JPS6020672B2 - Powder raw material calcination equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preheating device for powder raw materials, and is particularly suitable as a suspension preheater with a temporary furnace for preheating and temporarily holding cement raw materials in an air stream.

In the field of cement production, suspension preheaters are often used to suspend cement powder raw materials in kiln exhaust gas and heat the raw materials using the heat retained in the exhaust gas.There are various types of suspension preheaters, one of which is The upright cylindrical heat exchanger shown in Figure 1 is the heat exchanger that forms an upwardly directed swirling hot gas flow b in the odor tower a and brings it into countercurrent contact with the descending cement powder raw material c to heat the raw material. There is an exchange tower type, which is in practical use. This heat exchange column type is superior to other suspension preheaters, such as those consisting of multiple cyclones and ducts, in that it has a simple structure, is self-supporting, and has low pressure loss. By the way, in the cement firing method using a suspension breheater, most of the temporary bran and firing are performed in a kiln, so there are limits to the heat load, thermal efficiency, and capacity of the kiln.

Therefore, since there is a limit to increasing the size of the kiln, a temporary furnace has recently been installed between the rotary kiln and the suspension preheater, and the heat load is shared in the front stage of the kiln, and the raw material is calcined, that is, decarboxylated there. Several models of the suspension preheater system with a temporary furnace have been developed and have achieved good results. However, most of the suspension preheaters with a temporary scale furnace that have been developed to date are those in which a temporary scale device consisting of a temporary scale furnace and a separation cyclone is combined with the suspension preheater. If the heat exchange tower type suspension preheater is simply adopted as the suspension preheater for the calcination equipment, the heat exchange tower type suspension preheater alone has the advantage of a relatively low pressure loss, but Since the pressure loss of the separation cyclone that makes up the part is quite large, the pressure loss of the entire powder material preheating and preheating device is quite large, so the separation cyclone, which causes an increase in pressure loss, is omitted. A new type of temporary competition device is desired.

The present invention can make full use of the advantages of the heat exchanger type and can omit the separation cyclone that causes increased pressure loss, significantly improving the preliminary rate of raw materials before the kiln. The object of the present invention is to provide a novel suspension preheater with a calcining furnace. 2 to 4 regarding one embodiment of the present invention.
This will be explained with reference to the figures.

In Figures 2 and 3, 1 is a vertically cylindrical heat exchange tower body having a kiln exhaust gas inlet 2 that opens tangentially to the axis, and 3 is just below the heat exchange tower body 1. A cylindrical pseudomorphic furnace 4 is made up of a cylindrical body 3a and a vice principal's inverted conical body 3b, which are arranged so that their axes coincide with each other. A spouted layer forming duct having a forced fan 6 and a damper 5 in the middle, 7 a swirling airflow forming duct branched from the duct 4 that forms a swirling upward airflow after the middle part of the bran bran furnace 3; A damper "9" installed in the duct 7 indicates a plurality of combustion burners 1 installed along the gas flow in the pseudo-drying furnace 3.
0 is a temporary bran raw material outlet provided at the bottom of the temporary lantern 3; 1
1 is a raw material chute provided between the discharge port IQ and the kiln inlet chamber 14; a throttle passage whose cross-sectional area is smaller than the horizontal cross-sectional area of the column main body 1; and 13, a kiln exhaust gas duct whose one end is connected to the inlet 2 of the main body 1 and whose pond end is connected to the chamber 14; , 15 is a rotary kiln.

In the device for distributing raw materials constructed in this way,
The child heat raw material heated by the heat retained in the exhaust gas while flowing down inside the heat exchange tower main body 1 reaches the upper end of the cylindrical calciner 3 as shown by the dotted line arrow from its lower end along the inner wall of the throttle passage 12.
It is introduced into the temporary bran furnace 3 from the circular inner side of the cylindrical body 3a.

In the inner lower part of the calcining furnace 3, combustion air (in this embodiment, exhaust gas extracted from the clinker cooler) pressurized by the forced fan 6 is ejected upward from the spouted bed forming duct 4, creating an upward air flow. In the inner upper part of the calcining furnace 3, combustion air (exhaust gas extracted from the clinker cooler in this embodiment) is introduced tangentially from the swirling airflow forming duct 7 to form a swirling upward airflow. and burner 9
The temperature is maintained at a high temperature (above a temperature sufficient for the calcination reaction to proceed) by the combustion of fuel supplied from the reactor. therefore,
The co-heated raw materials introduced into the pseudo-darkening furnace 3 come into countercurrent contact with the high-temperature swirling updraft shown by the solid line arrow, and undergo heat exchange from the center of the furnace to the wall surface due to the diffusion action. As shown in , it descends along the furnace wall surface, rises on the updraft ejected from the duct 4, is diffused from the furnace center to the wall surface by the swirling flow in the upper part of the furnace, and descends again along the furnace wall surface, The swirling movement in the vertical direction, that is, the formation of a spouted bed. In this way, the raw material, which has undergone heat exchange in the spouted bed and has been sufficiently temporarily illuminated, will eventually separate from the airflow and fall to the discharge port 10'. "Thereafter, it is guided from the chute 11 through the kiln inlet chamber 14 to the rotary kiln 15 and fired. Therefore, the present invention provides a cylindrical temporary heater directly below the vertical heat exchange hair type suspension preheater. Since it is configured to install a Akatsuki furnace to improve the temporary ratio, the base area is the same as the conventional heat exchanger type suspension preheater, and the free-standing structure can be maintained as it is, and the firing capacity is increased with a simple structure. can be increased.

In addition, the heated raw material from the heat exchange tower is guided toward the center of the cylindrical temporary furnace through the throttle passage while maintaining a countercurrent relationship with the gas flow. Not only can the calcination reaction be accelerated, but also a spouted bed is formed in the cylindrical calcination furnace, which increases the residence time of the raw materials in the heat exchange castle, which increases the heat exchange rate. However, a high calcination rate can be obtained.Furthermore, since the raw material in the calcination furnace is pre-phosphorized and discharged from the center of the bottom of the furnace, it is possible to omit the separation cyclone which causes an increase in pressure drop. This results in lower pressure drop and significantly reduced power consumption compared to a conventional preheater consisting of a spouted bed and separation cyclone combined with a suspension preheater. By providing a throttle passage in between, the preheated raw material is guided toward the center of the cylindrical calciner along the inner wall of the throttle passage while maintaining a countercurrent relationship with the gas flow, so that heat exchange, that is, temporary The competitive reaction is improved, and the constriction passage restricts and regulates the fall of the preheated raw material into the cylindrical competition furnace, increasing the residence time of the preheated raw material in the heat exchange tower body, and reducing the heat in the preheater. The effects of the present invention, such as improved replacement, are extremely large.

[Brief Description of the Drawings] Fig. 1 is a partially cutaway elevational view showing an example of a conventional cement firing device, Fig. 2 is a partially cutaway elevational view of an embodiment of the present invention, and Fig. 3 is a partially cutaway elevational view showing an example of a conventional cement firing device. FIG. 4 is a partially sectional plan view taken along section line X--X in FIG. 2, and FIG. 4 is a partially sectional plan view taken along section line Y--Y in FIG. 1... Heat exchange tower main body, 2... Kiln exhaust gas inlet, 3... Cylindrical temporary furnace, 3a...
... Cylindrical body, 3b... Vice principal inverted conical body, 4...
...Duct for forming a spouted bed, 5...Duct, 6.
... Forced fan, 7 ... Duct for forming swirling airflow, 8 ... Damper, 9 ... Burner, 10 ... Raw material discharge port, 11. ... Chute, 12 ... Throttle passage, 13 ... Kiln exhaust gas duct, 14 ... Kiln inlet chamber, 15.
...rotary kiln. Multi 1 drawing Multi 2 drawing Multi 3 drawing Multi 4 drawing

Claims (1)

[Claims] 1 A throttle passage provided at the lower end of the vertical heat exchange tower body and communicating with the heat exchange tower, and a cylindrical body and a truncated body provided directly below the throttle passage and communicating with the throttle passage. and a cylindrical calciner consisting of an inverted conical body, and the cylindrical calciner includes a combustion burner and a raw material discharge port provided at the bottom to send the calcined raw material to the kiln inlet chamber. has
Moreover, a spouted layer forming duct is provided, the end of which is located at the bottom of the cylindrical calciner, and whose opening is directed upward to form an upward airflow within the calciner; A calcination device for powder raw materials, comprising a swirling airflow forming duct having an opening oriented tangentially into the cylindrical body so as to form a swirling airflow inside the cylindrical body of the cylindrical calcination furnace.