Abstract: An experimental study of the extent of axial backmixing in both gas and liquid phases was
conducted in a 150 mm ID column packed with Mellapak 250Y corrugated structured packing.
The column was operated at pressures ranging from 0.3 MPa to 2.0 MPa with nitrogen and
water flowing countercurrently through the packing.The amount of axial backmixing was
experimentally evaluated by the pulse response techniques using hydrogen in gas phase and
an aqueous solution of NaCl in liquid phase as inert tracers. The response of the tracer
was monitored by means of thermal conductivity in the gas phase and electrical conductance
in the liquid phase. The experimentally determined residence time distribution (RTD) curves
were interpreted in terms of the diffusion-type model. The results indicated that the axial
backmixing in the gas increased notably with gas flowrate and slightly with operating
pressure and liquid flowrate. The liquid-phase axial backmixing was an increasing function
of both gas and liquid flowrates and insensitive to pressure. Various correlations were
developed for reproducing the experimental mixing data. The agreement between experimental
and correlated data appeared to be acceptable and within +20% of difference.

Key words: structured packing, backmixing, elevated pressure, gas-liquid two-phase flow

摘要： An experimental study of the extent of axial backmixing in both gas and liquid phases was
conducted in a 150 mm ID column packed with Mellapak 250Y corrugated structured packing.
The column was operated at pressures ranging from 0.3 MPa to 2.0 MPa with nitrogen and
water flowing countercurrently through the packing.The amount of axial backmixing was
experimentally evaluated by the pulse response techniques using hydrogen in gas phase and
an aqueous solution of NaCl in liquid phase as inert tracers. The response of the tracer
was monitored by means of thermal conductivity in the gas phase and electrical conductance
in the liquid phase. The experimentally determined residence time distribution (RTD) curves
were interpreted in terms of the diffusion-type model. The results indicated that the axial
backmixing in the gas increased notably with gas flowrate and slightly with operating
pressure and liquid flowrate. The liquid-phase axial backmixing was an increasing function
of both gas and liquid flowrates and insensitive to pressure. Various correlations were
developed for reproducing the experimental mixing data. The agreement between experimental
and correlated data appeared to be acceptable and within +20% of difference.

关键词: structured packing;backmixing;elevated pressure;gas-liquid two-phase flow