US2753700A - Method for using natural gas - Google Patents

Description

July 10, 1956 w o so 2,753,700

METHOD FOR USING NATURAL GAS Filed March 27, 1952 United States Patent Office 2,753,700 Patented J uly 10, 1956 assignments, to Constock Liquid Methane Corporation, New York, N. Y., a corporation of Delaware Application March 27, 1952, Serial No. 278,986

'1 Claim. (Cl. 62-170) My invention relates to an improvement in method and apparatus for using natural gas.

One object of my invention is to use gas discharged under natural high pressure from the well to do work whereby the pressure of the gas is reduced to a level appropriate for use as a fuel.

Another object of my invention is to use the gas well pressure to provide refrigeration or power or both while in no wise reducing the usefulness of the gas as a combustible fuel.

Natural gas is normally discharged from the well at pressures in the order of two or three thousand pounds per square inch gauge and at temperatures in the order of the temperature of the ambient air. Such pressure is so high that heretofore special means have been used in the nature of reducing valves and the like to bring the pressures down to a point at which the gas can safely be burned. This has resulted in loss of the power value in the high pressure gas and has required special provisions to avoid icing or excessive cooling in connection with such pressure reduction.

It is well known that when gas at high pressure, for instance from a pressure container, is allowed to escape and is discharged at atmospheric pressure, the reducing valve or passage through which the discharge takes place is reduced in temperature as a result of the expansion of the gas down to the lower temperature, and it is common in the oil fields to see the so-called Christmas tree the oil mans name for the valve into which the gas is discharged from the well, covered with ice because the ambient air lacks suificient heat-absorbing characteristics to overcome the chilling effect of expansion.

I propose to cause the high pressure gas to pass through a series of expanding coils where the gas will expand with resultant reduction in temperature. I propose to use such expansion coil as a cooling coil to cool a eutectic such as brine and the like, which eutectic will be circulated about the coils for cooling and then will be passed to a freezing apparatus wherein ice is formed, the expansion coils being in this case substituted for the usual expansion coil in a refrigerating machine.

The result of this arrangement is that the gas will expand under controlled conditions down to a point at which it may safely be supplied to a gas main or to a burner to be consumed and the gas so expanded and so cooled will at the same time cool a eutectic which can be used to provide refrigeration or to freeze ice.

In carrying on such an operation, a certain amount of power is required and I propose, therefore, to interpose between the source of gas under pressure and the expansion coils a gas turbine wherein the high pressure warm gas will be allowed to do enough work in driving the turbine wheel to generate the power needed.

The work done by the gas in the turbine and the expansion of the gas as it does this work will, of course, cool the gas and it is possible to provide a turbine which will discharge the exhaust gas at pressure low enough to admit it to the gas main. Preferably, however, the turbine will be so arranged that only a part of the pressure drop takes place in the turbine and the remainder of the pressure drop will take place in the expansion coil.

By this arrangement it is possible either to use the gas pressure solely for the purpose of refrigeration in which case the turbine will not be used at all ,or to use the gas entirely for the generation of power, in which the expansion coil will not be used at all, or to use the gas both to generate power and to give efrigeration.

While I have referred to a turbine, any expansion engine, be it rotary or reciprocating, can be used to generate power from the pressure of the gas and to reduce the pressure of the gas. In every case, work is done by the expanding gas, either in the turbine or in the expanding coil and such work is represented either by power generated, by manufacture of ice, or by refrigeration.

I propose, therefore, to convert a gas well pressure which is furnished by nature into a salable commodity, refrigeration, ice, or power. In any event, the use of the gas in a prime mover or in an expander in no way decreases the B. t. u. value of the gas as fuel and merely substitutes for wasteful methods of reducing the oil well pressure heretofore used.

My invention is illustrated more or less diagrammatically in the accompanying drawing.

Like parts are indicated by like charatcers throughout the specification and drawing.

1 is a gas well, gas being discharged therefrom through pipe 2 controlled by valve 3. Gas then passes through a pipe 4 to the intake side of a gas turbine 6, rotating the runner 7, after which the gas passes at lower pressure through a pipe 8 to the expansion coil 9 in a heat exchange tank 10, thence the gas is discharged to a gas main 11 leading to a burner or burners not here illustrated.

The turbine shaft 12 rotates with the runner 7 and drives a pump 13. Pump 13 circulates the eutectic, preferably brine, through a pipe 14 into the heat exchange tank 10, where the eutectic is cooled by heat exchange with the gas passing through the expansion coil 9. The cool eutectic then passes through the pipe 15 to the iceforming tank 16, details of which are not shown as they form no part of my invention. The eutectic after giving up its heat in the tank 16 for the formation of ice returns through the pipe 17 to the low pressure side of the pump 13.

If desired, the shaft 12 may also drive an electric generator 18 to generate electric power for any desired purpose. Under some circumstances, for example, the clutch 19 on the shaft 12 between the runner 7 and the pump 13 may be disengaged so that the turbine 6 furnishes power only to the generator 18. Under these circumstances the turbine would be so operated that substantially all the pressure drop would take place at the turbine and gas at usable combustion pressure would merely pass through the expansion coil 9 to the main. When it is desired to make ice again the electric load might be entirely cut off or at least reduced, and clutch 19 be connected and the eutectic would again be circulated. Under these circumstances, only a small pressure drop would take place in the turbine. 20 illustrates an electric motor which can also drive the pump 13 if it is desired to operate it to circulate the eutectic without relying upon the turbine. Under these circumstances, electric power to actuate the motor 20 could come from the generator 18 or from any other source, as desired.

I have shown just one diagrammatic arrangement which can carry out my invention. The turbo alone might be used to reduce the pressure of the gas, the work done by the turbine representing in its entirety the pressure drop from oil well pressure to gas main pressure or the expansion coil alone might be used, in which case the work done by the pressure drop from oil well pressure to gas main pressure will be represented entirely by ice formed or if the refrigerator coils instead of being in an ice machine were disposed in a refrigerator, then the work done would represent the refrigeration efiect.

I claim:

The method of using natural gas which consists in supplying the gas at well pressure and temperature to a prime mover where it expands and generates power with resultant decrease in pressure and temperature, expanding the gas discharged from the prime mover in an expansion zone with resultant further decrease in pressure and temperature, associating an eutectic, in heat exchange relationship and outof contact with the gas, in the expansion zone whereby the eutectic supplies heat to the gas and is cooled thereby, using the power generated by the prime mover to circulate the eutectic, in closed circuit, about the expansion zone and through a refrigeration zone and discharging the gas from the expansion zone for use at reduced pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,084,424 Booth et al June 22, 1937 2,313,681 Steedman Mar. 9, 1943 2,316,744 Mellet et a1 Apr. 13, 1943

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