Standard Unit Operations Research Articles

Regional shipping strategy assessment based on installing a refuse-derived-fuel process in a municipal incinerator.

The rising prices of raw materials and the concerns of energy recovery have resulted in an increasing interest in processing the waste streams. In recent years, a number of credible surveys have shown that recycling and waste-to-energy processes appear to work well together. Compatibility exists for several reasons related to economic, environmental, political, and social aspects. However, the regional impacts of installing a centralised refused-derived fuel (RDF) process prior to waste-to-energy facilities remain unclear due to the inherent complexity of solid waste composition, generation rate, energy and material recovery goals, and the existing shipping patterns. This paper illustrates a thorough evaluation for a RDF pilot study from both quantitative and qualitative aspects. Such a process, consisting of the standard unit operations of shredding, magnetic separation, trommel screening, and air classification, might be useful for integrating the recycling and presorting efforts with a large-scale municipal incinerator in a region. A series of sampling and analyses of the waste streams were performed in Taipei County, Taiwan in order to characterise its potentials for recycling. Based on the proper estimation of solid waste generation, the goal programming modelling analysis not only focuses on an evaluation of how the waste inflows with different rates of generation, physical and chemical compositions, and heating values in the service areas can be processed by a centralised RDF facility to meet both the energy recovery and throughput requirements in different municipal incinerators but also indicates the optimal shipping pattern associated with several incinerators due to such an installation in a regional sense. A case study designed to explore the regional impacts on shipping patterns in the southwestern of Taipei County, Taiwan verifies the application potential of such a planning methodology.

An industrial design/control study for the vinyl acetate monomer process

This work presents design details of an industrial process for the manufacture of vinyl acetate monomer. Our purpose is to offer a realistic example that is uniquely suited for academic researchers pursuing simulation, design, and control studies. The vinyl acetate process has common, real chemical components. It contains many standard unit operations in a realistic flowsheet. And it illustrates the types of systems of industrial research interest in the areas of process design, optimization, simulation, and control. Vapor-phase reactions convert ethylene, oxygen, and acetic acid into vinyl acetate with water and carbon dioxide as byproducts. The process contains a packed tubular reactor, a feed-effluent heat exchanger, an absorber, a vaporizer, an azeotropic distillation column with decanter, and both gas and liquid recycle streams. All physical property, kinetic, and flowsheet data have been compiled from sources in the open literature. We detail the flowsheet information required to construct rigorous steady state and dynamic mathematical models of the process and present the process control requirements and objectives. Finally, we briefly describe the rigorous nonlinear dynamic simulation we have constructed for this process using TMODS, DuPont’s in-house dynamic simulator. Models of this process have also been developed by Aspen Technology and Hyprotech in their commercial simulators and are available directly from the vendors.

Systematic Evaluation and Uncertainty Analysis of the Refuse-Derived Fuel Process in Taiwan

ABSTRACT In the last few years, Taiwan has set a bold agenda in solid waste recycling and incineration programs. Not only were the recycling activities and incineration projects promoted by government agencies, but the related laws and regulations were continuously promulgated by the Legislative Yen. The solid waste presorting process that is to be considered prior to the existing incineration facilities has received wide attention. This paper illustrates a thorough evaluation for the first refuse-derived fuel pilot process from both quantitative and qualitative aspects. The process is to be installed and integrated with a large-scale municipal incinerator. This pilot process, developed by an engineering firm in Tainan County, consists of standard unit operations of shredding, magnetic separation, trommel screening, and air classification. A series of sampling and analyses were initialized in order to characterize its potentials in the solid waste management system. The probabilistic modeling for various types o f waste pro perties derived in this analysis may provide a basic understanding of system reliability.

Comparative evaluation of RDF and MSW incineration

In the last few years, a number of credible surveys have shown that material recycling and incineration processes appear to work well together in an integrated system. Compatibility exists for several reasons related to not only economic and environmental, but also political and social aspects in several developed countries. However, the impacts of solid waste presorting on incineration facilities remain unclear in developing countries due to the inherent complexity of solid waste composition. This analysis evaluates the comparative effects by burning municipal solid waste (MSW) and refuse-derived fuel (RDF) in the same incinerator. The solid waste presorting or RDF production process consists of standard unit operations of shredding, magnetic separation, trommel screening, and air classification. The production of RDF and collected MSW are dedicated to a small scale incinerator. Focus has been placed upon the comparative evaluation of heat balance, ash property, and the quality of flue gas in the incineration process. It appears that the incineration of RDF presents relatively better performance in several aspects.

Evaluation of heat value and its prediction for refuse-derived fuel

The rising prices of raw materials and the concerns of energy conservation have resulted in an increasing interest in the recovery of materials and energy from the waste streams. In recent years, a number of credible surveys have shown that recycling and the concept of waste-to-energy appear to be practical. Compatibility exists for several reasons related to economic, environmental, political and social aspects. However, the impacts of solid waste pre-sorting on waste-to-energy facilities remain uncertain in different countries due to the inherent complexity of the composition of solid waste. Here we illustrate a regression analysis of heating values based on the products generated by a typical refuse-derived fuel system, developed in Taiwan, that is prepared to coordinate subsequent waste-to-energy facilities for solving the municipal solid waste (MSW) problems in the future. This pre-sorting system, designed solely for municipal solid waste, consists of standard unit operations of shredding, magnetic separation, trommel screening and air classification. The prediction accuracy using regression models is proven to be better than other analytical formulas.

Generation of the system of equations for equationally oriented global simulation of complex systems

Generation of the system of equations from equational models of standard unit operations used for solution of global simulation of a complex system in steady state is considered. The procedure is illustrated on a simple example.