US795790A - Process of producing gas. - Google Patents

Description

UNITED STATES PATENT OFFICE.

, OARLETON ELLIS, OF NEW YORK, N. Y., ASSIGNOR TO ELDRED PROCESS COMPANY. OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF PRODUCING GAS.

Specification of Letters Patent.

Patented July 25, 1905.

Application filed ry 11, 1905. Serial No.240,626.

To all whom it may concern:

. gas by the producer process as distinguished from the retort and water-gas processes.

It relates particularly to that branch of the art wherein the gas producer is functionally remote from the consuming apparatus, and may therefore be an entirely independent structure, although independence of structure is not absolutely necessary to the practice of my invention, and it is possible to combine the gas producer and consuming apparatus in a single structure, provided the organization be such as to preserve the essential functional characteristics.

In the practice of this art it has been necessary to employ a thick bed of incandescent coal, so that the carbon dioxid from the combustion in the lower layers may pass through the hot layers above, to be there reduced, as far as possible, to carbon monoxid, one of the atoms of oxygen of the carbon dioxid splitting off and oining with an atom of carbon of the coal, thus making two molecules of carbon monoxid from one of dioxid. This reduction is never complete. The combustible gas from a gas-producer always contains carbon dioxid, and many efforts have been made to reduce the amount in order to secure greater fuel efficiency; but these haphazard attempt s up to the present time have been abortive, as certain principles connected with the law of mass action have not been realized.

I have discovered that the gases formed in or passing through a producer have a certain affinity or absorptive capacity for carbon dioxid which prevents its complete reduction. I believe that the principle involved has been heretofore noted in connection with certain laboratory experiments in connection with the theoretical investigations of Rathke; but Ibelieve that Iam the first to have discovered that this principle, heretofore apprehended theoretically, is of commercial importance in the practical art of making producer-gas. So far as I am aware, all of the makeshifts proposed have been founded on incorrect conceptions, not taking into account this principle, and for this reason, among others, they have not effected the end desired. 'By the application of the hereinafter-described chemical theory I have been enabled to solve the difficulty and to put the adjustment of the producer for highest efficiency upon an exact scientific basis.

The carbon dioxid found in the gas is derived by methods heretofore employed from the combustion of the coal in the producer. It is produced at the expense of fuel and without compensation, as a general rule, from steam dissociation. The coal in the producer therefore burns partly to carbon monoxid and partly to carbon dioxid; but up to the present time it has not been possible to burn this carbon completely to monoxid. In the combustion to carbon dioxid the full heat value of the fuel is evolved in the producer, where for obvious reasons it is of course not desired. Increase in carbon dioxid in the gas should mean increase in hydrogen when steam is used as the endothermic or cooling agent. This rarely proves to be the case. Therefore the content of carbon dioxid in the gas is generally taken as the index of efliciency or measure of waste. The object of my invention is to burn the carbon entirely to carbon monoxid and to thus overcome the waste now attendant on the complete combustion of a portion of the fuel to carbon dioxid. The reaction between carbon dioxid and carbon to form carbon monoxid is a reversible one and is expressed by in which the arrows indicate that the reaction may progress in either direction, according to circumstances. I determine this condition of reversibility from the following reactions:

(1.) The principal reaction in the lower part of the producer.

(2.) Reaction of reduction occurring at 600 centigrade and upward.

(3 and 4.) The reaction investigated by Mallard & LeChatelier. This occurs at temperatures varying from 300 centigrade to 800 centigrade.

or the reaction may take place in either direction. In accordance with the laws of mass action the products of the partial pressures of the two left-hand members of the equation 2 divided by the square of the par- (5.) From reactions 3 and 4.

tial pressure of the right-hand member, is a constant, or.

where p. is the partial pressure of carbon dioxid, p that of carbon, and p that of carbon monoxid. By the law of mass action this condition of equilibrium is dependent, not on the relative amounts of the reacting bodies, but on the concentration of these bodies. This explains, then, whyit has been impossible to reduce carbon dioxid to an inconsiderable amount by any of the methods heretofore exploited. Finding the reduction in the concentration of carbon dioxid below the degree represented by the artial pressure 19,, to be practically impossib e, I have found it feasi le to provide from an external source the carbon dioxid necessary to create this partial pressure. The determination of the amount of carbon dioxid required for the purpose may be found approximately by making a determination of the percentage of carbon dioxid in the gas produced by an air-blast containing no endothermically-reactin agent, care being taken that the bed of fuel during this determination is of such depth that no free oxygen passes through the fire unchanged. Under such conditions the percentage of carbon dioxid represents fairly Well the partial pressure requirement of the gas for this constituent.

My invention consists in the institution by external means of the desired partial pressure of carbon dioxid in the gas-producer. I aim to secure an equilibrium between carbon monoxid and carbon dioxid in an artificial manner, and I thus suppress the natural Carbon dioxid from any suitable source as, for instance, from waste products of combustionis introduced into the producer in amount sufficient to create the partial pressure 1).. along with air or oxygen. Striking the lower part of the fuel-bed the oxygen is burned to carbon dioxid, and the mixture passes up through the incandescent fuel, where reduction to carbon monoxid takes place down to that point where the partial pressure p. is realized. Thenceforth no further reduction occurs, and the gas departs with its complement of carbon dioxid represented by the partial pressure or concentration p... In so far as the object of this invention is concerned any possible interreactions occurring before the concentration p in the gas is reached to the carbon dioxid introduced from external sources need not be considered. The final or net result of the process is the combustion of carbon entirely to carbon monoxid.

For example, a gas-producer aflords a gas of the average composition: carbon dioxid, five per cent. carbon monoxid, twenty per cent. hydrogen, fifteen per cent.; hydrocarbons, three per cent. nitrogen, fifty-two per cent; steam, five per cent. The partial pressures of these constituents will be denoted hereinafter by the expression p 1),, p p 1),, and 19 respectively. The partial pressure of carbon dioxid or 10,, I call the partial-pressure-efliciency factor of the producer. The total pressure of the gas is P, and the partialpressure equation for the gaseous constituents is Now p the partial pressure of carbondioxid, provided no reaction producin carbon dioxid other than that embraced in these partial-pressure considerations exists, is represented by five per cent. in the above state ment, and this five per cent. represents the partial-pressure factor of efficiency of-the producer. The combustible matter of the gas consisting of carbon monoxid, hydrogen, and hydrocarbons heretofore shown and amounting to thirty-eight parts of the total will, if calculated in thermal value into terms of carbon monoxid, be equivalent to about forty-five parts of the latter. The thirtyeight parts of the total combustible matter in one hundred parts of the gas may therefore be expressed as equivalent to forty-five parts carbon monoxid. The carbon completely burned, as shown, to carbon dioxid is five parts, and this expressed in terms of carbon monoxid remains the same numerically namely, five parts. The total fuel value is therefore representd by fifty parts carbon monoxid, and the fuel allowed to go to waste in this manner is five-fiftieths or ten per cent. of the total. By my process this fuel is saved. Endothermic. reactions conducted in the producer with steam or otherwise do not succeed in converting the excess of heat developed in the formation of this carbon dioxid into latent gaseous energy as shown, by the fact hereinbefore mentioned that hydrogen does not increase in proportion as carbon dioxid increases.

In certain cases where the producer is efficiently desi ned, so as to largely complete reactions wit 'n 'thethick uniform fuel-bed, particularly where no steam is used or where the amount of steam is not too large, the partial pressure of carbon dioxid required in operating by my process may be obtained by the introduction of an amount of carbon dioxid which may be determined with approximate accuracy by making it equal in weight to the amount of carbon dioxid normally present in the combustible gaseous product.

What I claim is- 1. Process of generating combustible gas having a high content of carbon monoxid and alow content of carbon dioxid which consists in introducing into the gas-producing mass of fuel an air-blast containing as an endothermic constituent only carbon dioxid, approximately equivalent in amount to that producedby the passage through the fuel of an air-current containing no endothermicallyreacting medium, and in thereby artificially creating within the fuel mass the carbon-dioxid partial pressure p whereby a relatively large amount of fuel is converted into combustible gas. I

2. Process for generating producer-gas rich in combustible matter which consists in introducing into the draft-current supplied to the gas-producing mass of fuel as an endothermic constituent only an amount of carbon dioxid approximating that produced by the passage through the fuel of an air-current containing no endothermically-reacting constituent; thereby instituting the necessary partial pressure p... and converting a relatively large amount of the fuel into combustible gas.

3; Process for producing combustible gas having a relatively high content of carbon monoxid and a relatively low content of carbon dioxid which consists in injecting into the producer along with the air-draft as the endothermic constituent only an amount of carbon dioxid approximately equal to the amount of carbon dioxid present in the producer-gas, and under conditions which prevent the passage through the fuel-bed of free oxygen.

4. Process of manufacturing producer-gas containing a maximum of combustible elements in a producer constructed and designed to largely complete combustible-gasgenerating reactions and to pass little or no unchanged steam, whch process consists in injecting into the producer along with the draft thereto as the endothermic constituent only an amount of carbon dioxid approximately the same as the amount of carbon dioxid normally present in the gaseous products of said producer.

5. The process of generating producergas rich in combustible matter which consists in supplying to the blast fed through the producer as the sole endothermic constituent the amount of carbon dioxid which would be normally formed by the action of the blast alone in said producer, thereby eliminating the formation of carbon dioxid in said producer and waste of heat thereby.

6. The process of generating producer-gas rich in combustible matter which consists in supplying to the air-blast fed through a producer as the sole endothermic constituent the amount of carbon dioxid which would be normally formed by the action of the airblast alone in said producer, thereby eliminating the formation of carbon dioxid in said producer and waste of heat thereby.

7. The process of generating producer-gas rich in combustible elements which consists in determining the partial pressure p, of the carbon dioxid in the gas furnished in the normal working of a gas-producer and thereafter supplying to the blast feeding the said producer from extraneous sources as the sole endothermic constituent an amount of carbon dioxid corresponding to the said artial pressure, p substantially as described.

8. The process of enriching producer-gas which consists in determining the partial pressure, p of the carbon dioxid in the gas furnished in the working of a gas-producer by a pure-air blast under conditions which prevent the passage through the fuel-bed of free oxygen, and thereafter supplying to the blast feeding the said producer from extraneous sources as the sole endothermic constituent the amount of carbon dioxid corresponding to said partial pressure, p substantially as described.

9. In the art of making producer-gas having a relatively high content of carbon monoxid and a relatively low content of carbon dioxid, process for the substantially complete conversion of the fixed carbon of the fuel into carbon monoxid which consists in determining the partial pressure, p of the gas formed in passing an air-draft containin no endothermic constituent through the fuel mass under conditions which prevent the passage therethrough of free oxygen; and in thereafter supplying to the blast feeding the said fuel mass from extraneous sources the amount of carbon dioxid corresponding to the partial pressure, 19,, and no other endothermic constituent, substantially as de scribed.

10. In the art of making producer-gas having a relatively high content of carbon monoxid and a relatively low content of carbon dioxid, the process for the substantially complete conversion of the fixed carbon of the fuel into carbon monoxid, which consists in determining the partial pressure, p of the gas formed in passing an air-draft containing no endothermic constituent through the fuel mass under conditions which prevent the passage therethrough of free oxygen, and in thereafter supplying a blast composed only of air and products of combustion, and in re ulating the proportion of the latter with reference to its content of carbon dioxid to create the partial ressure, p of carbon dioxid within the fue mass.

Signed at New York city, in the county of New York and State of New York, this 10th day of January, A. D. 1905.

CARLETON ELLIS.

Witnesses:

MARY AGNES NELSON, GEORGE C. DEAN.