Estimated height hazards
In some cases, but "you can use the formula given in memory of CM-67. For the estimated heights of pollutant at least 30 m at a temperature difference between the outgoing and the outside air, equal to 10 В° C (for the most part takes place in the ventilation exhaust), and the volume of exhaust air is not less than 25 000 m3 / h (about 7,0 m3 / s) mentioned formula can be represented as follows:
Digital factor in the numerator (60) corresponds to the meteorological conditions of the European USSR and the rate of exit of air from the pipe ranging from 15 to 25 m / sec. For the Asian part of the Soviet Union indicated coefficient is 78.
As in the previous case, the maximum concentration of pollutant observed at a distance from the source, equal
Hr = 20 [m].
Calculated based on both formulas surface maximum concentration of sulfur dioxide (S02) under the following conditions: the amount emitted to the air 36,000 m3 / h (L - = 10 m31sek) \ release height / / = 40 m wind speed v0 = = 3 m / sec; amount of sulfur dioxide L1T = 2 g / sec / C = 1.
In this particular case the agreement is very close. Found the concentration of S02 is less than the permissible single concentration limit, which, for sulfur dioxide equal to 0.5 mg/m3.
Consider another example with the exhaust from the lower pipe at a lower productivity: / - = 5 ml / sec (18 000 m3 / h / / = 30 m; i> o = 3 m / sec, M = 1.5 g / sec , K = 1.
Compute C: according to the formula (33)
Fig, 18. Graph of the change of surface concentration and the pollutant - the curve for the gas, b - curve dchya dust
Analyzing formula (33) and (34), we note that the value of CM in both formulas is directly proportional to the number of ejected Mt hazard and inversely proportional to the square of height. In addition, the formula Andreeva See inversely proportional to the value estimated wind speed v0. In the formula (34) has a different, more complex dependence cm from the exhaust air volume L. Ceteris paribus the larger L, the smaller the value of CM other words, the ground level concentration Cm is smaller, the smaller the initial concentration of pollutant in the exhaust air.
Consider another example in which formula (34) does not apply: at low altitude ejection H = 18 m and a small performance exhaust setup is equal to 3600 m3 / h (i - 1 m31sek). Let A / m = 0.2 g / s and y0 = 3 m / sec.
As expected, in this example, the difference turned out almost 2 raza.Napomnim that no formula Andreeva, or formula (34) do not claim the accuracy of the PA. Calculate the surface concentration are approximate.
Both formulas give values of Cq na distance XLI = 20H on source separation of hazards. Sometimes it is important to know the value of surface concentration C at a certain distance X from the source of harm. Here is the schedule derived from the CH 369-67 (Fig. 18), where you can find the ratio - depending on the ratio - S / XM
For the first considered example Am = 20 вЂў 40 -= 800 m. The maximum concentration found 0.035 mg / m '. We find the concentrations at a distance A = 1600 m from the source of harm.