July, 1922
THE JOURNAL OP INDL'STSRIAI, A N D ENCIA'h'ItRING CfIEMI8TRY
GO7
stead of being allowed to pass to the boilers arid form a very dangerous and uneconomical scale. Another is that the water is kept clcan, which reduces foaming and prevents scoring of engine cylinders and the moving parts of turbines. Still another is that the efiiciency of a sorfacc condenser is increased from 20 t,o 25 per cent,, oil account of tlie absence
instead of just around the dry air suction pipe under ordinary conditions. The yearly saying effected by a deactivator of this type will fibowfrom 25 to 50 per cent on tlie cost of the installation, regardless of the otlrer advantages enumerated.
T
plant in this country has ncarly one Inmdred miles of wooden pipe. Its cost is also less than ihat, of iron or steel, considerably so in the larger sizes.
HE value of wood as a material of construction in the chemical industries is very commonly underestimated. This arises from the fact that little information is available in the literature in regard to the use of wood for such purposes, and it is often true that on account of lack of information the plant operator makes use of unsuitable wood, or puts it to improper uses. It is the purpose of this article to give a fairly comprehensive outline of the various woods and their uses for chemical plant work, ADVAN.I.AGES Chemical apparatus made of wood is usually less expensive in its first cost than when made of met,al. In many cases t.he difference in favor of wood is great. When used for water or other liquids whieli do not destroy the wood, the life of the wood is very long. Cypress tanks are known to have lasted for 130 yrs., while PCC. 1 wooden water pipes liave been in service underground for 100 yrs., such life heins much in excess of that ohdained from the ordinary steel of to-day. In many localities, the water contains material which quickly corrodes the hest of steels while wood is quite unaffected. Wood does not require frequent painting to prevent corrosion as is the case with steel, and i t can usually he repaired or remodeled by the local carpenter. Wood is a poor conductor of heat, and wooden apparatus exposed to frost requires much less heat to keep the contents from freezing than is the case with metals. Convcrsely t,he contents of tanks and piping can he kept cold more easily when wood is used. Wooden piping is not common in chemical plants, but i t has many advantages, among which are tlie absence of corrosion due to electrolysis by stray electric currents, and its grcatcr carrying capacity under given pressure drop. Its value may be indicat.ed by the fact that one large chemiaal
1
Received April 4, 1922. Published &s Contribution No. 17 from the Department of Chemical Encineerinx, M. I. T. 1 Assistant Professor of Chrmical Engineering.
of nonrondensahle vapors througliont thc entire condenser
I)ISADVANTAGES
Wood is not a suitable inaterial for usc in apparatus handling strong oxidizing agents, such as concentrated nitric or sulfuric acids. It is readily attacked by strongly alkaline solutions. It must he protected by a suitable protective coating from the action of certain ctremieals, such as concentrated hydrochloric acid. Wood is meclianically weaker t.han metals, and this lirnits the use to apparatus of comparatively moderate pressure, steel-banded wooden pipe having been used up to 130 Ibs. pressuro, and reinforced t,anke up to 50 Ibs. pressure. Wooden tanks and piping swell when brought into contact with liquids, and shrink if allowed to dry out afterwards. This permits the joints of t,hc apparatus to open up, and leaks develop. The apparatus must therefore be kept full of liquid and if this is not practicable, it should he filled with water to prevent drying out.
Kmns
OF
Woo0 AVAILABLE
The kinds of wood most commonly met with in this country arc listed belov in the approximate order of their popularity for chemical work in general.
1
a
FIG. 2
?'HE JOCIZSAL OF Ih'DUSTEI.4L A N D E~VGIXEEIZJiVG CHEMISTRY
608
Taem I
?-Yellor. poplar (PoDdur delioidrsl 8-White onk (@urrrui alba) 9-Tamarack (La& luricina) I O S p r u e e (Pi- ruhro) 11-Norway pine (Pinur rriinoau)
Long Leaf Ptne I 2 1
4
TEsTs O N EFFECT
1
OF
[email protected] X WOODS
2 4
:i
A series of tests were periortned by 8. .J. Hauser atid Clarence Behrmiin for the Kairser-Stnnder Tank Company on the itction of a numher of coinrnon solutions on six woods: cypress, long leaf pine, Douglas fir, redwood, hard maple, andwliiteoak. These tests included: I-The
contaniinriion
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o f the Iiouid hv the exerac.. .... tion Of eoiorine matter from t h e wuod. ~
PZO,
3
Vol. 14, S o . 7
?-The ahsri>tion of liquid by the wood. 3---The swell in^ or shrinking ut the wood. 4-The effect upon the strength end hardness 01 the wocrl
~~
3
2 2
4 3 2 1 1 1
2
1
pansion wxs lost upon subsequent drying. Some woods after treatment with nit,rir acid and the alkalies showed shrinkage after drying. Redwood showed the greatest swelling and oak t,lie least.
Redwood
2
3 2 4
a
2a
.* 3 2 4
a 2 2
a 2 2 1
corm--The color imparted to the liquid, while not iniportant in many chemical operations, is frequently the determining factor in the use of wood for drinking water, for laundry purposes, arid in the preparation of many food products. EFFECT O N PHYYIOak and redwood contain large amounts of coloring matter Pro. 5 which is extracted frcely hy water both hot and cold, the redwood being B little the better with respect to the latter. Maple is better than oak or redwood, but is considerably solutions upon tile softness, brittleness, and other physical worse than fir, pine, and cypress, the last of which has little properties of the woods was noted. Acetic acid in any concentration has no effect on any of effect nn the wat,er. Where wood in to bc used for handling drinking water the woods. or for food prodT m i s I1 ucts wherc a taste Douglnn Loill: Leaf iisra Whifc Cypress Fir Pine Redwood Mapi? Oilk of the wood mist bc Hot Cold HotCold Hot ColdI Hot Cold Iiot Cold 1f"t Cold avoided, fir and pine 3 2 4 3 3 3 4 3 4 4 4 % 4 3 3 2 4 2 4 3 4 4 4 3 should not be used. 4 2 4 2 1 3 3 4 3 4 4 4 3 Z Z 3 5 a 2 3 3 4 4 4 4 Cypress and maple 3 3 2 2 2 2 3 3 4 4 :i a are hcst in this re4 4 4 4 3 4 4 4 4 4 4 4 4 2 4 3 4 2 4 4 4 4 :i 3 spect. 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 2 2 4 4 4 4 4 4 The relative cffect 2 2 2 2 2 2 3 3 4 4 2 2 in the cold of various 3 a 3 3 2 2 4 1 4 4 a i 3 1 chemicals on the six 4 2 3 1 4 3 4 a 3 2 1 1 2 2 1 1 3 8 8 3 I i kinds of woods with 4 3 3 2 1 1 3 3 3 2 1 1 3 2 8 2 I 1 4 3 2 2 I 1 reference to color ex3 2 3 s 2 1 3 2 3 1 1 s tracted is given in Table I. The effect Dilute hydrochloric acid ( 5 per cent) makes redwood is indicated by the brittle, while 25 per cent acid has a similar effect on maple 'numbers 1 to 4, 1 and oak; cypress, fir, and pine *re unaffected. Conccnmeaning little or no trated acid destroys all woods. color and 4 strong Dilute sulfuric acid (5 per cent) has little effect on any of color. the xoods, except redwood, which is made brittle. Cypress The reldiue effect and pine are not seriously attacked by cold 25 per cent acid, of the above soh- but hot acid of this strength and concentrated acid destroy tions when boiling all woods. hot is 'as a rule unNitric acid has little action in the cold on cypress, fir, nhanged from when and pine in the 5 per oent concentration. The hot solution in the cold, though attacks all woods. the colors are of course intensified in all caseS. Maple, oak, and redwood arc readily attacked by 1 per ABSORPTION-The relative absorption of the same chemi- cent sodium hydroxide even in the cold, cypress and pine cals was studied. No relation hetween the conecntration being unaffected up to 10 per cent boiling hot. Pine is not and the amount absorbed WBS apparent.; so Table I1 gives affected by cold 25 per cent sodium hydroxide solution. Sodium sulfide up to 20 per cent concentration is destructhe results for the nveraEe of several concent.ratinns of each solution. Low absorption is represented hy 1; large by 4. tive in the cold only to oak and redwood.
July, 1922
T H E JOURNAL OF INDUS'TEIAI, A N D ZVGI!VEERIiVG CHE.MISI'RY
609
Solutions which absorb water readily, such as certain hot Hot sodium carbonate solution shrinks oak and softens redwood, arid hot. sodium chloride solution inakes the latder concentrated solutions of hydroscopic salts, will, when brought brittle. The other woods are not affected. into contact vrith wood, partly dehydrate it., causing it to These experiments indicate that, except for nitric acid and shrink and to leak. Other maderials sncb as hot tar have caustic sodti, at, least one of the six woods tested is suitable somewliat the same effect. for each of the chemHYDROGEN PEROXIOE; icals used, when in Maple has been Found to withst,and the action of 10 per inoderatc concentrations. Cypress, fir, cent solutions of hydrogen peroxide indefinitely. and pine are the woods least affected; rnaple and oak are for general use, of restricted value. There is conderahle difference of opinion regarding redwood.
IXFORMATION COM- the tendency is to
Fro. 8
Ptmn ny FOREST cause disintegmtion of the wood. If relatively nonporous PRODUCTS LABwood be selected, wooden crystallizing tanks are very satisOR.~TOI~ factory and are long lived. A few years ago TANKS the Forest Products Round wooden ianks are const,ructed either straight or 1,at)oratory compiled information from tapered. The construction of the bottom, the sectioiis of users of wood in which are held together by dowel pins,. and of the stave, is chemical plants.' Ex- shown in Fig. 1. The tanks are slripped ready to assemble periences were very according to directions furnished by the makers. The tanks l"
