Project No: FC26-99FT40685
Performer: Center for Photonics Technology


Robert Romanosky
Crosscutting Research Technology Manager
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880 
Morgantown, WV 26507-0880

Jenny Tennant
Gasification Systems Technology Manager
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV   26507-0880

Susan Maley
Project Manager
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880 
Morgantown, WV  26507-0880

Anbo Wang
Principal Investigator
Virginia Polytechnic Institute and State 
Center for Photonics Technology
460 Turner Street Suite 303
Blacksburg, Virginia 24061

Award Date:  10/01/1999
Project Date:  12/31/2013

DOE Share: $3,227,786.00
Performer Share: $847,596.00
Total Award Value: $4,075,382.00

Performer website: Center for Photonics Technology -

Crosscutting Research - Plant Optimization Technologies

Single-Crystal Sapphire Optical Fiber Sensor Instrumentation

Project Description

This system utilizes a sapphire-based fiber and a sapphire wafer to form a point sensor (Figure 1) that is referred to as an extrinsic Fabry-Perot interferometric (EFPI) sensor. The EFPI sensor records temperature data from inside the gasifier at temperatures up to 1,600 °C.

The project approach is based on the optical path difference (OPD) between reflections from the two surfaces of a sapphire wafer. The two reflections will interfere with each other, producing a modulated spectrum, the pattern of which is determined by the optical thickness (OT) of the wafer. The OT is the product of the refractive index and the thickness of the wafer, both of which have thermal dependence, resulting in a temperature-sensitive OT and spectrum. Therefore, the temperature can be determined from the change in the reflected spectrum.

Single-crystal sapphire sensor heads with sapphire fiber waveguides achieve greater precision through miniaturization

Single-crystal sapphire sensor heads with sapphire fiber waveguides achieve greater precision through miniaturization.

Program Background and Project Benefits

Gasification is used to convert a solid feedstock, such as coal, petcoke, or biomass, into a gaseous form, referred to as synthesis gas or syngas, which is primarily hydrogen and carbon monoxide. With gasification-based technologies, pollutants can be captured and disposed of or converted to useful products. Gasification can generate clean power by adding steam to the syngas in a water-gas-shift reactor to convert the carbon monoxide to carbon dioxide (CO2) and to produce additional hydrogen. The hydrogen and CO2 are separated—the hydrogen is used to make power and the CO2 is sent to storage, converted to useful products or used for EOR. In addition to efficiently producing electric power, a wide range of transportation fuels and chemicals can be produced from the cleaned syngas, thereby providing the flexibility needed to capitalize on the changing economic market. As a result, gasification provides a flexible technology option for using domestically available resources while meeting future environmental emission standards. Polygeneration plants that produce multiple products are uniquely possible with gasification technologies. The Gasification Systems program is developing technologies in three key areas to reduce the cost and increase the efficiency of producing syngas: (1) Feed Systems, (2) Gasifier Optimization and Plant Supporting Systems, and (3) Syngas Processing Systems.

Gasifier Optimization and Plant Supporting System technologies under development are targeted at increasing gasifier availability and efficiency, improving performance, and reducing the capital and operating costs of advanced gasification plants. Ongoing R&D projects are developing more durable refractory materials, 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. Future work will focus on the development of cutting edge gasifier technologies, which will start with multiple competing concepts and continue with support of the most aggressive and successful technologies being developed, both in the Gasification Systems program and other DOE programs, to reduce the cost of coal gasification. Future work will also aim to reduce the amount of water used in gasification plants and integrate technologies throughout the plant and beyond in a holistic approach to increase efficiency and reduce costs (e.g., the optimization of gasification plants to sell CO2 for EOR applications).

The Center for Photonics Technology at Virginia Polytechnic Institute and State University is conducting research to design, construct, and test an optically based temperature sensor capable of operating accurately and reliably within the harsh conditions of a coal gasifier. The sensor uses single-crystal sapphires to make optically-based measurements providing real-time monitoring of the high temperatures enabling better control and to increase the reliability and efficiency of gasifier systems including integrated gasification combined cycle.


This effort succeeded in developing and testing a prototype temperature measurement system under full-scale operating conditions thus creating a important opportunity for process improvement, cost reduction, and greater efficiency. Specific accomplishments include: