O c t . , 1913
T H E J O C R N d L OF I,YDCSTRIdL A S D ESGI-VEERISG CHEMISTRY
was produced a t the rate of 2,900,000 tons per year a t the Gary, I n d . by-product coke oven plant, on a mixture of 7 6 . 4 per cent Pocahontas and 23.6 per cent high volatile coals. The conservation of coal through producing this amount of coke in b y product ovens instead of bee-hive ovens amounts to about 1,190,ooo tons per year. It has been found by the United States Steel Corporation t h a t the coke produced in by-product ovens, when properly made, is fully equal in quality to t h a t obtained in beehive ovens; and t h a t it is possible to utilize a larger variety of coals, when properly selected and mixed, including coals which up t o the present time have been practically regarded as “noncoking.” and make a highly satisfactory metallurgical coke. The by-product plant can be erected near the blast furnaces and it is practicable t o ship to it coking coals from any radius within favorable freight rate; this, however, is not the case with the bee-hive ovens, which, in most cases, are placed near the coal mine which supplies the coal, and, when the mine is exhausted, the bee-hive plant has t o be abandoned. Blauvelt pointed out t h a t the first ovens in this country coked 1 4 tons of coal per oven per 2 4 hours, and t h a t 2 j ovens, with a carbonizing capacity of I I O tons a day, were regarded as the proper unit for one crew of men. “The oven of to-day is carbonizing 20 tons per day, and practically the same crew of men, with the help of modern machi will handle j o ovens or more, carbonizing 1,000 tons per d He stated that from 40,000,000 t o jo,ooo,ooo feet per day of illuminating gas from coke ovens are now produced and sold in the Vnited States. The following points were indicated by Blauvelt as important to a well-designed oven: Largest yield of surplus gas; ability to substitute producer gas for oven fuel gas; maximum yield of by-products; maxirnun yield of good coke ; shortest coking time ; lowest cost of operation and repairs; simple and strong, with weight properly distributed. -4twater called attention to the fact t h a t the recovery oven has achieved a definite place as a part of the steel-making process, and t h a t it presents economies and advantages with which the present-day steel manufacturers must reckon. bleissner had referred to the employment of benzol as a motor fuel; Atwater cited the case of a truck engaged in general city delivery work. On a six months’ test with benzol alone as a fuel, a gallon of benzol yielded 1 5 per cent more work than a gallon of gasolene; based on an equal number of heat units supplied the efficiency was about the same. “NERADOL D”, A SYNTHETIC TANNIN Stiasny, in the course of a paper on artificial tannins,’ gives an account of the production of “ syntans ” (synthetic tannins), one of which products has been placed on the market by the Badische Company, Ltd., under the name of “Seradol D.” Syntans are condensation products which may be produced either by heating phenol; with formaldehyde in a slightly acid solution and solubilizing the resinous products thus obtained by means of sulfuric acid, or they can be made by first sulfonating the phenols and then condensing them with formaldehyde under such conditions that only soluble products are formed. “Neradol D ” resembles, in its appearance, a vegetable tannin extract of bright color. The analogy between this product and natural tannins is shown by the following behavior of “ Seradol D : ” 1ts”water solution is of a semi-colloidal character, passing a semi- permeable membrane only slowly and giving n precipitate with gelatine solution. Iron salts produce a deep hluish violet coloration, and a IO per cent solution of iron alum is a suitable means of controlling the course of “Neradol D ” tannage; this is done by placing a fexv drops of the iron solution 011 the fresh cut of a half-tanned hide, when the tanned layers are colored deep blue. Lead acetate as well as aniline hydrochloride give precipitates with “h-eradol D.” Stiasny makes 1
Ciiani. i I - o r l d . 2 , S o . 7 , 2 1 G .
See also THISJ O U R X A L , 6 , 7 0 5 .
863
special mention of the very bright color of solutions of “Keradol D ” and of the complete solubility in cold water-distinct advantages over the ordinary tannin extracts. It is said that the real character of “Seradol D ” is t h a t of a light leather tannin, and that sumach and gambier are those natural tannins whose effects have the greatest resemblance to t h a t of “rieradol D.” It may be used a s a bleaching agent of dark-colored leather; in this case the retanning action of this artificial tannin prevents loss of weight, which accompanies most of the usual methods of bleaching heavy leathers. ___THE CAUSES AND PREVENTION OF SEWER PIPE FAILURES
It has been stated that, with the inclusion of cement pipe and the cost of labor and materials, it is probable t h a t $75,ooo,ooo are spent annually in this country in the construction of sewers and drains. This expenditure has been largely based upon a visual examination of the pipe or tile, and a conjectural inference as to the loads which it may be expected t o carry safely. IVith a view of developing a correct method of calculating the loads on pipe and of preparing adequate standard specifications for the quality of drain tile and sewer pipe, the Engineering Experiment Station of Iowa State College has conducted a series of experiments, the results of which are reported by Engineering Record. 68, 46; these are presented a t some length on account of their interest to the ceramic and sanitary engineer. The following general conclusions reached as t o the failure of drain tile and sewer pipe in ditches are based on extensive data obtained from drainage engineers: I . There h a r e been a large number of failures of drain tile and sewer pipe by cracking in ditches, and there is a wide prevalence of cracked pipe in existing sewers and drains. The cracking is generally confined to pipe larger than 14 in. in diameter. Engineers have not properly appreciated either the extent or the importance, nor have they fully understood the causes, of cracking of drain tile and sewer pipe in ditches. 2 . The principal cause of the cracking of the drain tile and sewer pipe in ditches is simply that, as a t present manufactured, sizes larger than I j in. in diameter are very generally too weak to carry the weight resting upon them from more than a few feet depth of ditch filling. 3. In very many cases it is entirely impossible to prevent cracking in ditches of drain tile and sewer pipe as a t present manufactured by any possible reasonable amount of care in bedding and laying the pipe and refilling the ditches, -1material difference in the carrying power of the pipe, however, can be made by proper care in bedding and laying. 4. Drain tile and sewer pipe crack more readily in ditches with hard bottoms than when laid on slightly yielding soils j . I t is reasonable, advantageous and necessary to require the pipe-laying contractor carefully t o shape the bottom of the ditch to fit the under half of the pipe surface, and to bed the pipe carefully for this distance in sand or granular soil, so as to secure a firm, uniform bearing. 6 . Drain tile and sewer pipe are so rigid and crack from such slight distortions, as compared with the yielding of the most solidly tamped earth filling, t h a t it is not feasible to prevent cracking by tamping the ditch filling on each side of thc pipe a t the midheight. Such side tamping, however, should always be required, and thoroughly done, for i t is of great value in preventing the collapse of pipe after it is cracked. j. IThere the pipe is found to crack in spite of faithful observance of the specifications stated in j and 6 above, the only effective remedy, other than using stronger pipe, is to bed the pipe in concrete up to the midheight. Such concrete can be lean, and need not be thick if the soil is firm, but must thoroughly fill all spaces between the lower half of the pipe and the bottom and sides of the ditch.
864
T H E JOCRLVdL O F 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 X I S T R Y
8. The width of the ditch a t the level of the pipe makes a great difference in the weight of filling resting on the pipe, this weight being greater the wider the ditch. Moreover, the narrower the ditch a t the midheight of the pipe, the more effective is the side support against the collapsing of cracked pipe. 9. Where the ditch filling over the pipe is rammed in layers during refilling, there is serious danger of cracking large drain tile and sewer pipe by using too heavy rammers 2nd too thin a layer just above the pipe. IO. While large amounts of cracked drain tile and sewer pipe are standing without collapsing in existing drains and sewers, the stability of cracked pipe must be considered precarious, as has been demonstrated by numerous collapses. 1 1 . Cracked pipe is especially dangerous in tile drains and storm sewers, for the reason that, in the best engineering practice, it is not found practicable to make the capacity of drains and sewers equal to the most exceptional floods. Hence they are certain eventually to be overcharged, and to run under pressure, and the collapse of cracked pipe is likely to result a t such times from the softening of the soil by water escaping through the joints and cracks. The general principles of the theory of loads on pipes in ditches, which were borne out by a long series of laboratory and field tests, may be in part summarized as follows: I . The weight of the filling in a drainage or sewerage ditch, a t the time of maximum load on the pipe, is carried partly by the pipe, and partly by friction against the sides of the ditch. Cohesion greatly reduces the loads carried by the pipe a t ordinary times, after the ditch is refilled and partly consolidated, except in the case of clean sand, or gravel filling, but does not appreciably affect the maximum loads. 2 . The maximum loads on pipes in ditches, due to the weight of ditch-filling materials, will usually occur a t the time of the first very thorough surface flooding of the ditch filling after construction, when there is a large settlement of the refill, but there is possibility of their occurring later. a t the time of extreme saturation of the ditch filling by surface flooding of the ditch and by overcharging of the drain or sewer. The maximum loads may even be postponed for many years in some cases, as is frequently shown by settlement of the filling in old ditches during paving construction. 3 . Safe values of the ordinarymaximumloadsonpipes in ditches, due to the weight of ditch-filling materials, can be computed by the formula W = CwBZ, using the values of C given where W = load on pipe in ditches, in pounds per linear foot; C = coefficient of loads on pipes in ditches; w = weight of ditch filling material, from 90 to I Z O lb. per cubic foot; B = breadth of ditch a t top of pipe, in feet; and H = height of fill, above top of pipe, in feet.
1701. j,
NO.10
the end thrust, and segmental brick of the proper radius, with thin points of fire clay. If thus constructed, i t will stand up under the high heat to which it is subjected.
The auxiliary air supply to the hollow bridge wall enters through the duct B B , controlled by the damper D ; to the transverse Passage c, which has a clean-out door; and then up and
FIG.2-HORIZONTAL
SECTION T H R O U G H
BOILERSETTIXC
out through l,'c-inch spaces between the fire brick in the crown of the bridge wall, The air is warmed by passage through the
-
A NEW DESIGN IN BOILER SETTINGS A modification of the usual horizontal tubular boiler setting is described in a recent bulletin issued by the Travelers' Indemnity Company, of Hartford, Conn. The two distinctive features of the settin: are the furnace arch A A , and the air duct B B , admitting secondary air through the bridge wall. I n the ordinary form of setting for horizontal tubular boilers, the fire sheet of the shell, relatively very much cooler than the burning gases in contact with it, acts as a check upon combustion by its chilling effect and is itself subject t o destructive strains. The deflecting arch, as shown by the sections, ends immediately back of the bridge wall, and the faces of fire brick are staggered to form projecting rings on its surface. This arch facilitates more staisfactory combustion of the furnace gases, and, in addition, distributes over the shell and tube surfaces the excess of work usually put upon the fire sheet. Both of these increase the efficiency of the boiler as well as add to t s life. The arch must be carefully laid, with good blocks for
..-..-.. GRATE
FIG. 3 - s E C T I O S
LEVEL
THROUGH I G N I T I O N A R C H
ducts, and is then introduced to the burning gases a t what has been experimentally determined to be the best point for its addition. - .._.. ~~~~
~
~
A SEPARATOR FOR DRY MATERIAL
F. 0. Stromberg, of Seattle, Wash., has devised an apparatus for the dry separation of ground ore, etc., which consists of a f a n or other means of introducing an air blast, which passes.
