I.VDiY:STRIAL AND ENGINEERING CHEMISTRY
February, 1927
should be sufficiently water-resistant to meet requirements embodied in the Kavy specifications for casein glue. In parallel-grain gluing with hard maple lumber the joints should be strong enough to tear the wood when tested to destruction. The proportion of water used in this formula can be altered sufficiently to give any viscosity required for ordinary woodworking purposes. In testing plywood panels made with animal glue containing paraformaldehyde for mater resistance it is imperative
2 U
1
Glue formula animal due
loo
219
perature the tanning of the glue is a slow reaction. Since the values for water resistance given in Tables I, 111, and IV were obtained with panels conditioned for 7 days before testing, they underestimated somewhat the degree of water resistance which the glues are capable of developing. No attempt is made in this paper to draw a close comparison between the water resistance of the glues discussed and that of commercial types on the market. Both are undergoing constant improvement and their water resistance therefore is not a fixed property. For most woodworking purposes both types are sufficiently water-resistant, and choice between them will be governed by differences in properties other than water resistance, and by the relative costs. Conclusions
I
1
I
I
4
Seasoning Parlod
-
I 8
I 10
I
I
I2
14
I 16
Ik
days
Figure 4-Shou ing that the Paraformaldehyde-Containing Glues Develop Their Water Resistance Slowly
that a seasoning period of at least 7 days, or preferably longer, be allowed after removing the panels from the press and before submitting specimens to the soaking test. -4s shown in Figure 4, the full water resistance of the glued joints is not developed for many days, presumably because at room tem-
1-Through the use of (a) formaldehyde polymers, ( b ) hydrolyzable formaldehyde compounds, (c) formaldehyde adsorption complexes, it is possible to introduce enough formaldehyde into animal glue sols to render glued joints water-resistant and a t the same time to retard the reaction sufficiently to give a working life practicable for woodworking. 2-The working life of such glues can be further extended by the addition of acids in small amounts, but often at the sacrifice of some of the water resistance. Oxalic acid extends the working life without loss in water resistance. 3-A glue of practicable working life and sufficient water resistance to meet requirements embodied in Navy specifications for casein glue is made by adding to a batch of animal glue, as ordinarily prepared, 10 parts by weight of paraformaldehyde and 5.5 parts of oxalic acid per 100 parts of dry glue.
Some Interesting Sugarhouse Incrustations’ By John W. Schlegel and J. P. Manley XEW YORK REFINERY. NATIONAL SUGAR REFININGCO., LONGISLAXD CITY. N. Y.
T
HE char filtration plant of a modern refinery is a fertile
field for the investigation of sugarhouse scales, deposits, and incrustations. Frequently further investigation of incrustations which upon casual examination seem of least importance leads to results of prime importance t o the refining process. The incrustations discussed in this paper are representative of these commonly found. So far as the writers are aware, no analyses of scales of this character have yet been published. Char Filter Deposit
Several years ago it was noticed that in the filtration of high remelt sirups over bone black a heavy, sticky sludge ultimately formed upon the upper surfaces of the filters, retarding the flow of liquor through the filters and later affecting the efficiency of the sweetening-off process. Investigation showed that, although the high remelt sirups from the centrifugal machines were brilliant. a flocculent precipitate appeared upon later dilution and heating preparatory to char filtration. This precipitate was later found deposited upon the upper surfaces of the char filters. A portion of this smear from the char filter tops was washed free from sugar, dried, and analyzed, with the following results : Presented before the Division of Sugar Chemistry a t t h e 72nd Meeting of the American Chemical Society, Philadelphi?. Pa., September 5 to 1 1 , 1926
.
Per cent
Organic and volatile.. ... 37.60 Si02 .................... 44.05
.....................
SOa FerOa
+ AlzO3. . . . . . . . . . .
5.48
3.99
Per cent PZOJ. . . . . . . . . . . . . . . . . . . 1.41 CaO . . . . . . . . . . . . . . . . . . . 4.66 MgO . . . . . . . . . . . . . . . . . . 2.82
--
TOTAL.. . . . . . . . . . . . . . . . 100.00
This scale evidently consists mainly of silica, combined with calcium sulfate, iron and alumina, and probably basic magnesium silicate. The very interesting feature of this deposit is its high percentage of silica, due probably to the use of diatomaceous earth in the clarification of the washed sugar liquors. During such clarification, especially if an excess of lime is used, small quantities of silica are dissolved from the earth, the degree of solubility depending largely upon the excess of lime used. Although normally, only mere traces of silica are dissolved, sometimes so much is dissolved that, upon the subsequent concentration of the impurities in the lower grade sirups, their limit of solubility is reached and the silica separates out. This is what seems to have happened in this case, for with more careful control over the defecation the deposition ceased. Liquor Pipe Incrustations
Scales found in the outlet pipes from low-grade char filters, used for the filtration of raw sugar washings through bone black, were analyzed, one lot about six years later than the other. These scales ultimately practically close up the pipes. In fact. it is the resultant slow flow of t>heliquor
220
IXDUSTRIAL ,4.2'0 ENGINEERI-VG CHEMISTRY
from these pipes which indicates that the scale has been deposited and is ready for removal. The composition of the scale was as follows, all analyses being made upon the Tvashed and dried scales: Scale S o . 1 l'olatile and organic . . . . . . . . . . . . . . . . . . . SiOn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CaO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FenOa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Per cent
26.30 49.66 3.60 3.20 A1203 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.95 SOa.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.810 MgO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.35 P206, . . . . . . . . . ............... 0.53 CuO.. ................................ Small amount Undetermined, . . . . . . . . . . . . . . . . . . . . . . . . 4.61
__
TOTBL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100.00
Scale No. 2
Per cent 30,27 48.02 7.00 1.02 2.42 2.19 0.42 3.05 Small amount 5.61
--
100.00
Here again the high percentages of silica are the significant feature, the quantities of bases present being too small to account for the total amount of this constituent. Kiln Flue Deposits The volatile matter driven off during the burning of bone black and expelled through flues and chimneys is largely organic and tarry, and contains considerable quantities of nitrogenous material, especially when new bone black is used. I n their passage through the chimneys, the more readily condensable of these bodies are deposited upon the cool sides of the chimney, especially near the top, producing scales of varying thickness and composition. On repairing a chimney which had been in use for twenty years, the interior was found heavily incrusted with scale, the color of which was a peculiar mixture of white, yellow, and brown, partly amorphous, partly crystalline. The crystalline portion consisted mainly of well-formed clusters of radiating needles, distinctly visible upon even macroscopic examination. This scale was contaminated with ash dust from the coal fires of the kilns. The total air-dried scale consisted of 68.06 per cent water-soluble and 31.94 per cent water-insoluble matter. The water-soluble fraction contained 80.26 per cent organic and volatile matter and 19.74 per cent mineral matter. The water-insoluble fraction contained 17.25 per cent organic and volatile matter and 82.75 per cent mineral matter. That is, the total scale contained 60.13 per cent volatile and organic matter and 39.87 per cent mineral matter. A complete analysis of the water-soluble portion gave the following results: . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . ... CI . . . . . . . . . . . . . . . . . . . . . . (NHdzO'.
S08..
2;;;; 1 . . . . . . . . . . . . . . . .
CaO . . . . . . . . . . . . . . . . . . ,. MgO . . . . . . . . . . . . . . . . .. P201,
a
. . . . . . . . . . . . . . . . . .. 17.29 per cent N.
Per cent 32.14 51.76 4'86 0.73 8.17 0.24 1'81
K20 . . . . . . . . . . . . . . . . . . . NalO,. . . . . . . . . . . . . . Total
..................
Peu cent 0.25 0.62 100.68
Oinx'sofCI . . . . . . . . . .
2.19
..........
98.39 1.62 1 E O
Undetermined
TOTAL.. ...............
As the nonvolatile portion of the water-soluble part contained 8.27 per cent of SO3, it is evident that this scale consists mainly of ammonium sulfate and calcium sulfate, with probably some potassium or sodium sulfate, and small quantities of the chlorides of these bases. I n order to ascertain the influence of the coal-ash contamination upon the foregoing results, a sample of incrustation that had been formed by a leakage through the flue with subsequent evaporation, was later obtained from the outside of a char filter chimney and analyzed. This deposit, which was practically free from coal ash, almost pure white in color, and crystalline, consisted of 98.29 per cent mater-soluble and 1.71 per cent water-insoluble matter. The matersoluble material consisted of 28.07 per cent organic and volatile matter and 71.93 per cent mineral matter. The water-insoluble matter consisted of 91.63 per cent organic
Vol. 19, s o . 2
and volatile matter and 8.37 per cent mineral matter, Thus the scale consisted of 29.16 per cent organic and volatile matter and 70.84 per cent mineral matter. It contained 20.06 per cent ammonia (16.51 per cent nitrogen) and 56.30 per cent sulfur trioxide. Although the composition of this second chimney scale does not correspond exactly with that of the first, it is close enough to indicate that the complete analysis of the watersoluble portion of the first scale gives a fair indication of the composition of these deposits. Char Drier Incrustation I n the burning of bone black in the ordinary vertical retort kiln, the hot gases from the fuel bed (in thi-b case coal) are passed through the horizontal pipes of a superimposed drier, the wet black being partially dried before entering the retort pipes by passing through this drier. A yellow scale found adhering in the form of incrusted nodules t o the inside of drier pipes which had been in use for about twent'y-five years was scraped off and analyzed with the following results: Per cent SiOz . . . . . . . . . . . . . . . . . . . . 3.04 C a O . . . . . . . . . . . . . . . . . . 0.68 FepOa . . . . . . . . . . . . . . . . . . . 46.02 P 2 0 6 . . . . . . . . . . . . . . . . . . 0.80 so3.. . . . . . . . . . . . . . . . . . . 31.12
Per cent Undetermined,.
........
2.75
Investigation showed the SiOz to be present as such, the (KHJZO as (NH&S04, and the CaO as Ca3(P01)2. This left the Fe present as a combination of Fe203(46.02 per cent.), HzO (10.21 per cent), and So3 (22.89 per cent), which corresponds to a formula, Fe2S04(0H)4. This formula corresponds to that of the insoluble salt produced from certain iron mordants as described by Roscoe and Schorexcept that the water of crystallization does not seem to be present. This is probably due t o the fact that t,his scale was subjected to a considerable and continuous heat during its formation. This scale may therefore be said to have the following composition: Per cent Si02 . . . . . . . . . . . . . . . . . . . . 3.04 (NHa)zSOa., . . . . . . . . . . . . . 13.66 Cas(P0a)z. . . . . . . . . . . . . . 1.48
Per cenl FeSOd(0H)p . . . . . . . . . . . . Undetermined, , . . , . . , TOT.4L..
..............
79.07 2.75
100.00
Heater Incrustation I n order to extract as much heat as possible from them, waste maters from char filters are passed through so-called Miles heaters. These heaters consist of two horizontal headers in which are expanded vertical copper tubes. The hot waste waters are passed through these copper tubes, and incoming cold fresh water is passed around the outside. After several years of use, the insides of these copper tubes are usually incrusted with a black slimy deposit, ordinarily organic, and readily removable by hot caustic soda solution. A heavy black incrustation of the copper tubes removed from one of these heaters in this refinery proved to be insoluble in caustic soda solution. This scale was arranged in strata, varying in color from a blue-black to a jet black, and when dried had the following composition: Peu ceiit CUS. . . . . . . . . . . . . . . . . . . . CuO.. . . . . . . . . . . . . . . . . .
55.38 39.94 C"SO4.. . . . . . . . . . . . . . . . 0 . 5 2 Si02 . . . . . . . . . . . . . . . . . . . 1.39
+ Alz CaO ........ Fen03
Per cent 1.51 0.27 -
. . . . . . . . . . . . . . . . 99.01 TOTAL.
The formation of this very unusual scale can probably be ascribed to the frequent presence of hydrogen sulfide or other sulfurous compounds in the char waste waters, these being particularly noticeable by the odor of the Tvaste water 2
"Treatise on Chemistry," I'd. 11, p. 1239.
ISDLTSTRI.4L ASD E S G I S E E R I S G CHEMISTRY
February, 192T
fiers consist of a series of horizontal superimposed shallow trays, the water entering a t the top and flowing from tray to tray, leaving a t the bottom on its way to the boilers. The function of the trays is to hold back as much of the precipitated sludge as possible. It was found that the water leaying these purifiers, although ordinarily clear, was distinctly turbid a t the time these samples mere taken. Contrary to our expectations, t'his separated material was found to consist almost entirely of a basic magnesium silicate. Complete analyses of the scales found in the Hoppes water purifier n-ere made. The pans in the water purifier, opened for this purpose, Tvere heavily loaded with precipitated sludge, deposit'ed a t both top and bottom. As the bottom sludge had a somewhat different appearance from the top sludge, samples of bpth xere taken from each row of pans. Analyses of these scales are shown in the table at the foot of this page. These results explain the react'ions taking place in the purification of the boiler feed water. The lime compounds were readily separated and deposited from the water, as shown by the decrease of the CaO and CO, from the top t o the bottom of the purifier. The percentages of MgO, SiO,, and combined water increase from the top to the bottom. Obviously then the cause of our trouble was the slow precipit'ation and separation of the magnesia in the form of basic magnesium silicate, a separation so slow as to be incomplet'e n-hen the water left the purifier. The percentages of CaO and C 0 2 are consistently higher, and those of MgO, Si02,and combined water are consistently lower in the top scale than in the bottom scale. This difference in composition is probably due to the fact that the mater splashes into the tops of the trays, while the bottom scales are deposited from water overflowing from the top and running down along the bottom of the trays to the next row. The separation of the basic magnesium silicate does not seem to be a function of time only, but also seems to be very susceptible to slight changes in operating conditions.
after it has been allowed to remain in the char filter or other receptacle. The insoluble cupric sulfide would of course be readily formed by the direct action of the sulfurous waste water upon the copper tubes. The formation of the cupric oxide can probably be best explained by the interaction of the ammoniacal bodies always present in waste water with either the cupric sulfide or the copper tubes, or by the interaction of the caustic soda with which these tubes had been boiled seyeral times with the cupric sulfide. Contrary to our expectations, thi? black scale contained no organic matter. The copper sulfate was probably formed by the oxidation of some of the cupric sulfide. As topper sulfate is readily soluble in water, its presence in this scale can only be explained by the observation that it occurred in the lower portion of the scale only, colyered by an impervious layer of the insoluble copper sulfide and copper oxide. Press Plate Scrapings
The ordinary plate-and-frame filter press seems to be peculiarly susceptible to the deposition of scale upon the corrugations and faces of the plates. At times this scale becomes so heavy as to necessitate its removal with sharp scraping tools. Dense scales from two presses of this kind, which had been used for several years for the filtration of phosphate sludge from the refinery bag filters, were removed by scraping, freed from all fibers and magnetic material, dried, and analyzed. Scale S o . 1 was obtained in 1919 and Scale S o . 2 about two years later. Scale S o 1 Scale No 2 Per cenl Per cenl Organic m a t t e r . 2 9 . 9 9 30.46 C a O . . . . . . . . . .21 . 3 3 22.45 14.16 Fen08 T AlcOa. . 1 2 . 4 1 13.37 S O , . . . . . . . . . ., 1 4 . 8 9
ScaleNo 1
ScaleXo 2
Per cent
Per Lent P2Os. . . . . . .. 7 . 2 5
3.81 2.84 (.92 1.64
RIgO.. . . . . . 6 . 4 8 C o t . . . . . . . .6 . 6 0 S O $ . . . . . . . .. 0 . 91
__
__
TOTAL. . . ..99,76
90,65
Boiler Incrustation
Yellowish brown stalactitic deposits around t'he caps of water tube boilers, caused by leakage from within the boiler, were examined. Investigation showed that traces of waste water from the char filters had leaked into the boilers where, through interaction with the soda ash present, it formed bhe deposit. Analysis of this stalactit'ic scale gave the follox-ing results : HzO (hygroscopic) (110' C . ) ,. Hz0 (combined) (300' C . J . .. .
Per cent 5 25
8.44 Na2COa. . . . . . . . 21.19 NaaSOI . . . . . . . . . . . . . . . . 1 5 , 2 1 NaCl . . . . . . . . . . . . . . . 5 . b 0 NatC02. . . . . . . . . . . . . . 1 7 . 3 4
Steam Trap Sludge
X return trap used for a long time to separate the condensate from our steam lines was found on being opened t o be almost full of a heavy oily deposit. A portion of this deposit was extracted until free from oil and the residue dried. The oil-free sludge had the following composition:
Pev cenl SazO,.. . . . . . . . . . . . . . . SarSiO8.. . . . . . . . . . . . KzSOb .
. . . . . . . . ........
+IlgSiOa \ohtile
matter..
221
3.61 0.6i
Per c e i i t M o i s t u r e . ,. . . . . . . . . . 1 . 4 7 Organic matter H20 (combined' . . . . . . 2 0 . 8 2
9.73
0.92 . __ 11.30
TOT.AL. . . . . . . . . . . . . . . . 9 9 . 4 6
I'eu c e n t Ah03.. . . . . . . . . . . . . 1.19 Cu . . . . . . . . . . . . Trace Z n . . . . . . . . . . . . . Trace S O ? .. . . . . . . . . . . . . . 23.42 sua.. . . . . . . . . 0.S6 P n O b , . . . . . . . . . . . . . . . 0.55 CI . . . . . . . . . . . . 0.35
c
0 2 \ 1IgO.. . . . . . . . . . . 24.77 . . . l?,l4 FezOa. . . . CaO . . . . . . . . 1.92 LTazO.. . . . . 4.42 K,O . . . . . . . . . . . . . . . . 1 . 9 1
Water Purifier Incrustations
I n the purification of boiler feed waters containing rather large quantities of calcium and magnesium carbonates, bv the use of a mixture of soda ash and caustic scda, the following procedure was adopted. The water TWS mixed continuously with the niixed purifying reagents and immediately passed through Hoppes Tvater purifiers. These puri-
--
T O T A L .. . . . . . . . . . . . . . . 9 9 . 8 3
This sludge therefore consists mainly of oil, basic silicate of magnesium, and iron rust. The basic silicate of magnesia was undoubtedly carried 01-er by entrainment from the boilers and deposited in the trap.
Analyses of Water Purifier Incrustations N.aruxc
l'.iS s u 1
'
F I X
UF
ISCKVST.ATIUS To11 Bottom, T o p ~
Si02 Organic FecOs - .LIX,, CaO LIgO SOJ CO2
H?O (comhined: P205
so 2 noitom
No. 4 ~FI I AN
SC8, 3
~
T o p Bottom1
PAN
1
PAN
Top Bottom1 T o p
s o . .5
I
P A X SU. t i P.iS ____
Bottom' Top
~
xi0
7
~
P.iS
NO.
Y
1
I'.iS s o . 9
E o r t o m ~T o p Bottom1 Top Hottom] ToIi Bottom
