US1307353A - And howell c - Google Patents

Description

1. B. GARNER AND H. c. COOPER. RECOVERY OF BUTPLNE AND PROPANE.

APPLICATION FILED AUG.5. 1916.

1,307,353. Y PatentedJune24, 1919.

3 SHEETS-SHEET l.

Q. :5 S m Q- F I E] E a k l E s 1 k\ WITNESSES INVEYNTORS APPLICATION FILED AUGHI I9I6v J. B. GARNER AND H. C. COOPER.

RECOVERY OF BUTANE' AND PROPANE.

m KEANE Po Au Q.

WITNESSES I. B. GARNER AND H. C. COOPER.

RECOVERY OF BL'TANE AND PROPANE.

; APPLICATION FILED AUG.5. 1916 1,307,353.

m mm QM 1T 11E 2 M s m; 6 hm 7 d H m p w t a P JAMES B. GEEK, '01 PITTSBURGH, PENNSYLVANIA, HOWELL C. COOPER, 0F =URG, WEST VIRGINIA, ASSIGNOBS TO HOPE NATURAL GAS COMPANY, OF

PITTSBURGH, IENNSYLVANIA, A GORPOEATION OF WEST VIRGINIA.

RECOVERY OF BUTAI'I' E AND PROPANE.

Specification of Letters ream. Patented June 24, 1919.

Application filed August 8', 1916. Serial No. 113,800.

To all whom it may concern: I

Be it known that we, JAMES B. GARNER,

residing at Pittsburgh, county of Allegheny,-

and State of Pennsylvania, and Hownnr. C. COOPER, residing at Olarksburg, in the county of Harrison and State of West Virginia, both citizens of the United States, have invented or discovered certain new and useful Improvements in the Recovery of Butane and Propane, of which improveto be constituents, in varying proportions,

of natural gas and of oil also. They are gases under normal atmospheric conditions of. pressure and temperature. Aside from their existence in such hydrocarbon mixtures of natural origin, there is, to the best of our knowledge, no other known-source of butane and propane, and such as have been commercially produced have been prepared synthetically. But although known to be constituents of hydrocarbon mixtures of natural origin, their. separation from such mixtures has not heretofore been accomplished commercially. However, if obtained economically on a commercial scale, each substance has great commercial value as a liquefied homogeneous combustible gas suitable, for example, for heating, for cutting and welding metals, and for internal combustion engines.

For various reasons it is essential that a liquefied hydrocarbon gas for such purposes be homogeneous. In the first place, for

shipment it must, of course, be placed in pressure fl asks, and it is necessary, in fact it is a requisite for interstate shipment, to

know the pressure to which such filled flasks may, under different temperatures, be sub jected. If the liquid be not a homogeneous substance, the pressure which it Wlll exert on its flask or container cannot, because of varying partial pressures, be predicted. In-

the second place, if the liquid gas be not'jai-i. homogeneous substance, that 18 to say, 1f--1t' be a mixture of various hydrocarbons, the

first gas used from a filled flask will include in its mixture a larger percentage of the lighter and more volatile h drocarbons than will the gas last used. onsequently, the heating value or B. T. U. of the gas from a single flask will vary as the flask'is emptied,

the gas first used having a lower B. T. U. than that last used; the amount of oxygen required to be mixed with the'gas will vary; and a burner, jet or carburetor suitable for the first portion of the gas delivered from the container will be unsuitable for the last portion delivered therefrom.

In the course of our experimentation we have endeavored in Vain to separate these components from natural gas containing them, by subjecting the gas directly to the normal operation of fractional condensation: that is to say, by gradually increasing pressure, to condense one component after another, as the point of liquefaction of the several components is successively attained. For reasons not certainly known butane and propane cannot be thus separately recovered.

In an application for United States Letters Patent filed by us on June 8th, 1916. Serial No. 102,489, we have described a pro cess of obtaining gasolene from natural gas consisting in certain improvements upon the process for that purpose described and claimed in United States Letters Patent No. 989,927 to George M. Saybolt, one of the purposes of the said improvements being the more efl'ectiv-e separation from the normal liquid product of the said. Saybolt process, of the so-called lighter combustible constituents of the gas. In the practice of the present invention we prefer to employ the appa ratus shown in the drawings of our sald pending application, and it is therefore illustrated in Figures 1 and 2 of the accom-- panying drawings. Fig. 3 shows a form of apparatus which we prefer to employ for the performance of the last steps of our present invention. It will be understood however that other forms ofapparatus may I tensed/it desired, and that shown may also cooler 3, and. by pipe 6 into the lower ab sorber 4 of a pair of obsorbers 4 and 5. The

portion of pipe 6 'within the absorber fl is perforated, as indicated, so that the compressed gas is made to bubble up through a body Of absorbent menstruumas will presently be described. The gas which is unabsorbed by the menstruum in the absorber 4 is caught in a perforate pipe or header 7, and thence passes through a pipe 8 to a perforate pipe 9* near the bottom of the absorber 5, and thence'flows through absorbent menstru-um contained in this absorber. The remaining unabsorbed gas is caught in a perforate, pipe or header 10 and flows out through the pipe 11 to the gas line.

The absorbent menstruum is made to flow through the absorbers in a direction opposite to that of the flow. of the gas. The menstruum enters the absorber 5 through the pipe 12, andfas viewed in Fig. l, flows from right to left to a pipe 13 leading downwardly into the left end of the absorber 4,

through which it flows from left to right to a pipe 14. Suitable partitions or dams l5,

' 16 are provided in the absorbers in order to suflicient weight to overcome all permissible.

maintain therein a body of menstruum of suitable depth:

As is stated in the. S'aybolt patent above referred to various l-iquids may be used as an absorbent menstruui'n; We prefer to usehowever a petroleum hydrocarbon having an initial Baum gravityof from 28 to 55, at 60Fahrenheit. Then the apparatus is operated as thus far explained, under conditions of pressure and temperature Well understood by those skilled in the art, the result is the absorption in the menstruum con tained in the absorbers 4 and 5 ofpvapors which are contained in the natural gas and which. when condensed constitute what is commerically known as gasolene, together with certain other lighter hydrocarbons, in varying quantities dependent upon conditions of operation, which are gaseous at at mospheric pressure and temperature, and which include butane and propane.

From rthe absorber-4 the menstruum, now

enriched by the hydrocarbons which it has been caused to absorb from the natural gas,

' flows through the pipe 14 into the primary still, consisting of the upper retort 17 and the lower retort 18, which maybe heated to the desired degree in any suitable way, but preferably by means, of the steam pipes to be presentl described. In the apparatus illustrated,'t epressure of the absorbers is maintained in the still, and in order to prevent gas from flowing from the absorber 4 into the retort 17 or the vapor from the retort 17 flowing into the absorber 4, a trap 19 is formed in the pipe 14, the vertical length of each leg of which is 'such as to. provide a column of the liquid enriched menstruum of or likely difference in pressure between the absorber 4 and the retort 17.

In the top of the retort 17 is a perforate pipe or header 20, through which the enriched menstruum is condicted from' the pipe 14 and. from which it flows over the steam pipes within the retort. .From the :bottom of the retort 17 the mefistruum flows through a pipe 21 into the bottom of the retort 18,

through which retort it flows, in a devious,

path determinedbythe bafiie plates 22, to the discharge pipe 23. In the apparatus shown a supply of hot water or'steam is taken from the heater 24 (Fig. 2) and flows through a pipe 25 into the retort 18, and from thence through a pipe 26 into the pipes in retort 17, and thence outthrough an escape pipe 27.

The function of the retorts 17 and 18 is to distil off from the enriched menstruum preferably only lighter constituents which have been absorbed from the gas, and which are gaseous at atmospheric pressure and temperature. Hence the temperature maintained in these retorts is comparatively low, say from 95 to 110 F. And the pressure, as already stated, approximates the pressure in the absorbers, so that those hydrocarbons which have been absorbed from the gas,

which are liquid at atmospheric temperature and pressure shall remain for the most part still contained in the enriched menstruum.

The lighter hydrocarbons which are'distilled out of the enriched'menstruumv in the retorts l7 and 18 pass from the retort 18 through the pipe 32 into the retort 17 and thence all of such distilled hydrocarbons ,pass out of the retort 17 through the pipe 30;or in the alternative the hydrocarbonvapors in the retort 18 may l:pass out through the pipe 31 into pipe 30. rom the plpe 30 these lighter gaseous hydrocarbons may pass directly through the pipe 58 into the line 11; or, as described in our application referred to; they "may be pumped by the pump 34 in the pipe 33 through a cooler 35 and liquefied products be deposited in receptacle 36, while still uncondensed vapors may pass through the pipe 37 to the line 11. Or the apparatus may be operated under such conditions bf pressure and temperature, as is well understood in the art, that the vapors in the pipe 11E recovery of propane and the primary distillation. Referring now to Fig. 2, the menstruum (still containing the e hydrocarbons and usually still some of the lighter hydrocarbons) passes from the bottom of the retort 18 through the pipe 23, which is provided with a pressure reducing valve 45, into the heat exchanger 43, whence it passes through the pipe 46 into the still 38. Within the heat exchanger 43 there is arranged a pipe system into which flows from the still 38 through the pipe 44 the hot denuded menstruum, which serves to heat the enriched menstruum flowing through the exchanger 43 on its way to the still 38. The lower part of the still 38 is provided with suitable pipes adapted to be heated by steam flowing from the header 39 at one end of the still to a similar header 40 at the other end thereof, these headers being provided with suitable steam connections. However steam may be admitted'directIyto the still 38 through the jets 41 connected to a steam supply pipe 42..

llithin the still.38 there are arranged suitable baffles 54 to cause the menstruum to flow in a devious path from one end to the other.

Because of the reduced pressure and the increase of temperature of the enriched menstruum in the heat exchanger 43, some ofthe contained hydrocarbons may be volatilized, and in order not to interfere with the distillation in the still 38 it is desirable that these vapors be drawn off through a trap I The conditions of temperature and pressure within the still 38 are such as to effect the distillation from the enriched menstruum of its absorbed gasolene content, usually however together with certain quantities of gaseous propane and butane. The distilled vapors pass out from the still 38 through thepipe 49 (which may be provided I with a suitable steam ejector 51) into the condensing coils 50, from which "the liquid product flows through'the pipe 53 into the closedstorage tanks 52, 52. The water, if any, and the 'gasolene, will be separated in'the storage tanks, and each may be drawn off separately as desired or found necessary. The pressure in the still 38, condenser coils 50, and tanks 52 and 52 may be maintained below a desired maximum by the use of a suitable relief valve placed in a tap 79 con.- nected to the pipe 59 leading from the tops of the storage tanks.

The still uncondensed vapors (namely butane and propane) in the storage tanks 52, 52, pass out through the pipe 59. In order to insure the attaining of a substantially pure mixture of gaseous butane and propane uncontaminated by any heavier hydrocarbon vapors, we preferably pass the uncondensed gases in the pipe 59 through a supplemental absorber or absorbers, wherein any pentane or other heavier hydrocarbon remaining in vapor formin the uncondensed gas will be absorbed, and a substantially pure mixture of butane and propane will be obtained for further treatment. To this end we have shown the pipe 59 connected by pipes 60 and 61 with the bottoms of a pair of absorbers and'56, which are adapted to contain amenstruum capable of absorbing .any of these heavier hydrocarbons. This menstruum will preferably be what is commercially known as sun spirits, a liquid hydrocarbon of the paraffin series having at F. a Baum gravity of about 337. The

filtration "will conveniently be carried on under normal atmospheric conditions of pressure and temperature. It may if preferred be carried on at a pressure greater than atmospheric, but less of course than the liquefaction pressure of butane. The sub division of the gas under treatment such as to cause it to bubble up through the menstruum in a finely divided state, and so to come into more intimate contact with the menstruum and to be more thoroughly cleansed and purified, will be accomplished according tothe well recognized principles of that operation. Connections are shown in the drawings whereby the gaseous substances in the pipe 59 may be caused to flow through the absorbers 55 and 56, either in series or in parallel, but such connections and the appliances connected therewith are well understood and need not be herein describedin detail.

From the tops of the absorbers 55 and 56 i the unabsorbed gases, now. substantially a treated is introduced in increasing quantities'and with increasing pressure.

We continue to pump into this compression-chamber quantities of the gas to be reduced until, in consequence of increasing pressure, a liquefaction has taken place. The occurrence of such liquefaction may be detected by opening from time to time one and another of the pet cocks 70 with which and through this inlet the mixture to be the compression chamber 69 is equipped at collects at the lower end of compression chamber 69, whence it is drawn off by gravity, through a valve-controlled duct 71, to a suitable storage tank 72. The inlet pipe 68 will meanwhile preferably have been closed. Thus a fractional condensation is achieved upon a natural-gas derivative which has been essayed in vain upon the gas itself.

WVhen the butane in liquid condition has been so drawn off there remains in compression-chamber 69 a body of substantially pure propane in gaseous form. The further operation involves compression of the propane to the point of liquefaction; this may e accomplished in any desired manner, and we shall here describe the means We have actually used, though other means manifestly may be employed. WVater impelled by pressure is introduced at the lower end of compression-chamber 69 through a suitable connecting pipe 73, and this entering column of water is forced in, mounting up in chamber 69 and compressing the propane at the upper end of the chamber, until (under unmodified temperature conditions) a pressure upon the gas of about 650 pounds to the square inch is attained. At this point the propane liquefies (a change which, again,

v, Pressure wise). lVhen the propane has been so liquefied a duct 74 is opened, and through-it the liquid propane is driven by the mounting column; of water, through a cooler 75, if need be, to a storage tank 76. As the column of water mounts in the chamber 69, driving liquid propane before it, the height of its rise may be detected at the pet-cocks,and when it is detected at pet-cock 7O at the upper end of the pressure-chamber, the impelling pressure is cutoff and duct 74 is closed. The storage tanks 72 and 76 may then be detached; valves may then be opened, the pressure-chamber drained, fresh storage tanks supplied, and the apparatus will thus be made ready for repetition of the operation now described. 77 is apressure-gage which we have found convenient to employ to assist and facilitate our work. gages maybe used elsewhere, if desired.

Our work in the premises (as has been intimated above) has had to do with a natural-gas derivative in which the butane. and propane components are, in terms'of weight, present in substantially equal quantities. It is conceivable (though the fact lies beyond'the range of our experimenta tion) that, given a gas in which these components are present in distinctly unequal proportions, some variation may be found in pursuing our method in the critical pressure required to condense and separate the butane component from the propane. While we have in the ensuing claims defined our invention according to the specific pressures which, under existing conditions, we have found correct, we recognize as within the scope of our invention and mean to include within the meaning of our claims such departures from the figures given, in this matter of critical pressure, as, in the case of compounds of other proportions, experience may find requisite. Of course, if for any reason it is found desirable to operate at temperatures other than substantially normal atmospheric, the critical pressures will vary accordingly, and We mean to include in the scope of our Letters Patent pressures equivalent to the pressures given proper allowance being made for substantial departures from normal atmospheric tem- 95 perature. I

We have described our invention as having to do with natural gas, and, more specifically, with certain refined derivatives of natural gas. It will be understood that mixtures of butane and propane may be detunes, from whatever particular source derived.

We claim as our-invention:

1. The method hereirLdescri'bed of recovering butane from petroleum and' natural gas and derivatives thereof which consists in isolating a substantially pure mixture of butane and propane alone and then subjecting such mixture to fractional condensation.

2. The method herein described of recovering butane and propane separately and each in liquid form which consists in isolating a substantially pure mixture of butane,

and propane alone, forcing the mixture into a suitable chamber until the condensation ing a substantially pure mixture of the butane and propane alone, and then separating said mixture of butane and propane into its constituent elements. i

- 4. The process of recovering butane from a gaseous mixture of butane, propane and other hydrocarbons, Which consists of subjecting such mixture to an absorbing menstruum and by the aid thereof absorblng the butane and propane, distilling said menstruum for the removal therefrom of butane andpropa'ne, subjecting the distillate to a substance capable of absorbing from the distillate the hydrocarbons heavier than butane, and separating therem'aining substantially pure mixture of butane andpropane into its constituent elements.

5.. The process of treating a gaseous mixture of butane, propane and hydrocarbons heavier than butane, which consists of subjecting such mixture to a liquid hydrocarbon of about 33.7 B-aum gravity and by theaid of said liquid absorbing said heavier hydrocarbons, and then separating the remaining gaseous mixture of propane and butane into.

distillation the butane and propane com ponents; third, in filtering the distillate through a naphtha-absorbing substance;

and, finally, separating the butane from the propane by fractional condensation.

In testimony whereof we have hereunto set our hands.

JAMES B. GARNER. HOWELL o. oooPER.

Witnesses:

BAYARD H. CHRIsTY, V FRANCIS J. ToMAssoN.

Images