When we talk about pulp and paper industry indicators, one that stands out is the Kappa number. With it, it is possible to identify the degree of delignification of cellulose.
The definitions of the Kappa number are carried out based on the output stream of the digester, over a stream of products that have already been processed.
How does the complete cooking process work?
The process starts with the arrival of the wood logs in the industry, which are collected, washed, debarked, chopped, and sorted.
After that, the chips are stored and then transported for cooking. Then, cooking is carried out in the digesters, where the chip is impregnated with white liquor. This is an alkaline liquid solution that contains reagents such as sodium hydroxide and sodium sulfide.
It is in this process that lignin is dissolved from the reaction of the white liquor with the wood, transforming the chips into brown cellulose.
The time it takes for the chip to go through all the steps until it is unloaded by the digester is what defines the cooking time.
What is the Kappa Number?
The Kappa number is the indicator used to identify the quality of the cellulose pulp produced and is directly linked to the lignin content. After all, this substance is responsible for the tone of the cellulose pulp, which depends on the degree of cooking of the chips.
Thus, it is essential for the pulp and paper industries to have control of the Kappa number, so that it is neither too high nor too low.
When we have these extreme values, we can have negative impacts, such as:
- Low-quality cellulose pulp;
- Possible damage to equipment (through obstructions, which generate a loss of product);
- Increased consumption of chemical products at certain stages;
- Loss of yield in the process;
- The viscosity of the cellulose sheet is affected.
What are the main benefits of Kappa Number control?
Now that you have understood what the Kappa Number is, we can discuss the benefits that controlling this index may bring.
There are still controversies about what would be the ideal Kappa number, but below you can find the positive impacts that controlling the indicator can bring to the pulp and paper industry:
1) Improved yield
Research has shown that one way to maximize overall yield improvement is to finish the cooking process with the highest possible Kappa number.
Through experiments, it has been concluded that by increasing the Kappa number from 14 to 18, there is an increase in yield from 50 to 51%.
2) Operational cost reduction
There are studies on operating costs for the Kappa number of Eucalyptus cooking at 14.1; 17.4; and 20.9. In which the conclusion was that the lowest costs were in Kappa numbers of 20.9.
In addition, the Kappa cooking number is indicated to be ranging from 17.5-21 for short-fiber pulps.
3) Reduction of residue content
The reduction takes place through cooking with extended impregnation to increase the Kappa number of the fiber release point.
4) Increased physical-mechanical properties
The production of eucalyptus pulp with high numbers of kappa (17-25) has proven that pulps with a kappa number of 17 and 22 had greater results, reducing the alkaline material.
Therefore generating less effort to the recovery boiler and resulting in better physical and mechanical properties.
5) Reduction of the organic material to the effluent
Finally, by completing the cooking with pulps with a Kappa number just below the fiber release point, there is a reduction in the organic material to the effluent. In addition, there is an increase in the overall pulp yield.
The need to optimize processes across industries as a whole isn’t something new
As the market demands increasingly competitive prices, in addition to reconciling with sustainable practices, it is important to encourage changes in the pulp and paper segment.
And with that, different strategies have been used to accelerate the development of the cellulose pulp manufacturing processes. The trend to reduce production costs and improve quality in a sustainable way is a reality, and it only tends to grow.
Therefore, indicators such as Kappa numbers and production yield become sustainability demands. In this way, industry results can be shaped based on numbers, with greater predictability of the expected result.
In general, the relationship with the Kappa number can have both negative and positive aspects. However, with the knowledge of which Kappa levels allow for certain characteristics, it is possible to define a strategy based on the factory’s needs.
How to identify the parameters to be optimized in industries
When all aspects of the factory are taken into account, it is possible to identify and balance the process parameters. In addition to the production, quality, and environmental impacts necessary for optimization to take place.
Thus, with industry 4.0 the need to monitor indicators, having end-to-end process visibility is essential. This monitoring must be done throughout the company, from the factory to the support areas. And all this becomes a matter of survival for competitiveness.
This is because it is from this information that managers are able to have a broader view of the improvements to be made in the industry. And as a result, having better decision-making processes that will lead the entire plant towards the expected goals.
Kappa, as mentioned here, is one of those indispensable indicators to be monitored.
Considering this, there are numerous actions and changes in the process that can be taken to achieve:
- Improved yield;
- Operational cost reduction;
- Reduction of residue content;
- Increased physical-mechanical properties;
- Reduction of the organic material to the effluent;
- Among so many others.
And with this, it is possible to achieve optimizations that previously didn’t seem possible. So don’t expect management to work the same way it used to in the past.
This is because the demands for a reduced price, quality, and sustainability are increasing, and indicators such as Kappa allow actions to emerge that will take your factory to the top.