Feljruur.v 2-<. 1021; 



HARDWOOD RECORD 



A uniform fuel supply is impossible by spouting direct from the 

 separator, by gravity, because the shavings do not arrive in the 

 separator in continuous uniform quantity, and there is very little 

 opportunity for close regulation, even though the material can be 

 deilccted into the overflow bin in times of plenty. Coal is resorted to 

 to hold even steam pressure, as a rule, and that is bad for the 

 economy of the burning shavings, and equally as bad for the economy 

 of the burning coal. 



Uniform spreading of the shavings shot into the furnace from 

 such a spout is not feasible, excepting by frequent hoeing, and this 

 means work, which is often shirked, and the shavings therefore ac- 

 cumulate in a heap, which becoming too compact to pass any air 

 through its interior, distills with the heat, instead of burning, mostly 

 producing carbon monoxide gas, owing to the lack of air within the 

 pile, part of which gas burns on release, producing carbon dioxide 

 gas, but a large portion of the monoxide gas never gets a chance to 

 Ignite because of the very surplus of the air it craves, since the 

 large amount of air coming into the furnace with the shavings 

 through the spout from the separator is cold, and in rushing through 

 the furnace has a tendency to cool the gases which are distilling 

 from the piled up fuel on the grates, to a point below their ignition 

 temperature. Fuel burned to carbon monoxide has given up only 

 about one-third of its heat if the monoxide is not burned but lost 

 without combustion. 



Wrong Feeding of Air 



A properly proportioned air supply is impossible when shavings are 

 fed in varying and intermittent quantities direct from the separator. 

 As the volume of fuel flowing through the spout to the fire decreases, 

 tlie volume of the air passing through the same spout increases, 

 which is just the reverse of the natural requirement, and this air, 

 probably much in excess of all demands of proper combustion, is en- 

 tering the furnace at the worst possible location, near the front and 

 above the fire, where it cannot assist combustion, and on its passage 

 through the furnace must acquire its heat from partially burnt 

 fuel and gases, depriving the latter of the opportunity to properly 

 ignite and thus deliver their full heat value. 



Such an excessive quantity of air, admitted to the furnace for no 

 useful purpose, besides also absorbs a large amount of heat which it 

 carries out through the stack, since it enters at about 70° and leaves 

 at about 450° to 500°. 



There is only one practical remedy for the conditions described 

 above, and that consists of feeding the shavings in concentrated 

 mass, without admixture of air, either with the shovel or with a 

 suitable mechanical device. 



All air necessary for the complete combustion of the shavings to 

 be introduced, in right volume, and at right pressure, through the 

 ashpit and the grate bars, up through the fuel, either by natural 

 draft, if this is sufficient, or by a mild forced draft, if the amount of 

 shavings to be burned per square foot of grate would preclude 

 passage of the requisite volume of air by natural draft. 



Such a feeding of the shavings requires a reasonable reservoir 

 capacity between the separator and the boilers, sufficient to hold 

 about four hours' supply for those boilers which are to operate at 

 their full capacity with shavings as fuel and without any assistance 

 from coal. This reservoir capacity to take up any inequalities in 

 the supply of shavings, on the one hand, and to permit the uniform 

 and continuous delivery of shavings in concentrated volume without 

 air to the boilers on the other hand. These shavings to be taken 

 from the bottom of the reservoir and conveyed to the furnaces by 

 a simple mechanical device, the speed of which can be conveniently 

 regulated to suit conditions of steam demand. 



The spreading of the fuel is accomplished by means of steam jets 

 located just below the mouth of the fuel entrance, and can be made 

 quite effective. 



An overflow bin will probably prove necessary to receive any 



temporary excess of shavings which cannot be accommodated in 

 the reservoir. 



Scrap Lumber Must Be Hogged 



Scrap lumber which must be burned, if produced in appreciable 

 quantities, should be hogged, and delivered to the separator with 

 the shavings. To burn sticks too long for the furnace, which makes 

 it necessary to leave the furnace doors open for long periods because 

 the sticks project, is a waste of good money, and should never occur 

 in a well managed plant. In several industries it has been found 

 much more profitable to sell scrap wood on a tonnage basis for 

 domestic use rather than to hog it and burn it under the boilers. 

 Any scrap wood which cannot be introduced into the furnace with 

 shavings, or with the shovel, and which must be thrown in by hand, 

 is very expensive fuel, aside from the labor cost, because of the 

 large amount of excess air entering the furnace through the almost 

 continuous opening of the furnace doors. 



No bed of coal is required to carry on combustion of shavings 

 from kiln-dried lumber with the process above described, because 

 the feeding can be made strictly proportional to the demand, and as 

 steady as the feeding of coal on a chain grate. 



The writer recalls some woodworking establishments where the 

 boiler firemen thought that they could not burn kiln-dried shavings 

 without a substantial bed of lump coal under the shavings. Even 

 coal screenings were not acceptable, it had to be expensive "lump" 

 coal. After proper training and some moral suasion, these same 

 men fully agreed that these same shavings could be quite properly 

 burned without an ounce of coal to assist. 



Coal and wood shavings, when burnt together in the same furnace, 

 in mixed state, make for bad economy in combustion of either. 

 This applies particularly to hand firing. With chain grate stokers 

 it is possible to feed a uniform, thin layer of coal and then spread 

 on top of this, in the manner described, a well-distributed layer of 

 shavings. In this case the coal should be of nut size, and it is used 

 only to shut off the air spaces between the grate links, which other- 

 wise would be too large for the shavings, and would pass shavings 

 down and too much air up. 



Conclusions On Steam Making 



It may be well to remark, in conclusion, that there can be no real 

 economy in any steam boiler operation, whether coal or wood fired, 

 unless the uptake dampers of the boilers are in good operating con- 

 dition, and the firemen are disposed to properly operate same, as 

 often as necessary, to the benefit of the fires. This is as essential to 

 economy as is the fuel itself to steam making, and it is the writer's 

 experience that if the damper operating mechanism is maintained 

 in good order and so placed that it shall be readily accessible from 

 the boiler front, in other words, that it will require the least possible 

 effort in its operation, that the firemen are agreeable to make proper 

 damper adjustments as required by the furnace conditions. 



And in order that the fireman may not be groping in the dark, a 

 set of combination draft gauges should be provided for each boiler, 

 at small expense, which will serve him, in a measure, as the compass 

 serves the mariner, and tell him at a glance the facts about his fires 

 and furnace conditions, good or bad, and will reflect the slightest 

 change in damper adjustment, right or wrong, excluding guesswork. 



Your shavings are worth money, gentlemen, ton for ton at least 

 two-thirds, and possibly three-fourths the price of the coal you 

 must buy. Do you get that heat value now in your furnaces from 

 the shavings you send to the boilers? 



The Light Woods of the United States 

 The three lightest woods in the United States are the corkwood, Leit- 

 nerin, ftoHdana, a small tree in Florida and southeastern Missouri : tupelo 

 huttrpss wood, the so-called tupelo "sounds. " and the interior wnnd of 

 cypress "knees." Corkwood when thoroughly dry is about one-fifth as 

 heavy as water, the root wood only one-sixth. A specimen of tupelo has, 

 been examined with a specific gravity of only .137 or less than one-seventh 

 the density of water. 



