A comparison of BSL Process benefits to other fractionation techniques by CITeD Ltd., an independent scientific innovation consultancy
Low Energy and Improved Safety
In comparison to ‘standard’ organosolv fractionation, the BSL process uses significantly lower temperatures and pressures: the system operates 60-80 °C lower than common organosolv processes, at pressures of 3-5 bar as opposed to 10-15 bar. This reduces both CapEx and OpEx costs and makes the process equipment safer to operate. The BSL process also does not need ethanol or acetone for fractionation, further reducing OpEx costs and improving safety. Strong mineral acids are not required (unlike the Kraft process), with only a catalytic amount of an organic acid needed.
Faster and more Efficient
Although not completely optimised, fractionation using BSL technology is complete in around 2 hours (ignoring heat-up and cool-down times). Traditional organosolv processes run for 4 to 8 hours. The BSL process can be run in batch-continuous mode through the addition of reactor modules making fractionation more efficient.
The relatively mild processing conditions in the BSL system do not lead to decomposition of the valuable products; hemicelluloses sugars are recovered without hydrolysis or decomposition, lignin is recovered without extensive depolymerisation or sulfonation and cellulose is recovered without damage. Non-sulfonated lignin is currently not widely available and the BSL process could open up exciting new opportunities for this product.
Low Waste and low CO2 Emissions
The BSL process generates almost zero waste – the only component that is currently not recoverable is the organic acid catalyst. The processing solvents (water and MiBK) can be filtered or distilled for reuse and all components of the incoming wood stream can be recovered as products. Combining low-temperature operation of the plant with highly efficient ultrasound fractionation means overall CO2 emissions through operation are currently similar to standard organosolv or pulping (approximately 1 tonne of CO2 emitted per tonne of feedstock processed.) Once further optimised and including the economies of scale-up, the BSL process is likely to emit less CO2 than its competitors.
Tuneable for Different Feedstocks
The use of ultrasound allows the process to be tuned to be most efficient depending on the feedstock. This level of processing refinement is not possible in other fractionation systems.
The BSL process has been operating at pilot-scale for over 4 years and is now ready to move to pre-production scale. Most organosolv competitors remain at laboratory or pre-pilot scale.
Dr Andrew West CChem. CSci. MRSC