Patent Application
20250179376
The present disclosure relates to systems and methods for removing metals such as mercury from, for example, liquid hydrocarbons.
Current separation methods using additives to hydrocarbons unfortunately may not effectively eliminate mercury from hydrocarbons due to the presence of submicron particulate matter, elemental, ionic, or other dissolved forms of mercury. These prior art additives do not universally address all forms of mercury species found in crude oil, condensates, and other fluids. Additionally, there are limitations related to mass transfer that necessitate increased mixing intensity and extended residence time. As a result, significant mixing energy and time are often required to promote the reactions.
These and other deficiencies exist. Therefore, there is a need to provide systems and methods that overcome these deficiencies.
Aspects of the disclosed embodiments include systems and methods for removing mercury from a hydrocarbon mixture.
In one embodiment the present disclosure provides a system for removing mercury from a hydrocarbon mixture with an initial level of mercury. The system comprises one or more tanks comprising one or more chemical additives. The one or more chemical additives promote a chemical reaction within the hydrocarbon mixture to form a top layer comprising crude oil with a reduced mercury content relative to the initial level of mercury in the hydrocarbon mixture and a bottom layer comprising water and at least one mercury containing compound(s). A separator in the system is configured to separate the top layer from the bottom layer.
In another embodiment the present disclosure provides a method for removing mercury from a hydrocarbon mixture with an initial level of mercury. The method comprises introducing one or more chemical additives into the mixture to promote a chemical reaction and form a top layer comprising crude oil with a reduced mercury content relative to the initial level of mercury in the hydrocarbon mixture and a bottom layer comprising water and at least one mercury containing compound(s). The top layer is then separated from the bottom layer.
Further features of the disclosed systems and methods, and the advantages offered thereby, are explained in greater detail hereinafter with reference to specific example embodiments illustrated in the accompanying drawings.
To facilitate a fuller understanding of the present invention, reference is now made to the attached drawings. The drawings should not be construed as limiting the present invention but are intended only to illustrate different aspects and embodiments of the invention.
Exemplary embodiments of the invention will now be described to illustrate various features of the invention. The embodiments described herein are not intended to be limiting as to the scope of the invention, but rather are intended to provide examples of the components, use, and operation of the invention.
Furthermore, the described features and advantages of the embodiments may be combined in any suitable manner. One skilled in the art will recognize that the embodiments may be practiced without one or more of the features or advantages of an embodiment, and one skilled in the art will recognize the features or advantages of an embodiment can be interchangeably combined with the features and advantages of any other embodiments. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments.
The flowchart and block diagrams in the figures illustrate the functionality, and operation of possible implementations of systems, methods, and compositions according to various embodiments of the present invention. In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.
The invention relates generally to new systems and methods which use one or more chemical additives for removing mercury from hydrocarbons such as crude oil, condensates, slop oil, and other hydrocarbon liquids. These one or more additives may include:
In general, the process and system employ one or more chemical additives using 1) Chemical injection, 2) mixing and reacting, 3) separation.
The systems and methods may be employed on hydrocarbons wherever mercury is in need of reduction, e.g., at the wellhead or at any time thereafter. The systems and methods are applicable to hydrocarbon mixtures having an initial mercury level of more than about 100 ppb, or less than about 500, or less than about 300, or in some cases less than about 100 ppb. The systems and methods may also be applicable to, for example, high-mercury condensates and crude oil, exceeding 300, or exceeding 500, or exceeding 1000, or even up to 3000 parts per billion (ppb) or more.
In some embodiments one or more chemical additives may be introduced at the wellhead through either new or existing chemical injection ports. It has been discovered that adequate mixing and residence time for the one or more additives reacting with mercury can often take place within pipelines spanning over 1 kilometer. Mercury advantageously partitions from the hydrocarbons into the produced water phase. If desired, existing oil/water separation units can be employed to isolate the produced water, including the mercury. Subsequently, this mercury-laden produced water can be safely disposed of using any desired system including, for example, an existing produced water disposal well injection system. As a result of this treatment, the crude oil and condensate will advantageously comprise significantly lower levels of mercury. In some embodiments, mercury content may also be reduced in the gas phase.
In some embodiments, more additives may be introduced into the crude oil or wash water just before a hydrocarbon mixture enters a desalter utilizing new or existing ports for injection of the one or more additives. While specific configurations and steps may vary, if desired, the mixing of the additive with crude oil may occur at a desalter's mixing valve and separation may then occur in the desalter's separator. In this manner mercury will migrate from the crude oil into the rinse water. The rinse water, now having higher mercury content, may be disposed of in any convenient manner. In some embodiments the rinse water may proceed through the effluent treatment plant which may or may not have pre-existing water treatment systems to efficiently remove mercury. Mercury removal from the water may include using heavy metal precipitants like NALMET™ from Nalco, METCLEAR™ from Veolia, Na2S, general coagulants and flocculants like FeCl3, AlCl3, polymeric agents, or adsorbents such as activated carbon, functionalized activated carbon, or organoclays. The processed crude oil, now considerably reduced in mercury content, may be further processed as desired, e.g., via a crude distillation unit (CDU).
Subsequently, in action 210, one or more chemical additives are introduced into the mixture. Upon incorporation, these additives are configured to promote a chemical reaction with both the oil and the mercury, ultimately leading to the formation of two distinct phases: crude oil and an aqueous solution comprising water and mercury containing compounds. Following an appropriate period of thorough mixing, the crude oil, which now exhibits diminished levels of mercury, ascends to the uppermost layer within the container. Conversely, the water, enriched with higher levels of mercury, descends to the lower layer.
In action 215, once the separation process reaches a sufficient level of completion, the mixture can be segregated in a manner that isolates the crude oil with reduced mercury content from the water containing heightened levels of mercury. Several methodologies for achieving this separation exist, including but not limited to, employing bulk separators and desalter separators, or resorting to solid-liquid separation techniques like sedimentation, centrifugation, filtration, and flotation. Furthermore, established oil/water separation equipment such as inlet separators, sedimentation tanks, and other oil purification processes may also be utilized.
In certain embodiments, the mercury precipitates due to the presence of additives in a bulk hydrocarbon liquid, subsequently being removed through a solid-liquid separation process. In alternative embodiments, the mercury is extracted or precipitated by additives in a bulk aqueous phase, thereby transitioning from the bulk hydrocarbon liquid phase to the bulk aqueous phase. Lastly, in other distinct embodiments, the mercury may undergo extraction or precipitation, transitioning directly from the bulk hydrocarbon liquid phase to the aqueous phase.
The dosages of additives usually depends on the additive, the amount of mercury, and/or potentially the type of hydrocarbon present. Typically, the dosage range includes, but is not limited to, concentrations of less than 1,000 parts per million (ppm) in relation to the mixture of crude oil and water. In a series of conducted experiments described below, additives were administered into water at a concentration of 1,000 ppm. Subsequently, hydrocarbon feed, encompassing various forms such as crude oil, condensate, and slop oil, was mixed with the additive solution at a 1:1 volume-to-volume ratio for a duration of one hour. The resultant mixture was then allowed to undergo separation, with measurement of the total mercury content performed within both the hydrocarbon phase and a sample of the hydrocarbon phase, which had been subjected to filtration through a 0.45-micron filter.
In some embodiments such as when the process is being performed at a wellhead, the additives and water can be added to the hydrocarbons at the same time. In other embodiments, the water and the hydrocarbons may already be mixed, then the additives are added to the hydrocarbon and water mixture.
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In some aspects, the process described herein relate to a system for removing mercury from a hydrocarbon mixture including: one or more tanks; one or more chemical additives for facilitating a chemical reaction within the mixture, resulting in the formation of two distinct phases: a top layer of crude oil with reduced mercury content and a bottom layer of an aqueous solution containing water and mercury; and a separation means for isolating the top layer of crude oil with diminished mercury levels from the bottom layer containing water enriched with elevated levels of mercury
In some aspects, the process described herein relate to a system, wherein, said separation means including bulk separators, desalter separators, sedimentation, centrifugation, filtration, flotation, inlet separators, sedimentation tanks, or other established oil/water separation equipment.
In some aspects, the process described herein relates to a system, wherein the top layer of crude oil with reduced mercury content is collected in a dedicated storage tank.
In some aspects, the process described herein relate to a system, wherein the additives include at least one selected from the group of 6-mercapto-1-hexanol, thiosalicyclic acid/4-mercaptobenzoic acid, pentaerythritol tetrakis(3-mercaptopropionate), triethylene glycol, terephthalic acid, and cysteine.
In some aspects, the process described herein relate to a system, wherein the additives include at least one selected from the group of 2,2′-thiodiethanethiol, ethylene glycol bis-mercaptoacetate, 6-mercapto-1-hexanol, cysteine, 4-mercaptobenzoic acid, a glycol such as, for example, triethylene glycol, an organic acid such as, for example, terephthalic acid, and 2-Mercaptobenzothiazole.
In some aspects, the process described herein relates to a system, wherein one or more additives may be dosed into water at from at least about 10, or at least about 20, or at least about 50, up to about 100 ppm, or up to about 500, or up to about 800, or up to about 1000, or up to about 1200 ppm or higher.
In some aspects, the process described herein relates to a system, wherein the hydrocarbon mixture may be mixed with a chemical additive solution at about 1:1 vol/vol ratio for about 1 hr or more.
In some aspects, the process described herein relate to a system, wherein the hydrocarbon mixture separates in from about 5 minutes, or from about 30 minutes, up to about 1 hr, or up to about 24 hr.
In some aspects, the process described herein relates to a system, wherein the separation is performed by a 0.2-10 micron nominal filter.
In some aspects, the process described herein relate to a method for separating mercury from a mixture including hydrocarbons and mercury, including the steps of: introducing one or more chemical additives into the mixture, promoting a chemical reaction between the additives, hydrocarbons, and mercury, resulting in the formation of two distinct phases: a top layer of crude oil with reduced mercury content and a bottom layer of an aqueous solution containing water and mercury containing compound(s), mixing the additives and crude oil together; effecting separation of the mixture to isolate the top layer of crude oil with diminished mercury levels from the bottom layer containing water enriched with elevated levels of mercury, and removing the mercury from the mixture.
In some aspects, the process described herein relate to a method, wherein step of removing includes one or more separation methods which may include at least on selected from the group of bulk separators, desalter separators, sedimentation, centrifugation, filtration, flotation, or inlet separators.
In some aspects, the process described herein relate to a method wherein the method is used at or near a well head.
In some aspects, the process described herein relate to a method, wherein the additives include at least one selected from the group of 6-mercapto-1-hexanol, thiosalicyclic acid/4-mercaptobenzoic acid, pentaerythritol tetrakis(3-mercaptopropionate), and cysteine.
In some aspects, the techniques described herein relate to a method, wherein the additives include at least one selected from the group of 2,2′-thiodiethanethiol, ethylene glycol bis-mercaptoacetate, 6-mercapto-1-hexanol, cysteine, 4-mercaptobenzoic acid, and 2-Mercaptobenzothiazole.
In some aspects, the techniques described herein relate to a method, wherein the hydrocarbons include at least crude oil.
In some aspects, the techniques described herein relate to a method, wherein the separation is performed by a 0.45 micron filter.
In some aspects, the techniques described herein relate to a method, wherein the method is performed in one more tanks including at least one selected from the group of a ship cargo, FSO cargo, or OCP tank.
In some aspects, the techniques described herein relate to a method, wherein the mixture step is performed by a desalter mixer or a recirculating pump.
In some aspects, the techniques described herein relate to a method, wherein the water and the additives are added at the same time to the hydrocarbons.
In some aspects, the techniques described herein relate to a method for separating mercury from a mixture including hydrocarbons and mercury, including the steps of: introducing one or more chemical additives into the mixture; facilitating a chemical reaction between the additives, hydrocarbons, and mercury, resulting in the formation of two distinct phases: a top layer of crude oil with reduced mercury content and a bottom layer of an aqueous solution containing water and mercury; mixing the additives and crude oil together; and effecting separation of the mixture to isolate the top layer of crude oil with diminished mercury levels from the bottom layer containing water enriched with elevated levels of mercury.
Although embodiments of the present invention have been described herein in the context of a particular implementation in a particular environment for a particular purpose, those skilled in the art will recognize that its usefulness is not limited thereto and that the embodiments of the present invention can be beneficially implemented in other related environments for similar purposes. The invention should therefore not be limited by the above described embodiments, method, and examples, but by all embodiments within the scope and spirit of the invention as claimed.
Further, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms “a” or “an” as used herein, are defined as one or more than one. The term “plurality” as used herein, is defined as two or more than two. The term “another” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). The term “coupled,” as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. The term “providing” is defined herein in its broadest sense, e.g., bringing/coming into physical existence, making available, and/or supplying to someone or something, in whole or in multiple parts at once or over a period of time. Also, for purposes of description herein, the terms “upper,” “lower,” “left,” “rear,” “right,” “front,” “vertical,” “horizontal,” and derivatives thereof relate to the invention as oriented in the figures and is not to be construed as limiting any feature to be a particular orientation, as said orientation may be changed based on the user's perspective of the device.
In the invention, various embodiments have been described with references to the accompanying drawings. It may, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The invention and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.
The invention is not to be limited in terms of the particular embodiments described herein, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent systems, processes and apparatuses within the scope of the invention, in addition to those enumerated herein, may be apparent from the representative descriptions herein. Such modifications and variations are intended to fall within the scope of the appended claims. The invention is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such representative claims are entitled.
The preceding description of exemplary embodiments provides non-limiting representative examples referencing numerals to particularly describe features and teachings of different aspects of the invention. The embodiments described should be recognized as capable of implementation separately, or in combination, with other embodiments from the description of the embodiments. A person of ordinary skill in the art reviewing the description of embodiments should be able to learn and understand the different described aspects of the invention. The description of embodiments should facilitate understanding of the invention to such an extent that other implementations, not specifically covered but within the knowledge of a person of skill in the art having read the description of embodiments, would be understood to be consistent with an application of the invention.
