US2247336A - Gas set and method - Google Patents

Description

June 24, i941, ..1. e. @KEEP-FV GAS SET AND METHOD Filed Jan. 14, 195s 2 sheets-sheet 1 ses A@ 2&5.

SQ Su June 24, 1941, 1 G, OKEEFFE 2,247,336

GAS SET AND METHOD Filed Jan. 14, 1959 2 Sheets-Sheet 2 ATTO EY j Patented June 24, 1941 GAS SET AND METHOD James G. OKeeie, Verona, N. J., assigner to Public Service Electric & yGras Co., Newark, N. J., a corporation of New Jersey Application January 14, 1939, Serial No. 250,883

8 Claims.

The present invention relates to improvements in carbon removal, and carbon deposit control, and is especially adapted for use in connection with carburetted water gas sets.

In 'the carburetting of water gas with hydrocarbon oils, particularly where a low grade heavy fuel oil yor residuum high in carbon content is used, the result of thermal decomposition of the oil is the formation and accumulation of carbon which deposits and buil-ds up into a hard cokelike material having an insulating effect on the fire-brick, lowering the efficiency yof the gas set and presenting a difficult removal problem.

The present invention relates to means and to a method for removing such carbon deposits, and controlling their accumulation, during the operation of the gas set. The invention is more particularly appli-cable to gas sets in which the carburetter is free or substantially free of checkerbrick or its equivalent, that is, in which the carburetter interior oiers substantially unobstructed passage through it for 'the gases, as distinguished from a carburetter whose interior is lled or substantially filled with checkerbrick or the like.

For many years the building up of a -caking ycarb-on deposit in the carburetter has presented a problem in the art, and its removal has been attempted in several ways and been effectively laccomplished in one. This is the manual removal `method which has to beresorted to at frequent intervals, commonly of the order of two to four days because of carburetting with low grade or high carbon content oils. This method requires opening of the doors of the carburet-ter chamber through which tools are inserted to remove the carbon- Relatively recent improvements in carburetting methods have eliminated the necessity `oi filling the carburetter with checkerbrick which had long been used to volatilize the oil which was iiowed upon and through it after the -checkerbrick had been heated by the blast gases. Carburetting may now be accomplished by spraying the oil under pressure, in a finely divided or atomiZe-d form, into a carburetter free or substantially free of checkerbrick or the like, but the result of eliminating the checkerbrick is that the carbon builds up von the walls and door, and

the problem of .its removal still exists. It is with this type of Icarburetter that the present invention may most advantageously be used.

In an eiort to avoid frequent shutdowns of gas sets `for the manual cleaning out of the carbon cake, attempts have been made to keep down or remove the carbon; deposit by burning it off With air, or by subjecting it to the action of va passing flow of steam while it is incandescent, the idea in both attempts being to combine i't with oxygen and drive off the resulting gas. For example, it has been proposed to supply, during the blast period, air in excess of the secondary air required for the combustion of the blast gases, in Ethe hope that such `air will supply enough loxygen to combine with lthe incandescent carbon deposit and carry it ofi. Such known attempts, however, have resulted only in a quick dilution of the excess air with the products of combustion of the producer gas and secondary air, so that the excess yair has been relatively ineffective on the carbon deposit. Some old attempts to solve the problem required adding la step in the usual gas cycle, by producing a flow oi" air through the set between blow and run periods. These attempts also were inadequately eiliective, besides merely substituting one disadvantage for another With-out gain. The time yand cost required to blow steam through the set to rem-ove carbon deposit make such methods impractical, even if lan effective result could be accomplished by them. But because of the temperatures involved it is impractical to remove all or even ya satisfactorily substantial part of the carbon by a mere run of steam through the set.

It is .an object of the present invention to provide a process and a preferred construction by which the objectionable carbon deposit can be removed and its accumulati-on controlled eflicierrtly and satisfactorily with `air during the blow period, and to a relatively slight exten-t with steam during the run.

Another object of the invention is to accomplish this result while at the same time providing for Ithe prevention of explosions.

The invention provides for the removal and control of carbon deposits in a carbure'tted water gas set to an extent that permits the continuous cyclic operation of the set over long periods yof time with continuing high operating eiliciency. Additional objects and advantages of the invention will appear from the following description, taken in connection with the accompanying drawings which illustrate a preferred embodiment of means by which the invention may be carried out.

The invention consists in the method of carbon removal and control hereinafter pointed out and claimed, and in the construction constituting a preferred means for carrying out the method.

In the drawings:

Fig, 1 is a vertical sectional view through a series of cooperating chambers constituting, and intended as illustrative of, the essential apparatus of .a water gas set in which the oarburetter chamber is free, or substantially free, of `gas flow obstruction, the illustration showing a preferred embodiment of the structure of the present invention;

Fig. 2 is a horizontal sectional View through the carburetter of Fig. 1;

Fig. 3 `is a transverse Vertical sectional View illustrating a preferred structural embodiment of inner wall nre-brick;

Fig. 4 is a top plan View thereof;

Fig. 5 is a front elevation of the fire-brick of Fig. 4;

Fig. 6 is a side elevation partly in section illustrating the construction of a diierent over-al1 shape of fire-brick such as is preferably used in the structure of Fig. 1 where a wall direction changes, for example, where the lower part of the crown of the oarburetter meets the side wall; and

Fig. 7 is a horizontal sectional View taken on line I-'I of Fig. 6.

Referring in detail to the drawings, a generator I supports on its grate the coke bed 2 supplied through the normally closed charging opening at the top of the generator. generator is provided with a steam inlet 3, a primary inlet 4, and a bottom gas outlet 5 leading to conduit 6 whose other end leads into the usual Wash-box IQ. At its upper end the generator is open to passage I, provided with secondary air inlet 9, and opening into the upper end of carburetter 8. The carburetter 8 is shown as being of the type that is absolutely free of checkerbrick because it is with this type that the greatest efciency of the invention can be realized. will be understood, however, that the invention may be practiced,v so far as the carburetter lining is concerned, with a carburetter whose interior may offer some obstruction' to gas passage but the invention is not directed to gas sets using carburetters lled or substantially filled with checkerbrick.

The carburetter 8 at its bottom has the connecting passage II opening into the bottom of superheater I2 which may be, and is shown as being, substantially filled with checkerbrick It. At its top, below the crown, the superheater is provided with a tertiary air inlet I5. The superheater has the usual stack valve It and takeoiT pipe 20 leading past a steam inlet 2l to washbox HI. The conduit 6 and the take-01T pipe 20 lead to the wash-box through a two-way valve 23, which in one position closes the conduit 6 from the wash-box and in the other position closes the passage 2i) therefrom, It will be understood that washed carburetter water gas passes through the wash-box to a collector main or storage in the usual manner.

The carburetter 8 is provided with an' oil atomizing spray shown at 26, and connected to a supply (not shown) of carburetting oil under pressure.

In order to illustrate more fully the extent to which the invention may be practiced, the generator I is shown as being supplied with a similar oil atomizing spray 23, although it will be understood that this, while preferred, is optional in the` sense that the invention in its broader aspects may be practiced where no oil is supplied within the generator.

Below the grate the It l.

Uil

The foregoing general description is intended to be illustrative of carburetted water gas sets in which the carburetter is absolutely or substantially free of checkerbrick or other obstruction.

The following description of ordinary cyclic operation of such a carburetted water gas set will shown where and when the objectionable carbon deposit tends to occur, and would normally occur and build up except for the present invention which as hereinafter described accomplishes its control or removal concurrently with the normal operation of the gas set.

The first stage of an operation cycle is the heating up stage or blow period, during Which steam inlet 3 in the generator is closed, primary air inlet is open, secondary air inlet S is open, tertiary air inlet IG is open, stack Valve I8 is open, steam inlet 2l is closed, and two-way valve 23 closes take-off pipe 29 from conduit 6. At this time conduit E also may, if desired, be closed oif by an additional valve, not shown. Air under pressure passes from primary air inlet ll up through the hot coke bed 2, burning the coke', bringing it to incandescence and generating blast gas which passes through the connection I into the upper part of the carburetter, the secondary air supplied through air inlet 9 serving to provide oxygen for its combustion. The burning blast gas passes downwardly through the carburetter, heating the nre-brick of the inner walls thereof, thence through bottom passage II and up through the checkerbrick of the superheater, heating the superheater and its checkerbrick, thence out throughl open stack valve I8 to atmosphere. The tertiary air supplied at I6 in the superheater provides additional oxygen to efect complete combustion of the blast gases before their discharge. With stack valve I3 open, the blast gases cannot enter the wash box because the pressure in the superheater is substantially atmospheric and the liquid seal at the wash box entrance prevents the flow into the gas holders of products of combustion.

When the coke has thus been brought to incandescence and to a temperature hot enough to make water gas, and the carburetter and superheater brought to the desired temperature, the blow is stopped and the second stage of the cycle, or gas run, is commenced, the first part of which is the up-run gas making period.

For making the run the primary air inlet 4 is closed, the secondary air supply 9 is closed, tertiary air supply i6 is closed, stack valve I8 is closed, steam supply inlet 2l is closed, two-way valve 23 still closes off wash box from conduit 6 and opens the wash boX to take-OIT pipe 20, and the steam supply inlet 3 is opened. In its passage upwardly through the incandescent coke, the steam injected under pressure at 3 reacts with the coke to form water gas which passes through connecting passage 'I into the top of the hot oarburetter. At this time, oil under pressure is sprayed into the Carburettor at 28 and its thermal decomposition results in combining the enriching oil gas with the water gas, and deposition of the carbon residue on the walls, floor and crown of the carburetter chamber, where, unless controlled or removed, it will accumulate in hard, coke-like deposits. The water gas and enriching gas pass from the bottom of the carburetter through pipe II into the bottom of the superheater and upwardly through the hot checkerbrick thereof, where they are intimately mixed, and the now xed oarburetted water gas passes through take-off pipe 20 into the washbox and thence to a collector main or storage, not shown. With stack valve I8 closed, the generated gas pushes down the liquid in the wash-box entrance dip pipe, escapes into the space above the liquid seal and is delivered to the holders.

During this up-run gas making period, further enrichment of the Water gas may be accomplished by injecting a spray of oil under pressure through atomizer 2S in the crown of the generator. This tends to produce carbon deposit on the generator crown, especially opposite the atomizer 28 due to the direction of gas flow, as well as upon the walls of the connecting passage 7 adjacent the oil spray.

Following the up-run it is usual to reverse the steam flow and commence a down-run. There are several reasons for this reversal, among them being `the character and location of the clinker or ash formation, and the cooling during the up-run of the lower portion of the coke body below efficient water gas making temperature while the top portion is still hot enough to make water gas.

For this purpose, all the air supplies remaining closed, steam supply 3 is closed, twoway valve 23 is moved to close oif the wash-box from passage 23 and open it to passage ii, and steam supply 2| is opened. The carburetting oil supply at 26 is shut off.

Steam supplied at 2l now enters the top of the superheater, travels down through it into the bottom of and upwardly through the carburetter, thence through passage 7 into the top of the generator where it strikes the upper or hottest part of the coke body, producing water gas which passes through conduit ii to the wash-box and thence to storage.

During the down-run, oil is sprayed at 23 into the generator. Due to the direction of the steam entering the top of the generator, the oil spray supply tends to be forced back against the generator crown in the vicinity of atomizer 23, with a tendency for the objectionable carbon residue to accumulate there. Any carbon deposit that would tend to 'accumulate at the bottom of the generator is simply added to the coke bed.

As 'soon as the upper portion of the coke bed, due to the injection of fresh steam upon it, cools to a point where further gas manufacture is ineiiicient, the down-run generating step is stopped by shutting off the steam supply at ZI and the oil supply at Z3. After this, there is preferably a short up-run of steam. through the set to purge it oi explosive gas before the next blow.

This completes the cycle, after which another blow period is started by closing oif all oil and steam and supplying air at d, 9 and i6 as above described to bring the coke bed to incandescence and heat the carburetter and superheater for the next gas run.

In accordance with the present invention, the removal and control of carbon deposit, and the prevention of its accumulation where it tends to form, are accomplished as follows:

Referring rst to the carburetter, where the carbon has the greatest tendency to accumulate, the carburetter refractory wall lining itself is constructed as 4a multiple blower, aud for this purpose consists of an outer wall and an inner wall spaced from it preferably by a generally annular chamber. As shown in the drawings, the wall, for this purpose, has a multiplicity of closely arranged openings, so that it has the general structure of, and functions like, a periorated grate. To accomplish best results from the invention, the crown and iioor of the carburetter are similarly constructed.

As stated above, there have been efforts in the art to use air for carbon deposit removal and control. These have included up or down air runs through the carburetter or the injection of air into the carburetter from a nozzle or nozzles directing the air into the carburetter interior with a View to having such air effect carbon control or removal simply by being present in the carburetter or by impinging upon some carbon deposit generally opposite the air supply and in any case `after the air has left the nozzle and completed its entrance into the carburetter interior. As distinguished from such efforts, which in practice accomplish little, the present invention provides an interior carburetter wall that is itself, in effect, `a blower, being so by reason of its being constructed as a multiplicity of closely adjacent air supplies, which accomplish the carbon control and removal not after any air has left is outlet and traveled from it across the carburetter to some other surface, but in the immediate local zone of each outlet itself and before the air has completed its departure from its outlet, in fact, during the time it is leaving its outlet. In accordance with the best construction the firebrick lining is so constructed that it is itself a multiple nozzle.

For this purpose, according to the preferred form of construction, the iire-bricks comprising the inner carburetter wall are each provided with one or a plurality of tuyres, preferably opening conically into the interior of the carburetter chamber and. connecting it with the annular space separating th-e inner and outer carburetter walls.

Structural examples of such iire-brick are shown in Figs. 3 to '7 inclusive. In Fig. 4 iirebrick 3l! has the conical passage 3i extending through it and similar half passages at each end, these half passages fitting with corresponding half passages at the ends of adjoining rebrick. It will be understood that the brick 3!) is not intended as a limiting denition of the shape or num-ber of the passages through the iire-brick, since it is obvious that these may, for example, he dependent upon the size or location of the bricks, and that within structurally safe limits an increase in the number of passages results in more eiiicient attainment. The invention, therefore, contemplates a plurality of complete tuyres in each brick.

To illustrate how the invention may be ernpioy-ed to greatest advantage, the nozzle wall structure is shown as being extended to include interior wall areas of the gas set wherever objectionable carbon tends to accumulate. Accordingly, it is shown as composing the crown and floor of the carburetter, including the lower part of the connecting passage il also the con necting passage 7 between carburetter and generator; also the crown and upper wall portion of the generator. The nozzle wall arrangement as here shown is satisfactorily adapted for the control and removal of carbon deposits formed as a result of using the illustrated, and in fact almost any, arrangement as to location and direction of oil sprays.

Figs. 6 and '7 show one form of tuyre firebrick, used, for example, at the base of the crown of the Carburettor and generator. The

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fire-brick 35 has the tuyre 38 opening into the brick channel 'Sii which aligns vertically with the annular air chamber and laterally with similar channels in adjacent crown base fire-brick. The portion 42 rests upon part of the outer wall to which the radial component of the weight of the crown may be transmitted by the projection Liri. It is obvious that to provide for desirable stability of the inner wall it may be anchored to the outer wall by anchor braces l5 or by other means.

To better illustrate the operation of the invention in the gas set shown, the inner wall firebrick, which necessarily appear therein on a reduced scale, are shown in Figs. 1 and 2 as having one passage through each brick, the small scale necessary to show the whole gas set preventing satisfactory illustration in these iigures of a plurality of passages through each brick, such as those shown in Figs. 4 and 5, or a` greater number, it being understood that the invention is not limited to one passage through each brick, but contemplates a plurality of such passages in the preferred construction.

Air may be supplied as shown in Fig. 1, in which valved air supply lines 5t connect with a plurality of valved delivery pipes 5l to supply air for the carburetter crown, Carburettor Wall, carburetter floor, and also for the passage il. Valve controlled air supply line 555 may connect by a valved delivery pipe 5l with the air supply space around the connecting passage l, including adjacent areas of the carburetter and generator crowns. A valved air supply line 58 may connect by a valved delivery pipe 59 to the generator crown air supply chamber. vIn general, it will be understood that any eicient air delivery system may be used to supply air under pressure to and through the inner wall at all points where there is a tendency for carbon to deposit and accumulate, the valves being used to regulate the supply to different zones in. accordance with local carbon deposition tendency. Obviously, the number of separate air supply chambers leading to different lining Zones may vary as may be desired.

The carbon controlling and removing air is forced through the inner walls during the blow period or heating-up stage and While leaving each brick tuyre to enter the carburetter or other gas set chamber, the air, heated by contact with the lire-brick lining, contacts with and supplies oxygen for the burning away of the hot carbon deposit in the local area around each tuyre opening, that is, in the part of the wall immediately adjacent the tuyre opening itself. It may be noted that this immediate attack upon immediately-adjacent carbon promptly effects the desired reaction with `the carbon deposit, so that this air initially and primarily effects carbon control and removal, as distinguished from first being diluted with, and having its oxygen used up in burning the blast gases.

In this manner any carbon `deposited upon the inner walls of `the gas set during a precedingcarburetting water gas step is kept down or removed during the blast step or blow period of each cycle, with the result that it does not build up into the objectionable insulating deposits which have heretofore required such frequent shutdowns.

A further feature of the invention relates to the prevention of explosions. This is accomplished not only without interfering with the regular cycle of the set, but also, where steam is used as the inert purging gas, with the advantage of producing at the same time, though to a miner extent, a certain amount of water gas.

In accordance with this feature, when the blow period or heating-up stage has been completed, the valved air supplies 50, 5E and 53 are shut oli and valved steam supplies 6D, 6G and 68 opened to the valved inlet supply pipes 5l, '51 and 59. Just as air was supplied through these pipes at a pressure greater than the pressure inside the gas set, so now steam is supplied to the same annular chambers to flow through the inner walls at a pressure greater than the internal pressure in the gas set during the water gas making stage. To a minor extent water gas is thus made by contact of this steam with such carbon as was deposited and was not entirely removed from the inner walls by the air supply, but the more important purposes of this supply of steam through the inner walls are first, to purge the set, including the spaces between inner and outer walls, of any air left there when the air supply was shut off at the end of the blow, driving such air into the interior of the gas set and through it so tha-t it would not be present between the walls, and thereby supply oxygen during the gas making step which might cause an explosion. The second important result accomplished at the same ytime is that this steam flow keeps all the tuyres open by preventing any carbon from depositing in the tuyres of the fire-brick lining in such a manner as to clog them. As a result, when the next blow stage is reached the carbon removing and controlling air supply repeats its action through all the tuyred lire-brick, and thus acts without loss of efficiency. rlhe ovr of steam is continued preferably throughout the up-run, and may be continued or not during the down-run as desired.

It will be evident that any carbon deposited occurs not at all in the passages through the rebrick and that any carbon deposition that does occur must be localized upon the unapertured rire-brick surfaces. 0f such carbon deposition it may be said, first, that such areas are preferably relatively small due to the large number and relatively close arrangement of vthe lire-brick tuyres; second, such carbon deposition never has a chance to build up to have any substantial or objectionable insulating effect upon the rebrick because its tendency to accumulate is counteracted by the burning-01T air supplied during each blow to the hot carbon.

It will be understood that air and steam are thus supplied alternately through the same openings, the air during the blow only, and the steam during the gas run only, at which time steam is being supplied to the generator for making water gas, and oil is being supplied for carburetting it. The purging and clogging preventing steam may be supplied during the up-run, down-run or both, and its contact with any adjacent hot carbon deposit results in the making of some,v though only a small amount, of Water gas which is added to that made in the generator.

From the foregoing, it will be clear that larger or smaller bricks may be used for the refractory lining or inner wall; that the number and shape of the tuyres in the refractory lining may be varied and that, still without departing from the invention, the double wall structure 'may be more extensive throughout the set or less extensive than that shown in the drawings, the obviously important feature being that in accordance with the invention it is used where it is desired to control the extent of carbon deposit by removing carbon as above described. The term carbon as herein used will be understood by those in the art to include the hard caking deposit, mostly carbon, that forms in water gas sets as a result of carburetting with hydrocarbon oils, including low grade or heavy oils, and oil residuum of high carbon content. It will also be understood that the term removal as herein used means the removal of such deposits to an eX- tent sufficient to prevent them from building up into an insulating deposit upon the nre-brick that heretofore has tended to lower the efficiency of the set and has required such frequent shutdowns to effect its removal. The term air is used because it is efficient for the purpose of burning away the carbon, is representative of any oxygen containing gas because air is already customarily supplied to gas sets of the type described for generating the blast gases and accomplishing their combustion, and hence is already available. The invention is described as using steam as a purging gas and to keep the carbon burning air outlets open because it is necessarily already available in water gas sets, is not inammable but inert, and has the added advantage of producing a small amount of water gas, added to the set output, by reason of its contacting the hot carbon deposits.

With the construction described it is possible to burn ofi` the deposited carbon as a separate or additional step in the cycle, but it is emciently, conveniently and preferably burned oir as described during the blow period. Before it reaches the carbon deposit the air is heated in its passage to and through the air outlet mouths in the refractory lining since it travels through the hot chamber separating the two walls and also through the hot nre-brick. By reason of its increased temperature its reactive effect upon the carbon deposit is increased. The double wall construction serves not only for the purposes indicated, but decreases heat losses by radiation from the set.

The invention provides for forcing carbon removing air, during the blow, in greater or less amounts, locally controllable, as may be necessary to supply oxygen for the burning away of the carbon on the air delivery wall zones themselves without increasing the air flow force to the point where it is merely injected away from the Wall toward and into, or through the center of. the gas set chamber, the purpose being to .provide for a flow of relatively undiluted air as a repeatedly replenished supply, or as a layer, formed by overlapping air streams, entering through and along the refractory walls in the direction of gas flow, the air being located in contact with the deposited carbon and between the refractory lining and the blast gas flowing through the set. Thus the carbon burning air is preserved from dilution with the products of combustion of blast gases until it has first reached the carbon deposit, and preliminary diminution of its oxygen content by appropriation for blast gas combustion is prevented. Hence the oxygen of the air is supplied primarily to the hot carbon on the refractory lining between the air iiow outlets therein, with the result that the carbon deposits on the air delivery walls themselves are consumed substantially as they are formed during each cycle.

In operation, any efficiency-lowering accumulation of carbon deposit in a carburetted water gas set is indicated by the tests, customarily conducted at frequent intervals, of the quality of the gas being produced; and as the distributionof carbon accumulation in any given set is known, the air supplied may be regulated by the valves to consume the carbon, the actual quantities of air supplied in any given set varying from time to time with the carbon forming characteristics of the carburetting oil used, the location and direction of the oil sprays, and the nature, location and extent of the carbon deposit. The invention is therefore not dependent upon using high air pressure, by which is meant high enough to force air jets at high speed quickly away from the refractory lining, across intervening space to some carbon deposit, but, on the contrary, depends upon injecting the air in such a manner as to provide for what may be termed a clinging flow of air or an air layer or both, continuously replenished, lying along the refractory Walls between them and the blast gas flow. In this way the air supplies its oxygen freshly and primarily for the combustion of deposited carbon, before the air has its oxygen supply reduced by appropriation for blast gas combustion, and its remaining oxygen diluted by the combustion products.

What is claimed is:

1. The method of preventing accumulation of carbon on the interior surfaces of a water gas set due to carburetting during the water gas run, comprising flowing carbon consuming air over said surfaces during the blast period at such a velocity and through numerous contiguous openings throughout said surfaces that said surf-aces are bathed with the said carbon consuming air during the blast gas flow and without substantial intermingling of said carbon consuming air with said blast gas flow.

2. The method of removing deposits of carbon from the interior surfaces of a water gas set due to carburetting during the water gas run, comprising injecting carbon consuming air during the blast gas run through a large number of closely adjacent openings in said surfaces and at such low velocity that the air discharged through the said openings iiows along said surfaces in the air stream joining relation to form a closely adherent carbon consuming air film on said surfaces between them and the blast gas flow.

3. The method of removing and controlling the accumulation of carbon deposits on the interior surfaces of a water gas set due to carburetting during the water gas run which cornprises flowing carbon combusting air over said surfaces during the blast gas run, said air being delivered onto and caused to iiow over said carbon deposits under a low velocity in such a manner as to closely adhere to the said interior surfaces in the form of a film thereon between said surfaces and the blast gas fiow, and discontinuing the fiow of said air and replacing it with a similar ow of steam during the water gas run.

4. The method of controlling the accumulation of carbon deposits on the interior surface of the carburetting chamber of a water gas set, comprising bathing the said surface during the blast gas run only with low velocity carbon consuming air in such a manner that the said air forms a closely adherent layer on sai-d surface between it and the blast gas flowing thereover and without substantial intermingling with the said blast gas.

5. A method as defined in claim 3, in which during the blast gas flow, a separate and additional air supply of higher velocity than the said carbon combusting air supply is injected into intermingling and combustion effecting relation with the said blast gas.

6. In a carburetted water gas set, a carburetter having a substantially open interior, means for effecting combustion of deposited carbon in the carburetter by flowing therealong a 10W velocity surface layer of carbon burning air lrn between the carburetter surface an-d a blast gas flow` through the carburetter, said means comprising a perforated refractory lining for said carburetter composed of closely contiguous multiple perforations through said lining, said perforations being closely adjacent and inwardly flared in cross section and having their discharge openings in substantially air stream joining relation with one another, and means for supplying air through the said perforations to form said closely adjacent perforations therethrough, said perforations being in substantially air stream joining relation with one another, and means for supplying air through the said perforations to form said low velocity carbon burning layer.

Y 8. In a carburetted water gas set, a carburetter, meansfor effecting combustion of deposited carbon in the carburetter by flowing therealong a low velocity surface annular layer of carbon burning air between the carburetter surface and a blast gas flow through the carburetter, said means comprising a refractory lining composed of tuyered nre-brick providing closely adjacent multiple jets through said liningj said jets being outwardly flared in cross section towards their `discharge openings whereby the air passing through the jets is reduced in velocity and is discharged in substantially air stream joining relation with one another to form a clinging lin of air on said carburetter surface, means for supplying air through the tuyres of said firebrick to form said carbon burning layer, and means to deliver during the blast period an additional supply of air of increasing velocity into the blast gas flow in combustion effecting relation therewith.

JAMES G. OKEEFFE.

CERTIFICATE OF CORRECTION. Patent No. 2,2Lm556, i June 2L, 19in..

JAMEsG. WKEEFFE..

It is hereby certified that error appears in the printed specification of the above numbered patent requiring; correction as follows: Page 2, first column, line 52, before "inlet" insert --air--g page, second .column, line 2li, for the word "is" reed -its; page 5, second column, line l?, for "both" read --bath; that the said Letters Patent should be read" with this correction therein that the same may conform to the record of the case in the Ptent office. Y

Signed and sealed this 50th day of September, L D. 19ML Henry Van Arsdale, (Seal) Acting Commissioner of Patents

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