Chemical pulping

Abstract

A conceptual ethanol production plant, based on conversion of a kraft pulp mill, has been studied. The process uses softwood as raw material, alkaline pre-treatment combined with delignification, and biochemical conversion of sugars to ethanol (i.e. hydrolysis and fermentation). The plant has been analysed by pinch methods in order to find steam-saving possibilities. It is shown in the study that a large amount of steam surplus can be found if energy efficiency measures are implemented. In order to study the possible effect on the profitability of the plant when introducing steam-saving measures, the process has been analysed from a techno-economic point of view. It is shown that implementing energy efficiency measures could have a substantial effect on profitability if the by-product (in this case lignin biofuel or power) is high-valued. It is also shown that lignin as by-product might be more profitable than power, mainly because the demand for CO 2 in lignin extraction might be supplied by CO 2 produced in fermentation of sugars to ethanol. If investments are made to convert a pulp mill to ethanol production, energy efficiency measures should be included in the discussion since they might play an important role in minimising ethanol production cost.

Excellence in Excrements: Upcycling of Herbivore Manure into Nanocellulose and Biogas

“…AD prior to chemical extraction resulted in a yield reduction (21% for 5 days AD to 12% for 20 and 30 days of AD). Wood as raw material using the established Kraft process has yields of 46–50%, which seems significantly higher. , But it needs to be pointed out that already biogas in high yields is produced from the fermentation residue and that this is a low-grade biomass compared with wood. Cellulose could be extracted from cow manure with a yield of 11% without prior AD, which is similar to elephant manure after 20–40 days of anaerobic digestion …”