380
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERIiVG C H E M I S T R Y .
and these latter are employed to prepare for the Fuller mills. Both the raw materials and the clinker are ground to a fineness of 96 per cent. passing a I O O mesh sieve. The clinker may be classed as difficult to pulverize, as it is always burned hard in order t o secure high quality. By referring t o the table it will be seen t h a t 3 0 . 7 per cent. of the power is required to prepare the material for the kilns and 4 5 . 2 per cent. for the pulverizing of the clinker. The other 2 4 . I per cent. is employed in the minor departments and represents also the losses in transmission lines, etc. The distribution of the power among the various departments depends, of course, largely upon both the installation and the materials to be ground. From a ball and tube mill plant the following figures are obtainable : Per cent. Crushers and dryers.. ..................... 5.6 Raw material pulverizing. . . . . . . . . . . . . . . . . . 2 9 . 8 Kilns. ............................ 7.0 Finishing mills.. .......................... 39.6 Coal mill and miscellaneous. ................ 18 .O
With very hard raw materials the power required t o prepare these for t,he kilns has risen t o 50 per cent. of the total power employed, but usually this department takes a little under one-third of the total power, a n d the clinker mill slightly more than this. Roughly speaking, we should be able, on an average, to prepare material for the kilns at an expenditure of between ~j and 2 0 kw. h. per t o n : or, from 5 t o 7 kw. h. per barrel of cement produced. For the operation of the kilns and dryers, including the pulverizing of the coal for the former, about 2 kw. h. per barrel of cement should be sufficient, while, lor the reduction of the clinker to cement, a final 7 to I O kw. h. will be required, or, in all, from 14 to 19 kw. h. (or 0 . 7 8 to 1.06 h. p. day) per barrel. Rating a km. h. as equivalent to about 3 pounds of ordinary steam coal (40,000B. t. u . ) , a barrel of cement would represent from 42 to 5 7 pounds of coal for power and from 80 t o I O O pounds for burning, or from 1 2 2 to 157 pounds in all. The question has been raised as to the advantage of employing the wet process for burning, thereby securing a more easily ground clinker. I t is also claimed t h a t the wet process allows the raw materials to be more easily ground. The wet process, however, increases the fuel required for burning a t 1ea.st one-third, or 30 pounds a t the lowest. As this quant i t y of coal is usually rated in practice as about equivalent t o I O kw. h . , or almost as much power as is required to grind both the raw materials and the clinker, the wet process on the score of power economy a t any rate does not seem to promise much. A careful analysis of the power question, particularly where fuel is cheap, would seem to indicate t h a t it is much more important t C J consider grinding ma chinery with a view to repairs and attendance than with a view to saving of horse-poxver. Of course, all things being equal, the saving of horse-power is essential, but in choosing machinery, economy of upkeep is fully as important as economy of power.
May, 1912
One kw. h. will usually cost about half a cent t o generate and will often cover the range of power per barrel between the -various types of well-known pulverizers used in the cement industry. I t may not, however, cover the difference in cost of repairs, etc. An analysis of the cost sheets of most cement plants will show t h a t the cost of attendance and repairs in the raw and clinker grinding departments is fully as high as the cost of the power delivered to them. For example : Repairs.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.55 2.44 0.04
-
Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.03 3.09
-
Total. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.12
Indeed, the cost sheets of the average cement mill will show repairs t o be a larger item t.han power. A good example of this is the following: Per bbl. Operating labor.. . . . . . . . . . . . . . . . . . . . . . . . Kiln coal.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power ................................. Packing.. ... Office, Iaboratory, e t c . . . . . . . . . . . . . . . . . . . .
$0.20 0.10
0.103 0.82
0.034 0.016 $0.535
This data is taken from the books of a highly successful new mill and t h e figure obtained is only achieved b y very careful a n d efficient management. The figures for power and repairs m a y both be considered low-and serve well t o show the relative relation between the two items. I n selecting the type of machinery t o be installed in a cement plant, therefore, it is not sufficient t o consider merely the relative power consumed b y the different types per barrel of the product obtained, but also the repairs. The mechanical engineer has often shown a tendency to make selections based solely on power-efficiency tests made in the machinery manufacturers' experimental plant, only to find out on actual operation t h a t the cost of repairs more than offset any saving in the coal bill. NEW FORMS OF APPARATUS FOR GAS ANALYSIS.' B y F. M. WILLIAMS. Received IIebruary 1 5 , 1912.
Probably the best known and most widely used apparatus for gas analysis is t h a t of Orsat, or one of its many modified forms. The numerous modifications which have appeared from time t o time bespeak a high tribute t o the general utility of this instrument and also a keen desire. t o remedy its shortcomings. The faults in the original Orsat apparatus may be briefly summarized as follows: First. Although portable, i t is much too bulky. I find its size may be reduced nearly fifty per cent., still retaining the I O O cc. measuring burette and without impairing accuracy a t any other point. Second. I t is awkward in manipulation, due t o position of burette on the right-hand side, necessita1 Paper presented at meeting of Division of Industrial Chemists and Chemical Engineers, Washington, December, 191 1.
May,
1912
OF I.ZTDCSTRIAL A M D ESGI,VEERIATG C H E M I S T R Y .
T H E JOURl\-AL
ting either left-handed manipulation or crossing the hands in t h e line of vision n-hile operating. Third. The design of its absorption pipettes with U-tube or goose-neck reservoir is particularly fragile and liable t o breakage a t the bend, with the attendant unpleasant deluge of highly concentrated caustic solutions.
FIG.1.
381
are shown, the simple and t h e bubbling, either form slipping interchangeably into the pipette jar or solution reservoir, with the closure at the top effected b y an ihexpensive rubber band. Both forins are so constructed as t o prevent the thin glass tubes from falling out when the pipette is removed from the jar. The simple pipette needs little comment. The bubbling pipette, which is exceedingly rapid in absorption, owes its high efficiency t o the fact t h a t the gas is not only caused to bubble through a long column of liquid b u t t h e bubbles are also finely broken up b y t h e thin glass tubes with which the pipette is filled and a large absorption area is presented by t h e wet surface of these tubes. While the arrangement at the top of this pipette somewhat resembles t h a t of Babb, this differenceiis t o be noted-in the original Babb the long capillary tube which passes to the bottom of the pipette enters at t h e center or highest point while in the form here presented the long tube enters a t the side, allowing the short capillary, through which the liquid is brought u p t o the reference mark, to be placed a t the highest point, thereby completely removing bubbles from t h e surface of the liquid. The mounting of the glassware in the case is such as t o render all parts accessible and instantly removable for cleaning or recharging. The T’s a t the top are held in a channel piece, G, resting in saddles. The front half of the cross-piece, H , is removable b y lifting from the supporting saddles a t the sides of the case. The exposed portions of the inside of the case are rubber covered. The detachable three-way T stopcock, with hard rubber pump and valves shown in Fig. 2 , makesTit possible to take a dry sample of gas directly from t h e source of supply, eliminating the inaccuracy and bother of collection over water, transference, etc.
This form of pipette is difficult t o wash and refill and is also slow in its absorption of gas. I n t h e modifications which are now submitted t o your favorable consideration, the above noted objections have been overcome. First. You will note a marked reduction in size. Model “A,” arranged for the complete analysis of combustible gases, occupies a space of only I Z x 4 x 1 7 M inches, syhile t h e flue-gas apparatus, Model B,” is only 9 % X 4 x 1 7 1 / ~ inches. The measuring burette is placed P at t h e left side, allowing freedom of t h e right hand in manipulating stopcocks, etc. A special design of explosion burette is indicated in Fig. 2 , with terminals permanently connected t o bindingF posts on outside of case. The bulb is placed lower upon the tube, permitting 1 5 cc. of clear graduation to be read on the small caliber of the FIG.Z.-WILLIAXS IMPROVEDGAS APPAIUTUS burette above the swell. MODELA. The next point to be noted is the FOR[COMPLETE A N A L Y s 1 s o F COMBUSTIBLE GAS-CARBON D I O X I D E , I L L U M I N A X T S , OXYGEN. CARBON absorption pipette, of which two forms ~ h f O N O X I D E ,HYDROGEN, ?rlETHANE AND XITROGEN. ‘ I
382
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y .
May, 1912
any desired period of time. This method of control has some advantages, at least, over a recording COS instrument, in t h a t its accuracy a n d , adjustment are unquestionable and we are also able t o determine carbon monoxide, which is sometimes a n important factor.
L
9
t
-
i
i
i I
l
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.
I
i
1 P
c ---------&-WILLIAMS' IMPROVEDGAS FIG. 4.-WILLIMIS' IMPROVED GAS APPARATUS, MODEL B. FORANALYSIS APPARATUS, MODEL C. FORANALYSISOF FLUEGAS-CARBON DxoxOF FLUE GAS-CARBON DIOXIDE,OXYDEN, CARBON MONOXIDE. IDE, OXYGEN,CARBON MONOXIDE.
FIO.
After connection with supply the pump is operated discarding the gas in the connecting line until the fresh sample is brought up to the apparatus, when b y turning the stopcock and lowering the water-level bottle the measured sample is taken directly into the burette. This feature is especially advantageous in fluegas analysis, when the apparatus may be Permanently housed in the boiler-room with a line of piping running t o the flues enabling an accurate determination of firing conditions t o be quickly made a t any time. The introduction of a n aspirator tank into the line also enables an average sample to be taken covering
J
t FIG. PIPETTE DETAILS.
I n conclusion, the writer believes t h a t years of experience with various kinds of gas apparatus warrants t h e statement that the form here described is f , convenience, without an equal in the aCCuraCY, rapidity and minimum liability t o breakage. LABORATORY OF F . M. WILLIAMS, WATERTOWN. N. Y. ,
CURRENT INDUSTRIAL NEWS
I
B Y W. A. HAMOR.
TANNERY WASTES IN SEWAGE. Gloversville, N. Y., the center of the glove industry in this country, has had a particularly trying experience with damage suits against tanneries located there, and under pressure of adverse verdicts, supported by an extensible injunction, the city has been obliged to adopt a new system of sewage disposal. In addition to the glove manufactories, Gloversville has 26 tanneries, at which glove leather and the finer grades of shoe leather are prepared. All of the domestic sewage, tannery waste (excluding hair) and mill refuse were formerly emptied directly into an adjoining creek, and it was by the riparian owners on this creek that the successful litigation was begun. The gross weight of wet and dry hides tanned annually in Gloversville amounts to 9,000,000pounds, and about 8,000,000 pounds of chemicals are used in the tanning processes. The analyses of the creek water indicated that the quantity of wastes which found its way from the tanneries to the creek averaged over 30,000 pounds per day; and it has been estimated that fully one-half of the total weight of the hides and chemicals used in the processes of tanning was eventually conducted into the creek. The City Council of Gloversville passed an ordinance requiring all wastes from the tanneries to be passed through settling tanks before discharging into the intercepting sewer. Since this ruling, it is reported that if the tanks are kept properly
cleaned, their efficiency is very satisfactory. The suspended matter occasionally exceeds 2 , 5 0 0 parts per million; but over 90 per cent. of the suspended matter is said to be removed in some cases, although the average is about 7 0 per cent. The Gloversville situation is one of great importance to chemical manufacturers, and to tanners in particular, in view of the question of municipal power over nuisances in waters (see, in this connection, L. R. A., 38, 324; 39, 649,681). Sedimentation in large fields had been found to be unsatisfactory and expensive for the treatment of strawboard waste liquor, in which case the operators proceeded on a wrong principle (see Water-Supply and Irrigation PaPer No. 189, U. S. Geological Surzey, 1906,p. 19). However, recent results a t Gloversville seem to show that tannery wastes may be treated without resorting t o mechanical filtration. In 1901,a very important question arose in England as to whether the effluent from a tannery could be excluded from its sewage system by a rural district council on the ground that it caused a nuisance (Sevenoaks Rural District Council z'. Whitmore, Imp. Inst. I . , July, 1901). The defendants had been called upon in 1886to erect tanks on their premises in which the effluent from their works might settle before being pumped on to a sewage farm. They complied with this order, but their later refusal to cut off their connection as ordered led to &hesuit in 1901.
