marine scrubber

1. Product Overview

The marine exhaust gas scurber (also known as the marine desulfurization tower or scrubber) is the core device of the marine exhaust gas cleaning system (EGCS), specifically designed to treat sulfur oxides (SOₓ) in the exhaust gas generated by the combustion of high-sulfur fuel oil in marine main engines and auxiliary boilers, helping ships meet the emission standards set by the International Maritime Organization (IMO). This product adopts a wet desulfurization process, which efficiently absorbs and removes SOₓ from the exhaust gas through thorough contact and chemical reaction between gas and liquid phases. The purified exhaust gas meets the emission requirements specified in IMO MARPOL Annex VI, making it a reliable technical solution for shipowners to comply with the "sulfur cap regulation".

This product can flexibly adopt open, closed, or hybrid system solutions based on ship types, navigation areas, and customer needs, adapting to various types of merchant ships, container ships, tankers, and bulk carriers. It is committed to providing green, efficient, safe, and reliable marine exhaust gas treatment solutions for global shipping customers.

 II. Working Principle

This product is based on the fundamental principles of acid-base neutralization and gas-liquid mass transfer. The high-temperature exhaust gas emitted by the main engine and boiler of the ship is first cooled down and then enters the absorber from the lower part. Inside the absorber, the absorption liquid (seawater or alkali solution) is uniformly atomized and sprayed out through a spray system, allowing the exhaust gas and absorption liquid to fully countercurrently contact within the absorber.

During the gas-liquid contact process, sulfur oxides (SO₂, SO₃) in the exhaust gas dissolve in water or undergo neutralization reactions with alkaline substances in the absorbing liquid, generating sulfites or sulfates, which are thereby removed from the exhaust gas. The purified exhaust gas continues to rise, and after removing the entrained liquid droplets through a demister at the top of the tower, it is discharged into the atmosphere; the scrubbing liquid that has absorbed SOₓ is collected at the bottom of the tower and is either discharged externally or undergoes cyclic regeneration treatment depending on the system type.

The open system utilizes the natural alkalinity of seawater (pH 7.5-8.3) to directly absorb SOₓ from exhaust gas. The scrubbed wastewater is directly discharged into the ocean. It has a simple structure and low operating costs, making it suitable for large vessels engaged in long-distance ocean voyages.

The closed system employs fresh water mixed with desulfurizing agents (such as NaOH or Mg(OH)₂) for circulating washing. The washing liquid is cooled, replenished with chemicals, and then recycled. It is suitable for sensitive waters with additional emission restrictions, such as inland rivers and ports.

The hybrid system combines the advantages of both open and closed modes, allowing for flexible switching of operation modes according to navigation areas and regulatory requirements, balancing compliance and economy.

 III. Product Features

 1. Efficient desulfurization, meeting international compliance standards. The desulfurization efficiency can reach over 98%, ensuring that the sulfur oxide content in the emitted flue gas always meets the requirements of the IMO 2020 "Sulfur Cap Regulation" (fuel sulfur content ≤0.5% m/m, and ≤0.1% m/m within Emission Control Areas (ECA)).

 2. Multi-tower design, suitable for various ship types. This product offers multiple tower structures such as Type I, U-shaped, and L-shaped, which can be flexibly customized according to the deck space of ships: - U-shaped tower: with a relatively low height and high safety, it is commonly used for large ships with limited space, such as bulk carriers, ore carriers, and VLCCs.
- Type I tower: Compact structure, suitable for ship types such as container ships that have high requirements for top space.
- L-shaped tower: With a beveled design, it is suitable for retrofitting scenarios where the chimney layout is complex.
In addition, according to the needs of shipowners, single-tower or multi-tower combination designs can be implemented to meet the requirements of different smoke exhaust loads.

 3. Low-resistance design reduces energy consumption. By optimizing the layout of spray layers and packing structure within the tower, the system pressure drop is controlled at a low level, enabling efficient desulfurization without the need for additional booster fans. This helps ships reduce fuel consumption and operating costs.

 4. Compact and lightweight, saving deck space. The internal structure of the tower has been optimized, resulting in small equipment size and light weight. It is suitable for installation in the void space at the stern of the ship, minimizing the impact on the ship's cargo transportation capacity and original design.

 5. High corrosion resistance: For components of the tower body and those in contact with the washing liquid that are suitable for marine environments, high corrosion-resistant materials such as duplex stainless steel (e.g., 2205) and titanium alloy are selected. The seawater piping is coated with epoxy powder or made of fiberglass material, ensuring long-term stable operation under acidic corrosion conditions and reducing maintenance costs.

 6. Automated control and easy operation: Equipped with a comprehensive automatic control and alarm system (including a power distribution box, control box, and HMI human-machine interface), it can monitor key parameters such as sulfur content at the inlet and outlet of flue gas, pH value of the scrubbing liquid, flow rate, and pressure in real time. It supports remote monitoring and automatic fault diagnosis, reducing operational difficulty and training costs for crew members.