JP2003210934A - Equipment for exhaust-gas treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide equipment which can restrain discharge of SO<SB>2</SB>. <P>SOLUTION: Concentrations of SO<SB>2</SB>and HCl are measured respectively by an SO<SB>2</SB>-measuring instrument (11) and an HCl-measuring instrument (12) in the downstream of a bag filter (10). If the measured value is found to be higher than a predetermined value in either side of the instruments, the amount of chemical-supply is increased by controlling powder-supply equipment (8) of a chemical-storage tank (7). If the concentrations of both of SO<SB>2</SB>and HCl are found to be lower than the predetermined value, the amount of chemical-supply is reduced. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment device, and more particularly to an exhaust gas treatment device for introducing chemicals to reduce the concentration of specific components of exhaust gas.

[0002]

2. Description of the Related Art As an exhaust gas treating apparatus for treating exhaust gas generated from a refuse incinerator or the like, a bag filter is disposed in the middle of an exhaust gas flow path, and a chemical, particularly slaked lime, is charged on the upstream side of the bag filter to supply a gas of a specific component, Some suppress the emission of HCl and SO ₂ . Here, conventionally, HCl is used rather than SO _2.
More was discharged, so H in the downstream of the bag filter
The Cl concentration was detected, and the chemical supply amount was controlled based on the HCl concentration.

However, in recent years, the quality of the discharged dust has changed, and due to an increase in the number of waste tires, for example, SO ₂ is more often discharged than HCl. In this situation, HC
By controlling the supply amount of the drug based on the concentration of l SO ₂
The emission concentration of does not decrease. If the emission concentration of SO ₂ is high, the catalyst of the denitration equipment on the downstream side of the dust collector may be damaged.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an exhaust gas treatment device which does not emit SO ₂ at a high concentration.

[0005]

According to the invention of claim 1, there is provided a bag filter for allowing the exhaust gas to pass therethrough, one chemical is supplied to the upstream side of the bag filter, and the SO in the exhaust gas is supplied by the one chemical. _An exhaust gas treatment device for reducing the concentrations of ₂ and HCl, characterized in that the SO ₂ concentration in the exhaust gas is measured on the downstream side of the bag filter, and the chemical supply amount is increased or decreased based on the measured SO ₂ concentration. An exhaust gas treatment device is provided. In the thus constructed exhaust gas treatment apparatus to measure the SO ₂ concentration in the exhaust gas, since increasing or decreasing the supply amount of chemicals in accordance with the SO ₂ concentration measured SO ₂
High concentrations will not be emitted.

According to the invention of claim 2, in the invention of claim 1, the H in the exhaust gas is further provided downstream of the bag filter.
Provided is an exhaust gas treatment device which measures a Cl concentration and increases the supply amount of a chemical when either one of the measured SO ₂ concentration and the measured HCl concentration exceeds a predetermined value. In the exhaust gas treatment device configured as described above, the SO
Not only the concentration of ₂ but also the concentration of HCl is measured, and if either of them exceeds the predetermined value, the supply amount of the chemical is increased.
When SO ₂ exceeds a predetermined value, when HCl exceeds a predetermined value, and when both SO ₂ and HCl both exceed a predetermined value, the chemical supply amount is increased, and SO ₂ and HCl are both high. It is not emitted in concentration.

According to the invention of claim 3, in the invention of claim 2, the supply amount of the chemical is reduced when both of the measured SO ₂ concentration and HCl concentration fall below the predetermined value. An exhaust gas treatment device is provided. In the exhaust gas treating apparatus configured as above, the SO ₂ concentration and the HCl
If either one of the concentrations exceeds the prescribed value, the supply amount of the drug is not reduced, and if both of them fall below the prescribed value, the supply amount of the drug is reduced, resulting in excessive reduction of the drug. To be prevented.

According to the invention of claim 4, in the invention of claim 2 or 3, the increase / decrease in the amount of supply of the medicine is measured S
O ₂ is the concentration and HCl concentration as performed in proportion to the deviation between the predetermined value, the measured concentration exceeds a large predetermined value, or when it falls below the chemicals large increase, or is reduced, A little over the specified value,
Alternatively, if it is not lower, the amount of the drug is slightly increased or decreased.

According to the invention of claim 5, in the invention of claim 4, when the amount of the chemical is increased, the concentration of SO ₂ and HCl are increased.
It is performed in proportion to the larger of the deviations of the concentration from the predetermined value, and when reducing the chemicals, it is performed in proportion to the smaller of the deviations of the SO ₂ concentration and the HCl concentration from the predetermined value. , SO ₂ concentration and HCl concentration are prevented from being discharged at a high concentration, and hunting due to a sudden decrease in the amount of chemicals is also prevented.

According to the invention of claim 6, claims 1 to 5
The concentration of SO _{2 and the} concentration of HCl used for increasing or decreasing the amount of chemicals in the exhaust gas treatment device described in (3) are instantaneous values, and changes can be promptly dealt with.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a hardware configuration common to each embodiment will be described. FIG. 1 is a diagram schematically showing a configuration of an exhaust gas treating apparatus according to the present invention. Exhaust gas discharged from an incinerator (not shown) is first introduced into a temperature reducing tower 1 and its temperature is lowered. The exhaust gas whose temperature has been lowered in the temperature reducing tower 1 is guided to the bag filter chamber 2 via the first duct 21 and passed through the bag filter 10 arranged in the bag filter chamber 2.

The exhaust gas passing through the bag filter 10 in the bag filter chamber 2 is introduced into the gas reheater 3 by the second duct 22.
To the denitration reaction tower 4 after being reheated by the gas reheater 3 and denitration in the denitration reaction tower 4, and then guided to the chimney 6 by the induction fan 5 and discharged from the upper end of the chimney 6. It Then, in the middle of the first duct 21, the chemical storage tank 7
The alkaline agent, specifically slaked lime, is supplied by the powder supply device 9 with its supply amount adjusted, and is supplied by the chemical supply blower 8 through the chemical supply pipe 24.

On the other hand, exhaust gas is collected in the middle of the second duct 22.
The exhaust pipe 23 is attached and the exhaust gas sampling pipe 23 collects
Part of the exhaust gas is SO_TwoMeasuring device 11 and HCl measuring device
And the SO in the exhaust gas_TwoDark
And the HCl concentration is measured. SO_TwoMeasuring device 11 and H
The measurement result with the Cl measuring device 12 is sent to the control circuit 13.
It The control circuit 13 is SO_TwoMeasuring device 11 and HCl measuring device
SO measured by device 12 _TwoBased on the concentration and HCl concentration,
By the chemical supply pipe 24 attached to the chemical storage tank 7.
The powder supply device determines the supply amount of chemicals (slaked lime, etc.) to be conveyed.
Controlled by 9.

Each of the embodiments having the above-described hardware configuration will be described below. First, the conventional method will be described. The conventional method is shown in FIG.
The concentration of HCl is measured, the average value Hm of the measured value H for a certain period of time is calculated, and if the value does not exceed the set value Ht, the supply amount M of slaked lime is not increased. Therefore, although it is not actually measured, even if the similar average value Sm of SO ₂ exceeds the set value St, the slaked lime supply amount M is not increased and is made constant.
_This means that the increase of ₂ cannot be suppressed.

Therefore, in the first embodiment of the present invention shown in FIG. 3, the concentration of SO ₂ is measured in addition to the concentration of HCl, and the average value Hm of the measured values H is set to the set value for HCl. Even if it does not exceed Ht, when the average value Sm of the measured values S of SO ₂ becomes larger than the set value St, the slaked lime supply amount M is increased by a predetermined amount ΔM. By doing so, SO ₂ Can be suppressed. When the value becomes smaller than the set value St, the amount is decreased by ΔM. The increase and decrease of the slaked lime supply amount M is shown in FIG.
Chemical supply pipe 24 attached to the chemical storage tank 7 in
The amount of chemicals (slaked lime, etc.) to be conveyed is controlled by the powder supply device 9.

Although not shown, conversely, slaked lime is also used when the average value Hm of the measured values H of HCl exceeds the set value Ht and the average value Sm of the measured values S of SO ₂ does not exceed the set value St. The supply M is increased.

[0017] that 4, a flowchart of a control of the first embodiment, SO ₂ at Step 41
Alternatively, it is determined whether or not the average value of the concentration of HCl exceeds the set value, and when the determination is affirmative, the routine proceeds to step 42, where the slaked lime supply amount M is increased by ΔM, and then the routine proceeds to step 45 and returns.

On the other hand, if the determination is negative, step 4
In 3, it is determined whether or not the average value of the concentrations of SO ₂ and HCl is below the set value, and if a positive determination is made, step 4
4, the slaked lime supply amount M is reduced by ΔM, and then the routine proceeds to step 45 and returns. If a negative determination is made, it means that the average value of the concentrations is equal to the set value. Proceed to and return.

Next, a second embodiment will be described. In the above-described first embodiment, the average value of the concentration of SO ₂ or HCl measured as in the prior art is obtained, and when the average value exceeds the set value, the amount of slaked lime is increased. Therefore, there is a problem that if the set value is momentarily exceeded, it cannot be dealt with, and that the response is slow. Therefore, in the second embodiment, not the average value but the instantaneous value is compared with the set value.

FIG. 5 is a diagram for explaining the control of the second embodiment. Referring to FIG. 5, the instantaneous values Si and Hi of the concentrations of SO ₂ and HCl exceed the set values St and Ht, respectively, for a certain time, but the instantaneous values Si of the concentration of SO ₂ exceed the set value St. Since the time is earlier than the time when the instantaneous value Hi of the HCl concentration exceeds the set value Ht,
When the instantaneous value Si of the concentration of SO ₂ exceeds the set value St, the amount of slaked lime is increased.

On the other hand, since the moment when the instantaneous value Hi of the concentration of HCl falls below the set value Ht is later than the moment when the instantaneous value Si of the concentration of SO ₂ falls below the set value St, the instantaneous value Hi of the concentration of HCl becomes high. When the value falls below the set value Ht, the amount of slaked lime is reduced.

FIG. 6 is a flowchart of the control of the second embodiment. In contrast to the flowchart of the first embodiment shown in FIG. 4, Sm is Si and Hm is Hi.
In step 61, it is determined whether or not the instantaneous value Si or Hi of the concentration of SO ₂ or HCl exceeds the set value St or Ht, and if the determination is affirmative, step 6
The routine proceeds to step 2, where the slaked lime supply amount M is increased by ΔM, and then the routine proceeds to step 65 and returns.

On the other hand, if a negative decision is made, step 6
Instantaneous values of SO ₂ and HCl concentrations at 3 and Si
Is below the set values St and Ht, and when a positive determination is made, the routine proceeds to step 64, where the slaked lime supply amount M is reduced by ΔM, and then the routine proceeds to step 65 and returns, and when a negative determination is made. Since this is the case where the average value of the densities matches the set value, the process proceeds to step 65 without doing anything and returns.

Next, a third embodiment will be described. This is because in the first and second embodiments, the slaked lime supply amount M is increased / decreased by a constant amount ΔM as in the conventional technique, and therefore, it is possible to cope with a sudden change in SO ₂ or HCl. Since it is delayed, the slaked lime supply amount is changed according to the deviation from the set value.

FIG. 7 is a diagram for explaining the control of the third embodiment, in which the deviation Si-St is calculated when SO ₂ exceeds a set value, and a coefficient k1 predetermined for this deviation is calculated. Multiply by and increase the amount of M. That is, M = M + k
1 × (Si-St). If HCl exceeds the set value and the deviation Hi-Ht is larger than DVS, M =
Let M + k1 × (Hi−Ht). Thus, when determining the amount of increase, the one with the larger deviation is used.

On the other hand, when reducing the amount of slaked lime, in this case, the deviation Hi- when the value is below the set value Ht of HCl.
Ht (negative value) multiplied by a predetermined coefficient k2, that is, k2 × (Hi-Ht) is used as the decrement of M, and M = M
+ K2 × (Hi-Ht). If SO2 is below the set value, the deviation Si-St (negative value) is the above D
If larger than VH (small absolute value), M = M +
Let k2 × (Si-St). Thus, when determining the amount of weight reduction, the one with the smaller deviation is used.

FIG. 8 is a control flowchart of the third embodiment. In step 81, as in step 61 of the flow chart of FIG. 6 described with reference to the second embodiment, SO ₂ or HCl Instantaneous concentration Si
Alternatively, it is determined whether or not Hi exceeds the set value St or Ht, and if a positive determination is made, the process proceeds to step 82.

In step 82, the deviation Si-St with respect to the set value of SO _{2 is} the deviation Hi- with respect to the set value of HCl.
It is determined whether or not it is larger than Ht. If an affirmative decision is made in step 82, the routine proceeds to step 83, where k1 × (S
After increasing the slaked lime supply amount M by i-St), the routine proceeds to step 89 and returns. When a negative determination is made in step 82, the process proceeds to step 84 and k1 × (Hi-H
After the slaked lime supply amount M is increased by t), the process proceeds to step 89 and returns. The deviation Si-St and the deviation Hi-
When the Ht is the same, whether to make an affirmative judgment or a negative judgment is determined in advance and the flow is followed. In this case, an affirmative decision is made.

On the other hand, if a negative decision is made at step 81, then the processing advances to step 85, at which it is decided whether or not the instantaneous values Si and Hi of the concentrations of SO ₂ and HCl have fallen below the set values St and Ht. When an affirmative decision is made in step 85, the routine proceeds to step 86, where it is determined whether the deviation Si-St (negative value) with respect to the set value of SO ₂ is larger than the deviation Hi-Ht (negative value) with respect to the set value of HCl. To determine.

If an affirmative decision is made in step 86, H
CL means that the deviation from the set value is small and the discharge amount decreases slowly. Therefore, after increasing the slaked lime supply amount M by k2 × (Si-St), the routine proceeds to step 89 and returns. If a negative determination is made in step 86, it means that SO ₂ has a smaller deviation from the set value and the decrease in the discharge amount is slower. Therefore, the slaked lime supply amount M is increased by k2 × (Hi-Ht). To step 89, the process returns.
When the deviation Si-St is equal to the deviation Hi-Ht, whether to make an affirmative judgment or a negative judgment is determined in advance and the flow is followed in the same manner as described above. In this case, an affirmative decision is made.

[0031]

According to the exhaust gas treatment apparatus described in each claim, since the chemical is supplied based on the concentration of SO ₂ , SO ₂
Even if exhaust gas treatment is performed in a current garbage incinerator, which is prone to generate SO ₂ , SO ₂ is not emitted in high concentration, and damage to the denitration device can be prevented. In particular, according to the second aspect, since the chemical is supplied even when the concentration of HCl is high, HCl is not discharged at a high concentration. Further, by supplying the chemicals based on the instantaneous value of the gas concentration as in the sixth aspect, it is possible to quickly respond to the change in the concentrations of SO ₂ and HCl, and it is possible to obtain better purification performance.

[Brief description of drawings]

FIG. 1 is a diagram showing a hardware configuration of the present invention.

FIG. 2 is a diagram illustrating control of a conventional technique.

FIG. 3 is a diagram illustrating control according to the first embodiment.

FIG. 4 is a flowchart of control according to the first embodiment.

FIG. 5 is a diagram illustrating control according to the second embodiment.

FIG. 6 is a flowchart of control according to the second embodiment.

FIG. 7 is a diagram illustrating control according to the third embodiment.

FIG. 8 is a flowchart of control according to the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Dehumidification tower 2 ... Bag filter chamber 3 ... Gas reheater 4 ... Denitration reaction tower 5 ... Induction fan 6 ... Chimney 7 ... Chemical storage tank 8 ... Chemical supply blower 9 ... Powder supply device 10 ... Bag filter 11 ... SO ₂ measuring device 12 ... HCl measuring device 13 ... control circuit

Continued front page    (72) Inventor Koji Namezawa             12 Nishiki-cho, Naka-ku, Yokohama-shi, Kanagawa Mitsubishi Heavy Industries             Yokohama Co., Ltd. (72) Inventor Shuzo Miura             12 Nishiki-cho, Naka-ku, Yokohama-shi, Kanagawa Mitsubishi Heavy Industries             Yokohama Co., Ltd. F-term (reference) 4D002 AA02 AA19 AC04 BA03 BA14                       CA11 DA05 DA12 GA02 GA03                       GB02 GB06 HA01

Claims (6)

[Claims] 1. An exhaust gas treating apparatus having a bag filter for passing exhaust gas, supplying one chemical to the upstream side of the bag filter, and reducing the concentration of SO ₂ and HCl in the exhaust gas by the one chemical. Then, measure the SO ₂ concentration in the exhaust gas on the downstream side of the bag filter,
An exhaust gas treatment device, wherein the supply amount of a chemical is increased or decreased based on the measured SO ₂ concentration. 2. Further, the HCl concentration in the exhaust gas is measured downstream of the bag filter, and the measured SO ₂ concentration and HCl are measured.
If either of the concentrations exceeds the specified value,
The exhaust gas treatment device according to claim 1, wherein the supply amount of the chemical is increased. 3. The measured SO ₂ concentration and HCl concentration,
The exhaust gas treatment device according to claim 2, wherein both of them reduce the supply amount of the chemical when the amount of chemicals falls below the predetermined value. 4. The increase / decrease in the amount of supplied chemicals is measured by measuring SO ₂
The exhaust gas treatment apparatus according to claim 2 or 3, wherein the exhaust gas treatment apparatus is performed in proportion to a deviation between the concentration and the HCl concentration and the predetermined value. 5. The increase is performed in proportion to the larger one of the deviations of the SO ₂ concentration and the HCl concentration from the predetermined value, and the decrease is performed within the deviation of the SO ₂ concentration and the HCl concentration from the predetermined value. The exhaust gas treatment device according to claim 4, wherein the exhaust gas treatment device is performed in proportion to the smaller one. 6. SO ₂ concentration and HC used for increasing and decreasing chemicals
6. The l-concentration is an instantaneous value.
The exhaust gas treatment device according to item 1.