Session: 20-03: Hydrogen and Natural Gas Compression and Infrastructure

Paper Number: 151989

Development of Hydrocarbon Gas Compressor With Integral Motor and Foil Bearing 

Turbo compressors have been indispensable equipment in oil and gas industry. Compressors increase pressures for gas fluid flows and phase changes in gas processing and refrigeration systems. Despite of advantages in size and efficiency, turbo compressors could not be widely applied for small capacity compressions due to high equipment cost and difficulties in high-speed rotor system design in comparison with reciprocating and screw compressors. With the reason, there has been virtual lower capacity limit of turbo compressor application and could not penetrate the reciprocating compressor dominant region. However, introduction of new technologies developed over many years of efforts from non-mechanical disciplines may demolish the traditional division boundary. High-speed inverter technology can replace heavy speed increasing mechanical gear system, magnetic or foil bearing can eliminate the lubrication oil system, and integral motor imbedded in the compressor casing can liberate the complicated gas sealing headaches from rotating system. By combining the technologies obtained from other sectors of industry, simplified and cost-effective turbo compressor solutions have been derived. Additionally, explosion protection technology for hydrocarbon gases has been developed through extensive studies and experiments on gas explosion mechanisms and investigations on relevant industrial regulations. In this paper, development of innovative compressor design, tests, and applications are introduced. The developed compressor has been tested for wide temperature ranges including very cold, typically -161 ^oC, boil-off gas from liquefied natural gas (LNG). Performance tests for the cryogenic temperature conditions also have been carried out. The compressor can handle various gases of methane, ethane, propane, butane, and multi-component hydrocarbon gases. Foil bearing has been used in industry for many years. However, the foil bearing technology application has been confined to turbo blowers and low-pressure air compressors, and no references have been existent for flammable gases. The reason could be difficulties in the compliance of explosion protection requirement in explosive gas ridden hazardous areas. Special gas-tight integral casing design and electric power feeder-through have been devised to get over the task. The developed compressor has been tested with diverse gases for oil and gas industry and refrigeration system. Since the compressor is hermitically sealed type, no leaked gas is emitted to the atmosphere from the rotating shaft and coupling, which contribute to the environment, whereas constant leaks of hydrocarbon gas are inevitable for most of industrial gas compressors. The compressor is very high speed, hence the weight of the developed compressed is very small compared with conventional turbo compressor and reciprocating or screw type ones. The typical speed of the developed compressor is 50,000 ~ 80,000 RPM (revolution per minute). For diverse kinds of gas, simulated gas from very light to heavy gases have been artificially tailored and utilized for the tests. Cryogenic heat exchanger also has been used to simulate very cold inlet temperature gas condition. Logging system connected with pressure, temperature, and flow transducers, has been prepared for detailed analysis of the compressor performance in various inlet conditions and compositions. Pressure ratios, actual volume versus pressure curves, isentropic head rise, surge point, electric power consumption, and vibration level under diverse inlet temperature, pressure, gas compositions, and compressor speed (RPM) have been obtained through experimental tests. The developed compressor is in commercialization (field application) stage, and it would be competitive to traditional reciprocating compressor range in oil & gas and hydrocarbon refrigeration system with the inherent compactness, easy of maintenance, and environment friendliness characteristics. The developed compressor can be used for natural gas compression, propane and natural gas liquefaction, and hydrocarbon base refrigeration systems. The innovative compressor incorporated with other discipline technologies and intensive design improvements and field tests would contribute to the industry with less material and less pollution to the environment.  

Presenting Author: Junghan Lee Cluster LNG Co., Ltd.

Presenting Author Biography: JungHan Lee is currently president of Cluster LNG. He founded the company in 2013 after 33 years work at DSME (South Korean Shipyard). His last position at DSME was executive vice president and head of R&D institution. Cluster LNG company specializes in small scale LNG liquefaction and LNG turbo machinery. He has published many innovative papers on LNG (liquefied natural gas) technologies and holds many international patents. Some of his patents have been applied to many LNG carriers and offshore floating storage re-gasification units (FSRU) and became de facto industrial standards, such as LNG fuel gas supply system and sealed LNG. He has a BS degree in Naval Architecture from Seoul National University, and an Ocean Engineer’s Degree from Massachusetts Institute of Technology.

Authors:

Junghan Lee Cluster LNG Co., Ltd.
Daehyuk Lee Cluster LNG Co., Ltd.