Методика прогнозирования степени улавливания паров углеводородов при абсорбции

Abstract

Over the years of practical use of absorption, various methods for calculating absorbers have been developed. Among others, the calculation of mass transfer processes was created based on the use of a so-called mass transfer coefficient β, showing how much mass of the target substance passes from the gas phase to the liquid one through a surface area unit per time unit. To determine β, empirical equations are used depending on their validity for a particular type of absorber and operating conditions given. However, these calculations are relatively complex and fail to be applicable to whatever absorber design used. The calculations of phase transitions using phase equilibrium constants do not depend on the design features of the equipment where mass transfer occurs. However, to date, the phase equilibrium theory has been applied to calculate the separation of a multicomponent mixture under no air condition; therefore, it could not be used to predict phase transitions when a gas-air mixture contacts a liquid absorber. Based on the theory of phase transitions, the authors developed a simplified method for predicting the degree of oil vapor recovery at absorption. The technique was successfully tested through calculating the efficiency of the jet absorption unit used to recover oil vapor. Also, the installation performance at absorbent replacement was simulated. The replacement of easily volatile oil used as a working fluid with oil of a lower saturated vapor pressure was shown to significantly increase the degree of hydrocarbon vapor recovery. The possibility of applying the technical solution is limited with the following conditions: low-volatile liquids used as absorbent cannot be highly viscous and have a high pour point; their quality should not deteriorate when absorbing oil vapor; the cost of replacing the working fluid should be reasonable.