Show safe storage of bituminous coal BY H H who should store coal every consumer should store what he can the domestic consumer should place his order early in the spring and store his supply as he can get it power plants should maintain a reserve supply adding to and subtracting from the storage so as to make uniform deliveries possible through the period of the year most favorable to transportation A reserve supply sufficient for thirty to ninety days continuous operation is desirable why store coal to guard against interruptions of supply to take advantage of lower prices in the spring and summer to give steady employment to miners instead of seasonal employment to transport coal in good weather when it costs less what would result from more storage it would permit coal mines to operate continuously instead of intermittently intermittent operation inc erases the cost per ton for mining and makes the yearly return to labor low these conditions contribute to serious instability and unrest in one of the fundamental industries of the country and this can be changed only by coal buyers doing their part to insure steady work the railroads are now required to transport the maximum amount of coal during the winter months when traffic is most interfered with by bad weather and when the maximum amount of coal is used by the railroads to handle other coal the railroads now use nearly 30 per cent of the total output of coal about one third of their freight traffic is hauling coal so that economy of fuel used by the railroads will produce decea a considerable gross saving railroads are required to transport large amounts of coal in the autumn months when they are operating under pressure to move the crops if some of this load can be transferred to the spring and early summer months when crop transportation is at a minimum further economies will be effected storing coal benefits dealers would retail dealers benefit by early ordering and storage the cost of delivery is less in spring and summer when the work of delivery crews can be well planned and be made continuous than in winter when bad weather may interrupt deliveries what are objections to storing coal money is tied up for some months unless deferred payments can be arranged if coal must be re handled this increases the cost if the coal is friable every produces fine coal or slack which in excess is sometimes more difficult to burn efficiently storage facilities cost money to provide maintain and operate if fine coal is stored consulting engineer U S dureau bureau of mines there is some risk of spontaneous combustion of coals other than anthracite does coal deteriorate in heating power when stored there is no appreciable apreci able loss of heating power because of age Is there chance of loss in the storage of coal sometimes coal heats spontaneously if allowed to heat too much it loses in heating value and must be removed and cooled this makes an expensive considering si the number of storage operations this chance is extremely remote Is this true of anthracite coal no what kinds of bituminous coal can be stored any kind providing proper precautions are taken some kinds of bituminous coal are more liable to spontaneous combustion than others but it is not possible to say of any given kind of coal that it will or will not ignite under favorable conditions lignite and bituminous sub coal have a stronger tendency toward spontaneous combustion than most bituminous coals but with care they can be stored since they lose moisture rapidly the degradation in size is an objection to storage cause of spontaneous combustion spontaneous combustion is apparently due to an oxidation of the coal surface this generates heat if the heat is not dissipated the temperature will continue to rise the oxidation is more rapid at increased temperatures so that the process is self aggravating A temperature may finally be reached where the coal is afire how may heating be detected by the odor given off from the pile or by thrusting iron rods into the pile and feeling them with the hand or by a thermometer steam should not be confused with smoke for water vapor coming out of the pile in winter time may produce visible steam when there is no appreciable heating within the pile temperature tests with an iron rod should be made if possible actual temperature determination should be made with any suitable type of thermometer what temperature is dangerous when the tempe arture rises above degrees fahrenheit the pile should be carefully watched if it rises rapidly to or degrees steps should be taken to move the coal and cool off the heated part what is the best way to stop heating which has started the best way is to move the coal as quickly as possible to a place where it can cool off it should be allowed to become thoroughly cooled before replacing it in storage or better still used at once and not returned to storage can heating be stopped by putting water upon the pile only if it is applied in sufficient quantities to extinguish the fire and cool the mass the water must reach the point at which heating occurs for it can do but little good if the stream is only played upon the surface of the pile most bituminous bitu inin coal cokes on heating and a shell of nf tarry material is formed about the hot spot scot which prevents the water reaching it TO be sure that the water reaches the burning coal it is usually necessary to dig into the pile and turn it over it is usually better to move the coal and not depend on water three fourths of the coal fires studied have occurred within ninety days after the coal was placed in storage oxidation is most rapid on a freshly broken surface oxidation of the pyrite in the coal also produces heat and assists in breaking up the lumps and thus increases the amount of fine coal in tho the pile rise in temperature either from external or internal causes promotes the oxidation ot of pyrite and thus increases the liability of the coal to spontaneous combustion it is wise to select low sulphur coals for storage if procurable but it must not be taken for granted that a low sulphur coal will necessarily store well or that a high sulphur coal will fire in storage Is it bad practice to mix different kinds of coal in storage this is generally believed to be the case but there seems to be no logical basis for the belief except in so far as mixing may produce conditions within the pile that lead to heating precautions to prevent spontaneous combustion avoid storing fine coal store screened nut and lump avoid external sources of heat such as steam pipes warm flues and boiler settings avoid making fresh broken surfaces in handling the coal into storage avoid foreign combustible matter which may itself spontaneously heat such as rags s paper waste etc avoid sticks and timbers in the pile pi which coal fora fo surrounded by coarse ducts or flues concentrating the warm currents from the coal below what other precautions should be taken in take care to pre P storing in a cellar vent an accumulation of fine coal in OD directly diorec 9 part of the pile as for example below the opening through which the coal co has been put in if IF this fine coal is scat sc through the pile it is not likely to heat there is no danger of spontaneous c twenty tw bustion in small piles say less than tons with these precautions observed to 20 tons storage of twenty ob be t to what are general principles served in storing bituminous coal in 1 1 P amounts twenty to tons the ex of 0 tion of degradation of segregation fabar kosure to oxidation under conditions ek of able tor for the generation of heat and kosure to outside sources of heat the what is meant by degradation g in size of the coal this ln increase coal surface it has already been bee explain ex coal the t that oxidation of the surface of the finer the coal the cause of its heating beating the t neater greater is its surface in proportion to its yo volume luine and the gre greater ater likelihood of its heating beating if there is a choice of coal for storage the least friable should be chosen mat is meant by segregation the separation of the fine coal from the coarser pieces nieces if the coal is allowed to roll or slide this segregation takes place and furnishes favorable conditions for heating at some place segregation may be avoided by being careful not to dump coal at a single point in a pile where fine coal would collect the coal should be spread in uniform horizontal layers Is there much fire risk to a build nig in which coal is stored in up to tons no whenever heating occurs it progresses slowly and can usually be detected by the odor from the pile long before there is any danger the coal pile should be inspected daily to note whether there are any signs of heating such as odor visible vapor warmth to the hand or of rods thrust into the pile storage of to 1000 tons does this call for additional precautions yes for the larger the pile the more difficult it is to watch and the more important it is to prevent heating it is easier to store lump coal because the heating surface is relatively small and the open spaces between the lumps permit the air to pass through the pile and carry off any heat generated very seldom if at all do fires occur in lump jump storage piles and upon investigation it will usually be found that the coal has been broken by being dumped from a hight height the fire starting in the fine coal thus produced can slack be stored safely slack coal and d screenings have been safely stored in large age amounts in the air but the only absolutely sol tely safe way is under water it if this is practicable keep air out of the coal pile a as enuch as possible by compacting the pile and approximating the conditions that preva vall in under water storage can mine run coal be stored safely uner ar ordinary nary conditions the presence of he e coal and dust makes its storage dipti cult ut many varieties may be successfully stored ored in all low piles in storing mine run n coal it should be placed in uniform lay ers 8 and segregation of the sizes prevented ehg e piles should be as low as space will carefully watched and provision anade mad e to move the coal it if heating occurs suitable stable storage place important 0 it storing betorin is time to fo begin egin the actual a and suitable place should be prepared a definite nite advance policy outlined far r enough in so do that every ery one who will have to ons the storing ing may receive definite in and une not merely suggestions it is to 10 wait until the co coal al to be stored has been delivered and then dump it anywhere on oil the ground merely to release the cars promptly storage instructions should be prepared in advance and carried out to the letter many failures in storing coal have been due not to faulty ins instructions but to the fact that the instructions have not been followed since the heat is due to oxidation what may be done to prevent circulation of air through the pile storage under water completely excludes air and prevents heating storage in airtight air tight containers such as cement bins sealed at the bottom also prevent heating if piles are so built as to be as dense as possible the air flow will be retarded Is it desirable to store coal in pits pits will serve to restrict air movement through the pile but as they are usually filled by backing the wagons or trucks over the pile the fine coal thus produced is likely to start a fire what kind of surface should coal be stored upon A concrete floor is best but blit a hard clay bottom thoroughly drained is desirable if the former is too expensive coal should not be dumped on ground covered with ashes or refuse of any kind and the ground should always be cleaned of vegetation and leveled off so that the reclaiming of the coal may be done as easily as possible and the dirt or refuse will not become mixed with the coal what objection is there to dumping coal from a trestle breakage results the legs of the trestle also tend to produce channels for air circulation if the coal is of a size or grade likely to heat it is not safe to dump around the legs of ot ofa a trestle does moisture have any effect in connection with spontaneous combustion the evidence of chemical laboratory experiments is contradictory it is not wise to put wet fine coal upon a pile if it can be avoided or to store coal on a damp dame base water or melting snow trickling through a coal pile will tend to choke the interstices and change the ventilating conditions possibly leading to heating storage of over 1000 tons what special precautions should be taken in storage in large piles the bigger the pile the more likely that somewhere within it conditions favorable to heating may occur and the more difficult it will be to move the coal in case of trouble we are therefore warranted in taking unusual care to likelihood of heating Is it well to ventilate these large piles the effect of ventilating coal piles is a disputed point but the weight of evidence in the united states seems to be against the practice |