Retrofits for Off-Spec CBG Plants
Retrofits that bring off-spec CBG plants back to specification and cut methane slip.
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Off-spec CBG plants brought back to specification
CRA audits CBG gas trains, finds where gas quality and methane are lost, and retrofits the scrubbing, drying and polishing stages that bring the plant back to specification.
Scope
Audit, design and retrofit
Common fixes
H₂S, moisture and pressure
Product gas target
IS 16087:2025
Work
At operating plants
How does a CBG plant retrofit work?
The retrofit starts with the data: raw gas analyses, product gas quality and operating records. CRA checks each stage of the gas train against what the next stage needs. The usual findings are H₂S breaking through, wet gas reaching the membranes, unstable compressor suction or air entering with a biological scrubber. CRA then designs and supplies the stages that fix them.
How it works
Retrofit skids tie into the existing gas train at the points the audit identifies.
Gas analyses and operating records show where quality is lost.
Each stage is checked against what the next stage needs.
CRA designs the scrubbing, drying or polishing the plant needs.
Skids tie into the existing gas train with short downtime.
Product gas analyses confirm the improvement.
Key Benefits
CRA audits the gas train stage by stage to find where quality is lost.
Retrofits target the CBG quality that IS 16087:2025 requires.
Stable inlet gas helps the membranes recover more methane.
Clean, dry, steady gas protects the membranes.
Retrofit skids are designed for installation at running plants.
Projects That Push Boundaries
Chemical scrubber with biological regeneration and activated-media polishing designed to reduce H2S from 10,000 ppm to below 200 ppm.
Removes H₂S from Biogas stream using a wet scrubber, engineered for CBG Application.
The CRA Edge
CRA has more than 30 years of experience in gas handling and flare engineering.
Design, R&D and manufacturing are carried out under one roof.
ISO 9001 certified through TÜV NORD, with designs aligned with ASME, API and CE.
Designs are customised to the process needs and the regulations that apply at site.
Applications
Built to help you specify.
Sizing tools, decision guides, and technical references. Use them before, during, and after your evaluation.
Frequently Asked Questions
Why do CBG plants go off-spec?
Most quality problems start upstream of the membranes: H₂S breakthrough, moisture, unstable pressure or air added by the scrubber.
What does a CRA retrofit cover?
It starts with an audit of the gas train, followed by upgrades to the stages that need them, such as bulk desulphurisation, drying and polishing.
Why can a biological scrubber cause off-spec CBG?
Biological scrubbers dose air into the gas, which puts oxygen and nitrogen into the CBG. CRA uses the chemical scrubber with biological regeneration for CBG duty.
What data does CRA need to start?
CRA needs the raw gas data, the product gas analyses, the plant's operating records and the specification it has to meet.
Can the plant keep running during the retrofit?
CRA plans retrofit skids for installation at operating plants and works with the plant to keep downtime short.