Figure 6.53. Phase structure of the first stage. Ft,: Binder addition rate, Pw: Agitator power consumption.
2, we have used percent binder solution added into the granulator as an indicator variable and sampled each variable at every 1% increase in this variable, resulting in 100 observations for each batch at this phase. These equalized data are appended to the fixed data of the first phase, resulting in a total number of 160 observations for stage 1 (Figs. 6.54a and 6.54b).
Stage 2 is the drying stage where a fluid bed dryer is used. The wet granulates are dried using hot airflow to decrease their moisture content. The increase in product temperature is measured as an indicator of drying. Airflow rate, inflow air temperature, drying rate, and product moisture are also measured. Product temperature is found to be appropriate as an indicator variable for this stage, and measurements on each variable are interpolated on every 0.5 °C increase in product temperature, resulting in 63 observations (Figs. 6.54c and 6.54d).
MPCA model development stage for data blocks: There are two operational phases at the first stage of the granule production process. The first phase contains dry mixing for a fixed time, and the second phase involves
Figure 6.54. Equalized process variable trajectories of both stages using indicator variable technique.
wet massing. Since the total amount of binder to be added is fixed, the exact completion of the second phase is reached when all of the binder solution is consumed. Data from the first phase are collected based on the fixed operation time, resulting in the Xjjifci unfolded matrix. Data arrangement in the second phase is based on a fixed indicator variable (percent binder addition), resulting in The index pairs j 1, kl and j2, k2 denote variables and observation numbers of each phase, respectively. The overall performance can also be investigated by appending these matrices to form an augmented matrix
Xijk = [Xij ifci Xij2k2}) where j — j 1 + j2 and k = kl + k2.
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