Is this the correct way to understand it? Urgent! Urgent! Urgent! ! !
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For example, consider a toluene storage tank with a storage temperature of 20°C. The volume of the gas phase is V (assuming this volume remains constant). Initially, the pressure in the gas phase is equal to the saturated vapor pressure of toluene at 20°C, namely P1. If nitrogen or some other gas is introduced to increase the pressure in the gas phase to P2, while the temperature stays at 20°C, then in my understanding: 1) Although the pressure increases to P2 after nitrogen sealing, the partial pressure of toluene in that gas phase remains P1. Therefore, the density of toluene in that volume (in mg/m3) stays unchanged. If it is assumed that the exhaust flow rate from the top remains constant, then nitrogen sealing cannot reduce the loss of toluene. Is this understanding correct? 2. After nitrogen is introduced to increase the gas phase pressure to P2, the pressure of toluene in the gas phase volume V remains at its saturated vapor pressure; nitrogen does not affect the saturated vapor pressure of toluene at that temperature. Is my understanding correct? Thank you
It doesn’t seem quite right. It seems to be related to physical chemistry; I also gave it back to the teacher.
Your understanding is correct. Your assumption is incorrect; at 20°C, the saturated vapor pressure of toluene, P1, is low. If the pressure in the gas phase space is P1, then the toluene tank would be in a vacuum state. Can your storage tank withstand that? Moreover, is your storage tank a fixed-roof tank or an internal floating-roof tank? With an internal floating-roof tank, the toluene loss you mentioned does not occur.
It doesn’t have to be toluene, nor does it have to be at 20 degrees; it can be anything whose saturated vapor pressure is greater than atmospheric pressure. It’s just an example. Do you think my understanding is correct?
This post was last edited by chen5714355 on 2020-10-13 at 14:54. “If it is assumed that the exhaust flow rate at the top remains constant, then a nitrogen blanket cannot reduce the loss of toluene.” Personally, I think this assumption is unreasonable; when the tank pressure increases from P1 to P2 while the exhaust flow rate stays the same, it is necessary to close the exhaust valve. The gas emitted after introducing nitrogen is a mixture of nitrogen and toluene. If the same flow rate is maintained, the amount of toluene that escapes should decrease, but there is still a loss of nitrogen