Use of a fractionation system for removing heavy hydrocarbons in a gas stream, comprising: a feed gas inlet configured to introduce a feed gas stream through it; a stripping section configured to receive a predominantly liquid phase of the feed gas stream; and first and second co-current contacting systems (200, 421a, 421b, 600) located in-line within a pipe, the first co-current contacting system (200, 421a, 600) configured to receive a predominantly vapor phase of the feed gas stream, each of the first and second co-current contacting systems (200, 421a, 421b, 600) comprising: a co-current contactor including a droplet generator (208, 428a, 612a-n) and a mass transfer section (210, 430a), the droplet generator (208, 428a, 612a-n) configured to generate droplets from a liquid and to disperse the droplets into a gas stream, and the mass transfer section (210, 430a) configured to provide a mixed, two-phase flow having a vapor phase and a liquid phase; and a separation system (222, 633) configured to separate the vapor phase from the liquid phase; wherein the system is configured such that the vapor phase of the co-current contactor in the first co-current contacting system (200, 421a, 600) comprises the gas stream for the co-current contactor in the second co-current contacting system (200, 421b, 600), and wherein the system is configured such that the liquid phase of the co-current contactor in the second co-current contacting system (200, 421b, 600) comprises the liquid (212, 438b) from which droplets are generated in the co-current contactor of the first co-current contacting system (200, 421a, 600). a feed gas inlet configured to introduce a feed gas stream through it; a stripping section configured to receive a predominantly liquid phase of the feed gas stream; and first and second co-current contacting systems (200, 421a, 421b, 600) located in-line within a pipe, the first co-current contacting system (200, 421a, 600) configured to receive a predominantly vapor phase of the feed gas stream, each of the first and second co-current contacting systems (200, 421a, 421b, 600) comprising: a co-current contactor including a droplet generator (208, 428a, 612a-n) and a mass transfer section (210, 430a), the droplet generator (208, 428a, 612a-n) configured to generate droplets from a liquid and to disperse the droplets into a gas stream, and the mass transfer section (210, 430a) configured to provide a mixed, two-phase flow having a vapor phase and a liquid phase; and a separation system (222, 633) configured to separate the vapor phase from the liquid phase; a co-current contactor including a droplet generator (208, 428a, 612a-n) and a mass transfer section (210, 430a), the droplet generator (208, 428a, 612a-n) configured to generate droplets from a liquid and to disperse the droplets into a gas stream, and the mass transfer section (210, 430a) configured to provide a mixed, two-phase flow having a vapor phase and a liquid phase; and a separation system (222, 633) configured to separate the vapor phase from the liquid phase; wherein the system is configured such that the vapor phase of the co-current contactor in the first co-current contacting system (200, 421a, 600) comprises the gas stream for the co-current contactor in the second co-current contacting system (200, 421b, 600), and wherein the system is configured such that the liquid phase of the co-current contactor in the second co-current contacting system (200, 421b, 600) comprises the liquid (212, 438b) from which droplets are generated in the co-current contactor of the first co-current contacting system (200, 421a, 600).