J u l y , 1916
T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E RI NG C H E M I S T R Y
will be designated for t h e sake of brevity as t h e “Standa r d ” method a n d t h e “ C u O ” method, respectively. GAS No. 24 GAS No. 24 GAS No. 25 METHOD: Standard CuO Standard CuO Standard CuO 0.0 0.1 0.1 0.0 0.0 0.1 Carbon dioxide, ....... 0.3 49.3 50.8 50.7 Heavy hydrocarbons... 4 8 . 1 48.2 4 7 . 9 4 9 . 8 0.4 0.5 0.5 0.4 0.5 0.5 0.5 Oxvnen . . . . . . . . . . . . . . 0.1 0.9 0.1 1.1 0.2 0.2 Ca;coon monoxide., , , , 1.2 10.3 9.3 9.2 10.4 Hydrogen.. . . . . . . . . . . 1 1 . 9 1 1 . 9 1 2 . 1 38.4 37.0 37.2 Paraffins. . . . . . . . . . . . . 3 7 . 3 3 7 . 6 3 7 . 7 3 8 . 1
_ _ - _ _ _ _
Total
99.3
98.4
98.5
98.7
97.6
99.7
~
98.7
T H E GAS R A T E
The gas rates for three temperatures are plotted against t h e oil rates in Fig. 8. At 621’ C. t h e gas r a t e increases with t h e oil r a t e u p t o an oil r a t e of 2 0 cc. per minute, b u t t h e introduction of more oil per minute causes no further increase i n t h e gas rate. Apparently with a heated t u b e of t h e dimensions used here only a certain q u a n t i t y of oil can be affected in a given time b y heat a t a temperature of 621’ C. A similar limitation would be expected in a commercial machine operating a t this temperature. At 7 2 3 ’ C. t h e gas r a t e is greater with greater oil r a t e a t all oil rates studied. Judging from t h e shape of t h e curve a n d from t h e analogy of t h e 621’ C. curve i t is apparent t h a t a n increase in oil r a t e above 45 t o 50 cc. per minute would produce no increase in t h e gas rate. At 825’ C. t h e gas r a t e increases with increase in oil r a t e as can be
601
THE EFFECTS OF MOISTURE INTRODUCED INTO THE DIGESTER IN THE COOKING OF SODA PULP By S. D WELLS Received M a y 1, 1916
T h e work of t h e Forest Products Laboratory in studying t h e il;fluences of t h e various cooking conditions in t h e manufacture of soda pulp from aspen indicated t h a t in varying a n y one of t h e four variables, steam pressure, initial concentration, amount of caustic soda used per unit of wood, or duration of cooking a n d maintaining the other conditions cons t a n t , t h e amount of bleaching powder necessary t o bleach t h e pulp t o a standard white was constant for a n y given yield of pulp. Twenty-four semicommercial cooks were made in studying these four variables a n d t h e yields of pulp obtained plotted 30
l
28
l
l
l
l
l
i
OAMOUNT ff CAUSTIC SODA ODURATION OF WOKING *PRESSURE ff COOKING OCONCENTRATIOW OF CAUSTIC SODA
YIELD-TOTAL
CRUDE PULP-PER
CENT
FIG. I
EFFECT OF VARYINGGAS RATE WITH VARIOUSOIL RATES AT THREE TEMPERATURES
seen, a n d at t h e oil rates studied there is no apparent tendency for a r a t e t o be reached beyond which there is no further increase. Obviously, however, such a point would be reached. I n comparing t h e gas r a t e curves it is interesting t o note t h a t a t low oil rates t h e change in temperature from ,621 t o 7 2 3 ’ C. has a much greater effect t h a n t h e change from 7 2 3 t o 8 2 j ’ C. At low oil rates a temperature of 7 2 3 ’ C. is sufficient t o gasify permanently t h e greatest portion of t h e oil. T h e slightly greater production of gas a t 8 2 5 ’ C. is largely due t o t h e decomposition of methane into carbon a n d hydrogen. As t h e oil r a t e increases, a temperature of 7 2 3 ’ C. becomes less a n d less effective for t h e purpose of permanently gasifying t h e oil; 825’ C. is much more effective, as can be seen from t h e increasing divergence between t h e curves. ( T o be concluded in our n e x t issue) DEPARTMENT O F CHEMICALENGINEERING COLUMBIAUNIVERSITY,NEW YORK CITY
against t h e bleach consumption are shown in Fig. I obtained from Bulletin 80 of t h e United States Department of Agriculture. This curve apparently indicates t h a t a n y reduction i n t h e consumption of bleach made b y altering a n y of t h e four variables mentioned cannot be brought about without lowering t h e yield. All t h e cooks made in t h e series, however, were in a digester of only 7 0 gals. capacity a n d t h e condensation during t h e cook was about six times as great as in a commercial sized apparatus of 31/2 cords capacity. A series was, therefore, run where all t h e conditions were maintained constant except condensation a n d this factor was varied b y using a combination of direct steam a n d indirect heating b y means of a jacket in t h e lower portion of t h e digester. T h e results obtained developed t h e remarkable fact t h a t on increasing t h e amount of condensation the yields of pulp were increased and a t t h e same time t h e quality of t h e pulp was slightly improved a n d t h e bleach consumption necessary t o obtain a standard white was decreased. The curves in Fig. I1 show t h e relation of bleach consumption a n d yield t o t h e amount of condensation during t h e cook, using t h e following- conditions:
.................. 90 R. per 1.
Concentration of N a O H . . N a O H per 100 lbs. chips.. . . . . . . . . . . . . . . . . . Maximum steam.pressure.. . . . . . . . . . . . . . . . . Duration a t maximum pressure.. . . . . . . . . . . . Time necessary to reach maximum pressure.. .
25 lbs. 120 lbs. per sq. in 4 hrs. 1 hr.
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
602
The yield of pulp was increased from 43. j per cent to 4 7 . I per cent of t h e weight of wood used or a n increase in t h e output of pulp from the same quantity of wood using the same quantity of cooking chemical and fuel of over 8 per cent while t h e quality of t h e pulp was improved a n d t h e bleach copsumption lowered from 13 t o 11 lbs. of bleaching powder per I O O lbs. of pulp. I n seeking a n explanation of this phenomenon, it was necessary t o study t h e conditions in t h e digester during t h e cook. The consumption of caustic soda as shown in Fig. 111 was very rapid during t h e first hour and a half b u t constantly decreased in rate and after the second hour had reached a point where only one-fourth of t h e original caustic was present as such. The condensation of steam increased very rapidly during t h e first hour due t o t h e fact t h a t t h e contents
caustic soda solution has penetrated t h e chips a t nearly t h e original concentration. It is evident t h a t t h e uncooked inner portions of the chips are capable of adsorbing sufficient caustic soda for their reduction, b u t on t h e conversion of this material t o pulp the adsorptive power is so reduced t h a t the remaining caustic soda passes back t o the liquor. The increased volume due t o condensation also more effectually removes t h e products of reduction from the wood and decreases the contamination of the pulp therefrom. I t is evident, then, t h a t while the power of t h e caustic soda t o reduce the ligno-cellulose is not diminished, t h e attack on t h e pulp is considerably decreased
I
! 1
i
i
1
2 s 4 T l Y K COOKIIIP-HOURS
i 5
I
I
1
2 3 4 TIME COOKIMP-HOURS
FIG. I11
542. E41
‘
-4--?-
1
i
Vol. 8, No. 7
5
FIG. IV
and t h e coloring of the pulp by t h e products of reduction is much less, thereby decreasing t h e bleach necesL-sary t o obtain a standard white. While no tests on a 1 I I commercial scale ha\-e yet been tried, it seems probai ble t h a t the same advantages would be gained. The equivalent of t h e added condensation could he obtained by injecting hot water with t h e steam supplied, by which means perfect control could be comparatirely simple. The only disadvantage would b e t h e increased volume of the black liquor t h a t ~ o u l d h a r e to be handled in the recovery of the soda. With multiple-effect evaporators, however. the excess water could be ex-aporated with very small increase in the fuel consumption and t h e increased production of pulp mould be attained a t extremely small cost. FOREST PRODVCTS
LABOR.4TORY
L f A D I S O S . \vISCOKSIN
THE RATE OF AMMONIA DISTILLATION FROM WATER By F . W. BRUCKMILLER
Received March 21, 1916
I n the determination of the ammoniacal nitrogen in waters, t h e quantity of ammonia obtained depends upon a number of factors, principal among which are t h e volume of t h e distillate sa\-ed and the rate a t which the ammonia comes over. Regarding this matter, Wanklyn,’ the originator of the method, s a y s : “The recommendation has heen given to nesslerize only the first j o cc. of the free ammonia and to throw away the next I j o cc. Formerly, it was,our custom to nesslerize all four 50 cc. tubes for the free ammonia, but that was a useless trouble, inasmuch as the first j 0 cc. invariably contained three-fourths of the total free ammonia, The rule is, therefore, to nesslerize the first j o cc. of the distillate and then add one-third. In the instance of the albuminoid ammonia, i t is necessary to nesslerize each separate j 0 cc. of the distillate (4) and to add the amounts together in order to arrive at the total albuminoid ammonia.” 1
“Water h n a l p i s . ” 1896, 43.
