5.Z5 I U. S. Department of Agriculture, Forest Service FOREST PRODUCTS LABORATORY In cooperation with the University of Wisconsin MADISON, WISCONSIN w U U MOV 7 1335 ^ DEPT. OF FORESTRY UNIVERSITY OF FUOHIOA DISTILLATION OF HARDWOOD B y L. F. HA WLEY Principal Chemist May, 1924 November, 1932 Digitized by the Internet Archive in 2013 http://archive.org/details/distillaOOfore DISTILLATI01T OF KASD7C C By L. F. ■- T, P r i nc rnal Chemi s t Destructiv . LI; Lcn of iodi terial hardwood distillation industry Is confined principally 1 nor • Pennsylvania? sout or • , ilea: > ever 80 perc of all plants being in these stal • ' for t ' ipalachi; .. soul >od belts, t] rdw are b most easily accessible at the present time. The species used occur Ls1 tunc Qy of "beech, biro' , > with 11 proportion of other hardwooi that naturally tow in se foresl . Several n ; distill ti plants ve recently been constructed in the South i re th uthern hardw :s, red '.ir,, ash, elm, : .' hi ■ . ry been \ised for d distillation. > 1 ■ some species slabs rive yields large as or ] ■ than bodywood. The importance of this fact in the utilization of mill waste is evident. Small wood, such as thin edgin or small limbs takes ux> so much • is so costly to handle in comparison with equal weights of ] •• material that it is not commonly 3 while very small sized material, such as sawdust and sh; 3, has been used satisfactorily. The snail size of such material makes it so poor a conductor of heat that it is impossible to char it coi I ly in the ordinary forms of par ■ and new types of apparatus for stirring the sawdust during distillation have had difficulty on account of the charcoal dust which clogs the condenser tut . Lnely divided rcoal is difficult to ccol and the market for it is limited. —This circuL - not be-^n compiled with I itention of living tec information or the results of original investigations, but to furnis r : I distillation in this country time that it is impossible to ,~ive in answer to the many ' ries ' i Torest Service receives c : try. "R77 There is one orocess using small s5 Lc is in commercial operation on a large scale. Phis pr< : s not /dust or shavings, however, but fairly ] chips, < :har :e ' \ not stirred. It i^ a continuous orocess, th< - • 'or-, beir delivered continuously to the top of tl 'tical stationary retort - nd L . ed continuously from the bottom. rt is not heated since the decomposition of the chi 'urni ; ' distill the fresh chips coming in. Jormerly only the best wood was iice^ for distillation; suitable for lumber frequently its way to the - 4 s. ■ ctice is becoming less frequent. Several pi; I re being run in connection with s i lis so that only t Her trees not tab] lumber ore used for di tion, to I r with the limbs down to •■ R inches in diameter and 1 : ■ slabs. Operation in connection .ills offers the additional : Lv; 1; ■• supply available as fuel to carr distillation a) I r proces is cut into corkwood lengths t pract] is allowed to season for -bout •-•■ year, either i • at 1 plant. "11116 it is not -probable that the y5 l ' - wood differs ■ ■ bly, cord for :ord, 'om 1 Leld air-seasoned wood, the r v i.ng lies in the fuel. ' her ber content of pxeei I necessitates more fuel for oarb< dilutes t: ;tillate, ■■ ' ur1 :cessive u 1 in i refining r 'ions. 5 ' l] olants have installed ratus for the •tificial " of the wood usii ' from ' Distilling Apparatus tod is distilled in three forms of apparatus in t un1 y: (a) In brick kilns; (b) in retorts; and (c) in oven . >ld types of charcoal kilns, ■ ■ . od under sod, all the valua l vapors escaped into the air ■ ■ • '. le in the modern charcoal kiln the vapors rm to the ovens. There ire usually two of these ' each oven, the charcoal going from the first coi Ler in1 nd at the end of thi t distillation. For both retorts and ovens the • ■ rcoal i : led for at least Us hours in closed vessels, pjid in the best practice is then cooled Ug hours longer in the air before shipping. Wood charcoal lias a strong tendency to spontaneously ignite, due tc its remarkable absorption properties, and for this reason must be carefully and thoroughly cooled. • noncondensable gas still contains appreciable quantities of pyroligneous acid, and in a few plants is passed through scrubbers to recover the valuable products. In nearly all distillation p] .' - ; whel or not it is passed through scrubbers, the gas is either piped under the carbonizing vessel, as with retorts or ovens, and burned t 1st in the distillation, or is burned under the boilers whic 1 for the refining operations. The pyroligneous acid and tar run off I ther from the condensers into wooden vats where d to settle, pyroligneous acid ' -'a brown in color, I s strong, r; :1 ri , burnt-wood odor, and contains fron •' ' h percent of wood alcohol, 10 12 percent acetic .• percent of tarry matter, and the rest water, e tar when in thin layers is dark brown in color ; id odor. Dissolved in the tar are son ■ cetic acid and wood alcohol, which are recovered ordinarily by simple distillation with steam. In most cases, after separating out the acid and alcohol by distillation, the tar is used for fuel at the plant by burning under the b 's or retorts, being mixed wit'- steam and sprayed v/ith a suitable nozzle. to the present time the commercial uses for hardwood tar have been limited, and since the fuel value is comparatively high the most frequent uses is as fuel at the plant. A few plants have distilled the tar for t • production of a hard pitch and various tar oils which have been used largely for flotation oils. The refining mi I having the mo si t nt is essentially as follow : (1) Distilling the pyroligneous acid in a copper still to fr it from the tarry matter dissolved in it; recovering the acid and . the settled tar, and adding it t : : tar-free pyroligneous acid. (2) Neutralizing t : :ibined tar-free distillate with lime or milk of lime. R77 (3) Distilling the neutralized liq- r in iron stills called the "lime lees" until all the alcohol i tilled of' . [h) Evaporating the residue from the "line lees" first t "mud" in shallow pans and finally to dryness on the tiled floor ovens or in specially constructed drying apparatus^ this residue 1 ray acetate of lime." r ) Distilling the -veal: alcohol from (3) in column stills. In thin step some plants obtain only a crude v lcohol of £2 p str .- Lch is sent to a refinery for further tr £;ive the crude 22 percent additional distilla* columns and obtain 95 to 93 percent wood alcohol witho i lor or unpl< t odor. T'iie bad odor often notice:", ir wood alcohol is due to impurities present because of incomplete re Lng. Ir. this ref. nrocess tr. stillatc ch step is completely condensed -cooled c rs. ire several opportunities for combin I .ose steps tc nomies in I ste iter nece- ns; Pi n1 producing la] ; ov: is of distillate and those *e c-.e ' -1 is n t ■ the best op- " Lty for s : lomi .^. The use of more modem triple effect v- ■ porators in place of simple stills for obtainin t --free pyroligneous acid,. bhe concentration :etate • in steam. Die separation of alcohol from the neutralize' pyr Li jneous acid by means of column stills provides another method of steaming economy. A heat economy introduced ! ly is drying the acetate mud in chambers heated by waste heat from the retort stacks or blast furnace stoves. These more modern methods are now being used at several of the larger plants. Y ields Kiln plants ' ' ch the combustion of part of the valuable products serves as heat to distill the rest yield o - r cord of hardwood: charcoal -- to ' ' bushels. - acetal Lim 30 to 120 ] T7cod alc< 1 !2 percent) Ov- -. ■ tort plants s it th i folic rer yields per c r : rcoal to 52 bushels. y acetate of lime l6( to " ,d alcohol (S ! percent) i to 11 gallons. The lack of chemical supervision in a number of plants makes statements of yields a little confusing, since wood alcohol and acet- of lime are variable in quality and the number of fallens .and pounds may, therefore, actually represent products of different composition, and also since the proportion of the various species used is quite different in different localities. p Uses of Products- Cha rcoal has its largest use in blast furnaces for the production of Dig iron. large quantities are used • mestic in some localities, particularly in the eastern Charcoal is also used in the manufacture of gunpowder, by tin and c ..-Iters, as in insulating material, in ooultry and. stoc ds, and for various chemical uses, such as case?: • i ng compounds and clarifiers in sugar refineries. Refined wood alcohol is m; and sold in various grades, each grade h vi] ; n particular use or uses. Methanol is the name now commonly used instead of methyl or wood alcohol on account of confusion with ei alcohol. The former larg e for wood alcohol as a solvent in the production of shellac varnishes, in hat making, etc., has diminished greatly in the last few years but its chemical uses as in the coal-" dye industry, in manufacture of formaldehyde, photographic films and celluloid have increased. Certain fractions obtained in the refining Drocess also have an important use as a denaturant for gr; I cohol to produce "industrial" or "denatured" grain alcohol. Acetate of lime is a gray, finely crystalline substance which is used principally in the manufacture of acetic acid and acetone, but is also used for the production of many commercial acetates, acetic ether, and ether products. Acetic acid is used extensively in numerous chemical manufactures, such as dyeing of cotton cloth, production of pigments, cellulose acetates, etc. From acetone may be produced chloroform iodoform. Acetone is also used in smokeless powder manufacture, solvent for acetylene in connection with acetylene welding process- , and in numerous chemical industries. 2 The market prices of these products vary considerably from time to til . They are, however, regularly quoted, .articles in the various chemi de journals. The use of acetone in the manufacture nf smokeless powder (especially in England) raid the use of acetic acid -and acetone in the preparation of the "dope" or coating for airplane v/ing fabrics placed acetate of lime in the class of war Munitions. The wood distillation industry, therefore, expanded greatly during this period. Commercial Operation The establishment of hardwood distillation plants for successful operation is subject to the usual requirements of any other highly technical industry such as (l) an adequate supply of raw mater' to operate the plant for a long period, (2) a market for all the products, and especially a nearby market for charcoal. The plants require expensive equipment, the present cost being in the vicinity of $5^00 P er cord per day capacity for a complete plant to manufacture acetate of lime and crude wood alcohol. May 7 j 192U. For the last few rs some of the products of wood distillation have met with )-:een competition because of the development of new sources of these products. Acetone, acetic acid, and methanol are new either being produced by fermentation or are being manufactured nthetically. With the appearance of these synthetic products the industry is being forced to depend more and more on the tars, oils, and charcoal for its Torofits. November 15, 1932. UNIVERSITY OF FLORIDA lllllllllilllll 3 1262 08866 4882