Biogas to fuel by VPSA I- Behavior of equilibrium and kinetic based adsorbents

• Type: Article in International Scientific Journal
• Date: 2007

Authors

Carlos Grande (Author) FEUP; Alírio Rodrigues (Author) FEUP

Journal

Title: Industrial & Engineering Chemistry Research

Vol. 46 No. 13

Pages: 4595-4605

ISSN: 0888-5885

Publisher: American Chemical Society

Indexing

ISI Proceedings

Scientific classification

CORDIS: Technological sciences > Engineering > Chemical engineering

Other information

Resumo (PT): LANDFILL GAS; CARBON-DIOXIDE; DIFFUSIVITY; SEPARATION; ZEOLITES; NITROGEN; UPGRADE; PELLETS; METHANE

Abstract (EN): Purification of biogas by vacuum pressure swing adsorption was evaluated to produce fuel grade methane (FGM). Two different adsorbents were employed to evaluate the process performance with equilibrium- and kinetic-based adsorbents. Carbon molecular sieve 3K was employed as the example of a kinetic adsorbent because methane diffusion is extremely small. A five-step cycle configuration (feed, intermediate depressurization, blowdown, purge, and pressurization) was employed to compare with results obtained with a four-step cycle without intermediate depressurization. The effect of different operating variables like step times and pressure conditions of the cycle was analyzed. We have employed zeolite 13X as the equilibrium-based adsorbent (much higher capacity for CO2 with fast diffusion of both gases). Different operating conditions as well as a new cycle configuration were evaluated. Methane with purity over 98% was obtained with both adsorbents. The CMS 3K adsorbent showed much higher methane recovery (close to 80%) compared to those obtained with zeolite 13X (close to 60%) because of low adsorption in the pressurization step and because the stream exiting the intermediate depressurization step can be considered as being a product.

Language: Portuguese

Type (Professor's evaluation): Scientific