US3925033A

US3925033A - Combustible gas system and method

Info

Publication number: US3925033A
Application number: US472601A
Authority: US
Inventors: Frederick W Mayo
Original assignee: N R G EQUIPMENT CORP
Current assignee: N R G EQUIPMENT CORP; Nrg Equipment Corp
Priority date: 1974-05-23
Filing date: 1974-05-23
Publication date: 1975-12-09
Anticipated expiration: 1992-12-09

Abstract

A combustible gas such as propane or natural gas is bubbled through a liquid having a higher BTU content, to provide an enriched mixture of gases which burns with a hotter flame. The enriching liquid is contained in a separate tank into which the gas to be enriched is fed by means of a dip tube which has an opening into the top of the tank above the liquid level as well as opening near the bottom of the tank. The enriched gas is withdrawn from the top of the tank.

Description

United States Patent Mayo Dec. 9, 1975 COMBUSTIBLE GAS SYSTEM AND METHOD Inventor: Frederick W. Mayo, Livonia, Mich.

N.R.G. Equipment Corporation, Livonia, Mich.

Filed: May 23, 1974 Appl. N0.: 472,601

Assignee:

US. Cl 48/144; 48/196 FM; 48/197 FM;

48/199 FM; 48/219; 261/121 R int. C1. CIOJ l/20 Field of Search... 48/196 FM, 197 R, 197 FM, 48/199 FM, 219, 144; 261/DIG. 7, 121 R, 126

References Cited UNITED STATES PATENTS 5/1973 Henes 48/219 FOREIGN PATENTS OR APPLICATTONS 427,624 4/1935 United Kingdom 48/199 FM 1,345,594 11/1963 France 48/219 Primary Examz'nerR, E. Serwin Attorney, Agent, or Firm-Harness, Dickey & Pierce [57] ABSTRACT 8 Claims, 2 Drawing Figures U.S. Patent Dec. 9, 1975 i ll;

COMBUSTIBLE GAS SYSTEM AND METHOD BACKGROUND OF THE INVENTION Combustible gases intended for industrial use in relatively high temperature operations in recent years have been improved by the development of enriched combinations of propane or the like with heavier hydrocarbons such as pentane, isopentane or other hotter burning constituents. Such enriching constituents have also been added to natural gas. Under proper conditions such enriched hydrocarbon gases are capable of relatively high temperature operations such as cutting heavy steel, and have replaced oxy-acetylene techniques for many purposes. An enriched propane gas is disclosed in U.S. Pat. No. 3,591,355, granted July 6, 197i.

Such enriched gases have generally been supplied to the user in premixed form in a container having a dip tube extending from the withdrawal valve to the bottom of the container. The dip tube has ports or orifices at points above the liquid level which allow vapor gas (almost exclusively propane or the other lighter constituent) to escape from the top of the cylinder into the dip tube and out the withdrawal valve. At the same time, the retained gas pressure in the cylinder forces heavier enriching constituents from the bottom of the tank up through the dip tube for entrain ment and mixture with the lighter gas. This commonly-used system is incapable of supplying a uniform and optimum mixture to the operator except under ideal conditions of demand rate and pressure. Since the top ports in the dip tube are necessarily of fixed size, if the operation calls for a small amount of gas (less than the full capacity of such ports), only the light gas from the top of the tank escapes, and the heat value of the enriching fluid is not obtained. On the other hand, where the demand is heavier than the capacity of such ports, the ports cannot supply enough of the lighter gas and the heavy constituents are discharged in excessive volume. Further, the pressure in the container varies widely, and causes additional differences of output. It is therefore generally impossible under practical operating conditions to supply fuel of constant heat value from such a system. Typically, either the enriching fluid or the propane is exhausted prematurely, and the container must be removed with a substantial waste. Inasmuch as these premixed fuels are expensive, a substantial cost penalty is involved in addition to the difficulty of obtaining efficient operation.

The object of the present invention is to provide an improved enriching system having operating characteristics which enable the feeding of an optimum mixture despite variations of demand and variations of pressure conditions, and which is efficient and economical.

A related object is to provide an improved system of the indicated character which is highly flexible and which permits use of the basic gas with or without the enriching fluid as may be desired.

Other objects and advantages will become apparent upon consideration of the present disclosure in its entirety.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING FIG. 1 is a partly diagrammatic side elevational view of gas enriching means constructed and operable in ac- 2 cordance with the invention, parts being broken away; and

FIG. 2 is a plan view, also somewhat diagrammatic, of a modified system.

DETAILED DESCRIPTION OF THE PREFERRED FORMS OF THE INVENTION Reference character 10 designates a metal tank which may be of a commercially-available type designed to withstand the internal pressure of the gases. The tank is filled to a level 2 or 3 inches below the top with an enriching liquid which may consist of one of the higher fraction hydrocarbons, a gaseous alkane such as pentane or isopentane, or a mixture of such materials with other liquids which burn at relatively high temperatures such as other hydrocarbons in the C or C range. The tank is provided with an inlet fitting 12 into which the basic combustible gas to be enriched, typically propane, is delivered through a conduit 14, a shutoff valve 15 being provided at the inlet. An adjustable pressure regulator 17, preferably of an infinitely adjustable type, is incorporated in the inlet conduit at a position convenient to the operator.

The inlet fitting 12 supports and communicates with a dip tube 16 which projects to and is open at a position near the bottom of the tank. An orifice 18 in the dip tube at a position above the liquid level in the tank permits a metered quantity of the gas to bypass the enriching liquid. The tank has an outlet opening in the top which communicates directly with a fitting 20 controlled by an outlet shut-off valve 22 which is in turn connected to the delivery conduit 24. A bypass conduit 25 controllable by a shut-off valve 26 permits a direct connection between the inlet and outlet conduits 14, 24, bypassing the enriching tank, when the valve 26 is open.

In operation, with valves 15-22 open and valve 26 closed, propane delivered to and through the tank is partially discharged through the orifice l8, and partially delivered to the bottom of the tank and bubbled up through the enriching liquid. The orifice 18 is relatively small so that substantial pressure remains in the dip tube, but the size of the orifice may vary in accordance with the demand which the system will be called upon to provide, so that a proper proportion of the gas is bubbled through the enriching liquid. The gas which rises from the liquid, containing molecules of the higher fraction substance, mixes with the bypassed gas and is discharged to the work via the outlet fitting 20 and delivery conduit 24.

By varying the delivery pressure at the adjustable pressure regulator 17, the operator is able to vary the BTU content of the gas delivered to the work via output conduit 24. This is due to the fact that the volume of the input gas which is forced to bubble up through the enriching fluid, and so become saturated with molecules of the hotter constituents, depends upon the pressure of the inlet gas which is delivered to the dip tube. When it is desired to employ the basic gas without enrichment, it is of course merely necessary to close the valves 15, 22 and open the bypass valve 26.

The. modified arrangement shown in FIG. 2 is arranged to permit a plurality of standardized enriching tanks to be used where a heavier demand exists. Two tanks, 10A and 108, each of which may correspond in construction to the enrichment tank 10 previously described, are illustrated. Parts designated by reference numerals followed by the letters A or B will be recognized as corresponding to components previously described, and will require no redescription. The arrangement disclosed is particularly suited for use with natural gas, or for selective use of either natural gas or propane as may be desired. A natural gas inlet conduit is indicated at 30 and a propane gas inlet conduit is indicated at 14A. Both inlet conduits 30 and 14A lead into a manifold 32 which is provided with a plurality of outlet fittings as 33 to each of which an inlet conduit as 34, 34A may be connected leading to the inlet valve as 15A, 15B of the enrichment tank. The outlet valves 22A, 22B of the enrichment tanks are connected to an outlet manifold 35 which is provided with a plurality of inlet fittings 36 and the outlet of which is connected to the discharge conduit 24A. The manifolds illustrated are designed to permit the use of up to three tanks, but this is of course subject to variation. A bypass line 25A controlled by a normally closed bypass valve 26A interconnects the manifolds 32, 35.

Each of the inlet lines 30-14A is controlled by a shutoff valve as 40, 41, and each inlet also icorporates an adjustable pressure regulator, 17A, 17B, adjustment of which has the effect of varying the BTU content of the delivered gas. 7

Where a heavy demand for enrichment exists, the manifold arrangement permits a plurality of standardized enrichment tanks to be connected and to function in parallel. Additional flexibility is provided by reason of the fact that the enrichment tanks can also be individually turned on and off merely by opening and closing the valves on the tanks. As will also be apparent, closure of the tank valves and opening the bypass permits either of the two basic gases to be used without enrichment.

This Detailed Description of Preferred Forms of the Invention, and the accompanying drawings, have been furnished in compliance with the statutory requirement to set forth the best mode contemplated by the inventor of carrying out the invention. The prior portions consisting of the Abstract of the Disclosure and the Background of the Invention are furnished without prejudice to comply with administrative requirements of the Patent Office.

What is claimed is:

l. The method of increasing the heating capacity of a combustible gas which comprises bubbling a portion of the gas through a combustible liquid having a greater caloric value than the gas and delivering another portion of the gas to an area above the liquid, and combining the gas portion above the liquid with the gas portion which has been bubbled through the liquid into said area.

2. The method of claim 1 wherein the liquid is contained in a pressure vessel and said one portion is deliv- 4 ered through a restricted orifice into said vessel above the liquid and said other portion through a dip tube to the bottom of the vessel from which it bubbles upwardly through said liquid to mix with said one portion.

3. The method of increasing the heating capacity of a combustible gas which comprises conducting the gas through an adjustable pressure regulator and then into the upper and lower portions of a pressure vessel containing an enriching liquid, allowing the gas to bubble upwardly through the enriching liquid and mix with the gas in the upper portion of the vessel above the liquid, and withdrawing the enriched gas mixture from the upper portion of the vessel above the liquid, whereby the BTU content of the enriched gas is variable by adjusting the pressure regulator.

4. The method of claim 3 wherein a portion of the gas is delivered through a restricted orifice into an upper portion of the vessel above the liquid level therein, and is then combined with the enriched gas as it bubbled upwardly and emerges from the liquid.

5. A combustible gas system including a pressure vessel having an outlet at the top and having a main inlet and a restricted gas delivery inlet connected to said main inlet and opening into the vessel near the top, a dip tube also interconnected with said main inlet and leading to a discharge opening below the level of liquid in the vessel, and a quantity of a liquid in the vessel of relatively higher heat value than said gas, the level of said liquid being below said restricted gas delivery inlet, whereby when gas is delivered simultaneously to said restricted gas delivery inlet and dip tube it is subdivided and one portion bubbled through the liquid and then combined with gas delivered to the space above the liquid for discharge therewith through the outlet.

6. A system as defined in claim 5 including an adjustable pressure regulator between said main inlet and the source of the gas at a position conveniently accessible to a point of delivery of the enriched gas from said outlet.

7. A system as defined in claim 5 including an inlet manifold connectible to a source of gas under pressure and having a plurality of outlets, and an outlet manifold having a plurality of inlets and having an outlet connectible to a delivery conduit, whereby a plurality of such pressure vessels may have their main inlets con nected to the inlet manifold and their outlets connected to the outlet manifold.

8. A system as defined in claim 7 including an adjustable pressure regulator interposed between said source and said inlet manifold at a position conveniently accessible to a point of delivery of the enriched gas from the outlet manifold.

Claims

1. The method of increasing the heating capacity of a combustible gas which comprises bubbling a portion of the gas through a combustible liquid having a greater caloric value than the gas and delivering another portion of the gas to an area above the liquid, and combining the gas portion above the liquid with the gas portion which has been bubbled through the liquid into said area.

2. The method of claim 1 wherein the liquid is contained in a pressure vessel and said one portion is delivered through a restricted orifice into said vessel above the liquid and said other portion through a dip tube to the bottom of the vessel from which it bubbles upwardly through said liquid to mix with said one portion.

7. A system as defined in claim 5 including an inlet manifold connectible to a source of gas under pressure and having a plurality of outlets, and an outlet manifold having a plurality of inlets and having an outlet connectible to a delivery conduit, whereby a plurality of such pressure vessels may have their main inlets connected to the inlet manifold and their outlets connected to the outlet manifold.