In this blog post, we talk about how to save considerable working hours for mill employees, equipment suppliers, as well as consultants – because less working hours translate into considerable cost reductions for your mill!
Very often, paper mills start working on the pre-feasibility and feasibility as soon as the budget is available. However, we argue that starting already beforehand, in order to prepare some ground work for the pre-feasibility is way more efficient for project development.
During pre-feasibility and feasibility studies, it is highly important to avoid unnecessary uncertainty regarding main design criteria. This uncertainty often results from a lack of time during the pre-feasibility 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 the other, a wrong design base for one equipment, could have a cascading effect on the productivity and design of the other equipment.
By executing the following 4 technical steps before starting a pre-feasibility study, you could save a considerable amount of time. Moreover, the chances of wrong investments will surely decrease:
1. NPE status
More often than not, recovery boilers, evaporation plants and lime kilns are the main bottlenecks for increasing the mill capacity. Knowing the NPE amount in advance will not only help to get the best possible design for the equipment, it will also be highly beneficial for planning preventive measures.
Potassium and chlorine content play a major role in defining the fouling factor for the super heater, and, consequently for the material selection of critical boiler parts. NPE in the lime cycle not only consumes 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 especially important if the mill is running with different seasonal productions, using different cooking processes. Moreover, NPE enrichment can only be seen if the measurements are done periodically for certain periods. A variation in the carbon content as well as in the heat value of the black liquor is crucial for integrated multi fiber line mills. To be familiar with all the variations is highly benefical for preparing the design constraints for the new boiler.
3. Wood, fiber, fiber furnish
A periodical measurement of the wood density helps for a better designing of the equipment. If the wood yield in the digester is known to be +- 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 main equipment, e.g. bark boiler.
Fiber properties at various levels of production could be useful information for choosing the right equipment.
The dependence of the broke on the bottom layer fiber demand is sometimes a crucial, however, forgotten information for multilayer board machines. Getting a clear idea about the fiber consumption of paper machines requires time and should be done early enough.
By periodially doing all the necessary measurements, unnecessary risks regarding the designing of the equipment can easily be avoided.
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 driver for paper manufacturers. If the mill is planning to invest in a new power plant concept, the first thing is “to know the consumers better”. Take the example of turbine extractions: The turbine extraction capacity could be designed only once. By making mistakes during the design phase regarding the steam demand, a major setback on future energy costs could be the result.
In combination to the aforementioned 4 crucial steps, the mill could also do a further analysis on the mill productivity and on potential energy savings. With an increase in energy costs and strict environmental regulations, the pulp and paper industry has to upgrade itself to be competitive on the market. A 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.