JP5088919B2 - Cement baking apparatus and waste treatment method - Google Patents

Description

  The present invention uses a cement firing device capable of efficiently treating waste and recycled resources, and further expanding the limit of the amount of waste treated or the amount of recycled resources used, and the same device It is related with the processing method of the waste.

  Conventionally, various apparatuses and methods have been proposed in treating waste such as municipal waste with a cement baking apparatus. For example, in Patent Document 1, a part of the high temperature air of the clinker cooler is introduced into a drying device for drying waste such as municipal waste, and the exhaust from the drying device is returned to the clinker cooler again. A technique is disclosed in which high-temperature air of a clinker cooler in which is mixed is used as combustion air for a cement kiln or a calciner.

  Patent Document 2 discloses that when combustible waste is incinerated with a cement baking apparatus, combustible waste is incinerated using part of the high-temperature air of the clinker cooler, and exhaust gas generated during the waste incineration process. Is described in which a preheater for heating the cement raw material is vented and slag generated during the waste incineration process is drawn out. In both of the techniques described in these documents, waste is treated using the high-temperature air of a clinker cooler.

  In processing the waste, in the technique described in the above-mentioned patent document, it is necessary to install a drying device or the like. Therefore, in practice, as shown in FIG. 3, the place where the waste is put into the cement baking apparatus 11 equipped with the cement kiln 12, the preheater 13, and the calcining furnace 14 should sufficiently perform the thermal decomposition of the waste. In view of the fact that the capital investment can be reduced, it is concentrated in the vicinity of the kiln bottom 15 and the calcining furnace 14.

JP 63-151650 A Special table 2003-506299 gazette

  However, the kiln bottom of the cement baking apparatus and the calcining furnace are the most important areas in the cement baking apparatus that require heat for decomposition of the limestone, which is a cement raw material. Lowering the temperature by putting waste (hereinafter referred to as “waste” also includes recycled resources in this application) into this region brings about a great deterioration in thermal efficiency and an accompanying increase in the amount of exhaust gas. In addition to this, waste contains washing dust with a lot of adhering water, which further promotes deterioration of thermal efficiency and increase of exhaust gas volume. The amount of waste disposal has reached its limit. Furthermore, when various kinds of waste are processed, waste supply facilities are concentrated at the kiln bottom and the supply space has reached its limit.

  On the other hand, although a large amount of heat flows out from the calcining furnace along with the exhaust gas, the heat utilization is limited to the range of raw material preheating as before, and the deterioration of thermal efficiency due to waste input is wasted. The current situation is that it is heated. It is also possible to recover the heat of the exhaust gas from the preheater with a waste heat boiler, but when the exhaust gas temperature is about 400 ° C. or higher of the heat resistance temperature of the waste heat boiler, the exhaust gas is cooled by watering or the like. It is necessary, and this further increases the processing air volume.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and in treating waste with a cement baking apparatus, by improving the thermal efficiency and reducing the amount of exhaust gas from the preheater, The purpose is to further expand the limit of the amount of waste that can be processed in the baking equipment.

In order to achieve the above object, the present invention is a cement firing apparatus, which is a combustion gas extracted from an exhaust gas passage from an outlet duct of a calcining furnace of a cement kiln to a preheater outlet duct (however, a preheater uppermost cyclone outlet duct) The preheating furnace or / and the drying furnace for preheating or / and drying the waste, and the waste from the preheating furnace or / and the drying furnace are used as the kiln for the cement kiln. A waste supply route for supplying to the bottom, and a second for returning the exhaust gas from the preheating furnace and / or the drying furnace to the exhaust gas flow path from the exit duct of the calcining furnace of the cement kiln to the preheater outlet duct An exhaust gas flow path is provided. Here, the waste refers to sewage sludge, wood chips, waste soil, incinerated ash, and the like, and includes recycled resources as described above. The extraction position is preferably an exhaust gas flow path from the outlet duct of the lowermost cyclone to the preheater outlet duct.

According to the present invention, the combustion gas from the exhaust gas flow path from the outlet duct of the cement kiln calcining furnace to the preheater outlet duct (except the combustion gas extracted from the preheater uppermost cyclone outlet duct) and waste As a result of the heat exchange, the exhaust gas temperature of the preheater decreases, and as a result, the exhaust gas amount of the preheater decreases. Accordingly, it is possible to increase the amount of air required for cement firing or waste processing, and to expand the limit of the amount of waste processing.

Further, in the present invention, thus the from the preheating furnace and / or drying furnace and this with a waste feed route to kiln of the cement kiln, preheated or dried waste is fed to the kiln inlet part, Compared with the case where the waste is not preheated and supplied to the kiln bottom, the temperature of the kiln bottom due to the waste can be prevented from being reduced, and the thermal efficiency can be improved.

Furthermore, in the present invention, a second exhaust gas flow path for returning the exhaust gas from the preheating furnace and / or the drying furnace to the exhaust gas flow path from the exit duct of the cement kiln calcining furnace to the preheater outlet duct is provided. Therefore in the this, it is possible to process the exhaust gases from the preheating furnace and / or drying oven without discharged out of the system, preheating furnace and / or raising the temperature, etc. of the heat cement material having the exhaust gases from drying oven Can be used.

The present invention also relates to a method for treating waste in a cement firing apparatus, wherein a combustion gas (however, a preheater uppermost cyclone outlet duct) is discharged from an exhaust gas passage from an outlet duct of a calcining furnace of a cement kiln to a preheater outlet duct. (Excluding the combustion gas discharged from the waste gas) is extracted and introduced into a preheating furnace or / and drying furnace, and in the preheating furnace or / and drying furnace, the waste is preheated and / or dried, and the preheating is performed. the exhaust gas from the furnace and / or drying oven, with back from the outlet duct of the calciner of the cement kiln to an exhaust gas flow path to the preheater outlet duct, kiln of the cement kiln to the preheater and / or dry waste It supplies to a part and processes with this cement baking apparatus. Thereby, as described above, the limit frame of the amount of waste processing can be expanded, and the thermal efficiency of the cement baking apparatus can be improved.

  In the waste processing method in the cement baking apparatus, the gas flow rate in the furnace of the preheating furnace and / or the drying furnace can be determined according to the particle size or / and decomposition conditions of harmful substances contained in the waste. . As a result, the waste can be treated without discharging harmful substances contained in the waste.

  As described above, according to the present invention, it is possible to expand the limit frame of the amount of waste processed in the cement baking apparatus.

  FIG. 1 shows an embodiment of a cement firing apparatus according to the present invention. This cement firing apparatus 1 includes a cement kiln 2, a preheater 3, a calcining furnace 4, a preheating furnace 6, and a fan 7. Composed.

  The cement kiln 2, the preheater 3 and the calcining furnace 4 have the same functions as those of a conventional cement calcining apparatus. The cement raw material R supplied to the preheater 3 is preheated by the preheater 3 and calcined by the calcining furnace 4. After that, the cement kiln 2 is fired.

  The preheating furnace 6 is a characteristic part of the present invention. The waste gas W is supplied to the preheating furnace 6 and combustion gas extracted from the exhaust gas flow path from the lowermost cyclone 3A to the second cyclone 3B is supplied to the preheating furnace 6. The waste W can be preheated. The preheated waste W is brought to the kiln bottom 5 via the waste supply route 9.

  The in-furnace gas flow rate of the preheating furnace 6 and the connection location of the exhaust passage are determined by the particle size of harmful substances contained in the waste to be treated. For example, the gas flow rate is determined based on the terminal sedimentation velocity derived by Stokes' law or the like, and the exhaust gas is connected to the lower stage of the cement firing apparatus 1 as shown in FIG. Accordingly, it is possible to appropriately treat waste in a situation where the risk of discharging harmful substances out of the cement baking apparatus 1 is minimized.

  The fan 7 is provided to introduce combustion gas from the preheater 3 into the preheating furnace 6, and the exhaust of the fan 7 is returned to the exhaust gas flow path from the lowermost cyclone 3 </ b> A to the second cyclone 3 </ b> B via the circulation duct 8. .

  By preheating the waste W using the preheating furnace 6, the preheated waste W is supplied to the kiln bottom 5 via the waste supply route 9. Thereby, compared with the case where it was supplied to the kiln bottom part 5 without being preheated, the temperature fall of the kiln bottom part 5 by the waste W can be prevented.

  Further, by using the exhaust of the lowermost cyclone 3A, which has not been conventionally used, in the preheating furnace 6, the exhaust gas temperature of the preheater 3 is lowered, and consequently the exhaust gas amount of the preheater 3 is reduced. And the amount of air required for cement firing or waste treatment can be increased by the amount of exhaust gas reduction, increasing the production volume of cement clinker, or expanding the limit frame of waste treatment amount It becomes possible.

  In the above embodiment, the case where the preheating furnace 6 is attached to the cement baking apparatus 1 has been described as an example. However, instead of the preheating furnace 6, a drying furnace is provided, and waste is dried in the drying furnace. The same effect as when the preheating furnace 6 is installed can be obtained. It is of course possible to provide both the preheating furnace 6 and the drying furnace to perform both drying and preheating of the waste.

  Further, in the above embodiment, the combustion gas extracted from the exhaust gas flow path from the lowermost cyclone 3A to the second cyclone 3B is supplied to the preheating furnace 6, but from the second cyclone 3B further upstream of the preheater 3. Combustion gas can be extracted from the exhaust gas flow path to the third cyclone 3C or the exhaust gas flow path from the third cyclone 3C to the fourth cyclone 3D and supplied to the preheating furnace 6.

  Furthermore, in the above embodiment, the exhaust from the preheating furnace 6 is returned to the exhaust gas flow path from the lowermost cyclone 3A to the second cyclone 3B via the circulation duct 8, but depending on the exhaust gas temperature of the preheating furnace 6, 3 may be returned to the upstream side. Furthermore, the exhaust from the preheating furnace 6 can be treated outside the cement firing apparatus 1.

  Next, an embodiment of the present invention will be described with reference to FIG. In the present embodiment, when the washing dust W is preheated by the preheating furnace 6, the outlet gas of the second cyclone 3B is introduced into the preheating furnace 6 by the fan 7 disposed at the rear stage of the preheating furnace 6, and after the preheating. In order to decompose harmful components contained in the gas, the exhaust from the preheating furnace 6 was introduced into the outlet duct of the lowermost cyclone 3A.

  As an example, when the washing dust W is thrown into each of the kiln bottom and the preheating furnace 6 of the cement kiln 2 and the washing dust W is not thrown into the cement baking apparatus 1 as a comparative example (Comparative Example 1), The test was performed for the case where the washing dust W was charged only into the kiln bottom (Comparative Examples 2 and 3). The test results are shown in Table 1. Note that (a) to (e) in the table correspond to (a) to (e) in FIG.

  From the test results of Comparative Examples 1 to 3, as the amount of washing dust W input to the kiln bottom of the cement kiln 2 is increased, the calorific value becomes worse, and the air volume intensity at the outlet of the lowermost cyclone 3A is also worsened accordingly. doing. Further, since it is necessary to maintain the preheater exhaust gas temperature at 430 ° C. or less in relation to a waste heat power generation facility (not shown) arranged on the downstream side of the fourth cyclone 3D, the sprinkling S at the outlet of the third cyclone 3C. As a result, the air volume basic unit of the preheater exhaust has further deteriorated.

  On the other hand, according to the present example, although the amount of the washing dust W charged into the cement baking apparatus 1 is larger than that in the comparative example 3, the air volume basic unit of the lowermost cyclone 3A is larger than that in the comparative example 3. It can be seen that the amount of sprinkling S at the outlet of the third cyclone 3C can be reduced, and the unit air volume of the preheater exhaust is also improved.

It is the schematic which shows the whole structure of one Embodiment of the cement baking apparatus concerning this invention. It is the schematic which shows the whole structure of one Example of the cement baking apparatus concerning this invention. It is the schematic which shows the whole structure of an example of the conventional cement baking apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cement baking apparatus 2 Cement kiln 3 Preheater 3A Bottom cyclone 3B 2nd cyclone 3C 3rd cyclone 3D 4th cyclone 4 Calciner 5 Kiln bottom 6 Preheating furnace 7 Fan 8 Circulation duct 9 Waste supply route R Cement raw material S Sprinkling W Waste (Washing dust)

Claims (3)

Combustion gas extracted from the exhaust gas passage from the exit duct of the cement kiln calcining furnace to the preheater outlet duct (excluding the combustion gas extracted from the preheater uppermost cyclone outlet duct) is supplied, and waste preheating or / And a preheating furnace or / and a drying furnace for performing drying ,
A waste supply route for supplying waste from the preheating furnace or / and drying furnace to the kiln bottom of the cement kiln;
Cement comprising a second exhaust gas flow path for returning exhaust gas from the preheating furnace or / and drying furnace to an exhaust gas flow path from an outlet duct of the calcining furnace of the cement kiln to a preheater outlet duct. Firing equipment. From the exhaust gas flow path from the exit duct of the cement kiln calcining furnace to the preheater outlet duct, a part of the combustion gas (excluding the combustion gas discharged from the preheater uppermost cyclone outlet duct) is extracted to extract the preheating furnace or / And introduced into the drying furnace,
In the preheating furnace or / and drying furnace, the waste is preheated and / or dried,
The exhaust gas from the preheating furnace or / and the drying furnace is returned to the exhaust gas flow path from the exit duct of the calcining furnace of the cement kiln to the preheater exit duct,
Method of treating waste in cement burning device characterized by the preheating and / or dry waste fed to the kiln of the cement kiln, is treated with the cement burning device. The cement baking apparatus according to claim 2 , wherein a gas flow rate in the furnace of the preheating furnace or / and the drying furnace is determined according to a particle size or / and a decomposition condition of a harmful substance contained in the waste. Waste disposal method.

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