Periodic operation simplification

For analysis of distributed-parameter systems, such as a tubular fixed bed reactor, numerical simulation of periodic operation at various values of control parameters is typically applied. Asymptotic models for quasisteady and relaxed steady states are valuable instruments for a substantial simplification of the original distributed-parameter system. A method allowing for... 

There are many other S02 simulation using the models described in Tables IX and X or their further simplifications (Boreskov and Matros, 1984 Matros, 1989 Bunimovich etal., 1990 Sapundzhiev etal., 1990 Snyder and Subramanian, 1993 Xiao and Yuan, 1994, 1996 Zhang et al. 1995 Wu et al., 1996). These simulations are capable of reproducing operating data as demonstrated in Table VIII and in the preceding discussion. They have been useful in understanding the application of periodic flow reversal to S02 oxidation, as we shall see. 

The present synthesis is an adaptation of a previously reported synthesis4 in a divided cell (i.e., separate anode and cathode compartments). The overriding consideration in making this modification has been to simplify the operations involved and render the synthesis more attractive to chemists not well acquainted with electrochemical procedures. The main simplification achieved is that the pH is controlled internally via the anodic generation of protons as noted above (in the reported procedure4 this is achieved by periodic addition of acetic acid to the cathode compartment). A further simplification has been to run the reaction with a constant current rather than at controlled cathode potential. After the electrolysis has been initiated, the reaction requires no special attention. A small price is paid for the simplicity of the present synthesis in that the yield is somewhat lower than that obtained previously.4 The major by-product formed is diethyl succinate, which results from a 2e reduction of diethyl fumarate or diethyl maleate ... 

A simplification assumption, particularly for the formulation of the performance criterion, is that the process between the transitions is running at steady state, operating under perfect control, eliminating any disturbance and hence preventing any deviation from on-spec production. With this assumption, the production periods between the transition periods do not need to be considered in this study and the performance index accounts only for the transition periods. 

The design of RIT is shown in Fig. 8. The overall dimensions of the reactor unit and the protective shell were essentially reduced. The reactor design was essentially simplified. The operation period was increased by 3.5 times as compared to KLT-40S reactor. The adopted engineering solution resulted in a significant reduction of the probability of LOCA and in simplification of the emergency core cooling systems. 

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