|
本論文探討非理想混合對於恆溫下，自身催化反應及生化反應與非恆溫、非絕熱下單
成分p 階反應（ p > 0）在連續攪拌反應槽多重穩態中的影響．並提出發生多重穩態
所需具備的必要及充分條件．
對於亙溫下，自身催化反應的反應式為 A=R → ( η + 1) R + 產物，其反應速率式
為 γ a = - k C aP Crr的系統，在兩個不預先混合進料時（反應物 A 及 B），巨
觀混合使得實際進料量不同於理想混合情況．不同的混合情況會使得實際有效進料量
比例不同，而使得多重穩態區域有移動的現象產生．在微觀混合方面，不同反應物應
有不同的混合時間常數，致造成不同反應物由完全凝聚區傳入分子混合區的速率也不
同．而改變的混合條件會使得 A 及 B 傳速率比例不同，使得多重穩態區域也有移動
的現象產生．
對於恆溫下，生化反應系統其反應速率式為 γa = -kCa/(a+KCa)2的多重穩態影響可
分為三方面討論．第一方面，此反應系統多重穩庇的必要及充分條件與理想混合不同
．第二方面，巨觀混合的旁流現象會引起此系統產生奇異現象，這些現象在理想混合
情況下不會發生．第一種奇異現象，為輸入多重穩態濃度現象，此現象與輸出多重狀
態現象同時發生時，如兩個非理想連續混合攪拌反應槽串聯時，其起始操作問題將更
加複雜．第二種現象為多重穩態數目的改變，如兩個理想連續混合攪拌反應槽串聯時
多重穩態數目最多為七個，在非理想混合卻為九個．第三方面，巨觀混合與微觀混合
會對此反應系統的多重穩態有不同的影響．巨觀混合會使得多重穩態區域有移動的效
果，而微觀混合會使得無因次進料濃度減低（稱為有效無因次進料濃度）．這個結果
可能會使得原本在理想混合應發生多重穩態的情況變成唯一穩態，也會使得原本在理
想混合應發生唯一穩庇的情況成為多重穩態．
對於非恆溫、非絕熱下單成分P 階反應 (p > 0)，其反應速率式為 γ=-k Cap的系統
，在非理想沘合中旁流現象及死區現象皆會影響到多重穩態區域．而有關於發生多重
穩態的必要及充分條件及多重穩態區域在本文中都將加以探討．
由於理想混合在實際上操作很難達成，同時，一般理想混合的探討結果，不能引用到
非理想混合系統中．因此，本文在探討上述反應系統在非理想混合所引起的奇異現象
．這些條件及現象對於實際反應器的設計、起始操作及控制將有實際的貢獻及參考價
值．
///////
This dissertation discussed the effect of non-ideal mixing on multiple
steady states in continuous flow stirred tank reactors where the chemical
reaction are isothermal, autocatalytic and biochemical reaction, and
nonisothermal, nonadiabatic, unimolecular, p-th order ( p > 0 ) chemical
reaction, respectively.
For isothermal, autocatalytic reaction which type is A + R → (η + 1) R +
products and rate expression is γa= -k CapCrr. In case of unpremixed
separative reactant feed, the effect of macromixing makes the actually
feeds (A and R) not the same as the ideal mixing''s. The ratio of actually
feed of the chemical reactant A to R is different under the different
mixing situation. And it amkes the exact region of multiplicity shift. As
to the effect of micromixing, the different chemical reactant (A and R)
have its own mixing time constant. This result makes the ratio of the
transport rate from the region of complete segregation to the region of
molectular mixed of A to R different. It also makes the region of
multiplicity shift. Simultaneously, the requirement of the necessary and
sufficient conditions for multiple steady states are also presented in
this dissertation.
The effect of multiplicity for the system of isothermal, biochemical
reaction which rate expression is γa= -k Ca/(1 + K Ca)2, can be
classified to three situations. For the first, the necessary and
sufficient conditions have been derives. The second, the phenomenon of
bypassing in macromixing caused the strange phenomena, but it did''nt
happen in ideal mixing. The strange phenomena have two various kinds. One
is the phenomenon of the input multiplicity concentration. When this and
the phenomenon of the output multiplicity concentration occurred in the
two CSTRs in series simultaneously, it makes the figure of startup
complex. The other is number of multiple steady states changed, for
example, under the two CSTRs in series, the maximuum number of states is
seven in the ideal mixing, but nine steady states exist in the non-ideal
mixing. The third, there are different effects on multiple steady states
in marcromixing and micromixing. Macromixing makes the dimensionless feed
concentration reduced to the effective dimensionless feed conceentration.
This result may change multiple steady states (unigue steady state) under
the ideal mixing into unique steady state (multiple steady states) under
the non-ideal mixing.
For the system of non-ideal nonisothermal, nonadiabatic, unimolecular,
p-th order ( P > 0 ) reaction which rate expression is γa= -kCap, the
phenomena of bypassing and dead space in nonideal mixing all affect the
region of multiple steady states. The necessary and sufficient conditions
for multiplicity have also been discussed in this dissertation.
Since ideal mixing hardly achieved in reality. And the results under the
ideal mixing situation can not apply to the non-ideal mixing situation. So
this dissertation discussed the multiple steady states for the
above-mentioned reacting system, put forward the necessary and sufficient
conditions for multiplicity, and discovered appearance of strange
phenomena from non-ideal mixing. These conditions and phenomena have
pratical contribution and reference value for chemical reactor design,
start-up and control in the real reactors.
|