Objectives and problems to be solved:
The main objective of the project is to increase the production of green electricity from the spent liquors of a new wood pulping process as an integral part of the fibre manufacture. This target is to be achieved by the adaptation of a new sulphur-free pulping process, which produces spent pulping liquors that are easier to gasify or fire in high pressure recovery boilers than the sulphur containing traditional kraft pulping black liquors. With traditional kraft pulp processing of chips to papermaking fibres the problem is the low amount of excess electrical energy obtained during the recovery of the cooking chemicals. If the spent pulping liquor could be gasified (or combusted in a high efficiency steam boiler), the excess amount of electricity would be about 1500 kWh per ton of the pulp produced (or 900 kWh per ton of pulp in the case of high efficiency recovery boiler). This is 3 to 5 times more than the excess electricity obtained in today's modern pulp mills. It is important to observe that this electricity is green, i.e. it is produced from renewable bio-resources. Description of work: The project is divided into three phases:
1. Pulping and bleaching studies of selected hardwood species,
2. Laboratory-scale studies on energy production (and on recovery of cooking chemicals) from the spent liquors of the new sulphur-free pulping process, and
3. Feasibility study of energy production and of cooking chemicals recovery using data from phase 2. The traditional kraft pulping process is used as a bench marking reference for the above feasibility studies. Expected Results and Exploitation Plans: The main results of this project can exploited to justify large-scale piloting of these new power generation processes in conjunction with the recovery of pulping chemicals. The results of this project do not yet warrant a direct expansion to a full-scale commercial process. The socio-economic significance of the eventual commercial scale green power production as an integral part of the pulp production is that European pulp industry could easily produce 3000 MW green electricity, i.e. about 1 % of EU's overall peak electricity demand. For countries having a significant pulp and paper industry, the results of this project could mean that an additional 10 % of the national electricity consumption could be supplied by this green electricity method. In addition, the new technology that will be developed could be exported to important areas of pulp production, i.e. to North America, South America, and South-East Asia thus providing markets and jobs for the European equipment suppliers.
Optimal conditions for sulphur free IDE cooking and bleaching was determined. Laboratory scale and pilot scale cooking trials proved that significant increase in yield is attainable with birch and eucalyptus. IDE pulps were shown to be more difficult to bleach than the Kraft pulps with conventional bleaching sequences. The quality of IDE pulps were compared to Kraft pulps using advanced laboratory facilities and pilot paper machine. Based on analyses and visual evaluations paper technical properties of papers produced from IDE pulps were equal and some even slightly better than those of Kraft reference. Some properties make an interesting combination for end users in special applications as for printing and writing types of paper. A kinetic model to describe the reactions of delignification and of degradation of carbohydrates during the cooking process was determined.
With a correlation between MIR and NIR spectra the parameters for on-line monitoring of the delignification reactions could be accessed. The analysed chemical and physical properties of IDE spent liquors confirmed the potential of recovery of chemical and energy with high efficiency in the sulphur free pulping process. Two alternative recovery processes for IDE spent liquor were outlined: advanced recovery boiler and Integrated Gasification Combined Cycle (IGCC). Potential on increased production of green electricity was proved for both alternatives. Techno-economic evaluation of the overall IDE mill process showed that sulphur free IDE process is an economically feasible option for new hardwood mills. Reasonable payback periods are achievable with both of the studied recovery process alternatives. Improved product capability, higher product differentiation, highly environmentally sound processes, odor free emissions, production of more green electricity, higher profitability and shorter payback times could attract capital and motivate the investment decision for a Greenfield mill.
Funding SchemeCSC - Cost-sharing contracts