Is there a fan in the top gas phase of the dichloroethane storage tank to draw air out (negative pressure of -0.02 MPA)?
Thread Content
In the dichloroethane storage tank, the vapor phase at the top is drawn off using a fan (under negative pressure of -0.02 MPA). Initially, the vapor phase can be considered to be at atmospheric pressure; once the suction process stabilizes, how should the amount of dichloroethane vapor generated be calculated? How is the concentration of dichloroethane gas calculated? Thank you!
This post was last edited by Hansonwen on 2018-7-19 at 15:03. Is it related to VOCs control? The volume of gas refers to the air extraction volume of the fan. The saturated vapor pressure of dichloroethane at 0°C is 9.33 kPaA (absolute pressure); at 25°C, it is 30.11 kPaA (absolute pressure) ； The saturated vapor pressure at 40°C is 54.84 kPaA (absolute pressure)
The molecular weight of dichloroethane is 98.96. Using the formula y=P*/P, it can be calculated that the total pressure is currently 81.33 kPa (–0.02 MPa). At 0°C, the molar fraction in the gas phase is 0.114718, corresponding to a density of 506.807 g/m3； At 25°C, the molar fraction in the gas phase is 0.370220, which corresponds to 1635.58 g/m3 ； Calculate 40 in the same way℃
Now, the fan airflow needs to be selected based on the components, so the airflow amount has to be calculated manually
I really want to understand: how does the current medium-pressure value of 81.33 kPa come about? At 0 degrees Celsius, the molar fraction in the gas phase is 0.114718, and the density is 506.807 g/m3. How is this value determined? Looking forward to your advice!
This post was last edited by Hansonwen on 2018-7-20 at 13:30. 101.33–20 kPa = 81.33 kPa, which is the negative pressure value in your tank at present; this value has simply been converted to absolute pressure. The mass concentration is calculated as the molar fraction of the gas phase multiplied by the mole fraction divided by 22.4. For example, if the molar fraction is 0.114718, then 114718 ppmv * 98.96 / 22.4 gives the result, with the unit being mg/m3
Generally, the amount of evaporation of the liquid in a heat-induced vaporization tank is very small; the volume of gas generated is usually equal to the flow rate of the liquid phase during feeding. For example, if the flow rate of dichloroethane pumped into the tank is 100 m3/h, then the volume of the liquid phase in the tank drives out the gas phase, and the volume of gas that escapes at this point corresponds to the flow rate of the liquid phase. Of course, there is also a amount of gas generated due to environmental radiation; we generally take this value to be 1.1 to 1.2 times the volume of the liquid phase
There is a lot of literature on the issue of breathing associated with tank size; take a look and you’ll understand