continuous distillation of gum turpentine

't A Staff-Induetru Collaborative Revort .

E. L. PA'ITON' AND G. P. SHINGLER' u. s. Department of A g r i c u i t m

In collaboration with WILL n. SHEARON, JR.

Asmeiote Editor

URPENTINE has come a long way since the days of 1606 T when the first turpentine farming wasstartedinNovaScotia, and the term "naval stores," which is applied to the industry producing turpentine, roein, and other oleoresinous materib from the pine tree, furnishes an interesting example of how an industry may change and yet retain some of its original flavor long after. It has been a long time since the principal products of the naval stow industry were pitch and pine tar for caulking ships and weatherproofing line; turpentine and rosin have long since usurped the title of naval stores, although today such a title is certaioly a eomplete misnomer. Palmer (6) suggests that up to 1800 the industry may have heen more properly named the pine tar industry; between 1800 and 1900, the turpeatine industry; and from la00 on, the rosin industry.

Originally turpentine w&8 produced only from the living pine tree; gum spirits of turpentine and gum rosin we- products of the exudate, which is a solution of resin acide in turpentine. Today there are three other very dieerent methods of production from a seoond sburce (stumpage and lightwood), and the prodncta

depend on the method employed. Destruotive distillation of pine wood gives destructively distilled wood turpentine, hut no rosin; the residue consists of pine tars and pitches instead of rosin from the distillate and charcoal from the kiln. The real beginnings of this branch of the naval atores indu8try me thought to have been in a plant erected by James Stanley; in 1872, at Wilmiugton, N. C. (8). .Steamdistilled wood turpentine was produced for the first tin,?j between 1900 and 1910 and a wood rosin also is obtained hy this method From the fefining of the volatile oils recovered from the digestion of pine wwd by both sulfate and sulfite paper manufacturing proteases, products c d a d sulfate and sulfite wood turpentine are formed. T h e processes produce no rosin, but acidification of the digester liquor from the sulfate process gives a liquid rosin known as Tallol, which is a mixture of resin acids and fatty acida.

The wood pbme of the naval &ores industv, although less than a generation old, hss made steady strides in quantity of production and improvement of methods. In 1947 wood turpan- tine and wood rosin production amounted to approximately 50% of 'the total turpentine and rosin production in this country (7). Table I shows a comparison of production of turpentine and

1 New Orleans, L.. Olultoo. Fh.

-

1695

1696 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 40, No. 9

Figure 1. Knabb Fire Still

rosin by all methods during the first half of 1948. The com- plet’ion of the plant of Honier T. Yaryan a t Gulfport, Miss., in 1910 marked the beginning of the steam and the solvent phase of the ivood naval stores industry. Hercules Power Company purchased the two existing Yaryan plants in 1920 and erected their plant, a t Hattiesburg, RIiss. Schantz (1B) gives a detailed account of the development of wood naval stores and the important part which Hercules has played in it, particularly in re- spect to rosin clarification, which was not provided for in the Yaryan process. There are at present two commercially succ~ss- ful processes (4j for refining wood rosin: the use of an adsorbent and selective refining with furfural. The advent of gasoline fractions of narrow boiling range cut down the use of the steam and solvent process, and the ma,ior processors of lightwood or stumpage use straight solvent extraction with benzol, naphtha, arid the like, fractionating the resulting solution (a),

One of the most surprising things about the gum phase of the industry, the only phase which will be dismssed in detail here, is the fact that for decades no particular progress Tvas made in the development of efficient methods of production. And yet this is not so surprising when the methods and circumstances involved are considered. For more than 150 years in this country gum naval stores products were produced in simple batch operations by very small operators. 4 s recent as 1935 practically all of the production was by fire still, a very crude method, and at’ one time there were about 2500 fire stills in operation. bIost of these fire stills were operated by the oimers of the pine stands them- selves. Speh (16) reported in 1926 that 11% of the operators produced annually less t’han 100 barrels of turpentine each; 40yG produced 250 barrels and 807‘, 500 barrels or less. It is easy to see the soundness of his statement tha’ ‘vie are not dealing with a manufacturing plant or an establishment that can exert chemical control over its products. Further, under present economic conditions, t’he average place has such a short life t,hat the expenditure of large sums for expensive equipment is not justified.” He also stated that, “there is at present a slorvly increasing recognition of the use of steam stills and it is entirely possible that as a result of the use of this more technical process we may be able to exercise some control over the chemical constants. This, however, is something for the future.”

Second-growth slash pine, seeding itself in cuhver areas, and the increasing regard paid to longleaf and slash pine as a crop to be farmed have to a large extent removed t,he disadvantage of short Blant life for the individual gum naval stores operator.

Lack of chemical control over products is still a very important point. The wood phase of the industry has not had this to cope with, and has been blessed also by the fact that most of the units are few in number and Iargc, or are supported by large companics having money for research and able to employ technically skilled operators. Considcrations of cost have not, becn as important in the gum industry as it’ might seem. However, probably the main reason for the slow development of improved methods has been the lack of research facilities and the insistance of those in the iridust any new methods be extremely to opcratc. Palmer (6) stated. in 1935, that’ there is no implication that technical advances have been lacking in gum turpentine and rosin production, but thcy have come to a considerable extent from influences outside the in

These influences havc been 1y those of the Naval Stores Rc-

search Division of the Unit’ed States Department of Agriculture, and of the Glidden Company, which only in very recent years has gone into the gum business, and to a lesser extent those of other Tyood naval stores companies who have initiated programs in gum rcsearch. It was not until the early 1930’s that the h7aval Etores Station a t Olustee, Fla., was established; the research labora- tories a t Yew Orleans (formerly in Washington) provided a fore- runner to this work.

The old fire stills were very simple affairs; generally thry con- sisted of large copper kettles heated directly by a wood or oil fire. The turpentine was distilled off with water and separated by gravity; the rosin remained in the kettle and was removcd and strained in a niolten condition at the end of the run. In the transition days of the middle thirties the h-aval Stores Station had designed a modern and much improved fire still for the larger operators, including provision for temperature recording and ob-

TABLE I. UNITED STATES PRODUCTIOS OF NAVAL STORES, 194@ Production

Jan. 1 Lo hprd 1 t o July 1. 1947 t o Mar. 31, 1948 June 30, 1948 J u n r 30, 1948

Turpentine 50-Gallon Barrels Wood plants

Steam distilled Destructively distilled Sulfate

Total TTood Gum stills Total gum and wood tur-

pentine

55,800 750

33,200 89,750 2 3,7 10

115.460

50,510 550

28,180 79,240

104,000 183.240

- ~~

.

138,918 2,740

98,687 260,34Z 204,469 464.814

.__

Rosin Drrinis of 620 Pounds S e t

S tca-~- -.- ..-.. - -. . , . . . Gun1 stills 84,700 Reclaimed rosin 1,420 ToOal gum 86,120 Total gum and wood rosin 382,720

__

Blants rn diqtTlled b m e eon 294,SOO 871,950

271,080 589,433 720 2,113

591.546 271,800 566,300 1,463,496

Other Productsc 50-Gallon barrels

carbons a Data from U. S. Dept . of Agriculture Annual Saval Stores Reports (1 8 ) b Total primary production of FF wood rosin. Stocks exclude by-

products, such as B wood resin, produced In refining FF wood rosin t o palei grades.

C Includes consigned stocks.

September 1948 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 1697

servation of the progress of the distillation. This plan combined the essential features of fuel economy, even heating of the kettle, better fire protection, and a better product. After the water present in the gum is removed, water must be added to the still t o finish the operation. Although this water is added hot from the condensers, the fact tha t i t must be vaporized prolongs the operation considerably compared to methods where the water is added directly in the form of steam. An additional serious ob- jection to the fire still is the fact that the chips removed from the rosin will be impregnated and coated with rosin up to 50% by weight, resulting in serious losses. The Southern Resin and Chemical Company at Glen-St. Mary, Fla., still uses the fire stills method and operates a model plant in a model community; one of the largest fire stills in existence today is that of the Knabb Turpentine Company a t McClenny, Fla. (Figure 1). But Speh’s prediction has come true; steam distillation has sup- planted the fire still. For the last decade the use of batch steam distillation has been on the increase until today there are only about 100 fire stills left; these will probably disappear within the next few years.

The batch still consists of a cylindrical tank containing steam coils and spargers. The distilled turpentine is condensed, separated from the water by gravity, and the final traces of water are removed in a dehydrator, which is essentially a receive1 containing 4-mesh rock salt, through which the turpentine passes upward. At the end of the charge the rosin is drawn off the bottom and packaged.

To the batch still’s disadvantages of time consumption, small capacity, inadequate equipment and methods, and lack of product control, were added problems of cleaning the gum. The commercial centralized cleaning of gum by the Olustee process began in the 1935-39 season, with the Operation of the first government type plant a t Hoboken, Ga., by K. S. Varn, and the central batch steam still was used along with it. The batch steam process was actually developed first and was not entirely successful because of the dirtiness of the gum-this was one of the basic reasons for development of the Olustee method for gum cleaning (15). Since the advent of the central still the owners of the pine stands are largely gum farmers instead of processors. They may have from 500 to 10,000 faces (a term applied to a series of wounds on the tree from which the exudate is obtained). A stand of 10,000 faces is termed a crop. Estimates of the present number of gum farmers run as high as 40,000, and the smallest processing plant has a capacity of about 100 barrels of gum per day. Since the introduction of the steam distillation procees there has been an improved government-type batch still developed. The first batch steam still was made from an old fire still, with a cone bottom, steam coils, and spargGrs added. The improved batch still is made of stainless steel instead of copper and is cylindrical in shape. There are today in the southeastern United States, 31 central stills, of which about 7570 use the Olustee method; the others use either a slight modification or an entirely different method. These methods will be dis- cussed briefly in a following section. According to geographical location the central stills are distributed as follows: Alabama, two; Florida, five; Georgia, twenty-four.

The really important step in the progress of distillation of turpentine

ment for which the industry has hoped since steam distillation was first introduced-a workable continuous process-has ar- rived. This discussion will center around the development of this continuous process from its beginnings up to the present 12-inch commercial scale still.

PREPARATION

Gum spirits of turpentine is usually about the same quality if properly distilled, whether it comes from a fire still or from a batch or continuous steam still. Rosin, however, varies greatly in quality according to the methods of processing used, and the profit in central still operation comes in the upgrading of the rosin which is made possible, in the additional amount of rosin recovered over the fire still and in the stilling methods.

Long- leaf and slash pines are the source of the gum, obtained by chip- ping or wounding the tree, technically termed streaking. Streak- ing is usually done during a 32-week season from spring to fall, once a week with a streak 0.5 inch high and 0.5 inch deep. The face should be limited to not more than one third the circumfer- ence of the tree, or 14 inches in width. I t is started as near the base of the tree as a cup ran be hung and is extended upward over a period of time to a height not to exceed 100 inches (page 1695). Acid stimulation is recommended by the United States Forest Service (I), using a sulfuric acid spray (60$& solution for long-leaf pine; 40% for slash pine), in which ease streaking need be done only twice a month to obtain the same or a slightly better yield. The exudate is collected by means of gutters and cups, and the cups are emptied every 3 or 4 weeks for delivery to central gum cleaning plants.

Crude gum is bought on a grade and yield basis, by the standard barrel (435 pounds). It is first judged by its appearance as to rosin. grade expected, then by its cleanliness as to probable yields of turpentine and rosin. Figure 2 shows the buyer evaluat- ing the crude gum a t the Keu ton Company’s gum naval stores processing plant at Lake City, Fla. The Federal Naval Stores Act of 1923 established twelve grades of rosin on a color basis. These grades are X, WW, WG, 3, M, K, I, H, F, E, G, and D; the color increases from a pale yellow, X, to the dark reddish amber, D. They may be grouped generally as pales (X-N), mediums (It-I), and darks (H-D), The most important items affecting rosin grade and yield (14) are: (A) condition of cups and tins (poor condition results in iron stain); (B) age of face;

The process of collecting the crude gum is a simple one.

from gum rosin, however, has been made in the last year. The improve-

Figure 2. Gum Buyer Grading Gum at the Newton Company, Lake City, Fla.

1688 I N D U S T R I A L A N D E N G

(C) dirt and trash; (D) distance gum flows over face; end (E) amount of scrape. A and B affect the grade; the ather factors may deet both the grade and the yield.

GUM CL~;ANINQ. Unless impurities in the crude gum are removed, particularly iron and trash, they impart stain (lowering the wade) as well as haze to the finished rosin. For these reasons and to eliminate waste, the Naval Stores Research Division d e veloped the Olustee gum cleaning process. The basis for this method is the fact that filtration and washing of the crude gum is carried out readily if the gum is diluted with turpentine and melted; the diluted gum then is filtered and washed with water. AII commercial methads of gum cleaning involve filtration, but the water-wash step, as such, is peculiar to the Olustee process. The Newton Company at Lake City, Fla., is considered to be typical of the best central plants.

The crude gum is drswn from a 9(F to 100-barrel charge vat to the blowease. Here 0.25 pound of filter aid (diatomaceous earth) and 0.25 to 0.5 pound of oxalic acid per barrel of gum are added. This latter is used to remove iron stain in the form of iron oxalate, thw improving the grade of the gum. The charge then is heated in the blowease until slightly warm steam-blown to the melter, diluted to 30 to 35% turpentine, an$ is heated with steam jacket and spargem to 200- to 220' F., depending on scrape content. (Scrspe is gum that haa hardehed on the face of the tree as compared with d!p which is the liquid gum collected in the cups.) Fmm there I t is steam-blown to the Sparkler filter, paasmg through a &mesh screen in the bottom of the melter. This filter is a stainless steel horiaontal filter containing thirteen plates 33 inches in diameter (about 75 square feet total area). The iilkr papfr is a 75% rag and 25% sulfite material. Pressure in the iilter IB from 10 pounds per square inch at the beginning to 35 pounds when the filter is to be redressed, and fifteen charges of 12 barrels each can be run through before the filter paper must be changed. The filtered gum is sprayed into about 400 gsllona of

I N E E R I N G C H E M I S T R Y Vol. 40, No. 9

ws[erat room tempwaturein tlre bottrmolthen.a~htank; then thrtankLb:fillrd wirhgumandthr\\.atrr-gumemulsioninalluwtd ' T O settle for a 4- to 8-hour oeriod: sltcr wttlinn thr rleanvd pum is drawn off to the still or i o a charge tank.

I

There are two other commer.cial cleaning processes in use in the industry: one is the process used by the Glidden Company in producing Nelio Resin, a patented dehydrated gum rosin containing approximately 20% turpentine; tbe other is used in pro- . ducing Nelio Rosin, a gum rosin made by the patented Nelioproc- esa developed by McGarvey Cline. In the Nelio process crude gum and R pulverized charcoal (as a filter aid) are dropped into a combbt ion melter and filter which is steam jacketed and con- tains spargers. If necessary, enough turpentine is added to the crqde gum a t this point to bring the content up to that of a barrel of crude gum or "dip." Brine is pumped up from the bottom of, the melter, forcing the gum through a 4mesh screen and four cloth filters at the top. Cotton flannel, light filter twill, and un- bleached sheeting are used most often as filter cloths in both this process and in the second or fltered rosin process. In the filtered rosin procaw the filtered gum-brine mixture goes to a separation tank from which the gum is Sed to a batch still which is run st 29Ei9 to 300" F., under a 20- to 25-inch vacuum, as compared with the Olustee batch still atmospheric pressure operation at maxi- mum temperature of 320O to 340" F.

One of the oldest central stills in the Southeast is that of the Shelton Navd Stores Processing Company, at Valdosta, Ga., formerly a plant of the Filtered Rosin Products Company of Georgia. This plant uses the filtered rosin process for cleaning, as do the two remaining planta of the Filtered Rosin Company at D o u g h and Baxley, Ga. The plant at Baxley, however, wes the OIwLstee procass also in the new unit recently completed. The filtered ro- D~OWSE is based on Dressure filtration and removal

i f ' , ; . . ; . , "'. ,:


CONTINUOUS DISTILLATION

J. 0. Reed of the Naval Stores Research Division patented a process in 1944 for the continuous distillation of turpentine (IO). The Reed patent did not provide for a flash chamber in the true sense of the word, therefore the gum had to be extremely dilute (60Cj0) and its best production rate was about 1000 pounds of rosin per hour. Mr. Reed's objectives, however, were sound and were used as a basis for modifying his original ideas to produce the prcscnt successful continuous still. He stated that the general object of his invention was the provision of a process and appa- ratus for manufacturing turpentine and rosin from oleoresin which would result in the production of turpentine and rosin with uniform compositions and which would not require exGessive amount>s of steam to distill the turpentine, thereby reducing the amount of required heat. A furzher object of this invention was t'o provide a method of the type mentioncd by virtue of which the ma- terials were not subjected to prolonged heat,ing, as in the batch process. Such prolonged heating adversely influences the grade of the rosin products. To accomplish these objectives, he provided nieans whereby the turpentine was distilled in a continuous proccss, rather than in batches, and the conditions of distillation were' maintained substantially constant without prolonged heating; this resulkd in a uniform composition of both turpentine and rvsiii.

Continuous distillation of gum turpentine represents no radical departures from ostablished principles. However, the system departs considerably both in design and operation from the batch steam still. used in the wood m v a l stores indust,ry, both because of its sim- plicity and the fact that it is operated a t atmospheric pressure.

Guni cleaned by the Olustee method, and therefore having B turpentine content of 30 to 40%, is preheated to about 350" F., and sprayed into the flash chamber, where about 70 to 807, of tho turpentine is flashed off. The rosin flows downward through the steam-jacketed column, and a current of live steam, passing. upward through the column, removes the remaining turpentine

It differs from continuous processes of distillat'ioii ,

to produce a merchantable rosin. The stripping coluinn acts as a wetted wall column, the rosin running down as a film on the column walls. Calculations show that about 96'34 of the rosin or partially distilled gum flows down the wall and 4y0 falls freely in the open column. Steam rising upward within the column produces turbulence on the falling film of rosin, thereby giving a better stripping action. No attempt' has been made to measure the thickness of the rosin film. The turpentine is removed continuously to a condenser, then to a decanter where it. is separated from the water, and rosin is removed continuously from the bot,tom of the still.

The first work at Olustee mas carried out using a 2-inch vertical pipe, then a 6-inch, but these were soon replaced with an 8-inch pipe; this provided a throughput almost double that of the 6-inch pipe. A successful commercial demonstration using this still was made a t the Newton plant at Lake City, but since no en- trainment trap was used, it was found that the resulting turpentine contained entrained gum, resulting in high acidity. An en- trainment trap was included then in the 8-inch and the later 12- inch design. It is considered probable t'hat the 8-inch design may prove advantageous in cases where production is less than t,hat of the average batch still. However, in order that the continuous process would have capacities equivalent to, or bet'ter than, that of the average large batch stills in current use, the 12- inch still was developed. Because adequate condensing capacity has not been available to date, production in experiniental runs has not reached the desired figure of 10 barrels of finished rosin per hour (8000 pounds of crude cleaned gum per hour feed). 'Table I1 gives a comparison oi" capacities and production times for fire, batch, steam, and continuous distillat,ion stills, with an estimate of their cost,.

Six runs on the 8-inch still resulted in a block of data which is considered to be t,ypical of,that which would be obtained on any central still layout. The cleaned, washed, gum fed t o the preheater had a range in content of 57 to 69y0 rosin, 30 to 407, turpentine, and 1 to 3% wat'er; the average composition was 637, rosin, 357, turpentine, and 2 7 , water. From this was obtained a rosin of normal melting point and pure gum spirits of turpent,ine with a gravity within the proper range (0.86 to 0.875). By using t,he preheat temperature of 350" F. it, was found that the still was operated properly when the distillate contained 45 70 water and 55% turpentine.

Average throughput with the 8-inch still was 3200 pounds cleaned gum per hour; it ranged from 2500 pounds per hour at

I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 40, No. 9

BIFFLE

TO FLbSH CHbYSER

t

TURPENTLNE TO CONDENSER

MODIFIED TO SHOW

OEHYDRbTING

CONDENSbTE FROM JACKET

glass body being of wrought iron. The flash chamber is 36 inches in diameter and 82 inches from flange to flange. The b d e in the top of the flash chamber consists of two Pinch rings of stainless steel, 10 inches apart, and a cone-shaped h d e 6 inches deep and 32 inches in diameter between the rings.

Use of a double flash chamber was tried but results showed no material savingin steam consump tion or improvement in dryness of the ragin.

The stripping column consists of a l Z i c h p i g within a 16inch pipe, both of black iron; the annular space is used 88 a steam jacket and carries steam at 100 pounds per square inch pressure (321" F.). The inner pipe is 316 stainleas steel clad and both consist of two sections, 5 feet and 10 feet in heiaht, . . for ease of construction and

F- 4. Detailed Drawing of Flash Chamber .nd.Stripping Column, l2-Inch Still handlink. Three Pinch stainleae

110 pounds per square inch steam p m u r e to 4500 pounds per hour-at 165 h n d i pressure. The variation in steam prceaure h a n c f i i b l e eiect on the steam consumption per pound of fced. Ta le 111 kves averare omratinn conditions. based on thc six - . - measurd rim.

Using published heat transfer data (B.t.u. per pound) as follows: latent heat of turpentine, 134; specific heat of turpentine, 0.41. specific heat of rosin, 0.52; specific bent of feed, 0.49: and coefficient of heat transfer (9). 300 to 500 B.t.u. per

- . - measurd rim.

Using published heat transfer data (B.t.u. per pound) as follows: latent heat of turpentine, 134; specific heat of turpentine. 0.41: soecific heat of rosin. 0.52: snecific bent of feed. 6.49: and edefficient of heat trhsfer (9). 300 to 500 B.t.u. per hour' per s uare foot per ' F., the following average steam cbn- snmption &urea were obtained: preheater, 0.132 pound per pound of feed; jacket, 0.040 pound per pound of feed; and snarzer. 0.317 wund ~ e r Dound of feed: or a total of 0.489 &&d of steam-per pound of feed.

With the hatch process approximately one pound of steam is required for every pound of feed; about 0.2 pound of this is sparger requirements. If the continuous still were operated without sparger steam, it would be poeaible to obtain a dry msin with a turpentine content of 15 to 25%. In order to reduce further the steam consumption, experiments were made using a b d e d stripping column, and i t was found that the %inch atill when provided with three half-moon bafflea reqnired an average of only 0.3 pound of steam per pound of feed. The disadvantage, however, comes in a decrease in throughput of approximately 25%. However, optimum ba&g may he included in the recommended design. Figure 3 is a flow chart of the continuous distillation process,

and Figure 4 is a detailed drawing of the Bash chamber and stripping column of the 12-inch still. The gum is pumped from the w d tank by a rotary positive-action pump to the Brown fintube preheatm, a steam-to-liquid type heat exchanger of the expanded surface type. Three standard tube-in-tube, return-bond, twin- section typea will handle 8ooo pounds of dilute gum per hour. The exit temperature of the preheater (approximately 350' F.) c a ~ he governed with a by-pass around the pump. The preheated gum is sprayed under 25 to 35 pounds per square inch pres- mre into the Bash c h h e r , using a standard hollow-cone type spray n o d e 10 mm. in diemeter; a design is chagen to give as b t a spray as possible.

The still itself is considered to consist of three parts: flash chsmber, stripping column, and dehydration zone. All of the &ashchamberinI€-gagestainlesssteel. with the flangesandsight-

steel pi& (straight pipes with a 90' welded ell connecting them

to the column jacket) 63.5 inches long carry steam for he& ing in the bottom or dehydration sone, and three steam spargem are placed at heights of 30, 39, and 48 inches from the base of that zone; the rasin liquid level is kept at approximately 5 feet above the base. These spargem are of 0.75-inch stainless steel tubing, perforated on both sides. Dehydrated rosin is received in drums from the bottom of the stripping column, as shown.

The use of the Flick centrifugal type separator as an entrain- ment trap between the flash chamber and condenser has resulted in a turpentine containing only a small amount of entrained gum (acidity normally less than 200 mg. of potassium hydroxide per liter of turpentine). This compares with about 400 mg. of pc- tassium hydroxide for a turpentine normally produced on a p r o p erly operated fire still and slightly greater than 400 mg. for a hatch steam still. This separator consists of a horizontal pipe 8 inches in diameter leading into the bottom of a 20 X 30 inch trap made of @ounce copper and containing eight copper impact vanes 24 inches long brazed vertically to the internal periphery of the trap. The vapam enter the trap hngentially at a velocity of 100 feet per second. whirl around to the top of the trap, and turn through 180 degrees, pasaing out through an %inch diameter

TABLE 11. COMPARISON OF TURPENTINE STILL TYPES Contiovovs

Fire Batch Still 8tilP Still kinehb Iz-inch'

Distillation time 2.5hr. 30to40mio. .. . .

Barrek crude gum wr 8-hr. 80 196 Bo 112 ca?%a crude sum per hour 1740 8wO azo0 6 ~ 0

~~

&Y. Production per hour. Barrelafinishedrosin(520Ib.) 2 .2 10 4 . 2 7 . 5 Gdlona turpentine (7.2 Ib./ 48.5 3404W 142 235


vertical pipe placed 5 inches from the top of the trap and extend- ing through bhe bott'om of the trap.

Experimental work is being carried out now using packing in the column in a further effort t o reduce steam consumption and to produce a drier rosin with a higher meltling point. The aon- denser in current use is 16 inches in diameter, 9.5 feet long, and will handle the turpentine from 6000 pounds of cleaned gum per hour, Tubes, tube sheets, and head are of stainless steel. This condenser will be augmentcd to take care of the greater condensing load. A 150-gallon black iron separator, painted on the inside to resist, turpentine, is used as a separator, with the water leaving the bottom by gravity flow. One type of paint thus used has been a mixture of red lead and natural shellac in an alcohol solution. -1 commercia! paint known as Jones Cup Paint also has been used for t,his purpose. These paints are used only when the separator or dehydrator is made of black iron. Experimental work a t the Kava1 Stores Station indicat,es that, a nickel or nickel- clad container is best: stainless steel is suitable, but the brine in t,he bottom of the dehydrator oft,en pits the containcr after 1 or 2 years of use. The turpentine is given final dehydration by passing it through 4-mesh rock salt before it goes to the receiver. Water-white turpentine and a rosin, pale in color and brilliantly clean, result (8).

ADVANT.4GES. The advantages of the continuous distillation method over the batch atmospheric distillation process are sev- eral. There is a considerably lower capital investment involved, as shown by Table 11, and a 50y0 reduction in steam consumption. At least two men are required t o operate a batch still and package the rosin; it appears that this work can be handled satis- factorily by one man with the continuous still. The continuous still occupies 75% less floor space than the ordinary batch still; casual examination of Figure 5 , taking into account also the large charge tank required with bat,ch stills, v:ill confirm the difference

Figure 5. Batch Still, Newton Company, Lake City, Fla.

TABLE 111. AVERAGE OPERATING CONDITIONS 8-Inch and 12-Incha

Continuous Stills Average, Range, '

Feed temperatures F. F. Entering pump 150 135 to 155 Entering preheatcr 160 135 to 155

340 to 350 Entering flash chamber 345 Distillate temperatures

Vapors from flash chamber 300 290 to 310 Distillate from condenser 100 90 to 110

Cooling water temperatures Entering condenser 80 70 to 90 Leaving condenser 165 140 to 190

300 to 340 Rosin leaving still 330 Pressure

Flash chamber

Steam

Flashed from 25 to 30 Ib. per sq. in. to atmosphcric

110 to 165 Ib. per sq. in a Final opt imum steam consumption figures for the 12-inch still are not

yet available.

in space requirements. Probably one of the more important advantages in wing the continuous still is the small operating load. Only about 5 minutes throughput time is required from the preheater to the rosin drum, therefore only relatively small quan- tities of robin are in process at any given time. I n the ordinary batch still more than 5000 pounds of rosin would be handled throughout the run.

Thc old time fire still was operated without temperaturc control ( I S ) ; regulation was based on sound. By listening at the tailpipe of the condenser worm the operator was supposed to be able to tell what was going on inside the kettlc because of different sound characteristics due to differ- ences in performance. Fire stills now have temperature control and the progress of the run is observed by examination of the distillate. In the batch still the water to turpentine ratio in the distillate represents an approximation of the amount of turpentine left in the gum, and therefore the progress of the distillation, and the turnout or end of the run is effected when the turpentine content of the distillate is approximately 5% by volume. I n both the fire still and batch still operations, of course, the water to turpentine ratio can never beponstant; regulation of this ratio in the continuous still is easy. Since the amount of water introduced with the crude, cleaned gum is reasonablv constant and therefore need not be taken into account as i t must be in the fir? and batch stills, the water to turpentine ratio in the case of continuous still operation indicates how much steam has been introduced at the spargers. The more steam introduced, the less is the amount of turpentine in the finished rosin; thus the amount of turpentine in the finished rosin ran be easily judged from the water-turpentine ratio.

It is of interest to note that the continuous process can be suc- cessfully used with undiluted gum; tha t is, i t is possiblc to make in the continuous still rosin of any desired turpentine content, or hot rosin which can be delivered from the bottom of the still directly into the tank car, patented bv Hercules, for the shipment of hot or liquid rosin. It is expected that this latter point will prove of great immediate interest to a number of centra! still operators.

OPERATIONAL TECHXIQUES.

FUTURE-PROSPECTS

There is much conjecture within and without the naval stores industry today as to just what the future holds. The industrial revolution that has taken place in the gum phase of the industry in thp last decade has certainly been of incalculable value to it. But the phenomenal rise of the wood phase of the industry, and more recently the competition of sulfate turpentine with gum spirits of turpentine (because of the successful removal of odor from the former) has seriously affected the gum phase. &lost important, however, is the competition from low priced petroleum products which are supplanting turpentine as a paint thinner ;

1702 I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY Vol. 40, No. 9

ones until very recently; if there is to be a bright fut,ure for thr naval stores industry it must be related to the manufacture of chemical derivatives. Schantn (11) in a summary of naval i torrs research, listed among the terpene hydi,ocarbons presently inann-

" 1 to .ir,ril 1 t o J ~ ~ , 1 to rlgril 1 to Factured, isobornyl thiocyanoacet'at,e, terpene ethers, 0-pinriic foi . Industry ~ a r . 31 June 30 ~ a r , 31 .''me 30 polymer resins, monocyclic t,erpenes for i ~ h b e r reclaiming, aiid in

Ahbatoira 0 0 4,,23 133 the preparation of sulfur derivatives for use as oil additives. 48

97 19.8 240 Production of isoprene ant3 rnent~hyl phenol from dipcntenc did ilutomobiles and wagons 1.5 18 53 64

30 118 Adhesives and plastics hsphal t io products

Chemicals and e j , p 1 2 21,984 91,080b 89,698 not continue after the war. TIe also inentions an expanded ust: Ester gunla*ds~'nthet icreyins 4.386 4 1 4 0 2 6t::ii 6+;:E; of the glycerol ester of hydrogeriated rosin in chcwing gum, initial Foundries and foundry supplirs 178 184

Insecticides and disinfectants 4 4 663 625 0 10,812 10,807 sihle use of a new terpene thiol in synthetic rubber polynivrize- Linoleum and floor covering 0

Oils and greaSes 11 21 Paint , varnish, and laciiuei 3 . ~ 5 ~ 3,647 28.739 3 1 . 1 5 4 tives.

In the ficld of iniprovi:nieut of prrsenf products, the: Kava1 Payer ancl paper size 0 Print ing ink 44 Railroads and sliiliyards 1,288 1.276 4,262 4,z!$ Stores Station, after having worlced Cor sevcral years in this dircc- Rubber 117 87 Shoe polish and shop inxterixls 757 808 1,133 929 tion with rosin, has 1 1 0 ~ mimed to turpentine. In the Iield of new

products they are attenipting to treat t,hc products froni gum soap 0 Other industries

x6 ,17 , j 32,710 B30,53jb 330,353 naval stores as raw chcmicds. . is far as the chemical industry i b Total rcyorted concerned, some of these ai'o iiierely LT-ell recognized basic ma.- terials; with naval stows people they are definitelv new matc~iiuls. Reports.

~ " ~ o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ i ~ ~ ~ ~ ~ ~ m ~ ~ &';e,a",;g$yj2 ~ ; ~ ~ ; $ ~ t , ! b : , l ' $ ~ ~ ~ ~ Chlorinated pinenes for insecticide usi: are among t h e pi'otlucts resin ab such. from turpentine being invePtigated at A-rw Orleans. (Tn t,hr

T A B L E I T r . RIGPORTED LTTNITED STATER h-AYAL STOREX CONHV~IPTIOS 1948"

'Turpentine, jO-Gallon Barreis - ~;$+o$:;u,m&e~f

Furni ture 37 47 1 1 ivorli on. a primary arninc and a nitrile froni modified rosin, po+

Matches 0 0 3,22ci 160 3,8:'z tion, and the use of terpwie thiol copper compounds as oil addi-

0 8J,.i76 93.504 1.536 1,377

37 1,239

0 30,130 23,443 942 31 30 019 -___

cL Data obtained f r o n i t-. S, D?pt. of Agricu!turc Annual S a v a l Stores

today at least' SO'$, of the thinner sold industrially is petroleum- derived. The development of packaged turpentinr marketing by the American Gum Turpentine Farmers' .issociation has helped to meet this competjtiori arid according l o Hosmer (3) has helped to create a househcld and consumer markel for the prodtic- t,ion of turpentine which has approximately absorbed the production. He points out t,hat guin turpentine is sold almost entirely in package form through retail paint, ha,rdm re, and drug stores, aiid that' only about 8yc of the consumption is iudustrial.

Competitive inroads on the turpentine market have not so much affected the demand for rosin, whicli lias a vei3- heavy consumption in the paper industry as sizing, and in soap manufacture (17) and for conversion to resins for use in protective coatings. Yet since turpentine must be produced along v3th the rosin, IICK

uses for turpentine must be found i f the industry is to continuo healthy.

There also is a vague feeling of uncertainty anio~ig the coni- panies engaged in mood naval stores production because the fact that gum naval stores can be produced as a ci'op giws the gum industry a very definite edge. The most optimistic estimates a r e the end in 40 years of the stumps left when the virgin pine forest were cut! and it is definite knowledge that second growth pine. while giving good yields of gurn, simply rannot be utiliscd a 5

stumpage for the wood naval stores plants. This is in large part due to the fact' that, second-growth pines are being cut, long beforr thev have sufficient heartwood. I t is therefore probable that the companies engaging in wood naval stores production n-ill lean more and inore to research along lines of gum production in thc, next few years.

Hosmer rest>ates a fac t that is becomiiig well recognized in thc gum naval stores phase of the industry-that the niajor need is for well planned research-research aimed at the accomplishmt-ti t of two objectives:

To obtain more information on the basic chemistry of both rosiii and turpent,ine as a means of developing new uses and, particularly, products; Pallrin (6) presents a comprehensive reviem- of the acids of pine oleoresin and rosin.

To conduct process research designed to det,ermine t,he requirements in composition and grade for the present uses and to deter- mine the most effective ways in which either rosin or turpentine can function in the processes in which they now play parts.

Table IV shows the major current uses of both gum and wood turpentine and rosin. Thesc uses have been largely mechnniral

vood naval stores field, Hercules i s increasing the output of loxa- phene, its chlorinated camphenc pvoduct.) 8-Pincne will bc t h c starting niatei,ial for a large family of terpene compounds i n addi- tion to these chlorinated piiieii nd synthetic camphor. S ;~pa- ration of resin acids from which new product9 can he matie also is recciving considerable attcntion in the resin field. Va,rious a.ddi- tion products of turpentine arid i,osin and of t,he gurn itself arc under investigation, and pilot plant, production of the malci(* mi- hydride adduct of I-pimaric acid has been carried out. This \\-hito powder a1)pears promising for use in paper coatings, anti ix varnishes, and currently is being investigated for possiblc UPO in chemical rubber manufacture. In this particular c a w thc Olustee clcaiiing process a s n o ~ v practiccd for norniul gum refining cannot be used on the c i ~ i d r gum, since I-pimaric acid changes on heating to abic'ti, acid, hut a process is being devc~loprtl t o accomplish this.

Perhaps Homier's predictions (3) are not tou optimistic:, n.hvn ,says that if the gains in the last 10 year's can be consolidated and then follovwl up with technicalrcsearcho~igur1inavali;torrsc~qual- irig or escepding that already done by the wood phase, then the gum phase should become au expanding, stabilized, a,nd noi~nially profitable segment of business. I t will certainly hcar wat chinp.

Ll'I'ERhTURE CITED

(1) Ge. A g r . Ezpt. Sta., B~t l i . 532, February 1947. (2) Hightower, J. V.. Chenz. Eng., 54, 119~-21 (1947). (3) Hosnier, J. E., Ga. S ta le E n ~ r . Ezp . Sta., BUZZ. 12, Maj. 10.1);. (4) Humphreg-, I. W., 1x1). ENG. CHEX.. 35, 1062-7 (1943). (5) Palkin, S., J . Chem. Edt ica t io?~, 12, 35-40 (1936). ( G ) Palmer, H. C., IKD. EKG. CHEM., 27, 741-4 (1935). (7) Patt,on, E. L., I h i d . . 40, 996-7 (1948). ( 8 ) Patton, E. L., "Modern Techniques foi Procesaiiig Pine Guiii"

presented before the National Meeting, Forest Product- I<<.- search Society. Oct. 31 t o Kov. 1, 1947.

(9) Patt.nn, E. L., aiid Fcagan. 11, .i., IND. ENG. CHXM., 33, 1237--9 (1941).

(10) Iteed, J. 0.. U. S. Patent 2,363,692. S o v . 28, 1944. (11) Schantz, J. AI. , Chem. h d s . , 61, 392-3 (1947). (12) Srhanta, J. M., and Marvin, Theodore, IND. E K ~ : . C H m r . . 31,

(13) Shingler. G. P., I\-aonl Stores Reciezi:. 51, 10, 16, 20 (1942). (14) Shirley, *4. R., U. 8. Dept. of -kgr., B u r . Agr. C'hrm. io' E'rrg.

(15) Smith, TT. C., Reed. J. O., Veitch. F. P., and shingle^, <;. I'..

(16) Speh, C. U , , Proc. Am. Soc. Testing .Katerials, 26 (In, 3%41

(17) Speh. C . F., IKD. ESG, CHEM., 31, 166-9 (1939). (18) C . S . Dept. of -481.. B u r . A Q ~ . Economics, .Vam/ A'tows R~,?wi t

IST quai'tei', 1948.

585-5 (1939).

Report ACE-5, undated.

U. 8. Patent 2,254.785, Sept. 2 , 1941.

(1926).

4th quarter, 1947:

Kr;cEx\-r:n .Tuly 15, 1948.

continuous distillation of gum turpentine

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