Solvent Oil Dewaxers

Solvent Oil Dewaxing filters have been specifically designed and constructed for the most efficient method of processing petroleum base oil lubricating stocks to produce wax-free oil and oil-free wax.

Dewaxer, Eimco-type
  • Solvent Oil Dewaxers
  • MEK, MiBK and DiMe Dewaxing Filters
  • Propane Dewaxers

Leader in Dewaxing Filter Technology

Wherever dewaxing filters are used, FLSmidth world-renowned technology has brought many benefits - superior recovery and quality of oil and wax, rigorous environmental protection, and maximum productivity. The know-how necessary to deliver a reliable product, tailor-made for the job, has resulted in considerable savings for the petrochemical industry over many years. 

The majority of lube oil plants use MEK based solvent dewaxing technology and Dorr-Oliver Eimco has supplied hundreds of filters for the MEK process as well as hundreds more for other solvent dewaxing processes, based on DIME, propane, etc.


Features and Benefits

  • Molded, interlocking filter grids
  • Filter and scroll drives
  • Special peripheral valve seal
  • EPDM flange gasket and self-aligning swing bolts
  • Floating stuffing boxes
  • Cake discharge deflector and clean out flush system
  • Hydraulic hood lifting mechanism
  • Expanded purge angle
  • Broken wire alarm
  • External wire tensioner.



  • Various design improvements have been pioneered and introduced by DORR-OLIVER and EIMCO
  • Valve end internal bearing design insures "vapor tight" unit while eliminating the need for stuffing boxes on the valve end
  • Drive end floating stuffing box arrangement in conjunction with a stainless steel bellow type seal, also insures "vapor tight" construction
  • Double mechanical seals and double tongue/groove arrangements for "zero-emission" perforemance
  • Nylon grid drum deck construction results in improved hydraulic efficiency, increased cloth media life and reduced maintenance
  • Redesigned drum internal piping improves drum hydraulics and enhances drum structural integrity

Performance Benefits

Elimination of solvent losses 

  • Double mechanical seals on all shafts. 
  • Improved hood-vat-seal 
  • Flexible bellows for valve-to-tank sealing 
  • Floating shaft seal at drive-end 

Elimination of wax losses or contamination in filtrate 

  • Positively-acting peripheral valve seal (50 % submergence MEK filters). 

Improved oil/wax recovery (maximum wax in cake) 

  • Optimal-drainage sloping filtrate pipe design
  • Inert gas purge to prevent cake rewetting on blow-back
  • Multiple branch-pipes and large filtrate piping for improved evacuation. 

Improved wax transport 

  • Multi-sectioned wax deflector for improved contact 
  • Large diameter scroll 

Increased operating time 

  • Optional cold solvent backwash of cloth (MEK). 
  • Hot solvent washing of cloth 
  • Minimum maintenance frequency. 
  • Minimum down-time for planned maintenance.


Dewaxing Filter

Maintenance Benefits

  • External precision, long-life, anti-friction, spherical roller bearings on drum shafts and scroll drive-side
  • Proven commercially-available, long life, cartridge-type, double mechanical seals on drum shafts and scroll; optional stuffing boxes. 
  • Floating seal arrangement on drum drive shaft. 
  • Valve design with easy access for adjustment or exchange of wear parts, without raising hood. 
  • Valve-centralising anti-friction bearing protected from process fluids. 
  • Shaft-mounted units for drum and scroll drive allowing easy removal. 
  • Variable frequency-controlled drum drive for minimum mechanical maintenance. 
  • Centrally supported wax scroll with special, self-aligning bearing to eliminate critical alignment and risk of failure. 
  • Was scroll on larger units split into two sections for ease of removal. 
  • Self-aligning, hydraulic hood-lifting system which eliminates accidental damage to hood, vat or seal. 
  • Easily-exchangeable hood-to-vat seals with swing bolts or commercially available clamp bolts, to facilitate hood opening. 
  • Safe-operation, modernised wire-winding device on carriage. 
  • Optional solvent wash-header system beneath deflector blade to eliminate wax build-up. 
  • Exchangeable tips for cake scraper blade. 
  • Large hood observation ports, with high internal light intensity for good visibility.

    Dewaxer DiME Type

  • Propane dewaxing is used where refinery logistics prefer available propane over other solvents. Propane dewaxers are similar to conventional, totally-enclosed solvent dewaxing filters - except that design pressures up to 4.5 bar (65 psi) are specified for the vat and hood. Operating pressures of 1.0 - 2.0 bar (15 - 30 psi) are used to maintain propane at the optimum pressure and temperature.

    FLSmidth has supplied more than 40 propane dewaxing filters and several have demonstrated a life span of over 45 years. Continuous development means that the latest generation design eliminates solvent emissions, prevents wax losses and minimises maintenance.


    Propane Dewaxer

    Features and Benefits

    • The propane dewaxer pressure vessel - vat, hood and integral flange closure - is manufactured from quality-certified materials. The vessel is fully stress-relieved after welding and the comprehensive testing and materials certification necessary for ASME or equivalent coded pressure vessel manufacture is provided, ensuring safe and reliable operation.
    • Special manufacturing procedures ensure perfectly mating surfaces in the critical flange-closure area. Dead sections of the vat are partitioned above trunnion level to eliminate unnecessary liquor hold-up. 
    • The drum, scroll and wax deflector features and benefits introduced into MEK/DIME dewaxing filters are applicable to the propane dewaxer. 
    • Large shell-type, force-oil-lubricated, drum bearings are normally located within the vat and hood to minimise problems of large shaft sealing. 
    • External drum drive is used. A small diameter drive shaft passes through a stuffing box or mechanical seal assembly mounted on the wall of the pressure vessel and the shaft is attached to the drum trunnion by a flexible connection. 
    • An external roller-bearing option with stuffing box or double-mechanical seal is available at the drive-end. 
    • The automatic valve is positioned in a vapour space within the vat and hood to overcome leakage during 50% submergence conditions. A back-up peripheral valve seal, similar to that in MEK dewaxers, is also fitted.


    Propane Dewaxer


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