Process for Removing Nickel and Vanadium From Hydrocarbons
Nickel and/or vanadium can be removed or transferred from a hydrocarbon phase to a water phase using an Extractant Composition selected from an isocyanate, a thiocyanate, a cyanides, mercaptides, nitrites, and mixtures thereof. The Extractant Composition may also include at least one mineral acid, a solvent, and other additives. The invention permits transfer of vanadium and nickel from a hydrocarbon into an aqueous phase with little or no hydrocarbon phase undercarry into the aqueous phase. The composition is particularly useful in treating crude oil.
Latest BAKER HUGHES INCORPORATED Patents:
This application claims priority from the U.S. Provisional Patent Application having the Ser. No. 60/887,262; which was filed on Jan. 30, 2007, the contents of which are incorporated herein by reference in their entirety.
FIELD OF THE INVENTIONThe present invention relates to a method for removing metals from hydrocarbons. The present invention particularly relates to removing vanadium and nickel from hydrocarbons.
BACKGROUND OF THE INVENTIONFor the purposes of the present application, the terms “hydrocarbon” and “hydrocarbons” mean the large class of organic compounds containing primarily carbon and hydrogen that are produced from crude oil; from coal, lignite, tar sands, and the like; from recycled hydrocarbons; and from biological sources such as bio-diesel and the like; as well as from other alternative energy sources.
The largest source of hydrocarbons currently used is crude oil. Crude oil is often contaminated with contamination coming from several sources, including, but not necessarily limited to:
Brine contamination as a result of the brine associated with the crude oil in the ground;
Minerals, clay, silt, and sand from the formation around the oil well bore;
Metals including calcium, zinc, silicon, nickel, sodium, vanadium, potassium, etc.;
Nitrogen-containing compounds such as amines used to scrub H2S from refinery gas streams in amine units, or from amines used as neutralizers in crude unit overhead systems, and also from H2S scavengers used in the oilfield; and
Iron sulfides and iron oxides resulting from pipeline and vessel corrosion during production, transport, and storage.
Nickel and vanadium can be a problem when present in hydrocarbons in at least two ways. First, both metals are toxic in humans. Ironically, both nickel and vanadium are also nutrients, but like many nutrients, they are toxic above a certain level or concentration. The tolerable upper intake level for vanadium is 1.8 mg of vanadium per day.
Toxicity has occurred in workers exposed to nickel dust or nickel carbonyl formed in refining. Increased risk of nasal and lung cancers was linked to occupational nickel exposure before current workplace safety standards were set. Environmental sources of lower levels of nickel include tobacco, dental or orthopedic implants, stainless-steel kitchen utensils and inexpensive jewelry.
Repeated exposures to nickel may lead to asthma and contact dermatitis, symptoms of which may worsen if the diet is high in nickel. The oral toxic dose is about 1000 times the amount consumed in food. Different chemical forms vary widely in toxicity. Excessive nickel in tissues is pro-oxidant (damaging chromosomes and other cell components) and alters hormone and enzyme activities, movement of ions through membranes, and immune function. These effects can change glucose tolerance, blood pressure, response to stress, growth rate, bone development and resistance to infection. Under some conditions, large amounts of nickel may precipitate magnesium deficiency or cause accumulation of iron or zinc.
The recommended Nickel content of Western self-selected and institutional diets ranges from 60 to 260 μg/day. If follows then that levels that are 1000 times this may be toxic and thus excess nickel may be undesirable in hydrocarbons, especially hydrocarbons that are used to prepare foods or prepare objects that will be in contact with foods.
Another way that nickel and vanadium may be a problem is undesired chemical reactions. For example, when crude oil is processed in a refinery, it is often put through fluidized bed reactors. Both nickel and vanadium can interact with certain catalysts, in some instances deactivating the catalysts. The costs associated with purchasing new catalysts or regenerating contaminated catalysts can be very high. Lost productivity of refinery units during the removal and replacement of spent catalysts is also a source of such undesirable costs. It follows therefore that it would be desirable in the art of making, selling, recycling, and using hydrocarbons to be able to remove as much vanadium and nickel as possible from the hydrocarbons. It would be particularly desirable in the art if an extractant composition (Extractant Composition) could be used that would facilitate the extraction or removal of nickel and vanadium from hydrocarbons while not complicating other processes related to the producing, selling, using and recycling of hydrocarbons.
SUMMARY OF THE INVENTIONIn one aspect, the invention is a process for removing nickel and vanadium from a hydrocarbon comprising admixing the hydrocarbon with an Extractant Composition and separating the Extractant Composition from the hydrocarbon.
In another aspect, the invention is a process for removing nickel and vanadium from a hydrocarbon comprising admixing the hydrocarbon with an Extractant Composition and separating the Extractant Composition from the hydrocarbon wherein the Extractant Composition includes water. In some embodiment of the invention, the process may also include one or more process steps wherein nickel and/or vanadium are isolated from the Extractant Composition.
In still another aspect, the invention is a process for removing nickel and vanadium from a hydrocarbon comprising admixing the hydrocarbon with an Extractant Composition and separating the Extractant Composition from the hydrocarbon wherein the Extractant Composition is selected from a the group comprising thiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixtures thereof.
In one embodiment of the invention, there is provided, in one form, a method of transferring nickel and vanadium from a hydrocarbon phase to a water phase involving adding to an emulsion of hydrocarbon and water, an effective amount of an Extractant Composition to transfer the nickel and vanadium from a hydrocarbon phase to a water phase. The emulsion is then resolved into a hydrocarbon phase and an aqueous phase, wherein at least a portion of the metals have been transferred to the aqueous phase.
In some embodiments, the invention may be practiced using at least one additional component that may be a hydrocarbon solvent, a corrosion inhibitor, a demulsifier, a scale inhibitor, metal chelants, wetting agents and mixtures thereof.
DETAILED DESCRIPTION OF THE INVENTIONIn the practice of the invention, a hydrocarbon is admixed with an Extractant Composition. The Extractant Composition includes a component selected from the group consisting of isocyanates, thiocyanates, cyanides, mercaptides, nitrites, and mixtures thereof. Isocyanates useful with the invention include, but are not limited to methylene diphenyidiisocyanate, toluene diisocyanate, and the like.
Thiocyanates useful with the invention include, but are not limited to potassium thiocyanates, sodium thiocyanates, ammonium thiocyanates, and mixtures thereof.
The process of the invention may be used with equipment that is dedicated to the process. However, in crude oil refineries and possibly other plants that prepare, process, or recycle hydrocarbons, there is a piece of equipment that is already in place that may be used with the process. This apparatus is known as a “Desalting Unit” and the process is known as “desalting.”
As already stated, hydrocarbons can be and often are contaminated with brine contamination, minerals, clay, silt, sand, calcium, zinc, silicon, nickel, sodium, vanadium, potassium, nitrogen-containing compounds such as amines and Iron sulfides and iron oxides. At least some of the materials are routinely removed using one or more desalting units. Such desalting is necessary prior to further processing to remove these salts and other inorganic materials that would otherwise cause fouling and deposits in downstream heat exchanger equipment and/or form corrosive salts detrimental to crude oil processing equipment.
In the refining of crude oil, desalting is often practiced as the resolution of the natural emulsion of water that accompanies the crude oil by creating another emulsion in which about 5 percent relative wash water is dispersed into the oil. The emulsion mix is directed into a desalter vessel containing a parallel series of electrically charged plates. Under this arrangement, the oil and water emulsion is exposed to the applied electrical field. An induced dipole is formed on each water droplet within the emulsion that causes electrostatic attraction and coalescence of the water droplets into larger and larger droplets. Eventually, the emulsion resolves into two separate phases; the oil phase (top layer) and the water phase (bottom layer). The streams of desalted crude oil and effluent water are separately discharged from the desalter.
The entire desalting process is a continuous flow procedure as opposed to a batch process. Normally, chemical additives are injected before or concurrently with mixing to help resolve the oil/water emulsion in addition to the use of electrostatic coalescence. These additives effectively allow small water droplets to more easily coalesce by lowering the oil/water interfacial tension.
Crude oil that contains a high percent of particulate solids can complicate the desalting process. The particulate solids, by nature, would prefer to transfer to the water phase. However, much of the solids in a crude oil exist in tight water-in-oil emulsions. That is, oil-wetted solids in high concentration in the crude may help form tight oil and water emulsions that are difficult to resolve. These tight emulsions are often referred to as “rag” and may exist as a layer between the separated oil and water phases. The rag layer inside the desalter vessel may grow to such an extent that some of it will be inadvertently discharged with the water phase. This may be a problem for the waste water treatment plant since the rag layer still contains a high percentage of unresolved emulsified oil.
Much of the solids encountered during crude oil desalting consist of iron, most commonly as particulate iron such as iron oxide, iron sulfide, etc. Other metals that are desirably removed include, but are not necessarily limited to, calcium, zinc, silicon, nickel, sodium, potassium, and the like, and typically a number of these metals are present. Some of the metals may be present in a soluble form. The metals may be present in inorganic or organic forms. In addition to complicating the desalter operation, iron and other metals are of particular concern to further downstream processing. This includes the coking operation since iron and other metals remaining in the processed hydrocarbon yields a lower grade of coke. Removing the metals from the crude oil early in the hydrocarbon processing stages is desired to eventually yield high quality coke as well as to limit corrosion and fouling processing problems.
Several treatment approaches have been made to reduce total metal levels and these all center on the removal of metals at the desalter unit. Normally, the desalter only removes water soluble inorganic salts such as sodium or potassium chlorides. Some crude oils contain water insoluble metal organic acid salts such as calcium naphthenante and iron naphthenante, which are soluble or dispersed as fine particulate matter in the oil but not in water.
In the practice of the process of the present invention, it would be desirable to use an Extractant Composition that allows for the removal of nickel and vanadium, but does not otherwise complicate desalter or other separation device operations. For example, the Extractant Compositions of the present invention do not cause excessive oil carry-under in the aqueous phase within a desalter.
In the process of the present invention, the addition of an Extractant Composition to a crude oil can significantly reduce the amount of nickel and vanadium in the hydrocarbon when it is run through a desalter in a refinery.
In one embodiment of the invention, the Extractant Composition is an aqueous additive. Being an aqueous additive, the Extractant Composition is typically added to the wash water in the desalter. This improves distribution of the Extractant Composition in the oil although addition to the aqueous phase, but it should not be viewed as a requirement for the composition of the invention to work.
It is contemplated and within the scope of the disclosure and claims of this application that the Extractant Compositions will be used together with and/or include other components including, but not necessarily limited to, corrosion inhibitors, demulsifiers, pH adjusters, metal chelants, scale inhibitors, hydrocarbon solvents, and mixtures thereof. Metal chelants are compounds that complex with metals to form chelates. Mineral acids may be used in some applications since metal removal may sometimes best be accomplished at an acidic pH. Suitable mineral acids for use with the process of this invention include, but are not necessarily limited to, sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, phosphorous acid, and mixtures thereof.
In one embodiment of the invention, the method of this invention is practiced in a refinery desalting process that involves washing the crude emulsion with wash water. In one non-limiting embodiment of the invention, the amount of mineral acid used may be sufficient to lower the pH of the wash water to 10 or below. In some embodiments of the invention, it may be necessary or preferred to lower the pH of the wash water to 8 or below, alternatively to 6 or below.
It will be appreciated that the necessary, effective, or desired proportions of the Extractant Composition will be difficult to predict in advance, since proportions or dosages may be dependent upon a number of factors, including, but not necessarily limited to, the nature of the hydrocarbon, the concentration of nickel and/or vanadium to be removed, the temperature and pressure conditions of the process, the particular Extractant Composition and mineral acid used, etc. In general, the more metal there is to be removed, the more of the Extractant Composition that must be added.
One of ordinary skill in the art of producing, using and/or recycling hydrocarbons will be well skilled in selecting optimum level of Extractant Composition to add. Still, generally, the extractant compositions useful with the present invention will be used in a concentration relative to the water used in the process of from about 30 to about 10,000 ppm in one embodiment. In another embodiment, they will be used at a concentration of from about 75 to about 5000 ppm. In still another embodiment, they will be used at a concentration of from about 100 to 1000 ppm.
When practiced in a desalter, the Extractant Composition of this invention is injected into the wash water before the mix valve in neat form or diluted with water, alcohol or similar solvent suitable to keep all additive components in solution. The amount of solvent used may range from about 10 to about 95 wt. %, based on the total composition, preferably from about 50 to about 10 wt. %.
The concentration of the Extractant Composition of this invention to be used in a hydrocarbon, such as crude oil, to be effective is very difficult to predict in advance since it depends on multiple, interrelated factors including, but not limited to, the composition of the crude, the desalting conditions (temperature, pressure, etc.), the flow rate of the crude and its residence time in the desalter, among others. Nevertheless, for the purposes of non-limiting illustration, the proportion of the Extractant Composition that may be used in the hydrocarbon (not including any solvent or mineral acid) may range from about 1 to about 8000 ppm-w, more preferably from about 10 to about 1000 ppm-w and will depend on the concentration of metal species to be removed. While the process of the invention may be used to remove 90 greater percent (substantially all) of the nickel and vanadium present, for economic reasons a refinery or other practitioner may chose to leave some of the metals in the hydrocarbon at an acceptably low level of contamination. In those cases the treatment level can be correspondingly reduced.
It is most preferred, of course, that in the practice of this invention there be no oil carryunder in the aqueous phase, or that oil carry-under is at least minimized. Further, while it is preferred that all of the nickel and/or vanadium transfers to the aqueous phase, in one non-limiting theory of the invention, some of the metals may be transferred from the oil phase into the rag. This proportion of metals and/or amines is then removed when the rag is cleaned out.
It is preferred, of course, in most embodiments of the invention, that in the practice of this invention, all of the nickel and vanadium transfer from a hydrocarbon to an aqueous phase. In another non-limiting embodiment of the invention, 90 percent or less of the vanadium and nickel are removed. In still another embodiment, 50 percent or even 20% or less of the nickel and vanadium are removed. In some cases the refinery may chose to leave higher percentages of the metals in a hydrocarbon if the detrimental effects are judged to be economically acceptable.
While a desalter in an oil refinery can be a desirable location in which to practice the method of the invention, any apparatus that allows for the admixing of an Extractant Composition with a hydrocarbon followed by resolving the hydrocarbon and Extractant Composition admixture into a hydrocarbon stream and an aqueous stream may be used. For example, a dedicated wash vessel can be used to extract nickel and vanadium from hydrocarbons.
In a dedicated vessel, the Extractant Composition is admixed with a hydrocarbon. In one embodiment, the Extractant Composition is admixed first with the hydrocarbon and then the hydrocarbon and Extractant Composition is then admixed with water to form an emulsion and then resolved into a hydrocarbon phase and an aqueous phase. The Extractant Composition and at least some of the nickel and vanadium present in the hydrocarbon, are then present in the aqueous phase.
In another embodiment, the Extractant Composition is present in the water prior to admixing the water with the hydrocarbon. Embodiments where the Extractant Composition is present in both the water and the hydrocarbon, as well as where the Extractant Composition is essentially a third feed component are also within the scope of the invention. In any of these embodiments, other additives and processes may be used to assist in first forming an emulsion and then in resolving the emulsion into an aqueous phase and a hydrocarbon phase.
In one embodiment of the invention, the nickel and vanadium removed from a hydrocarbon may be recovered for use or sale. These metals may be recovered from the aqueous solution by any suitable technique. Exemplary techniques include, but are not limited to, resin adsorption methods such as resin-in-pulp, resin-in-solution, and resin-in-leach; solvent extraction; cementation; electrolysis; precipitation; and/or combinations of two or more of these techniques.
The invention will be illustrated further with reference to the following Examples, which are not intended to limit the invention, but instead illuminate it further.
The following Electrostatic Desalting Dehydration Apparatus (EDDA) Test Method was employed to evaluate compounds as Extractant Compositions. The EDDA is a laboratory test device to simulate the desalting process.
EDDA Test Method
- 1. Add 800, 600 or 400 ml of crude oil to be tested minus the percent of wash water (depending on the number of tubes the EDDA will hold) to a Waring blender.
- 2. Add the required percentage of wash water to the blender to bring the total volume up to 800, 600 or 400 ml.
- 3. Mix at 50% speed (on the Variac) for 30 seconds. The speed can be reduced if the ΔP on the mix valve is low.
- 4. Pour the mixture into the EDDA tubes to just below the 100 ml line.
- 5. Place the tubes in the EDDA heating block that is at the desired test temperature (99° C.).
- 6. Add the desired quantity of demulsifier, in ppm, to each tube. With every test, a blank must be run for comparison purposes.
- 7. Place the screw top electrode in the tubes and allow the samples to heat for approximately 15 minutes.
- 8. Tighten the caps and shake each tube 100-200 times and place back in the heating block to reheat for five minutes.
- 9. Place the electrode cover over the tubes and lock into place. Make sure that there is good contact between the cover and the electrode caps.
- 10. Set the time for five minutes and run at 1500-3000 volts, depending on the test requirements.
- 11. At the end of the five minutes, pull the tubes out and check for the percent water drop. Also check the quality of the interface and the quality of the water and record it.
- 12. Repeat steps 9, 10, and 11 until the desired total residence time is achieved.
- 13. Determine the best candidates and run a dehydration test on those samples.
- a) Fill the desired number of 12.5 ml centrifuge tubes to the 50% mark with xylene.
- b) Use a glass syringe to pull 5.8 ml of dehydrated crude sample from the desired level in the tube and mix in with the xylene in the centrifuge tubes.
- c) Centrifuge the tubes at 2000 rpm for 4 minutes.
- d) Check for the quantity of water, emulsion, and solids that are present in the bottom of the tube and record.
An EDDA test, as set forth above, is conducted using North African Crude Oil as the hydrocarbon and with the wash water level in Step 2 being 5%. The Extractant Composition is incorporated into the wash water at the concentrations shown in the Table. The test is conducted using a blank as a control and the materials shown in the Table as Extractant Compositions.
After completing the EDDA test, the EDDA desalted hydrocarbon is tested for nickel and vanadium. Test results are shown below in the Table.
The results shown above in the Table demonstrate that the toluene diisocyanate and potassium thiocyanate, when used as the Extractant Composition of the invention, are effective in causing a substantial reduction in the concentration of vanadium and nickel in North American Crude Oil samples.
Claims
1. A process for removing nickel and vanadium from a nickel and/or vanadium containing hydrocarbon (Hydrocarbon) comprising admixing the Hydrocarbon with an Extractant Composition and separating the Extractant Composition from the Hydrocarbon wherein some or substantially all of the nickel and/or vanadium is transferred from the Hydrocarbon to the Extractant Composition.
2. The process of claim 1 wherein Extractant Composition includes a compound selected from the group consisting of thiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixtures thereof.
3. The process of claim 2 wherein the Extractant Composition includes an isocyanate or a thiocyanate.
4. The process of claim 3 wherein the Extractant Composition includes toluene diisocyanate.
5. The process of claim 3 wherein the Extractant Composition includes potassium thiocyanate.
6. The process of claim 1 wherein the Extractant Composition includes water.
7. The process of claim 1 additionally comprising admixing with the Hydrocarbon at least one additional component selected from the group consisting of a hydrocarbon solvent, a corrosion inhibitor, a demulsifier, a scale inhibitor, metal chelants, wetting agents and mixtures thereof.
8. The process of claim 1 wherein the Hydrocarbon is in the form of a water and Hydrocarbon emulsion.
9. The process of claim 1 wherein the Hydrocarbon and Extractant Composition are admixed to form an emulsion.
10. The process of claim 1 wherein the Hydrocarbon and the Extractant Composition are separated using a Desalting Unit.
11. The process of claim 6 wherein the Extractant Composition includes a compound selected from the group consisting of thiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixtures thereof; at a weight concentration of from about 30 to 10000 ppm.
12. The process of claim 11 wherein the Extract Composition includes a compound selected from the group consisting of thiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixtures thereof; at a weight concentration of from about 75 to 5000 ppm.
13. The process of claim 12 wherein the Extract Composition includes a compound selected from the group consisting of thiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixtures thereof; at a weight concentration of from about 100 to 1000 ppm.
14. The process of claim 9 wherein the Extractant Composition is admixed neat with the Hydrocarbon and water emulsion.
15. The process of claim 9 wherein the Extractant Composition is admixed with the Hydrocarbon and water emulsion and wherein the Extract Composition includes a compound selected from the group consisting of thiocyanates, isocyanates, cyanides, mercaptides, nitrites, and mixtures thereof; dissolved in a solvent.
16. The process of claim 15 wherein a solvent is present in the Extractant Composition at a concentration of from about 10 percent to about 95 percent.
17. The process of claim 1 wherein the process is performed at a pH of less than or equal to about 10.
18. The process of claim 17 wherein the pH of water associated with the Hydrocarbon and/or the Extractant Composition is adjusted using a mineral acid.
19. A process for removing nickel and vanadium from a nickel and/or vanadium containing hydrocarbon (Hydrocarbon) comprising admixing the Hydrocarbon with an Extractant Composition and separating the Extractant Composition from the Hydrocarbon wherein some or substantially all of the nickel and/or vanadium is transferred from the Hydrocarbon to the Extractant Composition and further comprising isolating the nickel and/or vanadium from the Extractant Composition.
20. The process of claim 19 wherein the nickel and/or vanadium isolated from the Extractant Composition is recycled.
Type: Application
Filed: Jan 24, 2008
Publication Date: Jul 31, 2008
Applicant: BAKER HUGHES INCORPORATED (Houston, TX)
Inventors: Tran M. Nguyen (Houston, TX), Jerry J. Weers (Richmond, TX), Joseph L. Stark (Richmond, TX), Mark Richard Williams (Katy, TX)
Application Number: 12/019,276
International Classification: C10G 29/02 (20060101);
