REFORMULATING FUEL OIL USING RE-REFINED USED COMPOSITE BYPRODUCTS AS A NEW CUTTER STOCK

Abstract

To reformulate a new fuel oil blend. Used lube oil feedstock, which is received from collection storage intermediary facilitiesis re-refined to form multiple re-refined byproducts including light solvent, used fuel oil, light extract, and heavy extract. A used oil composite byproduct is formed by blending a portion of the light solvent, a portion of the used fuel oil and a portion of the light extract. A portion of the used oil composite byproduct as viscosity cutter stock is blended with refined fuel oil to reformulate a final refined fuel oil blend. The refined fuel oil to which the portion of the used oil composite byproduct is added includes heavier hydrocarbons than the used oil composite byproduct.

Description

TECHNICAL FIELD

This disclosure relates to reformulating hydrocarbon blends, for example, blends of fuel oil used to generate heat and power.

BACKGROUND

Crude oil refining is a complex series of steps in which crude oil is broken down into its components and reconfigured into new products. The steps can include separation, conversion, treatment and blending. In the separation step, the crude oil is heated in furnaces and piped into distillation units. In the distillation units, the crude oil is separated into fractions (heavier and lighter fractions) based on physical properties such as boiling point and weight. In the conversion step, the fractions are further refined to create streams of finished products. The conversion step implements heat, pressure, catalysts or combinations of them to break the hydrocarbon chains in the fractions. In the treatment step, contaminants like sulfur, nitrogen and heavy metals are removed. In the blending step, the various streams are blended with additives and other components to create finished products with desired properties. The blended products can then be shipped or stored. Fuel oil is one example of finished product made by crude oil refining. Fuel oil is made by distilling crude oil causing different hydrocarbon components in the crude oil to vaporize and separate based on boiling points. Heavier fuel oil fractions collect at the bottom of a distillation tower, while lighter components rise to the top.

SUMMARY

This disclosure describes technologies relating to reformulating fuel oil using re-refined used oil composite byproducts as a new cutter stock from re-refining of used lube oil that is typically outside of the hydrocarbon refining process.

The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of an example of a process of re-refining used lube oil.

FIG. 2 is a schematic of an example of a process of preparing a final fuel oil blend using a new cutter stock.

FIG. 3 is a flowchart of an example of a process of re-refined used lube oil.

FIG. 4 is a flowchart of an example of a process of preparing a final fuel oil blend using used oil composite byproduct.

Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

This disclosure describes technology relating to recycled used oil re-refining outside of a typical hydrocarbon refining process. Re-refining recycled used oil generates re-refined base oil, residual water, and byproducts, such as light solvent, used fuel oil, light extract, and heavy extract. The lighter portion of the byproducts, such as the light solvent, used fuel oil, and light extract can be further processed and mixed as a diluent with heavier hydrocarbon fractions to produce various fuel oil blends. Processing the lighter portion of the byproducts can include filtration to adjust trace metal distribution in the diluent. The used composite byproduct component (i.e., the processed byproducts used as the diluent) can at least partially substitute conventional cutter stock, which is typically mid-distillate in fuel oil blends, to adjust the viscosity quality parameter of the resulting fuel oil blend.

In some implementations, a maximum of 5% of the used composite byproduct component is mixed with heavier hydrocarbon fractions to produce the fuel oil blend. Laboratory assessment of the produced fuel oil blends (including a maximum of 5% of the used composite byproduct component) indicated no issues in thermal stress tests and in key quality parameters, such as density, flash point, pour point, viscosity, micro-carbon residue, and sediments. Further, when spot tested, and the produced fuel oil blends exhibited homogeneous spots with no inner ring with a Spot Rating 1 using standard test method, such as ASTM (American Society for Testing and Materials) D4740.

Implementing the techniques described in this disclosure can yield one or more of the following advantages. By at least partially substituting conventional cutter stock, the processed byproducts can be used advantageously to enhance circularity of recycled and reprocessed used oil. Such reuse can assist decarbonization efforts for contributing to net zero emissions climate goals. Such reuse can also improve process resilience and leverage economic competitive advantages.

FIG. 1 is a schematic of an example of a process of re-refining raw used lube oil. As described later, used lube oil 102 is a recycled stream that is collected from outside of a typical crude oil (hydrocarbon) refinery. The used lube oil 102 is used as feedstock by used oil re-refining process system 104, which, in some implementations, is exogenous to a typical hydrocarbon refinery setup. In such implementations, the used lube oil 102 can be transported to the used oil re-refining process system 104 from collection storage intermediary facilities, for example, through fuel trucks. By products of re-refining the used lube oil 102 can be flowed or transported back to the hydrocarbon refinery for reformulating a new fuel oil blend.

The used oil re-refining process system 104 can include distillation units (for example, vacuum distillation units) to separate usable fuel oil from components in the used lube oil 102. The contaminants can include, for example, water, dirt and additives. The used oil re-refining process system 104 can also include hydrotreating units that use hydrogen gas to remove remaining impurities.

After processing the used lube oil 102, the used oil re-refining process system 104 produces re-refined base oils 106, byproducts 108 and residual water 110. The re-refined base oils 106 include light, medium and heavy hydrocarbons with varying viscosity index. In the context of this disclosure, light, medium and heavy is determined by the length and structure of carbon chains and molecular weight in the hydrocarbons. The re-refined base oils 106 can be flowed to different destinations for specific use. The residual water 110 can be lined up to wastewater treatment facility.

The byproducts 108 include process streams of light solvent 112, light extract 114, heavy extract 116 and used fuel oil 118, that were not separated into the base oils 106. Each process stream is produced during the distillation step of the used oil re-refining process. As described below, a portion of each of the light solvent 112, the light extract 114, and used fuel oil 118, is blended into used oil composite byproduct 120. The used oil composite byproduct 120 can be blended as a viscosity cutter stock to refined fuel oil that is produced within the hydrocarbon refinery. In some implementations, all of the light solvent 112, light extract 114, and used fuel oil 118 can be used to make the used oil composite byproduct 120. All of the used oil composite byproduct 120 can be used as a viscosity cutter stock as long as the maximum volume of this new viscosity cutter stock does not exceed 5% by volume. In implementations in which excess byproducts 108 or excess used oil composite byproduct 120 beyond that required as viscosity cutter stock is available, such streams can be used as combustion fuel.

FIG. 2 is a schematic of an example of a process of preparing a final fuel oil blend 216 using cutter stock 208 (e.g., conventional cutter stock such as diesel) and how the techniques described in this disclosure implement the utilization of used oil composite byproducts 120 to partially back off the cutter stock 208. The blending process system described with reference to FIG. 2 can use the used oil composite byproduct 120 (FIG. 1) as a blending component to the fuel oil. The refinery distillation process system 202 is the hydrocarbon refinery that is configured to process crude oil feedstock to form multiple process streams including diesel and fuel oil. The process system 202 can include, for example, crude distillation units, vacuum distillation units, supported by other auxiliary units that refine the raw crude oil into multiple process streams.

The process streams refined by the refinery distillation process system 202 include, for example, diesel flowed to a diesel reservoir 204 (or storage container) followed by diesel process stream hydro-desulfurization. The resulting product can be blended with appropriate fuel performance additives, and kerosene process stream, resulting in diesel. From the diesel reservoir 204, the final diesel product is available for transportation 206.

The process streams also include diesel cutter stock 208, which is a mid-distillate intermediary stream produced during the refining of crude oil that is typically received from the diesel reservoir 204. The used lube oil process stream 102 can produce a substitute to the diesel cutter stock as a byproduct of the used oil re-refining process 104. The diesel cutter stock is a low-viscosity oil mixture that is used to reduce the viscosity of (or “cut”) heavier fuel oils like residual fuel oil by blending.

The process streams also include heavy gas oil 210, which is again an intermediary process stream of refining crude oil. The heavy gas oil includes a heavy fraction of distilled crude oil and contains large hydrocarbon molecules. The heavy gas oil is often the heaviest liquid fraction produced before reaching the residual of the distillation tower. The heavy gas oil can be used as feedstock for further processing to produce lighter hydrocarbons through hydro-cracking.

The viscosity breaker plant (a visbreaker) 212 is a standalone processing unit part of the wider refining configuration, that breaks down large hydrocarbon molecules to heavy oils to create lighter product. A byproduct of the viscosity breaker plant is a visbreaker residue 214, which includes a thick, viscous liquid that has undergone mild thermal cracking for lowered viscosity adjustments.

Using flow equipment (pumps, valves, flow meters, and the like), metered volumes of certain blending components are flowed through the blender to a fuel oil reservoir 216, which can be a storage tank configured to hold and further agitate the blending ingredients. The flowed blending components can include a portion of the heavy gas oil 210 (e.g., 30% by volume). Portions of the diesel cutter stock 208 (e.g., 15% by volume) and the visbreaker residue 212 (e.g., 55% by volume) can also be flowed to the fuel oil reservoir 216 to blend with the heavy gas oil 210. The resulting product is the final fuel oil product that can be transported via fuel oil supply lines 218. The diesel cutter stock 208 and the visbreaker residue 214 function to reduce the viscosity of the final fuel oil reservoir 216 to levels acceptable for the fuel oil to be used for its intended purposes.

In some implementations, all or a portion of the used oil composite byproduct 120 can also be flowed to the fuel oil reservoir 216. The used oil composite byproduct 120 can be used to reduce the viscosity of the fuel oil in the reservoir 216. That is, the used oil composite byproduct 120 can be used to serve the same function as the diesel cutter stock 208. Consequently, a quantity of the diesel cutter stock 208, which would have been flowed to the reservoir 216 to reduce the viscosity of the fuel oil, no longer needs to be flowed to the reservoir 216. Instead, the quantity of the diesel cutter stock 208 can be reduced, for example, by a quantity equal to the quantity of the used oil composite byproduct 120. The reduced quantity of the diesel cutter stock 208 can be flowed, for example, to the diesel reservoir 204 to maximize the final diesel product yield for economic benefits.

FIG. 3 is a flowchart of an example of a process 300 of re-refined used lube oil. All or portions of the process 300 can be performed by the process systems described with reference to FIG. 1 or 2 or both. At 302, the process systems received raw used lube oil feedstock from collection storage intermediary facilities. For example, the used lube oil feedstock is exogenous to refining crude oil into fuel oil in a hydrocarbon refinery. The used lube oil is then provided (e.g., flowed) as feedstock to the used oil re-refining process systems 104. At 304, the used lube oil feedstock is re-refined to form multiple re-refined byproducts. The re-refining byproducts include light solvent, used fuel oil, light extract, and heavy extract, as described above. At 306, a used oil composite byproduct is formed by blending a portion of the light solvent, a portion of the used fuel oil and a portion of the light extract. For example, metered quantities of each of the respective portions is flowed to a storage tank by flow control equipment. At 308, a mixer can be implemented to mix the metered quantities to form the refined fuel oil blend. As described above, the refined fuel oil comprises of heavier hydrocarbons while the refined fuel oil blend comprises comparatively lighter hydrocarbons.

In one example, 5% by volume of the used oil composite byproduct 120 can be added to 95% by volume of the refined fuel oil 216. The concentration can be varied depending, for example, on the sulfur content in the refined fuel oil and the desired sulfur content in the blend of the refined fuel oil and the used oil composite byproduct. For example, the concentrations can be chosen based on desired properties of bunker grade

As described above, the refined fuel oil 216 is blended with cutter stock (e.g., diesel cutter stock) 208 that serves to reduce a viscosity of the refined fuel oil blend. In some implementations, a quantity of the cutter stock 208 blended with the refined fuel oil 216 can be reduced based on a quantity of the portion of the used oil composite byproduct 120 blended with the refined fuel oil 216. For example, the quantity of the cutter stock 208 reduced can equal the quantity of used oil composite byproduct 120 added (i.e., a ratio of 1:1). In other examples, the ratio can vary from 1:1 based on properties of the used oil composite byproduct.

In some implementations, the used oil composite byproduct 120 can be treated before being added as a viscosity reducer to the fuel oil. For example, one or more of the components blended to form the used oil composite byproduct 120 can include trace metals. Before being added to the fuel oil 216, a quantity of trace metals in the used oil composite byproduct 120 can be adjusted (e.g., by filtration). The filtration can be conducted at ambient temperature with moderate pressure that can be fine-tuned. Particles size distribution can be in the micro-level with target under 4 micrometer pore size, using porous metal filter cartridges in a filtration vessel.

FIG. 4 is a flowchart of an example of a process 400 of preparing a final fuel oil blend using used oil composite byproduct of used lube oil re-refining process 104. All or portions of the process 400 can be performed by the process systems described with reference to FIG. 1 or 2 or both. At 402, crude oil is refined in a hydrocarbon refinery to produce fuel oil, which is a byproduct of refining the crude oil. At 404, the fuel oil is flowed to a fuel oil reservoir. At 406, the used lube oil feedstock is re-refined to form multiple re-refined byproducts. The byproducts include light solvent, used fuel oil, light extract, and heavy extract. At 408, the light solvent, the used fuel oil and the light extract are mixed to form a used oil composite byproduct. The refined fuel oil to which the used oil composite byproduct is added includes heavier hydrocarbons than the light solvent and the light extract. At 410, the used oil composite byproduct is flowed to the fuel oil reservoir to mix with the portion of the fuel oil to form a final refined fuel oil blend.

In some implementations, the crude oil is refined in the hydrocarbon refinery to also produce diesel cutter stock 208, which can decrease a viscosity of the fuel oil 216. A portion of the diesel cutter stock 208 is flowed to the fuel oil reservoir 216. The diesel cutter stock 208 is used to reduce the viscosity of the fuel oil 216. A quantity of the diesel cutter stock 208 flowed to the fuel oil reservoir 216 can be decreased based on a quantity of the used oil composite byproduct 120 flowed to the fuel oil reservoir 216. In some implementations, a quantity of trace metals in the used oil composite byproduct 120 can be adjusted before flowing the used oil composite byproduct 120 to the fuel oil reservoir 216. As described earlier, such adjusting can be performed by filtration.

EXAMPLES

The table below shows quality parameters. ASTM D refers to standardized tests that were conducted to test each parameter. Unit refers to the unit of measurement for each parameter. The quality parameters were determined for certain byproducts produced when re-refining used oil (namely, light solvent, used fuel oil, light extra fraction and heavy extra fraction). The quality parameters were also determined for a used composite byproduct formed by blending certain byproducts of re-refining used oil, as described above. The quality parameters were further determined for fuel oil. Lastly, the quality parameters were determined for a reformulated fuel oil blend, which included 5% by volume of the used composite byproduct and 95% of the fuel oil.

				USED			USED OIL		FINAL
			LIGHT	FUEL	LIGHT	HEAVY	COMPOSITE	FUEL OIL	FUEL OIL
	ASTM		SOLVENT	OIL	EXTRACT	EXTRACT	BYPRODUCT	(BLENDING	BLEND
PARAMETERS	D	UNIT	112	118	114	116	120	COMPONENT)	216
Appearance	Visual	—	Clear to	Brownish	Black	Black	Black	Black	Black
			Amber	Liquid	Liquid	Liquid	Liquid	Liquid	Liquid
			Liquid
Density @ 15 C	1298	kg/L	0.760-0.800	0.820-0.870	0.870-0.910	0.890-1.0500	<0.900	1.029	Max 0.991
Flash Point	93	° C.	<10	60 Min	60 Min	250 Min	Min 40	>200	Min 60
Pour Point	97	° C.	—	—	—	—	<1	>50	Max 5
									(Winter)-
									Max 24
									(Summer)
Kinematic	445	cSt	0.5-1.5	3.0-6.0	40-150	>100000	<75	99395	Max 380
Viscosity @ 50 C
Conradson	189	Wt	0.05	—	—	>22	6.5	21.7	Max 18
Carbon Residue		%
Sulphur Content,	4294	Wt	Max 0.5	Max	<0.9	<2.5	<0.75	4.34	Max 3.5
Max		%		0.5
Water Content	95	Vol	<0.5	<0.3	<0.3	<0.3	<0.1	—	Max 0.50
		%
Sediments	4007	Vol					2.5	—	Max 0.1
		%
Calorific value,	4868	BT	18000	18000	17104		18660	—	18637
Min		U/lb
Distillation
Boiling Ranges
Initial Boiling		° C.	54	160	>180	550+	150.0	550+	150
Point (IBP)
Flash Boiling		° C.	277	<500	680		640.0	—	700
Point (FBP)

In addition, the fuel oil blend identified in the table above was thermally stressed at 100° C. to simulate accelerated conditions for instigating instability, and indicated no signs of incompatibility and instability issues. In addition, the fuel oil blend exhibited homogenous spot with no inner ring as Spot Rating 1 using the standard test method ASTM 4740.

Embodiments

Certain aspects of the subject matter described here can be implemented as a method to reformulate a fuel oil blend. Used lube oil feedstock, which is produced as a byproduct of refining crude oil, is received. The used lube oil feedstock is re-refined to form multiple re-refined byproducts including light solvent, used fuel oil, light extract, and heavy extract. A used oil composite byproduct is formed by blending a portion of the light solvent, a portion of the used fuel oil and a portion of the light extract. A portion of the used oil composite byproduct is blended with refined fuel oil to reformulate a final refined fuel oil blend. The refined fuel oil to which the portion of the used oil composite byproduct is added includes heavier hydrocarbons than the used oil composite byproduct.

An aspect combinable with any other aspect includes the following features. The refined fuel oil is blended with cutter stock configured to reduce viscosity of the refined fuel oil blend.

An aspect combinable with any other aspect includes the following features. A quantity of the cutter stock blended with the refined fuel oil is reduced based on a quantity of the portion of the used oil composite byproduct blended with the refined fuel oil.

An aspect combinable with any other aspect includes the following features. A quantity of trace metals in the portion of the used oil composite byproduct is adjusted before blending the portion of the used oil composite byproduct with the refined fuel oil to form the final refined fuel oil blend.

An aspect combinable with any other aspect includes the following features. The quantity of trace metals is adjusted by filtering the trace metals from the portion of the used oil composite byproduct.

An aspect combinable with any other aspect includes the following features. To blend the portion of the used oil composite byproduct with the refined fuel oil, 5% by volume of the used oil composite byproduct is blended with 95% by volume of the refined fuel oil.

Certain aspects of the subject matter described here can be implemented as a method to make a fuel oil blend. Crude oil is refined in a hydrocarbon refinery to produce fuel oil. A portion of the fuel oil is flowed to a fuel oil reservoir. The used lube oil feedstock is re-refined to form multiple re-refined byproducts including light solvent, used fuel oil, light extract and heavy extract. The light solvent, the used fuel oil and the light extract are mixed to form a used oil composite byproduct. The used oil composite byproduct is flowed to the fuel oil reservoir to mix with the portion of the fuel oil to form a refined fuel oil blend.

An aspect combinable with any other aspect includes the following features. The fuel oil to which the used oil composite byproduct is added includes heavier hydrocarbons than the light solvent and the light extract.

An aspect combinable with any other aspect includes the following features. The crude oil is refined in the hydrocarbon refinery to produce diesel cutter stock configured to decrease a viscosity of the fuel oil. A portion of the diesel cutter stock is flowed to the fuel oil reservoir.

An aspect combinable with any other aspect includes the following features. A quantity of the diesel cutter stock flowed to the fuel oil reservoir is reduced based on a quantity of the used oil composite byproduct flowed to the fuel oil reservoir.

An aspect combinable with any other aspect includes the following features. A quantity of trace metals in the used oil composite byproduct are adjusted before flowing the used oil composite byproduct to the fuel oil reservoir.

An aspect combinable with any other aspect includes the following features. To adjust the quantity of trace metals, the trace metals are filtered from the used oil composite byproduct.

An aspect combinable with any other aspect includes the following features. The portion of the fuel oil flowed to the fuel oil reservoir includes 5% by volume of the used oil composite byproduct.

An aspect combinable with any other aspect includes the following features. The portion of the used oil composite byproduct flowed to the fuel oil reservoir includes 95% by volume of the fuel oil.

Certain aspects of the subject matter described here can be implemented as a method to make a fuel oil blend. Crude oil is refined in a hydrocarbon refinery to produce fuel oil. The used lube oil feedstock is collected from collection storage intermediary facilities and is re-refined to produce re-refined base oil, residual water, and multiple byproducts including light solvent, used fuel oil, light extract, and heavy extract. The light solvent, the used fuel oil and the light extract are combined to form a used oil composite byproduct. The fuel oil and the used oil composite byproduct are combined to form a final refined fuel oil blend.

An aspect combinable with any other aspect includes the following features. Refining the crude oil in the hydrocarbon refinery produces fuel oil, and diesel cutter stock configured to decrease a viscosity of the fuel oil.

An aspect combinable with any other aspect includes the following features. The refined fuel oil includes a portion of the diesel cutter stock. The portion of the diesel cutter stock is combined with the fuel oil and the used oil composite byproduct to form the refined fuel oil blend.

An aspect combinable with any other aspect includes the following features. A quantity of the portion of the diesel cutter stock combined with the fuel oil and the used oil composite byproduct is reduced based on a quantity of the used oil composite byproduct being combined to form the refined fuel oil blend.

An aspect combinable with any other aspect includes the following features. A quantity of trace metals in the used oil composite byproduct is reduced before combining the fuel oil and the used oil composite byproduct.

An aspect combinable with any other aspect includes the following features. The refined fuel oil blend includes up to 5% by volume of the used oil composite byproduct.

Thus, particular implementations of the subject matter have been described. Other implementations are within the scope of the following claims.

Claims

1. A method to reformulate a fuel oil blend, the method comprising:

receiving used lube oil feedstock produced as a byproduct of refining crude oil;

re-refining the used lube oil feedstock to form a plurality of re-refining byproducts comprising light solvent, used fuel oil and light extract;

forming a used oil composite byproduct by blending a portion of the light solvent, a portion of the used fuel oil and a portion of the light extract; and

blending a portion of the used oil composite byproduct with refined fuel oil to reformulate a final refined fuel oil blend, wherein the refined fuel oil to which the portion of the used oil composite byproduct is added comprises heavier hydrocarbons than the used oil composite byproduct.

2. The method of claim 1, further comprising blending the refined fuel oil with cutter stock configured to reduce viscosity of the refined fuel oil blend.

3. The method of claim 2, further comprising reducing a quantity of the cutter stock blended with the refined fuel oil based on a quantity of the portion of the used oil composite byproduct blended with the refined fuel oil.

4. The method of claim 1, further comprising adjusting a quantity of trace metals in the portion of the used oil composite byproduct before blending the portion of the used oil composite byproduct with the refined fuel oil to form the final refined fuel oil blend.

5. The method of claim 4, wherein adjusting the quantity of trace metals comprises filtering the trace metals from the portion of the used oil composite byproduct.

6. The method of claim 1, wherein blending the portion of the used oil composite byproduct with the refined fuel oil comprises blending 5% by volume of the used oil composite byproduct with 95% by volume of the refined fuel oil.

7. A method to make a fuel oil blend, the method comprising:

refining crude oil in a hydrocarbon refinery to produce fuel oil which is a byproduct of refining the crude oil;

flowing a portion of the fuel oil to a fuel oil reservoir;

re-refining the used lube oil feedstock to form a plurality of re-refined byproducts comprising light solvent, used fuel oil, light extract, and heavy extract;

mixing the light solvent, the used fuel oil and the light extract to form a used oil composite byproduct; and

flowing the used oil composite byproduct to the fuel oil reservoir to mix with the portion of the fuel oil to form a refined fuel oil blend.

8. The method of claim 7, wherein the fuel oil to which the used oil composite byproduct is added comprises heavier hydrocarbons than the light solvent and the light extract.

9. The method of claim 7, further comprising:

refining crude oil in the hydrocarbon refinery to produce diesel cutter stock configured to decrease a viscosity of the fuel oil; and

flowing a portion of the diesel cutter stock to the fuel oil reservoir.

10. The method of claim 9, further comprising reducing a quantity of the diesel cutter stock flowed to the fuel oil reservoir based on a quantity of the used oil composite byproduct flowed to the fuel oil reservoir.

11. The method of claim 7, further comprising adjusting a quantity of trace metals in the used oil composite byproduct before flowing the used oil composite byproduct to the fuel oil reservoir.

12. The method of claim 11, wherein adjusting the quantity of trace metals comprises filtering the trace metals from the used oil composite byproduct.

13. The method of claim 7, wherein flowing the portion of the fuel oil to the fuel oil reservoir comprises flowing 5% by volume of the used oil composite byproduct to the fuel oil reservoir.

14. The method of claim 13, wherein flowing the used oil composite byproduct to the fuel oil reservoir comprises flowing 95% by volume of the fuel oil to the fuel oil reservoir.

15. A method to make a fuel oil blend, the method comprising:

refining crude oil in a hydrocarbon refinery to produce fuel oil and used oil;

re-refining the used oil to produce re-refined base oil, residual water, and a plurality of byproducts comprising light solvent, used fuel oil and light extract;

combining the light solvent, the used fuel oil and the light extract to form a used oil composite byproduct; and

combining the fuel oil and the used oil composite byproduct to form a refined fuel oil blend.

16. The method of claim 15, wherein refining the crude oil in the hydrocarbon refinery produces fuel oil, used oil and diesel cutter stock configured to decrease a viscosity of the fuel oil.

17. The method of claim 16, wherein the refined fuel oil comprises a portion of the diesel cutter stock, and the portion of the diesel cutter stock is combined with the fuel oil and the used oil composite byproduct to form the refined fuel oil blend.

18. The method of claim 17, further comprising reducing a quantity of the portion of the diesel cutter stock combined with the fuel oil and the used oil composite byproduct based on a quantity of the used oil composite byproduct being combined to form the refined fuel oil blend.

19. The method of claim 18, further comprising reducing a quantity of trace metals in the used oil composite byproduct before combining the fuel oil and the used oil composite byproduct.

20. The method of claim 19, wherein the refined fuel oil blend comprises up to 5% by volume of the used oil composite byproduct.