JP2010227747A - Exhaust gas treatment apparatus and exhaust gas treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment apparatus and an exhaust gas treatment method following variation in the existence condition of heavy metals in an exhaust gas in a short period of time and supplying the appropriate amount of an adsorbent without making a supply amount excessive. <P>SOLUTION: The exhaust gas treatment apparatus 1 includes: an adsorbent supply device 10 for supplying the adsorbent for adsorbing the heavy metals included in the exhaust gas to the exhaust gas; a dust collector 20 for receiving the exhaust gas supplied with the adsorbent and removing the adsorbent which has adsorbed the heavy metals included in the exhaust gas and dust; a particle size distribution measuring device 40 for measuring the particle size distribution of fine particles of the heavy metals in the exhaust gas discharged from the dust collector 20; and a controller 50 for deriving the concentration of the heavy metals indicating the existence condition of the heavy metals in the exhaust gas on the basis of the particle size distribution of the fine particles measured by the particle size distribution measuring device 40 and controlling the supply amount of the adsorbent to be supplied to the exhaust gas on the basis of the derived concentration of the heavy metals. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an exhaust gas treatment apparatus and an exhaust gas treatment method containing heavy metals.

  Removal of heavy metals contained in exhaust gas discharged from heat treatment processes such as combustion furnace equipment, melting equipment, and heating equipment in waste incineration facilities and steel refining facilities is being considered to make the exhaust gas harmless. . Since heavy metals have different vapor pressures depending on the form of the compound that can be produced, they are in a gaseous state depending on the temperature and atmospheric conditions in the exhaust gas treatment process. Since gaseous heavy metals pass through the dust collector, they cannot be captured by the dust collector. Gaseous heavy metals that have passed through the dust collector are condensed in the flue and after being released into the atmosphere to form particulate matter with a very small particle size, which is harmful to the human body. Further, even when gaseous heavy metals condense on the upstream side of the dust collector, the heavy metals become a particulate material having a very small particle diameter. The particulate matter cannot be sufficiently captured by a commonly used dust collector and flows out into the atmosphere.

  As a measure for removing heavy metals from exhaust gas before releasing the exhaust gas to the atmosphere, Patent Document 1 introduces exhaust gas into a dust collector to remove dust, and adsorbent in the exhaust gas before the dust collector. An exhaust gas treatment method is disclosed in which heavy metals are removed by collecting an adsorbent that has adsorbed gaseous and particulate heavy metals with the dust collector.

JP2001-212427

  In the waste incineration facility, the concentration of heavy metals in the exhaust gas from the incinerator and the like varies with changes in the type and quantity of waste to be treated. The analysis of heavy metal concentrations including fine particles in exhaust gas is performed by sampling by chemical absorption and quantitative analysis by wet analysis off-site. Concentration of heavy metals could not be obtained.

  Therefore, according to the exhaust gas treatment method of Patent Document 1, it is not possible to control the supply of the adsorbent while monitoring the heavy metal concentration in the exhaust gas. Therefore, in order to remove heavy metals stably at a high removal rate with respect to the concentration of heavy metals in fluctuating exhaust gas as in a waste incineration facility, it is necessary to supply an excessive amount of adsorbent.

  As a result of supplying an excessive amount of adsorbent, the amount of adsorbent used becomes excessive, increasing the cost of exhaust gas treatment, and the amount of adsorbent collected by the dust collector and collected together with the dust becomes excessive. Costs also increase. Further, since the amount of the adsorbent collected by the dust collector becomes excessive, the pressure loss of the filter to which the dust and the adsorbent adhere is increased and the load on the air feeding device is increased. Furthermore, the adsorbent accumulates in the flue, thereby causing an abnormality in the exhaust gas flow or blocking the flue.

  As described above, in the exhaust gas treatment method of Patent Document 1, it is not possible to supply an appropriate amount of adsorbent by following the fluctuation of the heavy metal concentration in the exhaust gas in a short time. Problems can arise.

  In view of such circumstances, the present invention can follow fluctuations in the presence of heavy metals in exhaust gas in a short time, and can supply an appropriate amount of adsorbent without excessive supply. It is an object to provide an exhaust gas treatment apparatus and an exhaust gas treatment method that can be performed.

<First invention>
The exhaust gas treatment apparatus according to the present invention is an apparatus for treating exhaust gas containing heavy metals.

  In such an exhaust gas treatment device, the present invention includes an adsorbent supply device that supplies the exhaust gas with an adsorbent that adsorbs the heavy metals, and a heavy metal that is contained in the exhaust gas after receiving the exhaust gas supplied with the adsorbent. A dust collector that removes the adsorbent and dust adsorbed, a particle size distribution measuring device that measures the particle size distribution of heavy metal fine particles in the exhaust gas discharged from the dust collector, and the particle size distribution measuring device. Further, an adsorbent supply amount control device that obtains an amount indicating the presence state of heavy metals in the exhaust gas based on the particle size distribution of the fine particles and controls the supply amount of the adsorbent supplied to the exhaust gas based on the obtained presence state of heavy metals. It is characterized by having.

  In the present invention, the adsorbent supply amount control device obtains an amount indicating the presence of heavy metals in the exhaust gas based on the particle size distribution measured by the particle size distribution measuring device, and indicates the obtained presence of heavy metals. Therefore, the amount of adsorbent supplied to the exhaust gas is controlled, so that the amount of adsorbent supplied increases or decreases depending on the presence of heavy metals. Therefore, even if the presence state of heavy metals varies, an appropriate amount of adsorbent is always supplied to the exhaust gas in accordance with the variation.

  Control of the amount of adsorbent supplied is, for example, the correlation between the particle size distribution of the actually measured fine particles, the particle size distribution of the fine particles held in advance by the adsorbent supply amount control device, and the amount indicating the presence of heavy metals. This is realized by deriving an amount indicating the presence state of heavy metals based on the data indicating the amount of adsorbent, and increasing or decreasing the supply amount of the adsorbent according to the comparison result between the amount indicating the presence state and a predetermined target concentration.

  The amount indicating the presence of heavy metals in the exhaust gas is the concentration of the heavy metals, and the adsorbent supply amount control device holds in advance data indicating the correlation between the particle size distribution of the fine particles and the concentration of heavy metals. Based on the data, the measured particle size distribution of the fine particles and the corresponding heavy metal concentration are derived, and when the derived heavy metal concentration is higher than a predetermined target concentration, the supply amount of the adsorbent is increased. The adsorbent supply device is controlled so that the adsorbent supply device is controlled to reduce the supply amount of the adsorbent when the derived heavy metal concentration is lower than a predetermined target concentration. It is preferable.

  As described above, the concentration of heavy metals is determined based on the data indicating the correlation between the particle size distribution of the actually measured fine particles and the particle size distribution of the fine particles and the concentration of heavy metals previously held by the adsorbent supply amount control device. It may be derived. Thereby, even if the concentration of heavy metals fluctuates during operation of the exhaust gas treatment device, an appropriate amount of adsorbent can always be supplied to the exhaust gas according to the fluctuation.

  It is preferable to further have a dilution cooling device for diluting and cooling the exhaust gas to be introduced into the particle size distribution measuring device. By diluting and cooling the exhaust gas with the dilution cooling device, gaseous heavy metals contained in the exhaust gas are condensed into fine particles, and the particle size distribution can be measured. As a result, by deriving the heavy metal concentration based on the particle size distribution of the fine particles, an accurate heavy metal concentration can be obtained, and the amount of adsorbent supplied can be more appropriate.

  The adsorbent supply device preferably supplies at least one of activated carbon, kaolin and clay mineral as an adsorbent into the exhaust gas.

<Second invention>
The exhaust gas treatment method according to the present invention is a method for treating exhaust gas containing heavy metals.

  In the exhaust gas treatment method, the present invention includes an adsorbent supply step of supplying an adsorbent that adsorbs the heavy metals to the exhaust gas, and a heavy metal contained in the exhaust gas that receives the exhaust gas supplied with the adsorbent. It was measured in the dust collection process for removing the adsorbent and dust adsorbed, the particle size distribution measurement process for measuring the particle size distribution of heavy metal fine particles in the exhaust gas discharged in the dust collection process, and the particle size distribution measurement process. An adsorbent supply amount control step for obtaining an amount indicating the presence of heavy metals in the exhaust gas based on the particle size distribution of the fine particles, and controlling the amount of adsorbent supplied to the exhaust gas based on the obtained presence of heavy metals. It is characterized by having.

  In the present invention, in the adsorbent supply amount control step, an amount indicating the presence status of heavy metals in the exhaust gas is obtained based on the particle size distribution measured in the particle size distribution measurement step, and based on the obtained presence status of heavy metals. Thus, since the amount of adsorbent supplied to the exhaust gas is controlled, the amount of adsorbent supplied increases or decreases depending on the presence of heavy metals. Therefore, even if the presence state of heavy metals varies, an appropriate amount of adsorbent is always supplied to the exhaust gas in accordance with the variation.

  According to the present invention, the amount indicating the presence of heavy metals determined based on the particle size distribution measured on-site is obtained, and the amount of adsorbent supplied is increased or decreased according to this amount. The supply amount can be followed in a short time with respect to the fluctuation of the existing state, and an appropriate amount of adsorbent can be supplied into the exhaust gas.

It is a block diagram which shows the structure of the exhaust gas processing apparatus which concerns on embodiment. It is a flowchart which shows control of the supply amount of the adsorption agent in the exhaust gas processing apparatus of FIG.

  Hereinafter, an embodiment of an exhaust gas treatment apparatus according to the present invention will be described based on the accompanying drawings.

  FIG. 1 is a block diagram showing a configuration of an exhaust gas treatment apparatus 1 according to the present embodiment. In the figure, the paths of the exhaust gas and the adsorbent are indicated by solid lines, and the paths of the electric signals are indicated by broken lines. The exhaust gas treatment apparatus 1 is provided between a heat treatment furnace 2 that exhausts exhaust gas containing gaseous heavy metals and a chimney 3 that releases the exhaust gas into the atmosphere. The heat treatment furnace 2 is, for example, a combustion furnace, a melting furnace, a heating device or the like in a waste incineration facility or a steel refining facility.

  The exhaust gas treatment device 1 receives an adsorbent supply device 10 for supplying an adsorbent for adsorbing heavy metals contained in the exhaust gas from the heat treatment furnace 2 into the exhaust gas, and an exhaust gas supplied with the adsorbent. A dust collector 20 that removes the adsorbent and dust adsorbing heavy metals in the exhaust gas, and a cooling gas is added to a part of the exhaust gas discharged from the dust collector 20 to dilute and cool the exhaust gas. A dilution cooling device 30 for condensing gaseous heavy metals to form fine particles, and a particle size distribution measuring device 40 for measuring the particle size distribution of heavy metal fine particles present in the exhaust gas discharged from the dilution cooling device 30; And a control device 50 for controlling the amount of adsorbent supplied based on the particle size distribution of the fine particles measured by the particle size distribution measuring device.

  The adsorbent supply device 10 blows the powdery adsorbent into the flue through which the exhaust gas flows from the heat treatment furnace 2 to the dust collector 20. The adsorbent supply device 10 includes an adsorbent storage tank (not shown) for storing the adsorbent, and a cutout that cuts out the adsorbent stored in the adsorbent storage tank, which includes a screw feeder, a rotary feeder, and the like. It has a device (not shown) and a blowing nozzle (not shown) for blowing the adsorbent cut out by the cutting device into the flue. The adsorbent is powdery and is preferably activated carbon, kaolin or clay mineral. Examples of the clay mineral include kaolinite, montmorillonite, halloysite, bentonite, dickite, illite and the like.

  The adsorbent supply apparatus 10 may supply a plurality of types of the activated carbon, kaolin, or clay mineral as an adsorbent. In this case, a plurality of adsorbent storage tanks and cutting devices are provided corresponding to each type of adsorbent. In the present embodiment, the adsorbent supply device 10 blows the adsorbent into the flue between the heat treatment furnace 2 and the dust collector 20, but instead, the blowing nozzle is used as the dust collector. The adsorbent may be blown into the upstream side of the filter of the dust collector 20.

  The dust collector 20 is constituted by, for example, a bag filter, a ceramic filter, and the like. The dust collector 20 receives the exhaust gas supplied with the adsorbent by the adsorbent supply device 10 and adsorbs the heavy metal in the exhaust gas and dust. Is collected and removed. The heavy metals contained in the exhaust gas from the heat treatment furnace 2 are in the form of gas and pass through the filter of the dust collector 20 as they are. In this embodiment, the gaseous heavy metals are easily collected by adsorbing the gaseous heavy metals with the adsorbent and collecting the adsorbent with the dust collector 20. Heavy metals that have not been adsorbed by the adsorbent pass through the dust collector 20 and are discharged from the dust collector 20. Hereinafter, heavy metals contained in the exhaust gas discharged from the dust collector 20, that is, heavy metals not collected by the dust collector 20, are referred to as “residual heavy metals”.

  The dilution cooling device 30 dilutes and cools the exhaust gas by adding a cooling gas to a part of the exhaust gas collected for measurement in the flue through which the exhaust gas flows from the dust collector 20 to the chimney 3. As a result, gaseous residual heavy metals contained in the collected exhaust gas are condensed into fine particles. Further, the remaining part of the exhaust gas not collected by the dilution cooling device 30 is released from the chimney 3 into the atmosphere. In the present embodiment, as will be described later, by controlling the supply amount of the adsorbent, the concentration of residual metals contained in the exhaust gas released into the atmosphere is reduced to an appropriate value. The dilution cooling device 30 is not essential, and it is not necessary to provide the dilution cooling device 30 when the heavy metals contained in the exhaust gas from the dust collector 20 are in the form of fine particles. In this case, a part of the exhaust gas collected from the flue is directly introduced into the particle size distribution measuring device 40 described later.

  The particle size distribution measuring device 40 measures the particle size distribution of fine particles of residual heavy metals contained in the exhaust gas cooled by the dilution cooling device 30. The particle size distribution measuring device 40 includes, for example, an electronic low-pressure impactor, a scanning mobility particle sizer (SMPS), a laser diffraction / scattering particle size distribution measuring device, and the like.

  The electronic low-pressure impactor is a device that applies an electrical process to a classifier called an impactor that applies the principle of inertial collision so that the particle size distribution can be measured online. The scanning mobility particle sizer is a device that can measure the particle size distribution by utilizing the one-to-one relationship between the particle size of charged fine particles and the electric mobility. The laser diffraction / scattering type particle size distribution measuring device is an apparatus that can measure the particle size distribution by utilizing the fact that the amount of scattered light and the scattering pattern differ depending on the particle diameter when the fine particles are irradiated with laser light.

  The particle size distribution measuring device 40 transmits the measured particle size distribution to the control device 50 as a measurement data signal.

  The control device 50 derives the concentration for deriving the concentration of residual heavy metals in the exhaust gas (hereinafter referred to as “residual heavy metal concentration”) based on the particle size distribution of the fine particles of residual heavy metals measured by the particle size distribution measuring device 40. 51, a supply amount determination unit 52 for determining the supply amount of the adsorbent based on the residual heavy metal concentration derived by the concentration deriving unit 51, derivation of the residual heavy metal concentration by the concentration deriving unit 51 and the supply And a data holding unit 53 that holds data used for determining the supply amount of the adsorbent by the amount determining unit 52.

  The data holding unit 53 holds in advance a database showing a correlation between a plurality of fine particle size distributions and a heavy metal concentration obtained by a chemical analysis method corresponding to each of the fine particle size distributions. The data holding unit 53 also holds in advance data of a target value (hereinafter referred to as “target concentration”) of the residual heavy metal concentration. The target concentration is determined based on, for example, exhaust gas emission regulations.

  The concentration deriving unit 51 receives a measurement data signal from the particle size distribution measuring device 40 and compares the measured particle size distribution with a database held by the data holding unit 53 to derive the concentration of residual metals. To do.

  The supply amount determination unit 52 compares the data of the residual heavy metal concentration of the residual metal derived by the concentration deriving unit 51 with the data of the target concentration held in advance by the data holding unit 53. When the residual heavy metal concentration is higher than the target concentration, the adsorbent supply device 10 is controlled so as to increase the supply amount of the adsorbent, and when the fine particle concentration is lower than the target concentration, the supply of the adsorbent is performed. It is set to control the adsorbent supply device 10 so as to reduce the amount.

  Hereinafter, the exhaust gas treatment operation of the exhaust gas treatment device 1 according to the present embodiment will be described.

  FIG. 2 is a flowchart showing control of the amount of adsorbent supplied in the exhaust gas treatment apparatus 1. First, the adsorbent supply device 10 supplies the adsorbent to the exhaust gas from the heat treatment furnace 2 (S1). Next, the dust collector 20 collects the adsorbent and dust that have adsorbed heavy metals in the exhaust gas (S2). Next, the dilution cooling device 30 collects a part of the exhaust gas discharged from the dust collector 20 and dilutes and cools the exhaust gas (S3). As a result, gaseous residual heavy metals contained in the exhaust gas are condensed into fine particles. Then, the particle size distribution measuring device 40 measures the particle size distribution of the residual heavy metal fine particles (S4).

  Next, the concentration deriving unit 51 compares the measured particle size distribution with a database held by the data holding unit 53 to derive a residual metal concentration (S5). Then, the supply amount determination unit 52 determines the supply amount of the adsorbent based on the residual heavy metal concentration, and controls the adsorbent supply device 10. Specifically, when the residual heavy metal concentration is higher than the target concentration (Y in S6), the supply amount determination unit 52 controls the adsorbent supply device 10 to increase the supply amount of the adsorbent. When the fine particle concentration is smaller than the target concentration (N in S6), the supply amount determination unit 52 controls the adsorbent supply device 10 so as to decrease the supply amount of the adsorbent. Specifically, for example, the output of the cutting device of the adsorbent supply device is controlled to an appropriate value. As a result, the residual metal concentration approaches the target concentration.

  In the present embodiment, during operation of the exhaust gas treatment device 1, the concentration of heavy metals contained in the exhaust gas from the dust collector 20 is derived, and the amount of adsorbent supplied is controlled based on the derived concentration of residual heavy metals. did. Therefore, even if the concentration of heavy metals in the exhaust gas fluctuates, the amount of adsorbent supplied can be increased or decreased in accordance with the fluctuation, so that the amount supplied can be followed in a short time, and an appropriate amount of adsorption can always be achieved. The agent can be supplied. As a result, the concentration of residual heavy metals contained in the exhaust gas finally released into the atmosphere can be reduced to an appropriate value.

  Moreover, since an excessive amount of adsorbent is not supplied, it is possible to suppress an increase in exhaust gas treatment costs and dust treatment costs. In addition, the filter pressure loss of the filter does not increase due to the filter of the dust collector collecting an excessive amount of adsorbent, and as a result, an increase in the load of the air supply device can be prevented. In addition, it is possible to prevent an abnormal flow of the exhaust gas and blockage of the flue caused by an excessive amount of adsorbent being deposited in the flue.

  INDUSTRIAL APPLICABILITY The present invention can be used in the industrial field for removing gaseous or particulate heavy metals in a gas.

DESCRIPTION OF SYMBOLS 1 Exhaust gas processing apparatus 10 Adsorbent supply apparatus 20 Dust collector 30 Dilution cooling apparatus 40 Particle size distribution measuring apparatus 50 Control apparatus (adsorbent supply amount control apparatus)

Claims (5)

In exhaust gas treatment equipment containing heavy metals,
An adsorbent supply device that supplies the exhaust gas with an adsorbent that adsorbs the heavy metals;
A dust collector that receives the exhaust gas supplied with the adsorbent and removes the adsorbent and dust adsorbing heavy metals contained in the exhaust gas;
A particle size distribution measuring device for measuring the particle size distribution of fine particles of heavy metals in the exhaust gas discharged from the dust collector;
Based on the particle size distribution of the fine particles measured by the particle size distribution measuring device, an amount indicating the presence of heavy metals in the exhaust gas is obtained, and the amount of adsorbent supplied to the exhaust gas is determined based on the obtained presence of heavy metals. An adsorbent supply amount control device to control,
An exhaust gas treatment apparatus comprising: The amount indicating the presence of heavy metals in the exhaust gas is the concentration of the heavy metals,
The adsorbent supply amount control device holds in advance data indicating the correlation between the particle size distribution of fine particles and the concentration of heavy metals, and the heavy metal concentration corresponding to the particle size distribution measured above based on the data Is derived,
When the derived heavy metal concentration is higher than a predetermined target concentration, the adsorbent supply device is controlled to increase the adsorbent supply amount,
2. The adsorbent supply device is set to perform control so as to reduce the supply amount of the adsorbent when the derived heavy metal concentration is smaller than a predetermined target concentration. Exhaust gas treatment equipment.   The exhaust gas treatment device according to claim 1 or 2, further comprising a dilution cooling device for diluting and cooling the exhaust gas introduced into the particle size distribution measuring device.   The exhaust gas treatment device according to any one of claims 1 to 3, wherein the adsorbent supply device supplies at least one of activated carbon, kaolin, and clay mineral as an adsorbent into the exhaust gas. In a method for treating exhaust gas containing heavy metals,
An adsorbent supply step of supplying an adsorbent that adsorbs the heavy metals to the exhaust gas;
A dust collection step of receiving the exhaust gas supplied with the adsorbent and removing the adsorbent and dust adsorbing heavy metals contained in the exhaust gas;
A particle size distribution measuring step for measuring a particle size distribution of fine particles of heavy metals in the exhaust gas discharged in the dust collecting step;
Based on the particle size distribution of the fine particles measured in the particle size distribution measurement step, the amount indicating the presence of heavy metals in the exhaust gas is obtained, and the amount of adsorbent supplied to the exhaust gas is controlled based on the obtained presence of heavy metals. Adsorbent supply amount control step to perform,
An exhaust gas treatment method characterized by comprising: