Reference method for measuring releases of mercury from mercury cell chlor-alkali plants: section 7

Section 7: Calculations

• 7.1 Equations
• 7.2 Nomenclature

To simplify recording during a test, field data may be entered in the units for which the sampling equipment is designed. These values must be converted, if necessary, to the metric units specified in the equations where they are used.

7.1 Equations

Dry Gas Meter Volume

The total sample volume measured by the dry gas meter is corrected to reference temperature and pressure conditions (25°C and 101.3 kPa) using Equation 1. For a temperature-compensated dry gas meter (T_m)_avg should be substituted by the temperature specified by the manufacturer.

Volume of Water Vapour

The volume of water vapour in the gas sample expressed at reference conditions (25°C and 101.3 kPa) is calculated using Equation 2.

Moisture Content

The volumetric fraction of water vapour in the gas expressed at reference conditions (25°C and 101.3 kPa) is calculated using Equation 3.

Volumetric Stack Gas Flow Rate

The average volumetric gas flow rate expressed on a dry basis and at reference conditions (25°C and 101.3 kPa) is calculated using Equation 4.

The average gas velocity [(U_s)_avg] and gas temperature [(T_s)_avg] for the test run from each process stream are determined by averaging the velocities and temperatures, respectively as measured at the traverse points.

Average Mercury Concentration

The concentration of mercury from each process stream is calculated using Equation 5.

Mercury Emission Rate

The mercury emission rate from each process stream is calculated using Equation 6.

7.2 Nomenclature

A_s

inside cross-sectional area of the stack, m ²

B_wo

volumetric fraction of water vapour in the process stream, dimensionless

C_Hg

average concentration of mercury from each source on a dry basis at reference conditions, μg/m ³

ER_Hg

mass emission rate of mercury from each source, g/day/(1000 kg of rated capacity for chlorine production)

M_H2O

molecular weight of water, 18 kg/kmol

P_bar

barometric pressure at the sampling site, kPa

P_d

rated capacity for chlorine production, 1000 kg chlorine/day

P_ref

reference pressure, 101.3 kPa

P_s

absolute stack gas pressure, kPa

Q_s

average volumetric gas flow rate from each source on a dry basis at reference conditions, m ³/h

R

universal gas constant 8.31 kPa·m (kmol·K) ^-1

(T_m)_avg

average of the dry gas meter temperatures, K

T_ref

reference temperature, 298 K

(T_s)_avg

average of the process source temperature, K

(U_s)_avg

average gas velocity at the source, m/s

V_a

sample aliquot volume, mL

V_m

volume of gas sample at meter conditions, m ³

(V_m)_ref

volume of gas sample at reference conditions, m ³

V_soln

total sample volume, usually 500 mL

(V_w)_ref

volume of water vapour in the gas sample at reference conditions, m ³

W_a

amount of mercury in the aliquot, μg

W_b

amount of mercury in the blank, μg

W_H2O

weight of water vapour condensed in the impingers, g

Y

dry gas meter calibration factor, dimensionless