NETL Researchers Develop Sensor for Detection of Defects in Buried Natural Gas Plastic Pipelines

	NETL's innovative flexible sensor conforms to the pipe wall using flexible circuit board materials. This technology can inspect plastic pipelines for small scale voids, cracks, holes and defects.

Researchers at NETL have developed the first technology that can detect flaws in plastic natural gas pipelines without disrupting pipeline operations.

The innovative flexible sensor conforms to the pipe wall using flexible circuit board materials.  This technology can inspect plastic pipelines for small scale voids, cracks, holes and defects.

The researchers have already published one paper and a new paper has been submitted for publication in the Review of Scientific Instruments. Two patent applications have been filed.

Over 500,000 miles of polyethylene plastic natural gas pipeline have been installed over the past 45 years in North America and there is a need to inspect these pipes for brittle cracking, excavation damage, and other safety hazards.

The NETL sensor includes a multi-layer laminate made of alternating layers of copper sheet and Kapton. It is fabricated with circuit traces and sensor electrodes chemically etched into the copper sheet, then it is sealed together with pressure and adhesive to form a flexible sensor.

A negative photo-lithographic technique is used to create the electrode shapes and circuit wiring on the individual levels ensuring uniformity from sensor to sensor. 
This new sensor is compact, thin and flexible allowing it to conform to the pipeline inside wall surface with minimal air gap to ensure accurate capacitive sensing.

Plastic can be tested for the presence of cracks and voids by using capacitance measurements taken against the pipe wall.  This capacitive sensor technology is now able to analyze the entire 360° circumference of a pipeline wall from the inside. 

The newest accomplishments include a flexible sensor that can adapt to the shape of the inner pipeline wall and a multi-sensor pig that can traverse the inside of a pipeline without excavating.

	This early prototype shows the hollow glass fibers of the hydrogen separation module prior to insertion into the housing.

NETL Tests Novel Membrane Prototype

NETL has fabricated and tested a prototype of a novel hydrogen separation module developed at NETL.

The membrane module performed successfully in tests at temperatures ranging from 400 to 800°C. 

The prototype consists of hollow, thin-walled glass fibers, and has hydrogen production capabilities comparable to commercial scale membrane materials on a volumetric basis. Additionally, the prototype membrane has shown promising selectivity for hydrogen over carbon dioxide.

Refractory Compositions Have Potential for Slagging Gasifier Liners

	Researcher Hugh Thomas examines NETL refractory test bricks being developed to improve commercial refractory compositions.

Researchers from NETL have worked with refractory companies to evaluate and improve existing commercial refractory compositions. Rotary slag testing of 14 of these compositions in flowing gasifier slag at 1600oC for five hours has identified five with potential for use in slagging gasifiers.

Discussions are underway with commercial gasifier users for field trials to evaluate those compositions with promise of extending gasifier online service life.

Slagging gasifiers are lined with high chrome oxide refractory materials that must be replaced every three to 36 months, a service life that depends on gasifier environment (temperature and pressure), the amount and type of carbon feedstock, and the amount of cycling between room and gasification temperature. Refractory wear occurs by two means, corrosion and spalling.

The current service life does not meet the performance needs of gasifier users, and limits achieving an online gasifier availability of 85-95% for utility applications and greater than 95% in applications such as chemical feedstock production. 

Failure to meet these criteria has created a potential roadblock to widespread acceptance and commercialization of advanced gasification technologies, and is a reason refractory liners were identified as a key barrier to wide spread commercialization of gasification technology.

NETL Completes Oxy-fuel Turbine Exposure Tests

	These are two of the preoxidized low cycle fatigue specimens that were oxidized by NETL and sent to Siemens for the fatigue testing.

NETL researchers in the Materials Performance Division have completed 1,000-hour exposures of a promising technology to generate electricity from turbines powered from oxygen-fired fuels. The technology will allow CO₂ capture to occur more economically than using air-fired fuels. 

The intermediate pressure turbine, which operates at the highest temperatures in the proposed system, will at this stage of development utilize existing gas turbine technology.

The oxy-fuel turbine steam-CO₂-oxygen environment, however, is different, and perhaps more aggressive, than gas turbine environments. NETL researchers are evaluating materials performance of nickel-base and cobalt-base superalloys and superalloy/coating systems in the oxy-fuel turbine environment to qualify them for use.

Evaluated properties include oxidation behavior and low cycle fatigue (LCF) resistance.  Researchers in the Materials Performance Division of NETL have completed 1000 hour exposures in H₂O-10%CO₂-0.2%O₂ at 630, 693, 748, and 821 °C of oxidation and low cycle fatigue (LCF) specimens.  The oxidation behavior is being examined using microstructural evaluation at NETL.  LCF behavior is being examined by Siemens as part of the Zero Emissions Coal Syngas Oxygen Turbo Machinery Cooperative Agreement.