How to purify and filter fuel oil?

Purification and filtration of fuel oil is a key step to ensure efficient fuel system operation and reduce equipment wear and emissions. The following are common purification and filtration methods and steps:

1. Sedimentation method

- Principle: Use gravity to separate water and solid impurities.

- Steps:

- Store the fuel in a static sedimentation tank (usually 24-48 hours).

- Water and larger particles naturally settle to the bottom and are discharged regularly through the bottom drain valve.

- Applicable: Primary treatment, especially for heavy or residual oil with high water content.

2. Mechanical filtration

- Equipment:

- Coarse filter: Remove larger particles (≥30 microns), usually a metal mesh or filter element.

- Fine filter: Remove fine particles (1-10 microns), such as paper, ceramic or synthetic fiber filter elements.

- Steps:

- Connect multiple-stage filters in series (coarse filter → fine filter), and ｒｅｐｌａｃｅ or clean the filter element regularly.

- For high-viscosity fuel oil (such as heavy oil), it is necessary to heat it to reduce the viscosity before filtering.

- Note: The filter must match the fuel type (such as light diesel, heavy fuel oil or biofuel).

3. Centrifugal separation

- Principle: Separation of impurities (water, solid particles) of different densities by centrifugal force.

- Equipment: Centrifugal oil separator (such as Alfa Laval oil separator commonly used in ships).

- Application:

- Processing of large amounts of fuel (such as ships, power plants).

- Can efficiently remove micron-sized particles and water.

4. Adsorption purification

- Method:

- Activated carbon: adsorption of organic impurities such as colloids and asphaltenes.

- Silica gel or molecular sieve: removal of residual water.

- Application: fine purification, often used in places with high requirements for fuel purity (such as gas turbine fuel).

5. Heating dehydration

- Steps:

- Heat the fuel to 60-80℃ (the specific temperature depends on the oil) to reduce viscosity and promote water separation.

- Combine precipitation or centrifugation to remove free water.

- Note: Avoid overheating and fuel oxidation.

6. Chemical treatment

- Additives:

- Demulsifier: Accelerate oil-water separation.

- Dispersant: Prevents colloid and particle aggregation.

- Applicable: For fuels with severe emulsification or poor stability.

Example of purification process (industrial/marine application)

1. Preheating: Heat the heavy oil to a flowing state (about 50-60℃).

2. Coarse filtration: Remove large particles through a self-cleaning filter.

3. Centrifugal separation: The oil separator continuously separates water and fine impurities.

4. Fine filtration: Pass through a 10-micron filter before entering the system.

5. Online monitoring: Detect moisture content (such as a capacitive sensor) and particle size.

Notes

- Regular maintenance: Clean the fuel tank and ｒｅｐｌａｃｅ the filter element to avoid secondary contamination.

- Fuel compatibility: Compatibility testing is required when mixing different oils (such as biodiesel and diesel).

- Safety: explosion-proof is required during heating, and static grounding must be good.

Depending on the type of fuel oil (light diesel, heavy oil, marine fuel oil, etc.) and purpose (engine, boiler, etc.), the combination and parameters of the purification process can be adjusted. For high-sulfur oil, desulfurization treatment must also be considered to meet environmental protection requirements.