WO1993002828A2

WO1993002828A2 - Fortified torch gas and process for making and using the same

Info

Publication number: WO1993002828A2
Application number: PCT/US1991/009096
Authority: WO
Inventors: Frank M. Hall
Original assignee: Hall Frank M
Priority date: 1991-07-26
Filing date: 1991-12-04
Publication date: 1993-02-18
Also published as: AU9105891A; SG44888A1; ZA925571B; WO1993002828A3

Abstract

Base hydrocarbon gas, preferably LPG gas, is fortified with 6 % to 20 %, preferably 10 % to 15 %, of methyl ethyl ketone, with activated carbon as a catalyst to make an azeotropic mixture. Cutting of ferrous metal can be accomplished even under water by mixing the fortified torch gas with oxygen having a purity as low as 90 %.

Description

Fortified Torch Gas and Process for Making and Using the Same

Technical Field The present invention relates to torch gas, that is, gas for use in cutting and/or welding torches fortified by the addition of an additive or conditioner.

Background Art Various attempts have been made heretofore to improve gas used in cutting and/or welding torches by adding an additive to them. These prior art gases have been composed of various hydrocarbons from methane to octane and some have included propane and butane. Harris U.S. patent No. 1 ,565,935, issued December 15, 1925, for example, fortified a wet casinghead gas composed of methane, ethane, propane, butane and hexane by the addition of ether. Other patents that proposed to add ether or ethyl oxide to a gas including propane or butane and propane are as follows:

U.S. patent No. 2,411 ,759, issued November 26, 1946 (Selay);

U.S. patent No. 2,513,769, issued July 4, 1950 (White) , U.S. patent No. 2,951 ,750, issued September 6, 1960 (White); and

British patent specification No. 813,981 , published May 27, 1959 (Oxy-Ferrolene Limited). In addition, Kessler U.S. patent No. 3,591 ,355, issued July 6, 1971, proposed the addition of methanol to a gas containing propane. White U.S. patent No. 3,989,479, issued November 2, 1976, also proposed the addition of methanol and British patent specification No. 569,108, accepted May 4, 1945, proposed the addition of ammonia.

Medsker U.S. patent No. 2,908,599, issued October 13, 1959, stated that methyl borate and acetone had been used previously for a fuel in torch use citing U.S. patent No. 2,281,910. The Medsker patent proposed a mixture of methyl borate and hexane as an additive for a gaseous fuel. The Bialosky et al. patent No. 2,281,910, issued May 5, 1942, discloses a liquid flux containing methyl borate and a ketone, such as acetone or methyl ethyl ketone, to be subjected to a stream of acetylene, hydrogen or similar combustible gas for coating the work with boric acid or oxide.

The British patent specification No. 569,108 mentioned above recommended increasing the amount of propane in producer gas, water gas, Mond gas and other commercially available gas mixtures in which methane predominated.

The principal torch gas used heretofore has been acetylene which is comparatively expensive, difficult to store and to transport, requires the use of almost pure oxygen with it and forms persistently adherent scoria when used for cutting ferrous metal.

Disclosure of the Invention A principal object of this invention to provide a fortified torch gas having characteristics superior to those of acetylene, especially for cutting ferrous metal, and also for welding.

A particular object is to provide a torch gas which will have high flame temperature and intense heating capability.

A further object is to provide torch gas that can be stored and transported easily and economically. Another object is to provide a torch gas having a base gas which is readily available in almost the entire world, can be provided more economically and is easy to fortify for enhancing its attributes. It is also an object to provide a torch gas enabling ferrous metal to be cut faster and cleaner.

Another object is to provide a gas that can be used by torches for cutting under water at considerable depths.

An additional object is to provide a gas that can be used for torch cutting more economically because it will combine effectively with oxygen containing a higher proportion of adulterating gases which cannot be used with acetylene.

The foregoing objects can be accomplished by utilizing liquefied petroleum gas fortified with methyl ethyl ketone.

Best Modes for Carrying Out the Invention Liquefied petroleum gas (LPG) is the preferred base gas for the fortified torch gas of the present invention because of its high butane and propane content. Both the n_-butane and isobutane isomers of butane are usually present in LPG, but a substantial amount of butane may have been removed from LPG sold as fuel because of the demand from industry for butane derivatives, in which case the LPG is made up largely of propane. It is, however, desirable that there be a reasonable proportion of butane in the LPG, such as from 5% to 40%.

The additive or conditioner used to fortify the base gas is methyl etnyl ketone, otherwise known as 2-butanone, having the formula CH3COCH2CH3. This additive is a liquid with a boiling point of 70.6° C. and a specific gravity of 0.805 at 20° C.

LPG must be stored under pressure to keep it in a liquid state, but relatively heavy pressurized storage tanks and handling equipment for LPG is commercially practical and customary. Without being fortified, LPG is not very effective for torch cutting and welding, not nearly as effective as acetylene gas, but by enriching the base gas with methyl ethyl ketone as an additive the flame temperature is substantially increased and the heating capability is greatly enhanced.

The procedure for combining the additive with the LPG is simple. Methyl ethyl ketone is a liquid at normal temperatures and is supplied to the storage tank in which the LPG is to be stored or transported. It is quite practical to supply the additive to standard 55- gallon drums. The additive is supplied in conjunction with a catalyst, preferably activated carbon in the form of powder, granules or pellets. The activated carbon is amorphous, preferably having been produced from coal or petroleum coke." Alternative catalysts that can be used are platinum, cupric oxide and granular silver carried by a suitable carrier.

The amount of additive used will depend on the extent to which it is desired to enhance the characteristics of the base gas, but the amount would be 6% to 20% of the base gas by weight, preferably 10% to 15%.

The amount of activated carbon used is not critical, but a sufficient amount should be placed in the bottom of a storage container so that the additive will be mixed with the base gas when it is supplied to the container under pressure. An amount of such catalyst between 1% and 5% of the weight of the additive would be satisfactory. The resulting mixture of base gas and conditioner will be azeotropic so that the fortified torch gas will be homogeneous when it is released from the storage container to the torch.

In order to provide an effective cutting flame, it is necessary to supply to an acetylene torch oxygen that is in substantially pure form, such as at least 99% oxygen by volume. Satisfactory cutting temperatures can be provided by mixing with the fortified base gas of the present invention less pure oxygen such as having a purity of approximately 90%, the balance of which can be nitrogen, carbon dioxide and other adulterants. Even when oxygen of 90% purity is used, the flame temperature of base gas LPG of approximately 5,000° F. can be raised to approximately 5,800° F. to 6,000° F. by use of the base gas LPG fortified according to the present invention. Such impure oxygen can be produced economically by compressing air to about 4,000 psi, chilling it to minus 360° F. which liquefies the air and then allowing the temperature of the liquefied air to rise gradually while venting the container to release the nitrogen component of the liquefied air which vaporizes at minus 320° F. leaving the oxygen in liquid form.

In other processes for producing impure oxygen, the nitrogen content of. air is removed by zeolite resulting in oxygen of 90% to 95% purity.

An advantage of using the fortified base gas of the present invention over acetylene for cutting ferrous metal is that a clean precise kerf is obtained. Oxyacetylene cutting produces a hard scoria persistently adherent to the work which increases the heating required and usually must subsequently be chipped off the work. Utilization of the fortified torch gas of the present invention produces a soft friable scoria which is sloughed off from the work and out of the kerf as the cutting progresses to leave a narrower clean kerf with virgin metal along opposite margins of the kerf.

A particular advantage which the fortified torch gas of the present invention has is that it can be used for flame cutting under water to a depth of 300 feet. The use of the oxyacetylene torch is limited to 20 feet under water because at pressures to which it would be necessary to subject the gas to enable it to be dispensed to the cutting torch at greater depths the acetylene will explode. Consequently, the only alternative that has been available for cutting under water at depths greater than about 20 feet prior to the present invention has been the use of a carbon arc, the action of which is slow and the use of which is dangerous.

Claims

1. A torch gas comprising a mixture of liquid petroleum gas and methyl ethyl ketone.

2. A fortified torch gas comprising a mixture of a major portion by weight of hydrocarbon base gas and a minor portion by weight of methyl ethyl ketone as an additive.

3. The torch gas defined in claim 2, in which the amount of additive is within the range of 6% to 20% of the base gas by weight.

4. The torch gas defined in claim 2, in which the amount of additive is within the range of 10% to 15% of the base gas by weight.

5. The torch gas defined in claim 2, claim 3 or claim 4, in which the base gas is liquefied petroleum gas .

6. The process of making fortified torch gas which comprises mixing methyl ethyl ketone and liquefied petroleum gas.

7. The process of making fortified torch gas which comprises supplying methyl ethyl ketone additive in conjunction with activated carbon and supplying a base hydrocarbon gas for mixing with the methyl ethyl ketone additive.

8. The process defined in claim 7, in which the additive is within the range of 6% to 20% of the base hydrocarbon gas by weight.

9. The process defined in claim 7, in which the additive is within the range of 10% to 15% of the base hydrocarbon gas by weight.

10. The process defined in claim 7, claim 8 or claim 9, in which the base hydrocarbon gas is liquefied petroleum gas.

11. The process of cutting ferrous metal which comprises supplying fortified torch gas to a cutting torch and simultaneously supplying to the cutting torch oxygen having a purity within the range of 90% to 98% by volume.

12. The process of torch cutting ferrous metal under water which comprises supplying to a torch submerged in water a mixture of fortified torch gas and oxygen.

13. The process defined in claim 12, in which the oxygen has a purity between 90% and 98%.

14. The process defined in claim 11 or claim 13, in which the purity of the oxygen does not exceed 95% by volume.

15. The process defined in any of claims 11 to 13, in which the fortified torch gas is base hydrocarbon gas fortified with methyl ethyl ketone.

16. The process defined in any of claims 11 to 14, in which the fortified torch gas is fortified liquefied petroleum gas.

17. The process of torch cutting ferrous metal under water which comprises supplying to a torch submerged in water a mixture of liquefied petroleum gas, methyl ethyl ketone and oxygen.