Transactions

650 TRANSACTIONS OF THE A.S.M.E. OCTOBER, 1941authors in this investigation were not referred to a standardtemperature.)Although the authors do not use the ammonia correctionsmentioned in the introduction to their paper, it should be pointedout that the value assumed by them is higher than experimentallydetermined values found by Rummel and by Schwartz.Rummel15 found 7.3 micromhos per ppm nitrogen ammonia forammonia alone in water, and 8 micrornhos per ppm nitrogenammonia for carbonated-ammonia solution. Schwartz16 reported8 micromhos per ppm nitrogen ammonia.Nomenclature. It is observed that the terms “total dissolvedsolids,” “total solids,” and “dissolved solids” appear to be usedinterchangeably throughout the paper. The following definitions17on water for industrial use are given by the AmericanSociety for Testing Materials:2 (e) Dissolved Solids.11 “Dissolved solids” comprise thedried residue from evaporation of the filtrate, after separation ofsuspended solids.2 (/) Dissolved Salts. “Dissolved salts” are the sum of theindividually determined ions in a complete analysis.The terms “dissolved solids” and “dissolved salts” are appropriatefor use and applicable to the subject m atter discussed bythe authors.A. E. Kin'REDOE.1* Preceding a broad discussion of steamsamplingequipment the writer wishes to commend the authorson the compact and effective mechanical design of the equipmentthey had described, in the light of the purpose for which thisequipment was developed. Reference to the field of applicationfor which this equipment is designed is purposely made becausethere is a fair distinction to be made between equipmentdesigned to serve the single function of degasifying the steamsample for conductivity test and that for the dual function ofboth degasifying the steam sample for conductivity tests whileyet permitting the collection of the separated gas for analysis.An appreciable demand for equipment of the latter type seemsto be indicated by the need for detecting quickly the generationof hydrogen in high-pressure boilers and superheaters, resultingfrom the dissociation of steam; appearance of hydrogen in thesample, of course, indicating a dissociation and active corrosionby the free oxygen so liberated.It seems impossible to discuss a paper of this kind technicallywithout first establishing a few points of fundamental fact. Inany physical process of gas removal there is no possible designwhich can produce an absolute zero in fact. Different designsemphasize different advantages but, in such a process, dependingupon a driving force between the solvent and the solute, the endpoint must, from the nature of the process, still have an actualif not measurable difference between the actual value, whethermeasurable or not, and absolute zero. Appreciation of this factis necessary to give proper evaluation to the different methodsof design of degasifying equipment. This paper emphasizes theuse of clean steam for flushing the fractionating tower and acounterflow arrangement of the condensed sample and the flushingsteam. Both of these elements are in themselves desirablefeatures if they can be utilized without sacrifice of other desir­16 D ata from curve prepared by J. K. Rummel and availablethrough the courtesy of The Babcock & Wilcox Company, NewYork, N. Y.le Footnote 13 of this discussion, refer to p. 729.17 “ Tentative M ethods of Reporting Results of Analysis of IndustrialW aters,” D596-40T A.S.T.M . Book of Standards, Supplement1940, p art 2, p. 541.18 The term “ total dissolved solids” is not defined on pp. 56 and92 of Bibliography (4), but what appears to be an ambiguous definitionappears on page 151.18 Chief Engineer, Cochrane Corporatien, Philadelphia, Pa.able features. The point we wish to make is that proper evaluationof all the elements entering into the degasifying process arenecessary to determine the best cycle of operation for any particularequipment.There are three basic factors to be considered in the design ofdegasifying equipment. These are:1 The creation of a satisfactory equilibrium condition.2 The selection of an advantageous operating temperature.3 The provision of an effective degasifying means.Equipments, designed to operate at relatively high vacuumsand temperatures below 100 F, very easily produce satisfactoryequilibrium conditions but are greatly handicapped by thehigher viscosities of water at these temperatures. The higherviscosity of the water places a greater burden on the deaeratingmeans in spite of the favorable equilibrium conditions. Degasificationat low temperatures can be accomplished but operatesunder a definite handicap.Operation of degasifying equipment at around atmosphericpressure with counterflow of steam and water provides a suitableequilibrium condition and utilizes the advantageously low viscosityof water at this temperature. In spite of the favorableequilibrium condition and operating temperature, the controllinglimitation on the design of degasifying equipment for atmosphericoperation will be the actual degasifying means. The latter isvery apt to be handicapped and compromised in the design ofsmall compact test equipment such as that under discussion.Because the limiting factor in the design of degasifying equipmentis the third element of the three tabulated, the design ofequipment of the writer’s company to be later described, utilizesthe most effective degasifying means known, i.e., the atomizingmethod, at a very slight sacrifice to the most favorable equilibriumcondition for the purpose of obtaining the greatest neteffective result.If a condensed-steam sample, containing as much as 1 cc per 1of oxygen is flushed with an equal quantity of steam at atmosphericpressure in an open chamber without a counterflow arrangement,all but 1 part in 100,000 of the dissolved gas in theliquid would be transferred to the steam, if equilibrium werereached. That is to say, when the quantity of flushing steamequals the quantity of condensate to be deaerated and the steamitself contains 1 cc per 1 of oxygen, the presence of that oxygenwould support in solution in the liquid only 0.00001 cc per 1.This value ranges somewhere between 0.2 and 1 per cent of thesmallest quantity of oxygen that can be determined by any knowntest method. It emphasizes the fallacy of limiting equipmentdesign to conditions which are theoretically advantageous butpractically worthless. For the same reason, we choose to placeemphasis, in the design of our equipment, on effective means ofdegasification. Similar values apply to other gases, proportionateto their solubility and inversely proportionate to their specificvolume at the operating conditions.In contrast to the equipment presented by the authors, wewish to refer to equipment designed by the writer’s company toserve all the purposes of the former equipment and, in addition,to make possible selection of gases removed from the steamsample for analysis. In the foregoing, we have briefly outlinedreasons for placing emphasis on the effectiveness of the deaeratingmeans as opposed to the obvious need of giving attention tosatisfactory equilibrium conditions. In the degasification of asteam sample, involving the removal of carbon dioxide and ammonia,there is additional reason to use the most effective meansof degasification possible.Solutions of both carbon dioxide in water and ammonia inwater form loose chemical combinations of carbonic acid andammonium hydroxide respectively. Each also ionizes the solu-