Enclosed Flares for Sewage Digester Gas
Enclosed biogas flares that burn surplus sewage digester gas safely when the engines, boilers or upgrader are unavailable.
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Safe disposal of surplus digester gas
A sewage treatment plant has to burn its digester gas whenever the engines, boilers or upgrading plant cannot use it. CRA's enclosed biogas flares are sized for the full gas production with the main consumer offline, and CRA supplies them with the booster blower, flame arrestor and controls that make up the flare train.
Destruction efficiency
>98%
Sizing
Full digester gas production
Supply
Flare and complete flare train
Operation
Fully automatic
What does a digester gas flare do?
A digester gas flare burns the biogas a sewage plant cannot use at that moment, so the gas holder does not have to relieve it to the atmosphere. An enclosed flare burns the gas inside a chamber, which keeps the flame, glare and radiant heat inside the plant.
How it works
The flare takes the surplus gas from the gas holder and starts and stops with the plant's needs.
When the engines, boilers or upgrader cannot take all the gas, the surplus is sent to the flare.
The booster blower raises the low-pressure digester gas to the pressure the burner needs.
The flare lights and proves its flame before it takes the gas.
The gas burns inside the enclosure, out of sight.
When the surplus has gone, the flare shuts down until it is needed again.
Key Benefits
The flare is sized for full digester gas production with the main consumer offline.
The flame burns inside the chamber, which keeps glare and radiant heat inside the plant.
CRA supplies the booster blower, flame arrestor, valves and controls with the flare.
The flare starts automatically when surplus gas builds up and shuts down when it is no longer needed.
The design accounts for moisture and siloxanes in sewage gas.
Projects That Push Boundaries
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Designed with continuous flame supervision and fail-safe shutdown for a public utility.
Two enclosed ground flares with spares for the 500 MLD wastewater treatment facility serving MCGM in Worli, Mumbai.
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.
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Frequently Asked Questions
How should a sewage plant flare be sized?
The flare should be sized for the full digester gas production with the engines, boilers or upgrader offline, so that surplus gas never goes to the relief valves.
Does CRA supply the booster blower?
Yes. Digester gas is usually at a low pressure, so CRA supplies the booster blower with the flare train.
Why choose an enclosed flare for a sewage plant?
An enclosed flare hides the flame and keeps radiant heat inside the chamber, which suits plants in urban areas.
Can the flare start automatically?
Yes. The flare starts when surplus gas builds up, proves its flame and shuts down automatically.
What data does CRA need to size the flare?
CRA needs the maximum and minimum gas flow, the methane content, the supply pressure and the site conditions.