Effect of kraft cooking methods on bleachability of Eucalyptus camaldulensis pulp | |
| Author | Fatehi, Pedram |
| Call Number | AIT Thesis no.PP-05-06 |
| Subject(s) | Wood-pulp--Bleaching Eucalyptus camaldulensis Pulp mills |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Continuous and batch digesters have been used for a long time in pulp mills. So far to increase their efficiency in terms of yield and delignification as well as reducing cost and better adjusting with recovery section, a lot of modifications have been done. As a result these digesters have different temperature and alkali profiles as well as cooking time. These cooking variables change the kinetics of delignification and hydrocarbon degradations. In order to understand better the differences between these pulps a research has been done some eucalyptus camaldulensis chips, ITC and Superbatch made pulps were collected at the same time from a mill. (The kappa number of ITC and Superbatch was fairly close together). Then, two laboratory cooked pulps at 165°C and 155°C (cooking time 90 and 225 min. respectively), at the same H factor, with having close kappa number and viscosity with mill made pulps were made at different Effective Alkali. Then all pulps were oxygen delignified, and then half of pulps were pretreated by acid stage. After that, all pulps were bleached with two different sequences: DEpD and ZEpD. With sequence DEpD 0.15, 0.20 and 0.25 kappa factors were chosen to find out the best kappa factor in term of bleachability for each pulp. Meanwhile, at each stage of bleaching HexA, viscosity, brightness and kappa were measured. After all, bleachability was analyzed. The result showed that ITC had the best bleachability and the highest brightness ceiling among bleached in DEpD sequence and Superbatch had worse bleachability. Meanwhile ITC pulp had highest HexA content and Superbatch pulps had lowest HexA content. Also, kappa factor of 0.20 was the best to get target brightness in all pulps. With ZEpD sequence, ITC pulp had the highest brightness and Superbatch pulp had higher brightness than laboratory cooked pulps. Moreover, acid stage was not very efficient to remove HexA. However, it did increase the final brightness of pulps and decreased the chlorine dioxide charge but bleachability was deteriorated a little bit. Also, with DEpD and ZEpD sequences lignin could be removed totally, but some amount of HexA remained at fully bleached pulps. |
| Year | 2005 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Pulp and Paper Technology (PP) |
| Chairperson(s) | Malinen, Raimo ; |
| Examination Committee(s) | Kolehmainen, Heikki ;Lehtinen, Esa ; |
| Scholarship Donor(s) | Government of Finland ;AIT Fellowship ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2005 |