Liquid Phase Decontamination

TC-5000 is a new-generation hydrocarbon decontamination formulation that is environmentally safe, fully biodegradable, and compatible to all metallurgy. It is a blend of surface-active chemicals in a benign, highly effective solvent. The anionic and nonionic surfactants and the solvent in TC-5000 are exceptionally effective in removing heavy-end hydrocarbons such as vacuum residue and asphalt, as well as light end hydrocarbons such as benzene, from the process vessels in refineries and petrochemical plants.

Typical concentration of TC-5000 for a process application is 1% in water. This aqueous solution of TC-5000 is circulated in a closed loop through the plant process vessels and piping at 80º to 90ºC for 8 to 12 hours (wash cycle). In the wash cycle, TC-5000 forms a stable emulsion with the hydrocarbons present in the plant equipment and piping. At the end of the wash cycle, the emulsion is pumped out of the system, thus transporting the trapped hydrocarbons out of the system. The system is then rinsed with fresh water to displace the residual emulsion out of the system. At the end of the rinse cycle, and once adequate ventilation is provided, the decontaminated unit will have zero LEL, less than one ppm of benzene, and zero H2S.

Vacuum Bottoms Sample after Water-Push and Steaming
Vacuum Bottoms Sample after
Water-Push and Steaming
Vacuum Bottoms Sample with TC-5000 Oil-in-Water Emulsion
Vacuum Bottoms Sample with
TC-5000 Oil-in-Water Emulsion
Vacuum Bottoms Sample after TC-5000 Wash
Vacuum Bottoms Sample
after TC-5000 Wash

Before the wash procedure is initiated, refinery personnel will complete the normal plant shutdown procedure. All equipment to be decontaminated will be pumped out and depressurized. Heavy circuits will be flushed with light oil at maximum velocities in order to bring down the pour point of the remaining heavy hydrocarbon below 90 degrees C. Following this step, predetermined circuits will be pushed with water or steam to displace free hydrocarbons as needed.

Once most of the free oil is displaced (free oil must not exceed 40% of loop volume) the system is charged with water to normal operating levels and placed under self-sustained circulation. Steam injection is used to raise the temperature of the circulating solution between 80 to 90 degrees C.

The system is normally circulated for a period ranging between 8 to 12 hours. During the decontamination process, the equipment will be vented first to the flare system and afterwards to the atmosphere.

The temporary pumps used to circulate the water/chemical solution, if any, will be connected to the process equipment by means of temporary piping spools and high-pressure-and-temperature rated hoses.

The effluent generated during the decontamination process is typically pumped off to a holding tank, where the aqueous phase is then discharged to the plant waste water system and the oil is sent to the slop tank for re-processing.