On the Local Filtration Properties of LignoBoost lignin: Studies of the influence of xylan and ionic strength
compressible filter cake
local filtration properties
Chalmers, Kemi och kemiteknik, Kemiteknik, Skogsindustriell kemiteknik
of consumer material commodities: it is an abundant and renewable resource that does not
compete directly with the production of food. Moreover, the current dominant wood-based
industries, i.e. mills that produce paper pulp via the Kraft process, generate an energy surplus
that is not generally utilized to its full potential. Only about half of the wood is actually used
for the production of the paper pulp, while the main organic by-product, lignin (an aromatic
polymer), is currently used almost exclusively as an on-site biofuel. Yet the total amount of
lignin generated in modern pulp mills contains more energy than is required internally in the
process. A promising opportunity thereby presents itself to modern Kraft pulp mills: the
implementation of technologies that enable the surplus lignin to be extracted and converted into
a wide range of value-added products and chemicals. The conversion of lignin into carbon fibres
is, for example, the focus of a large number of on-going investigations.
The LignoBoost process is a new, commercially-implemented, technology designed to extract
lignin during the Kraft process with a high degree of purity. Filtration is one of the main steps
of the LignoBoost process; the aim of this work is to improve the efficiency of the filtration
stage of the LignoBoost process further. The influence several parameters have on the filtration
of lignin was therefore investigated, and included the content of xylan (a sugar polymer which
is also present in the by-product stream of Kraft pulp mills) and the concentration of salt.
Furthermore, the filtration apparatus used in this work allows for the determination of local
filtration data, something that is not very common in the field of filtration: it is usually average
filtration data, which is easier to determine, that is considered. Local data provides nevertheless
a basis for a much better modelling of the filtration process and thereby also allows for a better
design of the filtration unit.
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4337
Chalmers tekniska högskola
KC-salen, Kemigården 4, Chalmers.
Opponent: Professor Eugene Vorobiev, Université de Technologie de Compiègne (UTC), France