INDUSTRIAL A N D ENGINEERING CHEMISTRY
1280
Vol. 22, No. 12
Production of Insulating Board from Cornstalks' C. E. Hartford Mairewooo PPODUCTS C o a ~ o n ~ r i oDueunua, x. IOWA
UCIf has been written in recent years concerning the utilization of agricultural waste materials. M e a t and corn have attracted the greatest attention because of the availability of their by-products in large quantities fairly well concentrated in certain regions. References to the utilization of wheat straw have recently been given by Gibson (8)in connection with a description of a new plant manufacturing insulating board from straw. A brief list of recent articles dealing with the utilization of corn wastes is appended to the present article, which is intended primarily &s a description of a plant producing insulating board from cornstalks. Insulating board is now being made by different concerns from such materials as bagasse (5, 6), waste wood ( d ) , and extracted licorice root, in addition to wheat straw and cornstalks. A rapidly expanding market for insulating board in recent years has encouraged development of the industry as a whole. Because of the natural geographical distribution of the various raw materials utilized. it is probable that permanent markets will be found for board produced from these materials, particularly since they have very similar mechanical, thermal, and acoustic properties. The adjarence of the Corn Belt to the industrial market for insulating board in Chicago and to the cheap fuel of the central coal fields assures the future of the product manufa(tured from cornstalks.
MI
Commercial Development of Cornstalk Insulating Board The Maizewood Products Corporation was originally incorporated in 1926 to develop and produce an insulating board from cornstalks, followingthe pioneer efforts of 0. R. Sweeney at Iowa State College (1, 7, 8). A plant was built at Dubuque, Iowa, in 1927, but remained in a development stage without attaining production until the fall of 1929, after the project had been taken over by another group and the plant oDerations h a d been reorganized under the personal direction of Professor Sweeney. I n January, 1930, N a t i o n a l Cornst,alk Processes, Inc., was organized as a holding company, with the backing of astrong g r o u p which included those mho h a d previously t a k e n o v e r the Maizewood project. The plant, shown in Figure 1, has been in production since late in 1929, although improvements are still being made in I
Rcecived Sep-
tember 16. 1930.
the manufacturing processes. On its new basis the company operates under contract with Professor Sweeney and with Iowa State College. National Cornstalk Processes anticipates the further development of industrial uses for corn wastes. Collection of Raw Material A t present the bulk of the corntallis used in the Maizewood plant is bought from baling crews. Individual f m e m break, cut, and rake tho stalks on their own land, the owner of a baler buys them, bales them, and ships them to the plant where a price of $10 per ton f. 0.b. Dubuque is paid by the company. Of this amount, an average of $3 per ton goes to the farmer, $2 to $3 are necessary to cover transportation, and the rest represents the return to the baler for his services. Owing to the location of the plant, most of the material is received by rail. The cornstalk bales are stored in large piles adjacent to the plant. As needed, they are transported from storage by means of a wagon which delivers them to the end of a conveyor at one sidp of the plant. Various more refined schemes for handling the bales have proved impractical. Narrowgage track must be relaid too frequently to be economical, as the edge of the storage pile moves inward, while a small tractor used for transporting mate~ialfrom storage to the plant consistently dug itself into the sand. The factory policy is to supply raw material for current operation as far as practical by unloading directly from cars on a siding to the shredder conveyor.
Preparation of Cornstalk Pulp The bales delivered to the conveyor are broken by hand, and the cornstalks pass to a Williams swing-hammer mill. "he shredded material leaving the mill falls onto a second convevor. which d e iiversbver a ~ i n m magnetic separator to a blower, which elevates the m a t e r i a l to the top of the plant and discharges it t o a n y one of four storage bins. Each bin serves a globe mtary digester. The shredded material is charged to a digester, w a t e r ie added, and the charge is h e a t e d up by blowing in skam. The durstion of the cook is at present limited to 2 hours from the time a pres sure of 40 pounds i s reached, t h e
INDUSTRIAL A N D ENGINEERING CHEMISTRY
December, 1930
final pressure being IO0 pounds, corresponding to a temperature of 338' F. (170* C.). No chemicals are added to the charge. At the end of a cook with one digester the steam is blown off and paw;ed by means of a header to one of the other dipaters, which ifi heating up at the time. The cooked material is dumped to a concrete pit, from which it is tramferred by means of a Shartles stuff pump to the top floor of
Flgure 2-Formlng
Machine
the plant, where it is waslied in two washers. These are tmmmels covered with 40-meah brass Rcreen and sprayed with water from pipes plared above them. The material pa= from t.he fust washer through an rnrilage cutter, which further redures it before it enter8 t.he Rerond washer. The liquor from the first washer is returned to the pit beneath the digenter to dilute the pulp at that point to the proper consistency for pumping. The liquor from the second washer is run to waste. Plans are now being worked out which will make it pofisihle to rrturn this liquor to the system as part of the cooker charge, thus saving all of the fiber now being lost t.hroiigh washing. As the material leaves the second washer, rosin size is added and is thoroughly mixed in a atock chest. The mixed mat.erial is pumped to the refiners. pa-sing first through a Clafiin and then through a Jordan. Alum is added to the material leaving the Jordan, which then passes t o a sreond stock chest. The rosin and alum are added in the propnrtionn of 2 and 5 per cent, respectively, of the weight of the bone-dry fiber From the spcond stock chest t.he pulp is pumped by a Fairbanks-Morse trash pump to the forming machine.
1281
ous chainfi and riding by means of rollers on bed plates. one fixed and the other carried on heavy springs. By adjustment of the springs any desired pressure may be exertrd on the sheet of pulp carried through hetween the caterpillar treads on the endless 8creen. A second screen passes through the prrm on the upper side of the sheet of pulp, both screenn stripping off over rollers as the pressed sheet emerges. The forming of the board is manually controlled by an o p m t o r on the basis of the thickness of the sheet leaving the pres. which is indicated continuously by a gage. He adjusts a Goodrich ruhher-lined valve on the supply line to the forming machine to maintain the desired thicknew;. In addition to the operating gage, an EsterlineAngus imtrument. continuously records the thickness of the sheet produced in order to check the control maintained. Figure 2 shows the forming machine. The formed hoard leaving the Dress at a meed of 7 feet per minute is cut by an automatic cgtter into 16. I&, or 20-foot lensrths, depending on whether B, 9-, OF IO-foot boards are desired as the final product. An automatic tipple charges the wet sheeta successively to the various levels of an Bdeck Coe continnous drier. Thie has a drying length of 168 feet, the board traveling through it. at the rate of 1foot per minute. The drier is heat,ed by steam at 165 pounds pressure, and is maintained at 310" F. (155' C.) at the wet end and 320' F. (160' C.) at the dry end. The temperatures at the two ends are rontinuonsly recorded by Foxboro instruments. FiKnre 3 shows boards emerging from the drier. The forming machine and presa and the tipple and drier mechanism are driven by one motor through a Reeves variahle-speed transmission in order to allow chanecq in the rate of operation without danger of putting the various units out of step with each other.
Formin& Pressing, and Drying the Board
'
The forming machine us& in the Maimwood plant waa originally developed in the experimental station for the study of the utilization of agricultural by-prndurta maintained jointly by the Bureau of Standard- and the Iowa State College Experiment Station at Ames. Iowa. A t Dubuque this machine is ret up internally with a Kutztown press iiwd for dewatering the hoard after its formnt.inn. Pulp is pumped UD x-ertically and ie dischareed over a sloping apron onto an endless moving Rereen of 14-mesh phnsphor-hronsr wire. The srrem passe8 first over idler rollers. where some water drains off. t,hen wrr a suetion box maintitined under n vaCiium of 3 inches of wnter. A vibrating levrler smooths the t o p surfare of the mat of wet pulp, which then is carried into the prrw;. This nonsistn essentially of two caterpillar treads formed by steel plates 4 inches wide carried on three continu-
Figure 3-Board
Passing from Drier to Trimmlnpl Saws
The drier delivers hoards having a moist.nre content of 4 per cent on a conveyor to the trimming s a m . AP they p w to the trim saws t.he boards are given n licht sprav with wnter to brinp t,heir moistim content up to 10 ppr cent. This puts the boards in equilihrinm wit.h the mnisttire wnt.ent of the air and innires a minimum of swelling or shrinking. Rnch trimmed sheet is then piakrd up by a rark t.rnvelirie at right anples to the ronveyor, whirh carrim t.he sheet through B serond pet of saws w h k h trim the ends and cui it in two pieces. These finished hoards aw inspried for defect,*and arr ehrcked for thicknese at both d r s nf earh rnd EP t.hey are piled up on skids. Lift t.rurkR handle the loaded skid- to stomp? Additional equipment includes a sanding machine to give
1282
INDUSTRIAL AND ENGINEERING CHEMISTRY
boards which are to be used for interior decoration and similar work a smoothly sanded surface; a machine for cutting a ship lap edge on boards which are to be used as a plaster base; and a stapling machine for fastening two or more layers of board together to make roofing or refrigerator insulation. Prospective Developments The plant as originally designed required an excessive amount of power, particularly in the various s t e p for the reduction of the cornstalks to pulp. A swing-hammer mill requiring 160 horsepower was originally installed between the first and second washers; the ensilage cutter which replaced i t has greater capacity and does the work required at that point very satisfactorily on 3 to 7 horsepower. Experiments
materials. Heat-conductance tesix made by the flat-plate method at Armour Institute of Technology on regular millrun board gave the results ahown in Table I. Table [--Heat
Inch
Lbr./ f'. ISb 16.3 14.9
C Y
1 2 3
0.485 0.487 0.500
Conducclvlty Coefficient of Maizewood
I
'F.
1% 93
xovrr
G7amr
0
284.2 324.6
1 2 4
8
24 48
72 96
Chlulgo 1933 World's Fak
are now under way to reduce further thepowerrequuementa for the refining equipment. The possibility of substituting a second Claflin for the Jordan now used is being investigated, and a Smalley ensilage cutter is being tried in place of the swing-hammer mill which shreds the dry cornstalks. The Clafiin uses 75 horsepower compared with 200 for the Jordan and the cutter requires 25 horsepower compared with 65 for the swing-hammer mill. Other mechanical changes planned include the elimination of the bins over the digesters, with direct pneumatic feed from the initial Williams mill to the digesters, and the possible replacement of the steel saws used in trimming the board by saws tipped with special abrasion-resistant materials. Experiments to date indicate, however, that although steel saws must be removed for sharpening every 24 hours, the added life obtained by using such materials BS Carboloy or Stellite for tipping the teeth does not offset the increased cost. More important than the mechanical improvements of the present process are the plans for the recovery of by-products. The cook liquor contains pentosan materials and furfural. By evaporation in a continuous cycle i t is hoped to recover the pentosans in the form of a thick liquor suitable as an adhesive for such purposes as coal briquetting, while the condensate, carrying furfural, will be returned to the digesters until the furfural content of the system is high enough to allow re+ covery. In addition, fibers recovered by filtration of waste water and dust from the trimming saws may very possibly be utilized in the production of maizolith (4), a subetanee which has many indicated uses in place of vulcanized fiber. Properties of Cornstalk Board Insulatine board made from cornstalks has mechanical and thermal properties very similar to board made from other
'P.
48
48 47
'F. 45 46 4s
O F .
70.5 71.0
70.0
1
1
,
B . 1. *.-in. P. ~. 0.325
Fn /L.-kr..* ~ . I
0.345
0.320
A moisture-absorption teat on a piece of board 12 inches square immersed in water a t room temperature gave the results shown in Table 11. Table 11-Moiature
Flgure 4-Malzewood Inaulating Slabs. 36 X 24 x 1 Inch B r l n g ApDiled to Roof of A d m i n l e n a t i o n B u i i d l n g of th:
Vol. 22, No. 12
333.7 364.0 404.6
497.8 618.0
703.3 766 5
Absororlon of Maizewood
crams 0.0 40.4 49.5 79.8
120.3 213.8 334.4
419.1
481.3
PET CC"1 0.0 14.2
17.4
28.2
42.3 75.0 118.0 147.0 1B9.0
I n a tensile test on a 4-inch width, a load of 205 pounds per square inch was necessary to cause failure, while on a t r a m verse test with a 4-inch width on a 3-inch span with the load applied a t the center, 110 pounds were necessary to cause failure. Plsstcr bond tests conducted on samples of several different insulating boards a t Iowa State College showed the highest values for Maizewood, with an average strength of 10.61 pounds per square inch. During the regular production of board, plan&control testa on strength, moisture absorption, and weight are run on every twenty-fifth board in order to insure uniform quality of product. One of the important usea of Maizewood is illustrated in Figure 4, which shows 36 X 24 X 1 inch insulating slabs being laid on the roof of the Administration Building, fust building of the Chicago 1933 World's Fair. Area Distribution of Cornstalk Supply
A problem inherent in the industrial utilization of any agricultural waste is the collection of the material at the plant which is to use it. I n most casea the cost of this collection will be a controlling economic factor. It is obvious that the cost of collection will tend to be lowest where the area concentration of the agricultural crop in question is highest, provided sufficiently good all-year roads are available for shortdistance trucking. The most recent complete data for the area of land devoted to raising corn available in published form are from the Census of Agriculture for 1925. which tabulates by counties the acreage ai land used for various crops. I n the case of corn the total acreage is further subdivided into acreage devoted to corn grown for grain as distinguished from that grown for silage or fodder or hogged off. From the standpoint of the industrial utilization of cornstalks this ie an important d i e tinction. since the stalks are not available from corn in these latter classifications. Any estimate of the amount of material available should be based only on corn grown for grain, since this will give a safe minimum value.
December, 1930
INDUSTRIAL A N D ENGINEERING CHEMISTRY
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The key in the lower left-hand cornef indicates the percentage of the land area devoted to the growing of corn for grain. Corn grown for silage or fodder. or hogged off, has not been included. and area concentrations below 15 per cent have not been indicated. This map is based on the data of the 1925 Census of Agriculture, with counties as units.
The general region of the Corn Belt is well known, but it is difficult to define the areas of greatest corn concentration, even by careful inspection of the data of the Census of Agriculture, unless a concentration map is prepared. Figure 5 is such a map, based directly on the Census data. Counties have been grouped in five classifications, depending on whether they contained grain-corn acreage in excess of 15, 20, 25, 30, or 35 per cent of the county land area. Concentrations below 15 per cent have not been indicated, and no differentiation has been made above 35 per cent, although four counties in Illinois and one each in Iowa and Nebraska show concentrations greater than 40 per cent. Certain regions in Iowa and Illinois show much higher values for total corn acreage, running in some cases up to 60 per cent, but, as mentioned before, the basis of acreage of corn grown for grain yields a much safer estimate of the amount of cornstalks available for industrial use than does the basis of total corn acreage. The two areas of highest concentration of industrially available cornstalks are at once apparent on inspection of Figure 5. The first of these is in east-central Illinois. where there is a compact group of ten counties in which more than 35 per cent of the land is devoted to growing corn for grain. This area, moreover, is bordered by three groups of counties totaling a somewhat greater area in which the concentration is between 30 and 34 per cent. The second area of high concentration is centered on the valley of the Missouri River and includes portions of the states of Iowa, Nebraska, South Dakota, Kansas, and Missouri, over half of the area lying in Iowa. The counties showing more than 35 per cent of the land planted to corn for grain are more scattered than in the first case, but the area showing between 30 and 34 per cent is much larger. It can safely be assumed that the general distribution of corn land has not changed greatly since 1925. More recent data are available from several of the states, but the 1925 Census figures were preferred for purposes of comparison.
A map of the distribution of corn acreage in Iowa by townships, prepared by the Agricultural Economics Department of Iowa State College, gives an especially detailed picture of the total corn acreage in tha.t state. The yield of cornstalks from a corn crop depends upon the time of harvesting, but 1.5 tons of bone-dry stalks per acre is a safe estimate according to Webber (9), who has published figures calculated on this basis showing that, where one-third of the land is planted to corn. there will be available within a radius of 10 miles a supply of 335 tons of stalks per day for a plant operating 300 days per year. As is evident from Figure 5, there are extensive areas where the concentration of grain corn will be high enough to require only very short hauls to a plant. Location of plants in these areas then becomes a matter of balancing the usual factors of fuel, power, water, labor. and transportation to market, and the special factor of all-year good roads. It is obvious from Figure 5 that the present plant of the Maizewood Corporation at Dubuque was not located advantageously with respect to the cornstalk supply. The area concentration of corn in its immediate vicinity is less than 15 per cent, and it is approximately midway between the area of highest concentration. It is likely that future plants will be located in one or the other region of high concentration, with the specific points determined by the economic factors other than raw material supply. Literature Cited (1) Arnold, Eng. Extension Dept., Iowa State Coll., Bull. 99 (1928). 22, 493 (1930). (2) Boehm, IND.EXG.CHBM.. (3) Gibson, I b i d . , 22, 223 (1930). (4) Hartford, Bur. Standards, Misc. Publ. 108 (1930). ( 5 ) Lathrop. ISD. ENG.CHEM.,22, 449 (1930). (6) Seidel, Ibid.. 22, 765 (1930). (7) Sweeney, Iowa State Coll. Eng. Expt. Sta., Bull. 73 (1924). (S) Sweeney, Zbid., Bulletin (in preparation). (9) Webber. IND. ENG.CRBM.,21, 270 (1929).
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
Additional Recent Literature on Corn-Waste Utilization Atkinson, U. S. Patents 1,472,318 (October 30, 1923); 1,538,505(May 19, 1925); 1,572,510(February 9,1926). Bache-Wiig, U. S. Patent 1,455,471(May 15,1923). Bcrntson. U. S.Patent 1,516,701(November 25, 1924). Burkey. Iowa State Coll. J . Sci., 3, 57 (1928). Burtt-Davy, S. African J . Ind., 6, 357 (1922). Clemen, Iowa Agr. Expt. Sta., Circ. 339 (1929). Darling, Raw Material, 6, 97 (1922). Ditman, U. S. Patents 1,456,540(May 29, 1923); 1,522,618(January 13, 1925). Dorner. British Patent 286,211 (February 28, 1927). Emley, Paper Trade J., 88,No. 25,61 (1929). Fred and Peterson, J. IND. END.CRBM.,13, 211 (1921). Hinde, U. S. Patent 1,623,184(April 5, 1926); British Patent 304,171 (July 14, 1927). Hulbert. Paper Trade J.. 87, No. 13, 51 (1928); P a p n Mill, 61, No. 39, 12, 38 (1928). Jackson, Pulp Paper Mag. Can., 26, 713 (1928); Paper Mill, 60, N o . 36, 2, 20 (1927).
Vol. 22, N o . 12
Kirkpatrick. Chem. Met. Eng., 38, 401 (1928). La Forge, J. IND.ENG. CHSM., 10, 925 (1918); 13, 1024 (1921); 16, 499
(1923);16, 130 (1924). La Forge and Mains, Ibid., 16,823,1057(1923). Ling and Nanji, J . Chcm. Soc., 123,620 (1923). Mains and La Forge, IND.ENG.CHEM.,16,356 (1924). Marsh, Jbid., 13, 296 (1921). Maxwell, Proc. Iowa Acad. Sci., 33, 174 (1926). Naudain, A m . Food J . BO, 508 (1925). Naylor, U. S. Patent 1,573,734(February 16, 1926). Peterson, Fred, and Verhulst, J. IND.END.CHBM.,18,757 (1921). Peterson and Hixon, Ibid., Anal. Ed., 1, 65 (1929). Phillips, J . A m . Chcm. Soc., 49,2037 (1927);60,1986 (1928). Rommel, IND.ENC. CHBM., 20, 587, 716 (1928); "Farm Products in Industry,'' Rae D. Henkle Co.. Inc.. New York. 1929. Skolnik. U. S.Patent 1.599.253 (September 7, 1926). Spirindelli, Notis. chim. ind.. 1, 412 (1926). St. Klein, Wochbl. Papierfnbr., 69, 1175 (1928). Sweeney, U.S. Patent 1,639,152(August 16.1927). Taylor. Chcm. Age (N.Y.),81, 549 (1923). Webber, Proc. Iowa Acad. Sci., S i , 290 (1924). Williamson, Burr, and Davison, IND. END.CHSM., 16,734 (1924).
Catalytic Reactions of Sulfur Compounds Present in Petroleum' I-High-Sulfur Naphthas in Contact with Nickel and Iron Catalysts J. C. Elgin, G. H. Wilder, and H. S. Taylor FRICK CHEMICAL LABORATORY OB PRINCETON UNIVERSITY, PRINCETON, N. J.
This paper presents results obtained in a study of the action of nickel and iron contact catalysts on the sulfur content of high-sulfur naphthas, carried out as the preliminary investigation in a systematic study of the catalytic reactions of the sulfur compounds in petroleum. Experiments have been made in the vapor phase a t 300' and 400' C., a t atmospheric pressure, and with and without added hydrogen. Adsorption of sulfur from the naphthas in the liquid phase has also been determined. It is shown that a reduction in the sulfur content of naphthas is effected by passage, in the vapor phase, over a nickel or an iron catalyst, nickel being the more efficient. Sulfur may be completely removed in contact with the initially sulfur-free nickel catalyst, but the catalyst undergoes a decrease in activity as sulfurization proceeds. It reaches a state in which it possesses a constant, definite, though reduced activity. Sulfur removed is converted to hydrogen sulfide. Hydrogen added to the vapor stream
tends to increase the extent to which sulfur is removed, and effects the removal of sulfur not affected by t h e catalyst in its absence. The percentage of sulfur removed under a fixed set of conditions varies with the naphtha sample studied. This is attributed to variations in the nature of the sulfur compounds present in the naphthas. All of the sulfur present in the naphthas studied is not removed under t h e present experimental conditions. Nickel and iron catalysts do not adsorb from the liquid phase all sulfur present in the naphthas. The preliminary results suggest that, with addition of hydrogen, alternate sulfide formation with the catalyst surface and its reduction by hydrogen may play an important role in the removal of sulfur and, in consequence, that variation in the ratio of hydrogen pressure to t h e sulfur compound pressure may increase the effectiveness of the catalyst action.
. . . . . . , . , . . .. HE present communication is concerned with results obtained in the first phase of an investigation which lias for its object a complete study of the reartions of sulfur compounds in petroleum in the presence of contact catalysts, alone, or with the addition of hydrogen The fact that metallic hydrogenation catalysts exhibit a specific affinity for sulfur suggested that the actian of a metallic nickel catalyst be studied first. The action of an iron catalyst, very active in the synthesis of ammonia, has also been studied. Since there is available very little fundamental information
T
1 Received October 18. 1930. Thrse papers contain rrsults obtained in an investination on 'Specific Absorbents for Sulfur Compounds in Pe-
troleum" listed a* Project No. 40 of American Pet-oleum Institute Research Financial assistance in this work has been received from a research f u n d donated by John D Rockefeller This fund is being administrred by the inst:tute with the coliperation of the Central Petroleum Committee of the National Rrsearch Council. Hugh S. Taylor, of Princeton University, is director of Project hTo. 40.
pertaining to this field, the preliminary investigations have been carried out with high-sulfur naphthas. In Part I1 the study will be continued with mixtures of pure-sulfur compounds in definite hydrocarbon materials. Cata!ysts
NrcmL-The metallic nickel catalysts employed were obtained from two sources. One material was prepared in several batches in this laboratory by the following method (4). Nickel was precipitated on a kieselguhr support as the hydroxide by expelling excess ammonia from a suspension of kieselguhr in ammoniacal nickel nitrate solution in a current of air at 70' C. The precipitate was filtered, dried in air at 100" C., and reduced in hydrogen. The temperature during reduction was raised slowly to 500" C. over a period of 5 hours and maintained at this temperature until reduction
