Advanced Gasification
Advanced Gasification

Carbon feedstock gasification is a promising pathway for high-efficiency, low-pollutant power generation and chemical production. The inability, however, to meet a number of operational goals could create roadblocks to widespread acceptance and commercialization of advanced gasification technologies. We must, for example, achieve gasifier online availability of 85–95 percent in utility applications, and 95 percent for chemical production and other applications so the service life of gasifiers can meet the performance needs of industry. To do so, we need new technologies that address carbon conversion, slag viscosity, and downstream fouling. Technologies that reduce the cost of CO2 separation and capture are also required.

The National Energy Technology Laboratory (NETL) Gasification Team and members of the NETL-Regional University Alliance (NETL-RUA) are taking an integrated approach to developing physics-based methods, models, and tools that can support the development and deployment of advanced gasification devices and systems.

High Resolution Simulations using NETL’s computational models.

AVESTAR™ Center The NETL Advanced Virtual Energy Simulation Training and Research (AVESTAR™) Center is pursuing a collaborative, innovative, internationallyrecognized R&D program to achieve operational excellence in current and next-generation gasification-based power plants, with or without carbon capture. Research has concentrated on developing high-fidelity dynamic models of coal-fired gasifiers, the centerpiece of integrated gasification combined cycle (IGCC) power plants. The models maximize the efficiency and profitability from plant operations through process control and by maximizing business value from all plant assets - all while reducing negative environmental impact and improving safety. The AVESTAR™ Center brings together dynamic simulation-based technologies, state-of-the-art facilities, and leading energy researchers. Current R&D efforts are focused on the areas of dynamic process modeling, advanced process control, and optimal sensor placement. AVESTAR™ will also be instrumental in preparing an industry workforce trained to safely and effectively operate, control, and manage commercial-scale IGCC systems with CO2 capture.  www.netl.doe.gov/avestar

 

Carbon feedstock gasification is a promising pathway for high-efficiency, low-pollutant power generation and chemical production. The inability, however, to meet a number of operational goals could create roadblocks to widespread acceptance and commercialization of advanced gasification technologies. We must, for example, achieve gasifier online availability of 85–95 percent in utility applications, and 95 percent for chemical production and other applications so the service life of gasifiers can meet the performance needs of industry. To do so, we need new technologies that address carbon conversion, slag viscosity, and downstream fouling. Technologies that reduce the cost of CO2 separation and capture are also required.

The National Energy Technology Laboratory (NETL) Gasification Team and members of the NETL-Regional University Alliance (NETL-RUA) are taking an integrated approach to developing physics-based methods, models, and tools that can support the development and deployment of advanced gasification devices and systems.

AVESTAR™ Center The NETL Advanced Virtual Energy Simulation Training and Research (AVESTAR™) Center is pursuing a collaborative, innovative, internationallyrecognized R&D program to achieve operational excellence in current and next-generation gasification-based power plants, with or without carbon capture. Research has concentrated on developing high-fidelity dynamic models of coal-fired gasifiers, the centerpiece of integrated gasification combined cycle (IGCC) power plants. The models maximize the efficiency and profitability from plant operations through process control and by maximizing business value from all plant assets - all while reducing negative environmental impact and improving safety. The AVESTAR™ Center brings together dynamic simulation-based technologies, state-of-the-art facilities, and leading energy researchers. Current R&D efforts are focused on the areas of dynamic process modeling, advanced process control, and optimal sensor placement. AVESTAR™ will also be instrumental in preparing an industry workforce trained to safely and effectively operate, control, and manage commercial-scale IGCC systems with CO2 capture.  www.netl.doe.gov/avestar

Warm Gas Cleanup
Palladium-based sorbents are among the most promising candidates for the high-temperature, one-step capture of trace elements from coal-derived fuel gases which will reduce the footprint, cost, and complexity of pollution mitigation. NETL research on gas cleanup is focusing on testing and developing palladium sorbents for the capture and removal of trace metals like mercury, arsenic, selenium, phosphorus, and cadmium (cocapture). NETL is also studying the removal and detection of these and other contaminants from fluid streams using techniques that include sorbent, catalyst, analytical, photochemical, and electrochemical methods. Capacity for capture is being determined in simulated fuel gases through the use of laboratory-scale packed-bed reactors and at larger scales in slipstreams of real fuel gas at an actual gasification facility. Warm gas cleanup research promotes the utilization of abundant domestic coal in a clean and environmentally friendly manner. Technology developed under this project will allow gasification to meet stringent EPA regulations for trace metal emissions. Three capture technologies developed by NETL were recently licensed to industry.

 
Changes in refractory wear between old technology (left), NETL developed (center), and unused refractory (right) after similar exposure in a commercial gasifier. Less wear in the newly developed refractory will result in longer service life and reduced downtime for gasifier repair.

Refractory Improvement
Coal and petcoke, common carbon feedstock in slagging gasifiers, are typically high in mineral impurities, materials which significantly impact slag viscosity and refractory wear. Research aimed at refractory improvement is focused on refractory development and the impact of additives on carbon feedstock ash behavior and refractory wear. Refractory service life improvement through material development or modeling and the control of slag chemistry is being evaluated via laboratory testing at NETL and through the cooperation of industry gasifier operators. Slag management for optimum gasifier service is being accomplished by developing a slag model to allow gasifier operators control of slag viscosity, maximize refractory service life, and minimize downstream material issues like syngas fouling. A modeling program is undergoing evaluation at a commercial gasifier site to control slag properties and minimize refractory wear.

 
Temperature inside the
high speed HS-TGA.

Low-Rank Coal Optimization

Research in this area focuses on the development of gasification performance prediction models to reduce uncertainties associated with the use of low-rank coals and co-feeds, including low-rank coal and biomass. The development of a hierarchy of co-feed trigonometric models with uncertainty quantification will provide a practical framework for quantifying various types of uncertainties and rank assessing the impact of their gasification through computer models of the physical system. Reducing the uncertainty associated with different carbon feedstock materials will enable designers and operators of gasifiers to predict and understand material behavior prior to utilization, leading to more efficient use of these materials.

Conversion and Fouling
Accurate physical models are currently unavailable for predicting and controlling rates of slag buildup in a gasifier and ash deposition in a convective syngas cooler. Problems associated with ash buildup can lead to gasifier shutdown. Plants have experienced problems such as lower carbon conversion and plugging of syngas coolers with fly ash, a problem that can be severe enough to lead to plant shutdown. Overall impact is reduced plant heat recovery, strain on solids handling and grey water circuits, and a reduction in the overall reliability of the gasifier.

 
Convective syngas cooler fouling source
Global Energy, Inc.

Research in this area has focused on establishing how slag iron and vanadium oxide content, as well as oxidation state, impact slag viscosity and is aimed at negating plugging and fouling throughout the syngas cooling system. Control of slag properties will lead to an increased capability to control gasifier performance and to determine the impacts and limits of using various coal grades and petcoke in entrained gasifiers. In addition, development of computational simulation tools will reduce uncertainty associated with the use of low-rank coal and mixed feeds. Results of this work will aid in gasifier design and performance relative to the use of these fuels, allowing for fuel flexibility in current and future gasification facilities.

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