JP7299721B2 - Exhaust gas treatment system and exhaust gas treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an exhaust gas treatment system and an exhaust gas treatment method.

When waste containing mercury is incinerated in an incinerator, exhaust gas containing mercury may be emitted. If such exhaust gas is released into the atmosphere as it is, air pollution will be caused. Therefore, it is required to remove the mercury in the exhaust gas.

As a method for removing mercury in exhaust gas, a method using activated carbon is known (see Patent Documents 1 to 3, for example). In such a method, powdery activated carbon is blown into the exhaust gas to cause the activated carbon to adsorb mercury contained in the exhaust gas.

WO2016/132894 JP 2017-94318 A JP 2017-94319 A

If the amount of activated carbon supplied to the concentration of mercury is smaller than necessary, exhaust gas containing mercury may be released into the atmosphere. On the other hand, if the supply amount of activated carbon is larger than necessary with respect to the concentration of mercury, the cost of treating exhaust gas will increase. Therefore, it is desirable to supply the optimum amount of activated carbon for the concentration of mercury.

Conventionally, the amount of activated carbon to be supplied is linearly or stepwise determined based on the measured mercury concentration (see, for example, Patent Documents 1 to 3). However, the concentration of mercury varies continuously depending on the type of waste being incinerated. Therefore, it is difficult to accurately determine the amount of activated carbon to be supplied based on continuously varying mercury concentration measurements.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an exhaust gas treatment system and an exhaust gas treatment method that can accurately determine the optimum supply amount of activated carbon for the concentration of mercury.

In one aspect, a dust collector that removes harmful substances contained in exhaust gas, and mercury contained in the exhaust gas that is disposed upstream of the dust collector in the flow direction of the exhaust gas and is introduced into the dust collector. A mercury meter that measures the concentration of the dust collector, an activated carbon supply device that supplies activated carbon to the exhaust gas introduced into the dust collector, and a control device that controls the amount of activated carbon supplied from the activated carbon supply device, The control device calculates an average mercury concentration value measured by the mercury meter by a moving average, and uses the calculated average mercury concentration value as a first nonlinear function for determining the supply amount of activated carbon. to calculate a first supply of activated carbon.

In one aspect, the first nonlinear function is a function such that the first supply amount of the activated carbon is zero when the mercury concentration is zero.
In one aspect, the control device calculates a rate of change in the concentration of mercury measured by the mercury meter, and uses the calculated rate of change in the concentration of mercury to determine a temporary supply amount of activated carbon. inputting to a second non-linear function to calculate a second supply amount of activated carbon; adding the calculated second supply amount of activated carbon to the calculated first supply amount of activated carbon to obtain a total supply amount of activated carbon; to decide.

In one aspect, the exhaust gas treatment system further includes an exhaust gas flow meter arranged downstream of the dust collector in the flow direction of the exhaust gas, and the control device controls the A third supply amount of activated carbon is determined based on the correlation between the flow rate of exhaust gas and the supply amount of activated carbon, and the determined third supply amount of activated carbon is added to the calculated first supply amount of activated carbon. to determine the total supply of activated carbon.
In one aspect, the control device calculates an average value of the actual supply amount of activated carbon supplied from the activated carbon supply device by a moving average, and calculates the calculated average value of the supply amount of activated carbon by the first nonlinear function. to calculate the first supply amount of the activated carbon.

In one aspect, in the flow direction of the exhaust gas, the average value of the concentration of mercury measured by a mercury meter arranged upstream of a dust collector that removes harmful substances contained in the exhaust gas is calculated by a moving average, A method for treating exhaust gas is provided, in which the calculated average mercury concentration is input to a first nonlinear function for determining the supply amount of activated carbon to calculate the first supply amount of activated carbon.

In one aspect, the first nonlinear function is a function such that the first supply amount of the activated carbon is zero when the mercury concentration is zero.
In one aspect, the rate of change in the concentration of mercury measured by the mercury meter is calculated, and the calculated rate of change in the concentration of mercury is applied to a second nonlinear function for determining the temporary supply amount of activated carbon. input, calculate a second supply amount of activated carbon, and add the calculated second supply amount of activated carbon to the calculated first supply amount of activated carbon to determine a total supply amount of activated carbon.

In one aspect, in the flow direction of the exhaust gas, the third supply of activated carbon is performed based on the correlation between the flow rate of the exhaust gas measured by an exhaust gas flow meter arranged downstream of the dust collector and the supply amount of activated carbon. and adding the determined third supply amount of activated carbon to the calculated first supply amount of activated carbon to determine a total supply amount of activated carbon.
In one aspect, the average value of the actual supply amount of activated carbon supplied from the activated carbon supply device that supplies activated carbon to the exhaust gas introduced into the dust collector is calculated by moving average, and the calculated supply amount of activated carbon is calculated. The average value is input to the first nonlinear function to calculate the first supply amount of the activated carbon.

In one reference example, a dust collector that removes harmful substances contained in exhaust gas, and a A mercury meter that measures the concentration of mercury, an activated carbon supply device that supplies activated carbon to the exhaust gas introduced into the dust collector, and a control device that controls the amount of activated carbon supplied from the activated carbon supply device. , the control device comprises a storage device storing a program, and a processing device for executing calculations according to the program, the program calculating a moving average of the average value of the concentration of mercury measured by the mercury meter. and inputting the calculated average mercury concentration to a first non-linear function for determining the supply amount of activated carbon to calculate the first supply amount of activated carbon. An exhaust gas treatment system is provided that allows

The controller determines the supply of activated carbon using a first non-linear function represented by a curve. Therefore, the control device can bring the supply amount of activated carbon determined by the first nonlinear function closer to the desired supply amount of activated carbon. As a result, the controller can accurately determine the optimum activated carbon feed rate for the mercury concentration.

1 illustrates an embodiment of an exhaust gas treatment system; FIG. FIG. 4 is a diagram showing control blocks of a control device;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a diagram showing an embodiment of an exhaust gas treatment system 1. As shown in FIG. As shown in FIG. 1, an exhaust gas treatment system 1 includes a dust collector 2 for removing harmful substances contained in exhaust gas, and a dust collector 2 disposed upstream of the dust collector 2 in the flow direction of the exhaust gas. a mercury meter 3 for measuring the concentration of mercury contained in the flue gas introduced into the dust collector 2; , and a control device 5 for controlling the amount of activated carbon supplied from the activated carbon supply device 4 .

The exhaust gas treatment system 1 includes an incinerator 10 that incinerates waste and a boiler 11 that recovers heat from the exhaust gas generated in the incinerator 10 . The incinerator 10 is arranged upstream of the dust collector 2 , and the boiler 11 is arranged downstream of the incinerator 10 . When waste is incinerated in the incinerator 10, the incinerator 10 generates high-temperature exhaust gas. The high-temperature flue gas is cooled by the boiler 11 and transferred to the dust collector 2 . Steam generated in the boiler 11 is transferred to a turbine (not shown) and used for power generation.

Mercury meter 3 and activated carbon supply device 4 are arranged in flue gas flow path 15 between boiler 11 and dust collector 2 . The mercury meter 3 measures the concentration of mercury contained in the exhaust gas flowing through the exhaust gas channel 15 . The activated carbon supply device 4 arranged downstream of the mercury meter 3 blows a determined amount of activated carbon into the exhaust gas flow path 15 based on the concentration of mercury measured by the mercury meter 3 . Mercury contained in the exhaust gas is adsorbed by the activated carbon blown into the exhaust gas flow path 15 and removed.

In the dust collector 2, harmful substances contained in the exhaust gas are removed, and the exhaust gas from which the harmful substances have been removed is released to the atmosphere from the chimney 13. The exhaust gas treatment system 1 further includes an exhaust gas flow meter 14 arranged downstream of the dust collector 2 in the flow direction of the exhaust gas. In this embodiment, the exhaust gas flow meter 14 is attached to the chimney 13 and measures the flow rate of the exhaust gas flowing inside the chimney 13 .

As shown in FIG. 1 , the mercury meter 3 , the activated carbon supply device 4 and the exhaust gas flow meter 14 are electrically connected to the control device 5 . The control device 5 is configured to accurately determine the optimal supply of activated carbon based on the concentration of mercury sent from the mercury meter 3 . The configuration of the control device 5 will be described below.

FIG. 2 is a diagram showing a control block of the control device 5. As shown in FIG. As shown in FIG. 2 , the concentration of mercury (more specifically, electrical signal) measured by the mercury meter 3 is sent to the control device 5 . The control device 5 includes a storage device 5a storing a program, and a processing device 5b that executes calculations according to the program (see FIG. 1). The program calculates the average value of the mercury concentration measured by the mercury meter 3 by moving average, and inputs the calculated average value of the mercury concentration to the first nonlinear function for determining the supply amount of activated carbon. contains a command for calculating the first supply amount of activated carbon (see control block CB1 in FIG. 2).

A computer control unit 5 receives an electrical signal corresponding to the concentration of mercury measured by the mercury meter 3 . Mercury concentrations vary continuously depending on the type of waste being incinerated. Therefore, the concentration of mercury measured by the mercury meter 3 may change continuously. The control device 5 integrates continuously changing concentrations of mercury, performs a moving average on the integrated values of mercury concentrations, and calculates an average value of mercury concentrations over a predetermined period of time. In one embodiment, the predetermined time is one hour.

In this way, the controller 5 can eliminate irregular fluctuations in the concentration of mercury by performing a moving average. As a result, the control device 5 can stably supply activated carbon without being affected by irregular fluctuations.

The storage device 5a of the control device 5 stores the first nonlinear function. The first non-linear function is represented by an orthogonal coordinate system in which the horizontal axis indicates the concentration of mercury and the vertical axis indicates the supply amount of activated carbon. In the present embodiment, the first nonlinear function is a function (for example, a quadratic function) in which the supply amount of activated carbon is zero when the concentration of mercury is zero. Therefore, the exhaust gas treatment system 1 can prevent unnecessary supply of activated carbon, and can save activated carbon.

In one embodiment, the first non-linear function may be calculated by performing the following steps. The process of determining the optimum supply amount of activated carbon for the concentration of mercury is repeated multiple times. Regression analysis is performed on a plurality of data points in a coordinate system specified from the concentration of mercury and the amount of supply of activated carbon to calculate a regression equation represented by a quadratic function, and this regression equation is used as a first nonlinear function Decide on the formula.

According to this embodiment, the control device 5 determines the supply amount of activated carbon using the first non-linear function represented by the curve. Therefore, the control device 5 can bring the supply amount of activated carbon determined by the first nonlinear function closer to the desired supply amount of activated carbon. As a result, the controller 5 can accurately determine the optimum supply amount of activated carbon for the concentration of mercury.

As shown in the control block CB2 of FIG. 2, the control device 5 calculates the rate of change in the concentration of mercury measured by the mercury meter 3, and uses the calculated rate of change in the concentration of mercury as the temporary supply of activated carbon. input to a second nonlinear function for determining the amount of activated carbon to calculate a second supply amount of activated carbon; add the calculated second supply amount of activated carbon to the calculated first supply amount of activated carbon; determine the total supply of A program for executing these steps is stored in the storage device 5 a of the control device 5 .

Waste that is incinerated includes waste that has a high concentration of mercury. When such waste is incinerated, the concentration of mercury measured by the mercury meter 3 may temporarily rise sharply. In the control block CB2, the control device 5 determines the supply amount of activated carbon based on the change rate (differential value) of the concentration of mercury over time. Therefore, the control device 5 can quickly respond to such a rapid rise and supply an appropriate amount of activated carbon. Thus, the exhaust gas treatment system 1 can improve the control performance of the control device 5 and enhance the responsiveness of the control device 5 to a rapid increase in mercury concentration.

The second nonlinear function is different than the first nonlinear function. The second non-linear function is expressed in an orthogonal coordinate system in which the horizontal axis indicates the rate of change in mercury concentration and the vertical axis indicates the supply amount of activated carbon. In this embodiment, the second non-linear function is a function (for example, a quadratic function) in which the supply amount of activated carbon is zero when the mercury concentration change rate is zero.

In the present embodiment, the control device 5 sums the first supply amount of activated carbon determined based on the first nonlinear function and the second supply amount of activated carbon determined based on the second nonlinear function, and determine the total supply of According to this embodiment, the controller 5 determines the amount of activated carbon to be supplied in consideration of not only the concentration of mercury but also the rate of change in the concentration of mercury. Therefore, the exhaust gas treatment system 1 can more reliably prevent the release of mercury-containing exhaust gas into the atmosphere.

As shown in the control block CB3 of FIG. 2, the control device 5 determines the third supply amount of activated carbon based on the correlation between the flow rate of exhaust gas measured by the exhaust gas flow meter 14 and the supply amount of activated carbon, The determined third supply amount of activated carbon is added to the calculated first supply amount of activated carbon to determine the total supply amount of activated carbon.

The correlation is stored in the storage device 5a of the control device 5 as a database. This correlation includes the relationship that when the flow rate of the exhaust gas is zero, the supply amount of activated carbon is zero.

Activated carbon adsorbs and removes not only mercury but also dioxins contained in the exhaust gas. Therefore, as a dioxin countermeasure, the control device 5 determines the supply amount of activated carbon according to the flow rate of the exhaust gas so that the supply concentration of activated carbon reaches a predetermined supply concentration. In one embodiment, the target supply concentration of activated carbon is 50 [mg/m ³ N].

In the embodiment shown in FIG. 2, the control device 5 adds the third supply amount to the first supply amount to which the second supply amount is added. In one embodiment, the controller 5 may add the third feed rate to the first feed rate to which the second feed rate is not added.

As shown in the control block CB4 in FIG. 2, the control device 5 compares the third supply amount of activated carbon with a predetermined upper limit value (see HLM in FIG. 2), and reduces the third supply amount to the predetermined upper limit value or less. decide. As shown in the control block CB4, the control device 5 does not have a lower limit value for the supply amount of activated carbon. Note that the control device 5 may perform the A/M conversion operation according to the operator's operation, if necessary.

The control device 5 issues a command to the activated carbon supply device 4 to supply the third supply amount of activated carbon. The activated carbon supply device 4 includes a motor (not shown) and an inverter (not shown) for executing the operation of supplying activated carbon. A proportional relationship exists between the rotation speed of the motor provided in the activated carbon supply device 4 and the current value supplied to the motor. Therefore, a current (4 to 20 mA, for example) corresponding to the third supply amount is sent to the activated carbon supply device 4 based on the command from the control device 5 . As a result, the activated carbon supply device 4 operates the motor to blow activated carbon into the exhaust gas flowing through the exhaust gas passage 15 .

As shown in the control block CB5 of FIG. 2, the control device 5 calculates the average value of the actual supply amount of activated carbon supplied from the activated carbon supply device 4 by moving average, and calculates the average value of the calculated activated carbon supply amount. may be input into the first non-linear function to calculate the first supply amount of activated carbon.

The amount of activated carbon supplied depends on the rotation speed of the motor provided in the activated carbon supply device 4 . Therefore, the control device 5 obtains the supply amount of activated carbon supplied from the activated carbon supply device 4 based on the rotation speed of the motor, and performs a moving average on the obtained integrated value of the supply amount of activated carbon. Then, the average value of the supply amount of activated carbon for a predetermined period of time is calculated. The calculated average value is input to the first nonlinear function to calculate the supply amount of activated carbon.

In this way, the control device 5 inputs the average value of the mercury concentration and the average value of the activated carbon supply amount into the first nonlinear function as parameters for determining the activated carbon supply amount, and determines the activated carbon supply amount. may With such a configuration, the controller 5 can more accurately determine the supply amount of activated carbon for the concentration of mercury.

As indicated by the dotted line arrow in FIG. 2, when the answerback signal from the inverter provided in the activated carbon supply device 4 is not sent to the control device 5 even after a predetermined time has passed, the control device 5 controls the activated carbon supply device 4 may be used to determine the supply amount of activated carbon.

In FIG. 2, the control device 5 comprises control blocks CB1 to CB5. However, the control device 5 may comprise at least the control block CB1. In one embodiment, the controller 5 may comprise a control block CB1 and at least one of the control blocks CB2-CB5.

Although the embodiments of the present invention have been described so far, the present invention is not limited to the above-described embodiments, and can of course be embodied in various different forms within the scope of its technical concept.

1 Exhaust gas treatment system 2 Dust collector 3 Mercury meter 4 Activated carbon supply device 5 Control device 5a Storage device 5b Treatment device 10 Incinerator 11 Boiler 13 Chimney 14 Exhaust gas flow meter 15 Exhaust gas flow path CB1 to CB5 Control block

Claims (8)

A regression analysis was performed on multiple data points in the coordinate system to determine the non-linear function determined based on the regression equation represented by the quadratic function, depending on the continuously varying concentration of mercury. An exhaust gas treatment system for bringing the supply amount closer to the desired supply amount of activated carbon,
a dust collector that removes harmful substances contained in the exhaust gas;
a mercury meter arranged upstream of the dust collector in the flow direction of the exhaust gas and measuring the concentration of mercury contained in the exhaust gas introduced into the dust collector;
an activated carbon supply device that supplies activated carbon to the exhaust gas introduced into the dust collector;
a control device for controlling the amount of activated carbon supplied from the activated carbon supply device,
The control device is
Calculate the average value of the concentration of mercury measured by the mercury meter by moving average,
The calculated average value of the mercury concentration is input to a first non-linear function indicating the correlation between the mercury concentration and the supply amount of activated carbon for determining the supply amount of activated carbon. 1 Calculate the supply amount,
Calculate the rate of change in the concentration of mercury measured by the mercury meter,
Inputting the calculated rate of change in mercury concentration into a second non-linear function representing the correlation between the rate of change in mercury concentration and the supply amount of activated carbon for determining the temporary supply amount of activated carbon. to calculate the second supply amount of activated carbon,
The exhaust gas treatment system, wherein the calculated second supply amount of activated carbon is added to the calculated first supply amount of activated carbon to determine a total supply amount of activated carbon. 2. The exhaust gas treatment system according to claim 1, wherein said first non-linear function is a function such that said first supply amount of activated carbon is zero when said concentration of mercury is zero. A regression analysis was performed on multiple data points in the coordinate system to determine the non-linear function determined based on the regression equation represented by the quadratic function, depending on the continuously varying concentration of mercury. An exhaust gas treatment system for bringing the supply amount closer to the desired supply amount of activated carbon,
a dust collector that removes harmful substances contained in the exhaust gas;
a mercury meter arranged upstream of the dust collector in the flow direction of the exhaust gas and measuring the concentration of mercury contained in the exhaust gas introduced into the dust collector;
an activated carbon supply device that supplies activated carbon to the exhaust gas introduced into the dust collector;
an exhaust gas flow meter disposed downstream of the dust collector in the flow direction of the exhaust gas;
a control device for controlling the amount of activated carbon supplied from the activated carbon supply device,
The control device is
Calculate the average value of the concentration of mercury measured by the mercury meter by moving average,
The calculated average value of the mercury concentration is input to a first non-linear function indicating the correlation between the mercury concentration and the supply amount of activated carbon for determining the supply amount of activated carbon. 1 Calculate the supply amount,
determining a third supply amount of activated carbon based on the correlation between the flow rate of exhaust gas measured by the exhaust gas flow meter and the supply amount of activated carbon;
The exhaust gas treatment system, wherein the determined third supply amount of activated carbon is added to the calculated first supply amount of activated carbon to determine a total supply amount of activated carbon. The control device is
calculating the average value of the actual amount of activated carbon supplied from the activated carbon supply device by a moving average;
The exhaust gas treatment system according to any one of claims 1 to 3, wherein the calculated average value of the supply amount of activated carbon is input to the first nonlinear function to calculate the first supply amount of activated carbon. A regression analysis was performed on multiple data points in the coordinate system to determine the non-linear function determined based on the regression equation represented by the quadratic function, depending on the continuously varying concentration of mercury. An exhaust gas treatment method for bringing the supply amount close to the desired supply amount of activated carbon,
Calculating the average value of the concentration of mercury measured by a mercury meter arranged upstream of a dust collector that removes harmful substances contained in the exhaust gas in the flow direction of the exhaust gas by a moving average,
The calculated average value of the mercury concentration is input to a first non-linear function indicating the correlation between the mercury concentration and the supply amount of activated carbon for determining the supply amount of activated carbon. 1 Calculate the supply amount,
Calculate the rate of change in the concentration of mercury measured by the mercury meter,
Inputting the calculated rate of change in the concentration of mercury into a second non-linear function representing the correlation between the rate of change in the concentration of mercury and the supply amount of activated carbon for determining the temporary supply amount of activated carbon. to calculate the second supply amount of activated carbon,
The exhaust gas treatment method, wherein the calculated second supply amount of activated carbon is added to the calculated first supply amount of activated carbon to determine the total supply amount of activated carbon. 6. The exhaust gas treatment method according to claim 5, wherein said first non-linear function is a function such that said first supply amount of activated carbon is zero when said concentration of mercury is zero. A regression analysis was performed on multiple data points in the coordinate system to determine the non-linear function determined based on the regression equation represented by the quadratic function, depending on the continuously varying concentration of mercury. An exhaust gas treatment method for bringing the supply amount close to the desired supply amount of activated carbon,
Calculating the average value of the concentration of mercury measured by a mercury meter arranged upstream of a dust collector that removes harmful substances contained in the exhaust gas in the flow direction of the exhaust gas by a moving average,
The calculated average value of the mercury concentration is input to a first non-linear function indicating the correlation between the mercury concentration and the supply amount of activated carbon for determining the supply amount of activated carbon. 1 Calculate the supply amount,
A third supply amount of activated carbon is determined based on the correlation between the flow rate of exhaust gas measured by an exhaust gas flow meter arranged downstream of the dust collector in the flow direction of the exhaust gas and the supply amount of activated carbon. ,
The exhaust gas treatment method, wherein the determined third supply amount of activated carbon is added to the calculated first supply amount of activated carbon to determine the total supply amount of activated carbon. calculating the average value of the actual supply amount of activated carbon supplied from the activated carbon supplying device that supplies activated carbon to the exhaust gas introduced into the dust collector by moving average,
The exhaust gas treatment method according to any one of claims 5 to 7, wherein the calculated average value of the supply amount of activated carbon is input to the first nonlinear function to calculate the first supply amount of activated carbon.

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