Real-Time Interactive Navigation on Input-Output Data Sets in Chemical Processes

Input-output data sets are ubiquitous in chemical process engineering. We introduce a real-time interactive navigation framework that provides several capabilities to the decision maker (DM). Once a surrogate model is trained the DM can perform what-if analyses in both input and output spaces by manipulating sliders. An approximated convex hull spanned in the input space supports both a reliable surrogate prediction and a navigation close to the data set. The framework has been tested on data sets obtained with a flowsheet simulator modeling a real steam methane reforming process.     

Gray‐Box Modeling for the Optimization of Chemical Processes

The availability of predictive models for chemical processes is the basic prerequisite for offline process optimization. In cases where a predictive model is missing for a process unit within a larger process flowsheet, measured operating data of the process can be used to set up such models combining physical knowledge and process data. In this contribution, the creation and integration of such gray‐box models within the framework of a flowsheet simulator is presented. Results of optimization using different gray‐box models are shown for a virtual cumene process.     

Effects of the depth of NO and N2O productions in soil on their emission rates to the atmosphere: analysis by a simulation model

Many factors are concerned in the changing forms of nitrogen compounds in soil, so it is not easy to make precise models to simulate the concentration profiles of soil nitric oxide (NO) and nitrous oxide (N₂O) and their emission rates under various soil conditions. We prepared a simple mathematical simulation model based on soil concentration profiles of NO and N₂O. The profiles were measured at lysimeters filled with Andosol soil and fertilized with ammonium sulfate at rate of 200 kgNha^-1, incorporating to plow layer (Hirose & Tsuruta, 1996). In this model, diffusion of gases in soil followed Fick's law and the diffusion coefficient was adopted from Sallam et al. (1984). The gas production rate was set up at constant value in the site of gas production, and the gaseous consumption followed Michaelis-Menten kinetics. By changing only the depth of NO and N₂O production in soil in this model, we obtained the following results.(1) When the depth of gas production was set at near the soil surface (NO: 0–10 cm, N₂O: 0-8 cm), the emission rates of both gases corresponded with the results of the lysimeter-measurement.(2) When the depth of gas production was shifted down 10 cm deeper (NO: 10–20 cm, N₂O: 10-18 cm), the gas emission rate of NO decreased to 1.3% of (1), while that of N₂O was almost the same as (1).(3) In the case that the total intensity of produced gases was not changed from (1) or (2), but that the extent of gas productions expanded 3 times wider (NO: 0–30 cm, N₂O: 0–24 cm) than (1) or (2), the emission rates of NO and N₂O became 26% and 95% of (1), respectively.The above results suggest the possibility of mitigating NO emission by setting the site of gaseous production in deeper soil, e.g. by means of deep application of fertilizer.