October, 1924
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
average for all automobiles. It is quite possible that certain engines whose carburetors are adjusted for a rich mixture will give off as much as 50 per cent more carbon monoxide, especially in starting during cold weather. With these the concentrations and effects described above would be produced in a great deal less time. An amelioration of this condition in the form of a vertical exhaust pipe extending a few inches above the tap line has been suggested by Henderson.6 Further, in practice the gas will not be evenly distributed throughout the garage, there being a lag in the dilution, and a much
1049
higher concentration will be present in the vicinity of the exhaust outlet. The time necessary to render a man unconscious will be further dependent upon the amount of exercise. The limitations described were made on the basis of moderate activity, whereas, should the occupant be doing strenuous work, his respiration would be increased and he would absorb a great deal more carbonmonoxideina giventime;hisneedforoxygenwould likewise increase with exercise. Both of these factors tend to decrease the time necessary to produce serious symptoms.
Economy through Smoke Abatement’ By H. B. Meller’ MELLONINSTITUTE OF INDUSTRIAL RESEARCH, PITTSBURGH, PA.
i
UCH antismoke agitation has taken place in the United States during the past ten or twelve years. Surveys have been made and ordinances passed. The net result has been a decided decrease in the amount of dense smoke in city air, without a corresponding abatement of the dirt and acid evils. In 1912-13 Mellon Institute of Industrial Research of the University of Pittsburgh made a survey of the City of Pittsburgh to determine the amount of “soot fall,” its effects, and possible methods of minimizing it. The results were published in nine bulletins. Data have been collected in Great Britain since 1914, under the auspices of the Advisory Committee on Atmospheric Pollution, attached to the Meteorological Office. “Soot-fall” studies were made in St. Louis, Cincinnati, and Pittsburgh in 1916, and Mellon Institute has just completed an eleven months’ survey of Pittsburgh. In all these investigations all solid matter that was deposited was considered, while in legislative action, taken with a view toward abatement, dense smoke only has been prohibited. Excellent results have been attained in combating this nuisance, but dense smoke is responsible for only a small percentage of the precipitate.
manufacturers would be given a reasonable time t o meet. There is now a tendency toward this restriction and manufacturers are showing a commendable willingness t o cooperate. 2-Permit is required beEore any work of installation, repair, or alteration of fuel-burning apparatus. From August 5, 1914, t o July I , 1924, the Bureau of Smoke Regulation of the City oi Pittsburgh issued 1695 permits under t h e ordinance. All new installations, of course, were required to be such as could be operated within the limits set. The person charged with the enforcement of an antismoke ordinance is therefore in a position t o assure himself t h a t plants are so designed and constructed t h a t reasonable care will prevent violation. 3-Penalty for violation. 4-In Pittsburgh and in some other cities private dwellings and t h e smaller apartment houses are exempt. The reason for this exemption in Pittsburgh was that, a t the time the ordinance was adopted in 1914, the customary domestic fuel was natural gas. The diminishing supply of this fuel has caused many t o change t o bituminous coal in t h e last few years.
When fuel is fired, the moisture is driven off first, then the volatile constituents. If the fuel is high-volatile bituminous coal, this expulsion may amount to 35 or 40 per cent by weight of the total; and if, as in hand-fired furnaces, the injection of fuel is intermittent, large volumes of volatile matter are distilled off in a very short space of time. It is during this period of distillation that dense smoke usually is emitted. PRESENT-DAY CONDITIONS RESPECTING SMOKE ABATEMENTIf the furnace temperature is sufficiently high and a sufficient volume of oxygen is present, the volatile matter will be burned A statement of the salient points in the antismoke ordi- above the fuel bed. The fixed carbon is then burned. nance of Pittsburgh and a brief description of the methods For complete combustion it is necessary that a sufficient used to minimize dense smoke will be pertinent in considering temperature be maintained in the furnace, that the furnace present-day conditions. have sufficient volume to permit the gases to be held long enough for completion of combustion, and that there be 1-Smoke of No. 3 density, Ringlemann chart (60 per cent black) for 2 minutes or more (aggregate) in any period of 15 proper provision for the admission of a sufficient volume of minutes, except in t h e case of locomotives or steamboats, where air, the internal construction being such that the gases from t h e allowable period is 1 minute in 8 minutes, is prohibited. No. the fuel will be thoroughly mixed with the air provided. I t 3 on t h e I2inglemann chart is equivalent t o smoke of such density is obvious that in hand-fired furnaces the volume shall be t h a t it is not possible t o see through it at the point of emission from the stack. Smoke of less density t h a n this is permissible adequate for the distillation period. It is necessary, also, at all times. that provision be made for the large proportion of air necesIt may seem t h a t this provision is too lenient, in t h a t it permits t h e production and emission of a n y quantity of light smoke sary during this period. In a large percentage of the plants in existence a t the time and a considerable volume of dense smoke; but, because of t h e present state of development of fuel-burning devices, it really of the passage of Pittsburgh’s antismoke ordinance in 1914, is fair. The fault has been t h a t t h e comparatively small number one or more of these necessary factors were missing. A of persons engaged actively in t h e work of smoke abatement have been more or less constrained t o follow t h e lead of the manu- number of methods, most of them quite simple, were used to make it possible to operate these plants within the limits facturers, tightening u p o n requirements as improvements were made in design, rather than t o set a high standard which t h e set by the ordinance. It should be remembered that only dense smoke was prohibited and that no attempt was made 1 Received August 1, 1924. to regulate by legal procedure the emission of any solid ma2 Chief, Bureau of Smoke Regulation, Department of Public Health terial that would not color the issuing stream. o f the City of Pittsburgh; and president of the Smoke Prevention AssociaIn cases where boilers were operated a t more than 50 pounds tion. Formerly Senior Industrial Fellow of Mellon Institute of Industrial Research, in charge of Air-Pollution Investigation. steam pressure, and where the supply of air was insufficient
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vel. 16, No. 10
INDUUSTRIAL A N D E N G I N E E R I N G CHEik?ISTRY
During the recent survey in Pittsburgh, data were secured from check stations in various sections of the city; the weights of the deposits showed considerable variation even where the points were not more than a block or two apart. It is impossible to get away entirely from the influence of stacks that are near the stations. It was found, too, that a container placed 15 or 20 feet above the roof collected less material than one placed on the roof. The regular stations that are reported were all on roofs, in order to obtain as direct a comparison with 1912-13 as possible. Wind velocity
for proper combustion, steam-air siphons were recommended. Where the pressure was less than that required to operate satisfactorily the steam jets, other means, such as larger openings in the fire doors or air ports in the sides of the furnace, were necessary. Settings were increased in height to provide greater volume of combustion space, and mixing piers or other provision for mixing the gases with air were insisted upon. Firemen were taught that, with furnaces fired by hand, approximately one-half the air necessary for combustion must be admitted over the fire; they were also
No. of stations averaged
PERIOD
CITY
August to June,
1923-24
Pittsh'lrgh
TABLE I ,--INSOLUBLEMATTER,TONS(2000 Lss.)
PER SQUARE MILE-
Tar
Combustible other than tax
Ash
Fez03
Total
2.87
464.3
557,3
279.9
1304.4
12
9.22
288,3
402.7
237.6
937.8
7
3.54
56.6
134.4
...
194.6
7
3.37
59.8
116.8
...
180,O
12
{August to June,
1912-13 August to June Average of 5 years August to June,
London
1922-23
and wind direction also influence the amount of material deposited a t a particular station. Consequently, while the figures in the accompanying tables can be accepted as indicating whether there is much or little dirt, they are not absolute measures. Table I shows the average of the twelve stations for the period August, 1923, to June, 1924, inclusive, and comparison with the corresponding period of 1912-13 for Pittsburgh, 1922-23 for London, and an average of five years for London. These figures include only the material insoluble in water. The water-soluble matter was not determined in 1912-13, nor was it found for August to December, 1923. Table I1 is a comparison of January to June, 1924, with the corresponding period of 1922-23, and an average of five years RESULTSOF INVESTIGATION OF SMOKE AND DUST PROBLEM for London. It includes both soluble and insoluble matter. OF PITTSBURGH Table I11 compares Pittsburgh in 1923-24 with Pittsburgh in 1912 and 1916, St. Louis in 1916, and Cincinnati in 1916, Beginning August 1,1923, and continuing to June 30,1924, for the months of April, May, June, July, August, and SepMellon Institute conducted an investigation to determine the tember. It is to be regretted that more complete data are improvement effected since 1913. Copper containers, ap- not available for other cities. Use has been made, however, proximately 4 inches in diameter by 10 inches high, were of all results that were obtainable. placed on stations in twelve sections of the city, each being I n London, where data have been gathered since 1914, in or very near the same location as the container used in little improvement is shown. In Pittsburgh the amount of taught the proper use of a damper. I n a great many cases chimney heights were increased. I n such simple ways as these a large number of stacks that had been persistent offenders were brought within the limits prescribed by the ordinance. The most efficient method of feeding fuel is in a continuous stream. The distillation of the volatile matter and the oxidation of the fixed carbon then proceed evenly and regularly. With coal, except it is pulverized, this is accomplished with the automatic stoker, which is required on larger furnaces. With pulverized coal, oil, or gas, regular feed and thorough mixture are possible. I n such cases it is necessary to see that the furnace volume is sufficient and that the necessary draft is provided.
CITY Pittsburgh London London
PSRIOD January to June,
1024
January t o June Average of 5 years January to June,
1022-23
--INSOI.UBI,EMATTER-Combustible other than Tar tar Ash
----SOL,UB&E
Loss
MATTER---
on ignition
Ash
Total solids
INCLUDED I N SOLUBl,Z M A T T S R
Sulfates as SOa
CI
NHs
1.91
251.2
471.2a
50.7
88.8
863.8
53.49
9.98
3.49
1.98
32.4
77.7
30.7
55.3
198.1
29.93
10.56
1.84
1.97
34.1
71.2
20.9
47.2
175.3
17.51
10.6b
1.81
a Includes FetOa.
1912-13. These vessels were changed monthly, and the deposits were weighed and analyzed for tar, combustible other than tar, ash, and ferric oxide in the insoluble matter, and for combustible, ash, sulfates, chlorides, and ammonia in the soluble matter. The results are compared with those of 1912-13 and with the findings in London between 1914 and 1923.3 8 This comparison is made because of the completeness of the data reported for London and because similar procedures of collecting deposits were used in both cities. Otherwise the comparison is unfair to Pittsburgh, which is an industrial city that is confronted with more serious sources of air pollution than are encountered in London. I t is unfortunate that similar data are not available for Sheffield or other English manufacturing centers. It is said that in Duisburg, Germany, the depositst otal 1200 tons per square mile per year. It has been learned since this article was written that the deposit in the center of Liverpool amounted to 97 tons per square mile for the month of June, 1924. The average of the twelve stations in Pittsburgh for the month of June was 89.7 tons per square mile.
tar has decreased materially, while the combustible other than tar and also ash have increased. This increase in solid matter deposited is due partly to an increase in the number of stacks, but mainly, it is believed, to the fact that legislation has attempted to control only dense smoke. If tar is taken as the criterion of dense smoke-and it is thought this is a fair measure-it will be seen that Pittsburgh has been successful in enforcing the antismoke ordinance. However, the very means taken t o eliminate dense smoke by increasing the draft in a large percentage of cases have resulted in increasing the amount of solid material emitted from stacks, as greater draft means higher velocities and the carrying of more and larger solid particles into the atmosphere. How much of the deposited solid material was not originally in fuel but came from sources other than stacks, is not
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INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1924
1051
TABLE111 No. of
CITY Pittsburgh
a
b c
St. Louis Cincinnati Average for 10 stations. Average for 8 stations. Average for 15 stations.
Year
i
1916 1916 1916
stations averaged 12 12 12 12 16
-,--TONS April 115.6 98.7 109.80 59.6 52.0
known as yet. Chicago, however, has estimated that 40 per cent of her deposit is composed of such material. It is believed that the percentage would be equally as high in Pittsburgh. One needs only to walk through some of the large plants to see and feel the amount of loose solid material that is being taken u p into the air, carried a short distance, and again deposited. Moreover, while the regulations are enforced for locomotives, it is true that the locomotive of today, with its so-called “self-cleaning front end,” which forces through the short stack practically all the solid material which reaches that front end, is responsible for much dirt and obnoxious gas in the vicinity of the railroads.
O P INSOLUBLE MATTER PER SQUARE MILEPER MONTH-May June July August September 111.7 67.2 ... 95.4 90.9 75.2 92.2 93.0 67.9 66.6 212 5b 147.6 167.7 219.00 167.6 58.9 42.4 66.5 55.7 50.2 50.2 33.6~ 49.2 33.9
...
In such a short article it is not possible to present an analysis of the data. It is clear, however, that, while results have been brought together that show enormous deposits of solid material in large cities, legislation thus far has been directed toward the abatement of dense smoke only, which represents a very small proportion of the nuisance. Surely the, time has come when remedial action should be taken. This problem merits the early attention of the Smoke Prevention Association, which could work advantageously in cooperation with such organizations as the American Chemical Society, American Institute of Mining and Metallurgical Engineers, and American Public Health Association.
Chinese Wood Oil’ By F. H.Rhodes and T. T. Ling CORNELL UNIVERSITY, ITHACA, N. IT.
HIKESE wood oil, also known as tung oil, is derived long, flattened and depressed a t the summit with irregular Erom the seeds of a tree belonging to the genus ridges. It is also much smaller and more fragile than in the Euphorbicae. I n China there are found two species: two former species. The fleshy part of the fruit is thin, soft, Aleurites fordii or tung-yu shu, literally, ((tung oil tree;” and fibrous, and incloses three to five smooth, compressed and Aleurites montana or mu-yu shu, literally, “wood oil seeds. tree.” I n Japan a third species occurs, Aleurites cordata CULTIVATION OF TREES or aburn kiri. These three species were formerly confused by the botanists. It was not until 1906 that Hemsley2 There are several methods by which Chinese wood oil first clearly defined Aleurites fordii. The other two species trees are cultivated. One method is to sow the seeds early were described by Lamark3 under the name of Dryanda oleifera. Most of his description refers to montana. Finally, in the spring, two in a spot of from 3 to 5 feet in diameter. Wilson,*l in 1913, showed that there are three varieties of The spots are cleared of grass and the soil is kept in loose Aleurites and pointed out the differences between them. condition for the retention of moisture. When both seeds The three distinct species are now definitely recognized by the germinate the stronger one is selected for growth. The seeds are sometimes sown in boxes or garden beds and when botanists. the shoots are about a foot high they are transplanted to These three species can be easily distinguished from one another by the ways in which the flowers are borne and by prepared spots on the hillsides. The roots are kept moist characteristic features of their fruits. I n Aleurites fordii until growth is well started. Sometimes trees are grown the flowers are borne before t.he leaves unfold, a t the end of from sprouts. Twigs from a grown tree are set in any kind the previous shoots. The fruit is apple-like, green passing of sandy or clayey soil and surrounded by wheat grains, to dull brown when ripe, flattened-round, with a short point watered plentifully, and allowed to grow for one year. The at the summit, and perfectly smooth on the outside. The shoot is then cut off above the ground. A larger sprout fibrous “flesh” incloses three to five compressed, broadly starts from the root and grows very rapidly-sometimes obovoid. seeds, which are very slightly ridged and warty. attaining a height of 10 feet in one season-and in about In Aleurites montana the flowers are borne after the leaves five years grows to a handsome shade tree. Most of the are fully expanded, on the shoots of the current season’s Chinese tung trees are grown from seed, since this method is growth. The fruit is egg-shaped, pointed a t the summit surer and less laborious. Tung trees are never grafted in and flattened a t the base, with uneven ridges on the outside. China. The age at which the tree begins to bear depends largely The interior of the fruit is thick and woody and usually incloses three compressed, broadly obovoid seeds. I n Aleurites upon the richness of the soil and the amount of moisture cordata the flowers are borne in branched, crest cymose received the first year after planting. I n some localities the panicles and are smaller than those of Aleurites montana. fruits are produced in three years, but usually from four to The leaves on the flowering branches are often three-lobed. six years are required. The tree then continues to bear for The fruit is somewhat turbinate and trigonous, wider than about ten years and if properly attended would undoubtedly retain its productive power for a longer period. * Received September 5, 1924. The tung tree grows rather rapidly. Normally it attains ZHooker’s Icon., 29, 2801, 2802 (1906). a height of about 20 feet and a diameter of from 7 to 10 8 “Encyclopedia of Methodical Botany,” Vol. 11, p. 329 (1786). inches, although trees larger than this have been reported. Buil. I m p . I n s t . , 11, No. 3 (1913).
C
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