Zone 3 - Gas Cleaning & Upgrading Equipments - Capacity, specification & price ranges
Seven Zone 3 gas cleaning and upgrading equipment items for a 10 TPD CBG plant — from H2S scrubber through membrane upgrading unit and online analyzer — with technical specifications and indicative Indian supplier price ranges.
| Equipment | Capacity / Throughput | Key Specifications | Price Range (Approx. INR) |
| H2S Scrubber (Iron Sponge) | 50 - 100 m^3/hr | Twin-tower design for 24/7 operation; SS 304 | ₹5,00,000 – ₹9,00,000 |
| Gas Chiller / Dehumidifier | 100 m^3/hr | Cools to 4C; Moisture separator included | ₹4,00,000 – ₹7,00,000 |
| Activated Carbon Filter | Dual Bed system | Removes VOCs and Siloxanes; SS 304 vessel | ₹2,50,000 – ₹4,50,000 |
| Membrane Upgrading Unit | 60 - 100 m^3/hr (Raw) | 3-stage hollow fiber; >98% CH4 recovery | ₹60,00,000 – ₹95,00,000 |
| PSA System (Alternative) | 60 - 100 m3/hr (Raw) | Carbon Molecular Sieve (CMS); 4-tower setup | ₹45,00,000 – ₹70,00,000 |
| Online Gas Analyzer | 4-Gas sensor | Measures CH4, CO2, H2S, and O2 | ₹4,00,000 – ₹8,00,000 |
| Vapor Liquid Separator | Sized to flow | SS 316 demister pad; Manual/Auto drain | ₹1,50,000 – ₹3,00,000 |
Beyond definitions
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How to read this table
- Equipment is listed in process sequence — H₂S Scrubber first, Vapor Liquid Separator last before the compressor.
- Membrane Upgrading Unit and PSA System are alternatives — select one based on the technology comparison in the Upgrading Technologies table.
- Price ranges are indicative ex-works procurement costs from Indian suppliers, excluding GST, installation, and civil works.
- m^3/hr = cubic metres per hour of raw biogas handled; SS 304 and SS 316 are stainless steel grades; VoCs = Volatile Organic Compounds.
- The Online Gas Analyzer price range reflects instrumentation-grade equipment with ATEX certification for explosive atmospheres — cheaper industrial analyzers are not suitable.
About this table
Zone 3 of a Compressed Biogas (CBG) plant is where raw biogas is cleaned and upgraded to fuel-grade purity. The process runs in two stages: first, contaminant removal (H₂S, moisture, volatile organic compounds), and then upgrading (removing CO₂ to raise methane content from 55–65% to 90%+). This table shows the seven equipment items that make up a complete Zone 3 system for a 10 TPD plant, with specifications and indicative procurement costs.
The cleaning sequence begins with the H₂S Scrubber (iron sponge type, 50–100 m³/hr, twin-tower SS 304). Hydrogen sulfide (H₂S) must be removed first because it corrodes downstream compressor and membrane components — even 200–300 ppm H₂S causes accelerated wear on metal surfaces and poisons the adsorption media in a PSA system. The twin-tower design allows one tower to be regenerated while the other remains online, enabling 24/7 continuous operation. After H₂S removal, the Gas Chiller or Dehumidifier cools the gas stream to 4°C, condensing and removing moisture before it enters the upgrading unit. Saturated water vapour in raw biogas causes hydrate formation and corrosion inside membrane modules and compressor seals.
The Activated Carbon Filter (dual-bed, SS 304) handles the trace contaminants that H₂S scrubbing and chilling do not remove: volatile organic compounds (VOCs) and siloxanes. Siloxanes, found especially in MSW-sourced biogas, convert to silicon dioxide on combustion and abrade engine and equipment surfaces — their removal is critical for CBG intended for vehicle fuel use. The main upgrading step is then performed by either a Membrane Upgrading Unit (3-stage hollow fiber, above 98% CH₄ recovery) or a PSA System (4-tower Carbon Molecular Sieve) — the two dominant technologies as discussed in the Upgrading Technologies comparison table.
Two monitoring and protection instruments complete the zone: the Online Gas Analyzer (4-gas sensor for CH₄, CO₂, H₂S, and O₂) provides continuous feed-forward data to the upgrading unit controls and alarms for product quality exceedances before the gas enters storage. The Vapor Liquid Separator (SS 316 demister pad) protects the compressor and membrane from liquid carryover — any liquid droplets reaching the membrane at high pressure will permanently damage the hollow fiber bundles.
Key insights
- H₂S must be removed before all other upgrading steps — it poisons PSA adsorption media and accelerates corrosion in membrane housings, making the H₂S Scrubber the first and non-negotiable step in Zone 3.
- Siloxanes in MSW biogas convert to abrasive silicon dioxide on combustion — the Activated Carbon Filter's siloxane removal function is critical for vehicle-fuel CBG quality even when siloxane levels appear low.
- The Online Gas Analyzer is the quality control gate — it verifies that upgraded CBG meets the 90%+ CH₄ specification before gas enters high-pressure storage, protecting against substandard product reaching the OMC.
- Membrane Upgrading Units (above 98% CH₄ recovery) significantly reduce methane slip compared to PSA (94–96%) — over a 10-year plant life, this 2–4% difference represents meaningful additional revenue and lower greenhouse gas emissions.
Methodology & sources
Equipment specifications are typical for Indian-manufactured and imported equipment at 10 TPD CBG plant scale as of 2024. The membrane upgrading unit and PSA system prices reflect imported systems or Indian-assembled units with imported core components. H₂S Scrubber iron sponge media requires periodic replacement (typically every 6–18 months depending on H₂S loading); media replacement cost is not included in the equipment price range. All prices exclude GST and installation.
Related data tables
Difference between biogas and compressed biogas
Side-by-side comparison of raw biogas and Compressed Biogas (CBG) covering methane purity, calorific value, impurities, and how each gas is transported — the two states of the same gas after the upgrading step.
Zone 2 - Capacity, specification & price ranges
Seven Zone 2 digestion equipment items for a 10 TPD CBG plant — digester tanks, agitators, biogas storage dome, heating coils, blower, and safety fittings — with capacity specifications and indicative Indian supplier price ranges.
Zone 3 - Gas Cleaning & Upgrading - Upgrading Technologies
Side-by-side comparison of three biogas upgrading technologies — Membrane Separation, PSA, and Water Scrubbing — covering how each works, methane recovery %, power demand, maintenance burden, and startup speed.