Oil reservoirs (oil collectors) are used to store drained oil residue from various oil-filled equipment and pipeline condensate. The most common users of such reservoirs are industrial enterprises of oil, petrochemical, oil refining, gas and power.
According to the existing classification there are horizontal underground oil collectors, underground storage tanks/reservoirs for oil and underground collectors for oil and water.
Underground storage tank is a device consisting of two conical bottoms and two manholes. Manholes are used by the personnel for reservoir maintenance and pumping out stored material using a semi-submersible pump nit. Special performance of the pump depends on the operating conditions of oil reservoir (explosion-proof, corrosion, double seal, etc.).
In order to prevent corrosive atmospheric effect on the pump motor and to protect it against low temperatures, metal or concrete wells are used.
The design of oil reservoir can also include an embedded heater. Metal coiled pipes for heating with steam-water mixture prevent oil from freezing or thickening. There is also an option to keep the temperature of reservoir using a heating cable.
Oil collectors, equipped with heating facilities, belong to Category 1. And the reservoirs without heating – to Category 2.
To prevent heat dissipation into the environment, the devices are equipped with special insulation.
Connection of additional devices (thermometers, fluid level indicators and pressure gauges) is achieved through special nozzles. Some underground oil reservoir models have special sumps, designed to reduce fluid oscillations during measurement operations.
The main advantage of underground oil reservoirs is an opportunity to save space. Such arrangement are now considered the most beneficial solution for substations.