US20110308995A1

US20110308995A1 - Dual reactor for better conversion of heavy hydrocarbons

Info

Publication number: US20110308995A1
Application number: US12/816,844
Authority: US
Inventors: Jose Armando Salazar-Guillen; Christopher Ard
Original assignee: Marathon Oil Canada Corp
Current assignee: Marathon Oil Canada Corp
Priority date: 2010-06-16
Filing date: 2010-06-16
Publication date: 2011-12-22

Abstract

An improved hydrocarbon cracking process includes a first reactor such as a nozzle reactor positioned in series with a second reactor such as a tubular reactor. A cracking fluid such as steam or natural gas is reacted with heavy hydrocarbon material in the first reactor. The first reactor may provide a tremendous amount of thermal and kinetic energy that initiates cracking of heavy hydrocarbon materials. The second reactor provides sufficient residence time at high temperature to increase the conversion of heavy hydrocarbon materials to the desired level. The cracking fluid functions as a hydrogen donor in the cracking reactions so that very little of the heavy hydrocarbon material becomes hydrogen depleted and forms coke even if the heavy hydrocarbon material is repeatedly recycled through the process.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The entire contents of the following documents are incorporated by reference herein: U.S. Pat. No. 7,618,597, entitled “Nozzle Reactor and Method of Use,” issued on 17 Nov. 2009 (the '597 patent) and U.S. Patent Application Publication No. 2009/0266741, entitled “Nozzle Reactor and Method of Use,” published on 29 Oct. 2009 (the '741 publication). In the event of a conflict, the subject matter explicitly recited or shown herein controls over any subject matter incorporated by reference.

BACKGROUND

Since different crude oils yield different distillation products, oil refining requires balancing product yield with market demand. Balancing these two without manufacturing large quantities of low value fractions has long required processes for the conversion of hydrocarbons of one molecular weight range and/or structure into those of another molecular weight range and/or structure. The basic processes for this are the so-called cracking processes in which relatively high boiling constituents are cracked, that is, thermally decomposed, into lower molecular weight, smaller, lower boiling molecules.
Conventional thermal cracking is the thermal decomposition of high molecular weight constituents (higher molecular weight and higher boiling than gasoline constituents) to form lower molecular weight (and lower boiling) species. The earliest thermal cracking processes consisted of heating heavier oils (for which there was low market demand) in pressurized reactors and thereby cracking, or splitting, the large molecules into smaller ones that form the lighter, more valuable fractions such as gasoline, kerosene, and light industrial fuels.
The development of more powerful engines gave rise to a need to increase the combustion characteristics of gasoline to improve engine performance. Cracking processes were developed that used catalysts to improve the quality of transportation fuels and further increased their supply. These improved processes, including catalytic cracking of residual and other heavy feedstocks, alkylation, polymerization, and isomerization, enabled the petroleum industry to meet the demands of high performance engines and to supply increasing quantities of transportation fuels.
The continuing increase in demand for petroleum products also heightened the need to process a wider variety of crude oils into high quality products. Catalytic cracking is one of the leading processes for upgrading lighter oils (e.g., conventional crude oil) into high qualify fuel that meets the needs of higher compression engines. Hydrocracking, a catalytic cracking process conducted in the presence of hydrogen, was developed to be a versatile manufacturing process for increasing yields of gasoline and/or jet fuels.
The discovery of huge reserves of heavy oil has attracted renewed interest in thermal cracking processes. Thermal cracking processes such as visbreaking, an abbreviated term for viscosity breaking or viscosity lowering, are used to convert heavy, high viscosity, high boiling hydrocarbons to lower viscosity fractions suitable for further processing or use in heavy fuel oil. These processes may accomplish one or more of the following objectives. First, they reduce the viscosity of the feed stream, which may include heavy hydrocarbon sources such as the residue from distillation operations, the residue from hydroskimming operations, natural bitumen from sources such as tar sands, and even certain high viscosity crude oils. Second, they reduce the amount of residual fuel oil produced in a refinery, which is generally regarded as a low value product. Third, they increase the proportion of middle distillates produced in the refinery. Middle distillates are often used as a diluent for heavy hydrocarbons to lower their viscosity to a marketable level. Cracking the residual hydrocarbons reduces the diluent requirement so that the saved middle distillates can be diverted to higher value products.
In one example of a process for cracking heavy hydrocarbon material such as those mentioned above, the feed is passed through one or more tubes in a furnace. The heavy hydrocarbon material is heated to a high temperature causing partial vaporization and mild cracking. Conversion is achieved primarily as a result of temperature and residence time, which is why this process is described as being high temperature (e.g., 455 to 510° C.) and short residence time. The short residence time is the principal reason that this is considered a mild thermal reaction. The product that exits the tube is quenched to halt the cracking reactions. This may be done by heat exchange with the feed material, which saves energy, or with a stream of cold material such as gas oil to achieve the same effect.
These processes extend the boiling range of the heavy hydrocarbon materials so that light and heavy gas oils can be fractionated from the product stream, fed into a catalytic cracking unit, or otherwise processed further as desired. The yield of the various hydrocarbon products depends on the “severity” of the cracking operation as determined by the temperature the feed is heated to in the furnace. At the low end of the scale, a furnace operating at 425° C. would crack only mildly, while operations at 500° C. would be considered as very severe. Arabian light crude residue cracked at 450° C. would yield around 76 wt % tar, 15 wt % middle distillates, 6 wt % gasolines and 3 wt % gas and LPG.
One problem commonly encountered when cracking heavy hydrocarbon materials is excessive coke formation. As thermal cracking proceeds, reactive unsaturated molecules are formed that continue to react and can ultimately create higher molecular weight species that are relatively hydrogen deficient and readily form coke. The coke is deposited on the cracking equipment and leads to fouling and necessitates frequent cleaning. This is especially a problem in tubular reactors. The coke is deposited in the reaction tubes and eventually fouls or blocks them. Tubular reactors require frequent de-coking, which is labor intensive and can result in substantial downtime.
Another disadvantage of processes for cracking heavy hydrocarbon material is that, unlike conventional thermal cracking, they do not employ a recycle stream. Conditions are too mild to crack a gas oil recycle stream, and the unconverted heavy hydrocarbon material, if recycled, would cause excessive coking. Further cracking of the residuals must be done in a separate unit that can remove the very heavy fractions that are left.
Processes for cracking heavy hydrocarbon material also produce a significant amount of gaseous hydrocarbons as a by-product. Although these can be separated for other uses, it is preferable to limit the amount of gases produced to maximize liquid yields.

SUMMARY

A system for cracking heavy hydrocarbon material includes a first reactor and a second reactor positioned in series. A feed that includes heavy hydrocarbon material and a cracking fluid are input into the first reactor where the heavy hydrocarbon material begins to crack into lighter hydrocarbon material. The cracking fluid is accelerated to supersonic speed in the first reactor and then mixed with the feed to initiate cracking of the heavy hydrocarbons. The cracking fluid functions as a hydrogen source thereby minimizing coke formation due to excessive hydrogen loss from the heavy hydrocarbon material. In one embodiment, the first reactor includes a nozzle reactor.
The second reactor provides the residence time at high temperature that further drives conversion of the heavy hydrocarbon material to lighter hydrocarbons. The second reactor may be a tubular reactor such as a coil reactor. The residence time and linear velocity of the heavy hydrocarbon material in the second reactor may be approximately 0.05 s to 1 s and approximately 4 to 40 m/s, respectively.
The effluent from the second reactor may be separated to isolate any remaining heavy hydrocarbon material. The heavy hydrocarbon material may then be recycled back to the first reactor until it is completely eliminated. The recycled heavy hydrocarbon material does not produce significant amounts of coke due to the hydrogen supplied by the cracking fluid. The entire process may be operated without the use of a catalyst or added hydrogen.
The foregoing and other features, utilities, and advantages of the subject matter described herein will be apparent from the following more particular description of certain embodiments as illustrated in the accompanying drawings.
The term “heavy hydrocarbon material” is used to refer to the hydrocarbon fraction that has a boiling point at or above 525° C. This material may be obtained from a number of sources such as the residue from distillation operations such as atmospheric or vacuum distillation, the residue from hydroskimming operations, natural sources such as tar sands (including oil sands and oil shale), and even certain high viscosity crude oils. The term “distillates” is used to refer to the hydrocarbon fraction that has a boiling point below 525° C. The term “coke precursor” is used to refer to carbon based material that is not soluble in toluene. It should be appreciated that all pressures are given as gauge pressures unless noted otherwise.

DRAWINGS

FIG. 1 is a schematic representation of one embodiment of a system for cracking heavy hydrocarbon material.

FIG. 2 is a schematic representation of another embodiment of a system for cracking heavy hydrocarbon material that includes recycle of unconverted heavy hydrocarbon material.

FIG. 3 shows an exemplary embodiment of a nozzle reactor that may be used in the process.

FIG. 4 shows an exemplary embodiment of a nozzle reactor coupled in series with a coil reactor.

FIG. 5 shows an exemplary embodiment of a method for cracking heavy hydrocarbon material.

DETAILED DESCRIPTION

An improved process for cracking or upgrading heavy hydrocarbon material is described herein. Although the process is described primarily in the context of upgrading heavy hydrocarbon materials, it should be appreciated that the process, concepts, and features described herein may be used in a variety of other settings that would be recognized by those of ordinary skill in the art (e.g., upgrading distillates). Also, it should be understood, that the features, advantages, characteristics, etc. of one embodiment may be applied to any other embodiment to form an additional embodiment unless noted otherwise.
FIG. 1 shows one embodiment of a system 100 for cracking heavy hydrocarbon material. The system includes a first reactor 102 and a second reactor 104 positioned in series. The first reactor 102 partially upgrades the heavy hydrocarbon material and the second reactor 104 further upgrades it until it reaches the overall desired conversion level. The second reactor 104 discharges an upgraded effluent material 110.
Heavy hydrocarbon material is fed to the first reactor 102 in the feed 106. A cracking fluid 108 is also fed to the first reactor. The heavy hydrocarbon material may be obtained from a variety of sources. Examples of suitable sources include the residual fraction of distillation operations such as atmospheric or vacuum distillation or from the residual fraction of hydroskimming operations. Other sources include natural sources such as oil sands (which includes tar sands, oil shale, etc.) or even certain high viscosity crude oils.
The composition of the feed 106 can vary widely, but often includes asphaltenes, resins, aromatic hydrocarbons, and alkanes in varying amounts. Asphaltenes are large polycyclic molecules that are commonly defined as those molecules that are insoluble in n-heptane and soluble in toluene. Resins are also polycyclic but have a lower molecular weight than asphaltenes. Aromatic hydrocarbons are derivatives of benzene, toluene and xylene. The feed may also include 12 to 25 wt % micro carbon as determined using ASTM D4530-07.
The feed 106 may include heavy hydrocarbon material and other lower boiling fractions. In most situations, it is advantageous to separate any distillates from the feed 106 so that it is composed entirely or almost entirely of heavy hydrocarbon material when it enters the first reactor 102. Any suitable separation process (e.g., distillation, etc.) may be used to separate the distillates. In one embodiment, the feed 106 includes at least approximately 95 wt % heavy hydrocarbon material, at least approximately 98 wt % heavy hydrocarbon material, or, desirably, at least approximately 99 wt % heavy hydrocarbon material. It should be appreciated that in other embodiments, the feed 106 may include a substantial amount of distillates.
The feed 106 is preheated before it enters the nozzle reactor to a temperature that is just below the temperature at which the cracking occurs. This imparts the maximum amount of energy to the feed 106 without initiating cracking. In one embodiment the feed 106 may be heated to a temperature that is no more than 400° C. In another embodiment, the feed 106 may be heated to at least approximately 350° C. In yet another embodiment, the feed 106 may be heated to approximately 350° C. to 400° C.
The cracking fluid 108 may be any material that when combined with the feed 106 in the first reactor 102 and the second reactor 104 cracks the heavy hydrocarbon material and/or serves as a hydrogen donor to the hydrocarbon material. The cracking fluid 108 may be supplied as a superheated fluid. Suitable cracking fluids include steam, natural gas, carbon dioxide, methanol, ethanol, ethane, propane, nitrogen, biodiesel, carbon dioxide, other gases, or combinations thereof. In one embodiment, the cracking fluid 108 is superheated steam, natural gas, or a combination of both.
The cracking fluid 108 may help to prevent the formation of coke in the system 100 by functioning as a hydrogen donor in the cracking reactions. The hydrogen from the cracking fluid 108 is transferred to the heaviest hydrocarbons thereby preventing them from becoming hydrogen depleted in the extreme conditions of the reactors 102, 104.
The cracking fluid 108 may be heated and pressurized before it is introduced to the first reactor 102. The heat and pressure give the cracking fluid 108 added energy that is transferred to the heavy hydrocarbon material causing it to crack or scission. The cracking fluid 108 may be provided in an amount and at a temperature sufficient to heat the feed 106 to the desired temperature and initiate the cracking reactions. The amount of heat supplied in the cracking fluid 108 may be determined using a mass and energy balance.
In one embodiment, the cracking fluid 108 may be supplied at a temperature of at least approximately 550° C. or at least approximately 600° C. In another embodiment, the cracking fluid 108 may be supplied at a temperature of approximately 550° C. to 700° C. or approximately 600° C. to 650° C. In yet another embodiment, the cracking fluid 108 may be supplied at a temperature of no more than approximately 700° C.
In one embodiment, the cracking fluid 108 may be pressurized to at least approximately 1380 kPa or at least approximately 3100 kPa. In another embodiment, the cracking fluid 108 may be pressurized to approximately 1380 kPa to 6200 kPa or approximately 3100 kPa to 5170 kPa. In yet another embodiment, the cracking fluid 108 may be pressurized no more than approximately 6200 kPa or no more than approximately 5170° C.
The ratio of cracking fluid 108 to feed 106 supplied to the first reactor 102 may vary depending on a number of factors. In general, it is desirable to minimize the amount of cracking fluid 108 while still successfully cracking the heavy hydrocarbons to reduce cost. In one embodiment, the ratio of cracking fluid 108 to feed 106 is no more than 2.0 or no more than 1.7. In another embodiment, the ratio of cracking fluid 108 to feed 106 may be approximately 0.5 to 2.0 or approximately 1.0 to 1.7. In yet another embodiment, the ratio of cracking fluid 108 to feed 106 is at least approximately 0.5 or at least approximately 1.0
It should be appreciated that the first reactor 102 may be any suitable reactor capable of at least partially upgrading heavy hydrocarbon material. In one embodiment, the first reactor 102 is a nozzle reactor. A nozzle reactor includes any type of apparatus wherein differing types of materials are injected into an interior reactor chamber for the purpose of chemically and/or mechanically interacting with each other.
The nozzle reactor may have any of a number of suitable configurations. In one embodiment, the nozzle reactor accelerates the cracking fluid to supersonic velocities and collides it with the heavy hydrocarbon material. In this way, the nozzle reactor generates a tremendous amount of thermal and kinetic energy.
In one embodiment, the nozzle reactor is configured to accelerate the cracking fluid to at least approximately Mach 1, at least approximately Mach 1.5, or, desirably, at least approximately Mach 2. In another embodiment, the nozzle reactor may accelerate the cracking fluid to approximately Mach 1 to 7, approximately Mach 1.5 to 6, or, desirably, approximately Mach 2 to 5.
The cracking produced in the nozzle reactor is influenced by a number of factors such as temperature, residence time, pressure, and impact force. Without wishing to be bound by theory, it appears that the mechanical forces exerted on the heavy hydrocarbon material due to the impact of the cracking fluid is a significant factor in the success of the system 100. The impact force weakens the molecule making it more susceptible to chemical attack and/or directly cleaves it apart.
In one embodiment, the nozzle reactor is the same or substantially similar to the nozzle reactor disclosed in the '597 patent or the '741 publication. The nozzle reactor may generally include an interior reactor chamber, an injection passage, and a material feed passage. The interior reactor chamber may have an injection end and an ejection end. The injection passage is positioned in fluid communication with the injection end of the interior reactor chamber.
The injection passage is roughly shaped like an hourglass with enlarged openings at the entrance (the enlarged volume injection section) and exit (the enlarged volume ejection section) and a restricted or narrowed area in the middle. The cracking fluid 108 enters the nozzle reactor through the injection passage. The cracking fluid 108 enters the injection passage at a material injection end and exits the passage at a material ejection end. The injection passage opens to the interior reactor chamber.
The heavy hydrocarbon material enters the nozzle reactor through the material feed passage, which is in fluid communication with the interior reactor chamber and is generally located adjacent to the location where the cracking fluid 108 exits the injection passage. Additionally, the feed passage is positioned transverse to the direction of the injection passage.
Turning to FIG. 3, an exemplary embodiment of a nozzle reactor 10 is shown. The nozzle reactor 10 has a reactor body injection end 12, a reactor body 14 extending from the reactor body injection end 12, and an ejection port 13 in the reactor body 14 opposite its injection end 12. The reactor body injection end 12 includes an injection passage 15 extending into the interior reactor chamber 16 of the reactor body 14. The central axis A of the injection passage 15 is coaxial with the central axis B of the interior reactor chamber 16.
The injection passage 15 has a circular diametric cross-section and, as shown in the axially-extending cross-sectional view of FIG. 2, opposing inwardly curved side wall portions 17, 19 (i.e., curved inwardly toward the central axis A of the injection passage 15) extending along the axial length of the injection passage 15. In certain embodiments, the axially inwardly curved side wall portions 17, 19 of the injection passage 15 facilitate high speed injection of the cracking fluid 108 as it passes through the injection passage 15 into the interior reactor chamber 16.
The side wall of the injection passage 15 can provide one or more of the following: (i) uniform axial acceleration of the cracking fluid 108 passing through the injection passage 15; (ii) minimal radial acceleration of such material; (iii) a smooth finish; (iv) absence of sharp edges; and (v) absence of sudden or sharp changes in direction. The side wall configuration can render the injection passage 15 substantially isentropic.
A feed passage 18 extends from the exterior of the reactor body 14 toward the interior reaction chamber 16 transversely to the axis B of the interior reactor chamber 16. The feed passage 18 penetrates an annular feed port 20 adjacent the interior reactor chamber wall 22 at the interior reactor chamber injection end 24 abutting the reactor body injection end 12.
The feed port 20 includes an annular, radially extending reactor chamber feed slot 26 in fluid communication with the interior reactor chamber 16. The feed port 20 is thus configured to inject the feed 106: (i) at about a 90° angle to the axis of travel of the cracking fluid 108 injected from the injection passage 15; (ii) around the entire circumference of a cracking fluid 108 injected through the injection passage 15; and (iii) to impact the entire circumference of the cracking fluid stream virtually immediately upon its emission from the injection passage 15 into the interior reactor chamber 16.
The annular feed port 20 may have a U-shaped or C-shaped cross-section among others. In certain embodiments, the annular feed port 20 may be open to the interior reactor chamber 16, with no arms or barrier in the path of fluid flow from the feed passage 18 toward the interior reactor chamber 16. The junction of the annular feed port 20 and the feed passage 18 can have a radiused cross-section.
The interior reactor chamber 16 may be bounded by stepped, telescoping side walls 28, 30, 32 extending along the axial length of the reactor body 14. In certain embodiments, the stepped side walls 28, 30, 32 are configured to: (i) allow a free jet of injected cracking fluid 108 to travel generally along and within the conical jet path C generated by the injection passage 15 along the axis B of the interior reactor chamber 16, while (ii) reducing the size or involvement of back flow areas (e.g., 34, 36) outside the conical or expanding jet path C, thereby forcing increased contact between the high speed cracking fluid stream within the conical jet path C and the feed 106 injected through the annular feed port 20.
As indicated by the drawing gaps 38, 40 in the embodiment of FIG. 3, the reactor body 14 has an axial length (along axis B) that is much greater than its width. In the embodiment shown in FIG. 3, exemplary length-to-width ratios are typically in the range of 2 to 7 or more.
The dimensions of the various components of the nozzle reactor shown in FIG. 3 are not limited, and may generally be adjusted based on the amount of feed flow rate. Table 1 provides exemplary dimensions for the various components of the nozzle reactor 10 based on the hydrocarbon input in barrels per day (BPD).

TABLE 1

Exemplary nozzle reactor specifications

Feed Input (BPD)

Nozzle Reactor Component (mm)	5,000	10,000	20,000

Injection passage entrance section	148	207	295
diameter
Injection passage mid-section diameter	50	70	101
Injection passage exit section diameter	105	147	210
Injection passage length	600	840	1,200
Interior reaction chamber injection end	187	262	375
diameter
Interior reaction chamber ejection end	1,231	1,435	1,821
diameter
Interior reaction chamber length	640	7,160	8,800
Overall nozzle reactor length	7,000	8,000	10,000
Overall nozzle reactor outside diameter	1,300	1,600	2,000
Overall nozzle reactor length to outside	5.4	5.0	5.0
diameter ratio

The use of the nozzle reactor 10 to crack the heavy hydrocarbon material is described in greater detail. The feed 106, which includes the heavy hydrocarbon material is injected into the interior reactor chamber 16 via the feed passage 18. The feed 106 may be pretreated prior to entering the nozzle reactor 10 to alter the amount or fraction of heavy hydrocarbon material. The feed 106 may also be pretreated to alter other characteristics of the feed.
The feed 106 and the cracking fluid 108 are simultaneously injected into the interior reactor chamber 16 through feed passage 18 and injection passage 15. The configuration of the injection passage 15 is such that the cracking fluid 108 is accelerated to supersonic speed and enters the interior reactor chamber 16 at supersonic speed. The cracking fluid 108 produces shock waves that facilitate mechanical and chemical scission of the heavy hydrocarbon material. In this manner, the heavy hydrocarbon material may be broken down into lighter hydrocarbon molecules.
The nozzle reactor's conversion rate of heavy hydrocarbon material into distillates varies depending on the inputs, conditions, and a number of other factors. In one embodiment, the conversion rate of the nozzle reactor 10 is at least approximately 2%, at least approximately 4%, or, desirably, at least approximately 8%. In another embodiment, the conversion rate of the nozzle reactor 10 is approximately 2% to 25%, approximately 4% to 20%, or, desirably, approximately 8% to 16%.
It should be appreciated that the second reactor 104 may be any suitable reactor capable of further upgrading the heavy hydrocarbon material. In one embodiment, the second reactor 104 is a tubular reactor. The tubular reactor may be any suitable reactor capable of converting the requisite amount of heavy hydrocarbon material into lighter distillates. The tubular reactor provides enough residence time at high temperature and high velocity to provide the overall desired level of conversion of heavy hydrocarbon material. The tubular reactor includes a tube that generally has a uniform internal diameter and may be linear or non-linear.
In one embodiment, the tubular reactor may be a non-linear tubular reactor such as the coil reactor 112 shown in FIG. 4. The non-linear shape of the coil reactor 112 forces the material to repeatedly change direction as it passes through the tube. This causes greater mixing and faster reaction time between the heavy hydrocarbon material and the cracking fluid 108.
The coil configuration affects the temperature and pressure distribution as well as the product yields. The coil reactor 112 is spiral shaped, but it should be appreciated that the coil reactor 112 may have any suitable non-linear shape. Other suitable shapes include a single row, split, reversed split, etc. Coil reactors typically increase the rate of conversion of heavy hydrocarbon materials as well as the amount converted making this the preferred tubular reactor configuration for most situations.
As shown in FIG. 4, the feed 106 and cracking material 108 pass directly from the nozzle reactor 10 to the coil reactor 112. This quick transition allows the materials to enter the coil reactor 112 without losing too much heat or velocity. It should be appreciated, however, that the materials may undergo some form of processing or treatment after leaving the nozzle reactor 10 but before entering the coil reactor 112.
The heavy hydrocarbon material is maintained at a temperature in the tubular reactor that is high enough to effectively crack it, but not high enough to cause excessive coking. In one embodiment, the temperature is at least approximately 410° C. or at least approximately 430° C. In another embodiment, the temperature may be approximately 410° C. to 490° C. or approximately 430° C. to 460° C. In yet another embodiment, the temperature may be no more than approximately 490° C. or no more than approximately 480° C.
In most situations it is not necessary to heat the tubular reactor. Large scale implementations do not require additional heat since the energy imparted to the feed 106 and the cracking fluid 108 before entering the system 100 is sufficient to achieve the desired conversion. However, if the material throughput is small relative to the size of the reactor tube, energy losses such as heat losses may be more acute. In these circumstances, it may be desirable to heat the reactor tube to maintain the desired conversion and/or product yields.
The residence time and linear velocity of the heavy hydrocarbon material in the tubular reactor may be adjusted as necessary to provide the desired conversion rate and product characteristics. In one embodiment, the residence time is at least approximately 0.05 s, at least approximately 0.10 s, or, desirably, at least approximately 0.15 s. In another embodiment, the residence time is approximately 0.05 s to 1 s, approximately 0.10 s to 0.8 s, or, desirably, approximately 0.15 s to 0.7 s. In yet another embodiment, the residence time is no more than approximately 1 s, no more than approximately 0.8 s, or, desirably, no more than approximately 0.7 s.
The linear velocity of the heavy hydrocarbon material in the tubular reactor may be at least approximately 4 m/s, at least approximately 5 m/s, or, desirably, at least approximately 6 m/s. In another embodiment, the linear velocity is approximately 4 to 40 m/s, approximately 5 to 35 m/s, or, desirably 4 to 32 m/s. In yet another embodiment, the linear velocity is no more than approximately 40 m/s, no more than approximately 35 m/s, or, desirably, no more than approximately 32 m/s.
The pressure in the tubular reactor may vary as required to sustain the cracking reactors. In one embodiment, the tubular reactor may be at a pressure of approximately −34 kPa to 240 kPa or approximately −34 kPa to 140 kPa.
The size and dimensions of the tubular reactor are determined based on the capacity of the system. Higher flow rates will require a larger reactor and vice versa. The tubular reactor may be made of any suitable material such as metal, composites, and so forth. In one embodiment, the tubular reactor is made of SS-316.
The system 100 cracks the heavy hydrocarbon material to produce lighter, lower molecular weight hydrocarbons. In one embodiment, the heavy hydrocarbon material is broken down into light hydrocarbon liquid distillate. The light hydrocarbon liquid distillate includes hydrocarbons having a molecular weight less than about 300 Daltons. In certain embodiments, about 25% to about 50% of the heavy hydrocarbon material cracked in the system 100 is converted into distillates.
The system 100 may provide a much higher conversion rate than other comparable systems. The conversion rate of heavy hydrocarbon material into distillates in the system 100 varies depending on the inputs, conditions, and a number of other factors. In one embodiment, the conversion rate of the system 100 is at least approximately 15%, at least approximately 30%, or, desirably, at least approximately 35%.
The total residence time of the heavy hydrocarbon material in the nozzle reactor and the tubular reactor may vary widely. In one embodiment, the total residence time is at least approximately 0.2 s or at least approximately 0.3 s. In another embodiment, the total residence time is approximately 0.2 s to 2 s or approximately 0.3 s to 1.2 s. In yet another embodiment, the residence time is no more than approximately 2 s or no more than approximately 1.8 s.
As already mentioned above, one significant advantage of the system 100 is that it produces very little, if any, coke and minimizes the amount of gas generated. This makes it possible to operate the system 100 for long periods of time without cleaning. In one embodiment, the system 100 may be operated indefinitely. Minimizing coke production also means that more of the heavy hydrocarbon material is conserved so that it can be used to produce higher value products than coke.
The amount of coke produced by the system 100 can be determined by measuring the amount of coke precursors present in the feed 106 and the effluent 110. For example, the feed 106 may include 0.1 wt % to 0.2 wt % of coke precursors and the effluent 120 may include 1 wt % to 2 wt % of coke precursors. This represents a substantial improvement over other technologies. In one embodiment, the effluent 110 may include no more than 5 wt % of coke precursors or no more than 3 wt % of coke precursors.
Conventional systems for processing heavy hydrocarbon material increase the amount of micro carbon in the feed. The amount of micro carbon in the feed may be considered a proxy for determining how much coke is produced in some situations. The system 100 reduces the amount of micro carbon present. The amount of micro carbon present in the effluent 110 is less than in the feed 106. This is another indication that the system 100 is producing favorable results.
It should be appreciated that some portion of heavy hydrocarbon material may pass through the system 100 without being cracked. This material may be referred to as non-participating heavy hydrocarbons or uncracked heavy hydrocarbons, since the reactors 102, 104 did not act on this material to crack it into lighter hydrocarbons. Heavy hydrocarbon material that is cracked but still qualifies as heavy hydrocarbon material may also be referred to as non-participating heavy hydrocarbons.
The effluent 110 from the system 100 may be transported to a separation unit that separates it into its constituent fractions. The separation unit may be any suitable separator capable of separating the effluent 110. Examples of suitable separation units include, but are not limited to, atmospheric or vacuum distillation units, gravity separation units, filtration units, and cyclonic separation units.
The non-participating hydrocarbons may be subjected to further processing to upgrade it into more useful material. Various types of processing may be performed on the non-participating hydrocarbon for upgrading the non-participating hydrocarbon. The remaining fractions may be used as end products or be subjected to further processing.
Depending on the situation, it may not be necessary to crack all of the heavy hydrocarbon material in the feed 106. It may only be necessary to upgrade a portion of the heavy hydrocarbon material to produce stable products such as synthetic crude oil, which can include some amount of heavy hydrocarbon material.
Turning to FIG. 2, another embodiment of a system 150 for cracking heavy hydrocarbon material is shown. The system 150 is similar to the system 100 except that the non-participating heavy hydrocarbons 152 are separated from the effluent 110 in separation unit 154 and recycled back to the first reactor 102. The non-participating heavy hydrocarbons 152 can be recycled back in perpetuity because the hydrogen interaction with the cracking fluid 108 minimizes or prevents coke formation.
The system 150 may provide a significantly higher conversion rate than other comparable systems including hydrocrackers. The conversion rate of heavy hydrocarbon material into distillates in the system 150 varies depending on the inputs, conditions, and a number of other factors. In one embodiment, the conversion rate of heavy hydrocarbon material in the system 150 may beat least approximately 65%, at least approximately 75%, or, desirably, at least approximately 90%. In another embodiment, most or at least substantially all of the heavy hydrocarbon material that enters the system 150 is cracked to distillates. The amount of non-participating heavy hydrocarbon material and/or coke left over from the process may be minor.
In another embodiment, the non-participating hydrocarbons may be injected into a third and fourth reactor positioned in series. The third reactor may be a nozzle reactor that is designed similarly or identical to the first nozzle reactor. The fourth reactor may be a tubular reactor that is similar or identical to the second reactor. The dimensions of the additional nozzle and tubular reactor may be identical to the dimensions of the first nozzle and tubular reactor, or they may be scaled up or down. The non-participating hydrocarbon stream may also be pretreated before entering the third and fourth reactor in a similar or identical way as those described above.
It should be noted that the systems 100, 150 crack the heavy hydrocarbon material without the use of a catalyst or added elemental hydrogen. Thus, the systems 100, 150 are not catalytic cracking processes or hydro-cracking processes.
A method 210 for cracking heavy hydrocarbon material is depicted in FIG. 5. The method includes the step 200 of reacting the heavy hydrocarbon material and the cracking fluid 108 in the first reactor 102 to form a first effluent material. At step 202, the first effluent material is reacted in the second reactor 104 to form a second effluent material. In one embodiment, the first effluent is discharged directly from the first reactor 102 to the second reactor 104 without undergoing any intermediate processing or storage.
The second effluent material is separated at step 204 to isolate the non-participating heavy hydrocarbon material from distillates 212 and gas 214. The non-participating heavy hydrocarbon material 152 is then recycled back to the first reactor 102. In some embodiments the separation and recycling step may be skipped in favor of sending the effluent on for further processing (e.g., catalytic cracking, hydro-cracking, etc.).

EXAMPLES

The following examples are provided to further illustrate the subject matter disclosed herein. These examples should not be considered as limiting or restricting the claimed subject matter in any way.

Example 1

This example compares the conversion of heavy hydrocarbon material in a nozzle and coil reactor versus a nozzle reactor alone. The hydrocarbon material used in this example is Cold Lake raw bitumen and it has the properties shown in Table 2. The cracking fluid is steam.

TABLE 2

Feed hydrocarbon material
Hydrocarbon material properties

	API	10.4
	Sulfur (wt %)	4.8
	Micro carbon (wt %)	16.9
	Heavy hydrocarbon material (wt %)	59.2

The nozzle reactor is substantially the same as the nozzle reactor shown and described in U.S. Patent Application Publication No. 2009/0266741. The specifications of the nozzle reactor are given in Table 3. The coil reactor is a 2194.4 cm long tube that has an internal diameter of 1.6 cm that is uniform throughout its entire length. The coil reactor has a spiral shape.

TABLE 3

Nozzle reactor specifications

	Nozzle Reactor Component	Size (mm)

	Injection passage injection section diameter	3.0
	Injection passage mid-section diameter	1.3
	Injection passage ejection section diameter	2.26
	Injection passage length	20
	Interior reaction chamber injection end diameter	3.7
	Interior reaction chamber ejection end diameter	16
	Interior coil reactor length	21944
	Overall length of nozzle and coil reactor	21964
	Overall nozzle reactor outside diameter	19

Each run is conducted as follows. The cracking fluid is superheated to approximately 650° C. and approximately 2000 kPa. The cracking fluid is sent to the nozzle reactor where it reaches a supersonic velocity of approximately Mach 2.8.
The heavy hydrocarbon material is preheated to a temperature of approximately 380° C. and injected into the nozzle reactor where it reacts with the superheated cracking fluid. The nozzle reactor converts part of the heavy hydrocarbon material into lighter hydrocarbons that have a boiling point below 525° C.
The partially upgraded feed from the nozzle reactor is discharged to the coil reactor. The coil reactor provides the residence time at cracking temperatures of 420 to 470° C. to further convert the heavy hydrocarbon material into lighter distillates.
Four runs are performed with the first run serving as a control since only the nozzle reactor was used. A recycle stream was not used in any of the runs. Table 4 shows the characteristics and results of each run.

TABLE 4

Conversion effectiveness of nozzle and coil reactor combination

		Coil
		Reactor		Distillates**
Sam-		Residence	Conversion*	Produced
ple	Reactor Type	Time (s)	(%)	(vol %)

N1	Nozzle only	NA	4.6	4.9
NC1	Nozzle and Coil Reactor	0.15	16.1	16.0
NC2	Nozzle and Coil Reactor	0.3	20.7	19.3
NC3	Nozzle and Coil Reactor	0.6	30.3	29.2

*Conversion refers to the amount of heavy hydrocarbon material converted to distillates.

This example demonstrates that the coil reactor increases the conversion of the heavy hydrocarbon material versus the nozzle reactor alone. The coil reactor provides increased residence time at high temperature, which drives conversion of the heavy hydrocarbon material.

Example 2

This example compares the cracking efficiency of a straight tubular reactor and a coil reactor. The procedure is the same as Example 1 except that the residual heavy hydrocarbon material discharged from the coil reactor is recycled back to the feed. Recycle is not used with the straight tubular reactor. The results are shown in Table 5.

TABLE 5

Conversion efficiency of straight tubular reactor versus a coil reactor

		Coil			Reaction
		Reactor			Rate
Sam-		Residence	Temp	Conversion*	Constant
ple	Reactor Type	Time (s)	(C.)	(%)	Ln(K)

NST	Nozzle and Straight	0.3	460	26	−0.13
	Tubular Reactor
NCR	Nozzle and Coil	0.3	445	21	−.07
	Reactor

*Conversion refers to the amount of heavy hydrocarbon material converted to distillates.

This example demonstrates the nozzle and coil reactor combination is more efficient than the nozzle and straight tubular reactor. The reaction rate constant of the nozzle/coil combination is twice that of the nozzle/straight tubular combination.

Example 3

The procedure for this example is the same as Example 1. One run was performed using only the nozzle reactor and another run used both the nozzle reactor and the coil reactor. The carbon profile for each run is shown in Table 6.

TABLE 6

Conversion of heavy hydrocarbon material

Carbon		Nozzle Reactor Only	Nozzle/Coil Reactor
Profile	Feed (wt %)	Profile (%)	Profile (%)

C1-C50	51.4	57.3	68.3
C50-C100	17.3	18.8	17.6
C100+	31.3	23.8	14.1

*Conversion refers to the amount of heavy hydrocarbon material converted to distillates.

This example demonstrates that the combination of the nozzle and coil reactor converts over 50 wt % of the heaviest material (the C100+ material) into C50-C100. It is significantly better than the conversion achieved by the nozzle reactor alone. It should be noted that C42+ material has a boiling point of 525° C. or higher.
The terms recited in the claims should be given their ordinary and customary meaning as determined by reference to relevant entries (e.g., definition of “plane” as a carpenter's tool would not be relevant to the use of the term “plane” when used to refer to an airplane, etc.) in dictionaries (e.g., widely used general reference dictionaries and/or relevant technical dictionaries), commonly understood meanings by those in the art, etc., with the understanding that the broadest meaning imparted by any one or combination of these sources should be given to the claim terms (e.g., two or more relevant dictionary entries should be combined to provide the broadest meaning of the combination of entries, etc.) subject only to the following exceptions: (a) if a term is used herein in a manner more expansive than its ordinary and customary meaning, the term should be given its ordinary and customary meaning plus the additional expansive meaning, or (b) if a term has been explicitly defined to have a different meaning by reciting the term followed by the phrase “as used herein shall mean” or similar language (e.g., “herein this term means,” “as defined herein,” “for the purposes of this disclosure [the term] shall mean,” etc.). References to specific examples, use of “i.e.,” use of the word “invention,” etc., are not meant to invoke exception (b) or otherwise restrict the scope of the recited claim terms. Other than situations where exception (b) applies, nothing contained herein should be considered a disclaimer or disavowal of claim scope. The subject matter recited in the claims is not coextensive with and should not be interpreted to be coextensive with any particular embodiment, feature, or combination of features shown herein. This is true even if only a single embodiment of the particular feature or combination of features is illustrated and described herein. Thus, the appended claims should be read to be given their broadest interpretation in view of the prior art and the ordinary meaning of the claim terms.
As used herein, spatial or directional terms, such as “left,” “right,” “front,” “back,” and the like, relate to the subject matter as it is shown in the drawing FIGS. However, it is to be understood that the subject matter described herein may assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Furthermore, as used herein (i.e., in the claims and the specification), articles such as “the,” “a,” and “an” can connote the singular or plural. Also, as used herein, the word “or” when used without a preceding “either” (or other similar language indicating that “or” is unequivocally meant to be exclusive—e.g., only one of x or y, etc.) shall be interpreted to be inclusive (e.g., “x or y” means one or both x or y). Likewise, as used herein, the term “and/or” shall also be interpreted to be inclusive (e.g., “x and/or y” means one or both x or y). In situations where “and/or” or “or” are used as a conjunction for a group of three or more items, the group should be interpreted to include one item alone, all of the items together, or any combination or number of the items. Moreover, terms used in the specification and claims such as have, having, include, and including should be construed to be synonymous with the terms comprise and comprising.
Unless otherwise indicated, all numbers or expressions, such as those expressing dimensions, physical characteristics, etc. used in the specification (other than the claims) are understood as modified in all instances by the term “approximately.” At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the claims, each numerical parameter recited in the specification or claims which is modified by the term “approximately” should at least be construed in light of the number of recited significant digits and by applying ordinary rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass and provide support for claims that recite any and all subranges or any and all individual values subsumed therein. For example, a stated range of 1 to 10 should be considered to include and provide support for claims that recite any and all subranges or individual values that are between and/or inclusive of the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to 3.56, and so forth) or any values from 1 to 10 (e.g., 3, 5.8, 9.9994, and so forth).

Claims

1. A heavy hydrocarbon cracking system comprising:

a nozzle reactor including a heavy hydrocarbon material feed input, a cracking fluid input, and a first effluent material output, the nozzle reactor including an injection passage having an entry opening, an exit opening, and a narrowed section intermediate, and narrower in size relative to the entry opening and the exit opening; and

a non-linear tubular reactor in fluid communication with the first effluent material output, the tubular reactor including a second effluent material output.

2. The heavy hydrocarbon cracking system of claim 1 also comprising a heavy hydrocarbon separator in fluid communication with the second effluent material output.

3. The heavy hydrocarbon cracking system of claim 2 wherein the heavy hydrocarbon separator includes a heavy hydrocarbon material output and the nozzle reactor includes a heavy hydrocarbon material recycle input, wherein the heavy hydrocarbon material output is in fluid communication with the heavy hydrocarbon material recycle input.

4. The heavy hydrocarbon cracking system of claim 1 wherein the tubular reactor comprises a coil reactor.

5. The heavy hydrocarbon cracking system of claim 1 wherein the tubular reactor includes a spiral internal passage section.

6. The heavy hydrocarbon cracking system of claim 1 wherein the tubular reactor comprises an elongated tube having a non-linear internal passage.

7. The heavy hydrocarbon cracking system of claim 1 wherein the injection passage has a circular cross-section.

8. The heavy hydrocarbon cracking system of claim 1 wherein the injection passage includes a side wall section curving inwardly intermediate the entry opening and the narrowed section.

9. A system comprising:

a feed including heavy hydrocarbon material;

a cracking fluid;

a nozzle reactor that receives the feed and the cracking fluid and outputs a first effluent material; and

a tubular reactor in fluid communication with the nozzle reactor;

wherein the tubular reactor receives the first effluent material and outputs a second effluent material.

10. The system of claim 9 wherein the nozzle reactor and the tubular reactor convert at least a portion of the heavy hydrocarbon material in the feed into distillates.

11. The system of claim 9 wherein the nozzle reactor receives heavy hydrocarbon material separated from the second effluent material.

12. The system of claim 9 comprising a separator that separates heavy hydrocarbon material from the second effluent material.

13. The system of claim 9 wherein the cracking fluid reaches Mach 1 in the nozzle reactor.

14. The system of claim 9 wherein the tubular reactor is a coil reactor.

15. The system of claim 14 wherein the coil reactor has a residence time of approximately 0.05 s to 1 s.

16. The system of claim 9 wherein the feed is at least approximately 95 wt % heavy hydrocarbon material and the second effluent material includes no more than 5 wt % of coke precursors.

17. A system comprising:

a feed including heavy hydrocarbon material;

a cracking fluid;

a first reactor that receives the feed and the cracking fluid and outputs a first effluent material; and

a coil reactor in fluid communication with the first reactor;

wherein the coil reactor receives the first effluent material and outputs a second effluent material.

18. The system of claim 17 wherein the first reactor and the coil reactor convert at least a portion of the heavy hydrocarbon material in the feed into distillates.

19. The system of claim 17 wherein the first reactor receives heavy hydrocarbon material separated from the second effluent material.

20. The system of claim 17 comprising a separator that separates heavy hydrocarbon material from the second effluent material.

21. The system of claim 17 wherein the cracking fluid reaches Mach 1 in the first reactor.

22. The system of claim 17 wherein the coil reactor has a residence time of approximately 0.05 s to 1 s.

23. The system of claim 17 wherein the linear velocity of the first effluent material in the coil reactor is approximately 4 to 40 m/s.

24. The system of claim 17 wherein the feed is at least approximately 95 wt % heavy hydrocarbon material and the second effluent material includes no more than 5 wt % of coke precursors.

25. A method comprising:

reacting heavy hydrocarbon material with a cracking fluid in a first reactor and producing a first effluent material; and

reacting the first effluent material in a second reactor and producing a second effluent material;

wherein the first effluent material is fed directly from the first reactor into the second reactor.

26. The method of claim 25 comprising separating heavy hydrocarbon material from the second effluent material and recycling it back to the first reactor.

27. The method of claim 26 comprising converting at least approximately 75% of the heavy hydrocarbon material that enters the first reactor into distillates.

28. The method of claim 25 comprising accelerating the cracking fluid in the first reactor to at least Mach 1.

29. The method of claim 25 wherein the first reactor includes a nozzle reactor.

30. The method of claim 25 wherein the second reactor includes a coil reactor.

31. A method comprising:

reacting heavy hydrocarbon material with a cracking fluid in a nozzle reactor and producing a first effluent material;

reacting the first effluent material in a tubular reactor.

32. The method of claim 31 wherein the tubular reactor outputs a second effluent material, the method comprising separating heavy hydrocarbon material from the second effluent material and recycling it back to the nozzle reactor.

33. The method of claim 31 comprising converting at least approximately 75% of the heavy hydrocarbon material that enters the nozzle reactor into distillates.

34. The method of claim 31 wherein the tubular reactor includes a coil reactor.

35. The method of claim 31 comprising accelerating the cracking fluid in the nozzle reactor to at least Mach 1.

36. The method of claim 31 wherein the tubular reactor has a residence time of approximately 0.05 s to 1 s.