MINLP Synthesis of Processes for the Production of Biogas from Organic and Animal Waste

This paper describes a superstructure approach for the synthesis of biogas processes simultaneously with the selection of different process background alternatives. The superstructure consists of anaerobic fermentation under thermophilic or mesophilic conditions, including options for a rendering plant, with different organic and animal wastes from either existing or new plants, different water supplies, wastewater treatments and biogas usage options. An aggregated mathematical model with an economic objective function, formulated as a mixed-integer nonlinear programming (MINLP) problem, was developed. An industrial case study was applied to an existing large-scale meat company, in order to describe the mathematical model and illustrate the MINLP synthesis approach. The optimal solution indicates that significant benefit can be obtained if biogas processes are selected simultaneously with the selection of different process background alternatives thus yielding the optimal integration of biogas processes with their background

A Robust Decomposition Methodology for Synthesis of Flexible Processes with Many Uncertainty Parameters – Application to HEN Synthesis

This contribution presents a new robust decomposition methodology for generating optimal flexible process flow sheets with a large number of uncertain parameters. During the initial steps, first-stage variables are determined by performing mixed-integer nonlinear programming (MINLP) synthesis of a flow sheet at the nominal conditions, and then by exposing the obtained flow sheet sequentially over a set of extreme MINLP scenarios of uncertain parameters. As a result, the sizes of the flow-sheet units gradually increase, and/or new units are added until the required feasibility is achieved. After testing the flexibility of the obtained design, a Monte Carlo stochastic optimization of the second- stage variables is performed using a sampling method in order to obtain an optimum value of the expected objective variable. The advantages of the proposed methodology are the independence of process model sizes from the number of uncertain parameters, the straightforward use of deterministic models for incorporating uncertainty, and relatively simple execution of MINLP synthesis of processes under uncertainty. Thus, it could be used for designing large processes with a large number of uncertain parameters. The methodology is illustrated by synthesis of a flexible Heat Exchanger Network

The outlook of building information modeling for sustainable development

As human needs evolve, information technologies and natural environments require a wider perspective of sustainable development, especially when examining the built environment that impacts the central of social-ecological systems. The objectives of the paper are (a) to review the status and development of building information modeling (BIM) in regards to the sustainable development in the built environment, and (b) to develop a future outlook framework that promotes BIM in sustainable development. Seven areas of sustainability were classified to analyze forty-four BIM guidelines and standards. This review examines the use of BIM in sustainable development, focusing primarily on certain areas of sustainability, such as project development, design, and construction. The developed framework describes the need for collaboration with the multiple disciplines for the future adoption and use of BIM for the sustainable development. It also considers the integration between “BIM and green assessment criteria”; and “BIM and renewable energy” to address the shortcomings of the standards and guidelines

Multilevel-hierarchical MNLP [i.e., MINLP] synthesis of process flowsheets

Abstract: "The objective of this contribution is to propose a multilevel-hierarchical approach to the MINLP synthesis of process flowsheets. Following a hierarchical strategy, the designer can postulate the superstructure at different levels of representation of flowsheet alternatives and model it at the corresponding level of aggregation and complexity. By the use of the prescreening procedure the superstructure is optimized more effectively and reliably. The approach enables one to address different process operations like reactions, connectivity and species allocation, separation, energy and heat integration and HEN through simultaneous superstructure optimization.

Multilevel strategies for the retrofit of a large industrial water system

This paper presents two multilevel strategies for retrofitting a large-scale water system, which integrates water-using operations and wastewater treatment units in different production sections within the same network. The proposed strategies are based on temporal decomposition. They can be applied to production processes with repeating batch/semi-continuous operations, and daily changes in production schedules over a working week. This approach uses a mixed-integer nonlinear programming (MINLP) model for water re-use and regeneration re-use in batch and semi-continuous processes (Tokos and Novak Pintarič, 2009). In the first step, both strategies perform simultaneous retrofit of an integrated water system for each working day, by identifying daily re-use and regeneration re-use connections among water consumers in all sections. At the second level, within the first strategy, the design of an integrated water system is performed over the entire working week for each section by fixing the identified daily matches between sections. In the second strategy, the freshwater upper and wastewater lower bounds of the integrated processes are modified, and retrofit is performed for each production section over the entire working week. The proposed strategies are applied to an industrial case study within a Brewery. © 2011 Elsevier B.V

Multilevel strategies for the retrofit of large-scale industrial water system: A brewery case study

This article presents an approach to designing a large-scale water system, which integrates water-using operations and wastewater treatment units in different production sections within the same network. This approach uses a mixed-integer nonlinear programming (MINLP) model for water reuse and regeneration reuse in batch and semicontinuous processes. The application of this mathematical formulation to large-scale industrial problems with changing daily production schedule leads to huge and complex mathematical models. Two alternative multilevel strategies are proposed to solve such problems by means of temporal decomposition. The approach is illustrated with a brewery case study that integrates water consumers in two production sections. The results obtained show that, despite the high piping cost, integration of both sections yields better result than the separate water network design in each section. © 2011 American Institute of Chemical Engineers (AIChE)

Multilevel strategies for the retrofit of large-scale industrial water system: A brewery case study

This article presents an approach to designing a large-scale water system, which integrates water-using operations and wastewater treatment units in different production sections within the same network. This approach uses a mixed-integer nonlinear programming (MINLP) model for water reuse and regeneration reuse in batch and semicontinuous processes. The application of this mathematical formulation to large-scale industrial problems with changing daily production schedule leads to huge and complex mathematical models. Two alternative multilevel strategies are proposed to solve such problems by means of temporal decomposition. The approach is illustrated with a brewery case study that integrates water consumers in two production sections. The results obtained show that, despite the high piping cost, integration of both sections yields better result than the separate water network design in each section. © 2011 American Institute of Chemical Engineers (AIChE)

PROSYN : an automated topology and parameter process synthesizer

Abstract: "This paper describes an improved, user friendly version of the computer package PROSYN -- a mixed-integer nonlinear programming (MINLP) process synthesizer. PROSYN is an implementation of the modeling and decomposition (M/D) strategy by Kocis and Grossmann (1989) and the outer approximation and equality relaxation algorithm (OA/ER) by Kocis and Grossmann (1987). Main characteristic [sic] of the new version of PROSYN is that it enables automated execution of simultaneous topology and parameter optimization of processes. Optimization of each NLP subproblem is performed only on the existing units rather than on the entire superstructure which substantially reduces the size of the NLP subproblems. In order to reduce undesirable effects of nonconvexities involved in the master problem the OA/ER algorithm has been improved by the use of an augmented penalty function. A simple process simulator has been built in to perform automated initialization of the first NLP step. A comprehensive PROSYN's library of models for basic process units and interconnection nodes, and a comprehensive library of basic physical properties for the most common chemical components have been developed. This enables to carry out [sic] an automated generation of a complex model representation for a superstructure in which the topology is specified by a concise interface. PROSYN allows to run in interactive mode and thus provides the user with a good control and supervision of calculations instead of having the procedure to be totally automated. PROSYN allows to carry out process synthesis at two basic levels of complexity: MINLP optimization through M/D and simultaneous heat integration including HEN costs. Applications with PROSYN are demonstrated with two example problems.