November 2019

Increased efficiency

GIG Karasek impresses Sappi once again with conversion of evaporation system at Alfeld plant

At its site in Alfeld, Sappi uses an acidic magnesium bisulphite process to produce high-quality bleached TCF pulp for the purposes of making special paper. The company is currently facing challenges in relation to the reduction of chemical oxygen demand in wastewater as well as reduced performance of the evaporation system in recent years. At the same time, it is looking to boost efficiency and improve system cleaning.

GIG Karasek was commissioned to find a solution to all of these challenges, as it had already managed to solve similar problems at other plants in the past. Specialist knowledge is crucial when it comes to the evaporation of spent sulphite liquor, and the experienced system builder has spent decades accumulating a wealth of expertise in this area. GIG Karasek was able to provide Sappi with an innovative process solution that minimises downtime.

The project team from Sappi decided to commission GIG Karasek to carry out the expansion work because of the flexibility demonstrated by the company during the tender phase with regard to responding to our needs. GIG Karasek was willing to work through a number of different scenarios with us in order to find the right cost-benefit-optimised solution. The decision was also influenced by the success of other projects that have been implemented at various Sappi sites in recent years.”

In the future, Sappi Alfeld will be switching from the 5-stage thermal evaporation system to a 6-stage system, with the possibility of expanding to a 7-stage version in the final configuration. This will result in maximum energy efficiency. Two new evaporation stages – featuring a falling film design which is ideally suited to the process in question – will be manufactured, delivered and installed by GIG Karasek. The centrepiece of the system is the heating elements, which are produced to the highest quality standards at GIG Karasek’s site in Austria. GIG Karasek has come up with an ideal cleaning concept involving chemical cleaning methods in order to maximise operating times. This requires in-depth process expertise in order to ensure that the desired effect is achieved and all necessary safety measures are fulfilled. A similar cleaning concept – successfully implemented by GIG Karasek – is already in use at Sappi Ehingen.

Alongside the new installation, the existing system also needs to be inspected and upgraded and individual components need to be replaced. The integration of the new system into the existing installation also represents an important project milestone. This requires excellent project management and coordinated production and logistics – all of which GIG Karasek can take care of in house. GIG Karasek has its work cut out at the moment as the first stage of conversion work is coming up in November during a short shutdown period.

Sappi Alfeld



Sappi is a global company that sells paper-based and biorefinery solutions as well as chemical pulp and paper pulp solutions to customers in over 150 countries. These solutions are used in applications including textiles, healthcare, graphic papers and packaging.

Furthermore, Sappi is leading the way in the field of technological innovation. The company is investing in an ambitious research and development programme which will enable it to harness the potential of sustainable renewable resources – primarily in the form of wood fibres – to an impressive extent in the future. This means that, in an age of regulated carbon emission values, Sappi will be able to diversify its portfolio and meet the growing demand in fields such as bioenergy and pharmaceuticals.