US2537815A - Gas distribution method and apparatus - Google Patents

Description

Jan. 9, 1951 J, DETHEROW 2,537,815

GAS DISTRIBUTION METHOD AND APPARATUS Filed Feb 9, 1948 L/A 505 A 175 THE/917W IN V EN TOR.

A TTORNE Y.

Patented Jan. 9, 1951 UNITED .s TATTEJS PATENT OFFICE GAS DISTRIBUTION .METIHOD AND APPARATUS 3 Claims.

This invention relates generally to gas distributing systems, and more particularly to a novel method of operating "such systems, and to equipment for facilitating the novel operation of such systems.

The "invention is capable of use with distributing 'or dispensing systems which handle various types of vaporized gases, such as air, carbon dioxide, natural gas, etc, as well as with systems for storing gas in 'looth its liquid "and vapor phases and subsequentlydistributing the gas in vaporized form, the latter systems including the liquefied petroleum gases such :asbutane, propane, and any combination of butane-propane.

The "vaporized gas handled by such systems normally carries a small amount :oi "Water in vaporized form, and is'moved under relatively high pressure from -a'isource .of supply through :a cond-uit'to or near to a point of use, adjacent which point "it is fed through :a pressure reducer, or :a series of such reducers, in order toxdeliver it to gas using applances at the desired low pressure. During the reduction of "pressure in the pressure reducers, a rapid-expansion of the :gas occurs. This :rapid expansion, in accordance with the laws of physics, produceszan extreme drop in thetemperature of :the .:gas. This flow temperature causes condensation of the *water vapor contained in the gas, and prompt freezing of the condensate at :or near the :pressure reducer inlet. Such ice formation often-completely seals the inlet and consequentlycuts 'ofi it-he flow {of gas to the gas :using appliances. This stoppage of flow not :only causes extreme inconvenience, but .may oftentimes be very dangerous; The reason is that the "air or earth surrounding the pressure reducer is often :at a temperature above freezing, resulting .in the gradual thawing of the ice which has throttled the gas flow. When the .ice has melted sufiiciently, gas a'gai-nbeginsa-to .fiow through-the reducer and to the .gas using appliances. Unless the appliances were shut off during the gas flow stoppage, raw gas begins to escape :into the room or building in which the appliances are located. TIT-he gas accumulates and creates both .an eaplosionand fire hazard.

It is .the primary :obj ectlof this invention, .therehire, to provide .a gas-distributing system, and a method of operating it, which prevents the freezing of moisture-carried by the :gas when that moisture is condensed to .a liquid and subjected to .a temperature Well below the freezing temperature of Water.

It is another object ,of this invention to provide a methodof operating gas distributing and dispensing systems which includes the step of introducing into the gas, prior to its rapid expansion and consequent cooling, a sufiic'ient quantity of-a suitable anti-freeze vapor to prevent the freezing of moisture which is condensed from the gas by low operating temperatures at ornea-r the'po'i-nt of expansion. I

"It is another objectto provide an improved gas distributing system which includes a means of introducing anti-freeze vapor into the gas prior to its arrival at the pressure reducer, the quantity er anti-freeze vapor being sufiicient to prevent the freezing of moistureat the pressure reducer inlet, or at any point in the service line betweenthe point'of introduction of the antifreeze vapor and the point of use of the gas.

"It "is'an additional object to provide a device for connection into the gas transmission or service line of any gas distributing system currently in use or currently available, which will automatically introduce into :thegas flowing through the pipe a sufficient quantity of antifreeze vapor to -prevent the freezing of mosture contained in the 7 gas when such :moisture is 1 condensed to a liquid by cooling, and subjected to temperatures well below the freezingpoint :of water.

Both the :method and apparatus embraced by the invention will be more .:clearly understood when the .efollovving description is read in connecizion withithe accompanying drawingswhich are :includedqiorillustrative purposes only, and in which:

Figure :l is :a diagrammatic side elevation of :a liquefied petroleum :gas distributing system embodying the-invention; I

Figure ;2 is :an enlarged vertical sectionai view of a preferred .iorm of anti-freeze vapor introducing device included the Figure 1 system;

and

Figure F3 is a side elevation of :a portion of a natural gas distributing system embodying the invention, another form of anti-freeze vapor introducing device being shown in vertical section.

Referring particularly to Figure 1, the numeral 5 designates a pressure storage tank in which a zpfitroleumfgasisuch as butane or propane risfstored under its cum vapor pressure in hothiits liquid .and yaporphases. A suitable shut off valve -6 is installed in the upper end of the tank to :control or stop the fiow of vaporized gas through the pipe .l-ines and 8,, to the pressure reducer and regulator S. A-se-rvice pipe line deserves .tocarry the gas at reduced pressure from the reducer -9 to gas using appliances such as stoves, gas :enginesetc. (notshoWn-l.

The system thus .far described is-conventional,

and includes only conventional apparatus, which it is unnecessary to'illustrate or describe in detail. When petroleum gas is stored in the tank, the pressure in the system varies with the surrounding temperature of the air or earth, as the case may be. With propane, the pressure is relatively highof the order of 125 to 160 p. s. i. The vaporized gas is conducted to the pressure reducer 8 at this pressure, where it passes through an orifice inside the reducer, and is permitted to expand rapidly, reducing the pressure of the gas to a relatively low pressure-between about 5 p. s. i. to 2 ounces per square inch as desired.

The rapid expansion of the gas, as it emerges from the pressure reducer orifice, has a refrigerating effect in accordance with the laws of physics, and produces a temperature within the regulator considerably lower than the freezing temperature of water. Under such low temperature conditions any moisture carried by the gas is condensed to a liquid and promptly freezes at or near the reducer inlet, often shutting off this inlet and completely stopping gas flow through the service line 50. 7

To my knowledge there has previously been only two methods of preventing the freezing of moisture carried by the gas. One is the exterior application of heat to the reducer housing to prevent the interior temperature from dropping below the freezing temperature of water. The other method is the introduction of a liquid antifreeze into the tank 5. The heat method has involved many difficulties. It has required the manufacture of a water or air jacket for the reducer, the provision of a means for heating the air or water, means for circulating air or water through the jacket, temperature control means, etc.

The introduction of liquid anti-freeze into the tank has also involved difficulties, primarily due to the high pressure under which the gas must be stored. Since it is not advisable to pump air into the storage tank, the anti-freeze method requires portable compressor equipment, a pressure hose sufficiently long that it will contain the required amount of anti-freeze liquid, valve f1- tings at each end of the hose, a means of evacuating air from the hose, etc. One end of the hose must be attached to the tank shut oif valve 6, which usually involves disconnecting the pipe line i. The other end of the hose is attached to a pump and air is then evacuated from the hose. The pump intake must then also be attached to the storage tank 5, or to a portable storage tank containing the same type of liquid gas. Such work often requires hours of time on the part of one or two men, in addition to the truck and other equipment mentioned above.

I have found that by providing a suitable antifreeze containing reservoir H capable of withstanding the maximum operating pressure of the system, and by aifording open communication between the upper end of this reservoir and the gas service pipes, sufficient anti-freeze vapor will be introduced into the gas flowing through the line to prevent .freezing of the moisture which condenses from the gas under low temperature conditions. 7

The Figure 1 reservoir H is shown more clearly in Figure 2. It is simply a hollow body 12 having 5 a threaded inlet 13, and a threaded outlet H3. Its upper end is provided with a threaded filler opening I5, which receives a filler plug i6.

Installation of the reservoir is accomplished quickly by one man. The valve 6 isshut oif and 4 the adjacent ends of the pipes 1 and 8 are connected to the reservoir inlet 13 and outlet it, respectively. Anti-freeze liquid is then poured into the reservoir until the liquid level is just below the inlet-outlet level. The filler plug is then replaced, the valve 8 opened, and gas begins to flow through the upper portion of the antifreeze reservoir. The vapor pressure of the antifreeze liquid causes a certain amount of its vapor to mix with the gas flowing through the pipe line.

It should be pointed out that the liquid antifreeze used should have a vapor pressure which is sufiiciently high at any given temperature that its vapor will mix with the vapor of water at the same temperature in such ratio that the resulting vapor mixture (water and anti-freeze) when condensed to a liquid by cooling, will have a freezing point below the temperature produced within the reducer by the rapid expansion of the vaporized gas flowing through the system. I have found that butyl, methyl, ethyl, and isopropyl alcohols and acetone and methyl ethyl ketone will all serve the purpose. There are undoubtedly other anti-freeze liquids which will serve equally well. Each of the ones mentioned has a vapor pressure higher than th vapor pressure of water at the same temperature. According to the laws of physics when any one of them is confined and subjected to the vapor pressure of water at the same temperature, the resulting vapor mixture will be made up of amounts of each vapor in proportion to their respective vapor pressures. The resulting vapor mixture will therefore contain a greater percentage of antifreeze molecules than water molecules. The freezing point of the condensate. of this vapor mixture (water and anti-freeze) will therefore be very materially lower than the freezing point of water. This is the theory behind the effective operation of my improved gas distributing system. However, the method embraced by this invention is not dependent on the introduction of anti-freeze vapor into the gas in any particular manner. .The introduction of such vapor may be accomplished in other ways. Anti-freeze vapor could be introduced into the system by means of a pump, for instance, or it could be jetted into the system under a desired pressure. It could even be introduced into the flowing gas at a point inside the pressure reducer, which is, of course, embraced by the invention.

Referring to Figure 3, a different type of antifreeze reservoir is shown. This reservoir H is in the form of a pressure bottle having a single opening at its upper end. It openly communicates with the natural'gas pipe line 18 and i9 through a nipple 2'0, the other end of which is attached to a 4-way pipe joint 2|. To fill the reservoir with anti-freeze liquid it is only necessary to remove a plug 22 from the joint. This embodiment of the means for introducing antifreeze vapor into any gas distributing system produces results fully equal to those produced by the Figure 2 embodiment.

From the above explanation it will be clearly understood that the method embraced by my invention involves the operation of any gas distributing system in the usual manner, but with the additional step of introducing anti-freeze vapor into the vaporized gas either at the pressure reducer or prior to its arrival at the pressure reducer. Aside from this method of operating a gas distributing or dispensing system, devices similar to those disclosed for introducing the anti-freeze vapor are definitely a part of the invention, even though the devices are simple, and even though the method may be carried out by other means.

Having described the invention with sufficient clarity to enable those familiar with the art to practice it, I claim:

1. In operating a liquified gas system which includes a tank in which gas is stored in both its liquid and vapor phases, a pressure reducer, appliances for using the gas in vaporized form, and pipe lines for conducting the vaporized gas from the tank to the pressure reducer and from the reducer to the appliances, the method which comprises the steps of passing the vaporized gas under relatively high pressure from the tank to the pressure reducer; introducing into the gas prior to its arrival at the pressure reducer a suificient quantity of vaporized anti-freeze to prevent the freezing, during the rapid expansion of the gas within the pressure reducer, of any moisture which may be carried by the gas; and conducting the gas under relatively low pressure from the pressure reducer to the gas using appli- I communication with the line connecting the source to the reducer; a filler inlet in the upper end of said reservoir; and a filler plug for said inlet.

3. In a liquified gas system, the combination with a tank in which gas is stored in both its liquid and vapor phases, a pressure reducer, appliances for using the gas in vaporized form, and pipe lines for conducting the vaporized gas from the tank to the reducer and from the reducer to the appliances, of: a closed anti freeze reservoir having an inlet and an outlet located near its upper end, and installed in the pipe line connecting the tank to the reducer; a filler inlet in the upper end of the reservoir; and a filler plug for said inlet.

JACOB A. DETHEROW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,040,886 Claude Oct. 8, 1912 1,702,683 Claude Feb. 19, 1929 1,726,018 Farrar Aug. 27, 1929 1,794,185 Lemoine Feb. 24, 1931 1,809,833 Davenport June 16, 1931 2,155,340 Stroud Apr. 18, 1939 2,305,314 Little Dec. 15, 1942

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