JP2005270722A - Exhaust gas treatment method and equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment method constituted so as to properly control the supply amounts of a chemical agent and activated carbon at the time of treatment of a plurality of harmful components to reduce a treatment cost, and equipment therefor. <P>SOLUTION: Harmful components in an exhaust gas are HCl, SOx, dioxins and the like, and when a result requiring treatment different from treatment based on the detection of one harmful component is obtained on the basis of the detection of the other harmful component on the way of the supply of a necessary treatment amount of the chemical agent corresponding to the detection result of one component of them, changeover control is performed so as not only to select the kind of the chemical agent corresponding to the treatment of other harmful component but also to supply a necessary treatment amount of the chemical agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas treatment method and its equipment, and more specifically, supplies a predetermined amount of a predetermined drug based on detection results from detection means for detecting a plurality of harmful components present in exhaust gas discharged from an incinerator or the like. The present invention relates to an exhaust gas treatment method and equipment for performing a detoxification process and then performing a dust removal process in the exhaust gas via a dust collecting means.

  When municipal waste and industrial waste are incinerated, harmful gases such as acid gases (HCl, SOx, etc.) are generated. Therefore, in the waste incineration facility, the exhaust gas generated by incineration is subjected to various detoxification treatments. And after being cleaned, it is released into the atmosphere.

  For example, in the dry processing method, chemicals such as slaked lime and baking soda are blown in the midway route where the exhaust gas discharged from the incinerator is introduced into a car-saving machine or temperature reducer and then sent to a dust collector such as a bag filter. Then, the dust is removed by a dust collector, detoxified, and discharged from the chimney to the atmosphere (for example, Patent Document 1).

  In this case, in order to make the chemical treatment amount efficient, the harmful component concentration in the exhaust gas is detected, and an instruction is given to inject a necessary amount of chemical according to the detected component concentration.

Similarly, in order to suppress the generation of dioxins due to incineration to below the regulation value, activated carbon as a chemical agent is cut out and blown in, but since this is highly toxic to the object, a large supply is made. ing.
JP-A-11-300157

  In the above-described conventional technology, only one component concentration of the components to be detected is measured and detected to instruct the amount of medicine to be supplied. Therefore, when other component concentrations become high, appropriate measures cannot be taken, There exists a problem that the density | concentration of the harmful | toxic gas component in the waste gas discharged | emitted increases. Therefore, in order to avoid such a situation, in an ordinary operation, it is generally performed to supply an excessive amount of medicine more than the necessary amount, which increases the amount of medicine consumed and causes an increase in processing cost. . For activated carbon that adsorbs and removes dioxins, a large supply is generally used, and the processing cost is similarly increased. Not only that, the amount of dust processed by the dust collector is increased, resulting in an increase in the number of times of maintenance and increasing the processing cost.

  Therefore, in view of the above-mentioned problems of the prior art, the problem to be solved by the present invention is an exhaust gas that can appropriately control the supply amount of a drug when processing a plurality of harmful components to reduce the processing cost. It is in providing a processing method and its equipment.

  The above object can be achieved by the invention described in the claims. That is, the characteristic configuration of the exhaust gas treatment method according to the present invention is to perform a detoxification process by supplying a predetermined amount of a predetermined drug based on detection results from detection means for detecting a plurality of harmful components present in the exhaust gas. Then, in the method of performing dust removal treatment in the exhaust gas through the dust collecting means, the harmful components are HCl, SOx, dioxins, and the required treatment amount of the medicine is determined according to the detection result of one of the components. In the course of supply, when a result that requires different processing from the processing based on the detection result of the first harmful component is obtained based on the detection result of the other harmful component, the processing of the other harmful component is performed. In addition to selecting a drug type according to the above, the switching control is performed so as to supply the necessary processing amount.

  According to this configuration, since processing is performed according to selection of necessary chemicals and required processing amount in response to changes in a plurality of harmful components present in the exhaust gas, excessive supply of chemicals is surely prevented and processing costs are reduced. In addition, it is possible to prevent the discharge of HCl, SOx, and dioxin in the exhaust gas, the amount of dust treated by the dust collecting means can be reduced, and the number of maintenance can be reduced.

  As a result, it has been possible to provide an exhaust gas treatment method that can appropriately control the supply amount of a medicine when treating a plurality of harmful components and reduce the treatment cost.

  In addition to setting a switching setting value for switching control based on the detection result of the other harmful components, the detection result lower than the setting value is set as a return setting value, and switching control is performed. It is preferable to carry out after a predetermined time delay.

  According to this configuration, the control is facilitated via the preset switching setting value, and when the switching is performed at the time of restoration, the restoration setting value is set low. Therefore, it is possible to reliably prevent the harmful gas exceeding the regulation value from being inadvertently discharged, and to prevent fluctuation due to a sudden change in the control output, thereby ensuring accurate and smooth control.

  Further, the characteristic configuration of the exhaust gas treatment facility according to the present invention includes a detection means for detecting a plurality of harmful components in the exhaust gas, and a predetermined amount of a predetermined agent is supplied based on the detection result from the detection means to render it harmless. A chemical supply means for performing treatment, and a dust collection means for performing dust removal treatment in the exhaust gas subjected to the chemical treatment, wherein the detection means for detecting harmful components is an HCl, SOx, dioxin detection sensor, A process different from the process based on the detection result of the one harmful component based on the detection result of the other harmful component during the process of supplying the necessary processing amount of the medicine according to the detection result of the first component When a result requiring the above is obtained, a drug type corresponding to the processing of the other harmful component is selected, and a control device that performs switching control so as to supply the necessary processing amount is provided.

  According to this configuration, it is possible to provide an exhaust gas treatment facility that can appropriately control the supply amount of a medicine when processing a plurality of harmful components to reduce the processing cost.

  The control device sets a switching setting value for switching control based on the detection result of the other harmful component, and is capable of switching control by setting a detection result lower than the setting value as a return setting value. It is preferable to have a timer function for performing the switching control after a predetermined time delay.

  According to this configuration, it is possible to reliably prevent inadvertent discharge of harmful gas and to perform control with higher accuracy.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a schematic configuration of an exhaust gas treatment apparatus in which the exhaust gas treatment method according to the present embodiment is implemented. The exhaust gas discharged from the incinerator is introduced into the economizer or desuperheater 1 and then sent to the bag filter 2 which is an example of the dust collecting means via the duct 3a. In the middle, chemicals such as slaked lime are blown to neutralize and remove the acid gas components, and dust is removed and cleaned, and again from the chimney 5 to the atmosphere by the induction fan 4 via the duct 3b. Released.

  The medicine is blown into the duct 3a, which is an exhaust gas path upstream of the dust collector 2, through the blowing line 6a by the fan or the blower 8 through the fixed amount feeder 7 so that a predetermined amount is supplied from the medicine storage tank 6. It is. These medicine storage tank 6, fixed quantity feeder 7 and blower 8 constitute a medicine supply means. In addition, as described later, the quantitative feeder 7 is a VVVF whose rotational speed (rpm) is increased based on the rotational speed (rpm) calculated from the relationship between the rotational speed and the drug supply amount (kg / hour). (Variable speed control).

  The medicine is supplied from the control device C based on the detection results from the HCl concentration detection sensor, which is a harmful component detection means, and the SOx concentration detection sensor S2 installed in the duct or chimney after the bag filter 2. Accordingly, the optimum amount is supplied.

  Also, for the treatment of dioxins, a detection sensor S2 is installed on the exit side of the chimney 5, and the detection result is transmitted to the control device C in real time, and the control device C is based on the transmitted detection result. Then, an optimum amount of activated carbon is cut out from a chemical reservoir (not shown) in which activated carbon is stored and fed to the duct 3a. In particular, a denitration device (not shown) is provided before dust is collected and discharged from the chimney, and when denitration is performed, dioxins are also removed to some extent. Therefore, the detection sensor S2 is provided on the exit side of the chimney 5. By installing, supply of excess activated carbon can be avoided. Of course, a dioxin detection sensor, an HCl concentration detection sensor, and a sensor S1 for SOx concentration detection are installed in the duct 3a between the economizer or desuperheater 1 and the chemical blowing line. Control may be performed based on this, or it may be installed in both places to perform control with higher accuracy.

  Hereinafter, with reference to FIGS. 2 and 3, a method of supplying a medicine based on the detection result of each sensor is an example of controlling the amount of slaked lime based on the detection result from the HCl concentration detection sensor and the SOx concentration detection sensor. Based on

  Measurement values (PV) from the HCl concentration detection sensor and the SOx concentration detection sensor S are individually input over time to the control device C that has a PID control mechanism and adopts a distributed control system (DCS). . Setting values (SV) for the HCl concentration and the SOx concentration are input to the control device C in advance, and the timing of drug supply and the amount of drug supply are determined while comparing the set values with the measured values from the sensors. It comes to judge.

  For example, based on the SOx concentration in the exhaust gas detected by the SOx concentration detection sensor, the HCl concentration is determined based on the detection result from the HCl concentration detection sensor while supplying the chemical for reducing the concentration below a certain level. When it is determined that the HCl concentration cannot be reduced below a certain level with the supplied medicine, the medicine is supplied by the switching logic mechanism of the control device C so that the medicine amount corresponding to the detected HCl concentration is supplied. A switching instruction is made to increase the supply amount. The switching instruction from the control device C calculates the rotational speed (rpm) of the quantitative feeder 7 from the relationship between the rotational speed calculated in advance and the supply amount (kg / hour), and based on the calculation result. The rotation speed (rpm) of the metering feeder 7 is increased through the operation device 9 that can be switched to automatic or manual. As a result, a chemical supply amount corresponding to the detected HCl concentration is supplied from the quantitative supply device 7 to the duct 3a.

  When the HCl concentration of the exhaust gas from the temperature reducer 1 becomes a certain value or less, the control is switched by the switching logic mechanism of the control device C so as to decrease the medicine supply amount, so that the optimum medicine supply amount is always secured. It has become. When switching the control, it is preferable to use a bumpless function to avoid a sudden change in control output. Thereby, control accuracy is further improved.

  In the case where it is detected that the SOx concentration is increased during the control of the chemical supply amount corresponding to the HCl concentration of the exhaust gas, the SOx with the increased chemical supply amount is similarly detected by the switching logic mechanism of the control device C. Control is switched to correspond to the density. In this way, by determining the timing and amount of drug supply according to the component that has risen, more than the necessary amount compared to the conventional technology that has determined the drug supply amount based on the detection result of only a specific component In addition to avoiding excessive supply of chemicals, harmful components in the exhaust gas exhausted can be reliably reduced and rendered harmless.

  A control method based on the set value input to the control device C will be specifically described with reference to FIG. FIG. 3 shows an example in which the HCl concentration increases during the PID control of the SOx concentration. When the HCl concentration exceeds the set value during the PID control and rises above the switching set value, After a predetermined time (usually about 5 minutes) has elapsed since the timer was activated, control on the HCl concentration is started based on the switching logic mechanism. Thereafter, the HCl concentration in the exhaust gas decreases to an HCl recovery set value set lower than the switching set value, and the timer operates for a predetermined time (usually about 5 minutes) to return to the PID control of the SOx concentration. The operation is repeated in this way to appropriately control the timing and amount of medicine supply. However, if both the HCl concentration and the SOx concentration are less than the set values, the medicine supply is stopped.

  The above switching is preferably performed automatically, but can also be performed manually based on the detection results from each sensor. By operating the timer in this way, it is possible to avoid a sudden change in control output and enable smooth, stable and accurate control.

  In this way, harmful components (HCl, SOx) in the exhaust gas can be removed with an optimal amount of chemical (slaked lime) supply, and dioxins similar to those shown in FIGS. By doing so, it is possible to calculate the optimum amount of activated carbon supply and to keep dioxins in the exhaust gas below the regulation value at all times.

  As the HCl concentration, SOx concentration, and dioxin detection sensor, for example, those manufactured by Tokyo Electronics Co., Ltd., Kyoto Electronics Industry Co., Ltd., etc. can be used.

The example at the time of implementing the exhaust-gas-treatment method shown in the said embodiment using the processing equipment shown in FIG. 1 is shown below with the comparative example which did not implement the said processing method.
(Example 1)
The exhaust gas temperature discharged from the waste incinerator is 180 to 220 ° C., and the HCl concentration and SOx concentration in the exhaust gas before treatment are 700 ppm by weight and 100 ppm by weight, respectively, and the dioxin on the smoke protruding side before treatment The concentration of the slaked lime was 0.005 ng / Nm ³ , and slaked lime was fed to reduce the SOx concentration to 30 ppm by weight or less. The feed rate was increased and the HCl concentration was controlled as shown in FIG. Furthermore, since dioxins exceeded 0.01 ng / Nm ³ after 3 hours, activated carbon was fed. Table 1 shows the supply amount of slaked lime and the supply amount of activated carbon during the above operation.
(Example 2)
Slaked lime is fed to reduce the HCl concentration to 50 ppm by weight or less, and after 3 hours, the SOx concentration is increased to increase the SOx concentration to 30 ppm by weight or less in response to the increase in the SOx concentration. The process was performed in the same manner as in Example 1 except that the control was performed as described above. Table 1 shows the supply amount of slaked lime and the supply amount of activated carbon at that time.
(Comparative Example 1)
The slaked lime was fed to the exhaust gas similar to that in Example 1 so that the HCl concentration was 50 ppm by weight or less based only on the detection result by the HCl concentration detection sensor without performing the above control. For dioxins, activated carbon was fed at 40 kg / hour from the beginning.
(Comparative Example 2)
The slaked lime was fed to the exhaust gas similar to that in Example 1 so that the SOx concentration was 30 ppm by weight or less based on only the detection result by the SOx concentration detection sensor without performing the above control. For dioxins, activated carbon was fed at 40 kg / hour from the beginning.

  Table 1 shows the measurement results of each component concentration when exhaust gas was discharged from the slaked lime, activated carbon consumption, and chimney of each of the above Examples and Comparative Examples.

表１に示すように、実施例１、２共、比較例に比べて消石灰消費量を２０〜３０％程度少なくできることが分かる。
〔別実施の形態〕
（１）本発明に実施可能な薬剤として、重曹、炭酸ナトリウム、セキス炭酸ナトリウム、天然ソーダ等あるいはこれらの複合剤を使用することができる。
（２）集塵手段としては、パルスジェット式あるいは逆洗式などのバグフィルター装置、電気集塵機などを使用することができる。

As shown in Table 1, it can be seen that the consumption of slaked lime can be reduced by about 20 to 30% in both Examples 1 and 2 compared to the comparative example.
[Another embodiment]
(1) As a chemical | medical agent which can be implemented to this invention, sodium bicarbonate, sodium carbonate, sex sodium carbonate, natural soda, etc., or these composite agents can be used.
(2) As the dust collecting means, a pulse jet type or backwash type bag filter device, an electric dust collector, or the like can be used.

Schematic overall configuration diagram of an exhaust gas treatment apparatus in which the exhaust gas treatment method according to the present invention is implemented The figure explaining the effect | action of a HCl concentration detection sensor, a SOx concentration detection sensor, and a control apparatus. Graph explaining one example of control status over time

Explanation of symbols

2 Dust collection means 6, 7, 8 Drug supply means C Controllers S1, S2 Toxic component detection means

Claims (4)

Based on the detection results from the detection means for detecting a plurality of harmful components present in the exhaust gas, a predetermined amount of a predetermined agent is supplied to perform the detoxification process, and then the dust removal process is performed through the dust collection means. In the exhaust gas treatment method to be performed, the harmful components are HCl, SOx, dioxins, and in the middle of supplying the necessary treatment amount of the chemical according to the detection result of one of the components, Based on the detection result, when a result that requires a different process from the process based on the detection result of the one harmful component is obtained, a drug type corresponding to the treatment of the other harmful component is selected and the necessity An exhaust gas treatment method characterized by performing switching control so as to supply a treatment amount. In addition to setting a switching setting value for switching control based on the detection result of the other harmful components, the detection result lower than the setting value is set as a return setting value, and switching control is performed. The exhaust gas treatment method according to claim 1, wherein the exhaust gas treatment method is performed after being delayed by a predetermined time. A detection means for detecting a plurality of harmful components in the exhaust gas, a chemical supply means for supplying a predetermined amount of a predetermined medicine based on the detection result from the detection means, and a detoxification process, and an exhaust gas subjected to the chemical treatment In the exhaust gas treatment facility equipped with dust collection means for performing dust removal treatment, the detection means for detecting harmful components is an HCl, SOx, dioxin detection sensor, and according to the detection result of one of the components In the process of supplying the necessary processing amount of the medicine, when a result that requires a different process from the process based on the detection result of the first harmful component is obtained based on the detection result of the other harmful component An exhaust gas treatment facility comprising a control device that selects a drug type according to the treatment of the other harmful components and performs switching control so as to supply the necessary treatment amount. The control device sets a switching setting value for switching control based on the detection result of the other harmful component, and is capable of switching control by setting a detection result lower than the setting value as a return setting value. The exhaust gas treatment facility according to claim 3, further comprising a timer function for performing the switching control after a predetermined time delay.

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