US2353753A - Coking high volatile coal - Google Patents

Description

Patented July 18, 1944 Carl Otto, Manhasset, N.

Y.,-assignor to Fuel Refining Corporation New York, N. Y., a corporation of Delaware No Drawing. Application December 2, 1941. Serial No. 421,368

Claims. (01. 202-33) The general object of th present invention is to provide a simple and effective method of producing a relatively strong and dense coke from coal having a volatile content of from forty to sixty percent, which is too high' to permit its 5 conversion into such coke by the customary methods used in the production of metallurgical coke. At the present time, practically all of the metallurgical coke used in the world is made in byproduct coke ovens of the horizontal regenerative type, and is made from a coal, or a coal mixture, having a volatile content which is seldom higher than thirty-five percent and usually is about twenty-five to thirty percent, and which is heated l6 to a final temperature of the order of 1800 F. or

higher. The volatile content percentages stated herein, are based on coal free from its actual moisture and ash contents.

'My present invention was especially devised for, and is well adapted foruse in coking so.- called Illinois coals, having a volatile content in the neighborhood of forty-five percent, of which great quantities are available in this country for mining at a relatively low cost. When such a when coked will contain seven pounds of ash will also contain twenty-eight pounds of carbon and.

coal is treated in a byproduct coke oven of standard type, in accordance with the standard procedure followed in the production of metallurgical coke, the solid residue remaining after forty-five percent or so of the weight of the charge has passed away from the ovens in gas or vapor form, is in the form of coke, which is too porous and friable for practical use.

I have discovered, however, that a relatively strong and dense coke can be made from Illinois and analogous high volatile coals by a process comprising the following steps. The formation of a moist carbonaceous mass having a water content of from ten to fourteen percent and which in most cases is preferably about twelve percent of the weight of the coal including its ash content, and a carbonaceous content consisting wholly of light'volatile coal in a finely subdivided state or, and preferably in many cases,

of such finely divided high volatile coal 'in ad- (5 mixture with from two to five percent by volume coke in a subdivided state; the stamping or compression of the moist mass into compressed bodies adapted for insertion in coking chambers, and

of such density that the weight of the non-volatile portion including the ash, of each body is approximately as great as that of a similar volume of metallurgical coke; the insertion of the compressed bodies in coking chambers and the heating of the coking chambers to temperatures similar to or slightly higher than the oven temperatures used in the standard production of -metallurgical coke. In order that the charge some cases the oven width may'well be about thirteen inches.

In producing metallurgical coke from a good coking coal, in an oven charged through openings in its top wall, the dry coal density of the coal charge in the oven will normally be about .75 and with a normal average volatile content, the coke produced will weigh about thirty-five pounds per cubic foot of charge, and in proceeding in accordance with the present invention, I consider it ordinarily desirable to so compress the coking charges, that the coke produced will weigh from thirty-three to thirty-eight pounds per cubic foot of charge. In general, the weight of a charge produced in accordance with the present invention will be greater when the ash content of the coal is relatively high than when it is relatively low. For example, a charge of such composition that a portion thereof which of 1, so that the compressed charge will weigh sixty-two and four-tenths pounds per cubic foot,

. and the coke formed with then weigh thirty-five pounds per cubic foot. Such coke maybe expected to have a density and mechanical strength approximately the same as that of good metallurgical coke. It is practically feasible, when conditions make it desirable, to compress the coal to a density appreciably higher than unity, for example to a density of 1.05.

In the preferred practical mode of carrying out the invention, I first break the coal into such relatively coarse particles that, after being cleaned by any usual or suitable washing process, the coal mass will hold the ten to fourteen percent moisture content needed in the compressed charge forming cake or body. After washing or otherwise wetting the coarsely subdivided coal, I subject it to a breaker or grinding action to subdivide the coal so finely that about eighty'perinch and adapted to pass particles about two' millimeters in diameter. I next compress the tomary in forming comp moist coal into a cake or body suitable for chargprior to the formation of the enough so thirty mesh screen, i. e.

and advantageously, in some cases, the coke forty mesh screen, i. e. a screen hundred openings per square inch. cake or body or coal so-called high temperature carbonization of coal metallurgical coke. In such high carbonization, the final coke temperature is of the order of 1800 F. whereas in the so-called low temperature carbonization of coal, the final coke, or char," temperature is of the order of 1000 F. Ordinarily each compressed cakeis made of proper size to form the entire charge of a coking chamber. However, in some cases, it may\be desirable to compress the coal into briquette-like bodies and to form each oven charge of a stack of said bodies.

The compression of the charge may be effected by the use of charge stamping, or compressing, apparatus of various known forms of apparatus devised for use in forming compressed coal cakes to be charged into coking chambers, provided such apparatus has, or is given suiilcient strength and power to efiect the compression required for thcimrposes of the present invention, which is appreciably higher than heretofore custo produce temperature the purposes of coal density of the compressed charge will normally be appreciably above be 1 or greaiigwhereas heretofore, the dry coal density of s ped coal charges has or y been below .95, and usually about .9. I

Heretofore it has been assumed that a stamped or. compressed oven coal charge should not have a height greater than the use of wider ovens with stamped coal charges than would otherwise be desirable. The greater density of a coal charge cake formed in accordance with the present invention, results in increased strength of the cake and permits the height to width ratio to be substantially greater than '7 to 1. In some cases the compressed charge bodies may be str ened and their coking properties improved, by adding pitch to the coal either by mixing it in finely ground form with the coal, or by spraying liquid pitch onto the coal and then subjecting the coal to a mixin action prior to the cake forming operation.

A coal charge forme compressed .and coked in accordance with the present invention, does not swell, and ordinari y does not deform during the coking operation so that the taper in the oven chamber wid which is characteristic of the standard type ovens, is not needed, but on the contraryris un esirable in the'practice of my invention. U

.The coking portion of my improved process may well be carried out in regenerative coke ovens differing from those of standard type only in the omission of oven taper,

nine hundred openings per square ressed coal charges. For the present invention, the dry' or, and prefer- In my copending trial and the large facture of metallurgical, and'also jected to the full customary in standard byproduct metallurgical 'coke oven plants. A practical economical ad- In such a low cost plant, the distillation gasesy be used, pa y i ing the coke oven hattery and partly in firing steam generating boilers included in the plant for power purposes, and waste heat boilers may also be heated, or other industrial heating purposes served, by the waste heating gases passing away from the coke oven battery.

The fact that the compressed coal charges do not swell or deform during the coking operation, permits the walls between the heating fines and the coking chambers to be reduced I without making the heating walls undesirably weak, and thereby permits the rate of heat transfer to the charge and the final coking temperature to be higher than is customary in the production ofv metallurgical coke with the same flue temperatures customarily employed n th n making up for some of the loss in thermal efliciency theoreticslly resulting from the non-use of regenerators. application for patent, Serial No. 330,049, iiled April 1'1, 1940, I have disclosed and claimed a relatively simple and inexpensive waste heat coke oven especially devised and adapted for use inthe practice of my improved process, but further references therein are unnecessary in view of the fact that the present other types and forms.

' By proceeding in accordance with the present invention, it is pomble to produce from high volatile coal a coke strong enough to withstand handling and transportation, with little if any 'greater formation of breeze, than is produced a similar handling and transportation of ordinary metallurgical coke.

rocess forms an excellent fuel, and because of its density and strength burns on a grate or in a fuel bed about as does ordinary metallurgical coke, and is a satisfactory substitute for the latter for domestic purposes and for many indus- The addition to the high volatile coal of from two to five percent of suitably sube e iii,

byproduct recovery treatment distillation gases evolved, to

inthickness' the manufacture of metallur ical The coke producedby divided coke adds to the mechanical strength of and improves the coke produced.

This application is acontinuation in part of my prior patent application Serial No. 330,048, filed April 17, 1940.

While in accordance with the provisions of the statutes, I have illustrated and described the best forms of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims invention may be used to advantage without a corresponding use of other features. l

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. The method density and strength to metallurgical coke; from 2. A method as specified in claim 1, in which the high volatile coal is mixed with from two to five percent of coke subdivided so finely that and that in some cases substantially all or it will pass a thirty mesh per inch screen.

3. A method heat is high at 1800 F.

4. The method'of producing a. relatively strong and dense coke from coal '5. The method of producing a relatively strong and dense coke from coal having a volatile content of forty or more percent, which consists in about eighty per cent content weight or from thirtythree to thirty-eight pounds then coking said body in a retort in which said