TW201524584A - Method for treating acidic gas - Google Patents

Abstract

A purpose of the disclosure is to provide a method for treating an acidic gas through a new control way for reducing over-addition of alkali agents. The method performs a stable treatment of acidic gas with less production of acidic gas concentration peaks in exports in a feedback form which does not require introducing new and valuable acidic gas measuring devices. The method for treating the acidic gas of the disclosure is to add an alkali agent in an exhaust gas including the acidic gas and to perform a feedback control to an additive amount of the alkali agent based on measured signals of an acidic gas concentration measuring equipment which measures the concentration of the acidic gas after powder dusts are collected collecting powder dusts. In addition, the method includes a step of calculating a basic additive amount obtained by multiplying an average additive amount which at least corresponds to an average time with a coefficient not larger than one and a step of calculating an output value of the additive amount of the alkali agent by a feedback calculation based on the calculated basic additive amount.

Description

Acid gas treatment method

The present invention relates to a method for treating acid gases such as harmful hydrogen chloride or sulfur oxides generated in combustion equipment such as municipal waste waste incinerators, industrial waste incinerators, power generation boilers, carbonization furnaces, and private factories. Specifically, it is a method for effectively controlling the amount of addition of an alkali agent for treating an acid gas.

The exhaust gas containing harmful hydrogen chloride or sulfur oxide is treated with an alkali agent such as calcium hydroxide or sodium hydrogencarbonate, and then dedusted by a dust collector such as a filter bag (BF, bag filter), and then discharged from the chimney. On the other hand, the fly ash collected by the dust collector contains harmful heavy metals such as Pb and Cd, and these harmful heavy metals are stabilized and then subjected to burying treatment.

As an alkali agent for treating an acid gas, that is, sodium bicarbonate processed to 5 μm to 30 μm by fine powder, it has higher reactivity than calcium hydroxide, and can stably treat acid gas, and has less unreacted components, and can be reduced. The amount of buried treatment is a more effective method for reducing environmental load. In addition, the heavy metal treatment method is usually a method of insolubilizing treatment by a chelate compound such as diethyldithiocarbamate, and in the short term, the heavy metal fixing effect is high, but the residual remains below. Problem: Due to the pH drop caused by acid rain and the oxidative self-decomposition of the chelate in the final treatment field, heavy metals such as lead are dissolved again. On the other hand, the fixation with a heavy metal of a phosphoric acid compound such as phosphoric acid changes to a form of hydroxyapatite which is an inorganic mineral, so that the long-term stability in the final treatment field is excellent, and from the viewpoint of environmental protection, A very high value processing method. Further, the method of treating the fly ash treated with the above-mentioned fine powder of sodium hydrogencarbonate by a heavy metal fixing agent such as phosphoric acid is an effective method for reducing the environmental load.

However, the addition of an alkali agent such as calcium hydroxide or sodium hydrogencarbonate to treat an acid gas such as hydrogen chloride or sulfur oxide can not only reduce the cost of acid gas treatment, but also reduce the unreacted component of the alkali agent and reduce the fly. The effect of the burial throughput of ash.

The amount of the alkali agent to be treated for an acid gas such as hydrogen chloride or sulfur oxide is usually also based on the HCl concentration measured by the ion electrode type hydrogen chloride measuring device provided in the subsequent stage of the filter bag, by proportional integral differentiation (ProportionIntegralDifferential, The PID) control device performs feedback control. However, in a combustion apparatus such as an incineration facility, a device for measuring the acid gas concentration at the inlet is generally not provided, and the PID control parameter is set and the control output is adjusted in a state where the inlet is not changed. However, the PID control device has five setting items of P, I, D, the addition amount (output) lower limit, and the addition amount (output) upper limit, and the set values of the respective items are combined to determine the control output value, so the appropriate addition control is studied. It takes a lot of time. Therefore, generally, when the setting of the PID control device exceeds the control target value (SV), most devices implement control that greatly increases the amount of addition.

However, the control output of the normal PID control device sets only a single upper limit. For example, when the control target value (SV) of the HCl concentration is set to 40 ppm, the single upper limit of the control output is limited to a concentration of 40 ppm or more. The addition of an alkaline agent results in an excessive addition of an alkaline agent. Further, the above feedback control is affected by the measurement delay of the acid gas measuring device. The HCl concentration at the outlet of the filter bag is usually measured by an ion electrode method (for example, HL-36 manufactured by Kyoto Electronics Industry Co., Ltd.), and the sulfur oxide concentration is measured by an infrared absorption method (for example, NSA-3080 manufactured by Shimadzu Corporation). The sampling time including the sample exhaust gas and the response time of the measuring device have a large measurement delay of 5 minutes to 10 minutes. This measurement delay causes a delay in the addition of the alkali agent, causes poor treatment of the acid gas, and causes excessive addition of the alkali agent.

In order to solve this problem, various control methods are studied. Patent Document 1 proposes to further add "P+PID Control" of P to a normal PID control formula. This proposal considers that it is difficult to cope with the sudden generation of acid gas by the usual PID control. Further, in Patent Document 2 and Patent Document 3, it is proposed to control the feedforward control of the amount of the alkali agent added according to the acid gas concentration of the inlet and the feedback control of the amount of the alkali agent added according to the acid gas concentration after the alkali treatment. The combination of control methods. It is considered that this control method is intended to suppress the effect of excessive addition of feedback control, and to obtain an effect of stabilizing the acid gas and reducing the excessive addition of the alkali agent.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-113327

[Patent Document 2] Japanese Patent Laid-Open No. Hei 10-165752

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2006-75758

However, in Patent Document 1, the acid gas suddenly generated at the inlet can be dealt with to some extent, but the upper limit value and the lower limit value of the control output are individually set. Therefore, in the equipment where the fluctuation of the inlet acid gas concentration is intense, Since the hunting is caused by the chemical, it is difficult to achieve a stable and stable treatment of the peak value of the outlet acid gas concentration. Further, irrespective of the measurement delay of the above-described measuring device, it is not possible to cope with the processing failure of the acid gas due to the delay in the addition of the alkaline agent due to the measurement delay. Further, Patent Document 2 and Patent Document 3 propose that in a combustion apparatus such as an incineration facility, only a device that measures the acid gas concentration of the outlet is dominant, and in order to implement this control method, it is necessary to introduce a new acid gas concentration of the measurement inlet. High-priced acid gas measuring device.

In view of the foregoing prior circumstances, it is an object of the present invention to provide an acid gas treatment method which produces a less stable acid gas at the peak of the acid gas concentration at the outlet without feedback of a new high-priced acid gas measuring device. The treatment is followed by a new control method to reduce the excessive addition of the alkaline agent.

(1) An acid gas treatment method in which an alkali agent is added to a combustion exhaust gas containing an acid gas, and a measurement signal of an acid gas concentration measuring device that measures an acid gas concentration after dust collection is added to an alkali agent. Performing feedback control includes: calculating a coefficient that is at least equal to an average addition amount (for example, 5 minutes, 15 minutes, 30 minutes, 1 hour, 3 hours, 6 hours, and the like described later) multiplied by 1 time or less (for example, 95%, 90%, 80%, as described later a step of adding a base amount obtained by 70%, 50%, or the like; and a step of calculating an output value of the addition amount of the alkali agent by a feedback calculation based on the calculated base addition amount.

In the PID control mainly used in the current situation, the addition of the output can only set a single upper limit and 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, in order to reduce the addition of the alkaline agent, the lower limit of the control output is added, and the control target is added. When the value (SV) is 40 ppm or more, in order to increase the addition of the alkali agent, the upper limit of the control output is added, and the alkaline agent thus added is improperly added (excessive addition or insufficient addition), and the HCl concentration at the outlet is largely changed. And become the cause of excessive addition of the alkaline agent.

On the other hand, as in the invention of (1), 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 base is calculated by the feedback calculation based on the calculated basic addition amount. When the addition amount of the agent is added, it is possible to prevent the improper addition of the alkali agent, and it is possible to achieve a stable treatment with a small fluctuation in the concentration of the outlet HCl to be treated, and it is also possible to reduce the result of the appropriate addition of the invention according to (1). The amount of the alkali agent added.

The invention of (1) is characterized in that, as a factor relating to the HCl concentration of the inlet which was previously unconsidered in the feedback control, focusing on the past average addition amount, a coefficient obtained by multiplying the average addition amount by a factor of 1 or less is used. The amount of base added is used as a controlling factor. In this way, it is not necessary to increase the lower limit and the upper limit in a large amount, and the base additive is added, and the base addition amount obtained by multiplying the past average addition amount which is a basis for the addition amount by a factor of 1 or less is used. On the basis of this, the amount of addition of the alkaline agent is calculated by feedback control such as PID. Therefore, the addition of the alkali agent is less changed, and the addition of the alkali agent itself is suppressed (excessive amount The disorder caused by the addition and the insufficient addition can be achieved by appropriately adding the amount of addition, and the stabilization treatment of the acid gas with less variation can be realized.

(2) The method for treating an acid gas according to (1), wherein in the step of calculating the addition amount output value by the feedback calculation, the calculated base addition amount is used as an output value of the addition amount of the alkaline agent. Lower limit value (for example, LO to be described later: lower limit of addition amount).

According to the invention of (2), by using the base addition amount as the lower limit value of the addition amount output value, based on the base addition amount, the excess amount and the shortage of the addition amount are adjusted by the previous feedback calculation, so that the base can be used. The addition of the agent is appropriate to effectively treat the acid gas.

Further, the average time of the average addition amount is not particularly limited, and is preferably an average value of the moving average of the applied amount, and is preferably applied at an average time of 5 minutes or more and 15 hours to 24 hours. Further, the coefficient defined by the amount of base addition is preferably 1 time or less. When the coefficient of one time or more is used, although the stabilization treatment of the acid gas can be achieved, the decrease in the amount of addition accompanying the decrease in the concentration of the inlet acid gas is hindered, and thus the addition is excessive. The base addition amount may be 1 time or less (a coefficient of 100% or less) of the average addition amount, and particularly preferably 0.5 times to 0.95 times (50% to 95%), particularly 0.7 times to 0.9 times (70% to 90%). ).

(3) The method for treating an acid gas according to (1) or (2), wherein the step of calculating the addition amount output value by the feedback calculation further comprises: setting a range of a slope of at least two acid gas concentrations (for example, a step in which the average of the slope of the closest HCl concentration described later is a positive range and a negative range, etc.), and an acid gas is set for each of the ranges of the at least two slopes a step of controlling the target value of the concentration (for example, 180 ppm or 220 ppm in Example 8 to be described later); and calculating the output value of the addition amount of the alkaline agent based on at least the control target value of each of the measurement signal and the range of the slope In the step of setting the control target value, when the range of the slope of the acid gas concentration is large (for example, the 6 second average of the slope of the closest HCl concentration to be described later is positive (when the acid gas concentration is increased)) The set control target value is smaller than the control target set when the range of the slope of the acid gas concentration is small (for example, when the average of the slope of the closest HCl concentration described later is negative (when the acid gas concentration is lowered)) value.

According to the invention of (3), when the range of the slope of the acid gas concentration at the outlet of the filter bag is large (when the acid gas concentration is increased), the acid gas concentration is smaller than when the range of the slope is small (when the acid gas concentration is lowered) Since the control target value is decreased, the output value of the alkali agent addition amount when the acid gas concentration is increased can be increased as compared with when the acid gas concentration is lowered. Therefore, compared with the current state control, the timing of adding the alkaline agent at the time of increasing the acid gas concentration can be accelerated, and the processing failure of the acid gas due to the measurement delay of the acid gas measuring device can be improved.

On the other hand, the amount of the alkali agent added when the acid gas concentration is lowered can be reduced as compared with the case where the acid gas concentration is increased. Therefore, when the acid gas concentration is decreased, the amount of the alkali agent can be rapidly decreased, and the acid gas measuring device can be lowered. The excessive delay caused by the measurement delay.

(4) The method for processing an acid gas according to any one of (1) to (3), wherein the step of calculating the addition amount output value by the feedback calculation further comprises the step of: calculating according to the measurement signal Lower limit value of the added amount output value (for example, LO of Table 2, Table 3, and Table 5 to be described later) and upper limit value (example) One or more of the acid gas concentrations (for example, BF outlet HCl concentrations in Tables 2, 3, and 5 to be described later) are set between LH [control output upper limit] in Tables 2, 3, and 5, which will be described later. A new upper limit value of the added amount output value (for example, LM1 [output limit 1] and LM2 [output limit 2] of Table 2, Table 3, and Table 5 to be described later). In the normal feedback calculation, the upper limit of the output is only one. If the acid gas concentration is equal to or higher than the control target value, the alkali agent may be added to the upper limit regardless of the acid gas concentration at the inlet, thereby causing excessive addition.

On the other hand, according to the invention of (4), the restriction of the control output corresponding to the current acid gas concentration is applied between the lower limit value and the upper limit value of the added amount output value, and the acid gas concentration can be used. The appropriate addition of the alkali agent is achieved in size, and the amount of addition can be reduced.

(5) The method for treating an acid gas according to any one of (1) to (4), wherein, in the step of calculating the base addition amount, 0.5 of an average addition amount when the moving average time is 5 minutes or longer The ratio of ~0.95 times is set as the base addition amount.

As described above, the average time of the average addition amount is not particularly limited, and it is effective to apply an average value of the moving average or the like of the added amount, and it is preferably applied at an average time of 5 minutes or more and 15 hours to 24 hours or so. . Further, the coefficient defined by the amount of base addition is preferably 1 time or less. When the coefficient of one time or more is used, although the stabilization treatment of the acid gas can be achieved, the decrease in the amount of addition accompanying the decrease in the concentration of the inlet acid gas is hindered, and thus the addition is excessive. The base addition amount may be 1 time or less (a coefficient of 100% or less) of the average addition amount, and particularly preferably 0.5 times to 0.95 times (50% to 95%), particularly 0.7 times to 0.9 times (70% to 90%). ).

Therefore, according to the invention of (5), the stabilization treatment of the acid gas can be performed and the excessive addition of the alkali agent can be prevented.

(6) The method for treating an acid gas according to any one of (1) to (5), wherein the step of calculating an additive amount output value by a feedback operation further comprises: using hydrogen chloride according to the feedback operation The step of calculating the addition amount of the alkali agent by the two outputs of the control output of the concentration calculation and the control output calculated based on the sulfur oxide concentration.

In the combustion equipment of industrial waste incinerators or private factories, in most cases, hydrogen chloride and sulfur oxides are produced at a high concentration. In this case, both of hydrogen chloride and sulfur oxide are treated, and for example, a control output obtained based on the hydrogen chloride concentration of the hydrogen chloride concentration measuring device provided in the subsequent stage of the filter bag, and a sulfur oxide concentration are obtained. The control outputs are added, and the two acid gases of hydrogen chloride and sulfur oxide are stably treated.

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

(7) The method for treating an acid gas according to any one of (1) to (6), wherein the step of calculating an addition amount output value by a feedback operation further includes: according to the hydrogen chloride concentration and / or the average value of the sulfur oxide concentration is a step of calculating the output value of the addition amount of the alkali agent.

However, the discharge concentration of the acid gas is managed by an average value of one hour of each acid gas concentration (hydrogen chloride concentration, sulfur oxide concentration). The control target value (SV) is usually set for control, but the control target value is merely a target, and there are cases where the concentration exceeds the target value of the controlled result. In particular, the reduction in addition amount is contrary to the stabilization of acid gas. So, the more you want to reduce the amount of addition, the greater the risk that the 1-hour average will exceed the management value. In this case, when the acid gas concentration reaches a concentration equal to or higher than the one-hour average management value or close to the one-hour average management value, the addition amount can be reduced and the acid gas can be obtained by adding a large amount of an alkali agent (predetermined by a certain fixed addition amount). The stable handling can coexist with a high degree of peace of mind.

Therefore, according to the invention of (7), the output value of the addition amount of the alkali agent is calculated from the average value of the hydrogen chloride concentration and/or the sulfur oxide concentration, so that the reduction in the amount of addition and the stabilization of the acid gas can be achieved. control.

(8) The method for treating an acid gas according to any one of (1) to (7) wherein the alkali agent is a fine powder of sodium hydrogencarbonate having an average particle diameter of 5 μm to 30 μm.

The alkali agent used in the present invention is not particularly limited. In particular, the average particle diameter of the reaction with the acid gas is adjusted to a fine powder of sodium bicarbonate of 5 μm to 30 μm, and the control responsiveness is good, and the performance of the control method of the present invention can be effectively exhibited. In addition, calcium hydroxide can also be used. In this case, even if it is JIS-specific calcium hydroxide, it is possible to exhibit the performance of the present invention by using calcium hydroxide having a high specific surface area of, for example, 30 m ² /g or more having a high reactivity with an acid gas. .

(9) The method for treating an acid gas according to (8), wherein another alkali agent different from the above-mentioned fine powder sodium hydrogencarbonate is used in combination.

The alkaline agent which exerts the effect of the present invention is not particularly limited. The alkali agent other than the fine powder of sodium hydrogencarbonate may, for example, be calcium hydroxide, sodium carbonate, potassium hydrogencarbonate, potassium carbonate, sodium sesquicarbonate, natural soda, sodium hydroxide, potassium hydroxide, magnesium oxide or magnesium hydroxide. Further, when the alkali agent is a powder, it is preferably a fine powder having a particle diameter of at least 30 μm, particularly 5 μm to 20 μm, which is highly reactive with an acid gas. Coping By using a pre-adjusted particle size, the pulverizing equipment can be placed on site, and the alkalinity agent having a coarse particle size is pulverized at the site. Further, it may be carried out by a slurry or an aqueous solution obtained by dissolving each alkali agent in water.

(10) The method for treating an acid gas according to (9), wherein the other alkali 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 in the group consisting of crude sodium hydrogencarbonate.

It is also an economically effective method to use an inexpensive alkaline agent different from the alkaline agent for controlling the present invention. The alkali agent to be used in combination is not limited, and an inexpensive alkali agent which is usually used may, for example, be calcium hydroxide, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, sodium sesquicarbonate, natural soda or crude sodium hydrogencarbonate.

According to the present invention, it is possible to provide an acid gas treatment method in which a peak of an acid gas concentration at an outlet is generated in a feedback form in which a new high-priced acid gas measuring device is not required to be introduced, and a less stable acid gas treatment is used, and A new way of controlling the excessive addition of alkaline agents.

1, 2‧‧‧ Acid gas treatment system

11, 21‧‧‧ control device

12,22,26‧‧‧Micronized sodium bicarbonate addition device

13, 23‧‧‧ filter bags

14, 24‧‧‧HCl concentration measuring equipment

Fig. 1 is a block diagram showing the configuration of an acid gas treatment system 1 in which a fine powder of sodium hydrogencarbonate is added to HCl as an exhaust gas in an incineration facility.

2 is a basic configuration diagram of a simulated reaction system.

Fig. 3 is a graph showing the relationship between the addition amount of fine powder sodium hydrogencarbonate and the HCl removal rate in the exhaust gas reaction.

Fig. 4 is a graph showing the relationship between the addition amount of fine powder sodium hydrogencarbonate and the HCl removal rate in the reaction on the filter bag.

Figure 5 is a graph showing the behavior of inlet HCl concentration.

Fig. 6 is a graph showing the behavior of the powdered sodium bicarbonate addition amount and the outlet HCl concentration as a result of actual machine research.

Fig. 7 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet of the simulation study.

Figure 8 is a graph showing the behavior of the inlet HCl concentration.

Fig. 9 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Comparative Example 1.

Fig. 10 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 1.

Fig. 11 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Comparative Example 2.

Fig. 12 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 2.

Fig. 13 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added, the concentration of the inlet HCl, and the concentration of the outlet HCl in Comparative Example 3.

Figure 14 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 3.

Fig. 15 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 4.

Fig. 16 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 5.

Figure 17 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 6.

Fig. 18 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 7.

Fig. 19 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 8.

Figure 20 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 9.

Figure 21 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 10.

Fig. 22 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 11.

Figure 23 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 12.

Figure 24 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 13.

Figure 25 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 14.

Fig. 26 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added and the concentration of HCl at the outlet in Example 15.

Figure 27 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 16.

Figure 28 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 17.

Figure 29 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 18.

Fig. 30 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added, the concentration of the inlet HCl, and the concentration of the outlet HCl in Comparative Example 4.

Figure 31 is a graph showing the behavior of the amount of fine powder of sodium bicarbonate added and the concentration of HCl at the outlet in Example 19.

Figure 32 is a graph showing the behavior of the amount of micronized sodium bicarbonate added, the inlet HCl concentration, and the outlet HCl concentration in Example 20.

Figure 33 is a graph showing the behavior of the amount of micronized sodium bicarbonate added, the inlet HCl concentration, and the outlet HCl concentration in Example 21.

Figure 34 is a graph showing the behavior of the amount of micronized sodium bicarbonate added, the inlet HCl concentration, and the outlet HCl concentration in Example 22.

Fig. 35 is a block diagram showing the configuration of an acid gas treatment system 2 in which fine powder sodium hydrogencarbonate is added to HCl as an exhaust gas in an incineration facility.

Fig. 36 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added, the concentration of the inlet HCl, and the concentration of the outlet HCl in Comparative Example 5.

37 is a graph showing the behavior of the amount of fine powder of sodium hydrogencarbonate added, the concentration of the inlet HCl, and the concentration of the outlet HCl in Comparative Example 6.

Figure 38 is a graph showing the behavior of the amount of micronized sodium bicarbonate added, the inlet HCl concentration, and the outlet HCl concentration in Example 23.

Figure 39 is a graph showing the behavior of the amount of micronized sodium bicarbonate added, the inlet HCl concentration, and the outlet HCl concentration in Example 24.

Hereinafter, the present invention will be more specifically described by way of embodiments, but the present invention is not limited thereto.

Fig. 1 is a block diagram showing the configuration of an acid gas treatment system 1 in which a fine powder of sodium hydrogencarbonate is added to HCl as an exhaust gas in an incineration facility.

The acid gas treatment system 1 includes a control device 11, a fine powder sodium hydrogencarbonate addition device 12, a filter bag 13, and an HCl concentration measuring device 14. The control device 11 calculates the addition of the fine powder sodium bicarbonate by feedback control (PID control method or step method) 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. The output value. The fine powder sodium hydrogencarbonate addition device 12 adds the fine powder sodium hydrogencarbonate to the HCl in the exhaust gas based on the output value of the added amount of the fine powder sodium hydrogencarbonate calculated by the control device 11.

Further, the base addition amount is calculated by multiplying the average addition amount of the past corresponding to the average time (for example, the moving average time) by a factor of 1 or less.

The filter bag 13 removes the dust after the reaction of HCl in the exhaust gas with the fine powder of sodium hydrogencarbonate. The HCl concentration measuring device 14 measures the HCl concentration of the fine powder sodium hydrogencarbonate accumulated on the filter bag 13 (the fine powder of sodium hydrogencarbonate remaining on the filter bag 13 by the reaction with HCl in the exhaust gas) is reacted with the HCl after the reaction with the exhaust gas. (The filter bag outlet HCl concentration to be described later), and the HCl concentration measurement signal is sent to the control device 11.

The acid gas treatment system 1 performs feedback control in response to such a cycle, and the control device 11 performs control for setting the control output value of the amount of the fine powder sodium bicarbonate added to an appropriate value.

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, it is preferable to set the HCl concentration so as to measure the HCl concentration (the concentration of the HCl of the filter bag outlet to be described later) after the reaction of the fine powder of sodium bicarbonate accumulated on the filter bag 13 with the exhaust gas. Measuring device 14. The reason for this is that the fine powder of sodium hydrogencarbonate remaining by the reaction with HCl in the exhaust gas is accumulated on the filter bag 13, and the accumulated fine powder of sodium hydrogencarbonate reacts with the HCl after the reaction of the exhaust gas, so that the HCl concentration can be more accurately performed. Determination.

In addition, the control device 11 performs feedback control using the calculated base addition amount as the lower limit value (for example, LO: the lower limit of the addition amount) which is the output value of the addition amount of the fine powder sodium hydrogencarbonate.

Therefore, based on the base addition amount, the excess and the insufficient amount of the addition amount are adjusted by the previous feedback calculation, so that the addition of the alkali agent can be appropriately performed, and the acid gas can be efficiently treated.

Further, the average time of the average addition amount is not particularly limited, and is preferably an average value of the moving average of the applied amount, and is preferably applied at an average time of 5 minutes or more and 15 hours to 24 hours. Further, the coefficient defined by the amount of base addition is preferably 1 time or less. When the coefficient of one time or more is used, although the stabilization treatment of the acid gas can be achieved, the decrease in the amount of addition accompanying the decrease in the concentration of the inlet acid gas is hindered, and thus the addition is excessive. The base addition amount may be 1 time or less (a coefficient of 100% or less) of the average addition amount, and particularly preferably 0.5 times to 0.95 times (50% to 95%), particularly 0.7 times to 0.9 times (70% to 90%). ).

Next, the control device 11 sets the slope of the HCl concentration (time change rate of the concentration) to two ranges of the positive range and the negative range. And, for this Each of these two ranges sets a control target value of the HCl concentration.

Here, the setting of the control target value of the HCl concentration can be set such that the control target value set with respect to the positive slope of the HCl concentration is smaller than the control target value with respect to the negative range. By setting in this manner, the amount of the fine powder sodium bicarbonate added when the HCl concentration is increased can be increased as compared with the case where the HCl concentration is lowered. On the other hand, the amount of the sodium fine sodium hydrogen carbonate added when the HCl concentration is lowered can be reduced as compared with the case where the HCl concentration is increased. Therefore, the addition output of the fine powder sodium hydrogencarbonate obtained by the feedback calculation can be performed in advance, and the influence due to the measurement delay can be further alleviated.

Next, the control device 11 can perform feedback control by a stepwise method. Here, the stepping method is a control method of setting the control output corresponding to the HCl concentration in stages. 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 in accordance with the HCl concentration.

Here, the upper limit of the output in the normal PID control is only one. When the acid gas is equal to or higher than the control target value, the alkali agent can be added to the upper limit regardless of the acid gas concentration, and excessive addition can be caused. Therefore, by using a step control method, a new control output upper limit value corresponding to the current HCl concentration is added between the lower limit value and the upper limit value of the added amount output value, thereby The fine powder of sodium hydrogencarbonate can be appropriately added depending on the concentration of the HCl, and excessive addition of the added amount can be suppressed.

Next, a new control output upper limit value (for example, LM1 [output limit 1] and LM2 [output limit 2] in Table 2, Table 3, and Table 5 to be described later) is set in accordance with the HCl concentration, and the new control is performed as the HCl concentration is higher. The upper limit of the output is also set to be higher. However, in order to suppress excessive addition of the alkaline agent, it is preferably set to be smaller than the upper limit value of the control output value set in the PID control method (for example, LH [Control Output Upper Limit] of Table 2, Table 3, and Table 5 to be described later). Value.

The acid gas measuring device used in the present embodiment can be implemented regardless of the measurement method. The concentration of hydrogen chloride can be measured by an ion electrode method, a single absorption line absorption spectrometry using a laser, or the like, and the sulfur oxide can be measured by an infrared absorption method, an ultraviolet ray method, or the like. Further, in the present embodiment, since the improvement effect can be obtained by applying a proper base addition amount which cannot be considered in the previous feedback control, the effect of the present invention can be obtained regardless of the measurement delay speed.

In the combustion equipment of industrial waste incinerators or private factories, in most cases, hydrogen chloride and sulfur oxides are produced at a high concentration. In this case, both of the hydrogen chloride and the sulfur oxide are treated, and the control output obtained in the above-described control method based on the hydrogen chloride concentration of the hydrogen chloride concentration measuring device provided in the subsequent stage of the filter bag, and the sulfur oxide-based The concentration and the control outputs obtained in the above control method are added, and the acid gases such as hydrogen chloride and sulfur oxide can be stably treated.

Next, there is an apparatus for managing the discharge concentration management of the acid gas with a one hour average value of each acid gas concentration (hydrogen chloride, sulfur oxide concentration). Usually, the control target value (SV) is set to be controlled, but the control target value is only a target, and there is often a case where the concentration exceeds the target value of the control result. In particular, the reduction in the amount of addition is contrary to the concept of stabilization of the acid gas. Therefore, the more the amount of addition is required, the greater the risk that the average value of one hour exceeds the management value. In this case, when a concentration equal to or higher than the average management value of one hour or close to the average management value of one hour is reached, a large amount of an alkali agent (predetermined for a fixed addition amount) is added. In addition, it is possible to achieve a high degree of safety control in which the addition amount is reduced and the acid gas is stabilized.

The alkali agent used in the embodiment is not particularly limited. In particular, the average particle diameter of the reaction with the acid gas is adjusted to a fine powder of sodium bicarbonate of 5 μm to 30 μm, and the control responsiveness is good, and the performance of the present control method can be effectively exerted. In addition, although calcium hydroxide may be JIS-specific calcium hydroxide, it is possible to exhibit the high specific surface area of calcium hydroxide having a specific surface area with high reactivity with an acid gas of, for example, 30 m ² /g or more. performance. The alkali agent other than the above may, for example, be sodium carbonate, potassium hydrogencarbonate, potassium carbonate, sodium sesquicarbonate, natural soda, sodium hydroxide, potassium hydroxide, magnesium oxide or magnesium hydroxide.

Further, when the alkali agent is a powder, it is preferably a fine powder having a particle diameter of at least 30 μm, particularly 5 μm to 20 μm, which is highly reactive with an acid gas. It is possible to apply a pre-adjusted particle size, or to provide a pulverizing device on site, and to pulverize an alkali agent having a coarse particle size on site. Further, it may be carried out by a slurry or an aqueous solution obtained by dissolving each alkali agent in water.

Next, it is also an economically effective method to use an inexpensive alkali agent different from the alkaline agent to be controlled by the present embodiment. The alkali agent to be used in combination is not limited, and an inexpensive alkali agent which is usually used may, for example, be calcium hydroxide, sodium hydroxide, magnesium hydroxide, magnesium oxide, sodium carbonate, sodium sesquicarbonate, natural soda or crude sodium hydrogencarbonate.

[Example]

The simulated reaction system will be described.

[Simulated Reaction System]: Composite reaction on exhaust gas and filter bag

The simulated reaction system includes: micronized sodium bicarbonate and hydrogen chloride (HCL) The reaction is instantaneously caused by the reaction in the exhaust gas, and the reaction of the unreacted fine powder of sodium hydrogencarbonate and HCL accumulated on the filter bag (see Fig. 2). In addition, the residence time of the capture material in the filter bag is usually about 2 hours. Therefore, in the present simulation, it is assumed that the fine powder of sodium hydrogencarbonate on the filter bag disappears for a predetermined period of time (set at about 2 hours).

The basic configuration of the simulated reaction system will be described with reference to Fig. 2 .

First, in the drug injection control in the incineration apparatus, the amount of the chemical addition is determined by a control calculation such as PID based on the HCl concentration (after treatment) signal of the ion electrode type HCl concentration measuring device provided at the outlet of the filter bag. The amount of sodium hydrogen added (Ag) (the following formula (1)) is added to the exhaust gas (inlet HCl concentration (Hi)) by the determined addition amount of the fine powder sodium hydrogencarbonate (acid gas treatment agent). The fine powder of sodium hydrogencarbonate added to the flue reacts with an acid gas such as HCl in the exhaust gas, and the HCl in the exhaust gas is removed.

Ag=Ag1+LO (1)

Ag: Micronized sodium bicarbonate added [kg/h]

Ag1: The amount of addition specified by the output of the HCl concentration measuring device [kg/h] (refer to Table 2, Table 3, and Table 5 in the case of the step method)

LO: lower limit of addition [kg/h]

In the usual case (when the base addition amount of the present invention is not applied), a preset LO is used.

When applying the base addition amount of the present invention, the LO is used as a base addition amount obtained by multiplying the moving average addition amount of the specified time by a specific coefficient, and transporting Calculate the output.

In addition, the HCl removal rate by the inlet HCl concentration of the sodium microbicarbonate is based on the application knowledge of the company's micronized sodium bicarbonate, and the HCl removal rate (αg) is determined according to the exhaust gas reaction fine powder sodium bicarbonate addition equivalent (Jg) and the exhaust gas. The relationship (Fig. 3) and the relationship between the reaction equivalent of sodium bicarbonate addition equivalent (Js) on the filter bag and the reaction HCl removal rate (αs) on the filter bag (Fig. 4) were used. In addition, the reaction of HCl with micronized sodium bicarbonate is instantaneous. First, the HCl concentration (Hg) after the reaction in the exhaust gas is derived from the fine powder sodium hydrogencarbonate addition equivalent (Jg) of the exhaust gas reaction and the exhaust gas reaction HCl removal rate (αg) (the following formula (2)). In addition, the fine powder sodium hydrogencarbonate addition equivalent (Jg) of the exhaust gas reaction is calculated according to the following formula (3).

Hg=Hi×(1-αg÷100) (2)

Hi: inlet HCl concentration (ppm)

Hg: HCl concentration after exhaust gas reaction (ppm)

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

[Set according to the relationship between the addition amount of the sodium carbonate sodium hydrogencarbonate and the HCl removal rate (Fig. 3)]

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

Jg: exhaust gas reaction fine powder sodium bicarbonate addition equivalent

Ag: Micronized sodium bicarbonate added (kg/h)

Hi: inlet HCl concentration (ppm)

M1: HCl molecular weight [set to 36.5]

M2: molecular weight of sodium bicarbonate [set to 84]

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

Further, the fine powder of sodium hydrogencarbonate remaining by the exhaust gas reaction accumulates on the filter bag at any time. The fine powder of sodium hydrogencarbonate accumulated on the BF reacts with the HCl reacted with the exhaust gas to determine the HCl concentration (Ho) at the outlet of the filter bag. At this time, the amount of sodium bicarbonate (As) accumulated on the BF is the amount of the fine powder of sodium bicarbonate which is reacted with HCl on the BF by the fine powder of sodium hydrogencarbonate accumulated in the exhaust gas reaction. Further, it is determined based on the addition amount (Js) of the fine powder sodium bicarbonate (Js) (hereinafter referred to as the following formula (5)) estimated on the filter bag by the amount of the sodium hydrogen carbonate (As) accumulated on the filter bag and the HCl concentration (Hg) after the reaction with the exhaust gas. The HCl removal rate (αs) on the filter bag determines the HCl concentration (Ho) at the outlet of the filter bag (the following formula (4)).

Ho=Hg×(1-αs÷100) (4)

Hg: HCl concentration after exhaust gas reaction (ppm)

Ho: filter bag outlet HCl concentration (ppm)

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

[Set according to the relationship between the addition amount of micronized sodium bicarbonate on the filter bag and the HCl removal rate (Fig. 4)]

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

Js: Adding equivalent of sodium microbicarbonate on the filter bag

As: The amount of micro-powder sodium bicarbonate on the filter bag (kg/h)

Hg: HCl concentration after exhaust gas reaction (ppm)

M1: HCl molecular weight [set to 36.5]

M2: molecular weight of sodium bicarbonate [set to 84]

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

As=Z _n ÷Ts×3600 (6)

Z _n : the amount of micro-powder sodium bicarbonate accumulated on the filter bag (kg)

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

[Set to 0.5sec]

Z _n =Z _n' ×(1-2.3÷T4×Ts) (7)

Z _n' : amount of unreacted micropowder sodium bicarbonate (kg)

T4: Accumulated micronized sodium bicarbonate 90% disappearance time constant (sec) on the filter bag

[Set to 7,200sec]

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

[Set to 0.5sec]

Z _n' =(Ag÷3600×Ts-Rg)+(Z _n-1 -Rs) (8)

Ag: Micronized sodium bicarbonate added (kg/h)

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

[Set to 0.5sec]

Rg: sodium bicarbonate reaction amount in exhaust gas reaction (kg/h)

Z _n-1 : The amount of powdered sodium bicarbonate in the filter bag before Ts (Sec) (kg)

Rs: sodium bicarbonate reaction amount in the reaction on the filter bag (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: molecular weight of sodium bicarbonate [set to 84]

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

Gg: 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: molecular weight of sodium bicarbonate [set to 84]

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

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

The HCl concentration at the outlet of the filter bag after the reaction was measured by an ion electrode type HCl concentration measuring device 14. However, in the ion electrode type HCl thick In the degree measuring device 14, there is a delay time (T1) due to the device, a measurement delay time (T2α) due to exhaust gas sampling, and a measurement delay time (T2β, response time) due to ion electrode type measurement, and feedback is generated. Unique control delay.

Therefore, the delay time (T) of the HCl concentration measuring device 14 of the present simulation is the sum of the delay time (T1) caused by the device and the measurement delay time (T2) of the HCl concentration measuring device 14 (the following formula (11)) . Further, the measurement delay time (T2) of the HCl concentration measuring device 14 sets the measurement delay time (T2α) of the exhaust gas sample after the HCl treatment from the flue and the measurement delay time (response time) of the ion electrode type HCl concentration measuring device (T2β). ), and set the sum of these measurement delay times (the following formula (12)). The 90% response time (measurement delay) of the ion electrode type which is generally used is affected by the diffusion of HCl gas into the absorption liquid, and is therefore set to T2β (the following formula (13)). In this simulation, the ion electrode type with a long delay time is set to T1=30 seconds, T2α=390 seconds (sampling delay 210 seconds + bromine exhaust passage delay 180 seconds), T2β=180 seconds according to the condition of the actual equipment. 600 seconds (10 minutes: T1 = 0.5 minutes, T2 = 9.5 minutes).

Further, when the HCl concentration measuring apparatus having a shorter measurement delay time than the ion electrode type is used, the measurement delay time is changed and the behavior is confirmed.

[HCl concentration measuring device (low speed response, analog ion electrode type)]

T=T1+T2 (11)

T: Delay time (sec) of the simulated reaction system of the HCl concentration measuring device

T1: Delay time (sec) of the device [set to 30sec]

T2: Measurement delay time (sec) of the HCl concentration measuring device

T2=T2α+T2β (12)

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

[Set to 390sec]

T2β: 90% response time (sec) of the HCl concentration measuring device [set to 180 sec]

T2β=2.3×τ (13)

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

τ: time constant (sec)

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

[Set to 0.5sec]

Xn: current assay device input HCl concentration (ppm)

Yn: current measuring device output HCl concentration (ppm)

Y _n-1 : The output of the previous device (before Ts (sec)) HCl concentration (ppm)

Further, the amount of the alkaline agent to be treated for the acid gas is defined based on the added output obtained by the feedback (the above formula (1)), and the feedback is obtained by estimating the concentration measured by the HCl measuring device. The basis addition amount of the present invention is calculated by using the moving average addition amount × coefficient (1 time or less) as the lower limit of the feedback control.

In addition, using the inlet HCl concentration as shown in Figure 5, the root The reaction efficiency of the exhaust gas reaction and the HCl reaction on the BF was set according to the PID addition behavior and the HCl production state (Fig. 6) and the results of the simulation reaction system (Fig. 7) in the actual machine. The results of this study are shown in Figures 6 and 7. In this apparatus, the HCl removal efficiency of the exhaust gas is 80%, and the removal efficiency of the reaction on the BF is 65%, and the actual machine is in accordance with the simulated behavior (Fig. 6, Fig. 7). Therefore, the following simulation was performed under the conditions. Further, in the present simulation, in order to clarify the control responsiveness by the control method, the inlet HCl concentration (Hi) of the time zone having a relatively large fluctuation is used.

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

The study in the following examples is based on the results of actual machine research to make a simulated reaction system, and to study the control results using each control method. In addition, since the average time of the average addition amount in the base addition amount was long (3 hours, 6 hours), the inlet HCl concentration was repeatedly used, and the evaluation was performed by the result of 6 hours to 9 hours.

[Comparative Example 1]

Using the inlet HCl concentration shown in Fig. 8, the PID control method "P (proportional gain) = 100%, I is based on the HCl concentration measured by the HCl measuring device (measuring device measurement delay time 9.5 minutes) in the above simulation. In the case of =0.1 sec, D = 0.1 sec, the lower limit of the amount of output, 200 kg/h, and the upper limit of the amount of addition, 480 kg/h, the control target value (SV) of the outlet HCl concentration was set to 200 ppm, and feedback control was performed.

The amount of sodium bismuth bicarbonate added and the concentration of HCl at the outlet of the filter bag after treatment with micronized sodium bicarbonate (average, 1 hour average maximum, instantaneous maximum, The lowest in 1 hour and the least in instant are shown in Table 1.

Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 9 .

The maximum value of the 1-hour average value of the outlet HCl concentration which can be preferably used as the discharge management value of the acid gas is 212 ppm, and the maximum value is 384 ppm in an instant.

[Example 1]

The 30-minute moving average addition amount (kg/h) was multiplied by a coefficient of 80% as a base addition amount, and used as a lower limit of the addition amount output, and the calculation was performed under the same setting conditions as in Comparative Example 1 and feedback control was performed. .

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added during the control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 10 .

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

Here, an outline of the step control method will be described. In Comparative Example 2, Comparative Example 3 and Comparative Example 6, Example 2, Example 3, Example 9 to Example 11, Example 17, Example 18, and Example 20 to Example 24, the step control method was used instead of the PID control method for control.

The stepping method is different from the PID control method, and is set to a control method that outputs the output according to the HCl concentration of the outlet. According to Comparative Example 2, Example 2, and Example 20 (Table 2), when the HCl concentration is between the SV control target value [control output start concentration (output lower limit or higher)]~SM1, between LO and LM1. Output output control. The concentration of HCl is SM1~SM2 When it is between, it outputs the control output set by LM2. When it is SM2 or more, it is set to output LH (control output upper limit). In addition, there is no output limitation in the normal PID control formula, and only LO and LH are set. In addition, the HCl concentration used in the control calculation of the HCl slope and the correction of the table for determining the control output are performed by SVA1 and SVA2, and when the HCl slope is positive, the HCl concentration used in the calculation is subtracted from SVA1. When the HCl slope is negative, the concentration of HCl used in the calculation is added to SVA2. Thereby, the control output calculated when the same HCl concentration is input is set to a control output when the value of the HCl slope is large (the acid gas concentration tends to increase) and the control output value and the HCl slope value are small. The value increases compared to the value.

Further, the amount of fine sodium hydrogencarbonate added (Ag) was determined by the above formula (1).

[Comparative Example 2]

In the above simulation, according to the HCl concentration measured by the HCl measuring device (measurement device measurement delay time 9.5 minutes), the control target value is controlled in the step mode control (in this mode, the control output of the alkaline agent is added to the lower limit of the output) The above concentration is defined as SV) and is set to 200 ppm to perform feedback control (refer to Table 2).

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 11 .

The maximum value of the 1-hour average value of the outlet HCl concentration in the stepwise mode was 212 ppm, and the maximum instantaneous value was 383 ppm.

[Example 2]

The 30-minute moving average addition amount (kg/h) was multiplied by a coefficient of 80% as a base addition amount, and used as a lower limit of the addition amount output, and the calculation was performed under the same setting conditions of the stepping method shown in Comparative Example 2. And feedback control.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 12 .

According to Example 2, the maximum value of the 1-hour average value of the outlet HCl concentration in the stepwise mode was 195 ppm, and the instantaneous maximum was 320 ppm. Compared with Comparative Example 2, the acid gas treatment performance was improved, and the addition amount was also reduced from 295 kg/h to 289kg/h.

[Comparative Example 3]

In the above simulation, according to the HCl concentration measured by the HCl measuring device (measurement device measurement delay time 9.5 minutes), in the control of the step mode, when the average of the slope of the closest HCl concentration is 6 seconds, the control target is The value (SV) was set to 180 ppm (SV-20 ppm), and when the average of the slope of the closest HCl concentration was negative for 6 seconds, the control target value (SV) was set to 220 ppm (SV+20 ppm), and feedback control was performed ( Refer to Table 3).

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 13 .

In addition to the current stepping method, the control target value is changed according to the slope of the HCl concentration (hereinafter referred to as SV change), and the maximum value of the 1-hour average value of the outlet HCl concentration controlled by the feedback control is 216 ppm. The maximum is 381ppm.

[Example 3]

The 30-minute moving average addition amount (kg/h) was multiplied by a coefficient of 80% as a base addition amount, and used as a lower limit of the addition amount output, and was calculated under the same setting conditions of the feedback form shown in Comparative Example 3, and Perform feedback control.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 14 .

According to Example 3, in the above feedback mode, the maximum value of the 1-hour average value of the outlet HCl concentration was 198 ppm, and the maximum instantaneous value was 283 ppm. Compared with Comparative Example 3, the acid gas treatment performance was improved, and the addition amount was also from 301 kg/h. Reduced to 289kg / h.

[Example 4 to Example 8]

The moving average addition amount (kg/h) of the average time will be changed [Example 4: 5 minutes, Example 5: 15 minutes, Example 6: 1 hour, Example 7: 3 hours, Example 8: 6 hours] Multiplied by 80% The coefficient is used as the base addition amount and used as the addition amount output lower limit. Otherwise, the feedback control is performed under the same setting conditions as in Comparative Example 1.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag are shown in Figs. 15 to 19 .

According to the examples 4 to 8, the basic addition amount obtained by multiplying the average addition amount by a factor of 1 or less is used as a factor of feedback control, and the operation of the alkali agent is performed. The amount of addition allows a stable treatment of the acid gas.

The effects of Examples 4 to 8 were obtained by applying the factor of the average addition amount in the feedback, and the average time is not particularly limited. In the average addition time of 5 minutes (Example 4), the equivalent amount of the outlet HCl concentration was 186 ppm at a maximum value of 1 hour, and the maximum instantaneous value was 369 ppm, whereby a stable treatment effect of the acid gas was obtained. Further, in the average addition time of 6 hours (Example 8), the 1-hour average value of the outlet HCl concentration was 194 ppm at the maximum and 308 ppm at the maximum, and a stable treatment effect was obtained, and the addition amount was also reduced to 311 kg/h. The average time of the added amount is preferably 5 minutes or more, and particularly preferably 15 minutes to 6 hours.

[Example 9 to Example 11]

The moving average addition amount (kg/h) of the average time is changed [Example 9: 15 minutes, Example 10: 1 hour, Example 11: 3 hours] multiplied by a coefficient of 80%, and is added as a base, and is used as an addition. In addition to the lower limit of the amount of output, the feedback control was performed under the same setting conditions as shown in Comparative Example 3.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag are shown in Figs. 20 to 22 .

According to Example 9 to Example 11 when the average amount of addition time in the feedback control using the step + SV change mode is changed from 15 minutes to 3 hours, the acid gas stabilization treatment effect and addition can be obtained regardless of the average time of the addition amount. The amount of reduction effect. This embodiment is a control method which is excellent in the effect of reducing the amount of addition when the amount of addition is 288 kg/h to 292 kg/h.

[Example 12 to Example 16]

The coefficient multiplied by the 1-hour moving average addition amount (kg/h) was changed [Example 12: 95%, Example 13: 90%, Example 14: 80%, Example 15: 70%, Example 16: 50%] as The base addition amount was used as the lower limit of the addition amount output, and the feedback control was performed under the same setting conditions as shown in Comparative Example 1.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag are shown in Figs. 23 to 27 .

The effects of the example 12 to the example 16 are obtained by applying the factor of the average addition amount in the feedback. When the basis addition amount is calculated, the coefficient by which the average addition amount is multiplied is not more than one. When the coefficient is multiplied by a factor of 1 time (100%) or more, even if the inlet HCl concentration is decreased, the average addition amount used for the base addition amount is not reduced and excessive addition is caused.

When the coefficient of the base addition amount is 95% (Example 12) to 70% (Example 15), the maximum 1-hour average value of the outlet HCl concentration and the instantaneous maximum value are lower than those of Comparative Example 1, and acid gas can be obtained. The effect of the treatment is stabilized, and the effect of reducing the amount of addition can be obtained. Further, when the coefficient was 50% (Example 16), although the amount of addition was slightly increased, the acid gas stabilizing treatment effect was obtained. The coefficient multiplied by the average addition amount when calculating the basic addition amount may be 1 time or less. It is preferably 50% to 95%, and particularly preferably 70% to 90%.

[Example 17, Example 18]

Change the coefficient multiplied by the 1-hour moving average addition amount (kg/h) Example 17: 90%, Example 18: 70%] was used as the base addition amount and used as the addition amount output lower limit. Otherwise, the feedback control was performed under the same setting conditions as shown in Comparative Example 3.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag are shown in Figs. 28 and 29 .

According to the example 17 and the example 18 when the coefficient multiplied by the operation base addition amount in the feedback control by the step + SV change mode is changed within 70% to 90%, regardless of the coefficient of the calculation base addition amount, The acid gas stabilization treatment effect and the addition amount reduction effect are obtained. In addition, this embodiment is a control method which is excellent in the effect of reducing the addition amount particularly when the addition amount is 289 kg/h to 297 kg/h.

[Comparative Example 4]

According to the HCl concentration measured by the HCl measuring device (measurement device measurement delay time 2 seconds) in the above simulation, the PID control method "P (proportional gain) = 100%, I = 0.1 second, D = 0.1 second, the amount of addition) In the output lower limit of 200 kg/h and the addition amount output upper limit of 480 kg/h, the control target value (SV) of the outlet HCl concentration was set to 200 ppm and feedback control was performed.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 30.

The effect of the measurement delay time of the measuring device was investigated. It is predicted that when feedback control is performed using an HCl measuring apparatus that measures a high-speed response with less delay, the change in the amount of addition of the alkali agent and the change in the concentration of the outlet HCl are instantaneously caused and improved. However, it is predicted that it will cause changes due to the addition of alkaline agents. The resulting additive failure is preferably used as the discharge management value of the acid gas. The maximum value of the 1-hour average value of the outlet HCl concentration is 209 ppm, and the maximum instantaneous value is 385 ppm.

[Example 19]

The feedback control was performed under the same conditions as in Example 1 except that the PID control calculation was performed by the HCl concentration measured by the HCl measuring device (measurement device measurement delay time: 2 seconds) in the above simulation.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 31.

[Example 20]

The feedback control was performed under the same conditions as in Example 2 except that the HCl concentration measured by the HCl measuring device (measurement device measurement delay time of 2 seconds) was calculated by the stepwise method in the above simulation.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 32.

[Example 21]

The feedback was performed under the same conditions as in Example 3, except that the HCl concentration measured by the HCl measuring device (measurement device measurement delay time: 2 seconds) was calculated by the step + SV change method in the above simulation. control.

The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. In addition, the micro-powder carbon in this control The behavior of the amount of sodium hydrogen hydride added and the concentration of HCl at the outlet of the filter bag is shown in Figure 33.

According to the example 21, the effect is exerted regardless of the length of the measurement delay time of the measuring device. And if the control form is in the form of feedback, it will exert its effect. Examples 19 to 21 are results of assuming a measurement delay time of 2 seconds, suppressing the addition of an alkali agent due to feedback, and obtaining an effect of stabilizing the acid gas and an effect of reducing the amount of addition.

[Example 22]

In the above simulation, when the average value of the outlet HCl concentration exceeded 190 ppm, the addition of the 480 kg/h alkali agent was carried out, and the same conditions as in Example 10 (delay time 9.5 minutes, step + SV change) were carried out. Feedback control. The HCl concentration of the fine powder sodium bicarbonate added to the filter bag outlet after treatment with the fine powder of sodium hydrogencarbonate is shown in Table 1. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added in the present control and the concentration of the HCl at the outlet of the filter bag is shown in Fig. 34.

The discharge concentration management of the acid gas has a device that is managed by a one-hour average value of each acid gas concentration (hydrogen chloride, sulfur oxide concentration). In the control, the control target value (SV) is usually set for control, but the control target value is only the target, and there is a case where the concentration exceeds the target value of the controlled result.

In the present example, in the example 10 in which the 1-hour average value of the outlet HCl concentration exceeded 200 ppm, an example of one-hour average management (190 ppm or more was performed at 480 kg/h) was carried out. When the 1-hour average value of the outlet is close to the concentration to be managed, the more stable treatment effect of the acid gas and the utilization of the effective alkali agent can be achieved by performing the control of adding a large amount of the alkali agent.

Hereinafter, Comparative Example 5 and Comparative Example 6 which are the results of actual machine research, In the case of Example 23 and Example 24, the configuration of the acid gas treatment system 2 used in Comparative Example 5, Comparative Example 6, Example 23, and Example 24 will be described.

Fig. 35 is a block diagram showing the configuration of an acid gas treatment system 2 in which fine powder sodium hydrogencarbonate is added to HCl as an exhaust gas in an incineration facility.

The acid gas treatment system 2 includes a control device 21, a fine powder sodium hydrogencarbonate addition device 22, a fine powder sodium hydrogencarbonate addition device 26, a filter bag 23, and an HCl concentration measuring device (ion electrode method) 24. The control device 21 calculates the fine powder by the feedback control (PID control method or step method) based on the HCl concentration measurement signal transmitted by the HCl concentration measuring device (ion electrode method) 24 and the basic addition amount calculated from the past average addition amount. The added amount of sodium bicarbonate output value. The fine powder sodium hydrogencarbonate addition device 22 adds the fine powder sodium hydrogencarbonate to the HCl in the exhaust gas based on the output amount of the fine powder sodium hydrogencarbonate added by the control device 21. Further, the fine powder sodium hydrogencarbonate addition device 26 is a fixed amount of fine powder sodium hydrogencarbonate which is added to the HCl in the exhaust gas irrespective of the output value of the added amount of the fine powder sodium hydrogencarbonate calculated by the controller 21.

Further, the base addition amount is calculated by multiplying the average addition amount of the past corresponding to the average time (for example, the moving average time) by a factor of 1 or less.

The filter bag 23 removes dust obtained by reacting HCl in the exhaust gas with fine powder of sodium hydrogencarbonate. The HCl concentration measuring device (ion electrode method) 24 measures the reaction of the fine powder sodium hydrogencarbonate (the fine powder of sodium hydrogencarbonate remaining on the filter bag 23 by the reaction with HCl in the exhaust gas) accumulated on the filter bag 23 with the exhaust gas. The concentration of HCl after the subsequent HCl reaction (concentration of the HCl of the filter bag to be described later) is sent to the control device 21 by the HCl concentration measurement signal.

In addition, the inlet HCl concentration of the filter bag is by HCl not shown. The concentration measuring device (laser mode) was measured.

The acid gas treatment system 2 performs feedback control in response to such a cycle, and the control device 21 performs control for setting the control output value of the fine powder sodium bicarbonate addition amount to an appropriate value.

[Comparative Example 5]

In an industrial waste incinerator, a HCl measuring device (KLA-1 manufactured by Kyoto Electronics Industry Co., Ltd.) in the form of a laser was placed between the outlet of the desuperheating tower and the filter bag, and the inlet HCl concentration was measured. In addition, the signal measured by the ion electrode type HCl measuring device (HL-36N manufactured by Kyoto Electronics Industry Co., Ltd.), which is an outlet of the filter bag, is subjected to feedback control by managing the oxygen-converted value of the discharge reference value. In addition, the feedback addition output (SV180 ppm) based on the SOx concentration signal of the outlet is added to the addition output according to the HCl concentration, but in this apparatus, since SOx is not generated, it is deleted from this report.

Further, the alkaline agent for treating the acid gas was added with 8 μm of fine powder sodium hydrogencarbonate (Hyperther B-200 manufactured by Kurita Industries) by the above feedback control. The alkaline agent addition device is applied by two units due to the problem of the maximum amount of addition, one set is set to 180 kg/h quantitatively, and the other one is based on the above-mentioned outlet HCl concentration signal by "lower limit 20 kg/h, upper limit 300 kg/h, PID" The feedback control is performed by controlling the setting P (proportional gain) = 100%, I = 0.1 second, D = 0.1 second.

The HCl concentration at the inlet of the filter bag and the HCl concentration at the outlet of the filter bag and the addition amount of the sodium hydrogencarbonate (calculated by two addition devices) are shown in Table 4. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added at the time of the present control and the concentration of HCl at the inlet and outlet of the filter bag are shown in Fig. 36.

[Comparative Example 6]

In the same apparatus, feedback control was performed using an HCl concentration signal (oxygen conversion value) measured by an ion electrode type HCl measuring device (HL-36N manufactured by Kyoto Electronics Industry Co., Ltd.). Further, similarly, the feedback addition output (SV180 ppm) based on the SOx concentration signal of the outlet was added in addition to the addition output according to the HCl concentration.

In addition, the same device is set to 180 kg/h for the same amount, and the other device is set to "Step + SV change method (see Table 5 for details)".

The HCl concentration at the inlet of the filter bag and the HCl concentration at the outlet of the filter bag and the addition amount of the sodium hydrogencarbonate (calculated by two addition devices) are shown in Table 4. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added at the time of the present control and the concentration of HCl at the inlet and outlet of the filter bag is shown in Fig. 37 .

[Example 23]

In the same device, in the feedback control of "Step + SV change mode", the base addition amount [30 minutes moving average addition amount, coefficient 70%] is applied, and the outlet HCl concentration is 1 hour average value is 213 ppm or more [this device HCl The feedback control was carried out by the same setting as in Comparative Example 6, except that the management value was 215 ppm or less] and 300 kg/h was added. Further, similarly, the feedback addition output (SV180 ppm) based on the SOx concentration signal of the outlet was added in addition to the addition output according to the HCl concentration.

In addition, the same device is set to 180 kg/h for the same amount, and the other device is set to "Step + SV change method (see Table 5 for details)".

The HCl concentration at the inlet of the filter bag and the HCl concentration at the outlet of the filter bag and the addition amount of the sodium hydrogencarbonate (calculated by two addition devices) are shown in Table 4. In addition, the amount of micro-powder sodium bicarbonate added during the implementation of this control and the filter bag inlet and outlet The behavior of the HCl concentration is shown in Figure 38.

This example is the result of the application of the real machine according to the present invention. The change in the inlet HCl concentration was smaller than in Comparative Example 5 and Comparative Example 6. According to the present example, the addition of the effective alkali agent of the present invention indicates the addition equivalent of the amount of the alkali agent added to the inlet HCl concentration, and can be reduced and effective control can be achieved as compared with Comparative Example 5 and Comparative Example 6.

[Example 24]

In the same device, in the feedback control of "Step + SV change method", high-response calcium hydroxide (TamakalkECO manufactured by Odomo Industries Co., Ltd.) having a specific surface area of 30 m ² /g or more is used in combination, and The feedback control was carried out by the same settings as in Example 23 except for the same. In addition, the feedback addition output (SV18 six ppm) and the addition output according to the HCl concentration are also performed in accordance with the feedback of the SOx concentration signal of the outlet.

In addition, one of the addition devices was set to a high-reaction calcium hydroxide of 170 kg/h, and the other was set to "step + SV change mode (see Table 5 for details).

The HCl concentration at the inlet of the filter bag and the HCl concentration at the outlet of the filter bag and the addition amount of the sodium hydrogencarbonate (calculated by two addition devices) are shown in Table 4. Further, the behavior of the amount of the fine powder of sodium hydrogencarbonate added at the time of the present control and the concentration of HCl at the inlet and outlet of the filter bag is shown in Fig. 39.

Table 1 is a table showing the amount of alkali agent added and the like for each of the comparative examples and the examples of the results of the simulation studies. Table 2 is a table of control settings of the step control method in Comparative Example 2, Example 2, and Example 20. Table 3 is Comparative Example 3, Example 3, Example 9, Example 10, Example 11, Example 17, Example 18, Example 21, and Example A table of 22 control settings for step control mode. Table 4 is a table showing the amount of alkali agent added and the like in each of the comparative examples and the examples of the actual machine research results. Table 5 is a table of control settings of the step control method in Comparative Example 6, Example 23, and Example 24.

This example is an example in which the industrially relatively inexpensive calcium hydroxide and finely divided sodium hydrogencarbonate are used in combination. In the method, the stable treatment effect of the acid gas can also be stably obtained. It is an industrially effective method because it uses inexpensive calcium hydroxide and reduces the cost of acid gas treatment.

1‧‧‧ Acid gas treatment system

11‧‧‧Control device

12‧‧‧Micronized sodium bicarbonate addition device

13‧‧‧Filter bag

14‧‧‧HCl concentration measuring equipment

Claims (6)

A method for treating an acid gas, which comprises adding an alkali agent to a combustion exhaust gas containing an acid gas, and feeding back a measurement signal of an acid gas concentration measuring device for measuring an acid gas concentration after the dust is collected, and feeding back an amount of the alkali agent. The method for controlling the acid gas includes: a step of calculating a base addition amount obtained by multiplying an average addition amount corresponding to an average time by a factor of 1 or less; and a feedback based on the calculated base addition amount The calculation is performed to calculate the output value of the addition amount of the alkaline agent. A method for treating an acid gas, which comprises adding an alkali agent to a combustion exhaust gas containing an acid gas, and feeding back a measurement signal of an acid gas concentration measuring device for measuring an acid gas concentration after the dust is collected, and feeding back an amount of the alkali agent. Controlling, and the method for treating the acid gas includes: a step of calculating a base addition amount obtained by multiplying an average addition amount corresponding to an average time by a coefficient less than 1 time; and a feedback based on the calculated basic addition amount In the calculation, the value of the addition amount of the alkali agent is calculated, and the calculated value of the base addition amount or more and a predetermined upper limit or lower is used as the output value of the addition amount of the alkali agent. The method for treating an acid gas according to claim 1 or 2, wherein in the step of calculating the addition amount output value by the feedback calculation, the calculated base addition amount is set as the alkali agent. The lower limit of the added quantity output value. The method for treating an acid gas according to the first or second aspect of the invention, wherein in the step of calculating the base addition amount, the average addition amount when the average time is 5 minutes or longer is 0.5 to 0.95 times. Add amount to the base. The method for treating an acid gas according to claim 1 or 2, wherein in the step of calculating the basic addition amount, the moving average addition amount is 0.5 to 0.95 times the base addition amount, and the moving average addition amount is specified by the average value of the acid gas concentration when the acid gas concentration is continuously measured for a predetermined time every predetermined time period selected from 5 minutes or more. . The method for processing an acid gas according to claim 1 or 2, wherein the step of calculating the added amount output value by the feedback calculation further comprises: in addition to the feedback calculation, according to a hydrogen chloride concentration and/or sulfur The average value of the oxide concentration is a step of calculating the output value of the amount of the alkali agent added.