The application of the plant and machines is the decontamination of soil cuttings which are generated during drilling operations. The cuttings are contaminated with oil based drilling mud. The purpose is to reach the UK 500 mg/kg limit on hydrocarbon contamination of soil. The decontaminated soil may be placed on non-hazardous landfill sites without further treatment, or may be used e.g. in road constructions, ceramic industry or other industrial use.
Filtered cuttings from the drilling are transferred into a cylindrical mill. The mill crushes the cuttings into particles of optimum size. The mill homogenises the incoming substance and stores this solution (“mud”) in a buffer tank.
The mud is pumped in a controlled manner to an emulsion breaker, where the breaker segregates the emulsion into oily and watery fractions.
From the emulsion breaker, the mixed substance moves to the decanter. Here the solids and liquids phases are separated. At this stage the liquids may include minor solid content besides water and oil. Before decanting this liquid further filtering is undertaken.
Pre-heating
The thick mud from the decanter passes through a pre-heater heat exchanger to a thin-film-evaporator. The heat needed by the process is obtained by the condensation of the outlet steam generated by the distiller.
Evaporating
The mixture now moves to the thin-film-evaporator, where it is dried out. Here the humidity is less than 2%. During this stage a part of the oil is also evaporated resulting in a rise of hydrocarbon concentration. As a safety measure, this takes place in an inert environment. Because of the good heat transfer coefficient of the process we use steam already generated as the method of heating.
The dry soil from the distiller passes through to a thermal screw where thermal desorption take place and the remnant hydrocarbons are removed. The atmosphere inside the tunnel is also inert. The soil then passes through a cooler to a container for the decontaminated soil.
The steam and gas from the evaporator and the thermal screw processes pass through a pre-heater heat exchanger. An additional condenser is activated which is cooled with coolant water in a closed cycle.
The condensed water and oil mixture leaves the unit through outlets to a liquid–liquid separator. Here the floating oil is transferred to barrels and the water transferred to water tanks.
The water tank supplies the necessary amount of water required by the MUD MAX© for washing, coolants, etc. The surplus water is transferred by a level controlled pump to the water tank used for of the preparation of the mud.
The steam is provided through a steam boiler. It contains its own oil burner should this be needed.
The steam system contains the boiler water supply tank, the water treatment, the condensate separator and pump.
Electrical energy is provided either by a diesel generator or direct mains supply. The diesel generators can supply the necessary energy for a day without the need to be re-filled.
The MUD MAX© is controlled through a distributed control system (DCS) and the process and parameters are projected on a monitor for ease of operation.
The temperature, pressure, level, and flow measurements are made through transmitters.