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FIXATION of ATMOSPHERIC NITROGEN

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FIXATION of ATMOSPHERIC NITROGEN THESIS ON THE FIXATION of ATMOSPHERIC NITROGEN. Submitted to the Faculty of the for the degree of Bachelor of Science in Electrical Engineering. by JacKson Kenelem Fairchild. June 10, 1911. APPROVEDRedacted for privacy Department of Electrical Engineering. Redacted for privacy Dean of School of Engineering. TIE ELECTROLYTIC FIXATION of ATMOSPHERIC. ITITUCGEIT. Introduction, Much has been accomplished in the last few years toward the conservation of natural resourses, and in this work the engineer has taken a leading part. The prevention of unnecessary waste, the utilisation of hither-to useless "by-products, and the economic pro duction of the world's necessities are important fea tures of th1 s work. It is the latter phase with which this subject deals. A large percentage of the world's commercial fertilizer comes from the immense beds found in the Atacama Desert, in Chile. But as the demand for Chili Saltpeter is increasing rapidly from year to year, scien tists are already "beginning to look around for another source of supply when these fields fail. The following paper will be divided into three parts; First, A discission of the theory and economic principles Second, a resume of the current literature on the sub ject. Third, The construction and tests of a chamber pa tented after the Thomas and Barry Process. Part I. Theory and Economic.. Principles. If and electric discharge is passed through a gas or mixture of gases, different chemical reactions are produced ascording to the nature of the discharge. Thus, if a silent discharge is passed through atmospheric air, the oxygen ( C^ molecules).in~the air is changed into ozone, f O5 molecules). On the other hand, if a spark or arc discharge passes through air, the oxygen and nitrogen of the air are forced to combine; since the nitrogen of the air is thereby fixed in the form of a useful compound, this process is spoken of as the fixation of atmospheric nitrogen. The combination of the niti'ogen and oxygen in air ^oy means of arc or spark discharges in air is apparently a purely th#$mal effect, so that one may speak of this pro cess as an electric furnace process. The arc or spJ simply produces the very high temperature which is re quired for the oxidation of the nitrogen, which would go on in the same way if the same temperature was produced in some other way. The reaction is : plus O2 equal 2TT0. At temper atures between 500 or GOO degrees, the NO changes rapidly into TTgO.' and Np04. Prober relations with either water or alkaline solutions ( caustic soda, lime water, etc.) Part I. Page 2. give either dilute nitric acid, or nitrates, cr a dilute mixture of nitrates.and nitrites. The higher the temperature, the greater is the con tent of nitric oxide produced, and the quicker is the transformation. Besides the necessity of producing a high temperature, the second chief requirement is to re move the nitric oxide formed as quickly as possible from the high-temperature zone, and to cool it down as quickly as possible. The reason is that with decreasing temper ature the opposite reaction takes place, and the nitric oxide dissociates into nitrogen and oxygon, so that if the cooling of the gas mixture containing the nitric oxide is too slow, the latter will break up into its con- stituants. Several commercial systems have been evolved as a result of experiment, and a brief review of them here will be inserted to give a general idea of the methods employed. They are treated more in detail in part two. In the Bradley-Love joy process, by mechanical means, (rotation of a wheel carrying one set of elec trodes which pass before a set of opposite and station ary electrodes], arcs are made and broke.:', at the rate of 6900 per second in the space through which the air is passed. The process has not been commercially success ful. Part I. PagQ 2. In the Birkeland - Eyde process, the arc is deviated magnetically ]rj means of a single phaso magnetic field, until the arc breaks, then a new arc is formed, and so on. This process has ^een used commercially since 1905 in Norway, f electric energy being very cheap at the plant, costing .094 cents per If.17.II. ) /mother method used by the Badische company, in a Norwegian plant is the Schonherr process,, the character istic feature of which is the use of a very long alter nating current arc, around which the air moves in a helical path. The paulding process, at a plant near Innsbruck, in Tyrol, uses an electric discharge quite similar to a horn lighhining arrester. The results obtained by these three commercial pro cesses, as given by the Standard Handbook, were given in 1909 as follows:- Grams H1T03 per E.17.H. Consent- _, ration Schonnerr 75 2.5 Birkeland Eyde. 70 2.*0 Paulding. 60 1. to l.*5 Part I. pa£.e 4# It seems evident that the most important factor in any of these processes the cheap cost of power. In the Northwest, altho waterpower abounds, it is not in the natural course of events, developed until there is a demand and market for it. And when so developed, other markets offer so much better remuneratation that it would be unprofitable to sell power at a sufficiently low price at this time to compete with the natural product. Another way of looking at it, however, is to con sider the advisability of the power company installing furnaces to utilize the off-peak load. It is well under stood that a power plant, to give satisfactory survice must be designed with a sufficient capacity to carry the maximum winter load, which usually comes, at least for the lighting load, form four to twelve P. I.I., about Christmas 2ime. Of cours, the plant can run on overload for this short.time, but the fact remains, that the average load factor of a up-to-date plant, ranges about fifty per. cent. This means that capital must be invested in machinery, equipment, etc. which works at its most effi cient capacity only a small part of the time. Therefore, if some arrangement could be made whereby the off-peak load could be utilised to produce dome commercial ne cessity, such as commercial fertilizer, the result would be almost clear profit, except for investment. Part T. Page 5. C.P. Stinmetz suggests another phase of this in the A.I.E.E. proceedings, May 1911, Vol X.X.X. No. 5 page 1021. "Another subject is the utilization of spare power and off-peal: po.ver. I am interested in the data given on the power required for irrigation, and the relatively small amount of po.ver it eosts to operate a -ramping plant for irrigation purposes. "Another use for off-pea1: power is the fixation of atmospheric nitrogen. We are rapidly approaching a time when we shall have to rly on fertilizers to maintain the productivity of our soil. Nov/ the commercial production ofnitrogen compounds by electrical power lias been con ducted successfully and economically; but only where the development of the water power has been extremely cheap, and where there was no market available for it,—as for instance in Scandinavia. We must however realize that the main part of the cost of installation of such industrial operations is due to the plant needed to convert the very dilute oxides into nitric acid, or solid nitrates for transportation. Therefore, a large part of the cost is due to the chem ical side of the production. When we come to intormittant use of the off-peak power, where the plant is used only for a part of the time, then the cost of the production rapidly increases, Part I. Page 6. due to the interest on the investment, and we find, very soon a point is reached where the production of nitrates would not be economical, even if the power cost nothing. Herein consists at present the groat difficulty of utiliz ing electrical power for the fixation of nitrogen. But since this results from the cost of concentration, then if ,/e could use the fixed nitrogen in a highly diluted state, we could save most of the investment, and so materially reduces the cost; and it would be economical. That means that this method of -sing off-peak power lends itself nicely to the combination with irrigation, We might use electrical power for irrigation and also for producing nitrates, and send out the nitrates as fertil izer with the irrigating water on a highly diluted state. In this way you could use a large amount of electrical power and get the benifit of intermittant and off-peal- power available in arid districts." UTILIZATIOIT OF ATMOSPHERIC ITITRCGEIT. What it Means to the Parmer. "by A. Benithsen. Director, Bradische Anilin-u Soda Faorik, Ludwi gshafen, a/RTI. Hote:- This article appeated in Tooth the Scientific American Supplement for ITov. 13,1909, and the Engineer ing and Mining Journals for Oct. 16,1909. And is an abstract of an address delivered at the 7th Internation al Congress of Applied Chemistry, London 1909. Part II. * 1767. Oxygen has hitherto "been considered bhe most im portant element of the atmosphere, since it is indis pensable to the existance of human life. Nitrogen, on the other hand has always been considered as an inert gas; in spite of this however nitrogen plans an import ant part in the nutrition of all living organisms, mak ing it necessary to investigate new sources for obtain ing nitrogen compounds.
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