Mar.,
I 9 13
T H E -70 URSAL OF I M D U S T R I A L AiVD EIVGIIVEERIiVG CHEMISTRY
proposition individually. The course to be adopted should vary with the local conditions, such as the price of fuel, the quantity of coke passed through the blast-furnace, and with the amount of power which can be used in the works themselves and by their subsidiaries, .as mines, cement works, etc., all of which afford a field for the use of gases now wasted, in addition to what can be sold to other undertakings. When coke-oven gas is available, as well as t h a t from blast-furnaces, the possible methods of utilization are largely increased. The adoption of rcgeneratib7e heating has greatly reduced the quantity of gas ivhich it isrnecessary to consume in the ovens themselves, so that fully j o per cent. of the total gases liberated are disposable for other purposes. I n the case: of the existing French works, Gouvy considers that the PrOFam to be adopted must be largely gok’erned by the character of the present steam plant, which i t is not always fillancially possible to modernize. IVhen, on the other hand, new works are being laid out, i t is generally feasible to arrange the power plant so t h a t i t is operated by the waste gases entirely. I t should, in such a case. be possible to operate by the waste gases the bloxving-engines, the electric power station of the works, and the rolling mills. If coke-oven gas is also available, it should, moreover, be possible to work thus the reheating furnaces, the steel furnaces, and the other accessory heating plant. The first essential to good results with blast-furnace gas is than o.5 to clean it, so that, as used, it does not contain grain of dust per cubic meter. This greatly increases the evaporat i v v poLver o[ any boiler heated \yith the gas, Thus, with the uncleaned gas, about 2 cubic meters are required per kilogram o f water evaporated, as comparcd with only I to 1 . 2 cubic meters per kilogram Jvith the uncleaned gas. The p e a t effect of cleaning on the evaporative efficiency is due to the fact t h a t the dust is an excellent non-conductor, and, if present, is deposited upon the heating surfaces, greatly impeding the transmission of heat across them t o the water. In a Westphalian works, where the cleaning plant reduces the dust content to less than 0 . 2 5 gram per crtbic meter, the consumption of gas is only 0.8 cubic meter 1)er kilogram of steam superheated to 250° C. ’The Same considerations are applicable to blast-heating stoves, o l ~,,.hich the dust deposit has a very prejudicial Its presence impedes the transfer of heat from the bricks to the gases, and viceTersa, and at the Same time, if a very hot blast is used, it acts as a flux, making the bricks waste rapidly, Cowper stoves, as usually worked, require from 50 to 60 per cent. of the whole of the furnace gases available, while if these gases are cleaned, the consumption for the Same blast temperature will be about only 40 per cent, of the total supply, Since, however, the gas is cooled in the cleaning process, special burners must lIe provided to insure its ignition, The costof cleaning to the limit stated should not exceed go,ooI46 per I,ooo cubic feet. engine-running the gas should be further purified, so as to I,ring its dust content below, as a maximum, o,03 gram per cubic meter. To purify the gas sufficiently for use in gasengines involves a n additional outlay over and above the cost of the preliminary cleaning of So.oor24 per I ,000cubic feet. Where coke-oven gas is available, still further economies can be effected. The by-products alone are worth from &.20 to *%.30 per ton of coal coked. If the ovens are fitted with regenerators, about 50 per cent. of the total volume of the gas evolved is available for use elseivhere. This volume varies with the quality of the coal from 2 jo cubic meters up to 330 cubic meters per ton coked, and its calorific value ranges from 3,500 calories up to j,soocalories per cubic meter. The cokeovens a t Heinitz, in the basin of the Saar, consume joo tons IVith the lvaste gases a central station of ro,jm ( J f coal daily. horse-power is operated and power is furnished to the surrounding district. The price realized a t the switchboard is $0.01 per kilowatt-hour, and the cost of generation, including capital
255
charges, is below~$o.ooq. A very suitable use for coke-oven gas is in heating reverberatory furnaces and steel furnaces: blast-furnace gas is hardly suitable for such purposes, although it is being tried in Germany.
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ABUSES IN WATER FILTRATION G , H, Pratt, at the last meeting of t,he N ~ i;rlgland ~ \ ~ \vaterAssociation, said t h a t the SUCCeSS a Jyater filtration plant depends, first, upon the selection of the method or purification best suited t o local conditions; second, upon the proper operation of the works after installation. slO,\. salld liltratiull for a waterhigh in algae is not to be recollllnclldcd, I , ~ ,,I~ the undue clogging of the beds, but by the use of acrutioii arid prefilters conditions may be greatly in1pr(,veti. I’laill filtration should not be depended upon to treat a \cry highly colored water; and the rates of filtration should nut 1)c c11a11gt.cl quickly, for such a practife tends t o disturb the bacterial CLctioil at the surface of the bed. A slow sand filtratioll \\.]licl, would handle a given watersatisfactorily might, as the at providence, R. I., be installed without covering the beds, In the case of rapid sand filters supervisioll must i)e particlilarly close, and constant chemical control mustbe maintained, ~-~ ~
THE COST OF HYPOCHLORITE DISINFECTION The following data relating to hypochloritc tlisinfecti~~n is
taken from Engineera% 67pNo’ I ’ I h : Commercial bleaching powder packed in sealed drunis Iioldiiig 7 0 0 to 800 Pounds each, with a guaranteed strength O f ,36 11) 38 per cent. of available chlorine, may be purchased ill carload lots for about $0.0125 per pound. -%ssuming a disinfectaiit containing 33‘/a Per cent. of available chlorine a t a cost of $0.02 Per Pound, the treatment of a selvage with 0.1 Part per I0O,ooO available chlorine would require 2 j pounds of disiufectant at a Cost for chemicals of $0.50 per million gallons. To produce complete sterilization, the cost \vould be well over $ 1 9.00 Per million gallons for sewages and the d%ents from contact and trickling filters, and would vary from $1.50 to over $19.00 for effluents from sand filters. To produce a qLlalit?. which would conform to the drinking water or roo-Io-j standard, the cost would Vary from 83.75 to over $19.00 per d l l i o u gallons for raw sewage and effluents from trickling filters, froill $7.50 to Over $19.00 Per million gallons for settled sewage, fro111 $15.00 to $19.00 per million gallons for strained sewage and COW effluents, be Over S19’Oo for septic sewage, tact and would vary between $1.75 and $9.50 per million gallons for the effluents from sand ‘Iters which Were not originally of t h a t quality to correspond t o quality. To produce a I000-IoO-50 standard, or*one which would be about equal t u that of the better class of st.-eams not seriously polluted, the coqt would be from $1.75 to $5.60 per million gallons fur ra\v sewage. These cost estimates are for chemical only, and do not inclu~lt. Operating and sinking fund charges*
THE PAPER INDUSTRY O F JAPAN Pafier (January I , 1913, p. 2 5 ) states t h a t after cotton-spitlninji, the manufacture of paper is the most important industry ( I [ Japan. As raw material, the so-called paper mulberry bush (Kodzu). Broussonetia fiapyrqera (mitsumata), serves. While the manrrfacture of domestic paper is very old, the production of ‘‘ €Sur(>pean” paper was first commenced by the Oji paper mill, workin: with rice-straw, rags and old paper. After the Saigon uprising in 1 8 j j , as a result of the establibliment of numerous printing plants, the demand for ISuropeali paper increased enormously. The manufacture of doniestic paper, mostly conducted with hand apparatus, is carried o n principally by the rural population as a secondary occupatioii,
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