Electrostatic Filtration Of Fine Solids From Bitumen (ExxonMobil)

Electrostatic Filtration Of Fine Solids From Bitumen (ExxonMobil)
United States Patent Application 20160102254
Cullinane; John Timothy ;   et al.   April 14, 2016
Assignee: ExxonMobil Research and Engineering Company
Abstract
Methods are provided for removing fine particles from crude oils extracted from mined oil sands using a non-aqueous extraction solvent. A bitumen derived from non-aqueous extraction of oil from oil sands can undergo optional physical separation to remove larger particles and then processed using electrostatic filtration to remove particle fines. This can allow for production of a bitumen product from a non-aqueous extraction process that has a sufficiently low particle content to be suitable for pipeline transport.
FIELD OF THE INVENTION
[0002] This disclosure provides methods for separating fine solids from bitumen using electrostatic filtration.
BACKGROUND OF THE INVENTION
[0003] Oil sands are an increasingly important source of raw petroleum. Due to the solid nature of oil sands, extraction of crude oil from oil sands presents a variety of challenges. Some challenges are related to creating a crude oil from the oil sands that is suitable for transport via pipeline.
[0004] One option for removing the non-petroleum material is to first mix the raw product with water. For example, a water extraction process can be used to separate a majority of the non-petroleum material from the desired raw crude or bitumen. A water extraction process can remove a large proportion of the solid, non-petroleum material in the raw product. However, after the initial water extraction process, smaller particles of non-petroleum particulate solids will typically remain with the oil phase at the top of the mixture. This top oil phase is sometimes referred to as a froth. Separation of the smaller non-petroleum particulate solids can be achieved by adding an additional solvent to the froth of the aqueous mixture. This is referred to as a "froth treatment". For example, a paraffinic solvent such as heptane can be added to the froth to cause a phase separation between an aqueous based phase and a bitumen phase. Unfortunately, due to the nature of the paraffinic solvent, a portion of the potential petroleum product is lost with the aqueous phase. The petroleum product lost with the aqueous phase may include a substantial portion of asphaltenes.
[0005] As an alternative to a water extraction, a non-aqueous extraction can be performed to separate crude oil from oil sands. Use of a non-aqueous extraction solvent can reduce or minimize the amount of water needed for extraction of crude oil from oil sands, and can potentially eliminate the need to perform a subsequent froth treatment.
[0006] However, use of a non-aqueous extraction solvent can increase the amount of fine particulate matter that remains in the bitumen phase. The presence of an elevated content of fine particulate matter can create difficulties when attempting to transport such a non-aqueous extracted crude oil via pipeline.
[0007] U.S. Pat. No. 8,114,274 describes a method for treating bitumen froth with high bitumen recovery and dual quality bitumen production. The method includes using multiple gravity settling steps to separate phases containing bitumen in a hydrocarbon diluent from phases containing water, fine solids, and residual bitumen. Naphtha is provided as an example of a hydrocarbon diluent. One described advantage of the method is generation of a lighter bitumen stream that is suitable for transport by pipeline without further processing.
[0008] U.S. Published Patent Application 2012/0000831 describes methods for separating out a solvent feed after use in recovery of bitumen from oil sands. The method includes treating a bitumen froth with a paraffinic or naphthenic type diluent to produce bitumen and froth treatment tailings. Toluene is identified as a naphthenic type diluent that can improve bitumen recovery from tailings.
[0009] U.S. Published Patent Application 2014/0021103 describes methods for extracting bitumen from an oil sand stream. The method includes contacting the oil sand stream with a non-aqueous solvent and then screening the combined oil sand and solvent stream to form a screened oil sand stream and a rejects stream. Bitumen is then extracted from the screened oil sand stream.
[0010] U.S. Pat. No. 5,308,586 describes an electrostatic separator using a bead bed. The separator is described as being suitable for separating FCC catalyst fines from an FCC slurry oil. The electrostatic separator is periodically backflushed with additional treated slurry oil to remove particles from the separator. These backflushed particles are returned to the FCC reactor.
SUMMARY OF THE INVENTION
[0011] In an aspect, a method is provided for producing a bitumen product from oil sands, including extracting bitumen from oil sands with a non-aqueous extraction solvent to form a mixture of bitumen and extraction solvent; performing a physical separation on at least a portion of the mixture of bitumen and extraction solvent to form at least a first filtered mixture of bitumen and extraction solvent; separating at least a portion of the first filtered mixture of bitumen and extraction solvent to form a filtered bitumen stream and a filtered extraction solvent stream, the filtered bitumen stream containing at least about 0.25 wt % of non-petroleum particles; and performing an electrostatic separation on at least a portion of the filtered bitumen stream to form a bitumen product containing about 1200 wppm or less of non-petroleum particles. Optionally, the method can further include diluting the bitumen product with a diluent, the diluent being different from the extraction solvent.
[0012] In some aspects, performing an electrostatic separation on at least a portion of the filtered bitumen stream can include passing the at least a portion of the filtered bitumen stream into a separation volume of an electrostatic separator under effective electrostatic separation conditions, the effective electrostatic separation conditions including maintaining a separation voltage across the separation volume, at least a portion of the separation volume optionally containing a solid dielectric material; purging the separation volume with a purge fluid to form a purged portion of the bitumen product; and washing the separation volume with the extraction solvent, a washing voltage across the separation volume during the washing being less than the separation voltage.
[0013] In another aspect, a method is provided for producing a bitumen product from oil sands, including extracting bitumen from oil sands with a non-aqueous extraction solvent to form a mixture of bitumen and extraction solvent; performing a physical separation on at least a portion of the mixture of bitumen and extraction solvent to form at least a first filtered mixture of bitumen and extraction solvent, the first filtered mixture of bitumen and extraction solvent containing at least about 0.25 wt % of non-petroleum particles; performing an electrostatic separation on at least a portion of the first filtered mixture of bitumen and extraction solvent to form a filtered, separated mixture of bitumen and extraction solvent; and separating at least a portion of the filtered, separated mixture of bitumen and extraction solvent to form a bitumen product and an extraction solvent stream, the bitumen product containing about 1200 wppm or less of non-petroleum particles. Optionally, the method can further include diluting the bitumen product with a diluent, the diluent being different from the extraction solvent.
[0014] In some aspects, performing an electrostatic separation on at least a portion of the first filtered mixture of bitumen and extraction solvent can include passing the at least a portion of the first filtered mixture of bitumen and extraction solvent into a separation volume of an electrostatic separator under effective electrostatic separation conditions, the effective electrostatic separation conditions including maintaining a separation voltage across the separation volume, at least a portion of the separation volume optionally containing a solid dielectric material; purging the separation volume with a purge fluid to form a purged portion of the filtered, separated mixture of bitumen and extraction solvent; and washing the separation volume with the extraction solvent, a washing voltage across the separation volume during the washing being less than the separation voltage.
Free Full Text Source:  http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=15&f=G&l=50&co1=OR&d=PG01&s1=separation.TTL.&s2=separation.AB.&OS=TTL/separation+OR+ABST/separation&RS=TTL/separation+OR+ABST/separation