Dispersion of Gases from Tall Stacks MOYER D. THOMAS, GEORGE R. HILL, AND JOHN N. ABERSOLD American Smelting and Refining Company, Salt Lake City, Utah
4#
The theoretical equations of Bosanquet and Pearson and Sutton for the dispersion of smoke from factory chimneys have been solved in terms of the conventional units of the smelting industry for the elimination of sulfur dioxide from four smelters. A large mass of field data for sulfur dioxide in the atmosphere, obtained by means of automatic recorders, has been evaluated in the form of Cu to M ratios, where Cis the field concentration, M is the mass emission of sulfur from the plant, and ~1is the wind velocity. The data for tall stacks at Selby, Calif., Tacoma, Wash., Garfield, Utah, and El Paso, Tex., agree well with the theoretical equations, when values of the diffusion
coefficients of 0.05 to 0.07 are used and the exponent of the distance, x, in Sutton’s equation is 2 ( n = 0). A somewhat smaller exponent may be needed to satisfy the data for the short stacks at Selby and El Paso. The theoretical curves and confirming data illustrate forcefully the beneficial effects of use of tall stacks in dispersing air contaminants from factories. Maximum ground concentration varies inversely ,with square of stack height. This results in lower peak and lower average concentrations from the tall stack and higher percentages of time when air is free of contamination. High temperature of smoke elimination increases effective stack height and improves dispersion.
I
concentrations from values in the line of propagation of the stream, and the final integrated equation is a form of the wellknown probability integral. Considering a single chimney of height, h (cm.), emitting M grams per second of a gaseous substance-for example, sulfur dioxide (or even an aerosol of particle size so small that the settling rate is negligible)-Bosanquet and Pearson give the concentration, C (grams per cc.), a t any point on the ground a distance, x (cm.), downwind from the chimney, and a distance, y (cm.), crosswind from the center line of the smoke stream:
N A previous paper (6) it was shown that high stacks and hot
gases a t Murray, Utah, and Selby, Calif., furnished an effective and practicable solution for smoke problems which had previously existed when the gases were emitted through low stacks and a t lower temperatures. It was suggested that qualitatively a t least, the data were in accord with the theoretical equations of Bosanquet and Pearson for the spread of smoke and gases from chimneys ( 2 ) . A large mass of field sulfur dioxide concentration data, obtained by means of continuous automatic air analyzers, is considered here in relation not only to the Bosanquet-Pearson equations but also to the mathematical treatment of Sutton (IO) which is based on the investigations of the British Chemical Defence Experimental Station a t Porton, England. Discussion is confined largely to the implications of these theories and t o the extent of agreement with the authors’ observations. These equations point the way t o effective pollution control in many industries. It is important to know how they may be expected to work out in practical application. In 1936, Bosanquet and Pearson (2)presented to the Faraday Society theoretical solutions of the problem of the dispersion of smoke from a single chimney (a point source) or from a row of chimneys (a line source), and in 1947 Sutton (IO) published his treatment of “The Theoretical Distribution of Air-Borne Pollution from Factory Chimneys.” Their equations are based on the idea that as the smoke stream proceeds, it fans out both horizontally and vertically, forming a cone of dispersed smoke. Dispersion occurs principally by eddy diffusion. At a certain minimum distance from the source, the edge of the cone strikes the ground, and thereafter the stream is said by Sutton to be reflected from the ground (assuming no absorption by or deposition on the ground itself) so that thereafter vertical dispersion is principally in one direction only. Proceeding downwind from this point, the ground Concentration increases rapidly because the vertical gradient across the cone is much greater than the downwind gradient. Soon a maximum ground concentration is reached, followed by a slow decrease, a t first, which gradually accelerates until the concentration approaches an inverse proportionality to the square of the distance. Horizontal and vertical dispersions are treated mathematically as standard deviations of the smoke
Where cy and c, are virtual diffusion coefficients in the horizontal and vertical directions, respectively, and u is the mean wind velocity (cm. per second). Sutton’s final equation is similar:
Factor 2 in the numerator of Equation 2 takes care of the reflection of the cloud from the ground. n is a pure number, ranging from 0 to 1, which depends on the atmospheric stability. Sutton states the value of n is 0 under extreme lapse conditions; about under neutral conditions; with mild inversion; and with strong inversion. Sutton, therefore, employs an exponent for x of 1.75 in a neutral atmosphere, instead of 2 as suggested by Bosanquet and Pearson. The equations state that the ground concentration varies directly with the mass of contaminant emitted and inversely with the wind velocity. At great distances downwind, where x is large compared with the stack height, h-say 50 stack lengths-the ground concentration varies inversely as the square, or the (2 - n) power, of the distance. It will be zero when x is zero and also when xis infinite. By differentiating Equations 1 and 2 it may be shown that the maximum ground concentration, which, of course, occurs along 2409
2410
INDUSTRIAL AND ENGINEERING CHEMISTRY
the center line of the smoke stream (y from Equation 1 :
=
0), is found at a distance,
or from Equation 2 :
Vol. 41, No. 11
n may be evaluated from the wind profile by means of the equation:
where u1 is the wind velocity at unit height and u is the velocity a t height z . The diffusion coefficients are defined by Sutton in or the crosswind vclocity terms of n and the vertical velocity (i')in the eddies:
(w')
(4) The maximum ground concentration is, from Equation I :
or from Equation 2 :
Though mathematically the diffusion coefficients e, and c, are not necessarily identical in the Bosanquet-Pearson and Sutton formulas, if the same numerical values of c, are employed in Equations 3 and 4, the distance from the stack to the point of maximum ground concentration will be twice as great by Equation 4 as by Equation 3, \vhen n = 0; and the distance by Equation 4 will be greater still when n is finite. For example, if e, = 0.05 (a probable value in a neutral atmosphere) z = 10h according to Bosanquet-Pearson; and z = 20h according to Sutton when n = 0; or z = 31h when n = 0.25. Equations 5 and 6 are identical except for an 8% difference in the constants, assuming the ratios of the diffusion coefficients are equal. They indicate that the maximum ground concentration is inversely proportional to the square of the stack height. This important deduction points the way to the solution of many industrial smoke problems. If by doubling the stack height the maximum ground concentration can be reduced to 25y0, great relief may often be expected. Though there will not be corresponding reduction of the ground concentration a t great distances from the stack, the improvement of conditions nearby is generally the most urgent need. Equations 5 and G include the ratio of the vertical diffusion coefficient to the horizontal. At the elevation of the top of a high stack, these coefficients are usually equal ( I O ) , but under stable inversion conditions, the vertical coefficient may be much smaller than the other, resulting in reduced ground concentrations. The reverse may be true under very unstable conditions, when a wind with a large vertical component downward may bring the smoke to the ground momentarily near the stack. Such contact generally will be of very short duration. This is in accord with the observations of Church and Gosline (4) who discuss different types of smoke streams under various atmospheric conditions. They classify the streams as looping, coning, and fanning: these are produced in an unstable, a neutral, and a stable atmosphere, respectively. X i t h thermal turbulence they have observed maximum ground concentrations more nearly at one stack length away from a 200-foot stack than ten lengths (3). Probably, however, the actual exposure (concentration times time) will be less very close to the stack than a t a greater distance. Under inversion conditions the smoke stream may travel great distances without coming to the ground. Beers (1) has illustrated these different conditions with drawings and photographs. The constants in Sutton's equations are not empirical, but are derived from theoretical considerations only. Sutton ( 10) refers to the Bosanquet-Pearson analysis as semicmpirical. The principal difficulty in applying the equations to a practical case lies in the uncertainty of the diffusion coefficients and n, which characterize the atmosphere at a particular time and which are measurable meteorological entities independent of the smoke.
where v is the kineinatic viscosity of the air (0.15 a t 20' C.). Continuous measurement of these meteorological parameters, along with the ground concentration, would be necessary for a rigorous test of the theoretical equations. Such measurements have not been made in the present study, and the results are presented with respect to assumed values of n, cy, and e,. Beers (1) has described a recent meteorological installation by which such data are being obtained. The diffusion coefficients cy and e, have been studied in smoke clouds near the ground and also at high elevations in shell bursts. The value of cu has also been determined by releasing clusters of small balloons and picking up as many of them as possible a t distances of 18 to 360 miles downwind. Sutton has found that near the ground c, is larger than e,! but a t elevations greater than 26 meters, the diffusion tends to be isotropic. Sutton (9) gives the equation: c, = c, - 0.075 log z , where e , is the diffusion coefficient on the ground, and x is the height in meters. I n a recent paper Sutton (IO) found from measurement on smoke clouds near the ground that c, is about 0.22, but in an earlier paper (9) he found c, = 0.30 from data a t high elevations. Using the value c, = 0.22, c, would be 0.07 a t 100 meters height and 0.05 a t 200 meters. The balloon data already referred to gave cy = 0.08. For convenience in applying the theoretical equations to field sulfur dioxide data, it is desirable to transpose the mass emission and the wind velocity to the left-hand side of the equations and to calcuIate the constants in conventional units of the smelting industry. Equation 1 then becomes: (la)
where C = p.p.m. (by volume) of sulfur dioxide a t sea level; u = miles per hour; 91 = tons of sulfur emitted per 24 hours; and 5,y, h = feet. Similarly the constant for Equation 2 is 121,000; for Equation 5 , 31,000: and for Equation 6, 44,500. These constants are about lSYc larger a t 4500 feet elevation. Solutions for the Bosanquet-Pearson and Sutton equations are shown in Figure 1, in which the Cu to Jf ratios for sulfur dioxide are plotted against distance from the stack, using two arbitrary values of the diffusion coefficients, c y = e,, and four values of the exponent factor, n. Only the center line of the smoke cloud is considered (y = 0). The curves give the maximum ground concentrations a t different distances downwind from the stack. They were first calculated for the bO&foot stack a t Selby, Calif. Transposition of the curves to other stack heights and other barometric pressures is accomplished by merely changing the coordinates of the chart, except that the abscissas of the curves having different exponents of z do not shift proportionately. Figure 1 gives the location of several recorders with their appropriate coordinates and shows the displacements of the abscissas for the 146-foot Selby stack, with different values of n in Sutton's equation. The corresponding displacements for the 407-foot Garfield stacks are not shown, but they are relatively unimportant.
3 Y
ci
I
IL pu 0
a
fj
*
241 1
INDUSTRIAL AND ENGINEERING CHEMISTRY
November 1949
(30-MIN. SAMPLES)
3
2
4
5
2 4 A
2
* J
3 W
B
m
0.310
m 2.10
0.123
0.248
1.68
0.098
0.186
1.26
0.0735
0.124
0.84
0.0491
0.062
0.42
E0.0245
X
AV.
YEARLY M A X . MONTHLY M A X .
(2-MLN. SAMPLES)
@ MAX\MUM @ AV. M O N T H L Y MAX.
A
A
P
AV.
D\LLON QKCORDER UNOkR 605'5TACK
5 e
Selby 605-It. stack, all curves Selby 146-ft. stack, l a , l b , 2a, 2b 3a, 3b 4a 46 Garfield 407-ft. stack, l a , lb,' 2a, 2b
20 5 4 3.6 13.3
30
..
.. .. 20
40 50 10 8 7.2 26.7 33.3 Distanoe from stack, 1000 ft.
....
80 15 12 10.8 48
70
.. ..
46.7
Figure 1. Solutions of Bosanquet-Pearson a n d Sutton Equations for Sulfur Dioxide Eliminated from Four Smelting Plants T w o values of diffusion coefficient8 and four values of Sutton's n are considered;
concentrations at the four smelters are shown
observed maximum ground
---- cy
-
= e, = 0.07 g = c, = 0.05
Bosanquet and Pearson, curves l a , l b Sutton, n 0 2a, 2b n = 0.25 3a, 3b n = 0.33 4a, 4b n = 0.50 5a, 5 b
The curves of Bosanquet-Pearson lie nearest to the stack and as already indicated have maxima a t seven to ten stack lengths distant, that lie about 8% below the Sutton maxima. Increasing the diffusion coefficients cy and c, shifts the curves nearer to the stack. The distance from the stack to the maxima in Sutton's curves when n = 0 is double the distance in the corresponding BosanquetPearson curves. As n is increased the Sutton curves move out to great distances, suggesting that under stable atmospheric conditions, the smoke may travel far before any of it reaches the ground. At sqme point downwind, however, the concentration could theoretically be as high as ever occurs near the stack, unless the horizontal diffusion coefficient is greater than the vertical coefficient. Figure 2 shows solutions of the equations for Selby under the short and tall stacks, with values of cy = c, ranging from 0.05 to 0.10, and values of n from 0 to 0.5. The curves indicate that the relations between Cu to M and the diffusion coefficients and n vary greatly with the ratio of stack height to sampling distance. This can, of course, also be inferred from Figure 1. The role of wind velocity in these equations needs to be emphasized. In a 1-mile-per-hour wind the ground concentration should be ten times as great as in a 10-mile-per-hour wind if the diffusion coefficients and n do not change. This presumes that the smoke will have no buoyancy when it emerges from the stack. I n prac-
tice, however, the smoke may be discharged at high temperatures, in which case it usually rises to high levels above the stack when the wind velocity is low, or is blown nearly horizontally from the top of the stack by strong winds. Departures from the theoretical equations may, therefore, be expected if the smoke is hot. O'Gara and Fleming (8) have estimated that each degree Fahrenheit of smoke temperature above environment is equivalent t o 2.5 feet of extra stack height.
SMELTERS AND SULFUR DIOXIDE RECORDERS Four smelters are considered in this paper:
1. The Selby, Calif., smelter (7') is below Car uinez Straits in San Francisco Bay. Figure 3 is a recent a e r i a photograph of the district. The smelter is marked by an arrow. The sulfur dioxide recorder, is on Dillon Point, elevation 100 feet, 2.6 miles east-northeast up the straits. The area has many large industries, which expanded greatly during the war years. The Selby plant had a 146-foot stack until October 1937. Thereafter it has employed a 605-foot stack on the same site. The recorder is in the prevailing wind direction from April through October, but the wind blows much less frequently to the east in the winter. The wind velocity is generally lower in winter than in summer. 2. The Tacoma, Wash., smelter is 4.5 mikes northwest of the city center. It has a 573-foot stack, placed a t the edge of the plateau above Puget Sound. A recently installed sulfur dioxide
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 41, No. l i
FIELD SULFUR DIOXIDE CQNCENTRATIONS The theoretical curves in Figure b have been tested by placing oii them the ratios of the mnximum ground concentrations of d f u r dioxide a t the different recoiders to the mass emission oi .ulhir from the smelter. I n each case the ratio has been multiplied by the wind velocity so as to give a value corresponding to 1mile per hour. The same ground concentration will, therefore, give a larger C a to J2 ratio, the more rapid the wind. If the wind veIocitp is low it sometimes happens that the maximum ground concentration dorb not yield the maximum C U to , It' ratio. In the table5 both the maximum CU to M ratios and the ratios associated with maximum ground concentrations are usually given. These ral ios me appreciably diff erent foi the yearly maxima but more nearly equal for the monthly maxima. The coordinates of the Selby and Garfield recurdeic are given in Figure 1. The Tacoma, stack is nearly as high as the tall Selbg stack, and the ordinates of the iatter need only to be incr~siedlOyoto give the correct ratios for Tacoma. The El Paso copper stack has t h y 0 05 007 0 0 8 0.10 0.0,; 0.07 0.08 10 same coordinates as the Garfield stacks and the El Past, lead stack has coordinates intermediate betn een tho76 Diffusion Coefficient, cy = LZ ofGarfield and the ''-foot 'elby stac'c. Figure 2. C ~ / M Values from Bosanquet-Pearson and Sutton The points in Figure I represent the average of all the a t Dillon Recorder with Relation to Short and Tall Selby Stacks monthly peak concentrations for the delby, Garfield, and Four values of diffusion coefficients and four of n are considered; observed El Paso recorders, and also thP average of the yearly peak maxima recorded a t Dillon are plotted concentrations. The latter are about 30% larger than the monthly peaks. These are 0.5-hour recordings. 'I'he 3. The Garfield, Utah, smelter is 20 miles southwest of Salt L'acoina and El Paso data give not only 0.5-hour recordings, butc Lake City, at the north end of a mountain spur, near the shore of ilm instantaneous (1 to 2 minute) peak concentrations. l'sr Great, Salt Lake (elevation 4200 feet). Figure 4 is an aerial toiliinately, the Tacoma d a t a are v ~ i v l i m i l r din amount. photograph of the plant. I t has thiee stacks, set about 1000 feet from each other, a t the corners of a nearly equilateral triangle. Stack 1 is 3.50 feet high and its base is a t an elevation of 4300 feet. Stacks 2 and 3 are each 407 feet high and their bases are a t elevations of 4350 and 4450 feet, respectively. To the south the mountains rise steeply to the end of a sharp ridge (elevation 9000 feet) which extends on to the south-southeast. Smelter Peak, 1000 feet high, is just east of the stacks. To the left in Figure 4 is the valley floor; to the right Kesler Canyon mounts t o the eastsoutheast 2.5 miles to a ridge 2000 feet high; beyond this the terrain falls off for a similar distance in Little Valley, until the main valley floor is reached again. A frequent path of the smoke is along the mountains to the south and south-southeast, or southsouthwest. Much less frequently the smoke travels east-southeast into the valley or skirts the north side of Smelter Peak. Figure 5 is a map of the Garfield district showing the smelter, the mountains, the agricultural area, and the locations of all the sulfur dioxide recorders which have been operated in the area Figure 6 is an aerial photograph of the agricultural area looking toward the Garfield smelter (G.S.) and Little Valley (L.V.). This paper is concerned principally with the three original stations which were established in 1930. The Litval recorder is 5 miles east-southeast of Garfield, Lyngberg is 1.5 miles due east, and Figure 3. Selby Smelter District Dillon Recorder Located Asarco is 1.5 miles northeast of Litval. Other recorders have at Upper Right Beyond Bridge been started subsequently and operated for various periods. 4. The El Paso, Tex., smelter is northwest of the city near the Rio Grande River. The copper department has a 400-foot stack In the i'ase of Selby tall-stack d a l a , a background of sulfui The lead departmrnt has a 225-foot stack, placed 1600 feet south (173 ") of the copper stack. The bases of these stacks are 50 feet dioxide from other industries in the area developed during the above the river. T o the northwest there is a strip of agricultural observation period. I n 1940 the recordings during 4 months land along the river. Two recorders are located in this river when the smelter was shut down were one third the average vaIueu valley. The first, Veck, is 3.2 miles northwest (305"), and the second, Farrell, 5.1 miles (310") ,from the stacks. A photograph in those months during the two preceding and two following years. of this agricultural district showing the Veck recorder with relaIn 1946 a similar comparison showed that the background had intion to the smelter stacks has been published ( 6 ) . A third recreased to two thirds of the concentrations with the smelter iii corder is on the slag dump 700 feet north (355') of the copper operation. For this reason, the Cu to M ratios recorded in Figure stack and 2300 feet from the lead stack. This recorder is almpst exactly in line with the two stacks but appreciably off the line 1 for the Selby 605-foot stack are one half the observed ratios. In from the stacks to Veck and Farrell. A fourth recorder, i"v.lcKellithe other records no correction is made for background, though a gon, is 1.5 miles east. The terrain slopes gradually upu-ard to this small adjustment on the Selby 146-fOOt stack data might be adinstrument, which is 150 feet below the top of the 400-foot stack. visable. During 6 years, 1942 to 1948, the Cu to M ratios ai The Veck recorder was started in 1929, Farrell in 1939, IClcKelligon in 1940, and Slag Dump in 1946. The latter 1s a sulfur Selby exceeded Sutton's (10) theoretical maximum during thirLydioxide-total sulfur instrument ( 1 1 ) from which 1-minute eight 0.5-hour periods, in the most extreme case by 57%. All peak concentrations can easily be read. Wind direction and these periods had wind velocities ranging from 8 to 18 miles per velocity were recorded on an unused stack 320 feet high a t the hour and, therefore, had only moderate ground concentration. If smelter. recorder is 2.8 miles south-southwest ol the stack, in the principal landward wind direction. The land between the stack and the recorder is essentially level. Only a limited record, extending from June 1948 through April 1949, is available at This recorder is the instantaneous type,giving short-time concrntr,2tions, as well as 0.5-hour average concentrations (IZ).
November 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY Table 1.
Table I1 summarizes the Tacoma data. No definite information is available reaard-
Sulfur Dioxide Recorded at Dillon Point (2.6 miles from Selby) Wind
2413
605-Foot
V.ln&trr
*
i
Theoretical maximum Average yearly maximurri C u / M from max. ground coricri. Max. C u / M ratios Average monthly maximum C u / M from max. groimd roririii. Max. Cu/M ratios Average all recordings a Standard deviation.
1 .o
2.10
6.4 12.4
0.371 0.531
8.1 L0.2 9.7
0.274 0.312 0,013
ing the peak recordings averaged 4 miles per hour. The highest short-time ground con0.057 centration was associated with 0.063 0.005 a wind of 4 miles per hour, and the highest Cu t o M ratio occurred with an S-mileper-hour wind. It is unlikely that turbulence was excessive during these recordings. The data seem to fit the Bosanquet-Pearson equation better than Sutton's, unless large diffusion coefficients are used. Momentary peak concentrations were less than double the highest 30-minute peak concentration. When all of the short-time peak concentrations were averaged, they were about 50% larger than the corresponding 30-minute values. The average of all recordings was 7% of the maximum concentrations. The recorder registered zero 91% of the time. Table 111is a summary of the Cu to M ratios in Pleasant Green, giving the monthly and yearly maxima, and also the values based on the average recorded concentrations. The latter are about 5% of the maxima. The average recordings a t Lyngberg and Asarco are appreciably less than expected, if the inverse square dilution factor is applied to the Litval data. This is undoubtedly because the smoke tends to turn to the south after clearing the ridge beyond Kesler Canyon, so that it does not come out into the valley, thereby recording at Litval, but often missing the other recorders. On the other hand, the highest concentrations are not sufficiently different to satisfy the inverse square dilution law. The peak values at the different recorders frequently represented different fumigations. On some fumigations the inverse square dilution law was more closely followed. The recorded maximum concentrations of sulfur dioxide in Pleasant Green are associated for the most part with low wind velocities, as shown in Table 111. It has repeatedly been observed that after a period of calm (less than 3 miles per hour), lasting several hours, during which time the smoke accumulated in a large cloud high above the plant and not far distant laterally, a gentle breeze (about 5 miles per hour) would take the cloud across Pleasant Green and produce the highest observed ground concentrations. Only on rare occasions has the smoke been carried
0.122 +
0.140",
*
0.045
f
0.163
A
0.1Sfi
these high ratios were not due t o background, it would probably be necessary to assume that the inverse proportionality to the velocity does not hold at high velocities, or that c, was greater than cy. However, it is practically certain that they were too high due to other sources of sulfur dioxide. Both the yearly and the monthly maxima for all the records, except those for the Selby 146-foot stack and the El Paso 225-foot stack, fall in the area between the Sutton and Bosanquet-Pearson curves in Figure 1. The exceptions at Selby have about three times the Bosanquet-Pearson values, and nearly double Sutton's values for n = 0. At Veck and Farrell the differences are smaller. I n no other cases have maxima been obtained which require values of n appreciably above zero, though very stable atmospheric conditions have undoubtedly prevailed a great deal of the time, particularly a t Garfield. The high recordings at Selby usually occurred at about midday and were associated with wind velocities that average 10 miles per hour. It is, therefore, possible that the diffusion coefficientswere large, whereas n was between 0 and 0.25. This would be more likely with the short stack than the tall stack. Figure 2 shows that Sutton's equation might apply to all Selby data if the diffusion coefficients were increased to 0.10 and values of R up to 0.25 were taken. The maxima at El Paso occurred under similar atmospheric conditions. Table I summarizes the Cu to M ratios for Selby. The effect of increasing stack height 4-fold has been to reduce the peak concentrations at Dillon Point 4-to 5.5-fold and t o reduce the average concentrations of all recordings, excluding zero values, about &fold. The average frequency of zero recordings has been increased from 12Yc of the time under the low stack to 19% under the high stack, and the zero recordings plus the 0.01 p.p.m. recordings from 41 to 57%. It is known from air analyses with portable apparatus that much higher concentrations occurred near the Carquinez Bridge than at Dillon Point when the short stack was in operation, and it is not unlikely, therefore, that the tall stack has decreased the maximum ground concentration 16-fold, as required by the theoretical equations. The average of all recordings was about 3% of the average yearly maximum under the low stack and 8% under the high stack. Table I indicates that the highest ground concentrations occurred with somewhat lower wind velocities than the average of 10 miles per hour. The wind velocity was the same for the two stacks for each group of entries in Table I. It may be inferred that conditions of neutrality or mild lapse probably obtained during these sulfur dioxide visitations because the majority occurred near noon on clear days.
0.126 0.187 0.114 0.126 0.010
0.122
*
0.04Ga f 0.014 f 0.041 =t0.042
Figure 4.
0.063 0.093
Garfield Smelter
INDUSTRIAL AND ENGINEERING CHEMISTRY
2414
Vol. 41, No. 1 1
in Pleasant Green agree so well with the Bosanquet-Pearson (Stack height 573 feet, recorder 2.9 miles from stack) equation. On the one hand Wind Short-Time Wind 30-Min. Av. the effective stack height is Velocity, Peak Concn., Velocity, Concn Mi./Hr. Cu/M Mi./Hr. CU/,G' much greater than the actual height during calms. Because Theoretical maximum 1 0 0 : 136 1.0 0.135 Observed maximum of the high temperature of the 4.0 0.060 C u / M from max. ground concn. 4.0 0,072 4.0 0.060 8.0 0.102 Max. C u / M ratio stack gases, the smoke usually A\,erage monthly maximum 5.2 0 . 0 2 6 * 0.016 rises 1000 to 2000 feet above 4.9 0.049 * 0.030" C u / M from max. ground concn. 6.5 0.027 0.016 8.3 0.066 * 0 . 0 2 9 Max. C u / M ratio the stack before it begins to ~~. .~~ 6.0 0,0043 Average all recordings spread out. On the other 0 Standard deviation. hand the atmospheric stability which usually obtains a t those Table 111. Sulfur Dioxide a t Garfield-1936 to 1948 times would tend toward poor Wind Velocity, Mi./Hr. dispersion. One effect may C u / M LyngAsarco Litval berg Asarco Litval Lyngberg offset the other to a considerTheoretical maximum 1.0 1.0 1.0 0 . 0 3 6 3 0.0229 0.0293 able extent. Average yearly maximum On rare occasions, the GarC u / M from max. ground concn. 3.7 4.6 4 . 5 0 , 0 2 9 0 * 0 . 0 1 1 3 a 0 . 0 2 7 4 It 0 . 0 0 9 5 a 0 . 0 2 6 6 * 0 . 0 1 1 4 a field smoke has been blown 6.2 6.9 7 . 2 0 . 0 3 7 3 * 0 . 0 0 8 5 0 . 0 3 1 5 * 0.0088 0 . 0 3 2 6 * 0 . 0 0 7 2 Max. C u / M ratios on steady brisk winds into dverage monthly maximum C u / M from max. ground Pleasant Green, causing maxiconcn. 4.7 6.1 5 . 9 0,0205 0.0094 0.0161 i 0.0085 0.0177 *00.0075 Average concentration 6.9 6.9 6 . 9 0.0025 0.0010 0.0014 mum Cu to M values without a Standard deviation. any previous accumulation of sulfur dioxide near the smelter. Per haps the most striking of these fumigations occurred on May 30, 1937. There are in the record a few counterparts from Garfield to Pleasant Green in high concentration, by a of this fumigation in the winter, but no other so striking in direct wind without a period of accumulation. the summer. This fumigation caused a narrow band of crop inWith conditions such as these controlling the Garfield smoke, it jury extending east-southeast near the Asarco recorder and for is perhaps coincidence that the maximum recorded concentrations
Table 11.
Sulfur Dioxide a t Tacoma, Wash.-June
1948 to April 1949
f
Figure 5. Map of Pleasant Green District, Locating Recorders with Relation to Garfield Smelter Arrow shows axis of fumigation
of May 30, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
November 1949
to the Asarco record. From records on similar days in this season of other years it is probable that an inversion existed a t least until after 7 A.M. on this date. It is evident from these records that the smoke stream skirted the north side of the hills in an easterly direction, then traveled east-southeast a t 103" across the district. Table IV gives not only the actual Cu to M values but also the theoretical values from Bosanquet and Pearson in the center of stream and a t various distances, y, crosswind from the center. The diffusion coefficients used were 0.05. The Sutton equation with n = 0 would have given nearly identical values with diffusion coefficients of 0.07. The data show that the axis of the stream passed over Asarco and Lyngberg during two full half-hour periods each, but more frequently it lay between the two recorders, being 1000 to 2000 feet from one or the other. The main stream definitely missed Litval, but the concentrations recorded there were very close t o the expected values. However, nearly the same concentrations were also shown on the Coon recorder, which lay so far to the south that its recordings should have been negligible. Probably a small portion of the smoke was deflected by the hills and eddied in that direction. In another similar fumigation, on February 22, 1943, the stream passed over Litval and Lyngberg directly and only the edge touched Asarco. Cu to M values like those in Table I V were obtained in this case also, indicating more than accidental agreement with the theoretical equations. This fumigation started a t 10 A.M. a t the same time recording thermometers on a 450-foot chimney near the laboratory showed a change from inversion t o lapse. The day was cloudy until 1 P.M. Thereafter it was practically cloudless. Change from lapse to inversion occurred a t 7 P.M. The Cu t o M ratios varied but the highest values were not greatly different in the morning, afternoon, and evening, suggesting that sunshine and temperature gradients were not controlling factors in this fumigation. At El Paso, with two stacks of different heights and with four recorders, the record is necessarily complex. Most of the record involves simultaneous operation of both stacks but there are a number of representative periods when the 225-foot stack
Table IV. Fumigation i n Pleasant Green May 30,1937, and Theoretical C @ / M Ratios from Bosanquet-Pearson Using c, = Time, A.M.
4:30 5:OO 5:30
6:OO
4
6:30 7:OO 7:30 8:OO 8:30 9:00 9:30
9 8 10
10:30
6
c
.
WindQ Velocity Mi./Hr.' 12 10 7
1o:oo
9 8 10 6 4
Average Calculated, y (feet) 0 1000 2000 3000 4000 6000 Distance from Garfield (miles) a
C.
= 0.05 Cu/M
Asarco 0,0154 0.0158 0.0286 0.0065 0.0094 0.0305 0.0233 0,0181 0.0244 0.0240 0.0250 0.0078 0.0034 0.0178
Lyngberg 0.0031 0.0058 0.0164 . 0,0088 0.0149 0.0149 0,0240 0.0103 0.0229 0.0078 0.0089 0,0034 0.0040 0.0108
Litval 0.0000 0.0000 0.0004 0,0009 0,0055 0.0043 0.0052 0.0035 0.0022 0 0039 0.0018 0.0012 0.0014 0.0027
Coon 0.0000 0.0000 0.0006 0.0004 0.0037 0.0078 0.0069 0.0056 0.0025 0.0022 0,0009 0.0007 0.0013 0.0030
0.0293 0.0235 0.0123 0,0040 0.0009
0,0229 0.0198 0.0120 0.0051 0.0016
0.0363 0.0274 0.0119 0.0030 0.0050
0.0281 0.0228 '0.0122 0.0043 0,0010 0,00002
5.75
6.50
5.05
5.9
...
...
I
Wind west-northwest.
several miles beyond, so 'that its axis was clearly defined not only by the recorders but also by the marked vegetation. The arrow in Figure 5 locates the axis of this smoke cloud, and Table I V gives the Cu to M values on four recorders for each half hour during the visitation. A line-drawing wind vane at Asarco showed a remarkably steady wind during this period, with very small shorttime fluctuations of direction, suggesting very low turbulence, considering the wind velocities registered. A pyrheliometer record a t the laboratory, 10 miles east of Asarco, showed an overcast sky during this period, with a light intensity of about 20% of a cloudless day, and the wind record a t the laboratory was similar
Table V.
2415
Sulfur Dioxide a t El Paso, Tex., Slag Dump and McKelligon Recorders Wind Velocity Mi./Hr:
C u / M Ratio 400-Foot Stack 30-min. 1to 2 min. av. peak
Both Stacksa
~~
225-Foot Stack
30-min. av.
1 to 2 min. peak
Slag Dump Recorder (0.13 and 0.43 Mile). Theoretical max. (Sutton) Calculated maximum Bosanquet-Pearson Sutton Observed maximum Max. C u / M ratio associated with max. ground concn. Max. C u / M ratio Av. monthlv max. Max. C u i M ratio associated with max. ground concn. Max. C u / M ratio Theoretical max. (Sutton) Calculated maximum Bosanquet-Pearson Sutton Observed maximum Max. C u / M ratio associated with max. ground conon. Max. C u / M ratio Av. yearly max. Max. C u / M ratio associated with max. ground concn. Max. C u / M ratio Av. monthly max. Max. C u / M ratio associated with max. ground concn. Max. C u / M ratio a e
1.00
1.00
0.32
0.32
?
0.93 0.22
'0.93 0.22
0.0006 10-&8
0.0006
? ?
0.58 0.92
b
b b
14 21
0.211 0.211
7 11
0.050 0.079
0.04SC
* 0.042 f
0.29 0.42
b
* O.llc A
0.12
10-5s
b
0.195 0.284 0.079 0.108
b
McKelligon Recorder (1.5 Miles) 1.00 0.32 1.00
0.32
0.5 ?
0.34 0.69
0.34 0.69
0.20 0.30
0.20 0.30
ir
19 25
0,266 0.266
0.354 0.376
0.123 0.123
0.33 0.51
12 21
0.114 0.123
12 17
0.076 * 0.074 0.083 I O . 0 7 7
t
0 096
* 0.102
0 176 A 0 102 0.257 =I 0.103
0.157 0.193
* 0.086 * 0.100
* 0.046E A
0.064
0.043 0.061
Slag Dump d a t a calculaked using emission from the 225-foot stack alone: McKelligon ratios represent total emission. Insufficient data. Standard deviation.
0.55 0.67
* 0.32~ f
0.33
0.5 ? 7
1
0.101 0,181 0 047 0.114
b
1.01 1.30
0.255 0.430 f
;b
0.029 0.043
* 0.041 f
0.038
0 191 0.277
o
124 0 150
f
h
t
0.054 0.105 0.095 0.095
INDUSTRIAL AND ENGINEERING CHEMISTRY
2416
Yoi. 41, No. 11
The theoretical maximum ground concentration for I-minute pcaks was exceeded at Slag Dump a few times--in one case by 30%--during operation of both stacks but assuming t,hat only the 225-foot stack contributed the gas. This assumption is questionable in particular cases. With the 225-foot stack operating alone the t>heoret,icalmaxiinuni was never exceeded. On these occasions the wind velocity reached 32 miles per hour, which would tend to magnify analytical errors. There is soine uncertainty also as to how nearly the stack emission a t the moment of sa.mpling corresponded with the 24-hour emission. Similarly, there was a tendency for the theoretical peak ground coricentrations a t McKelligon to be exceeded up t,o 60% during the short period when the 400-foot, stack was operating alone. The apparent discrepancy might be due to the fact that the McKelligon recorder was only 160 feet below the top of the 400-foot stack, and Kith strong winds such as prevailed during the recording of these xna,xima, the effective stack height might have been actually lower than 400 feet. None of these discrepancies are therefore sufficiently definite to invalidate the theoretical equa,tions.
Figure 6 . Pleasant Green District Looking from Granger to Garfield Smelter
Table V 1 presents the data for the Veck and Ir' Again t'he Cu to M ratios agree well with the Sut,ton a.nd Bosanquet-Pearson equat>ionsexcept that !$-hen the 225-foot stack was operating alone, the ratios showed a definite tendency to exceed the values estimated by Sutton's equation with n = 0. This is in accord with the observations under the l46-foot stack at Selby. The ratios are appreciably larger xvith the short, stack alone than with both stacks operating. Evidently i s requires considerably more sulfur elimination from both stacks, than from the 225-foot Btack alone, to produce the s l i m ground concentration. h comparison of eirnult>a,neousrecordings at Veck and Y a r d has been made which shows the dilut,ion of the gas in passing from the former station t o the latter. AI1 the principal periods of smoke visitation a t Veck during more t h a n 3 years were tabulated, and
operated alone. € 1 0 e~\ w . ihr 4OU-toot stack has operated alone, very seldom. Significant data For this condition is almost entirely lacking except for about I morith in April and Ala) 1940, at which time only the Fair ell and hlclielligon rpcoiders weie functioning The Slag Dump recorder i s leas than t a o slack lengths from the tall stack but about ten lengths trom the low stack. As the s t n c k s are exactly In line with this recorder, it aould be impossible to deTermine which stack was rcsponsihle for a particular fumigation except by visual observation. this usually indicated that the smoke from the tall stack passed high above the recorder. Accordingly, the data have been calculated using the emission values for the 225-foot stack only. AQ the latter generally emitted somewhat less sulfur than the Table VI. Sulfur Dioxide a t El Paso, Tex., Veck and Farrell Recorders 400-foot stack, the CZLt o 21 ratios during operation of both XX'ind C u / M (30-1LIinute Averam;-_ .. Velocity, _._____.___ etacks are too high if thiAIi./Hr. 225-foot stack 400-foot stack Both stacks. procedure is not correct. Thr Veck Recorder (3.2 Miles? ratios for all the other rtlI'heorctical max. (Sutton, P 1 ,00 0.32 Calculated maximum corders are calculated using Bosanquet-Pearaon 1 0.093 0,075 total sulfur emission. 1. 0.177 0.160 Sutton Observed inaximiirn The data for Slag Dump Cu/,M ratio f o r max. groutid ~ 0 1 1 ~ ~11 0.230 0,0137 0.168 14 0,243 0.067 0.168 >lax. C U j M ratio and McKelligon recorders are hv. yearly maxinium summarized in Table V. The C'u/.U ratio for max. g i o n n d concn. 20 0.130 * 0 . U 8 7 d b 0.100 i; 0.031? 15 0.174 * 0.057 b 0.131 i. 0 . 0 3 3 Max. C u / N ratio pattern of these records is of A v . monthly maximuin b 0 074 * 0.041 C u / X ratio f o r niax. groiind ooncn. 10 0 , 1 1 6 * 0.01% interest. With low steadt 14 0.133 0.064 h 0 090 i- n 040 ;\lax. C u i M Patio winds blowing toward the recorders, a uniform concentra1.00 Theoretiral mal. (Suiton) 1. (J,32 tion might persist for 10 Calaulatrd inaximnm 1 0 040 0.035 j: Bosanquet-Pearson minutes t o several hours. Hut 1 0 073 0.069 Suttnn Observed maximum with ninds oE 10 to 30 mile, 0.191 13 0.045 0.092 Cu/.Ii' ratio f o r mar. ground ('oncn. per hour, biief recording- of 0.115 13 0,101 0.046 hlax. Cliid1f ratio . i v . yrarly maximuin higher concentrations occuiird. b C u / M ratio for max. gronnd concn. 10 0.100 i- 0.048 0.064 i. 0.023 Max. C u i M ratio 15 0.114 * 0.042 b 0.085 =t 0.020 usually l a ~ t i n g only a t e i i 4v. monthly maximuin Cu/.li' ratio f o r mnx. p o i r n d ooncn. 10 0,072 * 0.049 b 0 . 0 9 i 0.027 minutes, tollon-ed by ncarl? b M a x . C u / M ratio 14 0 083 + 0.045 0.057 i- 0.026 wro recordings. These pclak 0 Standard deviation concentrations have been ? H I b 1n;ufIirient d a t a . fully calculated and a i r ineluded in Table T' and Figure Table VII. Simultaneous Recordings of Sulfur Dioxide during S m o k e Visitations 1 along TI ith t h p 30-minute at Veck and Farrell Recorders average iendings. The CR t(J (Inverse ratio 1.6; inverse square ratio 2 . 5 ) X ratios asqociated with maxiCu/:V (3.2_and _ _ ~5_ _~ _hiiles 1_ _ _ from Stack) hlax. Concentration per I'criod mum ground c o u c e n t r a t ~ o n ~ No. . Av. Concentration per Period Periods'b Veck 1:arrell Ratio Veck Fnrrell Xatio Year are given arid also the maxi2 . 5 =t2 , l a 0.075 2 . 3 i. 1,58 0.041 1!141-~42 86 0.032 0.018 mum Czi to ' 11 iatios \
