KR20120121836A - Method for treating acid gas - Google Patents

Abstract

PURPOSE: A treatment method of acid gas is provided to prevent an alkali agent from excessively adding into acid gas due to the delay of acid gas concentration measurement. CONSTITUTION: A treatment method of acid gas includes an acid gas concentration measuring process and a process for calculating the adding amount of an alkali agent. The acid gas concentration measuring process uses a plurality of acid gas concentration meters. The acid gas concentration meters have different measurement delay times and measure the concentration of the same acid gas. The adding amount of the alkali agent is calculated by signals from the acid gas concentration meters. [Reference numerals] (AA) Basic mechanism of simulation reaction; (BB) HCl concentration meter(low speed) measurement delay time(Tb); (CC) HCl concentration meter(high speed) measurement delay time(Tc); (DD) Chemical injection control; (EE) Delay time of a facility; (FF) Fine sodium bicarbonate adding amount(kg/h)(Ag); (GG) Exhaust gas reacted fine sodium bicarbonate adding equivalent(Jg); (HH) BF phase reactive fine sodium bicarbonate adding equivalent(Js); (II) Inlet; (JJ) HCl concentration(ppm); (KK) Exhaust gas reactive HCl removal rate(%); (LL) HCl concentration(ppm) after exhaust gas reaction; (MM) BF phase reaction HCl removal rate(%); (NN) BF outlet; (OO) HCl concentration(ppm)

Description

[0001] METHOD FOR TREATING ACID GAS [0002]

The present invention relates to harmful hydrogen chloride (hydrogen chloride) or sulfur oxide (sulfur oxide) generated in a combustion facility such as a municipal waste incinerator, an industrial waste incinerator, a power generation boiler, a carbonization furnace, The present invention relates to a method for treating an acidic gas of an acidic gas. More particularly, the present invention relates to a method for efficiently controlling the amount of an alkaline agent for treating an acidic gas.

The exhaust gas containing harmful hydrogen chloride or sulfur oxide is treated with an alkali agent such as slaked lime or sodium bicarbonate and then subjected to dust removal by a dust collector such as a bag filter BF And then discharged from the chimney. On the other hand, fly ash collected in the dust collector contains harmful heavy metals such as Pb and Cd, and these harmful heavy metals are subjected to stabilization treatment and landfill disposal.

The powdered sand bath processed in 5-30 μm, which is an alkaline agent that treats acid gases, is more reactive than slaked lime, can handle acid gases more stably, and has less unreacted powders and landfills. The amount of disposal can be reduced, which is an effective means for reducing environmental load. As a method for treating heavy metals, a method of insolubilization treatment by chelate such as diethyldithiocarbamate is generally used. In the short term, the heavy metal fixing effect is high, but the acid rain rate in the final disposal site (Re-elution) of heavy metals such as lead by the reduction of the pH by the oxidizing agent and the oxidative self-decomposition of the chelate (oxidation self-decomposition). On the other hand, since heavy metal fixation (heavy metal fixation) by a phosphate compound such as phosphoric acid changes to a hydroxyapatite form which is an inorganic mineral (inorganic mineral), it is excellent in long-term stability in the final disposal site It is a very valuable treatment from the viewpoint of environmental protection. In addition, the method of treating the fly ash treated with the above-mentioned fine powder baking soda with a heavy metal fixing agent such as phosphoric acid is an effective means having many environmental load reducing effects.

However, controlling the addition amount of an alkali agent such as a slaked lime or a sulfuric acid to treat an acidic gas such as hydrogen chloride or sulfur oxide not only can reduce the cost of treating the acid gas, but also reduces unreacted components of the alkali agent, It is possible to expect an effect of reducing the amount.

The amount of the alkaline agent for treating an acidic gas such as hydrogen chloride or sulfur oxide is generally controlled by a PID controller based on the HCl concentration measured in a hydrogen chloride measuring apparatus of ion electrode type (ion electrode type) Feedback control is being performed. However, in a combustion facility such as an incineration facility, a device for measuring the acidic gas concentration at the inlet is not installed, and the control output is adjusted by setting a PID control parameter without knowing the change of the inlet. However, since the PID control device has 5 setting items of P, I, D, the lower limit of addition (output) and the upper limit of addition (output) and the set values of each item are combined to set the control output value, It takes time. Therefore, in many cases, the setting by the PID controller generally controls the addition amount to be significantly increased when the control target value SV is exceeded.

However, usually only one upper limit can be set for the control output of the PID control device. For example, when the control target value SV of the HCl concentration is set to 40 ppm, one upper limit for controlling output at a concentration of 40 ppm or more An alkaline agent is added as a limit, which causes an excessive addition of an alkaline agent. In addition, the feedback control is affected by the measurement delay of the acid gas measuring device. The HCl concentration at the outlet of the bag filter is usually measured by the ion electrode method (e.g., Kyoto Electronics Co., Ltd.), and the sulfur oxide concentration is determined by the infrared absorption method. For example, it is measured by Shimadzu Corporation NS-3080, but there is an enormous measurement delay of 5 to 10 minutes including the sampling time of the sample exhaust gas and the response time of the measuring instrument. This measurement delay causes a delay in the addition of the alkali agent, which leads to a treatment failure of the acid gas and causes an excessive addition of the alkali agent.

Various control methods are being studied to solve this problem. In Patent Document 1, "P + PID control" in which P is added to a normal PID control formula is proposed. This proposal considers coping with the unexpected occurrence of acid gas which is difficult with ordinary PID control. Further, in Patent Documents 2 and 3, the feed forward control for determining the addition amount of the alkali agent based on the concentration of the acid gas at the inlet and the feedback for supplementing the addition amount of the alkali agent based on the acid gas concentration after the treatment with the alkali agent A control method of combining control is proposed. This control system can be expected to have an effect of suppressing the excessive addition of the feedback control, and it is thought that the effect of stable treatment of the acid gas and excessive addition of the alkaline agent is obtained.

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

However, in Patent Document 1, unexpected response to the inlet is possible to some extent, but measurement delay of the measuring apparatus is not taken into account, so that it can not cope with processing failure of the acid gas due to delay of addition of the alkali agent due to measurement delay. In Patent Documents 2 and 3, the measuring environment of the burning conduit during the evacuation has a higher concentration of acid gas than the measuring environment after the dust collecting, and therefore it is necessary to take countermeasures against corrosion of the measuring device base. In addition, since there is a lot of soot dust in the exhaust gas before the dust removal, workforce and the like are required for maintenance and maintenance such as measures for anti-vibration and replacement of a dust filter for example. Further, the measurement defects caused by defects in these measuring instruments have a serious problem in stably managing the acid gas concentration at the outlet, since the measurement signal of the acid gas concentration directly affects the addition amount of the alkali agent.

In view of the foregoing, the present invention provides a feedback system for controlling the addition amount of an alkaline agent based on a measurement environment capable of stably measuring an acid gas, that is, an acid gas concentration measurement signal after the dust collecting step, And an object of the present invention is to provide a method for treating an acidic gas which reduces the treatment failure of the acidic gas and the excessive addition of the alkaline agent due to the measurement delay.

(1) An acidic gas concentration measuring device provided with an alkaline agent added to a combustion exhaust gas containing an acidic gas and measuring an acidic gas concentration after dust is collected, (For example, an HCl concentration measuring instrument (low speed) 14 and an HCl concentration measuring instrument (high speed) 15, which will be described later) having a measurement delay time different from each other A step of measuring an acid gas concentration of the same kind and a step of calculating an output value of an addition amount of an alkaline agent based on a measurement signal of the plurality of acid gas concentration measuring instruments by feedback calculation, Way.

The acid gas concentration at the conventional bag filter outlet is measured by, for example, an ion electrode method having a measurement delay time of 5 to 10 minutes by a single measuring device, and the addition amount of the alkaline agent is controlled by feedback based on the measurement signal. This method causes an excessive addition of an alkali agent due to measurement delay of the measuring instrument.

On the other hand, according to the invention of (1), on the basis of measurement signals of a measuring instrument having a long measurement delay time and a measuring instrument having a short measuring delay time, that is, measurement signals of a plurality of measuring instruments having different measurement delay times, The output value is calculated by feedback calculation. Accordingly, it is possible to combine not only one measuring instrument with a long measuring delay time but also a measuring instrument with a short measuring delay time, so that excessive addition of the alkaline agent due to measurement delay of the acid gas concentration measuring instrument in the feedback control can be reduced.

Further, according to the invention (1), since the plurality of acid gas concentration measuring instruments having different measurement delay times are provided, the concentration of the acid gas at the outlet of the bag filter is appropriately adjusted by the measurement instrument having a long measurement delay time but high measurement reliability And the measurement reliability can be improved more than the feedback control by the measuring device having a low measuring delay but a low measuring reliability. Therefore, the addition of the alkali agent can be appropriately performed, and the treatment efficiency of the acid gas can be further improved.

Further, by combining a measuring instrument with a short measuring delay time in a measuring instrument having a long measurement delay time, the timing of adding the alkali agent at the time of increasing the acid gas can be made earlier than in the conventional control, and the acidity The treatment failure of the gas can be improved.

(2) The step of calculating the addition amount output value by the feedback calculation includes a step of calculating an upper limit value (upper limit value) of a plurality of addition amount output values (for example, 100% (A value obtained by multiplying the upper limit value of at least one of the plurality of upper limit values) by a value smaller than the upper limit value (for example, a value obtained by multiplying the output limit by 50%, which will be described later) (1). ≪ / RTI >

According to the invention of (2), an addition amount output value having a value smaller than the upper limit value is calculated for at least one upper limit value among the upper limit values of the calculated addition amount output values.

As compared with the case where both of the addition amount output value calculated based on the measurement signal of the measuring instrument with a long measuring delay time and the measuring instrument with a short measuring delay time are operated at the upper limit value (100%), It is possible to further prevent the excessive addition of the alkaline agent while stabilizing the treatment of the acidic gas even if only the addition amount output value calculated on the basis of the measurement signal of the measuring instrument is limited (for example, output limitation of 50%).

(For example, an output limit of 50%) is applied to both the addition amount output value calculated on the basis of the measurement signal of the measuring instrument having a long measuring delay time and the measuring instrument having the short measuring delay time, The excessive addition of the alkali agent can be further prevented.

(3) The step of calculating the addition amount output value by the feedback calculation is a step of calculating the inclination of at least two acid gas concentrations (for example, the 6-second average of the slope of the closest HCl concentration described later is positive (For example, 180 ppm or 220 ppm in the embodiment 8 to be described later) is set for each of the at least two inclination ranges, Further comprising a step of calculating an output value of an additive amount of an alkaline agent based on at least the measurement signal and the control target value for each range of the gradient, wherein in the step of setting the control target value, (For example, when the 6-second average of the gradient of the closest HCl concentration is positive (when the acid gas concentration is increased)) When the gradient of the concentration of the acid gas is small (for example, when the 6-second average of the gradient of the closest HCl concentration is negative (when the concentration of the acid gas is lowered)), Is smaller than the control target value set in the step (1) or (2).

According to the invention of (3), when the slope of the acid gas concentration at the outlet of the bag filter is positive (when the acid gas concentration rises), the slope of the acid gas concentration is lower than the acid gas concentration when the slope is negative Since the control target value is made smaller, the amount of the alkali agent added at the time of increasing the concentration of the acid gas can be made larger than that at the time of lowering the acid gas concentration. On the other hand, the amount of the alkali agent added at the time of lowering the acid gas concentration can be made smaller than that at the time of the acid gas concentration rising. Therefore, the addition output of the alkaline agent by the feedback calculation can be performed in advance, and the influence due to the measurement delay can be further alleviated.

(4) The step of calculating the addition amount output value by the feedback calculation includes a step of calculating a lower limit value (lower limit value) of the addition amount output value calculated based on the measurement signal (for example, LO 21, Fig. 23, and Fig. 31 (described later, for example) between the upper limit value (the lower limit of the output power) and the upper limit value One or more new upper limit values of the addition amount output values (for example, LM1 (output restriction 1), LM2 (output restriction 2) in FIG. 21, FIG. 23 and FIG. 31 described later) corresponding to the BF outlet HCl concentration The method of treating an acidic gas according to any one of (1) to (3), further comprising the step of:

The upper limit of the output in the normal feedback operation is only one, and when the acid gas is above the control target value, the alkali agent can be added up to the upper limit regardless of the acidic gas concentration at the inlet, resulting in excessive addition.

On the other hand, according to the invention of (4), it is possible to appropriately add the alkali agent according to the magnitude of the acidic gas concentration by limiting the control output according to the current acidic gas concentration between the lower limit value and the upper limit value of the addition amount output value. It is possible to reduce it.

(5) The treatment method of acidic gas according to any one of (1) to (4), wherein the alkali agent is a fine powder tank having an average particle diameter of 5 to 30 µm.

It is preferable that the alkali agent used for this invention is a fine powder tank which especially adjusted the average particle diameter to 5-30 micrometers with quick reaction with an acidic gas. Since the reaction is rapid in the differential boiling water, the control response is good and the performance of the present invention can be effectively exerted. However, the present invention is based on a control method, and can also be applied to slaked lime. The slaked lime is a slaked lime having a high specific surface area (high specific surface area) and a high specific surface area (specific surface area) of, for example, 30 m ² / g or more.

(6) The method for treating an acidic gas according to (5), wherein an alkali agent different from the group of the above-mentioned fine powders is used in combination.

The alkaline agent exhibiting the effect of the present invention is not particularly limited. Examples of the alkaline agent other than the neutralizing agent include sodium carbonate, potassium bicarbonate, potassium carbonate, sodium sesquicarbonate, natural soda, sodium hydroxide, Potassium hydroxide, magnesium oxide, magnesium hydroxide, and the like. In the case where the alkali agent is powder, it is more preferable that the reactivity with acidic gas is high and the particle diameter is less than 30 µm, particularly 5 to 20 µm fine powder. A medicament whose particle diameter has been adjusted in advance may be applied, or a crushing facility (dusting facility) may be installed in the site, and an alkaline agent having a rough particle size may be added while being pulverized locally. It is also possible to use a slurry or an aqueous solution in which each alkali agent is dissolved in water.

(7) The alkaline agent described above is at least one alkaline agent selected from the group consisting of calcium hydroxide, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, sodium sesquicarbonate, natural soda, A method for treating an acidic gas as claimed.

It is also an economically effective means to use an inexpensive alkaline agent different from the alkaline agent which performs the control according to the present invention. Commonly used inexpensive alkaline agents include calcium hydroxide, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, sodium sesquicarbonate, natural soda, and crude oil.

According to the present invention, there is provided a feedback system for controlling an addition amount of an alkaline agent based on a measurement environment capable of stably measuring an acid gas, that is, an acid gas concentration measurement signal after a dust collecting process, It is possible to reduce the treatment failure of the acid gas and the excessive addition of the alkali agent due to the measurement delay and to treat the acid gas stably by adding the alkali agent efficiently.

Fig. 1 is a block diagram showing the construction of an acid gas treating system 1 in which a differential booster is added to HCl which is an exhaust gas in an incineration facility.
2 is a basic configuration diagram of a simulation reaction system.
Fig. 3 is a graph showing the relationship between the addition amount of the fine powder and the HCl removal ratio in the exhaust gas reaction.
Fig. 4 is a graph showing the relationship between the equivalent amount of the added neutralizing agent and the HCl removal rate in the reaction on the bag filter.
5 is a graph showing the behavior of the entrance HCl concentration.
FIG. 6 is a graph showing the behavior of the addition amount of fine powder (addition amount of fine powder) and the outlet HCl concentration as a result of practical test.
FIG. 7 is a graph showing the behavior of the addition amount of the fine base powder and the outlet HCl concentration in the simulation result.
Fig. 8 is a table showing comparative examples of simulation results and amounts of alkaline agent added for each example. Fig.
9 is a graph showing the behavior of inlet HCl concentration.
10 is a graph showing the behavior of the addition amount of the differentiating salt and the outlet HCl concentration in Comparative Example 1. Fig.
11 is a graph showing the behavior of the addition amount of the differentiating salt and the outlet HCl concentration in Comparative Example 2. Fig.
12 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 1. Fig.
13 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 2. Fig.
Fig. 14 is a graph showing behaviors of the addition amount of the fine salt tin and the outlet HCl concentration in Example 3; Fig.
15 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 4. Fig.
16 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 5. Fig.
17 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 6. Fig.
18 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 7. Fig.
19 is a graph showing the behavior of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 8. Fig.
20 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 9. Fig.
Fig. 21 is a table of control settings of the step control system in the tenth embodiment.
22 is a graph showing behaviors of the addition amount of the fine salt tin and the outlet HCl concentration in Example 10. Fig.
23 is a table of control settings of the step control system in the eleventh and twelfth embodiments.
24 is a graph showing behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 11. Fig.
25 is a graph showing the behaviors of the addition amount of the fine salt preparation and the outlet HCl concentration in Example 12. Fig.
Fig. 26 is a block diagram showing the construction of an acidic gas treatment system 2 for adding a differential boiling tank to HCl which is an exhaust gas in an incineration facility.
Fig. 27 is a table showing comparative examples of practical test results and amounts of alkaline agent added for each of the examples. Fig.
28 is a graph showing the behaviors of the addition amount of the differentiating salt groups, the inlet HCl concentration and the outlet HCl concentration in Comparative Example 3;
29 is a graph showing behaviors of the addition amount of the differentiating salt tanks, the inlet HCl concentration, and the outlet HCl concentration in Example 13. Fig.
30 is a graph showing the behaviors of the addition amount of the differentiating salt, the inlet HCl concentration and the outlet HCl concentration in Example 14. Fig.
31 is a table of control settings of the step control system in the fifteenth and sixteenth embodiments.
32 is a graph showing behaviors of the addition amount of the differential salt tank, the inlet HCl concentration, and the outlet HCl concentration in Example 15. Fig.
33 is a graph showing behaviors of the addition amount of the differentiator tank, the inlet HCl concentration, and the outlet HCl concentration in Example 16. Fig.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Fig. 1 is a block diagram showing the construction of an acid gas treating system 1 in which a differential booster is added to HCl which is an exhaust gas in an incineration facility.

The acid gas treatment system 1 includes a control device 11, a fine particle addition device 12, a bag filter 13, an HCl concentration measurement device (low speed) (Low speed)) 14 and an HCl concentration measuring instrument (high speed) (concentration measuring instrument (high speed)) (15). The control device 11 performs feedback control (PID control method or step method) on the basis of the HCl concentration measurement signal transmitted from the HCl concentration measurement device (low speed) 14 and the HCl concentration measurement device (high speed) The output value of the addition amount of the differential dyeing tank is calculated. The differential bead addition device 12 adds a differential bead to HCl in the exhaust gas based on the output value of the addition amount of the differential bead preparation calculated by the control device 11.

The bag filter 13 removes dust after the reaction of HCl in the exhaust gas and the differential-salt tank. The HCl concentration measuring instrument (low speed) 14 and the HCl concentration measuring instrument (high speed) 15 are arranged in such a manner that the differential sodium bicarbonate (the differential sodium bicarbonate remaining in the exhaust gas by reaction with HCl in the exhaust gas) (To be described later, HCl concentration at the outlet of the bag filter) is measured after the reaction of HCl after the exhaust gas reaction with the HCl concentration measurement signal (which is accumulated on the filter 13) is transmitted to the control device 11.

The control device 11 appropriately controls the control output value of the addition amount of the differential baffle by repeatedly performing the feedback control on this cycle by the acid gas processing system 1. [

The HCl concentration measuring device (low speed) 14 is, for example, an ion electrode type HCl concentration measuring device, and the HCl concentration measuring device (high speed) 15 is, for example, a laser type HCl concentration measuring device. Further, the measurement delay time of the HCl concentration is longer than that of the HCl concentration measuring instrument (high-speed) (15) for the HCl concentration measuring instrument (14).

Further, as shown in FIG. 1, the HCl concentration measuring instrument (HCl concentration measuring instrument) was used to measure the HCl concentration (the HCl concentration at the outlet of the bag filter to be described later) after reacting HCl after the exhaust gas reaction with the differential- Low speed) 14 and an HCl concentration measuring instrument (high speed) 15 are preferably provided. This is because the minute differential tank remaining after the reaction with HCl in the exhaust gas is accumulated on the bag filter 13 and the accumulated differential tank is reacted with the HCl after the exhaust gas reaction so that the HCl concentration can be measured more accurately It is because.

The control performed by the control device 11 will be described in detail.

The control device 11 calculates the addition amount of each additive amount to the added amount of the differential halftone control tone based on the HCl concentration measurement signal transmitted from each of the HCl concentration measurement device (low speed) 14 and the HCl concentration measurement device (high speed) The upper limit value of the value is calculated. In this case, the output limit (e.g., the output limit of 50%) may be applied to either or both of the calculated upper limit values.

Thus, both of the addition amount output values calculated based on the HCl concentration measurement signal transmitted from each of the HCl concentration measuring instrument (low speed) 14 and the HCl concentration measuring instrument (high speed) 15 are set to the upper limit value (100%), (For example, an output limit of 50%) is applied only to the addition amount output value calculated on the basis of the measurement signal of the HCl concentration measuring instrument (low speed) 14, which has a long measurement delay time, The excessive addition of the alkali agent can be further prevented while stabilizing the treatment of the acid gas.

Further, the addition amount output value calculated based on the measurement signals of the HCl concentration measuring instrument (low speed) 14 having a long measuring delay time and the HCl concentration measuring instrument (high speed) 15 having a short measuring delay time is limited , It is possible to further prevent the excessive addition of the alkaline agent while stabilizing the treatment of the acidic gas.

Further, the control device 11 sets two ranges in which the slope of the HCl concentration (time variation rate of the concentration) is a positive range and a negative range. The control target of HCl concentration is set for each of the two ranges.

Here, the setting of the control target value of the HCl concentration may be set so that the control target value set for the range of the gradient of the HCl concentration is smaller than the control target value for the negative range. By doing so, the addition amount of the fine salt added at the time of increasing the HCl concentration can be made larger than that at the HCl concentration lowering. Conversely, when the HCl concentration is lowered, the addition amount of the differential salt can be made smaller than that when the HCl concentration is increased. Therefore, the addition output of the differential sampling by the feedback calculation can be performed in advance, and the influence of the measurement delay can be further reduced.

Also, the setting for changing the control target value according to the gradient of the HCl concentration may be performed for both of the HCl concentration measuring instrument (low speed) 14 and the HCl concentration measuring instrument (high speed) 15, or for either one of them.

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

Here, the upper limit of the output in normal PID control is only one, and when the acid gas is above the control target value, the alkali agent can be added up to the upper limit value irrespective of the acidic gas concentration, thereby causing excessive addition. Therefore, by adopting the step control method, by adding a new control output upper limit value corresponding to the current HCl concentration between the lower limit value and the upper limit value of the addition amount output value, it is possible to appropriately add the differential control tank according to the HCl concentration, The addition can be suppressed.

Here, a new control output upper limit value is set corresponding to the HCl concentration, but the higher the HCl concentration, the higher the new control output upper limit value is set. However, in order to suppress the excessive addition of the alkali agent, it is preferable to set the lower limit value of the control output value set in the PID control method (for example, LH (control output upper limit) shown in Figs. 21 and 23).

As a setting example of a new control output upper limit value, it is preferable to set a higher control output upper limit value as the HCl concentration is higher, such as the control output addition amount corresponding to the BF outlet HCl concentration described later in Figs. 21 and 23.

The acidic gas concentration measuring device used in the present embodiment can be practiced if the delay times of the measuring devices are different from one another regardless of the measuring method. In the case of HCl concentration measurement, the ion electrode method with a long measurement delay time of 5 to 10 minutes is the mainstream. In addition, although the response in the ion electrode part is about 3 minutes, when it includes the delay by gas sampling, it is 5-7 minutes. Also, if there is a possibility that bromine is mixed into the sampling gas, such as an industrial waste incinerator, a bromine scrubber (bromine scrubber) is installed to remove bromine since it greatly affects the measurement of hydrogen chloride. The passing time of the bromine scrubber is about 3 minutes and the measurement delay time is about 8 to 10 minutes.

In addition, the measurement delay time of hydrogen chloride by a single absorption line absorption spectroscopy by a laser is very short (a few seconds). The present invention can be implemented by performing feedback control using two measuring instruments having different measurement delay times, but it is optimal to combine these measuring devices in a measuring instrument in the present state. In addition, the measurement of the concentration of sulfur oxides is mainly performed by an infrared absorption method with a delay time of about 3 minutes to 5 minutes. Sulfur oxides can also be carried out by combining measurement instruments having different measurement delay times as hydrogen chloride.

Further, the present invention is directed to improvement of the measurement delay of the acid gas. Therefore, in a facility for measuring the acid gas at the back end of the bag filter by the ion electrode method with a large measurement delay using a hydrogen chloride measuring apparatus, Especially effective.

Also, in combustion facilities of industrial waste incinerators and civilian factories, hydrogen chloride and sulfur oxides are often generated at high concentrations. At this time, both of the hydrogen chloride and the sulfur oxide are to be treated, and based on the HCl concentration of the HCl concentration measuring device provided at the downstream end of the bag filter, the control output obtained in the above control method and the sulfur oxide concentration And the obtained control output is added, for example, to stably treat both the acid gases of hydrogen chloride and sulfur oxide.

In addition, there is a facility which manages the discharge concentration of acid gas by an average of one hour of each acid gas concentration (hydrogen chloride, sulfur oxide concentration). In the control, it is common to set and control the control target value SV. However, the control target value is always the target, and sometimes the concentration exceeds the target value as a result of the control. Particularly, since the addition amount reduction and the stable treatment of the acid gas are contradictory, if the addition amount is desired to be reduced, the risk that the average value for one hour exceeds the management value increases. In this case, when the concentration reaches or exceeds the average management value for 1 hour, a large amount of addition (prescribed by a certain amount of addition) is made, so that a high degree of safety control that can achieve both reduction in addition amount and stable treatment of acid gas is achieved. Becomes possible.

In particular, the fine powder bath used in the present embodiment is a fine powder bath in which the average particle diameter of the reaction with the acidic gas is fast adjusted to 5 to 30 µm. The reason for this is that since the reaction is rapid, the control response is good and the performance of the present embodiment can be effectively exerted. However, the present embodiment is based on a control method, and can also be applied to slaked lime. The slaked lime can exhibit the performance of the present embodiment as a lime of high specific surface area having a high reactivity with an acid gas and a specific surface area of 30 m ² / g or more, for example.

In the present embodiment, a fine-particle-sized tank is used as the alkaline agent, but there is no particular limitation on the alkaline agent that exhibits the effect of this embodiment. Examples of the alkaline agent other than the fine salt-forming agent include sodium carbonate, potassium hydrogen carbonate, potassium carbonate, sodium sesquicarbonate, natural soda, sodium hydroxide, potassium hydroxide, magnesium oxide and magnesium hydroxide. In the case where the alkali agent is powder, it is preferable that the reactivity with acidic gas is high and the particle size is fine powder of less than 30 µm, particularly 5-20 µm. A medicament whose particle diameter has been adjusted in advance may be applied, and a rough grinding facility may be installed in the site to add a rough alkaline agent having a particle size while pulverizing it locally. It is also possible to use a slurry or an aqueous solution in which each alkali agent is dissolved in water.

It is also economically effective to use a low-cost alkaline agent different from the group of the fine powders to be controlled according to the present embodiment. Examples of commercially available low-cost alkaline agents include calcium hydroxide, sodium hydroxide, magnesium hydroxide, and magnesium oxide.

[Example]

The simulation reaction system will be described.

[Simulation Reaction System]: Combined reaction on exhaust gas and bag filter

The simulation reaction system was constituted by two reactions: a reaction in which the reaction between the differential salt tank and the hydrogen chloride (HCL) occurs instantaneously in the exhaust gas, and the reaction of the unreacted differential salt tank and the HCL accumulated on the bag filter Reference). Also, the retention time of the collected product (collected product) in the bag filter is usually about 2 hours. Therefore, in this simulation, the differential sampling on the bag filter was made to disappear at the specified time (set at about 2 hours).

The basic configuration of the simulation reaction system will be described with reference to Fig.

First, in the chemical liquid injection control in the incineration facility, the HCl concentration measuring instrument (low speed) of the ion electrode type and the HCl concentration measuring instrument (high speed) of, for example, (Acidic gas treating agent) of the determined amount is added to the exhaust gas (the amount of the additive gas (Ag)) by the control formula of the PID or the like based on the signal (Inlet HCl concentration (Hi)). The differential booster added to the flue gas reacts with an acid gas such as HCl in the flue gas to remove HCl in the flue gas.

Ag = (Ag1 x K1 / 100 + Ag2 x K2 / 100) + LO (1)

Ag: Addition amount of fine powder [kg / h]

Ag1: Addition amount specified from the output of the HCl concentration measuring device (low speed) [kg / h]

Ag2: Addition amount specified from output of HCl concentration measuring instrument (high speed) [kg / h]

LO: Lower limit of addition [kg / h]

K1: Coefficient of adjustment for HCl measuring instrument 1 (low speed) [%]

K2: Coefficient of adjustment for HCl measuring instrument 2 (high speed) [%]

The HCl removal rate of the inlet HCl concentration due to the differential boiling is calculated from the knowledge of the application of the differential boiling tank of the Company to the relationship between the differential equivalent heptane addition amount (Jg) of the exhaust gas reaction and the exhaust gas reaction HCl removal rate (αg) (Fig. 4) of the reaction equivalent HCl removal rate (Fig. 4) on the bag filter. Also, the reaction between HCl and differentiation was made momentary. First, the HCl concentration (Hg) after the reaction in the exhaust gas is calculated by the differential equivalent heptane addition amount (Jg) of the exhaust gas reaction and the exhaust gas reaction HCl removal rate (? G) (the following formula (2)). Further, the equivalent weight (Jg) of the addition of the fine particles in the exhaust gas reaction is calculated by the following equation (3).

Hg = Hi x (1 -? G / 100) (2)

Hi: inlet HCl concentration (ppm)

Hg: HCl concentration after exhaust gas reaction (ppm)

? g: HCl removal rate in the exhaust gas reaction (%)

[Setting from the relationship between the equivalent amount of the exhaust gas reaction and the HCl removal rate (Fig. 3)

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

Jg: Equivalent amount of exhaust gas reaction differential

Ag: Addition amount of fine powder (kg / h)

Hi: inlet HCl concentration (ppm)

M1: HCl molecular weight [set to 36.5]

M2: Mesophase molecular weight [Set to 84]

F: amount of exhaust gas (Nm ³ / h) [set to 55,000Nm ³ / h]

In addition, the differential heavies remaining due to the exhaust gas reaction accumulate on the bag filter from time to time. The differential boiling tank 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 (As) of the accumulated fine particles on the BF phase was subtracted from the amount of the fine particles reacted with the HCl on the BF from the fine base oil accumulated by the exhaust gas reaction. The HCl concentration on the bag filter was calculated from the aspiration amount (As) of the fine particles accumulated on the bag filter and the Hf concentration after the exhaust gas reaction (Hg) The removal rate? S was determined, and the HCl concentration (Ho) at the outlet of the bag filter was determined (equation (4)).

Ho = Hg x (1 -? S / 100) (4)

Hg: HCl concentration after exhaust gas reaction (ppm)

Ho: Back filter outlet HCl concentration (ppm)

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

[Setting from the relationship between the equivalence addition amount of the fine powder on the bag filter and the HCl removal rate (Fig. 4)

Js = As? {Hg / 0.614? 1000? M1? M2? F? 1000}

Js: Equivalent amount of the additive on the bag filter

As: The amount of fine powder (kg / h) on the bag filter.

Hg: HCl concentration after exhaust gas reaction (ppm)

M1: HCl molecular weight [set to 36.5]

M2: Mesophase molecular weight [Set to 84]

F: amount of exhaust gas (Nm ³ / h) [set to 55,000Nm ³ / h]

As = Zn / Ts x 3600 (6)

Zn: accumulation amount of differential dye on bag filter (kg)

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

[0.5sec setting]

Zn = Zn 'x (1-2.3 / T4 x Ts) (7)

Zn ': Amount of unreacted fine powder (kg)

T4: accumulation on accumulator on the bag filter 90% decay time constant (decay time constant) (sec)

[7,200 sec setting]

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

[0.5sec setting]

Zn? = (Ag ÷ 3600 × Ts-Rg) + (Zn-1-Rs) (8)

Ag: Addition amount of fine powder (kg / h)

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

[0.5sec setting]

Rg: the amount of the azeotropic reaction in the exhaust gas reaction (kg / h)

Zn-1: The accumulation amount of the particulate matter on the bag filter before Ts (Sec)

Rs: the amount of the azeotrope reaction in the bag filter phase reaction (kg / h)

Rg = (H ÷ 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: Mesophase molecular weight [Set to 84]

F: amount of exhaust gas (Nm ³ / h) [set to 55,000Nm ³ / h]

? g: HCl removal rate in the 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: Mesophase molecular weight [Set to 84]

F: amount of exhaust gas (Nm ³ / h) [set to 55,000Nm ³ / h]

? s: 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 (low speed) 14 and an HCl concentration measuring instrument (high speed) 15. In the ion electrode type HCl concentration measuring instrument (low speed) 14, the delay time (Ta) by the facility, the measurement delay time (TBa) by exhaust gas sampling, and the measurement delay time by Tb , Response time), and a control delay specific to the feedback occurs.

Therefore, the delay time T1 of the HCl concentration measuring instrument (low speed) 14 of this simulation is calculated by adding the total of the delay time Ta by the facility and the measurement delay time Tb of the HCl concentration measuring instrument (low speed) (The following equation (11)). The measurement delay time Tb of the HCl concentration measuring instrument (low speed) 14 is determined by the measurement delay time Tb? For sampling the exhaust gas after the HCl treatment from the year and the measurement delay time Tb? Of the ion electrode type HCl concentration measuring instrument Tb? The delay time (response time) was set, and the sum of the delay time and the delay time was set (Expression (12)). The 90% response time (measurement delay) of a commonly used ion electrode type is determined by Tb? (The following equation (13)) because the diffusion of the HCl gas into the absorption liquid is affected. In this simulation, Ta = 30 seconds, Tb? = 390 seconds (sampling delay: 210 seconds + 180 seconds of passing through the bromoscrover), Tb? = 30 seconds from the situation of the actual facility 180 seconds for a total of 600 seconds (10 minutes: Ta = 0.5 minutes, Tb = 9.5 minutes).

The delay time T2 of the HCl concentration measuring instrument (high speed) 15 of the present simulation is calculated by adding the sum of the delay time Ta by the facility and the measurement delay time Tc of the HCl concentration measuring instrument (high speed) (The following equation (15)). The measurement delay time Tc of the HCl concentration measuring instrument (high-speed) 15 whose measurement delay time is shorter than that of the ion electrode type was changed to confirm the behavior (fate).

The addition amount of the differential halftone required by this feedback is calculated based on the addition amount of output Ag1 obtained from the HCl concentration measuring instrument (low speed) 14 and the addition amount of output Ag2 obtained from the HCl concentration measuring instrument (high speed) (Equation (1) above).

[HCl concentration measuring instrument (low speed response, simulation of ion electrode equation)]

T1 = Ta + Tb (11)

T1: Delay time (sec) of the simulation reaction system of HCl concentration measuring instrument (low speed)

Ta: Delay time of facility (sec) [30sec setting]

Tb: Measurement delay time (sec) of HCl concentration measuring instrument (low speed)

Tb = Tb? + Tb? (12)

Tbα: Exhaust gas sampling time (sec) of HCl concentration measuring instrument (low speed)

[390sec setting]

Tbβ: 90% response time (sec) of HCl concentration measuring instrument (low speed)

[180sec setting]

Tb? = 2.3 占? (13)

Yn = Yn-1 + (Xn-Yn-1) / TxTs (14)

τ: Time constant (sec)

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

[0.5sec setting]

Xn: current measuring device input HCl concentration (ppm)

Yn: Current measuring device output HCl concentration (ppm)

Y _n-1 : Measurement device output HCl concentration (ppm) of the last time (before Ts (sec)

[HCl concentration measuring instrument (high-speed response)]

T2 = Ta + Tc (15)

T2: Delay time (sec) of simulation reaction system of HCl concentration measuring instrument (high speed)

Ta: Delay time of facility (sec) [30sec setting]

Tc: Measurement delay time (sec) of HCl concentration measuring instrument (high speed)

A measuring instrument with a short measurement delay time changed only the Tc.

As shown in Fig. 5, the exhaust gas reaction and the BF phase reaction were observed from the PID addition behavior and the HCl occurrence state (Fig. 6) and the result of this simulation reaction system (Fig. 7) The reaction efficiency of HCl was set. The results of this examination are shown in Fig. 6 and Fig. In this facility, the HCl removal efficiency of the exhaust gas was 80%, and the removal efficiency of the BF phase reaction was 65%, which corresponded to the behavior of the actual catalyst and the simulation (FIGS. 6 and 7). Therefore, we performed the following simulation under this condition. In this simulation, the inlet HCl concentration (Hi) at a relatively large fluctuation time was used in order to clarify the control response by the control method.

The results of examination of various control methods in this simulation reaction system are shown below.

Moreover, the average particle diameter of the fine powder bath used in the following Examples 1-12 is 5-30 micrometers. In addition, the HC1 concentration measuring apparatus 14 used in Examples 1-12 is based on the ion electrode method.

[Comparative Example 1]

9, based on the HCl concentration measured only by the HCl concentration measuring instrument (low speed) 14 (9.5 minutes of the measuring machine mechanical measuring delay time) in the simulation, the PID control method "P The control target value SV of the outlet HCl concentration is set to 200 ppm at a ratio of proportional gain = 100%, I = 0.1 seconds, D = 0.1 seconds, an addition amount output lower limit of 200 Kg / h and an addition amount output upper limit of 480 Kg / Feedback control.

FIG. 8 shows the addition amount of the differential bicarbonate and the concentration of HCl in the outlet of the bag filter after treatment with the differential sodium bicarbonate (average, 1 hour average maximum, instantaneous maximum, 1 hour average minimum, and instantaneous minimum). Fig. 10 shows the behavior of the addition amount of the fine base oil and the HCl concentration at the outlet of the bag filter at the time of the present control.

According to the comparative example 1, the maximum value of HCl of the one hour average value which is well used as the outlet rich of the acid gas was 234 ppm and the maximum instantaneous was 416 ppm.

[Comparative Example 2]

In the simulation, control was performed in the same manner as in Comparative Example 1 except that the feedback control was performed based on the HCl concentration measured by the HCl concentration measuring instrument (high speed) 15 (delay time of 2 seconds on the measuring instrument side).

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. Fig. 11 shows the behavior of the addition amount of the fine base oil and the HCl concentration at the outlet of the bag filter during the present control.

It was predicted that the change in the addition amount of the alkaline agent and the change in the outlet HCl concentration would occur instantaneously when the feedback control was performed using only the high-response HCl concentration measuring instrument (high-speed) 15 having a small measuring delay as in Comparative Example 2. However, the hunting due to the addition of the alkaline agent occurred, and the maximum value of HCl was 227 ppm for one hour and 425 ppm for the instantaneous maximum.

[Examples 1-5]

P (proportional gain) = 100% and I = 0.1 (proportional gain) were calculated based on the HCl concentration measured by the HCl concentration measuring instrument (low speed) 14 (measuring instrument measurement delay time 9.5 minutes in total) HCl concentration measurement device (high-speed) measurement device with feedback control by setting the control target value (SV) of the HCl concentration at the outlet at 200ppm at the initial value of D = 0.1 sec, the addition amount output lower limit of 200 Kg / h and the addition amount output upper limit of 480 Kg / ) Based on the HCl concentration measured by (15), the control target value (SV) of the outlet was set to 200 ppm at the same setting, and the addition output of the feedback control was added and feedback control was performed.

The measuring instrument measurement delay time of the HCl concentration measuring instrument (high-speed) 15 was 2 seconds for Example 1, 1 minute for Example 2, 3 minutes for Example 3, 5 minutes for Example 4, 5 was 7 minutes.

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. 12 and 16 show the behavior of the amount of fine powder bath addition and the bag filter outlet HCl concentration at the time of this control.

According to Examples 1 to 5, stable processing of acid gas can be performed by calculating the addition output calculated based on the measurement signals of at least two acid gas measuring devices having different measurement delay times, and calculating the amount of alkali agent added. .

Example 1 is a result of feedback control using a combination of a measuring instrument measurement delay time (9.5 minutes) and a measuring instrument measurement delay time of 2 seconds (instantaneous) in an HCl system. However, unlike Comparative Example 1 and Comparative Example 2, It was possible to add an appropriate alkali agent according to the target value of the HCl concentration. In addition, it was found that the control of the chemical solution injected under the condition of the outlet HCl concentration of 193 ppm for one hour and the maximum of 272 ppm for the instantaneous HCl concentration was small and the control of the control was easy.

Also, the measuring instrument measurement delay time is improved in comparison with Comparative Example 1 and Comparative Example 2 even when the measurement delay time is 7 minutes (Example 5). However, as for management of the chemical liquid injection, it is effective to treat the acid gas stably for a short period of time, so that it is preferably 7 minutes or less, more preferably 3 minutes or less.

[Example 6]

Based on the HCl concentration measured by the HCl concentration measuring instrument (low speed) 14 (measuring instrument measuring delay time 9.5 minutes) in the above simulation, the output power was limited to 50% of the output power of the feedback control and the HCl concentration measuring instrument High speed) (15) (measurement delay time of measuring instrument: 2 seconds) based on the HCl concentration, feedback control was performed without adding any restriction (100%) and feedback control.

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. Fig. 17 shows the behavior of the addition amount of the deionized water and the HCl concentration at the outlet of the bag filter at the time of the present control.

Example 7

Based on the HCl concentration measured by the HCl concentration measuring instrument (low speed) 14 (measuring instrument measuring delay time 9.5 minutes) in the above simulation, the output power was limited to 50% of the output power of the feedback control and the HCl concentration measuring instrument High speed) Based on the concentration of HCl measured by (15) (measuring instrument measurement delay time 2 seconds), feedback control was performed by adding 50% of the output power to the feedback output.

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. FIG. 18 shows the behavior of the addition amount of the fine base oil and the HCl concentration at the outlet of the bag filter during the present control.

Here, as in Examples 6 and 7, the acid gas treatment result when at least one limit is applied to the upper limit of the added output calculated based on the measurement signals of at least two acid gas measuring instruments having different measurement delay times. It demonstrates.

Example 6 is an example in which a limit of 50% is added to the added output calculated from the measurement signal of the HCl concentration measuring instrument (low speed) 14. The seventh embodiment is an example in which a limitation of 50% is added to both of the output power of the HCl concentration measuring instrument (low speed) 14 and the HCl concentration measuring instrument (high speed) 15. In both examples, it was found that the treatment level of HCl was almost equivalent to that of Example 1, and the addition amount of the alkali chemicals could be reduced compared to Example 1 (311 Kg / h) as the addition amount was 271 to 300 Kg / h.

[Example 8]

In this simulation, the 6-second average of the slope of the HCl concentration nearest to the feedback control based on the HCl concentration measured by the HCl concentration measuring instrument (low speed) 14 (measuring instrument measurement delay time 9.5 minutes) (SV) is set to 180ppm (SV-20ppm), and if the 6-second average of the gradient of the closest HCl concentration is negative, the control target value (SV) + 20ppm), the control target value SV was set to 200 ppm at the time of feedback control based on the HCl concentration measured by the HCl concentration measuring instrument (high speed) 15 (measuring instrument measuring delay time 2 seconds) Added control output was added, and feedback control was performed.

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. FIG. 19 shows the behavior of the addition amount of the fine base oil and the HCl concentration at the outlet of the bag filter during the present control.

[Example 9]

In the simulation, a 6-second average of the slope of the closest HCl concentration at the time of feedback control based on the HCl concentration measured at the HCl concentration measuring instrument (low speed) 14 (measuring instrument measurement delay time 9.5 minutes) If the target SV is 180 ppm (SV-20 ppm) and the 6-second average of the gradient of the closest HCl concentration is negative, set the control target SV at 220 ppm SV + 20ppm), the output is limited to 50% and the feedback control based on the HCl concentration measured by the HCl concentration measuring instrument (high speed) (15) (measuring instrument measurement delay time 2 sec) The control target value (SV) was controlled to 200 ppm, and the addition output was added with an output limit of 50%, and feedback control was performed.

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. 20 shows the behavior of the addition amount of the fine dynease and the HCl concentration at the outlet of the bag filter during the present control.

Here, when the gradient of the HCl concentration nearest to the target is fixed based on the measurement signals of at least two acid gas measuring instruments having different measurement delay times as in Examples 8 and 9, the control target value is lowered, In the case where the gradient of the closest HCl concentration is negative, the result of the acid gas treatment when the control target value is increased and the addition output by feedback is made in advance will be described.

Example 8 shows the addition output calculated by changing the control target value SV when calculating based on the measurement signal of the HCl concentration measuring instrument (low speed) 14 and the addition output calculated by changing the control target value SV Based on the measurement signal, the addition output calculated with the control target value of 200ppm is added and feedback control is performed. In Example 9, on the basis of the measurement signals of the HCl concentration measuring instrument (low speed) 14 and the HCl concentration measuring instrument (high speed) 15 in Example 8, a limit of 50% The feedback control is added.

In Example 8, it was found that the instantaneous maximum HCl was reduced from 272 ppm to 248 ppm, especially at an addition amount almost equal to that of Example 1, and the peak correspondence was enhanced by this control method. Further, in Example 9, the peak correspondence was enhanced to 255 ppm in terms of instantaneous maximum as compared with Example 1, and the addition amount was reduced from 315 Kg / h to 279 Kg / h in Example 8, okay.

Hereinafter, Examples 10 to 12 will be described. In Examples 10 to 12, the control by the step control method is performed in place of the PID control method.

The outline of the step control method will be described here. Unlike the PID control method, the step method is a control method that specifies the output stepwise according to the HCl concentration at the outlet. Referring to the tenth embodiment (Fig. 21), the HC1 concentration outputs the control output step by step between the LO and LM1 between the SV control target value (control output starting concentration (above the output lower limit))-SM1. The control output set to LM2 is output between HM1 and SM2, and the output of LH (upper limit of control output) is above SM2. In normal PID control mode, there is no output limitation and only LO and LH are set. In addition, SVA1 and SVA2 are used to correct the table for determining the HCl concentration and control output used in the control operation (control operation) by the HCl gradient. When the HCl gradient is fixed, the SVA1 is subtracted from the HCl concentration used in the calculation, When negative, SVA2 was added to the concentration of HCl used in the calculation. Accordingly, the control output calculated when the same HCl concentration is input becomes larger than the control output value when the control output value when the value of the HCl gradient is larger (the tendency of the acid gas concentration to increase) is smaller than the value of the HCl gradient Format.

The addition amount (Ag) of the fine base powder is obtained from the above formula (1).

[Example 10]

In the above simulation, when feedback control is performed on the basis of the HCl concentration measured by the HCl concentration measuring instrument (low speed) 14 (measuring instrument measuring delay time 9.5 minutes), the control target value And the addition output controlled by setting the concentration at which the control output of the HCl concentration measuring device is added to the lower limit of the output to be 200 ppm and the HCl concentration measuring device (high speed) 15 (measuring device measuring delay time 2 seconds) In the feedback control based on the concentration, in the step-type control, the control target value was set to 200 ppm in the same manner, and the addition output was controlled so as to be added, and feedback control was performed (see Figs. 8 and 21).

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. Fig. 22 shows the behavior of the addition amount of the deionized water and the HCl concentration at the outlet of the bag filter at the time of the present control.

Example 11

In the simulation, when the feedback control is performed based on the HCl concentration measured by the HCl concentration measuring instrument (low speed) 14 (measuring instrument measuring delay time 9.5 minutes), in the stepwise control, (SV + 20ppm) when the 6-second average of the slope is equal to the control target value (SV + 20ppm) when the 6-second average of the slope of the HCl concentration nearest to the target is less than 180ppm 20 ppm), on the basis of the HCl concentration measured by the HCl concentration measuring instrument (high-speed) 15 (measuring instrument measuring delay time 2 seconds), the control target value The addition output was controlled by setting 200 ppm in the same manner, and feedback control was performed (see Figs. 8 and 23).

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. Fig. 24 shows the behavior of the addition amount of the deionized water and the HCl concentration at the outlet of the bag filter at the time of the present control.

Example 12

In the simulation, in the feedback control based on the HCl concentration measured by the HCl concentration measuring instrument (low speed) 14 (measuring instrument measurement delay time 9.5 minutes), in the stepwise control, the gradient of the closest HCl concentration (SV + 20ppm) when the control target value (SV) is 220ppm (SV + 20ppm) when the 6 second average of the slope of the nearest HCl concentration is less than the control target SV ), And the feedback control based on the HCl concentration measured by the HCl concentration measuring device (high-speed) (15) (measuring device measuring delay time 2 sec) , The control target value was set to 200 ppm in the same manner, and the addition output was controlled by adding 50% of the output power to the addition output, and feedback control was performed (Figs. 8 and 23 article).

The addition amount of the fine base powder and the HCl concentration at the outlet of the bag filter after treatment with the neutralization treatment are shown in Fig. Fig. 25 shows the behavior of the addition amount of the deionized water and the HCl concentration at the outlet of the bag filter at the time of the present control.

Embodiments 10 to 12 are embodiments in which the feedback is controlled by the step method. The step method is a method for preventing addition loss by setting a plurality of output limits at the upper limit value of the addition output.

As a result of controlling the step control method as a base, compared with Comparative Example 1 and Comparative Example 2 (1 hour average of 227 to 234 mm, instantaneous maximum of 416 to 425 mm), Examples 10 to 12 had an average hourly value of 206 to 218 mm and an instantaneous maximum. It shows stable acid gas treatment performance of 253 ~ 274mm. Compared to Examples 1, 8, and 9 (1 hour average 193-205 mm, instantaneous maximum 248-272 mm) controlled based on PID, the acidity was higher at 1 hour average (206-218 mm, 253-274 mm). The gas management performance was slightly inferior, but the addition amount was found to be reduced to 272-297 Kg / h relative to 279-315 Kg / h.

The present invention can be applied to both the PID method and the step method. From this result, it is considered that the PID method is effective when the stable processing of the acid gas is desired, and the step method is effective when the addition amount reduction effect is desired.

In the following description, Comparative Example 3 and Examples 13 to 16, which are the practical performance review results, will be described for the configuration of the acid gas treatment system 2 used in Comparative Example 3 and Examples 13 to 16. FIG.

Fig. 26 is a block diagram showing the construction of an acidic gas treatment system 2 for adding a differential boiling tank to HCl which is an exhaust gas in an incineration facility.

The acid gas treatment system 2 includes a control device 21, a differential particle counter addition device 22, a differential particle counter addition device 26, a bag filter 23, an HCl concentration measuring device (ion electrode method) And an HCl concentration measuring instrument (laser system) 25. The control device 11 controls the feed rate of the additive amount of the differential halftone control signal based on the HCl concentration measurement signal transmitted from the HCl concentration measuring instrument (ion electrode system) 24 and the HCl concentration measuring instrument (laser system) (PID control method or step method). The differential bead addition device 22 adds a differential bead to the HCl in the exhaust gas based on the output value of the addition amount of the differential bead preparation calculated by the control device 11. [ Further, the differential-dye-adding device 26 adds a certain amount of differential dyeing to HCl in the exhaust gas irrespective of the output value of the additive amount of the differential dyeing trough calculated by the control device 11.

The bag filter 23 removes dust after the reaction of the HCl in the exhaust gas and the differential-salt tank. The HCl concentration measuring instrument (ion electrode method) 24 and the HCl concentration measuring instrument (laser system) 25 are used to measure the concentration of the fine particles (The HCl concentration at the outlet of the bag filter to be described later) is measured after the HCl after the exhaust gas reaction is reacted with the HCl concentration measurement signal to the control device 21.

The control device 21 can appropriately control the control output value of the addition amount of the differentiating salt baffle by repeating this cycle of the feedback control by the acid gas processing system 2.

The HCl concentration measuring instrument (ion electrode system) 24 is longer than the HCl concentration measuring instrument (laser system) 25 in measuring the HCl concentration.

As shown in FIG. 26, the HCl concentration measuring device (the HCl concentration at the outlet of the bag filter) was measured with a HCl concentration measuring instrument (ion electrode System) 24 and an HCl concentration measuring instrument (laser system) 25 are preferably provided. This is because the differential neutralizing tank remaining after the reaction with HCl in the exhaust gas is accumulated on the bag filter 23 and the accumulated differential neutralizing tank reacts with the HCl after the exhaust gas reaction so that the HCl concentration can be measured more accurately Because.

[Comparative Example 3]

In an industrial waste incinerator, a laser type HC1 concentration measuring instrument (HP-1, manufactured by Kyoto Electronics Co., Ltd.) was installed between a thermo-thermal tower outlet and a bag filter, and the inlet HC1 concentration was measured. In addition, based on the signal measured by an HCl concentration measuring device (HL-36N manufactured by Kyoei Electronics Co., Ltd.) at the outlet of the bag filter, feedback control was performed with an oxygen conversion value (oxygen conversion value) for managing the emission reference value. In addition, although carried out by adding the feedback output added (SV180ppm) by the SO ₂ concentration in the outlet of the signal output by the addition of HCl concentration, did not generate the SO ₂ in the present Facilities.

Further, as the alkali agent for treating the acid gas, an 8-μm fine powder (Hyperiser B-200, manufactured by Kurita Kogyo Co., Ltd.) was added by the above-described feedback control. In the case of the addition of alkaline agent, two units are used because of the maximum amount of additive. One unit is added at a fixed amount of 180 kg / h and one unit is set at a lower limit of 20 Kg / h upper limit of 300 Kg / h and a PID control setting P (Proportional gain) = 100%, I = 0.1 seconds, D = 0.1 seconds ".

FIG. 27 shows the HCl concentration at the inlet of the bag filter, the HCl concentration at the outlet of the bag filter, and the addition amount of the differential salt tank (sum of two addition devices). Fig. 28 shows the behavior of the addition amount of the deionized water and the HCl concentration at the outlet of the bag filter at the time of the present control.

As shown above, the addition of the deuterium salt was roughly done and the HCl concentration at the outlet was largely changed, which was wasteful control.

[Example 13]

In the same facility, the HCl concentration signal (oxygen conversion value) measured by an ion electrode type HCl concentration measuring apparatus (HL-36N manufactured by Kyoto Electronics Industry Co., Ltd.) at the outlet of the bag filter and the HCl concentration measuring apparatus (Oxygen conversion value) measured by an HCl concentration meter (KLA-1 manufactured by Kyoto Electronics Industry Co., Ltd.). In addition, the same feedback, the addition output (SV180ppm) by the SO ₂ concentration in the exit signal, but carried out by adding the added output by the HCl concentration and did not generate the SO ₂ in the present Facilities.

In the same manner, one of the addition devices is set to a fixed amount of 180 kg / h, and one PID control setting P (proportional gain) = 100% and a lower limit of 20 Kg / h upper limit 300 Kg / 0.1 second and D = 0.1 second ", adding a limitation of 67% to both of the addition outputs calculated from the measurement signals of both the ion electrode type and laser type measurement devices, and adding 1 hour Feedback control was performed by adding 300 Kg / h for 213 ppm or more to 215 ppm of the facility management concentration of the average value.

FIG. 27 shows the HCl concentration at the inlet of the bag filter, the HCl concentration at the outlet of the bag filter, and the addition amount of the differential salt tank (sum of two addition devices). Fig. 29 shows the behavior of the addition amount of the deionized water and the HCl concentration at the inlet of the bag filter at the time of the present control.

[Example 14]

As in Example 13, the HCl concentration signal (oxygen conversion value) measured by the HCl concentration measuring instrument of the ion electrode type at the outlet of the bag filter and the HCl concentration measuring instrument (KLA-1 ) As the HCl concentration signal (oxygen conversion value). In addition, similarly, but it carried out by adding the feedback output is added (SV180ppm) by the SO ₂ concentration in the outlet signal to the addition output by the HCl concentration and did not generate the SO ₂ in the present Facilities.

Further, the control of the addition device under control was carried out under the conditions of "lower limit of 20 Kg / h upper limit of 300 Kg / h, PID control setting P (proportional gain) of 100%, I = 0.1 second, D = And addition of 300 Kg / h for an average of 213 ppm or more for one hour was carried out separately from this control.

FIG. 27 shows the HCl concentration at the inlet of the bag filter, the HCl concentration at the outlet of the bag filter, and the addition amount of the differential salt tank (sum of two addition devices). Fig. 30 shows the behavior of the amount of addition of the differentiating salt and the concentration of HCl at the outlet of the bag filter at the time of the present control.

In Examples 13 and 14, variations in the HCl concentration at the outlet are smaller than those in Comparative Example 3, and control with less addition loss can be performed. Further, the amount of the alkali agent to be added is different according to the inlet HCl concentration, and it is generally regarded as equivalent amount indicating the addition amount per inlet HCl concentration. It was found that the added equivalents were reduced as compared with the comparative examples, and the addition was efficiently carried out.

Examples 15 and 16 are described below. In Embodiments 15 and 16, the PID control method is replaced by a step control method. The outline of the step control method is the same as that described in the tenth embodiment.

[Example 15]

In the same facility, the HCl concentration signal (oxygen conversion value) measured by an ion electrode type HCl concentration measuring apparatus (HL-36N manufactured by Kyoto Electronics Industry Co., Ltd.) at the outlet of the bag filter and the HCl concentration measuring apparatus (Oxygen conversion value) measured by an HCl concentration meter (KLA-1 manufactured by Kyoto Electronics Industry Co., Ltd.). In addition, similarly, but it carried out by adding the feedback output is added (SV180ppm) by the SO ₂ concentration in the outlet signal to the addition output by the HCl concentration and did not generate the SO ₂ in the present Facilities.

In addition, one addition unit is added in a fixed amount of 180 kg / h, one unit is added in a stepwise manner by adding a limit of 50% to both of the addition outputs calculated from the measurement signals of both measuring units, When the average for one hour was 213 ppm or more, feedback control was performed to add 300 Kg / h (see Figs. 27 and 31).

FIG. 27 shows the HCl concentration at the inlet of the bag filter, the HCl concentration at the outlet of the bag filter, and the addition amount of the differential salt tank (sum of two addition devices). 32 shows the behavior of the addition amount of the deionized water and the HCl concentration at the inlet and outlet of the bag filter in the present control.

Embodiment 15 is a step-by-step embodiment. The fluctuation of the HCl concentration at the outlet is smaller than that in Comparative Example 3, so that the control with less addition loss can be performed. This added equivalent weight is reduced as compared with the comparative example, so that it is efficiently added.

[Example 16]

In the same facility, the HCl concentration signal (oxygen conversion value) measured by an ion electrode type HCl concentration measuring instrument (HL-36N manufactured by Kyoto Electronics Industrial Co., Ltd.) at the outlet of the bag filter and the HCl concentration measurement And the feedback control was performed with the HCl concentration signal (oxygen conversion value) measured with a device (KLA-1 manufactured by Kyoto Electronics Industry Co., Ltd.). In addition, similarly, but it carried out by adding the feedback output is added (SV180ppm) by the SO ₂ concentration in the outlet signal to the addition output by the HCl concentration and did not generate the SO ₂ in the present Facilities.

In addition, one addition device was prepared by adding 170 kg / h of a high-reacted slaked lime having a specific surface area of 30 m ² / g or more (manufactured by Okudama Kogyo Co., Ltd., Tamakaru Kogyo Co., Ltd.) A feedback control was performed in which a 50% limit was added to both of the addition outputs calculated from the measurement signals of both measuring devices in a stepwise manner and 300 Kg / h was added for an hour average value of 213 ppm or more apart from this control (See Figs. 27 and 31).

The HCl concentration at the inlet of the bag filter, the HCl concentration at the outlet of the bag filter, and the addition amount of the differential salt tank are shown in Fig. Fig. 33 shows the behavior of the addition amount of the differential salt tank and the HCl concentration at the outlet of the bag filter at the time of the present control.

Example 16 is an embodiment utilizing a comparatively industrially inexpensive calcined liquor and a fine particle liquor. In this method, a stable treatment effect of the acid gas was also obtained. It is an industrially effective method because it reduces the cost of treating acid gas by using cheap slaked lime.

1: Acid gas treatment system
11: Control device
12: Deionized water addition device
13: Bag filter
14: HCl concentration measuring instrument (low speed)
15: HCl concentration measuring instrument (high speed)

Claims (11)

An acid gas concentration measuring instrument for measuring an acid gas concentration after adding an alkaline agent to a combustion exhaust gas containing an acid gas and collecting dust. A method of treating acid gas for feeding back control of the amount of alkali agent added based on a measurement signal of
Measuring acid gas concentrations of the same type by a plurality of acid gas concentration measuring instruments having different measurement delay times;
A process of calculating, by a feedback calculation, an output value of the added amount of the alkaline agent based on the measurement signals of the plurality of acidic gas concentration measuring apparatuses;
Acid gas treatment method provided.
The method of claim 1,
Wherein the step of calculating the addition amount output value by feedback calculation comprises:
Calculating an upper limit value (upper limit value) of a plurality of addition amount output values which are respectively calculated based on the plurality of measurement signals;
A step of calculating an addition amount output value having a value smaller than the upper limit value with respect to at least one upper limit value among the calculated upper limit values
Wherein the acidic gas is treated by the acidic gas.
The method of claim 1,
Wherein the step of calculating the addition amount output value by feedback calculation comprises:
Setting a range of inclinations of at least two acid gas concentrations, setting a control target value of an acid gas concentration for each of the at least two inclination ranges,
A step of calculating an addition amount output value of the alkali agent based on at least the control target value for each range of the measurement signal and the inclination
More equipped,
In the step of setting the control target value, the control target value set when the inclination range of the acidic gas concentration is large is smaller than the control target value set when the inclination range of the acidic gas concentration is small. Acid gas treatment method.
The method of claim 2,
Wherein the step of calculating the addition amount output value by feedback calculation comprises:
Setting a range of inclination of at least two acid gas concentrations;
Setting a control target value of the acidic gas concentration for each of the at least two ranges of inclination;
A step of calculating an addition amount output value of the alkali agent based on at least the control target value for each range of the measurement signal and the inclination
More equipped,
In the step of setting the control target value, the control target value set when the inclination range of the acidic gas concentration is large is smaller than the control target value set when the inclination range of the acidic gas concentration is small. Acid gas treatment method.
The method of claim 1,
Wherein the step of calculating the addition amount output value by feedback calculation comprises:
Further comprising the step of setting at least one new upper limit value of the addition amount output value corresponding to the acid gas concentration between a lower limit value (lower limit value) and an upper limit value (upper limit value) of the addition amount output value calculated on the basis of the measurement signal Characterized in that the acidic gas is treated by a method comprising the steps of:
The method of claim 2,
Wherein the step of calculating the addition amount output value by feedback calculation comprises:
Further comprising the step of setting at least one new upper limit value of the addition amount output value corresponding to the acid gas concentration between the lower limit value and the upper limit value of the addition amount output value calculated on the basis of the measurement signal .
The method of claim 3,
Wherein the step of calculating the addition amount output value by feedback calculation comprises:
Further comprising the step of setting at least one new upper limit value of the addition amount output value corresponding to the acid gas concentration between the lower limit value and the upper limit value of the addition amount output value calculated on the basis of the measurement signal .
5. The method of claim 4,
Wherein the step of calculating the addition amount output value by feedback calculation comprises:
Further comprising the step of setting at least one new upper limit value of the addition amount output value corresponding to the acid gas concentration between the lower limit value and the upper limit value of the addition amount output value calculated on the basis of the measurement signal .
The method according to any one of claims 1 to 8,
A method for treating acid gas, characterized in that the alkaline agent is a fine powder bath with an average particle diameter of 5 to 30 µm.
10. The method of claim 9,
Characterized in that an alkaline agent different from the alkali in the fine powders is used in combination.
The method of claim 10,
The other alkaline agent is selected from the group consisting of calcium hydroxide, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, sodium sesquicarbonate, natural soda ) And at least one alkali agent selected from the group consisting of a crude soda (crude soda).

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