Replacement of the evaporating agent on the K-1 column of the primary oil refining unit

An apparatus (separator) for the preliminary separation of hydrocarbons, which removes part of light hydrocarbons and partially a fraction of light gasoline, or a column for partial oil refining K-1, can be included in the scheme of primary oil refining units. Preliminary fractionation in these devices is essential for the resource saving of the enterprise, since such schemes ensure a reduction in heat consumption for heating crude oil before fractionation in the main atmospheric column. The efficiency of the K-1 column is influenced not only by the quality of oil, technological modes and structural parameters of the apparatus, but also by the evaporating agents used. The paper shows the possibility of using its distillate in the K-1 column instead of water vapor with the organization of heat recovery by column flows and compares the achieved performance of the apparatus using these evaporating agents. The research was carried out using the UniSim Design modeling system. A comparative assessment of the use of various evaporating agents was carried out taking into account the quality and yield of fractions from the top of the K-1 column. The results of the computational experiment showed that the sensitivity of the K-1 column (fractional distillate composition) to varying the temperature of the recirculating distillate supplied to the column to 160 °C is low, that is, there is no noticeable change in the fractional composition of the distillate, and at temperatures above 160 °C the composition practically does not change. The appropriate amount of distillate recycled into the column as an evaporating agent is ~ 1% by weight. from the consumption of raw materials. The calculated temperature curves for the height of the column have a similar characteristic appearance, although the temperatures of the top and bottom of the apparatus (69.8 °C and 226.1 °C) differ from the corresponding column temperatures using water vapor (54.6 °C and 187.1 °C). When using the distillate of the column as an evaporating agent, a clear partial oil refining is achieved, there is no "humidification" of the output streams and an increase in the content of nk-180 °C fractions in the distillate stream is observed. The latter is important for technological schemes that use a gasoline secondary distillation unit for fractions nk-80°C, 60-90 °C and 80-180 °C. To heat the distillate before it is fed to the bottom of the K-1 column, heat recovery by the flows of the main atmospheric column is possible.