Handbook of Solvents - George Wypych - ChemTech - Ventech!

18.2 Prediction of organic solvents emission 1233
duced into the degreasing compartment and vapors of trichloroethylene condensed on
surface of the parts. After 30 s, the basket was removed from the machine. The average temperature
at the surface was 24 o C. There was an exhaust in the hall with a flow rate of 50
m 3 /min. The solvent loss was 30 l/day and it was independent of the number of degreased elements.
The solvent loss of 30 l/day equals 1.25 l/h or 1.825 kg/h with density of trichloroethylene
equal 1.46 g/cm 3 .
The average concentration of trichloroethylene measured near the exhaust by portable
IR spectrophotometer-Miran was 680 mg/m 3 . Calculation (equation [18.2.2]) with q=50
m 3 /min gives emission of 34 g/min or 2040 g/h.
According to equation [18.2.5] for trichloroethylene:
E= (657v + 63.6t + 699.6) × P r + 34.7P
v=0.3 m/s (still air near the surface)
t=24 o C
P r=0.825 m 2
In vapor degreasing, the coefficient of mass carried out on wet details ready to ship
P=0. Then
E= (657 × 0.3 + 63.6 × 24 + 699.6) × 0,825 = 1999 g/h
The measured value of 2040 g/h and the calculated value of 1999 g/h are in good
agreement, meaning that the equations can be successfully applied to predict the organic
solvents emission during process of automatic degreasing.
Process of manual degreasing was verified for washing motor parts in a metal dish -
0.72 m 2 filled with 500 l of extraction naphtha. The surface of parts was 0.227 m 2 . This process
took place in an open garage at temperature 14 o C. Air velocity in vicinity of parts was
0.48 m/s. The residual solvent volume after degreasing was 4.58 l. The process lasted 7 minutes.
Emission estimated according the loss of the solvent during the process was 420 ml.
Taking into account the weight density of naphtha - 0.72 g/cm 3 , emission was equal 302.4
g/7 min or 2592 g/h.
Applying the equation [18.2.10] for extraction naphtha
E= (632v + 49.5t + 1147) × P r + 19P
and:
v = 0.48 m/s
t=14 o C
P r= 0.72 + 0.227 = 0.947 m 2 , surface of the dish and details
P = 0.947 m 2 /7min [8.12 m 2 /h], solvent carried out on the details and on the surface of
the dish after pouring out extraction naphtha
Thus:
E= (632 × 0.48 + 49.5 × 14 + 1147) × 0.947 + 19 × 8.12 = 2184 g/h
Again measured value of 2592 g/h and the calculated value of 2184 g/h were in good
agreement thus the equation can be applied for predicting the organic solvents emission during
the processes of manual degreasing.