BLT-5500 Bleach Load Transmitter

The purpose of the BLT is to measure the total bleach load, or chemical demand of the pulp stream going into the bleach plant stages. The BLT uses UV-VIS light sources to measure both the fiber lignin and the lignin dissolved in the liquid phase of the pulp stream. The BLT provides an in-line continuous measurement of the total lignin content of the pulp stream thus giving the total blech load of the pulp. Furthermore, the BLT is simultaneously measuring the pulp brightness. Using the multiple light sources, it is also possible to calibrate the BLT to measure the conventional fiber kappa number provided that the pulp is well washed.

Neither the standard laboratory kappa test nor the result from a traditional online kappa analyzer addresses any lignin carry over in the filtrate coming with pulp stream. The ability to measure total bleach load allows for a more accurate control of the chemical charge thus reducing the cost for chemical without risking low brightness pulp.