Introduction to Dry Gas Seals and Systems

TutorialDry gas seals are used as low-leakage shaft end seals for many centrifugal compressors and other turbomachines. This short course provides a comprehensive overview of sealing system and dry gas seals in various turbomachinery applications, addressing multiple topics ranging from fundamentals to detailed design considerations for reliable operation. A course attendee can expect a greater understanding of technologies, failure modes, and requirements for components in dry gas seals and seal supply/vent systems, with perspectives from an end user, a seal manufacturer, and a research organization.This short course will give listeners a thorough understanding of dry gas seals, including design, operation, and maintenance. Starting with the background of how dry gas seals were developed as a response to issues with wet seals, the course will then move into a detailed discussion on seal design. The instructors will explain how each component of the seal contributes to its operation and issues that can arise if parts are selected incorrectly. Next, seal selection for various applications (pipeline, process, advanced applications) will be discussed. Methods for seal testing to ensure that design conditions are met will be described, including test rigs studying off-design conditions, such as transients or contaminant injection.The gas conditioning process can be critical to successful seal operation, so seal gas panels and their components will be discussed in great detail. Operation during transients can be particularly challenging, so panel considerations specific to transient operation will be discussed. The recently-released API 692 will be discussed as it pertains to dry gas seal panel design, seal requirements, and seal testing.Understanding common failure modes is an important step to improving dry gas seal reliability. Recent research on dry gas seal failures will be presented, including failure statistics and failure modes. Insight on failure modes specific to heat generation from liquid contamination will be discussed, and recommendations will be provided to reduce failures.Copyright© 2020 by Turbomachinery Laboratory, Texas A&M Engineering Experiment StationThis short course is aimed primarily at end users, but the multifaceted approach (end user, OEM, research) will provide a valuable perspective on dry gas seals to anyone in the rotating equipment industry. By the end of the course, attendees will have a detailed understanding of dry gas seals and their associated systems

sCO2 Compression

TutorialSupercritical Carbon Dioxide (sCO2) power cycles are a transformational technology for the energy industry, providing higher thermal efficiency compared to traditional heat-source energy conversion including conventional fossil and alternative energy sources. The novel cycle significantly reduces capital costs due to smaller equipment footprints and design modularity. In addition, it allows for rapid cyclic load and source following to balance solar and wind energy power swings. Compressing CO2 is not novel, but mostly at lower vapor pressures, and at higher pressure and lower temperatures as a liquid. Compression near the dome (near critical pressure and temperature) is a new interest that has many advantages and challenges. The key advantage is the low head requirement when compressing near the CO2 dome (95oF [35oC] and 1,233 psi [8.5 MPa]). To pressurize from 1,233 psi (target inlet pressure of power cycles) to 3,916 psi (27.0 MPa), only a single high-speed compressor stage is required. This low head requirement means less power is required to compress and leads to an increase in thermal efficiency of these cycles. High-efficiency compression technology can reduce the power of Enhanced Oil Recovery (EOR) and Carbon Capture and Sequestration (CCS) applications. This type of compression also brings many challenges. A compressor for this application pushes many current technology limits, including but not limited to: pressure rise per stage, bearing technologies, sealing technologies, damping, rotordynamics, compact machinery packaging, and high-density, high-speed compression. In addition, when compressing near the CO2 dome, there are large swings in density for slight changes in temperature. This is a unique challenge not observed when CO2 is pumped as a liquid or compressed as a vapor. Due to these large changes in density, range extension is required to maintain high compression efficiency and controlled mass flow over a range of operating temperatures. Recent testing finished on a state-of-the-art sCO2 compressor operating near the dome that was designed, manufactured, and tested by Southwest Research Institute (SwRI) and General Electric Global Research (GE-GRC). This tutorial will highlight many of the unique aspects of the design, especially those challenges and decisions that were focused on high pressure ratio compression stages, high-density and high-speed flow, special rotordynamic considerations, and the overall challenges of compact high-pressure turbomachinery. It will then cover how the design and analysis translated to testing with a real gas that experiences rapid changes in fluid properties for minimal fluctuations in temperature. In addition, due to its need for compact, high-power, and high-speed machinery, the development of sCO2 machinery aids in the development of many advanced components and hardware that can also be used in other applications. This includes high-pressure and high-temperature end seals, zero- to low-emission seals, hermetically sealed systems with gas or magnetic bearings, high-pressure single stage compressors, range extension technologies like variable Inlet Guide Vanes (IGVs), and high-density and high-critical speed ratio operation

INTRODUCTION TO DRY GAS SEALS AND SYSTEMS

TutorialThis tutorial presents an introduction to dry gas seals (DGSs) and their associated systems. DGSs are used as a shaft end seals for compressors and turbines, and they are installed on virtually all centrifugal compressors produced today. A DGS is able to provide very low leakage flow rates due to the small running clearance between the rotating and stationary components. This tutorial discusses the basic principles of DGS operation, terminology, applications, and API Standard 692 design requirements for DGS systems. The last section covers causes of DGS failures and practices to prevent them