Document mBmYe2n1B62o1XN0N37MRyYYg

1 / 1 s i f; j .T Automatic Feeding of Woodwaste AUTOMATIC CONTROL U outlined In a diagram that shows ' schematic hookup of combustion-control devices. Note location general toyout of feeding equipment ond draft system, plus a of the photo-electric cell for' measuring the brillloncy of fir* Tl 1)96) POWER July ;I948 HAND FIRING, even In a relatively up-to-date wood-burning amount of excess olr moy enter through fuel chutes. High boiler plant like this, Is inefficient bcccuse on uncontrolled velocity of fuel from conveyors to grate causes pile to pock Replaces Hand Firing, Saves Fuel Control system developed ot Klamath Falls plant, Weyerhaeuser Timber Co, uses fire's brilliancy to adjust automatically for differences in fuels, holds air-fuel ratio constant for smoke* free combustion. Harry Panning, mech supt, tells how it works *Whcn cha Nettie conditions made woodwaste scarce, higher efficiencies than could be obtained with hand Bring were needed, at the Klamath Falla, Oregon, plant o( Weyerhaeuser Timber Co. In collaboration with Bailey Meter Co, we developed automatic feeders and controls for the steam generators. This system includes measurement of fire brilliancy as s regulating factor In fuel* feed control. Changes In the fuel situation that encouraged this development are being Feu throughout the lumbering industry. no day Is rapidly disappearing when disposal of woodwaste, consisting of sawdust, planer shavings and hogged t*! (chipped slabs), represents a troublesome and often expensive prob- *** *or th lumber manufacturer.. In the peat, a smalt part of the waste served, os fuel for steam generation whilo the remainder was disposed of in any way possible, often by inc'tacrtiioa. Now, new developments on the one Hand reduce amount of'waste resulting from mill operations and, on the other band, make the waate that is produced valu able for a variety of purposes. Nol a Waste Product. Power plants in the wood Industries today thus burn a fuel that often hot real economic value, instead of a waste product to be disposed of by the least expensive means, which usually proved to be firing under a boiler. In many modern mills, supplementary fuels, such as oil and coal, ' must be burned because woodwaste supply for fuel purposes it inadequate. Accordingly, conditions ore beginning to put a premium on com bustion efficiency whereas it might bo fairly said that in the past there was a premium on inefficiency. Usual Setup. In the commonest ar rangement, woodwaste la fired on a flat or slightly inclined grate in a dutch oven, or extension furnace.' Most rela tively modem plants have an overhead conveyor running through the boiler room, and the one or more dutch-oven cells are fed by ebutes (see photo above). Amount of fuel fed is con trolled by an opening with a slide, in the bottom of the conveyor. This is op erated by the fireman, who walks along the furnace topa, looking' down on the fuel piles, and decides when to add-fuel according to his best judgment. In addi tion to dependence on the human factor, o major defect of this arrangement lies in the uncontrolled excess air that en ters through the luel chutes. This makes impossible close control of air-fuel ratio needed for high efficiency. Automatic Feeding- The photo and ` diagram on the feeing page show the automatic-feeding scheme developed at Klamath Falla to overcome these dif ficulties and boost combustion efficiency. *OWer July 1948 (197) 71