Thomas A. Adams

Chapter 6 – Processes and simulations for solvent-based CO2 capture and syngas cleanup

Abstract This chapter provides a detailed methodology for constructing steady-state flow sheet simulations of common solvent-based CO2 and H2S capture processes using popular commercial software. Detailed examples are provided for solvents such as monoethanolamine, methyldiethanolamine, DGA, Piperazine, Selexol, and Rectisol in a variety of applications, such as integrated gasification combined cycles, gas-to-liquid plants, coal-to-liquid plants, natural gas combined cycles, and sweet and sour gas cleaning. Tutorials are provided for Aspen Plus, Aspen Hysys, BRE ProMax, and Invensys Pro/II, with screen captures, step-by-step guides, and expert advice designed to make the construction of these notoriously difficult simulations as easy as possible. Twenty-one different examples are discussed, with completed simulation files available for download for the reader.

Effect of moderate static electric field on the growth and metabolism of Chlorella vulgaris.

An electric field (EF) generator device was fabricated and applied to the treatment of Chlorella vulgaris ISC33 at three distinct concentrations before cultivation. The EF of moderate intensity (2.7kVcm(-1)) has a hormetic effect on algal growth. The highest growth stimulation of 51% was observed after 50min treatment of 0.4gL(-1) algal suspension. The influence of EF on the system was then studied from both theoretical and experimental perspectives. The growth rate increased with treatment time up to a maximum because of improved membrane permeability, and then declined afterwards due to peroxide accumulation in the medium. The contents of chlorophylls, carotenoids, soluble carbohydrates, lipids, and proteins were also measured to understand possible changes on algal metabolism. The EF treatment of algal suspension has no observable effect on the cell metabolism while both algal growth and metabolism was significantly affected by the inoculum size.

Fuel Composition Transients in Fuel Cell Turbine Hybrid for Polygeneration Applications

Transient impacts on the performance of solid oxide fuel cell / gas turbine (SOFC/GT) hybrid systems were investigated using hardware-in-the-loop simulations (HiLS) at a test facility located at the U.S. Department of Energy, National Energy Technology Laboratory. The work focused on applications relevant to polygeneration systems which require significant fuel flexibility. Specifically, the dynamic response of implementing a sudden change in fuel composition from syngas to methane was examined. The maximum range of possible fuel composition allowable within the constraints of carbon deposition in the SOFC and stalling/surging of the turbine compressor system was determined.It was demonstrated that the transient response was significantly impact the fuel cell dynamic performance, which mainly drives the entire transient in SOFC/GT hybrid systems. This resulted in severe limitations on the allowable methane concentrations that could be used in the final fuel composition when switching from syngas to methane. Several system performance parameters were analyzed to characterize the transient impact over the course of two hours from the composition change.Copyright

Shale gas for the petrochemical industry: Incorporation of novel technologies

In this work, a new shale gas-based polygeneration system with essentially zero CO2 emissions is proposed that co-produces methanol, dimethyl ether (DME), olefins and power. The thermal and economic analysis of the proposed process is performed to determine the optimum product portfolio regarding current market prices. The optimization results show that production of methanol/DME and power can improve the performance of the olefin production section significantly. Therefore, the proposed plant can link the shale gas industry to the petrochemical sector efficiently and in an environmentally friendly way.

Techno-economic Analysis of a Thermochemical Lignocellulosic Biomass-to-Butanol Process

A novel continuous lignocellulosic biomass-to-butanol process using a thermochemical route and a mixed-alcohol synthesis catalyst has been developed. The process was designed and modeled using Aspen Plus and consists of major process steps such as biomass drying; indirect steam gasification; syngas cleanup and conditioning; mixed-alcohol synthesis over a modified methanol catalyst; alcohol separation; and utilities including cooling water, steam, and power generation. A heat integration analysis was also carried out, resulting in an energy-sufficient process with no requirement for external hot utilities and net power production. A technoeconomic analysis was carried out using results of the Aspen Plus model, equipment cost estimates, and discounted cash flow analysis, with an assumption of nth-plant costs and financing resulting in a minimum butanol selling price (MBSP) of

Challenges and Opportunities in the Design of New Energy Conversion Systems

0.83/L. Different plant and cost parameter scenarios were rigorously explored using a sensitivity analysis.

Integrated Design and Control of Semicontinuous Processes Using Mixed Integer Nonlinear Dynamic Optimization

Abstract In this perspective, an overview of the key challenges and opportunities in the design of new energy systems is presented. Recent shifts in the prices of natural energy resources combined with growing environmental concerns are creating a new set of challenges for process design engineers. Due to the massive scale and impact of energy conversion processes, some of the best solutions to the energy crisis lie in the design of new process systems which address these new problems. In particular, many of the most promising solutions take a big-picture approach by integrating many different processes together to take advantage of synergies between seemingly unrelated processes.

Fuel composition transients in fuel cell turbine hybrid for polygeneration applications

Abstract Semicontinuous separation is a distillation based process intensification technique devised for the purification of ternary mixtures to desired purities. It is particularly promising for small scale production processes where the semicontinuous system has a lower total annualized cost relative to the conventional continuous process, thus it can be a suitable option for the purification of biofuels. Semicontinuous systems are dynamic, control driven processes that work in a stable limit cycle with several modes of operations. Therefore, designing the system and its controllers is a challenging task which has not been thoroughly considered in the literature. In this work, for the first time, a methodology is presented to simultaneously obtain the optimum design parameters of the semicontinuous system such as the number of column stages, feed and side stream locations, as well as the optimum tuning parameters for the PI control structure. To design the semicontinuous process, it is formulated as a mixed integer nonlinear dynamic optimization problem using the equation oriented gPROMS software which has built-in deterministic optimization packages. The benzene, toluene and o-xylene mixture is chosen as a case study to demonstrate the methodology. The optimization took 1.03 CPU hours and the optimum design parameters are obtained. The results show that the total annualized cost of the designed semicontinuous system is lower than the respective conventional continuous process.

Clean Coal: A new power generation process with high efficiency, carbon capture and zero emissions

Transient impacts on the performance of solid oxide fuel cell / gas turbine (SOFC/GT) hybrid systems were investigated using hardware-in-the-loop simulations (HiLS) at a test facility located at the U.S. Department of Energy, National Energy Technology Laboratory. The work focused on applications relevant to polygeneration systems which require significant fuel flexibility. Specifically, the dynamic response of implementing a sudden change in fuel composition from syngas to methane was examined. The maximum range of possible fuel composition allowable within the constraints of carbon deposition in the SOFC and stalling/surging of the turbine compressor system was determined.It was demonstrated that the transient response was significantly impact the fuel cell dynamic performance, which mainly drives the entire transient in SOFC/GT hybrid systems. This resulted in severe limitations on the allowable methane concentrations that could be used in the final fuel composition when switching from syngas to methane. Several system performance parameters were analyzed to characterize the transient impact over the course of two hours from the composition change.Copyright

Understanding the dynamic behaviour of semicontinuous distillation

Abstract An environmentally friendly electricity generation process using coal gasification and solid oxide fuel cells (SOFCs) produces electricity with high efficiency, 99.95% carbon capture and essentially zero atmospheric emissions. Coal is gasified into syngas, cleaned and shifted to hydrogen gas to fuel SOFCs. The primary waste products, CO2 and H2O, are separated with a very small energy penalty. The carbon dioxide purity is high enough to meet most specifications for geological sequestration. Even with carbon capture capability, the power plant has a higher efficiency (4-10 percentage points) than standard pulverized coal or integrated gasification combined cycle processes without carbon capture and consumes significantly less fresh water. If cooling towers are replaced with dry-cooling technology, net water can be produced and recovered, rather than consumed. Moreover, under a cap-and-trade scenario, the process has the lowest cost-of-electricity, even with carbon capture, for carbon prices above