Worldwide Inline Process Control Solutions

Automatic Tank Dewatering System

Over time, hydrocarbon storage tanks will accumulate certain amounts of “free” water which ultimately settles at the bottom of the tank. This water comes from various sources such as tank venting, leakages or even from the hydrocarbon itself; and periodically must be removed to prevent degradation of the hydrocarbon and to prevent corrosion at the base of the tank.

Above this free water layer at the base of the storage tank is a so called ‘’rag layer’’ consisting of an oil-water emulsion. This rag layer has different optical properties than that of the free water below it or the hydrocarbon above it, so the detection of this rag layer can be used to ensure complete water removal and reduce the amount of hydrocarbon drained from the tank.

Benefits of Automatic Tank Dewatering System

  • High level of accuracy down to low ppm levels
  • Installed on the drain line and not in the tank
  • Fast reaction of the optek system prevents hydrocarbons above the environmental limits being released into the drain line
  • System complies with hazardous area classifications

Inline Monitoring

optek’s TF16-N scattered light sensor is an excellent real time, accurate and repeatable device capable of making extremely low ppm level oil-in water measurements. By installing a TF16-N sensor in the drain line of the storage tank, this allows the real time determination of the point where the water removal is complete and the rag layer begins. It would then be at this point an automatic signal is sent closing the drain line and preventing the higher concentrations of hydrocarbons from being released. This is especially important where strict environmental controls are in place.