US1339431A - Compression, storage, &c., of ethylene - Google Patents

Description

A. A. BACKHAUS. COMPRESSION, STORAGE, &c., 0F ETHYLENE.

APPLICATION FILED JUNE 6,1919. 1,339,431. Patented May 11, 1920.

2 SHEETS-SHEET I.

GWINVENTOR ATTORNEYS HAUS, residing at UNITED STATES PATENT OFFICE.

ARTHUR A. BACKH'AUS, or-mmmonn,

m ma, ASSIGNOR To U. s. INDUSTRIAL ALCOHOL COMPANY, OF-NEW YORK, N. Y., A CORPORATION OF WEST VIRGINIA.

,comrnnssron, s'ronAGE, m, or ETHYLENE.

Specification of Letters Patent.

Patented May 11, 1920.

Application lnea June 6,1919. Serial na-aoaaoe.

To all whom it may concern: I

Be it known.that'I,.AnrHUR A. BACK- land, have invented certain new and useful Improvements lilthe Compression, Storage,

&c., of Ethylene; and Ido hereby declare the following to be a full, clear, and exact description-of the invention, such as w1ll enable others skilled-in the art to which it' .appertains to make and use the same.

The presentinvention relates to improvements in the compression, storage, etc., of ethylene, whereby the ethylene, in large amount, can be' advantageously shipped and made available for use in a highly compressed state, blow-pipe: fuel, or for other purposes. 7'

Various combustible gases have heretofore been provided in containers under pressure for use in combustion processes, as in the production of a blowpipe flame for use in heating, welding, cutting, etc., or for other purposes. The-combustible gases which have been most commonlysupplied in this way have been hydrogen, Blau gas and acetylene. Hydrogen; can be readily compressed to a high degree, but it is de-l ficient in heating power and is of relatively little importance as afuel for commercial purposes.

Blaii gas issupplied' in special containers or cylinders in a liquefied state, 7 but its evaporation and use require special precautions, and are attended with certain well recognized disadvantages; The gas most commonly employed as a combustible gas,'an d supplied under pressure in con-.

tainers, is acetylene, and this gas, in spite of d the its objectionable characteristics, an compression, storage and use, prevails, at present, in the commercial field.

The danger incident to the manufacture, compression, storage and use of acetylene is well appreciated in the art. In order to make acetylene available at all for trans portation and use in a compressed state, va-

rious expedients ,must be resortedto, but

these have been only partially successful, and have served merely to reduce-and not to eliminate the inherent and constant menace and peril of spontaneous explosion,

Thus, in practice, the cylinders in which acetylene is compressed must be first completely filled with a porous material, and this material must be charged or soaked with ac'etone, orits equivalent, which serves .as

Baltimore, State of Marystored,

for example,- as' a upon its manufacture,

a solvent for the acetylene. The acetylene is then introduced and dissolved inthe sol-- vent. It is important for the cylinder to.

the solvent. The permissible pressure of the charged cylinder is limited to about 250 pounds per square inch at a temperature of about 7 0;F. Acetylene is well known to ,be explosive when in a compressed state and a rise intemperature and pressure of the cylinder and its contents due to exposure of the cylinder toa high temperature, will often bring about an explosion. The formation of explosive acetylids is'also a source of danger.

Further disadvantages incident to the compression, storage 'and supply of acety lene are the inevitable loss by evaporation of a part of the ace one solvent, which must be replacedwhent e cylinder is recharged; the presence of deleterious constituents,

such,- as phosphids, which may be present when acetylene "is obtained from carbid;

and the' instability of the acetylene which results in its decomposition when it is heatedto a high temperature during use. So also, particularly in extremely'cold weather, the lowering of temperature due to the evaporation of theacet lene and acetone may result in a partial reezing of the contents of thecylinder, so that the user is unable to obtain from the cylinder the same uantity of acetylene, as is obtainable there rom-in summer. Moreover, in some instances the user, 'unaware of the danger of the expodient, is tempted to Warm up the cylinder for the release of the residual acetylene, and

.is exposed to peril incident tothat procedure.

Furthermore, the protective filling and solvent, required in an acetylene cylinder, not only involve an additional expense in initial expense and in subsequent maintenance and replacement, but they materially increase the weight of the cylinder, so that the handling and transportation of both the charged and empty cylinders involves added effort and expense.

According to the present invention, the difficulties and objections referred to are avoided, and there is provided a compressed fuel gas, namely, compressed ethylene,

which can be compressed, stored, shipped and used without danger, and which, in addition, presents certain features of advantage over acetylene and the other available compressed fuel gases;

Chemically considered, ethylene is closely related to acetylene. Both. are unsaturated hydrocarbon gases containing two carbon atoms, and the only two such gases. They differ, chemically, only in their degree of unsaturation, z. 6., in the numberof hydrogen atoms which they contain, and, by hydrogenation, bothgases can be converted into the same saturated hydrocarbon, namely, ethane. It might, therefore, be expected that ethylene, because of its close chemical similarity to acetylene, would likewise require special precautions in its compression, storage and use, and be subject to like limitations.

I have found, however, that ethylene can A be directly compressed to a high pressure,

far in excess of that to which acetylene can be safely compressed, and that ethylene can be stored in cylinders or containers without theme of an absorbent filling and 'solvent, and ithout the danger and disadvantages incident to the compression and storage of acetylene. The entire space of the cylinder can, accordingly, be filled with the compressed ethylene. ,Moreover, since the ethylene is present in a gaseous, rather than a dissolved or liquid state, the entire content of the cylindefan be made available, .even in the cold est; weather, without objectionable lowering of temperature due 'to evaporation. I

I have made the further surprising dis- .covery'that the amount of ethylene which can be safely charged into a cylinder of standard construction is more than twice as great as the amount of hydrogen (likewise acombustible gas and a component of ethylene), or of oxygen (the common combustion-sup orting gas), which can be safelycharg d 'intoa cylinder ofthe same size and construction.

This important difference between ethyl ene and gases such as hydrogen and oxygen is further emphasized by the profound infiuence which the temperature of compression andecharging has upon the pressure required for the chargingpperation. Thus, if the limiting conditionof the cylinder is a pressure of about 2200 lbs. at a maximum temperature of about 50C. or 122 F., a cylinder, thecubical content of which is 1 cu. ft.,- will .contain about 288 cu. ft. of free ethylene, whereas this same amount of ethylene need only be compressed to a pressure of about 1320 lbs. (:per sq. inch abs.) if the temperature of the ethylene is lowered to about 203 C. I

In; the charging of cylinders with oxygen it is customary to charge the oxygen at or- ,in s, in which,

of about 2000 lbs. and at a temperature of about 203 and an increase in temperature up to about 50 0., will cause but a relatively small increase in pressure to about 2200 lbs, The amount of free oxygen so charged will be about 147 cu. ft. 'In the case of ethylene, however, if the cylinder were charged at the same temperature andpressure, the amount of ethylene will be about 360 cu. ft., and, if the temperature should increaseto 50 (3., the pressure would increase to about 3900. lbs.-far beyond the pressure for which the ordinary cylinder is constructed.

The compression of ethylene is accom panied bytheevolution of considerable heat,

and by a corresponding rise in temperature It is, therefore, important, in order to avoid too high temperatures and pressures, to. subject the ethylene to cooling during its compression, and thereby absorb and neutralize the heat of compression. This cooling is also of advantage in enabling a lower pressure to be used at the lower temperature, owing to the greater ease of. compression of ethylene at the lower temperatures, as above indicated.

The invention will be further described in connection with the. accompanying drawlgure 1 shows, in tional and diagrammatic manner, an arrangement of apparatus for compressing and cooling'the ethylene and charging it into the containers; and Fig. 2 shows a chart by means of which the proper charging pressure can be ascertained for any usual charging temperature.

In the apparatus of Fig. 1, the ethylene,"

from the generator or storage tank, is introduced through the .pipe 1 to the first cylinder 2 of a three stage compressor. The three cylinders of the three successive stages are indicated at 2, 6 and 10, respectively, and are each provided with a cooling jacket for absorbing. part of the heat of compression and thereby keeping down the tern perature of the compressed ethylene. From the three compression. cylinders the 'compressed ethylene passes through the three respective coolers or exchangers, where it is brought into indirect contact with water or other cooling agent, and its temperature is still further lowered. The connecting p'i 'es are indicated at 3, 5 7, 9 and 11.

rom the. last cooler 12, the com ressed and cooled ethylene passes through t e pipe 13 to the charging manifold 14, having branches with valves 16 and fiexlble pipe connections or pig-tails 17 through which the cylinders 15 may be charged.

Each cylinder is provided with the usual a somewhat convencommonly provided with 'spect, accordingly,

eth lene to be readily ascertained.

he'pressure to which the ethylene will require compression or to which it can be safely compressed, will vary with the temperature, as above stated. -The extent of this variation will be apparent'from Fig. 2, which is based upon observed figures. Assuming a maximum pressure of about 2200 lbs., at a maximum temperature of 50 (1. as the limiting conditions, the charging pressure for any lower temperature can be readily ascertained, inasmuch as the volume of the cylinder, and the number of cubic feet to be charged (about 288 cu. ft. of free ethylene at 20 C. and atmospheric pressure) will remain the same. At 163 C. this pressure will be only about 1050 lbs.; at 203 C., about 1350 lbs.; at 30.1 C., about 1630 lbs.; and at 10 0., about 1880 lbs. If the cylinder has a higher safe charging pressure, e. 9., about 3000 lbs., at a maximum temperature of 50 0., it will require a charging pressure of only about 1500 lbs. at 103 0., or about 1800 lbs. at 203 C. The correspondingly greaterease of compression, and the much less power required for the compression, at lower temperatures, will thus be apparent, as well as the profound effect of increase in temperature on. the pressure of the ethylene so charged. A very important economy in the power required for compression and charging of the ethylene will result from even a few degrees lowering of the temperature. Accordingly, by providing for the aftercooling of the compressed ethylene, and thereby reducing its temperature, it becomes possible not only to use less power for the compression,- but also to use a compressor of less expensive construction, thereby economizing both in the initial expense of the compressor and in the cost of its operation. With hydrogen and oxygen, there is no particular advantage to be gained by after-cooling of the compressed gases, inasmuch as the power. required is but slightly reduced bysuch after-cooling. In this reas well as in other respects elsewhere pointed out, the process of compression and charging of ethylene differs radically from that of hydrogen and oxygen. q

' hereas with hydrogen or oxygen the variations in pressure due to the variation in temperature commonly met with, are so small as to be within the margin of safety of the common metalcylinders, (which are safety devices that will be ruptured at excessive pressures, e. 9., about 400 lbs. in excess of the charging pressure for which the cylinders are tested) the variations in pressure with ethylene due is maintaine to like Variations in temperature are far inexcess of the safety limit.

It is accordingly necessary, with ethylene, to take precautions not required in the handling of these other gases. With the observation of these precautions, however,

and by proper cooling and regulation of I the charging temperature and pressure, it is nevertheless possible to charge the compressed ethylene, so that it can be safely stored, handled, transported andused, and

' so that it will, nevertheless, contain a far greater number of cubic feet of ethylene than a like cylinder would contain of other com bustible gases, such as hydrogen or acetylene. It is thus readily possible to charge more than one and a half or two times as much ethylene as hydrogen into a standard cylinder (about 1.54 cu. ft. capacity) at the same or a lower pressure, and such cylinders with their far larger amount of ethyl-' ene, can nevertheless be stored, handled, transported and used with substantially the same ease and safety as the ordinary hydrogen cylinders. That is, whereas acylinder having a cubical capacity of about .777 cubic foot is commonly called a 100 cubic foot hydrogen or oxygen cylinder, and a cylinder having a cubical capacity of'about=1.51 cubic feet is commonly called a 200 cubic foot hydrogen or oxygen cylinder; the amount of ethylene which can be safely charged into these same cylinders will be more than one and one-half times as much, and may amount to twice as much or even more. Expressed in terms, of cubic feet of ethylene per cubic foot of cylinder capacity, it is thus easily possible to charge more than 200 cubic feet of ethylene, and even more than 250 cubic feet of ethylene, per cubic foot of cylinder capacity, without danger, whereas, with hydrogen or oxygen the cylinders above referred to contain only about 130 cubic feet of hydrogen or oxygen per cubic foot of cylinder capacity. I

When the c linder of compressed ethylene at ordinary temperature, or it cooler temperatures,the pressure exerted y and the margin of safety of the cylinder correspondingly increased. Q

When in use, ethylene which a cylinder of compressed ethylene will contain, as compared .with cylinders of hydrogen or acetylene of like s ze, will enable the ethylene to be used for a change of cylinders.

the far larger amount of ders required to be purchased and kept on I hand can thus be radically reduced, with resulting saving in transportation charges, "and in initial expense of the cylinders.

\ Ethylene can be readily produced in a state of comparative I urlty, 7,. 6., containmg 95% or more ethy ene, and without the purity. Thus, for example, it may be obavailable quantities.

- free from absorbent tained by the liquefaction and fractional separation of oil gas or crackedoils or other gaseous mixtures 1n which it ls flpresent in I recommend, however, as the preferred source of the ethylene, obtaining it bythe catalytic dehydration of ethyl alcohol, employing, for example, alumina, clay or other like catalytic body at a suitable temperature. The ethylene may be produced ina continuous manner and supplied directly. to the compressor, or it may convenientlybe stored in a suitable holder and supplied to the compressor as re ui'red.

claim l 1. A' commercially transportable metal cylinder containing compressed ethylene which can,be safely stored, handled, shipped and used, said cylinder having its interior filler and solvent and containing the ethylene compressed to a high pressure, the amount of ethylene being more than one and one-half times of hydrogen in a cylinder of the same size under the same pressure; substantially as described.

2. A commercially transportable metal cylinder containing compressed ethylene which can be'safely stored, handled, shipped and used, said cylinder having its interior free from absorbent filler and solvent and containing the ethylene compressed to a high pressure; the amount of ethylene being more than 200"cubic feet of ethylene per cubic foot of cylinder capacity; substantially as .described. I v3. A commercially transportable metal" cylinder containing compressed ethylene which can be safely stored, handled, shipped and used, said cylinder having its interior free: from absorbent filler and solvent and containing the ethylene compressed to high pressure, the amount of ethylene beingmore than 250 cubic feet of ethylene percubic foot of cylinder capacity; substantially as described.

4. The method of compressing ethylene in cylinders, for storage, shipment and use,

which comprises. compressing the ethylene,

cooling the ethylene during compression and I thereby neutralizing the heat of compres sion and materially lowering the pressure the amount required, and charging the cooled com pressed ethylene under a regulated pressure and ina gaseous state into cylinders havin their interiors free from packing and so vent, the charging pressure being so regulated that the amount of ethylene charged into the cylinders will be more than one and one-half times the amount of hydrogen in cylinders of the same size under the same pressure; substantially as describe v 5. The method of compressing ethylene in cylinders for storage, shipment and use, which comprises subjecting the ethylene to progressively increased compression, cooling the ethylene during such progressive compression and thereby neutralizing the heat of compression, and materially lowering the pressure required, and cooled compressed ethylene at a temperature of about 20 C. to 40 C., and under a regulated pressure into cylinders havin their interiors free from packing and so vent, whereby the ethylene is contained in the cylinders in a compressed gaseous state, the charging pressure being so regulated that the amount of ethylene charged into the cylinders will be more than 250 cubic feet ture and pressure being so regulated that the amount of ethylene charged into the cylin ders will be more than one and one-half times the amount of hydrogen in cylinders of the same size under the same pressure; substantially as described.

7,. The method of compressing ethylene in cylinders for storage, shipment and use,

charging the which comprises compressing the ethylene,

cooling the ethylene both during and after compression and thereby neutralizing the compression and materially lowerheat of ing the pressure required, and charging the cooled compressed ethylene into cylinders having their interiors free from packing and solvent, the charging temperature and pressure being so regulated that the amount of ethylene charged into the cylinders will be more than one and one-half times the amount of hydrogen in cylinders ofthe same size under the same pressure; substantially as described.

In testimon whereof I aifix m si ature.

4 A THUR A. BAClhffA US.

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