An Approach to Compact, Wet Gas Compression

Abstract

In recent years, several papers have been written regarding the use of centrifugal compression technology to handle applications in which the process gas entering the equipment contains a significant amount of liquids, and can therefore be considered a wet gas. One such application that is currently being considered by many oil and gas operators is the installation of processing and compression equipment on the sea bed, to directly handle the process gas stream in close proximity to the wellhead. Other applications also exist topside, in which the operator would benefit from the installation of additional compression and processing capabilities at brown field facilities. Most of these existing installations have limited space for expansion and have strict size and weight limitations that have to be met by the additional equipment. This, in many cases, hinders the utilization of traditional compression and processing equipment, which is typically arranged using the large and heavy multi deck approach. A novel integrated compression system (ICS) has recently been developed to address the current need for compact compression systems that can handle wet process gas. The ICS makes use of centrifugal compressor stages driven directly by a high-speed, close-coupled electric motor, and incorporates a proprietary integrated centrifugal gas-liquid separation unit within the compressor case. This compact compression unit is packaged with process gas coolers in a single-lift module, providing a complete compression system that can be applied to all markets — upstream, midstream and downstream. With this integrated approach, the total footprint and weight of a conventional module or equipment layout can be greatly reduced. This paper is part of a series of publications that will describe the attributes of the new integrated compression system, and will serve to introduce the ICS and the benefits associated to the integration of the centrifugal separator into the compressor casing. The paper will focus on the OEM’s approach to Wet Gas Compression, with emphasis on the benefits of handling the liquid and vapor phases as separate streams, making the system more efficient and reliable than alternate solutions, including the ones that handle the wet gas directly. Finally the paper will provide a comparison between a traditional compression train and the new ICS to show how the latter system offers significant size and weight advantages.