2 Open-loop dynamic behavior
2．1 Plant non—linearity
Fig． 2 shows the responses to ± l％ step
changes from the initial value of pressure difference，
P 一P ，between the rectifying and the stripping sec—
tions．The responses to ± 1％ changes in feed ther—
mal condition q are given in Fig．3．It shows that q
has a stronger effect on both end product composi—
lions than P P ．
In addition， the degree of non—linearity in re—
sponses to both P r Ps and q increases with the in—
creasing purity． In low—purity system， positive and
negative perturbation leads to a little bit different re—
sponse．Its non linearity exists but is not very high，
so linear model is capable of describing the real plant
accurately．However，in moderate—purity system，the
responses to positive and negative changes are eom—
pletely different in terms of time constant and devia
lion．Therefore．mismatch between linear model and
real plant exists and this mismatch can limit control
performance of s
ome model—based control schemes u ．In
the high—and very high—purity system，non—linearity
is further intensified with the increasing purity．Posi—
tive perturbation of feed thermal condition results in
the relatively large deviation， sluggish response of
bottom product composition， little deviation， and
quick response of overhead product composition．On
the contrary， negative perturbation has opposite ef—
fects on both of the two end compositions．
上一页 [1] [2] [3] [4] [5] [6] [7] 下一页
蒸馏塔外文文献和翻译 第3页下载如图片无法显示或论文不完整，请联系qq752018766
