JP3757549B2 - Method and apparatus for detecting decrease in absorbent activity of flue gas desulfurization apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for detecting a decrease in absorbent activity of a flue gas desulfurization apparatus.
[0002]
[Prior art]
As shown in FIG. 4, a flue gas desulfurization apparatus using calcium carbonate (CaCO ₃ ) as an absorbent is generally formed with a liquid reservoir 1a of the absorbent 1 at the bottom and a number of spray nozzles 2 at the top. An absorption tower 3 installed, a circulation pump 4 that pumps up the absorption liquid 1 in the liquid reservoir 1a of the absorption tower 3 and sprays it from the spray nozzle 2, and circulates in the liquid reservoir 1a of the absorption tower 3. And an oxidized air blower 5 for supplying the air.
[0003]
In the case of the flue gas desulfurization apparatus as described above, the absorbing liquid 1 is circulated while being sprayed from the spray nozzle 2 by the operation of the circulation pump 4, and the exhaust gas sent to the absorption tower 3 from a coal fired boiler or the like not shown is The SO ₂ (sulfur oxide) is absorbed and removed by contact with the absorbing liquid 1 sprayed from the spray nozzle 2 and then discharged to the outside.
[0004]
On the other hand, a part of the absorbing liquid 1 that has absorbed SO ₂ from the exhaust gas is recovered as gypsum slurry from the bottom of the liquid reservoir 1a of the absorption tower 3, and water is removed from the gypsum slurry so that gypsum is generated. In addition, an absorbent slurry is appropriately supplied to the absorption tower 3 as necessary.
[0005]
By the way, as long as the pH (pH) of the absorption liquid 1 in the absorption tower 3 is controlled to be constant, and the sulfur content in the exhaust gas and the calcium in the absorbent are normally reacted one-to-one, it is unreacted. The absorbent is almost zero, and the desulfurization of the exhaust gas is performed reliably, but the sulfur content in the exhaust gas reacts with the absorbent for some reason, such as adhesion of impurities that inhibit the reaction with the sulfur around the absorbent. If it does not occur (so-called a decrease in the activity of the absorbent occurs), the exhaust gas is not sufficiently desulfurized and the desulfurization performance may be reduced.
[0006]
For this reason, conventionally, a part of the absorbing liquid 1 in the absorption tower 3 is regularly extracted by an operator by opening the valve 6 and manually analyzed to measure the unreacted absorbent concentration in the absorbing liquid 1. The decrease in the activity of the absorbent was judged.
[0007]
In the case where a decrease in the activity of the absorbent occurs, by injecting a neutralizing agent such as caustic soda from an injection line (not shown) into the liquid reservoir 1a of the absorbent 1 in the absorption tower 3, A decrease in the activity of the absorbent is eliminated, and the reaction between the sulfur content in the exhaust gas and the absorbent is promoted.
[0008]
[Problems to be solved by the invention]
However, as described above, it is troublesome for the operator to measure the concentration of the unreacted absorbent in the absorbent 1 by manual analysis and judge the decrease in the activity of the absorbent, and it is difficult to continuously monitor. Had.
[0009]
In view of such circumstances, the present invention can continuously monitor the concentration of unreacted absorbent in the absorbent in the absorption tower without manual measurement by an operator, and reliably reduce the activity of the absorbent. It is an object of the present invention to provide a method and an apparatus for detecting a decrease in the absorbent activity of a flue gas desulfurization apparatus that can detect the above and prevent a decrease in desulfurization performance.
[0010]
[Means for Solving the Problems]
The present invention detects an unreacted absorbent concentration in an absorbent in an absorption tower using calcium carbonate as an absorbent, detects the pH of the absorbent, and determines the unreacted absorbent concentration based on the pH of the absorbent. A flue gas desulfurization characterized in that a reference value is obtained, and it is determined that a decrease in the activity of the absorbent has occurred when the difference between the unreacted absorbent concentration and the unreacted absorbent concentration reference value is equal to or greater than a set value. This relates to a method for detecting a decrease in absorbent activity of a device.
[0011]
The present invention also includes a concentration meter for detecting the concentration of unreacted absorbent in the absorbent in the absorption tower using calcium carbonate as the absorbent,
A pH meter for detecting the pH of the absorption liquid in the absorption tower;
A function generator that calculates and outputs an unreacted absorbent concentration reference value based on the pH of the absorbent detected by the pH meter;
A subtractor that calculates the difference between the unreacted absorbent concentration detected by the densitometer and the unreacted absorbent concentration reference value and outputs an unreacted absorbent concentration deviation;
A signal monitor switch that outputs an ON signal when the unreacted absorbent concentration deviation output from the subtractor exceeds a set value;
An on-delay that outputs an ON signal after a predetermined time has elapsed since the signal output from the signal monitor switch is turned ON, and outputs an OFF signal instantaneously when the signal output from the signal monitor switch is turned OFF The present invention relates to an apparatus for detecting a decrease in absorbent activity of a flue gas desulfurization apparatus, characterized by comprising a timer.
[0012]
According to the above means, the following operation can be obtained.
[0013]
In the method for detecting a decrease in the absorbent activity of the flue gas desulfurization apparatus according to the present invention, during operation of the flue gas desulfurization apparatus, the concentration of the unreacted absorbent in the absorption liquid in the absorption tower is detected, and the pH of the absorption liquid is detected. An unreacted absorbent concentration reference value is obtained based on the pH of the absorbent, and when the difference between the unreacted absorbent concentration and the unreacted absorbent concentration reference value exceeds a set value, the activity of the absorbent It is determined that a decrease has occurred.
[0014]
Further, in the apparatus for detecting the decrease in the absorbent activity of the flue gas desulfurization apparatus of the present invention, during operation of the flue gas desulfurization apparatus, the concentration meter detects the unreacted absorbent concentration in the absorption liquid in the absorption tower, and the pH The pH of the absorption liquid in the absorption tower is detected by the meter, and the unreacted absorbent concentration reference value is obtained in the function generator based on the pH of the absorption liquid detected by the pH meter, and is output to the subtractor. The difference between the unreacted absorbent concentration detected by the densitometer and the unreacted absorbent concentration reference value is obtained in the analyzer, and the unreacted absorbent concentration deviation is output to the signal monitor switch and output from the subtractor. When the unreacted absorbent concentration deviation exceeds the set value, an ON signal is output from the signal monitor switch to the on-delay timer.
[0015]
Here, the on-delay timer outputs an ON signal after a predetermined time has elapsed since the signal output from the signal monitor switch is turned ON, and instantaneously when the signal output from the signal monitor switch is turned OFF. Since an OFF signal is output, an ON signal is not output from the on-delay timer if the unreacted absorbent concentration deviation temporarily exceeds a set value for some reason, and an error occurs. Only when a predetermined time set in the on-delay timer has elapsed after the operation is avoided and the unreacted absorbent concentration deviation exceeds the set value, an ON signal is output from the on-delay timer. As a result, it is determined that a decrease in the activity of the absorbent has occurred.
[0016]
As a result, in the method and apparatus for detecting the decrease in the absorbent activity of the flue gas desulfurization apparatus of the present invention, the operator measures the concentration of the unreacted absorbent in the absorbent by manual analysis as in the past, and the decrease in the activity of the absorbent. It is not necessary to judge the time, and it is not time-consuming and continuous monitoring is possible.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
1 to 3 show an example of an embodiment for carrying out the present invention. In the figure, the portions denoted by the same reference numerals as those in FIG. 4 represent the same items, and are not shown in the absorption liquid 1 in the absorption tower 3. A concentration meter 8 for detecting the reaction absorbent concentration 7, a pH meter 9 for detecting the pH of the absorbent 1 in the absorption tower 3, and an unreacted absorbent based on the pH of the absorbent 1 detected by the pH meter 9. A function generator 11 for obtaining and outputting a concentration reference value 10 and a difference between the unreacted absorbent concentration 7 detected by the densitometer 8 and the unreacted absorbent concentration reference value 10 to obtain an unreacted absorbent concentration deviation 12, a signal monitor switch 15 that outputs an ON signal 14 when the unreacted absorbent concentration deviation 12 output from the subtractor 13 exceeds a set value, and the signal monitor switch A predetermined time after the signal 14 output from 15 turns ON And an on-delay timer 17 that outputs an OFF signal 16 when the signal 14 output from the signal monitor switch 15 is turned OFF, and outputs an unreacted absorbent concentration. When the difference between 7 and the unreacted absorbent concentration reference value 10 is equal to or greater than a set value, it is determined that a decrease in the activity of the absorbent has occurred.
[0019]
As shown in FIG. 2, the densitometer 8 collects the absorption liquid 1 in an overflow type sample meter 8a connected to a drain recovery system, adds a certain amount of sulfuric acid to generate CO ₂ gas, and generates the CO ₂ gas. was introduced into the infrared CO ₂ meter 8b, it can be used the concentration of calcium carbonate unreacted by measuring the CO ₂ gas concentration, i.e., the outputs to analyze unreacted absorbent concentration 7.
[0020]
Since the unreacted absorbent concentration 7 is slightly higher as the pH value of the absorbent 1 is higher, the function generator 11 has a vertical value relative to the pH value taken on the horizontal axis as shown in FIG. A function is input in which the unreacted absorbent concentration reference value 10 taken on the axis is represented by a straight line with an upward slope.
[0021]
Next, the operation of the illustrated example will be described.
[0022]
During operation of the flue gas desulfurization apparatus, the concentration meter 8 detects the unreacted absorbent concentration 7 in the absorption liquid 1 in the absorption tower 3 and the pH meter 9 detects the pH of the absorption liquid 1 in the absorption tower 3. Based on the pH of the absorption liquid 1 detected by the pH meter 9, the function generator 11 obtains the unreacted absorbent concentration reference value 10 and outputs it to the subtractor 13, and the subtractor 13 outputs the concentration meter 8. The difference between the unreacted absorbent concentration 7 detected in step 1 and the unreacted absorbent concentration reference value 10 is obtained, and the unreacted absorbent concentration deviation 12 is output to the signal monitor switch 15 and output from the subtractor 13. When the unreacted absorbent concentration deviation 12 exceeds a set value, an ON signal 14 is output from the signal monitor switch 15 to the on-delay timer 17.
[0023]
The on-delay timer 17 outputs an ON signal 16 after a predetermined time has elapsed since the signal 14 output from the signal monitor switch 15 is turned ON, and the signal 14 output from the signal monitor switch 15. Since the OFF signal 16 is instantaneously output when the signal is turned OFF, the on-delay timer 17 starts from the on-delay timer 17 only when the unreacted absorbent concentration deviation 12 temporarily exceeds the set value for some reason. The ON signal 16 is not output, the malfunction is avoided, and the state in which the unreacted absorbent concentration deviation 12 is equal to or greater than the set value is not exceeded until the predetermined time set in the on-delay timer 17 has elapsed. An ON signal 16 is output from the timer 17, and it is determined that a decrease in the activity of the absorbent has occurred.
[0024]
When it is determined that a decrease in the activity of the absorbent has occurred, a neutralizing agent such as caustic soda is injected from an injection line (not shown) into the liquid reservoir 1a of the absorption liquid 1 in the absorption tower 3, and in the exhaust gas. The reaction between the sulfur content of the catalyst and the absorbent is promoted.
[0025]
As a result, it is not necessary for the operator to measure the unreacted absorbent concentration in the absorbent 1 by manual analysis and judge the decrease in the activity of the absorbent as in the conventional case, so that it takes less time and can be continuously monitored. It becomes.
[0026]
In this way, the unreacted absorbent concentration of the absorbent 1 in the absorption tower 3 can be continuously monitored without manual measurement by an operator, and a decrease in the activity of the absorbent can be reliably detected. A decrease in performance can be prevented.
[0027]
The method and apparatus for detecting the decrease in the absorbent activity of the flue gas desulfurization apparatus of the present invention is not limited to the above illustrated examples, and various modifications can be made without departing from the scope of the present invention. Of course.
[0028]
【The invention's effect】
As described above, according to the method and apparatus for detecting the decrease in the absorbent activity of the flue gas desulfurization apparatus of the present invention, the operator does not manually measure the unreacted absorbent concentration of the absorbent in the absorption tower. It is possible to continuously monitor, and it is possible to reliably detect a decrease in the activity of the absorbent and to exhibit an excellent effect of preventing a decrease in desulfurization performance.
[Brief description of the drawings]
1 is an overall schematic configuration diagram of an example of an embodiment for carrying out the present invention;
FIG. 2 is a schematic diagram of a densitometer according to an example of an embodiment of the present invention.
FIG. 3 is a diagram representing functions set in the function generator shown in FIG. 1;
FIG. 4 is an overall schematic configuration diagram of a conventional example.
[Explanation of symbols]
1 Absorbent 3 Absorption tower 7 Unreacted absorbent concentration 8 Concentration meter 9 pH meter 10 Unreacted absorbent concentration reference value 11 Function generator 12 Unreacted absorbent concentration deviation 13 Subtractor 14 Signal 15 Signal monitor switch 16 Signal 17 ON Delay timer

Claims (2)

In addition to detecting the concentration of unreacted absorbent in the absorbent in the absorption tower using calcium carbonate as the absorbent, the pH of the absorbent is detected, and the reference value of unreacted absorbent concentration is obtained based on the pH of the absorbent. The absorbent of the flue gas desulfurization apparatus is characterized in that when the difference between the unreacted absorbent concentration and the unreacted absorbent concentration reference value is greater than or equal to a set value, it is determined that a decrease in the activity of the absorbent has occurred. Activity fall detection method. A concentration meter for detecting the concentration of unreacted absorbent in the absorbent in the absorption tower using calcium carbonate as the absorbent;
A pH meter for detecting the pH of the absorption liquid in the absorption tower;
A function generator that calculates and outputs an unreacted absorbent concentration reference value based on the pH of the absorbent detected by the pH meter;
A subtractor that calculates the difference between the unreacted absorbent concentration detected by the densitometer and the unreacted absorbent concentration reference value and outputs an unreacted absorbent concentration deviation;
A signal monitor switch that outputs an ON signal when the unreacted absorbent concentration deviation output from the subtractor exceeds a set value;
An on-delay that outputs an ON signal after a predetermined time has elapsed since the signal output from the signal monitor switch is turned ON, and outputs an OFF signal instantaneously when the signal output from the signal monitor switch is turned OFF An apparatus for detecting a decrease in absorbent activity of a flue gas desulfurization apparatus, comprising a timer.

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