Maria Arvidsson

Integration opportunities for substitute natural gas (SNG) production in an industrial process plant

This paper investigates opportunities for integration of a Substitute Natural Gas (SNG) process based on thermal gasification of lignocellulosic biomass in an industrial process plant currently importing natural gas (NG) for further processing to speciality chemicals. The assumed SNG process configuration is similar to that selected for the ongoing Gothenburg Biomass Gasification demonstration project (GoBiGas) and is modelled in Aspen Plus. The heat and power integration potentials are investigated using Pinch Analysis tools. Three cases have been investigated: the steam production potential from the SNG process excess heat, the electricity production potential by maximizing the heat recovery in the SNG process without additional fuel firing, and the electricity production potential with increased steam cycle efficiency and additional fuel firing. The results show that 217 MWLHV of woody biomass are required to substitute the site’s natural gas demand with SNG (162 MWLHV). The results indicate that excess heat from the SNG process has the potential to completely cover the site’s net steam demand (19 MW) or to produce enough electricity to cover the demand of the SNG process (21 MWel). The study also shows that it is possible to fully exploit the heat pockets in the SNG process Grand Composite Curve (GCC) resulting in an increase of the steam cycle electricity output. In this case, there is a potential to cover the site’s net steam demand and to produce 30 MWel with an efficiency of 1 MWel/MWadded heat. However, this configuration requires combustion of 36 MWLHV of additional fuel, resulting in a marginal generation efficiency of 0.80 MWel/MWfuel (i.e. comparing the obtained electricity production potentials with and without additional fuel firing).

Integration of Biomass Gasification-Based Olefins Production in a Steam Cracker Plant—Global GHG Emission Balances

This paper investigates two options for integration of biomass-based olefin production with a fossil-based steam cracker plant at the heart of a chemical cluster. The work was conducted in the form of a case study considering the possible future partial replacement of a fraction of the cracker olefins with approx. 220 kt/y of biomass-based olefins (ethylene, propylene, and butylene) (approx. 25 % of total capacity) produced via gasification, methanol synthesis, and the methanol-to-olefins (MTO) process. Two options were compared with base case operation with fossil-only feedstock: (i) purchase of methanol produced off-site, and (ii) on-site methanol production. In both cases, the MTO section was assumed to be located at the cracker site, making use of existing olefin separation equipment. Consequences of such partial feedstock substitution for the steam, fuel gas, and electric power balances of the cracker plant were investigated. Potentials for generation of steam and electric power were estimated by assuming integration with a heat recovery steam cycle. Greenhouse gas (GHG) emission balances of the proposed options were estimated by applying a system boundary expansion approach. The GHG emission reduction potentials are shown to be between 50 % and 70 %, compared with the base case. The reduction potential depends on the choice of reference grid electricity generation technology but the major contribution comes from the introduction of renewable feedstock.