Process Optimization and Integration Strategies for Material Reclamation and Recovery

Industrial facilities are characterized by the significant usage of natural resources and the massive discharge of waste materials. An effective strategy towards the sustainability of industrial processes is the conservation of natural resources through waste reclamation and recycles. Because of the numerous number of design alternatives, systematic procedures must be developed for the effective synthesis and screening of reclamation and recycle options. The objective of this work is to develop systematic and generally applicable procedures for the synthesis, design, and optimization of resource conservation networks. Focus is given to two important applications: material utilities (with water as an example) and spent products (with lube oil as an example). Traditionally, most of the previous research efforts in the area of designing direct-recycle water networks have considered the chemical composition as the basis for process constraints. However, there are many design problems that are not component-based; instead, they are property-based (e.g., pH, density, viscosity, chemical oxygen demand (COD), basic oxygen demand (BOD), toxicity). Additionally, thermal constraints (e.g., stream temperature) may be required to identify acceptable recycles. In this work, a novel approach is introduced to design material-utility (e.g., water) recycle networks that allows the simultaneous consideration of mass, thermal, and property constraints. Furthermore, the devised approach accounts for the heat of mixing and for the interdependence of properties. An optimization formulation is developed to embed all potential configurations of interest and to model the mass, thermal, and property characteristics of the targeted streams and units. Solution strategies are developed to identify stream allocation and targets for minimum fresh usage and waste discharge. A case study on water management is solved to illustrate the concept of the proposed approach and its computational aspects. Next, a systematic approach is developed for the selection of solvents, solvent blends, and system design in in extraction-based reclamation processes of spent lube oil Property-integration tools are employed for the systematic screening of solvents and solvent blends. The proposed approach identifies the main physical properties that influence solvent(s) performance in extracting additives and contaminants from used lubricating oils (i.e. solubility parameter (delta), viscosity (v), and vapor pressure (p)). The results of the theoretical approach are validated through comparison with experimental data for single solvents and for solvent blends. Next, an optimization formulation is developed and solved to identify system design and extraction solvent(s) by including techno-economic criteria. Two case studies are solved for identification of feasible blends and for the cost optimization of the system

Conceptual synthesis of gasification-based biorefineries using thermodynamic equilibrium optimization models

An integrated biorefinery is a processing facility that converts biomass into a wide range of biochemical products and also provides a sustainable supply of biofuels and energy. One of its critical features is the ability to handle a wide variety of biomass feedstocks and the capacity to produce a portfolio of products through multiple conversion technologies. The gasification process is recognized as a promising option for initial processing of biomass, as it is a robust thermal conversion process. The composition of syngas, especially the ratio of H2 to CO, is crucial when the syngas is further converted to liquid fuels and chemicals. To optimize the production of syngas for application in an integrated biorefinery, a systematic approach is needed to design the system and predict its performance. In this work, a modular optimization approach to link a stoichiometric equilibrium model of biomass gasification and structural models of synthesis processes is developed. In this approach, all model components are solved simultaneously. The approach is used to evaluate the equilibrium composition of syngas, the optimum operating temperature, and the required types and amounts of oxidants. Two case studies are used to illustrate the approach. A sensitivity analysis is then performed to assess the most significant factors affecting the process economics in these examples. © 2011 American Chemical Society

Giant Adult Mesenteric Lipoma: A Rare Cause of Chronic Abdominal Distention and Discomfort

Solitary or multiple lipomas are considered common tumors that can occur anywhere in the body; however, mesenteric lipoma is a rare entity that is well known to present with signs and symptoms of small bowel volvulus. Hereby, we present a case of a 54-year-old male patient with multiple comorbidities who was suffering from chronic abdominal discomfort and gradual increase of his abdominal distention over many years without seeking any medical attention. The patient was seen by a general practitioner after complaining of an inflated abdomen, as he described his condition. After several imaging studies, he was diagnosed with one of the largest mesenteric lipomas in the literature. Mesenteric lipoma should be present in the differential diagnosis of any abdominal tumor. Magnetic resonance imaging plays a major role in differentiating benign from malignant lipomas