Hidekazu Kurimoto

Periodic control of continuous stirred tank reactors—II Cases of a nonisothermal single reactor

Abstract The optimal periodic control of a single nonisothermal CSTR in which a single reaction, a parallel reaction or a consecutive reaction is taking place is studied. Both the feed rate and the heat transfer between the reactor content and the immersed coil are periodically controlled. Utility consumption and conversion of the raw material into the waste are included in the performance index together with conversion into the desired product. The results indicate a respectable improvement in the reactor performance.

Binary periodic distillation scheme with enhanced energy conservation. II: Experiment

Abstract A laboratory-scale periodic distillation column using the idealized Cannon scheme which has been proposed in Part I was constructed and some basic experiments were carried out in order to examine its performance in view of energy conservation. A five-stage column was used. The system employed is the water-methanol mixture. The Murphree stage efficiency which was estimated on the basis of experimental results was 84.6%. The average vapor rate, which is roughly proportional to the energy consumption rate, is 50 and 20% lower than the vapor rate required for obtaining the same separation by use of a conventional continuous column with the same number of stages whose Murphree stage efficiency is 84.6 and 100%, respectively.

Binary periodic distillation scheme with enhanced energy conservation—I: Principle and computer simulation

It is known that the performance of continuous distillation in view of the energy conservation can significantly be improved by adopting the alternate-flow periodic operation which was first proposed and investigated by Cannon and his coworkers. Recently another alternate-flow periodic operation scheme using a stepwise operation has been proposed by Baron and Wajc. In this paper a composite scheme in which the advantageous features of Cannon scheme and Baron-Wajc scheme are combined with each other is constructed and its superiority to the conventional steady-state operation scheme, Cannon scheme and Baron-Wajc scheme is ascertained through some numerical analyses.

Periodic control of continuous stirred tank reactors—III: Case of multistage reactors

Abstract The optimal periodic control of a multistage CSTR in which a nonisothermal parallel reaction is taking place is investigated. By applying the infinite-frequency pi criterion it is examined in what condition the optimal periodic control is proper. Then, the optimal steady control and the suboptimal periodic control are determined by numerical calculation. The results indicate that the improvement in the reactor performance for the periodic control relative to that for the steady control is very much increased with increase in the number of stages.

Application of the infinite-frequency pi criterion to a periodically operated isothermal CSTR

In this communication the authors apply the infinite-frequency pi criterion to periodic operations problems of an isothermal CSTR with positive reaction orders and analytically discuss the conditions that the performance can be improved by periodic operation

Analysis of electrically induced flows in DC electric arc furnace

Limitations of natural resources and environmental pollution problems have forced people to consider seriously about recycling of materials. As a means of recycling, DC arc furnaces can be used to recycle scrap materials and already some industries have started to use them in small scale production. An in depth understanding of the process involved is essential for optimal design and efficient control. Therefore, in order to have a better understanding of the process, the authors developed a mathematical model and the model equations are numerically solved. Volume of fluid method is used to treat the free surface. Numerical results show that a single vortical region is generated within the melt when the bottom electrode diameter is large. When the bottom electrode diameter is small, two vortical regions are found with opposite rotation. It is also found that the volume of fluid method can give a more detailed picture of the flow near the surface below the top electrode.

Process Systems Engineering. Intellectual Sensing Based on Nonlinear Dynamics. Measurement of Components by Time-Dependent Response of a Semiconductor Gas Sensor.

動的非線形応答に含まれる多元的な情報を処理することで, 我々は生体の高度な化学センシング性能に近づくような, 知的なセンシング法を提案する.事例として, SnO2半導体ガスセンサーのヒーター部分にサイン波を加え, 表面温度を周期的に変化させることで, その動的非線形応答としての半導体の抵抗値の変化からガス種を識別するガスセンサーを検討した.アクチベーション・モデルとの類推から半導体の抵抗値に対数変換を施し, その波形を調和解析した.この結果, ガス種の分子量や反応性などの情報をより鮮明に抽出でき, 反応性が異なるガス種では混合比を推定できることを明らかにした.