Treatment process for waste streams
AssigneeScfi Limited
InventorsJohn O'Regan, David McGarry
Life of this patent
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Abstract
A spent caustic treatment process addresses the shortcomings with traditional Wet Air Oxidation Systems. The process can treat either refinery or sulphidic spent caustic streams with CODs of up to 50,000 mg/L. The process uses >90% oxygen as an oxidising agent. A horizontal, tubular reactor is operated at pressures between 100 and 170 Bar (ideally 145-165 Bar). The reactor has an operating temperature of between 120° C. and 320° C., ideally 280° C. to 300° C. A closed heat transfer medium circulation loop is utilised for heat recovery from the reactor effluent stream to the spent caustic feed stream. The invention allows for a COD reduction of 7 5 to 99.9%.
Claims18
A treatment process for treatment of a feed stream with oxidizable COD, wherein the process comprises:
- a. feeding the feed stream through a tubular reactor with exothermic oxidation reactions at line velocities and sufficient salt dilution to avoid precipitation, in which a plurality of injection points inject inline oxygen and quench water to control exothermic oxidation reactions in the reactor, wherein:
- retention time in the reactor is in the range of 8 mins to 30 mins,
- a pump pumps quench water to the quench water injection points along the length of the reactor, quenching the reactor temperature before more oxygen is injected, driving the reactions to completion,
- reactor heating is performed by one or more heat exchangers having a tube-in-tube configuration, the outer tube carrying a pressurized heat transfer medium, temperature in the reactor is in the range of 220° C. to 360° C.,
- pressure in the reactor is in the range of 90 Bar to 170 Bar,
- b. performing heat recovery from a reactor effluent stream, and
- c. a gas/liquid separator separating the effluent stream to provide a gas safe for discharge and a treated liquid effluent stream.
Dependencies are inferred from the claim text.