Methodology of concentration calculation of harmful substances in atmospheric air due to hazardous production facility emissions

In Ukraine an assessment and prediction of air pollution produced by stationary sources of emission are implemented under current regulatory methodology ОНД-86.

1. Maximum value of air pollutant concentration C _M (mg/m3) produced by air-gas emission from a stationary source with a round orifice under adverse weather (meteorological) conditions at a distance of X _M (m) is calculated by the formula:

, (3.2)

where A is the coefficient that depends on the temperature stratification of the atmosphere and climatic conditions of the region (A = 160 for Ukraine); M is the emission rate of air pollutant, g/s; F is the dimensionless coefficient that depends on the rate of air pollutants sedimentation in the atmospheric air. Thus, F = 1 for gases; F = 2 ÷ 2.5 for fine particles matter and coefficient purification of emissions 75-90%; F = 3 for coefficient purification of emissions less than 75%; m, n are the coefficients, that take into account the emission conditions of air-gas mixture from a stationary source with a round orifice and are calculated by the formulas (3.8, 3.9); H is the height of a stationary source of emission over the ground surface, m; η is the coefficient, which takes into account of the terrain impact on concentration values of air pollutants, η =1; ΔT is the temperature difference between exhaust gases T_e and ambient air Т_a.

2. The temperature difference between exhaust gases T_e and ambient air Т_a is:

(3.3)

3. The exhaust air-gases rate, V₁, m³/s is:

(3.4)

D is an orifice diameter of a stationary source of emission, m; ω₀ is the mean value of exit velocity of exhaust gases, m/s.

4. The coefficient value m, n are determined in dependence on parameters f (3.5), V_m (3.6):

(3.5)

(3.6)

5. The coefficient m is calculated by the following formulas:

f<100 (3.7)

f>100 (3.8)

6. The coefficient n is calculated by the following formulas:

V_m≥2

0.5≤V_m<2 (3.9)

V_m<0.5

7. The distance X_M (m) from stationary source of emission, at which concentration of air pollutant C (mg/m3) obtains maximum value C _M under adverse weather (meteorological) conditions is determined by the formula:

, (3.10)

where d is the dimensionless coefficient, which depends on such parameters as f (f <100) and V_m:

V_m <0.5

0.5≤ V_m <2 (3.11)

V_m ≥2

8. The value of dangerous wind velocity Um (m/s) at which concentration of air pollutant obtains maximum value CM (mg/m3) is determined by the following formulas (f<100):

V_m ≤0.5

0.5< V_m ≤2 (3.12)

V_m >2

9. The maximum concentration of air pollutant C_MU (mg/m³) under wind velocity U (m/s), which does not correspond to value of dangerous one (U_m), is calculated by the formula:

, (3.13)

where R is the dimensionless coefficient, which depends on the relation U/U_m:

U/U_m ≤1

(3.14)

10. The distance X_MU (m) from stationary source of emission, at which concentration of air pollutant obtains maximum value C_MU (mg/m³) under adverse weather (meteorological) conditions and wind velocity U, is determined by the formula:

(3.15)

where Pis the dimensionless coefficient, which depends on the relation U/U_m:

U/U_m ≤0.25

0.25< U/U_m ≤1 (3.16)

U_m >1

Example: Calculate the maximum short-term concentration of sulphur dioxide (SO₂) in atmospheric air produced by emission of boiler plant of thermal power station under specified and adverse weather conditions. Operating and meteorological characteristics are presented in Table C.1 (input data for variant № 1).

1. The exhaust air-gases rate (V ₁, m³/s) is determined by input data (Table C.1): m³/s

2. Overheating of exhaust air-gases (Δ T) is determined by (3.3):

.

3. The parameters f, V_M are calculated by formula (3.5, 3.6):

m/s.

4. Since the value of f is less than 100, coefficient m is calculated by the following formula (3.7):

.

5. Since the value of V_M is higher than 2, coefficient n=1 (3.9).

6. On the basis of previously estimated parameters, the maximum short-term concentration of SO₂ in atmospheric air under adverse weather (meteorological) conditions is found from the formula (3.2):

mg/m³.

7. The distance X_M (m) from the boiler plant, at which concentration of SO₂ obtains maximum value C_M under adverse weather (meteorological) conditions, is determined by the formula (3.10, 3.11):

; m

8. The value of a dangerous wind velocity U_m (m/s) at which concentration of air pollutant obtains maximum value C_M (mg/m³) is determined by the formula (3.12):

m/s

9. The maximum short-term concentration of sulphur dioxide (SO₂) in atmospheric air under specified wind velocity (U =3 m/s) is defined by the formula (3.13, 3.14):

; mg/m³

10. the distance X_MU (m) from the boiler plant, at which concentration of SO₂ obtains maximum value C_MU under specified wind velocity (U =3 m/s) is determined by the formula (3.15, 3.16):

; m.

Conclusion: The concentration of SO₂ obtains the maximum value (0.18 mg/m³) at distance (481.16 m) from boiler plant of the thermal power station under wind direction – 3m/s.

Problem 3.3. Assess air quality by comparison of calculated maximum concentration of pollutant С_MU with established maximum permissible concentration C_MPC according to Ukrainian law and standards.

Дата добавления: 2015-11-16