Febbcary 9, 1922 



The Florists^ Review 



25 



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LIGHT ON THE FIRE 



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WHAT COAL FIGURES MEAN. 



Interpreting Fuel Analyses. 



Tho quality of the various coals avail- 

 able in most of the markets varies 

 greatly, and in considering the instal- 

 lation of a heating system the quality 

 and grades of coal available become an 

 important element in the proposition 

 as to the type of plant to be installed. 

 The tendency of modern installations 

 has been toward automatic stokers. 

 When properly operated to suit the par- 

 ticular coal used, a more uniform result 

 is obtained and labor cost is reduced. 

 The automatic stoker is the result of 

 two elements of "feconomy, the reduction 

 of labor cost and the use of a cheaper 

 grade of coal. In addition to this, a 

 more uniform and constant supply of 

 fuel to the boiler is obtained. The 

 result of the installation of a large 

 number of stoker systems has been to 

 increase the demand for screenings, 

 which are always more abundant during 

 the season when lump coal is in great- 

 est demand. The storage of screenings 

 is not desirable, as the tendency of 

 screenings from a large majority of the 

 bituminous coals of the country is to 

 spontaneous combustien, which not only 

 involves loss in fuel value, but con- 

 siderable fire hazard as well. Having in 

 mind the various coals available, the 

 size of the heating system to be operated 

 and the available labor at hand, the 

 eflQciency of the type of heating appara- 

 tus is to be considered. If a high class 

 of labor can be employed, certain types 

 of boilers may be used which are capable 

 of greater efficiency, but will require 

 more skillful and intelligent handling. 

 If less intelligent and skillful handling 

 is necessary, simpler types of boilers 

 would be more desirable even though 

 not so efficient. 



Selecting Coal. 



In the selection of coals two essential 

 things should be considered: 



First: Its physical qualities. Hard 

 and lumpy, or friable and liable to 

 slack in handling and storing; freedom 

 from impurities, such as units of slate 

 and iron pyrites. 



Second: Its chemical composition. 

 The percentage of moisture, ash and 

 sulphur which may be considered prac- 



Grecnhouse men are becoming increas- 

 ingly expert at studying the coal they 

 huy in the light of technical analysis. 

 Only hy so doing are th^jj able to operate 

 their heating systems at highest efficiency. 

 Assistance in such study comes from the 

 large coal companies. Thomas I). Miller, 

 a representative of the Consolidation Coal 

 Co., Detroit, delivered a paper before the 

 Ohio district organisation of the National 

 Flower Growers' Association at Colum- 

 bus January 24 of which the meat is here 

 given. Careful study will give greenhouse 

 men light on the coal they buy. 



tically as noncombustible. While sul- 

 phur is combustible, its deleterious ef- 

 fect on boiler and stack should be con- 

 sidered, as well as the effect of admit- 

 ing into the atmosphere sulphur com- 

 pounds to an extent which might become 

 harmful to plants. 



The calorific value of the coal is of 

 course the ultimate essential to be con- 

 sidered. In the operation of a heating 

 system, regardless of the quality of the 

 coal, there will be unavoidable losses in 

 tho use of the coal. 



The problem of storing coal in any 

 quantity where the coal is subject to 

 spontaneous combustion has occupied the 

 best talent in the chemical and engineer- 

 ing field and no fixed or established 

 formula has been deduced from which it 

 can be determined whether a coal will 

 ignite spontaneously or, when it does, 

 why it did. 



Entirely satisfactory results from the 

 use of any fuel can only be obtained 

 by adopting methods of handling best 

 suited to it. Many of the larger coal 

 companies maintain technical depart- 

 [ nients for the special purpose of han- 

 ^-dHng special problems as to the most 

 suitable grade of fuel to be used under 

 specific conditions. 



The practical value of different coals 

 in boiler practice will be found in tlie 

 heating value of the coal as received; 

 that is, the coal must be considered in 

 conjunction with the impurities and in- 

 ert matter found in it and witli it. The 

 consumer of the coal is specifically in- 

 terested in the coal as it reaches liim and 

 its available value in that condition. 



Moisture. 



"Wlicn coal is fired into a furnace, the 

 nioisture in tlie coal will consume 1,370 



British thermal units (referred to here- 

 after as B. t. u.) of the heat in the coal 

 for each pound of moisture in the coal, 

 which is based on the following prin- 

 ciple: 



The calculations of loss on account of 

 moisture are based on the coal being 70 

 degrees Fahrenheit when it is fired into 

 the furnace and the outgoing gases are 

 600 degrees Fahrenheit as they leave the 

 furnace. 



The heat necessary to evaporate one 

 pound of moisture at atmospheric pres- 

 sure and raise it to 600 degrees will be: 



B. t. u. 



Sensible heat from 70° to 212° 142.0 



Uateiit heat of steam 970.4 



Sensible lieat of expansion at atmospheric 



pressure 71.7 



Sensible heat in vapor from 212° to 000° 180.24 



Total loss of heat evaporating 1 lb. 



moisture 1,370.34 



Coal having a heating value of 14,500 

 B. t. u. per pound and containing two 

 per cent moisture, will contain forty 

 pounds of moisture per ton of coal and 

 the evaporation of this moisture will 

 consume 54,800 B. t. u., or the total heat 

 contained in three and eight-tenths 

 pounds of the coal. Then the total loss 

 on account of moisture will be: 



Pounds 



Moisture 40.00 



Coal to evaporate it r 3.80 



Total loss on account of moisture, per 

 ton 43.8 



A coal containing ten per cent mois- 

 ture with a heating value of 11,000 B. 

 t. u. per pound will show a loss of 200 

 pounds of moisture and the heat con- 

 tained in 22.4 pounds of coal to evapo- 

 rate it, making a total loss of 222.4 

 pounds on account of moisture. 



Lignites run high in moisture and 

 illustrate tlie extreme view of this loss. 

 A lignite showing 6,970 B. t. u. per 

 pound contained thirty-two and one-half 

 per cent moisture, or 650 pounds per 

 ton. 



It will require the heat contained in 

 eighty-six pounds of moisture-free lig- 

 nite to evaporate this moisture. Then 

 tho loss will show 650 pounds of mois- 

 ture and eighty-six pounds of lignite to 

 evaporate it, or a total of 736 pounds out 

 of every ton fired will be lost on account 

 of this moisture. 



Fixed Carbon and Volatile Matter. 



The fixed carbon in coal may be taken 

 as 14,500 B. t. u. per pound. Deducting 



Proximate Analyses 100% 



Volatile Fixed Sul- 



Description of Coal Moisture Matter Carbon Ash phur 



.'Jtate County Namo '> Tc % To % 



Maryland, Allegany, Frostburg ;!.20 14. .".0 7.5.00 0.70 0.!>2 



W. Virginia, Fayette. MrDonald . . . . ;{.22 17,r.,3 70.40 2.70 0.04 



W. Virginia, McDowell, Rodornild.. 2.32 10.70 00. SO 11.12 1.78 



W. Virginia, McDowell, Ennis .1.2.-) 14.40 7S.0.") 4.24 0.48 



W. Virginia. Fayette, .^Jun 2.04 10.0'J OS. (-,7 8.70 1.80 



Ponn.sylvania, .Somerset, Windbir.. 2.40 13. .'0 77.80 0.31 1.20 



Illinois, Williamson, Cartcrville. . . . 0.18 27.30 .'■>.->.40 8.12 0.00 



Illinois, Franltlin, Zeigler 11.82 27.00 -,Tt.\(i .').42 0.40 



Iliinols, Madi.son, Collinsville 12.70 20.30 41.47 0.47 3.07 



Ohio, Guernsey, Danford O.O.". 33.04 48.80 10..').'i 3.13 



Oklahoma. Pittsburg, McAlester. . . 3..'i8 32.11 TM.Ui .".27 0..'>0 



Alabama, .^Shelby, Straven 3.83 32.03 ."S.(!0 ,''1.48 0.07 



Alabama, Jofferson, Dolomite 3.10 2.-..40 07.7.") 3.00 C^O 



S. Dakota, Perkins, Lodge Pole 30.10 24.08 27.81 8.3.-. 2.22 



Iowa, I.ucas, Chariton 1.-..30 30.40 41.40 12.03 3.10 



Penn., Washington, Marianna 1.44 34.01 .57.77 0.18 0.78 



Penn., AVestmoreland, CreensliupK . . 2.14 30.02 .".8.81 0.03 1.17 



W. Virginia, Marion, Monongali . . . . 2.it5 3.5.01 .50.44 .5.00 0.07 



Kentucky, Pike, Hellier 3.73 30.01 .50.42 0.84 0..5G 



Consolidation, Elkhorn 1.85 30.G5 58.40 3.01 0.43 



P 



Analysis of Some of ttie Principal Coals, Showing the 



( 



Estimated Loss and Available Fuel Value of Each. 



