How to save considerable working hours for not only mill people but also for equipment suppliers and consultants, which results in good cost reductions for your mill. Better to be prepared than to repair afterwards.
Paper mills start working on the prefeasibility and feasibility as soon as the budget is available. But starting beforehand to prepare some ground work for prefeasibility is the better way for project development.
During prefeasibility and feasibility studies the most important thing to avoid is unnecessary uncertainty on main design criteria. This uncertainty comes mainly due to lack of time during the prefeasibility phase to investigate the technical discrepancies (e.g. boiler load, black liquor properties, NPE status, steam fiber imbalance). Given the kraft process complex entanglement in dependency of one equipment on other, wrong designing base for one equipment could have cascading effect on the productivity and design of the other equipment.
Doing these following four main technical steps before starting with a prefeasibility study could save considerable time as well as it would reduce the chances of wrong investments.
1. NPE status
More often than not recovery boiler, evaporation plant, lime kiln are the main bottlenecks for increasing the mill capacity. Knowing the NPE amount in advance will help to have the best design for the equipment as well as to a have plan for preventive measures.
Potassium and chlorine content plays measure role in defining the fouling factor for the super heater, and so on boiler critical parts material selection. NPE in the lime cycle not only consume the energy but also limits the capacity utilization and productivity.
2. Black liquor and ESP ash analysis
Doing the periodic black liquor analysis for one complete year is a necessity if a new recovery boiler is planned. This is most important if the mill is running with different seasonal production using different cooking processes. Also, NPE enrichment could only be seen if the measurements are done periodically for certain period. Variation in the carbon content, as well as heat value of the black liquor, is crucial thing for integrated multi fiber line mills. Having known all the variation is best for the preparing design constraints for the new boiler.
3. Wood, fiber, fiber furnish
Having made good periodical measurement of the wood density helps for better designing of the equipment. If the wood yield in the digester is known with +- 5% certainty, then all major equipment will have same uncertainty on the design. Chip quality, as well as wood yard losses, are also crucial information for designing the crucial equipment, e.g. bark boiler.
Fiber properties at various levels of production could be useful information for choosing the right equipment.
Dependence of the broke on bottom layer fiber demand is sometimes crucial forgotten information for multilayer board machines. Getting a clear idea about the fiber consumption at paper machine needs time and should be done early enough.
Having done periodically all the necessary measurement will avoid unnecessary risk involved in equipment designing.
4. Check on measurement instruments
Upgrading non-working flow meters, pressure gauges and temperature measurement units would save a considerable amount of working hours during the mill balancing and capacity check phase of the project. Energy is major cost for paper makers, if the mill is planning to invest in a new power plant concept then first thing is “to know the consumers better”. Take the example of turbine extractions, turbine extraction capacity could be designed only once, making mistakes during design phase regarding the steam demand could have major setback on future energy costs.
Together with stated four crucial things mill could also do the further analysis on the mill productivity and potential for energy savings. With an increase in the energy costs and strict regulation on the environmental norms pulp and paper industry has to upgrade itself to be competitive in the market. Pinch analysis is a useful tool for unearthing potentials for energy savings at existing situations.
If you are facing one of these challenges you are cordially invited to reach out and discuss your case with one of our experts to increase the productivity of your mill and your production output.