e-methanol e-fuels e-alcohols acetic acid
Ole ns, aromatics, fuels
CO + CO
Heat recovery
Methanol synthesis Fischer-Tropsch process Bio process
CO + CO + N + O
Electrical heater renewable system
Choose the need process
Wind, solar
Gases separator
FCC feed waste, VGO, Bio feeds plastic recycling
N
Water
O (<21%)
Green hydrogen
CO
Energy storage for short period
Electrolyser
O
Water
Figure 3 Refining schemes in which bio-oil is fed directly to the FCC process
yield to chemicals from crude oil in an economical and envi- ronmentally responsible manner. Due to growing awareness of depleting crude oil resources, rising CO₂ levels, global warming, and secur - ing energy supply, it would be advantageous to use bio- mass-derived feedstock in existing petroleum refineries. As petroleum refineries are already in place, the use of this infrastructure to produce fuels and base chemicals, such as propylene from biomass, requires, in principle, relatively little investment costs. An attractive and already explored option is the co- processing of biomass-derived oxygenates with petro- leum-derived fractions, such as VGO. FCC processing of biomass-derived oxygenates gives products with higher hydrogen content than the starting biomass-based feed- stock by removing oxygen as carbon monoxide and carbon dioxide, next to an increased amount of water. In addition, higher amounts of carbon deposits are found on the FCC catalyst material, which then can be burned off in the regenerator to produce process heat. Alternatively, the coke deposits formed by co-processing biomass with VGO during FCC operations can be converted into syn- thesis gas (CO + H₂), which can be used elsewhere in the oil refinery. Co-processing routes The co-processing of bio-oil and fossil streams in the cata- lytic cracking process has been considered a promising route for advanced fuel production. FCC is a conversion process that is present in most petroleum refineries. Its flexibility allows the operating conditions and catalyst to be adjusted to maximise other products, such as propylene. 2-4 Figure 3 illustrates proposed refining schemes in which the bio-oil is fed directly to the FCC process, bypassing the refinery atmospheric and vacuum distillation towers
(i.e., crude oil fractionation). The co-processing of bio-oil and VGO in the FCC has already reached the demonstra- tion scale, which offers a better understanding of bio-oil co-processing. The FCC demonstration-scale unit used in many bio-oil co-processing studies in the literature has been intensively employed for many years to develop FCC technologies. 5 Some of Figure 3 ’s features stand out, such as the pos- sibility of using one or more of its multiple injection feed points positioned along the riser reactor. Different points of injection in the riser are common practice for fossil gaso- line or LCO/HCO recycling and involve the use of closed cyclones to separate the hydrocarbon products from the catalyst. Consequently, in these studies, bio-oil could be segre- gated from conventional FCC feedstocks by introducing it into the reactor separately. The tests carried out in demon- stration-scale units using this method allowed production of sufficient volumes of diesel and gasoline, which were then hydrogenated to reduce sulphur and meet US specifi - cations (for example). Both fuels have obtained certification in the US. The tests were carried out in a demonstration-scale FCC unit (total capacity of 200 kg/h). The renewable-carbon content was measured in the product samples obtained from co-processing VGO with 5%, 10%, and 20% bio-oil (by weight). The VGO feed temperature ranged from 220ºC to 320ºC, and two reaction temperatures were used: 540ºC and 560ºC. The catalyst circulation rate may be adjusted by chang- ing the feed preheater temperature to achieve a set reactor outlet temperature (reaction temperature). The bio-oil was injected separately from the VGO at an injection point axi- ally below the VGO injection point, at the base of the riser reactor. The regenerated catalyst temperature was kept at
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PTQ Q3 2022
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