Control of the adiabatic flow reactor by feeding the catalyst solution

1979 ◽  
Vol 44 (8) ◽  
pp. 2352-2365
Author(s):  
Josef Horák ◽  
Zina Sojková ◽  
František Jiráček
Keyword(s):  
Steady State ◽  
Constant Temperature ◽  
Reaction Temperature ◽  
Control Algorithm ◽  
Flow Reactor ◽  
Operating Temperature ◽  
Temperature Deviation ◽  
Adiabatic Flow ◽  
Dosing Frequency ◽  
Laboratory Reactor

Control algorithm of the operating temperature is described in the reactor, which is operated at constant temperature and composition of the inlet mixture. The temperature is controlled by dosing a constant volume of the catalyst solution. The dosing frequency is determined according to the reaction temperature (deviation of the temperature from the desired value and the sign of the derivative of temperature). The control algorithm has been verified experimentally for the laboratory reactor in unstable steady state.

Control of an adiabatic continuous reactor by feeding catalyst

1980 ◽  
Vol 45 (11) ◽  
pp. 2903-2918 ◽  
Author(s):  
Josef Horák ◽  
Zina Valášková ◽  
František Jiráček
Keyword(s):  
Steady State ◽  
Reaction Temperature ◽  
Continuous Reactor ◽  
Control Element ◽  
Inlet Temperature ◽  
Switching Cycle ◽  
Point Temperature ◽  
Set Point ◽  
Constant Rate ◽  
Laboratory Reactor

Algorithms have been presented, analyzed and experimentally tested to stabilize the reaction temperature at constant inlet temperature and composition of the feed by controlled dispensing of the catalyst. The information for the control element is the course of the reaction temperature. If the temperature of the reaction mixture is below the set point, the catalyst is being fed into the reactor at a constant rate. If the reaction temperature is higher the catalyst dispenser is blocked; dispensing of the catalyst is not resumed until the set point temperature has been reached again. The amount of catalyst added is a function of the duration of the switching cycle. The effect has been discussed of the form of this function on the course of the switching cycle. The results have been tested experimentally on a laboratory reactor controlled in an unstable steady state.

Nonisothermal control of batch reactor with reaction by digital computer. Experimental verification of the control algorithm based on mathematical model of the system

1983 ◽  
Vol 48 (9) ◽  
pp. 2473-2483
Author(s):  
František Jiráček ◽  
Josef Horák
Keyword(s):  
Mathematical Model ◽  
Heat Carrier ◽  
Reaction Temperature ◽  
Flow Rate ◽  
Control Algorithm ◽  
Operating Temperature ◽  
Batch Reactor ◽  
Time Derivative ◽  
Reactor Model ◽  
Operating Reactor

Two-position feedback temperature control of the mixture in a batch reactor with the strongly exothermic autocatalytic reaction is studied. The control is based on continuous measurement of reaction temperature, evaluation of its time derivative and periodical determination of conversion of the reactant. On basis of numerical solution of equations of the mathematical model of the reactor is then evaluated the highest operating temperature of the mixture at which is still secured a safe operation of the reactor and trajectories along which the given operating temperature could be reached in the shortest time period. The manipulated variable was the flow rate of heat carrier into the cooler. Sampling of the reaction temperature and two-position switching over of flow rate of the heat carrier was performed in real time by use of the digital measuring center Hewlett-Packard 3052A. In the experiments has been verified the effect of changes in reactivity of the mixture, accuracy of the mathematical reactor model and effect of additional noise in the measured reaction temperature on control safety. Results of the experiments have proved that the proposed control algorithm enables safe control of the reaction temperature also in cases when the operating reactor states are unstable at the open control loop and when the cooler has a slow response to changes in the manipulated variable.

A Nonlinear Feedback Control Scheme for Transient Performance Enhancement in Hard Disk Drives

2014 ◽  
Author(s):  
Minghui Zheng ◽  
Xu Chen ◽  
Masayoshi Tomizuka
Keyword(s):  
Steady State ◽  
Pid Controller ◽  
Control Algorithm ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Transient Performance ◽  
Nonlinear Feedback ◽  
Nonlinear Pid Controller ◽  
Steady State Performance

This paper aims to develop a nonlinear control algorithm to break the limitations of linear PID controls and improve the transient performance during the short-span track seeking / settling in hard disk drives (HDDs). It is designed based on a baseline PID controller which is well-designed to obtain good track following performance. The control algorithm is a combination of a nonlinear PID controller and a nonlinear turbo controller (NTC): when the position error signal (PES) is large, NTC assists the nonlinear PID controller to rapidly reduce the error; when PES is small, NTC is turned off to avoid possible chattering and ensure good steady state performance. As PES becomes even smaller, the nonlinear PID controller is reduced to the baseline PID controller to keep good steady state performance.

Relaxation of Compression Springs at High Temperatures

1970 ◽  
Vol 92 (3) ◽  
pp. 627-632
Author(s):  
M. J. Siegel ◽  
D. P. Athans
Keyword(s):  
Stainless Steel ◽  
Steady State ◽  
Stress Relaxation ◽  
Operating Temperature ◽  
Transient Creep ◽  
Tensile Creep ◽  
Creep Data ◽  
Limited Life ◽  
Compression Springs ◽  
Design Stress

An analysis is developed to determine the relaxation of cylindrical compression springs at temperatures where creep is predominantly steady state and the effect of transient creep and anelastic strain is small. Springs which operate under these conditions must be designed for limited life. Equations are derived which predict the relaxation of springs directly from tensile creep data for various materials. Using creep data for 18-8 stainless steel and Inconel-X, families of design curves are presented which give the time-temperature initial-stress relationships for various stress-relaxation ratios. These curves are useful in selecting an initial design stress for a specific operating temperature.

scholarly journals A Steady State Model for Burning Coal Mine Methane in a Reverse Flow Burner

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7957
Author(s):  
Jinsheng Lv ◽  
Junrui Shi ◽  
Mingming Mao ◽  
Xiangjin Kong ◽  
Dan Zhou
Keyword(s):  
Steady State ◽  
Coal Mine ◽  
Flow Reactor ◽  
Reverse Flow ◽  
State Model ◽  
Computational Time ◽  
Transient Model ◽  
Coal Mine Methane ◽  
Steady State Model ◽  
Burning Coal

In this study, a steady state model for burning of coal mine methane in a Reverse Flow Burner (RFB) with full kinetics was developed by analogy of a steady counter-flow reactor, and the developed model was used for quick prediction of the lean combustibility limit (LCL). The model was successfully validated with experimental and numerical results, and it was shown that the developed model has excellent accuracy and computational efficiency. Good agreement between the predicted temperature, LCL, and the experiments was observed. The LCL of the equivalence ratio of 0.022 for methane/air mixture was obtained by the developed model. The model was then used to evaluate LCL for the RFB, focusing on the effect of heat loss and burner length on LCL. This indicated that the computational time using the developed model can be reduced by a factor of 1560 compared to the complete transient model.

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