FIELD OF THE INVENTION

The invention is in the field of methods for shaping materials, in particular by physically and chemically treating viscous bituminous liquids to form discrete solid-encapsulated shapes, optionally with associated recovery of light ends as a separate product stream.

BACKGROUND OF THE INVENTION

It is common practice to segregate petroleum substances of high viscosity and density into two categories, “heavy oil” and “bitumen”. For example, some sources define “heavy oil” as a petroleum that has a mass density of between about 920 kg/m3(or an API gravity of about 26°) and 1,000 kg/m3(or an API gravity of about 10°). Bitumen is sometimes described as that portion of petroleum that exists in the semi-solid or solid phase in natural deposits, with a mass density greater than about 1,000 kg/m3(or an API gravity of about 10°) and a viscosity greater than 10,000 centipoise (cP or 10 Pa·s) measured at original temperature in the deposit and atmospheric pressure, on a gas-free basis. Although these terms are in common use, references to heavy oil and bitumen represent categories of convenience, and there is a continuum of properties between heavy oil and bitumen. Accordingly, references to heavy oil and/or bitumen herein include the continuum of such substances, and do not imply the existence of some fixed and universally recognized boundary between the two substances. In particular, the term “heavy oil” includes within its scope all “bitumen” including hydrocarbons that are present in semi-solid or solid form. Similarly, a “bituminous” material is one that includes a bitumen component, as that component is broadly defined.

Bituminous liquids generally include an asphaltene component. Asphaltenes may for example be suspended as a nanocolloid or otherwise dispersed within a bituminous liquid. Asphaltenes may be defined practically by differential solubility, for example as the component of a bituminous material that is insoluble in n-alkanes, such as n-pentane or n-heptane, and soluble in toluene or benzene. In molecular terms, asphaltenes are generally present as a complex mixture that includes high molecular weight polyaromatic carbon ring units, with oxygen, nitrogen, and sulfur heteroatoms, as well as alkane chains and cyclic alkanes. As used herein, the term “asphaltenes” encompasses this wide range of variously defined materials, and an “asphaltenic” material is one that includes an asphaltene component, as that component is broadly defined.

The presence of asphaltenes in bitumen has in some circumstances been suggested to represent a potential production or transportation problem. During production, for example, asphaltene precipitation and deposition are recognized risks that may result from changes in pressure, temperature, chemical composition and shear rate. In contrast, in some bitumens, relatively high asphaltene concentrations appear to be present as a stable viscoelastic network (Yang and Czarnecki, 2005, Energy & Fuels 19, no. 6: 2455-2459). In the context of transportation, methods have for example been described for removing asphaltenes from bitumen prior to transport (see for example US Patent Publication 20170002275). For these and other reasons, a wide range of processes are known for removing asphaltenes from petroleum liquids, for example in de-asphalter units in crude oil refineries or bitumen upgraders, such as solvent de-asphalter units that separate the asphaltenes by virtue of the fact that light hydrocarbons, such as propane, butane or pentane, will dissolve aliphatic compounds but not asphaltenes.

Heavy oils and bitumen can be separated into not only viscous components such as asphaltenes but also lighter materials. These light ends are composed of saturate (alkane) and aromatic components and typically have viscosities lower than that of the asphaltenic component. Upon heating of heavy oil or bitumen, reactions occur that can break bonds in the heavy components of the heavy oil and bitumen leading to the generation of lighter materials such as saturate and aromatic components. These components, when mixed with the original heavy oil and bitumen, can lead to an upgraded oil product.

The foregoing characteristics of heavy oils and bitumen give rise to a variety of risks and challenges associated with transportation, handling and storage, in liquid form or otherwise. There is accordingly an ongoing need for improved techniques for transporting and handling heavy oil and bitumen. Furthermore, if the heavy oil or bitumen is processed for transportation which generates lighter components from the reactions done to prepare the heavy oil or bitumen for transport, then these light components can be collected and sold as a product stream or collected and remixed with the original heavy oil and bitumen to yield the original oil product or a partially upgraded oil product.

SUMMARY

In one aspect of the invention, processes are provided that take advantage of the recognition that endogenous asphaltenes in a bituminous liquid may be induced to coalesce on the surface of an aliquot of the bituminous liquid, so as to form a resilient membrane that has sufficient structural integrity to retain the remaining bituminous liquid in the form of a discrete shape. In effect, endogenous asphaltenes in the bituminous liquid are converted into a resilient solidified surface layer on shaped units of the bituminous liquid. These pellets or capsules of bitumen are then amenable to material handling techniques adapted for particulate solids. During these processes to form endogenous asphaltenes on the surface of an aliquot of the bituminous liquid, light components may be generated from reactions that occur at the surface of the bituminous liquid. These light components are generally composed of relatively low molecular weight alkanes (linear hydrocarbons up to C20 alkanes and potentially above) and aromatics (cyclic hydrocarbons up to C20 aromatics and potentially above). These light components can be collected as a separate liquid product stream.

Methods are accordingly provided for segregating a bituminous liquid into discrete shaped units. In a continuous process, generally applied to heated bitumen, the bituminous liquid may be divided into shaped liquid aliquots, each aliquot having a discrete shape defined by a material handing mechanism that contains the aliquot. For example, in a process analogous to gravure printing, a rotating cylinder may be shaped with indentations, and the surface of the cylinder flooded with bituminous liquid. The cylinder may then be wiped with a doctor blade, so that separate aliquots of the bituminous liquid remain within each of the recessed indentations. The exterior surface of each shaped aliquot may then be treated, for example by heating of the rotating cylinder, so that the indented gravure cylinder acts as a heated coating roll, with the heat forming an outer membrane of asphaltenic material from the shaped bituminous liquid. In this way, each shaped aliquot is encapsulated within a resilient asphaltenic coating. The outer asphaltenic layer is sufficiently resilient to retain the discrete shape of the shaped aliquot when the aliquot is released from the material handling mechanism. In a process again analogous to the transfer of ink in gravure printing, the shaped aliquots may for example be released from the patterned rotating cylinder onto a substrate, for example after being nipped between a second heated backing roll and the heated patterned gravure roll. The shaped aliquots released onto the substrate form resiliently shaped units of bituminous liquid encapsulated in the asphaltenic outer membrane, which may for example be cooled on the substrate, and then released from the substrate, for example with a scraper, producing pellets of bituminous liquid. During the process analogous to gravure printing, the light components generated during the step of forming the shaped bituminous liquid can be collected into a separate liquid product stream.

In alternative aspects, the density of the units of bituminous liquid produced by processes of the invention may be adjusted, for example by incorporating agents within the pellets such as gas bubbles, catalysts, or solvents. In some embodiments, pellets can accordingly be designed to be buoyant in water, which may for example facilitate recovery of the pelleted material in the event of an environmental release or spill.

In other alternative aspects, the light component stream may be collected and sold as an individual product or can be mixed at a later time with the units of bituminous liquid to form a mixture similar to the original heavy oil or bitumen or a partially upgraded oil.

