The goal of this project is to develop a gas compressor that can be installed directly in a pipeline, utilizing a variable speed induction motor with magnetic bearings. The project will advance the direct-coupled, seal-less, in-line electric motor driven compressor (IEMDC) to the stage where detailed manufacturing drawings can commence.

Dresser-Rand Company (D-R) – project management and overall research product 
Curtiss-Wright Electro-Mechanical Corporation (EMD) – electric motor design

Location:
Olean, New York 14760

A recognized need exists within the gas transmission industry for a new generation centrifugal compressor. The characteristics desired for this new compression system include: minimal maintenance requirements; capability of starting and stopping several times per day; easy installation; low total life cycle cost; and minimal environmental detriments. Several factors driving this need include: the increasing demand for natural gas, stringent environmental regulations, maintenance requirements of gas-fired equipment, and the age of the installed pipeline infrastructure.

Considering the current configurations of commercially available pipeline compressor systems, an alternative system designed for increased throughput to meet the growing demand on the aging pipeline infrastructure would provide an attractive solution to the challenges facing the gas industry. This system would need to be capable of readily replacing older compressors, re-powering compressor stations, and creating easily installed new compressor stations for the gas industry. Currently, there is an aging fleet of 20 to 50-year-old gas-driven compressors on pipelines. Maintaining this aging fleet of compression equipment can be a daunting challenge to gas pipeline operators due to: a) on site gas leakage; b) emissions that cause air pollution, c) availability and cost of spare parts, d) system monitoring capability, and e) noise. Many of these older installations use gas-fired compression equipment and lack operating flexibility, making it difficult to meet varying flow conditions. This is a concern given the projected growth in the gas market over the next decade. Therefore, the reliability, capacity, and efficiency of these older installations need to be upgraded through significant investment or replaced with more advanced and cost efficient designs.

The features of the compressor developed under this work, if fully developed and widely implemented, offer several potential impacts. The in-line design and small footprint offer the option for potential distributed compression, which by minimizing pressure drop losses between large stations, could increase the throughput capacity of the existing infrastructure by as much as 20% without the need for additional horsepower. In addition, the flexibility of operation of the VFD controlled electric motor offers an opportunity to more efficiently operate the system over a wider range of pipeline conditions, reducing associated losses, and making more gas available for consumption. The separable design and magnetic bearing offer the chance to reduce compressor maintenance costs and downtime, enhancing overall infrastructure delivery reliability. Finally, the hermetically sealed bearings and electric motor drive reduce compressor- based emissions often found with gas-driven systems, thus reducing lost product and overall environmental impact from product loss and combustion by-products.

• Performed initial economic analysis to confirm potential for commercial viability of IEMDC,
• Demonstrated the design feasibility of a direct drive high-speed motor controlled by a variable speed drive and capable of operating an integral pipeline compressor mounted on the motor shaft,
• Selected a supplier for the design of the magnetic bearing system (Kingsbury Magnetic Bearings)
• Selected a design approach for mechanically integrating the compressor and motor,
• Completed development of the compressor aerodynamic flowpath and pressure containment boundary.
• Finalized development of the high-speed, gas-cooled motor
• Completed development of the motor drive specification
• Completed definition and engineering of the compressor/motor interfaces, including cable penetrations, gas cooling configuration, motor-mounting arrangement, system rotor dynamics, and system controls.
• Initiated commercialization activities.

The final in-line configuration of the IEMDC, as compared to existing compressor systems, makes this a potentially attractive solution for the gas pipeline industry. It advances the concept of installing electrically-powered, highly flexible, efficient, low maintenance compression by a combination of features that no other product currently offers as a complete package. It offers a compact design featuring a small footprint by the use of single stage compression utilizing an overhung impeller at the compressor end of the integrated electric motor shaft. Due to it's small footprint, the IEMDC offers competitive advantages as new compressor station equipment or for re-powering an existing station.

The IEMDC offers significant capabilities for a compressor with an integrated variable speed electric motor system, a high power density, a unique compressor modular bundle design and a hermetically sealed system levitated by magnetic bearings. The design is a single stage unit offering accessibility for ease of maintenance without the necessity of disconnecting the piping, and the integrated electric motor compression system offer flexibility through the full operating range of the IEMDC. 

and Remaining Tasks:
Work under this project has been completed with performance and structural design taken to the point where detailed engineering drawings could be developed. Final deliverables provided include design specifications for all components. Follow-on work to the project includes potential commercialization efforts by the performer. Efforts are underway to locate a customer to fund or purchase the initial physical development model of the system design.

$937,054

$803,965

NETL – Richard Baker (richard.baker@netl.doe.gov or 304-285-4714)
Dresser-Rand – Harry F. Miller (716-375-3316)

Final Technical Report  [PDF-3700KB] 
Gas Machinery Conference 2003 Presentation  [PDF-3375KB] 
ASME paper  [PDF-707KB]