INDUSTRIAL A N D ENGINEERING CHEMISTRY
730 PROXIMATE
AND
ULTIMATE ANALYSESO F COALS TESTED (PER CENT)
AND SUMMATION
AT
480° c.
Vol. 16, KO. 7
REACTIONHEATO F TYPICAL COALS I N NITROGEN
AND
HYDROGEN
Reaction Heat in N i t r o g e n , ~Calories per Gram 180
+
188 +42
114
+7
REACTIOX HEATSOF COALS The reaction heat of coal for any given carbonization temperature range comprises a summation of heats of exothermic and endothermic reactions taking place within that range. This is indicated by the work of Hollings and Cobb,' and has been verified i n the Bureau of Mines Laboratory.8 The time of exposure to the maximum temperature, the gaseous atmosphere in which the carbonization takes place, the rate of heating, and the exposure of distillation products to cracking temperatures affect the summation heat, and they are all factors that are difficult to control by practical test methods. I n other words, it is very difficult to so fix carbonization conditions that reaction heat determinations may be duplicated, and even when this has been accomplished it is hard to estimate how accurately the results apply to a corresponding temperature range in a coke oven. Here the heating rate varies widely from the oven wall to the oven center; coal a t the oven wall reaches the maximum temperature in a very few minutes, whereas for that a t the oven center about 16 hours are required before the full coking temperature is reached. Furthermore, distillation products from various parts of the charge must be in contact with heated zones for varying lengths of time. Thus in a coke oven conditions prevail which it is impossible to duplicate exactly in any small-scale test. Numerous laboratory-scale tests have shown that this is true as regards yield and quality of reaction products and it could hardly be otherwise as applied to reaction heats. Carbonization reaction heais as determined in the apparatus described above can be made to vary as much as 20 per cent when conditions other than the maximum distillation temperature are varied. The highest results that can be obtained under practical working conditions are for coking coal, around 30 calories per gram exothermic. This applies when the maximum carbonization temperature is around 500' C., or within the range of primary decomposition of the coal. If higher maximum temperatures are attained, the result is a lower heat of reaction8-that is, with higher temperatures the predominating reactions tend to become endothermic. While realizing that it is not possible to reproduce coke-oven carbonizing conditions exactly in a small-scale 7 8
Hollings, Harold, and Cobb, J . Gus Lightzng, 126, 917 (1914). Davis and Place, THISJOURNAL,16, 889 (1924)
coking test such as it is Dractical to make in a calorimeter. the results must be of the' same order of magnitude, and'one must conclude that the exothermic effect in the coking of coal amounts to a very small, practically negligible, proportion of the total heat involved in the process. This coiiclusion seems all the more justified when one considers that in the coke oven t'he finishing temperatures are well above 650' C., 'where the calorimeter indicates that endothermic reactions begin to increase. The accompanying table gives the primary reaction heats as determined for a few typical coals over temperature ranges where the maximum exothermic reaction heats were obtained. ACKNOWLEDGMENT The writer wishes to acknowledge his indebt,edness for many helpful suggestions in this work to Walter P. White of the Geophysical Laboratory, and to A. C. Fieldner, superintendent, and Rf. D. Hersey, physicist, Pittsburgh Station. P a t e n t s in t h e Chemical I n d u s t r y I n the Journal of the Patent Ofice Society is given an abstract of a n article on t h e question of patents in the chemical industry from Proprittb Industrielle, from which we abstract t h e following : Legislation of t h e principal countries of the world concerning patentability of chemical products may be classed under four heads, where the countries have been grouped according t o their patent practice. 1-Laws containing no special disposition concerning invention of chemical products or processes. Argentine, Brazil, Belgium, Rulgaria, Chile, Cuba, Denmark, United States, France, Great Britain, Greece, Haiti, Italy, Morocco (French Zone),-Roumania, Salvador, Sweden, Tunis. and Turkey. Z--I,aws limiting the patentability of these products or processes. Dominican Republic, Spain, Morocco (Spanish Zone), and Switzerland. 3-Laws excluding chemical products from protection but admitting t h e patentability of processes for obtaining them. Germany, Austria, Bolivia, Free City of Dantzig, Esthonin, Finland, Hungary, Japan, Lithuania, Luxemburg, Mexico, Korway, Portugal, Kingdom of Serbs, Croats, a n d Slovenes, and Czechoslovakia. 4-Laws limiting protection t o chemical processes but admitting t h a t t h e patent granted for this process extends to the chemical product thus obtained. Netherlands and Poland.
T h u s nineteen countries have no special legislation concerning chemical patents; four admit either t h e products or processes with some limitations; fifteen exclude the protection of products b u t grant patents for processes; and two, while granting patents for processes, also recognize t h a t t h e effect of these patents extends t o the products.
