PR771-242005-R01 Selective Catalytic Reduction Best Practices

This document serves as a guide to best practices and lessons learned when installing Selective Catalytic Reduction (SCR) systems to gas compressors. The information is relevant to both reciprocating and turbine compressors both as new construction and retrofit.

Gas compressors have a unique NOx and VOC emissions profile due to constant load changes and variation in prime movers. The compressor emission profile, compared to other applications such as power generation, requires a different approach from the start. Operating permits must reflect the limitations of SCR technology applied to gas compressors.

The type of compressor, load profile, and the permit limits for NOx and VOCs make the design of the SCR specific to each unit. This report highlights the challenges of applying SCR technology to gas compressors. Lessons learned and advice for each compressor type (Four-stroke, Two-Stroke, and turbine) are provided discussing the specific challenges and ways to overcome them. The technology of the catalyst, process design, reagent selection, regent handling, and injection are detailed.

Operation and maintenance of SCRs for gas compressors including expectations for startup/commissioning and ongoing maintenance is discussed. The information is provided to help designers and operators of this technology make good choices of the many options available while selecting proper equipment that is operable and practical to the needs of compressor stations.