Document bBz9pgqVJM8z90q3NOgr5xwjk

Ambrican Society of Heating and Ventilating Engineers Guide Anthracite Anthracite is a clean, dense, hard coal which creates very little dust in han is comparatively hard to ignite but burns freely when well started. It is 00n' b< Semi-Anthracite Semi-anthracite has a higher volatile content than anthracite, is not as hard and igni somewhat more easily; otherwise its properties are similar to those of anthracite. 242 Chapter Y5--Solid Fuels ^tuminous Coal ' ous coal is soft and friable, and fines and dust are created by handling, g^pbitumino s|owjy anj burns with a medium length of flame. Its caking prop- jfligSites somew jatjje matter increases, but the coke formed is relatively weak. the volatile matter-content of the more abundant bituminous coals *^^fie>buml with less production of smoke, and is sometimes called smokeless coal. 'Staminous Coal bituminous coal covers a large range of coals, and includes many types having ^^??ffprent composition, properties and burning characteristics. The coals range (partly.bituminous coals of the East to the poorer coals of the West. Their frpmtthe tug range from coals which completely melt, to those from which the sliPff'Tatars are distilled without change of shape, so that they are classed as nonjgjatile ana kUrning. ^ost bituminous coals are strong and non-friable enough to aSKS'tbe'saeenSi sizes being delivered free from fines. In general, they ignite |s,fi57uth,,rn freely; the length of flame varies with different coals, but it is long. Much * and soot are possible and are difficult to reduce to reasonable amounts at low rafes of burning. "' Sub-Bituminous Coals Yc'ub-bituminous COals occur in the Western States; they are high in moisture when Ihed and tend to break up as they dry or when exposed to the weather; they are.liable ' Snimitespontaneously when piled or stored. They ignite easily and quickly and have a ' length flame, are non-caking and free-burning; the lumps tend to break into s&ll pieces if poked; very little smoke and soot are formed. ' 'litfute `^Lignite is of woody structure, very high in moisture as mined, and of low heating value; it is clean to handle. It has a greater tendency than the Sub-bitumihous coals to \ jisuitegrate as it dries, and also is more liable to spontaneous ignition. Freshly mined lignite, because of its high moisture, ignites slowly. It is non-caking. The char left after the moisture and volatile matter are driven off burns very easily, like charcoal. The lumps tend to break up in the fuel bed and pieces of char falling into the ash pit continue to bum. Very little smoke or soot is formed. COKE Coke is produced by the distillation of the volatile matter from coal. The type of coke depends on the coal, or mixture of coals used, the tem peratures and time of distillation and, to some extent, on the type of Jj|e]ta>rt'Or oven; coke is also produced as a residue from the destructive *" distillation of oil. .'High-Temperature Cokes ..Coke as usually available is of the high-temperature type, and contains between l and 2 per cent volatile matter. High-temperature cokes are sub-divided into beehive coke of which comparatively little is now sold for domestic use, by-product coke, which covers the greater part of the coke sold, and gas-house coke. The differences between :thcfe c0^es are relatively small;.their denseness and hardness decrease and friability increases in the order named. In general, the lighter and more friable cokes ignite and bum the more easily. Low-Temperature Cokes . ^ bow-temperature cokes are produced.at lower coking temperatures, and only a portion - ot the volatile matter is distilled off. Gokes as made by various processes under develop ment have contained from 10 to; 15 per cent volatile matter. In general, these cokes aTM urn more rcadily than high-temperature cokes. The properties of various . *Imperature cokes may differ more than various high-temperature cokes because of l 9M*ercnces in the quantities of volatile matter and because some may be light and others-are briquetted. 243