Optimization of technological modes of the reaction product separation column at the light paraffin isomerization plant

By the process of isomerization of light gasoline fractions, valuable components for environmentally friendly gasoline are synthesized. The products of the isomerization reaction, along with the target high-octane hydrocarbons, contain low-branched C6 hydrocarbons, the presence of which reduces the octane number of the isomerizate, therefore, in industrial conditions it is advisable to separate them from the reaction mass in order to recycle them into the reactor feed stream as one of the initial reactants of the process. In industrial conditions, low-branched paraffin C6 hydrocarbons.they are selected in a deisohexanizer column by a side run. The difficulty of separating the isomerizate components is explained by their relatively close boiling points. The work optimizes the technological mode of operation of the deisohexanizer column in order to maximize the extraction of these components into the recycle. The research was carried out using the Honeywell Unisim Design modeling program. The thermodynamic properties of the flows were calculated using the Peng-Robinson method. The calculations performed have established the technological parameters of the column, which ensure almost complete extraction of normal hexane and methylpentanes in the lateral shoulder strap in the amount of 99.99% by weight and 99.72% by weight. Accordingly, the structural parameters of the deisohexanizer column did not change. The achieved increase in the amount of raw hydrocarbons in the lateral pursuit makes it advisable to use an additional deisopentanizer column in the technological scheme of installation in order to remove isopentane from the raw materials of the isomerization reactor unit. A fragment of the technological scheme of the installation with the inclusion of a deisopentanizer column with its optimal technological and structural parameters is presented. The total calculated effect of the proposed solutions in the form of an increase in the octane number of isomerizate was 1.9 points.