US1143132A - Process of fixing atmospheric nitrogen. - Google Patents

Description

s. PEAcoCK.

PROCESS 0F FIXING ATMOSPHERIC NITROGEN.

APPLICATION FILED NOV- 5, 1912.

Patented June 15, 1915.

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UNITE SARS ERICE,

SAMUEL PEACOCILOI? CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AGRICULTURAL RESEARCH CORPORATION, 0F NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

PROCESS OF FIXING ATMOSPHERIC NITROGEN.

Specification of Letters` Patent.

Patented I une 15, 1915.,

Application led November 5, 1912. Serial No. 729,605.

T0 all whom t may concern:

Be it known that I, SAMUEL PEAooox, a citizen of the 'United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Processes of Fixing Atmospheric Nitrogen; andI do hereby declare the following to be .a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a process of fixing atmospheric nitrogen, and has for one of its objects to chemically fix this element even though it is mixed with another gas or gases.

Another Objectis to provide a process by which free nitrogen can be fixed in one operation Without the employment of electrically generated heat.

As is well known, electricity is now used as a source of heat in fixing atmospheric nitrogen largely because it offers the great advantage of simplifying the process. That is to say, unless during and after the lfixation, the nitrogen product is protected from chemically active oxygen, which may be in the form of free oxygen, of water vapor, of carbon dioxid, etc.; the said product is liable to be decomposed as fast as formed, and electrically produced heat offers an easy means of. excluding this objection. But on the other hand, it is' also well known that such heat entails a number of disadvantages, such as its high cost in all localities, where there are no water powers, .or where the water powers are not substantially constant vall the year around.

It is therefore an important feature of my invention that I employ fuel and thereby dispense with electrically generated heat, while protecting the product from chemically active oxygen, for at the same time I avoid the above objections and thereby leave the manufacturer free as to his choice of a factory site.

By .my .process free nitrogen is fixed chieiy as a double nitrid of carbon combined with a second or even a third element'. Said nitrogen may also be fixed in lesser degrees as a single nitrid, as a cyanid, or even as a c anamid, as will appear below.l

enerally stated, my process consists in providing a suitably proportioned mixture of finely divided carbon and an oxid not capable of volatilization at atmospheric pressure at a temperature below 1700 C., and subJectlng'said mixture to a temperature between 1200o C. and 1600o C., in an atmosphere containing free nitrogen but containlng no chemically active oxygen. After the product is formed, it is further discharged mto suitable receptacles where it is cooled out of contact with such chemical-ly active oxygen, all as will be clear from the following drawings forming a part of this specification, in which the figure is a diagrammatic sectional view of a furnace suitable for carrying out my process.

In said drawings, 1 indicates any suitable base; 2, 3 and 4 any suitable supports for the furnace body; 5 a power shaft; 6 a pinion on said shaft; 7 a gear carried by th'e furnace body meshing with said pinion; 8 the furnace body; 9 guiding rollers taking in guide rings 10 on said body; 11 a steel shell surrounding said body; 12 a refractory lining for the shell; and 13 a readily removable end closure for the upper or feed end of the furnace.

14 indicates a steel casing for the closure 13; 15 a suitable blast device for feeding oil and air or finely divided carbon and air or fuel gas and air into the furnace; 16 a pipe located in the apparatus 15 and forming a part thereof; 17 a feed conveyer for supplying charge vmaterial 18 to the furnace; 20 an exit associated with the discharge end of the furnace; 21 a receptacle fitted air tight to said exit 20; 22 an escape passage for the gases leading into the dust collector 23; 24 a flue leading out of said dust collector to which may be attached a suction device not shown if desired; 25 the bottom of said dust vcollector on which the dust settles: 26 openings for the removal of the dust: 27 a valve in the flue 24 to regulate the escape of the gases. and therefore the pressure inside the furnace body; and 28 partitions in said dust collector, of which there may be any desired number, and which are successively spaced farther apart in order to facilitate the settling of the dust.

30 represents spaces which are left between the closure 13 at one end, and the dust collector at the other end of the furnace to permit the escape of the burning gases, and thereby form an edectual seal against the entrance of air into the furnace, except .through the blast device 15. The pressure in also aided by the proper manipulation of the valve 27. A

31 represents a valve in the exit 20 for the purpose of closing air tight the receptacle 21 when the product is being cooled therein; and 32 represents rollers for removing the receptacle 21.

I prefer, as a charge for the furnace, an oxid vof alumina, lime orsilica, and I provide such an excess of carbon as to supply from four to five times as much carbon as may chemically combine With the total free and combinedexygen present in Whatever form it may occur.

The zone of highest temperature inl the body portion 8 occurs at about four feet from the upper or feed end of the cylinder, and it may extend as far as about thirty feet, from which point all the oxygen present in Whatever form Will be converted to carbon monoxid CO, and no further evolution of heat from the oxidation of carbon can occur. The temperature in this zone may be maintained as high as 1700o C., or it 'may be kept as low as 1200o C., depending upon the commercial needs of the process. At the higher temperature, the reaction is vmore rapid, 'but the fuel consumption is more than correspondingly greater, so that commercial considerations will govern the limitsof4 the temperature actually employed.

Nitrogen in sufficient quantities is supplied to the charge by means ofthe air used in operating the furnace. As the heated furnace gases and the reaction products travel in the same direction to the lower or discharge end of the furnace, a temperature of 1000o C. or more is readily maintained throughout the full length of the furnace, and this temperature serves to 4prevent any material reconversion of the carbon monoxid to free carbon and carbon dioxid. At the discharge end, the gases-pass, as above stated into the dust collector and the damper serves to maintain the pressure in the furnace materially above that of the'atmosphere. This higher pressure! serves to cause the gases from the furnace to escape through- The solid product containing fixed nitrogen is discharged by gravity ,through the exit 20 into the receptacle 21, Which, when full, is closed air tight by turning the valve 3l, andthe receptacle may thereupon be` removed and a new one brought into place.

In operating my process, the temperatures are only controllable lWithin say 200O to 300, and therefore the end product Will be found of variable composition. The most economical product is a double nitrid, such as Al2C,l\T6 When alumina is used as an oxid. As this compound may be more or less heated above its heat of formation, it may dissociate to aluminum nitrid AJ2N2, free nitrogen N, and cyanogen gas (CN). Also, in the presence of-alumina, owing tothe difficulty of controlling the temperature, more or less of a true cyanid Will be formed in accordance with the following equation z- -sAizcaNmLAizoae mum. In some cases Where supplies of free nitrogen more or less contaminated With other gases are available, I may also enrich the furnace atmosphere With said nitrogen and thereby facilitate the reaction.

It is obvious that those skilled in the art may vary the details of my process Without departing from the spirit thereofQand therefore I do not Wish to be Ilimited to the above disclosure except as may be required by the claims. What I claim is 1. The. method of fixing atmospheric nitrogen in fuel fed furnaces, which consists in providing a suitable furnace` charge of carbon and an oxid, the carbon being in such excess as to preclude the formation of carbon dioxid during the process; and feeding free nitrogen, air and fuel to said furnace and thereby subjecting said charge to a temperature sufficient to fix the said free nitrogen, as Well as some of the nitrogen left in said air after the oxygen has been consumed, substantially as described.

2. A process for the fixation of nitrogen Which consists in forming a mixture of a compound of one of the nitrogen xing metals and carbon; causing the same to travel through a closed chamber; simultaneously burning in said chamber a carbonaceous fuel injected with air; and leading the products of combustion to their exit in the same direction of travel as and in contact with the said mixture.

mame@ 3. A process for the fixation of nitrogen 'which consists in forming a mixture of a Compound on one of the nitrogen fixing metals and carbon; feeding the same. into one end of a rotary furnace through which it is caused to travel; injecting and burnlng in the same end of the furnace air and a carbonaceous fuel; and leading the products of combustion to the exit end of the furnace in Contact with the said mixture.

In testimony' whereof, I aiiX my signav ture, in presence `of two Witnesses.

SAMUEL PEAUUCK. Witnesses:

ROBT. C. BIOREL, GRUNEFLUN ALBRIGHT.

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