Journal . ple, water boils at 100° C, but benzene boilsat about 80° C, toluene at 110° C, and the xylenes at 135-145° upwards. Naphthalene boils at 218° C, and creosote oil at ahigher temperature, and so by heating up this mixture of hydro-carbons known as Crude benzol first to a temperature of about85° C, all the benzene comes off first, and can be collected in aseparate storage tank. Then by raising the temperature to115c C. all the toluene can be got to boil over, and to 160° C. allthe xylenes. It should be noted that although these light spiritsare driven off, the impurities, naphtha
Journal . ple, water boils at 100° C, but benzene boilsat about 80° C, toluene at 110° C, and the xylenes at 135-145° upwards. Naphthalene boils at 218° C, and creosote oil at ahigher temperature, and so by heating up this mixture of hydro-carbons known as Crude benzol first to a temperature of about85° C, all the benzene comes off first, and can be collected in aseparate storage tank. Then by raising the temperature to115c C. all the toluene can be got to boil over, and to 160° C. allthe xylenes. It should be noted that although these light spiritsare driven off, the impurities, naphthalene and creosote oil, areleft behind in the still. These impurities are worked up intowhizzed naphthalene and clear creosote in a separate building. spirit thus obtained is still very impure, and requires tobe chemically washed. This is carried out in large cast-ironvessels fitted with mechanical agitators. The capacity of thevessels is about 3,700 gallons. 162 COAL AND ITS Fig. 2.—View of Benzole Rectification Plant. Front of Stillswith Washers Beyond. COAL AND ITS BY-PRODUCTS. 163 The once-distilled spirit is mixed with sulphuric acid (con-centrated oil of vitroil) and washed, the acid being run off and thespirit again washed with water to remove the spent acid. It isthen treated with one or two further washings of soda solution,and finally with water. This treatment removes from the spiritsome ammonia, pyridene, tar acids, and the remaining resinoussubstances. The spirit is still, however, not sufficiently is therefore redistilled in another still fitted with a fractionatingcolumn and dephlegmator. This apparatus is to control thetemperature of the vapours during distillation so that nothing isallowed to escape except the quality of spirit required. The benzol stills, condensers and separators are water-cooledvessels for condensing the vapours from the stills, and the sepa-rators are for separating the spirit from the water. Th
Size: 1305px × 1915px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade186, bookpublisherlondon, bookyear1861
