Oil Water Separator in Washing Plant

2021-03-12 vwalve By vwalve
Steel manufacturers apply proactive coatings to their products to prevent rust, and all stamping processes use protective coatings or lubricants on dies and forming equipment to extend the service life of the dies and machinery. When the parts are cleaned to remove these coatings and ensure proper paint adhesion, the oils build up in the cleaning solution of the parts washer.
 
Below is a typical application case of our oil-water separator for oil removal in the industrial washing industry:
 
The function of the battery can washing machine is to clean battery cans and prepare them for subsequent drying and assembly. To achieve this, it is essential to remove all residues left on the can surface after stamping and forming, including: lubricating oil, iron filings, and mineral oil. The cleaning principle involves using high-pressure spray to impact the workpiece surface for degreasing and cleaning, combined with the physical decontamination of solvent-based cleaners. This is followed by a chemical water-based anti-rust spray treatment to enhance surface corrosion resistance and prevent surface oxidation.
 
A significant amount of lubricating oil, iron filings, and mineral oil is generated during this cleaning process. Therefore, it is necessary to continuously return the cleaning tank fluid and/or part of the tank fluid from other stations to the pre-cleaning tank to maintain its pH at approximately 2.0. This facilitates better removal of soluble lubricating oil, promotes oil decomposition, and prevents oil accumulation on the tank sidewalls and bottom.
 
The oil-water separator and overflow wastewater recovery system applied in this case collects the discharged overflow wastewater. Through sedimentation, the dispersed oil in the middle and lower layers of the aqueous solution first aggregates and then separates, achieving thorough oil-water separation. The oil contaminants float to the top of the sedimentation tank and are discharged into an oil collection tank via an adjustable overflow port. The separated cleaning fluid is then recirculated to the pre-cleaning tank for reuse. This treatment process not only recovers part of the cleaning fluid but also significantly reduces wastewater discharge.
 

How does the oil water separator work?(flow chart as below)

COALESCER -oi water separator-FLOW CHART

  1. PROCESS WATER IS SKIMMED FROM WASH TANK TO COLLECTION TANK
  2. WATER/OIL IS PUMPED TO COALESCER FROM COLLECTION TANK
  3. WATER/OIL TRAVELS OVER UNDER BAFFLES AND THROUGH MEDIA
  4. OIL IS SKIMMED OFF TO OIL COLLECTION TANK THEN PUMPED TO WASTE/RECYCLE
  5. PROCESS WATER IS GRAVITY RETURNED TO MIX TANK
  6. ADD CITY WATER TO MIX TANK
  7. PROCESS WATER IS PUMPED FROM MIX TANK TO PRE-WASH SPRAY

How to adjust the oil flow?

oil water separator- weir adjust
  • Ensure the tramp oil discharge valve is closed before starting.
  • Set the adjustable weir to the upper position until a significant tramp oil buildup is observed.
  • Raise the weir by turning the weir handle clockwise.
  • After sufficient buildup, lower the adjustable weir (clockwise) so oil spills over and exits the separator.
  • Open the tramp oil discharge valve to transfer accumulated oil to the disposal container; remove as needed.
  • Avoid excessive buildup to prevent backflow into the sump.
  • If desired, keep the level high and periodically open the discharge port’s ball valve to purge the oil; in high-tramp-oil scenarios, leave the port open continuously to remove oil.

Performance and Benefit

The separation efficiency can achieve up to 99%, effectively removing virtually all free and dispersed non‑emulsified oils from the process fluid, and reducing the residual oil concentration in the effluent to below 6 ppm. Meanwhile, the wash bath is stabilized within the specified control range for reaction products, ensuring consistent cleaning capacity and sustained performance throughout the operation.

oil water separator - effect