Overview of Important Considerations in Wet Gas Compression Testing and Analysis
During upstream production of natural gas fields, it is common that a gas-liquid mixture of product is brought to the surface. The mixture, termed wet gas, is generally made up of mostly gas with a small amount of liquid, typically up to 5% by volume of the mixture. Because of the difficulties of compressing wet gas, the practical approach has been to separate the liquid and gas phases before compression. However, large separation equipment is unfavorable for subsea installations because of the cost to place machinery on the sea floor. Instead, a compressor designed for wet gas operation is preferred because it eliminates the need for large separation equipment leading to plant simplification and cost reduction. To address this design need, researchers have been active in addressing the challenges with wet gas compression. As result, experimental work has been conducted to study the effects of wet gas on compressor aerodynamic and mechanical performance. This experimental research has presented many challenges in recreating wet gas conditions and quantifying the effect of the liquid on the compressor performance. The results from this testing have helped to characterize the performance effects. But so far each work has focused on a range of test variables without identifying those that have the largest effect on compressor performance. This paper aims to provide the reader with an overview of the completed wet gas research, the challenges associated with doing the experimental work, and a discussion of the resulting trends observed in most of the wet gas research. This will include an in-depth review of relevant literature on wet gas compression testing and performance, a discussion of the important
Measured Effects Of Liquid Distribution On Compressor Performance During Wet Gas Ingestion
Upstream production of natural gas is commonly a mixture of both liquid and gas hydrocarbons that is separated before boosting the gas or liquid flows to higher pressure for transport. The gas-liquid mixture is known to affect the compressor performance, but it is not known if the distribution of the liquid entering the compressor affects the maximum amount of liquid that the compressor can safely ingest. The work presented in this paper determines if liquid atomization affects the compressor operation or influences the amount of liquid that can be safely ingested by the compressor, compared to non-atomized liquid. To determine the effect of atomization on compressor performance, three injection methods are used to characterize the performance for atomized and non-atomized flow. Non-atomized flow is generated by injecting liquid far upstream of the compressor to allow a natural two-phase flow regime to develop before entering the compressor. Atomized flow is generated near the compressor suction flange using liquid pressure to generate large droplets on the order of 2,000 m and gas-assisted atomization to generate droplets at least an order of magnitude less than the large droplets (100 m). Results of the work are reported in this paper to include compressor performance measurements for two rotation speeds and a range of liquid and gas flow rates. In addition, the control of the compressor during wet gas ingestion is demonstrated through movement of the compressor on the flow map. Finally, high-speed flow images of the liquid entering the compressor are qualitatively shown to illustrate the difference in injection method.
MAT, a novel, open cycle gas turbine for power augmentation
Abstract A Moisture Air Turbine (MAT) cycle is proposed for improving the characteristics of land-based gas turbines by injecting atomized water through an inlet into a compressor. Compressor work of isentropic compression for moist air mixtures with phase change is theoretically considered, which has revealed that water evaporation may reduce compressor work. An experiment using a 15 MW class axial flow load compressor has also verified the theory. Realistic cycle model calculations predict that a 10% power increment by a ratio of 1% water to compressor intake air is expected and also that the amount of water consumption is much less than that of conventional inlet air cooling systems, used for heat rejection at the cooling tower. In addition, thermal efficiency is anticipated to be improved mainly due to the reduction of compressor work. Contrary to the conventional evaporative cooler, a MAT cycle could provide power output at a desired value within its capability regardless of ambient humidity condition.