Decarbonisation Technology May 2022 Issue

Light gases

EE to export

Autothermal reforming

Power generation

Light gases

Recycle gases

Biomass

FT-synthesis o ff-gas

IP steam

Gasication & tar cracking

HTHR & gas cleaning

Acid gas removal

Fisher-Tropsch synthesis

Syncrude rening

Product rening

Ash

Sustainable aviation fuel

Marine diesel oil

Particulate Water to WWT

Solvent regeneration

H production

Air separation

CO t reat. & compression

Air

CO to storage

Option

Figure 1 Biomass to liquid process setup

Union’s Horizon 2020 research and innovation programme under grant agreement N° 884197. Case study In the context of the GLAMOUR project, Siirtec Nigi developed the benchmark against which to compare the new technology. In order to find out the conditions for the economic viability of investments in BTL-FT processes, the case for the production of 1.5 MMbbl/y of middle distillates from 149.2 t/h of herbaceous biomass was modelled. Table 1 shows the main properties of the biomass fed to the plant. The plant setup is shown in Figure 1 . The plant front-end consists of the chopping of herbaceous feedstock followed by feeding via lock-hoppers. The syngas from biomass is produced by a dry- fed, oxygen/steam-blown fluidised bed gasifier operating at 30 bar. An on-site air separation unit provides the O 2 . The tar-free gas from the gasification unit is then cooled in the high-temperature heat recovery (HTHR), where high-pressure steam is raised to be sent to the power generation section. For this case study, the gasification was designed to deliver syngas with an H 2 :CO ratio of about 2. 114 t/h of CO 2 is removed in an acid gas removal process and vented in the base case. Alternatively, this CO 2 is compressed, dehydrated, and delivered to an underground storage facility.

The FT design is based on the slurry-phase reactor, which enables a high heat transfer, resulting in the high conversion of feed gas to liquids in a relatively small reactor volume without excessive temperature rise. The syncrude is distilled to split naphtha, distillate, and wax. The naphtha stream is first hydrotreated, resulting in the production of hydrogen-saturated liquids (primarily paraffins). The distillate stream and the wax fraction are also hydrotreated, resulting directly in the finished products. A slipstream of the light gases (C 1 -C 4 ) separated from the syncrude is used as fuel gas in the power generation block, while most of them are mixed with unconverted syngas and the off-gas from the H 2 production section and recycled back to the FT synthesis through the autothermal reformer to maximise the liquid fuel production. About 66 MW of electric power is being generated in the power generation, with two- thirds of this power being used to meet internal power demand, while the balance is delivered to the electric grid as a by-product. For this case study, the economic viability has been assessed by: • Fixing a preset rate of return (RR) on investment and the CO 2 price ($80/tons as per the average January 2022 ETS) • Varying the price of the synfuels products expressed in terms of barrel of oil (Brent) equivalent (BBE) or crude oil equivalent (CEO)