R&D for Gasifier Optimization/Plant Supporting Systems
Gasifiers operate under demanding conditions, presenting several challenges especially in regard to materials, where not only is the gasifier itself—more specifically the refractories—under severe physical and chemical stress, but so are any devices inserted to monitor and control the gasification process.
Availability is very important to the economics of a gasification plant. A shut-down gasifier halts synthesis gas (syngas) production and, therefore, final product output (electricity, liquid fuels, etc.). With current, state-of-the-art technology, many integrated gasification combined cycle (IGCC) designs incorporate a spare gasifier in order to achieve acceptable overall plant availability, even though this entails a higher capital cost. With continued operating experience and research, it is believed that an online availability of 85–95 percent in utility applications—and 95 percent for chemical production and other applications, can be achieved by a gasification plant, but currently, most plants cannot achieve that without redundancy or fuel backup:
- Tampa Electric Integrated Gasification Combined-Cycle Project – operating commercially since 1996, 82% gasifier availability and 74% plant availability.
- Wabash River Coal Gasification Repowering Project – operating commercially since 1995, reaching 79.1% plant availability, and 76% gasifier availability.
- Great Plains Synfuels Plant – operating since 1984, 98.7% days with production (i.e., not-zero production), although this is not traditionally how availability is measured.
- Elcogas SA IGCC, Puertollano, Spain – operating since 1998, provided 78.6% gasifier availability, and 48% overall plant availability as of 2007.
Research and development is being conducted to increase the availability of the gasifier and decrease the cost of operation and maintenance, thereby substantially optimizing gasifier operation. Examples include advanced materials development for refractory and the development of a reliable, practical and cost-effective means of monitoring real-time temperature in the gasifier through advances in sensors and instrumentation.
In addition to development of technologies such as advanced refractories and sensors, current research efforts also include development gasifiers for low-rank coal, creating models to better understand the kinetics and particulate behavior of fuel inside a gasifier, and developing practical solutions to mitigate the plugging and fouling of syngas coolers. All these research areas are further discussed below.