US1747761A - Natural-gas liquefaction - Google Patents

Description

H. DUMARS Feb. 18, 1930.

NATURAL GAS LI QUEFACTI ON Filed Sept. 8. 1922 w E o k INVEN-TOR V HORHC'E DUMB/PS ATTORNEY v Patented Feb. 18, 1 930 UNITED s A'rEs PArENr: OFFICE HORACE DUMABS, OF NEW SUFFOLK, NEW YORK, ASSIGNOR, BY DIRECT AND MESNE TASSIGNMENTS,'OF TWO-THIRDS 'IO BOWEN -DUMALRS POWER CORPORATION, OF N EW YORK, M cunrz, or NEW ORK, n. Y.

N. '21,. A- CORPORATION OF NEW YORK, AND ONE-THIRD TO HERMANN I.

NATURAL-GAS IlI'QUErAc'rron Application filed September a, 1922. Serial No. 586,996.

itably used as a gas and under suitable conditions may be used in a double or treble aspect, namely, by utilizing the refrigereither or both respects make such attempts ating effect when it has reached its destination and the liquid is allowed to expand and return tq a gaseousstage, or partly in this manner and partly by using the gasified liquid under its. pressure created by gasifaction, in order to produce power.

6 In the research of many years and experience due to active work when air was first "liquefied commercially, and with much knowledge of the, many difficulties and intricate questions involved in the liquefaction of different gases, the present invention has been the discovery of the possibilities of utilizing all of the factors that are involved-in the character of natural gas, as well as the condition under which such gas is won from the ground. I

It is known that others have endeavored to compress naturaLgas and in so doinghave compressed the, gas, and by the increased pressure of the natural gas, the constituents, hydrocarbons making up natural gas, have been changed and the changes have been such that their deleterious content finds its way into the resultant liquid. This deleterious effect due to the compressionof natural gas is of various aspects, including the dissociation toa more or less extent, of the qualities of the gas, but also creating someextremely explosive chemical compound. which in commercially impractical or abortive for any practical use or after use ofthe gas, and more particularly preclude the possibilities of safe transport. The excessive pressure may in part, have the effect of cracking on the same generalprinciples as are involved in the now so-called cracking methods for thetreatment of natural oils. Y

My process aims toovercomeallofthe difficulties heretofore experienced or contemplated by those skilled 1n the art,f or the pur-;-

pose of making-possible the economical lique faction of natural gas audits transportation to market and to permit its economic utilization. a

I will now describe in detail a specific embodiment of my process which involves the following:

' I provide in reasonably close proximity to the natural gas Wells, apparatus which in its simplest form'may comprise what is known in the art as a temperature interchanger. In certain localities enormous supplies of natural gas are available at a rock pressure running over years uniformly at approximately 1000 pounds, and with the casing construction used and the safety equipment of the wells such gas is available at casing-head at a pressure which I establish for use in my apparatus through suitable connections at a fairly uniform pressure which may be any point between 300 to 1000 pounds. Associated with the temperature interchangcr I connect an expansion engine into which the natural gas passes at a predetermined pressure. This expansion engine isso designed that clearance relation to the volume of the cylinder permits the expansion of the gas from the predetermined established pressure to a predetermined pressure such as 60 pounds, which pressure is suflicient to carry away the natural gas into the piping at the plant and to the places of utilization locally whereit is required and is moved by the natural pressure.

In the expansion engine the drop, for example, from 300 to 60 pounds would reduce the temperature to something like 130 degrees, but I do not aim to realize this full drop in temperature'because the first expansion engine is intended to serve the purpose as hereinafter shown, to rotate the shaft actuating the piston in a second expansion engine. The exhaust from the first expansion engine passes through the heat interchanger through which there passes into a counter-current through an internal tube, a fresh quantum of natural gas moving-under the predetermined casing-head exit pressure of, say, 300 pounds, whichfresh quantum of gas is therefore reduced in temperature to something higher than the 130 degrees, but it is still maintained under its 300 pounds'press ure until its exit from this single interchanger, passing into a second expansion engine. This second expansion engine is made of greater volumethan -the first expansion engine and the clearance is proportioned so that the gas ontering at approximately 130 degrees, willbe expanded to zeropressure, and with such expansion, having this second engine properly dimensioned, the expansion drops the temperature with the drop in pressure, to the point of liquefaction of natural gas which is approximately -263. The dimensions are such it safely can be within the zone of liquid and safely pass the critical pointof liquefaction. Having to deal only with the as, which has previously been analyzed and o a reasonably constant and known quality at casinghead, there will be no other gases to liquefy within the reasonable range of temperatures for which the apparatus is designed to reduce temperature in the second stage, thereby keeping out of the liquid any other liquefied admixtures that mingle with or change the gharacter ofthe liquefied gas.

Between the casing-head and the first expansion engine there'are suitable straining tanks for the purpose of drying and clarifying the natural gas dependent upon the analysis of the gas at the particular casing-head when the process is being operated. This includes the separation of gasoline, or what is thought'desirable in order that it may be.

eliminated as a factor in the liquefaction step and also be eliminated from the gas delivered h at market from the liquid transported and expanded for use for refrigeration, power and fuel.

It will be noted that the first expansion engine passes thenatural gas without any excessive change in temperature and with a regulated outlet exhaust pressure, so ,that it may be utilized without any loss whatsoever, so that the first expansion step serves the purpose of what today are necessary expan- I sion valves required at the gas fields to reduce the pressure for commercial local use.

A diagrammatic illustration of one embodiment of my system is shown in the accompanying drawing, in which: v

Natural gas at high pressure, such as direct from wellhead, flows through the pipe 1, while a separate supply by a wellhead pressure flows through the pipe 2, each of these leading to opposite ends of a double-acting engine, as,for example, a Corliss engine comprising one cylinder 4, but in effect, for this purpose providing two cooperating expansion cylinder spaces or two effective expansion engines. The valves 5 and 6 cooperate in the usual manner whereby with one closed, as 6, after the admission of the high pressure gas from the well, and valve 7 opens, the gas previously admitted through 6,will expand and drive the piston 9, expelling the previously expanded gas on the other side out of.

the interchanger 13. This gas having expanded, its resultant adiabatic cooling rethe-valve 7 through the conduit or pipe 12 to sults in gas at a much reduced temperature passing through the interchanger, diagrammatically illustrated at 13, and thereby cools thequantum of'gas passing at high pressure from the well through pipe 1. The inter changer may be of any usual construction familiar to those in the art, as, for: example, indicated in Patents Nos. 749,040, January 5,

1904, or 1,074,103, September 30, 1913. This pre-cools the quantum of gas passing through the supply pipe 1 at predetermined wellhead pressure, so that their further expansion after passing through valve 6, and driving piston 9, results in a further adiabatic cooling, so that when the piston returns expelling the pre-cooled and further expanded gases out:

of valve 8, they pass into the trap 14 where the liquefied gases settle and are drawn off by the valve 17, and any surplu's'unliquefied gas passes through the overflow 15 and is led into storage or to pipe line, with any suitable valve control to meet the particular conditions in any one case; The engine used for expansion may have,as diagrammaticallyindicated, a piston rod 10 with suitable crosshead, connecting-rod and crank driving a suitable pulley for transmission of power, and with flywheel and any usual parts desired for proper transmission or absorption of power and control.

By my utilization of the controlled pressure emanating from the natural gas wells, I utilize a vast amount of natural energy which today goes to -waste absolute. The

utilization of this pressure by the control and interconnection of steps in my apparatus, converts this energy at no cost whatsoever-beyond the initial cost of the apparatus to serve the purpose of liquefying the gas to anextent of 50 per cent or less of the gas passing through the apparatus. The exact proper-- tion of the gas liquefied will depend upon the efliciency of the apparatus with respect to insulation and efficiency of the engines and uniformity of operation and other factors which will be evident to those skilled in the art of manufacture of apparatus.

In the entire process it will be seen that the progress is from higher to lower pressures and at no point is there any recompression, therefore eliminating entirely any question of compressing with the deleterious effects that have heretofore been found, and, furthermore, eliminating the cost of compression 1 or recompression which compression has heretofore been the underlying basis of the production of liquefied gases.

Having produced the liquid natural gas without any compression'b'eyond the natural condition at the well, and without any recompression, the resultant liquor does not have the prohibitive dangers'or changed qualities which have been found to preclude any commercial use of compressed natural gas, and therefore I provide suitable means of transport, such as tank cars, which will carry the liquid and deliver the same at market.

The transportation methods and the gasifica- ,tion with the refrigerating utilization at market, involve the physical and structural apparatus which may vary materially and will not therefore be specifically described in this particular application. a

It will be realized that modifications may be made, and under certain conditions similar results may be effected by variations in I the process and apparatus still containing the essential factors necessary for the results hereinbefore set forth. Under certain condi tions the equivalent of an expansion engine in one or both steps may be resorted to, but while many similar other essential conditions, a plurality of interchangers maybe used particularly when the expansion engines are not actuated in combination as hereinbefore' specifically set forth.

Essentially the process involves my discovery of the possibilities of utilizing the now almost entirely Wasted pressure energy of natural gas at the wells, and making it perform in a practical andcommercial way what heretofore has been the prime and essential cost factor in liquefaction of gases.

\Vhile not confining myself to the specific process and apparatus above described, what I claim and desire to secure, by Letters Pattent is:

.The process of liquefying natural gas as delivered at two points from the well, comprising admitting a portion of the gas at well temperature and pressure to anexpansion engine, thereby reducing the pressure and temperature of the gas, controlling the temperature and pressure to keep said gas from liquefying in said expansion engine, passing the cooled gasfrom said expansion device into heat-interchanging relation with the other portion of gas at well temperature and pressure, and admitting said second portion of pre-cooled gas to a second expansion engine, so designed as to expansive capacity to liquefy at least a portion of said "as. n In testimony whereof, I have signed my name to this application, this 7th day of September, 1922.

HORACE DUMARS.

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