US118579A - Improvement in the manufacture of coal-gases - Google Patents

Description

UNITED STATES JOHN A. BASSETT, OF SALEM, MASSACHUSETTS, ASSIGNOR OF ONE-HALF HIS PATENT OFFICE.

RIGHT TO HENRI L. STUART, OF NEW YORK CITY.

IMPROVEMENT IN THE MANUFACTURE OF COAL-GASES.

Specification forming part of Letters Patent No. 118,579, dated August 29, 1871.

To all whom it may concern:

Be it known that I, JOHN A. BASSETT, of Salem, in the county of Essex and State of Massachusetts, have invented certain Improvements in the Manufacture of Illuminating-Gas, ofwhich the following is a specification:

The nature of my invention consists in carbonizin g coal for making illuminating-gas by a continuous process, in which the coal, after being finely pulverized, is continuously and automatically introduced into a heated chamber and the products of the destructive distillation continuously withdrawn. The first part of my invention relates to the devices by which this result is aecomplished. The second part of my invention relates to the means used for purifying the gas made in the manner set forth.

In carrying my process into effect I make use of the apparatus substantially in the form shown in the drawing annexed to this specification, in which Figure 1 represents a vertical section of the generating apparatus. Fig. 2 represents a vertical section of the purifier. Fig. 3 represents a plan of the same. Fig. 4 represents a section of the seal used in the purifier to connect the parts.

Similar letters of reference indicate like parts in all the figures.

A represents the retort, which I prefer to make of clay, cylindrical in section, and in lengths of two feet or more, as shown in the drawing. It may be made of any suitable length-not less, however, than is necessary to make the coal incandescent in its passage from the top to the bottom. The retort should be made in such a manner and of such materials as will best enable it to withstand the highest temperatures and allow of a proper degree of expansion without injuring the joints between each section. I prefer, in making it of clay, to use a large proportion of burned refractory material, ground carefully and mixed with a small proportion of new clay. The sections may thenbeplaced in position and burned in the furnace in which it is to remain permanently. In the drawing the body of the retort within the furnace is shown as made of clay, in sections, and the top and bottom, outside the heating-surface, are made of cast-iron. The section of the retort A above the furnace is united to the body of the retort in any suitable manner and holds and supports the apparatus for lcharging the coal.

To the top of the retort A is iitted a cast-iron ring, B, which covers the retort and extends down over the side, fitting over the retort A with a ground joint. It revolves upon rollers which run upon a serrated surface, so that a jarring motion is given to the ring and the coal-po\\"der, which is delivered through a coneshaped grating forming a part of the ring, and distributes the coal uniformly around the periphery of the ring, in close contact with the interior of the retort. Above this ring is placed the hopper C, which contains the coal-powder, the supply of which is controlled bythe valve D, operated from the top of the hopper by the lever, as shown in the drawing. The lower part of the retort, outside the furnace, is also made of cast-iron, and supports the main body of the retort in the furnace. The outlet-pipe E communicates with the exhauster and purifiers. F represents the elevator for conveying the crushed coal to the hopper C. rIhe ring B is revolved by the belt B', which receives motion from the pulley which actuates the elevator F. The coke falls down through the ret-ort into the water-seal G upon the endless belt H, from which it is conveyed by the elevator I to the furnace J. K represents a steam-boiler, which may be heated by the waste heat of the furnace. From this boiler steam is ta-ken through the superheater L and injected into the retort at M. This drawing indicates an apparatus in which the retortor generating-chamber is from thirty to fort-y feet in length and from fifteen to eighteen inches in diameter. The other parts of the appara-tus are made of a size to correspond with these dimensions. In this apparatus the conditions which are recognized by those skilled in the art as essential to the perfect elimination of all the gas from the coal, for preserving its illuminating power unimpaired, and producing the minimum of liquid products, are fully maintained. It is necessary for the success of this method ot making gas that the coal should be reduced to an impalpable powder, and there are various means by which this result may be attained, which are well known and do not require a description in this connection. Other methods may be used for introducing the coal at the top of the retort. It may, if desirable, be introduced directly from the crushing apparatus, which may be placed above the level of the top of the retort for this purpose. But the plan indicated will be saved. The furnace is arranged so as to make to form a chamber at this point in which is an Which is best adapted for producing liquid hyfound to work satisfactorily in practice, asA the quantity of coal admitted can be more perfectly regulated and controlled. It may also be desirable to remove the coke by other means than* that shown in the drawing; but with the apparatus devised, in connection with the peculiar form of furnace shown, the fine coke is more perfectly taken care of and charged into the firespace, and much expense for labor in stoking is a large combustion-chamber, and the coke, as it burns, moves slowly down an inclined plane perforated with suitable openings arranged to admit air freely to the burning fuel. This furnace may be on one or more sides of the retort-chamber, and it may be desirable, in the use `of a very long retort, to have two or more furnaces placed one above the other, for the purpose of heating the retort more perfectly. Itis necessary that the outlet-pipe for the gas should correspond very nearly to the shape shown in the drawing. It should have an inclination relatively to the base of the retort, in order that if the fine coke is drawn into the outlet with the current of gas it will fall back into the seal, and not pass into the condenser and purifier. It may be desirable apparatus which will shower the current of gas with water so as more perfectly to free it from particles o' coke. The setting of the retort in the furnace is arranged so that the lateral supports come at the level of the joints in the retort and assist in deflecting and distributing the heat uniformly over the whole exterior surface of the retort, and the outlet-fines are arranged with suitable dampers so as 4to allow the heat toV pass directly to the chimney or to be deiie-cted so as to heat the steam-boiler. The steam from the boiler is conducted through a suitable superheater, by which it may become highly heated, equal, at least, to a temperature necessary to decompose the coal-dust, and is used, either continuously or at intervals, whenever it may be difficult to conduct sufficient heat through the walls of the retort to the interior, or whenever a very rich coal is used a quantity of hydrogen resulting from the decomposition of the steam Ymay be mixed with the richer gases derived from the coal. It is also used to accelerate the motion of the coal-dust in its passage through the retort. In either case it is essential that the steam should be highly heated, and sufficient superheating surface should be provided to accomplish this result.

A brief synopsis of the rationale of the present process now in use for earbonizing coal for gas purposes is necessary at this point for a more complete elucidation of the novel features involved inthe present application. In roasting the coal in mass in a horizontal retort the coal is acted upon bythe heat gradually; and while the exterior layer is acted upon by a very intense heat, which decomposes the light-giving constituents into solid carbon, leaving only light carbureted hydrogen and carbonio-oxide gases, the intericr of the mass is slowly distilled at a low heat,

drocarbons, which are condensed and lost-that is, so far as their availibility or use in the gases is desired. A large amount of tar is produced,

alyzed, contains as much, and in many cases more, of light-giving properties of the coal as the gaseous products of distillation derived in this way. This objectionable feature of the present condition of gas manufacturing is entirely avoided.

By the method here proposed the coal is nel'y divided, and each atom is immediately subjected to the proper heat to convert it into a permanent gas. there is no hydraulic main or seal, and the gas is withdrawn as fast as made, it does not deteriorate in photometric value by being retained in a sluggish movement in contact7 under pressure, with a highly-heated surface until all or nearly all of the valuable hydrocarbon v'apors are decomposed and lost. equality of the heat during the carbonizingprocess the chemical changes in the destructive distillation of the coal give rise to a variety of deleterious compounds, which occasion great expense for purification; The number of these compounds and their complex character are reduced and modiiied by the instantaneous evolution of the coal into a permanent gas without the intermediate changes which take place at low or unequal heats. The opening of the retorts at. intervals of from four to six hours for withdrawing the retort is not exposed to the unequal expansion and contraction and the introduction of air resulting from this cause.

The conditions for the economical and successful manufacture of illuminating-gas from coal are secured by this method of operation, and theadvantages may be stated as follows: First, the process is continuous and uniform in its results. Second, a larger quantity of gas, having a greater photometric value, is produced by this method than any before devised. Third, the coal is uniformly acted upon by the heat, each particle in detail. Fourth, the gas, as soon as eliminated, is withdrawn from the retort without further decomposition. Fifth, all the light-giving properties of the coal, are obtained in the form of gas without the production of liquid hydrocarbons. Sixth, the' expense of puriiication is reduced. Seventh, the apparatus is compact, nearly automatic, and does not depend to any large extent up on skilled labor for the production of a uniform quality of gas, and the plant required to generate a given quantity of gas is reduced in size and expense. Eighth, the lower grades of coals from Nova Scotia and elsewhere are used successfully to produce gas of proper photometric value without the admixture of the more expensive cannels now so necessary and so much used.

The second part of my invention'relates to the purification of illuminating-gas, and this part of the invention may be used in connection with the apparatus herein shown and described or with the ordinary method of generating gas 5 and consists in a process by which the lime or other mawhicln as has been'carefully estimated and an-` The gas -is eliminated instantly, and, as

In consequence of the incoke and charging with coal is avoided, and the teri al used for purifying is automatically charged into a chamber upon revolving perforated screenplates, through which the gas passes, and the lime, as it becomes charged with the impurities, is gradually withdrawn.

O represents the lime-chamber, which is made of wrought-iron plates or other suitable material. It is supported upon the columnsP at a suitable height, so that the spent material may be conveniently taken away. rlhe perforated screenplates R are mounted on a shaft and revolved by means of a gear and pinion, the 'gear being attached to the top screen-plate and the pinion working inr the water-seal S, which unites and makes a gas-tight joint between the top and body of the apparatus. The linie passes from the hopper T down into the chamber U, which is made gas-tight by the slidevalvcs V, which are e11- cased in a gas-tight casino'. The upper valve being opened and the lower valve closed, tl ie chamber U is filled with lime from the hopper. The upper valve is then closed and the lower valve opened and the lime passes down to the screen, which conveys it to the lower chamber; and from this it may be taken when the chamber is full and removed by the same valve arrangement as is used at entering. The gas-inlet X is a concentric opening passing entirely around the circumference of the purifier, opening into the interior so as to secure a thorough diffusion of the gas. It is delivered in the same manner through the outlet-pipe Y. A slow and gradual revolution is given to the screen-plates, so that the lime, as it becomes impregnated with the impurities of the gas, is constantly .being removed. The lime is constantly in motion and is presenting fresh surfaces in contact with the passing current of gas.

A less quantity of purifying material is used, the gas is brought into more immediate contact with it, and the labor of opening and closing the puriiier, removing the spent material, and filling with fresh lime \is almost entirely dispensed with.

I claim as my invention- I. The manufacture of illulninating-gas from coal by the continuous process, substantially as is herein shown and set forth. l

2. In carrying the above-named process into eeet, an apparatus in which the coal is automatically charged into the retort and the coke is automatically withdrawn, in the manner set forth.

3. In carrying the abovenanied process into effect, a vertical retort, having a water-seal which communicates with an automatic apparatus for removing the coke.

4. In carrying the above-named process into effect, the combination, with a vertical retort, of a charging apparatus, which is constructed so as to deliver and regulate the coal to the retort, substantially as set forth.

5. In carrying the above-named process into effect, the method of carhonizing and decomposing disintegrated coal by the employment of highly-heated steam in a vertical retort, substantially as described.

6. Purifying illuminating-gas by means of an automatic apparatus in which the purifying material is retained between perforated screenplates, which receive a progressive motion in the reverse direction to the current of gas passn g through the purifying-chamber.

7. A purifying apparatus, in which the fresh purifying material is retained in a close chainher communicating with the purifying-chamber by means of valves7 so that the apparatus may be charged without stopping the action of the puri` fier or loss of gas, and in which the spent material is removed in a similar manner.

JOHN A. BASSETT.

Witnesses:

EMIL VossNAcK, H. L. STUART. (38.)

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