INDUSTRIAL
1080
ENGINEERING CHEMISTRY
since there is no visible dust whatever in the fan discharge. The temperature of the exhaust air from the filters was taken as 110" F. dry bulb, 94" F. wet bulb, compared with atmospheric conditions of 82" F. dry bulb and 71" F. wet bulb. On the basis of these figures the 1800 c. f. m. of vented air carry away 124 grains of moisture per cubic foot, or 191.3 pounds of moisture per hour, from the two mills. This is equivalent to removing as moisture 1.2 per cent of the weight of material ground.
5'01. 22, No. 10
The current consumption of the whole system is not over The only labor required is inspection and lubrication, and over a 6-month period the service has been negligible. The serious dust nuisance has been eliminated completely, which has both improved the appearance of the plant and increased the good will of the surrounding district. I n addition the 0.2 per cent recovery of product formerly lost has proved a distinct increment in the over-all efficiency of the plant. 15 horsepower hours.
The Cracking Process i n the Gas-Making Industry' Gustav Egloff and J. C. Morrell RESEARCH LABORATORIES, UNIVERSAL OIL PRODGCTS COMPANY, CHICAGO, ILL.
The cracking process produced more than 250 billion of tars from some gas-making cabic feet of cracked gas of approximately 1250 B. t. u. process, once considprocesses gives substantial per cubic foot during the year 1929. ered by the r e f i n e r yields of motor fuel in addition The gas from the cracking process is an enriching largely as a loss, is now octo high B. t. u. gas and coke. one suitable for blending with water gas and producer cupying a unique place among The cracking process opergas, and the coke produced is highly suitable for water petroleum products. More ated in conjunction with a gas or producer gas production. than 250 billion cubic feet of gas-making plant will produce The cracking process can be operated so as to produce cracked gas were produced gas from any hydrocarbon maximum yields of gas and minimum yields of gasoline, during 1929. This gas has material such as tars or oils. or maximum yields of gasoline and minimum producdistinctive properties, and is An economic balance can be tion of gas, dependent upon the market requirements. findine a market in enriching maintained as a function of gases Tor domestic and indug maximum yields of gasoline, trial use and as a raw material for chemical synthesis of such or gas production from the cracking process. This is dependent substances as alcohols and glycols and their derivatives. upon the peak demands of each commodity during the year. Table I shows the relative production of various kinds of The gas plant of the future will be a distributor of highgases, both natural and artificially produced. It is interest- antiknock motor fuels in addition to cracked gas. ing to note that the combined volume of gas from the peComposition of Cracking-Still Gases troleum stills and from the cracking process is greater than Gas from cracking stills is characterized by a relatively the entire manufactured-gas output of the country, and it is safe to predict that the production of gas from the cracking high content of olefins. These give it high illuminating values, and in addition make it a suitable material for the process will increase a t a rapid rate. preparation of chemical derivatives. The percentage of Table I-Production of Gas in 1929 hydrocarbon groups present in cracked gases varies widely Billoon cubic feef Natural gas" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1800 as a function of the charging stocks and temperatures and Gas from petroleum distillation. . . . . . . . . . . . . . . . . . . . . . . . . 270 pressures used.. By proper regulation of the cracking process Gas from the cracking process.. . . . . . . . . . . . . . . . . . . . . . . . . 250 255 Carbureted water gasb.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . the percentage of components present in the gas may be Oilgasb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 Manufactured gas, total (includes carbureted water gas, varied almost at will. Table I1 shows some approximate coal gas, oil gas, and coke-oven gas distributed by gas analyses of gas from the cracking process. companies) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514 U . S. Department of Commerce Table I11 shows typical analyses of a number of gases from b American Gas Association. the cracking process. I n less than two decades the cracking of heavy oils has Gas Produced from Cracking grown from a n incident in the oil industry to a major reThe amount of gas produced per barrel of charging stock finery operation. From practically zero production in 1912 cracked gasoline has gained in importance until it now repre- varies quite widely. Gas formation is particularly high sents one-third of the total of 17 billion gallons gasoline in non-residue operation when producing distillate and coke as the only other products. The gas production depends produced during 1929 in the United States. The cracking process is important to the gas industry. on the nature of the oil and the conditions of the cracking It will not only supply a substantial proportion of gas of operation, such as temperature, pressure, and time. I n high calorific value for enriching purposes, but will function Table V are shown the yields of gas produced by cracking also as a balance in cracking liquid products, such as gas different oils using the non-residue type of operation. tars and coal tars. Cracking plants located in refineries Flexibility of Cracking Process near populous .districts are already being utilized to enrich The primary use of the cracking process at the present gases of low fuel value. The gas from the cracking process with approximately 1250 B. t. u. per cubic foot permits the time is the conversion of petroleum into gasoline. No one enriching of gases, such as water, blast furnace, producer, method of operation will fit all the economic demands made and coke-oven gas. I n some communities the supply of upon the refining or gas industry. The process must be so gas consists of a mixture of coke-oven and producer gas flexible that oil of any type can be cracked into products in enriched with gas from the cracking process. The cracking greatest demand. This condition is fulfilled by the cracking process, whose adaptability is such that it may be operated Presented before the Division of Gas and 1 Received April 19, 1930. for maximum yields of gasoline, furnace or Diesel oil, residual Fuel Chemistry at the 79th Meeting of the American Chemical Society, oil, coke, and gas. The process may be operated so aa to Atlanta, Ga., April 7 to 11, 1930.
AS from the cracking
G
0
INDUSTRIAL A N D ENGINEERIXC: CHEMISTRY
October, 1930
Table 11-Analyses CHARGING STOCK
A . P. I 85.6
Midcontinent kerosene distillate North Texas kerosene distillate hiidcontinent fuel oil Midcontinent topped crude Ranger topped crude Healdton crude Montana topped crude Kentucky fuel Mexican distillate Mexican gas oil Panuco residuum (Mexico) Panuco residuum (Mexico) Panuco residuum (Mexico) Panuco residuum (Mexico! Panuco crude Panuco crude Venezuela fuel Venezeula fuel Tarnkan crude (Borneol Tarakan crude (Borneo)
38.4 39.5 26.9 98.9 26.8 29.6 38.4 25,s 26.3 21.0 9.7 9.7 9.7 9.7 12.6 12.6 13.4 13.4 18.2 18.2
of Gases f r o m Cracking Process COMPOSITION
GR.4vITY
hlidcontinent gas oil
1081
HzS
+ COz
Cdzn
co
0 2
%
'70
70
%
0 5
12 8
0.2
01
3.9
82.5
0.5
14.0 8 7 9 0 8 3 8 4 51 52 2 21 5 8 9 9 41 46 3 7 83 6 32 7 47 9 10 3 74 52 5 8
0.3
0.2 0.4
6.4 11.1 4.4 3.8 4.4 5.2 10.2 3.06
79.6 79.2 84.6 86.9 86.3 87.4 82.6 91.27 79.6 84.0 75.9 76.5 84.8 72.7 74.63 74.29 73.00 79.89 89.6 87.4
0.0
1.0 0.7 0.4 1.6 0.0 0.61 6.4 0.1 13.1 10.5 7.2 13.9 11.82 12.15 7.34 9.32 0.6
0.4
0.6
0.5
0.5 1.1 0.5 0.4
0.2 0.0
0.3 1.4 2.24 0.2 0.3 0.9 0.5 0.5
0.6 0.61
1.9 1.4 1.0 1.3 0.4
1.1
1.02 0.92 1.92 0.93
0.3 0.6
0.6
0.63 0.61 2.04 3.01 0.3 0.2
SP. GR.
CnH?n+z -I-Nz
H2
70
70
6.1
4.3 5.0 6.6 3.4 3.4 5.58 4.56 6.60 3.11 4.0 J .6
0.894 0.861 0.660
0.847 0.900 0.850 0.802 0.722 0.806 0.807 0.827 0.898 0.873 0.908 0.960 0 928 0.917 0.956 0.884 0.784 0 787
CALORIFIC VALUE B. t . U. per cu. ft. 11234 gas (mixed 1220) 11234 1395 1702b gas 1680b 1562 1427 1600b
...
1368 l6OOb 1265 1238 1326 1284 1302 1326 1264 1300 1317 1388
Gas from cracked distillate receiver. b Gas from cracked distillate separator.
0
produce maximum quantities of gas. Viscous oils may be used as charging stock and cracked but lightly in order to lower their viscosity and cold test so that they will flow readily through pipe lines. The manner in which the process is used will depend upon market conditions and the charging stock available for cracking. Various tars from coal, shales, lignite, peat, or wood may be used also for charging stocks. The operation may be controlled to produce maximum yields of any product desired without modification of the cracking unit in principle or equipment. Table 111-Analyses
%~.~%
$6
of Gases f r o m Cracking Process
%
%
%
%
%
%
%
%
Ethylene 0.6 1.9 2.2 2.5 2.7 4.0 4.7 6.3 27.0 28.0 32.4 11.7 0.8 15.2 5.0 7.6 6.8 6.1 12.0 16.0 19.0 16.8 Propylene 5.4 4.7 7.4 3 . 9 0 . 3 6 . 5 2.6 2.0 7.1 9 3 . . Butylenes .. ..0.2.. . . . . . . . . . . 1.1 Amylenes . . . . . . . . . . . . . . . 1.0 ~ . -0 . z Butadiene 0.u s.1 Higher olefins 3:o i:ci 2:o 3:o 5:o 5 : 6 i:7 i:o . . . . Hydrogen 80.0 88.0 77.7 . . . 80.281.6 81.4 72.9 40.0 . . . . Paraffins
:::
of M i d c o n t i n e n t Cracked Gas .Per cent Per cent Hydrogen.. . . . . . . . . . . . 2.9 Hexane . . . . . . . . . . . . . . . . . Trace Methane . . . . . . . . . . . . . . . . 64.5 Ethylene . . . . . . . . . . . . . . . . 2.9 Ethane.. . . . . . . . . . . . . . . . . 16.0 Propylene . . . . . . . . . . . . . . . 1.9 Propane.. . . . . . . . . . . . . . . . 6.7 Butylenes . . . . . . . . . . . . . . . 1.3 Butanes. . . . . . . . . . . . . . . . . . 2.9 Higher unsaturates.. . . . . . Trace Pentanes . . . . . . . . . . . . . Trace Hydrogen sulfide and carTable IV-Analysis
A detailed analysis of gas from the cracking of a Midcontinent fuel oil is also shown in Table IV. The residual oil method of operation of the cracking process may be carried out continuously for a period of thirty days or more, producing high yields of gasoline, a fuel-oil residue passing all market specifications, and an insignificant amount of coke, the amount of coke produced per barrel of charging stock ranging from a trace to a few pounds. The volume of gas produced may be 800 cubic feet per barrel more or less, as desired. The cracking operation may also be so controlled that only cracked gasoline, coke, and gas are produced: This mode of operat'ion produces the maximum yield of gasoline, gas, and coke. The gas production may exceed 1200 cubic feet per barrel of oil cracked. With high-temperature operation of the cracking process the amount of gas per barrel of oil will be over 2000 cubic feet while making high yields of gasoline. The operation may also be varied to crack overhead products of the process of intermediate boiling range such as reflux condensate in a separate heating element. This will permit higher temperatures and increased gas yields. Other changes in the arrangement of the process may also be made to meet requirements.
Table V-Gas
Production i n Cracking Representative Oils
FURNACE
SOURCE OF OIL
GRAVITY GAS
MOTOROR DIESEL FUEL OIL COKE
cu.
yo
' A . P.I . f t . / b b l . a FUEL
Panhandle, "ex. Caddo-Bull Bayou, La. Midcontinent Muskegon, Mich. Rosecranz, Calif. California Eastfield Ark. North d x a s Wyoming Oregon Basin, Wyo. Kentucky Pondera, Mont. Ventura, Calif. McCamey, Tex. Alamitos, Calif. California California Texas
29.5 28.6 27.4 26.1 26.7 25.6 23.6 22.7 22.4 22.2 22.0 21.1 20.1 19.9 19.5 17.2 16.7 8.9
Pennsylvania California Eldorado, Ark. California Texas California
38.8 38.6 34.7 33.7 27.3 23.2
Lbs./bbl
OILS
425 388 517 620 517 670 476 499 576 700 640 865 368 624 698 855 637 427
65.5 67.8 61.2 60.1 58.0 61.2 60.9 61.6 59.8 56.6 60.8 49.3 07.2 59.1 42.7 48.8 48.2 30.6
11.4 12.2 17.9 16.5 21.2 17.3 15.5 12 5 9.9 11.6 14.6 15 0 15.8 13 5 85 15 9 14.6 3.2
43
71.9 64.8 60.7 47.1 48.6 56.4
6.8 16.8 21.5 38.9 32.2 13.9
24.8 12.9 30.0 14.7 29.3 33.6
58.8 61.7 46.3 52.1 45.2
16.5
21.3 21.3 19.7 21.3
43 21 86 42 73
28
41 77 38 44 53 31 60
77 48 72 33 63 62 89 103 138
G A S OILS
570 350 255 250 330 628
CRUDE OILS
22.5 Nacome, "ex. 17.9 Cole Bruni, Tex. 15.4 Posecreek, Calif. 15.4 Maricopa Flats, Calif. 13.7 Maricopa Flats, Calif. a 42 gallons per barrel.
644 608 838 785 874
The accompanying photograph shows the arrangement of a modern cracking plant. Uses of Cracking-Process Gas
At present the major use of gas from the cracking process is for refinery fuel. However, several city gas companies are purchasing cracked gas from refineries for enriching purposes. The gas has a n average calorific value of 1250 B. t. u. per cubic foot when stripped of gasoline, and some values are as high as 1600 B. t. u. per cubic foot. The extent to which gas from cracking surpasses other commercial gases in heating value is shown in Table VI. Table VI-Approximate
Calorific Values of Various C o m m e r c i a l Gases
B. t.
U.
+er cu. j l .
Cracking-still gas. . . . . . . . . . . . . . . . . . . . . . . . . . 1260 Natural g a s . , . . . . . . . . . . . . . . . . . . . . . . . . . 1000 Crude-oil distillation gas. . . . . . . . . . . . . . . . . . . . 1000 Carbureted water g a s . . . . . . . . . . . . . . . . . . . . . 550 Coke-oven g a s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 550 Water gas (blue gas). . . . . . . . . . . . . . . . . . . . . . . . . 310 140 Producer gas from coal or c o k e . . . . . . . . . . . . . . . . . . Blast-furnace gas. ............................. 100
INDUSTRIAL A S D E.YGISEERING CHEMISTRY
1082
Vol. 2 2 , s o . 10
Gas from Cracking of Low-Temperature Coal Tars
Cracking of Tar Acids from Low-Temperature Coal Tar
There are projects now under way in which the gas obtained from low-temperature carbonization is being blended with water gas and distributed by public utility companies for domestic use. This gas has a calorific value of approxiinately 850 B. t. u. per cubic foot. One low-temperature carbonization plant is in commercial operation with an approximate capacity of 600 tons per day.
The tar acids produced by lowtemperature carbonization have been converted by the cracking process into lower boiling tar acids useful as disinfectants, antiseptics, mood preservatives, and for the manufacture of resins froin the condensation of phenols and aldehydes. When tar acids separated from low-temperature coal t a r were cracked, approximately 1000 cubic feet of gas per barrel
Modern Cracking P l a n t
It is estimated that there are 3154 billion tons of bituminous coal in the world, of which the United States has approximately 1600 billion tons, By means of low-temperature distillation of this quantity of bituminous coal, 960 billion barrels of tar can be produced which under cracking conditions will yield approximately 240 billion barrels of motor fuel of high antiknock properties. The motor fuel produced from low-temperature carbonization and cracking, when operating a high-compression motor, will give more than double the mileage per gallon compared with ordinary gasoline using present-day motors. The superior quality of this type of motor fuel is due to the high percentage of aromatic and unsaturated hydrocarbons contained therein. The amount of gas that would be available by low-temperature carbonization of the total bituminous coals in the United States is 9,600,000 billion cubic feet. The amount of gas from cracking the tar derived from the coal would approxitnate 480,000 billion cubic feet, and this could be increased a t the expense of motor fuel if so desired. Table T'II shows the production of gas and other products froin the cracking of coal-tar and related oils. Table VII-Cracking
OF
Low-temperature carbonization Straight-distillation acid oil from l o w - t e m p e r a t u r e carbonization Intermediate-temperature carbonization Kentucky High-temperature cannel coal tar Lignite t a r Lignite digtillate Brown-coal t a r
of Coal-Tar a n d Related Oils FURNACE
GRAVITY
MOTOR OR DIESEL FUEL OIL COKE
GAS
70
c/o
Lbs./bbz.
8.9
570
28.8
10.3
...
9.9 6.0
485
26.3 14.5
28.9 17.7
241
... 18.1 ...
.A. P. I . Cu.f t . / b b l .
500
2?y
it;
:E:
13.9 21.1 9.2
767
38.3
672 835
.
46.7 28.6
73
iii &
241
of charge were obtained. The use of approximately 15'to 20 per cent of water or steam during the cracking operation produced approximately 1900 cubic feet of gas per barrel. The gas when no water or steam were present had the following composition: Pev cent Carbon monoxide . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Carbon dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 Unsaturated hydrocarbons. . . . . . . . . . . . . . . . . . . . 1 . 2 Paraffin hydrocarbons. . . . . . . . . . . . . . . . . . . . . . . . 30.6 . . . . . . . . . . . . . . 39.2 Hydrogen. . . . . . . . . . . . . . . . . Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0
The use of water and steam in conjunction with the operation, while producing practically double the gas, had very little observable effect upon the compxition of the gas. The coke formation and yield of neutral oils were also increased. The over-all results in the use of steam in the cracking of tar acids or low-temperature coal tars containing them is a large increase in gas formation, some increase in coke formation, and an increase in the forination of neutral oils-all a t the expense of tar acids. =inother important factor having a direct bearing upon the cracking process is the creosote-oil problem caused by the increasing-use of low-temperature carbonization processes and gas retorts which produce similar tars. The content of creosote oils in these tars meeting present specifications for wood preserving is much lower than that present in ordinary coal tars. The chief reason for this difference in gas tars is the use of steam in the vertical ovens and the withdrawal of the tar from relatively low-temperature zones. The present creosote-oil requirement of the United States is approximately 200 million gallons, of which 50 per cent is imported from abroad. Approximately 500 million gallons of coal tar, sufficient to supply the total requirements of creosote oil of the United States, are produced in this country.
INDUSTRIAL A N D EXGINEERIXG CHEMISTRY
Octoher. 19.30
The problem are, of course, niore acute in Europe because they are directly affected by both angles. The solution of this problem lies in the cracking of the low-temperature coal tar and similar gas tars directly or in the cracking of the straight distillates or neutral oils obtained therefrom. The straight distillates may be extracted to remove any portion of tar acids desired for other purposes-e. g., the tar acid. may be blended with petroleum products to make excellent wood preservatives. Cracking of Gas Tars The cracking of water-gas tars produces a relatively low yield of high-antiknock motor fuel, but a fair volume of gas is made as well as a high yield of coke. The coke, owing to its characteristic porous structure and low ash content, is especially suitable for gas making, either for mater gas or producer gas. Tar from vertical gas retorts which utilize steam, such as the Glover West retort, has properties both chemical and physical wnilar to low-temperature coal tar, and the results from cracking approach those obtained in the cracking of low-temperature coal tar-i. e., approximately 22 per cent of high-antiknock motor fuel and 600 cubic feet of gas per barrel of charge. Similar tars have been produced from modified Koppers coke ovens. Apparently the use of steam in the retorts and the withdrawal of the tar from relatively low-temperature zones gives to the tars properties and characteristics of the lowtemperature type, making them highly suitable for cracking for the production of both gas and gasoline. Tar from Glover West Retort The analysis of the tar from Chilean coal proressed in a Glover W e d vertical gas retort and the results obtained on cracking follow: Specific g r a v i t y . , . . . . . . . . . . . . . . . . . . . . . ....... 1.0&97 Initial boiline ooint t o end uoint foil and water). 210" to 705' F. F l a i h ~ p o i n trcleveland ope; cup) . . . . . . . . . . . . . 1603 F. Fire point(Cleve1and open cup). . . . . . . . .. . . . . . . 215' F. 146' F. Flash point (Pensky Marten). . . . . . . . . .. . . . Furol viscosity a t 122' F.. . . . . . . . . . . 20 seconds Cold test . . . . . . . . . . . . . . . . . . . . . . . . . . . +65' F. 4.2 qc B S. & K '. (benzene centrifuge).. . . . . . 5' T n'ater (.4. S.T.M.).. . . . . . . . . . . . . . 2.4
:
OVER P e r cenl 5
10 20 30
40 50 60 70 80 E n d point
TEMPERATURE F. 340 406 464 520 58.5
639 669 io5 Superheated io5
Over 410' F 437' F 572' F Water Coke by weight
Per cent 85 0 0 0 5 9
Table VI11 summarizes the yield of unrefined products made by cracking coal-gas tar. T a b l e VIII--Yield of Unrefined P r o d u c t s (Based on coal-gas tar) MOTORFUELENDPOINT 392" F. 400' F. 437' F. Per cent Per cent Per cent 4 7 4.7 4.7 9.6 9.6 9.6 2.3 2.3 2 3 6.0 6.0 6.0 naphthalene) Pressure-distillate bottoms (free from tar acid, t a r baqe, and naphthalene) Coke and pas. including loss Redistillation loss Total
Specific gravity.. . . . . . . . . . . . . . . . . . . . . . . . . Carbon dioxide.. . . . . . . . . . . . . . . . . . . . . . . Unsaturated hvdrocarhons.. . . . . . . . . . . . . Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hydrogen. . . . . . . . . . . . . . . . . Carbon monoxide. . . . . . . . . . . Paraffin hydrocarbons . . . . . . . . . . . . Sitrogen (by difference). . . . . . . . . . . Total
11.8
12.4
15.7 49.7 0.2
15.1 49.7
49.7
0.2
0.2
100 0
100 0
18.0
0.8173
. . . . .. .
P e r cent 2.1
5.6 2.1 11.3 0.8 . . 65.9 . . 12.2 100.0
Tars quite similar to low-temperature coal tars have been produced from modified Koppers coke ovens. Apparently the use of steam in the retorts and the withdrawal of the tar from relatively lowtemperature zones gives to the tars properties and characteristics of the low-temperature type, making them highly suitable for cracking for the production of both gas and gasoline. The use of steam during the cracking process should greatly increase the yields of gas in accordance with the reactions shown with tar acids. Water Gas and Producer Gas from Petroleum Coke The most extensively manufactured gas is blue gas. sometimes called water gas, according to the following reaction: C
+ HzO = CO +
H2
The physical properties of coke from the cracking process make it an ideal raw material for the manufacture of blue gas. This coke has an apparent density of 0.9 to 1.1; a cellular and firm structure exposing maximum area to reaction with the steam; and contains from 5 to 15 per cent of volatile matter, from 80 to 90 per cent of fixed carbon, and 0.1 to 1.5 per cent of ash. The heating value is approximately 15,500 B. t. u. per pound, with a sulfur content depending upon the source of the oil from which it is produced. For example, from a Pennsylvania or Midcontinent oil the sulfur content will be usually less than 1 per cent, while from a Mexican or California oil it will vary from 1 to 5 per cent depending upon the kind of oil. The utilization of coke from the cracking process for the manufacture of blue gas and the carburetion of this gas by gas from the cracking process is a practical and economic basis of manufacture. Coke from the cracking process can also be used for making producer gas, which has for its basis the following reaction: 2c
S O
13 36 2 15
1083
+
0 2
=
2co
Some tests mere made upon coke of the following composition and calorific value: Per cent Moisture.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . 9 7 . . . . . . . . . . . . 9.35 Volatile m a t t e r . . Fixed carbon. . . . . . . . . . . . . . . . . 8 9 . 0 1 . . . . . . . . . . . . 0.67 Ash. . . . . . . . . . . 13. t. u. per p o u n l . . . . . . . . . . . . . . . . . . . . . 16,042
The composition of the gas produced was as follows: Carbon dioxide.. Unsaturates.. . . Oxygen. Hydrogen Carbon monoxide Methane Ethane Nitrogen
........................ . .
. . . . . . . . . . . . .
Per Lent 5.25 0.27 3.23 13.40 22.40 0 48 0 33 54 64
9.5
10:
0
The products shown in this table were made without recycling any pressure-distillate bottoms. Additional gasoline may be obtained by recycling the bottoms. From each barrel of coal-gas tar cracked, 144 pounds of coke and 823 cubic feet of gas were produced. The unscrubbed gas had the following composition:
The gas had an average calorific value of 144 B. t. u. per cubic foot. The clinkerous slag was removed through a water seal a t the bottom of the producer. The over-all hot gas efficiency of the process was between 90 and 94 per cent. By operating the cracking process to produce coke and gas as the major products and by gasification of the coke in the manner described, the process will be chiefly a gasmaking one.
