Stabilising the wet end in paper mills
Closed water systems have been developed in the paper-making industry to cut the demand for fresh water, an advantage economically and ecologically. The downside to this is the accumulation of impurities and dissolved materials in the so-called wet end of paper mills. The forming section, commonly called the wet end, is where the slurry of fibres is filtered out on a continuous fabric loop to form a wet web of fibre. Accumulation of dissolved and colloidal material (DCM) costs the industry in Europe up to EUR 1 billion a year, largely through instability, corrosion and explosions that cause downtime in paper machines. Avoiding these economic losses through optimised and more stable wet end systems is essential for smaller paper mills if they are to remain competitive against their bigger rivals which benefit from economies of scale. The project 'A smart homogenization approach improving process knowledge and papermaking competitiveness' (Shaker) is an EU-funded initiative involving small and medium-sized enterprises (SMEs) from several countries. Shaker researchers have developed a preventative approach to avoid problems in paper mill water systems. These largely stem from bad homogenisation and fast de-mixing of the water/pulp mixture in dead zones in tanks and pipes. These areas of stagnant water result in high anaerobic activity and an increased amount of microorganisms in the mixture, causing process instability. Shaker’s main innovation is an improved homogenisation concept which should help to avoid these dead zones and reduce the amount of impurities in the system. The new system is based on an optimised mixing chest (tank), working towards a constant wet end and totally chest-free system in paper production. Project partners estimate potential reductions of 20 % in energy, natural gas and water, some 5 % less wood will be used and 25 % less chemicals consumed. Further improvements are also possible in plant productivity and final product quality. Shaker partners have been working towards the commercialisation of the system. Market research and the definition of proper routes for dissemination and exploitation of the results have already been completed. The new system promises to maintain a competitive edge for Europe over the Far East, South America and the United States.