US1581522A - Device for burning cement, magnesite, lime, etc. - Google Patents

Description

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H. STEHMANN DEVICE FOR BURNING CEMENT. MAGNESITE, LIME, E'I'G Filed August 30, 1921 2 Sheets-Sheet. 2

i Ptented Apr. 20,192&

UNITED STATES MY WN, OI BIBLIN-EOBENSCHONHAUBEN. GEBHANY.

` DIVICE ?OB BUMIG CBHENT, KAGNEBI'I'E, LIKE, BTC.

Application ed Au ust :9,1921. sera no. 07,035.

(smun m l! TE! PIOVIBIOII 01' nm AUT O! KARO!! 3, 1921, 41 SIME. L., 1313.)

To all whom it may coment:

Be it known that I, HARRY STEIIMANN, a subject of the German State, and resident of Berlin-Hohenschonhausen, in the State of 6 Prussia, Germany, have inveted certain and useful Improvements in a Device for Burning Cement, Magnesite, Lime, Etc. (for which I have filed an application for patent in Germany, January 14, 1920, #St 10 32805) and I do lereby declare the following to be a full, clear, and exact descrpton of the invention, such as will enable others skilled in the art to which it'pertains to make and use the same. i

A disadvantage of rotary kilns at present used for burning cement, magnesite, lme, etc. is that the waste heat is not utilized fully, and particularly the usual coolng drums used to transfer the heat of the clinker to the air of combustion have an insuflicient effect. The apparent saving of heat of the materal, the burning of which has been finished, causes in fact an increased expense for fuel used for further heating the slightly warmed cooling air up to the temperature of the combustion or clinkering zone.

The object of this invention is a device for burning cement, magnesite, lime, etc., consisting of a rotary kiln and coolng chamber which has the form of a shaft kiln of such height and size that the air is heated to the ignition temperature of the fuel by the material discharged from the rotary kiln. The shaft kiln must be large enough to expose the burnt material for a lon time (12 to 24 hours) to the cooling ar traversin the chamber in an opposite direction. By this means a relatively small quantity of air for the cooling is used, which, highly heated, s led to the clinkering zone, and there the fuel introduced is entirely burned.

Preferably the shaft kiln is built as an automatic kiln continuously discharging mechanically and closed entirely, whereby the heat is entirely used.

In the clinkering zone, or just before reaching it, the hot air current from the cooling chamber meets'the fuel blown into the head of the rotary kiln, and produces a better combustion of the fuel in the clinkering zone than s possible by the arrangements now being used with the air current almost cold at the beginning of ignition.

possible to charge the' calcining zone with a i bodying my invention.

The great amount of waste heat in a rotary kiln may be explained b the rapid movement of the ases into t e calcinng zone and the bad mixing of the 'burning material and the hot gases.

This loss of heat I avoid by giving to the calcining zone a section consderably lar er than the clinkering zone. Instead of tis larger section of the calcining zone or drum, several such drums connected to .one clinkering drum may be used.

To atlain a better mixing of the material with the heating gases, the enlarged ealciing zoneor drum is divided into several longitudinal chambers.

By the above-described arrangements it is 7" greater amount of material to be burned, move it more slowly forward, and likewise, by a slower movement of the gases make better use of their heat in the rotary kiln over practically the whole cross-section. By these means thelength of the rotary kilns and the buildings containing them is very much curtailed, and the radiating surface of the rotary kiln is lessened.

The so Shortened rotary kiln is furnished with a nantle and the air heated by the radiation in the interspace between mantle and rotary kiln is exhausted and sent. through the cooling chamber, so that the radiated heat can a so be used with profit.

Generally the material in the lower, narrow part of the rotary kiln is so highly heated that it is already sintered, or the sintering is completed in the upper parts of the shaft kiln without the addition of more fuel. To complete the sintering in case, under the most adverse conditions, the sintering in the rotary kiln might not be finished, be it accidentally or intentionally, t is possible to supply additional fuel to the shaft kiln through a special opening in the head over the shaft kiln.

Referring to the drawings- Figura 1 is a Vertical section of a kiln em- 100 Fig. 2 is a like view of a modification, and Fig. 3 is a cross-section of the calcining chamber.

Figure 1 represents the rotary kiln as having anenlarged calcinin zone a and the smaller continuation b or the clinkering over-burning by the highly zone. For example, the letter has the diameter of a common rotary kiln, while the calcining zone a is of greater diameter.

The material to be sintered passes from the clinke'rig 'zone b, into the cooling shaft or shaft kiln a frnished with an automatic dischar device d and closed entirely. The rotary fillu has a mantle e whose ends are pa'tly or wholly open. Out of this mantle' the blast device f draws the air heated by the radiating rotary kiln, and forces it into the cooling slmft c at about the middle, and into the material to be cooled. The blast f' forces cold air under the ate or discharge device d into the coolng shaft. Both streams of air ure heated strongly by the material to be cooled and then pass into the .clinkering zone of the rotary kln at g. The

third blast dcvice f* draws the hot air out of the nantle e and forces it, mixed with fuel into the head of the rotary kiln. Here and in the lower part of the clinkering zon'e b the cooling ar strongly heated, meets the stream of fuel blown in at g'.

It is possible in using the ordinary rotary kiln that the material which is discharged into the cooling drum is not well burned, and a clinkering of the material is impossible. By nv invention, in such a case, the clinkering o the material afterwards is ptossible in the upper part of the cooling sha c by the highly heuted air, and' it may be necessary with some materials to discharge them, not yet clinkered into the coolinshaft, to avoid eated air.

If the heat is not suflicient thene can be introduced through the opening h granulated fuel to complete the lin 'ering. If the clinkering is eiiected chiefly in the upper parts of the cooling shaft, the clinkering chamber I can be Shortened, as in Fig. 2,vand the clinkering completed'altogether by the fuel introduced through the opening h.

By thismeans, for the firsttime, it is possible to burn in the shaft kiln with a coal rich in gases without loss of the distilling gases of the fuel, which was heretofore impossible in automatic shaft kilns.

Figure 3 illustrates in section the separating walls i, z', separating the calcining zone into fourchambers..

I claim- 1. In the artof burning cement, magnesite, lime etc., in a rotary kiln connected substantially air tight at its discharge end to a LOOLOQB cooling chnber into which the hot mdctof the kiln is discharged; the math which comprises forcing air for supportin combuston through the chamber and e hot product theren; maintaining the relative quantities of ir useing through the chamber and of said ot product in said chamber, adequate to heat the air to the i ition temperature of the fuel used for heating the kiln as the air leaves said chamber.

2. In the art of burning cement, magneste, lime etc., in a rotary kiln connected substantially air tight to a cooling chamber into which -the hot product of the kiln is disclargedr -the method which comprises forcing air 'for supporting oombustion and heated by said kiln through the chamber and the hot product therein, maintaining therelative uantities of air passing throu h said cham r and 'of hot product in sai chamber adequate to hoat the air'to the ignition temperature of the fuel used for eating kiln as the air leaves said chamber.

, 3. In the art of burnin cement, magnesite, lime etc., in a rotary iln connected .substantially air tight to a cooling chamber into which the hot product of the kiln is discharged; the method which comprises supplying combustion air heated`b the heat passing through the kiln wal to said chamber at a point intermediate its height and supplying a further quantity of cold air to saihd chanlber at its lottom and maintainingt e tota quantit o air passin throu h said chamber relatiely to the i antit %f hot product in said chamber suflicent to eat the air to the ignition temperature of the fuel as the air leaves said chamber.

4. In a device for burning cement, magnesite, lime and the like, a rotary kiln, a mantle therefor, a shaft kiln into which the ronected substantially air-tight, means to blow -tary kiln discharges and to which it is oonfuel across the top of the sh'aft kiln into the rotary kiln, means tosupply hotair from said mantle to said blowing means, means to supply hot airfrom said mantle to about the middle of the shaft kiln, a device to continuously disch'arge said shaft kiln a device to close the bottom of said shaft kln air-tight, and means to supply cold air between both devices.

In testimony tha-t I claim the foregoing as my invention, I have signed my name.

HARRY STEHM ANN.

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