Patent Application
20230287273
The present disclosure generally relates to petroleum refinement, and more particularly relates to reducing foaming for delayed cokers.
Crude oil processing involves a wide variety of different processing steps to achieve all the different possible petroleum products, such as liquid petroleum gasses, lubricating oils, gasoline, naphtha, diesel, kerosene, coke, and a wide variety of additional products. Very broadly, major processing steps in oil refinement may include atmospheric distillation, vacuum distillation, and delayed coking. Delayed coking is a process in which residual oil from other refining processes may be thermally cracked to break long chain hydrocarbon residual oils into shorter hydrocarbon chain products, as well as petroleum coke. In very general terms, delayed coking may include heating the long chain hydrocarbon residual oils from other refining process to a temperature that will allow thermal cracking of the long chain hydrocarbons into shorter chain products. During the delayed coking process, the heated hydrocarbons injected into a coke drum may experience undesired foaming. Conventionally, silicone products have been utilized to control the undesired foaming. However, silicone products, such as polydimethylsiloxane (PDMS) may break down due to the high temperatures, and may contaminate the hydrocarbon liquid products recovered from the delayed coking unit. The contamination in the liquid products may additionally result in the contamination of catalyst that may be utilized for subsequent (e.g., post-delayed coking) refinement (e.g., so-called catalyst poisoning).
According to an implementation, a method of reducing foaming within a coke drum of a delayed coking unit is provided. The method may include forming a plastic mixture including a plastic material and a carrier. The method may further include injecting the plastic mixture into the coke drum during operation of the coke drum.
One or more of the following features may be included. Forming the plastic mixture may include at least partially dispersing the plastic material in the carrier. Forming the plastic mixture may include at least partially dissolving the plastic material in the carrier. Forming the plastic mixture may include combining the plastic material and the carrier using a high-shear mixer. The high-shear mixer may include a slotted rotor/stator high-shear mixer.
The plastic material may include one or more of: polyolefin, polystyrene, polyvinylchloride, waste tire scrap, polyethylene terephthalate, polyester, polyamide, acrylic, other plastic material, and mixtures thereof. The plastic material may include one or more of a virgin plastic material, a recycled plastic material, a post-consumer plastic material, and a combination of one or more thereof.
The carrier may include a hydrocarbon carrier. The carrier may include one or more of: light coker gas oil, heavy coker gas oil, pyrolysis fuel oil, diesel, naphtha, fluid catalytic cracker (FCC) slurry oil, decant oil, aromatic solvents, and combinations thereof. Forming the plastic mixture may include temperature controlling the carrier to an elevated temperature. The plastic mixture may include between about 0.5 wt. % to about 70 wt. % plastic material by weight of the total plastic mixture.
Injecting the plastic mixture into the coke drum may include injecting the plastic material into the coke drum via one or more of: an antifoam injection port; an antifoam quill, and an antifoam nozzle. Injecting the plastic mixture into the coke drum may include injecting the plastic material at rate of between about 5 wppm (weight parts per million) to about 200 wppm or greater of the total coker feedstock transferred to the coke drum.
According to another implementation, a method of reducing foaming within a coke drum is provided. The method may include providing a plastic material, and providing a carrier. The method may also include combining the plastic material and the carrier using a high-shear mixing. Combining the plastic material and the carrier may at least partially disperse the plastic material in the carrier. Combining the plastic material and the carrier may at least partially dissolve the plastic material in the carrier. The method may further include injecting the combined plastic material and carrier into the coke drum during thermal cracking of a coker feedstock.
One or more of the following features may be included. The method may also include heating the carrier to a temperature of greater than at least about 400° F. Heating the carrier may include heating the carrier prior to combining the plastic material and the carrier. Heating the carrier may include heating the carrier during high-shear mixing of the plastic material and the carrier. The plastic material may include one or more of: polyolefin, polystyrene, polyvinylchloride, waste tire scrap, polyethylene terephthalate, polyester, polyamide, acrylic, other plastic material, and mixtures thereof. The carrier may include one or more of: light coker gas oil, heavy coker gas oil, pyrolysis fuel oil, diesel, naphtha, fluid catalytic cracker (FCC) slurry oil, decant oil, and combinations thereof. Combining the plastic material and the carrier may include combining between about 0.5 wt. % to about 70 wt. % plastic material by weight of the total combined plastic material and carrier.
Injecting the combined plastic material and carrier into the coke drum includes injecting the plastic material at rate of between about 5 wppm (weight parts per million) to about 200 wppm or greater of the total coker feedstock transferred to the coke drum. Injecting the combined plastic material and carrier may include injecting the combined plastic material and carrier into the coke drum via one or more of an antifoam quill, and antifoam nozzle, and an antifoam port.
In general, the present disclosure relates to reducing and/or suppressing the occurrence and/or the degree of foaming that may occur in a coke drum of a delayed coker unit. In general, during a delayed coking process, heated coker feedstock may be introduced into a coke drum of the delayed coker unit. Thermal cracking of the coker feedstock may generally occur, at least in part, within the coke drum. During the thermal cracking process, long chain hydrocarbon coker feedstock may be broken down to produce shorter chain hydrocarbon products. Due to the elevated temperatures of the coker feedstock and/or within the coke drum, the shorter chain hydrocarbon products (which may be referred to herein as “coker products”, and e.g., which may be gaseous and/or liquid at standard temperature and pressure) may be released as vapors/in gaseous form. Depending upon the nature of the coker feedstock, the release of the coker products may result in foaming of the remaining material within the coke drum. Particularly as the coke drum begins to fill up with solid coke, foaming of the remaining liquid/semi-solid material in the coke drum may be problematic, as it may risk being carried from the coke drum along with the released coker products. Consistent with the present disclosure, such adverse foaming and/or foam-over may be prevented, suppressed, and/or reduced in magnitude.
Further, in some embodiments, the present disclosure may relate to reducing and/or suppressing the occurrence and/or the degree of foaming that may occur in a coke drum of a delayed coker unit, while reducing and/or eliminating the introduction of materials and/or substances that may have a negative impact on downstream processing of the coker products recovered from the delayed coking process. For example, in some embodiments, the present disclosure may eliminate and/or reduce the usage of silicone products, such as polydimethylsiloxanes, which may often be utilized in coker antifoaming applications. Accordingly, in some implementations the present disclosure may reduce and/or eliminate the introduction of silicone products into downstream refining operations of the coker products, which may, for example, contaminate catalysts used in the downstream refining operations, which could degrade the performance thereof. In some implementations consistent with the present disclosure, in addition to reducing and/or suppressing the occurrence and/or degree of foaming, the liquid yield of the delayed coking unit may be increased. Consistent with some general aspects of the present disclosure, a plastic mixture of a plastic material and a carrier may be utilized as a defoaming product within a coke drum of a delayed coker unit.
Consistent with an illustrative example embodiment, the present disclosure may provide a method of reducing and/or suppressing foaming within a coke drum of a delayed coking unit. The method may generally include forming a plastic mixture including a plastic material and a carrier. The plastic mixture may be injected into the coke drum during operation of the coke drum. For example, and referring to
The flow of feedstock 14 may be received at coker heater 12 and may be heated to a desired temperature. For example, as schematically depicted, the coker heater 12 may include one or more pipe runs (passes) through the heater, during which the coker feedstock may be heated to a desired temperature (e.g., which may be at and/or above a desired thermal cracking temperature for the feedstock). In some implementations, as generally shown, the coker heater 12 may include multiple discrete heater runs (passes), each of which may convey a respective stream of coker feedstock through the heater to be heated to the desired temperature. As also generally depicted, in some implementations, the coker heater may include various different sections (e.g., which may experience different heating temperatures and/or profiles). For example, the coker heater may include one or more convection heating sections and one or more radiant heating sections. It should be appreciated that the depiction of the convection heating section(s) and the radiant heating section(s) is intended for illustrative purposes, and is not intended to depict the relative location, size, and/or arrangement of the heating sections within the coker heater. As shown, in some implementations, heater runs (passes) within the different heater sections may be connected by one or more crossovers (e.g., crossover 20), which may allow coker feedstock to traverse from one heater section to another heater section (e.g., to be exposed to different heating temperatures and/or different heating profiles). While only one crossover is diagrammatically depicted, it will be appreciated that in some embodiments, each heater pass may include a separate crossover tube connecting heater passes in each of the various regions of the coker heater. According to some such implementations, the coker heater may include as many crossovers as passes in each respective region.
The coker feedstock, heated to a desired temperature for thermal cracking may be transferred from the coker heater 12 to a coke drum (e.g., coke drums 22a, 22b). Consistent with some implementations, the delayed coking process may generally include two, or more, coke drums, e.g., with one coke drum being online for receiving the heated coker feedstock, while the other coke drum may be offline for removal of accumulated coke, cleaning, etc. The coker feedstock received by the online coke drum may generally be cracked with vapor phase 24 (e.g., the coker products) being directed to the fractionator 16, and solid and/or liquid phases being collected in the coke drum. The vapor phase 24 may be separated in the fractionator 16 into various components, such as, but not limited to, gaseous phases 26, naphtha 28, LCGO (light coker gas oil) 30, HCGO (heavy coker gas oil) 32, and/or various additional and/or alternative products. It will be understood by those of skill in the art that the preceding depiction and description of a delayed coking configuration is intended for the purpose of illustration and that various additions, omissions, and/or alternations may be applied.
As generally discussed above, the release of the vapor phase coker products may result in foaming of the liquid and/or semi-solid material remaining within the coke drum 22a, 22b. Consistent with the present disclosure, the plastic mixture 34, including the plastic material and the carrier, may be injected into the active coke drum (e.g., coke drum 22a in the illustrated example embodiment). Consistent with the present disclosure, the injection of the plastic mixture into the coke drum may reduce and/or suppress the occurrence and/or the degree of foaming within the coke drum. Consistent with some such implementations, the vapor phase 24 may not be impacted by and/or entrained with the foaming residual material, and/or may be less impacted by and/or entrained with less of the foaming residual material. Additionally, reductions and/or suppression of foaming and/or degree of foaming of the residual material in the coke drum may influence the nature of the coke formed within the coke drum.
As discussed above, consistent with the present disclosure, a method of reducing foaming within a coke drum of a delayed coking unit may include forming a plastic mixture including a plastic material and a carrier. Accordingly, a plastic material may be provided for forming the plastic mixture. Consistent with various embodiments of the present disclosure, the plastic material may include a wide variety of different plastic materials. As used herein, plastic materials may generally refer to any polymeric materials. According to some implementations, the provided plastic material may include a non-silicone-based plastic material. Consistent with some such implementations, the likelihood and/or degree to which the coker products may be contaminated with silicone may be reduced (and/or at least minimally impacted by the provided plastic material), which may reduce the degree to which subsequent catalysts may be negatively affected (e.g., at least as compared to the usage of silicone-based antifoaming agents).
Consistent with various example embodiments, the plastic material may include a single plastic material and/or may include a mixture of different plastic materials. Further, consistent with various example embodiments, the provided plastic material may include a virgin material, a recycled plastic material, a post-consumer plastic material, and/or combinations thereof. Examples of suitable plastic materials may include, but are not limited to, one or more of: polyolefin (e.g., polyethylene, such as HDPE, LDPE, LLDPE, polypropylene, polyolefin elastomer, etc.), polystyrene, polyvinylchloride (e.g., which may include at least partially and/or fully dehydrochlorinated PVC, which may, in some embodiments, exhibit lower corrosivity and/or toxicity), waste tire scrap, polyethylene terephthalate (e.g., PET and/or PETE), polyester, polyamide, acrylic, other plastic materials, and mixtures thereof. Consistent with various embodiments, the plastic material may be provided having a variety of configurations, such as, but not limited to, fibers, pellets, granules, chunks, shredded material, flakes, and the like, as well as combinations thereof. Consistent with some embodiments, the plastic material may be provided having a size less than about 50 mm. In some embodiments, the plastic material may be provided having a size less than about 6 mm. However, it will be appreciated that the plastic material may be provided having different sizes and/or different configurations. The size and configuration of the plastic material may be selected based upon the type, configuration, and capacity of the equipment utilized for mixing the plastic material with the carrier, as discussed in greater detail below.
As noted above, the plastic mixture may additionally include a carrier. Consistent with some example embodiments, the carrier may include any suitable fluid that may at least partially dissolve the plastic material, and/or that may at least partially disperse the plastic material. Herein, the carrier may also be referred to as a “solvent,” whether the carrier actually dissolves the plastic material or whether the plastic material is only dispersed in the carrier. Consistent with some illustrative example embodiments, the carrier may include a hydrocarbon carrier, such as a hydrocarbon liquid or solvent. For example, in some embodiments, the carrier may include any suitable hydrocarbon fluid, mixture, and/or solvent that may be readily available in a refinery. Illustrative examples of suitable carriers may include, but not limited to, available feed or products from the delayed coker unit, such as, but not limited to, light coker gas oil, heavy coker gas oil. Additionally and/or alternatively, the carrier may include a hydrocarbon source from other units such as pyrolysis fuel oil, naphtha, diesel, fluid catalytic cracking (FCC) slurry oil, decant oil, other aromatic solvents and mixtures of any of these. In addition to the foregoing considerations, consistent with some implementations, selection of a carrier may also be based, at least in part, on the viscosity of the carrier, as well as the viscosity of the resulting plastic mixture.
The plastic material and the carrier may be combined to form the plastic mixture. Consistent with some example embodiments, combining the plastic material and the carrier may include at least partially dissolving and/or dispersing the plastic material in the carrier. Consistent with some such implementations, the plastic material and the carrier may be mixed using any suitable techniques and/or any suitable equipment, mechanisms, and/or process that may at least partially dissolve and/or at least partially disperse the plastic material in the carrier. For example, in an illustrative example embodiment, forming the plastic mixture may include combining the plastic material and the carrier using a high-shear mixer. For example, high-shear mixing equipment may be utilized in either an in-line continuous mixing process (e.g., in which the plastic mixture may be provided generally continuously) and/or a batch mixing process (e.g., in which the plastic mixture may be provided in batches, which may be subsequently utilized after formation of the batch of plastic mixture). Consistent with some example implementations, the high-shear mixing equipment may relatively rapidly achieve a generally and/or substantially homogeneous plastic mixture (e.g., with or without the need for additional mixing vessels). In some implementations, the plastic mixture may be achieved by processing liquid and solid material (e.g., which may respectively include, but is not limited to, the carrier and the plastic material) through a combination of high-speed slotted rotor/stator mixers which may generate relatively and/or very high hydraulic shear and moderate mechanical shear.
For example, and referring to
In some illustrative example embodiments, one or both of the plastic material and the carrier may be heated prior to and/or during mixing to form the plastic mixture. In some implementations, heating one or both of the plastic material and the carrier may facilitate forming the plastic mixture. For example, in one illustrative example embodiment, combining and/or mixing the plastic material and the carrier to form the plastic mixture may include temperature controlling the carrier to an elevated temperature. For example, the carrier may be heated to a temperature of greater than at least about 400° F. Further, in some particular embodiments consistent with the present disclosure, the carrier, at the inlet to the high-shear mixing equipment, may be a minimum temperature in the range of between about 400-450° F. (e.g., which may, in some embodiments, be dependent upon achieving a desired viscosity of the mixture). It will be appreciated that the temperature of the carrier, as provided at the inlet of the high-shear mixer for mixing with the plastic material, may be selected based upon, at least in part, the nature of the carrier, as well as the nature of the plastic material. For example, in some implementations, some hydrocarbon solvents that may be readily available in a refinery may become viscous below about 350° F. when mixed with plastic material as a carrier. The viscosity of such a plastic mixture may pose a problem, e.g., for pumping and/or otherwise conveying the plastic mixture to the coke drum, etc. Accordingly, in some such embodiments, the carrier may be mixed with the plastic material at a relatively higher temperature (e.g., between about 400-450° F.) at which the mixture may have a relatively lower viscosity that may facilitate efficient processing. As such, and as noted above, the temperature level may be based, at least in part, on the practicality of mixing the carrier and the plastic material in consideration of the viscosity of the mixture at various temperatures. As such the exact temperature level may vary depending upon the carrier and type of plastic material. Accordingly, it will be appreciated that in various embodiments, the temperature of the carrier, when mixed with the plastic material, may be less than about 400° F. and/or may be greater than about 450° F.
Continuing with the foregoing, and as generally suggest, consistent with various implementations the carrier and/or the plastic material may be heated to facilitate, at least in part, mixing of the plastic material and the carrier. Consistent with some example embodiments, heating the carrier may include heating the carrier prior to combining the plastic material and the carrier (e.g., prior to introduction of the carrier to the mixer). Further, consistent with some example embodiments, heating the carrier may include heating the carrier during high-shear mixing of the plastic material and the carrier. For example, in some embodiments the mixer may be heated, such that the carrier and/or the plastic material may be heated while undergoing mixing. Additionally and/or alternatively, the carrier and/or the plastic material may be heated, at least in part, through the mixing action, e.g., due at least in part the mechanical action of the mixing process and/or the shearing mechanics. Various additional and/or alternative implementations and combination may also be utilized.
The plastic mixture may include various concentrations of plastic material. In some implementations consistent with the present disclosure, the concentration of plastic material in the plastic mixture, and/or selection of the carrier, may be determined based on the design and/or circumstances of a given delayed coker unit, and/or a feedstock being processed by a delayed coker unit at a given time. For example, the concentration of the plastic material in the plastic mixture and/or the selection of the carrier may be based upon, at least in part, a foaming potential of the feedstock being processed in the delayed coking unit. For example, some coker feedstock makeups may be more prone to foaming, e.g., based on the various constituents of the feedstock and the relative ratios of the constituents. As such, the concentration of the plastic material in the plastic mixture may vary. Similarly, the particular carrier, and/or combinations of carriers, may also vary.
Consistent with the foregoing, in various implementations, the plastic mixture may include various concentrations of plastic material. Consistent with various example embodiments, the plastic mixture may include from between about 0.5 wt. % plastic to about 70 wt. % plastic of the total plastic mixture. Herein, the foregoing range is considered to include all subranges and individual weight percent contents of the plastic material, as a total of the material provided to the coke drum, within the identified range. Consistent with the foregoing, according to some implementations, the amount of plastic in the plastic mixture may be based upon, at least in part, the availability and type of carrier (e.g., the concentration of plastic material that may be at least partially dissolved and/or at least partially dispersed by the carrier), the availability and capability of equipment to combine the plastic material and carrier, the ability of the pumping and/or transit equipment of the delayed coker unit to process and/or pump the plastic material to the coke drum, as well as the foaming potential of the coker feedstock. Additionally, these factors may, at least in part, by impacted by the type of plastic material (e.g., with may impact the dissolution and/or dispersion of the plastic material in the carrier), the form of the plastic material (e.g., pellet, granule, fiber, flake, etc., which may also impact the dissolution and/or dispersion of the plastic material in the carrier), the size of the plastic pellets, granules, fibers, flakes, etc., as well as the mixing equipment utilized for forming the plastic mixture.
Consistent with the present disclosure, the plastic mixture may be injected into the coke drum during operation of the coke drum. That is, the plastic mixture may be injected into the coke drum before, during, and/or after coker feedstock is transferred to the coke drum. As such, the plastic mixture may be injected into the coke drum before foaming occurs, as foaming is occurring, and/or after a substantial degree of foaming has already occurred (e.g., as a result, at least in part, of the release of vapor components from the coker feedstock within the coke drum). Accordingly, in various implementations, the plastic mixture may be injected into the coke drum as a preventative measure, as an inhibiting measure, and/or as a curative or suppressive measure. It will be appreciated that the timing of the injection of the plastic mixture into the coke drum may desirably occur within a time frame that will allow the desired foaming prevention, suppression, and/or mitigation to occur. For example, if the plastic mixture is injected too soon before the coker feedstock is introduced into the coke drum, the plastic mixture may be diluted by the incoming coker feedstock, e.g., which may not be fully outgas sing vapor components, and may not have a fully desired impact. Similarly, if the plastic mixture is injected into the coke drum after a foam-over condition (e.g., point at which foaming may interfere with the overhead vapor passages) has arisen, the plastic mixture may suppress and/or decrease the foam-over condition, however it may be desirable to inject the plastic mixture in time to prevent the foam-over condition from occurring. However, while the timing of injection of the plastic mixture may be optimized for certain desired effects, it will be appreciated that injection of the plastic material at any various timing point may at least in part suppress, mitigate, and decrease the occurrence and/or degree of foaming in a desirable manner. Injection of the plastic mixture may also be continuous.
Consistent with the present disclosure, the plastic mixture may be injected into any suitable location within the coke drum. For example, coke drums may include various locations through which antifoaming agents may be injected, including, but not limited to, overhead locations (e.g., locations at or near the top of the coke drum) and/or locations at any point in the coke drum. As will be appreciated, such antifoam injection points may include, but are not limited to, locations from which the plastic mixture may be dispensed on top of any foam occurring in the coker feedstock within the coke drum. For example the plastic mixture may be injected into the coke drum via one or more of any existing or conventional antifoam injection port; an antifoam quill, and an antifoam nozzle. Additionally and/or alternatively, one or more special purpose injection points may be provided in the coke drum for injecting the plastic mixture.
Consistent with the present disclosure, the plastic mixture may be injected into the coke drum at any suitable rate. For example, as generally discussed above, different coker feedstocks may have different tendencies for foaming and/or may tend to foam to different degrees. The tendency and/or the degree of foaming may be based upon a variety of factors, including, but not limited to, the operating conditions of the delayed coker unit, the constituents of the coker feedstock, and the ratios of the constituents of the coker feedstock, as well as various additional and/or alternative factors. Accordingly, the plastic mixture may be injected into the coke drum at a variety of rates, depending upon such factors. Consistent with some illustrative example embodiments, injecting the plastic mixture into the coke drum may include injecting the plastic material at rate of between about 5 wppm (weight parts per million) to about 200 wppm or greater of the total coker feedstock transferred to the coke drum. That is, for example, the plastic material may make up between about 5 wppm of the total material provided to the coke drum to about 200 wppm or greater of the total material provided to the coke drum. Herein, the foregoing range is considered to include all subranges and individual weight percent contents of the plastic material, as a total of the material provided to the coke drum, within the identified range.
Consistent with a particular illustrative example embodiment, and referring to
While not intending to be limited to any particular mode, mechanism, or theory of operation, consistent with some implementations of the present disclosure, the addition of a plastic mixture to a coke drum may, consistent with some embodiments of the present disclosure, suppress foaming by, e.g., homogeneous and/or heterogeneous mechanisms including, but not limited to, tailoring the viscosity of the plastic mixture to achieve desired, partial, and/or maximum foam control. The reduction in foaming may, in some embodiments, be associated with the plastic materials cracking with faster kinetics than the other feedstock at equivalent temperatures (e.g., having much lower residence time in the drum), and not contributing to the formation of the highly viscous liquid mesophase (which may be a main player in the formation of stable reactive foams), as compared to typical delayed coker feedstocks. Accordingly, some possible benefits that may be recognized consistent with the present disclosure may include, but are not limited to:
Herein various embodiments, and implementations have been discussed, including a various individual features and combinations of features. It will be appreciated that various additional and/or alternative embodiments may be realized consistent with the foregoing description. For example, the features, aspects, advantages, and/or attributes of the variously described embodiments and implementations may be provided in combinations in addition to those specifically discussed. Similarly, various features, aspects, and/or attributes of one embodiment or implementation may be utilized in connection with one or more other embodiments and/or implementations. All such combinations and modifications are considered to be within the scope of the present disclosure. As such any inventive concepts herein should not be limited by the specifically described embodiments and implementations.
This application claims the benefit of U.S. provisional patent application Ser. No. 63/318,571, filed 10 Mar. 2022, entitled “PLASTIC SOLUTION BASED ANTIFOAMING FOR DELAYED COKER,” and claims the benefit of U.S. provisional patent application Ser. No. 63/318,558, filed 10 Mar. 2022, entitled “FOULING MITIGATION OF DELAYED COKER HEATERS BY PROCESSING PLASTIC SOLUTIONS,” the entire disclosures of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63318571 | Mar 2022 | US | |
| 63318558 | Mar 2022 | US |
