US1708693A - Rotary kiln - Google Patents

Description

April 9, 1929- J. 5. FASTING ROTARY KILN Filed Jan. 6; 1926 2 Sheets-Sheet 1 IN l/EN 70R W M QM J. S. FASTING ROTARY KILN April 9, 1929.

Filed Jan.6, 1926 2 Sheets-Sheet 2 INVENTOR J V ,M%@

I Patented Apr. 9, 192 9.

UNITED STATES .PATENT OFFICE.

J'OHAN SIGISMUND FA STING. OF VALBY, NEAR COPENHAGEN, DENMARK, ASSIGNOR.

. TO F. L. SMIDTH 00.,- OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

ROTARY KILN.

Application filed January 6', 1926, Serial No. 79,509, and in Great Britain January 7, 1925.-

In rotary kilns, such as are used in the manufacture of cement, there are frequently insorted in the kilns near the feed end, metal members, such as cross plates or lifters or chains, for the purpose of promoting the travel of the material through the kiln or of increasing the surface contact of the material with the hot combustion gases to promote the drying or the heating of the material. The

10 temperature of the combustion gases is usually so intense, however, that such metal members are subject to rapid deterioration. In accordance with the present invention it has been found that this disadvantage .can be 1 overcome and a reasonable life assured for such metal members by reducing the temperature of the combustion gases in the kilns, in the zones where such metal members are located, by the introduction into the kilns,

below such zones, of a relatively cool gaseous bod such as air or even relatively cooler stac gases. Preferably atmospheric air, which is not charged with moisture taken up from wet raw material, as might be the case with stack gases, is employed and means are also preferably provided whereby such atmospheric air shall be heated somewhat before it is introduced into the kiln iii-order to avoid the great reduction of temperature within the kiln. Means are also preferably provided whereby may be regulated the volume of the relatively cool air to be admitted.

It will be understood that the particular form of means employed in the practice of the invention may be varied greatly according to the convenience of the manufacturer of the kiln or of the cement manufacturer and the conditions of use. In the-accompanying drawings, in which are illustrated two embodiments of the invention:

Figure 1 is a view partly in section and partly in elevation of a. kiln adapted for introduction of unheated atmospheric air below the heating and drying zone. v

Figure 2 is a detail view in section on the broken line 2-2 of Figure 1.. I

Figure 3 is a view partly in section and or heating the air before admission to the kiln. I

Figure 4 is a detail view in longitudinal sectional elevation and on a larger scale of the means indicated in Figure 1 for regulating the admission of air.

Figures 1, 2 and 4, through which, in the con- 7 cool by the passage through it of the tively cool air and at the same time is heated partly in elevation of a kiln with provisions Figure 5 is a detail view partly in section.

and partly in elevation and on a larger scale of the means indicated in Figure 3 for regulating the admission of air.

Except as hereinafter explained, the rotary kiln a may be of any usual or suitable construction, provided at its lower or discharge end, as at b, with means for the supplying of fuel for combustion in the kiln, and at its upper or feed end with means indicated at c for the feeding of the material to be treated, the upper end of the kiln entering, as-usual, a dust chamber d. As shown in Figure 1, the kiln may be provided near its upper or feed end, in the heating and drying zone, with cross plates 6 of metal, which form longitudinal channels within the kiln in which the material is distributed, in order that it may be more effectively dried and heated through contact with the combustion gases which pass through the kiln and the dust chamber and thence into the usual stack, not shown. Such metal members as the cross plates e or other metal members, when subjected to the intense heatof the untemper'ed combustion gases, de-

teriorate somewhat rapidly and must be reso newed from time to time, involving the stopping of the operation of the kiln. To obviate this difiiculty openings are provided through the kiln wall, as indicated generally at f in struction represented in these figures, atmospheric air is admitted at a point below the heating and drying zone of the kiln, in which are located the metal members 6. In order to prevent the escape of cement material fromthe kiln through such openings and in order also that the relativelv cool air may be admitted to the kihi near its axis ratherthan close to the wall, the air is admitted through a tubular conduit g, disposed diametrically through the wall of the kiln, with its open ends outside the wall and provided with an opening 9- near the axis of the kiln and directed toward the upper or feed end of the kiln. This conduit is itself kept relatively 10o relaby the combustion gases to some extent sothat the air admitted is itself somewhat heat ed and too great reduction of temperature in the kiln is prevented. I

.It is desirable that the volume of relatively cool air admitted shall be capable of regulation according to the conditions of operation of the kiln and there is therefore provided for the opening g a valve h which may be carried by a rod k pivoted at oneen'd, as at If, in the conduit 9 and provided at the other end, as at h with a latch for engagement with a rack 72, so that the valve k can be held in such position with respect to the opening g as toiadmit so much air as may be found desirable. I

The construction shown in Figures 3 and *5 is generally similar to that shown in Figures 1, 2 aud t, but difiers in details now to be described. In this embodiment of the invention provision is made for the heating of the air before its introduction into the kiln at a point below the drying and heating zone. Al-.

though the air is heated, it will be understood that its temperature is low as compared with the temperature within the kiln at the point where the air is admitted and that the effect is to reduce the temperature in the heating and drying zone to a point below that by which the metal members in that zone would be caused to deteriorate rapidly. As show in Figure 3', a staionary shell 11 is placd around the portion of the kiln within which is the burning zone, such shell being open atits lower end and connected -by a suitable conduit a" with a stationary shell 71 which surrounds the kiln at the point where the openings f are provided, so that heated air iscontinuously supplied to the chamber 11 such heated air, however, being relatively cool .as compared with the normal temperature of the combustion', gases within the kiln at that point. A diametrically disposed tubular conduit g,

' having open ends and with a central opening g directed toward the upper end of the kiln and also with a valve h to control the admis-..

sion of the relatively cooler air, is provided substantially as already described with respect to Figure 3, but with special provision for controlling the position of the valve, necessitated by the provision of the fixed shell '5 In this construction, shown in detail in Figure 5, the pivoted rod h which carries the valve h, is provided at its lower end with a roller k which is received in a U section ring is. The latter is supported within the shell i so as to be capable of adjustment in an axial direction, but is preferably not rotatable within the shell. A block 70 in which the ring is is seated is engaged by a screw 70 which is carried by a stationary nut k and has outside the shell 71 an operating head. or handle 70. Movement of the ring Join an axial direction,

by manipulation of the screw 70 causes movement of the valve h toward. or from the opening 9 to regulate the admission of the relatively cooling air.

changes can be made in the form and character of the devices for admitting and regulating the flow of the relatively cooling'air, as well as of the provisions for heating the air somewhat before it is admitted to the kiln.

' I claimas my invention:

1. The combination of a rotary kiln having metallic members near its feed end and extending inwardly away from the lining and provided with an opening adjacent the metal- 'lic members for the introduction of air at a point adjacent the metallic members in the direction of the discharge end, a stationary shell surrounding the discharge end of the kiln to form an air heating chamber,.a second stationary shell'surrounding the kiln intermediate the feed and discharge end and forming a chamber for communication with the opening in the kiln, a conduit connecting said chambers, means to introduce air into the kiln from the second chamber, means to direct the air so introduced toward the feed end of the kiln and upon the metallic members, and means to control the flow of the air.

2. The combination of a rotary kiln having metallic members near its feed end and ex tending inwardly away from the lining and provided with an opening adjacent the metallic members for the introduction of air at a point adjacent vthe metallic members in the direction of the dischargeend, a stationary shell surrounding the discharge end of the kiln to form an air heating chamber, a secthe opening in the kiln, a conduit connectin said chambers, a tubular conduit mounte within the kiln and communicating with the opening therein, an opening in the conduit within the kilndirected toward the feed end thereof to direct the air toward the feed end and upon the metallic members, a valve for the opening in said conduit, a pivoted rod carrying the valve and having an end outside the kiln, a section ring within the second chamber and engaged by the end of said rod, and means to move the ring in an axial direction.

This specification signed this 15th day of December, A. D. 1925. Y

JOHAN SIGISMUND FASTING.

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