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한창대 한국화학공학회 1972 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.10 No.3
A first attempt is presented at investigating the problems of the automatic control of a diammonium phosphate granulation plant. This system is chosen for its simplicity, requiring one solid and one liquid feed stream to the granulator. A dynamic model is developed for the granulator in the form of a set of nonlinear differential equations in the zeroth, first and second moments of the granulator discharge stream particle size distribution. The equations are linearized and it is shown that the responses to similar disturbances of both the nonlinear and linear systems agree closely. Using the linear form, the model is extended to include the entire plant and a feed forward controller is designed by which disturbances in feed rate are used for manipulating the product recycle ratio to maintain constant the average particle size of granulator product.
Initiator 와 단량체를 여러 위치에서 공급하는 폴리에틸렌 고압식 관상반응기의 성능
한창대,Liu,Ta Jo 한국화학공학회 1977 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.15 No.4
低容度 폴리에틸렌을 生産하는데 있어서 品質管理를 爲하여 long-chain branching을 control하는 일이 대단히 중요하다. 그 理由는 long-chain branching이 生産된 低密度 폴리에틸렌의 流動學的 物性과 加工性에 큰 영향을 주기 때문이다. 高壓下에서 生産되는 폴리에틸렌 反應器의 특징은 管狀反應器를 使用하는 경우에 그 길이가 直徑의 230倍 내지 1,200倍나 된다는 點이다 生産費의 상당한 額數가 에틸렌을 壓縮시키는데 所要되므로 傳化率을 增加시킬 수 있다면 生産費를 크게 감축시킬수 있다. 이의 한 方法으로서 initiator나 單量體 또는 兩者를 同時에 反應器의 여러 位置에서 加하여 주는 것(multiple injections)이 좋다고 文獻에 報告되어 있다. 著者들은 이러한 提示를 證明하기 爲하여 理論的인 硏究를 遂行하였으며 反應器內에서의 溫度分布, 單量體 및 initiator의 傳化率, 分子量 分布度等의 代表的인 結果를 報告하는 바이다. In the production of polyethylene under high pressure, yielding so called "low-density polyethylene," control of the long-chain branching reaction is of paramount importance to product quality. This is because the long-chain branching level influences the rheoloaical properties and processability of the polyethylene produced. The high pressure polyethylene tubular reactor is characterized by its large length-to-diameter ratio which ranges from 250:1 to as high as 1200:1. Since a significant portion of the production cost of polyethylene in a high-pressure tubular reactor is attributed to the power consumption needed to compress the ethylene, an increase in conversion should help reduce the production cost considerably. It has been suggested in the literature that the use of multiple injections of initiator and/or monomer can increase the conversion of ethylene considerably. We have recently investigated the performance (the conversion and product quality) of a high-pressure polyethylene tubular reactor with multiple injections of initiator and monomer. As part of the investigation, temperature profiles, monomer and initiator conversion, and the number-and weight-average molecular weights were calculated along the length of the reactor. In this paper, we shall present some of the highlights of the study.
한창대 한국화학공학회 1989 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.27 No.4
두 개의 고분자물질을 용용상태에서 섞었을 때, 열역학적 요인에 따라 상분리가 좌우된다. 이러한 혼합물질의 혼합비율에 따른 점탄성의 변화를 이론과 실험결과에 의하여 고찰하였다. The rheological behavior of compatible polymer blends in the molten state is different from that of incompatible polymer blends. Experimental data are first presented and then explained by phenomenological arguments for incompatible polymer blends, and by molecular/thermodynamic arguments for compatible polymer blends.