SOLID FUEL COMPOSITION FROM PETROLEUM REFINERY WASTE SOLIDS
FIELD OF THE INVENTION
[0001] The present disclosure pertains to technical field of solid fuels. In particular, the present disclosure pertains to solid fuel composition prepared from petroleum refinery waste solids, and to methods for preparing the same.
BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Petroleum refineries have a need to dispose of the wastes comprised of oily sledges (oil-solid or oil-solid-water mixtures) produced in waste water treatment facilities and hydrocarbon storage tanks. In recent times, tank bottom wastes, sometimes referred to as sludge and often shortened to just tank bottoms, have become an increasing problem since their regulation has often classified them as environmentally hazardous wastes with the corresponding difficult and expensive handling problems. However, by appropriate processing, this designation can wane off and the resulting constituents can become potential products/materials or can be disposed of in an ordinary manner. Additionally, their composition, being a mixture of hydrocarbon, solids and water, is unacceptable for refineries, which would require the removal of significant portions of solids and water.
[0004] The amount of this potential tank bottom waste builds to large quantities, not only because of the large oil field, pipe line, and refinery capacities in this country, but also because of the storage of these tank bottoms until some disposal method can be employed. Particularly, in remote oil fields, far from refineries, storage needs to be continued for many years. Most of these wastes are disposed of by microbial treatment on large area of land at a site. However, certain types of oily sludge cannot be land treated due to the bio-refractory nature of the oil contained therein. For example, some refinery tank bottom sludge (e.g., Coker hot slop tank sludge and cat fractionator’s bottoms sludge) contain viscous oil and high levels of bio refractory polynuclear aromatic components, which are not suitable for disposal through land treatment. Removal of 2
bio-refractory oil from oily sludges in order to make them suitable for land treating could be an attractive waste management option. However, conventional de-oiling processes and services are costly and in some cases do not achieve the desired result. For example, extraction based technologies using special solvents rely on recovery and recycling of the solvent and may leave asphaltene fractions of the oil on the solids.
[0005] Similarly disposal of spent charcoal and petroleum coke from delayed coker plant is also a problem because of presence of heavy metals and sulphur. Petroleum coke (also petcoke) is a carbonaceous solid by-product produced by coker unit in crude oil refineries after crude oil has been subjected to a fractional distillation process. Activated charcoal is used by petroleum refineries for the removal of objectionable organic compounds from liquid and vapor streams. The term “spent charcoal” or “spent activated carbon” is used in petroleum industries to denote activated carbon that has lost all or a significant amount of its absorptive capacity and is no longer useful as an adsorbent. Spent activated carbon must either be discarded and replaced by fresh activated carbon or regenerated. Regeneration of activated carbon is achieved by heat treatment at extremely high temperatures, and because of the energy consumed in heat treatment the price of regenerated activated carbon is nearly equal to the price of new activated carbon. Consequently, many petroleum refineries send their spent activated carbon to waste handling facilities such as landfills rather than either sending it to regeneration facilities or regenerating it on-site.
[0006] US patent 5269234 discloses a method for utilizing land fill prohibited solid hazardous waste material as an energy source in a cement kiln. The method comprises combining the solid waste materials with a liquid fuel in a milling apparatus to form a mixture, grinding the mixture in the milling apparatus in a manner reducing the particulate size of the solid hazardous waste material to form fuel slurry, and delivering the fuel slurry directly into the flame of the cement kiln.
[0007] US. Patent 4481101 describes a method for refining coker feedstock to remove metals and other contaminants from petroleum coke.
[0008] US patent 5495986 discloses a method for providing a fuel mixture by processing refinery sludge and blend stock, which provides fuel. The process contains steps of grinding the waste material in a tank containing the blend stock with the grinding being in at least part provided by the co-action between a rotating impeller and a stationery plate. 3
[0009] US patent 5259945 discloses a process for the recovery of tank bottom wastes employing a flash tank fed with hot, pressurized tank bottom wastes and separating a vapor component and heavier bottoms then fed to a stripping reactor along with hot gas producing an overhead vapor with a solid remainder. Tank bottom sludge is employed as fuel.
[00010] US patent 5288391 discloses a process for de-oiling wastes. The process is integrated with a refinery and utilizes a refinery intermediary hydrocarbon stream as a solvent to recover waste oil for reprocessing in the refinery and to produce waste solids, which are either reused or disposed for land treatment. US patent 5078593 discloses a method for disposal of oil refinery sludge containing a hydrocarbon component, a solid component comprising sediments such as sand, silt, rust or scale, and water in an operating rotary kiln.
[00011] US patent 4786401 discloses a liquid sludge disposal process wherein hydrocarbon-containing liquid waste sludge from refinery waste streams can be disposed of by blending with the feedstock being passed in a fluid catalytic cracking unit. The sludge is premixed with a hydrocarbon, such as light oil, prior to mixing with the feed. However, by mixing with FCC feed, it may damage the catalyst due to poisonous metals and high nitrogen and also leads to high emissions and change in product slate.
[00012] Nevertheless, there remains a continuing need in the art for technologies that not only solve the problem of disposal of petroleum refinery waste solids such as refinery tank sludge, spent charcoal and petroleum coke, but also render the waste solids usable as a valuable fuel.
[00013] The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.
[00014] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[00015] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found 4
herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability.
OBJECTS OF THE INVENTION
[00016] It is an object of the present disclosure to provide a method of processing petroleum refinery waste solids, which not only solves the problem of waste disposal but also renders the waste solids usable as a valuable fuel.
[00017] It is another object of the present disclosure to provide a solid fuel composition which is prepared solely from waste solids generated by petroleum refinery operations.
[00018] It is another object of the present disclosure to provide a solid fuel composition having high calorific value.
[00019] It is another object of the present disclosure to provide a solid fuel composition that is economical to produce.
[00020] It is another object of the present disclosure to provide a solid fuel composition that effects disposal of petroleum refinery waste solids and potentially hazardous materials.
[00021] It is another object of the present disclosure to provide a solid fuel composition that finds utility as a fuel in rotary mineral processing kiln, such as a lime, light-weight aggregate, asphalt, cement kiln, brick industry and the like.
[00022] It is yet another object of the present disclosure to provide a method of preparation of a solid fuel composition from waste solids generated by petroleum refinery operations.
SUMMARY
[00023] Aspects of the present disclosure relate to solid fuel composition prepared from waste solids generated by petroleum refinery operations. The solid fuel composition disclosed herein can exhibit high calorific value and can find greater utility as fuel in rotary mineral processing kiln, such as a lime, light-weight aggregate, asphalt, cement kiln, brick industry and the likes. Further, the solid fuel composition can be easily handled and transported.
[00024] In an aspect, the present disclosure provides a solid fuel composition which can include a waste mixture including petroleum refinery sludge and at least one of petroleum coke and spent charcoal. According to embodiments of the present disclosure, the solid fuel composition can exhibit calorific value of at least 7000 calories/gram. 5
[00025] In an embodiment, the waste mixture used to produce the solid fuel composition can be a combination of petroleum refinery sludge and petroleum coke.
[00026] In an exemplary embodiment, the waste mixture can include petroleum refinery sludge and petroleum coke in a weight ratio ranging from 1:5 to 5:1.
[00027] In a most preferred embodiment, the waste mixture can include petroleum refinery sludge and petroleum coke in a weight ratio of 1:1.
[00028] In an embodiment, the waste mixture used to produce the solid fuel composition can be a combination of petroleum refinery sludge and spent charcoal.
[00029] In an exemplary embodiment, the waste mixture can include petroleum refinery sludge and spent charcoal in a weight ratio ranging from 1:5 to 5:1.
[00030] In a most preferred embodiment, the waste mixture can include petroleum refinery sludge and spent charcoal in a weight ratio of 2:1, 3:1 or 4:1.
[00031] In an embodiment, the solid fuel composition disclosed herein can be in the form of an extrudate.
[00032] According to embodiments of the present disclosure, the petroleum refinery sludge can be landfill-prohibited solid hazardous petroleum refinery tank sludge which contains water in an amount ranging from 10% to 30% by weight of the sludge.
[00033] In another aspect, the present disclosure provides a method of preparation of a solid fuel composition, the method can include the steps of: combining petroleum refinery sludge with at least one of petroleum coke and spent charcoal to form a mixture; and extruding the mixture using an extruder to produce a solid fuel composition, wherein the solid fuel composition exhibits calorific value of at least 7000 calories/gram.
[00034] In an embodiment, the method disclosed herein can further include the step of drying the produced solid fuel composition.
[00035] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.
BRIEF DESCRIPTION OF DRAWINGS
[00036] The diagrams are for illustration only, which thus is not a limitation of the present invention, and wherein: 6
[00037] FIG. 1 is a photograph of a sample of refinery tank sludge obtained from a petroleum refinery.
[00038] FIG. 2 is a photograph of a sample of petroleum coke obtained from a petroleum refinery.
[00039] FIG. 3 is a photograph of a sample of spent charcoal obtained from a petroleum refinery.
[00040] FIG. 4 shows a photograph of an exemplary pelletized solid fuel composition made from a mixture of refinery tank sludge and petroleum coke in accordance with an embodiment of the present disclosure.
[00041] FIG. 5 shows a photograph of an exemplary pelletized solid fuel composition made from a mixture of refinery tank sludge and spent charcoal in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[00042] The embodiments herein and the various features and advantageous details thereof are explained more comprehensively with reference to the non-limiting embodiments that are detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
[00043] Unless otherwise specified, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions may be included to better appreciate the teaching of the present invention.
[00044] As used in the description herein, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[00045] As used herein, the terms “comprise”, “comprises”, “comprising”, “include”, “includes”, and “including” are meant to be non- limiting, i.e., other steps and other ingredients which do not affect the end of result can be added. The above terms encompass the terms “consisting of” and “consisting essentially of”.
[00046] As used herein, the terms “composition” “blend,” or “mixture” are all intended to be used interchangeably. 7
[00047] The terms “weight percent,” “wt%,” “percent by weight,” “% by weight,” and variations thereof, as used herein, refer to the concentration of a substance as the weight of that substance divided by the total weight of the composition and multiplied by 100. It is understood that, as used here, “percent,” “%,” and the like are intended to be synonymous with “weight percent,” “wt-%,” etc.
[00048] The present disclosure generally relates to recovery of energy values from petroleum refinery waste solids such as refinery tank sludge, refinery spent charcoal and petroleum coke. In its broadest sense the present disclosure provides a solid fuel composition prepared from waste solids generated by petroleum refinery operations. The solid fuel composition disclosed herein can exhibit high calorific value and can find greater utility as fuel in rotary mineral processing kiln, such as a lime, light-weight aggregate, asphalt, cement kiln, brick industry and the likes. Further, the solid fuel composition can be easily handled and transported.
[00049] In an aspect, the present disclosure provides a solid fuel composition which can include a waste mixture including petroleum refinery sludge and at least one of petroleum coke and spent charcoal. According to embodiments of the present disclosure, the solid fuel composition can exhibit calorific value of at least 7000 calories/gram.
[00050] In an embodiment, the waste mixture used to produce the solid fuel composition can be a combination of petroleum refinery sludge and petroleum coke.
[00051] In an exemplary embodiment, the waste mixture can include petroleum refinery sludge and petroleum coke in a weight ratio ranging from 1:5 to 5:1.
[00052] In a most preferred embodiment, the waste mixture can include petroleum refinery sludge and petroleum coke in a weight ratio of 1:1.
[00053] In an embodiment, the waste mixture used to produce the solid fuel composition can be a combination of petroleum refinery sludge and spent charcoal.
[00054] In an exemplary embodiment, the waste mixture can include petroleum refinery sludge and spent charcoal in a weight ratio ranging from 1:5 to 5:1.
[00055] In a most preferred embodiment, the waste mixture can include petroleum refinery sludge and spent charcoal in a weight ratio of 2:1, 3:1 or 4:1.
[00056] In an embodiment, the solid fuel composition disclosed herein can be in the form of an extrudate. 8
[00057] According to embodiments of the present disclosure, the petroleum refinery sludge can be landfill-prohibited solid hazardous petroleum refinery tank sludge which contains water in an amount ranging from 10% to 30% by weight of the sludge.
[00058] In another aspect, the present disclosure provides a method of preparation of a solid fuel composition, the method can include the steps of: combining petroleum refinery sludge with at least one of petroleum coke and spent charcoal to form a mixture; and extruding the mixture using an extruder to produce a solid fuel composition, wherein the solid fuel composition exhibits calorific value of at least 7000 calories/gram.
[00059] In an embodiment, the method disclosed herein can further include the step of drying the produced solid fuel composition.
[00060] According to embodiments, the solid fuel composition disclosed herein can either be used as a fuel substitute alone or mixed with other fuels such as coal, oil materials, or the like.
[00061] Typically, oily refinery sludge composition includes both organic and inorganic components, varying from one refinery to the other and often varying within a refinery depending upon time and source. Factors likely to affect the composition include crude oil characteristics, composition and quantity of water, spills and leaks, blow down, refinery housekeeping, refinery size and age, and segregation of oil drains.
[00062] Oil refinery sludge contains oil, gas fraction, water fraction and a solid fraction. Prior to dewatering, the oil and gas fraction typically contains about 15-45% by weight of the sludge and includes paraffins, napthenes, asphalts or other oils. Prior to dewatering, the solid fraction typically is in excess of about 3% by weight of the sludge and includes sediments such as sand, silt, rust, and scale and other inorganic components including various sulfur containing compounds and metals such as arsenic, barium, cadmium, chromium, lead, mercury, nickel, selenium, silver, and vanadium and compounds containing such metals. Such sludge typically contain in the range of about 40 to 90 percent water by weight prior to dewatering. In addition, the majority of the inorganic constituents of oily refinery sludge is advantageously incorporated in and contributes to the mineral value of the in-process mineral matter.
[00063] Figure 1 shows a photograph of a sample of refinery tank sludge obtained from a petroleum refinery. Typical composition of petroleum refinery tank sludge is shown in Table1 below.
9
Table 1
Metals
Sludge
Wt%
Copper
0.005
Aluminium
0.057
Iron
1.36
Magnesium
0.063
Manganese
0.014
Sodium
0.053
Zinc
0.007
Nickel
0.015
Chromium
0.004
[00064] The main inorganic constituents of spent charcoal and sludge mixtures are alumina and silica and other metals that go through a chemical and/or physical change in the process of the present invention. Particularly in the elevated temperatures of the firing zone of the kiln, toxic metals are generally chemically combined to form non-leachable complex silicates and aluminates. These chemical components of sludge and spent charcoal mixtures are having good cementation properties which can add value to the final burned material.
[00065] Prior to dewatering, oily refinery sludges typically have excess water content ranging from 10 to 60 wt% and an energy content of substantially less than 4000 BTU per pound (453.5 gr). In this form, the material is difficult to handle and has insufficient energy content to be used by itself as a fuel for burning. In typical cement making process, raw materials, such as clay, shale, limestone and silica are crushed in crusher and stored in raw material storage tanks. For the manufacture of cement, the raw materials are ground in the wet raw grinding mill, and slurried with water (about 34 wt. % water). The kiln feed slurry is introduced to the rotary kiln through the cold end of the rotary kiln. Coal stored in bin is ground in mill and introduced to hot end of the rotary kiln. The coal may be supplemented by fuel from supplementary fuel source. Immediately inside the rotary kiln the fuel is ignited.
[00066] Sludge and spent charcoal or petroleum coke extrudates may be charged to the rotary kiln for burning in any number of methods. In one method, extudates with an energy content of at least about 4,000 BTU per pound, preferably at least 5,000 BTU per pound, is blended with ground coal or coke and the blended material is then handled in a manner identical 10
to that in which ground coal and coke are handled as fuels, i.e., pneumatically or mechanically charged to a zone of the kiln in which fuel is burned, preferably the firing zone. The blend preferably should have an energy content of at least about 8,000 BTU per pound.
[00067] In another method, sludge and spent charcoal or petroleum coke mixtures are charged directly to a zone of the kiln in which fuel is burned, preferably the firing zone, without prior mixing or blending with another fuel. When charged to the kiln directly, the dewatered particulate material should have an energy content of at least 4,000 BTU per pound, preferably at least 5,000 BTU per pound, and most preferably greater than about 8,000 BTU per pound (4438 Cal per gram).
[00068] In yet another method, the dewatered particulate sludge is slurried with a liquid fuel and the slurry is then charged to a zone of the kiln in which fuel is burned, preferably the firing zone. For use in this method, the dewatered particulate material should have an energy content of at least 4,000 BTU per pound, preferably at least 5,000 BTU per pound, and the slurry should have an energy content of at least about 8,000 BTU per pound. Prior to charging to the rotary kiln, the sludge and spent charcoal mixtures are dried to the level of water content by 40%.
[00069] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
EXAMPLE
[00070] The present disclosure is further explained in the form of following examples. However, it is to be understood that the foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the 11
disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.
EXAMPLE 1
[00071] In order to prepare best solid fuel composition out of petroleum refinery sludge and refinery spent charcoal different mixtures were prepared. Sludge collected from refinery tank and FCC spent catalyst (i.e. spent charcoal) were mixed in 1:1 ratio. In a typical experiment about 200 grams of sludge was mixed with 200 grams of refinery spent catalyst in a beaker using a spatula. After mixing, the resultant mixture was loaded into laboratory extruder which had 4mm diameter die. Extruded material was dried at room temperature for four days. Figures 1 and 3 show photograph of a sample of refinery tank sludge and spent charcoal obtained from a petroleum refinery, respectively. Figure 5 shows a photograph of the pelletized solid fuel composition. The resultant pelletized solid fuel composition exhibited less calorific value of 5876 Cal/gram, as illustrated in Table 2 below.
Table 2
Sludge : Spent charcoal
Calorific value, Cal/gram
1:1
5876
EXAMPLE 2
[00072] Sludge collected from refinery tank and refinery spent charcoal were mixed in 2:1 ratio. In a typical experiment about 400 grams of sludge was mixed with 200 grams of charcoal in a beaker using a spatula. After mixing, the resultant mixture was loaded into laboratory extruder which had 4mm diameter die. Extruded material was dried at room temperature for four days. The resultant pelletized solid fuel composition exhibited very good calorific value of 7026 Cal/gram, as illustrated in Table 3 below.
Table 3
Sludge : Spent charcoal
Calorific value, Cal/gram
2:1
7026 12
EXAMPLE 3
[00073] Sludge collected from refinery tank and refinery spent charcoal were mixed in 3:1 ratio. In a typical experiment about 600 grams of sludge was mixed with 200 grams of charcoal in a beaker using a spatula. After mixing the resultant mixture was loaded into laboratory extruder which had 4mm diameter die. Extruded material was dried at room temperature for four days. The drying process may be enhanced by applying vacuum or heating at moderate temperatures. The resultant pelletized solid fuel composition exhibited very good calorific value of about 7315 Cal/gram, as illustrated in Table 4 below.
Table 4
Sludge : Spent charcoal
Calorific value, Cal/gram
3:1
7315
EXAMPLE 4
[00074] Sludge collected from refinery tank and refinery spent charcoal were mixed in 4:1 ratio. In a typical experiment about 800 grams of sludge was mixed with 200 grams of charcoal in a beaker using a spatula. After mixing the resultant mixture was loaded into laboratory extruder. Extruded material was dried at room temperature for four days. The resultant pelletized solid fuel composition exhibited a calorific value of about 7609 Cal/gram, as illustrated in Table 5 below. The calorific value of the pelletized fuel composition matches with best coals used for fuel applications.
Table 5
Sludge : Spent charcoal
Calorific value, Cal/gram
4:1
7609
Composition of the refinery tank sludge and metal profile of the pelletized solid fuel composition is shown in Table 6 below:
Table 6
Metals
Sludge
Final product (4:1) 13
Wt%
wt%
Copper
0.005
0.004
Aluminium
0.057
0.550
Iron
1.36
1.92
Magnesium
0.063
0.429
Manganese
0.014
0.019
Sodium
0.053
0.101
Zinc
0.007
0.033
Nickel
0.015
0.017
Chromium
0.004
0.005
EXAMPLE 5
[00075] Sludge collected from petroleum refinery tank and petroleum coke were mixed in different ratios and extruded using a mixtruder facility. Figure 2 shows photograph of a sample of petroleum coke obtained from a petroleum refinery. Figure 4 shows a photograph of the pelletized solid fuel composition. The resultant pelletized solid fuel composition exhibited very good calorific value as illustrated in Table 7 below.
Table 7
Sludge : Petroleum coke
Calorific value, Cal/gram
1:1
7027
Petcoke
8193
ADVANTAGES OF THE INVENTION
[00076] The present disclosure provides a method of processing petroleum refinery waste solids such as refinery tank sludge, spent charcoal and petroleum coke, which solves the problem of waste disposal as well as renders the waste solids usable as a valuable fuel.
[00077] The present disclosure provides a solid fuel composition which is prepared solely from waste solids generated by petroleum refinery operations. 14
[00078] The present disclosure provides a solid fuel composition that has high calorific value.
[00079] The present disclosure provides a solid fuel composition that is economical to produce.
[00080] The present disclosure provides a solid fuel composition which can be easily handled and transported.
[00081] The present disclosure provides a solid fuel composition that effects disposal of petroleum refinery waste solids and potentially hazardous materials.
[00082] The present disclosure provides a solid fuel composition that finds greater utility as a fuel in rotary mineral processing kiln, such as a lime, light-weight aggregate, asphalt, cement kiln, brick industry and the like.
[00083] The present disclosure provides simple, environment friendly and highly efficient method for preparation of solid fuel composition from petroleum refinery waste solids.

We Claim:
1. A solid fuel composition comprising a waste mixture comprising petroleum refinery sludge and at least one of petroleum coke and spent charcoal, wherein the solid fuel composition exhibits calorific value of at least 7000 calories/gram.
2. The solid fuel composition as claimed in claim 1, wherein the waste mixture comprising petroleum refinery sludge and petroleum coke.
3. The solid fuel composition as claimed in claim 2, wherein the waste mixture comprising petroleum refinery sludge and petroleum coke in a weight ratio ranging from 1:5 to 5:1.
4. The solid fuel composition as claimed in claim 2, wherein the waste mixture comprising petroleum refinery sludge and petroleum coke in a weight ratio of 1:1.
5. The solid fuel composition as claimed in claim 1, wherein the waste mixture comprising petroleum refinery sludge and spent charcoal.
6. The solid fuel composition as claimed in claim 5, wherein the waste mixture comprising petroleum refinery sludge and spent charcoal in a weight ratio ranging from 1:5 to 5:1.
7. The solid fuel composition as claimed in claim 5, wherein the waste mixture comprising petroleum refinery sludge and spent charcoal in a weight ratio of 2:1, 3:1 or 4:1.
8. The solid fuel composition as claimed in claim 1, wherein the petroleum refinery sludge is a solid petroleum refinery tank sludge, and wherein the petroleum refinery tank sludge comprising water in an amount ranging from 10% to 30% by weight of the sludge.
9. The solid fuel composition as claimed in claim 1, wherein the solid fuel composition is an extrudate.
10. A method of preparation of a solid fuel composition, the method comprising the steps of: 16
combining petroleum refinery sludge with at least one of petroleum coke and spent charcoal to form a mixture; and
extruding the mixture using an extruder to produce a solid fuel composition,
wherein the solid fuel composition exhibits calorific value of at least 7000 calories/gram.
11. The method as claimed in claim 10, wherein the mixture comprising petroleum refinery sludge and petroleum coke in a weight ratio of 1:1.
12. The method as claimed in claim 10, wherein the mixture comprising petroleum refinery sludge and spent charcoal in a weight ratio of 2:1, 3:1 or 4:1.
13. The method as claimed in claim 10, wherein the petroleum refinery sludge is a solid petroleum refinery tank sludge, and wherein the petroleum refinery tank sludge comprising water in an amount ranging from 10% to 30% by weight of the sludge.
14. The method as claimed in claim 10 further comprising the step of drying the solid fuel composition.