Use the concept of relative degree to synthesize control configurations with favorable structural coupling. Propose an integer optimization formulation to synthesize fully decentralized control configurations. Propose a hierarchical clustering procedure to generate block decentralized configuration candidates. Illustrate the application of the method to a complex process network. a b s t r a c tIn this paper, a method to systematically synthesize control configurations with favorable structural coupling is developed, using relative degree as a measure of such coupling. Initially, an integer optimization problem is formulated to identify optimal distributions of inputs and outputs (decentralized control configurations) that minimize the overall structural coupling in the network. Then, a hierarchical clustering procedure, which allows identifying groups of inputs and outputs that are strongly connected topologically (block decentralized control configurations), is proposed. The application of the method is illustrated through an example process network.

In this study, a techno-economic analysis is performed to analyze the effect of the choice of microalgal species on the economics of microalgae-based lipid production. Three microalgal species (Chlorella vulgaris, Tetraselmis suecica, and Nannochloropsis sp.) are selected given their disparate cell characteristics and high promise as feedstocks for commercial-scale microalgae-based lipid production. In the economic analysis, significantly different total production costs are obtained for the three species ($6.5/kglipid, $7.0/kglipid, and $8.3/kglipid for Chlorella vulgaris, Tetraselmis suecica, and Nannochloropsis sp., respectively), and the percentage of each processing stage contributing to the total cost also turned out to be quite different depending on the species. On the basis of the economic analysis, a sensitivity analysis is performed to analyze the effect of different cell characteristics on the overall economics, and to identify the most influential characteristic. The further scenario-based analysis shows that the economic results, as well as the relative standings of the species, change significantly when processing technologies are changed, pointing to the need to optimize the processing pathway individually for each species for a fair evaluation.

In this article, a conceptual process design for the production of lactide is proposed, where an one-step gas phase synthesis route is adopted. Then, the proposed process is evaluated and compared with the conventional two-step (polycondensation and depolymerization) lactide synthesis process. Specifically, techno-economic analysis and life cycle analysis are performed to compare both processes in terms of lactide conversion cost and global warming potential, respectively, to examine the sustainable production capability of the one-step lactide synthesis process. At the lactic acid feed supply rate of 20 ton/h, the lactide conversion cost was $37.57/ton and $70.82/ton for the one-step and two-step processes, respectively, showing that the one-step synthesis of lactide is economically more attractive than the conventional two-step approach. Also, the global warming potential was 0.11 and 0.22 kg CO2eq/kg for the one-step and two-step processes, respectively, implying that the one-step process can produce lactide in a more sustainable way. Finally, sensitivity analysis is performed to identify important process operating conditions and parameters which affect the economics and sustainability significantly. It was shown that the operating variables of the reaction sections, which affect the purity of crude lactide, are the most important factors, and the one-step process is more sensitive to the changes in such variables than the conventional process.

No abstract

No abstract