US1920951A - Gas manufacture - Google Patents

Description

Patented Aug. 1, 1933 GAS MANUFACTURE Charles J. Ramsburg, Edgeworth, Pa., assignor to The Koppers Company of Delaware, a Corporation of Delaware I No Drawing. Application September 27, 1928,

Serial No. 308,870

.2 Claims. (Cl. 20233) My invention relates to gas manufacture and particularly to the production of fuel gas by the distillation of coal or other carbonaceous materials.

My invention has for one of its objects to provide a process for the manufacture of fuel gas whereby valuable by-products may be removedtherefrom without reducing the B. t. u. value below standard requirements for such gas.

A further object of my invention is to provide a process for preparing coal for coking whereby the quality of certain of the by-products of the coking operation are greatly improved.

A further object is to provide a process for treating coal or other carbonaceous material before coking whereby the operating conditions of coking plants are materially improved.

A still further object of my invention is to provide a process whereby an increased quantity of certain by-products of the operation of coking coal may be removed by the resulting gases of distillation without coking additional coal to maintain the total B. t. u. of the gas produced.

In the operation of coking plants for the production of gas to be supplied for domestic use in cities, the plant is ordinarily operated on the basis of the gas required for such use rather than the requirements for the coke produced in the operation. The coke is usually a product that is rather difficult of disposition since the latter has a comparatively limited market and the quantity of coke relative to the gas requirements is usually large.

Accordingly, it is desirable to maintain the quantity of gas relativel high for a given amount of coal to be coked in order that the quantity of. coke produced may be as low as possible. For this reason, it has not been customary to remove certain of the light oils from coke-oven gas because the B. t. u. value of the gas is materially reduced thereby and it is accordingly necessary to coke additional coal in order to supply the same requirements for gas. These light oils comprise benzol, toluol and xylol which are comparatively valuable products and their removal is desirable when it can be accomplished without complicating the operation of the coking plant.

I have found that if thecoal to be coked is treated with oil such as gas oil or fuel oil before the coking operation, the resulting gases of distillation are sufficiently enriched that the light oils may be removed from the resulting gas and the B. t. u. value of the gas after the light oils have been scrubbed therefrom is substantially the same as that of normal coke-oven gas containing the light oils. I have found that such oil may be added to the coal prior to its storage in the bins for charging the coke ovens and thatits addition involves a relatively sm all cost. It has been demonstrated, also, that the addition of the oil very materially improves the operating conditions of the plant in that substantially dustless.

the coal is rendered Furthermore, the quality of certain of the by-products, such, for example, as the tar, is greatly improved by the absence of coal dust therein.

In accordance with the present invention, coal is prepared in the usual in anner for coking by supplying it to a hammer mill for reducing its size. Gas oil or fuel oil, which is a petroleum product, is sprayed through nozzles that are so arranged as to give maximum coverage of the coal upon entering the hammer mill. The rate of oil 'flow may be gauged by suitable metering devices in order that the quantity may be fairly accurately gauged. The coal passes through the hammer mill and over the usual conveyor belts to the storage bins, from which it is supplied to the usual larry cars for charging coking chambers of a coke-oven battery. The quantity of oil added is approximately one percent by weight of the coal. The quantity of oil used per ton of coal is gallons. Tests have shown approximately three that from each gallon of gas oil approximately 96,000 B. t. u.s of gas may be obtained. Light oil may be assumed to have a heating value of 126,000 B. t. u.s per gallon. Accordingly, if three gallons of gas oil areadded to a ton of coa amount of light oil that m 1 before coking, the ay be removed from the resulting gases of distillation without material change from normal B.

t. u. values of cokeoven gas would be'as follows:

gallons.

The coal is coked in the usual manner and the light oils, including benzol, toluol and xylol,

are scrubbed therefrom by well-known means,

scrubbing of the light oils gases of distillation.

from the resulting There are, however, additional advantages from the employment of my invention. One of the most disagreeable features in connection with the operation of a coking plant is the great amount of coal dust resulting from the handling of the coal through the crushing devices such as the hammer mill and the handling by means of the various conveying belts. When the oil is sprayed on the coal at the entrance to the hammer mill, there is an almost entire absence of dust throughout the remainder of the coal-handling system and this improvement of operating conditions has been very marked.

A further improvement in operating conditions has been the elimination of the relatively large quantity of coal dust that has blown upward upon the charging of coke ovens, a great percentage of which adheres to the upper side walls and roof of the coke oven and forms what is known as "roof carbon. The removal of this material requires considerable labor and a delay in the recharging of the ovens from which it is being removed, as well as a loss of heating gas by reason of the necessity for circulating cold air through the roof of the oven.

The substantial elimination of dust during the charging operation, as well as the subsequent coking operation, has resulted in materially improving the quality of the tar, which is a byproduct of the manufacture of coke and cokeoven gas. Prior to the employment of my invention, a comparatively large quantity of coal dust and coke dust has been withdrawn from the coke ovens with the gases of distillation and the result has been to very materially increase the insoluble material in the tar and to correspondingly increase the residue when tar is distilled. This residue is a great disadvantage in that it increases the difiiculties by reason of the formation of coke in the bottoms of tar stills.

The employment of my invention has reduced the free carbon content of tar produced in connection with coke ovens from about 4.9% to 3.5%, a reduction of approximately 30%. The free carbon content remaining in tar under the improved conditions is composed principally of pitchy or resinous materials and it is not desirable to further reduce the free carbon content.

-facture and the production of coke.

The cracking operation in the coke ovens by means of which the oil added to'the coke is gasified does not require additional gas for underfiring since the exothermic and the endothermic reactions of the cracking operation substantially balance each other. Accordingly, the B. t. u. value ofthe gas from the oil is added to the coke-oven gas without additional expense for the transformation. In addition, the residue from the oil is probably added to' the coke in the form of skin carbon and the B. t. u. value of the coke is accordingly somewhat increased.

It will be noted that the employment of my invention results in a number of advantages. It permits the recovery of valuable by-products which was not possible heretofore without increasing the quantity of coke relative to the amount of gas produced by the plant. Operating conditions surrounding the plant have been greatly improved by the substantial elimination of dust during the handling of the coal and its charging into the ovens.

The formation of roof carbon has been materially reduced, thus increasing the percentage of time that each oven is in actual operation. The quality of tar has been improved by the reduction of its free carbon content and the distillation of the tar has been rendered less difiicult.

The foregoing and other advantages will be apparent to those skilled inthe art of gas manu- My invention is not to be limited except as expressed in the claims.

I claim as my invention:

1. The process of producing coke-oven gas of substantially normal B. t. u. value, which comprises adding approximately one percent by weight of gas oil to coal to be coked, coking said coal and then removing light oils from the resulting gas.

2. The process of producing coke-oven gas of substantially normal B. t. u. value, which comprises adding approximately three gallons of heavy hydrocarbon oil to each ton of coal to be coked, coking said coal and then removing light oils from the resulting gas.

CHARLES J. RAMSBURG.