Stainless Steel Absorber for Marine Exhaust Gas Cleaning

Product Introduction

In response to IMO 2020 “sulphur cap” regulations, the maritime industry urgently needs reliable, durable, and cost‑effective exhaust gas cleaning systems. Our Stainless Steel Absorber – the core component of a marine scrubber system – offers a proven solution to remove sulphur oxides (SOₓ) from ships’ engine and boiler exhaust. Designed with premium stainless steel materials, this absorber combines high corrosion resistance, structural integrity, and long‑term operational economy, making it the preferred choice for vessel owners seeking compliance without switching to low‑sulphur fuel.

Working Principle

The absorber operates on the principle of counter‑current gas‑liquid contact. Hot exhaust gas enters the lower section of the tower, while an alkaline scrubbing medium (seawater or fresh water with NaOH/Mg(OH)₂) is sprayed downward through multiple nozzle layers. As the gas rises and the liquid falls, intimate contact allows SO₂ and other sulphur oxides to dissolve and neutralise, forming harmless sulphates or sulphites. Cleaned gas passes through a high‑efficiency mist eliminator at the top before being released to the atmosphere. The spent scrubbing water is either discharged (open‑loop), treated and recirculated (closed‑loop), or handled in a hybrid mode.

Why Stainless Steel?

The choice of stainless steel – primarily Duplex 2205 and, for more demanding conditions, super austenitic grades like 254 SMO or titanium – is critical for absorber performance in the marine environment.

- Superior corrosion resistance: The scrubbing process creates acidic conditions (pH as low as 3–4). Stainless steel resists pitting, crevice corrosion, and stress corrosion cracking caused by chlorides and acidic sulphates, far outperforming carbon steel with coatings.  
- High mechanical strength: Duplex stainless steel offers nearly twice the yield strength of austenitic grades, allowing thinner walls and reduced weight – a vital advantage for shipboard installation where space and weight are limited.  
- Long service life: Our absorbers are designed for a minimum of 20 years of continuous operation. Stainless steel does not degrade or require frequent recoating, drastically lowering maintenance costs and downtime.  
- Heat resistance: Exhaust gases can reach high temperatures; stainless steel maintains its mechanical properties and corrosion resistance under thermal cycling, eliminating the risk of coating blistering or cracking.

Product Features

1. High Desulphurisation Efficiency
Efficiency >98%, ensuring outlet SOₓ concentration meets IMO limits (≤0.5% m/m globally, ≤0.1% m/m in ECAs).

2. Flexible Tower Configurations
We supply U‑type (low height, ideal for VLCCs and bulk carriers), I‑type (compact, for container ships), and L‑type (angled design for retrofit projects). Each is fabricated from stainless steel with precision welding and passivation to guarantee leak‑tight, corrosion‑free joints.

3. Low Pressure Drop
Optimised internal design (spray layers, packing-free or low‑packing options) keeps pressure drop below 650 Pa, reducing backpressure on the main engine and saving fuel.

4. Integrated Automation
A PLC‑based control system with HMI monitors pH, flow, pressure, and exhaust gas composition. Automated alarms and remote diagnostics minimise crew workload.

5. Versatile System Modes
- Open‑loop: Uses seawater’s natural alkalinity; simplest and most economical for ocean‑going vessels.  
- Closed‑loop: Recirculates fresh water with caustic addition; zero discharge – suitable for inland waters and ports.  
- Hybrid: Switches between modes for global route flexibility.

Technical Specifications

| Parameter | Value |
|-----------|-------|
| Desulphurisation efficiency | ≥98% |
| System back pressure | ≤650 Pa |
| Engine power range | 1 MW – 70 MW (customisable) |
| Tower material | Duplex 2205 / 254 SMO / titanium |
| Tower types | U / I / L |
| Mist elimination efficiency | ≥99% |
| Design life | 20+ years |

Application Cases

Our stainless steel absorbers are already in service on:

- VLCCs and aframax tankers (U‑type, open‑loop) – over 3 years without any corrosion issues.  
- 14,000 TEU container vessels (I‑type, hybrid) – passing all ECA inspections with emission margins well below limits.  
- Bulk carriers and chemical tankers (L‑type retrofits) – installed during scheduled dry docks with minimal hull modifications.

Conclusion

A stainless steel absorber is not just a component; it is a long‑term investment in regulatory compliance, operational reliability, and reduced lifecycle cost. By choosing our marine exhaust gas cleaning system, you gain:

- Full IMO compliance without switching to expensive low‑sulphur fuel.  
- Unmatched corrosion resistance and structural durability.  
- Low maintenance – no coating repairs or frequent replacements.  
- Customised design for any vessel type and operating profile.  

Contact us today for a detailed proposal and engineering support. Let our stainless steel absorbers power your green shipping journey.