US2894830A - Fuel compositions - Google Patents

Description

COMPOSITIONS States I mm assi'gno'rs to General" Electric Company, 'a corporation.

of New York No Drawing. Application November 30, 1948 Serial No. 62,786

6 Claims. (Cl. 52-5) The present invention relates to improved fuels. It is particularly concerned with fuels of improved combustibility and velocity of flame propagation.

The invention is based on the discovery that the addition of small amounts of boron hydrides to conventional fuels employed for heating or propulsion purposes markedly increases both the combustibility and the velocity of flame propagation of such fuels. As a result of the present invention, there can obtained an increase in the burning rate of the fuel with a resultant increase in the rate of fuel consumption to effect an increase in the total heat output of a given burner. Such an increase in the rate of heat release thus may result in a higher power output for continuous combustion devices such as reaction motors, rockets, or jets. Thus small units or smaller burners can be employed to obtain the same energy output with a resultant saving in size and Weight. Further the increased burning rate obtained by the addition of boron hydrides will permit the utilization of low grade fuels for many applications for which they are not now acceptable due to their present slow burning rates.

In accordance with the presentinvention the abovementioned advantageous results are obtained by the use of a gaseous or vaporized boron hydride such as diborane, B H tetraborane, B H or pentaborane, B H The boron compounds are added to the fuel in amounts such that the boron hydride comprises up to 20% by volume of the fuel component of the gaseous combustion mixture.

The following examples are illustrative of the manner in which the present invention can be carried into effect and of the results which can thereby be obtained.

Example 1.-A conventional Bunsen burner was operated on illuminating gas and from time to time small amounts of diborane were injected into the fuel stream. Admixture of amounts of diborane, less than 510% of the total gas flow, were sufiicient to cause a marked shortening of the inner flame cone, indicating a definite increase in the burning velocity.

Example 2.-A solution of 4% of pentaborane in hexane showed a combustion velocity from 1.2 to 1.5 times that of a control sample of hexane alone. The solution and the control were burned alternately in the same burner at the same conditions of vapor flow and air flow during the combustion tests.

Example 3.--A mixture of illuminating gas comprising carbon monoxide, hydrogen, and hydrocarbons was mixed with air and combusted in a long tube laminar flow burner. The gas flow was 0.142 c.f.m. (cubic feet/minute) and air flow was 0.480 c.f.m. From measurements on the flame come, the combustion velocity of this mixture was calculated to be about 1 6.3 cm./sec. Then,

maintaining the same rate of gas and air flow, diborane was added to the gas flow at the rate of 0.009 c.f.m.

ice

seen that the addition of 6.3% of diborane to the fuel flow, or 1.4% to the total reactant flow, resulted'in a 3.3 times increase in the combustion velocity of the gas air mixture.

Example 4.Air was bubbled through methyl alcohol held at 35 C., and the resulting mixture was combusted in the same burner as Example 3. Assuming vapor-liquid equilibrium in the bubbler the flow of reactants approximated 0.14 c.f.m. of air and 0.037 c.f.m. of alcohol vapor. The velocity of combustion of this mixture was calculated from measurements on the flame as about 18.7 cm./sec. The addition of 25 cc./min. of diborane to the flow of reactants increased the burning velocity to about 35.6 cm./sec. This amount of diborane represents about /2 of 1% of the total reactant flow. The estimated combustion velocity of diborane at this fuel to air ratio is less than 30 cm./sec. so the effect is disproportionate to the amount of diborane added.

Example 5.-Hydrogen and oxygen were mixed and combusted in a torch having a long narrow tube burner tip. With a hydrogen flow of 0.19 c.f.m. and an oxygen flow of 0.077 c.f.m., the combustion velocity was measured as about 575 cm./sec. The replacement of 0.02 c.f.m. of hydrogen by 0.006 c.f.mv of diborane, the oxygen floW being held constant, produced a flame with a combustion velocity of approximately 1050 cm./sec. This amount of diborane represents about 2.5% of the total reactant flow or about 3.5% of the total fuel gas flow.

Example 6.-Hexane was vaporized from a bubbler at room temperature by an air stream and carried into a burner of the type employed in Examples 3 and 4, Where it was mixed with additional air and combusted. The total air flow was about 3.9 c.f.m. and, assuming equilibrium in the bubbler, the hexane vapor flow was about 0.1 c.f.m. The measured combustion velocity calculated from measurements of the flame was 50 cm./ sec. When a mixture of hexane containing 4% by weight of pentaborane was substituted for the hexane, all other conditions being held constant, the combustion velocity was measured as 76 cm./sec. or an increase of 1.5 times. As the vapor pressure of pentaborane is slightly higher than that of hexane, correcting for this indicates that the amount of pentaborane in the vapor did not exceed about 6.5% by weight of the total fuel and the ratio of pentaborane to air did not exceed about 1 to 600.

Depending upon the fuel, the boron hydride may be added either to the fuel before mixing with the oxidizing agent or may be added to'the fuel-air or fuel-oxygen mixture just prior to burning. In the case of acetylene or other fuels which react with diborane, the borane should be introduced into the fuel or fuel-air mixture just prior to the burning thereof.

In general, the limits desirable for the diborane content of the fuel component of the gaseous combustible mixture is from /2 to 20%. gaseous or vaporized fuel, applies whether the fuel and boron hydride are mixed in the gaseous or liquid state or used as solutions of the hydride in the liquid fuel, e.g., hexane. Greater amounts may lead to trouble with clogging of jets and may be uneconomical because of the relative high cost, at present, of boron hydrides.

What we claim as new and desire to secure by Letters This ratio, based on the /z to"20% byvolume of b'oronhydride. T 5." The method of increasing the rate of combustion of illuminating gas which comprises blending therewith about /2 to 20% by volume of a boron hydridef 6. A fuel composition consisting of a mixture of hex ane vapor and from /2 to 20% by volume of a boron hydride.

References Cited in the, file of this patent M 1 UNITED STATES PATENTS 2,257,194 Rosen Sept. 30, 1941 2,266,776 Leum Dec. 23, 1941 2,461,797 ZWicky Feb. 15, 1949 OTHER REFERENCES Chemical Abstracts, Vol. 30, p. 4421 (1936). Abstract 10 of Hydrides of Boron V. The Ethyl and Propyl Diboranes, by Schlesinger et'al.

I. Am. Chem. Soc. 58, 4079 (1936).

Chemical and EngineeringNews, vol. 26, No. .39,

September 27, 1948, Jet PropulsionlBo 15 Flame Mechanics, pp. 2892, 2893.

osts Interest in

Claims (1)

1. 8. A PROCESS FRO THE PRODUCTION OF A METAL FROM FINELY DIVIDED PARTICLES OF A REDUCIBE COMPOUND THEREOF, WHICH COMPRISES PREHEATING SAID PARTICLES IN A PREHATING ZONE, CONDUCTING SAID PREHEATED PARTICLES TO A REDUCING ZONE WHEREIN SAID PARTICLES ARE SUSPENDED IN A STREAM OF REDUCING GAS AT A TEMPERATURE AND FRO A TIME SUFFICIENT TO REDUCE THE MAJOR PART OF SAID PARTICLES TO METAL, THE CONDITIONS IN SAID REDUCING ZONE BEING THOSE OF A FLUIDIZED REDUCING BED, INTRODUCING GASES EMERGING FROM SAID REDUCING ZONE INTO A COMBUSTION ZONE INTERMEDIATE SAID PREHEATING AND REDUCING ZONES, BURNING SAID GASES IN SAID COMBUSTION ZONE AND INTRODUCING THE COMBUSTION PRODUCTS INTO SAID PREHEATING ZONE TO HAT THE PARTICLES THEREIN