FIELD: chemistry.
SUBSTANCE: invention relates to a method of removing a fraction with high nitrogen content from a starting fraction primarily containing nitrogen and hydrocarbons. The starting fraction is partially condensed and divided by fractionation into a fraction with high nitrogen content and a fraction with high methane content. According to the invention, during cut-off of the supply of the starting fraction being fed for fractionation, the separation column(s) (T1/T2) and heat exchangers (E2) serving for partial condensation (E1) of the starting fraction and cooling and heating process streams formed during fractionation are kept, through one or more different coolants (6-11), at temperature levels substantially corresponding to temperature levels during the normal operating mode of the separation column(s) T1/T2) and heat exchangers (E1, E2).
EFFECT: improved method.
2 cl, 4 dwg
