Water Separator - Filtration. Pressure Vessel

October, 16 2020 by HVM
Oil Water Separator - Pressure Vessel
HVM Pressure Vessel

A water separator is an equipment used to separate water from different kind of materials like oil, fuel, diesel etc. (Nelson, 1989) There are different types of water separators based on the types of materials being separated and the separation performance parameters.

Types of Water Separators:

  • Oil Water Separators
  • Fuel Water Separators

Oil Water Separators (OWS): are used to separate oil and water in ship engines before removing oil into the sea from engine compartments which might have accumulated large amounts of water (Patterson et al., 2017).
Fuel Water Separators (FWS): Just like the oil water separator, the fuel water separator is a device used to separate water from fuel in the engines in order to make sure the proper engine running and functions (Jiang et al., 2018).

Working Principle and Basic Function of a Water Separator

The basic working principle of water separators is the gravity differential between oil/fuel/diesel and water. The density of oil/fuel/diesel is less than water, which makes the separation of both relatively easy.
A water separator typically consists of three units;
i. Separator Unit (Separates oil/fuel/diesel and water)
ii. Filter Unit (Filters other physical impurities from water)
iii. Control Unit (Monitors oil/fuel/diesel level)

The oil/fuel/diesel is separated from water in a separator tank in two phases. The first phase is separation by gravity while the second phase is separation by coalescing filters (Liao et al., 2020).

Oil Water Separator - Pressure Vessel
An Oil Water Separator. Adapted from (Kumar, 2020).

  • During first phase, the compartment is filled with clean water and the oil/fuel/diesel- water. The oil/fuel/diesel will rise above the level of water in heating process due to its low density in the coarse separating compartment. The entire section is known as collection space.
  • The oil/fuel/diesel level will then be monitored by a sensor and the oil/fuel/diesel will be dumped into a dirty oil tank (ppm/microns).
  • The remaining oil/fuel/diesel- water mixture will further move from the catch plates which will filter out more oil/fuel/diesel from the water and will send it to the collection space.
  • Then in the second phase, the water will be passed through the coalescer filters which will remove other physical impurities as well as the remaining oil/fuel/diesel impurities (if any) from the water.
  • Finally this clean water will be moved to clean water storage tank (15ppm) having audio and visual alarms for monitoring of water storage (Liao et al., 2020).

Water Separator Technical Requirements

  • The certification of the oil content control unit inside the separator which controls and monitors the storage of oil and internal alarm recordings is compulsory according to MEPC 107 (49).
  • The OCM that is equipped with the oil/fuel/diesel- water separator must be tempered- proof.
  • The OCM must trigger and sound an alarm whenever freshwater is used for zeroing or cleaning purposes.
  • Separator should be capable of achieving 15ppm on type C emulsion (Patterson et al., 2017).

Three factors affect the rate of separation at the most:

  • The size of oil/fuel/diesel globule
  • Temperature of the system
  • Type of water being used for separation (Piao et al., 2017)

Thus, while designing a pump for water separation, these factors must be kept into consideration for an effective and desired separation.

KUMAR, S., 2020. Mariners Point, Oily Water Separator : Construction, Working Principle, How It Works?. [Online] Available at: https://marinerspoint.in/oily-water-separator/2020/04/
JIANG, Z., LOFTIS, T. & JOHNSON, M. 2018. Fuel water separator filter. Google Patents.
LIAO, X.-H., YANG, S.-J., QIN, M.-W., DOU, M.-Y., FENG, Q., LI, H.-M. & ZOU, S. Overview of Oil-water Separation Equipment Technology of Refined Oil. IOP Conference Series: Earth and Environmental Science, 2020. IOP Publishing, 012131.
NELSON, P. E. 1989. Water separator. Google Patents.
PATTERSON, L. A., KONSCHNIK, K. E., WISEMAN, H., FARGIONE, J., MALONEY, K. O., KIESECKER, J., NICOT, J.-P., BARUCH-MORDO, S., ENTREKIN, S. & TRAINOR, A. 2017. Unconventional oil and gas spills: risks, mitigation priorities, and state reporting requirements. Environmental Science & Technology, 51, 2563-2573.
PIAO, L., KIM, N. & PARK, H. 2017. Effects of geometrical parameters of an oil-water separator on the oil-recovery rate. Journal of Mechanical Science and Technology, 31, 2829-2837.

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