Dry Iron Scrubber

H2S Removal at a Fraction of Cost

Skid-mounted dry iron oxide scrubber vessel for H2S removal from biogas and landfill gas streams.
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Overview

H2S Removal Engineered Around Impregnated Iron Oxide Media

CRA's Dry Iron Scrubbers use impregnated iron oxide media to strip H2S from biogas, landfill gas, and associated gas streams at a lower cost per pound removed than activated carbon. Each skid is fabricated in-house to ASME Section VIII Div. 1, with bed sizing calculated against actual site gas composition rather than generic sizing charts. The system targets H2S specifically; it does not remove VOCs, siloxanes, or other organic compounds, and is best suited to applications where H2S is the primary contaminant of concern. A moisture conditioning point ahead of the bed keeps the media within its active reaction range across fluctuating inlet loads.

H2S Removal

Up to 99.9%

Media Type

Impregnated Iron Oxide

Configuration

Custom multi-vessel

Vessel Code

ASME Section VIII

Technology explained

What is a Dry Iron Scrubber?

A Dry Iron Scrubber is a fixed-bed vessel that strips H2S from a gas stream by passing it through media impregnated with iron oxide. H2S reacts with the iron oxide to form iron sulfide, which stays trapped in the bed while treated gas exits below the required outlet specification. The process does not filter VOCs, siloxanes, or other organic compounds.

How it works

Raw gas enters the vessel through a distributor plate and passes down through the impregnated iron oxide bed, where H2S reacts with the media to form iron sulfide, while a moisture conditioning point ahead of the bed keeps the reaction active across fluctuating inlet loads before treated gas exits to the downstream flare, engine, or upgrading skid.

1
Gas Inlet Distribution

Raw gas enters the vessel through a distributor plate that spreads flow evenly across the bed cross-section, preventing channeling.

2
Iron Oxide Bed Contact

Gas passes down through the impregnated iron oxide media, where H2S reacts with the iron oxide to form iron sulfide.

3
Moisture Conditioning

A moisture injection point ahead of the bed keeps the media within its active reaction range, since the iron oxide reaction requires bound water to proceed.

4
Treated Gas Outlet

Conditioned gas exits below the outlet specification for H2S and routes to the downstream flare, engine, or upgrading skid.

5
Media Change-Out

Once the bed is exhausted, spent media is removed through top or side access ports and replaced with fresh charge.

Key Benefits

Here’s how they keep your operations safe, efficient, and

1
Lower Cost Per Pound of H2S Removed

Impregnated iron oxide media strips H2S at a lower media cost than activated carbon, without paying for adsorption capacity the application does not need.

2
Simple Fixed-Bed Design

No moving parts, no rotating equipment, and no chemical dosing system to maintain across the life of the skid.

3
Tolerates Fluctuating H2S Loads

The fixed bed absorbs day-to-day and seasonal swings in inlet H2S concentration without process upset, though bed life shortens as loading increases.

4
Fast Media Change-Out

Spent media is removed and replaced through top or side access ports, typically achievable within a single working shift.

5
No Liquid Waste Stream

Dry media handling avoids the solvent or liquid waste disposal requirements that come with wet scrubbing alternatives.

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The CRA Edge

With decades of flare system expertise, CRA goes beyond equipment — we deliver full solutions.

In-House Skid Fabrication

Vessel design, media loading, and controls integration handled under one roof, from ASME-code fabrication to site commissioning.

Site-Matched Media Sizing

Bed volume and change-out interval are calculated against each site's actual H2S loading and gas flow rather than a standard catalogue size.

ASME Pressure Vessel Design

Every vessel is built to ASME Section VIII Div. 1, independent of the media technology inside it.

Gas Conditioning Experience

Delivered gas conditioning and treatment skids across biogas, landfill gas, and associated gas applications alongside CRA's flare and compression systems.

Applications

See how we turn hard problems into high-performance infrastructure.

Landfill gas H2S polishing ahead of flaring
Associated gas H2S removal ahead of compression
Digester gas conditioning at wastewater treatment plants
Seasonal H2S load variation management
Biogas conditioning ahead of CHP engines
Pretreatment ahead of RNG/biomethane upgrading membranes
Low-to-moderate H2S streams where activated carbon cost isn't justified
Standalone polishing step downstream of bulk H2S removal

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