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346 CHAPTER 14 1958 Guide a heat balance when required in testing of heating devices. Typical ulti mate analyses of the various kinds of coal are shown in Table 1.* Other important qualities of coals are the screen sizes, ash fusion tem perature, friability, caking tendency, and the qualities of the volatile matter. In considering these-factors the following points are of interest. The volatile products given off by coals when they are heated differ mate rially in the ratios by weight of the gases to the oils and tars. No heavy oils or tars are given off by anthracite, and very small quantities are given off by semi-anthracite. As the volatile matter in the coal increases to as much as 40 percent of ash and moisture-free coal, increasing amounts of oils and tars are released. For coals of higher volatile content, the relative quantity of oils and tars decreases and is therefore low in the sub-bituminous Table X. Typical Ultimate Analyses fob Coals Btu per Lb CoKsrmrxNTS, Per Cent Rase Moist, Mineralmatier- free* Moist, as Received Oxygen Hy drogen Carbon Nitrogen Sulfur- Ash Orf Bt Anthracite. ........... 14,600 12,910 5.0 2.9 80.0 0.9 0.7 10.5 87.9 Serai-Anthracite. 15,200 13,770 5.0 3.9 80.4 1.1 1.1 8.5 89.3 Low-Volatile Bituminous 15,350 14,340 5.0 4.7 81.7 1.4 1.2 6.0 91.4 Medium-Volatile 15,200 13,840 5.0 5.0 79.0 1.4 1.5 8.1 89.0 High-Volatile Bituminous A.........-- 14,500 13,090 9.2 5.3 73.2 1.5 2.0 8.8 87.7 High-Volatile Bituminous B 13,500 12,130 13.8 5.5 68.0 1.4 2.1 9.2 87.3 High-Volatile Bituminous C-............ 12,000 10,750 21.0 5.8 60.6 1.1 2.1 9.4 87.4 Sub Bituminous B. 10,250 9,150 29.5 6.2 52.5 1.0 1.0 9.8 88.2 Sub Bituminous C.-------- 9,000 8,940 35.8 6.5 46.7 0.8 0.6. 9.6 89.0 Lignite. ___________ 7,500 6,900 44.0 6.9 40.1 0.7 1.0 7.3 91.0 * (Btu as received) X 100 -5- (100 -- 1.1 Ash) coals and in lignite. The percentage of ash and its fusion temperature do not indicate the composition or distribution of its constituents. Classification of Coals A classification of coals is given in Table 2, and a brief description of the kinds of fuel is given in the following paragraphs, but it should be recog nized that there are no distinct lines of demarcation between the kinds, and that they graduate into each other. Anthracite is a clean, dense, hard coal which creates little dust in handling. It is comparatively hard to ignite, but it burns freely when well started. It is non-caking, it burns uniformly and smokelessly with a short flame, and it requires no attention to the fuel bed between firings. It is capable of giving a high efficiency in the common types of hand-fired furnaces. A tabulation of the quality of the various anthracite sizes will be found in a Bureau of Mines Report.* Standard anthracite sizing specifi cations are shown in Table 3. Semi-anthracite has a higher volatile content than anthracite. It is not so hard, and ignites somewhat more easily. Otherwise their properties are similar. Semi-bituminous coal is soft and friable, and fines and dust are created by handling it. It ignites somewhat slowly and burns with a medium length of flame. Its caking properties increase as the volatile matter increases, but the coke formed is relatively weak. Having only half the volatile matter content of the bituminous coals, it can be burned with less production of smoke, and is sometimes called a smokeless coal- Fuels and Combustion 347 The term-bituminous coal covers a large range of coals and includes many types having distinctly different composition,' properties, and burning characteristics. The coals range from the high-grade bituminous coals of the East to tbepooref coals of the West. Their caking properties range] from coals which melt completely,. to those from which the volatiles and1 tars are distilled without change of form, so that they are classed as non-caking or free-burning. Most bituminous coals are strong Table 2. Classification of Coals by Rank* . : Legend: F.C. = Fixed Carbon. V.M. *= Volatile Matter. Btu = British thermal units. Limits op Fixed Cabbon ob Btu Mineral-Matteb- Free Basis Requisite Physical Properties I. Anthracite. II. Bituminous^. Ill Sub-bitumi nous IV. Lignitic.. 1. Meta-anthracite. Dry F.Cm 98 per cent or more (Dry V.M., 2 per cent or lees) 2. Anthracite........... Dry F.C., 92 per cent or more and less than '98 per cent (Dry V.M., 8 per cent or less and more 3. Semi-anthracite. than 2 per cent) Non-agglomerating Dry F.C., 86 per cent or more and less than 92 per cent (Dry V.M*. 14 per cent or less and more than 8 per cent) 1. Low volatile bituminous coal.. Dry F.C., 78 per cent or more and less than 86 per. cent (Dry V.M., 22 per cent or less and more than 14 per cent) 2. Medium volatile bituminous Dry F.C., 69 per cent or coal more and less than 78 per cent (Dry V.M., 31 per cent or less and more Either agglomerat than 22 per cent) ing* or non- 3..High volatile A bituminous Dry F.C., less than 69 per coal cent (Dry V.M more, weathering^ than 31 per cent); and moist0 Btu, 14,000 or more 4. High volatile B bituminous Moist Btu, 13,000 or more coal and less than 14,000 5. High volatile C bituminous Moist Btu, 11,000 or more Coal and less than 13,000 1. Sub-bituminous A coal................ Moist Btu, 11,000 or more 2. Sub-bituminous B coal.. and less than 13,000 Moist Btu, 9500 or more Both weathering and and less than 11,000 non-agglomerat- 3. Sub-bituminous C ooal. . mg* Moist . Btu, 8300 or more 1. Lignite........ 2. Brown coal. and less than 9500 Moist Btu less than 8300 Moist Btu less than 8300 Consolidated Unconsolidated does nt include a few coals which have unusual physical and chemical properties and j-nt- ^e,liTMit8 of fixed carbon or Btu of the high-volatile bituminous and sup-bituminous mnn*tha eiS P0**8 either oontain less than 48 percent dry, mineral-matter-free fixed carbon, or have i16,500 "OIst' mmeral-matter-free Btu. MotWtlera^clas8*fy low-volatile group of the bituminous class, of the fqqj15111 relers coal containing its natural bed moisture but not including visible water on'the surface e that there may be non-caking varieties in each group of the bituminous class. MPn-j:-, . ^in? percent or more fixed carbon on the dry, mineral-matter-free basis shall be classified to fixed carbon, regardless of Btu. eratine and^nnn1166 of coal in the high-volatile C bituminous coal group, namel y, Variety 1, agglom non-i^thering Wea"enn*: Variety 2* agglomerating:and weathering; Variety 3, non-agglomerating and dapted from A -S.T.M. Standards, 1937, Supplement, p. 145, American Society for Testing Materials, In een>n~^r*?i?k no.ub 1 permit the screened sizes being delivered free from fines, coals k t ^ easily and burn freely; the length of flame varies with different at IftwV* 1S- ,nS* Much smoke and soot are possible, if improperly fired, especially S 6 **. 68 01 burning. mined coa^s occur *n Ike western states; they are high in moisture when liable to* break up as they dry or when exposed to the weather; they are and hav spontaneously when piled or stored. They ignite easily and quickly, to break^f1116^1'1111 flame; are non-caking and free-burning; the lumps tend . into small pieces if poked; very; little smoke and soot are formed. 9ni e ib of woody structure, very high in moisture as mined; and of low heating