Main Process Flow of Oil Sludge Pyrolysis Refinery

Main Process Flow of Oil Sludge Pyrolysis Refinery

The core of an oil sludge pyrolysis refinery is to recover oil from sludge and stabilize residues through oxygen-free pyrolysis. The entire process is divided into five key stages: pretreatment, pyrolysis, oil-gas condensation and refining, exhaust gas purification, and residue disposal.

1. Oil Sludge Pretreatment

Dehydration and Drying: Mechanical dehydration (e.g., centrifugation, filter pressing) and hot air drying reduce the moisture content of oil sludge from 60%–80% to below 10%, improving pyrolysis efficiency.

Crushing and Screening: Oil sludge is crushed to a particle size of less than 10 mm, removing sand, metal, and other impurities to avoid equipment wear or impaired pyrolysis performance.

Conditioning and Modification: Some high-viscosity oil sludges require additives to reduce viscosity, ensuring uniform feeding.

2. Pyrolysis Reaction

Continuous Feeding: Pretreated oil sludge is fed into a closed pyrolysis furnace (typically a horizontal rotary furnace or fluidized bed furnace) via a screw feeder.

Oxygen-Free Pyrolysis: At 450–650°C in an oxygen-deficient environment, organic components in the sludge crack to produce an oil-gas mixture and solid residues.

Heat Recycling: Combustible gas generated during pyrolysis is purified and reused to heat the furnace, achieving energy self-sufficiency and reducing operating costs.

3. Oil-Gas Condensation and Refining

Multi-Stage Condensation: High-temperature oil gas passes through a quenching tower and condensers in sequence, separating crude oil (fuel oil) and non-condensable gas.

Oil Refining: Crude oil undergoes dehydration, impurity removal, hydrotreatment, or catalytic processing to eliminate sulfur, nitrogen, heavy metals, and other impurities, producing non-standard diesel or fuel oil.

Non-Condensable Gas Recovery: Uncondensed combustible gases (e.g., methane, hydrogen) are partially reused for furnace heating, with excess gas supplied as clean fuel.

4. Exhaust Gas Purification

Desulfurization and Dechlorination: Acid gases such as hydrogen sulfide and hydrogen chloride are removed via an alkali scrubber.

Dioxin and VOCs Treatment: Activated carbon adsorption and catalytic oxidation are used to deeply purify dioxins and volatile organic compounds (VOCs) in exhaust gas, ensuring compliance with emission standards.

Dust Removal: Dust in exhaust gas is removed using a baghouse or electrostatic precipitator, and the final clean exhaust gas is discharged through a chimney.

5. Residue Disposal

Residue Cooling: Solid residues from pyrolysis are cooled by water or air, consisting mainly of carbon black, ash, and stabilized inorganic substances.

Resource Utilization: If residue oil content meets national standards (typically ≤3%), it can be used as road base material, brick-making raw material, or for carbon black extraction. Excess oil content residues are disposed of as hazardous waste in accordance with regulations.