TND USTRIAL AiVD ENGINEERING CHEMISTRY
104
by electric or electromagnetic means, certainly should be more considered in this respect. This will need a revision of our present conception of so-called structureless or amorphous matter. But this revision having been realized, I do not doubt for a moment that the result will be as fruitful as Arrhenius’ theory of ions, a theory which when first published did not greatly increase the scientific esteem of its mental father. The value of applied colloidal knowledge may be demonstrated by a simple experiment. If we compare a rubber cement such as is obtained by dissolving milled rubber in an organic solvent to a concentration of 5 per cent rubber and natural rubber latex of 35 per cent rubber content, we find that the latter has the lowest viscosity. If, however, we dip a mold into such a solution and dry the adhering film, we find that the film obtained by the latex dip is considerably thinner, owing to the poor adhesion of this type of water dispersion. This known factor has been a considerable drawback in some lines of latex application. A close study of the colloid chemistry of rubber, however, has shown us various ways of overcoming these difficulties. For example, by dipping a mold, which is covered with a varnish which will act as a coagulant, into the latex, the non-adhesiveness of the water phase may be replaced by the effect of coagulation of the dispersed rubber. The result is a reasonably thick uniform coating in one operation. Just a few words in regard to the most recent development in structure research, a line which I have already emphasized as being of the greatest importance in attempting to imitate nature, not only chemically, but also in building up compounds from a structural point of view. It has finally been possible, after long and extensive work, to obtain a picture of the structure of cellulose which will meet any demand in regard to chemical reactability, etc. It has been ascertained that two glucose radicals joined in a 1-4 link, and therefore present in a digonal helix configuration, cause the appearance of what we term “identity periods” in x-ray analysis of fibrous materials. We have, furthermore, considerable evidence that such celluIose double rings are linked up to form straight main-valency chains and that 40 to 60 of these chains lined up parallel are held together by micellar forces, thus forming a cellulose particle. In my opinion the most important concept which can be arrived at, and the only one I shall mention here, is that nature makes a preferential use of the principle of building
VOI. 21, N o . 2
in the form of main-valency links to long chains. I am even convinced that the future will prove that the linkage of amino acids in proteins is another example. Furthermore, Emil Fisher’s now practically discarded experiments seem to lead to this conclusion. Rubber in stretched condition is another example of the validity of such a conception, which is especially valuable because rubber when stretched to a maximum will behave similar to a natural fiber. This work, however, necessitates a somewhat different attitude in regard to terminology than has been assumed in recent years, especially when talking of molecules. The term “molecule” should only be used for substances that can be isolated in the pure state and properly identified. One is entitled to talk of a cellobiose or glucose molecule, but not of a cellulose molecule. A hexose would be a main-valency chain of linkedup glucose radicals and a cellulose micella is composed of main-valency chains closely packed and attached one to the other by micellar forces. One can talk of an isoprene, perhaps of a dipentene, molecule, but to talk of a rubber molecule means nothing, as the dimensions of such a thing depend on factors beyond our control. This main-valency chain formation can extend in one, two, or three directions into space, and differs distinctly from the so-called molecular lattices of some organic substances derived by simple association forces. In the present case the link is a chemical one, which also explains simply the heretofore unexplainable differences in behavior towards solvents, reactabilities, etc. A closer and still more detailed knowledge of structures and their bearing on properties is, however, essential for a thorough understanding of this class of natural colloids, which have so unique a value in the today’s industries and in life in general. UP
Conclusion
I hope that I have been able to emphasize your interest in a branch of science which is still in the midst of its childhood, a branch which will need as much attention t o grow as a child in becoming a valuable member of society, and may demand a considerable change in our present conceptions, just as the youth of today has forced many a parent to change his way of looking a t things, in short a branch whose maturing will aid in the development and growth of science and industry, just as we all hope that our children will become valuable factors in the future of our country and of the whole world.
Thermal Characteristics and Heat Balance of a Large Oil-Gas Generator’ Robert D. Pike and George H. West 4068 HOLDEN ST.,EYZRYVILLE, CALIF.
N T H E Pacific coast, except in Washington, manufactured city gas is made largely from California residuum fuel oil. This also applies in other scattered localities in the United States. The generators used are large and operate with low maintenance and labor costs. The large quantity of oil available a t the present time gives this process considerable interest. This article presents the results of a five-day test conducted on a large gas generator of the Jones type, one of a set of five operating a t the Potrero, San Francisco, plant of the Pacific Gas and Electric Company. The generator is illustrated in outline in Figure 1, which shows the relative dimensions of the two connected shells,
0
1
Received May 16, 1928.
which are filled with checker brick. The cycle of operation is 20 minutes long and consists of three periods-the make, the blow, and the heat. The make lasts for 10 minutes. During this period oil and steam are introduced a t several points in each shell, passing downward in each, and gas is removed through the offtake of the secondary shell t o the wash box, where the temperature is lowered to slightly above atmospheric, and lampblack and tar are removed from the gas stream. The blow lasts approximately 5 minutes and is intended to burn out carbon deposited in the generator during the make. The oil feed and the greater part of the steam are shut off, and air is blown in at the top of the primary shell,
February, 1929
INDUSTRIAL AND ENGIATEERIXG CHE;MISTRY
105
passing through both shells and out a t the top of the secondary. Auxiliary air is introduced a t the bottom of the secondary after the first minute of the blow. The heat lasts approximately 5 minutes. Oil and air are fed in a t the top of the primary and burn while passing through both shells, finally leaving a t the top of the secondary. The heat brings the brick checkerwork up to temperature again after the slight cooling of the blow.
The amount of steam used during blowing and heating could not be obtained by direct measurement. Recourse was accordingly had t o analysis of the water content of the waste gases. Since the amount of these waste gases could be calculated from the measured oil and air input, this analysis allowed the calculation of the total amount of water leaving the generator. By subtracting from this total the amount of water entering the generator in the air and oil, the amount introduced as steam was obtained. The composition of the waste gases was obtained by Orsat analysis, and the water content by aspiration of a known volume of the gas through a calcium chloride tube. The gas samples were obtained through a 3/4-in~hsampling tube, which was automatically swung into the waste gas stream when the atmospheric valve a t the top of the secondary was opened. Two continuous gas samplers were used, the first taking gas during the first 5 minutes, corresponding approximately to the blow, and the second during the second 5 minutes, corresponding approximately to the heat. The temperature of the waste gases was obtained by means of iron-constantan thermocouples inserted through the wall of the secondary shell immediately below the atmospheric valve, and exposed bare to the gas stream. A radiation screen was used to minimize error due to radiation from the Figure 1-Plan a n d Elevation of Jones Gas Generator thermocouple to the atmosphere. GAS-~IAKIKG PERIOD-The amount of oil used was measThe relative durations of the blow and heat are variable, ured and corrected as described for the oil measurements but the combined duration of these two periods is always during the blowing and heating period. 10 minutes. I n the subsequent calculations of test data, the The amount of steam used during the gas-making period combined blow and heat will be treated together as half of was estimated from boiler-room records, which showed that the cycle, and the make as the other half of the cycle. steam was furnished during the make a t the steady rate of 14,000 pounds per hour. Test Measurements The temperature of I n order t o run a heat balance on the generator it was first the manufactured gas necessary to establish a material balance. Test measure- was m e a s u r e d in the offtake from the secments were made as follows: BLOWINGAND HEATING PERIOD-The amount Of air to ondary shell by means the generator was measured by a Venturi meter located in o f a c o n t i n u o u s r e the air-supply line, as indicated in Figure 2. Readings were corder. This recorder taken on an indicating water gage with which the Venturi was calibrated against meter was equipped, and also with a continuous dial recording a potentiometer with gage. The readings of the indicating water gage were the i r o n - c o ns t a n t a n checked by means of two Pitot tubes installed 12 feet above thermocouple in place. The composition of the Venturi meter. Since it was not possible to make the Pitot tube measurements a t a point farther removed from the manufactured gas irregularities in the pipe line, particular care was exercised in was obtained by analytraversing the cross section of the pipe, and 960 separate sis of the gas from the readings were taken to establish the constant for the Pitot entire plant, and is thus tube. It was found that the Pitot tube measurements an average figure. The amount of the checked those of the indicating water gage within 1.2 per cent. The recording gage was then calibrated against the latter, and manufactured gas could test data were taken by means of the charts from this record- not be m e a s u r e d directly, but was calcuing gage. '"* '"" The amount of oil fed t o the generator was measured by lated from the amounts of oil used in the genmeans of oil meters, which showed the quantity of oil used for heating, the quantity used for making gas, and the total erator under test and in Figure 2-Sketch of Air Piping plant consumption. These meters were checked against the t h e e n t i r e Dlant. tcrecords of oil storage and shipment and were found t o read gether with t i e total plant production of gas. The composition of the oil was obtained by analysis of approximately 5 per cent low. Although the assumption that these meters were mutually consistent is not necessarily typical California fuel oil used for gas generation. valid, i t must be made, since there was no available way of ASSUMPTIOKSCONCERNING TRANSITION CONDITIONSchecking individual meters. On the basis of this assumption, During the gas-making period steam is furnished continuously a meter correction factor of 1.05 was applied to the meter a t a steady rate to the generator. After 1minute oil is turned readings to obtain the volume of oil consumed. I n convert- on for 6 or 7 minutes, after which it is turned off and steam ing volume data t o weight, a further correction factor of 0.99 only is supplied during the last 2 or 3 minutes. I n spite of on the density was necessary in order to allow for the increase this, the gas rushing from the atmospheric valve a t the end in temperature above that a t which the density was deter- of the make period occasionally burns, indicating that conmined. siderable gas must still be present in the generator. Since
Imro*
1
-
I Hmm* 1
INDUSTRIAL AND ENGINEERING CHEMISTRY
106
it is impossible to ascertain the exact analysis of this residual gas, it is assumed that it is composed half of steam and half of made gas by volume. When the valve is being closed after the heat period, the oil and air are shut off, but the steam is not. Although the residual gas in the generator a t this instant probably contains a little more steam than the stack gases during the heat, it is again impossible to obtain an accurate analysis. It will be assumed, therefore, that this residual gas has the same analysis as the stack gases during the heat. It will be seen during the calculations that these assumptions can introduce no serious error, owing to the relatively small amounts of materials involved.
Vol. 21, No. 2
Volume Per Cenl 45.9 26.2 13.2 3.2 1.2 6.5 0.5 3.3
Hz CHI
co
C2H4 CsHa
coz 0 2
Nz
Weight Per Cent 6.30 28.75 25.35 6.14 6.42 19.60 1.10 6.34
-100.00
--
100.0
Lampblack production-13 pounds per 1000 cu. f t . of made gas at 32" F. and 7.3 inches of water above atmospheric pressure. Heating value--14,900 B. t. u. per pound by bomb calorimeter. Analysis of lampblack (assumed from heating value) : Weigh1 Per Cent Carbon Hydrogen
99.2 0.8
Plant Data
100.0
Total plant oil consumption during test, gallons Total plant gas production during test, cubic feet at standard conditions Average gas production, cubic feet per generator cycle Oil consumption, Generator 5 , gallons per cycle Average gas production, Generator 5 , cubic feet at standard conditions
4 68,333 65,650,000 62,100 433.7
Tar production-2.5 pounds per 1000 cu. ft. of made gas a t 32" F. and 7.3 inches of water above atmospheric pressure. Heating value-l3,716 B. t. u. per pound by bomb calorimeter. Analysis of tar (assumed from heating value) :
61,200
Weight Per Cent Carbon Hydrogen Oxygen
Test Data
90.00 2.04 7.96
Blowing and Heating Period
Air consumption-average
100.00
of 340 cycles:
Calculations
DURATION AIR OF PERIOD AIR FLOW CONSUMED Min. Cu. ft./min. Cu. ft. 0.25 .... .... 0.75 16,800 12,600 2.98 19,300 57,500 3.73 .... 70,100 5.77 16,350 94.450 0.25
PERIOD Valves open Primary blow Primary and secondary blow Total blow Heat Valves closed
....
Oil consumption-average of 350 cycles, 56.7 gallons per cycle. Analysis of fuel oil and chief properties: DISTILLATION Carbon Hydrogen Oxygen Nitrogen Sulfur Water
WEIGHT Per cent 86.0 11.0 1.0 0.2 0.8 Heating value by bomb calorim1.0 eter--18,554 B. t. u. per lb. 100.0
Per cent 150 0.75 200 1.7 250 8.6 25.7 300 51.5 338 Residue 9.5 97.75
of 311 readings: c.
O
797 784
During blow During heat
F.
1467 1452
Nz
Humidity of air-90 0.031
per cent a t 93" F. ; lbs. H20 per lb. dry airGas-Making Period
Oil consumption-average of 350 cycles, 381 gallons per cycle. Steam consumption-2333 pounds per cycle. Temperature of manufactured gas-average of 14 cycles: At end of make At beginning of make Average
Analysis of manufactured gas:
841 759 so0
2490.0
(2) Tar Weight of tar per 1000 cu. ft. gas a t standard con-
ditions, lbs.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Weight of tar per cycle, lbs.. . . . . . . . . . . . . . . . . . . . . . . . Weight of elements in tar per cycle: Per cent 90.00 2.04 7.96
2.61 160
Lbs 144.0 3.3 12.7
--
--
160.0
Per cent 99.2 0.8
Carbon Hydrogen
100.00 Weight Per Cenl 5.02 11.41
c.
---
100.00
conditions, lbs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.57 Weight of lampblack per cycle, lbs.. . . . . . . . . . . . . . . . . . 831.O Weight of elements in lampblack per cycle:
100.00 HIO
---
( 3 ) Lampblack Weight of lampblack per 1000 cu. f t . gas at standard
---
__
Lbs. 1218.5 372.5 741.2 157.8
100.00
Volume Per Cent Blow Heat 12.81 15.38 0.27 0.33 4.29 0.61 82.63 83.68
0 2
Per cent 48.93 14.95 29.78 6.34
Carbon Hydrogen Oxygen Nitrogen
Carbon Hydrogen Oxygen
Analysis of waste gases:
coz co
Volume of gas produced per cycle, cu. f t . a t standard conditions. . . . . . . . . . . . . . . . . . . . . . . . 0.0407 Density of gas, lbs. per cu. f t . . . . . . . . . . . . . . . . . . 61,200 Weight of gas produced per cycle, lbs.. . . . . . . . . . 2490 Weight of elements in gas per cycle:
F.
--
Temperature of waste gases-average
( 1 ) Manufactured Gas
O
F.
1546 1398 1472
Lbs. 824.4 6.6
--
__
100.0
831.0
( 4 ) Residual Gas, End of Heat
Volume of gas a t 1800" F. and 20 inches water in excess of atmospheric pressure, cu. f t . . . . . . . 13,000 0.0787 Density at standard conditions, lbs. per cu. f t . . . Weight of residual gas, lbs.. . . . . . . . . . . . . . . . . . . . 234.5 Weight of elements in residual gas: Carbon Hydrogen Oxygen Nitrogen
DRYGAS Per cent 5.49
HzO Per cent
15'00 68.10
10 13
i:is ... _-
88.59
11.41 100.0
--
DRYGAS Lbs. 12.9
...
35 2 169.7
--
207.8
Hz0 Lbs. 3:0 23.7
.. --
26.7 234.5
INDUSTRIAL AND ENGINEERTNG CHEMISTRY
February, 1929
( 5 ) Residual Gas, End of Make Volume of gas at 1600" F. and 30 inches water in excess of atmospheric pressure, cu. ft.. . . . . . 13,000 0.0455 Density at standard conditions, lbs. per cu. f t . . . . Weight of residual gas, lbs.. . . . . . . . . . . . . . . . . . . . 152.5 Weight of elements in residual gas: HzO
DRYGAS
Per cent Carbon Hydrogen Oxygen Nitrogen
...
21.90 6.70 13.33 2.84
6.19 49.04
... --
--
44.77
DRYGAS Lbs. 33.4 10.2 20.3 4.3
Per cent
.. --
68.2
Carbon Hydrogen Oxygen h'itrogen Sulfur
X)
Total weight of waste gases from heat per cycle, lbs.. .... 7657 Weight of elements in waste gases from heat per cycle:
OIL
Hz0
Per cent
86.0 11.0 1.0 0.2 0.8
0.89
99.0
1.00 100.0
OIL Lbs. 2662.8 327.8 29.8 6.0 23.8
o:ii .. ..
HzO Lbs.
Per cent Carbon Hydrogen Oxygen Nitrogen
Lbs. 261 2072
100.0
2333
_-
3'3 26.5
Carbon Hydrogen Oxygen Nitrogen Sulfur
.. ..
y
Total weight of waste gases from blow, lbs.. . . . . . . . . . . 5586.9 Weight of elements in waste gases from blow: Carbon Hydrogen Oxygen Nitrogen
HzO
Per cent
4.93
0: 56 4.46
l7:34 72.71 94.98
100.0
GAS Lbs. 275.4
....
..
970.0 4061.0
5.02
5306.4..
874
...
5215
HzO
Per cent
86.0 11.0 1.0 0.2 0.8
--
7657
100.0
OIL Lbs. 381.8 48.8 4.4 0.9 3.6
o:ii 0.89 .. .. --
--
1.00
439.5
Hz0 Lbs.
...
0.5 4.0
...
... 4.5
444.0
and Heat
DRYAIR Lbs. 5,031.0 6,779.0
HzO Lbs. 156.0 210.0
TOTALMOISTAIR Lbs. 5,187.0 6,989.0
11,810.0
366.0
12,176.0
---
Total
+ + ++
GAS
6783
OIL
Blow (8) Heat (9)
weight of H20 in waste gases weight of carbon in waste gas from lampblack burned out of eenerator = total weight of waste gases = 0.0502 (5031 x y) = 0.0493 (5031 x y) = 280.5 lbs. H20 in waste gases = 275.4 lbs. carbon in waste gases
Per cent
11.41
Per cent
PERIOD
= y =
y x
98 776
(11) Air for Blow
--
Volume of air used during blow, cu. ft . . . . . . . . . . . . 70,100 Density of air, lbs. per cu. f t . . . . . . . . . . . . . . . . . . . . 0.074 Humidity of air, 90 per cent at 93' F., lbs. HzOper lb. dry air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.031 Weight of moist air, lbs.. . . . . . . . . . . . . . . . . . . . . . . 5187 Weight of HzO in air, lbs.. . . . . . . . . . . . . . . . . . . . . . 156 5031 Weight of dry air, lbs.. . . . . . . . . . . . . . . . . . . . . . . . .
+ x + xy
iika
Components of air for blow and heat per cycle:
( 8 ) Waste Gas from Blow
5031
...
1.28 10.13
...
100.0
Hi0 Lbs.
(10) Oilfor Heat Weight of oil used per cycle, lbs. (9).. . . . . . . . . . . . . . . . . . . 444 Weight of elements in oil per cycle:
Weight of steam used in make per cycle, lbs.. . . . . . . . . 2333.0 Weight of elements in steam:
Let x
...
99.0
11.2 88.8
Lbs. 420
5.49
88.59
2960.2 29.8 2980.0
Per cent
GAS
15160 68.10
(7) Steam for Make
Hydrogen Oxygen
HzO
Per cenf
GAS
84.3 152.5
Volume of oil used for make per cycle, gallons. . . . . . . . 381.0 Weight of 1 gallon oil, lbs.. . . . . . . . . . . . . . . . . . . . . . . . . 7.90 0.99 Temperature correction factor.. . . . . . . . . . . . . . . . . . . . . Weight of oil used per cycle, lbs.. . . . . . . . . . . . . . . . . . . 2980 Weight of elements in oil per cycle: Per cent
= weight of H20 in waste gases from heat +Let 444 + x - 0.11 X 444 X 9 = total weight of waste gases x = 0.1141 (6783 +
x = 874 lbs. H20 in waste gases from heat
Oilf o r Make
(6)
56.7 7.90 0.99 444
1c
6779
Lbs.
_-
55.23 100.0
Volume of oil used during heat per cycle, gallons.. Weight of 1 gallon oil, lbs.. . . . . . . . . . . . . . . . . . . . . Temperature correction factor. . . . . . . . . . . . . . . . . . . Weight of oil used during heat per cycle, lbs.. . . . .
HzO 9:4 74.9
107
H20 Lbs.
...
31.3 249.2
--
Weight of elements in air for blow and heat per cycle: AIR Per cenf Hydrogen Oxygen Nitrogen
Hz0
Per cent 0.34 2.67
AIR Lbs.
Hz0 Lbs. 41.4 324.6
......
22:50 74.49
_-
.. --
9,070.0 ----
2,740.0
... --
96.99
3.01
11,810.0
366.0
(12) Steam for Blow and Heat
Weight of HzO in waste gases from blow, lbs. (8). . . . . . Weight of H20 in waste gases from heat, lbs. (9). . . . . .
280.5 874.0
Total HzO content of waste gases, lbs.. . . . . . . . . . . . . . . 1154.5 Weight of H20 from combustion of oil, lbs.. . . . . . . . . . . 440.0 Weight of HZOfrom air, lbs. (11). . . . . . . . . . . . . . . . . . . . 366.0 Weight of HzO from residual gas after make (5). . . . . . . 84.3 Total of HzO except steam supplied during blow and heat, lbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
890.3
Weight of HzO supplied as steam, lbs.. . . . . . . . . . . . . . .
264.2
...
( 1 3 ) Sensible Heat above 60" F. in Waste Gases
280.5
~386.9
( 9 ) Waste Gas from Heat
Volume of air used during heat, cu. f t . . . . . . . . . . . . 94,450 Density of air, lbs. per cu. f t . . . . . . . . . . . . . . . . . . . . 0.074 Humidity of air, 90 per cent a t 93 F., lbs. Ha0 per lb. dry air . . . . . . . . . . . . . . . . . . . . . . . :. . . . . . . . . . 0.031 Weight of moist air, lbs.. . . . . . . . . . . . . . . . . . . . . . . 6989 Weight of HzO in air, lbs.. . . . . . . . . . . . . . . . . . . . . . 210 Weight of dry air, lbs.. . . . . . . . . . . . . . . . . . . . . . . . . 6779
__-_
COMPONENT Blow:
Cot
CO,
02,
H20 Heat:
COz CO, Hz0
02,
Nz
Nz
HEATCONTENT 1467'F. 6 0 ' F . Diff. Mols B. t. u./lb. mol. 1 2 . 8 1 14,900 250 14,650 8 7 . 1 9 10,200 200 10,000 8 . 8 8 12,800 250 12.550 15.38 84.62 21.80
1443' F. 14,500 250 10,000 200 12,500 250
CHANGE IN HEAT CONTENTGAS
B. 1. u.
Lbs.
187,700 564 870,190 2457 141.200 160 1,199,090 3181
14,260 9,800 12,250
219,000 677 829,500 2372 267,000 393
--__
__
1,315,500 3449
INDUSTRIAL AND ENGINEERING CHEMISTRY
108
Vol. 21, No. 2
Heat Balances T a b l e I-Complete
-x'-= 7657
1315500 3442
61,200
Cycle
47,800
B. I . u . / l 0 0 0 cu. ft. gas Per cent OUTPUT
Heat of combustion:
Total heat content
=
-x
82,200 B. t. u. per 1000 cu. ft. gas
Purified gas, 7;;;;
Material Balances
GEN
1218.5 372.5 1.5 144.0 3.3
GEN
GEN
741.2
167.8
FUR
23.8
12.7
824.4
6.6
275.4 33.4
2.2 19.6
95.2
169.0
1338.1
4.3
80.0 20.6 0 . 03 .6 2575.7 595.3 2187.2 165.7 2 3 . 8 2562.8
18.50 3.28
15,780
1.45
82,200 32,800
7.53 3.01
17,150 Lampblack and t a r (13.52 2.61) X 0.35 (1472 60) 8,000 Residual gas after make 1.11 (1472 - 60) 0.57 900 1.38 Steam in residual gas after make 18,016 (12,800 - 265) 960 Latent heat: 1164.6 Steam in waste gases, 7 X 1085 20,480 "I.& Steam in made gas in offtake, 24.62 X 1085 26,700 Steam in residual gas after make 1.38 X 1085 1,500 H e a t in HnS 110 Heat losses b y radiation and convection and unaccounted for 67,620
1.57 0.73 0.08
Residual gas expelled after make, X 579 Sensible heat above 60' F.: Waste gases (13) Made gas in offtake, 40.68 (1472 - 60) 0.57 24.62 Steam in offtake, 18,016 (12,800 - 265)
-
+
-
Total output
INPUT
Oil (6) Steam (7)gas after heat (4) Residual Total input
53.00
202,000 35,800
-,
OUTPUT
Gas (1) HzS in gas T a r (2) Lampblack: Separated from made gas (3) Deposited in producer a n d burned out in blow (8) Residual gas after make (5) Steam condensed o u t in wash box (by diff.) Unaccounted for Total output
579,000
1.11
(Elements in pounds per cycle) Gas-Making Period CAR- HYDRO- OXY- NITRO-SULBON
579
Lampblack from gas, 13.57 X 14,900 T a r from gas, 2.61 X 13,716
331.3
56.3
6.0
23.8
261.0 2072.0 12.9 3.0 58.9159.72575.7 595.3 2187.2 165.7 2 3 . 8
Blowing and H e a t i n g Periods CAR- HYDRO- OXY- NITRO-SULGEN
BON
GEN
GEN
FUR
0.09 1.88 2;44 0.14
0.01 6.29
1,090,860
100.00
1,037,900 48,900
95.13 4.50
INPUT
++ +
Heat of combustion in oil (48.69 7.25) 18,554 H e a t in steam above 60' F. (38.12 4.32) 1152 Sensible heat above 600 F , : 7.25) I n oil, (93 - 60) 1.35 (48.69 I n air for blow and heat, (428 200)
19ii5 -
2,500
0.23
1,560
0.14
-_--
Totalinput
1,090,860
--
100.00
OUTPUT
Waste gases: From From blow heat gas from Unaccounted
T a b l e 11-Blowing (8) including residual (Q), heat
for
Total output
275.4 420.0 -4.8
-_
690.6
31.3 98.0 12.7
1219.2 4061.0 1924.0 5215.0 2 5 9 . 0 -200.8
__ __ -
-
3402.2
9076.2
3.6
49.3 41.4 29.5 19.6
8.4 3064.6 234.0 95.2
0.9 9070.0
3.6
INPUT
Oil for heat (10) Air for blow and heat (11) Steam for blow a n d heat (12) Residual gas from make (5) Lampblack deposited in producer make and burned out during blow (8)
381.8
275.4
-_
2.2 ---
--- -
Total input
690.6
142.0
9075.2
33.4
G a s - M a k i n g Period-Actual
3402.2
E. 1.
u. /I000 cu. ft. gas Per cent
OUTPUT
Sensible heat above 60' F. of waste gases Losses b y radiation and convection-(half amount for complete cycle) Latent heat of steam in waste gases Useful work in heating checkerwork (by diff.) Total output
4.3
82,200
39.20
33,810 20,480 73,180
16.15 9.75 34.90
___
--
209,670
100.00
134,500 68,600
64.14 32.72
320 1,560 4,690
0.16 0.74 2.24
INPUT
3.6
Materials
Lbs./cycle
.
3.6
142.0
a n d H e a t i n g Periods
Lbs./lOOO cu. fl. gas
H e a t of combustion In oil, 7.25 X 18,ao4 In lampblack burned out, 4.54 X 14,900 Sensible heat above 60' F.: In oil, (93 - 60) 1.35 X 7.25 In air for blow a n d heat Total heat in steam above 60' F., 4.32 X 1085 Total input
--
---
209,670
100.00
OUTPUT
Gas Lampblack in gas Tar Carbon deposited in generator Steam condensed from gas in wash box Residual gas after make Steam in residual gas after make HIS in gas Unaccounted for: Hydrogen Carbon Nitrogen
2490.0 831.0 160.0 277.6 1507.1 68.2 84.3 25.3
40.69 13.58 2.61 4.53 24.62 1.11 1.38 0.41
20.6 80.0 3.6
---
0.33 1.31 0.06
--
Total output
5547.7
90.63
2980.2 2333.0 207.8 26.7
48.69 38.12 3.39 0.44
INPUT
Oil for gas-making Steam for gas-making Residual gas after heat Steam in residual gas after heat Total input
-
-
5547.7
90.64
M a t -erials Lbs./1000 Lbs./cycle cu. fl. gas
Blowing a n d H e a t i n g Periods-Actual OUTPUT
Waste gases: From blow From heat, including residual gas from heat and 3.6 inches sulfur Unaccounted for Total output
5586.9
91.29
7657. 70.4
125. 1.26
---
13,314.3
217.55
444.0 12,176,O 264.2 152.5
7.25 198.95 4.32 2.49
INPUT
Oil for heat h r for blow a n d heat Steam Residual gas from make Lampblack deposited in producer during make a n d burned out during blow Total input
277.6 ____
4.54
13,314.3
217.55
Utilization of Heat Content of Waste Gases
The heat balance for the blowing and heating periods of the generator shows that 85,300 B. t. u. are lost as sensible heat in the waste gases for every 1000 cubic feet of gas manufactured. This corresponds to a loss of 5,220,000 B. t. u. per cycle of the generator, or 376,000,000 B. t. u. per 24 hours of operation. The temperature of these waste gases, given in the test data, varied from 784" to 797" C., or from 1452" to 1467" F. Assuming an efficiency of 50 per cent for a waste-heat boiler, the installation of such a unit would allow the recovery of 188,000,000 B. t. u. per 24 hours' operation on each generator. Economic Analysis of Lampblack Production
The heat balance for the complete generator cycle shows that 18.5 per cent of the output is in the lampblack separated from the manufactured gas, and 3.28 per cent in the tar. This lampblack and tar is utilized in the boiler plant for the production of the steam utilized in the generator, but cannot be fired so efficiently as oil. If it were possible t o operate the generator so that no lampblack would be deposited in the generator, the heat efficiency of the process could be increased. It is necessary, however, to calculate whether the economic efficiency of the process would be raised or lowered.
IATDUSTRIALAll-D ENGINEERING CHEXISTRY
February, 1929
The average yearly operation of the producer plant calls for the continuous operation of three generators and the additional operation of a fourth generator for 12 hours per day during 6 months of the year. Thus, three generators are in use three-fourths of the time and four generators, one-fourth of the time. When three generators are running, the average evaporation per day in the boilers is 30,000 cubic feet from feed water a t 170" F. to steam a t 90 pounds pressure. When four generators are running, the amount of lampblack produced increases proportionately, but the steam production only increases to 32,500 cubic feet. Since all the lampblack and tar are fired, some of the fuel must go to waste under these conditions. Table I11 shows the average operating data calculated from the test data and from the information given above, and the boiler efficiencies calculated from these data. Table 111-Calculation
of Boiler Efficiencies with Lampblack a n d
Tar a s Fuel 4 GENERATORS AVERAGE 3 GENERATORS Average gas production for plant, 13,410,000 17,900,000 14,530,000 cu. ft. per day Weight of lampblack burned, lbs. per hr. 7,580 10,106 8,211 Weight of tar burned, Ibs. per hr. 1,460 1,95i 1,584 H e a t from lampblack, B. t. u. per hr. Heat from tar. B. t. u. uer hr. Total heat from fuel, B. t. u. per hr. Evaporation, cu. ft. per day from water a t 170' F. t o steam a t 90 lbs. pressure H e a t content of steam above water a t l i O ° F . , B. t . u. per hr. Boiler efficiency, per cent
113,000,000 150,700,000 122,400,000 20,200,000 26,900,000 21,900,000 133,200,000 177,600,000 144,300,000 30,000
32,500
30,600
81,600,000 61.2
88,400,000 49.8
83,300,000 57.7
A boiler efficiency of 80 per cent may safely be assumed for oil-firing. On this basis there would be re24 = 134,950 pounds of oil per day. quired 83J300'000 18,551 X x 0.80 With oil a t $1.18 per barrel of 333 pounds, the daily cost of 134 950 oil for fuel would be 333 l.lg = $478.
A
The comparative cost of firing lampblack and tar as against firing oil is calculated and shown in Table IV, which gives the resultant equivalent value of lampblack and tar as fuel.
Table IV-Equivalent
109
Cost per Day of Lampblack a n d Tar as Fuel Compared with Oil
LAMPBLACK Fuel oil Firing expenses: 32 firemen a t $6.00 per day 3 firemen a t $6.25 per d a y 3 water tenders a t $6.25 per day 3 boiler cleaners a t $5.25 uer . day. Equivalent value of lampblack and t a r
OIL
.....
$478.00
$192.00
.....
.....
18.75 15.75 304 75
18.75 18.75 15.75
___
. . ---
$531 25
$531 25
From the value of $304.75 found in Table IV for the equivalent value of lampblack and tar per day as fuel, it follows that the value of the heat content of these materials 304 75 per million B. t. u.when used as fuel is 144.3 'x 21 = $0.088. The value of one million B. t. u. in manufactured gas, however, with gas worth $0.30 per 1000 cubic feet a t the genera0.30 tor, is o.579 = $0.518. The economic efficiency of the gasproducing process can therefore be materially increased, if it is possible to eliminate the production of lampblack and tar in the generator and put the heat now represented by their removal back into the manufactured gas, with the corresponding change to oil as fuel for the boiler plant of the producers. While it is possible to increase the economic return from the lampblack by briquetting it for sale, the value of the heat units in the lampblack will invariably be lower than the value of the same number of units in the gas, and the highest economic efficiency will result from complete gasification. The senior author has developed a modification of the Jones process2 in which lampblack is eliminated or greatly reduced by passing the gas from the primary through an intermediate shell before enriching it. In this intermediate shell sufficient heat is stored in the checker brick, and sufficient time is allowed for all the lampblack to react with the steam. Acknowledgment
Acknowledgment is due Willis S. Yard, vice president in charge of the gas department of the Pacific Gas and Electric Company, for advice relative to the practical aspects of gas-making. 2
Pike, U S. Patent 1,644,146.
Catalysts for the Formation of Alcohols from Carbon Monoxide and Hydrogen' 111-X-Ray Examination of Methanol Catalysts Composed of Copper and Zinc Per K. Frolich, R. L. Davidson, and M . R. Fenske DEPARTMENT OF CHEMICAL
I
ENGINEERING, MASSACHUSETTS INSTITUTE OF
N T H E experiments on the decomposition and synthesis
of methanol previously r e p ~ r t e d , ~the J catalysts composed of copper and zinc were prepared by precipitating the mixed hydrates from the corresponding nitrate solutions, dehydrating the gel, and subsequently reducing the oxides with methanol vapor a t the lowest temperature a t which reduction would possibly take place-i. e., about 200" to 220" C. Although zinc oxide is usually considered non-reducible at this temperature, it was, nevertheless, found to be partly reduced by the above treatment when present in mixture with copper oxide. Such reduction of zinc oxide has been reported Received August 10, 1928. Frolich, Fenske, and Quiggle, IND.END.CHEM.,20, 294 (1928). a Frolich, Fenske, Taylor, and Southwich, I b i d . , 20, 1327 (1928).
TECHNOLOGY, CAMBRIDGE,
in the patent literature4 as well as in a recent publication by R0gers.j The reduction manifested itself in the present catalyst mixtures by a somewhat greater loss in weight than that corresponding to reduction of the copper oxide alone. In a previous publication2 attention was called to the fact that the free-energy change in the reduction process varies somewhat depending upon the type of products formed from the methanol used for reduction. It was pointed out that the carbon dioxide concentration of the reducing gas mixture might build up to as high a value as 7 per cent according to the equilibrium:
1 2
MASS.
4
British Patent 273,030 (July 23, 1925). Chem. Soc., 49, 1432 (1927).
6J. Am.
