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INDUSTRIAL AND ENGINEERING CHEMISTRY
ciency of heat-energy recoveries in carbonization-as, for example, the utilization of the sensible heat in the discharged coke-will aid materially. NEWDEVELOPMENTS IN THE CARBONIZATION FIELD From the foregoing considerations it readily becomes apparent that carbonization of coal, in order t o gain ground as an aid in the application of fuel, especially if applied in steam-power production, must make improvement along one or all of three lines. It must (1) lower its expenditure of heat energy, or (2) lower its plant and operating costs per unit of output, or (3) increase the “form value” of its products more nearly t o balance the costs of conversion. The prevailing high temperature coke- and gas-making processes are progressing in some small degree along the first-named line, in more marked degree along the second, but almost not at all along the third line. Their progress on the second line is notable and creditable. Rate of output is being increased by improvements in design and in structural materials, and operating costs are being reduced. Vertical gas-retort plants with their simplified charging and discharging equipment, their lower operating labor cost and their adaptability t o steaming for increase of gas-making capacity, contribute in important measure t o the advance in this direction. Low-temperature carbonization processes and those “complete gasification” processes which embody low-temperature carbonizing as an element in their operation, lead toward advances along the third line named above; in other words, they show prospects of yielding tars, oils, and coked residues of an enhanced “form value” for special purposes. If they do not succeed in doing this in marked degree, they will fail. For in capacity or rate of output, and therefore in production costs, the low-temperature processes compare very unfavorably with the established high-temperature processes. The great virtue of low-temperature carbonizing is the saving of the oils from the coal-the preserving of these presumably “high form-value” materials from cracking and degradation into soot and gas carbon. The oil yield is doubled; and, if all or nearly all is found‘applicable to motor fuel use, both in light-fuel motors and the Diesel heavy-oil motor-as is claimed to be possible-the form value in this product should compensate for much of the increased plant and operating costs. The coked residue, however, must also create for itself, perhaps in the domestic field, a high form value and win its way in public favor before these processes can satisfactorily overcome their handicap of high costs. COMPLETE GASIFICATION ” PROCESSES
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“Complete gasification” processes are those effecting complete conversion of the coal into gas, except for the ash residue and a certain amount of tar. Ordinarily, the term is now applied to those processes involving destructive distillation in one zone, and the making of producer gas or water gas in an adjoining zone of the same apparatus. The distillation is usually effected, in part at least, by the sensible heat of the producer gas or water gas passing directly through the raw coal in the upper or distilling zone. This is an application where low-temperature carbonization finds great promise. It is an adjunct here to a gas-making process of a high degree of heat economy and low operating cost. Its special virtue of yielding rich, uncracked vapors and oils may be utilized, and its solid residue converted to the higher “form-value” gas. Such gas, however, being lower in heat value per cubic foot than the now-used public gas supply-say, 350 B. t. u. as against 570-will have to await public acceptance as of suitable quality. It has
Vol. 15, No. 4
been shown in some countries to answer well the requirements for fuel purposes. In projects for expansion of the public use of gas fuel, industrial and domestic, the serious problem of distribution costs enters as a factor fully as important as production cost. The “form value” of this kind of fuel is high, but it is counterbalanced in a measure by high delivery costs. The Tully gas-making process-a complete gasification process used in England since the war in a large number of plants-may be cited merely as an example. It is said t o secure, under favorable conditions, 50,000 cu. ft., of 360 B. t. u. gas from a ton of coal, together with 8 to 9 gal. of tara yield of about 20 million B. t. u., or 70 to 72 per cent of the original in the coal. This is a slight improvement in heat economy (3 to 5 per cent) over the two-stage, water-gas processes now in common use, and the operating costs are lower. To illustrate the general principle applied in many “complete gasification” processes, such as the Dellwyk-Fleischer in Germany, and H. L. Doherty’s recently patented process in this country, the Tully process may be outlined as follows: A vertical shaft or retort surmounts a shaft generator or producer wherein the fuel is intermittently blasted with air to raise the heats. The blast gases pass around the superimposed retort in checquer brick chambers where their heat is largely recovered. After an interval of blast, the “make” period starts, steam being blown through the hot charge in the generator and the hot water gas thus made being passed through the raw coal in the retort. The latter is thus carbonized (under low-temperature conditions) by the heat of the gases supplemented by the external heat of the surrounding checquer brick chambers. “Low-temperature’’ condensation products are carried off, with a mixture of blue water gas and coal-distillation gases.
In this country “complete gasification” has not yet obtained a commercial footing, nor, in fact, have any of the numerous tentative low-temperature carbonization processes. Much experimental work along both of these lines is being carried on, however, some of which has been brought to an industrial scale of operation. In this work there is great promise of an improved efficiency in coal carbonization and gasification, and an increase in the aggregate “form value” of the products. Abroad, Bergius has made recent researches worthy of note on distilling coal mixed with oil under high pressures whereby a hydrogenation is accomplished and remarkable yields of the lighter hydrocarbon oils are obtained.
An Efficient Reflux Air Condenser By George T. Dougherty A M ~ R I C ASTEEL N FOUNDR~ CHICAGO, S, ILL.
In the saponification of oils and fats in an alcoholic solution of potassium hydroxide it has been found convenient to use an air condenser made from a condenser tube, with adapter sealed to it, such as is furnished by all apparatus dealers for Liebig condensers. The condenser tube is inserted through the cork stopper of the flask with the adapter in the top. A test tube nearly filled with cold water is placed in the adapter and kept from fitting tightly by extending a wire between the adapter and test tube, nearly to the bottom of the latter. This prevents blocking of the outlet by any alcohol fumes. In making these extractions the flask is placed in a sand bath heated by a Bunsen burner. In case the flask breaks, the alcohol is absorbed in the sand and not ignited. This apparatus is also available for the determination of crude fiber in flour and core compounds, and for other purposes where it is desired to maintain a fairly constant volume of liquid during boiling.
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