KR20140036313A

KR20140036313A - Method for treating acidic gas

Info

Publication number: KR20140036313A
Application number: KR1020147001441A
Authority: KR
Inventors: 미쯔히로 마시코
Original assignee: 쿠리타 고교 가부시키가이샤
Priority date: 2011-07-14
Filing date: 2012-07-13
Publication date: 2014-03-25
Also published as: TW201306918A; CN103648616A; CN103648616B; MY163303A; TW201524584A; KR101528743B1; JP2013022471A; JP5720455B2; TWI565514B; WO2013008918A1; TWI608861B

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a stable acidic gas treatment with less peak generation of an acidic gas concentration at an outlet in a feedback form in which an expensive acidic gas measuring apparatus is not newly introduced, and to reduce excessive addition of an alkaline agent. The present invention relates to a method of treating acid gas by a new control method.
In the acid gas treatment method of the present invention, an alkali agent is added to a combustion exhaust gas containing an acid gas, and the amount of alkali agent added is determined based on a measurement signal of an acid gas concentration measuring instrument that measures the acid gas concentration after collecting dust. As a method for treating acidic gas to be controlled by feedback, a basic addition amount obtained by multiplying an average addition amount corresponding to at least an average time (for example, 1 hour to be described later) by a factor of 1 or less times (for example, 80% to be described later). And a step of calculating the added amount output value of the alkali chemicals based on the calculated basic addition amount based on the feedback calculation.

Description

Method for Treating Acidic Gas

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating harmful gases such as hydrogen chloride and sulfur oxides generated in combustion facilities such as municipal waste incinerators, industrial waste incinerators, power generation boilers, carbonization furnaces, and private plants. In detail, it is related with the method of controlling the addition amount of the alkali chemicals which process an acidic gas efficiently.

Exhaust gas containing harmful hydrogen chloride and sulfur oxides is treated with an alkaline agent such as slaked lime or baking soda, and after being dusted by a dust collector such as a bag filter (BF), it is discharged from the chimney. On the other hand, the fly ash collected by the dust collector contains harmful metals such as harmful Pb and Cd, and is disposed of after disposal of these harmful heavy metals.

Baking soda finely processed to 5-30 μm, which is an alkaline agent that treats acid gases, is more reactive than slaked lime, can stably process acid gases, and has less unreacted fractions. Since landfill disposal can be reduced, it is an effective means for reducing environmental load. In addition, as a heavy metal treatment method, diethyldithiocarbamic acid (diethyldithiocarbamic) A method of insolubilizing with a chelate such as acid salt) is common, and in the short term, the effect of fixing heavy metals is high, but heavy metals such as lead are reused due to a decrease in pH due to acid rain at the final disposal site and oxidative autolysis of chelate. Shipment remains a problem. On the other hand, the fixation of heavy metals by phosphoric acid compounds such as phosphoric acid changes to the form of hydroxyapatite, which is an inorganic mineral, and thus is excellent in long-term stability at the final disposal site and is a highly valuable treatment method from the viewpoint of environmental protection. Furthermore, the method of treating the fly ash treated with the above-mentioned finely baked baking soda with heavy metal fixatives such as phosphoric acid is an effective means having a lot of environmental load reduction effect.

By controlling the amount of alkali agent, such as slaked lime or baking soda, which treats acidic gases such as hydrogen chloride and sulfur oxide, not only can the cost of acidic gas treatment be reduced, but also the unreacted portion of the alkaline agent is reduced, and the fly ash is embedded. The effect of reducing the quantity can be expected.

The addition amount of the alkali agent which processes acidic gases, such as hydrogen chloride and sulfur oxides, is generally feedback-controlled by the PID control apparatus based on the HCl density | concentration measured by the ion-electrode-type hydrogen chloride measuring apparatus provided in the back of a bag filter. However, in a combustion facility such as an incineration plant, a device for measuring the concentration of acid gas at the inlet is usually not installed, and the control output is adjusted by setting a parameter of PID control without knowing the fluctuation of the inlet. However, PID controller has 5 setting items such as P, I, D, addition amount (output) lower limit and addition amount (output) upper limit, and the setting value of each item is combined to determine the control output value. It takes time. For this reason, in general, there are many facilities in which the setting by the PID controller performs a control in which the addition amount greatly increases when the control target value SV is exceeded.

However, the control output of a normal PID controller can only set a single upper limit. For example, when the control target value SV of the HCl concentration is set to 40 ppm, a single upper limit of the control output is set at a concentration of 40 ppm or more. An alkali agent is added as a limit and it becomes a cause of excessive addition of an alkali agent. In addition, the said feedback control is influenced by the measurement delay of an acidic gas measuring apparatus. The HCl concentration at the bag filter outlet is usually measured by an ion electrode method (for example, HL-36 manufactured by Kyoto Electronics Co., Ltd.), and the sulfur oxide concentration is measured by an infrared absorption method (for example, NSA-3080 manufactured by Shimadzu Corporation). Including the sampling time of the exhaust gas and the response time of the measuring instrument, there are many measurement delays of 5 to 10 minutes. This delay in measurement causes an lag of addition of the alkali agent, which leads to poor processing of the acidic gas and causes excessive addition of the alkali agent.

In order to solve this problem, various control methods are examined. In patent document 1, "P + PID control" which adds P to the normal PID control formula is proposed. This proposal considers the correspondence of the sudden generation | occurrence | production of the acidic gas which is difficult by normal PID control. Moreover, in patent documents 2 and 3, the feed forward control which determines the addition amount of an alkali chemical agent based on the acidic gas concentration of an inlet, and the feedback which supplements the addition amount of an alkali chemical agent based on the acidic gas concentration after an alkali agent is processed. A control scheme that combines control has been proposed. The present control method is expected to have an effect of suppressing excessive addition of feedback control, and it is considered that the effect of stabilizing an acidic gas and reducing an excessive addition of an alkaline agent can be obtained.

Japanese Patent Application Laid-Open No. 2002-113327 Japanese Patent Application Laid-Open No. 10-165752 Japanese Patent Laid-Open No. 2006-75758

However, in Patent Literature 1, although the sudden correspondence of the inlet is possible to some extent, since the upper limit value and the lower limit value of the control output are a single setting, in the facility where fluctuations in the inlet acid gas concentration fluctuate, the agent causes hunting. Stable treatment with a low peak of acid gas concentration is difficult. In addition, the measurement delay of the said measuring apparatus is not added, and it cannot respond to the processing failure of the acidic gas by the addition lag of the alkali agent by the measurement delay. Furthermore, in Patent Documents 2 and 3, most of the facilities that measure only the acid gas concentration at the outlet of combustion facilities such as incineration plants occupy the majority. In order to implement this control method, the acid gas concentration at the inlet is determined. It is necessary to further introduce an expensive acid gas measuring apparatus to be measured.

In view of the foregoing, the present invention provides a stable acidic gas treatment with less peak occurrence of the acidic gas concentration at the outlet in a feedback form in which no expensive acidic gas measuring apparatus needs to be introduced. It is an object of the present invention to provide an acidic gas treatment method by a novel control method for reducing the addition.

(1) Treatment of an acidic gas which adds an alkaline agent to the combustion exhaust gas containing an acidic gas and feedback-controls the addition amount of the alkaline agent on the basis of a measurement signal of an acidic gas concentration measuring instrument which measures the acidic gas concentration after collecting dust. It is a method, and the coefficient of 1 times or less to the average addition amount corresponding to at least an average time (for example, 5 minutes, 15 minutes, 30 minutes, 1 hour, 3 hours, 6 hours, etc. mentioned later) (for example, mentioned later) 95%, 90%, 80%, 70%, 50%, etc.) of the acidic gas having a step of calculating the basis addition amount and the step of calculating the addition amount output value of the alkali agent based on the calculated basis addition amount by a feedback operation Treatment method.

In PID control, which is mainly used at present, the additive output can be set to a single upper limit and a lower limit. Therefore, for example, when the control target value SV of the outlet HCl concentration is set to 40 ppm, when the actual outlet HCl concentration is 40 ppm or less, it is added as the lower limit of the control output to reduce the addition of the alkali chemicals, and the control target value SV ) At 40 ppm or more, improper addition of the alkali agent (overaddition, underaddition), which is repeated at the upper limit of the control output in order to increase the addition of the alkali agent, causes a large variation in the HCl concentration at the outlet and Cause.

On the other hand, as in the invention of (1), at least the basic addition amount obtained by multiplying the average addition amount corresponding to the average time by a factor of 1 or less is calculated, and the addition amount output value of the alkali chemicals is calculated by the feedback calculation based on the calculated basic addition amount. In this case, improper addition of the alkali agent can be prevented, and stable treatment with a small fluctuation in the outlet HCl concentration to be treated is possible, and the addition amount of the alkali agent can be reduced as a result of the appropriate addition according to the invention of (1).

The invention of (1) focuses on the past average addition amount as a factor related to the HCl concentration of the inlet, which has not been able to be added to the feedback control in the past, and utilizes the base addition amount obtained by multiplying the past average addition amount by a factor of 1 or less as a control factor. It is characterized by Thereby, the addition amount of the alkali agent is based on the basic addition amount which multiplied the coefficient of 1 times or less with the past average addition amount which is feasible as a base of the addition amount, without repeating the conventional lower limit and the upper limit repeatedly. For example, it calculates by feedback control, such as PID. Therefore, the fluctuation of the addition of the alkali agent is small, the hunting caused by the poor addition of the alkali agent itself (over addition, under addition) is suppressed, and the addition amount can be reduced by performing the appropriate addition, and the stable treatment of the acid gas with little fluctuation Becomes possible.

(2) In the step of calculating the addition amount output value by a feedback calculation, the acidity of (1) described in which the calculated basic addition amount is a lower limit value (eg, LO: addition amount lower limit described later) of the addition amount output value of the alkali chemicals. Method of processing gas.

According to the invention of (2), since the excess or deficiency of the addition amount is adjusted by the conventional feedback calculation based on this base addition amount by adjusting the base addition amount to the lower limit of the output amount of the addition amount, the addition of the alkaline agent is appropriate and acidic gas is removed. It can be processed efficiently.

Moreover, although the average time of an average addition amount does not have a restriction | limiting in particular, It is effective to utilize average values, such as a moving average of an addition amount, and it is preferable to utilize an average time about 5 minutes or more and about 15 to 24 hours. Moreover, 1 time or less may be sufficient as the coefficient prescribed | regulated by a basic addition amount. When a coefficient of 1 or more times is used, the stabilization treatment of the acidic gas is possible, but the addition is excessive since it prevents the decrease in the amount of addition accompanying the decrease of the inlet acidic gas concentration. The base addition amount may be 1 times or less (coefficient 100% or less) of the average addition amount, but is preferably 0.5 to 0.95 times (50 to 95%), particularly 0.7 to 0.9 times (70 to 90%).

(3) In the step of calculating the addition amount output value by a feedback calculation, the range of the slope of at least two acidic gas concentrations (for example, the six second average of the slope of the immediately adjacent HCl concentration described later is positive and negative). And the step of setting a control target value (for example, 180 ppm, 220 ppm, etc. in Example 8 described later) for each of the at least two inclination ranges; Calculating an addition amount output value of the alkali chemical agent based on at least the measurement signal and the control target value for each of the inclination ranges, and in the step of setting the control target value, when the inclination range of the acidic gas concentration is large (For example, the control target value set to the case where the 6 second average of the slope of the HCl concentration immediately adjacent to be described later is positive (at the time of increasing the acid gas concentration) is described above. (1) smaller than the control target value set in the case where the range of the slope of the acidic gas concentration is small (for example, when the 6 second average of the slope of the immediately adjacent HCl concentration described later is negative (when the acidic gas concentration falls)). Or (2) a method for treating an acidic gas as described above.

According to the invention of (3), when the range of the inclination of the acid gas concentration at the bag filter outlet is large (when the acid gas concentration rises), the control of the acid gas concentration is less than when the inclination range is small (when the acid gas concentration falls). Since the target value was made small, the alkali agent addition amount output value at the time of the acidic gas concentration rise can be made larger than the time of the acidic gas concentration fall. Therefore, the timing of adding the alkali agent at the time of increasing the acid gas concentration can be made faster than the current state control, and the poor processing of the acid gas due to the measurement delay of the acid gas measuring device can be improved.

On the contrary, since the amount of the alkali agent added to the acidic gas concentration drop can be made smaller than that of the acidic gas concentration rise, the amount of the alkaline agent added can be reduced quickly when the acidic gas concentration decreases, thereby reducing the excessive addition due to the measurement delay of the acidic gas measuring apparatus. can do.

(4) The step of calculating the addition amount output value by a feedback operation includes a lower limit value (eg, LO in FIGS. 12, 15 and 41 to be described later) and an upper limit value (example) calculated based on the measurement signal. For example, the acidic gas concentration (for example, the BF exit HCl concentration in FIGS. 12, 15 and 41 described later) between LH (upper limit of control output) in FIGS. 12, 15 and 41 described later. Correspondingly, the step of setting one or more new upper limit values (e.g., LM1 [output limit 1], LM2 [output limit 2] in FIGS. 12, 15, and 41 to be described later) corresponding to the added amount output value. The processing method of the acidic gas in any one of (1)-(3).

In the normal feedback operation, there is only one output upper limit, and when the acidic gas concentration becomes higher than the control target value, the alkali agent can be added up to the upper limit regardless of the magnitude of the acid gas concentration at the inlet, causing excessive addition.

On the other hand, according to the invention of (4), the addition of the limit of the control output corresponding to the current acid gas concentration between the lower limit value and the upper limit value of the addition amount output value, and the appropriate addition of the alkali agent according to the magnitude of the acid gas concentration It becomes possible, and the addition amount can be reduced.

(5) In the step of calculating the basic addition amount, the acidic gas according to any one of (1) to (4), wherein 0.5 to 0.95 times the average addition amount when the moving average time is 5 minutes or more. Treatment method.

As mentioned above, although the average time of an average addition amount does not have a restriction | limiting in particular, It is effective to utilize average values, such as a moving average of an addition amount, and it is preferable to use an average time about 5 minutes or more and about 15 to 24 hours. Moreover, 1 time or less may be sufficient as the coefficient prescribed | regulated by a basic addition amount. When a coefficient of 1 or more times is used, the stabilization treatment of the acidic gas is possible, but the addition is excessive since it prevents the decrease in the amount of addition accompanying the decrease of the inlet acidic gas concentration. The base addition amount may be 1 times or less (coefficient 100% or less) of the average addition amount, but is preferably 0.5 to 0.95 times (50 to 95%), particularly 0.7 to 0.9 times (70 to 90%).

Therefore, according to the invention of (5), it is possible to prevent the addition of the alkali agent while performing the stabilization treatment of the acidic gas.

(6) The step of calculating the addition amount output value by a feedback operation calculates the addition amount output value of the alkali chemicals using the output of the control output calculated from the hydrogen chloride concentration and the control output calculated from the sulfur oxide concentration in addition to the feedback operation. The processing method of the acidic gas in any one of (1)-(5) containing the process further.

In industrial waste incinerators and combustion plants of private factories, hydrogen chloride and sulfur oxides are often generated at high concentrations. At this time, both hydrogen chloride and sulfur oxide are subject to treatment, and a control output obtained based on the hydrogen chloride concentration of the hydrogen chloride concentration measuring device installed at the rear of the bag filter and a control output obtained based on the sulfur oxide concentration are given, for example. By the addition, two acid gases of hydrogen chloride and sulfur oxide can be treated stably.

Therefore, according to the invention of (6), two acid gases of hydrogen chloride and sulfur oxide can be treated stably.

(7) The step of calculating the addition amount output value by a feedback operation,

The method for treating acidic gas according to any one of (1) to (6), further comprising the step of calculating the amount of output of the alkali agent based on the average value of the hydrogen chloride concentration and / or the sulfur oxide concentration in addition to the feedback calculation.

By the way, there exists a facility which manages discharge | emission density | concentration of acidic gas by the 1 hour average value of each acidic gas concentration (hydrogen chloride concentration, sulfur oxide concentration). Generally, although the control target value SV is provided and controlled, there exists a case where the control target value is a target to the last, and the control target value becomes a density | concentration exceeding a target value. In particular, since the addition amount reduction and the acidic gas stabilization treatment are contrary to each other, if the addition amount reduction is required, the risk of the one hour average value exceeding the management value is increased. In this case, when the concentration of the acidic gas reaches a concentration equal to or higher than the average management value for 1 hour or close to it, by adding a large amount of alkaline agent (which defines a certain amount of addition), the addition amount reduction and the stabilization treatment of the acidic gas are achieved. Compatible safety can be achieved.

Therefore, according to the invention of (7), since the amount of output of the alkali agent is calculated on the basis of the average value of the hydrogen chloride concentration and / or the sulfur oxide concentration, it is possible to control with high safety that both the addition amount reduction and the stabilization treatment of the acidic gas are compatible. Become.

(8) The processing method of the acidic gas in any one of (1)-(7) whose said alkali chemicals is the fine powder baking soda of 5-30 micrometers of average particle diameters.

There is no particular limitation on the alkali agent used in the present invention. The finely divided baking soda in which the average particle diameter of the reaction with the acidic gas is rapidly adjusted to 5 to 30 µm, in particular, has good control response and can effectively exhibit the performance of the control method of the present invention. In addition, slaked lime is also applicable. In this case, the JIS-specialized calcination circuit is also applicable, but the use of the high specific surface area calcined lime having a specific surface area of high reactivity with acidic gas, for example, 30 m ² / g or more can achieve the performance of the present invention.

(9) The processing method of the acidic gas of the description of (8) which uses together the alkaline agent other than the said fine baking soda.

There is no restriction | limiting in particular as an alkali chemicals which exhibits the effect of this invention. Examples of alkali agents other than finely baked baking soda include hydrated lime, sodium carbonate, potassium hydrogen carbonate, potassium carbonate, cesky sodium carbonate, natural soda, sodium hydroxide, potassium hydroxide, magnesium oxide, magnesium hydroxide and the like. In the case where the alkali agent is powder, a fine particle having a high reactivity with acidic gas having a particle diameter of less than 30 µm, particularly 5 to 20 µm, is preferable. Agent which adjusted particle size beforehand

) May be applied, or an crushing facility may be provided locally, and an alkali agent having a poor particle size may be added while pulverizing locally. Moreover, it can also implement in the slurry or aqueous solution which melt | dissolved each alkali chemicals in water.

(10) The other alkali agent is acidic according to (9), which is at least one alkali agent selected from the group consisting of slaked lime, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, sesqui carbonate sodium, natural soda, and faulty baking soda. Method of processing gas.

It is also an economically effective means to use an inexpensive alkali agent different from the alkali agent which performs control by this invention. Although there is no restriction | limiting in particular for alkali used together, As an inexpensive alkali agent generally used, hydrated lime, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, cesky sodium carbonate, natural soda, fine baking soda can be illustrated.

According to the present invention, in the feedback form in which no expensive acid gas measuring device needs to be introduced, the stable acid gas treatment with less peak generation of the acid gas concentration at the outlet is performed and the excessive addition of the alkali agent is reduced. It is possible to provide an acid gas treatment method by a new control method for the same.

Fig. 1 is a block diagram showing the configuration of an acid gas treatment system 1 in which fine powder baking soda is added to HCl which is exhaust gas in an incineration plant.
2 is a basic configuration diagram of a simulation reaction system.
3 is a graph showing the relationship between the addition amount of finely baked baking soda and the HCl removal rate in the exhaust gas reaction.
4 is a graph showing the relationship between the addition amount of finely baked baking soda and the HCl removal rate in the bag filter phase reaction.
5 is a graph showing the behavior of the inlet HCl concentration.
6 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration according to the actual device examination results.
7 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration of the simulation examination result.
8 is a table showing the amounts of alkali chemicals added per Comparative Example and Examples of simulation examination results.
9 is a graph showing the behavior of the inlet HCl concentration.
10 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Comparative Example 1. FIG.
11 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 1. FIG.
12 is a control setting table of the step control method in Comparative Examples 2, 2 and 20. FIG.
13 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Comparative Example 2. FIG.
14 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 2. FIG.
15 is a control setting table of the step control method in Comparative Example 3, Example 3, 9, 10, 11, 17, 18, 21 and 22. FIG.
FIG. 16 is a graph showing the behavior of the amount of finely baked baking soda, the inlet HCl concentration and the outlet HCl concentration in Comparative Example 3. FIG.
17 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 3. FIG.
18 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 4. FIG.
19 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 5. FIG.
20 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 6. FIG.
21 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 7. FIG.
22 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 8. FIG.
23 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 9. FIG.
24 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 10. FIG.
25 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 11. FIG.
26 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 12. FIG.
27 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 13. FIG.
28 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 14. FIG.
29 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 15. FIG.
30 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 16. FIG.
31 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 17. FIG.
32 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 18. FIG.
33 is a graph showing the behavior of the amount of finely baked baking soda, the inlet HCl concentration and the outlet HCl concentration in Comparative Example 4. FIG.
34 is a graph showing the behavior of the amount of finely baked baking soda and the outlet HCl concentration in Example 19. FIG.
35 is a graph showing the behavior of the amount of finely baked baking soda, inlet HCl concentration and outlet HCl concentration in Example 20. FIG.
36 is a graph showing the behavior of the amount of finely baked baking soda, the inlet HCl concentration and the outlet HCl concentration in Example 21;
37 is a graph showing the behavior of the amount of finely baked baking soda, inlet HCl concentration, and outlet HCl concentration in Example 22;
FIG. 38 is a block diagram showing the configuration of an acid gas treatment system 2 in which fine baking soda is added to HCl which is exhaust gas in an incineration plant.
39 is a table which shows the comparative example of the actual apparatus examination result, the addition amount of alkali chemicals, etc. for every Example.
40 is a graph showing the behavior of the amount of finely baked baking soda, the inlet HCl concentration and the outlet HCl concentration in Comparative Example 5. FIG.
41 is a control setting table of the step control method in Comparative Example 6, Example 23, and 24;
FIG. 42 is a graph showing the behavior of the amount of finely baked baking soda, the inlet HCl concentration and the outlet HCl concentration in Comparative Example 6. FIG.
FIG. 43 is a graph showing the behavior of the amount of finely baked baking soda, inlet HCl concentration and outlet HCl concentration in Example 23; FIG.
FIG. 44 is a graph showing the behavior of the amount of finely baked baking soda, inlet HCl concentration and outlet HCl concentration in Example 24; FIG.

Although an Example is given to the following and this invention is demonstrated further more concretely, this invention is not limited to this.

FIG. 1 is a block diagram showing the configuration of an acidic gas treatment system 1 in which fine powder baking soda is added to HCl which is exhaust gas in an incineration facility.

The acidic gas processing system 1 is comprised of the control apparatus 11, the fine powder baking soda addition apparatus 12, the bag filter 13, and the HCl concentration measuring apparatus 14. As shown in FIG. The controller 11 controls the addition amount output of the differential baking soda based on the HCl concentration measurement signal transmitted from the HCl concentration measuring device 14 and the basic addition amount calculated from the past average addition amount (PID control method or step). Method). The fine powder baking soda addition apparatus 12 adds fine powder baking soda to HCl in waste gas based on the output value of the addition amount of the fine powder baking soda calculated by the control apparatus 11.

In addition, the basis addition amount is computed by multiplying the coefficient of 1 times or less with the past average addition amount corresponding to average time (for example, moving average time).

The bag filter 13 removes dust after reaction of HCl in exhaust gas and fine baking soda. The HCl concentration measuring device 14 includes the finely baked baking soda accumulated on the bag filter 13 (the finely baked baking soda is accumulated on the bag filter 13 by the reaction with HCl in the exhaust gas) and the exhaust gas. The HCl concentration (back bag outlet outlet HCl concentration described later) after the reaction of HCl after the reaction is measured, and the HCl concentration measurement signal is transmitted to the controller 11.

The acidic gas processing system 1 repeats these cycles and performs feedback control, and the control apparatus 11 performs control which makes appropriate the control output value of the amount of fine baking soda addition.

In addition, the HCl concentration measuring device 14 is, for example, an ion electrode type HCl concentration measuring device.

In addition, as shown in FIG. 1, the HCl concentration measuring device (HCl concentration measuring device H) after measuring the differential baking soda accumulated on the bag filter 13 and the HCl after the exhaust gas reaction (the bag filter outlet HCl concentration described later) ( 14) is preferably installed. This is because the finely divided baking soda remaining by the reaction with HCl in the exhaust gas accumulates on the bag filter 13, and the accumulated finely divided baking soda reacts with HCl after the exhaust gas reaction, thereby more accurately measuring the HCl concentration. Because you can.

Moreover, the control apparatus 11 performs feedback control as a lower limit (for example, LO: addition amount lower limit mentioned later) of the calculated basic addition amount as the addition amount output value of fine baking soda.

Therefore, since the excess or deficiency of the addition amount is adjusted by the conventional feedback calculation based on this basic addition amount, addition of an alkali chemicals is moderated and an acidic gas can be processed efficiently.

Furthermore, the control apparatus 11 provides two ranges in which the slope of HCl concentration (time change rate of concentration) is a positive range and a negative range. Then, the control target value of the HCl concentration is set for each of these two ranges.

Here, the setting of the control target value of the HCl concentration may be set so that the control target value provided for the positive range of the gradient of the HCl concentration is smaller than the control target value for the negative range. By doing in this way, the amount of the finely divided baking soda added at the time of increasing the HCl concentration can be made larger than at the time of decreasing the HCl concentration. On the contrary, the amount of finely baked baking soda at the time of decreasing the HCl concentration can be made smaller than at the time of increasing the HCl concentration. Therefore, the addition output of the differential baking soda by a feedback calculation can be performed beforehand, and the influence by a measurement delay can be further reduced.

Moreover, the control apparatus 11 may perform feedback control by a step system. Here, the step method is a control method for setting stepwise the control output corresponding to the HCl concentration. Specifically, in addition to the upper limit of the control output value set in the PID control system, a new upper limit of the control output value is set corresponding to the HCl concentration.

Here, there is only one output upper limit in normal PID control, and when acidic gas becomes more than a control target value, alkali chemicals can be added to an upper limit irrespective of the magnitude | size of acidic gas concentration, and it causes excessive addition. Thus, by adopting a step control method, by adding a new control output upper limit corresponding to the current HCl concentration between the lower limit value and the upper limit value of the addition amount output value, an appropriate addition of the differential baking soda according to the magnitude of the HCl concentration is achieved. It becomes possible, and suppression of the addition of the addition amount becomes possible.

Furthermore, a new control output upper limit value (e.g., LM1 [output limit 1] and LM2 [output limit 2] in FIGS. 12, 15 and 41 described later) is set corresponding to the HCl concentration, but the new higher the HCl concentration is set. The control output upper limit is also set high. However, in order to suppress the excessive addition of an alkali chemicals, it is set as a value smaller than the upper limit of the control output value set by PID control system (for example, LH [the upper limit of control output of FIGS. 12, 15, 41 mentioned later]). It is preferable.

The acidic gas measuring apparatus used in this embodiment can be implemented irrespective of a measuring system. The hydrogen chloride concentration can be measured by an ion electrode method, a single absorption line absorption spectroscopy with a laser, or the like, and the sulfur oxide can be measured by an infrared absorption method, an ultraviolet fluorescence method, or the like. In addition, in this embodiment, since the improvement effect can be obtained by utilizing the reasonable base addition amount which was not added in the conventional feedback control, the effect of this invention can be acquired regardless of a measurement delay speed.

Hydrogen chloride and sulfur oxide are often produced in high concentration about industrial waste incinerator and combustion facility of private factory. At this time, both hydrogen chloride and sulfur oxide are subject to treatment, and in the control method based on the control output and sulfur oxide concentration obtained in the control method based on the hydrogen chloride concentration of the hydrogen chloride concentration measuring device installed at the rear of the bag filter. By adding, for example, the obtained control output, it is possible to stably treat two acid gases, hydrogen chloride and sulfur oxide.

Furthermore, there is a facility that manages the emission concentration of acidic gas as an hourly average value of each acidic gas concentration (hydrogen chloride and sulfur oxide concentration). Generally, although the control target value SV is provided and controlled, there exists a case where the control target value is a target to the last, and the control target value becomes a density | concentration exceeding a target value. In particular, since the addition amount reduction and the acidic gas stabilization treatment are contrary to each other, if the addition amount reduction is required, the risk of the one hour average value exceeding the management value is increased. In this case, it is safe that addition amount reduction and stabilization treatment of acidic gas are compatible by adding a large amount of alkali chemicals (prescribed constant amount of addition) when it reaches more than one hour average management value or near this level Higher control is possible.

The alkali agent used in the present embodiment is not particularly limited. In particular, the finely divided baking soda having an average particle diameter of 5 to 30 µm with rapid reaction with an acidic gas has good control responsiveness and can effectively exhibit the performance of the present control method. Moreover, although slaked lime is possible also with JIS-specialized slaked lime, using the slaked lime of the high specific surface area which is 30 m <2> / g or more, for example, the specific surface area which is highly reactive with acidic gas can exhibit the performance of this invention. Examples of alkali agents other than the above include sodium carbonate, potassium hydrogen carbonate, potassium carbonate, cesky sodium carbonate, natural soda, sodium hydroxide, potassium hydroxide, magnesium oxide, magnesium hydroxide and the like.

In the case where the alkali agent is powder, a fine particle having a high reactivity with acidic gas having a particle diameter of less than 30 µm, particularly 5 to 20 µm, is preferable. You may apply the agent which adjusted the particle diameter previously, and you may provide a grinding | pulverization facility in the field, and may add the alkali agent with a grain size, grinding | pulverizing locally. Moreover, it can also implement in the slurry or aqueous solution which melt | dissolved each alkali chemicals in water.

Furthermore, using an inexpensive alkaline agent different from the alkali agent which performs control by this embodiment also becomes an economically effective means. Although there is no restriction | limiting in the alkaline agent used together, As an inexpensive alkali agent generally used, hydrated lime, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, cesky carbonate, natural soda, and fine baking soda can be illustrated.

[Example]

The simulation reaction system will be described.

[Simulation reaction system]: Complex reaction in exhaust gas and bag filter

The simulation reaction system consisted of two reactions of the reaction between the finely-baked soda and hydrogen chloride (HCL) in the exhaust gas at an instant and the unreacted finely-baked soda and HCL accumulated on the bag filter (see FIG. 2). In addition, the residence time of the collection material in a bag filter is about 2 hours normally. Therefore, in this simulation, the differential baking soda on the bag filter was set to extinguish in the prescribed time (set to about 2 hours).

With reference to FIG. 2, the basic structure of a simulation reaction system is demonstrated.

First, in chemical injection (drug injection) control in an incineration facility, the amount of chemicals added (based on the HCl concentration (after processing) signal of an ion electrode type HCl concentration measurement instrument installed at the bag filter outlet) is calculated by a control equation such as PID ( The amount of finely baked baking soda (Ag) is determined (formula (1) below), and the amount of finely charged baking soda (acid gas treating agent) determined is added to the exhaust gas (inlet HCl concentration Hi). The finely divided baking soda added to the fire passage reacts with an acidic gas such as HCl in the exhaust gas to remove HCl in the exhaust gas.

Ag = Ag1 + LO (1)

Ag: amount of finely baked baking soda [kg / h]

Ag1: The addition amount [kg / h] prescribed from the output of the HCl concentration measuring instrument (for the step method, see FIGS. 12, 15 and 41).

LO: Lower limit of addition amount [kg / h]

Normally (when not applying the basic addition amount according to the present invention), the LO set in advance is used.

When applying the base addition amount which concerns on this invention, an output is computed by the base addition amount which multiplied LO by the moving coefficient addition amount of predetermined time, and a predetermined coefficient.

In addition, the HCl removal rate of the inlet HCl concentration by the fine powder baking soda is the relationship between the exhaust gas reaction fine powder baking soda addition equivalent (Jg) and the exhaust gas reaction HCl removal rate (αg) from the application knowledge of our fine powder baking soda (FIG. 3). And the test calculation from the relationship between the equivalent of the back filter phase reaction finely baked baking soda (Js) and the HCl removal rate (? S) of the bag filter phase reaction (Fig. 4). In addition, reaction of HCl and fine baking soda was made into the instant. First, the HCl concentration (Hg) after the reaction in the exhaust gas is derived by the equivalent baking soda addition equivalent (Jg) and the exhaust gas reaction HCl removal rate (αg) of the exhaust gas reaction (Equation (2) as follows). In addition, the fine baking soda addition equivalent (Jg) of exhaust gas reaction is computed by following formula (3).

Hg = Hi × (1-αg ÷ 100) (2)

Hi: Inlet HCl concentration (ppm)

Hg: HCl concentration after exhaust gas reaction (ppm)

αg: HCl removal rate (%) in exhaust gas reaction

[Set from Relationship between Exhaust Gas Reaction Differential Baking Soda Added Equivalent and HCl Removal Rate (Fig. 3)]

Jg = Ag ÷ {Hi ÷ 0.614 ÷ 1000 ÷ M1 × M2 × F ÷ 1000} (3)

Jg: Exhaust gas reaction finely added baking soda equivalent

Ag: amount of finely baked baking soda (kg / h)

Hi: Inlet HCl concentration (ppm)

M1: HCl molecular weight [set to 36.5]

M2: baking soda molecular weight [set to 84]

F: Exhaust gas amount (Nm3 / h) [set to 55,000 N㎥ / h]

In addition, the fine baking soda which remained by the exhaust gas reaction accumulates on a bag filter at any time. The finely divided baking soda accumulated on the BF reacts with HCl after the exhaust gas reaction to determine the HCl concentration Ho at the outlet of the bag filter. At this time, the amount of finely divided baking soda (B) stored in the BF phase was subtracted from the finely baked baking soda reacted with HCl on the BF from the finely baked baking soda accumulated in the exhaust gas reaction. In addition, the bag filter is derived from the amount of fine powder baking soda (As) accumulated in the bag filter and the amount of fine powder baking soda added in the bag filter (Hs) after the exhaust gas reaction (Equation (5) as shown below). The HCl removal rate (αs) in the phase was determined to determine the HCl concentration (Ho) at the outlet of the bag filter (Equation (4) as follows).

Ho = Hg × (1-αs ÷ 100) (4)

Hg: HCl concentration after exhaust gas reaction (ppm)

Ho: HCl concentration in the bag filter outlet (ppm)

αs: HCl removal rate (%) of the reaction on the bag filter

[Set from Relationship between Addition of Powdered Baking Soda Added to Bag Filter and HCl Removal Rate (Fig. 4)]

Js = As ÷ {Hg ÷ 0.614 ÷ 1000 ÷ M1 × M2 × F ÷ 1000} (5)

Js: Addition of finely baked baking soda on bag filter

As: amount of finely baked baking soda on the bag filter (kg / h)

Hg: HCl concentration after exhaust gas reaction (ppm)

M1: HCl molecular weight [set to 36.5]

M2: baking soda molecular weight [set to 84]

F: Exhaust gas amount (N㎥ / h) [Set to 55,000 N㎥ / h]

As = Zn ÷ Ts × 3600 (6)

Zn: Accumulated baking soda in bag filter (kg)

Ts: unit simulation time (= data sampling time) (sec)

[0.5 sec setting]

Zn = Ｚ _{ｎ '} × (1-2.3 ÷ T4 × Ts) (7)

_{Ｎｎ '} : unreacted finely divided baking soda (kg)

T4: 90% decay relaxation time (sec)

[7,200 sec setting]

Ts: unit simulation time (= data sampling time) (sec)

[0.5 sec setting]

Ｚ _{n '=} (Ag ÷ 3600 x Ts-Rg) + (Ｚ _nn-1 -Rs) (8)

Ag: amount of finely baked baking soda (kg / h)

Ts: unit simulation time (= data sampling time) (sec)

[0.5 sec setting]

Rg: Reaction amount of baking soda in exhaust gas reaction (kg / h)

Ｎｎ _-1 : Accumulated baking soda in the bag filter before Ts (Sec) (kg)

Rs: Baking soda reaction amount in bag filter phase reaction (kg / h)

Rg = (Hi ÷ 0.614 ÷ 1000 ÷ M1 × M2 × F ÷ 1000) ÷ 3600 × Ts × αg ÷ 100 (9)

Hi: Inlet HCl concentration (ppm)

M1: HCl molecular weight [set to 36.5]

M2: baking soda molecular weight [set to 84]

F: Exhaust gas amount (N㎥ / h) [Set to 55,000 N㎥ / h]

αg: HCl removal rate (%) in exhaust gas reaction

Rs = (Hg ÷ 0.614 ÷ 1000 ÷ M1 × M2 × F ÷ 1000) ÷ 3600 × Ts × αs ÷ 100 (10)

Hg: HCl concentration after exhaust gas reaction (ppm)

M1: HCl molecular weight [set to 36.5]

M2: baking soda molecular weight [set to 84]

F: Exhaust amount (Nm3 / h) [set to 55,000 Nm3 / h]

αs: HCl removal rate (%) of the reaction on the bag filter

The HCl concentration at the outlet of the bag filter after the present reaction is measured by an ion electrode-type HCl concentration measuring instrument 14. By the way, in the ion electrode type HCl concentration measuring device 14, the delay time T1 by the facility, the measurement delay time T2α by the exhaust gas sampling, and the measurement delay time T2β by the measurement of the ion electrode type, Response time), resulting in a control delay specific to the feedback.

Therefore, the delay time T of the HCl concentration measuring apparatus 14 of this simulation was made into the sum of the delay time T1 by a facility, and the measurement delay time T2 of the HCl concentration measuring apparatus 14 (the following formula). (11)). In addition, the measurement delay time T2 of the HCl concentration measuring device 14 includes the measurement delay time T2α for sampling the exhaust gas after HCl treatment from the fire passage and the measurement delay time (T2β) of the ion electrode type HCl concentration measuring device T2β. Response time) was set and these were summed (the following formula (12)). In general, the 90% response time (measurement delay) of the ion electrode type used is T2β (Equation (13) below) because diffusion of HCl gas into the absorption liquid is affected. In this simulation, the long ion electrode formula of the measurement delay time is 600 seconds in total, T1 = 30 seconds, T2α = 390 seconds (210 seconds sampling delay + 180 seconds scrubbing pass delay delay), and T2β = 180 seconds from the actual equipment facility. (10 minutes: T1 = 0.5 minutes, T2 = 9.5 minutes).

In addition, when using the HCl density | concentration measuring apparatus whose measurement delay time is shorter than an ion electrode type | formula, the measurement delay time was changed and the behavior was confirmed.

[HCl concentration measuring instrument (simulating low speed response, ion electrode type)]

T = T1 + T2 (11)

T: delay time (sec) of the simulation reaction system of the HCl concentration measuring instrument

T1: Delay time in facility (sec) [30 sec setting]

T2: measurement delay time (sec) of HCl concentration measuring instrument

T2 = T2α + T2β (12)

T2α: Exhaust gas sampling time (sec) of HCl concentration measuring instrument

[390 sec settings]

T2β: 90% response time (sec) of HCl concentration measuring instrument [180 sec setting]

T2β = 2.3 × τ (13)

Yn = Ｙ _n-1 + (Xn-Ｙ _n-1 ) ÷ τ × Ts (14)

τ: relaxation time (sec)

Ts: unit simulation time (= data sampling time) (sec)

[0.5 sec setting]

Xn: current measuring instrument input HCl concentration (ppm)

Yn: current measuring instrument output HCl concentration in ppm

Ｙｎ _-1 : Measurement device output HCl concentration (ppm) of the previous time (before Ts (sec))

In addition, the addition amount of the alkaline agent which processes an acidic gas is prescribed | regulated based on the addition output calculated | required by the feedback calculated by the test based on the density | concentration measured with the HCl measuring apparatus (the said Formula (1)). The basic addition amount which concerns on this invention computed the moving average addition amount x coefficient (1 time or less) as a lower limit of feedback control.

In addition, as shown in FIG. 5, using the inlet HCl concentration fluctuating, the exhaust gas reaction and the HCl generation situation (FIG. 6) and the results of this simulation reaction system (FIG. 7) in the actual apparatus and The reaction efficiency with HCl of the BF phase reaction was set. This examination result is shown in FIG. 6 and FIG. For this facility, the HCl removal efficiency of the exhaust gas was 80% and the removal efficiency of the BF phase reaction was 65%, and the behavior of the actual device and simulation matched (FIGS. 6 and 7). Therefore, the following simulation was performed on this condition. In addition, in this simulation, in order to make the control responsiveness by a control method clear, it implemented using the inlet HCl density | concentration (Hi) of the time zone with comparatively large fluctuation | variation.

Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to this.

In the following Examples, the simulation reaction system was produced from the actual device examination results, and the control results according to the respective control methods were examined. In addition, since there was a condition (3 hours, 6 hours) where the average time of the average addition amount in a base addition amount was long, it evaluated by the result at the time of 6-9 hours using inlet HCl concentration repeatedly.

[ Comparative Example One]

Using the inlet HCl concentration shown in FIG. 9, the PID control method "P (proportional gain) = 100%, I = based on the HCl concentration measured by the HCl measuring device (measuring instrument measurement delay time meter 9.5 minutes) in the said simulation. 0. 1 second, D = 0. In 1 second, the addition amount output lower limit 200 kg / h and the addition amount output upper limit 480 kg / h "set the control target value (SV) of outlet HCl concentration to 200 ppm, and feedback control was performed.

The amount of finely baked baking soda and the bag filter outlet HCl concentration (average, 1 hour average maximum, instantaneous maximum, 1 hour average minimum, instantaneous minimum) after treatment with the differential baking soda are shown in FIG. 8. In addition, the behavior of the amount of finely baked baking soda and the bag filter outlet HCl concentration at the time of this control is shown in FIG.

The maximum of 1 hour average value of outlet HCl density | concentration used well as discharge | control management value of acidic gas was 212 ppm, and the instantaneous maximum was 384 ppm.

[ Example One]

30 minutes moving average addition amount (kg / h) was multiplied by a factor of 80%, and it was made into the basic addition amount, and it computed and feedback-controlled on the same setting conditions shown in the comparative example 1 except having utilized as an addition amount output lower limit.

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. In addition, the behavior of the amount of finely baked baking soda and the bag filter outlet HCl concentration at the time of this control is shown in FIG.

According to Example 1, the maximum value of HCl at an average value of 1 hour was 189 ppm, and the instantaneous maximum was 309 ppm and the acid gas treatment performance was improved compared with Comparative Example 1, and the addition amount was also reduced from 330 kg / h to 315 kg / h. It became.

Here, the outline | summary of a step control system is demonstrated. In Comparative Examples 2, 3 and 6, and Examples 2, 3, 9 to 11, 17, 18 and 20 to 24, the control by the step control method is performed instead of the PID control method.

Unlike the PID control method, the step method is a control method for defining the output step by step according to the HCl concentration of the outlet. Referring to Comparative Example 2, Examples 2 and 20 (FIG. 12), the HCl concentration outputs the control output step by step between the LO and LM1 between the SV control target value (control output starting concentration (more than the output lower limit)) to SM1. The control output set to LM2 was output between H1 and SM2 between SM1 and SM2, and the LH (upper limit of control output) was outputted above SM2. In addition, in the normal PID control type, there is no output limitation, only the setting of LO and LH. In addition, correction of the table for determining the HCl concentration and control output used in the control operation by the HCl slope is performed by SVA1 and SVA2. When the HCl slope is positive, SVA1 is subtracted from the HCl concentration used in the calculation, and the HCl slope is negative. At that time, SVA2 was added to the HCl concentration used in the calculation. As a result, the control output calculated when the same HCl concentration is input is such that the control output value when the value of the HCl slope is large (the acid gas concentration tends to increase) becomes larger than the control output value when the value of the HCl slope is small. It was.

In addition, the amount of finely divided baking soda (Ag) can be calculated | required by said formula (1).

[ Comparative Example 2]

Based on the HCl concentration measured by the HCl measuring device (measurement measuring time delay of 9.5 minutes) in the above simulation, the control target value (in this method, the concentration at which the control output of the alkaline agent is added above the output lower limit is defined as SV). Feedback control (see Fig. 12).

The maximum value of the 1-hour average value of the outlet HCl concentration by the step method was 212 ppm, and the instantaneous maximum was 383 ppm.

[ Example 2]

It computed and feedback-controlled on the same setting conditions of the step system shown in the comparative example 2 except having used the 30-minute moving average addition amount (kg / h) by multiplying the coefficient of 80%, making it a basic addition amount, and using as a lower limit of the addition amount output.

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. In addition, the behavior of the amount of finely baked baking soda and the concentration of the bag filter outlet HCl at the time of this control is shown in FIG.

According to Example 2, also in the step method, the maximum value of the hourly average value of the outlet HCl concentration was 195 ppm, the instantaneous maximum was 320 ppm and the acid gas treatment performance was improved compared to Comparative Example 2, and the addition amount was 295 kg / h. From 289 kg / h.

[ Comparative Example 3]

The control target value (SV) when the 6-second average of the slope of the immediately adjacent HCl concentration is positive in the step method control based on the HCl concentration measured by the HCl measuring instrument (measuring instrument measurement delay time 9.5 minutes) in the simulation. Is 180 ppm (SV-20 ppm), and if the 6 second average of the slope of the HCl concentration next to is negative, the control target (SV) is 220 ppm (SV + 20 ppm) and feedback control (see FIG. 15). It was.

In addition to this step method, the maximum value of the 1-hour average value of the exit HCl density | concentration by this feedback control which changed the control target value by the gradient of HCl density | concentration (henceforth SV change) was 216 ppm, and the instantaneous maximum was 381 ppm.

[ Example 3]

30 minutes moving average addition amount (kg / h) was multiplied by a factor of 80%, and it was made into the basic addition amount, and it computed and feedback-controlled on the same setting conditions of the feedback form shown in the comparative example 3 except having utilized as an addition amount output lower limit.

According to Example 3, the maximum value of the hourly average value of the outlet HCl concentration in the feedback method is 198 ppm, the instantaneous maximum is 283 ppm and the acid gas treatment performance is improved compared to Comparative Example 3, and the addition amount is also from 301 kg / h. Reduced to 289 kg / h.

[ Example 4 ~ 8]

Moving average addition amount which changed the average time (kg / h) [Example 4: 5 minutes, Example 5: 15 minutes, Example 6: 1 hour, Example 7: 3 hours, Example 8: 6 hours] 80 The feedback control was performed by calculating on the same setting conditions shown in Comparative Example 1 except that the coefficient of% was multiplied to make the base addition amount and utilized as the addition amount output lower limit.

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. In addition, the behavior of the amount of fine baking soda added and the bag filter outlet HCl concentration at the time of this control is shown to FIGS. 18-22.

According to Examples 4-8, the stabilization process of acidic gas is attained by using the basic addition amount which multiplied the average addition amount by 1 time or less as a factor of feedback control, and calculating the addition amount of an alkali chemicals.

The effect of Examples 4-8 is obtained by utilizing the factor of average addition amount as a feedback, and there is no restriction | limiting in particular in average time. In an average amount of addition time of 5 minutes (Example 4), a stable treatment effect of 186 ppm at an outlet HCl concentration maximum of 1 hour and a maximum of 369 ppm at an instant can be obtained with an equivalent addition amount.

Moreover, even in the average amount of addition time 6 hours (Example 8), the maximum 1 hour average value of the outlet HCl concentration was 194 ppm, the instantaneous maximum of 308 ppm, and the addition amount was also reduced to 311 kg / h. . 5 minutes or more are preferable and, as for the average time of addition amount, 15 minutes-6 hours are especially preferable.

[ Example 9-11]

Moving average addition amount (kg / h) which changed the average time (Example 9: 15 minutes, Example 10: 1 hour, Example 11: 3 hours) multiplied by a factor of 80%, and made it as a basic addition amount, and the addition amount output lower limit Except as utilized as the above, calculation was performed under the same setting conditions shown in Comparative Example 3 to control feedback.

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. In addition, the behavior of the amount of finely baked baking soda and the bag filter outlet HCl concentration at the time of this control is shown to FIGS. 23-25.

According to Examples 9-11 when the addition amount average time in feedback control by a step + SV change system was changed into 15 minutes-3 hours, the acidic gas stabilization treatment effect and the addition amount reduction effect were made irrespective of the addition amount average time. You can get it. This system is a control system which is especially excellent in the addition amount of 288-292 kg / h, and the addition amount reduction effect.

[ Example 12-16]

The coefficient multiplied by the 1 hour moving average addition amount (kg / h) was changed to [Example 12: 95%, Example 13: 90%, Example 14: 80%, Example 15: 70%, Example 16: 50%] It computed and feedback-controlled on the same setting conditions shown in the comparative example 1 except having used as the base addition amount and using as an addition amount output lower limit.

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. In addition, the behavior of the amount of finely baked baking soda and the bag filter outlet HCl concentration at the time of this control is shown to FIGS. 26-30.

The effect of Examples 12-16 is obtained by utilizing the factor of an average addition amount for feedback, and the coefficient multiplied by the average addition amount at the time of calculating a basic addition amount should just be 1 times or less, and there is no special limitation. When the coefficient is multiplied by a factor of one or more times (100%), even if the inlet HCl concentration decreases, the average addition amount used for this basic addition amount does not decrease, causing excessive addition.

When the coefficient for calculating the amount of the basic addition is 95% (Example 12) to 70% (Example 15), both the one hour average value maximum and the instantaneous maximum value of the outlet HCl concentration are lower than those of Comparative Example 1, A stable treatment effect was obtained and at the same time an addition amount reduction effect was obtained. In addition, when the coefficient was 50% (Example 16), the addition amount slightly increased, but the acidic gas stabilization treatment effect was obtained. The coefficient to be multiplied by the average addition amount when calculating the basis addition amount may be 1 or less, preferably 50 to 95%, particularly preferably 70 to 90%.

[ Example 17, 18]

The coefficient multiplied by the one-hour moving average addition amount (kg / h) was changed to [Example 17: 90%, Example 18: 70%], except that it was used as the base addition amount and used as the addition amount output lower limit. The feedback control was performed under the same setting conditions.

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. 31 and 32 show the behavior of the amount of finely baked baking soda and the concentration of the bag filter outlet HCl during this control.

According to Examples 17 and 18 when the coefficient to be multiplied when calculating the basic addition amount in the feedback control by the step + SV change method is changed to 70 to 90%, regardless of the coefficient for calculating the basic addition amount, The gas stabilization treatment effect and the addition amount reduction effect can be obtained. Moreover, this system is a control system excellent in the addition amount reduction effect especially with addition amount 289-297 kg / h.

[ Comparative Example 4]

PID control method "P (proportional gain) = 100%, I = 0. Based on HCl density | concentration measured by the HCl measuring device (measuring instrument measurement delay time meter 2 second) in the said simulation. 1 second, D = 0. In 1 second, the addition amount output lower limit 200 kg / h and the addition amount output upper limit 480 kg / h "set the control target value (SV) of outlet HCl concentration to 200 ppm, and feedback control was performed.

The influence of the measurement delay time of the measuring device was examined. When feedback control was performed using a high-speed response HCl measuring instrument with low measurement delay, it was predicted that the change in the amount of alkali agent added and the change in the outlet HCl concentration occurred instantaneously and improved. However, it was predicted that the addition failure by the alkali agent addition fluctuation occurred, and the maximum value of the 1-hour average value of the outlet HCl concentration which is well used as the emission management value of acidic gas was 209 ppm and the instantaneous maximum was 385 ppm.

[ Example 19]

In the simulation, feedback control was carried out under the same conditions as in Example 1 except that PID control calculation was performed based on the HCl concentration measured by the HCl measuring device (measuring device measurement delay time meter 2 seconds).

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. 34 shows the behavior of the amount of finely baked baking soda and the concentration of the bag filter outlet HCl in this control.

[ Example 20]

In the simulation, the feedback control was carried out under the same conditions as in Example 2 except that the calculation was performed by the step method based on the HCl concentration measured by the HCl measuring device (measuring device measurement delay time meter 2 seconds).

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. 35 shows the behavior of the amount of finely baked baking soda and the concentration of the bag filter outlet HCl in the present control.

[ Example 21]

In the simulation, the feedback control was carried out under the same conditions as in Example 3 except that the calculation by the step + SV change method was performed based on the HCl concentration measured by the HCl measuring device (measuring device measurement delay time meter 2 seconds).

The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. 36 shows the behavior of the amount of finely baked baking soda and the concentration of the bag filter outlet HCl in the present control.

According to Example 21, an effect is exhibited regardless of the length and length of the measurement delay time of a measurement instrument. In addition, as a control form, all are effective in a feedback form. Although Examples 19-21 assumed the measurement delay time of 2 second, the addition defect of the alkali agent by feedback was suppressed, and all were able to acquire the stabilizing effect of an acidic gas, and the effect of reducing the addition amount.

[ Example 22]

In the simulation, when the hourly average value of the outlet HCl concentration exceeded 190 ppm, the feedback control was carried out under the same conditions as in Example 10 (delay time 9.5 minutes, step + SV change) except that an alkali agent of 480 kg / h was added. . The amount of finely baked baking soda and the bag filter outlet HCl concentration after treatment with finely baked baking soda are shown in FIG. 37 shows the behavior of the amount of finely baked baking soda and the concentration of the bag filter outlet HCl during this control.

There is a facility that manages the emission concentration of acidic gas as an hourly average value of each acidic gas concentration (hydrogen chloride and sulfur oxide concentration). In the control, it is common to provide and control the control target value SV, but there are cases where the control target value is a target to the last, and the concentration becomes over the target value as a result of the control.

This Example is an example in which Example 1 (average of 190 ppm or more is added 480 kg / h) in Example 10 in which the hourly average value of the outlet HCl concentration exceeds 200 ppm. When the hourly average value of the outlet is close to the concentration to be managed, the control of adding a large amount of an alkali agent enables a more stable treatment effect of the acidic gas and the use of an efficient alkali agent.

Hereinafter, the structure of the acidic gas processing system 2 used by comparative example 5, 6, Example 23, 24 is demonstrated, demonstrating about the comparative example 5, 6, Examples 23, 24 which are actual device examination results. do.

FIG. 38 is a block diagram showing the configuration of an acidic gas processing system 2 in which fine powder baking soda is added to HCl which is exhaust gas in an incineration facility.

The acidic gas treatment system 2 includes a controller 21, a powdered baking soda adding device 22, a powdered baking soda adding device 26, a bag filter 23, an HCl concentration measuring device (ion electrode method) 24 It consists of). The controller 21 controls the addition amount output of the differential baking soda based on the HCl concentration measurement signal transmitted from the HCl concentration measuring device (ion electrode method) 24 and the basic addition amount calculated from the past average addition amount. PID control system or step system). The fine powder baking soda adder 22 adds fine powder baking soda to HCl in exhaust gas based on the output amount of the fine powder baking soda calculated by the control apparatus 21. In addition, the fine powder baking soda adder 26 adds a predetermined amount of fine powder baking soda to HCl in the exhaust gas irrespective of the output amount of the fine powder baking soda calculated by the controller 21.

The bag filter 23 removes dust after reaction of HCl in exhaust gas and fine baking soda. The HCl concentration measuring device (ion electrode method) 24 accumulates on the bag filter 23 the finely baked baking soda (the finely baked baking soda remaining by the reaction with HCl in the exhaust gas is accumulated on the bag filter 23). HCl concentration after the reaction of HCl after the exhaust gas reaction (the bag filter outlet HCl concentration described later) is measured, and the HCl concentration measurement signal is transmitted to the controller 21. In addition, the inlet HCl concentration of a bag filter is measured by the HCl density | concentration measuring apparatus (laser system) which is not shown in figure.

The acidic gas processing system 2 repeats these cycles and performs feedback control, and the control apparatus 21 performs control which makes appropriate the control output value of the amount of fine baking soda addition.

[ Comparative Example 5]

In the industrial waste incinerator, a laser type HCl measuring instrument (KLA-1 manufactured by Kyoto Electronics Co., Ltd.) was installed between the temperature reduction tower exit and the bag filter, and the inlet HCl concentration was measured. Moreover, feedback control was performed by the oxygen conversion value which manages discharge | emission reference value based on the signal measured by the ion-electrode HCl measuring apparatus (HL-36N by Kyoto Electronics Industry) of the bag filter exit. In addition, although the feedback addition output (SV180ppm) by the SOx concentration signal of an exit was added to the addition output by HCl concentration, it implemented, but since SOx did not generate | occur | produce in this facility, it abbreviate | omits in this report.

In addition, the alkaline agent which processes an acidic gas added the 8 micrometer fine baking soda (Kurita Hiparser B-200) by the said feedback control. Alkaline addition device utilizes two units due to the problem of maximum addition amount, and one unit adds 180 kg / h quantitatively, and one unit is based on the exit HCl concentration signal. And PID control setting P (proportional gain) = 100%, I = 0.1 second, D = 0.1 second ".

39 shows the bag filter inlet HCl concentration, the bag filter outlet HCl concentration, and the addition amount of the finely divided baking soda (two addition devices added). 40 shows the behavior of the amount of finely baked baking soda and HCl concentration at the outlet of the bag filter inlet at the time of performing this control.

[ Comparative Example 6]

In the same facility, feedback control was performed by the HCl density | concentration signal (oxygen conversion value) measured by the ion electrode system HCl measuring apparatus (HL-36N by Kyoto Electronics Industry) of the bag filter exit.

In addition, the feedback addition output (SV180ppm) by the SOx concentration signal of the exit was added to the addition output by HCl density | concentration similarly, and it implemented. In addition, the addition apparatus set 180 kg / h fixed quantity addition one likewise, and set one as "a step + SV change system (refer FIG. 41 for details)."

39 shows the bag filter inlet HCl concentration, the bag filter outlet HCl concentration, and the addition amount of the finely divided baking soda (two addition devices added). 42 shows the behavior of the amount of finely baked baking soda and HCl concentration at the outlet of the bag filter inlet at the time of carrying out this control.

[ Example 23]

In the same facility, in the feedback control of the "step + SV change method", the average amount of the outlet HCl concentration for one hour was 213 ppm or more using the base addition amount [30 minutes moving average addition amount, coefficient 70%]. 215 ppm or less], except that 300 kg / h was added, feedback control was performed by the same settings as in Comparative Example 6. In addition, the feedback addition output (SV180ppm) by the SOx concentration signal of the exit was added to the addition output by HCl density | concentration similarly, and it implemented.

In addition, the addition apparatus was set to 180 kg / h quantitative addition similarly, and set it as "the step + SV change system (refer FIG. 41 for details)."

39 shows the bag filter inlet HCl concentration, the bag filter outlet HCl concentration, and the addition amount of the finely divided baking soda (two addition devices added). 43 shows the behavior of the amount of finely baked baking soda and the concentration of HCl at the outlet of the bag filter inlet at the time of carrying out this control.

This embodiment is an application result by the actual apparatus of this invention. Compared with Comparative Examples 5 and 6, the variation in the inlet HCl concentration was reduced. According to the present Example, the addition equivalent which shows the addition amount with respect to the inlet HCl density | concentration of alkaline agent by addition of the efficient alkali agent concerning this invention was reduced compared with Comparative Examples 5 and 6, and efficient control was possible.

[ Example 24]

In the same facility, in the feedback control of the "step + SV change method", the same as in Example 23, except that high-reaction calcined lime (Tamakark ECO manufactured by Ukutama Industrial Co., Ltd.) having a specific surface area of 30 m 2 / g or more was used in combination. Feedback control was performed by setting. In addition, the feedback addition output (SV180ppm) by the SOx concentration signal of the exit was added to the addition output by HCl density | concentration similarly, and it implemented.

In addition, one addition device set 170 kg / h of quantitative addition of high-reaction calcined lime, and the other set it as "step + SV change system (refer FIG. 41 for details)."

39 shows the bag filter inlet HCl concentration, the bag filter outlet HCl concentration, and the addition amount of the finely divided baking soda (two addition devices added). 44 shows the behavior of the amount of finely baked baking soda and HCl concentration at the outlet of the bag filter inlet at the time of performing this control.

This embodiment is an example in which a combination of comparatively inexpensive slaked lime and finely baked baking soda is used. Also in this method, the stable treatment effect of the acidic gas can be obtained stably. It is an industrially effective method because the cost of acidic gas treatment is reduced by utilizing inexpensive slaked lime.

1: acid gas treatment system
11: Control device
12: powder baking soda addition device
13: Bag filter
14: HCl concentration measuring instrument

Claims

An alkali gas treatment method for adding an alkali agent to a combustion exhaust gas containing an acid gas and feedback-controlling the addition amount of the alkali agent based on a measurement signal of an acid gas concentration measuring instrument for measuring an acid gas concentration after collecting dust.
Calculating a base addition amount by multiplying an average addition amount corresponding to at least an average time by a factor of 1 or less; and
A processing method of an acidic gas having a step of calculating an output amount of an alkali chemicals addition amount based on the calculated basic addition amount by a feedback calculation.

The method of claim 1,
In the process of calculating the said addition amount output value by a feedback calculation, the processing method of the acidic gas which makes the calculated basic addition amount the lower limit of the addition amount output value of the said alkali chemicals.

3. The method according to claim 1 or 2,
The process of calculating the addition amount output value by a feedback operation,
Setting a range of slopes of at least two acid gas concentrations,
Setting a control target value of an acid gas concentration for each of the at least two slopes;
Calculating an addition amount output value of an alkali chemical agent based on at least the said control signal and the control target value for every range of the said inclination,
In the step of setting the control target value, the control target value set to the case where the slope of the acidic gas concentration is large is less than the control target value set to the case where the slope of the acid gas concentration is small. Way.

4. The method according to any one of claims 1 to 3,
The process of calculating the addition amount output value by a feedback operation,
And setting at least one new upper limit value of the addition amount output value corresponding to the acidic gas concentration between the lower limit value and the upper limit value of the addition amount output value calculated based on the measurement signal.

5. The method according to any one of claims 1 to 4,
In the process of calculating the said basic addition amount, the processing method of the acidic gas which makes 0.5 to 0.95 times the average addition amount when an average time is 5 minutes or more as a basic addition amount.

The method according to any one of claims 1 to 5,
The process of calculating the addition amount output value by a feedback operation,
And a step of calculating the addition amount output value of the alkali chemicals by using the two outputs of the control output calculated from the hydrogen chloride concentration and the control output calculated from the sulfur oxide concentration in addition to the feedback operation.

7. The method according to any one of claims 1 to 6,
The process of calculating the addition amount output value by a feedback operation,
And calculating the addition amount output value of the alkaline agent on the basis of the average value of the hydrogen chloride concentration and / or the sulfur oxide concentration in addition to the feedback calculation.

8. The method according to any one of claims 1 to 7,
A method for treating acidic gas in which the alkali agent is finely divided baking soda having an average particle diameter of 5 to 30 µm.

9. The method of claim 8,
A method of treating an acid gas using another alkaline agent different from the finely divided baking soda.

10. The method of claim 9,
The said other alkali agent is the processing method of the acidic gas which is at least 1 sort (s) of alkali chemicals chosen from the group which consists of calcined lime, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, cesky carbonate, natural soda, and fine baking soda.