28 Tons of Acid-Washed Coal GAC Shipped to the Middle East for Amine Gas Sweetening

In an amine gas-sweetening plant, the amine solution is the asset you protect at all costs. It circulates for years, pulling H₂S and CO₂ out of sour gas — and it slowly gets dirtier every cycle. Hydrocarbons condense into it, surfactants build up, and the amine itself degrades into heat-stable salts and organic acids. Left alone, that contamination shows up as one expensive symptom: foaming. Foaming carries amine overhead, trips the unit, spikes antifoam spend, and accelerates corrosion.

The fix is a carbon filter on a slipstream of the lean amine. But the carbon has to be the right kind — because the wrong grade adds contamination instead of removing it. Here's the full breakdown of this shipment: the grade we supplied, why acid-washed matters, how the filter is designed, and how the 28 tons moved.

Order Summary

What Contaminates an Amine Solution

An amine unit runs the same solution in a closed loop for a long time, so contamination accumulates from several sources at once:

• Dissolved and entrained hydrocarbons — heavier hydrocarbons in the sour gas partition into the amine and don't leave cleanly. They're the single biggest foaming driver.
• Surfactants and well-treating chemicals — corrosion inhibitors, glycols, and completion-fluid carryover from upstream all act as surfactants that stabilize foam.
• Amine degradation products — heat-stable salts and organic acids form as the amine cycles through hot regeneration. They raise viscosity and corrosivity.
• Iron and particulates — corrosion products and fines circulate and plug filters if not controlled.

Activated carbon targets the organic side of that list — the hydrocarbons, surfactants, and organic degradation products. Its pore structure adsorbs the large organic molecules that drive foaming, which is exactly why a carbon bed on the lean amine is one of the most cost-effective interventions in a gas plant.

Key takeaway: foaming is a symptom of organic contamination. A slipstream carbon filter removes the cause, so you dose less antifoam and run the unit more stably.

Why Acid-Washed, Low-Ash Carbon Is Non-Negotiable

This is the spec that separates amine-grade carbon from a generic industrial grade. A standard coal-based carbon can carry an ash content of 8–15%, and a good fraction of that ash is soluble iron and other minerals. Put that carbon into an amine solution and it leaches metals into the very fluid you're trying to protect.

Iron in an amine solution is a double problem: it accelerates corrosion of the carbon steel in the unit, and it catalyzes further amine degradation — making more of the heat-stable salts you were trying to remove. So the carbon has to be acid-washed, which dissolves out the soluble minerals during manufacture and brings ash down to ≤3%. For amine service, low ash isn't a nice-to-have; it's the whole point.

Carbon Grade by Amine System

The base choice — acid-washed coal-based GAC — holds across amine chemistries, with the iodine number and mesh tuned to the system. This is the same selection logic we apply on the amine purification application:

This customer runs a formulated MDEA solution, so they took the ≥950 mg/g 4×8 grade — high iodine for organic-removal capacity, and a coarse mesh that keeps pressure drop low across a slipstream vessel.

Designing the Amine Carbon Filter

The carbon grade is half the job; the filter design is the other half. Four points decide whether the bed performs:

1. Slipstream 10–20%. Route a slipstream of lean amine through the carbon bed rather than full flow. This holds contaminants at a low steady-state level without an oversized vessel or excessive pressure drop.
2. Pre- and post-filtration. A particulate filter upstream protects the carbon bed from plugging; a fine post-filter downstream catches any carbon fines before they return to circulation.
3. Adequate contact time. Size the bed for a superficial velocity that gives enough contact — too fast and organics slip through, too slow and the vessel is oversized. Typical bed life is 3–12 months.
4. Change-out on trend, not calendar. Track foaming tendency, amine color, and hydrocarbon content. A rising foaming tendency is the practical signal the bed is spent — far more reliable than a fixed calendar interval.

What the Plant Was Dealing With

The unit had been fighting recurring foaming and climbing antifoam consumption on its formulated MDEA solution. Antifoam is a band-aid — it suppresses the symptom but does nothing about the organic load causing it, and over-dosing antifoam can itself add to the surfactant problem. The plant wanted to attack the cause.

They switched the lean-amine slipstream to our acid-washed coal GAC 4×8 at a 15% slipstream ratio. Measured foaming tendency dropped substantially within one circulation cycle, antifoam dosing came down, and H₂S/CO₂ removal steadied out. The bed was then put on a foaming-tendency change-out schedule rather than a fixed date, so carbon spend tracks actual solution condition.

Packaging & Shipping

The 28 tons went out in a mix of 25 kg bags on pallets and jumbo FIBC bags — the smaller sacks make it easy to charge a slipstream vessel in measured amounts, while the jumbo bags cover bulk top-ups. Every batch shipped with its own Certificate of Analysis covering iodine number, ash, hardness, and particle size, so the plant could verify the grade against spec before charging the bed.

Bags were loaded at our facility and trucked to Tianjin Port for the sea route to the Middle East. We handled the full export document set and arranged pre-shipment inspection, so the plant had third-party confirmation of the specs before the container left port. This is a route we run often — see our related case on 56 tons of coal GAC shipped to Saudi Arabia for municipal water.

Why We Test a Sample First

Amine service is contamination-specific: the hydrocarbon carryover, degradation-product load, and surfactant mix are different on every unit. We recommend validating a sample against the plant's actual lean amine before committing to bulk. This customer ran a sample evaluation first, confirmed the 4×8 grade brought foaming tendency down on their solution, then placed the 28-ton order.

We Supply Amine & Gas-Treating Carbon Worldwide

This is one of many gas-processing shipments we've handled. We supply acid-washed coal-based and coconut shell carbon to gas plants, refineries, and chemical processors for amine purification, solvent recovery, and H₂S control. For the wider picture, see our overview of activated carbon for the chemical industry, and as a Middle East buyer's reference, our guide to sourcing an activated carbon supplier for the Middle East.

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