Recent Research Projects

  • Dry Gas Seal Reliability: A Study of the Effects of Liquid Contamination on Seal Performance

    Project Champion: Michael Matheidas, ExxonMobil Production Company

    Dry gas seals are the primary type of shaft seals in many turbomachinery applications, including centrifugal gas compressors. These seals have very low leakage rates due to their small operating clearance (3-10 microns) between rotating and nonrotating parts. However, this low clearance also causes the seal to be sensitive to contamination from the process gas, bearing lubrication oil, or seal supply gas. A previous GMRC study on dry gas seal reliability indicated that liquid contamination was the most common source of seal failure in the cases studied. Dry gas seal failures from liquid contamination are expensive to repair and can result in costly down time. Field experience shows that some seals continue to function even when liquid contamination exists, but industry knowledge regarding acceptable levels/types of liquid contamination is insufficient. This project will identify the underlying mechanisms behind failure modes due to liquid contamination and use this information to develop a test to investigate allowable levels of liquid contamination.

    The results of this study will be detailed in a comprehensive report that includes a summary of the mechanism behind dry gas seal liquid contamination failures, industry experience with liquid contamination failures, results of testing a dry gas seal with liquid injection, and recommendations for maximizing system reliability.

    The report will be targeted to end users of centrifugal compressors and other turbomachinery utilizing dry gas seals.

  • Direct Enthalpy Rise Measurement

    Project Champion: Rainer Kurz, Solar Turbines

    One of the conclusions of the direct thermophysical property measurements in the previous GMRC Equation of State Comparison project was that the most beneficial property for end users and OEMs would be a direct measurement of enthalpy of a gas mixture. Accurately calculating the enthalpy and specific heat at a constant pressure (Cp) of the process gas or gas mixture is essential in most aspects of the design and operation of facilities. The problem with the current method is the significant error introduced by indirectly calculating Cp. Thermodynamic properties are calculated using pure gas component models matched to within I% of actual pure gas experimental data. Properties of gas mixtures, more common for industrial applications, are computed using mixing laws applied in various equations of state (EOS) models. This introduces significant error when calculating enthalpy.

    The specific deliverable of this project will be a report describing the design and characteristics of an apparatus that can measure Cp directly. Additionally, the results of direct Cp measurement of two gas mixtures at three operating points will be provided for comparison with EOS predictions.

  • Guidelines for the Selection of Filtration Equipment - Phase 1

    Project Champion: Christine Scrivner, Kinder Morgan

    Liquid contaminants in a compressor inlet gas stream can severely damage the compressor. Similarly, oil and other liquids that enter a compressor outlet stream can damage other process equipment and can also result in pipe corrosion. Although various separation technologies are currently available that will remove liquids with some degree of efficiency, it is not clear which technologies best address different circumstances or at what point in the process filtration should be installed. Perhaps, in some instances, more than one type of filtration is required.

    The deliverables from this project include three teleconferences and a detailed final report. The teleconferences will be used to describe and discuss the project status with the Project Champion. The final report will document the work accomplished in the five major work tasks. The focus of the report will be a description of the current state of the art in performance of gas filtration equipment, the current guidelines and best practices in selecting filtration equipment. and recommendations for future work to close gaps in the technology.

  • Wet Gas Formation and Carryover in Suction Equipment – Phase 2

    Project Champion: Gary Bourn, Anadarko

    In gas processing, boosting and gathering applications, drying and/or separating equipment is placed upstream of the compression equipment to remove water and hydrocarbon condensates. However, liquids can still be carried over from the separation equipment due to changes in operating conditions. Furthermore. even when the gas leaving the separator is dry (i.e., saturated vapor), pressure and heat losses in suction bottles and nozzles may be sufficient to lead to liquid condensation. While it is generally understood that liquid carryover and liquid condensation can occur, it is less clear how the multiphase fluid moves through equipment downstream of the separator. In the past year, the first phase of a project led by Southwest Research Institute® (SwRI) was completed to investigate wet gas formation and carryover in compressor suction equipment. In this first phase, one-dimensional (1-D) thermal-fluid models were developed for three (3) unique compressor suction bottles. The models provide valuable insight and represent an effective means to quickly determine whether a particular compressor skid design is susceptible to liquid dropout and accumulation. Still, because the models use a 1-D approach, complex flow features that can occur in the suction bottles are not fully captured. To improve the 1-D modelling approach, the complex flow patterns and their influence on liquid carryover need to be investigated.

    The deliverable from this work will be a detailed report that describes the complete results of the proposed analysis. The methods used for analysis will also be included in the report. Modifications to the 1-D modeling procedure will be documented and results of the CFO and 1-D models will be compared.

  • Development of a Robust Scrubber Level Control

    Project Champion: Scott Schubring, Williams Companies

    Gas-liquid scrubbers rely on level control systems to maintain an appropriate liquid level within the vessel. A typical level control system comprises a level indicator, a modulating level controller, level switches, and a pneumatic control valve for liquid release. In natural gas service, these control systems are subject to harsh environments often characterized by the influx of liquid slugs, high velocity gases, corrosive fluids, vibrations, and a chaotic gas-liquid interface. In these harsh conditions, level control system failures are commonplace and tend to lead to safety and environmental hazards, equipment damage, and lost production. A need exists to augment or replace the typical liquid level system with an alternative solution that is cost effective, robust, and can operate reliably in the harsh natural gas environment.

    The deliverables from this work will include a detailed final report and a detailed set of specifications and/or drawings describing the final prototype design. The final report will document work completed during the five technical tasks. The specifications and/or drawings for the prototype liquid level control system will document the final design details and will be used to build the concept prototype in Phase II.

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