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DOE OSTI2016

Particulate solid attrition in CFB systems – An assessment for emerging technologies

Over the years, circulating fluidized bed systems have been designed for chemical conversion and energy recovery due to the ability of allowing continuous processing. While many CFB technologies are well established, a number of emerging technologies in recent years are utilizing the CFB concept, such as chemical looping combustion, novel continuous temperature swing adsorption, and transport gasifiers. A major uncertainty in these new technologies is the effect that attrition of bed material has on the overall process economics and system operability. Furthermore this work presents a review of the study of attrition for CFB systems, including relevant material properties, basic modeling and prediction, as well as particle population balance techniques. Because some of these new processes use novel materials, this work focuses on applying fundamental material properties to the understanding of attrition.

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2020

The Development of a Generalized Riser Flow Regime Map Based Upon Higher Moment and Chaotic Statistics Using Electrical Capacitance Volume Tomography (ECVT)

Dynamic analyses have been applied to the temporal signals from an Electro Capacitance Volume Tomography instrument located near mid-height on the riser of an industrial-scale cold-flow circulating fluidized bed to characterize gas-solids flow behavior in the riser. Twelve capacitance electrodes surround the cylindrical riser over a height of 1.3 m. The instrument used a neural network deconvolution algorithm to determine the spatially resolved solids fraction recorded at 52 Hz. Experiments were carried out over a range of gas and solids flows in the transport regime using a Geldart Group B bed material, high density polyethylene with mean particle size of 880 μm. The radial solids distribution was found to vary from one-time step to the next between profiles typical of laminar and turbulent flow. The duration of time spent in each of these flow profiles depended upon the operating regime – dilute, core-annular, or fast fluidized bed. The chaotic structure of the temporal data was characterized using the three conventional approaches: the first 4 moments from the distribution of signal in time, system memory parameters from the autocorrelation function and the Hurst exponent, and analysis of the correlationentropy and correlation dimension of the attractor. These signal analysis techniques were used to clearly distinguish differences between different transport operating regimes. Specifically, it was experimentally observed that a riser transitions from core annular flow profile to dilute and dense regimes via increasing the frequency of short term transients to either dilute or dense flow profiles, respectively. A regime map was generated based upon these dynamics using solids flux and gas velocity axes. Fast fluidized, core annular, and dilute each exhibited different degree of dynamic characteristics typical of fluid dominated or particle compromising behavior. It should be noted that the magnitude for the different statistics was in the same range regardless of the regime, it was the radial profile for the statistic that changed and subsequently identified that there was a change in the regime. Finally, a reduced regime map was developed consisting of plotting the gas velocity normalized by the upper transport velocity versus the solids flux normalized by the saturation carrying capacity. The use of this reduced plot allowed the data from widely different conditions to be plotted and compared on the samegraph. Note that in many instances, some of the statistics identified the operating point as being in one regime while others indicated that it was in another indicating a transition region between dilute or core annular regimes and between the core annular and fast fluidization regimes. This now provides a tool that can be used to optimize process performance, identify changes in operating states, or replicate process dynamics during process scaling or changing operating parameters.

Breault, Ronald↗

DOE OSTI2023

Scaling CFB risers: Beyond the data using microstructure similarity

Scaling circulating fluidized bed risers has been a point of contention for nearly a century. There have been numerous attempts to define various methodologies. These have all fallen short of providing a robust approach, primarily due to a lack of maintaining microstructure dynamics – a key factor in maintaining interphase heat and mass transfer. Recent work by the author put forward an approach based upon preserving dynamic similarity at different scales by ensuring that the microstructure remained similar by maintaining statistical and chaotic parameters across the scale. That work relied on a dimensionless regime map in which the x-axis was defined by the ratio of the solids flux to the saturation carrying capacity. This latter property was only good within the range of the data, and it became evident that extrapolation beyond the limits of the data could induce unrealistic conditions. Therefore, literature was reviewed to develop a better correlation for the saturation carrying capacity. In doing so, a critical riser diameter concept was developed and applied to the correlations for both Geldart Group A and B materials. The critical diameter for Geldart Group A and B materials is 0.2 m and 0.3 m, respectively. Here the paper then gives three examples on how to use the scaling approach to maintain dynamic similarity across the scales.

02 PETROLEUM↗

DOE OSTI2017

Techno-economic Evaluation of Utility-Scale Power Plants Based on the Indirect sCO 2 Brayton Cycle - Report

This report presents the results of a techno-economic analysis (TEA) of a coal-fired utility scale power plant based on the indirect supercritical carbon dioxide (sCO 2 ) Brayton cycle using an oxy-fired circulating fluidized bed (CFB). A baseline plant configuration was examined as well as three variations to the sCO 2 power cycle examining the impact of reheat (Rht), main compressor intercooling (IC), and a combination of reheat and main compressor intercooling (RhtIC). Each plant configuration was assessed at two turbine inlet temperatures of 620 °C and 760 °C.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2017

Techno-economic Evaluation of Utility-Scale Power Plants Based on the Indirect sCO2 Brayton Cycle - Presentation

This presentation discusses the results of a techno-economic analysis (TEA) of a coal-fired utility scale power plant based on the indirect supercritical carbon dioxide (sCO2) Brayton cycle using an oxy-fired circulating fluidized bed (CFB). A baseline plant configuration was examined as well as three variations to the sCO2 power cycle examining the impact of reheat (Rht), main compressor intercooling (IC), and a combination of reheat and main compressor intercooling (RhtIC). Each plant configuration was assessed at two turbine inlet temperatures of 620 °C and 760 °C.

Brayton power cycle↗

DOE OSTI2020

Verification and Validation of MFiX-PIC

This work is aimed at verification and validation (V&V) of particle-in-cell (PIC) approach in the National Energy Technology Laboratory’s (NETL) Multiphase Flow with Interphase eXchanges (MFiX-PIC) which was officially released in April 2019. Under verification, the results from MFiX-PIC are compared with exact or analytical solutions, while experimental results are used for benchmarking under validation. The test suite consists of the following cases: Terminal velocity. Particle advection in time-varying flow field. Particle settling in a dense medium. Evaporation. Rayleigh-Taylor instability. Minimum fluidization. Mini-circulating fluidized bed. The cases reported in a format consistent with the existing Verification and Validation Manual (Musser et al., 2018) explore a wide range of flow velocities and concentration regimes. Only one case considered in this work verifies the implementation of heat and mass transfer routines in MFiX-PIC, while a few other studies are currently underway to further expand the validation space in reacting flows. This study highlights the need for a rigorous analysis to objectively quantify the effect of model parameters. In addition, there is a scarcity of high-quality experimental data in the literature suitable for validating PIC methodology. Future efforts would include performing experiments which provide results for a valuable database. While designing such experiments, particle count should be significant to have sufficient particles per parcel while maintaining an optimal parcel to cell volume ratio. Also, datasets should have objectively assessed experimental uncertainty whereby confidence interval in those measurements become more explicit.

42 ENGINEERING↗

DOE OSTI2021

Optimized Performance and Cost Potential for Exemplar Indirect SCO 2 Coal Plants

This NETL report presents the techno-economic analysis (TEA) optimization results of coal-fired utility-scale power plants based on the indirect supercritical carbon dioxide (sCO 2 ) power cycles both with and without carbon capture and storage (CCS). For the plants without CCS, the heat source is an air-fired circulating fluidized bed (CFB). For plants with CCS, the heat source is an oxy-fired CFB. Four power cycle configurations were examined for this study: recompression cycle (RC) without and with reheat turbine (“RC without reheat” and “RC with reheat”), and partial cooling cycle (PCC) without and with reheat turbine (“PCC without reheat” and “PCC with reheat”).

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2023

Cost and Performance Baseline for Fossil Energy Plants Volume 3: Low Rank Coal and Natural Gas to Electricity

This report presents an independent assessment of the cost and performance of select fossil energy power systems—pulverized coal (PC), circulating fluidized bed (CFB), and natural gas combined cycle (NGCC) plants—using a systematic, transparent technical and economic approach. This is Volume 3 of a five-volume series, which comprise the following reports: Volume 1: Bituminous Coal and Natural Gas to Electricity; Volume 2: Coal to Synthetic Natural Gas and Ammonia (Various Coal Ranks); Volume 3: Low Rank Coal and Natural Gas to Electricity; Volume 4: Bituminous Coal to Liquid Fuels; and Volume 5: Natural Gas Electricity Generating Units for Flexible Operation. The cost and performance of fossil fuel-based generation technologies represented in this report (and the series at large) are important inputs to assessments and determinations of technology combinations to be utilized to meet the projected demands of future power markets. In addition to informing technology comparisons, the reference plant configurations found in this report provide perspective for regulators and policy makers. From a research and development perspective, this report is used to assess goals and metrics and to provide a consistent basis for comparing developing technologies.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2025

The Co-Firing of Pine Biomass and Waste Coal in 100 and 600 MW Power Plants: A Sustainable Approach to Reduce GHG Emissions

Climate change is a global issue that has gained much attention recently. Co-firing biomass with coal/waste coal reduces the electricity sector’s GHG emissions sustainably. This study uses commercial software to model waste coal and biomass co-firing in 100 MW and 600 MW power plants. The objective is to assess the effects of fluid types (subcritical and supercritical), plant capacities (100 MW and 600 MW), boiler types (pulverized coal and circulating fluidized bed boilers), biomass and waste coal co-firing ratios (0:100, 20:80, 40:60, 60:40, 80:20, and 100:0), and carbon capture and storage efficiencies (0%, 90%, 95%, and 97%) on performance parameters such as net plant efficiency, heat rate, net plant CO2 and SO2, and particulate matter emissions. The feedstocks selected for this investigation include anthracite waste coal and loblolly pine biomass. As the biomass fraction increases from 0% to 100%, co-fired power plants net efficiency increases by 3–8%. Supercritical plants had a 6% higher net plant efficiency than the subcritical plants. The study found that the biomass’s high heating value decreased the fuel flow rate and reduced plant CO2 emissions by 10–16%. With 100% biomass power plant feed and 90% carbon capture and storage efficiency, CO2 emissions drop by 83% and SO2 and PM emissions drop to zero.

Bhoi, Prakashbhai R. (ORCID:0000000333104888)↗

DOE OSTI2023

Particle Flow Distribution in a Fluidized-Particles Multitube Solar Receiver

A fluidized-particles two-tube solar receiver was tested at ambient temperature at PROMES Laboratory to investigate the influence of an inhomogeneous solar flux density on the particle mass flow rate between the tubes. The principle of this 3rd generation solar receiver is to fluidize the particles in a container, called dispenser, in which the tubes’ bottom are immersed. The fluidized particles are flowing upward the tubes by applying an overpressure in the dispenser. Air velocities are changed inside the tubes, thanks to air mass flow controllers, to represent temperature heterogeneity between the tubes. Air velocities from 0.05 up to 0.52 m/s were tested, both in homogeneous and heterogeneous conditions. In the heterogeneous ones, the differences in air velocity between the tubes aim to mimic a difference in temperature from 20 to 100 % with homogeneous air flow rates injected. The following conclusions were drawn. First, the particle mass flux in the tubes are the same with homogeneous air velocities, each one following a calibration map previously obtained. Second, different air velocities lead to different particle mass flux. Third, the rise of the total particle mass flux diminishes the pressure in the dispenser. Four, this diminution of pressure leads to a decrease of the particle mass flow rate of the tube with the lower air velocity. This influence can lead in some cases to the stop of the fluidized bed circulation in the affected tube.

Sahuquet, Guillaume (ORCID:0000000302752890)↗

DOE OSTI2012

Apparatus and method for determining solids circulation rate

The invention relates to a method of determining bed velocity and solids circulation rate in a standpipe experiencing a moving packed bed flow, such as the in the standpipe section of a circulating bed fluidized reactor The method utilizes in-situ measurement of differential pressure over known axial lengths of the standpipe in conjunction with in-situ gas velocity measurement for a novel application of Ergun equations allowing determination of standpipe void fraction and moving packed bed velocity. The method takes advantage of the moving packed bed property of constant void fraction in order to integrate measured parameters into simultaneous solution of Ergun-based equations and conservation of mass equations across multiple sections of the standpipe.

47 OTHER INSTRUMENTATION↗

DOE OSTI2015

Design of a Commercial Scale Oxy-Coal Supercritical CO2 Power Cycle

This presentation provides an overview of NETL’s analyses of the supercritical CO2 (SCO2) recompression Brayton cycle for application to commercial scale power plants with CO2 capture. This cycle has the potential to achieve over 50% efficiency due to the recuperation of heat from the SCO2 turbine exhaust, while the high SCO2 density may yield reductions in plant footprint and capital cost. Prior work has found that a circulating fluidized bed (CFB) with enhanced combustion air preheating would be a suitable indirect heat source for a SCO2 power cycle. This work investigates several options for efficiently integrating an oxy-fired CFB with an indirect SCO2 cycle, including thermal integration with the air separation unit, and utilization of combustor exhaust heat to thermally balance the low temperature recuperator. The sensitivity of plant performance to various cycle parameters is investigated, and the effect of design choices on the plant’s capital cost is discussed.

Weiland, Nathan↗

DOE OSTI2017

Overview and Systems Studies of Supercritical CO2 Power Cycles

This seminar discusses both indirect and direct-fired supercritical CO2 (sCO2) power cycles, briefly reviews the status of pilot plants under development for each of these cycles, and discusses NETL’s systems studies of coal-fueled commercial-scale sCO2 plants with carbon capture and storage (CCS).  Indirect sCO2 systems studied include an oxy-fired circulating fluidized bed heat source coupled to various sCO2 power cycles.  The direct-fired sCO2 cycle design is thermally integrated with a Shell gasifier to efficiently burn syngas within the oxy-combustor of the sCO2 cycle.  The performance and cost analyses of these plants are discussed, as well as comparisons to alternative cycles with CCS.  Results show that coal-fueled sCO2 plants of either type can exceed 40% HHV plant efficiency with CCS, and have a reduced cost of electricity relative to other cycles.  Other cycle configurations that offer further improvements in plant performance and cost-effectiveness are also discussed.

Weiland, Nathan↗

DOE OSTI2016

Development and Scale-Up of Copper-Based Chemical Looping with Oxygen Uncoupling

The University of Utah has been researching chemical looping with oxygen uncoupling of coal since 2007, focusing on copper-based carriers and a system configuration based on two interconnected circulating fluidized bed reactors. R&D has combined fundamental, lab-scale systems with operation of CLOU reactor systems at various scales and computational simulations for performance evaluation and reactor scale-up. Development has progressed from small lab scale through bench scale with a 10 kW dual bed research reactor to semi-pilot scale with a recently-inaugurated 220 kW chemical looping combustion process development unit. One of the challenges of scaling up copper-based CLOU technology is acquiring enough oxygen carrier material to support operation in larger reactor systems. The UofU CLC PDU, for example, requires 150-200 kg of inventory, so the oxygen carrier must be readily available in large quantities at comparatively low cost. Because no supplier capable of delivering 1+ tons of copper-based oxygen carrier material could be identified, an inexpensive oxygen carrier material was developed in-house and the carrier production process was scaled to produce large quantities of material sufficient for the CLC PDU. This presentation describes development of the CLOU process at the University of Utah, including evaluation of fundamental processes key to performance of CLOU, modeling and scale-up of the process, large-scale production of copper based oxygen carrier material and experience to date with the world’s largest dedicated CLOU reactor.

Whitty, Kevin J.↗

DOE OSTI2021

Process for generating high purity synthesis gas hydrogen from heavy oil or hydrocarbons

The present invention provides a steam reforming process for heavy oil or hydrocarbons using a circulating fluidized bed reactor, the process having a reforming step and a regeneration step, wherein the reforming step and the regeneration step comprise a fluidized reactor containing a fluidizable nickel-containing reforming catalyst and produce hydrogen as a product of the reforming bed. The invention produces high purity hydrogen in the synthesis gas product stream and avoids irreversible fouling on the catalyst.

Srinivas, Girish↗

DOE OSTI2023

Maintaining Microstructure – The Path to Successful Technology Maturation in Fluidized Systems

Scaling circulating fluidized bed risers has been a point of contention for nearly a century. There have been numerous attempts to define various methodologies. These have all fallen short of providing a robust approach, primarily due to a lack of maintaining microstructure dynamics – a key factor in maintain interphase heat and mass transfer. Recent work by the author put forward an approach based up maintaining dynamic similarity at different scales by ensuring that the microstructure remained similar by maintaining statistical and chaotic parameters across the scale. That work relied on a dimensionless regime map in which the x-axis was defined by the ratio of the solids flux to the saturation carrying capacity. This latter property was only good within the range of the data and it became evident that extrapolation beyond the limits of the data could induce unrealistic conditions. Therefore, literature was reviewed to develop a better correlation for the saturation carrying capacity. In doing so, a critical diameter concept was developed and applied to the correlations for both Geldart Group A and B materials. The critical diameter for Geldart Group A and B materials is 0.2 m and 0.3 m, respectively. The paper then gives examples on how to use the scaling approach to maintain dynamic similarity across the scales.

Breault, Ronald↗

DOE OSTI2015

Model-free adaptive control of advanced power plants

A novel 3-Input-3-Output (3.times.3) Model-Free Adaptive (MFA) controller with a set of artificial neural networks as part of the controller is introduced. A 3.times.3 MFA control system using the inventive 3.times.3 MFA controller is described to control key process variables including Power, Steam Throttle Pressure, and Steam Temperature of boiler-turbine-generator (BTG) units in conventional and advanced power plants. Those advanced power plants may comprise Once-Through Supercritical (OTSC) Boilers, Circulating Fluidized-Bed (CFB) Boilers, and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2019

Dover Light & Power 10 MWe Coal Direct Chemical Looping (CDCL) (Large Pilot Plant Test - Phase I Feasibility)

A feasibility study was conducted to install a 10 MWe coal direct chemical looping large pilot plant at a host site. The coal direct chemical looping technology was based on The Ohio State University and Babcock & Wilcox iron-based metal oxide technology coupling a moving bed reduction reactor with a circulating fluidized-bed oxidation reactor. The host site was the Dover Light & power Plant in Dover, Ohio. The Electric Power Research Institute performed the host site evaluation. Trinity Consultants prepared the Environmental Information Volume. WorleyParsons Group performed the civil engineering. Clear Skies Consulting served as lead on the Industrial Advisory Committee.

20 FOSSIL-FUELED POWER PLANTS↗