Question

A power plant burns coal with 2 % sulfur. Emissions occur through a 70-m tall 02. stack with a diameter of 1.5 m. The exit velocity and temperature are 15 m/s and 340°C, respectively. The atmospheric conditions are temperature of 28°C and pressure of 90 kPa. On a clear summer aftemoon with a wind speed of 2.8 m/s at 10-m level, the ground level SO concentration is measured to be 143 ug/m at a point 2.5 km downwind and 300 m off the plume centerline. How much coal does the plant bun?

Answer 1

brinen, the height of the stack is 70m The diameter of the stack is 1.5m. The velocity and temperature of the exit gas is 15ml See and 340°c respectively. The ginen atmospheric pressure is sure is 90 kfc = 900 milli bars, Heike we have to use Hollandi Equation to find the effective stack height (H) The Hollands Equation is given as, Ah = 3 [1.5 + 2.68x10² p. D / T3 - Ta]] .... (1) where, Ah is the effective phame height in in. is is the exit velocity of the gas in m/sec. D is the diameter of the stalk in me u is the mind relocity in m/sec. Pis the atmospheric pressure in milli hears Is is the exit you demperature in K. Ta is the surrounding temperature ink. и Now, Ah = 15$45 [1s+288 x 10 * 2004 15/161371301)]m Ah - 15X15. 2.8 2 651/613-301 613 = 26.85 m This effective stakk height= Ahth 1 = 26.85+ 70 = 196.85m

Asain, it is stated that it is a clear summer ofternoon with a mind speed of 2.8 m/sec at 10 m level. Thus from the table provided me can conclude that the stability condition is class (A-B) Now, to find the amdent of coal larent in the plant me have to find the emission rate of 802. The emission rate of 50 g could he found day transion Distribution Equation, a city where, Cosy is the concentration of the gas in gesen, & is the emission rate of the gas in gessee u is the mind relocity in aussee E is the Plumes Standard Debiation in vertical direction in m Sy is the Plume's standard deviation in cross mind direction in an k and y are the down mind and cross-mind horizontal distances, respectively inm. His the effective height of stack in m.


Now, we have to find the values of 67 and by from the graphs provided below, 8z = 1500m with respect to a = 2.5 km and class (A-B) by = 400m with respect to x = 2.5km and class (A-B) the given concentration is 143 ugensom? = 14,3 x 100 g / m² Putting the respetine values in equation (a) we get, 74341016 @ fo rtement cou) eal (1sool2 t. XX2.8x1500xhon x in a = 1001.95 qm / see x 1002 qm /sec (affrex.) Thus the emission rate is 1000gm see Since, the molecular mass of both Sand Og als 32, they combine in equal amounts to form sbg. The emission rate of 50g per hour is = 100 2x sorbo Kg Ihr = 360 7.2 Kg Ihr Thus the amount of sulphur (5) present = 360+ 2 = 1803. 6 Kg/hr Since, Sulthus present in the coal is only 27., the total amount of coal is = 1803-64100 = 90180 Kg Ihr = 90.18 lows the Thus the plant burns 90.18 tons Ihr or 2164.32 tons/day

Vertical dispersion coefficient, in m- A-Extremely unstable B-Moderately unstable C-Sighly unstable D-Neutral E-Slightly stable F-Moderately stable 10 109 109 Downwind distance (1) from source in m Fig. 18.8., sxfor different atmospheric stabilities.

horizontal dispersion coefficient in A-Extremely unstable 3-Moderately unstable C-SE unstase D-Neutral E-Sigdy table F-Moderately stable Downwind distance from source in m- Fig. 18.7., v5 x for different atmospheric stabilities

Surface wind spend in m/sec Table 18.3. Pasquill Stability Types Day Night Incoming solar radiation Mostly Mostly strong moderate Ouercast clear A- B AB B- C C-D Category A-extremely unstable B-moderately unstable C-slightly unstable D-neutra! E-slightly stable F-moderately stable