Device and method for cooling cement clinker

Abstract

[Problem] To provide a cooling device and a cooling method which are capable of efficiently recovering heat from cement clinker. [Solution] A cooling device 1 for cement clinker comprises: a conveying device 5 for conveying cooled cement clinker C5 to an outlet of a cement kiln 2; and an adding device for adding the cooled cement clinker C5 conveyed by the conveying device 5 to high temperature cement clinker C1 present at the outlet of the cement kiln 2. The conveying device 5 can convey cement clinker C3 immediately after being discharged from a clinker cooler 3 attached to the cement kiln 2 to the outlet of the cement kiln 2.

Description

Cement clinker cooling device and cooling method

[0001] The present invention relates to a cooling device and a cooling method for cement clinker, and more particularly to a technique for efficiently recovering heat from high-temperature cement clinker.

[0002] Conventionally, as shown in Figure 2, high-temperature cement clinker (hereinafter referred to as "clinker") C2 at 1300 to 1450°C is burned in a cement kiln (hereinafter referred to as "kiln") 2 and cooled by air A1 from a blower 4 in a clinker cooler (hereinafter referred to as "cooler") 3, and high-temperature secondary air A2 that has exchanged heat with the clinker C2 is recovered in the kiln 2. Note that the clinker C3 discharged from the cooler 3 is transported to the subsequent cement crushing process, the tertiary air A3 is used in the calciner, and the remaining air A4 is discarded.

[0003] However, with the above-mentioned conventional method, when semi-molten clinker C2 falls into the cooler 3, problems arise, such as the clinker sticking to itself or to the grate, making it impossible to transport the clinker, or the grate burning out. Meanwhile, molten clinker C2 accumulates in layers on the fixed part at the tip of the cooler 3, creating so-called "snowmen," making it difficult to operate the kiln 2. In view of these issues, in order to maintain stable operation of the kiln 2 and cooler 3, the amount of cooling air A1 must be increased, which reduces the temperature of the secondary air A2 and increases the amount of heat used by the kiln.

[0004] Figure 3 shows the air load (grate 1m) of the first chamber (the chamber closest to the kiln) in various current coolers. ２ Air volume per m ３ N / min = standard gas velocity passing through the grate (mN / min) and the heat recovery efficiency (cooler efficiency) in the cooler. The cooler efficiency is (sensible heat of the gas introduced into the kiln (secondary air) and the gas introduced into the calciner (tertiary air)) / (sensible heat of the clinker and cooling gas supplied to the cooler).

[0005] In the grate type cooler, air is blown in from under the grate that moves the clinker to cool it, and the grate is set 1m apart to prevent the grate from burning out. ２ Hit 110-140m ３The cooler is operated in an area (area Z) with a high air flow rate of N / min, which causes air to blow through, resulting in insufficient heat exchange with the clinker layer and low cooler efficiency.

[0006] On the other hand, in an air beam type cooler equipped with a mechanism that supplies cooling air to several grate plates with a dedicated fan, ２ Hit 90-100m ３ It operates at a lower air volume than the grate type (Y area), and the cooler efficiency is also good. However, the grate 1m ２ Hit 70-90m ３ N / min (X area) is the optimum point, and it is preferable to operate in this area, but there are the problems mentioned above, especially for the grate 1m. ２ Hit 70m ３ Near the damage prevention lower limit LL, the grate may be burned.

[0007] Therefore, an object of the present invention is to solve the above problems and to provide a cooling device and a cooling method that can efficiently recover heat from clinker.

[0008] In order to achieve the above object, the present invention is a clinker cooling device characterized by comprising a conveying device that conveys cooled clinker to a kiln outlet, and an adding device that adds the cooled clinker conveyed by the conveying device to high-temperature clinker present at the kiln outlet.

[0009] According to the present invention, cooled clinker is added to the high-temperature clinker at the kiln outlet, and the temperature is lowered to a temperature range of 1200 to 1300°C (preferably 1200 to 1250°C) at which the liquid phase of the clinker disappears. After that, the clinker is cooled in a cooler (air quenching cooler). This enables stable operation of the cooler and increases the thickness of the clinker layer. By solving the above problem, cooling can be performed with the necessary and sufficient cooling air, and heat recovery is also improved.

[0010] In the cooling system, the conveying device can convey the clinker to the kiln outlet immediately after it is discharged from a cooler attached to the kiln. Although cooled clinker can be extracted from a clinker silo or the like, it is more efficient to separate the clinker at the cooler outlet, which has a shorter transport distance.

[0011] The present invention also provides a method for cooling clinker, characterized in that cooled clinker is added to high-temperature clinker present at a kiln outlet, and the high-temperature clinker is mixed and cooled in the kiln.

[0012] According to the present invention, cooled clinker is added to the high-temperature clinker at the kiln outlet, and the temperature is lowered to a range where the liquid phase of the clinker disappears. After that, it is cooled in a cooler (air quenching cooler), which makes it possible to increase the thickness of the layer and effectively use the air that has efficiently exchanged heat with the clinker as combustion air (secondary air, tertiary air).

[0013] In the cooling method, the clinker immediately after being discharged from the cooler attached to the kiln can be added to the high-temperature clinker at the kiln outlet. Although cooled clinker can be extracted from a clinker silo or the like, it is more efficient to collect the clinker at the cooler outlet, which has a shorter transport distance.

[0014] The cooled clinker is added in an amount of 3% by mass to 25% by mass of the high-temperature clinker present at the kiln outlet, and the temperature of the clinker at the kiln outlet can be controlled to 1250°C to 1300°C, thereby preventing the clinker from fusing within the cooler.

[0015] Grate 1m in the first chamber of the cooler attached to the kiln ２ Cooling air volume per unit: 70m ３ N / min or more 90m ３ N / min or less, thereby improving the heat recovery efficiency in the cooler.

[0016] As described above, according to the present invention, it is possible to efficiently recover heat from high-temperature clinker while avoiding problems such as adhesion of clinker and burning of the grate.

[0017] The present invention relates to a clinker cooling device, a cooling system for clinker ...

[0018] Next, an embodiment of a clinker cooling device according to the present invention will be described in detail with reference to the drawings.

[0019] FIG. 1 shows one embodiment of a clinker cooling device according to the present invention. This cooling device 1 includes a cooler 3 that cools clinker C2 discharged from a kiln 2 with air A1 from a blower 4, and a clinker transport device 5 that transports a portion C5 of the clinker C3 discharged from the cooler 3 to the outlet of the kiln 2.

[0020] The cooler 3 is, for example, an air quenching type cooler having a plurality of grates with slits formed therein, in which cooling air A1 is blown from the bottom of the grates through the slits by a blower 4, thereby transporting the clinker C2 while cooling it.

[0021] The clinker transport device 5 is composed of a separation device 8 that separates a portion C5 of the clinker C3 discharged from the cooler 3, and a general transport device, and the transport device penetrates the kiln front hood 7 and drops the clinker C5 into the outlet of the kiln 2.

[0022] Next, the operation of the cooling device 1 will be described with reference to FIG.

[0023] During operation of the kiln 2, air A1 is introduced into the cooler 3 from the blower 4, and the clinker C2 discharged from the kiln 2 is cooled by the air A1. At the same time, a portion C5 of the clinker C3 discharged from the cooler 3 is collected and dropped into the outlet of the kiln 2 by a clinker conveying device 5. The collected clinker C5 is added in an amount of about 3 to 25% by mass (preferably 3 to 15% by mass) relative to the clinker C1. Since the clinker C3 discharged from the cooler 3 has been cooled to about 100°C, the clinker C1 present at the outlet is cooled.

[0024] As described above, by cooling the clinker C1 at the outlet beforehand with clinker C5, the viscosity of the clinker can be reduced, and as a result, the thickness of the clinker bed in the cooler 3 can be increased, allowing high-temperature secondary air A2 to be supplied to the kiln 2 and enabling efficient heat recovery from the high-temperature clinker C1. The clinker C4 that is discharged from the cooler 3 and not separated is transported to the subsequent cement grinding process.

[0025] In addition to the above effects, by introducing clinker C5 into the outlet of the kiln 2, the thickness of the clinker layer inside the kiln 2 can be increased, increasing the amount of heat recovered. Furthermore, a stable, thick layer of clinker can be stably exchanged with the air inside the cooler 3, and the clinker is less likely to adhere to each other (the clinker is less likely to become sticky), allowing for stable transport of the clinker inside the cooler 3. As a result, the operation of the kiln 2 is also stabilized.

[0026] Table 1 shows the relationship between the temperature (°C) of the high-temperature clinker (clinker C2 discharged from kiln 2), the temperature (°C) of the cooled clinker (such as the separated clinker C5), the addition rate (mass%) of the cooled clinker, and the temperature (°C) of the mixed clinker in this embodiment. Tables 1(a) and 1(b) show the case where the temperature of the cooled clinker is set to 100°C and the temperature of the mixed clinker is set to 1300°C or 1250°C, while Tables 1(c) and 1(d) show the case where the temperature of the cooled clinker is set to 30°C and the temperature of the mixed clinker is set to 1300°C or 1250°C.

[0027]

[0028] From this table, it can be seen that the clinker addition rate should be controlled according to the high-temperature clinker temperature, the cooled clinker temperature, and the mixed clinker temperature (target temperature according to the clinker quality).

[0029] In the above embodiment, the clinker C3 (C5) immediately after being discharged from the cooler 3 is dropped into the outlet of the kiln 2, but it is also possible to use clinker that has been temporarily stored in a storage tank or storage area, rather than clinker that has been immediately discharged from the cooler 3, and any clinker that has been cooled can be used.

[0030] The illustrated embodiments are merely examples and are not intended to limit the technical scope of the present invention.

[0031] 1 Clinker cooling device 2 Kiln 3 Cooler 4 Blower 5 Clinker conveying device 7 Kiln front hood 8 Separation device

Claims

1. A cement clinker cooling device comprising: a conveying device for conveying cooled cement clinker to a cement kiln outlet; and an adding device for adding the cooled cement clinker conveyed by the conveying device to high-temperature cement clinker present at the cement kiln outlet.

2. A cement clinker cooling device as described in claim 1, characterized in that the conveying device conveys cement clinker to the cement kiln outlet immediately after it is discharged from a clinker cooler attached to the cement kiln.

3. A method for cooling cement clinker, comprising adding cooled cement clinker to high-temperature cement clinker present at the outlet of a cement kiln, and mixing and cooling the high-temperature cement clinker in the cement kiln.

4. A method for cooling cement clinker according to claim 3, wherein the cooled cement clinker is cement clinker immediately after being discharged from a clinker cooler attached to the cement kiln.

5. A method for cooling cement clinker according to claim 3 or 4, characterized in that the cooled cement clinker is added in an amount of 3 mass % to 25 mass % of the high-temperature cement clinker present at the cement kiln outlet, and the temperature of the cement clinker at the cement kiln outlet is controlled to 1250°C to 1300°C.

6. Grate 1m in the first chamber of the clinker cooler attached to the cement kiln ２ Cooling air volume per unit: 70m ３ N / min or more 90m ３ 6. The method for cooling cement clinker according to claim 5, wherein the cooling rate is controlled to be equal to or less than N / min.

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