Alexander M. Niziolek

Municipal solid waste to liquid transportation fuels – Part I: Mathematical modeling of a municipal solid waste gasifier

Abstract This paper presents a generic gasifier model towards the production of liquid fuels using municipal solid waste (MSW) as a feedstock. The MSW gasification has been divided into three zones: pyrolysis, oxidation, and reduction. The pyrolysis zone has been mathematically modeled with an optimization based monomer model. Then, the pyrolysis, oxidation, and reduction zones are defined with different chemical reactions and equations in which some extents of these reactions are not known a priori. Using a nonlinear parameter estimation approach, the unknown gasification parameters are obtained to match the experimental gasification results in the best possible way. The results suggest that a generic MSW gasifier mathematical model can be obtained in which the average error is 8.75%. The mathematical model of the MSW gasifier is of major importance since it can be a part of a process superstructure towards the production of liquid transportation fuels.

Municipal solid waste to liquid transportation fuels – Part II: Process synthesis and global optimization strategies

Abstract This paper investigates the production of liquid transportation fuels from municipal solid waste (MSW). A comprehensive process synthesis superstructure is utilized that incorporates a novel mathematical model for MSW gasification. The production of liquid products proceeds through a synthesis gas intermediate that can be converted into Fischer–Tropsch hydrocarbons or methanol. The methanol can be converted into either gasoline or olefins, and the olefins may subsequently be converted into gasoline and distillate. Simultaneous heat, power, and water integration is included within the process synthesis framework to minimize utilities costs. A rigorous deterministic global optimization branch-and-bound strategy is utilized to minimize the overall cost of the waste-to-liquids (WTL) refinery and determine the optimal process topology. Several case studies are presented to illustrate the process synthesis framework and the nonconvex mixed-integer nonlinear optimization model presented in this paper. This is the first study that explores the possibility of liquid fuels production from municipal solid waste utilizing a process synthesis approach within a global optimization framework. The results suggest that the production of liquid fuels from MSW is competitive with petroleum-based processes. The effect that the delivered cost of municipal solid waste has on the overall cost of liquids production is also investigated parametrically.

Municipal solid waste to liquid transportation fuels, olefins, and aromatics: Process synthesis and deterministic global optimization

Abstract This paper proposes a comprehensive process superstructure-based approach toward the sustainable production of liquid transportation fuels, olefins, and aromatics from municipal solid waste, MSW. A deterministic global optimization based branch-and-bound algorithm is utilized to solve the resulting nonconvex mixed-integer nonlinear optimization model. Several novel, commercial, and competing technologies are modeled within the proposed framework. The production of higher-value hydrocarbons proceeds through a synthesis gas intermediate that can be subsequently converted via Fischer–Tropsch refining or methanol synthesis. Simultaneous heat, power, and water integration is included in every process design to minimize utility costs. For every proposed process design, two profitability metrics, the overall profit and the net present value, are calculated. The optimal process topologies that produce liquid fuels and high-value chemicals at the highest profit are illustrated for several case studies. The effects of refinery scale and composition of products produced on the overall profit and the selected process topology are investigated. The effect that the tipping fee of MSW has on the overall profitability of the process is investigated parametrically for several values. Complete material, energy, carbon, and greenhouse gas balances are additionally provided for each case study investigated. The results suggest that production of liquid fuels, olefins, and aromatics is profitable at the highest scales (i.e., 5 thousand barrels per day of liquid fuels and 500 metric tons per day of chemicals) investigated with superior environmental performance compared to petroleum-based processes.

Multi-scale approaches for gas-to-liquids process intensification: CFD modeling, process synthesis, and global optimization

Abstract This paper presents a multi-scale framework for the intensification of small scale gas-to-liquids (GTL) processes. As the process intensification tool, a radial microchannel reactor is used to facilitate the catalytic steam reforming of methane. Due to the endothermicity of this reaction, a microchannel reactor serves as a promising alternative because of its enhanced heat transfer characteristics. However, the underlying mathematical model for the microchannel reforming process is complex. Since our aim is to elucidate the optimal process topology from a plethora of alternatives through a global optimization framework, we built a surrogate mathematical model to bridge this gap. Through a rigorous model identification, parameter estimation, and cross-validation analysis we have developed an accurate mathematical model that can predict the microchannel reactor output within 0.43%. We then implemented this mathematical model into a process superstructure that considers several novel and competing process alternatives for the production of liquid fuels from natural gas. Across different case studies ranging from 500 to 5000 barrels per day of total production, we have observed that the microchannel process can improve break-even oil prices (BEOP) by as much as

Enhancing natural gas-to-liquids (GTL) processes through chemical looping for syngas production: Process synthesis and global optimization

10/bbl. Since the small scale GTL process aims to utilize stranded natural gas with almost zero value, a parametric analysis is performed to evaluate the BEOP at different feedstock prices. We have observed that the microchannel reforming alternative is the superior process at all the scales investigated when a natural gas price of

Municipal Solid Waste to Liquid Transportation Fuels - Part III: An Optimization-Based Nationwide Supply Chain Management Framework

1/TSCF is considered. The topological findings suggest that process intensification through microchannel steam reforming is a viable approach to monetize stranded natural gas.

Production of Benzene, Toluene, and the Xylenes from Natural Gas via Methanol

Abstract A process synthesis and global optimization framework is presented to determine the most profitable routes of producing liquid fuels from natural gas through competing technologies. Chemical looping is introduced into the framework for the first time as a natural gas conversion alternative. The underlying phenomena in chemical looping are complex and models from methods such as computational fluid dynamics are unsuitable for global optimization. Therefore, appropriate approximate models are required. Parameter estimation and disjunctive programming are described here for modeling two chemical looping processes. The first is a nickel oxide based process developed at CSIC in Spain; the second is a iron oxide based process developed at Ohio State University. These mathematical models are then incorporated into a comprehensive process superstructure to evaluate the performance of chemical looping against technologies such as autothermal reforming and steam reforming for syngas production. The rest of the superstructure consists of process alternatives for liquid fuels production from syngas and simultaneous heat, power, and water integration. Among the various case studies considered, it is shown that chemical looping can reduce the break-even oil prices for natural gas-to-liquids processes by as much as 40%, while satisfying production demands and obeying environmental constraints. For a natural gas price of

Production of Liquid Transportation Fuels From Coal and Duckweed Biomass

5/TSCF, the break-even price is as low as

Multi-scale systems engineering for energy and the environment: Challenges and opportunities

32.10/bbl. Sensitivity analysis shows that these prices for chemical looping remain competitive even as natural gas cost rises. The findings suggest that chemical looping is a very promising option to enhance natural gas-to-liquids processes and their capabilities.

Biomass and Natural Gas to Liquid Transportation Fuels and Olefins (BGTL+C2_C4): Process Synthesis and Global Optimization

Abstract An optimization-based supply chain management framework for municipal solid waste (MSW) to liquid transportation fuels (WTL) processes is presented. First, a thorough analysis of landfill operations and annual amounts of MSW that are deposited across the contiguous United States is conducted and compared with similar studies. A quantitative supply chain framework that simultaneously accounts for the upstream and downstream WTL value chain operations is then presented. A large-scale mixed-integer linear optimization model that captures the interactions among MSW feedstock availabilities and locations, WTL refinery locations, and product delivery locations and demand capacities is described. The model is solved for both the nationwide and statewide WTL supply chains across numerous case studies. The results of the framework yield insights into the strategic placement of WTL refineries in the United States as well as topological information on the feedstock and product flows. The results suggest that large-scale WTL supply chains can be competitive, with breakeven oil prices ranging between