ie503243f_si_001.pdf (204.32 kB)
Upgrading Biogas at Low Pressure by Vacuum Swing Adsorption
journal contribution
posted on 2015-01-14, 00:00 authored by Aarti Arya, Swapnil Divekar, Ruchika Rawat, Pushpa Gupta, Madhukar O. Garg, Soumen Dasgupta, Anshu Nanoti, Ranjeet Singh, Penny Xiao, Paul A. WebleyPerformance of four adsorbents (three
zeolites and one molecular
sieve carbon) for CO2–CH4 separation
from simulated biogas feed containing 42% CO2 (balance
methane) is compared in a simple four step dual bed vacuum swing adsorption
(VSA) cycle. The VSA cycle consisted of four sequential steps in each
column namely adsorption, cocurrent depressurization, evacuation and
pressure equalization. Among the adsorbents tested, zeolite NaUSY
appears to give the best results for producing pipeline grade methane
(>98%) at recoveries exceeding 85%. The methane productivity obtained
by the present process is in the range of 11–16 mol/h/kg, which
is considerably higher than the literature reported values with zeolite
and carbon based adsorbents. The high methane productivity of the
present process is due to the absence of purge step during regeneration
with methane rich adsorption product as well as due to absence of
any blow down step in the VSA cycle. Another advantage of the present
process is that operation for biogas up-gradation is at near atmosphere
pressure, which is typically the pressure available for biogas generated
from an anaerobic digester.