3/d FOREST RESEARCH LABORATOR Y LIBRARY DISTILLATION Of RESINOUS WOO D No. 496 Revised May 1958 I I I I I I i l ll llllllllllllll - Illllllllllillllllliill,ni UNITED STATES DEPARTMENT OF AGRICULTUR E FOREST PRODUCTS LABORATOR Y FOREST SERVIC E MADISON 5, WISCONSIN In Cooperation with the University of Wisconsin FOREST RESEARCH LABORATOR Y LIBRARY . DISTILLATION OF RESINOUS WOOD-.. B y EDWARD BEGLINGER, Chemis t Forest Products Laboratory, 2 Forest Servic e U. S. Department of Agricultur e Raw Material r The commercial distillation of resinous wood is carried on at widely scat- tered plants in the pine regions of the South and Southeast . The wood generally used is obtained from longleaf and slash pine species . Live- trees of these species are also tapped for the oleoresin from whic h gum turpentine and rosin are obtained . Similar products recovered by dis- tillation or extraction of the wood are referred to as destructively distille d and steam distilled wood turpentines and wood rosin . Some plants proces s a small proportion of the more resinous wood from shortleaf and lobloll y pines . Best results are obtained, however, by limiting the selection of ra w material to longleaf and slash pine species . Since the marketable product s obtained are chiefly derived from the resin in the wood, the most desirabl e raw material for the processing is wood of high resin content . Stem stock or the average sawmill and logging waste from longleaf, slash, shortleaf, loblolly, and : other pine species does not contain sufficient resin for satisfactory plant distillation. Only the very resinous or pitchy portion s of the tree are commercially suitable . Such pitchy portions may be selecte d as they occur in wood operations or in the course of lumber production . - I . -The intent of this publication is to provide only the general information re- garding the methods and products of the resinous-wood-distillation indus - try . This is a revision of an earlier Forest Products Laboratory report of the same title, by L . F . Hawley. Maintained at Madison, Wis . , in cooperation with. the University of Wis - c ons in. Rept. No . 496 (Revised) -1 - Agriculture-Madison . The resinous portions of fallen or felled trees like longleaf and slash pines , when allowed to remain upon the ground, resist decay indefinitely . The less . resinous areas, particularly the sapwood, decay rapidly and disappear . The , remaining resinous material is called "lightwood, " "fatwood, " or, in th e case of the conically shaped pieces of pitchy wood from the base of the limbs , "pine knots . " In the same way, sapwood and the less resinous portions: of the heartwood of the stumps decay, leaving a core of pitchy heartwood . Waste log and limb lightwood, together with larger proportions of stum p wood from old cut-over areas, •-comprise most of the raw materials fo r product recovery . Selected pitchy slabs and trimmings. from pine-mill operations provide further limited amounts of raw material to the plants . The resinous wood of other species, such as the red or Norway pine of the North and the Douglas-fir and ponderosa pine of the West and Northwester n States, has attracted attention as raw material for destructive distillatio n and solvent processes . - Potentially large supplies of raw material from thes e species await possibly further developments in processing and wood-procure- ment methods . Expanded markets for the products might also lead to mor e economical production . Previous efforts to use mill and stump waste fro m these species have not been commercially successful . Howeve.r, there ha s recently been r=enewed interest in the possible utilization of these woods as ' raw material for extraction and distillation . Fairly extensive pilot-plant extraction studies have been conducted for some time by one large companlr 3 now operating on southern resinous woods . Other pilot-scale investigations - at Oregon State College, have indicated further possibilities in the use o f woods of lower resin contents, such as Douglas-fir mill waste, by modifie d destructive distillation, charcoal briquetting, and tar-recovery procedures . Destructive Distillation of Southern Pin e Distillation Equipment Both retort and oven-type distillation equipment is used in this industry . h The retorts are cylindrical steel vessels set horizontally in brickwork wit i. a fire box under one or both ends . They vary in capacities from 1 to 2 cord s of wood and are charged and discharged through an end door . Retort vola- tiles are piped to condensers located to the side or to the rear of the retorts . 3Reicks, H. G., E . G . Locke, and E. Tower . Charcoal -- Industrial Fue l and Industrial Tars . Same authors, the Timberman 46(2, 4, 5), Dec . 1944, Feb . and Mar. 1945 . Rept. No. 496 -2 - The larger oven-type heating chambers are loaded with wood contained i n cars or "buggies, " while the smaller retorts are charged and discharged by _ ; hand. Some of the ovens are of concrete construction= and are heated intern- ' ally by full-length iron flues . Another type of oven is of boiler-plate construc- tion. Heat is supplied by fireboxes located at one or both ends of the oven. in some cases, also, with ovens of concrete construction, the bottom is not heated directly and part of the crude liquid product is withdrawn from th e bottom of the oven . The remainder, in the form of volatiles, passes throug h an outlet pipe to the condenser . The kinds of fuel and the methods of firing vary at different plants . - Natural gas, oil, and coal are among the more common fuels used : . Time periods of 24 to 48 hours are required to complete the distillations to an end temperature , generally of about 800 F , Products The crude products obtained at most plants are the water-oil distillate, un- condensable gas, and charcoal . The vapors and gases pass from the heating chamber through a condenser for recovery of the distillate and separation o f the gases . The gases are piped for fuel use Under the wood charge or to th e boiler plant, or are vented to the atmosphere. Upon standing, the crude total distillate separates into a watery or pyroligneous acid layer .. and a lighter oil y layer . The oil layer contains the most important and valuable products . The crude,-oil distillate is not always obtained as a total product, but may be ob- 1! tained from the retort in various fractions . Plant procedure may include th e collection of the first oily distillate or crude ' turpentine separately at a coni paratively low temperature followed by .other products at progressively highe r temperatures . Another practice includes heating the bottom of the retor t only moderately high to allow collection of the less volatile products at thi s point. Pitch or tar may be drawn off, depending upon the temper=ature ap- plied. Whether the crude oils are collected as a whole or in fractions, re - distillation in tar stills is required for separation of primary. pr-oducts . There is no standard practice for preparing final plant products from th e crude-oil distillate, .since special products may also be produced at differ- ent plants to fit specific use and market requirements . The total crude oil after it is separated from the pyroligneous acid by means of settling tank s isidistilled in a pine-tar still . The products of this distillation are usuall y pitch, light and heavy pine tars, and a composite fraction of several ligh t solvent oils . Further chemical treatment and fractional distillation of th e -Naval Stores Review, International Yearbook 119 (1948) . Rept. No . 496 -3 - solvent oils yield turpentine, dipentene, and pine oil, together with smal l amounts of various hydrocarbons . The water portion of the total distillate or pyroligneous acid contains methanol and acetic acid like the crude distillate from hardwood distillation, but i n amounts too small to be recovered profitably. The charcoal remaining from the primary distillation is cooled in the retort s or, in some cases, may be raked out hot into suitable metal containers and sealed airtight . When ovens with cars are used, the cars with the charcoa l are run into closed sheet-iron coolers of about the same size and shape as the ovens, for periods of 24 to 48 hours . Yields Because few plants operate under the same conditions and various en d products are recovered from the crude oil, it is difficult to indicate th e average yields of products obtainable from the longleaf and slash pine ra w material. Moreover, the raw material may also vary widely in resin con - tent and provide further yield variations . The following tabulation shows roughly the ordinary yields obtained in destructive-distillation practice pe r ton of average southern pine stump and "lightwood. " Total oils 35 to 50 gallon s Destructively distilled wood turpentine . 4 to 6 gallons Tar 20 to 30 gallons Charcoal 350 to 400 pound s Uses of Product s Turpentine . --Incompletely refined wood turpentine obtained from destruc- tive-distillation processing is occasionally sold as a material inferior t o gum turpentine, largely on account of its off odor . There appear to b e numerous uses, however, in which this odor is no disadvantage . The refine d destructively distilled wood turpentine is used for many of the same purpose s as gum or steam-distilled turpentine . Chemically, the wood turpentines dif- fer considerably from gum turpentine, although the properties are not mark- edly different . The main difference in composition is essentially the presenc e of a rather large beta-pinene fraction in the gum product and its virtual ab- sence in the wood turpentine .