JP4983231B2 - Cement clinker manufacturing method and manufacturing apparatus thereof - Google Patents

Description

The present invention relates to a method and apparatus for manufacturing a cement clinker that bleeds part of exhaust gas from a cement kiln and reduces the amount of volatile components such as alkali chloride in a cement raw material firing system.

Volatile impurities brought from cement raw fuel into cement kiln firing systems such as SP (suspension preheater method) kiln and NSP (suspension preheater method with kiln) kiln are vaporized in the high temperature kiln and air flow To return to the cement raw material preheating device (hereinafter referred to as preheater). Volatilized impurities are liquefied or solidified in the preheater, which is at a lower temperature than in the kiln, and circulated in the system by being brought back into the kiln. The concentration gradually increases, and finally adheres to the inner wall of the cement raw material firing system such as the preheater. Occurrence and growth of coaching causes the path to be blocked, causing a forced stop. As a method of solving this problem, a part of the cement kiln exhaust gas is extracted and treated from the cement raw material firing system to remove a part of the volatile components mainly composed of alkali chloride, thereby eliminating the coating trouble in the firing system. A method called chlorine bypass to suppress is known.

The principle of this chlorine bypass is that gas is extracted from inside the preheater, the gas is cooled in the exhaust gas treatment device of the chlorine bypass facility, and the volatile alkali contained in the gas is solidified and collected. By bypassing the kiln part, the amount of volatile components circulating in the cement raw material firing system is reduced.

On the other hand, in recent years, as a contribution to a recycling-oriented society, waste such as incineration ash has been used as a raw material for cement and its effective use has been promoted. With this, the amount of alkali chloride brought into cement raw material manufacturing equipment has increased. . For this reason, it is necessary to increase the extraction amount of chlorine bypass in accordance with the increase in alkali chloride brought in from waste.

The solidified volatile alkali that cools and solidifies the extracted gas and removes it outside the cement clinker production system is fine particles of about several microns, and is generally collected by a bag filter type dust collector. However, the normal heat resistant temperature of the filter cloth of the bag filter is about 200 ° C. even for high temperatures, and it is necessary to lower the temperature of the extracted exhaust gas entering the bag filter dust collector to be below the heat resistant temperature of the filter cloth in order to protect this filter cloth. .

For example, Patent Document 1 discloses a cooling method by spraying water. However, the moisture in the extracted exhaust gas becomes high. As a result, the chlorine compound is deliquescent in the bag filter portion due to moisture in the gas, which causes clogging of the bag filter. The extracted gas also contains sulfur gas, which reacts with moisture to produce sulfates, etc., which may cause corrosion of the equipment, etc., which may hinder the operation and long-term stable operation of the equipment. is there.
On the other hand, with an increase in the amount of waste used, it is assumed that the extraction rate of the extracted exhaust gas is increased. From such a viewpoint, even when the extraction rate of the extracted exhaust gas is increased, development of an apparatus system capable of stably operating the cement clinker manufacturing apparatus for a long period is awaited.

JP 62-252349 A

The present invention provides a cement clinker manufacturing apparatus capable of stably operating a cement clinker manufacturing apparatus for a long period of time while greatly improving the extraction rate of the extracted exhaust gas in addition to effectively treating the extracted exhaust gas by a simple method. It is an object of the present invention to provide a clinker manufacturing method and a manufacturing apparatus.

The inventors of the present invention have developed the present invention as a result of earnestly studying that a cement clinker production apparatus equipped with a high extraction chlorine bypass stably operates with a simple configuration.
That is, the present invention extracts a part of the exhaust gas from the cement clinker production apparatus, separates the volatile component contained in the extracted exhaust gas from the exhaust gas, reduces the volatile component in the cement clinker production apparatus, and removes the cement clinker. In the manufacturing method, the extracted exhaust gas is rapidly cooled with air, and the rapidly cooled exhaust gas is cooled with an indirect cooling device.
Further, as another invention, an extraction pipe for extracting the exhaust gas of the cement clinker production apparatus, a cooling unit connected to the extraction pipe for directly quenching the extracted exhaust gas with air, and cooling the quenched exhaust gas The cement clinker manufacturing apparatus includes an indirect cooling device for separating the solid matter contained in the indirectly cooled exhaust gas from the exhaust gas.
The solid matter referred to here is a mixture of a cement clinker raw material sucked together with a volatile component having a low melting point solidified by cooling and an exhaust gas extracted.

According to the present invention, the processing air volume of the extracted exhaust gas can be reduced. In addition, the solid matter contained in the exhaust gas can be easily separated from the exhaust gas. As a result, the extraction rate of the extracted exhaust gas can be greatly improved, and the use of waste as a raw fuel for cement production can be expanded. By reducing volatile components, such as alkali chloride, the trouble of the baking apparatus of a cement raw material can be eliminated by these, and a cement clinker can be manufactured stably.

FIG. 1 is a schematic view of a first embodiment of a cement clinker manufacturing apparatus using the present invention. The cement clinker manufacturing apparatus includes a pre-heater 1B for preheating and pre-calcining cement clinker raw material, a kiln 1A for clinker firing, and a clinker cooler 11 for rapidly cooling the clinker fired in the kiln 1A. The extraction pipe 2 is connected to the wall surface of the rising duct 1C. In order to rapidly cool the kiln exhaust gas from the rising duct 1C, the kiln exhaust gas is led to the cooling chamber 3 which is a cooling unit via the extraction pipe 2. Air is blown into the cooling chamber 3 by a cooling air fan 4. Thereby, exhaust gas is rapidly cooled and rapidly cooled below the melting point of the volatile alkali salt contained in the exhaust gas. Volatile components in the rapidly cooled exhaust gas are sufficiently cooled and solidified in the cooling chamber 3, sucked by an exhaust fan, and collected and separated by a dust collector 7 as a separating means. Thereby, the volatile component in a cement clinker manufacturing apparatus can be reduced.

  A method for directly quenching the extracted exhaust gas with air will be described in more detail. The temperature of the extracted exhaust gas is 1000 to 1200 ° C. Air is at ambient temperature. Direct quenching refers to heat exchange by bringing the extracted exhaust gas and cooling air into direct contact. Rapid cooling refers to a cooling rate of 600 to 800 ° C./second. The temperature of the exhaust gas after quenching is 300 to 600 ° C. The temperature after cooling is appropriately controlled by the temperature and air volume of the extracted exhaust gas and the temperature and air volume of the cooling air.

  The exhaust gas containing the rapidly cooled solid matter is cooled by an indirect cooling device before being introduced into the dust collector 7. In the indirect cooling device 6, almost all of the ducts connecting the dust collector 7 have a double pipe structure. Extracted exhaust gas is passed through a pipe inside the double pipe, and cooling air is passed between the inner and outer pipes. As a result, the extracted gas is indirectly cooled and lowered to a temperature lower than the heat resistance temperature of the dust collector. The double pipe type cooler may be divided into a plurality of parts in order to increase the cooling efficiency. The number of divisions is appropriately determined in the range of 2 to 5 in consideration of costs such as the amount of cooling air flow and the length of the double tube cooler so that the temperature after heat exchange of the cooling air is about 60 to 100 ° C. Is done. Further, the method of passing the cooling air through the cooling duct is forced ventilation by a fan and may be either suction or pushing. As a result, the extracted exhaust gas can be effectively cooled and solid matter can be removed. In addition, even when the exhaust gas extraction rate is increased, it does not cause an increase in the amount of gas to be processed due to an increase in cooling air, so that it is possible to prevent an increase in the size of gas extraction equipment such as a dust collector and a fan. it can. Here, the bleed rate is defined as the ratio of the bleed gas capacity (converted to the standard state) extracted per unit time to the kiln exhaust gas capacity (converted to the standard state) flowing in the cement clinker production apparatus per unit time. According to the present invention, for example, a high bleed rate of 5 to 15% by volume can be achieved.

  It is preferable that the cooling air for cooling the extracted exhaust gas is blown in the tangential direction of the cooling chamber 3 by the cooling air fan 4 to form a swirling flow and introduced into the cooling chamber 3. The extracted exhaust gas is mixed and rapidly cooled in the cooling chamber 3 with air that forms a swirling flow along the inner wall of the cooling chamber 3. Thereby, a volatile compound turns into a solidified material. As a result, by forming the air curtain along the inner wall of the extraction pipe 2, it is possible to suppress the occurrence of coaching on the inner wall of the extraction pipe 2.

  A chamber 5 can be provided between the cooling chamber 3 and the indirect cooling device 6. The chamber 5 has a shape in which the flow passage area is rapidly expanded to 4 to 6 times the duct connecting the cooling chamber 3 and the indirect cooling device 6 and plays a role of rapidly promoting the mixing of the cooling air and the extracted exhaust gas. Bear. The position of the chamber 5 is preferably in a range where the swirling flow of cooling air remains on the downstream side of the cooling chamber 3.

The exhaust gas outlet of the dust collector 7 which is a separation means is connected to the cooling medium inlet of the clinker cooler 11. As a result, the exhaust gas from which the solid matter has been removed in the dust collector 7 is introduced into the air chamber as a cooling medium provided in the lower part of the clinker cooler 11 via the clinker cooler blowing fan 15 through the exhaust gas duct 9 and clinker cooling. It is used as mixed air. The mixed air of the bleed exhaust gas after the dust collector and the cooler exhaust high-temperature air is ejected from the lower air chamber of the clinker cooler to the upper surface of the grate from a hole of a plate called a perforated plate-shaped grate that serves as a partition between the clinker layer and the lower air chamber, The temperature is raised by exchanging heat while passing through the inside of the high-temperature clinker layer moving on the upper surface of the Great. Thereafter, since the amount of the extracted gas is suppressed, the flow returns to the cement raw material firing apparatus, and the entire amount of the extracted gas is used as the combustion air for the fuel used in the kiln or calciner. This method replaces the normally used atmosphere with the exhaust gas extracted after the dust collector, and there is almost no heat loss.

The exhaust gas from which the solid matter has been removed in the dust collector 7 can also be heated and introduced into the clinker cooler 11 by heating. As a result, the temperature of the mixed air rises, the temperature above the dew point of sulfuric acid or the like caused by SOx can be maintained in the air chamber below the clinker cooler, and corrosion in the apparatus due to sulfuric acid or the like can be prevented. As a means for raising the temperature, direct mixing of hot air can be mentioned.
As the direct mixing, as shown in FIG. 2, it is mixed with the high temperature air of the clinker cooling cooler exhaust gas carried by the cooler exhaust high temperature air return duct 16, and the lower part of the clinker cooler 11 is connected via the clinker cooler blowing fan 15. This can be achieved by introducing it into the air chamber. Thermal efficiency can be improved by recovering waste heat discharged from the rear of the clinker cooler by using and recovering it as mixed air for clinker cooling. The connection position of the exhaust gas duct 9 and the cooler exhaust hot air return duct 16 is not particularly limited as long as it is on the suction side of the clinker cooler blowing fan 15.

An embodiment of the present invention will be described with reference to FIG. A 14,000 m 3 N / h kiln exhaust gas corresponding to a 10% extraction amount was extracted from an extraction pipe 2 for extracting the kiln exhaust gas at a temperature of 1100 ° C. installed on the wall surface on the kiln side of the rising duct 1C. The extracted exhaust gas was introduced into the cooling chamber 3 via the extraction pipe 2. The exhaust gas introduced into the cooling chamber 3 was cooled to 380 ° C. by the air blown into the cooling chamber 3 as a swirling flow by the cooling air fan 4. The cooling air had a temperature of about 25 ° C. and was mixed and cooled by blowing about 4 times the amount of the extracted gas.

Volatile components in the exhaust gas were further mixed between the cooling chamber 3 and the chamber 5 and sufficiently cooled to become fumes, which were sucked into the exhaust fan 13 and collected and removed by the dust collector 7. The chamber 5 was installed at a position 10 times the duct diameter from the cooling chamber 3. The dust collector 7 is a bag filter type, and the heat resistance temperature of the filter cloth of the dust collector is 200 ° C.

80% of the bleed exhaust gas duct 20 connecting the dust collector 7 from the chamber 5 was a double pipe type cooler having a double pipe structure. The inner pipe of the double pipe has the same diameter as the extraction exhaust gas duct 20 of the extraction equipment, the outer diameter of the inner pipe is 1150 mm, and the outer diameter of the outer pipe is 1500 mm. The extraction gas is an indirect cooler having a structure in which the inside of the double pipe flows in the pipe and the cooling air flows between the inner pipe and the outer pipe. Outside the inner tube, fins having a height of 160 mm were installed at intervals of 36 divisions in the circumference, approximately the same length as the outer tube in the longitudinal direction of the tube. The double pipe type cooler was divided into three parts, and the length of each divided section was 20 to 40 m. The method of passing the cooling air through the cooling duct was forced suction ventilation with a fan.

The cooling air of the double-tube cooler installed separately uses outside air of about 25 ° C. The air volume is about 1100m3 / min for the 1st and 2nd stage, and the inlet of the dust collector 7 is for the 3rd stage. The temperature was controlled at 800 to 1200 m <3> / min to reach 200 [deg.] C. The cooling air was made to flow countercurrently to the extraction gas flow. During this time, heat exchange of 2 to 3 GJ / h was performed from the extracted exhaust gas to the cooling air in each section of the double-tube cooler, and the inlet temperature of the dust collector 7 could be managed at approximately 200 ° C.

The exhaust gas from the dust collector 7 was led to the suction position of the clinker cooler air blowing fan 15 through the exhaust gas duct 9. During this time, the exhaust gas temperature decreased to around 160 ° C. due to heat dissipation loss and the like. On the other hand, the cooler exhaust hot air exhausted from the clinker cooler after dust removal by the electric dust collector 12 was led to the upstream position of the clinker cooler cold air blowing fan 15 through the cooler exhaust hot air return duct 16. At that time, the mixing amount of the cooling air is adjusted by the opening degree of the damper of the cooling air intake port (not shown) installed in the cooler exhaust hot air return duct 16 and the temperature of the cooler exhaust hot air 260 is adjusted. The temperature was controlled to be 180 ° C. which is lower than the heat resistance temperature of the clinker cooler air blowing fan 15. The exhaust gas exhausted after the dust collector and the clinker cooler exhaust gas from the dust collector 7 are mixed upstream of the clinker cooler cool air blowing fan 15 to become clinker cooling air, and the clinker cooler 11 is connected via the clinker cooler cool air blowing fan 15. It was introduced into the lower air chamber. The temperature of the lower air chamber of the clinker cooler 11 exceeded 130 ° C., which is the dew point of sulfuric acid or the like in the gas state of this example, and corrosion inside the apparatus due to sulfuric acid or the like was not observed. The mixed gas introduced into the lower air chamber was heat-exchanged with a high-temperature clinker, then supplied to a calcining furnace as fuel combustion air for manufacturing a cement clinker, and returned to the cement clinker manufacturing apparatus.

Indirect cooling of the extracted exhaust gas with a double pipe reduces the amount of gas and keeps it below the amount of air required for fuel combustion for cement clinker production. I was able to. As a result, the SOx contained in the exhaust gas extracted after the dust collector is decomposed, adsorbed, or combined into a solid form by combustion heat or contact with the cement raw material, and is not discharged in a gaseous form outside the cement clinker production system. It was able to operate without environmental problems. In addition, although there is heat loss due to extraction of gas for the operation of the cement clinker production facility, even if chlorine in the raw material increases, the amount of chlorine circulation in the equipment can be greatly reduced and stable operation can be achieved. became.

As a comparative example, bleeding was performed with an equivalent facility such as a bleeder gas bleeder fan as shown in FIG. The temperature of the dust collector inlet is 380 ° C, and it rises above the heat resistance temperature of the dust collector. Therefore, cooling air is taken in from the cooling air intake port for protection, and cooling air is mixed and cooled so that the heat resistance temperature of the dust collector is 200 ° C or lower. did. In this case, in order to lower the exhaust gas at 380 ° C. to 200 ° C., about 3 times as much air mixing as the extraction gas was required. The extraction capacity of the kiln exhaust gas corresponding to the amount of cooling air required for mixing cooling is reduced from the upper limit of the suction capacity of the gas extraction fan, and the capacity of the fan and dust collector is required to extract up to 10%. It had to be about 1.5 times.

Also, since the amount of gas increases due to the mixed air, it becomes more than the amount of air necessary for fuel combustion for cement clinker production, so the entire amount cannot be returned to the cement clinker production equipment, and SOx treatment is supported. However, it was difficult to limit the amount of extraction. Furthermore, when a large amount of outside air was introduced, when the moisture in the atmosphere increased due to the weather, etc., there was a concern about the corrosion in the device due to the increase in the amount of sulfuric acid etc. generated by SOx and its moisture contained in the extracted exhaust gas. .

INDUSTRIAL APPLICABILITY The present invention can be used for a cement clinker firing apparatus that uses a large amount of waste as a cement raw fuel.

It is the schematic which shows 1st Embodiment of the cement clinker manufacturing apparatus concerning this invention. It is the schematic which shows 2nd Embodiment of the cement clinker manufacturing apparatus concerning this invention. It is the schematic which shows the structure of the conventional cement clinker manufacturing apparatus. It is an example schematic diagram of a double tube cooling device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cement baking apparatus 1A Kiln 1B Preheater 1C Rising duct 2 Extraction pipe 3 Cooling chamber 4 Cooling chamber 4 Cooling air fan 5 Chamber 6 Double pipe type cooler 7 Dust collector 8 Extraction device gas extraction fan 9 Dust collector after extraction exhaust gas duct 10 Alkali chloride capture Collection tank 11 Clinker cooling cooler 12 Cooler exhaust dust removal device 13 Cooler exhaust air flow fan 14 Cooler exhaust air chimney 15 Clinker cooler air blowing fan 16 Cooler exhaust high-temperature air return duct 17 Dust collector post-extraction exhaust gas duct 18 Double pipe Cooler cooling air flow 19 Double-pipe cooler extraction exhaust gas flow 20 Extraction exhaust duct

Claims (3)

Bled part of exhaust gases of the cement clinker manufacturing apparatus, the method of the volatile component contained in the bled exhaust gas in separated from the exhaust gas to reduce the volatile components in the cement clinker manufacturing apparatus for manufacturing cement clinker, wherein The extraction rate of the exhaust gas is 5 to 15% by volume. The extracted exhaust gas is directly quenched with air, the quenched exhaust gas is cooled with an indirect cooling device, and the exhaust gas after separating the volatile components is exhausted from the clinker cooler. And the temperature of the exhaust gas is increased to supply the clinker cooler and then the cement clinker manufacturing method. The method for producing a cement clinker according to claim 1 , wherein the air forms a swirling flow . A bleed pipe for extracting 5 to 15% by volume of the exhaust gas from the cement clinker manufacturing apparatus, a cooling unit connected to the bleed pipe for directly quenching the extracted exhaust gas with air, and cooling the quenched exhaust gas An indirect cooling device for separating the solid matter contained in the indirectly cooled exhaust gas from the exhaust gas, and connecting the outlet of the exhaust gas of the separating means and the inlet of the cooling medium of the clinker cooler, the connection Cement clinker manufacturing equipment with a clinker cooler exhaust discharge line connected to the section.

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