WO2015021225A1

WO2015021225A1 - Delayed coking process using steamed additive

Info

Publication number: WO2015021225A1
Application number: PCT/US2014/050048
Authority: WO
Inventors: Jan Gijsbert MESU; Philip Andrew LANE; Ryan Ashley NICKELL
Original assignee: Albemarle Corporation
Priority date: 2013-08-09
Filing date: 2014-08-07
Publication date: 2015-02-12

Abstract

This invention relates to a coking process whereby an additive is introduced into a coking vessel above the vapor/liquid-solid interface. In particular, the invention relates to a coking process, whereby a specific steamed fresh additive is introduced into a coking vessel above the vapor/liquid-solid interface to increase the yield of highly desirable coking process products and/or reduce the yield of undesirable products. The steamed fresh additive is prepared by a process comprising the steps of: (i) preparing a composition comprising at least two of (a) a zeolite, (b) a clay and (c) a matrix, wherein said matrix is alumina, silica or mixtures thereof; (ii) shaping the composition to form particles; and (ii) heating said particles in the presence of steam to form the steamed fresh additive.

Description

DELAYED COKING PROCESS USING STEAMED ADDITIVE

TECHNICAL FIELD

This invention relates to a coking process whereby an additive is introduced into a coking vessel above the vapor/liquid- solid interface. In particular, the invention relates to a coking process, whereby a specific steamed fresh additive is introduced into a coking vessel above the vapor/liquid- solid interface to increase the yield of highly desirable coking process products and/or reduce the yield of undesirable products.

BACKGROUND

For many years, delayed coking units have played an important role in oil refineries as one of the most cost effective processes to convert vacuum residue into more valuable products. The delayed coking yields are the result of thermal reactions and mainly a function of feed properties and operating conditions such as furnace outlet temperature and drum pressure; however, this process generally results in less than about 40% coke yield based on feed and typically in coke yields from about 10-40% of feed.

WO2008/064162 discloses a process for introducing additives, such as catalysts, seeding agents, quenching agents, carrier fluids, or combination thereof, into a delayed coking vessel above the vapor/liquid-solid interface in order to increase the yield of desirable products.

However, there is a need to develop better additives for the above-identified process in order to further increase the yield or selectivity of desirable products and/or reduce the yield of undesirable products in the delayed coking process.

SUMMARY OF THE INVENTION

This invention relates to a coking process comprising the step of: introducing a steamed fresh additive into a coking vessel above or into a vapor/liquid- solid interface during a coking cycle of a delayed coking process; wherein said additive is prepared by a process comprising the steps of: preparing a composition comprising at least two of (a) a zeolite, (b) a clay and (c) a matrix, wherein said matrix is alumina, silica or mixtures thereof; shaping the composition to form particles; and heating said particles in the presence of steam to form a steamed fresh additive.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a coking process comprising the step of: introducing, or injecting a steamed fresh additive into a coking vessel above or into a vapor/liquid-solid interface during a coking cycle of a delayed coking process; wherein said additive is prepared by a process comprising the steps of: preparing a composition comprising at least two of (a) a zeolite, (b) a clay and (c) a matrix, wherein said matrix is alumina, silica or mixtures thereof; shaping the composition to form particles; and heating said particles in the presence of steam to form a steamed fresh additive.

The term "fresh additive" means an additive that has not been used, or substantially used, in refinery equipment, operations or processes prior to introduction into the coking vessel. Such refinery equipment, operations or processes, include, but are not limited to: a FCC unit or process, isomerization unit or process, alkylation unit or process, hydrocracking unit or process, hydroprocessing unit or process, or a coker unit or process.

In one embodiment of the present invention, the composition comprises clay and matrix. In another embodiment, the composition comprises zeolite and matrix and in yet another embodiment, the composition comprises zeolite, clay and matrix.

The matrix component may comprise silica, alumina or mixtures thereof. Any suitable silica or alumina material used in the refinery art may be used in the present invention for the matrix material.

Examples of suitable silicas that may be used include, but are not limited to: (poly) silicic acid, silica sol, potassium silicate, lithium silicate, calcium silicate, magnesium silicate, barium silicate, strontium silicate, zinc silicate, phosphorus silicate, borium silicate, polyorganosiloxanes, and mixtures thereof.

Examples of suitable alumina's that may be used include, but are not limited to: gibbsite, pseudoboehmite, micro-crystalline boehmite, diaspore, aluminum hydroxide, polyaluminum chlorides (e.g., aluminum chlorohydrol), aluminum sulfate, polyaluminum nitrates, aluminum nitrate and mixtures thereof.

As described above, the composition may comprise a clay component. Any suitable clay material used in the refinery art may be used in the present invention for the clay material, such as anionic or cationic clays. Groups of clays that may be used are kaolin- seprentine (e.g., kaloninite, berthierine), pyrophyllite-talc (e.g., pyrophyllite, talc), smectite (e.g., montmorillonite, saponite), vermiculite (e.g., di- and tri-vermiculite), micas (e.g., illite, muscovite and biotite), chlorite (e.g., sudoite, chamosite), sepiolite-palygorskite (e.g., sepiolite, palygorskite), and mixed layer clays (e.g., rectorite and corrensite).

Examples of preferred clays that may be used include, but are not limited to: kaolin (e.g., kaolinate, bentonite), saponite, sepiolite, attapulgite, laponite, hectorite, halloysite, imogolite or mixtures thereof.

The composition may also comprise a zeolite component. Any suitable zeolite material used in the refinery art may be used in the present invention.

Examples of suitable zeolites that may be used include, but are not limited to X- Zeolite, Y-zeolite, Ultra-stabilized Y zeolite, (USY), Rare earth exchanged Y zeolite, (REY), ZSM-5, ZSM-11 ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-41, ZSM-48, ZSM-50, ZSM-57, silicalite, mordenite, ferrierite, L-zeolite, zeolite beta, hexagonal faujasites, and hydrothermally, chemically modified zeolites and mixtures thereof.

The above-identified components (e.g., zeolite, clay, alumina and silica) may also be modified by acid or base washing or leaching. Examples of procedures that may be used to do such acid or base washing or leaching may be found in U.S. Patent Nos.: 8,486,369; 8,206,498 and 7,807,132, herein incorporated by reference.

In the embodiment where the composition comprises clay and matrix, the amount of clay may range from about 1 to about 99 wt , or from about 5 to about 95 wt , or from about 10 to about 90 wt , or from about 20 to about 80 wt , or from about 25 to about 75 wt ; and the amount of matrix may range from about 1 to about 99 wt , , or from about 5 to about 95 wt , or from about 10 to about 90 wt , or from about 20 to about 80 wt , or from about 25 to about 75 wt ; all based on the total weight of the clay and matrix.

In the embodiment where the composition comprises zeolite and matrix, the amount of zeolite may range from about 1 to about 99 wt , or from about 5 to about 95 wt , or from about 10 to about 90 wt , or from about 20 to about 80 wt , or from about 25 to about 75 wt ; and the amount of matrix may range from about 1 to about 99 wt , %, or from about 5 to about 95 wt , or from about 10 to about 90 wt , or from about 20 to about 80 wt , or from about 25 to about 75 wt ; all based on the total weight of the zeolite and matrix.

In the embodiment where the composition comprises zeolite, clay and matrix, the amount of zeolite may range from about 1 to about 90 wt , or from about 5 to about 90 wt , or from about 10 to about 90 wt , or from about 20 to about 80 wt , or from about 25 to about 75 wt ; the amount of clay may range from about 5 to about 90 wt , or from about 10 to about 90 wt , or from about 15 to about 85 wt , or from about 20 to about 80 wt , or from about 25 to about 75 wt ; and the amount of matrix may range from about 2 to about 70 wt , or from about 5 to about 70 wt , or from about 10 to about 70 wt , or from about 20 to about 60 wt , or from about 25 to about 60 wt ; all based on the total weight of the zeolite, clay and matrix.

Optionally, other components or materials may be added in the composition. Examples of such optional components include, but are not limited to: mineral acids, such as sulfuric acid, nitric acid, hydrofluoric acid, hydrochloric acid or phosphoric acid; organic acids such as citric acid, formic acid, lactic acid, ethylenediaminetertraacetic acid (EDTA) or acetic acid; inorganic bases such as ammonium hydroxide, calcium hydroxide, potassium hydroxide or sodium hydroxide; organic bases such as pyridines, methyl amines or imidazoles; barium titanate, calcium titanate, magnesium titanate, mixed metal oxides, layered hydroxy salts, magnesium oxide, and/or metal additives in the composition or the zeolite, wherein the metal additives are selected from the group consisting of alkaline earth metals, Group IIIA transition metals, Group IVA transition metals, Group VA transition metals, Group VIA transition metals, Group VIIA transition metals, Group VIIIA transition metals, Group IB transition metals, Group IIB transition metals, lanthanides and mixtures thereof.

The composition may be in form of a slurry, a paste, or another form that can be shaped into a particle. Preferably, the composition is in a form of a slurry.

The slurry may be prepared by suspending at least two components of clay, zeolite, and matrix in water. The optional components or materials may also be added. The components can be slurried by adding them to water as dry solids. Alternatively, slurries containing the individual materials are mixed to form the slurry. It is also possible to add some of the materials as slurries, some as solutions, and others as dry solids. The solids content of the slurry preferably is about 10 to about 60 wt%, or about 20 to about 50 wt%, or about 30 to about 45 wt%.

The pH of the slurry to be shaped preferably is above about 2.5, more preferably in the range of about 2.5 to about 9, and most preferably in the range of about 2.7 to about 7.

The slurry may be aged at a temperature of from about 20°C to about 100°C for a period of time (e.g., about 1 minute or about 5 minutes to about 1 day or about 5 days) prior to shaping.

Any suitable shaping method may be used to shape the composition in the form of a particle. Suitable shaping methods include spray-drying, pulse drying, freeze drying, pelletizing, extrusion (optionally combined with kneading), beading, or any other conventional shaping method used in the catalyst and absorbent fields or combinations thereof. A preferred shaping method is spray-drying. If the catalyst is shaped by spray-drying, the inlet temperature of the spray-dryer preferably ranges from about 300°C to about 600°C and the outlet temperature preferably ranges from about 90°C to about 200°C.

The shaped composition is in the form of particles, such as spherical, cone or rod shape particles. The average particle size of the particles to be shaped are in the range of about 40 to about 250 microns, or about 50 to about 200 microns, or about 75 to about 125 microns.

The particles may optionally be calcined either before or after the steam step described below. The calcination temperature preferably is in the range of about 120°C to about 1200°C, more preferably in the range of about 400°C to about 700°C. Calcination is preferably performed from about 5 minutes to about 24 hours, more preferably about 5 minutes to about 3 hours.

The particles are steamed to form the steamed fresh additive, whereby the particle are heated in steam with a steam partial pressure of from about 5% to about 100% or a steam partial pressure of from about 10% to about 100%, or a steam partial pressure of from about 20% to about 100%; at a temperature of from about 100°C to about 1000°C, or a temperature of from about 200°C to about 800°C, or a temperature of from about 300°C to about 700°C; for about 1 min to about 5 days, or from about 30 minutes to about 1 day or from about 1 hour to about 12 hours.

As will be described below in further detail, additives can be also be added before or after the steam step or the optional calcine step. For example, the shaped particles may be immersed in a protic liquid containing certain anions such as carbonates, bicarbonates, nitrates, chlorides, sulfates, bisulfates, vanadates, tungstates, borates, phosphates, formates, acetate, and mixtures thereof. It may also be desirable to have other additives both metals and non-metals, such as rare earth metals (especially Ce and La), Si, P, B, Group VI metals, Group VII metals, noble metals such as Pt and Pd, alkaline earth metals (for instance Mg, Ca, Sr and Ba) and/or transition metals (for example Mn, Fe, Ti, V, Zr, Cu, Cr, W, Pt, Ni, Zn, Mo, Sn). Said metals and non-metals can be added separately or in mixtures. Suitable sources of metals or non-metals are oxides, halides, or any other salt, such as chlorides, nitrates, phosphates, and the like. If the particles are optionally calcined, the particle may be rehydrated and the additional additives may be added during the rehydration step.

The steamed fresh additive is introduced or injected into a coking vessel above or into a vapor/liquid- solid interface during a coking cycle of a delayed coking process. Any suitable method may be used to introduce the additive into the coking vessel.

One method for introducing the additive into the coking vessel is an addition system using an additive mixture. The additive mixture is comprised of a liquid portion (the carrier) and the steamed fresh additive. The system comprises an additive vessel wherein the solid fresh steamed fresh additive is contacted with a carrier fluid or carrier oil and mixed under proper conditions to avoid solids settling. The additive mixture may then be pumped to the coking vessel through piping and introduced in the vessel via a spray nozzle to ensure a proper distribution, or substantially equal distribution, of the additive throughout the coking vessel.

EXAMPLES

A demonstration of the benefits of the present invention is provided here in the case of four examples, two fresh additives and the same two additives used after steaming, i.e., "steamed fresh additive". The data included here was collected using a pair of pilot-scale batch cokers widely used by the oil refining industry for pilot testing. Each coker in the system consists of a stainless steel reactor 3.0 inches in diameter and 72 inches in length. The reactor is hung vertically with the hot coker feed fed from the bottom. A single feed system supplies each coker and only one reactor can be in use at any time. The feed is preheated to 300 °C and continuously circulated. It is transferred to the reactor by a gear pump. All liquid or vapor products leave through the top of the reactor as a vapor stream. The final feed heater and the reactor are hung inside a six-zone insulated clamshell furnace which is used to maintain the various feed and reactor temperatures by PID control. When the temperature deviates from the target it is possible to adjust the coke yield based on an industry guideline published by Lieberman.[l] The pressure inside the drum is maintained by a back-pressure flow regulator. The feed is introduced to the reactor at a target rate of 3600 g/hr. Small amounts of antifoam were introduced to the reactor as necessary. A single experiment typically has feed flowing into the drum for between 3 and 5 hours. The length of any given experiment is dictated by the pressure drop across the coke bed and the height and density of the coke. Should none of the other factors terminate the run before 5 hours the run is stopped at that time. A 1 hour steam strip always occurs immediately after the feed flow is stopped and is finally followed by a water quench. The amount of coke produced is determined from the change in mass of the reactor when compared to its mass before the experiment began.

The additive is continuously mixed and circulated as slurry with heavy coker gas oil (HKGO). The additive makes up approximately 5 wt of the slurry. It is injected into the top of the reactor in 100 ms bursts using a custom made spray injection gun. The burst typically occur every 2 to 3.5 seconds depending on what is required to maintain the target injection rate for the run. A small burst of nitrogen accompanies each injection to atomize the spray. In the experiments reported the target was 288 g/hr of slurry. The mass of HKGO carrying the additive into the reactor is subtracted away from the liquid products before the final yields are calculated.

Example 1: Additive 1

Additive 1 was formed via spray drying and had a final composition of between 10- 30wt zeolite, 40-60wt matrix and 25-50 wt clay. A portion of Additive 1 produced was then steamed in a rotary calciner at >80 steam partial pressure and 785 °C wall temperature. The bed temperature was measured as approximately 650 °C and the additive was steamed for 2 hours. Both the fresh and steamed fresh additive were sieved to leave particles between 40 and 90 μιη in diameter. As a final step both additives were calcined at 615 °C overnight to remove any water loosely held by the additive.

The tests were run on two different coker units, Coker A and Coker B, so two control runs without additive are included for comparison. Each coker was given the same setpoints and approximately the same feed rate, but subtle differences can create enough variability that it is standard procedure to compare each experiment to a control case run on the same unit.

Data for Example 1

Coker Unit A B A B

Additive None None Fresh Steamed

Example type Control Control Comparison Inventive

Average Drum Pressure (psig) 35.9 36.0 36.0 36.0

Drum Inlet Feed Temperature (°F) 895 895 895 895

Average Drum Overhead Temperature (°F) 811 815 793 794

Feed Rate (g/hr) 3804 3615 3814 3766

Average additive slurry rate (g/hr) n/a n/a 285 291

Length of Time on Feed (min) 180 240 180 180

Coke Yield (wt%) 33.7 32.6 33.9 32.3

Change in Coke Relative to Base (wt ) n/a n/a +0.2 -0.3

Temperature Corrected Coke (wt ) n/a n/a 32.5 30.6

Temp. Corrected Change in Coke (wt ) n/a n/a -1.2 -2.0

Without compensating for temperature differences the use of the fresh additive has created slightly more coke, while use of the steamed fresh additive has led to a net reduction in the coke produced. When the runs with additive are corrected back to the overhead temperature of the base runs both additives reduce coke, but the steamed fresh additive reduces it by more. Example 2: Additive 2

Additive 2 was also formed via spray drying. The final composition of the particles was between 10-30 wt% zeolite, 15-40 wt% matrix, and 50-70 wt% clay. A portion of Additive 2 produced was then steamed in a rotary calciner at >80 steam partial pressure and 785 °C wall temperature. The bed temperature was measured as approximately 650 °C and the additive was steamed for 2 hours. Both the fresh and fresh steamed additive were sieved to leave particles between 40 and 90 μιη in diameter. As a final step both additives were calcined at 615 °C overnight to remove any water loosely held by the additive. These tests were run on the same coker, Coker Unit B, so only one control run without additive is included for comparison. Each test was given the same setpoints and approximately the same feed rate.

Data for Example 2

Coker Unit B B B

Additive None Fresh Steamed

Example type Control Comparison Inventive

Average Drum Pressure (psig) 36.0 36.0 36.0

Drum Inlet Feed Temperature (°F) 895 895 895

Average Drum Overhead Temperature (°F) 815 805 803

Feed Rate (g/hr) 3615 3748 3706

Average additive slurry rate (g/hr) n/a 277 280

Length of Time on Feed (min) 240 180 180

Coke Yield (wt%) 32.6 31.8 30.5

Change in Coke Relative to Base (wt ) n/a -0.8 -2.1

Temperature Corrected Coke (wt ) n/a 31.0 29.5

Temp. Corrected Change in Coke (wt ) n/a -1.6 -3.1

In the case of Additive 2 both the fresh and the steamed fresh additive has reduced the amount of coke produced, but the steamed additive has created a larger coke reduction. A greater coke reduction with fresh steamed additive is also seen when the coke yield is corrected based on the overhead line temperature.

References

[1] Lieberman, Norman, Good Operating Techniques Improve Coker Yield, Increase Gas-Oil Production, Oil & Gas J. (Mar. 10, 1986) 53-54.

Components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., another component, a solvent, or etc.). It matters not what chemical changes, transformations and/or reactions, if any, take place in the resulting mixture or solution as such changes, transformations, and/or reactions are the natural result of bringing the specified components together under the conditions called for pursuant to this disclosure. Thus the components are identified as ingredients to be brought together in connection with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense ("comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and/or ingredients in accordance with the present disclosure. The fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with ordinary skill of a chemist, is thus of no practical concern.

The invention described and claimed herein is not to be limited in scope by the specific examples and embodiments herein disclosed, since these examples and embodiments are intended as illustrations of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.

Claims

1. A coking process comprising the step of:

introducing a steamed fresh additive into a coking vessel above or into a vapor/liquid- solid interface during a coking cycle of a delayed coking process;

wherein said steamed fresh additive is prepared by a process comprising the steps of:

(i) preparing a composition comprising at least two of (a) a zeolite, (b) a clay and (c) a matrix, wherein said matrix is alumina, silica or mixtures thereof;

(ii) shaping the composition to form particles; and

(ii) heating said particles in the presence of steam to form the steamed fresh additive.

2. The process of claim 1, wherein said matrix comprises both silica and alumina.

3. The process of claim 1, wherein said composition comprises clay and matrix.

4. The process of claim 1, wherein said composition comprises zeolite and matrix.

5. The process of claim 1, wherein said composition comprises zeolite, clay and matrix.

6. The process of claim 1, wherein said clay is selected from the group consisting of: cationic clays, anionic clays and mixtures thereof.

7. The process of claim 1, wherein said clay is: kaolin, saponite, sepiolite, attapulgite, laponite, hectorite, halloysite, imogolite or mixtures thereof.

8. The process of claim 1, wherein said alumina is selected from the group consisting of: gibbsite, pseudoboehmite, micro-crystalline boehmite, diaspore, aluminum hydroxide, polyaluminum chlorides, aluminum sulfate, polyaluminum nitrates, aluminum nitrate and mixtures thereof.

9. The process of claim 1, wherein said silica is selected from the group consisting of (poly)silicic acid, silica sol, potassium silicate, lithium silicate, calcium silicate, magnesium silicate, barium silicate, strontium silicate, zinc silicate, phosphorus silicate, boron silicate, polyorganosiloxanes, and mixtures thereof.

10. The process of claim 1, wherein said zeolite is selected from the group consisting of: X- Zeolite, Y-zeolite, USY, Rare earth exchanged Y zeolite, (REY), ZSM-5, ZSM-11 ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-41, ZSM-48, ZSM-50, ZSM-57, silicalite, mordenite, ferrierite, L-zeolite, zeolite beta, hexagonal faujasites, and hydrothermally, chemically modified zeolites and mixtures thereof.

11. The process of claim 1, wherein said composition may further comprise: acids, bases, barium titanate, calcium titanate, magnesium titanate, mixed metal oxides, layered hydroxy salts, magnesium oxide, and/or metal additives in the composition or the zeolite, wherein the metal additives are selected from the group consisting of alkaline earth metals, Group IIIA transition metals, Group IVA transition metals, Group VA transition metals, Group VIA transition metals, Group VIIA transition metals, Group VIIIA transition metals, Group IB transition metals, Group IIB transition metals, lanthanides and mixtures thereof.

12. The process of claim 1, wherein the particles are heated in steam with a steam partial pressure between about 5% to about 100% and at a temperature between about 100°C to about 1000°C for about 1 min to about 5 days.

13. The process of claim 3, wherein the amount of said clay is about 1 wt % to about 99 wt%, and the amount of said matrix is about 1 wt % to about 99 wt%, based on the total weight of the clay and matrix.

14. The process of claim 4, wherein the amount of said zeolite is about 1 wt % to about 99 wt%, and the amount of said matrix is about 1 wt % to about 99 wt%, based on the total weight of the clay and matrix.

15. The process of claim 5, wherein the amount of zeolite is about 1 wt % to about 90 wt , the amount of clay is about 5 wt % to about 90 wt , and the amount of matrix is about 2 wt % to about 70 wt , based on the total weight of the zeolite, clay and matrix.

16. The process of claim 1 wherein the composition is in the form of a slurry and wherein the particles are shaped by spray-drying the slurry.

17. The process of claim 1, wherein said additive has an average particle size between about 40 to about 250 microns.