JP2009248058A - Method of and apparatus for predicting ignition of activated carbon layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of and apparatus for predicting ignition of an activated carbon layer, the method and apparatus detecting an ignition phenomenon regardless of the position of the ignition phenomenon part when it occurs inside the activated carbon layer, thereby surely predicting the ignition of the activated carbon layer and preventing the ignition. <P>SOLUTION: In the activated carbon layer 1 for predicting the ignition of the activated carbon layer filled with activated carbon in order to absorb and remove harmful components in exhaust gas, a plurality of temperature sensors 2 are disposed, with any positions inside the activated carbon layer as origins, so that at least one temperature sensor 2 is present within the area of 1 m from each origin, it is determined that there is the risk of the ignition when at least one of the temperatures measured by the plurality of temperature sensors 2 becomes a prescribed temperature or higher, and an ignition preventing measure is taken. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ignition prediction method and apparatus for an activated carbon layer for predicting ignition in an activated carbon layer filled with activated carbon in order to adsorb and remove harmful components in exhaust gas.

  In the treatment of various types of waste such as general waste and industrial waste, if incineration or melt decomposition is performed, dioxins and sulfur oxides are generated and mixed into the exhaust gas, and are also contained in the waste. Heavy metals that have been mixed in the exhaust gas. Therefore, it is necessary to remove these harmful components before releasing the exhaust gas into the atmosphere. Conventionally, an activated carbon layer filled with activated carbon has been widely used as a means for removing the harmful components in the exhaust gas. .

  However, especially when removing harmful components in the exhaust gas generated by incineration or melt decomposition of waste, the activated carbon layer is relatively hot (for example, about 150 to 250 ° C.) for the purpose of preventing equipment corrosion due to condensation. ). The ignition temperature of activated carbon is usually 400 to 500 ° C. However, when organic substances or heavy metals are adsorbed on the activated carbon, the ignition temperature of the activated carbon may be reduced to about 250 ° C. due to its catalytic reaction, etc. It may lead to an accident.

  As a method of preventing such an ignition accident of the activated carbon layer, in Patent Document 1, a temperature sensor and a cooling pipe are provided in the activated carbon layer, and when the temperature of the activated carbon layer measured by the temperature sensor is equal to or higher than a predetermined temperature, A method of cooling the activated carbon layer by flowing cooling water through the cooling pipe is disclosed.

However, in Patent Document 1, since the temperature sensor is provided only at one place in the activated carbon layer, the temperature rise that leads to the ignition of activated carbon at a place away from the temperature sensor (hereinafter referred to as “ignition”). This is called “phenomenon” and is called “ignition phenomenon place”), but it cannot be detected. That is, in Patent Document 1, when an ignition phenomenon occurs in the activated carbon layer, it may not be detected depending on the position of the ignition phenomenon location, which is insufficient as a method for predicting or preventing the ignition of the activated carbon layer.
JP 2003-1065 A

  The problem to be solved by the present invention is that when an ignition phenomenon occurs in the activated carbon layer, it can be detected regardless of the position of the ignition phenomenon, and the ignition of the activated carbon layer is reliably predicted, thereby preventing ignition. An object is to provide a method and apparatus for predicting the ignition of an activated carbon layer.

  In the activated carbon layer for predicting the ignition of the activated carbon layer filled with activated carbon to adsorb and remove harmful components in the exhaust gas, the present invention starts at any position within the activated carbon layer and is within 1 m from each starting point. A plurality of temperature sensors are arranged so that there is at least one temperature sensor, and it is judged that there is a risk of ignition when at least one of the temperatures measured by the plurality of temperature sensors exceeds a predetermined temperature. It is.

  As described above, in the present invention, by arranging a plurality of temperature sensors so that there is at least one temperature sensor in an area of 1 m from each starting point in the activated carbon layer, the ignition phenomenon occurs at any position in the activated carbon layer. Even if it occurs, this can be detected.

  The arrangement standard of at least one temperature sensor in this 1 m area is based on the following knowledge.

  FIG. 3 shows the measured temperature of the temperature sensor at the shortest distance from the ignition phenomenon location and the others with respect to the distance between the ignition phenomenon location and the temperature sensor at the shortest distance when a plurality of temperature sensors are arranged in the activated carbon layer. This is a result of calculating the difference in temperature measured by the temperature sensor with the temperature of the ignition phenomenon being 250 ° C. and the ambient temperature as a parameter. In addition, it is known that ignition accidents of the activated carbon layer often occur immediately after the shutdown, and the ambient temperature of 160 ° C. is assumed immediately after the shutdown, and the ambient temperature of 100 ° C. is several hours after the shutdown. Is assumed.

  As shown in FIG. 3, when the distance (horizontal axis) between the ignition phenomenon location and the temperature sensor at the shortest distance is 0.6 m, for example, when the ambient temperature is 160 ° C., the measured temperature of other ambient temperature sensors Temperature difference (vertical axis) is 30 ° C., and the ambient temperature is 100 ° C., the temperature difference is 50 ° C. In order to reliably capture the ignition phenomenon with an actual activated carbon layer, a minimum temperature difference of 20 ° C. is necessary as a temperature difference from the surroundings. Therefore, according to the results of FIG. A plurality of temperature sensors are arranged so that there are two temperature sensors.

  The size of the area where at least one temperature sensor is arranged is smaller than 1 m, and the detection accuracy of the ignition phenomenon is improved. However, considering the balance with the installation cost of the temperature sensor, it is actually less than 0.4 m. Although it is not appropriate, when the detection accuracy is improved or the device becomes large, it is effective to apply a cable sensor device using an optical fiber that is cost-effective.

  In the present invention, as described above, it is determined that there is a risk of ignition when at least one of the temperatures measured by the plurality of temperature sensors arranged in the activated carbon layer becomes equal to or higher than a predetermined temperature. This predetermined temperature is set according to the ambient temperature during normal operation of the activated carbon layer, specifically, a temperature that is 20 ° C. higher than the ambient temperature.

  Further, in the present invention, when it is determined that there is a risk of ignition in the activated carbon layer, nitrogen gas or inert gas is introduced into the activated carbon layer by gas introduction means to prevent ignition, and the inside of the activated carbon layer is nitrogen gas or inert. Fill and purge with gas. In addition, if the temperature measured by the temperature sensor does not fall below the predetermined temperature even after a predetermined time has elapsed after introducing nitrogen gas or inert gas into the activated carbon layer, or the temperature during introduction of nitrogen gas or inert gas When the temperature measured by the sensor rises, it is determined that ignition has actually occurred and expanded, and water is sprayed on the activated carbon layer by watering means to prevent the expansion of ignition.

  According to the present invention, since the ignition of the activated carbon layer can be reliably predicted and an appropriate ignition prevention measure can be taken, the ignition of the activated carbon layer can be prevented and the activated carbon layer can be used safely and effectively.

  Embodiments of the present invention will be described below based on examples shown in the drawings.

  FIG. 1 is a cross-sectional view of an activated carbon adsorption tank to which the present invention is applied. The activated carbon adsorption tank shown in the figure has two activated carbon layers 1, exhaust gas is introduced into the activated carbon adsorption tank from the left side of the figure, and the activated carbon layer 1 is allowed to pass through and discharged as indicated by arrows in the figure.

  FIG. 2 is a perspective view showing an arrangement example of the temperature sensor 2 arranged in the activated carbon layer 1. In the figure, the activated carbon layer 1 has a height of 2200 mm, a width of 2100 mm, and a thickness of 430 mm. Within the activated carbon layer 1, temperature sensors 2 are arranged at a total of nine locations at intervals shown in FIG. . In addition, the unit of the number of the space | interval shown in FIG. 2 is mm.

  As shown in FIG. 2, the maximum length of the interval between the temperature sensors 2 is 507 × 2 mm, and even if an ignition phenomenon occurs at the midpoint, the distance between the temperature sensor 2 and the temperature sensor 2 at the shortest distance is 507 mm. . That is, the arrangement example of FIG. 2 satisfies the criterion of the present invention in which a plurality of temperature sensors 2 are arranged such that at least one temperature sensor 2 exists within an area of 1 m from the ignition phenomenon location.

  In the present invention, it is determined that there is a risk of ignition when at least one of the temperatures measured by these temperature sensors 2 exceeds a predetermined temperature, that is, an ignition phenomenon has occurred.

  When this ignition phenomenon is detected, the exhaust gas introduction path valve 3 a and the exhaust gas discharge path valve 3 b shown in FIG. 1 are closed, the nitrogen gas introduction path valve 4 a is opened, and the activated carbon layer is formed by the nitrogen gas introduction means 4. Nitrogen gas is introduced into 1 and the activated carbon layer 1 is sealed and purged with nitrogen gas to prevent the occurrence of a fire accident. At this time, in order to prevent the exhaust gas from leaking into the activated carbon layer 1 from the exhaust gas introduction path, the pressure value of the pressure gauge 5a installed in the activated carbon layer 1 is the pressure installed upstream of the valve 4a in the nitrogen gas introduction path. The degree of opening and closing of the valve 3b in the exhaust gas discharge path is adjusted so that the pressure value of the total 5b is +0.5 kPa. Alternatively, a highly airtight valve 3a in the exhaust gas introduction path can be selected.

  After elapse of a predetermined time (for example, 30 minutes) from the start of the nitrogen gas purge, it is confirmed by the oxygen meter 3c installed in the exhaust gas discharge path that the oxygen concentration is 0.5% or less, and the nitrogen gas purge is terminated.

  However, if the temperature measured by the temperature sensor 2 that detects the ignition phenomenon does not drop below the predetermined temperature even after a predetermined time has elapsed since the start of the nitrogen gas purge, or if a temperature increase is detected during the nitrogen gas purge, It is judged that the ignition has actually occurred and expanded, and the valve 6a installed in the watering path is opened, and water is sprayed from the watering nozzle 6b at the tip of the watering means 6 to the activated carbon layer 1 to prevent the expansion of the ignition.

  The watering amount is integrated by the flow meter 6c, and when a predetermined amount is sprinkled, the watering is terminated. This watering amount is set to about 40 to 60% of the activated carbon filling amount of the activated carbon layer 1.

  The detection of the ignition phenomenon by the temperature sensor 2 described above and the execution of the ignition prevention measure by the subsequent valve operation or the like can be performed manually, or automatically by connecting the temperature sensor 2 or each valve to the control device. You can also.

It is a cross-sectional view of the activated carbon adsorption tank to which the present invention is applied. It is a perspective view which shows the example of arrangement | positioning of the temperature sensor arrange | positioned in the activated carbon layer of the activated carbon adsorption tank shown in FIG. This is a graph plotting the calculation results of the relationship between the location of the ignition phenomenon and the temperature sensor at the shortest distance, and the difference between the measurement temperature of the temperature sensor at the shortest distance from the ignition phenomenon and the measurement temperature of the other temperature sensors. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Activated carbon layer 2 Temperature sensor 3a, 3b Valve 3c Oxygen meter 4 Nitrogen gas introduction means 4a Valve 5a, 5b Pressure gauge 6 Watering means 6a Valve 6b Watering nozzle 6c Flowmeter

Claims (6)

An activated carbon layer ignition prediction method for predicting ignition in an activated carbon layer filled with activated carbon to adsorb and remove harmful components in exhaust gas,
Starting from every position in the activated carbon layer, the temperature in the activated carbon layer is measured with a plurality of temperature sensors arranged so that there is at least one temperature sensor in a region 1 m from each starting point, and the plurality of temperature sensors An ignition prediction method for an activated carbon layer that determines that there is a risk of ignition when at least one of the measured temperatures is equal to or higher than a predetermined temperature.   2. The method for predicting ignition of an activated carbon layer according to claim 1, wherein nitrogen gas or inert gas is introduced into the activated carbon layer when at least one of the temperatures measured by the plurality of temperature sensors becomes equal to or higher than a predetermined temperature.   After introduction of nitrogen gas or inert gas into the activated carbon layer, if the temperature measured with the temperature sensor does not drop below the predetermined temperature even after a predetermined time has passed, or measured with the temperature sensor while introducing nitrogen gas or inert gas The method for predicting ignition of an activated carbon layer according to claim 2, wherein water is sprayed on the activated carbon layer when the temperature rises. An ignition prediction device for an activated carbon layer for predicting ignition in an activated carbon layer filled with activated carbon to adsorb and remove harmful components in exhaust gas,
An ignition prediction apparatus for an activated carbon layer in which a plurality of temperature sensors are arranged such that at least one temperature sensor exists in a region 1 m from each starting point, starting from any position in the activated carbon layer.   5. The activated carbon layer according to claim 4, further comprising gas introduction means for introducing nitrogen gas or an inert gas into the activated carbon layer when at least one of the temperatures measured by the plurality of temperature sensors becomes equal to or higher than a predetermined temperature. Ignition prediction device.   After introduction of nitrogen gas or inert gas into the activated carbon layer, if the temperature measured with the temperature sensor does not drop below the predetermined temperature even after a predetermined time has passed, or measured with the temperature sensor while introducing nitrogen gas or inert gas The ignition prediction apparatus of the activated carbon layer according to claim 5, further comprising watering means for spraying water on the activated carbon layer when the temperature rises.

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