DE2258587A1 - ROTARY FURNACE WITH HEAT EXCHANGERS - Google Patents

Description

Dr. Ing. A. vtm der Wssrlii £ 9th NOV. 1972

jg1 Hamburg © Ο
VVilstorier SireB »33

IMuSmidth & Go. A / S,

Vigerslev Alle 77, DK-25OQ Copenhagen-Valby / Denmark

Rotary kiln with heat exchangers

Priority: December 2, 1971, UK No. 56051/71

The invention makes use of a system with a rotary kiln and a number of rows of units connected in series which exchange heat between a powdery material and the flue gases from the rotary kiln. "Effect. When using such a system," for example For making cement, the powdery material can be used Cement rawhi, which is effected by the units Heat exchange causes the flour to be preheated, “Each unit consists of a riser pipe through which flue gas flows and into which the powdery material flows is introduced, the heat exchange between the gas and powdery material takes place, and from a cyclone, z, B, a twin cyclone, in which the powdery material is separated from the flue gases.

In a plant like the one in the time industry "is used, the high-pressure gases from the rotary kiln are used pulled through the individual riser pipes and cyclones one after the other by means of a blower, a number of which are one above the other Stages are arranged. As far as the foremost cyclone stage comes into consideration - that is the cyclone stage, which is passed through first by the flue gases from the rotary kiln *, the cyclone outlet pipe for cement raw material is connected directly to the rotary kiln, while the Roluaehl-

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discharge lines of the individual cyclones of the other cyclone stages open into the riser pipe, which leads to the previous jn Cyclone leads in the direction of the streams of flue gases. Each Riser pipe is provided with means for its feeding with the cement raw meal, which on its way through the various Cyclones and their risers one after the other come into contact with ever hotter flue gas and thereby open heated to a high temperature. Every single cyclone stage thus represents a separate stage for heating the raw meal.

Effective heating is used in such known systems of the raw meal - sometimes followed by a partial oalination (Expelling COp) - carried out with the result that the heat content of the fuel fed to the rotary kiln is exploited in an economically advantageous manner will.

The early systems of this type consisted of only one single row. However, the tendency in the cement industry and also other industries goes to the use steadily larger units, including rotary kilns, whatever means that the capacity of the corresponding raw meal preheater must increase in the same way. It had therefore been known for some time to use this requirement for to satisfy increased capacity by providing the furnace with two parallel rows

According to the invention, such a system now has four Rows of units, arranged symmetrically both with respect to a vertical plane through the furnace axis, such as also with respect to another vertical plane, perpendicular to the first one, in front of the flue gas outlet of the rotary kiln. The result obtained in this way is a very compact space-saving system, a very suitable pipe arrangement and tin low material consumption for the construction of the required heights Support frames.

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The system according to the invention ensures that the paths for the powdery material and for the flue gases are the same in each row, with both media being distributed in the same way over the rows. In addition, the presence of four rows grants a high degree of reliability for the entire rotary kiln plant, because in the event of a failure or overhaul of one or more rows it is still possible to operate at reduced capacity by working with a reduced number of rows without stopping of the rotary kiln.

As already mentioned, the invention provides a heat exchange system for preheating cement raw meal. Each row can have one, two or three, but preferably four units

include. '...-.-..-

Preferably, the four risers that lead to unite belong to the lowest units, in a common town, into which the rotary kiln opens. To do this the four risers can combine in pairs at the bottom into two common risers and the two like this Common riser pipes created can then unite at the bottom to form the common shaft. ..;

A system according to the invention is still, for example, on the drawings which represent:

Pig. 1 is a perspective view,

Fig. 2 is a side elevation,

Pig. 3 shows a horizontal section along line III-III from Pig.

and
Pig. 4 shows a horizontal section along line IV-IV of Pig. 2.

For greater clarity, the supporting racks are on the Drawings left out

The system shown has four rows and four cyclone stages, that is, each row comprises four units. The cyclone stages are counted in the direction of the transport of the solid material so that the first cyclone stage is the top one. In the drawings ifit da «relationship of the individual components of the apparatus

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ture to the individual treatment stages by adding a Letter index given for reference number. Hence the four Treatment stages through the letters A to D, tone above beginning, designated. It should be noted that not all of the ingredients are specified below in this way and are labeled, can be seen on the drawings.

The first cyclone stage comprises four twin cyclones "IA, 2A, 3A and 4A with respective risers 5A, 6A, 7A and 8A. These risers lead from the top of each of the four Cyclones 9B, 10B, 11B and 12B in the second cyclone stage, which comprises corresponding riser pipes 13B, 14B, 15B and 16B, which lead from the tips of the four individual cyclones 17C, 180, 19C and 2OG into the third cyclone stage. To this Cyclones include the risers 21C, 22G, 23C and 24C, which from the top of the two twin cyclones 25D and 26D into the fourth cyclone stage, while corresponding risers 27D and 28D, each composed of two risers, each lead to its own twin cyclone and to itself unite a common shaft 29 into which a rotary kiln 30 opens.

As can be seen, the mentioned system consists of four rows, which are symmetrical both with respect to a vertical axis through the furnace axis, as well as with respect to another irertical plane at right angles to the former in front of the iauchgasauslaß of the rotary kiln are arranged.

During normal operation of the system, the higher gases are off learn rotary kiln 30 by means of a fan, not shown, deducted and laughed at one another through the individual cyclone stages are evenly distributed over the individual rows. Consequently a quarter of the flue gas along the way out of the rotary kiln 30 through shaft 29 and further through the riser pipe! 7D, one of the twin cyclones 25D, riser pipe 21C, cyclone 17C, riser 13B, Zjklon 9B, riser 5A and both twin cyclones 1A, from the top of which the flue gas is drawn by means of suction through the middle outlets shown and one not shown Pipe system is removed. Everything happens in an analogous way

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of the remaining three quarters of the raw gas a separate one Way through the raw meal preheater. All of these paths are of equal and uniform length and cross-sectional area along which, four ways changes evenly the gas flow, as desired, exactly evenly on the four Paths distributed.

The raw meal is fed to the individual rows through feed pipes 31, 32, 33 and 34, from which it passes through shut-off valves 35, 37 and 38 which are designed to prevent the smoke gases from entering the feed pipes while it is pouring the raw meal allow B to be fed into risers 5A, 6a, 7A and 8A. On its further path, the raw meal, suspended in the flue gases, flows through the above-mentioned riser pipes, the raw meal being heated and the gases being cooled. The flue gases and the raw meal suspended therein go from the riser pipes into twin cyclones 1 A, 2A, 3A and 4A of the first cyclone stage, in which centrifugal force and gravity work together in a known manner to separate flue gases and raw meal from one another, after which the raw meal passes over the cyclones the raw meal outlets 39 »40, 41 and 42 leave via their built-in shut-off valves 43, 44, 45 and 46 which are intended to prevent the flue gases from moving backwards into the cyclones 1A, 2A, 3A and 4A, but which are intended to allow the raw meal to enter the riser pipes 13B, HB, 15B and 16B, in which new heat exchange takes place. 47 _r 48, 49 and 50 and via shut-off valves 51, 52, 53 and 54, the raw meal is now heated further »into the riser pipes 2tC, 220, 23C and 240 for further heat exchange with hotter gases * In 4 cyclones 170, 180, 190 and 200 of the third cyclone stage, gases and raw meal are again separated and the raw meal goes through raw meal outlets 55 »56» 57 and 58 and via shut-off valves 59, 60, 61 and 62 into shaft 29, from which the raw meal is suspended in flue gases and in the Heat exchange with these, through the risers 27D and 28D in the twin cyclones 25B and 26D of the fourth cyclone stage. You can do it from here

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raw meal, which has now been separated, is heated further through raw meal outlets 63, 64, 65 and 66, which combine in pairs to form lines 67 and 68 in the shaft 29.

The inlets for introducing raw meal into the risers are with distribution devices (not shown in the drawings) which serve to promote uniform mixing of raw meal in the flue gas stream.

In this way, the cement raw meal gets on its way through the individual cyclones, and in particular through obren associated riser pipes in close contact with flue gas of steadily higher temperature, and this will eventually open brought a high final temperature. The uniformly distributed pipe connections 55, 56, 57 and 58 to the shaft 29 ensure a favorable uniform distribution of the preheated raw meal which is fed into the twin cyclones 25D and 26D is introduced. The pipes 67 and 68 open in the same way symmetrically into the shaft 29, in which they continue as invisible channels, and are used to feed the

> xphr
Ronmehls in the Drenofen 30.

In a similar way to the flue gases, the raw meal can flow along four equal paths and provided that the Amount of raw meal to be fed into the rotary kiln 30, evenly per unit of time between the four Feed pipes 31, 32, 33 and 34 is distributed, the amount and the temperature of the raw meal, which the rotary kiln from each row supplied will be the same.

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Claims (1)

f a t withdrawal claims e 1 · System for preheating powdery material with flue gases pipe
of a rotary kiln, characterized in that it has four rows of units which are symmetrical both in relation to a vertical plane through the rotary kiln axis and in relation to another vertical plane, perpendicular to the first, in the front of the furnace flue gas outlet are arranged. 2β Plant according to claim 1 ~ for cement raw meal, characterized marked that each row has four units includes. 3. Plant according to claim 2, characterized that the four riser pipes belonging to the lowest units unite below this in a common shaft, into which the rotary kiln opens. 4. Plant according to claim 3, characterized in that g e k e η η ζ e i c h η e t that the four risers of the lowest units unite in pairs in two common risers and so formed two common riser pipes then unite in a common shaft. 3 0 9823/08 13