コンピューター・シミュレーションによるペーパーマシン・ドライヤー・セクションの解析
第4報マシン幅方向変動のコンピューター解析
1985 年 39 巻 11 号 p. 1073-1081
詳細
1985 年 39 巻 11 号 p. 1073-1081
Using the extended computer model in Part III, the effects of the variations of dryer operating conditions in cross directions are investigated with two commercially running machines, a low speed fine paper machine and a high speed LWC machine. The cross directional data are converted to percent deviations from averages of each cylinders respectively, to get more useful informations on cross directional variations.
Regarding operating conditions, followings are summarized.
1. Cylinder pocket air absolute humidities show far bigger percent deviations than cylinder surface temperatures and cylinder pocket air temperatures in both machines.
2. The fine paper machine has bigger variations than the LWC machine in above three operating conditions.
The simulated results suggest several fundamental differences between two kinds of paper machines as followings.
1. In the fine paper machine, the cross directional variations of cylinder surface temperatures primarily cause the cross directional variations of water evaporation at each cylinder, which are accumulated to produce the variations of web moisture contents.
2. Even though a web dries up in a rather good moisture profile, it is suggested that its moisture profile during drying is not necessarily even all the way. The web moisture difference of 0.05 g water/g. fibre in a cross direction may well be expected at some cylinder.
3. In the LWC machine, the cross directional variation of water evaporation is rather influenced by that of cylinder pocket air absolute humidity, not by that of cylinder surface temperature.
4. One of the reasons of the above different behaviors may be that the ratio of water evaporation in pockets to total evaporation is higher in the LWC machine, which means that the pocket conditions are more influential in a high speed machine than in a low speed machine.
5. Moreover, the cylinder surface temperature variations of the LWC machine are quite limited. With this fact combined with the above reason, they become less important than the pocket conditions.
