V?OLYS/S of WOOD Treatment with Sulfuric A c i d in a Stationary Digester ELWIN E. HARRIS, EDWARD BEGLINGER, GEORGE 1. HAJNY, AND E. C. SHERRARDI U. S.
IIREE oonutitumta --cclluloae, honiicellulose, and 1ignin~~form sbout 95% of the weight of dry woad. Cellulose and
T
hemicellulose may be oonverted by hydrolysis into simple carbohydrstes, a portion of whieli can be fomented for the production of alcohol. The hydrolysis of the hcmioellulose portion of wood was made tho basis for converting wood into doohol in the United Stntsa from 1909 to 1923, with B yield of 20 to 27 gallons per ton of wood (18). This work was continued b,y Sherrsrd and co-workers ( 1 , 4, 8, 9. 36). Conseoutive tioatments for wood hydrolysis were studied by Sherrerd and Dsvidson (87), with B yield of 31.61% reducing sugar in six short trent.ments (xpproximtely 8Gminute total hydrolysis). These sugars would be equivalent to about 35 gallom of alcohol per tori of wood. More recently in Germany Sehollet worked out B proceds requiring 20 hours by which wood is subjected to suece~sivetreatments with dilute sulfuric acid similar to t h a t of Sherrard and Davidaon. Alcohol yields were 50 to 58 rnllona DBT ton of wood in concentrntionvranging from 1.18 to 1.27% (8,3,6, 6 , 7, IO. 11, 13-31, ;?1-,?5, 59).
From 1935 to 19.10 the Cliffs Dow Chemical Company and the Tennessee Eastman Corporation investigsted prooesses for the hydrolysis of wood. Preliminnry wood hydrolyses were carried on from Janusry to Junv, 1943, at the Forest Products Laboratory to determine tho conditions required. A stationary digester was not available, 80 the experiments were carried out in a rotary digester. Some of the results are shown in Table I. It WBS found difficult to obtain high y i d h of sugar at high coneentrstions in a rotary digester. This work was continued at the Laborstory and is described in another report. The pilot-plant runs were carried out in B stationary digester s t tho Cliffs Dow Chemical Company, Marquette, Mioh. Woad chips, aawduat, or hogged wood wan subjected to sueeessive treat-
Forest Products Laboratory, Madison, Wig,
January. 1945
INDUSTRIAL A N D ENGINEERING CHEMISTRY
ments w i t h bat.ches ui dilotc d f u n r i i c i i l at gradually iricrailnirig temperatures from 135" to 185' (:. Fresh dilute acid nil8 run in intcrmittently at the top of a piLeked ciilurnn of finely divided wood and taken off i ~the t bottom.
13
silh the follou~iug: ~ ~ ~ , : ~ L ~~ -I i~~ O e l ImU iine r ~~rW 21, K \~.liichcontains themoeouple 22 for r n e w u i i n ~the temperat,ure oi tho s u g ~solution r leavirq the dixest,er: prrssure m p : 23: s t e m t line24 for usedurine the blowin:! 01 the Iixnin residue: s t a m line is filled
25 forxtenmingthe chsrgefmrn t,heLot.tom; and~tesrn-blondosn
v d v e 26 for discharging the l i x ~ i Ipsidue n through dirchar e pipe 27 in1.o cyclone 28. Inside of cone 20 and held in pl?ee%y the Ranxes that hold cone 20 is R filter made of two nestin:: perfor-
Figure 1 is a Eow 511eet of the priieeh.. \vater tank I is eonnocted to triglox m t e r pump 2, w i t h 8 eaated cones with R, 20-mesh acid-resistant bronze screen between pscity of 11 gallorls per minute. Acid tank 8 is connected to acid pump 4 which b;ts a capacity of 6 (litlions per hour. Punips 2 and them. Su~ar-solurionline 21 connects lhroueh sicrlit elass 29A to 4 BE driven by the same motor tlirough variablespeed drive 5 so that B Constnnt relation between water nnd acid may be held. The pumping speed of acid pump 4 may be verier1 by regulnt,or 6 . Water leaving pump 2 paises through steam-jet heater 7, consisting of E. 1.5-inch iron pip! rurioundinx il0.75-ineh perforated ipe, through which steam IS introduced into itir water stre&m. Ifhestesm prwmre in the steam-jet heatw is regulated by msiiiithroo-w$ cock, 35, p%t sampling rock SG, into solution reeeivinn ally operated steam regulstor 8. The temperntux of the water leaving the heater is mowured bv inrtriirnrnt, 9. Acid fmnr l m k s 37-40. ranshle of holrlinz noomxiinatelv 250 eallona ench. 'These t,a&ks ach equipped ~unm 4 i s introduced into the w i t h stirrers for mixin:: xurl b a t & line through quarts jet w i t h stearn
