title: Measurement of residence time distribution of liquid phase in an industrial-scale continuous pulp digester using radiotracer technique.
abstract: A series of radiotracer experiments was carried out to measure residence time distribution (RTD) of liquid phase (alkali) in an industrial-scale continuous pulp digester in a paper industry in India. Bromine-82 as ammonium bromide was used as a radiotracer. Experiments were carried out at different biomass and white liquor flow rates. The measured RTD data were treated and mean residence times in individual digester tubes as well in the whole digester were determined. The RTD was also analyzed to identify flow abnormalities and investigate flow dynamics of the liquid phase in the pulp digester. Flow channeling was observed in the first section (tube 1) of the digester. Both axial dispersion and tanks-in-series with backmixing models preceded with a plug flow component were used to simulate the measured RTD and quantify the degree of axial mixing. Based on the study, optimum conditions for operating the digester were proposed.
authors.affiliation: Department of Chemical Engineering, Thapar University, Patiala 147004, Punjab, India.
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Sheoran
authors.affiliation: Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
authors.forename: Sunil
authors.initials: S
authors.lastname: Goswami
authors.affiliation: Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai 400085, India. Electronic address: hjpant@barc.gov.in.
authors.forename: Harish J
authors.initials: HJ
authors.lastname: Pant
authors.affiliation: Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
authors.forename: Jayashree
authors.initials: J
authors.lastname: Biswal
authors.affiliation: Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Sharma
authors.affiliation: Department of Chemical Engineering, Thapar University, Patiala 147004, Punjab, India.
authors.forename: Avinash
authors.initials: A
authors.lastname: Chandra
authors.affiliation: Department of Chemical Engineering, Thapar University, Patiala 147004, Punjab, India.
authors.forename: Haripada
authors.initials: H
authors.lastname: Bhunia
authors.affiliation: Department of Chemical Engineering, Thapar University, Patiala 147004, Punjab, India.
authors.forename: Pramod K
authors.initials: PK
authors.lastname: Bajpai
authors.affiliation: Satia Industries Limited, Sri Muktsar Sahib 152101, Punjab, India.
authors.forename: S Madhukar
authors.initials: SM
authors.lastname: Rao
authors.affiliation: Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
authors.forename: A
authors.initials: A
authors.lastname: Dash
keywords: Axial dispersion model; Bromine-82; Mean residence time; Plug flow component; Pulp digester; Radiotracer; Residence time distribution; Tanks-in-series with back-mixing model