Structural considerations in zeotropic distillation sequences with multiple feeds

The separation of multiple feed streams with some common components using sequences of distillation columns produces a rich space of alternatives that must be considered. In this work, we present the main structural characteristics of sequences generated when we want to take advantage of the synergies of common components in multiple feed streams to reduce both, energy consumption and the total number of distillation columns. In general, the sequence of separation tasks of the whole system can be obtained from the sequences of separation tasks of each one of the feeds. However, the integration in actual columns is not so straightforward and we must consider aspects like the optimal location of feeds in multiple-feed columns; and the alternatives of integration of common sub-mixtures (when possible) in actual columns. Besides, the optimal sequence of separation tasks for each feed is not necessarily the same when all of them are considered simultaneously. We show that the minimum number of actual columns, without considering further intensification, depends on the number of components in each feed and on the possibilities of integration of common sub-mixtures, so we extend the concepts of regular and basic column sequences to deal with these new situations. The examples show the potential savings in energy and number of columns compared to maintain isolated each feed; mixing the feed streams or an incorrect integration.The authors acknowledge financial support to the “Generalitat Valenciana” under project PROMETEO 2020/064

Rigorous design of distillation columns using surrogate models based on Kriging interpolation

The economic design of a distillation column or distillation sequences is a challenging problem that has been addressed by superstructure approaches. However, these methods have not been widely used because they lead to mixed-integer nonlinear programs that are hard to solve, and require complex initialization procedures. In this article, we propose to address this challenging problem by substituting the distillation columns by Kriging-based surrogate models generated via state of the art distillation models. We study different columns with increasing difficulty, and show that it is possible to get accurate Kriging-based surrogate models. The optimization strategy ensures that convergence to a local optimum is guaranteed for numerical noise-free models. For distillation columns (slightly noisy systems), Karush–Kuhn–Tucker optimality conditions cannot be tested directly on the actual model, but still we can guarantee a local minimum in a trust region of the surrogate model that contains the actual local minimum.The authors gratefully acknowledge the financial support of the Ministry of Economy and Competitiveness of Spain, under the project CTQ2012-37039-C02-02

Hybrid simulation-equation based synthesis of chemical processes

A challenging problem in the synthesis and design of chemical processes consists of dealing with hybrid models involving process simulators and explicit constraints. Some unit operations in modular process simulators are slightly noisy or require large CPU times to converge. In this work, this problem is addressed by combining process simulators and surrogate models. We have replaced some unit operations, which cannot be used directly with a gradient-based optimization, by surrogate models based on Kriging interpolation. To increase the robustness of the resulting optimization model, we perform a degree of freedom analysis and aggregate (or disaggregate) parts of the model to reduce the number of independent variables of the Kriging surrogate models (KSMs). Thus, the final model is composed of KSMs, unit operations (maintained in the process simulator) and also explicit equations. The optimization of the well-known vinyl chloride monomer (VCM) production process is performed to test the proposed approach. The effect of the heat integration is also studied. In addition, the economic feasibility of the optimized process is calculated assuming uncertainty in raw material and product prices.The authors gratefully acknowledge the financial support by the Ministry of Economy and Competitiveness from Spain, under the project CTQ2016-77968-C3-02-P (AEI/FEDER, UE), and Call 2013 National Sub-Program for Training, Grants for pre-doctoral contracts for doctoral training (BES-2013-064791)

Rigorous Design of Complex Distillation Columns Using Process Simulators and the Particle Swarm Optimization Algorithm

We present a derivative-free optimization algorithm coupled with a chemical process simulator for the optimal design of individual and complex distillation processes using a rigorous tray-by-tray model. The proposed approach serves as an alternative tool to the various models based on nonlinear programming (NLP) or mixed-integer nonlinear programming (MINLP) . This is accomplished by combining the advantages of using a commercial process simulator (Aspen Hysys), including especially suited numerical methods developed for the convergence of distillation columns, with the benefits of the particle swarm optimization (PSO) metaheuristic algorithm, which does not require gradient information and has the ability to escape from local optima. Our method inherits the superstructure developed in Yeomans, H.; Grossmann, I. E.Optimal design of complex distillation columns using rigorous tray-by-tray disjunctive programming models. Ind. Eng. Chem. Res.2000, 39 (11), 4326–4335, in which the nonexisting trays are considered as simple bypasses of liquid and vapor flows. The implemented tool provides the optimal configuration of distillation column systems, which includes continuous and discrete variables, through the minimization of the total annual cost (TAC). The robustness and flexibility of the method is proven through the successful design and synthesis of three distillation systems of increasing complexity.The authors would like to acknowledge financial support from the Spanish “Ministerio de Ciencia e Innovación” (CTQ2009-14420-C02-02 and CTQ2012-37039-C02-02)

Exosomal Osteoclast-Derived miRNA in Rheumatoid Arthritis: From Their Pathogenesis in Bone Erosion to New Therapeutic Approaches

Rheumatoid arthritis (RA) is an autoimmune disease that causes inflammation, pain, and ultimately, bone erosion of the joints. The causes of this disease are multifactorial, including genetic factors, such as the presence of the human leukocyte antigen (HLA)-DRB1*04 variant, alterations in the microbiota, or immune factors including increased cytotoxic T lymphocytes (CTLs), neutrophils, or elevated M1 macrophages which, taken together, produce high levels of pro-inflammatory cytokines. In this review, we focused on the function exerted by osteoclasts on osteoblasts and other osteoclasts by means of the release of exosomal microRNAs (miRNAs). Based on a thorough revision, we classified these molecules into three categories according to their function: osteoclast inhibitors (miR-23a, miR-29b, and miR-214), osteoblast inhibitors (miR-22-3p, miR-26a, miR-27a, miR-29a, miR-125b, and miR-146a), and osteoblast enhancers (miR-20a, miR-34a, miR-96, miR-106a, miR-142, miR-199a, miR-324, and miR-486b). Finally, we analyzed potential therapeutic targets of these exosomal miRNAs, such as the use of antagomiRs, blockmiRs, agomiRs and competitive endogenous RNAs (ceRNAs), which are already being tested in murine and ex vivo models of RA. These strategies might have an important role in reestablishing the regulation of osteoclast and osteoblast differentiation making progress in the development of personalized medicine.This research was supported by the grant CIGE/2021/162 funded by Generalitat Valenciana and by University of Alicante, grant number GRE21-17, both as the Emerging Research Groups Grants

El grupu neandertal de la Cueva d'El Sidrón (Borines, Piloña).

Na monografía clásica de Puig y Larraz (1896: 250-252) amiéntense delles cavidaes del Conceyu de Piloña2 , pero non la Cueva d’El Sidrón (Fig. 1). Esta conocíase, ensin dulda, dende la Guerra Civil y el maquis al servir d’abellugu a persiguíos políticos, y guarda una alcordanza imborrable nuna de les sos múltiples entraes, yá qu’ellí ta enterrada Olvido Otero González (1908-1938). Per El Sidrón pasaron munches persones a lo llargo de los años, pero en 1994 prodúxose’l descubrimientu per parte d’unos espeleólogos xixoneses d’unos güesos humanos que dieron un importante xiru a la conocencia de los nuesos antepasaos neandertale

Simulation-based optimization of distillation processes using an extended cutting plane algorithm

The use of commercial flowsheeting programs enables straight-forward use of rigorous, but user hidden, mathematical formulations of chemical processes. The optimization of such black-box models is a challenging task due to nonconvexity, absence of accurate derivatives, and simulation convergence failures which can prevent classical optimization procedures from continuing the search. Here, we present an optimization framework based on the extended cutting plane algorithm with additional heuristic techniques and strategies designed to improve its practical performance for solving nonconvex simulation-based MINLP problems. The new algorithmic features include two approaches for dealing with nonconvexities; the first technique expands the search space to restore feasibility of the MILP subproblems, and the second is a restarting technique to avoid premature termination to non-optimal solutions. We also propose two approaches for handle simulation failures, based on no-good cuts and backtracking. The proposed optimization framework is successfully applied to four case studies dealing with the economic optimization of distillation processes.The authors JJ and JC acknowledge financial support from the “Generalitat Valenciana” under project PROMETEO 2020/064. The author JK acknowledges financial support by a Newton International Fellowship from the Royal Society (NIF\R1\182194) and a grant by the Swedish Cultural Foundation in Finland

Efficient Energy Integration and Design of Distillation Separation Sequences

In this paper we show that for a zeotropic mixture the simultaneous implementation of different heat integration alternatives like direct reboiler-condenser heat exchange, Direct or reverse vapor recompression cycles, multi-effect distillation, partially or totally breaking of thermal couples and substitution of thermal couples by the equivalent only liquid transfer alternative, when possible, considerable increase the thermal efficiency of a sequence of distillation columns and its total cost. We illustrate the procedure with the separation a four-component mixture. Results show that we can get impressive reductions in total annual cost.The authors acknowledge financial support to the Spanish «Ministerio de Economía, Industria y Competitividad» under project CTQ2016-77968-C3-2-P (AEI/FEDER, UE) and to the «Generalitat Valenciana» under project PROMETEO/2020/064

Alternative carbon dioxide utilization in dimethyl carbonate synthesis and comparison with current technologies

Dimethyl carbonate (DMC) has recently gained popularity due to its environmentally friendly status and multiple applications in which it is able to replace more toxic chemicals. Among its several commercial synthesis production routes, the ethylene carbonate (EC) transesterification shines as a CO2 consuming process. However, other factors such as the high emitting synthesis of EC precursors hinder its environmental capabilities. Methanol oxycarbonylation is a mature DMC non-CO2 consuming synthesis route with the potential to indirectly utilize the greenhouse gas throughout the synthesis of its intermediates. In this work, we propose a DMC production superstructure using the methanol oxycarbonylation route with the aim of consuming CO2 in both the synthesis gas (syngas) and methanol synthesis stages. Results show that the integration of methanol and syngas synthesis with the DMC production process vastly decreases both the cost and emission with respect to the unintegrated case. However, the addition of a Reverse Water Gas Shift (RWGS) reactor further decreases the emission down to a minimum of 1.019. kg CO2-eq/kg DMC, resulting in a 54 % decrease in the indicator compared with the direct CO2 utilization route. In comparison with other routes, utilization of this DMC in blends with gasoline manages to reduce the GWP of using the fuel mix to a potential 16 %.The authors gratefully acknowledge financial support from the project PROMETEO2020/064. The authors would also like to thank «Generalitat Valenciana: Conselleria de Educación, Investigación, Cultura y Deporte» for the Ph.D grant (ACIF/2016/ 062)

Economic and Environmental Performance of an Integrated CO2 Refinery

The consequences of global warming call for a shift to circular manufacturing practices. In this context, carbon capture and utilization (CCU) has become a promising alternative toward a low-emitting chemical sector. This study addresses for the first time the design of an integrated CO2 refinery and compares it against the business-as-usual (BAU) counterpart. The refinery, which utilizes atmospheric CO2, comprises three synthesis steps and coproduces liquefied petroleum gas, olefins, aromatics, and methanol using technologies that were so far studied decoupled from each other, hence omitting their potential synergies. Our integrated assessment also considers two residual gas utilization (RGU) designs to enhance the refinery’s efficiency. Our analysis shows that a centralized cluster with an Allam cycle for RGU can drastically reduce the global warming impact relative to the BAU (by ≈135%) while simultaneously improving impacts on human health, ecosystems, and resources, thereby avoiding burden-shifting toward human health previously observed in some CCU routes. These benefits emerge from (i) recycling CO2 from the cycle, amounting to 11.2% of the total feedstock, thus requiring less capture capacity, and (ii) reducing the electricity use while increasing heating as a trade-off. The performance of the integrated refinery depends on the national grid, while its high cost relative to the BAU is due to the use of expensive electrolytic H2 and atmospheric CO2 feedstock. Overall, our work highlights the importance of integrating CCU technologies within chemical clusters to improve their economic and environmental performance further.ISSN:2168-048