Multivariate Analysis of Variables Affecting Thermal Performance of Black Liquor Evaporators

Multiple Effect Evaporators (MEE) are used in kraft pulp mills to concentrate black liquor. In order to verify if the MEE is operating at an optimum condition, thermal performance of evaporators is calculated. Due to the interconnection of many variables involved, this can be a challenging task. Thus, this work involved the study of operating data from two Canadian pulp mills using Multivariate Data Analysis (MVDA) techniques: Principal Component Analysis (PCA) and Partial Least Squares Analysis (PLS). Moreover, the evaporation system was modelled using a dynamic simulation software called CADSIM. MVDA determined that the thermal performance of the evaporators was positively correlated with the weak black liquor flow rate and negatively correlated with the steam pressure (to the first effect). The CADSIM model confirmed these findings. Therefore, these two techniques show to be useful tools in identifying operating variables that may be adjusted to improve thermal performance of evaporators.MAS