Process, method, and system for removing heavy metals from fluids

Abstract

Trace amount levels of heavy metals such as arsenic in crude oil are reduced by contacting the crude oil with an oxidizing agent, extracting heavy metals into a water phase for subsequent separation from the crude oil. In one embodiment, the oxidizing agent is selected from the group of hydroperoxides, organic peroxides, inorganic peracids and salts thereof, organic peracids and salts thereof, halogens such as iodine (I2), bromine (Br2), and ozone. In one embodiment, at least a complexing agent selected from the group of metal m halides and / or sulfur compounds can be added to facilitate the removal of arsenic from crude oil by forming soluble heavy metal complexes in the water phase.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. patent application Ser. Nos. 12 / 950,060; 12 / 950,170; and 12 / 950,637, all with a filing date of Nov. 19, 2010. This application claims priority to and benefits from the foregoing, the disclosures of which are incorporated herein by reference.TECHNICAL FIELD[0002]The invention relates generally to a process, method, and system for removing heavy metals such as mercury, arsenic, and the like from hydrocarbon fluids such as crude oil.BACKGROUND[0003]Heavy metals such as lead, zinc, mercury, silver, arsenic and the like can be present in trace amounts in all types of hydrocarbon streams such as crude oils. In some crude oils, amounts of a heavy metal such as arsenic are associated with the mercury level. The amount can range from below the analytical detection limit (0.5 μg / kg) to several thousand ppb depending on the feed source. It is desirable to remove the trace amounts of these metals fro...

AI Technical Summary

Benefits of technology

[0007]In one aspect, the invention relates to an improved method to treat a crude oil to reduce its heavy metal concentration. In the method, a water stream consisting essentially of an oxidizing agent is added to the crude oil to extract at least a portion of the heavy metals into the water stream forming a waste stream. The improvement comprises adding a complexing agent, facilitating the formation of soluble compounds in the water stream, prior to separating the wastewater from the crude oil, leaving a treated crude oil having a reduced heavy metal level.

[0008]In another aspect, the invention relates to a method for reducing a trace amount of heavy metals, e.g., mercury, arsenic, etc., in a crude oil. The method comprises mixing into the crude oil an amount of an oxygen-containing compound selected from the group of oxyhalites, hydroperoxides, and organic peroxides, inorganic peracids, organic peracids, molecular halogens such as iodine (I2), bromine (Br2), and ozone to extract the heavy metals into a water-oil emulsion; adding an amount of a complexing agent to the water-oil emulsion to facilitate the formation of soluble heavy metal complexes in the water phase; and separating the water containing the soluble heavy metal complexes from the crude oil, leaving a treated crude oil having a reduced concentration of heavy metals such as arsenic and or mercury.

Problems solved by technology

However, filtering crude oil and / or condensate to remove arsenic is cumbersome and not cost effective.

Absorbent beds tend to get clogged by solid particulates in the crude, thus impeding the flow of the feed.

Absorbents can also be very costly due to the large quantity needed.