Athena Instruments Pvt. Ltd.

Biogas Purification Plant                       
The typical composition of biogas is:Methane (CH₄): ~60%Carbon dioxide (CO₂): ~40%Trace gases: Hydrogen sulfide (H₂S), moisture, etc.
Biogas can either be:Used directly as a fuel, orPurified and upgraded into Compressed Bio-Gas (CBG)CBG contains more than 90% methane, making it comparable to natural gas in terms ofenergy content and usability.

PURIFICATION OF RAW BIOGASwww.athenatechnology.inBIOGAS PURIFICATIONBiogas production is generally a continuous process. However, its efficiency as a fuel depends largely on methane concentration. Therefore, purification is essential to:Increase methane content Reduce carbon dioxide concentrationRemove corrosive gases like hydrogen sulfide (H₂S)Purification enhances the calorific value of biogas and improves its suitability for compression and storage.The purified gas is compressed into CBG, which must comply with IS 16087:2016 (BIS standards).

Several technologies are used for biogas upgrading:1.Pressure Swing Adsorption (PSA) / Vacuum PSA (VPSA)2.Water Scrubbing3.Membrane SeparationChemical Scrubbing (e.g., Monoethanolamine - MEA system

PSA/VPSA is a gas separation process that uses specially designed adsorbents known as molecularsieves.Working Principle:Molecular sieves have microporous surfaces.Under high pressure, they selectively adsorb:CO₂H₂SN₂Moisture (H₂O)Methane (CH₄) passes through as the product gas.After adsorption, the adsorbent is regenerated by reducing pressure (depressurization).This cycle of adsorption and regeneration is repeated continuously to produce methane-rich gas.

FEATURES OF VPSA BIOGAS PURIFICATION SYSTEMHigh efficiency with low maintenanceLow energy consumptionLow noise operationEnvironment-friendly processStable and high-performance operationCentralized and simple control systemUser-friendly interface


ADVANTAGES OF VPSA BIOGAS PURIFICATION SYSTEMHigh-quality purified gas outputMinimal methane lossLow energy requirementReliable and high-quality componentsEasy operation through efficient control panelsSuitable for 24/7 continuous operationOperator-friendly designConsistent gas purityLong operational life with minimal issuesCompact system requiring less floor space

1. GAS SUCTION AND PRESSURIZATIONRaw biogas is first stored in a gas holder.A blower sucks the biogas and increases its pressure.This pressurized gas is then forwarded for purification.2. WATER SCRUBBING (PRIMARY CLEANING)Biogas enters from the bottom of the scrubber column.Water is introduced from the top (counter-current flow).Water acts as an absorbent to remove:Hydrogen sulfide (H₂S)Ammonia (NH₃)👉 Output:Impurities dissolve in waterGas leaving the top contains:CH₄ + CO₂ + traces + moisture3.CHEMICAL SCRUBBER (SECONDARY H₂S REMOVAL)Gas passes through a chemical scrubberUses iron flakes / iron oxide mediaRemoves remaining H₂S traces👉 Ensures protection of downstream equipment4. DEHUMIDIFICATION (MOISTURE REMOVAL)Gas passes through a chemical scrubberUses iron flakes / iron oxide mediaRemoves remaining H₂S traces👉 Ensures protection of downstream equipmentGas is cooled to 8–10°C using a chillerMoisture condenses and is removed via:Cyclonic moisture separatorAutomatic drain valve👉 Produces dry gas for efficient adsorptionBIOGAS PURIFICATION