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Steam-boiler economics
CURRENT ToPIcs.
291
alloy is that it removes those features of irregularity which have given steel a bad name for its unreliability in certain directions. In a recent trial of the alloy in basic open-hearth by one of the large steel makers, it was found that I ~ per cent. of alloy was necessary to remove the last vestiges of brittleness and of blow holes, and this made the steel so dense that it was unusually strong, and became the source of much comment and investigation.
Alloys for Permanent Magnets. ANon. (Amer. Machinist, xxxiv, IO75.)--The addition of chromium to pure iron without carbon does not give good results, according to G~nie Civil. An alloy containing 5 to 6 per cent. of chromium with o.75 to I per cent. of silicon and o.3 to o.5 per cent. of carbon is excellent. An alloy containing 8 per cent. of molybdenum, o. 3 per cent. of vanadium and o.6 per cent. of carbon makes good permanent magnets, which preserve their magnetic properties above IOOO° C. Alloys of tungsten and iron are useless, except one which contains 4 per cent. of tungsten and o.4 per cent. of vanadium; this makes an excellent permanent magnet. Steam-boiler Economics. Edit. (Eng. Record, lxiii, 689. ) Mr. Geo. H. Barrus reviewed the results of 3 ° years' experience in steam-boiler testing, in a paper read before the Congress of Technology at Boston, Mass. This is a paper worthy the attention of steam-users. Its main points may be recommended thus: The economy resulting from the admission of air over the fuel bed, in a boiler of the horizontal return tubular type, is stated to be such that the evaporation per pound of combustible was increased IO per cent,, from IO.23 to 11.35 lbs. from and at 212 ° F. ; the draft between damper and boiler being about o.3 inch, and the temperature of the escaping gases was 51o ° F. with air admission, and 515 ° F. without it. The disadvantages of a thick fuel were clearly shown. With a fire-thickness of 12 inches the percentage of carbon monoxide in the gases was I.I compared with o.I with a 6 inch fire, and the evaporation was 11.5 lbs. with the thicker fire and I2 lbs. with the thinner. The importance of a clean heating surface is clearly shown. Incomplete combustion is often responsible for relatively low efficiency. Forcing the output reduces the efficiency. Interior scale and neglect in maintenance also result in low evaporation.
To Prevent Dusting of Concrete Floors.
ALBERT ~V[OYER.
(Eng. Record, lxiv, I 6 . ) - - A f t e r washing thoroughly with clean water, and scrubbing with a stiff broom or scrubbing brush, allow the surface to dry and apply a solution of one part water glass (sodium silicate), 4o ° Beaum6, and 3 to 4 parts water, the proportion of water depending upon the porosity of the concrete in the floor surface to be treated.
291
alloy is that it removes those features of irregularity which have given steel a bad name for its unreliability in certain directions. In a recent trial of the alloy in basic open-hearth by one of the large steel makers, it was found that I ~ per cent. of alloy was necessary to remove the last vestiges of brittleness and of blow holes, and this made the steel so dense that it was unusually strong, and became the source of much comment and investigation.
Alloys for Permanent Magnets. ANon. (Amer. Machinist, xxxiv, IO75.)--The addition of chromium to pure iron without carbon does not give good results, according to G~nie Civil. An alloy containing 5 to 6 per cent. of chromium with o.75 to I per cent. of silicon and o.3 to o.5 per cent. of carbon is excellent. An alloy containing 8 per cent. of molybdenum, o. 3 per cent. of vanadium and o.6 per cent. of carbon makes good permanent magnets, which preserve their magnetic properties above IOOO° C. Alloys of tungsten and iron are useless, except one which contains 4 per cent. of tungsten and o.4 per cent. of vanadium; this makes an excellent permanent magnet. Steam-boiler Economics. Edit. (Eng. Record, lxiii, 689. ) Mr. Geo. H. Barrus reviewed the results of 3 ° years' experience in steam-boiler testing, in a paper read before the Congress of Technology at Boston, Mass. This is a paper worthy the attention of steam-users. Its main points may be recommended thus: The economy resulting from the admission of air over the fuel bed, in a boiler of the horizontal return tubular type, is stated to be such that the evaporation per pound of combustible was increased IO per cent,, from IO.23 to 11.35 lbs. from and at 212 ° F. ; the draft between damper and boiler being about o.3 inch, and the temperature of the escaping gases was 51o ° F. with air admission, and 515 ° F. without it. The disadvantages of a thick fuel were clearly shown. With a fire-thickness of 12 inches the percentage of carbon monoxide in the gases was I.I compared with o.I with a 6 inch fire, and the evaporation was 11.5 lbs. with the thicker fire and I2 lbs. with the thinner. The importance of a clean heating surface is clearly shown. Incomplete combustion is often responsible for relatively low efficiency. Forcing the output reduces the efficiency. Interior scale and neglect in maintenance also result in low evaporation.
To Prevent Dusting of Concrete Floors.
ALBERT ~V[OYER.
(Eng. Record, lxiv, I 6 . ) - - A f t e r washing thoroughly with clean water, and scrubbing with a stiff broom or scrubbing brush, allow the surface to dry and apply a solution of one part water glass (sodium silicate), 4o ° Beaum6, and 3 to 4 parts water, the proportion of water depending upon the porosity of the concrete in the floor surface to be treated.