油库废气中挥发性有机物的低温脱除过程模拟分析

The volatile organic compounds (VOCs) in oil depot exhaust should be removed and recycled. The present authors simulated the cryogenic condensation removal of the small quantity of propane in the mixture gas using the one-dimensional calculation method. The results showed that for gas with initial propane fraction of 2.25% the heat exchanger used in present study with a length of 2.85m was required to reduce propane molar concentration in the mixture gas to 1.26×10^-4, and the molar fraction of propane decreased by 76% in the first one meter of the heat exchanger while by only 23.6% in the next 1.85m. The length of the heat exchanger required for condensation varied with the initial concentration of propane. The shortest length, 2.84m, was required when the initial molar concentration of propane was 2.0%. When the initial molar concentration of propane was below 2.0%, the main factor affecting the removal of propane was the condensation rate, and the required heat exchanger length increased rapidly in an approximately parabolic trend as the propane initial molar concentration decreased. When the propane initial molar concentration was higher than 2.0%, the main factor affecting the removal of propane became the total quantity of propane, and the required heat exchanger length increased approximately linearly at a smaller rate as the propane concentration increased. Present study could provide a reference to the design of the length of the heat exchanger for the condensation removal of the valuable component in petroleum gas.