Landfill gas valorization: biomethane for natural gas grid injection
Résumé
This work focuses on optimal management of landfill gas from an economic and environmental sustainability perspective. The main objective is to propose the most effective treatment operations for all stages of the process and a flowsheet allowing the simulation of landfill biogas valorization based on the final composition of biogas injection pressure and its obviously dependent specifications imposed by the network manager. Thus, our work led to the development of two processes whose performances were compared to upgrade biogas to biomethane for injection in the natural gas grid. The first process includes chemical absorption of H 2 S with H 2 O 2 , condensation technique for water vapor removal, and cryogenic distillation to separate CH 4 from CO 2 , O 2 and N 2. The second process consists from physical absorption with H 2 O to remove simultaneously CO 2 and H 2 S, dehumidification with TEG (Triethylene glycol) to remove water and cryogenic distillation to separate CH 4 from N 2. Our results show that both processes fully meet the specification requirements (purity >97% CH 4). However, the biomethane quality produced by the second process is higher, and the electric energy consumption is lower. The methane recoverable fraction is 98.2 instead of 97.3% and electricity consumption value is 0.18 instead of 65.5 kWh/m 3. .