into a standard petroleum refinery. Syngas may also be produced.
FFHydrothermal processing: Uses high pressure and moderate temperature to initiate chemical decomposition of biomass or wet waste materials to produce an oil that may be catalytically upgraded to hydrocarbon fuels.
FFGasification: During this process, biomass is thermally converted to syngas and catalytically converted to hydrocarbon fuels.
Co-processing optimises the value chain Where conversion of biomass into biofuels is done in existing refineries, this is termed co-processing. Many refineries operate below their capacity, making co-processing a viable option to meet sustainability goals and maximise production without making expensive investments in refining assets. Most co-processing happens in hydrotreaters, hydrocrackers, or fluid catalytic crackers. These catalytic processes remove sulfur, oxygen, nitrogen, and metals. It is critical to remove sulfur as this reduces SOX emissions when fuels are combusted; sulfur also poisons downstream noble metal reformer catalysts (<0.5 ppm S is a typical naphtha feed spec). This clean-up also saturates olefins to yield easier-to-process intermediates. The reaction is carried out in a hydrogen-rich environment over a fixed catalyst bed, and the replacement of sulfur or nitrogen contaminants with hydrogen makes the process a
Figure 2. Biofuels power plant with wood biomass.
Figure 3. Biomass processing plant.
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consumer of hydrogen. Protection of the heat exchangers and catalyst beds from fouling is critical to maintaining long-term hydrotreating efficiency. Treated products are then stabilised with heat to remove hydrogen sulfide and light ends. Use of direct steam injection is common.
Why is filtration critical to biofuel production? Despite pre-treatment, biomass tends to degrade during transportation and storage. These particulate impurities and gels can cause severe damage to downstream equipment if left unfiltered. In addition, biomass typically contains an abundance of oxygen that gets converted into carbon monoxide, carbon dioxide, and water during hydroprocessing. Depending on the type and proportion of the feedstock inserted into the refinery for the production of liquid biofuels, the volume of gaseous products and moisture generated may differ significantly and impact refinery operations. Some of the challenges include: pressure build-up over the catalyst bed and heat exchanger; additional hydrogen demand; higher gas treatment and removal capacity required; and removal of additional co-produced water. The increased risk of moisture and contamination in catalysts and critical equipment due to biomass processing may lead to frequent downtime to repair or replace these expensive pieces of technology. In addition to solid particulate removal, separation of water from the final biofuel product is an essential step in the biofuel refinery process. To achieve premium diesel quality, Pall liquid/liquid coalescers can be installed downstream of the hydrotreater to separate and remove water content to an acceptable level. For example, a major EU producer of biodiesels and sustainable aviation fuels (SAF) uses Pall Aquasep XS liquid/ liquid coalescer filters to polish the refined biodiesel product to an acceptable water content specification of <100 ppm. The coalescer media agglomerates water molecules as the biodiesel flows through it, creating larger water droplets that can be separated from the feed fluid. The dense coalescer media provides optimum separation capacity (typ. ≤15ppm separation level achievable), protected by appropriate particulate pre-filters that can retain the gels and waxes that might otherwise blind and therefore reduce coalescer performance. The production of biogas happens through anaerobic technology and consists mainly of methane and carbon dioxide. However, it can also contain small amounts of hydrogen sulfide, siloxanes, and moisture, all of which can have a detrimental effect on the production process. To maximise methane output and protect critical equipment such as compressors and membranes, it is important to eliminate as many impurities as possible through particle filtration and liquid/gas coalescence methods. Without efficient filtration and separation technologies, heavily contaminated gases can lead to compressor corrosion, abrasion in moving parts, and degradation of purification units. In the processing of both liquid biofuels and biogas, investing in an efficient, high-quality filtering system is essential to protect downstream equipment and to ensure installations run smoothly with less downtime. Where poor filtration and
