Gray-box surrogate models for flash, distillation and compression units of chemical processes

2021 ◽  
Vol 155 ◽  
pp. 107510
Author(s):  
Fabian Zapf ◽  
Thomas Wallek
2020 ◽  
Vol 6 (4) ◽  
pp. 0467-0473
Author(s):  
Christian De Oliveira Martins ◽  
Felipe Fernando Furlan ◽  
Roberto De Campos Giordano

The techno-economic analysis of chemical processes is usually based on steady state simulations. When dynamic processes are present, simplified or surrogate models are used to avoid the dynamic simulation of the overall system. Nevertheless, this usually results in loss of information when the simplified model is used or a large number of parameters when the surrogate model is applied. To circumvent this problem, a hybrid surrogate model is proposed that combines the low-cost prediction of the average behavior by a simplified model with the fine tuning provided by a multilinear look-up table. This concept was applied to the homogeneous alkaline transesterification of the soybean oil with ethanol in a batch reactor. The hybrid approach enabled a 70% reduction in the number of points of the look-up table compared to the pure interpolator model, for an accuracy tolerance of 0.01 mol/l.


1991 ◽  
Vol 223 ◽  
Author(s):  
Hans P. Zappe ◽  
Gudrun Kaufel

ABSTRACTThe effect of numerous plasma reative ion etch and physical milling processes on the electrical behavior of GaAs bulk substrates has been investigated by means of electric microwave absorption. It was seen that plasma treatments at quite low energies may significantly affect the electrical quality of the etched semiconductor. Predominantly physical plasma etchants (Ar) were seen to create significant damage at very low energies. Chemical processes (involving Cl or F), while somewhat less pernicious, also gave rise to electrical substrate damage, the effect greater for hydrogenic ambients. Whereas rapid thermal anneal treatments tend to worsen the electrical integrity, some substrates respond positively to long-time high temperature anneal steps.


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