Method for Utilizing Refined Coal to Purify Refining Process Components in Petroleum Coke Production

Abstract

A method for producing coke and one or more volatile products includes the following steps: (i) providing a purified coal product (PCP), wherein the PCP is in particulate form and wherein at least about 90% v of the particles have a diameter not greater than about 100 microns; wherein the PCP has an ash content of less than about 10% m and a water content of less than about 5% m; (ii) combining the PCP with a liquid residual oil to produce a combined solid-liquid blend, wherein the solid-liquid blend comprises at least about 0.1% m and at most about 30% m of the PCP; (iii) subjecting the solid-liquid blend to a temperature in excess of 375 °C for a period of time sufficient to cause at least 1% of the PCP particles to crack to produce one or more volatile products, and (iv) producing coke from the product of step (iii).

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to UK Patent Application No. 1906563.0, filed on May 9, 2019, and UK Patent Application No. 1907378.2, filed on May 24, 2019, both of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention lies in the field of the processing and utilization of solid hydrocarbons, and more specifically coal. Specifically, the present invention lies in the field of remediation and utilization of waste pulverized coal derived from mineral extraction and mining activities as well as coke production. Background Art

[0004] Pulverized coal and ultrafine powder (including fine powder) are small particles of coal generated from larger lumps during the mining and preparation processes. Although pulverized coal retains the same energy potential as coal, due to the particulate nature of the product, it is difficult to sell and transport, and thus it is usually regarded as a waste product. The mining industry alone generates up to 70 million to 90 million tons of pulverized coal as waste by-products in the United States every year (Baruva, P., Losses in the coal supply chain, IEA Clean Coal Centre Rep. CCC / 212, p. 26, December 2012, ISBN 978 - 92 - 9029 - 532 - 7), the vast majority of which remains unused. Therefore, pulverized coal is usually discarded as slag near coal mines, thus forming large waste piles, or it is contained in large ponds that require careful future management to avoid environmental pollution.

[0005] However, in its natural state, coal fines typically contain significant levels of ash-forming components and high water content, which renders them unsuitable for many conventional uses. It is a traditional view that the cost of dehydrating and / or drying and de-ashing powders with a diameter <150 μm generally exceeds the actual value of the resulting product (Muzenda, E., "Potential uses of South African Coal Fines: A Review", 3rd International Conference on Mechanical, Electronics and Mechatronics Engineering (ICMEME'2014), 19 - 20 March 2014, Abu Dhabi (United Arab Emirates (UAE)), p. 37). It is known that highly processed coal fines are added to fuel oil to reduce the cost per unit volume of the resulting blended fuel oil (see, for example, U.S. Patent No. 9,777,235). Additionally, highly processed coal fines can be added to crude oil to facilitate the fractionation products after distillation (see the international patent application published as WO2017 / 174973). In both cases, the coal fines are blended with liquid hydrocarbons to produce a resulting admixture with an increased perceived commercial value greater than the commercial value of the solid fines alone.

[0006] Coke is classified as a fossil fuel and is a non-renewable energy source. Traditionally, coke is produced by the destructive distillation of coal in coke ovens. In this process, the coal is heated (i.e., coked) in an oxygen-free atmosphere until most of the volatile components in the coal are expelled. The remaining material is a solid carbon mass called coke. As the popularity of coal declines, coke has recently been increasingly obtained from residual oils through destructive distillation (thermal cracking), such as in delayed or fluidized coking processes. Coke produced by these processes is commonly referred to as "petroleum coke". Additionally, similar to oil refining, the volatile products obtained from the delayed coking process are always more valuable than the residual oil feedstock. A way to blend the residual oil feedstock with cheaper starting materials to expand the limited reserves of hydrocarbon-containing mineral resources and the resulting refined distillate products would be highly desirable.

[0007] Delayed cokers are an integral part of the oil refining process as they help upgrade the heavy residual oil fractions obtained from earlier crude oil distillation / catalytic cracking processes into distillate fractions and petroleum coke, a carbon-rich solid material. The recovered distillates are used to prepare additional naphtha, kerosene, and oil gas streams within the refinery. Petroleum coke is used as fuel and, if the sulfur and metal content is low, as a more valuable anode grade in the manufacture of alumina and titanium oxide.

[0008] An alternative to the delayed coker is the fluid coker, in which the feedstock is pyrolyzed on the surface of hot fluidized coke particles. The feedstock is sprayed into a fluidized bed of hot petroleum coke particles in a first vessel. Volatiles are released, separated from the coke particles, and collected for further processing. The fluidized coke particles now with an additional coke load from the pyrolyzed feedstock are sent to a second vessel where they are partially burned to raise their temperature. A portion of these hot coke particles is returned to the first vessel to continue the cycle, while the remaining coke particles are withdrawn and used for other purposes, such as feedstock for a gasifier unit.

[0009] U.S. Patent 4,259,178 relates to a method for carbonaceous coke. The carbonaceous coke is produced by delayed coking a slurry mixture of about 10% to about 30% by weight of caking or non-caking coal having an approximate analysis of about 32.7% volatiles, 7.2% moisture, 44.8% fixed carbon, and 15.3% ash and about 90% to 70% by weight of a petroleum processing residue having a composition of about 51% aromatics, 19.3% saturates, 25.2% polar compounds, and 4.5% asphaltenes and a specific gravity of about 1.006 at a mixing temperature of 50° - 65°C. The produced coke has very special properties and is described as softer, more brittle, and more porous than conventional metallurgical coke or foundry coke.

[0010] U.S. Patent 4,427,532 relates to a method for producing coking coal. Hydrotreated petroleum resid is coked in the presence of coal to increase the yield and quality of the liquid coking products. Suitable coals are of low grade, having a carbon content of less than 75% (by weight), and best results are obtained using sub-bituminous coal. It is proposed that the oxygen content of the coal causes the removal of heteroatoms such as nitrogen and sulfur from the resid and thus, the oxygen content of the coal is of importance in coal selection, which is considered applicable to the described process.

[0011] U.S. Patent 4,943,367 relates to a method for producing high-purity coke from coal that has been beneficiated to an ash content of not more than 20%. High-purity coke particularly suitable for producing anodes for aluminum smelting is produced by an integrated process including flash pyrolysis and delayed coking. In the integrated process, the rapid pyrolysis of carbonaceous materials such as coal, oil shale, or tar sands is carried out under conditions that maximize the production of liquid tar suitable for subsequent use in a delayed coker.

[0012] U.S. Patent 4,259,178 describes a method for making carbonaceous coke by delayed coking a slurry mixture of about 10 to about 30% by weight of caking or non-caking coal and the remaining petroleum resid blended at a temperature below 50°C. Parameters of the coal used such as particle size and distribution, ash, and water content are not disclosed in detail.

[0013] Chinese Patent Application No. 109504416 relates to the technology of producing coal-based needle coke from a kerosene mixture. This document describes coal-based needle coke with a D50 between 20 - 50 mm.

[0014] British Patent No. 866,859 relates to a method for producing petroleum coke suitable for conversion to graphite for use in nuclear reactors and includes treating a hydrocarbon material composed of petroleum distillates by physical treatment and / or chemical reaction with oxygen at a temperature of 175 to 400 °C and subjecting the resulting product to thermal cracking treatment under conditions for forming petroleum coke.

[0015] Burgess & Schobert (Energeia Vol. 19, No. 1, 2008) described a process for producing jet fuel and high-quality carbon by the delayed coking of a blend of ultra-clean seam coal and decant oil. Due to excessive iron and silicon content, the quality of the sponge coke produced was insufficient to meet the specifications for anodes in aluminum smelting.

[0016] The present invention solves the problems existing in the prior art, especially in reducing the further accumulation of waste fines as a by-product of the coal mining industry and improving the throughput of the delayed coker by providing alternative raw materials outside the refinery. Summary of the Invention

[0017] The present invention relates to adding a purified coal product (PCP, a form of fine coal) to conventional and unconventional coker feeds, which can be introduced by blending with a hydrocarbon liquid component prior to thermal pretreatment in a delayed coker, a fluid coker, or a flexi coker. Such blends can be produced from the fractionated material of the coal-based feedstock and petroleum coke (Pet-coke) at the cracking temperature in a preheater and a coking drum. By doing so, the utilization rate of the delayed coker, fluid coker, or flexi coker can be significantly increased by providing alternative raw materials outside the refinery, and the flexibility of refinery operations can be improved by releasing residues for other uses.

[0018] The inventors have developed a method that provides for the use of very high-quality (low ash, sulfur, and water content) purified coal products (PCP) purified from coal tailing ponds, impoundments, or tips and waste from current coal production processes (such as thickener underflow or tailings underflow waste streams), as well as high-ash, low-quality coal seams that have hitherto been uneconomical to mine, or in mining coal production operations in the following exemplary non-limiting applications: blending with a hydrocarbon liquid component prior to thermal pretreatment in a delayed coker to obtain coke and valuable volatiles, such as residual oil, during the delayed coking process.

[0019] The first aspect of the present invention provides a method for producing coke, comprising the following steps:

[0020] (i) Provide a purified coal product (PCP), wherein the PCP is in particulate form and wherein at least about 90 volume % (%)v of the particles have a diameter not greater than about 75 μm; wherein the PCP has an ash content of less than about 10 %m and a water content of less than about 5 %m;

[0021] (ii) Combine the PCP with an oil to produce a combined solid-liquid blend, wherein the solid-liquid blend comprises at least about 0.1 %m and at most about 30 %m of the PCP;

[0022] (iii) Subject the solid-liquid blend to a temperature in excess of 375 °C for a time sufficient to cause cracking of at least 1 % of the PCP particles to produce one or more volatile distillate products, and

[0023] (iv) Produce coke from the product of step (iii).

[0024] A variety of conventional coking processes can be used to implement aspects and embodiments of the present invention, including delayed coking, fluid coking, and flexi-coking. Some embodiments of the present invention are described below with reference to the delayed coking process, but the same considerations generally also apply to the other coking processes mentioned.

[0025] In a specific embodiment of the present invention, at least about 90 volume % (%)v of the PCP particles have a diameter not greater than about 50 μm; optionally, not greater than about 20 μm. Generally, the ash content of the PCP is less than about 2 %m, suitably less than about 1.5 %m; optionally not exceeding 1 %m. Suitably, the PCP has a water content of less than about 2 %m.

[0026] In an embodiment of the present invention, the oil comprises one or more of the following: residues from atmospheric distillation of a refinery crude oil feedstock; residues from vacuum distillation of a refinery crude oil feedstock; slurry oil from a catalytic cracker; bottoms from a naphtha cracker; oils produced by pyrolysis of coal, plastics, wood, and biomass; black liquor from the kraft process for pulp manufacture; light and heavy cycle oils; light and heavy hydrocarbon gases; diesel fuel; fuel oil; bunker oil; boiler fuel oil; marine fuel oil; marine diesel; biodiesel; waste oil; oils derived from tar sands; fluid catalytic cracking (FCC) decant oil; crude oil; topped crude oil; synthetic crude oil (such as that produced in Canada); any derivative of crude oil; and low-viscosity oils from biofuel manufacture.

[0027] According to yet another embodiment, the solid-liquid blend of (iii) is used as a feedstock in a delayed coker in step (iv). Optionally, the feedstock can be preheated before being introduced into the coker fired heater via heat exchange with other suitable streams. Suitably, the feedstock is introduced into the drum of the delayed coker. Typically, the feedstock is heated to a temperature of at least 450 °C, for example in a fired heater. Optionally, step (iii) further includes a fractionation step. In a specific embodiment, the method further includes a step of calcining the coke of step (iv) to produce calcined coke.

[0028] A second aspect of the invention provides a method for operating a delayed, fluid or flexible coker, comprising carrying out the method as described herein in a delayed, fluid or flexible coker.

[0029] A third aspect provides a coke product obtainable by the method as described herein. Suitably, the coke is prepared from a solid-liquid blend comprising at least about 5% m and at most about 30% m PCP, optionally at least about 10% m and at most about 20% m PCP. In one embodiment, the coke is prepared from a solid-liquid blend comprising vacuum residue or fluid catalytic cracking (FCC) decant oil. Suitably, the coke is selected from: fuel grade coke; anode grade coke; needle coke; and cell coke.

[0030] A fourth aspect of the invention provides a calcined coke product obtainable by the method as described herein.

[0031] A fifth aspect of the invention provides a carbon anode comprising the calcined coke product as described herein.

[0032] A sixth aspect of the invention provides a distillate hydrocarbon liquid product obtainable by the method as described herein.

[0033] A seventh aspect of the invention provides a method for increasing the yield of liquid volatile fractions during a delayed coking process, comprising adding a purified coal product (PCP) to a liquid oil feed stream, wherein the PCP is in particulate form and wherein at least about 90 volume % (%) v of the particles have a diameter not greater than about 75 μm; and wherein the PCP has an ash content of less than about 10% m and a water content of less than about 5% m.

[0034] The eighth aspect of the present invention provides the use of purified coal product (PCP), wherein the PCP is in particulate form and wherein at least about 90 volume % (%) v of the particles have a diameter not greater than about 75 μm; wherein the PCP has an ash content of less than about 10% m and a water content of less than about 5% m as an additive in a delayed coking process to increase the proportion of liquid volatile products produced by the process. In one embodiment of the present invention, the use results in a decrease in the proportion of gaseous volatile products from the delayed coking process. In another embodiment, the use results in the conversion of gaseous volatile products from the delayed coking process into liquid volatile products.

[0035] It should be understood that the present invention may be subject to additional combinations of features disclosed herein but not explicitly recited above. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is further illustrated by reference to the accompanying drawings, in which:

[0037] Figure 1 is a schematic diagram of a delayed coker;

[0038] Figure 2 shows a schematic diagram of a small coking unit;

[0039] Figure 3 shows photographs of coke produced during delayed coking using three feedstocks: (a) PCP derived only from coal from Kentucky, USA (Coal 7); (b) only vacuum residue (RF-D); and (c) a mixture of 80% RF-D and 20% Coal 7 PCP;

[0040] Figure 4 shows a graph of the conversion of Coal 4 PCP to volatiles in a micro-coking apparatus over a certain temperature range;

[0041] Figure 5 shows a graph of the conversion of Coal 4 PCP combined with residual fuel oil to volatiles in a micro-coking apparatus over a certain temperature range;

[0042] Figure 6 shows a graph of the conversion of Coal 4 PCP combined with decant oil to volatiles at a temperature of 460 °C in a micro-coking apparatus; DETAILED DESCRIPTION

[0043] All references cited herein are incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0044] Before elaborating on the present invention in more detail, a number of definitions are provided that will assist in understanding the present invention.

[0045] As used herein, the term "comprising" means that any element set forth must be included and other elements may optionally be included. "Consisting essentially of" means that any element set forth must be included, elements that would materially affect the basic and novel characteristics of the listed elements are excluded, and other elements may optionally be included. "Consisting of" means that all elements other than those listed are excluded. Embodiments defined by each of these terms are within the scope of the present invention.

[0046] The term "coal" is used herein to denote solid hydrocarbonaceous materials derived from sedimentary minerals that are combustible, including but not limited to hard coals such as anthracite; bituminous coal; sub-bituminous coal; and brown coal, including lignite (as defined in ISO 11760:2005). "Natural" or "run-of-mine" coal refers to coal that has not undergone extensive processing and whose physical composition (e.g., coal quality content) has not been materially changed from the perspective of extraction. In contrast, the terms "purified coal product (PCP)", "coal-derived product", "coal substitute product", and "purified coal composition" are used herein to refer to various coals that have undergone one or more processes resulting in changes to the physical and / or chemical composition of the coal, thereby causing significant changes from the point of extraction (i.e., the natural state).

[0047] Petroleum coke (Pet coke or Pet-coke) is a solid by-product of the petroleum refining process. Typically formed using the delayed coking process, it is classified as fuel-grade petroleum coke or anode-grade petroleum coke. Fuel-grade petroleum coke accounts for more than three-quarters of global production and is used as a clean fuel in power plants, cement kilns, and the steel industry. Anode-grade petroleum coke (raw petcoke (RPC), green pet coke (GPC), or uncalcined petroleum coke) is used as a calcining feedstock to produce calcined petroleum coke (CPC). CPC is used in the aluminum, graphite electrode (e.g., for manufacturing lithium batteries), steel, and titanium dioxide industries. Generally, the properties of petroleum coke can vary widely depending on the chemical composition of the petroleum feedstock used to produce it. Thus, petroleum coke can be hard or relatively soft; physically, petroleum coke can resemble highly porous rock, or it can resemble small marbles, ranging in size from a grain of sand to a large pebble. Embodiments of the present invention advantageously reduce the variability of petroleum coke properties by replacing a portion of the oil feedstock with highly refined purified coal products.

[0048] As used herein, the term "ash" refers to the inorganic - e.g., non - hydrocarbon - mineral components found in most types of fossil fuels, especially in coal. Ash is included within the solid residue remaining after coal combustion, which is sometimes also referred to as fly ash. Since the sources and types of coal vary widely, so do the composition and chemistry of ash. However, typical ash content contains several oxides such as silica, calcium oxide, iron(III) oxide, and alumina. Depending on its source, coal may further contain one or more substances in trace amounts that can be included in the subsequent ash, such as arsenic, beryllium, boron, cadmium, chromium, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium.

[0049] As used herein, the term "low - ash coal" refers to natural coal with a lower proportion of ash - forming components compared to other industry - standard coals. Typically, low - ash natural coal or raw coal will contain no more than about 12% m ash. The term "de - ashed coal" or related term "demineralized coal" is used herein to refer to coal with a reduced proportion of inorganic minerals compared to its natural state. Ash content can be determined by proximate analysis of the coal composition as described in standard test methods such as ASTM D3174–12 Standard Test Method for Ash in Analyzed Samples of Coal and Coke from Coal. Ultra - low - ash coal is rare and correspondingly expensive, with an ash content typically less than 8% m of ash.

[0050] As used herein, the term "coal powder" refers to coal in particulate form, with a maximum particle size typically less than 1.0 mm. The term "ultrafine coal" or "ultrafine pulverized coal" or "ultrafine powder" refers to coal with a maximum particle size typically less than 0.5 mm (500 micrometers (μm), approximately 0.02 inches). The term "fine coal" or "fine pulverized coal" or "fine powder" refers to coal with a maximum particle size typically less than 20 μm.

[0051] As used herein, the term "water content" refers to the total amount of water within a sample and is expressed as a concentration or mass percentage (m%). When the term refers to the water content in a coal sample, it includes the inherent or residual water content of the coal, as well as any water or moisture absorbed from the environment. As used herein, the term "de - watered coal" refers to coal with a lower proportion of absolute water than its natural state. The term "de - watered coal" can also be used to refer to coal with a low proportion of naturally occurring water. Water content can be determined by analysis of natural or purified coal compositions as described in standard test methods such as ASTM D3302 / D3302M–17 Standard Test Method for Total Moisture in Coal. Coal considered to be de - watered typically contains no more than 10% m water, usually no more than 5% m water, and optionally less than 2% m water.

[0052] As used herein, the term "hydrocarbonaceous material" means: a material containing hydrocarbons; a hydrocarbon which is an organic compound consisting essentially of the elements hydrogen and carbon. Hydrocarbonaceous materials can include aliphatic as well as aromatic hydrocarbons. Hydrocarbonaceous materials of mineral origin may also contain one or more heteroatoms such as nitrogen, oxygen or sulfur.

[0053] The term "fractionation" is used herein to refer to the separation of a mixture into different parts. The term "fractionation" will include a separation process in which a quantity of a mixture (gas, solid, liquid or suspension) is separated into a number of smaller quantities (fractions) during a phase change, where the composition varies according to a gradient. Fractionation includes "fractional distillation", which separates a mixture into its components, or fractions, based on differences in their boiling points. Any distillation output from a fractionation technique can be referred to as a "fractionation product". The viscous residue from atmospheric fractionation can be used as a feedstock for further upgrading by vacuum distillation, as a fuel component, or for the asphalt fraction. The fractionation or fractionation product has a reduced composition, or is purer than the crude product from which it is derived. Typically, the atmospheric distillation of crude oil is carried out at a temperature of about 300 to about 350 °C at or near atmospheric pressure. The atmospheric residue can then be fed into a vacuum distillation unit which operates at a vacuum of about 350 °C and about 40 mmHg (about 53 mbar).

[0054] Coal mines, particularly multi-seam open-pit mines and associated coal processing and preparation plants, are limited in terms of output and market pricing by the availability of high-grade quality seams required to meet the high specifications for coking coal and pulverized coal injection (PCI) coal. From the perspective of the rapidly diminishing global resource base, these limitations result in reduced production and inefficiencies in this important chemical feedstock. More stringent product specifications for internationally traded thermal coal also lead to reduced production and efficiency in the coal industry. Due to increasingly high environmental standards, the ability of coal processing plants to store waste coal products in tailings ponds, reservoirs or dumpsites is also increasingly limited.

[0055] Thermal coal sold and traded internationally for power generation is typically of high ash content (at least 15 - 20 m% dry basis), high sulfur content (1 - 2 m% dry basis), moderately high water content (10 - 15 m% or higher), and has a relatively coarse particle size distribution (< 50 mm). Coal-fired power plant boilers utilize pulverized PCI fuel (i.e., dried coal particles, typically in the size range of 20 - 120 microns), and consume significant amounts of energy in crushing, drying and pulverizing thermal coal. The ash generated during combustion must be removed in the form of slag ash or fly ash: in both cases, the ash reduces operating efficiency and incurs environmental and commercial costs for disposal. Power stations utilize flue gas desulfurization technology to minimize the emission of sulfur oxides to the atmosphere; the cost of operating this desulfurization technology is proportional to the sulfur content of the coal feedstock.

[0056] Coal seams with high ash content are abundant worldwide and, in terms of various geological reserves, sometimes occur as thick seams that persist over a wide geographical area. However, due to the aforementioned problems, many seams are not economically exploitable.

[0057] When the residue from a refinery is insufficient to operate a delayed coker at full capacity, additional components can be introduced to increase production and operating efficiency. The present invention relates to adding fine coal to conventional and unconventional coker feeds, which can be introduced by blending with hydrocarbon liquid components prior to thermal pretreatment in a delayed coker or a flexible coker. Such blends can be produced from a coal-based feedstock of distillate materials and petroleum coke formed at cracking temperatures in a preheater and a coking drum. By doing so, the production of a delayed coker or a flexible coker can be increased by providing an alternative feedstock external to the refinery, and the flexibility of refinery operations can be enhanced by freeing up residue for other uses.

[0058] The residual oil in the context of this application should be understood to refer to the residue obtained after at least one refinery stage, such as the residue from the atmospheric and vacuum distillation of a refinery from a crude oil feedstock; residues from other refinery processes, such as the slurry from a fluid catalytic cracker and / or the bottoms from a naphtha cracker (carbon black feedstock); waste oil; decant oil; oils and tars produced by the pyrolysis of coal (such as coal tar pitch), wood, and biomass; black liquor, a waste product from the kraft process for making wood pulp; low-viscosity oils from a refinery (such as recycle oil, refinery gas, etc.). The residual oil can also be a lower-viscosity oil from biofuel production (such as fatty acid methyl ester) used to pre-blend fine coal into a paste prior to mixing with any of the aforementioned hydrocarbon liquid materials.

[0059] It was previously unknown that co-distilling heavy hydrocarbon liquids such as residual oil with coal powder, especially coal powder containing micron-sized and nanometer-sized coal particles, would provide large amounts of high-quality coke at temperatures around 450 °C or above 450 °C. These amounts are in addition to the amounts attributable to the distillation of the hydrocarbon liquid component alone and are thus attributable to the presence of the solid material.

[0060] Without wishing to be bound by theory, it should be understood that when coal powder is distilled as a blend with residual oil, any coal tar and liquid produced during pyrolysis condense together with the conventional fractions from the residual oil. In addition, the various hydrocarbon substances present in the residual oil can act as hydrogen donors to facilitate the decomposition of the coal polymer structure and can promote the production of condensable hydrocarbon fractions. Using existing process equipment can avoid large-scale investment in major new manufacturing facilities and plants. This represents a significant economic advantage of the present invention.

[0061] According to an embodiment of the present invention, there is provided a method of pyrolyzing and distilling residual oil mixed with pulverized coal of any specification to produce a distillate product and coke. A specific embodiment of the present invention relates to the pyrolysis and distillation of residual oil blended with pulverized coal, where the pulverized coal has specifications, particularly water content and ash content, which after distillation provide a distillate product that meets suitable product and environmental emission standards. A distillate product that meets or exceeds the specifications for the product type has a higher value, thus making the overall process as described herein highly commercially viable.

[0062] Recent developments in pulverized coal processing provide a fine coal product, PCP, which has a low water content (<15% m, typically <7% m, suitably <3% m) and a low ash content (<10% m, typically <5% m, suitably <2%). The demineralization process of PCP also has a beneficial effect on the sulfur content by removing pyrite. The demineralization and dehydration of pulverized coal are typically achieved by combining foam flotation separation (designed specifically for ultrafine and fine particles) with mechanical and thermal dehydration techniques. A typical process for producing dehydrated ultrafine coal is provided in US-2015 / 0184099, which describes a vibration-assisted vacuum dehydration process. However, it should be understood that there are also several other suitable dehydration methods in the art, for example, providing coal as a cake that contains fine coal particles in a hydrocarbon carrier, where the water has been removed by using one or more hydrophilic solvents.

[0063] Pulverized coal of any particle size suitable for distillation with residual oil is considered to be included in the present invention. Suitably, the particle size of the pulverized coal is in the ultrafine range. Most suitably, the particle size of the pulverized coal is in the fine range. Specifically, the maximum average particle size can be at most 500 μm. More suitably, the maximum particle size can be at most 300 μm, 250 μm, 200 μm, 150 μm, or 100 μm. Most suitably, the maximum average particle size can be at most 75 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, or 5 μm. The minimum particle size can be 0.01 μm, 0.1 μm, 0.5 μm, 1 μm, 2 μm, or 5 μm. Thus, in a specific embodiment, the present invention includes the use of nanoscale pulverized coal with an average particle size in the submicron range.

[0064] An alternative measure of particle size is a percentage value or "d" value that refers to the maximum particle size and the proportion of the volume of particles below that size within the sample. For the present invention, pulverized coal of any particle size suitable for distillation with crude oil is considered to be included in the present invention. Suitably, the particle size of the pulverized coal is in the ultrafine range. Most suitably, the particle size of the pulverized coal is in the fine range. Specifically, the maximum particle size can be at most 500 μm. More suitably, the maximum particle size can be at most 300 μm, 250 μm, 200 μm, 150 μm or 100 μm. Most suitably, the maximum particle size can be at most 75 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm or 5 μm. The minimum particle size can be 0.01 μm, 0.1 μm, 0.5 μm, 1 μm, 2 μm or 5 μm. Any "d" value can be associated with any one of these particle sizes. Suitably, the "d" value associated with any of the above maximum particle sizes can be d99, d98, d95, d90, d80, d70, d60 or d50. In order to maximize the reaction of coal during the delayed coking process, it is desirable for the coal particle size to be both relatively uniform and small so that the small particles can be well dispersed in the residual oil phase. For example, in a specific embodiment of the present invention, the d90 of the fine pulverized coal is <100 μm, <90 μm, <70 μm, <50 μm, optionally <20 μm. Suitably, the d99 of the fine pulverized coal is <70 μm, <60 μm, <50 μm, <40 μm, optionally <20 μm.

[0065] According to a specific embodiment of the present invention, there is provided a method of mixing (i.e., suspending) the solid particulate matter of dehydrated and demineralized fine coal in residual oil before pyrolysis and fractionation. When fractionated under reduced pressure, a large amount of coke is produced, which cannot be solved solely by the pyrolysis and distillation of the residual oil components. Therefore, this coke product is derived from the presence of fine and / or ultrafine coal.

[0066] The residual oil can be selected from the group consisting of: residues from atmospheric and vacuum distillation of refineries from crude oil feedstocks; residues from other refinery processes, such as slurry from catalytic crackers and / or bottoms from naphtha crackers (carbon black feedstocks); oils and tars produced by pyrolysis of coal (such as coal tar pitch), wood and biomass; black liquor, waste from the kraft process for making wood pulp; low-viscosity oils from refineries (such as cycle oils, oil gases, etc.). The residual oil can also be a low-viscosity oil, including those oils from biofuel manufacturing (such as fatty acid methyl esters). Before blending with any of the above hydrocarbon liquid materials, the fine coal can be pre-mixed into a paste using any of the above hydrocarbon materials.

[0067] Thus, according to a specific embodiment of the present invention, a residual oil feedstock such as vacuum residue and other process residues as described above is fed to a thermal fractionator (such as a distillation column), where valuable lighter fractions are distilled off. Such lighter fractions may include one or more of the following: heavy oil gas; light oil gas; kerosene; coker naphtha, diesel; gasoline; and gas.

[0068] From there, the heavy bottoms residue from the thermal fractionator is heated in a furnace in the presence of steam to its cracking temperature above 450 °C (suitably about 480 °C) and then fed to one or more coking drums. Without wishing to be bound by theory, it is believed that thermal cracking has started in the feed pipe between the furnace and one or more coking drums and ends in the drum. The addition of steam helps prevent coke deposition in the feed pipe. Further thermal cracking occurs inside the coking drum, and additional distillates and gas are discharged, leaving behind deposited solid coke in the coking drum, which can be recycled and is valuable as a "clean carbon" thermal fuel in metallurgy (such as aluminum, steel, and other metal production). The distillates and gas are returned to the fractionation column or another refining process. Typically, a coking unit will include at least first and second coking drums such that when the first drum is filled with coke, the second drum is steamed to further reduce the hydrocarbon content of the coke and then quenched with water for cooling. After the first drum is filled, the process is switched to the second drum so that the hot mixture from the furnace reaches the second drum for continuous production. A high-pressure decoking derrick may be positioned above one or more coking drums and can be used to deliver high-pressure water to the coking drum to facilitate the removal of coke, which is typically collected from the bottom of the coking drum. This may also be referred to as hydraulic decoking (Petroleum Processing, Vo.5, No.2, 1950) (see Figure 1 ).

[0069] In an embodiment of the present invention, demineralized fine coal (such as PCP) is typically combined with the residual oil feed before heat treatment through the furnace. The fine coal can be added as a powder to the delayed coking system but is suitably mixed with the residual oil feedstock. The PCP produced in the slurry is pumpable. A similar step may occur when using a fluidized bed or a flexible coking unit.

[0070] The amount of fine coal that can be blended with the residual oil is at least 1% m (1 mass percentage), suitably at least 5% m, typically up to about 20% m, optionally up to about 30% and at most 70% m, suitably up to 60% m, optionally up to 50% m. Thus, by mass, the fine coal component can make up the majority of the resulting residual oil or residual oil bottoms blend. This allows for considerable production economy by replacing a large portion of the liquid components with a cheaper solid material. The combined blend can also be introduced into existing equipment and processes without significant re-design of conventional equipment.

[0071] In another embodiment of the present invention, a method for operating a fluid coker or a flexible coker is also provided. A fluidized bed coker generally includes a reactor or coking vessel and a heater vessel. The residual feedstock is sprayed directly as a liquid into the coking reactor where the liquid feedstock is distributed as a thin oil film over the hot fluidized coke particles. When the oil film breaks, it evaporates and is rapidly removed from the coking zone, thus avoiding secondary reactions. During this process, a portion of the removed coke is burned with air to provide heat for the reactor. Thus, the fluid coking process can be operated continuously with a single reactor and a single heater. According to the present invention, the fluid coking process can be adjusted to include one or more of the following steps:

[0072] · As described herein, a preheated feed comprising a combination of residual oil and PCP is sprayed into a bed of hot fluidized petroleum coke particles contained within a first vessel that provides the heat required for thermal cracking.

[0073] · The cracked products are separated from the coke particles and transferred from the first reaction vessel to a fractionator.

[0074] · In a second reaction vessel, a portion of the coke particles are burned to generate heat and a portion of the coke particles are discharged as a coke product.

[0075] · In the case of flexible coking, these hot coke particles are then gasified in a third reaction vessel

[0076] The pre-blending of solid materials with such hydrocarbon liquids to produce a homogeneous, stable mixture as a feedstock is enhanced by using finely divided coal having a particle size below about 20 microns and a moisture content below about 5% m.

[0077] The use of finely divided coal (d90 < 50 microns) having a very low ash content (< 2% m) and low sulfur (< 1% m) enables the resulting coke to meet the specifications of higher value products, such as anode coke. Anode coke is used in the steel and aluminum industries to melt raw materials. Such finely divided coal can be extracted from lignite, sub-bituminous coal, and bituminous coal of any geological age or origin, which is quite advantageous. In addition, in certain embodiments, it can be derived from low-grade coal that, prior to demineralization, was considered to have little or no commercial value, let alone be upgraded to a component of anode-grade petroleum coke.

[0078] The present invention facilitates the use and upgrading of fine coal into higher value volatile products such as distillates, as well as the production of petroleum coke. Additionally, conventional equipment that requires little or no additional modification can be used. Such distillate fractions can be distinguished from typical volatile products derived from delayed cokers, fluid cokers, or flexicokers using exclusive residual oil feedstocks, as they can contain elevated oxygen content depending on the chemical composition of the original coal source. As demonstrated in the examples below, PCP from coals with higher volatile matter content can contribute significantly to the liquid distillate fraction. The inventors have surprisingly found that PCP can assist in the transfer from lower value gaseous products typically produced during residual oil coking to higher value liquid fractions. Thus, PCP can be used as an additive (possibly at a lower %m concentration) in conventional coking processes to facilitate and / or increase the production of liquid fractions and correspondingly reduce the production of gaseous fractions (such as carbon dioxide, fuel gas, liquefied petroleum gas).

[0079] The particle size and particle size distribution of the fine coal are selected to enable the stable dispersion of the coal in hydrocarbon liquids, thereby allowing the mixture to be transported to the coking facility through a simple supply chain.

[0080] The synergistic interaction between the fine coal and the residual oil feedstock / fractionator residue results in unexpected beneficial changes in the composition of the recovered high value fractions. Additionally, the high surface area generated by the fine coal particles aids in the uniform reaction with the residual fuel, resulting in a homogeneous product with improved morphology.

[0081] The fine coal improves the economic performance of the refinery coker by increasing the utilization of excess coking plant capacity. Additionally, the produced petroleum coke has very low sulfur, nickel, and vanadium, thus increasing the commercial value of the petroleum coke as a premium manufacturing ingredient for steel, aluminum, and other metal alloys.

[0082] In an embodiment of the present invention, the coke prepared according to the method may be subjected to one or more additional calcination steps to produce a calcined coke product. Calcined coke is used in a variety of industries and applications; in particular, it is a valuable material for the production of carbon anodes as well as for the manufacture of titanium dioxide. The coke produced by the method can be calcined in a rotary kiln, where the coke is heated to a temperature between 1200 and 1350 °C (2192 and 2460 °F). The high temperature heat treatment removes any excess moisture, extracts all remaining hydrocarbons, and alters the crystal structure of the coke, resulting in a dense, conductive product.

[0083] The present invention is further illustrated by the following non-limiting examples:

[0084] Examples

[0085] The demineralization and dehydration of coal fines can be achieved by combining foam flotation separation specifically designed for ultrafine and fine particles with mechanical and thermal dehydration techniques.

[0086] In all embodiments, a purified coal product containing demineralized and dehydrated fine coal is used as a coal substitute product. The purified coal product (PCP) can be prepared by a multi-step process as described below:

[0087] · Obtain a representative sample of a coal waste slurry derived from a reservoir, a tailings pond, or a tailings underflow, such as a medium volatile bituminous coal A from Queensland.

[0088] · Then reduce the sampled material to a particle size of d80 = 30 - 50 microns (or finer in some coals) to achieve effective separation to a target ash content of 5 - 8%. To achieve this, the feed is diluted with water to a solids content in the range of 20 - 40%, and then ground in a ball mill or a bead mill depending on the top size of the feed. The product is screened in the size range of approximately 100 microns. In some cases, a dispersant additive (such as a lignin-based dispersant, e.g., Borresperse, Ultrazine, and Vanisperse manufactured by Borregaard, 1701 Sarpsborg, Norway) is included to optimize energy use. Suitable equipment is manufactured by: Metso Corporation, Fabianinkatu 9A, PO Box 1220, FI-00130 Helsinki, FIN-00101, Finland; Glencore Technology Pty. Ltd., Level 10, 160 Ann St, Brisbane QLD 4000, Australia; and FLSmidth, Vigerslev Allé 77, 2500 Valby, Denmark.

[0089] · Typically, one stage of flotation (one roughening step and multiple cleaning steps) is performed to reduce the ash content to the target level. For some coals where the mineral matter is mainly dispersed in the sub-10 micron size domain, more than one flotation stage may be required after further milling.

[0090] ·Typically, the coal slurry is further diluted with water to a solids range of 5 - 20 m%, then collected in a tank, and a froth flotation agent called a frother (e.g., methyl isobutyl carbinol and pine oil) and a collector (e.g., diesel fuel or other hydrocarbon oils and Nasmin AP7 from Nasaco International Co., Petite Rue 3, 1304 Cossonay, Switzerland) are added using a controlled dosing rate. A microparticle separator (e.g., a flotation testing machine manufactured by FLSmidth, Vigerslev Allé 77, 2500 Valby, Denmark; Metso, Fabianinkatu 9, FI - 00130 Helsinki, Finland (post box 1220); and GTEK Mineral Technologies Co., Ltd.) is filled with process water, and filtered air from an enclosed air compressor is used to separate the hydrophobic carbonaceous material from the hydrophilic mineral material. The foam containing hydrocarbon particles overflows the tank, and this foam is collected in an open top trough. The mineral slurry is retained in the separation tank before discharge, while the de - mineralized coal slurry is degassed and then pumped to the granulation step.

[0091] ·Then, depending on the actual particle size under pressure or vacuum, sometimes with blowing, the concentrate from foam flotation is de - watered to a target range of 20 - 50 m% using a filter press or a tube press to mechanically remove water to produce a feed for the extruder. Suitable filter press equipment is manufactured by Metso, Helsinki, Finland FI - 00130; FLSmidth, Valby, Denmark; and Outotec, Rauhalanpuisto 9, 02230 Espoo, Finland.

[0092] o In some instances, a flocculant (or thickener, e.g., an anionic polyacrylamide additive manufactured by Nalco Champion, 1 Ecolab Place, St. Paul, MN 55102 - 2233, USA) is added to optimize the settling properties and the underflow density. To optimize the procedure, settling tests are performed to measure the settling rate and generate a settling curve, tracking the underflow density over time.

[0093] o Filtration may also be required, depending on the filtration rate and the resulting cake moisture. To optimize the percent of solids fed to the process (thickened / unthickened), the feed viscosity, pH, and filtration pressure will be measured, and the filter cloth will be selected after evaluating cake discharge and blinding performance. The suitable filter cloth is manufactured by Clear Edge Filtration, 11607 E 43rd Street North, Tulsa, Oklahoma 74116 USA.

[0094] o In some cases, a decanter centrifuge can be incorporated into the process design to concentrate the solids content prior to the filter press. The suitable equipment is manufactured by AlfaLaval Corporate AB, 1, SE - 226 55 Lund, Sweden. 1, SE - 226 55 Lund, Sweden.

[0095] · If needed, an extruder or granulator or briquetting machine can be used to pelletize the wet cake of fine coal to provide mechanical integrity and transportability. However, as described in the following examples, PCP is typically used in micronized form for the production of petroleum coke.

[0096] Example 1 - PCP Blend Characteristics are Compatible with Petroleum Coke Specifications

[0097] Table 1 shows the specifications of three different grades of petroleum coke, which are affected by the inclusion of PCP as a blending component. Also given are the values of each property for two types of PCP (designated "Arq Fuel A" and "Arq Fuel B") and the contribution of 10% of each PCP to each property.

[0098] Table 1 shows the maximum negative impact of PCP on coke properties, as the calculation assumes that all heteroatoms (O, N, S, O) and all inorganic matter will report to the coke fraction. In reality, each of these elements is partitioned between the solid and volatile (gas and liquid) products, thus reducing the net content in the product coke. Finally, during the calcination of the coke, additional heteroatoms are expected to be removed, whether derived from the pitch or from the PCP or from blends of these feeds.

[0099] The nitrogen content requirement for calcined needle coke is very low. Although nitrogen will mainly disproportionate into liquid and gaseous products (such as ammonia) during the pyrolysis of PCP, for a specific needle coke application, blends containing only 1% Arq Fuel A may still be unacceptable. However, nitrogen is one of the heteroatoms that will be distributed between the coke product stream and the liquid product stream. Some nitrogen is even reported as a gaseous product stream as ammonia. All these distributions are used to reduce the nitrogen value in the coke. At a nitrogen content of 17,000 ppm, an Arq Fuel A concentration of up to 45% can be easily used for fuel coke applications. The nitrogen content is not a specification parameter for anode coke.

[0100] Ash content: At an ash content of only 1.0% m, 30 - 40% of Arq Fuel A can be accommodated for fuel coke and calcined anode coke, and similarly, 60 - 80% of Arq Fuel B can be accommodated. This represents the potential to replace most of the residue feedstock with PCP during the delayed coking process.

[0101] Sulfur content: At a sulfur content of 0.8% m, the sulfur concentration in Arq Fuel A is lower than the specified concentration for fuel coke and anode coke, so the sulfur content does not limit the blending concentration of Arq Fuel in these two coke grades. The sulfur content of needle coke is low, but depending on the exact sulfur specification limit, 25% - 60% m of Arq Fuel A (or 50% - 100% of Arq Fuel B) can be accommodated. Similarly, this represents the potential to replace most of the residue feedstock with PCP during the delayed coking process.

[0102] Nickel and vanadium content: The concentrations of nickel and vanadium in Arq Fuel A are lower than the specified levels, so neither of these two elements limits the concentration of Arq Fuel that can be blended to meet any of the three coke specifications.

[0103] The Arq Fuel blending properties meet the petroleum coke specifications at least for fuel coke and anode coke. Ignoring any operating limitations, concentrations of up to 70% m and up to 80% m of Arq Fuel B can be accommodated in fuel coke and anode coke, respectively, without exceeding the specification limits.

[0104] Table 1. Specifications of three grades of petroleum coke and two types of PCP (Arq Fuel)

[0105]

[0106] Example 2 – Blending waste-derived PCP with residue oil.

[0107] To achieve good dispersion, the PCP must first be finely ground. An average (D50) particle size of about 5 microns and a maximum particle size of about 10 microns (d99) provide excellent performance.

[0108] Dispersing this powder into vacuum residue or residual fuel oil requires high-shear mixing. The type of mixing found in rotor / stator equipment, such as those manufactured by Silverson or KADY International, is particularly useful in obtaining a homogeneous, well-dispersed slurry, although other types of mechanical and static mixers can be used. Depending on the physical and chemical properties of the coal and oil, good dispersion may only require passing through such equipment once, or may require repeated recirculation.

[0109] High-shear mixing is preferably carried out at a temperature where the viscosity of the oil phase is less than 500 cSt, suitably less than 100 cSt. This viscosity ensures that the coal particles have sufficient mobility to be enveloped by the oil and that the oil penetrates into at least some of the pores within the coal particles. Thus, both the "external" and "internal" surface areas of the coal particles are in contact with the oil phase.

[0110] Once prepared, the slurry should be kept well-dispersed before introduction into the coker. Depending on the oil viscosity at the storage temperature, this may require continuous stirring, intermittent mixing, or no mixing.

[0111] Example 3. – Compatibility of PCP blend properties with delayed coker feed specifications.

[0112] Table 2 shows a set of typical coker feedstock specifications for US refineries. Each property value is given for PCP (Arq Fuel A), four residual fuels (RF-A, B, C, and E, plus a single vacuum residue (RF-D)) and 10% m ArqFuel blends in each residual fuel.

[0113] Table 2. Comparison of key coker feed specification parameters with values for 10% m PCP (Arq Fuel) / residual fuel blends

[0114]

[0115] Surprisingly, the sulfur content (for all five RF-AE), flash point (RF-A, B, C, and E), vanadium content (more typical high-vanadium RFO samples: RF-C, D, and E), and TAN (RF-E) are actually improved by blending with Arq Fuel.

[0116] The viscosity at 50 °C and pour point increase upon addition of PCP, but in the blends of 10% of RF-A, B, C, and D, these two parameters are still well below the specification limits of 1160 cSt and 110 °F (43.3 °C).

[0117] Adding Arq Fuel increases the ash and water content, but not significantly, and in all 10% blends shown, both are well below the specification limits of 0.24% m and 0.5% m respectively. This indicates that the blends can accommodate additional Arq Fuel without exceeding the defined limits. Additionally, if the mixing temperature of the oil and Arq Fuel is higher than about 100 °C, at least a portion of the water in the mixture will be released as vapor.

[0118] The Conradson carbon residue / asphaltene ratio and total nitrogen content also increase by adding Arq Fuel, but are still well below the specification limits of 1.8 (10% RF-C blend) and 10,000 ppm, w (10% RF-A blend).

[0119] Example 4. - Production of volatiles from different types of fine coal under delayed coking temperature - time conditions.

[0120] The best time - temperature curve (heating rate of 20 °C / min up to 460 °C and then isothermal at 460 °C) was developed to best represent the delayed coking conditions for a 3 mg PCP sample using a standard thermogravimetric analyzer (TGA). The amount of volatile loss and residue were determined for 13 different ranks (sub - bituminous to medium volatile bituminous), coal quality compositions, and geographical / geological sources of coal.

[0121] Table 3. Details of the test coals and TGA results

[0122]

[0123] The yield of volatile components (combined liquid and gas) ranges from 12% m for a higher - rank coal to almost 50% m for the lowest - rank coal, demonstrating that PCP can produce significant amounts of volatiles (such as Arq Fuel) under delayed coking conditions.

[0124] Example 5. Production of volatiles from blends of vacuum residue and residual fuel oil with fine coal.

[0125] Three different types of residual fuel oils (RF-C, F, and G, Table 2) and one vacuum residue (RF-D) oil were combined with PCP (Arq Fuel) prepared from coal 7 to form 20% Arq Fuel and 80% oil. Table 4 gives the amount of volatiles boiling above 580 °C, determined for each oil in column 2 by simulated distillation (SIMDIS, ASTM D2887). The volatiles produced by these oils individually under the above TGA coking conditions are shown in column 3. These tests were repeated at least 5 times to create a data set with a standard deviation of less than 1%. The data shown are the mean values calculated from this data set. The volatiles produced from Arq Fuel and 20% / 80% Arq Fuel / RF blends under delayed coking TGA are given in columns 5 and 7, respectively, and the standard deviation of the latter determination is given in column 9.

[0126] Table 4. Comparison of Delayed Coker TGA Volatile Yields (a) Determined Directly on 80% Arq Fuel 20% Residual Oil Blends and (b) Calculated from Individual Components.

[0127]

[0128] 1. Mean Yields at TGA 460 °C Isotherm

[0129] det. = determined, calc. = calculated

[0130] By scaling the individual oil TGA data (column 4) and the individual coal TGA data (column 6), the expected volatile yields for the 20% / 80% blends (column 8) can be calculated as a weighted average of the volatiles from the individual components. Surprisingly, in three of the four cases, the actual volatile production was higher than predicted: the differences between the determined and calculated values are shown in column 10. If the incremental volatile production is attributed to the presence of coal, then the conversion of coal to volatiles can be calculated as shown in column 11.

[0131] Example 6. - Production of Liquids from Residual Fuel Oils and Blends of Residual Fuel Oils with PCP (ArqFuel) in a Custom-Built Miniature Coking Unit.

[0132] To further simulate the reaction of Arq Fuel and slurry in a refinery delayed coker, a laboratory-scale version of the coking drum was constructed as Figure 2 shown.

[0133] The coking drum is electrically heated externally, nitrogen purge is provided to assist in removing the cracked hydrocarbon products from the coking drum (simulating steam purge in commercial cokers), and a series of cold traps are employed to condense and capture the liquid products. Different from the TGA experiment, the micro-coker can determine the yields of gases and liquids, not just volatiles, as well as the yield of petroleum coke. In addition, sufficient products are generated to allow for the analysis of product quality.

[0134] The experiments were conducted with individual oils and a mixture of 80 wt% oil and 20 wt% coal. Each experiment was repeated at least 3 times to ensure that the standard deviation was less than 1%.

[0135] Table 5. Yields and properties of coke and liquids from residual fuel D, coal 7 (see Table 3), and a 20% coal 7 blend in RF-D prepared in the micro-coking unit at 460 °C for two hours.

[0136]

[0137] Blending 20% PCP (Arq Fuel, coal 7) with the fuel residue RF-D increased the coke yield from 21.3% m to 32.4% m and decreased the liquid yield from 62.5% m to 53.8% m (Table 5). Calculation of the relative contributions of the two blend components showed that coal 7 reacted to produce 77% coke, 19% liquid, and 4% gas. After blending PCP with the residual oil, the yield of the most valuable component, liquid, increased from 11% to 19%, almost doubling the previous yield.

[0138] Compared with the residual fuel, coal has a relatively high oxygen content, and most of the oxygen is only found in the liquid from coal 7, and its aromaticity (low H / C) is also higher than that of RF-D. Surprisingly, the combined product from RF-D and coal 7 is very similar to the product from RF-D alone, and the increase in oxygen in the distillation fractions from the blend is small: -

[0139] · The oxygen increased by only 0.3 wt%,

[0140] · The nitrogen increased by only 0.1 wt%,

[0141] · The H / C decreased slightly from 1.68 to 1.64.

[0142] The 20% blend coke of coal 7 and RF-D has the following differences compared with the coke from RF-D alone: -

[0143] · The sulfur content increased. Sulfur decreased significantly from 4.13% m in RF-D to 2.88% m in the blend.

[0144] · The nickel content increased. Nickel decreased significantly from 295 ppm,w in the blend to 168 ppm,w.

[0145] · The vanadium content increases. Vanadium in the blend significantly decreases from 749 ppm,w to 424 ppm,w

[0146] · The ash content of the coke from the blend increases as expected; in this case, it reaches a level higher than the specification limits of fuel coke and anode coke (0.8% m). The ash content of 0.35% m of the coke from only RF-D is slightly within these petroleum coke ash limits. It is obvious that a slight modification of the blending parameters will be able to produce coke with an ash content lower than 0.2% m. For example, by changing the blend to 10% coal 7 in RF-D, the required ash limit may be met. Alternatively, choosing fuel residues with a lower inherent ash content will result in a higher PCP content in the mixture.

[0147] Visual inspection of the coke products from the small coker runs shows surprising morphological differences (as Figure 3 shown):

[0148] · Coke made only from PCP (Arq Fuel, coal 7) is a fluffy black powder without agglomerating into lumps.

[0149] · Coke made only from RF-D is hard and brittle, with shiny flakes, crumbling to the touch, and seems to be formed on the walls of the microcoker vessel.

[0150] · Coke made from an 80 / 20 blend of RF-D and coal 7 is a porous solid material with high strength. All the fine coal particles are "incorporated" into the lumps, and some "nodules" seem to form at the bottom of the coking vessel.

[0151] Example 7. – Increase the production of liquid volatiles from the blend of fuel residue and PCP from a North American coal (Arq Fuel) with a high volatile content.

[0152] Using the method described previously, the PCP is derived from a North American coal with a high volatile content in West Virginia (coal 2 in Table 3 above). The coal 2 PCP is mixed with RF-D vacuum residue in an 80:20 liquid-solid blend, as in Example 5 (see above). Based on the TGA results (about 30%), a high volatile yield is expected. Surprisingly, the results of the microcoker tests significantly exceeded these expectations, with a liquid volatile yield of about 48%. It should be noted that the data was obtained from the average of three replicate runs using this liquid-solid mixture, with a standard deviation of only about 1%.

[0153] Without wishing to be bound by theory, it appears that a chemical interaction occurs between the PCP and the oil, which may contribute to an increased observed liquid yield compared to predictions based independently on TGA analysis of solid PCP and the residual oil. This may indicate that the coal-derived components interact with the gaseous products from the oil, resulting in a preferential conversion from low-value gas products to significantly higher-value liquid products. This observation enables the benefits of the present invention to be extended to a range of similar coals (including rejects and wastes) with high volatile matter content, which can represent large and commercially available feedstock sources.

[0154] Example 8. – Production of volatiles from residual fuel oil and blends of residual fuel oil with PCP (ArqFuel) in a custom-built micro-coking rig

[0155] The previously described TGA tests were carried out at the milligram level in a micro-coking rig. The micro-coking rig increased the sample size to the gram range. A quantity of either the individual coal (Coal 4 from Table 3), the individual oil, or a blend of 20 wt% coal and 80 wt% oil was loaded into a custom-built 15 ml nickel alloy container equipped with a press-fit lid. The lid had a 1 mm hole to allow the volatiles generated during the experiment to escape. The container was placed in a pre-heated furnace at different temperatures for different times. The percentage of volatiles generated was calculated from the difference between the initial and final weights of the sample. By using the individual oil and blend data, the conversion of coal in the blend could be calculated.

[0156] Each data point was repeated at least 5 times and the standard deviation for each set of data was generally less than 1 percentage point.

[0157] The conversion of Coal 4 over a range of temperatures is as Figure 4 shown. The conversion over a range of temperatures when blended with vacuum residue (RF-E in Table 2) is shown in Figure 5 . The results show a significant increase in the conversion of coal to volatiles, as shown in Figure 5 .

[0158] A similar set of experiments was carried out on a blend of 20 wt% Coal 4 and 80 wt% decant oil (a heavy slurry oil from a catalytic cracker on the US Gulf Coast). The data summarized in Figure 6 again shows a significant increase in the conversion of coal to volatiles when coked in the presence of oil.

[0159] Example 9. – Further improvement in the production of liquid volatiles from blends of fuel residues with PCP from a North American coal (Arq Fuel) with high volatile content.

[0160] A series of similar small-scale coking experiments using coal 4 and the same vacuum residue (RF-D) showed surprising results, including a higher conversion rate of coal to liquid products. The results are summarized in Table 6:

[0161] Table 6 Yields and properties of coke and liquids from residual fuel D, coal 4 (see Table 3), and a 20% coal 7 blend in RF-D prepared in a micro-coking unit at 460 °C for two hours.

[0162]

[0163] From these data, we can calculate the conversion of the coal in the blend to various products. The data show that in the coal / oil blend, the coal portion of the blend produces 58% liquid products, 49% solid products, and -7% gas products. Initially, a negative conversion to gaseous products seems unlikely. However, this indicates that the conversion of some cracking products from the oil, which are normally reported as gas phase, reacts with the cracking products from the coal and forms slightly heavier materials reported as the liquid phase. Without prior hydrotreating of the fuel oil, this level of gas-to-liquid product conversion is completely unexpected and very important because the value of liquid products is generally higher than that of gas products.

[0164] The present invention is further illustrated by the following non-limiting numbered clauses:

[0165] 1. A method for producing coke and one or more volatile products, the method comprising the steps of:

[0166] (i) providing a purified coal product (PCP), wherein the PCP is in particulate form and wherein at least about 90 volume % (%) v of the particles have a diameter not greater than about 100 μm; wherein the PCP has an ash content of less than about 10% m and a water content of less than about 5% m;

[0167] (ii) combining the PCP with a liquid residual oil to produce a combined solid-liquid blend, wherein the solid-liquid blend comprises at least about 0.1% m and at most about 30% m of the PCP;

[0168] (iii) subjecting the solid-liquid blend to a temperature in excess of 375 °C for a sufficient time to cause at least 1% of the PCP particles to crack to produce one or more volatile products, and

[0169] (iv) producing coke from the product of step (iii).

[0170] 2. The method of clause 1, wherein at least about 90 volume % (%) v of the PCP particles have a diameter not greater than about 75 μm; optionally, not greater than about 50 μm.

[0171] 3. The method of clause 1 or 2, wherein the ash content of the PCP is less than about 2% m, suitably less than about 1.5% m; optionally not exceeding 1% m.

[0172] 4. The method of any one of clauses 1 to 3, wherein the PCP has a water content of less than about 2% m.

[0173] 5. The method of any one of clauses 1 to 4, wherein the residual oil comprises one or more of the following: residues from the atmospheric distillation of a refinery from a crude oil feedstock; residues from the vacuum distillation of a crude oil feedstock; slurry from a catalytic cracker; bottoms from a naphtha cracker; oils produced by the pyrolysis of plastics, wood, and biomass; black liquor from the kraft process for making wood pulp; light and heavy cycle oils; light and heavy gas oils; diesel fuel; fuel oil; bunker oil; boiler fuel oil; decant oil; marine fuel oil; marine diesel; biodiesel; waste oil; oils derived from tar sands; crude oil; synthetic crude oil; and oils from the production of biofuels.

[0174] 6. The method of any one of clauses 1 to 4, wherein the solid-liquid blend of (iii) is used as a feedstock in a delayed coker, a fluid coker, or a flexicoker in step (iv).

[0175] 7. The method of clause 6, wherein the feedstock is introduced into the drum of a delayed coker.

[0176] 8. The method of any one of clauses 6 or 7, wherein the feedstock is heated to a temperature of at least 450 °C.

[0177] 9. The method of clause 6, wherein the feedstock is introduced into a fluidized bed coking reactor.

[0178] 10. The method of any one of clauses 1 to 9, wherein step (iii) includes a fractionation step.

[0179] 11. The method of any one of clauses 1 to 10, further comprising a step of calcining the coke of step (iv) to produce calcined coke.

[0180] 12. A method of operating a delayed coker, comprising performing the method of any one of clauses 1 to 8 in a delayed coker.

[0181] 13. A method for operating a fluid coker or a flexicoker, comprising performing the method of any one of clauses 1 to 6 or clause 9 in a fluid coker or a flexicoker.

[0182] 14. A coke product obtainable by the method of any one of clauses 1 to 10.

[0183] 15. The coke product of clause 14, wherein the coke is prepared from a solid-liquid blend comprising at least about 5% m and at most about 30% m PCP, optionally at least about 10% m and at most about 20% m PCP.

[0184] 16. The coke product of clause 14 or 15, wherein the coke is prepared from a solid-liquid blend comprising residual oil.

[0185] 17. The coke product of any one of clauses 14 to 16, wherein the coke is selected from: fuel grade coke; anode grade coke; needle coke; liquid coke; and battery coke.

[0186] 18. A calcined coke product obtainable by the method of clause 11.

[0187] 19. A carbon anode comprising the calcined coke product of clause 18.

[0188] 20. A distillate hydrocarbon liquid product obtainable by the method of any one of clauses 1 to 10.

[0189] 21. A method for increasing the yield of liquid volatile fractions in a delayed, fluid or flexible coking process, comprising adding a purified coal product (PCP) to a liquid oil feed stream, wherein the PCP is in particulate form and wherein at least about 90 volume % (%) v of the particles have a diameter not greater than about 75 μm; wherein the PCP has an ash content of less than about 10% m and a water content of less than about 5% m.

[0190] 22. The method of clause 21, wherein at least about 90 volume % (%) v of the PCP particles have a diameter not greater than about 75 μm; optionally, not greater than about 50 μm.

[0191] 23. The method of clause 21, wherein at least about 80 volume % (%) v of the PCP particles have a diameter not greater than about 20 μm.

[0192] 24. The method of any one of clauses 21 to 23, wherein the ash content of the PCP is less than about 2% m, suitably less than about 1.5% m; optionally less than 1% m.

[0193] 25. The method of clause 24, wherein the PCP has an ash content of less than about 0.9% m.

[0194] 26. The method of any one of clauses 21 to 25, wherein the PCP has a water content of less than about 2% m.

[0195] 27. The method of any one of clauses 21 to 26, wherein the liquid oil comprises one or more of the following group: residues from atmospheric distillation of a refinery of a crude oil feedstock; residues from vacuum distillation of a crude oil feedstock; slurry from a catalytic cracker; bottoms from a naphtha cracker; oil produced by pyrolysis of plastics, wood, and biomass; black liquor from the kraft process of pulp manufacture; light and heavy recycle oils; light and heavy oil gases; diesel fuel; fuel oil; marine oil; boiler fuel oil; decanted oil; marine fuel oil; marine diesel; biodiesel; waste oil; oil derived from tar sands; crude oil; synthetic crude oil; and oil from biofuel manufacture.

[0196] 28. Use of a purified coal product (PCP), wherein the PCP is in particulate form and wherein at least about 90 volume % (%) v of the particles have a diameter not greater than about 75 μm; wherein the PCP has an ash content of less than about 10% m and a water content of less than about 5% m, as an additive in a delayed, fluid, or flexible coking process to increase the proportion of liquid volatile products produced by the process.

[0197] 29. The use of clause 28, wherein the PCP is added to a residual oil to produce a feedstock for a delayed coking, fluid coking, or flexible coking process.

[0198] 30. The use of clause 29, wherein the residue is not hydrogenated.

[0199] 31. The use of any one of clauses 29 to 30, wherein the residual oil comprises one or more of the following group: residues from atmospheric distillation of a refinery of a crude oil feedstock; residues from vacuum distillation of a crude oil feedstock; slurry from a catalytic cracker; bottoms from a naphtha cracker; oil produced by pyrolysis of plastics, wood, and biomass; black liquor from the kraft process of pulp manufacture; light and heavy recycle oils; light and heavy oil gases; diesel fuel; fuel oil; marine oil; boiler fuel oil; decanted oil; marine fuel oil; marine diesel; biodiesel; waste oil; oil derived from tar sands; crude oil; synthetic crude oil; and oil from biofuel manufacture.

[0200] 32. The use of any one of clauses 28 to 31, wherein the use results in a decrease in the proportion of gaseous volatile products from a delayed coking process.

[0201] 33. The use of any one of clauses 28 to 31, wherein the use results in the conversion of gaseous volatile products from a delayed coking process into liquid volatile products.

[0202] Although specific embodiments of the present invention are disclosed in detail herein, this is by way of example only and for illustrative purposes only. The foregoing embodiments are not intended to limit the scope of the present invention which they follow. The inventors contemplate that various alternatives, modifications, and variations of the present invention can be made without departing from the spirit and scope of the present invention.

Claims

1. A method for producing coke and one or more volatile products, the method comprising the following steps: (i) Providing a purified coal product (PCP), wherein the PCP is in particulate form and wherein at least 90 volume % (%)v of the particles have a diameter not greater than 100 μm; wherein the PCP has an ash content of less than 10 %m and a water content of less than 5 %m; (ii) Combining the PCP with a liquid residual oil to produce a combined solid-liquid blend, wherein the solid-liquid blend comprises at least 0.1 %m and at most 30 %m of the PCP, and wherein the residual oil refers to a residue obtained after at least one oil refining stage; (iii) Subjecting the solid-liquid blend to a temperature above 375 °C for a sufficient time to cause at least 1 % of the PCP particles to crack to produce one or more volatile products, and (iv) Producing coke from the product of step (iii).

2. The method according to claim 1, wherein at least 90 volume % (%)v of the PCP particles have a diameter not greater than 75 μm; optionally, not greater than 50 μm.

3. The method according to claim 1, wherein the ash content of the PCP is less than 2 %m, suitably less than 1.5 %m; optionally not exceeding 1 %m.

4. The method according to claim 1, wherein the water content of the PCP is less than 2 %m.

5. The method according to claim 1, wherein the liquid residual oil comprises one or more selected from the group consisting of: residues from atmospheric distillation of refineries from crude oil feedstocks; residues from vacuum distillation of crude oil feedstocks; slurry from catalytic crackers; bottoms from naphtha crackers; oils produced by pyrolysis of plastics, wood and biomass; black liquor from kraft processes for pulp manufacture; light and heavy cycle oils; light and heavy oil gases; diesel fuel; fuel oil; marine fuel oil; boiler fuel oil; decanted oil; marine bunkers; marine diesel; biodiesel; waste oil; oils derived from tar sands; and oils from biofuel manufacture.

6. The method according to claim 1, wherein the solid-liquid blend of (iii) is used as a feedstock in a delayed coker, a fluid coker or a flexicoker in step (iv).

7. The method according to claim 6, wherein the feedstock is introduced into the drum of the delayed coker.

8. The method according to claim 6, wherein the feedstock is heated to a temperature of at least 450 °C.

9. The method according to claim 6, wherein the feedstock is introduced into a fluidized bed coking reactor.

10. The method according to claim 1, wherein step (iii) comprises a fractionation step.

11. The method according to claim 1, further comprising a step of calcining the coke of step (iv) to produce calcined coke.

12. A method of operating a delayed coker, comprising performing the method of claim 1 in the delayed coker.

13. A method of operating a fluid coker or a flexicoker, comprising performing the method of claim 1 in the fluid coker or the flexicoker.

14. A coke product obtainable by the method of claim 1.

15. The coke product according to claim 14, wherein the coke is prepared from a solid-liquid blend comprising at least 5% m and at most 30% m PCP, optionally at least 10% m and at most 20% m PCP.

16. The coke product according to claim 14, wherein the coke is prepared from a solid-liquid blend comprising residual oil.

17. The coke product according to any one of claims 14 to 16, wherein the coke is selected from: fuel grade coke; anode grade coke; needle coke; liquid coke; and battery coke.

18. A calcined coke product obtainable by the method according to claim 11.

19. A carbon anode comprising the calcined coke product of claim 18.

20. A distillate hydrocarbon liquid product obtainable by the method according to claim 1.

21. A method for increasing the yield of liquid volatile fractions in a delayed, fluid or flexible coking process, comprising adding a purified coal product (PCP) to a liquid residual oil feed stream, wherein the residual oil is the residue obtained after at least one refinery stage, and the PCP is in particulate form, and wherein at least 90 volume % (%) v of the particles have a diameter not greater than 75 μm; wherein the PCP has an ash content of less than 10% m and a water content of less than 5% m.

22. The method according to claim 21, wherein at least 90 volume % (%) v of the PCP particles have a diameter not greater than 75 μm; optionally, a diameter not greater than 50 μm.

23. The method according to claim 21, wherein at least 80 volume % (%) v of the PCP particles have a diameter not greater than 20 μm.

24. The method according to claim 21, wherein the ash content of the PCP is less than 2% m, suitably less than 1.5% m; optionally less than 1% m.

25. The method according to claim 24, wherein the ash content of the PCP is less than 0.9% m.

26. The method according to claim 21, wherein the water content of the PCP is less than 2% m.

27. The method according to claim 21, wherein the liquid residual oil comprises one or more selected from the group consisting of: residues from the atmospheric distillation of a refinery of a crude oil feedstock; residues from the vacuum distillation of a crude oil feedstock; slurry from a catalytic cracker; bottoms from a naphtha cracker; oils produced by the pyrolysis of plastics, wood and biomass; black liquor from the kraft process for pulp manufacture; light and heavy cycle oils; light and heavy hydrocarbon gases; diesel fuel; fuel oil; marine fuel oil; boiler fuel oil; decant oil; marine bunkers; marine diesel; biodiesel; waste oil; oils derived from tar sands; and oils from biofuel manufacture.

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