JP2012041223A - Treating method for cement kiln extraction gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of emergence of a chlorine bypass dust in order to raise chlorine removal efficiency in chlorine bypass equipment, and to stabilize the contents of chlorine and calcium of a chlorine bypass dust in order to prevent destabilization, etc., of a cement quality when the chlorine bypass dust is added to cement.SOLUTION: In a treating method for a cement kiln extraction gas, when cooling and simultaneously extracting a part G of a combustion gas from a kiln exhaust gas channel continued from a kiln inlet of a cement kiln 2 to a lowest step cyclone, separating a coarse powder D1 from an extraction gas G1, and collecting a fine powder from an extraction gas G2 containing a fine powder D2, the concentration of dust (D1+D2) accompanied to the extraction gas G1 or the classification point of a cyclone (classifier) 4 for isolating the coarse powder D1 from the extraction gas G1 is adjusted, in order to restrict the chlorine concentration of the fine powder D2 to 10 mass% or higher and the CaO concentration of the fine powder D2 to 35 mass% or lower.

Description

  The present invention relates to a method for treating a cement kiln extraction gas, and more particularly, to a method for treating combustion gas extracted from a kiln exhaust gas flow path from the bottom of the cement kiln to the bottom cyclone in order to remove chlorine.

  Conventionally, a chlorine bypass facility for removing chlorine that causes problems such as blockage of a preheater in a cement manufacturing facility has been used. In recent years, recycling of waste by converting to cement raw material or fuel has been promoted, and as the amount of waste processed increases, the amount of volatile components such as chlorine brought into the cement kiln also increases, and the amount of chlorine bypass dust generated is reduced. There are problems such as an increase and a decrease in chlorine removal efficiency in the chlorine bypass facility.

  In addition, when processing the recovered chlorine bypass dust, the chlorine content and calcium content (CaO) content of the dust is not stable. There are also problems such as lack of equipment capacity during processing.

On the other hand, in Patent Document 1, in order to improve handling of fine dust recovered from cement kiln extraction gas, the temperature of the extraction gas is extracted when extracting a part of the exhaust gas at the bottom of the preheater or the kiln bottom of the cement kiln. Is maintained in the range of 950 ° C. to 1150 ° C., and the extracted gas is cooled below the melting point of the chlorine compound. By collecting and removing from the gas, the chlorine concentration of the collected fine dust is adjusted to a range of 5 to 20% while maintaining the amount of fine dust to be collected in the range of 50 to 150 g / m ³ N. Technology is disclosed.

JP 2010-89994 A

  The present invention has been made in view of the above problems in the prior art, and reduces the amount of chlorine bypass dust generated, increases the chlorine removal efficiency in the chlorine bypass facility, and improves the chlorine content of the chlorine bypass dust. The purpose is to stabilize the CaO content and prevent destabilization of cement quality when added to cement.

  In order to achieve the above object, the present invention provides a method for treating a cement kiln extraction gas, wherein the extraction is performed while cooling a part of the combustion gas from the kiln exhaust gas passage from the bottom of the cement kiln to the bottom cyclone. When the coarse powder is separated from the extracted gas and the fine powder is collected from the extracted gas containing fine powder, the concentration of dust accompanying the extracted gas while cooling or the gas extracted while cooling By adjusting the classification point of a classifier that separates coarse powder from the above, the fine powder has a chlorine concentration of 10 mass% or more and a CaO concentration of 35 mass% or less.

  According to the present invention, by adjusting the dust concentration or the classification point of the classifier, the amount of chlorine bypass dust generated can be reduced, and the chlorine removal efficiency in the chlorine bypass facility can be increased. The chlorine content of fine powder (chlorine bypass dust) and the CaO content can be stabilized. Therefore, when fine powder is added to cement, destabilization of cement quality can be prevented, and equipment capacity is insufficient at the time of dust washing treatment, or installation of excessive equipment can be avoided.

In the cement kiln extraction gas processing method, the dust concentration in the gas extracted while cooling can be set to 120 g / m ³ N or less. Thereby, the chlorine concentration of fine powder can be 10 mass% or more.

  Also, the chlorine concentration and CaO concentration of the fine powder can be adjusted by measuring the 10 μm passage of the fine powder and adjusting the classification point of the classifier that separates the coarse powder from the gas extracted while cooling. . Since there is a correlation between the 10 μm passage of fine powder and the chlorine concentration and CaO concentration of fine powder, the chlorine concentration and CaO concentration of fine powder can be adjusted efficiently by measuring the 10 μm passage and adjusting the classification point of the classifier. Can do.

  Furthermore, the chlorine concentration can be 10 mass% or more and the CaO concentration can be 35 mass% or less by setting the 10 μm passage of the fine powder to 80 mass% or more.

  In the cement kiln extraction gas processing method, the amount of gas extracted from the kiln exhaust gas passage from the bottom of the cement kiln to the lowest cyclone is set to 0.1 volume of combustion gas flowing through the kiln exhaust gas passage. % Or more and 30% by volume or less, and even if the amount of gas extracted is increased, the chlorine concentration and calcium (CaO) concentration of the fine powder can be maintained within a preferable range.

In the cement kiln extraction gas processing method, the cooling air volume of an extraction device for extracting air while cooling a part of the combustion gas from the kiln exhaust gas passage from the bottom of the cement kiln to the lowermost cyclone, and / or the extraction air By adjusting the insertion length of baffle plates installed above and below the extraction port of the apparatus, the dust concentration in the gas extracted while cooling can be reduced to 120 g / m ³ N or less.

Further, the present invention is an extraction device for extracting air while cooling a part of the combustion gas from the kiln exhaust gas passage from the kiln bottom of the cement kiln to the lowermost cyclone, and the dust concentration in the extracted gas is determined. A dust concentration measuring device to be measured, and a dust concentration adjusting means for adjusting the dust concentration measured by the dust concentration measuring device to 120 g / m ³ N or less are provided. According to the present invention, by adjusting the dust concentration in the extracted gas to 120 g / m ³ N or less, it is possible to stabilize the chlorine content and CaO content of fine powder (chlorine bypass dust) recovered at a later stage. The chlorine concentration of the fine powder can be 10% by mass or more.

  As described above, according to the present invention, the amount of chlorine bypass dust generated is reduced, the chlorine removal efficiency in the chlorine bypass facility is increased, and the chlorine and calcium content of the chlorine bypass dust is stabilized. It is possible to prevent destabilization of cement quality when added to cement.

It is the schematic which shows the chlorine bypass installation to which the processing method of the cement kiln extraction gas concerning this invention is applied. It is the schematic which shows the baffle plate installed in the upper and lower sides of the extraction port of the probe which comprises the chlorine bypass installation of FIG. It is a graph which shows the relationship between the inlet dust density | concentration of the probe (bleeding apparatus) of a chlorine bypass facility, and the chlorine density | concentration of chlorine bypass dust. It is a graph which shows the 10 micrometer passage part of chlorine bypass dust, and the relationship of chlorine concentration. It is a graph which shows the 10 micrometer passage part of chlorine bypass dust, and the relationship of CaO density | concentration.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a chlorine bypass facility to which a cement kiln extraction gas processing method according to the present invention is applied. This chlorine bypass facility 1 is a kiln extending from the kiln bottom of a cement kiln 2 to a lowermost cyclone (not shown). From the exhaust gas flow path, a probe 3 for extracting while cooling a part of the combustion gas G, a cyclone 4 as a classifier for separating coarse dust D1 contained in the extracted gas G1 extracted by the probe 3, and a cyclone 4 The heat exchanger 5 that cools the extracted gas G2 containing the fine powder D2 discharged from the air, the bag filter 6 that collects the extracted gas G3 from the heat exchanger 5, and the heat exchanger 5 and the bag filter 6 that are discharged. It includes a dust tank 7 that stores dust (D3 + D4), an exhaust fan 8 that discharges exhaust gas G4 from the bag filter 6 to the atmosphere, and the like.

  With the above configuration, when a part of the combustion gas in the cement kiln 2 is extracted while being cooled by the probe 3, fine crystals of chlorine compound are generated, and chlorine is unevenly distributed on the fine powder side of the dust contained in the extracted gas G1. The coarse powder D1 classified by the cyclone 4 is returned to the cement kiln system. On the other hand, the extraction gas G2 containing the fine powder D2 separated by the cyclone 4 is introduced into the heat exchanger 5 to perform heat exchange between the extraction gas G2 and the medium. The extraction gas G3 cooled by the heat exchange is introduced into the bag filter 6, and the dust D4 contained in the extraction gas G3 is collected in the bag filter 6. The dust D4 collected by the bag filter 6 is once stored in the dust tank 7 together with the dust D3 discharged from the heat exchanger 5, and then added to the cement grinding mill system as chlorine bypass dust D5.

  The overall configuration and operation of the chlorine bypass facility 1 are the same as those of the conventional chlorine bypass facility. However, in the above configuration, the present invention is the concentration of dust (coarse powder D1 + fine powder D2) accompanying the extraction gas G1, or By adjusting the classification point of the cyclone 4, the chlorine concentration of the fine powder D2 is 10 mass% or more and the CaO concentration is 35 mass% or less.

  The concentration of dust (coarse powder D1 + fine powder D2) accompanying the extraction gas G1 is adjusted by installing a device for measuring the dust concentration in the extraction gas G1, such as a light scattering dust concentration meter or a light transmission dust concentration meter. When the dust concentration is high from the measurement result, the cooling air volume of the probe 3 is increased or the probe 3 is installed above and below the bleed port of the probe 3 as shown in FIG. Insertion length L of baffle plates 3a, 3b that reduces the amount of dust brought along with a part of the combustion gas G by changing the flow of ascending airflow from the cement kiln 2 near the extraction port to the preheater This is done by adjusting etc. In addition, in the dust concentration adjustment operation, a control device can be introduced to operate as a system that can automatically obtain a predetermined dust concentration.

  The classification point of the cyclone 4 is adjusted by installing a device capable of continuously measuring the particle size distribution of dust (fine powder D2) accompanying the extraction gas G2, or measuring the particle size distribution by collecting the fine powder D2 or dust D4. Thus, the opening of the variable throttle provided at the inlet of the cyclone 4 is adjusted, or the primary air amount is adjusted so as to obtain a predetermined cyclone inlet flow velocity. Furthermore, a control device can be introduced for adjusting the granularity, and the system can be operated as a system that can automatically obtain a predetermined classification point.

  In addition, the density | concentration of the dust (coarse powder D1 + fine powder D2) accompanying the extraction gas G1 is measured with the measurement part 10 arrange | positioned at the duct between the probe 3 and the cyclone 4, and the 10 micrometer passage part of the fine powder D2 is cyclone. The measurement is performed by the measurement unit 11 disposed in the duct between the heat exchanger 4 and the heat exchanger 5 or the measurement unit 12 disposed in the discharge part of the dust collected by the bag filter 6.

By adjusting the concentration of dust accompanying the extraction gas G1 as described above, the inlet dust concentration of the probe 3 and the chlorine concentration of the fine powder D2 have a relationship as shown in FIG. The lower the concentration, the higher the chlorine concentration of the fine powder D2, and the chlorine concentration of the fine powder D2 can be 10% by mass or more by setting the inlet dust concentration of the probe 3 to 120 g / m ³ N or less.

  In addition, as shown in FIG. 3, the 10 μm passage of fine powder D2 correlates with the chlorine concentration, and the chlorine concentration increases as the 10 μm passage increases, and the classification point of cyclone 4 is adjusted to pass the fine powder through 10 μm. By making the content 80% by mass or more, the chlorine concentration can be 10% by mass or more.

  Furthermore, as shown in FIG. 4, the 10 μm passage of fine powder D2 correlates with the CaO concentration, and the CaO concentration decreases as the 10 μm passage increases, and the classification point of cyclone 4 is adjusted to allow the fine powder to pass through 10 μm. By making the content 80% by mass or more, the CaO concentration can be 35% by mass or less.

  As described above, by adjusting the concentration of dust (coarse powder D1 + fine powder D2) accompanying the extraction gas G1 or the classification point of the cyclone 4, the amount of chlorine bypass dust D5 generated is reduced, and the chlorine bypass facility 1 Since the chlorine removal efficiency can be increased, the amount of gas extracted from the kiln exhaust gas passage from the kiln bottom of the cement kiln 2 to the lowermost cyclone is set to 30% by volume of the combustion gas flowing through the kiln exhaust gas passage. It is also possible to increase it to the extent.

1 Chlorine bypass facility 2 Cement kiln 3 Probe 4 Cyclone 5 Heat exchanger 6 Bag filter 7 Dust tank 8 Exhaust fan 10-12 Measuring unit

Claims (7)

A portion of the combustion gas is extracted from the kiln exhaust gas flow path from the bottom of the kiln of the cement kiln to the lowermost cyclone while cooling, extracting coarse powder from the extracted gas, and capturing the fine powder from the extracted gas containing fine powder. In collecting,
By adjusting the concentration of dust accompanying the gas extracted while cooling, or the classification point of a classifier that separates coarse powder from the gas extracted while cooling, the chlorine concentration of the fine powder is 10% by mass. As mentioned above, the processing method of the cement kiln extraction gas characterized by making CaO density | concentration into 35 mass% or less. The method for treating a cement kiln extraction gas according to claim 1, wherein the dust concentration in the gas extracted while cooling is 120 g / m ³ N or less.   3. The cement kiln extraction gas according to claim 1, wherein the fine powder passes through 10 μm and adjusts a classification point of a classifier that separates coarse powder from the extracted gas while cooling. Processing method.   The treatment of cement kiln bleed gas according to claim 3, wherein a chlorine concentration is 10 mass% or more and a CaO concentration is 35 mass% or less by setting the 10 μm passage of the fine powder to 80 mass% or more. Method.   The amount of gas extracted from the kiln exhaust gas flow path from the kiln bottom of the cement kiln to the lowermost cyclone is set to 0.1 volume% or more and 30 volume% or less of the combustion gas flowing through the kiln exhaust gas flow path. The processing method of the cement kiln extraction gas in any one of Claims 1 thru | or 4 characterized by the above-mentioned. Installed above and below the bleed air outlet of the bleeder, or / and the amount of cooling air introduced into the bleeder that bleeds a part of the combustion gas from the kiln exhaust gas flow path from the bottom of the kiln of the cement kiln to the lowermost cyclone The dust concentration in the gas extracted while cooling is adjusted to 120 g / m ³ N or less by adjusting the insertion length of the baffle plate. Cement kiln extraction gas processing method. A bleeder that bleeds while cooling a part of the combustion gas from the kiln exhaust gas passage from the kiln bottom of the cement kiln to the lowermost cyclone,
A dust concentration measuring device for measuring the dust concentration in the extracted gas;
A bleeder comprising: a dust concentration adjusting means for adjusting a dust concentration measured by the dust concentration measuring instrument to 120 g / m ³ N or less.

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