JP5823245B2 - Operation method of chlorine bypass system - Google Patents

Description

The present invention relates to a cement kiln kiln or the like to bleed part of the combustion gas operation how the chlorine bypass system to remove chlorine.

  Focusing on chlorine, sulfur, alkali, etc., which causes problems such as blockage of preheaters in cement manufacturing facilities, from the bottom of the kiln of the cement kiln to the bottom cyclone From the kiln exhaust gas flow path, a part of the combustion gas is extracted to remove chlorine.

  As an apparatus for removing chlorine and the like, for example, in Patent Document 1, a part of exhaust gas is extracted using a probe from a preheater rising duct, and the extracted exhaust gas is reduced to a melting point of halogen of 600 to 700 ° C. or lower. Reduce the amount of halogen to adhere to the dust in the exhaust gas, collect the dust in a dust collector at a high temperature of 300 ° C or higher, and return the exhaust gas after removing the dust to the suspension preheater exhaust gas line. An exhaust gas treatment device is disclosed.

  In Patent Document 2, combustion gas is extracted from a kiln bottom of a cement kiln while cooling with a probe, dust contained in the extraction gas is separated into coarse powder and fine powder by a cyclone, and the exhaust gas from the cyclone is boosted. A chlorine bypass system is described in which a fine powder containing a large amount of chlorine such as potassium chloride (KCl) is collected by a bag filter after being attracted by a fan, introduced into a cooler and cooled.

JP 2007-261886 A JP 2010-195660 A

  However, in the apparatus described in Patent Document 1, although dust attached with halogen in the extracted exhaust gas can be separated and collected in a high temperature state of 300 ° C. or higher, the cyclone type dust collecting apparatus is Since dust collection efficiency is low, there is a problem that fine powder containing a large amount of halogen cannot be efficiently recovered, and the halogen removal efficiency is lowered.

  On the other hand, in the system described in Patent Document 2, the fine powder contained in the exhaust gas of the cyclone is collected by the subsequent bag filter, so that the fine powder can be efficiently recovered. However, since the extracted exhaust gas must be cooled to 130 to 200 ° C., which is lower than the heat resistance temperature of the bag filter, it cannot be processed at a high temperature, causing not only cooling heat loss but also maintenance of the cooler. The need also arises. In addition, the use of the bag filter increases the pressure loss, and the filter cloth needs to be replaced periodically. This increases the operating cost and maintenance cost.

  The extracted gas cooled by the cooler can also be collected by an electric dust collector, but the fine powder contained in the exhaust gas after separating the coarse powder by a classifier such as a cyclone has a fine particle size and a high chlorine concentration. For this reason, there is a problem that the electric dust collector is not stably charged and the dust collection efficiency is lowered.

Therefore, the present invention has been made in view of the problems in the above-described conventional technology, and while maintaining high recovery efficiency of fine powder, it reduces cooling heat loss and pressure loss, and lowers operating cost and maintenance cost. It aims at providing the operating method of the chlorine bypass system which can be suppressed.

In order to achieve the above object, the present invention is a method for operating a chlorine bypass system , and bleeds while cooling a part of combustion gas from a kiln exhaust gas passage from a kiln bottom of a cement kiln to a lowermost cyclone. A probe, a classifier that separates coarse dust particles in the bleed gas extracted by the probe, and collects fine dust particles in the exhaust gas after separating the coarse particles by the classifier, at least at 250 ° C or higher In a chlorine bypass system comprising an electric dust collector having heat resistance, the temperature of the exhaust gas introduced into the electric dust collector is adjusted to 200 ° C. or higher and 450 ° C. or lower, and the classification point of the classifier is set to the electric adjusted based on the discharge current value or / and charge voltage value of the dust collecting apparatus, controlling the particle size of the fine powder contained in the exhaust gas introduced into the electric dust collector that And features.

  According to the present invention, the dust collection of the dust in the exhaust gas is collected by the electric dust collector having a heat resistance of at least 250 ° C. or higher, so that the collection efficiency of the fine powder can be maintained high and the cooling heat loss Can be kept low. In addition, since no cooler is required, the apparatus cost and the operation cost can be reduced. Furthermore, since no bag filter is used, an increase in pressure loss can be suppressed, and operating costs and maintenance costs can be suppressed low.

Further, by adjusting the temperature of the exhaust gas to 200 ° C. or higher 450 ° C. or less, the dust apparent electrical resistivity in the exhaust gas to be introduced into the electric precipitator, preventing re-entrainment of the dust in the electrostatic precipitator It is possible to prevent the dust collection efficiency from being lowered within the range that can be performed, and to collect the exhaust gas at a high temperature, thereby reducing the cooling heat loss.

Furthermore, by adjusting the classification point of the classifier based on the discharge current value or / and the charge voltage value of the electrostatic precipitator, by controlling the particle size of the fine powder contained in the exhaust gas introduced into the electrostatic precipitator , it is possible to perform the electrostatic stable dust collection by controlling the electrical resistivity of the dust by the electric dust collector is introduced into the dust charged in the electrostatic precipitator is stable and high dust collecting efficiency Can be maintained .

  In the operation method of the chlorine bypass system, the classification point can be adjusted to 10 μm or more and 25 μm or less. Thereby, the electrical resistivity of the dust introduced into the electrostatic precipitator can be stabilized and high dust collection efficiency can be maintained.

As described above, according to the present invention, there is provided a chlorine bypass system operation method capable of reducing cooling heat loss and pressure loss and keeping operation costs and maintenance costs low while maintaining high recovery efficiency of fine powder. It becomes possible to do.

It is an overall configuration diagram showing a chlorine bypass system for explaining a method of operating such a chlorine bypass system according to the present invention. It is a graph which shows the relationship between the classification point of the classifier of a chlorine bypass system, and the chlorine concentration of the fine powder isolate | separated with the classifier. When the classification point of the classifier of the chlorine bypass system is 10 μm and the chlorine concentration of the fine powder separated by the classifier is 23%, the gas temperature of the exhaust gas containing fine powder discharged from the classifier and the apparent electrical resistivity of the fine powder It is a graph which shows the relationship.

  Next, embodiments for carrying out the present invention will be described with reference to the drawings.

Figure 1 shows a chlorine bypass system according to the method of operating such a chlorine bypass system according to the present invention, the system 1 roughly includes the cement kiln 2 from kiln up to the bottom cyclone (not shown) As a classifier that separates the probe 3 for extracting a part of the combustion gas from the kiln exhaust gas flow path, the cooling fan 4 for supplying cold air to the probe 3, and the coarse powder D1 contained in the extracted gas G1 extracted by the probe 3. , A dust collector 6 that collects the fine powder D2 from the exhaust gas G2 containing the fine powder D2 discharged from the cyclone 5, an exhaust fan 7 that attracts the exhaust gas G3 of the electrostatic dust collector 6, and the like. The probe 3, the cooling fan 4, the cyclone 5, and the exhaust fan 7 are devices used in a conventional chlorine bypass system, and detailed description thereof is omitted.

The chlorine bypass system 1 includes an electrostatic precipitator 6, and the electrostatic precipitator 6 has a heat resistance of 250 ° C. or higher and approximately 450 ° C. or lower. For example, JP 2010-115618 A A filter type electrostatic precipitator manufactured by Furukawa Industrial Systems Co., Ltd. as described in the publication can be used.

  Next, operation | movement of the chlorine bypass processing system 1 which has the said structure is demonstrated, referring FIG.

  While extracting a part G 1 of the combustion gas from the kiln exhaust gas flow path from the bottom of the kiln 2 of the cement kiln 2 to the lowermost cyclone by the probe 3, it is cooled by the cold air from the cooling fan 4. As a result, the extraction gas is rapidly cooled to about 550 ° C. or less, and a chlorine compound microcrystal is generated. Since the fine crystals of the chlorine compound are unevenly distributed on the fine powder side of the dust contained in the extraction gas G1, the coarse powder D1 classified by the cyclone 5 is returned to the preheater attached to the cement kiln 2 as a cement raw material.

  The exhaust gas G2 containing the fine powder D2 discharged from the cyclone 5 is introduced into the electric dust collector 6, and the fine powder (chlorine bypass dust) D2 is collected. At the same time, the exhaust gas G3 from the electrostatic precipitator 6 is attracted by the exhaust fan 7, and the exhaust system of the cement kiln 2, that is, the exit side of the fan (IDF) that attracts the exhaust gas of the cement kiln 2, or the cement kiln 2 Return to the preheater attached.

  In the above operation, it is preferable to adjust the classification point (separated particle size) of the cyclone 5 to 10 μm to 25 μm. By adjusting the classification point within this range, the chlorine concentration of the fine powder D2 separated by the cyclone 5 becomes 5 to 25% from the graph shown in FIG. 2, and the fine powder (chlorine bypass dust) D2 having a high chlorine concentration is recovered. In addition, the properties of the fine powder D2 introduced into the electrostatic precipitator 6 are stabilized, and the dust collection efficiency of the electrostatic precipitator 6 is stabilized.

Further, when the operation, you adjust the temperature of the exhaust gas G2 which is introduced into the electrostatic precipitator 6 to 200 ° C. to 450 ° C.. By adjusting the temperature of the exhaust gas G2 within this range, the apparent electrical resistivity of the fine powder D2 in the exhaust gas G2 introduced into the electrostatic precipitator 6 can be prevented from being scattered again in the electrostatic precipitator 6. Can be kept within the possible range.

  For example, when the classification point of the cyclone 5 is adjusted to 10 μm and the chlorine concentration of the fine powder D2 is 23% and the moisture of the exhaust gas G2 is 2.0%, the temperature of the exhaust gas G2 as shown in FIG. When the temperature exceeds about 200 ° C., the apparent electrical resistivity 1.0E + 10 that can prevent the dust from re-scattering in the electrostatic precipitator 6 can be reduced, and the dust collection efficiency of the electrostatic precipitator 6 can be reduced. It can be avoided.

Further, the discharge current value or the charge voltage of the electrostatic precipitator 6, or based on both of these, that controls the classification point of the cyclone 5. Since the discharge current value and the charge voltage value of the electrostatic precipitator 6 are indices for determining the quality of the operation state of the electrostatic precipitator 6, by controlling the classification point of the cyclone 5 based on these values, High dust collection efficiency can be maintained.

DESCRIPTION OF SYMBOLS 1 Chlorine bypass system 2 Cement kiln 3 Probe 4 Cooling fan 5 Cyclone 6 Electric dust collector 7 Exhaust fan D1 Coarse powder D2 Fine powder G1 Extraction gas G2 Exhaust gas G3 Exhaust gas

Claims (2)

A probe for extracting air while cooling a part of the combustion gas from the kiln exhaust gas flow path from the kiln bottom of the cement kiln to the lowermost cyclone, and a classifier for separating coarse dust in the extracted gas extracted by the probe When, to the dust collecting dust of fines in the flue gas after separation of the coarse powder by該分classifier, the chlorine bypass system that Ru and an electrostatic precipitator having at least 250 ° C. or higher heat resistance,
The temperature of the exhaust gas introduced into the electrostatic precipitator is adjusted to 200 ° C. or higher and 450 ° C. or lower, and the classification point of the classifier is based on the discharge current value or / and the charge voltage value of the electrostatic precipitator. A method for operating a chlorine bypass system, comprising adjusting and controlling a particle size of the fine powder contained in the exhaust gas introduced into the electric dust collector . The method for operating a chlorine bypass system according to claim 1 , wherein the classification point is adjusted to 10 μm or more and 25 μm or less.

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