US658627A - Apparatus for making pure carbonic acid. - Google Patents

Description

N6. 658,627. Patented Sept. 25. I900.

H. s. ELWORTHY.

APPARATUS FOR MAKING PURE CARBONIC AClD.

(Application filed 153x31, 1900. No Model.)

alka i W1 0 7H5 Noam PETERS ca mom-mum WASHINGTON, n. c.

HERBERT SAMUEL ELIVORTHY, OF LONDON, ENGLAND.

APPARATUS FOR MAKING PURE CARBONIC ACID.

SPECIFICATION forming part of Letters Patent No. 658,627, dated September 25, 1906. Original application filed December 22, 1897, Serial No. 663,049. Divided and this application filed March 31. 1900. Serial To (tZZ 71/71/0177, it nuty concern:

Be it known that I, HERBERT SAMUEL EL- WoRTHY, a subjectof the Queen of Great Britain, residing at London, England, have invented certain new and useful Improvements in Apparatus for Making Pure Carbonic Acid; andl do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has reference more particularly to the manufacture by combustion of carbonic acid free from permanent gases, such nitrogen, for the preparation of liquefied or solid carbonic acid, for the charging of beverages with or without previous liquefaction, and to other uses to which such pure carbonic acid may be adapted; but each of the improvements constituting the invention is intended to be secured for all the uses to which it may be applicable.

The combustion of carbon in carbonaceous bodies of all kinds yields carbonic acid, as is well known, when the combustion is effected with a sufficient quantity of oxygen; but when such combustion is eifected by means of air the resultant gases consist mainly of nitrogen. Such a gaseous mixture is Wholly unsuited to many uses to which carbonic acid is applied, and even a small proportion say five per cent., for example-of a non-condensable gas will interfere with its uses for many purposes. Thus" if it be desired to liquefy the carbonic acid by compression it is found that-it is necessary to employ much, higherpressure (at a given temperature) if even five per cent. of a non-condensable gas is present. Again, if the liquefied carbonic acid is to be used in refrigerating-machines the presence of the non -condensable gas (which may be dissolved in the liquefied carbonic acid) is apt to interfere with the Working of the machine by necessitating higher pressure in compression, and thereby impeding the action of the pumps. Further, if

water is charged with impure carbonic acid the non-condensable gas dissolves also to a sufficient extent to impair the comestible value of the carbonated water, as the so charged Waters lose their sparkle and sharp iNo model.)

taste quickly after opening. Moreover, for certain chemical reactions carbonic acid will not answer if it contain a certain proportion of inert gas. In each of the cases mentioned the same objection would be encountered, whether the impurity consists of air, nitrogen, hydrogen, or other neutral gas non-condensable as compared with carbonic-acid gas. In accordance with the present invention carbon (in the form of coke, charcoal, petroleum, or other carbonaceous substance or substances herein termed the fuel, for convenience of reference) is burned without air by converting the said carbon, first, by steam or carbonic acid or a mixture thereof into carbonic oxid (00) free from non-combustible non-condensable gas, and, second, oxidizing completely this carbonic oxid and any accompanying combustible non-condensable gas by means of a metallic oxid, which is formed again after reduction, so that the same charge can be repeatedly utilized.

In order to convert carbon into carbonic oxid by means of steam or-carbonic acid or mixture thereof, it is necessary to supply heat from an outside source, and to do so in the most advantageous manner recourse is had (in the present invention) to contact with the surfaces of fire-brick or other suitable inert bodies previously raised to a sufiiciently-high temperature. According to one mode the steam or carbonic acid or mixture thereof is superheated by contact with such highly-heated surfaces before it is brought into contact with the carbonaceous substance. According to another mode the steam or carbonic acid or mixture thereof and the fuel are passed together over the highly-heated inert surfaces. These two modes can be combined by admitting part of the fuel to pass with the steam or carbonic acid or mixture thereof over the highly-heated inert surfaces in such manner that the escaping products are so highly superheated that on contact with a further portion of fuelafurther amount of carbonic oxid is formed. In either or any mode the inert surfaces must supply heat enough to compensate for that which is rendered latent by the decomposition of the steam or carbonic acid, or both, and the conversion of carbon into carbonic oxid. In

other words, the formation of the carbonic oxid develops a certain quantity of heat; but the decomposition of the steam or carbonic acid, or both, (the oxidizing-gas as it may be shortly expressed,) renders latent a larger amount of heat than is thus developed. The excess is supplied by contact of the oxidizing-gas or of the oxidizing-gas and fuel with the highly-heated surfaces. The fuel, when superheated steam or carbonic acid is brought in contact therewith, may, and indeed should, itself be at a high temperature. In many places, and perhaps under most conditions, it may be advisable to use coke or charcoal or other solid fuel massed in a stack or cupola as customary in the making of water-gas. At the beginning such coke or other solid fuel may be brought to incandescence by an air-blast; but by suitably superheating the steam or carbonic acid or mixture thereof the formation of carbonic oxidcan afterward be made continuous without requiring the charge to be blown with air at short intervals. Such periodic blowing with air would be very objectionable, because after each application of an air-blast the carbonic oxid obtained would be mixed with the non-condensable non-combustible nitrogen for a considerable time, until, in fact, the nitrogen which would remain in the fuel when the air-blast is stopped should have been all removed. These losses are avoided by supplying the heat by means of inert bodies. If the temperature of the latter fall, they can readily be raised again to a proper tem perature,and if in the heating the nitrogen isleft between them it can readily be swept out by a blast free from non-condensable non-combustible gasas of steam orcarbonic acid, for example.

In order to effect the complete combustion of the carbonic oxid into carbonic acid bya metallic oxid or oxids, the latter may be arranged in various ways. What is considered the best way, itself forming a special improvement, is to combine the oxid with fragments of an inactive or less active substance toconstitute a carrier for the oxid.

The invention also comprises certain other features and certain improvements in apparatus, as hereinafter set forth.

The accompanying drawing, which forms part of the specification, is a diagram of apparatus in accordance with the present invention.

The furnace D, which constitutes a generator of carbonic oxid and which is shown in the form of a cupola, although other forms may be used, is supplied with coke or other solid fuel, or, according to another mode of working, it may be filled with brick or other inert refractory material, or it may be cut out or disused entirely. It is shown as connected on the one side by the flue J with the hot-blast stoves B and O and on the other by the flue P J* with the two oxidizing-furnaces E F, charged with a body E F of an oxidizing or oxidiz'able metal, which most advanta= geously is distributed over the fragments of an inactive or less active refractory substance as a carrier. This carrier is particularly useful in connection with an active substance like copper oxid, which is fusible. Between each of the hot-blast stoves and the fine J is a valve K L, respectively, so that either stove can be connected with the flue J while the other is cut off, the object being to use the stoves alternately. This is necessary with the regenerating type of stove, since such a stove has to be shut off while it is being reheated. Each stove consists of a chamber filled with the open brickwork usual inregencrating-furnaces and provided with the valved inlet X or X for the admission,and valved out let K or Lfor the escape, of the steam or carbonic acid or mixture thereof, and also with a valved inlet W or W for the admission of the reheating-gas, the valved air-pipe U or V for the admission of air for burning the reheating-gas, and a valved passage Gr or G for the escape of the products of combustion. The valved air-pipes lead from a hot-blast stove A, which, as shown, is also of the regenerating type and consists of a chamber filled with the usual brickwork and provided, in addition to the valved air-pipes U and V for delivering the hot-air blast to the chambers B and C, with the valved inlet W for the gas to reheat chamber A, a valved passage G or G for the escape of the products of combustion, and means for admitting air at top or bottom of the chamber, as may be desired. These means most advantageously are constituted by four-way reversing-valves H H provided each with an airinlet h and an outlet H for the products of combustion and interposed one between the tops of the chambers A and B and the other between the tops of chambers A and 0. Between each of these valves and the tops of the corresponding chambers are additional valves, each in the form of an inverted cup g, whose edges are sealed by dipping into a gutter g, which is filled by melted lead or other suitable metal. If the inverted cups gin the passages G and G are raised and the valve 'H is in the position shown in full lines, air

can enter the top of the chamber A, and by turning the valve H to the position shown in dotted lines air from the inlet 71. can enter the top of chamber B and will enter the bottom of the chamber A by the passage U after passing through the brickwork of chamber B. Similarly if the inverted cups in the passages G G are raised, those in the passages G Gr being shut down, air can enter the top of chamber A from the inlet h and passage Gr when valve H is in the position shown. By

turning the said valve to the position shown in dotted lines the air from the inlet It will first enter the top of chamber 0, and after it has passed through the brickwork in this chamber it will enter the bottom of chamber A by the passage V. With this arrangement the dotted openings Z Z Z Z would be unnecessary; but if desired the four-way valves could be omitted and valved passages opening at Z and Z respectively, might serve to admit air to the top and bottom, respectively, or the air could be admitted to the top of the chamber A by an opening at Z and to the bottom of said chamber by the passage U or V, the air in this case first entering the chamber B or G at Z or Z and descending through the brickwork therein before it goes through the passage U or V into the bottom of chamber A.

The connection of the carbonic-oxid generator D with the oxidizing-furnacesE F may be direct or through gas-purifying apparatus, or both forms of connection may be provided. The flue P J* is shown as opening directly into the bottom of the oxidizing-furnaces E F, through the valved branch pipes SQ; but such direct connection is advisable only in case the fuel in the furnace D is a very pure car- Ordinarily the carbonic oxid from the flue J* would be passed through one or more coolers and scrubbers or other purifying apparatus to the pipe R, from which it would pass into whichever of the furnaces E E has its charge E or F in an oxidized condition.

1 At R is indicated such purifying apparatus,

which serves to remove any ammonia or other impurity yielding non-condensable gas by oxidation. After or before passing through the purifying apparatus the carbonic oxid may be stored in gasometers. Blowers can be employed to force the carbonic oxid into the furnaces.

Each of the oxidizing-furnaces has a valved inlet N or N for admitting air or steam thereinto for oxidizing its metallic charge E or F, and each of said furnaces also has an outlet 6 orffor the residual gas and for the carbonicacid gas. As shown, one opening is represented. This may serve for both gases; but of course the passage leading therefrom would be used, one for the residual gas and the other for the carbonic-acid gas. The charge E or F may consist of fragments of brick or other refractory material coated or combined with copper oxid. This is considered the best ma terial; but other oxids and other ways of supporting the oxid can be used so long as aeriform fluids have access to the metallic matter, (oxidized or deoxidized, as the case may be.) What is considered the best way of coating or combining the copper oxid with the refractory material is to fuse the copper oxid, which can be done in any ordinary glass-furnace such as a tank-furnace, for instanceand to immerse fragments of fire-brick therein. To prevent the oxid of copper being reduced by small amounts of organic matter present in the fire-brick or by the gases of combustion, ammonium or sodium nitrate in small amounts may be added to the bath of fused copper oxid from time to time. By making the nitrate adhere to the fragments of firebrick it can be introduced with the latter.

Having charged the furncce D with coke and the furnaces E F with a material which is capable of being oxidized or deoxidized, preferably fragments of fire-brick coated with copper oXid, the said furnaces and also the chambers A B O are raised to a high temperature. To ignite the charge of solid fuel in the furnace D, a fire is started in the bottom of said furnace, the top T is raised, and air from one of the stoves A B Gis blown in until the mass of fuel is at a white heat. At this time the valves S and S are closed, also the valve L (if the air is taken from the chamber B) and the valve U. The air can be admitted to the chamber B through the valve H and passage G by turning the valve H to the dotted position and raising the inverted cup 9 in the passage G or it can be admitted to B by the opening Z", if this be used. To heat the furnaces E and F, air may be introduced at N and N and fuel in the form of carbonic oxid or of other combustible gas through the branches of pipe B. To raise the temperature of chambers A B C, (producergas, for example) from the inlet W is burned among the brickwork of the chamber A by air introduced from the chamber B, (let us say,) or from the passage Z if this be used. By raising the inverted cups 9 in the passages G G" and turning the valve H to the dotted position the air may descend through the chamber B and enter the chamber-A by the passage U, and the products of combustion can escape to the chimney I through the passage G and the flue H. After a proper time (half an hour or more or less) by turning the valve H to the position represented the air will go by the passage G to the top of the chamber A, while products of combustion from the chamber B can escape to the chimney I by the passage G and the flue H. At this time the gas at W is cut off and is admitted at W into the chamber B. Combustion now takes place among the brickwork of the chamber B. After a proper time the valve H is reversed and gas from the opening W is burned among the brickwork of the chamber A by a hot blast of air from the chamber B. In time after changing the position of the valve H as often as necessary both chambers are brought to an intenseheat. In like manner the chamber C is heated, the chamber A serving to heat the air which is introduced by the passage V to the bottom of the chamber 0 and which serves to burn the gas which is introduced at the opening WV. During this operation the passages G G would be closed and the passages G G would be opened and the valve H would be shifted from time to time. Assuming that chamber B is heated to, say, above 1,500 centigrade and that the passages G W",and U are closed, the valve K is opened and also the valves S S Steam or carbonic acid or mixture there- ICC passes 06 to a waste-fiue or to any desired receiver. When all of the nitrogen has been expelled, the valve S is closed and the valves M and S opened, the top Tbeing shut down. The steam or carbonic acid or mixture thereof now passes into the incandescent fuel in the furnace D and is decomposed, the products of decomposition passing out by the flue P J* and valve S to any suitable receiver. When the nitrogen left by the air-blast in the interstices of the fuel in the furnace D has been carried oif, the products of decomposition will consist of carbonic oxid free from non-condensable and non-combustible gas, the only other gases being hydrogen (from the steam, if this is used) and ammonical sulfur and hydrocarbon compounds, (from the solid fuel in the furnace D, if this is not sufliciently pure.) These bodies are either combustible or condensable and therefore removable at once or after combustion in the oxidizing-furnace. Hence they are not open to the objection which arises from the presence of anon-combustible non-condensable gas like nitrogen. In order that the decomposition in the carbonic-oxid generator D may take place as near as may be without loss of temperature, the steam or carbonic acid or mixture thereof is heated by contact with the inert surfaces of the fire-brick in the stove B so much above the temperature necessary for the decomposition in the carbonic-oxid generator that it carries with it from said stove B enough heat energy to compensate for that which is rendered latent by said decomposition without lowering the temperature below the decomposing-point. After a time, however, the temperature of stove B (when of the regenerating type, as shown) becomes insuflicient properly to superheat the steam or carbonic acid or mixture thereof. When this occurs, the valve K is closed, and the brickwork of the stove 0 being at the highest temperature used the valve L and pipe X are opened, so that this stove now supplies the superheated blast of steam or carbonic acid or mixture thereof to the carbonic-oxid generator. Before, however, this steam or carbonic acid or mixture thereof is admitted to the furnace D it is allowed (the valve M being temporarily closed) to blow 0% through the flue J J* and valves S S until the nitrogen is displaced from chamber 0 and flue J J*. The valve M is now opened, the Valve S is closed, and the superheated steam or carbonic acid or mixture thereof from the chamber or regenerating-stove C is admitted to the furnace D. While using the stove C, the brickwork of stove B is reheated by the combustion of gas from opening W by means of a hot blast from the stove A. In this reheating the valve H is shifted once or oftener in the manner before explained. Thus the chambers B and O serve alternately as hot-blast stoves for superheatin g the steam or carbonic acid or mixture thereof, which is supplied to the furnace D, while the chamber A serves as a hot-blast stove for supplying hot air alternately to the stoves B and O for reheating-the same. The carbonic oxid from the generator D free from non-condensable non-combustible gas is passed through whichever of furnaces E F is ready to receive it, the said carbonic oxid being when desired first passed through one or more coolers and scrubbers or other purifying apparatus, or when this is not desired and the carbonic oxid is sufficiently pure being admitted directly to the oxidizing-furnace. Assuming that the furnace E is ready, the valve S and the passage S may be opened for a direct admission, or, the passage S being closed, the carbonic oxid, passing away by the flue Jand the valve S may be passed through appropriate purifying apparatus 13* and afterward be introduced through the pipe R and its left-hand branch. The carbonic oxid or carbonic oxid and other combustible gas in the products of decomposition from the furnace D in passing through the furnace come in contact with the metallic oxid therein and combine with oxygen of said oxid to form carbonic acid or carbonic acid and water. The contact with the said oxid should be sufficient completely to burn all the combustible gas, the resulting product being simply carbonic acid or carbonic acid and vapor of water free from non-condensable gas. After a time the furnace F is utilized, the charge E in furnace E being reoxidized by passage of air or steam from the inlet N through the said charge. If air is used, the operation is completed by a current of steam, so that no nitrogen is left in said furnace. When the charge in the furnace F has been sufliciently deoxidized, the delivery of carbonic oxid thereto is stopped and the charge is reoxidized either by air or steam or mixture thereof, and the furnace E is utilized while this is being done. The carbonic-acid gas from the oxidizing-furnace is passed through coolers for lowering its temperature and removing.

therefrom the vapor of water which it may contain, and, being free from any non-condensable gas, it is then ready for liquefying by compression for charging beverages or for use in the gaseous state.

If it be desired to fill the cupola D with inert refractory material instead of with solid fuel, the fuel for decomposing the steam or carbonic acid or mixture thereof may be introduced into the superheated steam or carbonic acid or mixture thereof on its way to the furnace D, the superheating in the chamber 13 or G being sufficient to supply the heat for elfecting decomposition without lowering the temperature of the furnace D.

Instead of bringing the'fuel into contact with the steam or carbonic acid or mixture thereof after superheating the latter they may be passed together over the highly-heated inert surfaces which supply the heat reudered latent by the decomposition.

drawing the pipes Y Y are for introducing In the liquid or vaporized or gaseous hydrocarbon of any suitable descriptionpetrolcum, for example. Solid fuel in powder could also be introduced alone or in connection with other forms. It might be injected by the blast of steam or carbonic acid or mixture thereof. The furnace D need not be used, and it could either be dispensed with entirely or be simply shut off by closing the valves M and S.

The furnace D, filled with solid fuel, may be used in conjunction with the delivery of fuel into the hot-blast stove, the decomposition of the steam or carbonic acid, or mixture thereof, being effected partlyin the stove and partly in the furnace D. After the decomposition has been carried on in the stove B the brickwork therein loses its temperature until it falls below the decomposition temperature. Just before this point is reached the supply of fuel and of steam or carbonic acid, or mixtu re thereof, is transferred to the stove C, the chamber B being now reheated by producer or other suitable gas from the opening W and a blast of hot airfrom the stove A in the manner hereinbefore explained. The carbonic oxid, free from non-condensable noncombustible gas which is generated in the chambers B and C, is passed through the oxidizing-furnaces E F in such manner that all the combustible gases are completely consumed, leaving only carbonic acid free from non-condensable gas. The carbonic oxid,unless sufficiently pure, should, and it in any case may, be passed through purifying apparatus before it is passed through the oxidizing-furnace. The principal impurity (as is also the case when the steam or carbonic acid or mixture thereof is deoom posed by the solid fuel in the furnace D) would be ammonia, which would be decomposed in the oxidizingfurnace with the elimination of nitrogen. Washing the carbonic oxid with water or dilute acid would remove the ammonia.

Although the pipe J is for convenience shown exposed and unlined, this is preferably made of large diameter and internally lined with refractory material and may also be coated outside with some non-conducting composition. The valves exposed to a high temperature are of the hot-blast type in which a water-current is caused to circulate through the valve and also through the seat to prevent fusion.

It is believed to be of the highest industrial importance to generate the carbonic oxid free from non-condensable non-combustible gas and to effect a complete combustion. by the metallic oxid in the oxidizing-furnaces, so that the carbonic acid thus obtained shall be free from non-condensable gas. In the working of the apparatus described with solid fuel in the furnace D some carbonic oxid is produced (at the beginning of an operation) which is mingled with nitrogen, and itlnay sometimes happen that by carelessness of the attendant a complete combustion is not effected and more or less carbonic acid is obtained which is mingled with hydrogen or carbonic oxid, both of which are non-condensable. Such impure carbonic oxid and carbonic acid may be used as fuel, but it may in some cases he preferred to prepare pure carbonic acid therefrom. For this purpose carbonic oxid can be passed through an oxidizing-furnace, and the carbonic acid thus generated can then be separated from the non-condensable gas by any known or suitable means, such as solution in water under pressure and evaporation therefrom., In the case of the impure carbonic acid a like separation can be effected, or the impure carbonic acid when the non-condensable impurity or impurities are combustible may be passed again over metallic oxid to effect a complete combustion. Heretofore it has been proposed to separate carbonic acid from non-condensable gas in admixture therewith; but, so far as I am aware, this step was never used in combination with the two operations of, first, decomposing steam or carbonic acid, or mixture thereof, and, second, effecting a combustion of the carbonic oxid by metallic oxid. The resulting gaseous mixture consists mainly of carbonic acid, and thus difiers essentially from ordinary products of combustion, which are mainly composed of nitrogen. When carbonic acid predominates. it is much easier to effect a separation of the same than where it is mixed with an excess of nitrogen. When the step of separating the carbonic acid from non-condensable gas in admixture therewith is used in the combination just mentioned, some air might be admit-ted during the decomposing operation into the stove Aor B or into the furnace D, whether this contain solid fuel or be filled with inert refractory material, and some air might be admitted into the furnace E or F during the oxidation of the carbonic oxid to carbonic acid; but this is not recommended. For some uses where carbonic acid above a certain degree (which is always more than half carbonic acid) is required the carbonic acid may be obtained in admixture with the (for such purposes immaterial or comparatively unimportant) amount of non-condensable gas. The generation of carbonic oxid and the oxidation with metallic oxid may be employed without any separation of the carbonic acid from the smaller volume of non-condensable gas mingled therewith.

It will be understood that in referring to carbon in the claims following it is intended to include coke, charcoal, anthracite coal, crude petroleum, petroleunrtar, other petroleum products, coal-tar, wood-tar, asphaltum, bitumens, natural or artificial gas containing carbon compounds, and any other suitable form of carbon, combined or uncombined.

If it should be desired, the carbonic acid free from non-condensable gas can of course be subjected to a treatment calculated to effeet a separation of the carbonic acid from non-condensable gas mixed therewith. Such a treatment would be asolution in water and evaporation from such solution, and it might perhaps be useful in some'oases for a more assured state of absolute purity to use such treatment notwithstanding that the carbonic acid may be free from noncondensable gas, or practically so, for purposes of liquefaction.

Certain hydrocarbon ases such for instance, as natural gas-may be sent through the regenerative stoves B or C and thence into the oxidizing-furnaces E or F Without admixture with steam or carbonic acid; but it is preferable to mixa certain proportion of one or other of the two latter gases with the hydrocarbon. The hydrocarbon gas might also be sent direct into the oxidizing-furnaces without first passing through the regenerative stoves; but in this case again it would be preferable to mix it with a certain proportion of carbonic acid or steam, more especiallythelatter. Wherethehydrocarbonissent direct into the oxidizing-furnaces, it isa difficult matter to get entirely rid of the odor, and this may unfit the gas for commercial use for the manufacture of aerated beverages or ice. Where the production of carbonic acid free from non-condensable gas is desired as the direct result of the oxidation, a complete combustion must be effected by the metallic oxid and the gas or vapor which is passed into the oxidizing-furnace must be free from non-condensable non-combustible gas. If, however, the product after leaving the oxidizing-furnace is to be subjected to a treatment calculated to separate the carbonic acid from condensable gas or if the carbonic acid would be suited to the use intended notwithstanding the presence of a non-condensablegas, which would unfit it for liquefaction, the freedom from non-condensable non-combustible gas of the gas or vapor which is supplied to the oxidizing-furnace and a complete combustion of said gas or vapor by metallic oxid are not essential, the content of carbonic acid in any case exceeding the content of noncondensable gas of the gaseous product which results from the oxidation with metallic oxid.

The process improvements hereinbefore claimed constitute the subject-matter of a patent of even date in my application of December 22, 1897, Serial No. 663,049, of which the application for the present patent (for apparatus) is a division and continuation, my said application of December 22, 1897, being originally for the improvements described both of process and apparatus.

I claim my invention or discovery 1. The combination with an oxidizing-furnace charged with metallic oxid, of a carbonic-oxid generator which excludes air constantly from the decomposing-chamber and which is prpvided with a regenerative hotblast stove for supplying to said chamber the specified oxidizing-gas so highly superheated as to compensate for the heat rendered latent in its decomposition with carbon, said stove having inert heating-surfaces and also having passages separate from the oxidiziu g-gass inlet and outlet for admitting reheating-gas and air to said stove and for discharging therefrom the products of combustion, and being also provided with means for intensely heating the air preparatory to its admission, substantially as described.

2. A carbonic-oxid generator which exeludes air constantly from the decom posingchamber and which is provided with a regenerative hot-blast stove for supplying to said chamber the specified oxidizing-gas so highly superheated as to compensate for the heat rendered latent in its decomposition with carbon, said stove having inert heating-surfaces and also havi ng passages separate from the oxidizing-gass inlet and outlet for admitting reheating-gas and air to said stove and for discharging therefrom the products of the combustion and being also provided with means for intensely heating the air pre paratory to its admission, substantially as described.

' 3. The combination with an oxidizing-furnace of a carbonic-oxid generator which is provided with a hot-blast stove having inert heating-surfaces and also having passages for admitting the specified oxidizing-gas and carbon and for discharging the products of the decomposition, and other passages for admitting reheating-gas and air to said stove and for discharging therefrom the products of the combustion, and being also provided with means for intensely heating the air preparatory to its admission, substantially as described.

4:. A carbonic-oxid generator which is provided with a hot-blast stove havinginert heating-surfaces and also having passages for admitting the specified oxidizing-gas and carbon and for discharging the products of the decomposition, and other passages for admitting reheating-gas and air to said stove and for discharging therefrom the products of the combustion, and being also provided with means for intensely heating the air preparatory to its admission, substantially as described.

5. An apparatus for making carbonic acid, composed of a carbonic-oxid generator, two regenerating hot-blast stoves each consisting of a chamber filled with inert refractory material and'provided with an inlet for the admission and an outlet for the escape of the specified oxidizing as, and also with inlets for the admission of the reheating-gas and air and an outlet for the escape of the products of combustion, valved flue connections between the oxidizing gas outlet of each ofsaid stoves and the said generator for connecting said stoves alternately with said generator, two furnaces each charged with material that can be oxidized and 'deoxidized and provided with inlets for an oxidizing medium and for carbonic oxid respectively and also with outlets for the residual gas and carbonic acid respectively, and valved flue connections between the said carbonic-oxid generator and the carbonic-oxid inlets of each of the said furnaces, for connecting said generator with said furnaces alternately, substantially as described.

6. An apparatus for making carbonic acid, com posed of two regenerating hot-blast stoves each consisting of a chamber filled with inert refractory material and provided With inlets for the admission of carbon and of the specified oxidizing-gas, with an outlet-for the escape of carbonic oXid, and also with inlets for the ad mission of the reheating-gas and air and an outlet for the escape of the products of combustion, two furnaces each charged with material that can be oxidized and deoxidized and provided with inletsfor an oxidizing medium and for carbonic oxid respectively and also with outlets for the residual gas and carbonic acid respect-ively,and valved flue connections between the carbonic-oxid outlet of each of said stoves and the carbonicoxitl inlet of each of said furnaces, substantially as described.

7. An apparatus for making carbonic acid, composed of a carbonic-oxid generator, two regenerating hot-blast stoves each consisting of a chamber filled with inert refractory material and provided with inlets for the admission of carbon and of the specified oxidizinggas, with an outlet for the escape of carbonic oxid and undecomposed portions of the specified oxidizing-gas, and also with inlets for the admission of the reheating-gas and air and an outlet for the escape of the products of combustion, valved flue connections between the oxidizing-gas outlet of each of said stoves and the said generator for connecting said stoves alternately with said generator, two in rnaces each charged with material that can be oxidized and deoxidized and provided with inlets for an oxidizing medium and for carbonic oxid respectively and also with outlets for the residual gas and carbonic acid respectively, and valved flue connections between the said carbonic-oxid generator and the carbonic-oxid inlets and each of the said furnaces, for connecting said generator with said furnaces alternately, substantially described.

8. The combination with a carbonic-oxid generator, of two regenerating hot blast stoves each consisting ofa chamber filled with inert refractt'n-y material and provided with an inlet for theadinission and an outlet for the escape of the specified oxidizing-gas, and also with inlets for the admission of the reheatinggas and air and an outlet for the escape of the products of combustion, and valved flue connections between the oxidizing-gas outlet of each of said stoves and the said generator for connecting said stoves alternately'with said generator, substantially as described.

9. The combination with a carbonic-oxid generator, of two furnaces each charged with material that can be oxidized and deoxidized and provided with inlets for an oxidizing medium and for carbonic oXid respectively and also with outlets for the residual gas and carbonic acid respectively, and valved flue connections between the said carbonic-oxid generator and the carbonic-.oxid inlets of each of the said furnaces, for connecting said generator with said furnaces alternately, substantially as described.

10. Ahot-blast apparatus composed of three regenerating-stoves each provided with inlets for the reheating-gas and an air-blast to be heated and outlets for the escape of the products of combustion and the hot blast, and valved flue connections between one of said stoves and each of the other two, said connections opening into all three stoves at the ends which receive thereheating-gas so as to effect hot-blastcombustion ot the reheating-gas in all three stoves, substantially as described.

11. In combination with a carbonic-oxid generator, a hot-blast apparatus composed of three regenerating-stoves each provided with inlets for the reheatinggas and an air-blast to be heated and outlets for the escape of the products of combustion and the hot blast, and valved flue connections between one of said stoves and each of the other two, said connections opening into all three stoves at the ends which receive the reheating-gas so as to effect hot-blast combustion of the reheating-gas in all three stoves, substantially as described.

12. In combination with afurnace or furnaces charged with material to be oxidized and deoxidized, a hot-blast apparatus composed of three regenerating-stoves each provided with inlets for the reheating-gas and an air-blast to be heated and outlets for the escape of the products of combustion and the hot blast, and valved flue connections between one of said stoves and each of the other two, said connections opening into all three stoves at the ends which receive the reheatingrgas so as to effect hot-blast combustion of the reheating-gas in all three stoves, substantially as described.

13. In combination with a carbonic-oxid generator, and a furnace orfnrnaces connected therewith and charged with an oxidizable and deoxidizable material, a hot-blast apparatus composed of three regenerating-stoves each provided with inlets for the reheatinggas and an air-blast to be heated and outlets for the escape of the products of combustion and the hot blast, and valved flue connections between one of said stoves and each of the other two, said connections opening into all three stoves at-the ends which receive the reheatinggas so as to effect hot-blast combustion of the reheatinggas in all three stoves, substantially as described.

14. Two regenerating-stoves having their fuel-inlet ends connected through a valve for establishing intercommunication and provided at the other end with passages leading to opposite sides of a four-way valve which puts said passages in communication with an airinlet and an outlet respectively, each stove being thereby alternately connected with an air-inlet and an outletaccording to the position of said four-way Valve, substantially as described.

15. Two regenerating stoves connected with each other at top and bottom, the connection at one end being through a four-way valve, and at the other, through a valve which opens the passage between the stoves, and an additional valve being placed in one of the passages between said four-way valve and a stove, substantially as described.

16. In combination with a carbonic-oxidgenerating apparatus in which is used a set of regenerating hot blast stoves provided with valves and passages for continuously supplying a hot blast, two furnaces charged with refractory material combined with metallic oxid and provided with means whereby a stream of carbonic oxid from said generating apparatus can be sent through said fur naces alternately and whereby an oxidizingcurrent can be sent through each furnace when the flow of carbonic oxid is out 01f therefrom, substantially as described.

17. A hot blast apparatus composed of three regenerating hot-blast stoves connected at their fuel-inlet ends through valved passages for establishing intercommunication and provided at the other ends with passages leading to opposite sides of four-way valves each of which puts its own passages in communication with an air-inlet and'an outlet respectively, each stove being thereby alternately connected with an air-inlet and an outlet according to the position of the said fourway valves, substantially as described.

18. A hot blast apparatus composed of three regenerating chambers connected at one end by valved passages which can establish an open way between two chambers, and at the other end through four-way valves and provided with an additional valve or valves between one or both of said four-way valves and one or both the chambers connected with each valve, substantially as described.

19. A carbonicacid plant composed of three regenerating-chambers each provided with inlets for reheating-gas and air-blast to be heated and with outlets for the products of combustion and hot-air blast, and two of them further provided with inlets for carbon and the specified oxidizing-gas, a furnace or furnaces charged with oxidizable and deoxidizable material valved flue connections be tween the said two chambers and the third regenerating-chamber, andvalved flue connections between said two regeneratingchambers'and the said furnace or furnaces, substantially as described.

20. A carbonic acid plant composed of three regenerating-chambers each provided with inlets for reheating-gas and air-blast to be heated and with outlets for the products of combustion and hot air blast, and two of them further provided with inlets for the specified oxidizinggas, valved flue connections between the said two chambers and the third regeuerating-chamber, and valved flue connections between said two regeneratingcliambers and the said carbonic-oxid generator, substantially as described.

21. Two regenerating stoves connected with each other at top and bottom, the connection at one end being through a four-way valve, and at the other by a valved passage which when open establishes communication between the two stoves, and an additional valve being placed in each of the passages between the said four-way valve and a stove, substantially as described.

22. A set of three regenerating-stoves connected at the fuel-inlet ends through valved passages for establishing and shutting off intercommunication and at their opposite ends with valved passages for establishing communication for each stove with an air-inlet and an outlet separately and for shutting the com m unication with both simultaneously, inlets and outlets additional to the foregoing being also provided, substantially as described.

23. The combination with an oxidizing-furnace charged with metallic oXid, a carbonicoxid generator, and an intermediate conduit between the outlet of said generator and the inlet of said furnace, of a regenerator-stove having an inlet for the specified oxidizinggas and separate outlets for respectively the products of combustion and the specified oxidizing-gas, a conduit between the oxidizinggas outlet and the inlet of said generator, a second regenerator-stove, and means for supplying both stoves with gaseous fuel and with highly-heated air, the said means including a conduit between the hot-air outlet of the secoudunentioned stove and a hot-air inlet of the first-mentioned stove, said carbonic-oxid generator being constantly closed against ingress of air, substantially as described.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

HERBERT SAMUEL ELWOR'lli l.

Witnesses:

J OHN HAMPTON BARNES, EVAN B. LEWIS.

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