JP2000317264A - Method for removing harmful component in waste gas and device for treating waste gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control the discharge concn. of the harmful component contained in waste gas to a specific value or below by spraying the required minimum quantity of chemicals such as neutralizing agent. SOLUTION: At the time of removing the harmful component incorporated in the waste gas by spraying the chemicals to the waste gas discharged from a waste incinerating furnace 1, the harmful component quantity of the subject to be treated is estimated by using one or more values among the waste gas flow rate after dust collecting treatment, the waste gas temp. at the upstream than a waste gas cooling means by water spraying, the steam generating quantity by a steam type heat recovering means, the air quantity for combustion to a waste incinerator, the secondary air quantity to the waste incinerator, the low level heat generation of the matter to be incinerated, the CO2 concn. in the waste gas after dust collecting treatment and the O2 concn. in the waste gas after dust collecting treatment without always detecting the acidic component concn. in untreated waste gas without always detecting the harmful component concn., and the spraying quantity of the chemicals is controlled on the basis of the harmful component quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detoxifying exhaust gas containing harmful substances discharged from municipal solid waste incineration facilities, flammable waste treatment facilities, and the like. The present invention relates to a harmful component removal method and an exhaust gas treatment device for controlling an amount of sprayed chemicals when removing harmful substances contained in a waste gas.

[0002]

2. Description of the Related Art Exhaust gas emitted during the process of incineration of municipal solid waste and industrial waste and the preheating and melting of scrap containing combustible deposits at metal smelting plants and the like includes dust, HCl and SOx. It contains various harmful substances such as acidic components such as nitrogen oxides, heavy metals such as mercury, dioxins and their precursors. Among these harmful substances, acidic components such as HCl and SOx are widely used as dry methods in which powdered slaked lime, which is a neutralizing agent, is blown into exhaust gas and neutralized in a reactor or bag filter to remove it from exhaust gas. Used. NOx, which is a nitrogen oxide, is sprayed with ammonia or urea water into the incinerator or the outlet of the incinerator to form N2.
A non-catalytic denitration method for selectively removing Ox is widely used. Further, as necessary, a catalytic denitration method is used in which nitrogen oxides are removed by spraying ammonia with a denitration tower using a denitration catalyst. Also, mercury and dioxins are
An activated carbon blowing method is used in which powdered activated carbon is blown into exhaust gas and is adsorbed and removed by a reactor or a bag filter.

[0003] In general, chemicals such as slaked lime, NH ₃ (or urea aqueous solution), and activated carbon for removing these harmful substances are controlled in the spray amount as follows. In other words, when removing acidic components and nitrogen oxides in the exhaust gas, a method of spraying a certain amount of slaked lime or NH ₃ (or urea water) or the concentration of the acidic components or the nitrogen oxides in the exhaust gas after the treatment is used. Based on the above, a method of performing feedback control of the slaked lime spray amount and the NH ₃ (or urea water) spray amount is adopted. Also, when removing mercury and dioxins in exhaust gas, a certain amount of activated carbon is sprayed, or a spray amount control corresponding to the CO concentration is adopted by detecting the CO concentration called an indicator substance of dioxin. You.

Here, as a conventional example in the case of performing the slaked lime spray amount and the like by feedback control, an outline of a control system thereof will be described with reference to FIG. FIG. 11 is a diagram schematically showing a conventional exhaust gas treatment control method. In FIG. 11, 1
01 is a waste incinerator, 102 is a boiler, 103 is a cooling tower, 104 is a bag filter, 105 is a denitration tower, 106 is a chimney, 117 is a feedback calculator, 118 is a slaked lime spray amount control device, and 119 is ammonia gas spray. Quantity control device (for denitration tower), 120 is activated carbon spray quantity control device, 12
8 is an HCl concentration detector, 129 is a NOx concentration detector, 1
Reference numeral 30 denotes a CO concentration detector.

An exhaust gas containing an acidic component such as HCl, a nitrogen oxide such as NOx, and an organic halogen compound such as dioxin is discharged from an incinerator 101, passed through a boiler 102, and further introduced into a water spray type cooling tower 103. After the exhaust gas temperature becomes suitable for exhaust gas treatment, slaked lime is sprayed from the slaked lime spray amount control device 118 before being introduced into the bag filter 104, and acidic components such as HCl are removed in the bag filter 104. Here, the amount of slaked lime sprayed by the slaked lime spray amount controller 118 is obtained by feeding the concentration signal from the HCl concentration detector 128 installed at the chimney inlet to the feedback calculator 1.
17 and is determined by updating the shortage or excess of the slaked lime spray amount at regular time intervals using a PID control method or the like so that the HCl concentration becomes a predetermined HCl concentration. That is, the slaked lime spray amount is controlled by feedback control based on the HCl concentration after the treatment.

Similarly, in the denitration by ammonia, ammonia is sprayed by the ammonia spray amount control device 119, and the ammonia spray amount is feedback-controlled based on the NOx concentration of the NOx concentration detector 129 installed at the chimney inlet.

In the case of the activated carbon spray amount control device 120 for removing dioxin, a fixed amount of activated carbon is sprayed, or the CO concentration of the CO concentration detector 130 installed at the chimney inlet is controlled.
Activated carbon spray corresponding to the concentration is performed. However, since it is usually impossible to keep the CO concentration constant by spraying activated carbon, it is different from feedback control exactly,
In FIG. 1, feedback control is described for convenience.

[0008]

However, the amount of slaked lime spray is controlled by detecting the concentration of HCl after the treatment.
Has the following problems. In other words, the point at which the acidic component such as HCl is measured is sampled downstream of the exhaust gas treatment facility, not at the upstream of the exhaust gas such as the incinerator outlet where the acidic component is generated. The acidic components in the exhaust gas, such as HCl, are usually absorbed by a sample exhaust gas into an absorbing solution such as an ion electrode system, and the concentration in this solution is measured to convert it into a concentration in the exhaust gas. In this method, the response time is generally long, and the measured value is indicated with a delay of, for example, 10 minutes, despite the temporary generation of a large amount of HCl. Is often displayed, so that a longer time delay occurs. From this, if the concentration of the acidic component after the treatment is measured and then the amount of slaked lime as a neutralizing agent is controlled, a time delay occurs, so that the required amount of slaked lime cannot be sprayed correctly, resulting in waste. Slaked lime is consumed, and the concentration of HCl after the treatment shows a large pulsation behavior, which causes a problem that it is difficult to control the concentration to a constant value or a constant value or less.

As another method different from that shown in FIG. 11, for example, the concentration of an acidic component in exhaust gas before treatment, such as a boiler outlet, is measured in advance, and the spray amount of a neutralizing agent such as slaked lime is measured with respect to the generated amount. However, in this case as well, for the above reasons, there is a problem that a time delay occurs due to a slow response time of the continuous analyzer, and a long-term continuation of exhaust gas before treatment having a high dust content. Even if a problem arises in which sampling is difficult due to clogging of the sampling probe, or if a continuous analyzer with a backwash function that can avoid clogging of the sampling probe is used, the response time of the continuous The problem of time delays due to slowness,
The continuous analyzer with the backwash function is expensive, and even with the backwash function, regular maintenance is indispensable and extra labor is required.

[0010] Next, although the description is omitted, the N
The case where the amount of ammonia spray is controlled by detecting the concentration of Ox and the case where the amount of activated carbon spray is controlled by detecting the concentration of CO, which is an indicator of dioxin, have almost the same problems as those described above. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the discharge concentration of harmful components can be reduced to a certain value or less than a certain value by spraying a necessary minimum amount of a chemical such as a neutralizing agent. It is an object of the present invention to provide a method and an apparatus for removing harmful components in exhaust gas which can be controlled stably.

[0012]

The invention according to claim 1 is
In the method of removing harmful components contained in the exhaust gas by spraying the agent on the exhaust gas discharged from the waste incinerator, without spraying the agent on the exhaust gas, without constantly detecting the concentration of the harmful component in the exhaust gas, A) the exhaust gas flow rate after dust collection, b) the exhaust gas temperature upstream of the exhaust gas cooling means by water spray, c) the amount of steam generated by the steam-type heat recovery means, d) the amount of combustion air to the waste incinerator, and e) ) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, Ji) O ₂ concentration in the exhaust gas after dust collection, A method of removing harmful components in exhaust gas, characterized by estimating the amount of harmful components to be treated using at least one of the above, and controlling the spray amount of the chemical based on the estimated amount.

The concentration (or amount) of harmful components in exhaust gas, such as acidic components such as HCl, nitrogen oxides such as NOx, and organic halogen compounds such as dioxin, depends on the operating conditions of the incinerator and the diversified properties of the incinerated material. For this reason, it hardly takes a constant value, and generally involves a large fluctuation. In such a case, if the concentration of the harmful component having a large concentration change before the chemical treatment is constantly detected and the amount of the harmful component is sprayed, the harmful component can be efficiently removed. Cannot be adopted because it has. That is, to detect harmful components before treatment, it is necessary to measure the concentration of harmful components in the exhaust gas containing dust with a continuous measuring instrument,
The problem is that the sampling probe of the measuring instrument is frequently clogged and cannot be measured due to dust-containing exhaust gas, and the response time of the measuring instrument is delayed, for example, an ion electrode type continuous measuring instrument for measuring HCl. However, there is a problem that it is difficult to quickly cope with a harmful component concentration which fluctuates rapidly with a time delay of about 10 minutes. Therefore, in the present invention, the concentration of the harmful component in the untreated exhaust gas is not always detected, and instead of this, the above a) to
H), the amount of the harmful component to be treated is estimated using at least one of them.

Here, each of the above (a) to (h) used in the present invention will be described. B) The flow rate of the exhaust gas after the dust collection process may be the flow rate of the exhaust gas after the denitration tower 5 in the subsequent stage, for example, if the flow rate of the exhaust gas after the dust collection by the bag filter 4 in FIG. Uses the exhaust gas flow value continuously measured by the exhaust gas flow detector 11 after the denitration tower 5 as a control factor. Although the exhaust gas flow rate is often converted to normal by an exhaust gas thermometer (not shown), either the normal converted exhaust gas flow rate or not may be adopted. This is because the temperature of the exhaust gas that normally exits the dust collector is substantially constant, and the tendency of the exhaust gas flow rate is similar whether or not the value of the exhaust gas flow rate is converted by the temperature. The exhaust gas flow rate tends to increase when the amount of incineration in the incinerator or the calorific value of the incinerated material is large. That is,
The exhaust gas flow rate is one index indicating the incineration state.

(B) The exhaust gas temperature upstream of the exhaust gas cooling means by water spray is generated in the incinerator, for example, the temperature in the incinerator, the incinerator outlet temperature, the boiler 1 pass temperature, the boiler 2 pass temperature, the boiler outlet temperature, and the like. The temperature of the exhaust gas to be discharged may be any temperature before the exhaust gas is cooled by the water spray from a cooling tower or the like. Since the temperature is appropriately adjusted to a temperature suitable for a dust collector or the like at the subsequent stage by cooling by water spray, the temperature does not reach the temperature indicating the incineration state of the furnace after water spray cooling. The graph shown in FIG. 5 shows that the furnace temperature A, the furnace outlet temperature B, and the boiler two-pass temperature C have different average values, but the fluctuations are very similar, indicating that there is a good correlation. That is, these temperatures are one index indicating the incineration state.

(C) The amount of steam generated by the steam-type heat recovery means is the amount of high-pressure steam generated in the boiler (evaporation amount). When the incineration temperature is high, the amount of steam generated tends to increase. The graph shown in FIG. 5 shows that the furnace temperature A and the like and the evaporation amount D have a good correlation. That is, the amount of generated steam is one index indicating the incineration state.

D) The amount of combustion air to the waste incinerator is
For example, it refers to the amount of air introduced as combustion air into the furnace from a combustion air inlet (not shown) provided at the lower part of the incinerator. When the amount of incineration in the incinerator or the amount of heat generated by the incineration is large, the amount of combustion air tends to increase. That is, the combustion air amount is one index indicating the incineration state.

E) The amount of secondary air to the waste incinerator is determined, for example, by a secondary air inlet (not shown) installed near or inside the outlet of the incinerator, and the secondary air is supplied to the inside or the outlet of the incinerator. The amount of air introduced as combustion air. While the secondary air promotes secondary combustion, it may also serve to cool the furnace temperature which has become too high in some cases. In any case, the amount of secondary air tends to increase when the amount of incineration in the incinerator or the amount of heat generated by the incinerator is large. That is, the secondary air amount is one index indicating the incineration state.

F) The lower calorific value of the incinerated material is a calorific value obtained as a heat source when the incinerated material is burned, which is preliminarily calculated from, for example, the furnace temperature and the amount of waste input. is there. When the lower heating value is managed centrally in a continuous incinerator or the like, it is recorded as operating data. If the lower heating value of the incinerated material is large, the furnace temperature tends to increase. That is, the lower heating value is one index indicating the incineration state.

G) CO in exhaust gas after dust collection_TwoConcentration and
Is, for example, the dust collected by the bag filter 4 in FIG.
CO in gas_TwoIf the concentration is higher than that of the subsequent denitration tower 5
CO in exhaust gas_TwoConcentration may be a continuous measuring instrument
CO measured by_TwoIt means concentration. In the incinerator
If the combustion in the furnace is active, the furnace temperature rises
O contained in combustion air_TwoLarge consumption of CO_TwoMany
appear. That is, CO _TwoConcentration is one finger indicating incineration status
It is a mark.

H) The O ₂ concentration in the exhaust gas after the dust collection process is, for example, the O ₂ concentration in the exhaust gas after the dust collection by the bag filter 4 in FIG. May be the O ₂ concentration in the exhaust gas, and refers to the O ₂ concentration measured by a continuous measuring instrument. If the combustion in the incinerator is active, the temperature inside the furnace increases, and the O ₂ contained in the combustion air is greatly consumed to reduce the O ₂ concentration. That is, the O ₂ concentration is one index indicating the incineration state.

As described above, each of the indices a) to h) is an index indicating the activeness or inactivity of the incineration state in the incinerator. Is an easy indicator of The present invention does not always detect the concentration of harmful components in the exhaust gas of unsprayed chemicals and uncollected dust that is difficult to continuously measure because it is dust-containing, that is, without newly installing a continuous measurement device,
This is a value measured by a continuous measuring instrument already installed in a normal exhaust gas treatment facility, which has a relatively fast response. A) The exhaust gas flow rate after dust collection, b) the exhaust gas temperature upstream of the exhaust gas cooling means by water spray, Steam generated by steam-type heat recovery means, d)
Combustion air quantity to the waste incinerator, e) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, h) Since the amount of harmful components to be treated is estimated using one or more of the O ₂ concentrations in the exhaust gas after dust collection, the spray amount of the chemical can be set based on this using a simpler method. Becomes at the same time,
The effect of avoiding the intense pulsation of the concentration of the harmful component after treatment and the wasteful consumption of the chemical spray amount by the conventional control can be obtained.
That is, it is possible to minimize the consumption of the drug while suppressing the pulsation of the harmful component after treatment without newly installing a continuous measuring device for the harmful component concentration.

The phrase "without constantly detecting the concentration of harmful components in exhaust gas" means that the concentration of harmful components in exhaust gas not sprayed with chemicals and uncollected is measured, for example, in performance tests during construction of exhaust gas treatment facilities. Then, the measurement result may be used as a reference value in the subsequent normal operation or may be adopted as the reference value according to claims 5 and 6, but it has already been described that the measurement result is not continuously measured in the normal operation. As described above, the reference value described here will be described later.

According to a second aspect of the present invention, when the harmful components to be removed are acidic components such as HCl and SOx and nitrogen oxides such as NOx, the values of the above items a) to g) are different from each other. When the value of the above (h) is lower than the reference value or when the value of the above (h) is lower than the reference value, the spray amount of the corresponding drug is increased in accordance with the degree, and each value of the above (a) to (g) is The harmful component in the exhaust gas according to claim 1, wherein the spraying amount of the corresponding chemical is reduced in accordance with the degree when the value is lower than the reference value or when the value of (h) is higher than the reference value. This is the removal method.

According to a third aspect of the present invention, when the harmful component to be removed is an organic halogen compound such as dioxin, the values of the above (a) to (g) are lower than the respective reference values, or In any case where the value of h) exceeds the reference value, the spray amount of the corresponding drug is increased in accordance with the degree, and whether each value of a) to g) exceeds each reference value, or 2. The method for removing harmful components in exhaust gas according to claim 1, wherein when any one of the values of (1) is lower than the reference value, the spray amount of the corresponding chemical is reduced according to the degree.

The present inventors have conducted intensive studies and have reached the following conclusions. The graph shown in FIG. 3 shows the furnace outlet temperature (exhaust gas temperature upstream of the exhaust gas cooling means by water spray) which is one index indicating the incineration state of the incinerator, and the temperature before the chemical treatment (boiler outlet). 5 shows the results of examining the temporal changes of the HCl concentration and the NOx concentration. According to the figure, the furnace outlet temperature, the HCl concentration and the NOx concentration show a change tendency very similar to each other. The HCl concentration follows the furnace outlet temperature with a delay of about 10 minutes due to a noticeable time delay by the measuring instrument. FIG. 4 shows the correlation between the furnace outlet temperature and the HCl concentration and NOx concentration corrected for the time delay.
According to the figure, it can be seen that both the furnace outlet temperature and the HCl concentration and the furnace outlet temperature and the NOx concentration remarkably show a positive correlation. That is, the harmful component HCl
Since the concentration and the NOx concentration have a good positive correlation with the furnace outlet temperature, which is an index indicating the incineration state of the incinerator, when estimating the amount of harmful components to be treated, b) exhaust gas cooling means by water spray The result is that the furnace outlet temperature, which is the temperature of the exhaust gas on the upstream side, may be used. Then, if the spray amount of the medicine is controlled based on the estimated harmful component amount, it becomes possible to spray the minimum amount of medicine without time delay.

As described above, it has been found that the furnace outlet temperature and the concentration of harmful components (HCl, NOx) have a positive correlation. The spray amount may be increased according to the degree when the value exceeds the reference value, and the spray amount may be decreased according to the degree when the value falls below the reference value. Can be obtained. Of course, in place of the furnace outlet temperature, a furnace temperature, a boiler one-pass temperature, a boiler two-pass temperature, and a boiler outlet temperature that show the same change tendency may be used. It is sufficient if the temperature is the exhaust gas temperature.

SOx, which is an acidic component, behaves similarly to HCl, which is an acidic component, and thus can be controlled in the same manner. In the case of a refuse incineration facility, since the HCl concentration is as high as, for example, about 10 times the SOx concentration, it is sufficient to control only HCl to remove acidic components.

The present inventors have further determined: a) the flow rate of the exhaust gas after the dust collection, c) the amount of steam generated by the steam type heat recovery means,
D) the combustion air quantity to the waste incinerator, e) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, In any case,
B) Similar to the temperature of the exhaust gas upstream of the exhaust gas cooling by water spray, a positive correlation (not shown) with acidic components such as HCl and SOx and nitrogen oxides such as NOx was found. The same control as in the case b) can be performed by using one or more of the above, and the same operation and effect can be obtained.

On the other hand, (h) the O ₂ concentration in the exhaust gas after the dust collection process has been found to have a negative correlation with the CO ₂ concentration in the exhaust gas after the dust collection process. Unlike the case of (1), there is a negative correlation with the concentration of acidic components and the concentration of nitrogen oxides. That is, in the case of (h), when the value of (h) exceeds the reference value, the spray amount of the drug is reduced according to the degree, and when the value of (h) is below the reference value, the spray amount of the drug is increased according to the degree. By doing so, the same functions and effects as in cases a) to g) can be obtained.

Next, when the harmful component to be removed is an organic halogen compound such as dioxin, the present inventors have found that the same action can be obtained by the reverse control.

The graph shown in FIG. 7 is an index indicating the incineration state of the incinerator, the furnace outlet temperature (above mentioned (b) the exhaust gas temperature upstream of the exhaust gas cooling means by water spray) and the chemical treatment (boiler). It shows the result of investigating the relationship with the dioxin concentration at the outlet). According to the figure, it can be seen that the furnace outlet temperature and the dioxin concentration clearly show a negative correlation. That is, organic halogen compounds such as dioxin, which is a harmful component, have a good negative correlation with the furnace exit temperature, which is an index indicating the incineration state of the incinerator, so when estimating the amount of the harmful component to be treated, (B) The result is that the furnace outlet temperature, which is the temperature of the exhaust gas upstream of the means for cooling the exhaust gas by water spraying, may be used. Then, if the spray amount of the medicine is controlled based on the estimated harmful component amount, it becomes possible to spray the minimum amount of medicine without time delay. It was found that the furnace outlet temperature and the concentration of harmful components (the concentration of organic halogen compounds such as dioxin) had a negative correlation. It is sufficient that the spray amount is increased according to the degree when the value is lower than the predetermined value, and the spray amount is reduced according to the degree when the value exceeds the reference value. Obtainable. Of course, in place of the furnace outlet temperature, a furnace temperature, a boiler one-pass temperature, a boiler two-pass temperature, and a boiler outlet temperature that show the same change tendency may be used. It is sufficient if the temperature is the exhaust gas temperature.

Organic halogen compounds other than dioxins have various molecular forms including a dioxin precursor. For example, if an adsorbent such as activated carbon powder is used as a drug, these can be adsorbed and removed in the same manner as dioxins. The same operation and effect can be obtained.

The present inventors have further determined: a) the flow rate of the exhaust gas after the dust collection, c) the amount of steam generated by the steam type heat recovery means,
D) the combustion air quantity to the waste incinerator, e) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, In any case,
B) Similar to the temperature of the exhaust gas upstream of the exhaust gas cooling means by water spray, it was found that there was a negative correlation (not shown) with organic halogen compounds such as dioxin. The same control as in the case of the above can be performed, and the same operation and effect can be obtained.

Further, (h) the O ₂ concentration in the exhaust gas after the dust collection process has been found to have a negative correlation with the CO ₂ concentration in the exhaust gas after the dust collection process. Unlike the case (g), there is a positive correlation with organic halogen compounds such as dioxin. That is, in the case of (h), if the value of (h) exceeds the reference value, the spray amount of the medicine is increased in accordance with the degree, and if the value of (h) is below the reference value, the spray amount of the medicine is decreased in accordance with the degree. By doing so, the same functions and effects as in cases a) to g) can be obtained.

According to a fourth aspect of the present invention, the reference values of (a) to (h) are the rated value of the exhaust gas treatment facility, the average value during normal operation, the representative value at startup of the exhaust gas treatment facility, and the operating conditions. The method for removing harmful components in exhaust gas according to claim 2 or 3, wherein the method is a value selected from representative values at the time of change.

As described above, the reference values of (a) to (h) are specifically set, and the unspecified reference value of the chemical spray amount corresponding to the harmful component amount corresponding to this reference value is set. ~
The method according to claim 2 or 3, wherein the increase / decrease control of the amount of the medicine spray is performed on the basis of the reference value of the amount of medicine spray with respect to the increase / decrease in the reference value of (h). The effect of the invention according to the above can be obtained more reliably and effectively.

The reference value of the chemical spray amount corresponding to the reference values of (a) to (h) is obtained, for example, from the correlation diagram shown in FIG. At 850 ° C., since the HCl concentration at the boiler outlet is approximately 700 ppm, the corresponding H
What is necessary is just to fill the chemical spraying amount as a Cl removing agent. At this time, needless to say, the reference value of the chemical spray amount is set by using a reference value such as an exhaust gas flow rate as needed. Alternatively, a measurement value or a rated value of the boiler outlet HCl concentration different from FIG. 4 corresponding to the reference value of the furnace outlet temperature is adopted,
A corresponding amount of the chemical spray as the HCl remover may be used. Further, the reference value of the amount of sprayed medicine may be appropriately updated based on the value of the measurement result of the HCl concentration in the untreated exhaust gas that is not indispensable, as appropriate. In these cases, (b) not only the furnace outlet temperature as the exhaust gas temperature upstream of the exhaust gas cooling means by water spray but also one of the items (a) to (h) shown as the invention according to claim 1 or the like. It is apparent from the above that the indicated values may be used, by analogy.

According to a fifth aspect of the present invention, the amount of the harmful component to be treated is estimated by using a plurality of the items (a) to (h). The spray amount of the medicine is increased accordingly, and when this value is lower than the reference value, the spray amount of the medicine is decreased according to the degree thereof. This is a method for removing harmful components in exhaust gas.

When a plurality of items described in (a) to (h) are used,
For example, a) harmful components due to the exhaust gas flow rate after dust collection
Estimated amount, b) upstream of exhaust gas cooling means by water spray
Estimated amount of harmful components by furnace outlet temperature as exhaust gas temperature,
C) O in exhaust gas after dust collection processing _TwoHazardous component estimation by concentration
Quantification, and the predetermined weight of each of these estimators
Calculated average value and re-estimated as harmful component estimator, then
The spray amount of the medicine based on this is compared with the reference value of the amount of harmful components.
This is to increase or decrease the amount of sprayed medicine. in this way
Using multiple control factors, the total amount of harmful components
And the corresponding amount of sprayed medicine is estimated.
It is possible to control the amount of the medicine sprayed with an accurate amount.
The operation described in 4 can be further ensured.

Here, when a plurality of control factors are adopted from (a) to (h), selection of the following control factors is more effective. That is, as the first group, a) the exhaust gas flow rate after the dust collection process, d) the combustion air amount to the waste incinerator,
E) Secondary air volume to waste incinerator, as second group, b)
Exhaust gas temperature upstream of exhaust gas cooling means by water spray,
C) the amount of steam generated by the steam-type heat recovery means, f) the lower heating value of the incinerated material, as a third group, g) the CO ₂ concentration in the exhaust gas after dust collection, and h) in the exhaust gas after dust collection. O ₂ concentration,
When divided into three groups, it is desirable to adopt zero or one or more of these groups and to employ a total of two or more from two different groups. This is because the control factors of the first group, the second group, and the third group have relatively similar properties in each group and the correlation between the control factors is stronger. This is because selecting two or more from different groups, rather than selecting a plurality from, allows application of chemical spray amount control in accordance with a wider range of operating conditions of the exhaust gas treatment facility.

To explain this more specifically, in the case of removing acidic components, for example, from the first group, which greatly affects the amount of exhaust gas, a) the exhaust gas flow rate after the dust collection processing is adopted, and it is closely related to the exhaust gas temperature. B) The furnace outlet temperature as the exhaust gas temperature upstream of the exhaust gas cooling means by water spray is set to 2
When adopted as the second, the opposite result is that although the former exhaust gas flow rate increases and the chemical spray amount is estimated to be large, the latter furnace outlet temperature is lowered and the chemical spray amount is estimated to be small. May occur depending on some operating conditions, but it is better to adopt the estimated value of the total amount of chemical spray as a result of these conflicting results from the same first group. , D) Adopting two combustion air volumes to the waste incinerator to obtain a more accurate chemical spray volume than when both the exhaust gas flow rate and the fuel air volume estimated from the combustion air volume are estimated to be larger. It can be estimated. This is not limited to the example described here, and it is more preferable to employ a plurality of groups from different groups than to employ a plurality of groups from the same group having a strong correlation with each other.

According to a sixth aspect of the present invention, the reference value of the estimated amount of the harmful component according to the fifth aspect is a rated value of an exhaust gas treatment facility, an average value during normal operation, and a representative value at startup of the exhaust gas treatment facility. A method for removing harmful components in exhaust gas, characterized in that the value is a value selected from a value and a representative value when operating conditions are changed.

As described above, after the reference value of the amount of harmful components estimated by the plurality of control factors a) to h) is specifically set, the excess or deficiency of the spray amount of the corresponding chemical due to the plurality of factors is determined. Since the control is performed by the method described in claim 5, the operation of the invention according to claim 5 can be obtained more reliably and effectively.

The invention according to claim 7 is characterized in that the drug is a calcium compound or a sodium compound, and is a powdery, liquid or slurry-type basic neutralizer. The method for removing harmful components in exhaust gas according to any one of 2, 4, 5, and 6.

As a chemical for removing acidic components such as HCl and SOx, if a powdery, liquid or slurry-like basic neutralizing agent, which is a calcium compound or a sodium compound, is employed, it is relatively effective. This is desirable because it is inexpensive and has excellent neutralization efficiency. More desirably, powdered slaked lime (Ca (OH) ₂ ) having almost no change in exhaust gas temperature by spraying a chemical may be inexpensive. However, these choices are determined according to the specifications of the equipment in the existing exhaust gas treatment facility, or determined appropriately according to other operating conditions and the like.

The invention according to claim 8 is characterized in that the chemical is one of ammonia gas, aqueous ammonia and urea water, or an amine chemical that generates ammonia gas. 4. The method for removing harmful components in exhaust gas according to any one of 4, 5, and 6.

As a chemical for removing nitrogen oxides such as NOx, any one of ammonia gas, aqueous ammonia, and urea water, or an amine-based chemical that generates ammonia gas can be used at a relatively low cost. It is desirable because it can be used for both non-catalytic denitration and catalytic denitration. More desirably, ammonia gas from an ammonia cylinder or the like can be easily provided for both non-catalytic denitration and catalytic denitration, and the handling and incidental facilities can be simplified, and the reaction efficiency is slightly higher than urea water. Having a point is desirable.

[0049] The invention according to claim 9 is characterized in that the drug is a carbon-based porous powder.
The method for removing harmful components in exhaust gas according to any one of 4, 5, and 6.

It is desirable to employ a carbon-based porous powder as a chemical for removing organic halogen compounds such as dioxin, since the organic halogen compound can be more efficiently adsorbed and removed because it is carbon-based. More preferably, it is preferable to use activated carbon powder having a large specific surface area and a sufficient ignition point and a high ignition point.

According to a tenth aspect of the present invention, there is provided a method for detecting the concentration of various harmful components after spraying a drug and controlling the amounts of spraying the corresponding various drugs by feedback control. This is a method for removing harmful components in exhaust gas performed in combination with the above.

By combining the feedback control as described above, the amount or concentration of the harmful component to be discharged can be more safely and reliably suppressed to a predetermined value or a predetermined value or less.

The invention according to claim 11 is an apparatus for removing harmful components contained in flue gas by spraying a chemical on flue gas from a waste incinerator, comprising: a) a) a flow rate of flue gas after a dust collection process; The temperature of the exhaust gas upstream of the exhaust gas cooling means by water spray; c) the amount of steam generated by the heat recovery means; d) the amount of combustion air to the waste incinerator; e) the amount of secondary air to the waste incinerator. Lower calorific value of incinerated material; g) CO ₂ concentration in exhaust gas after dust collection processing;
O ₂ concentration in the exhaust gas after h) dust collection, and one or more continuous measuring device for measuring at least one of, b) the by integrating a measured value signal from the continuous measurement instrument to be processed A drug spray amount calculator for estimating a harmful component amount, calculating a drug spray amount based on the harmful component amount, and transmitting a drug spray amount signal to a drug spray amount control device; c) a drug spray amount signal from the drug spray amount calculator. And d) a harmful component removing device for removing harmful components in exhaust gas by chemical spraying. Since the chemical spray amount calculator, the chemical spray amount control device, and the harmful component removing device are configured as described above, the invention according to claims 1 to 6 can be easily implemented.

According to the twelfth aspect of the present invention, when a chemical for removing an acidic component or an organic halogen compound in the exhaust gas is used, the harmful component removing device includes a bag filter, a dry reaction tower, a semi-dry reaction tower, a wet washing tower, The at least one device selected from a cooling tower.
It is an exhaust gas processing apparatus of the description. By defining the harmful component removing agent and the harmful component removing device in this way, it is possible to more reliably implement the inventions according to claims 1 to 7, 9, and 11.

According to a thirteenth aspect of the present invention, when a chemical for removing nitrogen oxides in exhaust gas is used, the harmful component removing device is a non-catalytic denitration device and / or a denitration device installed in an incinerator or an outlet of the incinerator. 2. The tower according to claim 1, wherein the tower is a tower.
An exhaust gas treatment apparatus according to item 1. By defining the harmful component removing agent and harmful component removing device in this way,
The invention according to claims 1, 2, 4 to 6, 8, and 11 can be more reliably implemented.

According to a fourteenth aspect of the present invention, a plurality of chemical spray amount control devices are provided.
An exhaust gas treatment apparatus according to any one of the above. As described above, since a plurality of chemical spray amount control devices corresponding to various chemicals for removing acidic components such as HCl and SOx, nitrogen oxides such as NOx, and organic halogen compounds such as dioxins are installed, more types of chemical sprays are provided. The effect of simultaneously removing harmful components with high accuracy and the effect of the invention according to claims 1 to 9 and 11 to 13 can be obtained.

[0057]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an example of an embodiment in which the method for removing harmful components according to the present invention is applied to a refuse incineration facility. FIG. 2 is a block diagram showing an example of another embodiment in which the harmful component removing method according to the present invention is employed in a refuse incineration facility. The configuration shown in FIG. 1 includes an HCl concentration detector 28 and a NOx concentration. Detector 29
And a CO concentration detector 30 is added. In these figures, 1 is a waste incinerator, 2 is a boiler, 3 is a cooling tower, 4 is a bag filter, 5 is a denitration tower, 6 is a chimney, 11
Is an exhaust gas flow detector installed at the outlet of the denitration tower 5 (or the inlet of the chimney 6), 12 is a furnace outlet temperature detector capable of continuously measuring the exhaust gas temperature at the outlet of the waste incinerator 1, 13
Is a steam generation amount detector capable of continuously measuring the steam generation amount of the boiler 2, 14 is a combustion air amount detector capable of continuously measuring the amount of combustion air to the waste incinerator 1, and 15 is the waste incinerator 1. Secondary air flow detector capable of continuously measuring space-time volume
Is a low calorific value detector capable of continuously measuring the lower calorific value of the incinerated material, 17 is a chemical spray amount calculator, 18 is a slaked lime spray amount control device, 19a is an ammonia gas spray amount control device (for a denitration tower), 19b Is an ammonia gas spray amount control device (for a non-catalytic denitration device), 20 is an activated carbon spray amount control device, and 21 is C
An O ₂ concentration detector, 22 is an O ₂ concentration detector, 28 is an HCl concentration detector, 29 is a NOx concentration detector, and 30 is a CO concentration detector.

Hereinafter, an outline of a processing flow of exhaust gas generated during incineration of waste will be described with reference to FIGS.

[0059] 700 to 1 discharged from the waste incinerator 1
The exhaust gas at 000 ° C. is introduced into the boiler 2 and is cooled to, for example, 200 to 400 ° C. by heat recovery. Subsequently, the exhaust gas is introduced into the cooling tower 3 and cooled to a constant temperature in the range of 150 to 250 ° C. suitable for the bag filter 4 by water spray from a spray nozzle. The air is emitted from the chimney 6 through the air outlet 5. The exhaust gas discharged from the waste incinerator 1 includes HCl, SO
harmful components such as acidic components such as x, nitrogen oxides such as NOx, and organic halogen compounds such as dioxin. Among them, acidic components such as HCl and SOx are contained in the slaked lime from the slaked lime spray amount controller 18. By spraying, the gas is removed by a neutralization reaction in the flue at the entrance of the bag filter 4 or in the bag filter 4. Organic halogen compounds such as dioxin are removed by the activated carbon spray from the activated carbon spray amount control device 20 by adsorption in the flue at the entrance of the bag filter 4 or in the bag filter 4. Nitrogen oxides such as NOx are removed by the ammonia gas spray from the ammonia gas spray amount control device 19a and the denitration catalyst in the denitration tower 5 and the selective catalytic denitration reaction. Further, if necessary, the ammonia gas spray from the ammonia gas spray amount control device 19b causes a selective non-catalytic deNOx reaction in the incinerator 1 or a non-catalytic NOx device (not shown) installed at the outlet of the incinerator 1. Is removed.

The method of removing harmful components according to the present invention is characterized in that the method for removing harmful components represented by three of the slaked lime spray amount control device 18, the ammonia gas spray amount control devices 19a and 19b, and the activated carbon spray amount control device 20. The following method is used in the operation of the medicine spray amount control device for the purpose. When spraying chemicals on the exhaust gas from the waste incinerator 1 to remove the harmful components contained in the exhaust gas, the concentration of the harmful components in the untreated exhaust gas is not constantly detected, and a) the flow rate of the exhaust gas after the dust collection process B) the temperature of the exhaust gas upstream of the exhaust gas cooling means by water spray; c) the amount of steam generated by the steam heat recovery means;
D) the combustion air quantity to the waste incinerator, e) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, H) The amount of harmful components to be treated is estimated using one or more of the O ₂ concentrations in the exhaust gas after the dust collection process, and the spray amount of the chemical is controlled based on this.

More specifically, one or more of the measured value signals of the above (a) to (h), namely, (a) a measurement signal from the exhaust gas flow rate detector 11 indicating the exhaust gas flow rate after the dust collection processing, and (b) water A measurement signal from the furnace outlet temperature detector 12 indicating the temperature of the exhaust gas upstream of the exhaust gas cooling means by spraying; c) a measurement signal from the steam generation amount detector 13 indicating the amount of steam generated by the steam type heat recovery means; A measurement signal from the combustion air amount detector 14 indicating the amount of combustion air to the waste incinerator; e) a measurement signal from the secondary air amount detector 15 indicating the secondary air amount to the waste incinerator. ) the measurement signal from the lower heating value detector 16 indicating the lower heating value of the incinerated, g) the measurement signal from the CO ₂ concentration detector 21 indicating the CO ₂ concentration in the exhaust gas after dust collection, h) collection from the O ₂ concentration detector 22 indicating the O ₂ concentration in the exhaust gas after the dust treatment One or more measured value signals among the constant signals are transmitted to the chemical spray amount calculator 17, the calculator 17 estimates various harmful component concentrations, and a signal of the spray required amount of various drugs based on the concentration is estimated. To each of the slaked lime spray amount control device 18, the ammonia gas spray amount control devices 19a and 19b, and the activated carbon spray amount control device 20, and the three control devices spray the various chemicals by the corresponding harmful component removing device. Do.

Here, for each of the above a) to h),
It will be described again. B) The flow rate of the exhaust gas after the dust collection process may be the flow rate of the exhaust gas after the denitration tower 5 in the subsequent stage, for example, if the flow rate of the exhaust gas after the dust collection by the bag filter 4 in FIG. Uses the exhaust gas flow value continuously measured by the exhaust gas flow detector 11 after the denitration tower 5 as a control factor. Although the exhaust gas flow rate is often converted to normal by an exhaust gas thermometer (not shown), either the normal converted exhaust gas flow rate or not may be adopted. This is because the temperature of the exhaust gas that normally exits the dust collector is substantially constant, and the tendency of the exhaust gas flow rate is similar whether or not the value of the exhaust gas flow rate is converted by the temperature. The exhaust gas flow rate tends to increase when the amount of incineration in the incinerator or the calorific value of the incinerated material is large. That is,
The exhaust gas flow rate is one index indicating the incineration state.

B) The temperature of the exhaust gas upstream of the exhaust gas cooling by water spray is, for example, the temperature in the incinerator, the temperature of the incinerator outlet detected by the furnace outlet temperature detector 12, the temperature of one pass of the boiler (not shown), the temperature of the boiler 2 The temperature of the exhaust gas generated in the incinerator, such as the pass temperature and the boiler outlet temperature (not shown), may be the temperature before the exhaust gas is cooled by the water spray from the cooling tower 3 or the like. By cooling with water spray, the temperature is forcibly adjusted to a temperature suitable for the dust collector of the bag filter 4 at the subsequent stage.
After the water spray cooling, the temperature does not reach the temperature indicating the incineration state of the furnace. The graph shown in FIG. 5 shows that the furnace temperature A, the furnace outlet temperature B, and the boiler two-pass temperature C have different average values, but the fluctuations are very similar, indicating that there is a good correlation. Although not shown in the figure, it has been confirmed that the boiler one-pass temperature also has a good correlation, and that the boiler outlet temperature has a similar relationship, although a little slower due to the large amount of heat recovered. That is, these temperatures are one index indicating the incineration state.

C) The amount of steam generated by the steam-type heat recovery means is the amount of high-pressure steam generated in the boiler (evaporation amount). When the incineration temperature is high, the amount of steam generated tends to increase. The steam generation amount is a signal continuously detected by the steam generation amount detector 13. The graph shown in FIG. 5 shows that the furnace temperature A and the like and the evaporation amount D have a good correlation.
That is, the amount of generated steam is one index indicating the incineration state.

D) The amount of combustion air to the waste incinerator
For example, it refers to the amount of air introduced as combustion air into the furnace from a combustion air inlet (not shown) provided at the lower part of the incinerator. The combustion air amount is determined by a combustion air amount detector 14.
Is a signal continuously detected by When the amount of incineration in the incinerator 1 or the calorific value of the incinerated material is large, the amount of combustion air tends to increase. That is, the combustion air amount is one index indicating the incineration state.

E) The amount of secondary air to the waste incinerator is determined, for example, by a secondary air inlet (not shown) installed near or inside the incinerator outlet, and the secondary air is injected into the furnace or at the outlet. The amount of air introduced as combustion air. The secondary air amount is a signal continuously detected by the secondary air amount detector 15. While the secondary air promotes secondary combustion, it may also serve to cool the furnace temperature which has become too high in some cases. In any case, when the amount of incineration in the incinerator 1 or the calorific value of the incinerated material is large, the amount of secondary air tends to increase. That is, the secondary air amount is one index indicating the incineration state.

F) The lower heating value of the incinerated material is the calorific value obtained as a heat source when the incinerated material is burned, which is calculated in advance from the furnace temperature, the amount of waste, and the like (not described). is there. The lower calorific value is a signal continuously detected by the lower calorific value detector 16, but is often calculated from the furnace temperature and the amount of waste input as described above. It is the value detected by the detector 16. When the lower heating value is managed centrally in a continuous incinerator or the like, it is recorded as operating data. If the lower heating value of the incinerated material is large, the furnace temperature tends to increase. That is, the lower heating value is one index indicating the incineration state.

G) The CO ₂ concentration in the exhaust gas after the dust collection processing means, for example, the CO ₂ concentration in the exhaust gas after being collected by the bag filter 4 in FIG. The CO ₂ concentration in the exhaust gas may be the CO ₂ concentration measured by the continuous CO ₂ concentration detector 21. If combustion is vigorous in incinerator 1, the furnace temperature is much generates CO ₂ consumes large O ₂ contained in the combustion air with increased. That is, the CO ₂ concentration is one index indicating the incineration state.

(H) The O ₂ concentration in the exhaust gas after the dust collection process is, for example, the O ₂ concentration in the exhaust gas after being collected by the bag filter 4 in FIG. May be the O ₂ concentration in the exhaust gas, and refers to the O ₂ concentration measured by the continuous O ₂ concentration detector 22. If the combustion in the incinerator 1 is active, the temperature inside the furnace rises, and the O ₂ contained in the combustion air is greatly consumed to reduce the O ₂ concentration. That is, the O ₂ concentration is one index indicating the incineration state.

As described above, each of (a) to (h) is an index indicating the activeness or inactiveness of the incineration state in the incinerator. Is an easy indicator of At least one of the signals of these indices is accumulated in the medicine spray amount calculator 17 to estimate the concentration of various harmful components and control the spray amount of various medicines. The present invention does not always detect the concentration of harmful components in exhaust gas of unsprayed and uncollected chemicals, which are difficult to continuously measure because of containing dust, that is, without newly installing a continuous measuring device, Fast response, measured by a continuous measuring instrument already installed in an ordinary exhaust gas treatment facility, a) exhaust gas flow rate after dust collection, b) exhaust gas temperature upstream of exhaust gas cooling means by water spray, c) steam type The amount of steam generated by the heat recovery means, d) the amount of combustion air to the waste incinerator, e) the amount of secondary air to the waste incinerator, f) the lower calorific value of the incinerator, g) after dust collection CO ₂ concentration in the exhaust gas, Ji) O ₂ concentration in the exhaust gas after dust collection, since estimates the harmful components of the processing target using one or more of,
The spray amount of the medicine can be set based on the spray amount by a simpler method. At the same time, the effect of avoiding the pulsation of the concentration of the harmful component after the treatment and the wasteful consumption of the chemical spray amount by the conventional control can be obtained. That is, it is possible to minimize the consumption of the drug while suppressing the pulsation of the harmful component after treatment without newly installing a continuous measuring device for the harmful component concentration.

The phrase "without constantly detecting the concentration of harmful components in exhaust gas" means that the concentration of harmful components in exhaust gas not sprayed with chemicals and uncollected is measured, for example, in a performance test at the time of constructing an exhaust gas treatment facility. Then, the measurement result may be used as a reference value in the subsequent normal operation or may be adopted as the reference value according to claims 5 and 6, but it has already been described that the measurement result is not continuously measured in the normal operation. The reference value described here will be described later.

Next, in the method for removing harmful components in exhaust gas according to this embodiment, the harmful components to be removed are HCl, S
In the case of an acidic component such as Ox or a nitrogen oxide such as NOx, any one of the above-mentioned values a) to g) exceeds each reference value or the value of the above h) falls below the reference value. In this case, the spraying amount of the corresponding drug is increased according to the degree, and each of the values of the above (a) to (g) is lower than the respective reference value or the value of the above (h) is higher than the reference value. The spray amount of the corresponding medicine is reduced in accordance with the degree.

That is, when removing acidic components such as HCl and SOx, any of the measured values of the above (a) to (g) exceeds each of the reference values or the measured value of the above (h) is below the reference value. In this case, the sprayed amount of slaked lime, which is a neutralizing agent, is increased by the slaked lime spray amount control device 18 via the chemical spray amount calculator 17 in accordance with the degree thereof, and each of the measured values a) to g) is changed. If the measured value is lower than each reference value or the measured value in the above (h) is higher than the reference value, the chemical spray amount calculator 1
The spray amount of slaked lime, which is a neutralizing agent, is reduced according to the degree by the slaked lime spray amount control device 18 via 7. The slaked lime from the slaked lime spray amount control device 18 is supplied to the bag filter 4
Is sprayed into the inlet flue or bag filter 4.

Similarly, when removing nitrogen oxides such as NOx, either of the measured values of the above (a) to (g) exceeds the respective reference value or the measured value of the above (h) is lower than the reference value. In this case, the ammonia gas spraying amount control device 19a via the chemical spraying amount calculator 17 increases the ammonia gas spraying amount according to the degree thereof, and the measured values of the above items a) to g) are adjusted to the respective reference values. If the measured value is less than the reference value or the measured value in the above (h) exceeds the reference value,
Via the ammonia gas spray amount control device 19a
The spray amount of ammonia gas is reduced according to the degree. The ammonia gas from the ammonia gas spray amount control device 19a is sprayed into the inlet flue of the denitration tower 5 or into the denitration tower 5. When performing non-catalytic denitration using a non-catalytic denitration device (not shown) attached to the waste incinerator 1, the same operation may be performed using the ammonia gas spray amount control device 19b, and the inside of the incinerator or at the outlet portion The ammonia gas is sprayed in the temperature range of 700 to 900 ° C. to perform non-catalytic denitration.

Next, in the method for removing harmful components in exhaust gas according to this embodiment, when the harmful component to be removed is an organic halogen compound such as dioxin,
-G) is less than each reference value, or
Is larger than the reference value, the spray amount of the corresponding drug is increased in accordance with the degree, and each value of the above (a) to (g) exceeds each reference value, or If the value is lower than the reference value, the spray amount of the corresponding medicine is reduced according to the degree.

That is, when removing the organic halogen compound such as dioxin, the measured value of each of the above (a) to (g) is lower than the respective reference value or the measured value of the above (h) is higher than the reference value. Then, the spraying amount of the activated carbon as the adsorbent is increased by the activated carbon spraying amount control device 20 via the chemical spraying amount calculator 17 according to the degree.
In either case where the measured value of (g) exceeds each reference value or the measured value of (h) is below the reference value, the activated carbon spray amount control device 20 via the chemical spray amount calculator 17 The spray amount of activated carbon as an adsorbent is reduced according to the degree. The activated carbon from the activated carbon spray amount control device 20 is sprayed into the inlet flue of the bag filter 4 or into the bag filter 4.

These methods of controlling the amount of sprayed medicine are based on the results of investigations unique to the present inventors described below.
FIG. 3 shows the furnace exit temperature (exhaust gas temperature upstream of the exhaust gas cooling means by water spray), which is one index indicating the incineration state of the incinerator, and the HC before chemical treatment (boiler exit).
It is a figure which shows the result of having investigated the time change of 1 density | concentration and NOx density | concentration. According to the figure, the furnace outlet temperature, the HCl concentration and the NOx concentration show a change tendency very similar to each other. The HCl concentration follows the furnace outlet temperature with a delay of about 10 minutes due to a noticeable time delay by the measuring instrument. FIG. 4 shows the correlation between the furnace outlet temperature and the HCl concentration and the NOx concentration corrected for the time delay. According to FIG. 4, both the furnace outlet temperature and the HCl concentration and the furnace outlet temperature and the NOx concentration are positively correlated. Can be clearly seen. That is, since the concentration of HCl and the concentration of NOx, which are harmful components, have a good positive correlation with the furnace outlet temperature, which is an index indicating the incineration state of the incinerator, when estimating the amount of harmful components to be treated, The result is that the furnace outlet temperature, which is the exhaust gas temperature upstream of the exhaust gas cooling means by water spraying, may be used.
Then, if the spray amount of the medicine is controlled based on the estimated harmful component amount, it becomes possible to spray the minimum amount of medicine without time delay. Furnace outlet temperature and harmful component concentration (HC
(l, NOx) has been found to have a positive correlation, and the agent for removing harmful components at this time increases the spray amount according to the degree when the furnace outlet temperature exceeds the reference value. When the value falls below the reference value, the spray amount may be reduced in accordance with the degree, and the above-described effect of the invention according to claim 1 can be reliably obtained. of course,
Instead of the furnace outlet temperature, a furnace temperature, a boiler one-pass temperature, a boiler two-pass temperature, and a boiler outlet temperature, which show the same change tendency, may be used. Should be fine.

[0078] SOx, which is an acidic component, exhibits the same behavior as HCl, which is an acidic component, so that the same control is possible. In the case of a refuse incineration facility, since the HCl concentration is as high as, for example, about 10 times the SOx concentration, it is sufficient to control only HCl to remove acidic components.

The present inventors further obtained: a) the flow rate of the exhaust gas after the dust collection, c) the amount of steam generated by the steam type heat recovery means,
D) the combustion air quantity to the waste incinerator, e) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, In any case,
B) Similar to the exhaust gas temperature upstream of the exhaust gas cooling means by water spray, it was found that there was a positive correlation (not shown) with acidic components such as HCl and SOx and nitrogen oxides such as NOx. The same control as in the case of b) using one or more can be performed, and the same operation and effect can be obtained.

On the other hand, (h) the O ₂ concentration in the exhaust gas after the dust collection process has been found to have a negative correlation with the CO ₂ concentration in the exhaust gas after the dust collection process. Unlike the case (g), there is a negative correlation with the acid component concentration and the nitrogen oxide concentration. That is, in the case of (h), when the value of (h) exceeds the reference value, the spray amount of the drug is reduced according to the degree, and when the value of (h) is below the reference value, the spray amount of the drug is increased according to the degree. By doing so, the same functions and effects as in cases a) to g) can be obtained.

Next, when the harmful component to be removed is an organic halogen compound such as dioxin, the present inventors have found that the same action can be obtained by the reverse control. FIG. 7 shows the furnace outlet temperature (exhaust gas temperature upstream of the exhaust gas cooling means by water spray described above) which is one index indicating the incineration state of the incinerator, and the dioxin concentration before chemical treatment (boiler outlet). FIG. 9 is a diagram showing a result of examining the relationship of. According to the figure, it can be seen that the furnace outlet temperature and the dioxin concentration clearly show a negative correlation. That is, organic halogen compounds such as dioxin, which is a harmful component, have a good negative correlation with the furnace exit temperature, which is an index indicating the incineration state of the incinerator, so when estimating the amount of the harmful component to be treated, (B) The result is that the furnace outlet temperature, which is the temperature of the exhaust gas upstream of the means for cooling the exhaust gas by water spraying, may be used. Then, if the spray amount of the medicine is controlled based on the estimated harmful component amount, it becomes possible to spray the minimum amount of medicine without time delay. It has been found that the furnace outlet temperature and the concentration of harmful components (organic halogen compounds such as dioxin) have a negative correlation, so the agent for removing harmful components at this time has a furnace outlet temperature lower than its reference value. In this case, the spray amount may be increased in accordance with the degree, and the spray amount may be decreased in accordance with the degree when the spray amount exceeds the reference value. Can be. Of course, instead of the furnace outlet temperature, the furnace temperature, which shows the same change tendency,
The temperature of the boiler 1 pass, the temperature of the boiler 2 pass, and the temperature of the boiler outlet may be used. B) The temperature of the exhaust gas upstream of the exhaust gas cooling means by water spray may be used.

Organic halogen compounds other than dioxins have various molecular forms including a dioxin precursor. For example, if an adsorbent such as activated carbon powder is used as a drug, these can be adsorbed and removed in the same manner as dioxins. The operation and effect of the invention can be obtained.

The present inventors have further determined: a) the flow rate of the exhaust gas after the dust collection, c) the amount of steam generated by the steam type heat recovery means,
D) the combustion air quantity to the waste incinerator, e) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, In any case,
B) Similar to the temperature of the exhaust gas upstream of the exhaust gas cooling means by water spray, it was found that there was a negative correlation (not shown) with organic halogen compounds such as dioxin. The same control as in the case is possible, and the same operation and effect can be obtained.

On the other hand, (h) the O ₂ concentration in the exhaust gas after the dust collection process has been found to have a negative correlation with the CO ₂ concentration in the exhaust gas after the dust collection process. Unlike the case (g), there is a positive correlation with organic halogen compounds such as dioxin. That is, in the case of (h), if the value of (h) exceeds the reference value, the spray amount of the medicine is increased in accordance with the degree, and if the value of (h) is below the reference value, the spray amount of the medicine is decreased in accordance with the degree. By doing so, the same functions and effects as in cases a) to g) can be obtained.

Next, in the method for removing harmful components in the exhaust gas according to this embodiment, the reference values of the above items a) to h) are changed to the rated value of the exhaust gas treatment facility, the average value during normal operation, Typical values at start-up, typical values when operating conditions are changed,
The value is selected from the following. That is, the above a)
Any of the reference values of (1) to (4) selected from the rated value of the exhaust gas treatment facility, the average value during normal operation, the representative value when starting up the exhaust gas treatment facility, and the representative value when changing the operating conditions. Alternatively, these average values may be employed.

As described above, the reference values of (a) to (h) are specifically set, and the unspecified reference values of the various chemical spray amounts corresponding to the various harmful component amounts corresponding to the reference values are set.
With respect to the increase / decrease with respect to the reference values of (a) to (h), the method according to claim 2 or 3 is used to perform the increase / decrease control of the amount of various kinds of medicine spraying based on the reference value of the amount of various kinds of medicine spraying. The operation of the invention according to claim 2 or 3 can be obtained more reliably and effectively.

The reference value of the spray amount of the chemical such as slaked lime corresponding to the reference value of (a) to (h) can be obtained, for example, from the correlation diagram shown in FIG. When the furnace outlet temperature is 850 ° C., the HCl concentration at the boiler outlet is approximately 700 ppm, and therefore, it is sufficient to fill the corresponding amount of slaked lime as the HCl remover. Alternatively, a measured value or a rated value of the HCl concentration at the boiler outlet different from that in FIG. 4 corresponding to the reference value of the furnace outlet temperature may be adopted, and the slaked lime spray amount as the HCl remover corresponding thereto may be used. Further, the reference value of the slaked lime spray amount may be appropriately updated based on the value of the measurement result of the indispensable measurement of the HCl concentration in the chemical untreated exhaust gas. At this time, it goes without saying that the reference value of the slaked lime spray amount is set using the reference value such as the exhaust gas flow rate as needed. Here, it has been described that the slaked lime spray amount corresponding to the HCl concentration or amount is set for convenience. It is desirable to determine the reference value of the slaked lime spray amount by utilizing the relationship between the amount (slaked lime equivalent ratio) and the HCl removal rate.

In these cases, b) not only the furnace outlet temperature as the exhaust gas temperature upstream of the exhaust gas cooling means by water spray but also the a) to h) of the invention according to claim 1 etc. It will be clear from the foregoing that one or more of the indicated values may be used. The same applies when the harmful component is a nitrogen oxide such as NOx or an organic halogen compound such as dioxin.

Next, in the method for removing harmful components in exhaust gas according to this embodiment, the amount of harmful components to be treated is estimated by using a plurality of items a) to h) above. When the value exceeds the reference value, the spray amount of the medicine is increased in accordance with the degree, and when the value is lower than the reference value, the spray amount of the medicine is decreased in accordance with the degree.

That is, in the case where the harmful component is an acidic component such as HCl or SOx, a plurality of control signals of the above (a) to (h) are integrated and calculated by the chemical spray amount calculator 17 to be processed. Estimate the amount of acidic component of, when this value exceeds the reference value of the amount of acidic component, increase the spray amount of slaked lime in the slaked lime spray amount control device 18 according to the degree,
When this value is lower than the reference value, the slaked lime spray amount may be controlled so that the slaked lime spray amount in the slaked lime spray amount control device 18 is reduced according to the degree. The same applies when the harmful component is a nitrogen oxide such as NOx or an organic halogen compound such as dioxin.

If a plurality of items described in a) to h) are used,
For example, a) harmful components due to the exhaust gas flow rate after dust collection
Estimated amount, b) upstream of exhaust gas cooling means by water spray
Estimated amount of harmful components by furnace outlet temperature as exhaust gas temperature,
C) O in exhaust gas after dust collection processing _TwoHazardous component estimation by concentration
Quantification, and the predetermined weight of each of these estimators
Calculated average value and re-estimated as harmful component estimator, then
The spray amount of the medicine based on this is compared with the reference value of the amount of harmful components.
This is to increase or decrease the amount of sprayed medicine. in this way
Using multiple control factors, the total amount of harmful components
And the corresponding amount of sprayed medicine is estimated.
It is possible to control the amount of the medicine sprayed with an accurate amount.
The operation described in 4 can be further ensured.

Here, when a plurality of control factors are adopted from (a) to (h), selection of the following control factors is more effective. That is, as the first group, a) the exhaust gas flow rate after the dust collection process, d) the combustion air amount to the waste incinerator,
E) Secondary air volume to waste incinerator, as second group, b)
Exhaust gas temperature upstream of exhaust gas cooling means by water spray,
C) the amount of steam generated by the steam-type heat recovery means, f) the lower heating value of the incinerated material, as a third group, g) the CO ₂ concentration in the exhaust gas after dust collection, and h) in the exhaust gas after dust collection. O ₂ concentration,
When divided into three groups, it is desirable to adopt zero or one or more of these groups and to employ a total of two or more from two different groups. This is because the control factors of the first group, the second group, and the third group have relatively similar properties in each group and the correlation between the control factors is stronger. This is because the selection of two or more from different groups can apply the spray amount control of the chemical in accordance with a wider range of operating conditions of the exhaust gas treatment facility than the selection of a plurality from.

To explain this more specifically, in the case of removing acidic components, for example, from the first group, which greatly affects the amount of exhaust gas, a) the exhaust gas flow rate after the dust collection process is adopted, and it is closely related to the exhaust gas temperature. B) The furnace outlet temperature as the exhaust gas temperature upstream of the exhaust gas cooling means by water spray is set to 2
When adopted as the second, the former results in a large amount of chemical spraying due to an increase in the exhaust gas flow rate, but the latter results in a low furnace outlet temperature and a low amount of chemical spraying. May occur depending on some operating conditions, but it is better to adopt the estimated value of the total amount of chemical spray as a result of these conflicting results from the same first group. , D) Adopting two combustion air volumes to the waste incinerator to obtain a more accurate chemical spray volume than when both the exhaust gas flow rate and the fuel air volume estimated from the combustion air volume are estimated to be larger. It can be estimated. This is not limited to the example described here, and it is more preferable to employ a plurality of groups from different groups than to adopt a plurality of groups from the same group having a strong correlation with each other.

Next, in the method for removing harmful components in the exhaust gas according to this embodiment, the reference value of the estimated amount of harmful components according to claim 5 is changed to the rated value of the exhaust gas treatment facility and the average value during normal operation. , A representative value when starting up the exhaust gas treatment facility, and a representative value when changing the operating conditions. That is, as the reference value of the estimated amount of the harmful component according to claim 5, the rated value of the exhaust gas treatment facility, the average value during normal operation, the representative value at startup of the exhaust gas treatment facility, and the representative value when the operating conditions are changed. Value, or an average value of these values.

The required chemical spray amount corresponding to the reference value of the harmful component amount is, for example, in the case of slaked lime, the relationship between the slaked lime spray amount (slaked lime equivalent) and the HCl removal rate shown in FIG. May be determined with reference to the relationship between the activated carbon spray amount and the dioxin concentration shown in FIG. in this way,
6. The method according to claim 5, wherein a reference value of a harmful component amount estimated by a plurality of control factors of a) to h) is specifically set, and a corresponding excess or deficiency of the spray amount of the drug due to the plurality of factors is set. Therefore, the effect of the invention according to claim 5 can be obtained more reliably and effectively.

Next, a chemical for removing acidic components such as HCl and SOx is a calcium compound or a sodium compound, which uses a powdery, liquid or slurry basic neutralizer. is there. As a chemical for removing acidic components such as HCl and SOx, a powdery, liquid or slurry-like basic neutralizing agent, which is a calcium compound or a sodium compound, is relatively inexpensive and It is desirable because the neutralization reaction efficiency is excellent. More desirably, powdered slaked lime (Ca (OH) ₂ ) having almost no change in exhaust gas temperature by spraying a chemical may be inexpensive. However, it is determined according to the specifications of the equipment of the existing exhaust gas treatment facility or appropriately determined according to other operating conditions.

Next, as a chemical for removing nitrogen oxides such as NOx, any one of ammonia gas, aqueous ammonia, and urea water, or an amine chemical that generates ammonia gas is used. As chemicals for removing nitrogen oxides such as NOx, ammonia gas, aqueous ammonia,
Employing any of urea water and an amine-based agent that generates ammonia gas is desirable because it is relatively inexpensive and can be used for both non-catalytic denitration and catalytic denitration. More desirably, ammonia gas from an ammonia cylinder or the like can be easily provided for both non-catalytic denitration and catalytic denitration, and the handling and incidental facilities can be simplified, and the reaction efficiency is slightly higher than urea water. Having a point is desirable.

Next, carbon-based porous powder is used as a chemical for removing organic halogen compounds such as dioxin. If a carbon-based porous powder is used as a chemical for removing an organic halogen compound such as dioxin, it is desirable to be able to more efficiently adsorb and remove the organic halogen compound because it is carbon-based. More preferably, it is preferable to use activated carbon powder having a large specific surface area and a sufficient ignition point and a high ignition point.

Next, in the method for removing harmful components in exhaust gas according to this embodiment, as shown in FIG. 2, various harmful component concentrations after chemical spraying are detected, and various chemical spray amounts corresponding thereto are detected. The method of controlling by the feedback control is performed in combination with the respective methods of the first to ninth aspects.

An HCl concentration detector 28, a NOx concentration detector 29, and a CO concentration detector 30 are permanently installed in the stack stack of the exhaust gas discharged from the denitration tower 5, and the concentration of each harmful gas component in the exhaust gas is measured. Is measured continuously. These density signals are transmitted to the medicine spray amount calculator 17 together with the above-mentioned signals a) to h), and the feedback control is further added to the medicine spray amount control described above to obtain various medicine spray amount control devices. The control signal is transmitted to and various kinds of medicines are sprayed. By combining the feedback control in this way, it is possible to more safely and reliably suppress the amount or concentration of the harmful component to be discharged to a predetermined value or a predetermined value or less.

In the present invention, when the agent according to claim 7 or 9 is used, that is, when removing an acidic component such as HCl or SOx or an organic halogen compound such as dioxin, for example, slaked lime or activated carbon is used as the agent. When used, a harmful component removing device that removes harmful components by spraying these chemicals, other than the bag filter 4 illustrated,
A dry reaction tower (not shown), a semi-dry reaction tower (not shown), a wet washing tower (not shown), and a cooling tower 3 may be used. The dry reaction tower is a device for spraying slaked lime powder or the like and forcibly mixing with flue gas to remove acidic components in the flue gas in a dry manner, and the same effect can be obtained by using the method of the present invention when controlling the spray amount of slaked lime powder. . The semi-dry reactor is a device that removes acidic components by spraying slaked lime slurry into exhaust gas.
The same effect can be obtained by using the method of the present invention in controlling the spray amount of slaked lime slurry. The wet-type washing tower is a wet-type apparatus that removes acidic components by injecting caustic soda water into exhaust gas, and the same effect can be obtained by controlling the spray amount of caustic soda (NaOH) by using the method of the present invention. Although the cooling tower 3 is a water injection type exhaust gas cooling device, if the slaked lime powder is sprayed at the inlet of the cooling tower or slaked lime slurry is mixed into the water injection spray nozzle, the acidic components in the exhaust gas can be removed. When controlling the spray amount of slaked lime powder or slaked lime slurry, the same effect can be obtained by using the method of the present invention. A plurality of these devices may be used in combination, including the case where the reaction device is the bag filter 4. Similarly, activated carbon to be sprayed when removing organic halogen compounds such as dioxin is a dry reaction tower, a semi-dry reaction tower,
If the apparatus is selected from a wet washing tower and a cooling tower 3, the powder may be sprayed as it is or as a slurry if necessary, and the same effect can be obtained by using the method of the present invention in controlling the spray amount. Can be

In the present invention, when the chemical according to claim 8 is used, that is, when removing nitrogen oxides such as NOx, for example, when using ammonia gas as a chemical, the chemical is sprayed. The harmful component removing device for removing harmful components includes a smokeless medium denitration device (not shown) and / or a denitration tower 5 installed in the incinerator 1 or at the outlet of the incinerator 1.
Should be fine. If the method of the present invention is used to control the amount of ammonia gas sprayed when ammonia gas is removed by spraying ammonia gas onto the non-catalytic denitration apparatus and / or the denitration tower 5 installed in the incinerator 1, The effects of the described invention can be obtained efficiently.

In the present invention, it is preferable that a plurality of drug spray amount control devices are provided using each drug spray amount control device corresponding to the type of drug. For example, a slaked lime spray amount control device 18 for spraying slaked lime, ammonia gas spray amount control devices 19a and 19b for spraying ammonia gas, and an activated carbon spray amount control device 20 for spraying activated carbon are simultaneously provided. It is arranged to be determined and controlled based on each calculation result by the quantity calculator 17.

Thus, acidic components such as HCl and SOx,
Since a plurality of chemical spray amount control devices corresponding to various chemicals for removing nitrogen oxides such as NOx and organic halogen compounds such as dioxin are installed, more kinds of harmful components can be simultaneously and accurately removed, The effects of the invention described above can be obtained.

The type or configuration of the exhaust gas treatment apparatus shown in FIGS. 1 and 2 cited for describing an embodiment of the method for removing harmful components of the present invention is not limited to these. The present invention can be applied to any form in which the medicine is sprayed and added, and the same effect can be obtained.

The slaked lime spray amount control device 18 used in the present invention
The medicine spraying amount control device such as receives the signal from the medicine spraying amount calculator 17 and can control the medicine spraying amount without a large time delay based on the signal. Any format may be used.

The exhaust gas flow rate detector 11, the furnace outlet temperature detector 12, the steam generation amount detector 13, the combustion air amount detector 14, the secondary air amount detector 15, the low heat generation amount detector 16, Known detectors may be used for each of the CO ₂ concentration detector 21 and the O ₂ concentration detector 22. However, since these detectors are used for rapid control of the amount of sprayed medicine, these detectors have relatively quick response. Is desirable.

The case where the embodiment of the present invention is applied to a refuse incineration facility has been described above in detail. However, acidic components such as HCl and SOx and nitrogen oxides such as NOx are contained in exhaust gas discharged during combustion and heating. Applicable if any harmful component of organic halogen compounds such as wastes and dioxins is present. Combustible waste such as industrial waste and other exhaust gas discharged from combustion equipment, and scrap preheating at metal refining plants The same applies to an exhaust gas discharged during melting. Organic halogen compounds such as dioxin that can be removed with carbon-based porous powders such as activated carbon are defined as dioxins and dioxin precursors specified by the Ministry of Health and Welfare as guidelines for converting wastewater into toxic conversion values. It is a generic term for chlorobenzene, chlorophenol, PCB, and the like, which are called substances, and those chemical substances that are partially substituted with halogen elements other than chlorine. Furthermore, dioxins are a general term for polydipentazoparadioxin and polydibenzofuran,
It is usually evaluated by the equivalent toxicity concentration. In this specification, it is refused that these may be simply referred to as dioxins.

[0109]

EXAMPLES Examples showing the effects of the present invention obtained by adopting the method for removing harmful components according to the present invention in a waste incineration plant will be described.

FIG. 9 is a diagram showing the time-dependent changes in the concentration of HCl and NOx at the chimney inlet obtained when the present invention is carried out. FIG. 10 is a diagram showing time-dependent changes in the concentration of HCl and NOx at the chimney inlet obtained when the conventional method is performed. Table 1
3 is a table showing the results of comparing slaked lime consumption and ammonia gas consumption between an example of the present invention and a comparative example of the conventional method. Here, the embodiment of the present invention shown in FIG.
In the comparative example according to the conventional method shown in FIG. 10, the feedback control is performed using only the feedback control. It was what was. In addition, in order to perform an accurate comparison, the operating conditions of the incinerator were set to be substantially the same as those in the example and the comparative example.

[0111]

[Table 1]

According to Table 1, the HCl concentration and the NOx concentration after the treatment (inlet of the chimney) in both the working example of the present invention and the comparative example according to the conventional method could almost reach the target concentration on average. . However, according to FIG. 9, the variation of the HCl concentration and the NOx concentration were as small as about 10 ppm in the example in which the present invention was implemented, whereas the comparative example in which the conventional method was implemented in FIG. ,
The fluctuation range of the HCl concentration was as large as about 50 ppm, and the fluctuation range of the NOx concentration was as large as about 25 ppm, and large pulsations were periodically generated. Furthermore, comparing the examples and comparative examples in Table 1 with respect to the amount of drug consumed, the examples of the present invention show that
Slaked lime consumption was reduced by 35%, and ammonia gas consumption was reduced by 22%. Also, not shown here,
Regarding SOx as an acidic component, the same result as that of HCl shown here was obtained.

As described above, by implementing the present invention,
It has been shown that stable removal of harmful components with minimal fluctuation and pulsation of harmful components after treatment can be achieved, and that the consumption of drugs can be significantly reduced.

[0114]

As described above, according to the present invention, when treating the exhaust gas from a waste incinerator containing various harmful components, the concentration of the harmful component in the exhaust gas is not always detected,
It is a relatively fast response value measured by a continuous measuring instrument provided in existing facilities.
B) the temperature of the exhaust gas upstream of the exhaust gas cooling means by water spray, c) the amount of steam generated by the steam-type heat recovery means, d) the amount of combustion air to the waste incinerator, and e) the secondary air to the waste incinerator. Amount, f) lower calorific value of incinerated material, g) CO ₂ concentration in exhaust gas after dust collection, h) O _{2 in} exhaust gas after dust collection
The concentration of the harmful component to be treated is estimated using one or more of the concentrations, and the spraying amount of the drug is controlled based on the estimated harmful component. The pulsation of the concentration of the harmful component after the treatment by the feedback control and the wasteful consumption of the drug can be avoided, so that the stable removal of the harmful component and the saving of the drug consumption can be achieved by a simple method.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment in which a harmful component removing method according to the present invention is employed in a refuse incineration facility.

FIG. 2 is a block diagram showing another embodiment in which the harmful component removing method according to the present invention is employed in a refuse incineration facility.

FIG. 3 is a diagram showing changes over time of a furnace outlet temperature, HCl concentration, and NOx concentration.

FIG. 4 is a diagram showing a correlation between a furnace outlet temperature and HCl concentration and NOx concentration.

FIG. 5 is a diagram showing changes over time in a furnace temperature, a furnace outlet temperature, a boiler two-pass temperature, and an evaporation amount (steam generation amount).

FIG. 6 is a diagram showing the relationship between the spray amount (slaked lime equivalent ratio) and the HCl removal rate.

FIG. 7 is a diagram showing the relationship between furnace outlet temperature and boiler outlet dioxin concentration.

FIG. 8 is a diagram showing the relationship between the amount of powdered activated carbon sprayed and the concentration of dioxin at the chimney inlet.

FIG. 9: Chimney inlet HCl obtained when carrying out the present invention.
FIG. 4 is a diagram showing a change over time of the NOx concentration and NOx concentration.

FIG. 10 shows a chimney inlet HC obtained when the conventional method is performed.
It is a figure which shows the time change of 1 and NOx density | concentration.

FIG. 11 is a block diagram showing an example of a conventional harmful component removing method.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 waste incinerator 2 boiler 3 cooling tower 4 bag filter 5 denitrification tower 6 chimney 11 exhaust gas flow rate detector 12 furnace outlet temperature detector 13 steam generation amount detector 14 combustion air amount detector 15 secondary air amount detector 16 Low calorific value detector 17 Chemical spray amount calculator 18 Slaked lime spray amount control device 19a Ammonia gas spray amount control device (for denitration tower) 19b Ammonia gas spray amount control device (for non-catalytic denitration device) 20 Activated carbon spray amount control device 21 CO ₂ concentration detector 22 O ₂ concentration detector 28 HCl concentration detector 29 NOx concentration detector 30 CO concentration detector

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 53/70 (72) Inventor Toru Shioman 1-2-1 Marunouchi, Chiyoda-ku, Tokyo In-house (72) Inventor Atsushi Hirayama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan In-house Pipe Co., Ltd. (72) Inventor Masaru Ayukawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo In Japan Pipe Co., Ltd. F-term (Reference) 4D002 AA02 AA12 AA19 AA21 AC04 BA02 BA03 BA04 BA13 BA14 CA01 CA11 CA13 DA02 DA05 DA07 DA12 DA41 DA57 EA02 GA01 GA02 GA04 GB01 GB02 GB03 GB06 GB12 GB20 HA02

Claims (14)

[Claims] 1. A method for removing harmful components contained in exhaust gas by spraying a chemical on exhaust gas discharged from a waste incinerator, wherein the harmful component concentration in the exhaust gas is constantly adjusted when the chemical is sprayed on the exhaust gas. Without detection, a) Exhaust gas flow rate after dust collection, b) Exhaust gas temperature upstream of exhaust gas cooling means by water spray, c) Amount of steam generated by steam type heat recovery means, d)
Combustion air quantity to the waste incinerator, e) secondary air amount to the waste incinerator, to) lower heating value of the incinerated, Doo) CO ₂ concentration in the exhaust gas after dust collection, h) O ₂ concentration in the exhaust gas after dust collection, using one or more of the estimates the harmful components of the processing target, in the exhaust gas and controlling the spray amount of the drug based on this How to remove harmful components. 2. The harmful component to be removed is HCl, SOx
In the case of an acidic component such as NOx or a nitrogen oxide such as NOx, the value of each of the above a) to g) exceeds each reference value, or the value of the above h) is below the reference value. In accordance with the degree, the spray amount of the corresponding drug is increased, and the value of each of the above (a) to (g) is lower than the respective reference value or the value of the above (h) is higher than the reference value. 2. The method for removing harmful components in exhaust gas according to claim 1, wherein the spray amount of the corresponding chemical is reduced according to the degree. 3. When the harmful component to be removed is an organic halogen compound such as dioxin,
If each value of g) is below each reference value or the value of h) exceeds the reference value, the spray amount of the corresponding drug is increased according to the degree, and 3. The method according to claim 1, wherein when the value of each of the above (1) is greater than each of the reference values or the value of (2) is below the reference value, the spray amount of the corresponding medicine is reduced according to the degree. The method for removing harmful components in exhaust gas according to claim 1. 4. The reference values of (a) to (h) are a rated value of an exhaust gas treatment facility, an average value during normal operation, a representative value when starting up the exhaust gas treatment facility, a representative value when changing operating conditions, The method for removing harmful components in exhaust gas according to claim 2 or 3, wherein the value is a value selected from the following. 5. A method for estimating the amount of a harmful component to be treated by using a plurality of the items (a) to (h), and when this value exceeds a reference value of the amount of the harmful component, the spraying amount of the medicine according to the degree. The harmful component removal in the exhaust gas according to any one of claims 2 to 4, wherein when the value is lower than the reference value, the spray amount of the medicine is reduced according to the degree. Method. 6. The reference value of the estimated amount of harmful components according to claim 5, wherein the rated value of the exhaust gas treatment facility, the average value during normal operation, the representative value at startup of the exhaust gas treatment facility, and changes in operating conditions A method for removing harmful components in exhaust gas, wherein the value is selected from representative values of time. 7. The method according to claim 1, wherein the drug is a calcium compound or a sodium compound, and is a powdery, liquid or slurry basic neutralizer.
The method for removing harmful components in exhaust gas according to any one of 2, 4, 5, and 6. 8. The method according to claim 1, wherein the chemical is one of ammonia gas, aqueous ammonia, and urea water, or an amine chemical that generates an ammonia gas.
The method for removing harmful components in exhaust gas according to any one of 2, 4, 5, and 6. 9. The method for removing harmful components in exhaust gas according to claim 1, wherein the chemical agent is a carbon-based porous powder. 10. A method of detecting the concentration of various harmful components after spraying a drug and controlling the amount of spraying the corresponding drug by feedback control in combination with the method according to any one of claims 1 to 9. A method for removing harmful components in exhaust gas. 11. An apparatus for spraying chemicals on exhaust gas discharged from a waste incinerator to remove harmful components contained in the exhaust gas, comprising: a) a) an exhaust gas flow rate after dust collection processing, and b) an exhaust gas by water spray. Exhaust gas temperature upstream of the cooling means, c) the amount of steam generated by the heat recovery means, d) the amount of combustion air to the waste incinerator, e) the amount of secondary air to the waste incinerator, and Low calorific value, g) CO ₂ concentration in exhaust gas after dust collection,
H) one or more continuous measuring instruments for measuring at least one of O ₂ concentration in the exhaust gas after the dust collection processing, and b) the measured value signals from the continuous measuring instruments are integrated to be processed. A medicine spray amount calculator for estimating a harmful component amount, calculating a medicine spray amount based on the harmful component amount, and transmitting a medicine spray amount signal to the medicine spray amount control device; c) a medicine spray amount signal from the medicine spray amount calculator. An exhaust gas treatment device, comprising: a medicine spray amount control device that receives a chemical spray and performs a medicine spray; and d) a harmful component removal device that removes a harmful component in exhaust gas by the chemical spray. 12. When using an agent for removing acidic components or organic halogen compounds in exhaust gas, the harmful component removing device is selected from a bag filter, a dry reaction tower, a semi-dry reaction tower, a wet washing tower, and a cooling tower. The exhaust gas treatment device according to claim 11, wherein the exhaust gas treatment device is at least one device. 13. When using a chemical for removing nitrogen oxides in exhaust gas, the harmful component removing device is a non-catalytic denitration device and / or a denitration tower installed in the incinerator or at the outlet of the incinerator. The exhaust gas treatment device according to claim 11, wherein 14. The exhaust gas treatment device according to claim 11, wherein a plurality of chemical spray amount control devices are provided.