US1949728A - Process for manufacturing carbureted water gas - Google Patents

Description

March 6, 1934.

PROCESS FOR MANUFACTURING CARBURETED WATER GAS Filed May 16, 1951 2 Sheets-Sheet 1 Ziff im Q G. J. NoRDMl-:YER 1,949,728

March 6, 1934. G. J. NoRDMEYER 1,949,728 PROCESS FOR MANUFACTURING CARBURETED WATER GAS Filed May 16, 1931 2 Sheets-Sheet 2 JNVENTOR. :ZM/meyer Patented Mar. 6, 1934 g 1,949,728 PROCESS FOR MANUFACTURING CARBURETED WATER GAS Gerald J. Nordmeyer, Fort Wayne, Ind., assigner to The Koppers Company of Delaware, a corporation of Delaware Application May 16, 1931, Serial No. 537,911

3 Claims.

My invention relates to the manufacture of carbureted water gas, and more particularly to process and apparatus for the manufacture of carbureted water gas in which water gas, generated by the passage of steam through a bed of incandescent carbonaceous fuel, is carbureted at elevated temperatures by the addition thereto of heavy oil.

As is well known, carbureted water gas is ordinarily made inv an intermittent manner, that is to say in a series of cycles each comprising principally a blow or heating period, and a run or gas-making period. The blow or air-blast period is carried out by blasting a bed of carbonaceous fuel to incandescence, removing the resultant air-blast gases and conducting them through carbureting apparatus, which generally comprises a carbureter and a superheater the interior of each of which is partially lled with checkerbrick.

During the passage of the air-blast gases through the carbureting apparatus, additional or secondary air is admitted, causing the combustion of the air-blast gases. In this manner the carbureting apparatus is brought to a high temperature by means of the heat of combustion or sensible heat of the air-blast gases.

In the subsequent steam run period, steam is passed through the incandescent fuel and all or a portion of the resultantwater gas is conducted through the highly heated carbureting apparatus where oil is introduced to carburet and enrich the gas, This oil is vaporized, cracked, and finally fixed as a permanent gas in the stream of water gas, thereby forming carbureted water gas,whichis then withdrawn for use as fuel or illuminating gas. This cycle of operation is repeated, carbureted Water gas thus being produced intermittently.

At the present time the greatest problem confronting the manufacturers of carbureted water gas is the use of heavy oil, such as bunker oil. The gas oils which have been used for carbureting purposes in the past are now becoming more expensive and less available.

By reason of these facts as Well as the necessity y of reducing manufacturing costs to a point where carbureted water gas can successfully compete with natural gas, oil refinery gas and other gases now available, it has become of the greatest importance for the manufacturerof carbureted Water gas to be able to employ for carbureting purposes inexpensive heavy oils of low grade, such as the so-called bunker oils.

However, when it has been attempted to use such oils for carbureting purposes in the manufacture of carbureted water gas great diillculties have been encountered, principally from the extremely high coke content and the low volatility of such oils. Carbureted water gas processes which have been entirely satisfactory insofarV as .60 the use of gas oil having less than 1% coke content is concerned have proved entirely incapable of handling heavy fuel oils, the cokeV content of which ranges from 6% to 20%.

In instances where such oil has been substituted for gas oil in plants previously operating satisfactorily on gas oil, without other change in the process or apparatus, the carbon deposits formed in the carbureting apparatus have been so excessive that the passages through the check- I erbrick of the carbureter and superheater have been plugged with carbon deposit within a few hours, frequently necessitating shutting down the apparatus before one day's operation had beenr completed.

Moreover, this shutting down has necessarily been followed by removal and replacement of the checkerbrick in the carbureter, an expensive, tedious and time-consuming operation greatly increasing the manufacturing cost of the gas. 8o Moreover in such instances the oil cracking eillciencies and fuel economies obtained have been poor.

It has been proposed as a solution `of this heavy oil problem that the checkerbrick be removed from the carbureter of the standard threeshell set. but this method is open to a number of marked disadvantages. In the first place, the removal of checkerbrick greatly reduces the thermal capacity of the set and makes it diillcult to introduce the necessary quantity of oil, this diiculty being enhanced by the fact that the oil employed is more diilcult to volatilize and crack than the lighter oils previously used.

It has also been found that tne use of a separate checkerless carbureter necessitates daily cleaning periods of an hour or more in duration in which the carbon deposited in the bottom and on the sides of the carbureter must be removed by hand. Despite statements in the literature to the contrary, this carbon deposits in the bottom and on the walls of the carbureter in a hard, tenacious form, making such manual re-v moval diflicult and tedious.

It has also been proposed to spray part or 105 all of the oil into the upper portion of the generator where the removal of the checkerbrick from the separate carbureter so reduced the thermal capacity of the carbureter as to make it impossible to introduce all of the necessary oil into the same, but this method has not proved entirely satisfactory in the past by reason of the fact that prior apparatus and methods have not provided sufficiently for accumulating enough heat in the upper portion of the generator to properly handle the admission of oil at this point.

In order for an entirely satisfactory solution of the heavy oil problem to be accomplished, it is clear that the solution must be dominated by certain considerations. In the first place, the capacity of the set must not be decreased and it must be possible to produce gas of satisfactory thermal value at proper oil and fuel economies. The deposit of carbon in the carbureting apparatus must be consumed automatically during the regular course of the cycle so that no shutdown periods for carbon removal are necessary.

Moreover, the carbon deposit should be entirely utilized as fuel, and preferably in such manner as to assist in maintaining the desired high temperature conditions in the generator fuel bed and carbureting apparatus. The proper balance of temperature conditions throughout the set must be maintained in order to carefully avoid that operating condition which makes gas too high in heating value to be wasted and yet too high in inerts to be delivered to the holder. Moreover, it is highly desirable to provide a cycle of gas making operations in all portions or periods of which some useful purpose other than the mere removal of carbon is being accomplished.

In view of the above, therefore, the general object of my present invention is the provision of apparatus and process for the manufacture of carbureted water gas in which heavy oil isemployed for carbureting purposes and which shall be free from disadvantages such as those set forth hereinabove and effective to provide a solution for the problem of the utilization of heavy oil in the manufacture of carbureted water gas.

A further object of my invention is to provide a process for the manufacture of carbureted water gas from heavy oil in which carbon deposited from the heavy oil is removed during the ordinary cycle of operation without necessitating shut-down periods for the removal of such carbon from the apparatus, and without lengthening the cycle.

A third object of my invention is to provide a process for the manufacture of carbureted water gas from heavy oil in which carbon deposited from the heavy oil is advantageously employed as fuel in the process.

A further object of my invention is to provide a process of the character indicated in which regulation of temperatures throughout the apparatus, and more particularly in the fuel bed and carbureting apparatus, within an efficient range is facilitated, and in which improved fuel and oil economies may be obtained.

A still further object of my invention is to provide a method of the character indicated that is simple in operation and does not require inclusion of periods or operations of little utility in the operating cycle.

A still further object of my invention is to provide a method for the manufacture of carbureted water gas from heavy oil in which the advantages of a separate checkerless carbureter may be obtained withoutincurring the disadvantages inherent in the same.

A still further object of my invention is to provide simplified and compact apparatus for the manufacture of carbureted water gas from heavy oil and which shall be especially suitable for carrying out the process hereinafter described.

My invention has for further objects such other operative advantages and improvements as may hereinafter be found to obtain.

My invention does not contemplate a departure from the fundamental water gas operating cycle of intermittent blow and run, although as will be apparent hereinbelow, the contemplated cycle or cycles of operation differ materially as to the nature and extent of various portions of the cycle as compared with prior cycles employed for the manufacture of carbureted Water gas from gas oil and the like.

My invention contemplates the provision of a two-shell apparatus consisting primarily of a generator or combined generator-carbureter and a superheater, the generator-carbureter having an internal portion located above the fuel bed which is unobstructed by cheokerbrick and which has an increased thermal capacity as compared to unobstructed portions of previous generators.

Into this unobstructed upper portion of the generator which essentially constitutes the carbureter of the set I introduce all of the heavy oil necessary for carburetinglthe water gas made during the operating cycle, this intrdouction of oil being accomplished in such manner that the residual carbon is deposited on the upper portion of the fuel bed in the generator.

In order to provide for the accumulation of sufficient heat in the walls of the unobstructed upper portion of the generator and in the upper portion of the fuel bed, I employ as an integral portion of the operating cycle afreverse-air-blast in the manner set forth and described in the copending application of Gerald J. Nordmeyer and Thomas W. Stone, Serial No. 537,968, filed May 16, 1931, or as set forth in the copending application of George I. Koons and Malcolm H. Mer- 12(- ritt, Serial No. 537,969, also filed May 16, 1931.

I have found that the use of reverse-air-blast in the amount and manner described in the aforesaid applications is particularly advantageous Y with respect to the manufacture of carbureted water gas from heavy oil according to the present invention.

In general, this use of reverse-air-blast comprises the passage of sufficient air in reverse direction through the superheater, carbureter and generator to cause the combustion of all or substantially all of the carbon deposited in the apparatus during the introduction of heavy oil.

As also described in the aforesaid applications, additional secondary air may be added during the reverse-air-blast period and all or a portion of the reverse-air-blast gases thus produced may be withdrawn where so desired at an intermediate level in the generator fuel bed just below that portion of the fuel bed the temperature of which 14.0 is affected by the introduction of heavy oil thereto.

In order that my invention may be fully set forth and understood I now describe with reference to the accompanying drawings the preferred lf2/.tc

manner and form in which my invention may be practiced and embodied. In these drawings,

Figure 1 is a view partly in elevation and partly in vertical section of apparatus for manufactur- "ing carbureted water gas in accordance with the 15D ing upon the fuel bed 6.

present invention, certain parts being more or less diagrammatically shown; v

Fig. 2 is a view partly in elevation and partly in vertical section of the upper portion of the generator shown in Figs. 1 and 3 and illustrating a preferred manner in which fuel is discharged into the same; and

Fig. 3 is a plan view of the apparatus shown in Fig. 1.

Similar characters of reference designate similar parts in each of the views of the drawings.

Referring to these drawings, there is shown apparatus for manufacturing carbureted water gas comprising principally a generator or combined generator and carbureter 1, a superheater 2, and a gas oiitake seal or tar batter 3.

The generator 1, which is of substantially twice the normal height, is provided at its lower portion with a grate v5 adapted to support a bed of carbonaceous fuel 6 occupying the lower half of the interior of the generator 1. There is also preferably, but not necessarily, provided means such as a revolving beam 7 'for continuously removing ash or clinker from the fuel bed 6.

The upper portion 8 of the and unobstructed and is of a size comparable `to the size of the carbureters which have been employed in the prior art. f

Fuel is introduced to the generator from a charging opening 9 located in the top thereof, the introduction of the fuel being preferably accomplished by an automatic charging device 10 located immediately above the charging opening 9 and having a spreader 1l of substantially conical shape which is adapted to cause the fuel entering the generator to be thrown outwardly and to impinge upon the walls of the upper or carbureting portion 8 of the generator 1 while fall- In Fig. 3 the charging device 10 has been omitted for convenience.

The upper portions of the generator 1 and the superheater 2 are connected by means of a conduit 12 which is so constituted as to provide a permanently free passage for gas between the generator and superheater. The interior of the superheater 2 is partially filled with checkerbrick 13, this checkerbrick being preferably so spaced as to provide minimum obstruction of the ow of gas therethrough with maximum heat storage capacity.

The lower portion of the superheater 2. is provided with a gas olftake conduit 14 having a branch 15 and a stack valve 16 leading to a stack (not shownyfor discharge of gases to the atmosphere, and also having a branch 17 leading to the tar batter 3 and terminating below the level of the sealing liquid therein.

The base of the generator 1 is provided with a conduit 18 for introduction of gases into or' removal of gases from the generator fuel bed 6. as the case may be, said conduit having a branch 19 and stack valve 20 leading toa suitable stack (not shown) for discharge of gases into the atmosphere and a branch 22 leading to the tar batter 3 and terminating below the level of sealing liquid therein. K

Within the tar batter 3 there is provided a valve device 23 adapted to alternately and oppositely open and close the connections 17 and 22 in accordance with the desired sequence of operation. The tar batter 3 is also provided with a gas offtake 24 leading to a gas h older (not shown) or to the distribution system. It will be understood that one purpose of the tar batter 3 and valve 23 is to insure against pasgenerator is openV `into account sage of gas in a reverse direction from the gas oiftake 24 into the carbureted water gas set and another purpose of the same is' to provide for the reversal of flow through the generator and superheater.

In Fig. 1 the valve 23 is shown in position for the passage of gas in a forward direction through the generator and superheater in the order named and thence through the tar batter 3 to the gas oiftake 24, while preventing flow of gas from the base of the generator to the tar batter 3. If the valve 23 is reversed so that it closes conduit 17 and opens conduit 22 then gas can iiow only through the superheater and generator 1 in the opposite direction.

Air blast for the operation of the set is provided from an air blast manifold 31 which is provided with a primary blast pipe 32 having a valve 33 and leading through the connection 18 into the base of the generator 1. A secondary air blast pipe 34 has a valve 35 and communicates with the top of the superheater 2, or alter-- natively with the conduit 12. Also, a reverseair-blast pipe 36 has a valve 37 and communicates with the conduit 14 leading to the base of ,100 the superheater 2, or alternatively leads directly into the base of the superheater 2.

Heavy oil for carbureting purposes is supplied from suitable storage and heating facilities (not shown) through a conduit 40 and mani- 105 fold pipe 41 and a plurality of sprays 42 having valves 43 and located inthe side of the upper portion 8 of the generator 1 at a point not far removed from the top of the fuel bed 6. Heavy oil may also be additionally or alternatively introduced through a conduit 44having a valve 45 and terminating in a spray 46 located in the extreme upper portion of the generator 1.

The sprays employed for the introduction of the heavy oil are preferably' so designed as to 115 provide for substantial atomization of the oil introduced and preferably constitute sprays such as those shown in my copending application Serial No.537, 912 (Case No'. 494) filed concurrenterewith. 120

I further provide an uprun steam connection having a valve 51 and communicating through the connection 18 at the base o1' the generator 1, a backrun steam connection 52 having a valve 53 and communicating with connection 17 or al- 125 ternatively leading directly into the lower portion of the superheater 2, and also (for use when so desired) a downrun steam pipe 54 having a valve 55 and communicating with the upper portion of the generator 1, or alternatively with the 1U conduit 12.

The generator 1 is preferably provided with a reverse-air-blast oiltake manifold communicating through a plurality of ports 61 with the I generator fuel bed. The ports 61 may be of any 136 desired number according to the size of the generator 1 and are preferably located on a circle at an intermediate level of the fue! bed 6 and preferably from two to five feet below the top of the fuel bed.

This level is readily determined by an analysis of the reverse-air-blast gases passing downward through the generator fuel bed 6 todeterminle` that point at which said gases contain a minimum content of carbon monoxide. In this connection it may be noted that variations in the depth of the generator fuel bed must be taken in locating the ports 61.

Where, as in the preferred instance, mechanical charging apparatus is employed and the 160 through the fuel bed 6.

generator is charged with fuel during each operating cycle, the level of the'top of the fuel bed 6 will remain fairly constant. In any event the ports 61 will be located with reference to the average height of the adjacent or outer portions of the f uel bed, bearing in mind the effect of temperature changes during the charging cycle upon the carbon monoxide content of the reverse-air-blast gases.

The reverse-air-blast oiftake manifold is provided with a connection 62 having a stack valve 63 leading to a stack (not shown), and may also be provided, where so desired, with a branch connection leading to a waste heat boiler (not shown).

With respect to the aforesaid apparatus, I now describe for purposes of illustration a preferred operating cycle according to which the process of my present invention may advantageously be carried out. This cycle consists of the following periods and operations set forth hereinbelow.

1. Forward-air-blast period During this period all steam andloil valves are closed, as are the auxiliary stack valves 20 and 63, while the reversing valve 23 is held in the position in which it is shown in Fig. 1. The reverse-air-blast valve 37 is also closed, the primary air blast valve 33 being open. Air is admitted to the base of the generator 1 and passes upward The resultant air blast gases then pass through the upper portion 8 of the generator and through the conduit 12 to the top of the superheater2.

After the first few seconds of this period additional or secondary air is admitted by opening the secondary-air-blast valve 35 to admit sumcient air to cause the tially all of the carbon monoxide content of the air-blast gases coming from the generator l.

The resultant air-blast gases andgases of combustion pass downward through the superheater 2, meantime yielding the greater portion of their gases of combustion or sensible heat to the checkerbrick 13, and finally pass through the conduits 14 and 15 to the open stack valve 16 into the atmosphere.

When the desired temperature conditions, as determined largely by the nature of the heavy oil to be employed for carbureting purposes, have been attained, the forward-air-blast period is discontinued by closing the valves 33 and 35 and the stack valve 16. A reverse-air-blast period then follows.

2. Reverse-air-blast period y the superheater 2 becoming highly superheated through contact with the checkerbrick 13 and causing the combustion of carbon deposited thereon, and then passes in this highly heated condition through the conduit 12 into the upper portion 8 of the generator 1. Here the highly heated reverse-air-blast causes the combustion of substantially all carbon deposited upon the walls of the upper portion 8 of the generator 1, which assists in raising the temperature of the walls to a very high poi t sufficient to effect the necessary volatllization of oil during the ensuing carbureting period.

The highly heated reverse-air-blast then enters the fuel bed, causing the combustion in the upper portion thereof, which combustion is largely that of carbon deposited in the fuel bed during the admission of heavy oil to the generator in a previous carbureting period.'

The resultant reverse-air-blast gases then pass downward through the remainder of the generator fuel bed 6, driving ahead of them any airblast gases produced in the previous period and still remaining in the apparatus, which gases may. as indicated above, for a brief blow run period of a few seconds be withdrawn through the gas offtake 24 and commingled with carbureted water gas produced during other periods of the cycle.

As soon as this brief blow run period is accomplished the stack valve 20 or the stack valve 63 is opened, thus permitting the discharge of the reverse-air-blast gases to the atmosphere. As an alternative procedure, these gases may be discharged through a waste heat boiler or otherA heat recovery apparatus.

As hereinabove set forth, it is preferred to employ the stack valve 63 for this purpose rather than the stack valve 20 in order that the reverseair-blast gases may pass through the upper portion only of the fuel bed 6 and be withdrawn at a point where they have the minimum carbon monoxide content. In the upper portion of the fuel bed during this reverse-air-blast period the reactions favor the formation of carbon dioxide.

But if the reverse-air-blast gases are permitted t-o traverse the entire fuel bed, carbon dioxide present in the reverse-air-blast gases entering the generator l, or formed during-the passage of the reverse-air-blast downward through the upper portion 8 of 'the generator 1 and the upper 115 portion of the fuel bed 6, will tend to be converted to carbon monoxide in the lower portion of the fuel bed. This would produce a gas of too high calorific value to be discharged to the atmosphere without los`s of fuel economy and too high in inert gases, such as nitrogen and carbon dioxide, to be included for other than a very brief period in the make.

During this period, as set forth in the copending application of Nordmeyer and Stone, at least sufficient air is employed to insure the combustion of the carbon deposit within the carbureting apparatus, and it is desirable to provide additional air in such quantity as to cause sufficient combustion in the upper portion of the fuel bed 6 to balance the heat reduction caused by the introduction of heavy oil to the upper portion of the generator during other portions of the cycle.

It will be obvious that the combustion taking place within the carbureting space 8 and also in 135 the upper portion of the fuel bed 6 during this reverse-air-blast period is largely that of carbon derived from the decomposition of heavy oil employed for carbureting purposes in a previous cycle so that not only is the set kept free of undesirable carbon but the fuel value of this carbon is recovered in a particularly advantageous mannerand to a valuable extent.

The introduction of air during the reverse-airblast'period with the above in view may be ac- 145 complished solely throughthe reverse-air-blast connection 36, but in many instances it will be desirable to introduce only sufficient air through the connection 36 to insure the combustion of such carbon as has been deposited upon the 150 checkerbrick 134 within the superheater 2 or to cause sufficient preheating of the reverse-airblast entering the generator to effect proper combustion of carbon within the latter. In this instance such additional air as may be necessary to cause the desired combustion in the top of the generator fuel bed 6 will be introduced to the Secondary air connection 34 and the secondary lair blast valve 35.

According to this mode of operation the passage of excessive amounts of air through the superheater 2 may be avoided, thus eliminating any undesirable cooling effect upon the superheater 2 which might be caused by excessive air blasting and also reducing the total back pressure exerted by the apparatus upon the reverseair-blast which in turn makes it possible to blast more air through the apparatus in a shorter time.

Just before the conclusionl of this reverseair-blast period the stack valve or the stack valve 63 (depending upon which one of these valves has been in the open position) may be closed, thus providing for a brief blow run period in which the reverse-air-blast gases (which at this time may contain considerable quantities of carbon monoxide) are permitted topass through the connections 18 and 22 into the tar batter 3 and out through the gas oitake 24, to be commingled with carbureted water gas produced during other portions of the cycle.

A steam run then follows which is divided into three periods, the first of which is a steam-uprun period.

3. Initial steam-uprun period With all the stack valves and air valves closed and the reversing valve 23 placed in the position in which it is shown in Fig. 1, steamis admitted through the connections and 18 to the base of the generator 1 by opening the steam uprun 'valve 51.

.batter 3, and finally out through the gas oiftake 24.

During substantially the whole of this period, heavy oil, preferably at a high temperature and considerable pressure is introduced through the sprays 42 or 46, or both, to the upper portion 8 of the generator 1. For example, I may employ a temperature of 200 F. and a pressure of 225 lbs. per square inch, or whatever pressure and temperature are necessary in order to provide a proper flow of oil.

I'his heavy oil upon entering the interior of the generator is volatilized by the radiant and sensible heat of the walls of the generator and upper portion of the fuel bed and by the sensible heat of the water gas passing upward from the fuel bed 6. The resultant oil gases and vapors commingle with the water gas and pass to the superheater 2 where they are permanently fixed by contact with the highly heated checkerbrick 13 within the latter, thus producing carbureted water gas.

As this is the only portion of the cycle in which oil can be admitted for carbureting purposes without reducing the specific gravity of the final gas it is necessary, except in the instance noted hereinbelow, to accomplish a suflicient carburetion of the uprun water gas produced during this period to so provide that the monate mixture of carbureted and uncarbureted gases passing through the gas ofl'take 24 during the entirel course of the cycle is of suicient caloric value,

for example, for 500 to 530 B. t. u. per cubic feet.

The large size of the upper portion 8 of the generator 1 and the use of reverse-air-blast in the manner disclosed for storing heat in the walls of the generator and in the upper portion of the fuel bed 6 make it possible according to the present invention to introduce all of the necessary heavy oil into the generator 1.

In order to maintain the proper conditions within the generator fuel bed it is necessary to reverse the `direction of steam flow through the generator fuel bed during a considerable portion of the total steam run. This is preferably accomplished by following the foregoing period with a steam backrun or downrun period.

4. Steam backrun o1' dowm'un period In going from a steam uprun period to a steam backrun period the uprun steam valve 51 is closed, the reversing valve 23 is placed in a position opposite to that shown in Fig. 1 and the backrun steam valve 53 is opened. Steam now flows through the backrun connection 52 and connections 17 and 14 into the bottom of the superheater 2, and passes upward through the superheater 2 and conduit 12 intothe top of the generator 1. 105

During its travel the backrun steam becomes highly superheated by contact with the checkerbrick 13 within the superheater 2 and may also react with any small quantities of carbonaiceous material remaining upon the to form water gas, thereby consuming such carbon.

The resultant highly heated backrun steam, which may include small quantities of water gas produced in the manner just described, then passes downward through the upper portion 8 of the generator 1 where it may form more water gas if there is any carbon remaining upon the walls surrounding theupper portion 8 of the checkerbrick 13 1,10

generator 1, and nally passes downward through the generator fuel bed 6. The resultant backrun water gas then passes from the base of the generator 1 through the connections 18 and 22 into the tar batter 3 and is withdrawn through the gas offtake 24 to be commingled with water gas and blowrun gas produced during other portions of the cycle.

Where the specific gravity of the final gas is otherwise somewhat high, it may be desirable to introduce heavy oil to the generator during this period. By reason of the fact that the oil vapors and gas thus produced areicarried downward to the fuel bed 6 and are subjected to considerable cracking, the effect /of such oil introduction is to decrease the specific gravity of the gas while increasing the capacity of the apparatus.

It will be obvious to those skilled in the art that while the steam employed during this period is preferably introduced through the connection 52,

forward-air-blast period of the next cycle to ac- 1.50

complish a final steam uprun period and preferably also an air purge period.

5. Final steam uprun period The reversing valve 23 being placed in the uprun position in which it is shown in Fig. 1, the valves 53 and 55 being closed, and the valve 51 open, steam is admitted at the base of the generator and passes upward through the generator fuel bed 6, the carbureting space 8, conduit 12 and superheater 2 as in the previous initial steam uprun period, the resultant Water gas passing through the tar batter 3 into the gas offtake 24. As soon as suilicient steam has been admitted in this manner to insure that no water gas remains in the base of the generator 1, this period may be discontinued, being followed by an air purge period.

6. Air purge period .During this brief period the stack valve 16 is kept closed, the reversing valve 27 being held in the uprun position, so that the water gas remaining in the set is driven by the air blast into the tar batter 3 and passes through the gas oiftake 24.

As there can be no sharp line of division between the water gas and the air-blast gas, it

will be obvious that the length of this period is determined largely by considerations of thermal value and inerts in the finished gas.

In general, as soon as the set is clear of water gas, as determined by experimentation in the usual manner, the stack valve 16 is opened and the forward-air-blast period of the next cycle immediately proceeds.

While it will be obvious to those skilled in the art that the actual quantities of air, steam and oil and the length of the various periods of the cycle will depend upon factors varying from set to set and from plant to plant, nevertheless the following summary of operating conditions in one actual installation will be of value as illustrative of the practice of my present invention. These gures are based upon actual operation of a standard carbureted-water-gas set having a 4nine-foot generator and equipped with connections for reverse-air-blast and backrun steam,

but not in this instance provided with the reverseair-blast oiftake located at an intermediate point ot the fuel bed, as shown at 60 and 61 in Fig. 1 o! the drawings.

1.-Forwardairblast: *s

Primary air 60 seconds at 9500 cu. ft. per

minute Secondary air 52 seconds at 2300 cu. ft. per

minute 2.-Reverse-air-blast:

(a) Blow run 4 seconds at 5500 cu. ft. of air per minute (b) Reverse-air-blast to stack 35 seconds at 6000 cu. ft. of air per minute (c) Blow run 6 seconds at 5500 cu. ft. of air per minute 3.--Initi'al steam uprun:

65 seconds at 145# of steam per minute L`i.--Steam backrun:

60 seconds at 135# of steam per minute 5.-Final steam uprun:

23 seconds at 145# of steam per minute 6.-Purge: Sv

5 seconds at 8200 cu. ft. of air per minute.

While the above figures represent an actual operating instance and are believed to be relevant as disclosing to a considerable extent the actual ,u nature of a satisfactory cycle, they are not to be taken as necessarily indicative of the best results obtainable by means of my process or as establishing a fixed rule for the operation of other apparatus under different conditions, as will readily be appreciated by those skilled in the art.

In any event the cycle employed differs materially from a cycle which would be satisfactory when using gas oil for carbureting purposes in the same apparatus, this difference residing prin- 9i cipally in the manner of introduction of the heavy oil and the extent and duration of the reverseair-blast period as well as in the disposition oi' the resultant gases. Whereas in the manufacture of carbureted water gas from gas oil the use of reverse-air-blast has hitherto been necessarily confined to a very brief blow run period of, for example, 8 seconds, with a forward-airblast period of 105 seconds, in the present instance, a reverse-air-blast period of, for example, 45 seconds and a forward-air-blast of only 60 seconds may be employed. v

In the present instance, I prefer to employ a reverse-air-blast equal in amount to from onetenth to one-half of the total air requirement of the process, depending principally upon the nature of the heavy oil used. The greater portion or all of the reverse-air-blast gases thus produced are discharged to the atmosphere or delivered to waste heat recovery apparatus. In general, the total air requirement of the process (which includes both forwardand reverseair' blasting, and both primary and secondary air) will not differ materially from the air-blast requirement of the conventional carbureted watergas process of the past, in which gasoil was used for carbureting purposes and about 30 to 40 cu. ft. of air per pound of steam were employed.

By reason of the fact that the amount of reverse-air-blast according to my process constitutesy a large portion of the total air-blasting or blow period, it will be obvious that where the reverse-air-blast gases are removed through the ports 61 and the manifold connection 60, the airsteam ratio insofar as the lower portions of the fuel bed 6 are concerned may be considerably lower than that employed heretofore.

My experience has indicated that this does not always have a harmful effect upon generator fuel bed conditions, but where it is desired to main- 13@ tain the lower portion of the fuel bed at a high temperature and still retain the advantages of removing the reverse-air-blast gases at an intermediate level in the fuel bed, and especially where a self-clinkering grate device is employed, a suitable regenerator may be placed in the connection 18 contiguous to the base of the generator 1, as set forth and described in the copending application of Thomas W. Stone, Serial No. 225,881, filed October. 13, 1927 (Case No. 101).

Such a regenerator is effective to absorb heat from the downrun or backrun gases leaving the base of the generator and to transfer such heat ..50 to air or steam, or both, about to enter the gen'- i erator for upward passage through the fuel bed 6. Either the primary-air-blast alone or the uprun steam alone, or both. may be passed through this regenerator, which is thus particularly effective where a self-clinkerlng grate device is employed and there is no relatively large and cool regenerative ash zone at the bottom of the fuel bed 6.

As pointed out hereinabove, when fuel is charged into the generator, which ordinarily takes place during the steam backrun or downrun period, it is preferred to discharge the fuel in the manner shown in Fig. 2, so that carbon which may be deposited upon the side walls of the upper portion 8 of the generator 1 may to some extent at least be dislodged and removed.

Where the charging of fuel is done in this manner and is accomplished frequently, for example, during each cycle of operation, a considerable portion of the carbon may be removed from the walls of the generator in this manner, thus facilitating the maintenance of the upper portion of the generator in a relatively clean condition and assisting in the consumption of this carbon by means of the reverse-air-blast. Where, as in the present instance, all of the heavy oil is introduced into the generator, the reverse-airblast period may follow the steambackrun period in the cycle, as set forth and claimed in the aforesaid copending application of Koons and Merritt. v

It will be apparent from the above that my invention accomplishes the various objects set forth hereinabove, making it possible to manufacture carbureted water gas from heavy oil Without loss of capacity `and Wit-hexceptionally good oil and fuel economy, in apparatus of an exceedingly simple and compact nature while accomplishing numerous other advantages and avoiding disadvantages inherent in the methods and apparatus of the prior art. For these reasons the utility of my invention is exceedingly great.

It will furthermore be apparent to those skilled in the art that my invention is not limited to the details of the specific apparatus or methods set forth hereinabove by way of illustrative example, but is to be construed as of the scope of the claims hereinafter made.

I claim as my invention: K

1. The process of manufacturing water gas in an apparatus including a generator having a bed of solid fuel and a superposed carbureting chamber, which process consists in separately and successively passing air blasts and steam in opposite directions through said fuel bed, a portion of the blast in each direction being utilized for the purpose of driving residual gas resulting from a previous steam run into a collecting medium, admitting heavy oil into the carbureting chamber of said generator coincidently with the steam runs to enrich the made gas, and conducting said gas to said collecting medium, the major portion of the reverse air blast passing downwardly through the upper portion only of the fuel bed and thence being withdrawn circumferentially of the generator at a point below the top of said fuel bed, whereby the carbonaceous deposits on the fuel bed resultingl from the admission of said heavy oil are consumed.

2. The process of manufacturing water gas in an apparatus including a generator having an elongated carbureter chamber, a superheater and a tar batter, which process consists in alternately introducing an air blast and av steam run into the fuel bed of a gas generator, and admitting heavy oil circumferentially. into the `carbure'ting chamber of the generator simultaneously with the steam run to enrich the resulting gas, said air blast being introduced in a reverse direction into the combined generator and carbureter and downwardly through the upper portion only of the fuel bed to consume carbonaceous deposits resulting from the admission of said heavy oil, and withdrawing the .air blast from the combined generator and carbureter at a point below the top of the fuel bed.

3. The process of manufacturing carbureted water gas in an apparatus including a combined generator and carbureter, a superheater and tar batter, which`process consists in alternately introducing an air blast and a steam run into the fuel bed of the generator, and admitting' heavy oil into and circumferentially of the carbureter portion of the generator simultaneously with the steam run to enrich the resulting gas, said air blast being introduced in a reverse direction into the generator and downwardly through the upper portion only of the fuel bed to form air blast gas and tov consume carbonaceous deposits resulting from the admission of saidV heavy oil, and withdrawing the air blast from the generator circumferentially thereof at a point intermediate

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