US2705193A - Conversion of liquid hydrocarbons to fixed gases - Google Patents

Description

March 29, 1955 C, BAFRANCls 2,705,193

CONVERSION OF LIQUID HYDRCARBONS T0 FIXED GASES Filed may 12. 195o 2 shets-sneet 1 gw/gauw@ afm( lMarch 29, 1955 l c. B. FRANCIS 2,705,193 CONVERSON 0F LIQUID HYDROCARBONS T0 FIXED GASES Filed May 12. 195o 2 Sheets-Sheet 2 United States Patent O CONVERSION F LIQUID HYDROCARBUNS T0 FIXED GASES Charles B. Francis, Pittsburgh, Pa. Application May 12, 1950, Serial No. 161,559 4 Claims. (Cl. 48-215) This invention relates to a method of converting liquid and liqueable carbonaceous fuels to fixed gases. The term fixed gases includes any mixture of compounds and elements that remain in the gaseous state at ordinary atmospheric temperatures and pressures. Such mixtures may be entirely consumed as fuels directly, or may be processed to obtain certain substances which may be used for other purposes.

More particularly, the invention relates to the conversion into ixed gases of such carbonaceous liquids as coal tar and soft pitch, which are now largely consumed as liquid fuels, and hydrocarbon oils, such as crude petroleum, and the residues resulting from the high temperature processing thereof, which residues have heretofore been used mainly as liquid fuels in certain types of furnaces and processes operating at high temperatures. In addition to the named liquids, the process is also adapted to the conversion to fixed gases of certain animal and vegetable oils, and to the conversion to fixed gases of many waste products, such as used automobile oils, discarded wash oils, etc.

The advantages of a fixed gaseous fuel, such as natural gas, for use in certain industrial processes, as well as for household use, are well known. In many districts natural gas is not available. In other districts, which are supplied with natural or manufactured gas, shortages are often experienced.

It is an object of the present invention to supply these deficiencies with a fuel gas of high heating value-a fuel gas manufactured from any carbonaceous liquid available, including such waste products as those mentioned.

Most large steel producers make coke, and in the process great quantities of coal tar and/or soft pitch are produced and used as fuel. But the use of tar as fuel is restricted to certain furnaces, such as open hearths, that operate at high temperatures. The tar or pitch is viscous and costly to handle, particularly in cold weather. such viscous materials are generally produced at a distance from the points of consumption and must be transported in tank cars or trucks to such points.

A further object of the present invention is to provide a process whereby the tar or pitch may be economically converted at the point of production or origin into a sulfur-free fixed gas, and then delivered in gas lines (many of which are already in existence) to the points of consumption.

Fixed gases suitable for use as gaseous fuels have for many years been produced from petroleum residues. These gases are commonly designated as oil gas. In general, oil gas Varies in composition and heating value about as follows:

Range in Typical Analyses, Per- Oil Gas Constituents Percent By cent By Volume ot 3 Volume specimens Methane, CH4 27.6 to 43.2. 27. 6 43. 2 30. 0 Etnie, (32H5, and Propane 0.0 to 6.4...- 0. O 6.4 1.0

3 8. Eltbhylene, 02H4 and other ole- 3.5 to 17.0... 3. 5 17. 0 26.0

ns. Acetylene, 02H4 0.0 to 0.5.... 0. 0 0.5 1.1 Hydrogen, H2 50.8 to 23.2.- 50.8 23. 2 9. 4 Carbon monoxide, OO 10.2 to 3.6- 10. 2 3. 6 2. 7 Carbon dioxide, CO 2.6 to 1.1-... 2. 6 1.1 3.0 Oxygen, Oz 0.2 to 1.0-. 0. 2 1.0 2.8 Nitrogen and otheri rt gases.. 5.1 to 4.0. 5.1 4. 0 25.0 Total B. t. u. per cu. it 548 to 975.-.- 548 975 1, 030

Also,

Still a further object of the present invention is to control the heating value of a fixed gas, produced from the materials indicated, at any desired value between 500 and 1000 B. t. u. per cu. ft., and to produce a clean vapor free gas having a heating value practically constant, so that burners may be adjusted and combustion accurately controlled over any desired period of time. Also, an object is to provide for the control of the specific gravity of the gas produced in those instances when desired.

With the exception of those processes that employ the principle of partial combustion of the oil with air or oxygen, and those using nickel catalysts (which are poisoned by the sulfur in mineral oils), practically all of the processes used heretofore for converting liquid hydrocarbons into fixed gases are intermittent in operation, requiring the use of a set of two producer units, these units consisting essentially of two or more checker chambers of brick, into one of which oil and steam are injected while the other is being heated to restore its temperature and eliminate carbon depositions. Such intermittent operation is very inetcient for reasons which this specification need not become involved.

Another object of the invention is to provide a coutinuous process that may be conducted in a single unit or producer, whereby gas may be produced continuously from a given fuel oil, and at a controlled rate over long periods of time.

Still other objects will be apparent in the following specification.

In the accompanying drawings, apparatus is illustrated, in the operation of which the invention is realized, the apparatus selected in this case being a small unit, designed to convert about 15 gal. of oil per hour into about 4,000 cu. ft. of gas, having a heating value of from 500 B. t. u. to 600 B. t. u. per cu. ft.:

Fig. l is a diagrammatic view,

illustrating the apparatus in longitudinal, vertical section;

Fig. 3 is another view in horizontal section of the generator unit, as seen on the plane III-III of Fig. 1;

Fig. 4 is still another view in horizontal section of the generator unit, as seen on the plane IV-IV of Fig. 1;

Fig. 5 is a view in vertical section of a pressure-regulating electrical switch included in the apparatus for automatically controlling the generation of gas according to the rate at which it is consumed; and

Fig. 6 is a developed view or layout of a vaporizer or boiler included in the apparatus.

Referring to the drawings, the apparatus comprises a gas generator unit 1, a gas-scrubbing or purifying unit 2, and a gas receiver tank 3. The tank 3 is not essential t0 the process, and may be varied in design and size. Indeed, it may comprise merely an enlargement in the gas main, or it may comprise a gas storage tank of any capacity desired. The gas-scrubbing and purifying unit 2 is essential only in the event it is desired to cool the gas, or to free it from oil and water vapors, and/or sulfur compounds.

The generator unit 1 comprises a catalyst chamber 5, constructed of heat-resistant metal, typically chromenickel-molybdenum alloy steel. This chamber contains a porous catalyst body 6 formed of hard hematite, crushed and graded in lumps or pieces from 1/2" to 3%1 in size. The catalyst chamber is arranged Within a heating charnber 7. In the smaller sizes of gas generators it may be practical to supply the necessary heat in chamber 7 by means of electrical resistors, but in the illustrated unit, as well as in units of larger size, the heat is preferably supplied by burning oil and/or gas. In the present case a combination oil-gas burner 8 s mounted on the generator body at or near the zone of the section plane II-II in Fig. l, and is of the construction shown in Fig. 2. The burner llame parallel to a Wall of the combusfor the products of combustion opens through the top of the generator. In starting with the generator cold, this burner is operated on a light fuel oil injected with air under super-atmospheric pressure, until the generator is producing gas, at which time the oil is turned off and the generator is heated by a small portion of the gas generated, delivered to the burner through a line 9 leading from the gas delivery line 463 of the apparatus.

The walls of heating chamber 7 are formed of steel plate 11, lined with refractory material. A storage box 12 is located on top of the catalyst chamber 5 and holds enough of the sized hematite to till the catalyst chamber. At the bottom of the generator a catalyst-receiving box 13, formed of ordinary carbon steel, is provided.

A thermo-electric pyrometer 14 projects into the combustion chamber, and, when the generator is making gas, this pyrometer (in conjunction with conventional control devices, not shown) automatically controls the flow of gas to the burner, to maintain the temperature at any desired point within the Working range of 1500" F. to l700 F., as revealed by an indicator 140.

Such control devices are well-known in the art and it is needless to an understanding of the present invention to illustrate them, or to describe their operation in detail herein. Within the generator means are provided to produce superheated steam, which is a gaseous oxidizing agent, for use in the production of fixed gas. Such means may comprise a boiler formed of four pairs of vertical tubes 21, 21a, 2lb, and 21C (Figs. 3 and 6), that are preferably embedded in the refractory lining of the combustion chamber, and lie within the anges of steel channels 22 .that support or reinforce the steel walls 11 of the chamber 7. The two tubes of each pair are interconnected by tubes 21d adjacent their lower ends and by tubes 21e adjacent their upper ends, and the four pairs of tubes are inter-connected in series adjacent their upper ends by means of pipes 21f. Water is supplied by a line 15 to an overhead tank 16 which includes a iioat-valve 17 for maintaining the water in the tank at desired hydrostatic head. Water from tank 16 is delivered bv way of a pipe 18 to the bottom of boiler tubes 21-21f, the rate of iiow being measured by iiow meter 19 and regulated by valve 20; and the steam generated in such tubes is delivered by way of a pipe 23 to a manifold 24 that encompasses and is welded to the heat-conducting wall of catalyst chamber 5, in the position shown in Fig. l. In its flow in tube 23 and manifold 24 the steam is highly superheated for the chemical reactions presently to be considered. Pet cocks 51 and S2 are connected at suitable points to the boiler tubes for testing. The described arrangement of tubes provides a boiler that utilizes, for the generation of steam, heat which would otherwise be lost by radiation from the walls of the generator.

From the manifold 24 steam, superheated to the temperature of the hot gases in combustion chamber 7, is jetted through orifices 2S into the catalyst chamber 5.

Oil is injected into the porous catalyst body by means of a motor-driven pump 26 that draws oil through line 27 from a conventional storage tank (not shown) which may be located below oor level and heated. ln the case of very viscous fuel oils or other carbonaceous liquids that may be used for the production of ixed gas, the products of combustion in chamber 7 may be employed to preheat such liquids. As one example of the Way this may be done, a pipe coil 300 is shown at the top of the combustion chamber, and the viscous liquid may be passed through this pipe, whereby the viscosity of the liquid is lowered and the temperature raised` The liquid fuel, drawn through pipe 27 from the supply, is forced through a ow meter 28` and feed line 30 to an injector pipe 29 located at an intermediate zone in the catalyst chamber, as shown. The pipe 29, otherwise closed at its inner end, is provided with a small (/32" to IAM) hole positioned in its wall to direct a jet of oil downwardly. The injector pipe 29 is connected to the oil feed line by a union 31, and extends through a heat resistant shield tube 32, which projects through and is welded to the wall of the catalyst chamber 5. It is important that the jet of oil be directed downwardly through a small orifice. I have found that an injector tube with open end or large delivery orifice soon becomes clogged with carbon. It is further important that the steam shall be injected or shall be eifective below the point or points of admitting the oil to the catalyst.

The motor 260 that drives the pump 26 is started by closing a switch 33. Thereafter, the operation of the pump and its motor is controlled by the pressure of the gas in tank 3, through the instrumentality of a special pressure regulating electrical switch 34, later described in detail. By means of said switch 34, which maybe set to respond to a pressure between one-half lb. and two lbs. in tank 3, the energizing circuit of the pump motor 260 is interrupted when the pressure in tank 3 reaches that at which said pressure-regulating switch is set. The circuit is reclosed when the pressure in the tank drops below that at which such switch is set. In this way the generation of gas is automatically controlled and adjusted to the rate at which the gas is used, up to'the maximum capacity of the generator. The tioat-valve in tank 16 and the valve 20 control the ilow of water 4to the generator, and these valves, in conjunction with the gaspressure-controlled oil pump 26, provide for accurate proportioning of the oil and water iiow to the generator. Other devices may be designed or may exist for accomplishing the same results, but they are more costly and less reliable than the device 34. For example, if a water pump and an oil pump were driven by a single motor ythat stops the ow of both oil and water at the same time, the results would be imperfect, since the ow of the water should be maintained for several minutes after the oil is shut off, to prevent the formation of coke carbon, and to permit the regeneration of the catalyst in chamber 5.

In preparing the apparatus for service, the catalyst chamber 5 and storage box 12 are lled with the crushed and sized hard hematite, and gasketed covers 35 and 35a are securely bolted in place over the charging openings in the top of storage box 12. The generator is gradually heated to a temperature of l650 F., as shown by the indicator 140.

While the generator is being heated, the gas scrubbing and purifying units are preparedA `for use. The scrubbing and purifying units include a cooler and scrubber unit 36, an oil separator 37, a sulfur remover 45 (employed only where the removal of sulfur is needed), and an oil scrubber 46. The scrubber 36 and the oil separator 37 are charged with cold water by opening a valve 38 in a pipe leading from the water supply line 15.

The scrubber 36 comprises a vertical steel tank, having a pipe 360 extending from a point midway of its vertical extent downwardly to the oil separator 37, which also comprises a vertical tank, arranged at lower level than tank 36. When the rising level of the water in tank 36 reaches the mouth of pipe 360, water ows through such pipe into the oil separator 37, and when the level of the water rising in the oil separator reaches the point where it appears in a sight gage 39, the water inlet valve 38 is closed. Next, if sulfur-free gas is desired, a few pounds of slaked lime are introduced through cover 40 of a sealed container 42, the lime being placed and supported upon a perforate partition or screen 41. The cover 40 is then sealed in place on the top of container 42, and a valve 43 is opened to admit water from supply line 15. The water rises through the body of lime on screen 41 until its level reaches the opening of a pipe 420 leading from container 42 to the .top of the sulfur remover 45.

The sulfur remover 45 comprises a vertical tank having a water-overflow pipe 450 leading into the oil separator tank 37. As the water rising in tank 45 reaches the mouth of pipe 450, it overows through the latter pipe into the oil separator tank 37, with the effect ,that the level of the water in sight gage 39 begins to rise. At this time the valve 43 is adjusted in a position which (in the case of the 5000 C. F. H. apparatus herein illustrated) reduces the low to about one quart per minute. The rate of ow is determined by opening valve 44 in a line 440 leading from the bottom of the oil separator 37 and measuring the water delivered. The valve 43 is manipulated until it reaches the position at which the ow through pipe 440 reaches the desired rate. The water running from pipe 440 may be led to a drain line, sewer, or other convenient point of disposal. When the desired flow of water has thus been established through the lime container 42, the tank 45, the tank 37, and drain line 440, the valve 38 is reopened and adjusted in such position that the total ow of water from drain line 440 equals about one gallon per minute when the water is at 40 F., or one and one-half gallons per minute when it is at 65 F. The level of the water is thus established at operating levels in scrubber 36, sulfur remover 45, time container 42, and oil separator 37. Then, the positions in which the valves 38 and 43 have been adjusted are marked and the valves closed.

aromas The oil scrubber 46 is now made ready. The oil scrubber consists in a vertical tank having two horizontal partitions 460 and 461, as shown. The chamber 470 above partition 460 includes a bubbler cap 67, whose lower edge is notched, as shown. The cap 67 seats over the upper end of a tube 68 which extends downwardly through the partition 460 to a bubbler cap 69 at the bottom of the tank. In preparing the oil scrubber for service, light oil (such as No. 1 or No. 2 fuel oil) is introduced to the upper chamber 47 by way of a funnel inlet 48 including a valve 480. From the chamber 47 the oil runs into chamber 470 by way of -a by-pass 490 that includes a valve 49. The oil rises in chamber 470 to the level at which it overflows the upper edge of tube 68, whence it falls .through such tube to the bottom of tank 46, where it forms a body of oil that envelopes the bubbler cap 69. When adequate pools of oil have thus been formed around the bubbler caps 67 and 69, the valve 49 is closed and the chamber 47 is filled, whereupon the pouring of oil into the funnel 48 is discontinued and the valve 480 closed. Next, the valve 49 is opened, and is adjusted in such position that the oil ows through by-pass 490 at a rate of about sixty drops per minute, asmay be checked by means of a sight-glass 50 included in the bypass. A vent tube 471 opens through the partition 461 and extends almost to the top of chamber 47. The oil is fed at the rate of about sixty drops per minute as long as the generator remains in operation.

While the scrubbing and purifying units are being brought into service condition as described above, the ring of the combustion chamber is continued, until the temperature therein reaches 800 F. or 900 F. Then, the pet cock 51 and valve 20 are opened, admitting water into the boiler 21-21f. When water flows from said pet cock, the pet cock and valve 20 are closed and pet cock 52 opened. Pet cock 52 remains open until the temperature in the combustion chamber 7 reaches 1650" F., at which time pet cock 52 is closed, and valve 20 is adjusted to provide for a ow of water at a volumetric rate equal to one-half that of the oil delivered by pump 26 for conversion to gas.

In the particular case of the generator illustrated and described herein the water ow may be at a rate of one pint per minute. Next, any excess water in the scrubbers is displaced and the apparatus tested for leaks, by admit- `ting compressed air into line 57 through an inlet 570 until the pressure in tank 3 rises to two lbs. The specied ow of cooling and scrubbing water is then established by opening and adjusting valves 38, 43 and 44, the

valves 38 and 43 being opened at the marked positions o already determined for the required flow.

To start the production of gas, main delivery valve 53 is opened, switch 33 is closed to start the oil pump, and valve 54 is opened until the ow meter 28 indicates the ow of oil desired-one quart per minute for the illustrated generator. Gas is formed at once and soon displaces all the air in the apparatus. With the catalyst chamber filled with freshly prepared hematite, the gas is high in CO2 and N2 for the first five to ten minutes, and this gas may be wasted by temporarily closing valve 53 and opening pet cock 530. The gas released through pet cock 530 may be burned. After about ten minutes the pet cock 530 is closed and main delivery valve 53 is opened, allowing the gas to flow to the desired points of consumption.

The conversion of the oil to gas is effected within a fraction of second by a series of physical and chemical reactions. For example, when No. 2 fuel oil is injected (as at 29) into the hot hematite it is rst volatilized and then decomposed by the process known as cracking to lighter or more volatile compounds and carbon. The carbon is no sooner formed than it reacts either with the ore or the superheated steam injected (as at 25) to form CO gas or CO and H2 gas according to the following type reactions:

Reaction a occurs only when the catalyst is new. fThe surfaces of the pieces of hematite (FezOa) that form the catalyst are soon reduced to magnette (Fes04) whereupon only reaction b can occur, such reaction b taking place only on the surfaces of the pieces of ore. These changes and reactions give a mixture of fixed gases composed of CO and H2, plus vapors composed of water and light oils. As these mixtures ascend through the hot ore body above, some of the light oils undergo, while passing through super-heated tubes 55 and 55a, a pyrolysis which results mainly in the formation of unsaturated hydrocarbons known as olens, while others of the light oils react with the ore and water to form CH4, H2 and CO. If the gas is not cooled quickly, the oletins tend to polymerize, forming aromatic compounds and H2. Furthermore, if the generator is operated at maximum capacity, and particularly at temperatures near 1500 F., a little oil vapor escapes unchanged with the gas passing through the super-heater tubes 55 and 55a at a high velocity.

In chamber 5 the gases, together with some water and oil vapors, leave the ore body at a temperature between 1300 F. and 1500 F., and pass through a duct 57 into the cooler and scrubber 36. At the top of this scrubber cold water, entering a manifold 58, is sprayed through orifices 580 into the gas, thereby cooling it. The gas flows downwardly through a tube 59 into a distributing or bubbler cap 60, from the bottom of which the gas rises and bubbles through a colum 600 of water extending to a height slightly above the bottom edge of the mouth of overow pipe 360. By this scrubbing action, most of the water and oil vapors are condensed, and, the oil in globule form escapes with the cooling water through the overllow 360. In this scrubber 36 some sulfur and other water-soluble compounds are separated from the gas. The temperature of the overflow water from this scrubber is kept below 120 F. If the temperature rises above this value the flow of water is increased by adjusting valve 38. If, in order to keep the temperature of the water down to desired value, the ow is increased to a rate at which the water level rises above the gage glass 62, drain valve 63 at the bottom of the scrubber is opened until the water reaches the normal level, whereupon valve 63 is closed and the flow through valve 44 re-adjusted. Cleanliness of the gas is tested by opening a pet cock 64 provided at the top of scrubber 36. The escaping gas is ignited and a flame kept burning with a long candle-like llame.

The gas leaving the scrubber 36 at a temperature of from 100 F. to 120 F. carries with it some entrained water and oil, some fog, and part of the sulfur in the gas developed in the generator, mainly in the form of HzS-an acidic gas. To remove these impurities the gas is passed through a second scrubber 45, which is practically a duplicate of the iirst scrubber, but somewhat smaller in size. As the gas enters this scrubber by way of a duct 361 it is scrubbed with dilute lime water obtained from tank 42, the lime water being introduced through a spray nozzle 65 at the top of a downtake tube 66. At the bottom of the scrubber, the gas is forced through a submerged bubbler cap 61, and as the gas temperature is now well below F. both oil and water vapors are condensed. The lime water also removes HzS and some of the other acidic gases present, such as CO2. The lime water may be very dilute, as water having a hydrogen ion concentration of pH 8 is effective in removing 90% of the H2S in the gas, assuming of course that sufficient lime water is supplied.

The gas produced from certain oils contains some organic compounds of high molecular weight in molecular suspension which are not removed by scrubbing the gas with water or aqueous solutions. To remove these gumlike compounds, the gas is passed from scrubber 45 through a duct 451 into the double oil scrubber 46. In this scrubber the gas is forced to bubble downwardly through a body of light oil in chamber 470, whence it enters bubbler cap 67, forming a spray which is carried with the gas down a tube 68 and into the second bubbler cap 69. The gas bubbles upwardly through the body of oil in the bottom of the scrubber 46, thereby separating the spray from the gas. In this way practically all of the organic compounds carried in suspension by the gas are left behind dissolved in the oil, which, as the process continues, rises in the scrubber and overflows through pipe 462 into the oil-separating tank 37. In this tank the ow of liquids is very slow, with the water being removed from the bottom by means of line 440, as already v84 that passes through noted. The oils, all having a density less than that of water, rise to the surface of the water in tank 37, and, by maintaining the water level in the tank well above the water outlet the oils accumulate in the upper half of the chamber, whence they are drawn off periodically through a line 59 controlled by a valve 590. The oil removed through line 59 is returned to the oil supply tank for reintroduction to the generator. The process provides for practically 100% conversion of oil to gas.

The clean gas, rising from the bottom of scrubber 46, flows by way of a pipe 463 into the receiver tank 3, whence it is delivered to the points of consumption under the control of valve 53.

From the preceding description it is apparent that the operation of the generator and gas cooling and purification units is practically automatic as long as the rates of ow of water and oil, as adjusted at the start of the run, are maintained. However, the amount of gas that can be usefully consumed by either industrial or domestic users varies, not only from day to day but also for different periods in each day, wherefore it is highly desirable to produce gas only as fast as it can be profitably or usefully consumed. Since the proportion of oil and water injected into the generator may vary without affecting the process, that is, as long as a certain minimum proportion of water is delivered, the rate of gas production may be varied by adjusting the oil injected. When the gas consumption for several hours is constant and can be anticipated, a rough adjustment of the rate of iiow of water and oil can be made by means of the ow meters provided, but such adjustment does not provide for the small unavoidable variations in the volume of gas consumed in relation to the volume produced.

It is desirable that the gas be supplied at a constant gage pressure, which for most commercial uses varies from one-half lb. to two lbs. per square inch.

To meet this requirement, a particularly effective pressureregulating electrical switch has been devised, the switch being shown attached to gas tank 3 in Fig. l. A vertical section through the center of the switch is shown on larger scale in Fig. 5.

The switch 34 comprises a thick-walled glass U-tube 74. The tube is of 1/z" internal diameter, and is 21/2 long. measured from the inside of the bend in thc U. One leg of the U-tube is longer than the other, and includes a 90 bend at its upper end, which is equipped with a rubber collar 75 sealed and clamped in an orifice formed in the side wall of tank 3, as indicated in Fig. l. The tube is supported and protected by a steel guard 76, secured to the wall of tank 3. The longer leg of the U is calibrated in centimeters and millimeters from a line TA6 above the bend for a distance of 5 centimeters. Clean mercury is placed in the tube to the level indicated at 90 in Fig. 5, which is the level of the 25 mm. graduation on the wall of the tube.

At the top of the shorter leg of the U, a set of electric contacts 77 and 81 is provided. The contact 77 comprises a ring formed of copper or brass tubing having a diameter slightly larger than the outside diameter of the U-tube. The upper edge of the ring is swedged and ground to form a flat seat, and the body of the ring is slit longitudinally. A rubber sleeve 78 is cemented to the inner surface of the ring; an electric conductor wire 770 is solderedvto the ring; and a clamp 79 secures the ring assembly in desired vertical position upon the shorter leg of the U-tube. A float 80 formed of glass tubing of l0 mm. outside diameter, closed at its lower end, tits loosely within the open end of the shorter leg of the U-tube. The length of the oat 80 is not less than 11/2, and the otherwise open end of the float is necked-n and closed by means of a stopper S3 of electric insulating material.

The contact 81 comprises a ring of light gage copper tubing, having its upper end closed by means of copper disk 82 soldered to the edge of the ring. The contact member 81 is secured to the float by means of a screw the end wall 82 into the body of the stopper 83. The screw 84 provides the terminal post for uniting an electrical conductor 810 to the contact member 81. The contact member 81 normally bears at its lower edge upon the seat formed on the upper edge of contact ring 77, as shown in Fig. 5. Positionedover the assembled contact members is a protecting hood 85 formed of insulating material, or of metal lined with insulating material. As long as the pressure in tank 3 remains below that desired, the oat 80 remains stationary,

with the copper rings 77 and 81 in Contact, closing through conductors 8,10 and 770 that are connected to switch 33 the electric energizing circuit of the oil pump motor 260. lf there is a drop in quantity of gas consumed in service the pressure in tank 3 is increased, pushing the mercury level in the long arm of the U-tube downwardly and raising the mercury level under the oat. The tioat rises with the mercury and breaks the circuit to the oil pump motor 260, thus interrupting the ow of oil until such time as more gas is consumed and the pressure in the tank'3 decreased. This control is well adapted to the process, since the generator continues to produce some gas for several minutes after the oil is shut off, and makes gas immediately when the ow of oil into the generator is reinstated. This lag, or the gradual decrease in the generation of gas after the oil has been shut off, increases the intervals between the stopping and the starting of the motor. lt will be manifest that, by adjusting the vertical position at which the contact assembly 77-85 is clamped on the shorter leg of the U-tube, the apparatus may be made automatically responsive to any selected delivery pressure.

The composition, specific gravity, and heating value of the. gas produced vary somewhat according to the type of oil used, and the temperature at which the generator is operated. With a well-condition catalyst in the generator operating at a temperature of l500 F., the gas will have a specific gravity of about 0.7, and a heating value of about 950 B. t. u. per cu. ft. a heating value greater than hydrogen, or carbon monoxide, or mixtures thereof. With the generator operated at 1600" F. to 16,50o F., the gas will contain a higher percentage of Hz and CO, which will lower the heating value of the gas, but will increase the volume of gas produced from a given amount of oil. Again, by introducing air through valve 570 the heating value of the gas may be lowered to any value desired, while the specific gravity and the quantity of gas produced will be correspondingly increased, due to the formation of CO and dilution with N2. ln general, the volume of gas produced from a given volume of oil varies from cu. ft. to 250 cu. ft. per gallon of oil, according to the type of oil used, and the heating value of the gas produced.

With certain oils that give high residues on distillation, such as No. 6 or Bunker C oil, it is advisable to inject a little air continuously through line 57, which flows upwardly from box 13, to prevent the formation of coke in the bottom of the generator. With oils which give little or no residue, it is necessary to introduce only enough air in box 13 to equal the gas pressure in the generator, and this will prevent water and oil vapors from flowing through the body of the catalyst 6 into the box 13.

lf vapors are permitted to enter box 13 they will condense, creating a partial vacuum that promotes a continuation of the undesired fiow.

As already mentioned, the iron ore in acts as a catalyst to prevent the formation of carbon, and is largelyr self-regenerating, provided 'that an excess of steam (or a little air) is employed, and the temperature of the ore is maintained above l300 F. in all parts of the chamber 5. On the other hand, if the temperature is increased above 1700 F. the oxide on the surface of the pieces of ore may bc reduced to metallic iron which will cause the lumps to stick together, or sinter, particularly if too much air is added with a high residue oil. The latter situation is avoided by limiting the operating temperature in the combustion chamber. The temperature of the ore, which is a poor conductor of heat and is being continuously cooled by the injected oil, is held to a value between 1500" F. and 1550 F. at the top of the catalyst chamber, and to a still lower value below the point at which the oil is injected. At a temperature below l400 F. the ore will not react with carbon, and the oil will not be cracked sufficiently to form fixed gases. Ditiiculty from these causes is avoided by forming the catalyst chamber with its walls flaring upwardly, as shown, and by preheating the injected steam to a vtemperature near that prevailing in the combustion chamber. In operating at the higher temperatures and using a high sulfur oil, the ore tends to absorb some sulfur, forming FeS on the surface of the lumps, but this sulfide isreconverted to oxide by reaction with the air or Water at the high operating temperatures.

As a precaution against all factors that tend to decrease the effectiveness of' the iron oxide catalyst, provision 1s the chamber 5 made for moving the ore through the catalyst chamber j,

from the storage chamber 12 at the top of the generator to the box 13 at the bottom. This movement is obtained by a pusher 70, which is moved back and forth through a distance of 2" to 3 by oscillating a lever 72. Each stroke of the lever pushes three to four lbs. of ore into the box 13. Eight to ten strokes of the pusher each hour is suicient.

The air introduced through pipe 57 to the box 13 tends to keep the vapors from ilowing downwardly from the catalyst chamber, and serves to regenerate or reactivate the catalyst delivered into the box 13, whereby such catalyst may be re-used.

In the use of fuel oils giving little or no residue, movement of the ore appears to be unnecessary, especially if catalyst-regenerating air is injected by way of box 13 to the bottom of chamber from time to time.

Regarding the overall eiiiciency of the generator; the reactions taking place in th'e catalyst chamber are both exothermic and endothermic, with the latter slightly overbalancing the former. The chief source of heat absorption in the catalyst chamber is that required to vaporize the oil injected, which, added to the heat absorbed by the chemical reactions, amounts to about 600 B. t. u. per pound of oil injected. The other heat losses are the sensible heat in the gases formed and in the products of combustion that escape through the ue 73. ln large installations the latter may be used to preheat the oil as it is pumped to the generator, and the loss from radiation may be reduced to a minimum by insulating the combustion chamber. Thus, the overall efficiency, by which term is meant the total heating value of the oil used as compared with the total heating value of the gas delivered, ranges from about 80% for the small generator described herein to 85% and higher for larger units.

It will be perceived that the method of my invention involves not only the physical and chemical changes known as cracking, and those changes knownl as pyr0lysis, but also involves certain chemical reactions among the components of the carbonaceous liquid, the ore, and the water and/or oxygen of the air used. Such carbonaceous liquids as fuel oils derived from petroleum are composed mainly of residues from distillation and cracking processes that are repeated until the residue will no longer yield a lighter hydrocarbon of value. a mixture of such heat-stable liquids is injected into my catalyst chamber heated to a temperature above l450 the initial action is that of vaporizing the oil.. This physical change is instantly followed by a chemical action, in which1 the hydrocarbon molecules are first broken down by reaction with oxygen derived from the oxide catalyst. Thisreaction is primarily limited to the oxygenA available on the surfaces of the catalyst mass, and it mag be said that in some surface areas of the pieces forming catalyst mass the oxide is reduced from a higher to a lower oxide, with possibly the formation of a slightY amount of metal. With the decomposition of hydrant carbon molecules thus initiated, there immediately follows a cracking reaction, in which molecules of smaller molecular weights are formed with the usual deposition `of carbon. This carbon is converted to CO by reaction with the oxygen supplied by the catalyst, or to CO and H2 by reaction with the water vapor or steam supplied. Finally, the hydrocarbons having molecular weights above ethane and butane undergo a pyrolysis or decomposition without deposition of carbon, and unsaturated hydrocarbons known as olens are formed.

In the absence of an oxidizing gas, such as water va por, the catalyst oxide would soon be reduced to the point where it becomes inactive, but with water injected in the form of superheated steam as described, the lower oxide on the surfaces of the lumps is oxidized to a higher oxide (and such slight quantity of metal as exists is oxidized), and the water is reduced to H2. All of these reactions proceed to equilibrium, which depends upon the temperature and the proportion of water vapor or steam injected.

The catalyst will be understood to be formed of a substance which yields or promotes the release of oxygen for breaking down heat-stable hydrocarbons as described above. In the presence of heat and such an oxidizing gas as steam, the substance of the catalyst is at least partially converted or restored from a lower to a higher oxide. Hard hematite, or its equivalents set forth l0 in my copending application for patent, below noted, comprises such a catalyst.

Although hard hematite is preferred as the substance or material of which to form the catalyst, other oxides of metals having a valency of at least two, such as manganese dioxide, nickel oxide, and chromic, cobaltic, molybdic, and tungstic oxides, may serve. For example, I have produced gas using manganese dioxide as a catalyst, but I found the reduced oxide is a powder which either clogs the generator or is carried over with the gas, making an extra step necessary to clean the gas of this dust. Likewise, the other oxides mentioned present certain diculties in operation, all of which are avoided by the use of hematite. However, as those skilled in the chemical art will know, the diiiiculties referred to may be overcome by reinforcing, pelletizing, or capsulating the catalytic substance within walls or coatings of a suitably pervious substance.

By virtue of the invention herein disclosed a clean fixed gaseous fuel, including at least one hydrocarbon gas, is produced. The gas developed in the generator is=not only cleansed of water and oil vapors in the scrubber 36, but the gas is cooled below the temperature at which the hydrocarbon gas polymerizes or decomposes under the effect of heat alone. And as already described in detail the units 45 and 46 cleanse the generated gas of acidic and gum-like organic inclusions.

In certain of the appended claims the terms oxidizing gas and gaseous oxidizing agent appear, and from the context of the foregoing specification these terms will be understood to cover water vapor or steam or air, or a mixture of water vapor or steam with air or oxygen.

Within the intent of the appended claims various modications and variations in the method described may be practiced within the skills of the experts in the art, without departing from the spirit of the invention.

Notice is given of my divisional application Serial No. 210,005, filed February 8, 1951.

I claim:

1. The method of producing fuel gases from liquidl carbonaceous hydrocarbon mixtures, which comprises the steps of subjecting the liquid to a cracking process by injecting it at a controlled rate and at a fixed point centrally located in a particulate body of hard hematite maintained at a temperature above 1450 deg. F. and subsequently subjecting the products of the said cracking process to the action of gaseous oxidizing agents simultaneously injected into the body of hematite at points down stream from the point of injection of the carbonaceous liquid, thereby producing a combustible mixture of iixed gases having a higher heating value than that of hydrogen, carbon monoxide and mixtures thereof.

The method of producing fuel gases from liquid carbonaceous hydrocarbon mixtures, which comprises the steps of subjecting the liquid to a cracking process by injecting it at a controlled rate and at a fixed point centrally located in a particulate body of hard hematite maintained at a temperature above 1450 deg. F. and

subsequently subjecting the products of the said cracking process to the action of gaseous oxidizing agents simultaneously injected into the body of hematite atpoints down stream from the point of injection of the carbonaceous liquid, thereby producing a combustible mixture of xed gases having a higher heating value than that of hydrogen, carbon monoxide and mixtures thereof, delivering the gaseous mixture under superatmosf plieric pressure into a pipe line, and regulating the rateof injecting said carbonaceous liquid into said catalytic body in accordance with variations in the line pressure of the mixture. j

73. The method of producing fuel gases from liquid carbonaceous mixtures, which comprises the steps of subjecting the carbonaceous liquid to a cracking process, by injecting the liquid at a controlled rate and at a fixed point centrally located in a particulate body of hard hematite maintained at a temperature above 1450 deg. F. and subsequently subjecting the volatile poducts of the cracking process toa pyrolysis by simultaneously injecting superheated steam at points located at the periphery ofthe body of hematite and down stream from the point of injecting the carbonaceous liquid, thereby producing a combustible mixture of fixed gases having a heating value higher than that of hydrogen carbon monoxide and mixtures thereof.

4. The method of producing a combustible mixture of xed gases having a higher heating value than hydrogen, or carbon monoxide, or mixtures thereof, from a carbonaceous liquid, which method comprises subjecting such liquid to contact with a catalyst composed of a porous body of iron ore heated to a temperature at least above the decomposition point of liquid hydrocarbons, thereby producing hydrocarbon gases and vapors and carbonaceous residue, and introducing superheated steam to said porous body at points below the region where said carbonaceous liquid contacts the catalyst and subjecting the products thus formed to the action of superheated steam owing through the interstices of the ore body in the same direction as the volatile products formed from the carbonaceous liquid, thereby converting the hydrocarbon vapors to xed gases and the carbonaceous residue, under the combined ett'ect of said steam and said catalyst, to hydrogen and the oxides of carbon.

References Cited in the le of this patent UNITED STATES PATENTS 1,902,004 Whitlock Mar, 21, 1933 12 Grumble et a1. Feb. 27, 1934 Huettner et al. Apr. 28, 1936 Johnson June 2, 1936 Nonhebel et al. Aug. 17, 1937 West Oct. 20, 1942 Rollman et al. Jan. 26, 1943 Steinwedell Dec. 7, 1943 Claffey Oct. 16, 1945 Cummings Aug. 1, 1950 Shaplegh Oct. 10, 1950 Shapleigh Oct. 10, 1950 Lewis Aug. 19, 1952 FOREIGN PATENTS Great Britain of 1905 OTHER REFERENCES Handbook of Chemistry and Physics, 27th ed., page 20 1703, Chemical Rubber Pub. Co., Cleveland, 1943.

Claims (1)

1. THE METHOD OF PRODUCING FUEL GASES FROM LIQUID CARBONACEOUS HYDROCARBON MIXTURES, WHICH COMPRISES THE STEPS OF SUBJECTING THE LIQUID TO A CRACKING PROCESS BY INJECTING IT AT A CONTROLLED RATE AND AT A FIXED POINT CENTRALLY LOCATED IN A PARTICULATE BODY OF HARD HEMATITE MAINTAINED AT A TEMPERATURE ABOVE 1450 DEG. F AND SUBSEQUENTLY SUBJECTING THE PRODUCTS OF THE SAID CRACKING PROCESS TO THE ACTION OF GASEOUS OXIDIZING AGENTS SIMULTANEOUSLY INJECTED INTO THE BODY OF JEMATITE AT POINTS DOWN STREAM FROM THE POINT OF INJECTION OF THE CARBONACEOUS LIQUID, THEREBY PRODUCING A COMBUSTIBLE MIXTURE OF FIXED GASES HAVING A HIGHER HEATING VALUE THAN THAT OF HYDROGEN, CARBON MONOXIDE AND MIXTURES THEREOF.

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