow by weight with respect to the processing gas flow rate, of the claims 1 to 3 and can be controlled by setting the 10 to 200 mg / Nm ³ The exhaust gas treatment apparatus according to one. Controller according to a predetermined maximum value of the activated carbon supply amount determined as activated carbon blow by weight with respect to the processing gas flow rate, to claim 2 or claim 3 and be controlled by setting the 300~1000mg / Nm ³ Exhaust gas treatment equipment. Controller controls the predetermined minimum value of the activated carbon supply amount determined as activated carbon blow by weight with respect to the processing gas flow rate is set to 10 to 200 mg / Nm ^3, by setting a predetermined maximum value 300~1000mg / Nm ³ The exhaust gas treatment apparatus according to claim 2 or claim 3 to be performed.   The control device shall be based on the activated carbon supply amount of the predetermined minimum value in the range from the measured value of the mercury concentration in the exhaust gas to zero or less than the measurable minimum value to the first predetermined mercury concentration. Activated charcoal is supplied, and after the mercury concentration measurement value reaches the first specified mercury concentration, the activated carbon supply amount is linearly increased from the predetermined minimum value as the mercury concentration measurement value increases, and the mercury concentration measurement is performed. When the value reaches the second predetermined mercury concentration, the activated carbon supply amount is set to the predetermined maximum supply amount, and after the mercury concentration measurement value reaches the second predetermined mercury concentration, the mercury concentration measurement value The exhaust gas treatment device according to claim 1, wherein the activated carbon supply amount is kept constant at a predetermined maximum value with respect to the increase.   The control device sets the first supply amount at a predetermined minimum value in a range from the value where the measured mercury concentration in the exhaust gas is zero or less than the minimum measurable limit to the first predetermined mercury concentration. Activated carbon is supplied under the activated carbon supply amount, and when the mercury concentration measurement value reaches the first predetermined mercury concentration, the activated carbon supply amount is increased stepwise to the predetermined second supply amount, When the measured mercury concentration reaches the second predetermined mercury concentration, the activated carbon supply rate is kept constant at the second supply amount, and when the measured mercury concentration value reaches the second predetermined mercury concentration. In order to increase the activated carbon supply amount to a predetermined third supply amount, the activated carbon supply amount is increased stepwise as the mercury concentration measurement value increases, and the activated carbon supply amount is increased to a predetermined maximum value. After the increase to Exhaust gas treatment apparatus according to claim 1, keeping constant the activated carbon supply amount at the predetermined maximum value. In the exhaust gas treatment method in which activated carbon is blown from the activated carbon supply device from the activated carbon supply device to the exhaust gas flow path that guides the exhaust gas from the furnace to the dust collection device by exhausting the exhaust gas containing mercury discharged from the furnace,
Measurement of the mercury concentration in the exhaust gas at the downstream side of the furnace and upstream of the dust collector with an upstream mercury concentration meter and the mercury concentration in the exhaust gas at the downstream side of the dust collector with a downstream mercury concentration meter And a control step for controlling the activated carbon supply amount of the activated carbon supply device by the control device,
In the control process, the activated carbon supply amount is maintained above the predetermined minimum value, and the downstream side of the dust collector is based on the measured mercury concentration value by the upstream mercury concentration meter and the measured mercury concentration value by the downstream mercury concentration meter. A method for treating exhaust gas, wherein the activated carbon supply amount is controlled so that the mercury concentration in the exhaust gas at or below is less than a set value. In the control step, when the mercury concentration measurement value by the upstream mercury concentration meter or the downstream mercury concentration meter is equal to or higher than each predetermined mercury concentration, the activated carbon supply amount is controlled to be maintained at a predetermined maximum value. Item 10. The exhaust gas treatment method according to Item 9 . In the control step, the downstream mercury concentration ratio of the mercury concentration measurement value in the exhaust gas downstream of the dust collector by the downstream mercury concentration meter to the mercury concentration set value in the exhaust gas downstream of the dust collector is predetermined. When the ratio is equal to or greater than the ratio, or the mercury concentration measurement value in the exhaust gas upstream of the dust collector by the upstream mercury concentration meter, the upstream mercury concentration relative to the mercury concentration set value in the exhaust gas downstream of the dust collector When the ratio is equal to or higher than a predetermined ratio, the activated carbon supply amount is controlled to be kept at a predetermined maximum value, and the predetermined downstream mercury concentration ratio is determined within a range of 0.4 to 0.8, The exhaust gas treatment method according to claim 9 , wherein the upstream mercury concentration ratio to be determined is set within a range of 20 to 200. Control step, a predetermined minimum value of the activated carbon supply amount determined as activated carbon blow by weight with respect to the processing gas flow rate, of the claims 9 to 11, to be controlled by setting the 10 to 200 mg / Nm ³ The exhaust gas treatment method according to one. Control step, according to predetermined maximum value of the activated carbon supply amount determined as activated carbon blow by weight with respect to the processing gas flow rate, in claim 10 or claim 11 and be controlled by setting the 300~1000mg / Nm ³ Exhaust gas treatment method. Control step, controls the predetermined minimum value of the activated carbon supply amount determined as activated carbon blow by weight with respect to the processing gas flow rate is set to 10 to 200 mg / Nm ^3, by setting a predetermined maximum value 300~1000mg / Nm ³ The exhaust gas treatment method according to claim 10 or claim 11 to be performed. In the control process, the measured value of the mercury concentration in the exhaust gas is zero or less than the minimum measurable minimum value until the first predetermined mercury concentration is reached. Activated charcoal is supplied, and after the mercury concentration measurement value reaches the first specified mercury concentration, the activated carbon supply amount is linearly increased from the predetermined minimum value as the mercury concentration measurement value increases, and the mercury concentration measurement is performed. When the value reaches the second predetermined mercury concentration, the activated carbon supply amount is set to the predetermined maximum supply amount, and after the mercury concentration measurement value reaches the second predetermined mercury concentration, the mercury concentration measurement value The exhaust gas treatment method according to claim 9 , wherein the activated carbon supply amount is kept constant at the predetermined maximum value with respect to the increase. The control process includes a first supply amount at a predetermined minimum value in a range from a value where the measured mercury concentration in the exhaust gas is zero or less than the minimum measurable minimum value to the first predetermined mercury concentration. Activated carbon is supplied under the activated carbon supply amount, and when the mercury concentration measurement value reaches the first predetermined mercury concentration, the activated carbon supply amount is increased stepwise to the predetermined second supply amount, When the measured mercury concentration reaches the second predetermined mercury concentration, the activated carbon supply rate is kept constant at the second supply amount, and when the measured mercury concentration value reaches the second predetermined mercury concentration. In order to increase the activated carbon supply amount to a predetermined third supply amount, the activated carbon supply amount is increased stepwise as the mercury concentration measurement value increases, and the activated carbon supply amount is increased to a predetermined maximum value. After the increase to Exhaust gas treatment method according to claim 9, it is kept constant activated carbon supply amount at the predetermined maximum value.

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