March, 1933
Ii Y D U S T R I A L A I\; D E N G I
one of them alone or the combination of any t\vo of them. It has been shown further that, although it is possible to obtain good vulcanized products from this polymer Tvithout the addition of sulfur, a great increase in the rate of cure and substantial improvement in physical properties of vulcanized from the use Of as little as O'' per cent Of products It is further shoWn that Of the polymer' On the pine tar and rosin oil may be substituted for rosin but that
N E E R I N G C H E M I ST R Y
283
they are somewhat less efficacious. The authors postulate that the value of rosin, pine tar, and rosin oil is probably due to the organic acids that they contain. Coumarone resin and brown factice are shoivn to be desirable compounding ingredients for chloroprene polymers. RECEIVEDAugust 29, 1932. Presented before the Dlvlsion of Rubber Chemistry a t the 84th Meeting of t h e .$mencan Chemical Society, Denver, cola, August 22 t o 26, 1932.
Flow of Paper Pulps in Pipe Lines C. A. BRAUTLECHT AKD J. R. SETHI,University of Maine, Orono, hle. facilities for determining data U R I S G the rapid dePower required as a ,factor due to friction in i n v o l v i n g w a t e r and fluids. velopment of pulp and the pumping of paper p u l p s has been studied o n Usually, however, the equippaper mills of ever ina small scale experimentally. Power consumpm e n t f o r agitating pulps in creasing size, the need of pumption in p u m p i n g cellulose (screened unbleached s u s p e n s i o n , s h r e d d i n g , or ing and flow of pulp has been suljite p u l p ) in dilute suspensions through a breaking up pulps obtained as one of the most important facsheets or pressed laps, etc., is tors. Cost of capital invested, &inch centrifugal p u m p and varying lengths of not available. I n addition, the equipment , economy of operaone-inch p i p e have been determined. Seventeen i n t r o d u c t i o n of pulps i n t o tion in a highly competitive intests have been made with inrialions in concentanks, pipe lines, pumps, and dustry, and maintenance have tration of suspension, length of pipe line, and v a l v e s i n v o l v e s considerable led to an effort to select motors, introduction of ,fittings. Power required to lift cleaning costs or other difficulpumps, pipe lines, and storage ties. tanks of sufficient capacity, but one pound of water or p u l p suspensions, up to One objective of this simple w i t h o u t too large excess and 1.57 per cent concentration, per minute per 100 e x p e r i m e n t a l s t u d y was to corresponding waste in pome r feet is the same; rate of discharge into a weighing and in operation and maintestimulate l a r ge-s c a1 e studies box falls quite rapidly with a n increase in length nance expense. Thus, engineero n t h e p a r t of organizations of pipe; with concentration constanf, increase in supplied mi t h the n e c e s s a r y ing data have been often sought without much of value b e i n g equipment, funds, etc., so that rate of floto increases velocity head and is proeventually complete data would found. Of the many types of reportional to the square of the velocity; friction ciprocating, rotary, and centrifube available for the h a n d l i n g head increases with rate o j discharge, which gal pumps, the plunger, openof suspensions of groundwood, raries with p i p e length; total actual effective impeller volute centrifugal, and sulfite, soda, kraft, a n d o t h e r head increases with increase in velocity; amount rotary pumps of the Sash type, pulps in all commercial concenare most used in the pulp industrations and for all pump and of power increases with rate of discharge; intry. Conversation and c o r r e pipe sizes. creased p i p e length decreases celocity of jlow in spondence with engineers having Scientific data wi!l be more in feet per second; and total actual head decreases to do with pulp mill design have demand in transporting paper with increased p i p e length because of the rapid indicated that little information pulps in the future because the decrease in celocily and velocity head. was available and that hydraulic "slush system" of moving pulp data were commonly employed in water suspension from pulp in connection with comtmtations to paper m i l l s i n v o l v e s : (I) or design for the pumping and flow of dilute suspensions decreased labor; (2) decreased waste, due to making laps, of pulp. The literature comprises only a few articles in rolls, sheets, or bales, and to transportation and the subsejournals and published data of pump manufacturers (4). quent resuspension of the cellulose; (3) decreased heat; Some companies pump pulps a considerable distance. and (4) decreased power. Every pulp mill using new wood The Fraser Company produces pulp in Canada and pumps it pulp logically should be associated with a paper mill, except across the St. John River to its paper mill in the IJnited States where a paper mill is in an old established locality where lorn a t Madawaska, hle. The Webster mill of the International taxes prevail, and where tariffs, embargoes, markets, pulp Paper Company involves the production of groundwood pulp costs, transportation, etc., do not act adversely. Pulp on one side of the Stillmater River, a t Orono, Me., and pumps mills with favorably situated timber holdings, or located a t it a t about 4 per cent concentration one-fifth of B mile to the the head or on navigable tidewater with rail facilities, will paper mill on the other side of the river. I n the control of always have a trade advantage with a n associated paper mill water power it is desirable for a pulp and paper company to a t the same location. own its dam and the property adjacent to the clam on both OBJECTOF STUDY sides of the river. This leads often to a consideration of a pulp mill on one side of a river and a paper mill on the other The chief objective of this study was to investigate some side, with the problem of a pulp pipe line to be solved. I n of the factors involved in pumping unbleached sulfite pulp many of the new large mills paper machines are also frequently through various lengths of pipe lines and also the effect of a a considerable distance from pulp grinders, screens, bleach few fittings. tanks, etc. (2, 7-9). The laws of flow of mater in pipe lines may be summarized hlany hydraulic laboratories throughout the world have as follows (5):
D
I N D I 1 S T 1%1 A L A N D E N G 1 N E E I \ 1 N G C El E hl I S T H Y
284
The loss in friction is nrouortiorial to the lcnrth . . . of the nipe, .. . with equal velocities. The friction increases n e d y &s tho square of the velocity. The friction deore$%ma deoreasea witlr increase of diameter of the pipe for any given length. The friction inereasm with the roughness of the interior surface of the pipe. I'riction is indcpendent of the pressure. Bernoulli, in 1738, worked out an equation for steady flow as follows:
,!'
+ z, + 4
1
p,
=
p?
+ + V?B 2Y El
(assuming that flow is steady, fluid is incornpresxihle, v e l o c i t y across any section is uniform) where p = intensity of water uressure, feet z = any vertical distance ahove any arbitrary d a t u m plane, it. V = absolute velocity, it./sec. y = gravity acceleration, ft./seo./sec.
Bernoulli's theorem states that along any stream line the effective h e a d r e m a i n s c o n s t a n t . This is not true, however, lor in a f l u i d which is viscous there can be no flow w i t h o u t some loss due t o friction. This loss of friction is expressed by K x V/2g, for by experiment it has been found that the friction loss is some function of the \,elocity. Hence, after correction, Bernoulli's theorem reads:
Written thus it states that along any stream line the effective head always decreases in the direction of flow. This is t m e both in theory and practice. Later, much work was done on tile measurement and flow of water through nxirs, Pitot tubes, Venturi meters, etc. The Venturi meter, invented by Clcnens I-terschel in 1886, by means of .~.tiicliaccurate measurement of the flow of water, oil, or gases can be obtained, employed the principle of the drop of pressure due to the increased velocity through the throat of a pipe RS a means for the measurement of fluid pn.ssing through the tube. (It may tie that a flexible metal diaphragm inserted inside of or in the inncr wall of a Venturi meter can be applied to pulp flow measurement.) Darcy, ('hezy, Hazeii and Williams, and Kutber (the latter on coefficient on roughness) and n host of other engineers have also made valuablc contributions to an understanding of pipe friction and friction factors for u-ater. Although much attention has been devoted to the study of water, and some to pipe transportation of crude oil or other liquids, almost iione has been given to pulp suspensions. Paper making u p to about 1865 involved the use of rags, their pulping in a beater, making up into sheets or rolls, drying,
Val. 25. No. 3
siring, and redrying in a relatively small space With the advent of mechanical wood pulps and chemical pulps, the pulp mill units were, of necessity, some distance from the paper machine; and, with the building of large pulp and paper mills, the distance pulp suspensions had to be transported became an increasingly important factor. As in most pioneer work, assumptions had to be made. Iior instance, the friction factor (f)in the formula for calculation of total head was assumed to be the same as that of water. This assumption is justified hecause a failing sphere moves at about the same rate through water as through dilute (0 t o 1.57 per cent) pulp suspensions (10). TIIEOItI
In early hydraulic s t u d i e s all particles of w a t e r (or f l u i d ) in a given cram section were assumed to move in parallel paths and with equal velocities; i n F i g u r e 1 a particle of water at point 0 moves along t h e a x i s of 8 p i p e with a velocity 0 B. Likewise, every other p a r t i c l e of w a t e r across scction 0'00' is assumed t o move with the samevelocity giving the v e l o c i t y c u r v e A B C, a straight line. It is well known, however, t h a t in a pipe the actual curve is similar t o A' B' C'; the velociLy of a particle of water 0 in the center of the pipe being 0 B', whereas that near the wall of the pipe is 0' A'. This difference is due to the friction of the circumferential particles against the wells of the pipe. This may be more or less according to the internal surface of the pipe, but, experimentally, it has been determined that in a smooth pipe and with a steady flow, velocity of 0 B' is twice that of 0' A', the mean velocity of 0' A'being 0.84 that of 0 B'. Actually, however, a steady flow and smooth surface are rarely possible in commercial practice. The motion of particles of water is not straight. They clash with other part.icles, and the walls of the pipe thus produce irregular velocity. This irregularity will increase with increased viscosity, coarseness, and specific gravity. In case of cellulose pulp, it can be expected that the velocity will be decreased owing to the kind and concentration af pulp, size of fibers, degree of surfaee hydration, and other factors. The mean velocity a t any section of the pipe is obtainable by dividing the total rate of discharge by the total area of the cross section. That is,
v = g/P (1) mean velocity total rate of discharge st any section, cu. ft./sec., gal,/day, etc. (volume of water flowing mmss any section per unit time) F = total area of cross section, sq. it.
where V
= p =
The equation far effective head is:
where H = effective head p = pressure head, ft. of water (the intensity) z = static head, ft. (the elevation of a point above any ordinary datum plane) V = velocity, ft./sec. g = gravity acceleration, ft./sec./sec. (32.16 ft./sec./sec. for water)
FACTORS AFFECTINGRATEOF FLOWOF LIQUIDSTHROUGH PIPE LINES The rate of flow of a liquid moving through a pipe under a gravity head is influenced primarily by three characteristics of the liquid itself-namely, its density, which supplies the pressure producing flow; its viscosity which retards flow; and its inertia, which under A 0' certain conditions manifests i t s e l f i n the dissipation of energy by the collision of the e d d pi n g particles. T h e s e three factors constitute what are c a l l e d the " i n t e r n a l group'' of factors affecting the flow. The other three factors, such as diameter, length, and roughness of the pipe, the 01 C1 gravity head, etc., may be FIGURE 1. VELOCITY CURVES called the "external group." Any or all of the e x t e r n a l factors may, in practice, be varied a t will, and the resultant flow will respond to these variations according to laws which may be experimentally determined and analytically stated. It was in a n effort to determine some of these factors experimentally with pulp that this study was undertaken. In a pipe line, therefore, the loss of head between two sections is apparently a function between them and the factor k , representing the roughness of the pipe. It is also found that the hydraulic friction is independent of the pressure and the temperature, the friction due to the latter cause being so slight that it can be neglected. The loss of head is expressed by H'=kX-
V"
2g where H1 = loss of head due t o friction of pipe k = a constant V = absolute velocity of water, ft./sec. n = a constant of varying value from 1.75 to 2.0 g = gravity acceleration, ft./sec./sec.
(3)
mately equal to f1/4m. =
rn =
friction factor (found experimentally by applying Bernoulli's theorem for a flow in a pipe, or found for water from the formula f = 0.02 0.02/d") area of water cross section, divided by length of wetted perimeter; m ,in case of a circular pipe, equals d / 4 , f o r m then is equal to: ?r X r2/2nr = r/2 = d/4
+
Thus the loss of head in a circular pipe full of water is:
where 1 d
-!! 29
pressure or suction head (if a pressure head, it is to be subtracted to obtain the actual effective head or lift) z = static head " = velocity head
where p
=
ti
fl/d X
V2 = H 1 = loss or friction head
%?
This is, therefore, the formula that gives the total actual effective head against which the pump works-that is, the height to which a given quantity of water is to be elevated. To find the theoretical horsepower required to elevate the given quantity of water or pulp to the given height, it is necessary to multiply the weight of water or pulp by this height and divide the result by 33,000 (for 33,000 pounds elevated one foot in one minute equals one horsepower). To determine the actual brake horsepower, we divide the theoretical power obtained by the efficiency of the pump, Theoretical horsepower can also be computed by use of the formula : H X G. p. m. h.p* = 3982 _.._ where H = head G. p. m. = gal. per min. and 3962 = gal. of water in 33,000 lb. The two formulas given above, one for the determination of total actual effective head (Equation 5 ) and the other for the determination of the brake horsepower, are the ones that have been used in computing the results, which have been expressed in watts instead of horsepower.
EXPERIMENTAL PROCEDURE The method selected as most suitable for the experiments to be performed was to weigh the quantity of a suspension of pulp in water which is discharged from a pipe line in a given time, noting the power required, theoretically and actually. Screened unbleached sulfite pulp was suspended in a pulp storage tank 42 inches in diameter and 62 inches deep. Six inches above the bottom of the tank was a 6-inch suction line to a centrifugal pump fitted with a 4-inch discharge pipe. A gate
,
i
length of pipe, ft. diameter of pipe, ft. = velocity head
= =
Hence the equation for effective head now is given by the formula : (5)
d o
SZOb
"._/
I
I
?$I1
It has been determined experimentally that k is approxiwhere f
285
INDUSTRIAL AND ENGINEERING CHEMISTRY
March, 1933
,
'
~ L/ " ~
0.1
0.2 0:3
0!4 015 0.6
0.7
0'8
0.q I O 1.1
112 1'3
I:+ 1:5 l!b
Percent Gonce ntration FIGURE 2 . PLOTOF CURVE1 valve in the suction line controlled the flow of pulp to the pump. The pump was operated by a 550-volt, 5-h. p. motor, and the pulp suspension was kept uniform by an agitator. The discharge of the pump was a 4-inch line, reduced to one inch. From this point, one-inch pipe was used on all runs made. The total height from the discharge flange of the pump to the highest elevation (including the 4-inch pipe section) was 8.16 feet. Horizontal sections of one-inch pipe were then used in various lengths with a few fittings attached in some runs and the flow of pulp suspensions up to 1.57 per cent concentration studied. The weighing box was supported on a platform scale so that it could be quickly weighed, either empty or full. It was also fitted with a valve so that it could be emptied quickly into the storage tank, a mark indicating when the weighing tank was filled to a determined capacity. There was practically no loss in stock during the runs so that the head of suspension in the storage or reservoir tank remained constant for each run. The time required to fill this weighing box to the mark was noted, and weight of suspension and power consumed were determined. Knowing the diameter and area of cross section of the one-inch pipe, the velocity in feet per second, and the discharge in cubic feet per second, the gallons per minute of stock could be easily computed.
INDUSTRIAL AND ENGINEERING CHEMISTRY
286
The unbleached sulfite produced in the laboratory, screened through a No. 10 flat screen, was suspended in water to yield an approximate predetermined concentration of pulp. After agitation and circulation through the pump, pipe line, and weighing box back into the tank until uniform circulation was obtained, t'he pump was stopped and the box weighed. Concentration of pulp in an agitat,ed sample was determined. Weighing box outlet was then closed and the motor started; time required to fill the weighing box was noted by means of a stop watch, pressure in line by gages, and power by a wattmeter. The weight of suspension was then determined. Vhile the box was being filled, revolutions per minute of pump, and pressure a t the discharge end of pump and a t end of discharge line were noted. Temperature of the room was from 42" to 54" F., and there was practically no loss of water by evaporation. Seventeen tests were started and sixteen completed, and about five readings were taken for each test. Concentration of stock was from 0 to 1.57 per cent; computed power consumption was from 18.7 to 85.6 watts, actually somewhat less because of assumption of 50 per cent efficiency for pump. The vertical pipe was constant a t 8.16 feet in each test. The formula for computation was: h
z
+ + H' Ti2 29
where z = static head (8.16 ft.) " = velocity head; velocity is found by dividing rate of discharge (cu. ft./sec.) divided by area of cross section of pipe (ft.), and is equal to q / F , where q is rate of discharge (cu. ft./sec.) computed from weight of discharge (pounds), and F is area of cross section (feet), which is 0.00545 sq. ft. for a one-inch pipe); Ti for run 1 = 0.0398/0.00545 = 7.3 ft./sec. Substituting this value of V in the expression for velocity head, there results (7.3)2/64.4 = 53.3/64.4 = 0.828. H' = friction or lost head; for a circular pipe this is given by the expression f l / d X V2/2g. Here f , the friction factor, is 0.04 (for run 1) and is obtained from the formulaf = 0.02 0.02/d, where cl is diameter of pipe (in,). This f or friction factor of pipes is dependent on the material of which the pipe is made, on the inside surface of the pipe, and the material pumped; 1 is length of pipe (ft.), being 5.16 ft. in run 1; d is diameter of pipe (ft.), being 0.0833 in run 1; P / 2 g is velocity head, which was calculated to be 0.828.
+
Vol. 25, No. 3
per second will be 2725/100 = 27.2 foot-pounds per second. With one horsepower equivalent to 550 foot-pounds of work done per second, the work done in run 1 in terms of horsepower will be 27.2/550 = 0.0495 h. p. Dividing this by the efficiency of the pump (assumed t o be 50 per cent), vie obtain the actual or brake horsepower required to do this work. ThuP 0.0495/0.5 = 0.099 h. p., or0.099 X '746 = 73.8watts.
FIGURE 3. PLOTOF CURVES2
AKD
3
(Concentration constant = 0 81 per cent)
Watts per 100-foot lift for curve 8 (Figure 5 ) and column 14 (Table I) were computed as follows: pounds stock per minute X 100 feet head = foot-pounds per minute + 33,000 footpounds per minute per horsepower = horsepower + percentage efficiency of pump X 746 = watts.
RESULTSAND CONCLUSIONS Curve 1 (Figure 2 ) was plotted from concentrations against watts per pound per minute, per 100-foot lift. The latter quantity (ordinate) was obtained by calculation as a direct ratio between the power required for the actual head employed in the experiment and the 100-foot head, for the power required is directly proportional to the head. The quantity thus obtained was divided by the discharge per minute at that concentration to obtain the power per pound per minute per 100-foot lift. For run 1, 73.8 watts for 10.94-foot head = 675 watts per 100-foot head, or 249 pounds in 1.67 minutes. Thus 150 pounds per minute and 675 watts i 150 pounds = 4.5 watts per pound per 100 feet. This curve as shown in Figure 2 is a straight line, indicating that no matter what the concentration of stock between 0 and 1.57 per cent, the power
Substituting these values in the expression for the lost or friction head the result is: H'
=
(0.04 X 5.16)/(0.0833 X (7.3)2)/(64.4)
=
2.05 ft.
Substituting the values of static head, the velocity head, and the lost head in the expression for the total head, we obtain: h = 8.16
+ 0.828 + 2.05 = 11.038 ft.
T o this value we have t o add the friction head caused by the fittings, which in this case are two elbows (4). For a given discharge (7.3 feet per second) in run 1and one-inch pipe, the friction head for one elbow is 0.707. Therefore, for two elbows it will be 2 X 0.707 = 1.414 feet. Adding this head to t h a t obtained above, we have h = 11.04 1.414 = 12.454 as the total effective head. The pump was working under a pressure head which must be subtracted. Pressure head in run 1 is 1.51 feet. Therefore, the total actual effective head is 12.454 - 1-51 = 10.944 feet (the elevation to which water was lifted and work done). The theoretical horsepower t o do this work can be calculated by multiplying the total actual effective head by pounds of water or suspension lifted. This will give the foot-pounds of work done in the time required to pump the given weight. For run 1, it will be 249 X 10.944 = 2725 foot-pounds. This amount of work was done in 100 seconds; the work done
+
FIGURE 4. PLOTOF CURVES4
TO
7
(Concentration constant = 0.81 per cent)
required to lift one pound of suspension in one minute per 100 feet is the same. This curve for the concentrations employed should be a straight line because it assumed that Pitot tube readings (the friction value), if these were possible, for 1.57 per cent pulp suspension would be found to be the same as for water. I n more concentrated suspensions the friction caused by the interlaced pulp fibers must, naturally, increase very rapidly. A 3 per cent suspension with the power employed here could not be forced through a one-inch pipe line 91 feet in length with thirteen fittings. With larger pipe sizes, concentrations of as high as 6 per cent can be pumped commercially. The friction factor or loss with low concentration (0.0 to 1.57 per cent) of stock would likewise be low in large commercial pipe sizes of 6,8,10, and 12 inches.
INDUSTRIAL AND ENGINEERING CHEMISTRY
288
friction due to increased pipe length increases. This being the case, the velocity head would decrease still more, for it is proportional to the square of the velocity. Curve 9 (Figure 5 ) shows the relation of increase in pipe length to the total actual effective head. We see here that, although the pipe length is increasing, the total actual effective head is decreasing, whereas theoretically it should increase, for the friction head increases with increase in the Iength of pipe. The reason that the total actual effective head decreases with increase in length of pipe may be that velocity, hence the velocity head, is falling very rapidly, thus nullifying the effect of the increase in the head due to the pipe length. This may be shown if curves 8 and 9 are interpreted with reference to each other. Curve 10 (Figure 6) shows friction loss (in feet per 100 feet of pipe) to increase with gallons pumped per minute. The friction factor has been taken as that of water for concentrations up to 1.57 per cent for one-inch, clean, smooth, steel pipe. The behavior of a falling sphere through pulp suspensions of this concentration is about the same as that of water (IO). 16
+-
15 ‘C,
:g
Vol. 25, No. 3
and friction, commercial design for low concentration of pulp will be largely based on utilization of the mass of scientific information based on water. This appears logical and is in agreement with the known facts. For higher concentrations, factors d e r i v e d from the e x p e r i e n c e of designers of pulp mills and pumps, and of engineers operating pulp mills must be relied upon. Since these tests were made in 1923, some data on pumping pulps in largesize commercial iron pipes have been obtained, based on pulp pumped and power consumed by pumps. T h e s e l e a v e a gap for small pipes, and the data above stated conform to what one would expect for such small pipe sizes (1, 3, 6). FIGURE 6. PLOTOF CURVE10
I S i S ~
1 3 25 +-v
“2
r
I l T e IO$
qa
100
110
120
I30
140
150
I60
FIGURE 5. PLOTOF CURVES8
AND
110
110
9
ACKNOWLEDGMENT The writers acknowledge the suggestions and information given by many pulp and paper mill superintendents and engineers, and engineers having to do with producing pumping and pipe equipment for the cellulose industry.
(Concentration constant = 0.81 per oent)
LITERATURE CITED
Pitot tubes are not applicable for determining friction factors because the pulp fibers adhere to the entrance of the tubes or interfere with admission of the suspension. It is suggested that experiments be performed to study effect of (1) varying the construction of Pitot tubes to determine if, by use of large orifices, they can be adapted to pulp suspensions; (2) using a pump of determined brake-power efficiency and a variable-speed, direct-connected motor, to determine rate of discharge with variation of power input; (3) variation due to concentration of the commercial pulps; (4) variation due to kind of pulp; (5) variation due to kind and size of pipe (wrought iron, drawn steel, brass, copper, cast iron, spun cast iron, wood, copper, and commercially available alloys) ; and (6) length of pipe and fittings. Much of this, superficially, appears simple, but actually much .time and expense are involved. Until more scientific data become available on pulp flow
(1) Allis-Chalmers Co., Bull. 1649 (1930). (2) Annis, R. R., Paper Mill Wood Pulp News, 51, 49 (Feh. 25, 1928). (3) Cameron Steam Pump Works (subsidiary of Ingersoll-Rand Co.), Cameron Hydraulic Data (including International Paper Co. data), pp. 15-18 (1925). (4) Cameron Steam Pump Works, Hydraulic Data, Union Engineering Handbook, pp. 91-164, Union Steam Pump Co., Battle Creek, Mich., 1921. ( 5 ) Hiscox, G. D., “Hydraulic Engineering,” p. 82, N. W. Henley Co., New York, 1908. (6) Hydraulic SOC.,Standards, 6th ed., 1930. (7) Klosson, M. M., Am. Pulp and Paper Mill Superintendents’ Assoc. Year Book, pp. 173-6 (1932). (8) MacNeille, Paper Mill Wood Pulp News, 50, 20 (July 16, 1927). (9) Morris Machine Works, Bull. 148, 4, 5 (1932). (10) Tang, Tao-Yuan, Univ. of Maine, Thesis 668.8 T 15G (1924). R E C E I V E D November 3, 1932. Presented before the Division of Cellulose ChemiQtry at t h e S3rd Meeting of t h e American Chemical Society, New Orleans, La., March 28 to April 1, 1932.
Production of Parchment-Like Membranes from Cultures of Slime-Forming Microorganisms J. R. SANBORN, International Paper Company, Glens Falls, N. Y.
I“
investigation of the microorganisms involved in theAN formation of pulp and paper mill slimes, the author’ has emphasized the diversity of the slime flora and the heterogeneity of the viscous materials produced. Among the isolations certain yeastlike forms, belonging to the genera Oidium and Monilia, occurred prominently. These organisms develop with great rapidity in carbohydrate-rich media, producing doughy and somewhat rubbery growths. Either potato decoction or extract of groundwood, with the addition of glycerol, dextrin, or glucose, may he employed. 1 Sanborn,
J. R., J . Bad., 83, 70 (1932); t o be published (1933).
The production of satisfactory parchment-like membranes from these slime growths has been achieved by comminution of the material in water, deposition of the slime particles upon the sheet-forming substratum with the aid of an aspirator, and lubrication of the resulting membrane by means of a glycerol and mineral oil treatment. The slime particles coalesce to form a continuous, uniform, semi-transparent membrane. The final process was completed by drying in a steam hot-plate sheet drier. RECEIVED February 13, 1933:
