KR20140138142A - Integrated hydrotreating and steam pyrolysis process including hydrogen redistribution for direct processing of a crude oil - Google Patents

Abstract

A process is provided for a steam pyrolysis zone integrated with a hydrogenation process zone that includes hydrogen redistribution that permits direct processing of the crude oil feedstock to produce a petrochemical product comprising olefins and aromatics. An integrated hydrotreating and steam pyrolysis process for direct processing of crude oil for the production of olefins and aromatic petrochemicals comprises the steps of separating the crude oil into a light component and a heavy component; A hydrogenation process zone in which the heavy component and hydrogen are operated under conditions effective to produce a hydrotreated effluent with reduced contaminant content, increased paraffinization, decreased mine station correlation index, and increased U.S. Petroleum Association specific gravity ; Filling the hydrotreated effluent and steam with a convection section of the steam pyrolysis zone; d. Heating the mixture from the convection section of the steam pyrolysis zone and passing it to the vapor-liquid separation section; Removing the residual from the steam-liquid separation section from the steam pyrolysis zone; Filling the hard component from the initial separation stage, the hard portion from the vapor-liquid separation section and the steam into the pyrolysis section of the steam pyrolysis zone; Recovering the mixed product stream from the steam pyrolysis zone; Separating the mixed product stream; Purifying the recovered hydrogen from the mixed product stream and recirculating it to the hydrogenation process zone; And recovering olefins and aromatics from the separated mixed product stream.

Description

[0001] INTEGRATED HYDROTRATING AND STEAM PYROLYSIS PROCESS INCLUDING HYDROGEN REDISTRIBUTION FOR DIRECT PROCESSING OF A CRUDE OIL [0002]

This application claims benefit of U.S. Provisional Application No. 61 / 591,814, filed January 27, 2012, the contents of which are incorporated herein by reference.

The present invention relates to integrated hydrotreating and steam pyrolysis processes for direct processing of crude oil for the production of petrochemicals such as olefins and aromatics.

Lower olefins (i.e., ethylene, propylene, butylene, and butadiene) and aromatics (i.e., benzene, toluene, and xylene) are basic intermediates that are widely used in the petrochemical and chemical industries. Thermal cracking or steam pyrolysis is a major type of process for forming this material, typically in the presence of steam and in the absence of oxygen. Feedstocks for steam pyrolysis may include petroleum gases and distillates such as naphtha, kerosene and gas oil. The availability of these feedstocks is usually limited and requires expensive energy-intensive process steps at the crude refinery.

A study was conducted using heavy hydrocarbons as feedstock to steam cracking reactors. A major drawback in conventional heavy hydrocarbon cracking operations was coke formation. For example, a steam cracking process for heavy liquid hydrocarbons is disclosed in U.S. Patent No. 4,217,204, wherein mist of the molten salt is introduced into the steam cracking reaction zone in an effort to minimize coke formation. In one example using an Arabian light crude oil having a Conradson residual carbon fraction of 3.1 wt.%, The cracking apparatus can continue to run for 624 hours in the presence of molten salt. In the comparative example in which the molten salt is not added, the steam cracking reactor occludes and becomes inoperable after only 5 hours due to coke formation in the reactor.

In addition, the yield and distribution of olefins and aromatics using heavy hydrocarbons as feedstock to the steam cracking reactor are different from those using light hydrocarbon feedstocks. Heavy hydrocarbons have a higher content of aromatics than light hydrocarbons, as indicated by the higher Bureau of Mines Correlation Index (BMCI). BMCI is a measure of the aromaticity of the feedstock and is calculated as follows:

Wherein,

VAPB is the volumetric average boiling point in Rankine temperature units,

sp. gr. is the proportion of feedstock.

With decreasing BMCI, the ethylene yield is expected to increase. Thus, high paraffins or low aromatics feeds are usually preferred for steam pyrolysis to obtain higher yields of desired olefins and avoid more undesirable products and coke formation in the reactor coil section.

The absolute coke formation rate in steam crackers is described by Cai et al . In Coke Formation in Steam Crackers for Ethylene Production, " Chem . Eng . & Proc . , vol. 41, (2002), 199-214. Generally, the absolute coke formation rate is in the order of increasing olefin>aromatics> paraffin, and olefins are heavier olefins.

Other types of feedstock that can be purchased in large quantities, such as crude oil, are attractive to manufacturers to respond to the growing demand for these petrochemicals. The use of crude feeds minimizes or eliminates the possibility of refinery bottlenecks in the manufacture of this petrochemical product.

The steam pyrolysis process is specially developed and suitable for its intended purpose, but the feedstock rate is very limited.

The system and process herein provides a steam pyrolysis zone integrated with a hydrogenation process zone that includes hydrogen redistribution to permit direct processing of crude oil feedstocks to produce petrochemical products including olefins and aromatics.

The integrated hydrotreating and steam pyrolysis process for direct processing of crude oil for the production of olefins and aromatic petrochemicals comprises the steps of separating the crude oil into a light component and a heavy component; Under conditions effective to produce a hydrotreated effluent with reduced heavy contaminant and hydrogen content, increased paraffinization, reduced mine correlation index, and increased specific gravity of the American Petroleum Institute Filling the hydrotreating process zone to be operated; Filling the hydrotreated effluent and steam with a convection section of the steam pyrolysis zone; d. Heating the mixture from the convection section of the steam pyrolysis zone and passing it to the vapor-liquid separation section; Removing the residual from the steam-liquid separation section from the steam pyrolysis zone; Filling the hard component from the initial separation stage, the hard portion from the vapor-liquid separation section and the steam into the pyrolysis section of the steam pyrolysis zone; Recovering the mixed product stream from the steam pyrolysis zone; Separating the mixed product stream; Purifying the recovered hydrogen from the mixed product stream and recirculating it to the hydrogenation process zone; And recovering olefins and aromatics from the separated mixed product stream.

The term "crude oil" described herein should be understood to include total crude oil from conventional sources undergoing some pretreatment. The term crude oil also includes water-oil separation; And / or gas-oil separation; And / or desalting; And / or stabilized.

Other aspects, embodiments and advantages of the process of the present invention are described in greater detail below. Moreover, both the above information and the following detailed description are merely illustrative examples of various aspects and embodiments, and are intended to provide an overview or basis for understanding the nature and characteristics of the claimed features and embodiments. The accompanying drawings are exemplary and provide a further understanding of the various aspects and embodiments of the process of the present invention.

The invention is described in more detail below with reference to the accompanying drawings:
1 is a process flow diagram of an embodiment of the integrated process described herein; And
Figures 2A-2C are schematic illustrations of a perspective view, a top view, and a side view of a vapor-liquid separation device used in certain embodiments of a steam pyrolysis unit in the integrated process described herein.

A process flow diagram including an integrated hydrogenation process involving hydrogen redistribution and a steam pyrolysis process and system is shown in FIG. The integrated system generally includes an initial feed separation zone 20, a selective catalytic hydrogenation process zone, a steam pyrolysis zone 30, and a product separation zone.

Generally, the crude feedstock is flashed, where a harder fraction (having a boiling point that includes the minimum hydrocarbons that require additional cracking and that is readily released, for example, is below about 185 ° C) And only the fraction required, i.e., the fraction having a hydrogen content less than the predetermined content, is subjected to the hydrogenation process. This is advantageous because it provides an increased hydrogen partial pressure in the hydrogenation process reactor, thereby improving the efficiency of hydrogen transfer through saturation. This reduces the hydrogen solution losses and H ₂ consumption. The readily released hydrogen contained in the crude feed is redistributed to maximize the yield of the product, such as ethylene. Redistribution of hydrogen generally reduces the heavy products and increases the production of light olefins.

The first separation zone 20 includes an inlet for receiving the feed stream 1, an outlet for discharging the hard fraction 22 and an outlet for discharging the heavy fraction 226. The separation zone 20 may be a single stage separation device, such as a flash separator, with a break point in the range of about 150 ° C to about 260 ° C. In certain embodiments, the hard fraction 22 may be a naphtha fraction. Table 1 shows the hydrogen content based on various blocking points.

In a further embodiment, the separation zone 20 comprises, or substantially consists of, a cyclone-based separation device or other separation device based on physical or mechanical separation of the vapor and liquid (i.e., operates in the absence of a flash zone) . An example of a vapor-liquid separation device is illustrated with reference to Figs. 2A-2C. A similar arrangement of vapor-liquid separation devices is also described in U.S. Patent Publication No. 2011/0247500, which is incorporated herein by reference in its entirety. In embodiments where the separation zone comprises or consists essentially of separation devices based on physical and / or mechanical separation of the vapor and liquid, the separation point may be adjusted based on the fluid velocity and the vaporization temperature of the material entering the device.

The hydrogenation process zone comprises a hydrogenation process reaction zone (4) having a mixture of light hydrocarbon fraction (21) and recycled hydrogen (2) from the steam pyrolysis product stream and an inlet for receiving the necessary make-up hydrogen. The hydrogenation process reaction zone (4) further comprises an outlet for discharging the hydrotreated effluent (5).

Hydrogenation Process The reactor effluent (5) from the reactor (s) is cooled in a heat exchanger (not shown) and transferred to a high pressure separator (6). The separator overhead fraction 7 is washed in the amine unit 12 and the resulting hydrogen rich gas stream 13 is passed to a recycle compressor 14 which is used as the recycle gas 15 in the hydrogenation process reactor. The bottom stream 8 from the substantially liquid phase high pressure separator 6 is cooled and introduced into the low pressure low temperature separator 9 where it is separated into a gas stream and a liquid stream 10. The gas from the low pressure cryogenic separator comprises hydrogen, H ₂ S, NH ₃ and any light hydrocarbons such as C ₁ -C ₄ hydrocarbons. Typically, the gas is delivered for further processing, such as flare processing or fuel gas processing. According to certain embodiments herein, stream gas stream 11 comprising hydrogen, H ₂ S, NH ₃ and any light hydrocarbons such as C ₁ -C ₄ hydrocarbons is combined with steam cracker product 44 to produce hydrogen Recall. All or a portion of the liquid stream 10 acts as a feed to the steam pyrolysis zone 30.

The steam pyrolysis zone 30 generally comprises a convection section 32 and a pyrolysis section 32 which can be operated on the basis of filling the convection section with heat cracking feed in the presence of steam pyrolysis unit operation known in the art, 34). In addition, in any of the specific embodiments described herein (shown in phantom in FIG. 1), a vapor-liquid separation section 36 is included between section 32 and section 34. The vapor-liquid separation section 36 through which the heated steam cracking feed from the convection section 32 passes may be a separation device based on physical or mechanical separation of the vapor and liquid.

In one embodiment, a vapor-liquid separation device is illustrated with reference to Figs. 2A-2C. A similar arrangement of vapor-liquid separation devices is also described in U.S. Patent Publication No. 2011/0247500, which is incorporated herein by reference in its entirety. In this device, the vapor and liquid flow into the cyclone geometry, where the device is isothermally driven at a very low residence time. Generally, the vapors are vortexed in a circular pattern such that heavier droplets and liquid are trapped and channeled through the liquid outlet as fuel oil 38, for example to the pyrolysis fuel oil blend, As a filler 37 for the steam outlet. For example, in certain embodiments that are compatible with the residual fuel oil blend at about 540 < 0 > C, the gasification temperature and fluid velocity may be varied, e.g., to adjust the approximate temperature cut-off point.

The quench zone 40 includes an inlet in fluid communication with the outlet of the steam pyrolysis zone 30, an inlet to receive the quench solution 42, an outlet to discharge the quenched mixed product stream 44, And an outlet for discharging.

Generally, the intermediate quenched mixed product stream 44 is converted to an intermediate product stream 65 and hydrogen 62, which is purified in the present process and recycled in the hydrogenation process reaction zone 4 to the recycle hydrogen stream 2 . The intermediate product stream 65 may be separated into one or more separate units such as de-ethanizer, de-propanizer and de-butane absorber de lt; RTI ID = 0.0 > (70) < / RTI > For example, a suitable apparatus is described in U.S. Pat. No. 6,984,303, which is incorporated herein by reference in its entirety. .

Generally, the product separation zone 70 includes an outlet 78 for discharging the inlet and methane in fluid communication with the product stream 65, an outlet 77 for discharging ethylene, an outlet 76 for discharging propylene, A plurality of product outlets 73-78 including an outlet 75 for discharging the ene, an outlet 74 for discharging the mixed butylene, and an outlet 73 for discharging the pyrolysis gasoline. Further, an outlet is provided for discharging the pyrolysis fuel oil 71. Optionally, the fuel oil portion 38 from the vapor-liquid separation section 36 is combined with the pyrolysis fuel oil 71 and added to the pyrolysis fuel oil blend 72, such as a sulfur-rich fuel oil blend ≪ / RTI > Although six product outlets are shown, it should be noted that fewer or more outlets may be provided, depending on the arrangement and yield and distribution requirements of the separation unit used, for example.

In one embodiment of the process using the arrangement shown in FIG. 1, the crude feedstock 1 is separated into a hard fraction 22 and a heavy fraction 21 in a first separation zone 20. The hard fraction 22 is transported to the pyrolysis section 36, i. E., Bypassing the hydrogenation process section and combined with a portion of the steam cracked intermediate product to produce the mixed product stream described herein.

The heavier fraction 21 is mixed with an effective amount of hydrogen (2 and 15) to form a combined stream (3). The mixture (3) is charged to the inlet of the selective hydrogenation process reaction zone (4) at a temperature in the range of 300 ° C to 450 ° C. In a particular embodiment, the hydrogenation process reaction zone 4 is co-owned U.S. Patent Publication No. 2011/0083996 and PCT Patent Application Publication Nos. WO2010 / 009077, WO2010 / 009082, WO2010 / 009089 and WO2009 / 073436, The entire contents of which are incorporated herein by reference). For example, the hydrotreating process zone may comprise one or more beds comprising an effective amount of a hydrogen metallization catalyst and one or more beds comprising an effective amount of a hydrogenation process catalyst having hydrothermalization, hydrogen denitrification, hydrodesulphurisation and / Or more bed. In a further embodiment, the hydrogenation process reaction zone (4) comprises more than two catalyst beds. In a further embodiment, the hydrogenation process reaction zone 4 comprises a plurality of reaction vessels each comprising, for example, one or more catalyst beds of different functions.

Hydrogenation Process The reaction zone 4 is operated under a parameter effective to hydrotreat the crude feedstock and / or hydrogenate the hydrocarbons and / or hydrogen denitrification and / or hydrodesulfurize and / or hydrogen crack the crude feedstock do. In certain embodiments, the operating temperature ranges from 300 ° C to 450 ° C; Operating pressures ranging from 30 bar to 180 bar; And using the terms of liquid hourly space velocity of 0.1h ^-1 to 10h ^-1 range performs the hydrogenation process.

The reactor effluent (5) from the hydrogenation process zone (4) is cooled in an exchanger (not shown) and transferred to a high-pressure cold or hot separator (6). The separator overhead fraction 7 is washed in the amine unit 12 and the resulting hydrogen enriched gas stream 13 is passed to a recycle compressor 14 which is used as a recycle gas 15 in the hydrogenation process reaction zone 4 Is used. The separator bottom oil 8 from the substantially liquid-phase high-pressure separator 6 is cooled and introduced into the low-pressure low-temperature separator 9. The remaining gas, stream 11, comprising any light hydrocarbons that may include hydrogen, H ₂ S, NH _3, and C ₁ -C ₄ hydrocarbons, is conventionally purged from a low pressure, low temperature separator and further processed, Flare processing or fuel gas processing. In a particular embodiment of the process, stream 11 (shown in dashed lines) is combined with cracking gas, stream 44, from the steam cracker product to recover the hydrogen. (10) from the low pressure separator (9) to the steam pyrolysis zone (30).

The hydrotreated effluent 10 includes reduced contaminant content (i.e., metal, sulfur and nitrogen), increased paraffinization, reduced BMCI, and increased US Petroleum Association (API) weight.

The hydrotreated effluent 10 is passed through the convection section 32 in the presence of an effective amount of steam received, for example, through a steam inlet (not shown). In the convection section 32, the mixture is heated to a predetermined temperature using, for example, one or more waste heat streams or other suitable heating arrangement. The heated mixture of the hard fraction and steam passes into the vapor-liquid separation section 36, which rejects the portion 38 as a fuel oil component suitable for blending with the pyrolysis fuel oil 71. The remaining hydrocarbon fraction is transported to the pyrolysis section 34 to produce a combined product stream 39, along with the hard fraction 22, e.g., the naphtha fraction, from the first separation zone 20.

The steam pyrolysis zone 30 is operated under parameters effective to crack the effluent 10 with the desired products including ethylene, propylene, butadiene, mixed butene and pyrolysis gasoline. In certain embodiments, the temperature in the convection section and pyrolysis section is in the range of 400 ° C to 900 ° C; A steam to hydrocarbon ratio in the convection section ranging from 0.3: 1 to 2: 1; And in the convection section and the pyrolysis section, the conditions of the residence time in the range of 0.05 second to 2 seconds are used to perform the steam cracking.

In a particular embodiment, the vapor-liquid separation section 36 comprises one or more vapor liquid separation devices 80 shown in Figs. 2A-2C. The vapor liquid separation device 80 is economical to operate and maintain since it does not require power or chemical supply. Generally, the device 80 includes three ports, including an inlet port for receiving a vapor-liquid mixture, a separate vapor and a vapor outlet port for collecting and collecting liquid respectively, and a liquid outlet port. The device 80 can be used to switch the linear velocity of the incoming mixture by a whole flow preliminary rotary section to a reasonable rate, a control centrifugal effect that pre-separates the vapor from the liquid (residual oil), and the separation of the vapor from the liquid Based on the combination of the phenomena including the cyclone effect that promotes the flow of water. To achieve this effect, the device 80 includes a pre-rotating section 88, a controlled cyclone vertical section 90, and a liquid collector / settling section 92.

2B, the pre-rotating section 88 includes a controlled pre-rotating member between the cross-sectional area S1 and the cross-sectional area S2, and a controlled cyclone vertical section 90 located between the cross-sectional area S2 and the cross- ). The vapor liquid mixture emerging from the inlet 82 having a diameter D1 enters the apparatus tangentially at a cross-sectional area S1. The area of the entry section S1 for the incoming flow is at least 10% of the area of the inlet 82 according to the following equation:

The pre-rotating member 88 defines a curved flow path and is characterized in that the cross-sectional area from the inlet cross-sectional area S1 to the outlet cross-sectional area S2 is constant, decreases or increases. The ratio between the exit cross-sectional area from the controlled pre-swivel member S2 and the inlet cross-sectional area S1 is in the range 0.7? S2 / S1? 1.4 in certain embodiments.

The rotational speed of the mixture varies depending on the radius of curvature R1 of the center line of the preliminary rotary member 38 and the center line is a curved line abutting on the center point of the continuous sectional surface surface of the preliminary rotary member 88 Is defined. In a particular embodiment, the radius of curvature R1 is in the range 2? R1 / D1? 6, and the opening angle is in the range 150??? R1? 250.

The cross sectional shape at the inlet section S1 is generally rectangular, but may be a rectangle, a round rectangle, a circle, an ellipse or other linear, curvilinear, or a combination of the above-mentioned shapes. In certain embodiments, the shape of the cross-sectional area along the curved path of the pre-rotating member 38 through which the fluid passes continues to change, for example, from a generally rectangular shape to a rectangular shape. The continuously varying cross-sectional area of the member 88 in a rectangular shape advantageously maximizes the open area so that the gas is separated from the liquid mixture in the initial stage and obtains a uniform velocity profile and minimizes shear stress in the fluid flow.

The fluid flow from the pre-swivel member 88 controlled from the cross-sectional area S2 passes through the section S3 to the controlled cyclone vertical section 90 through the connecting member. The connecting member includes an open area open to and integrated with the inlet in the controlled cyclone vertical section 90. The fluid flow enters the controlled cyclone vertical section 90 at a high rotational speed to create a cyclone effect. The ratio between the connecting member outlet cross-sectional area S3 and the inlet cross-sectional area S2 ranges from 2? S3 / S1? 5 in certain embodiments.

The mixture at high rotational speed enters the cyclonic vertical section 90. The kinetic energy decreases and the vapor separates from the liquid under cyclonic effect. A cyclone is formed at the upper water level 90a and the lower water level 90b of the cyclone vertical section 90. At the upper water level 90a, the mixture is characterized by a high concentration of steam, and at the lower water level 90b, the mixture is characterized by a high concentration of liquid.

In a particular embodiment, the inner diameter D2 of the cyclone vertical section 90 is in the range 2? D2 / D1? 5 and can be constant along its height, and the length LU of the upper portion 90a is 1.2? LU / D2? 3, and the length LL of the lower portion 90b is in a range of 2? LL / D2? 5.

The end of the cyclone vertical section (90) adjacent to the steam outlet (84) is connected to the partial opening release vertical tube and connected to the pyrolyzing section of the steam pyrolysis unit. The diameter (DV) of the partially open release is in the range 0.05? DV / D2? 0.4 in certain embodiments.

Thus, in certain embodiments, depending on the nature of the incoming mixture, a large volume fraction of the vapor in the mixture leaves the device 80 from the outlet 84 through a partially open release pipe having a diameter DV. A liquid phase (e.g., residual oil) with a low or no vapor concentration leaves through the bottom portion of the cyclone vertical section 90 having a cross-sectional area S4 and is collected in the liquid collector and settling pipe 92.

The connection between the cyclone vertical section 90 and the liquid collector and settling pipe 92 is 90 [deg.] In each particular embodiment. In a particular embodiment, the inner diameter of the liquid collector and settling pipe 92 is in the range 2? D3 / D1? 4, constant over the length of the pipe, and the length LH of the liquid collector and settling pipe 92 is 1.2? LH / D3? 5. A liquid with a low vapor volume fraction is removed from the apparatus via a pipe 86 having a diameter of DL and is located adjacent to or at the bottom of the settling pipe and in certain embodiments the diameter is in the range 0.05 < RTI ID = 0.0 > to be.

Although the various elements are described separately and as separate parts, the device 80 may be formed as a monolithic structure, for example, cast or molded, or it may be formed, for example, And those skilled in the art will appreciate that separate parts that do not exactly correspond to or correspond to the parts can be assembled from separate parts by welding or otherwise attaching them together.

While various dimensions are described as diameters, it is understood that this value can also be the same effective diameter in embodiments where the part part is not cylindrical.

The mixed product stream 39 is passed through the inlet of the quench zone 40 having a quench solution 42 (e.g., water and / or pyrolysis fuel oil) introduced through a separate inlet, The intermediate quenched mixed product stream 44 with reduced temperature, such as < RTI ID = 0.0 > C, < / RTI > The gas mixture effluent 39 from the cracker is typically a mixture of hydrogen, methane, hydrocarbons, carbon dioxide and hydrogen sulphide. After cooling with water or oil quench, the mixture 44 is typically condensed in a multi-stage condenser section 51 in steps 4-6 to produce a condensed gas mixture 52. [ The condensed gas mixture 52 is treated with a caustic treatment unit 53 to produce a gas mixture 54 that is poor in hydrogen sulfide and carbon dioxide. The gas mixture 54 is further condensed in the condenser section 55 and the resulting cracked gas 56 is cryogenically treated in a unit 57 which is typically dehydrated and further dried using molecular sieves.

Temperature cracked gas stream 58 from the unit 57 to the demethanizer tower 59 and an overhead stream 60 comprising hydrogen and methane from the cracked gas stream is produced therefrom. The bottoms stream 65 from the demethanizer tower 59 is then subjected to further processing in a product separation zone 70 comprising a fractionation tower comprising a deethanizer, a depopropanizer and a de-butane absorber tower To be transported. De-methane absorbers, deethan absorbers, deprovan absorbers and de-butane absorbers can also be used in different process batches.

Following the process of the present disclosure, hydrogen 62, typically having a purity of 80-95 vol%, is obtained after separation from methane in the demethanizer tower 59 and hydrogen recovery in the unit 61. The recovery method in unit 61 includes cryogenic recovery (e.g., at a temperature of about -157 占 폚). Thereafter, the hydrogen stream 62 is passed through a hydrogen purification unit 64, such as a pressure cycling adsorption (PSA) unit, to obtain a hydrogen stream 2 having a purity of 99.9% +, or passed through a membrane separation unit, 95% hydrogen stream 2 is obtained. The purified hydrogen stream (2) is then recycled back to serve as a major component of the required hydrogen for the hydrogenation process zone. The subcomponents may also be used for the hydrogenation of acetylene, methyl acetylene, and propadiene (not shown). Further, according to the process herein, the methane stream 63 may optionally be recycled to the steam cracker and used as fuel for the burner and / or heater.

The bottoms stream 65 from the demethanizer tower 59 is fed to the inlet of the product separation zone 70 and discharged through the outlets 78, 77, 76, 75, 74 and 73, respectively, , Butadiene, mixed butylene and pyrolysis gasoline. Pyrolysis gasolines generally contain C5-C9 hydrocarbons, and benzene, toluene and xylene can be extracted from this oil fraction. Optionally, the rejected portion 38 from the vapor-liquid separation section 36 is heated to a boiling point above the boiling point of the lowest boiling point C10 compound, also known as the "C10 +" And the mixed stream may be discharged as a pyrolysis fuel oil blend 72, such as a sulfur-rich fuel oil blend (further processed in an off-site refinery).

Advantages of the system described herein with respect to Figure 1 include increased hydrogen partial pressure in the reactor and improved efficiency of hydrogen transfer through saturation. Generally,

PT = PA + PB + PC. (2)

In this case,

PT = P naphtha + PH2 + PX + PY. (3)

When the present inventors remove P naphtha, the PT is the same, so that both PH2 (and PX and PY) increase.

Rate (saturation) = kSat [reactant] x [pH2]. (4)

The system described herein also reduces solution loss and reduces H ₂ consumption. This makes it possible to operate such a system as a closed or nearly closed system.

In certain embodiments, the selective hydrogenation process or the hydrotreating process can increase the paraffin content of the feedstock (or reduce the BMCI) by saturating, followed by mild hydrogen cracking of aromatics, especially polyaromatics. When the crude oil is hydrotreated, pollutants such as metals, sulfur and nitrogen can be removed by passing the feedstock through a series of stacked catalysts that perform the catalytic function of demetallization, desulfurization and / or denitrification.

In one embodiment, the order of the catalysts to perform hydrogen metallization (HDM) and hydrodesulfurization (HDS) is as follows:

a. Hydrogen metallization catalyst. The catalyst in the HDM section is generally based on a gamma alumina support having a surface area of about 140-240 m 2 / g. This catalyst is best described as having a very high pore volume, for example greater than 1 cm3 / g. The pore size per se is typically usually macroporous. This is necessary to provide a large capacity for the absorption of metals and optionally dopants on the catalyst surface. Typically, the active metal on the catalyst surface is a nickel and molybdenum sulfide in a ratio of silver Ni / Ni + Mo < 0.15. The concentration of nickel is lower in the HDM catalyst than in the other catalysts, since it is expected that some of the nickel and vanadium will act as catalyst and settle out of the feedstock itself during removal. The dopant used may be at least one of phosphorous (see, for example, US Patent Publication No. US 2005/0211603 (incorporated herein by reference)), boron, silicon and halogen. The catalyst may be in the form of an alumina extrudate or an alumina bead. In certain embodiments, the alumina beads are used to promote the un-loading of the catalytic HDM bed in the reactor, since the metal absorption is in the range of 30% to 100% at the top of the bed.

b. Intermediate catalysts can also be used to perform the transition between HDM and HDS functions. It has medium metal loading and pore size distribution. The catalyst in the HDM / HDS reactor may be selected from the group consisting of alumina based on a support substantially in the form of extrudates, optionally at least one catalytic metal from Group 6 (e.g. molybdenum and / or tungsten) and / or Group 8 , Nickel and / or cobalt). The catalyst also optionally comprises at least one dopant selected from boron, phosphorus, halogen and silicon. Physical properties include pores having a surface area of about 140-200 m 2 / g, a pore volume of at least 0.6 cm 3 / g, a mesoporosity, and a range of 12 nm to 50 nm.

c. The catalyst in the HDS section can include, for example, having a gamma alumina based support material as a conventional surface area towards the higher end of the HDM range in the range of about 180 to 240 m &lt; 2 &gt; / g. This requires a larger surface for the HDS and produces a relatively smaller pore volume, for example less than 1 cm 3 / g. The catalyst comprises at least one element from group 6, such as molybdenum and at least one element from group 8, such as nickel. The catalyst also comprises at least one dopant selected from boron, phosphorus, silicon and halogen. In certain embodiments, cobalt is used to provide a relatively higher level of desulfurization. The metal loading on the active phase is higher because the required activity is higher, so that the molar ratio of Ni / Ni + Mo is in the range of 0.1 to 0.3 and the (Co + Ni) / Mo mole ratio is in the range of 0.25 to 0.85.

d. The final catalyst (optionally replacing the second catalyst and the third catalyst) is described, for example, in Appl. Catal. A General, 204 (2000) 251) (rather than the primary function of hydrodesulfurization). The catalyst is also promoted by Ni, and the support is gamma alumina with wide pores. Physical properties include, for example, a surface area towards the higher end of the HDM range in the range of 180-240 m &lt; 2 &gt; / g. This requires a larger surface for the HDS and produces a relatively smaller pore volume, for example less than 1 cm 3 / g.

The methods and systems herein provide improvements over known steam cracking cracking processes, including the ability to use crude oil as a feedstock for the production of petrochemicals, such as olefins and aromatics. Additional impurities such as metal, sulfur and nitrogen compounds are also significantly removed from the starting feedstock to avoid post-treatment of the final product.

In addition, the hydrogen produced from the steam cracking zone is recycled to the hydrogenation process zone to minimize the demand for fresh hydrogen. In certain embodiments, the integrated system described herein requires only fresh hydrogen to initiate operation. When the reaction reaches equilibrium, the hydrogen purification system can provide hydrogen of sufficiently high purity to maintain operation of the entire system.

While the method and system of the present invention are described above and in the accompanying drawings, Variations will be apparent to those skilled in the art, and the scope of protection of the present invention should be defined by the following claims.

Claims (7)

An integrated hydrotreating and steam pyrolysis process for directly processing crude oil to produce olefins and aromatic petrochemicals,
a. Separating the crude oil into a light component and a heavy component;
b. The heavy components and hydrogen can be used to reduce the pollutant content, increase the degree of paraffinization, decrease the Bureau of Mines Correlation Index and increase the proportion of the American Petroleum Institute Filling the hydrogenation process zone to be operated under conditions effective to produce the effluent;
c. Filling the hydrotreated effluent and steam with a convection section of a steam pyrolysis zone;
d. Heating the mixture from step (c) and passing the mixture to a vapor-liquid separation section;
e. Removing the remaining portion from the vapor-liquid separation section from the steam pyrolysis zone;
f. Filling a hard component from step (a), a hard portion from said vapor-liquid separation section and steam into a pyrolysis section of said steam pyrolysis zone for thermal cracking;
g. Recovering the mixed product stream from the steam pyrolysis zone;
h. Separating the heat cracked mixed product stream;
i. Purifying the recovered hydrogen in step (h) and recycling it to step (b);
j. Recovering the olefin and aromatics from the separated mixed product stream; And
k. Recovering the pyrolysis fuel oil from the separated mixed product stream. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; 2. The method of claim 1, wherein step (h)
Condensing the heat cracked mixed product stream to a plurality of condensation stages;
Subjecting the condensed thermally cracked mixed product stream to an azeotropic treatment to produce a heat cracked mixed product stream having reduced hydrogen sulfide and carbon dioxide contents;
Condensing said heat cracked mixed product stream with reduced hydrogen sulfide and carbon dioxide content;
Dehydrating the condensed heat cracked mixed product stream with reduced hydrogen sulfide and carbon dioxide content;
Recovering hydrogen from the dehydrated condensed heat cracked mixed product stream with reduced hydrogen sulfide and carbon dioxide content; And
Obtaining olefins and aromatics as in step (j) from the remainder of said dehydrated condensed heat cracked mixed product stream with reduced hydrogen sulfide and carbon dioxide content and obtaining a pyrolysis fuel oil as in step (k);
Wherein step (i) comprises purifying the recovered hydrogen from the dehydrated condensed heat cracked mixed product stream with reduced hydrogen sulfide and carbon dioxide content for recycle to the hydrogenation process zone, And steam pyrolysis method. 3. The method of claim 2, wherein the step of recovering hydrogen from the dehydrated condensed heat cracked mixed product stream with reduced hydrogen sulfide and carbon dioxide content comprises recovering hydrogen from the methane Further comprising the step of separately recovering the hydrotreated hydrocarbons. 2. The process of claim 1, wherein the remaining portion from the vapor-liquid separation section is blended with the pyrolysis fuel oil recovered in step (k). The method of claim 1, wherein the step of separating the heated hydrotreated effluent into a vapor fraction and a liquid fraction is by a vapor-liquid separation device based on physical and mechanical separation, . 6. The apparatus of claim 5, wherein the vapor-
A pre-rotating member having an inlet portion and a transition portion having an inlet and a curved conduit for receiving a flowing fluid mixture,
Controlled cyclone section; And
A liquid collector / settling section through which the liquid passes,
Said controlled cyclone section comprising:
An inlet adjacent to the pre-rotating member through convergence of the curvilinear conduit and the cyclone section, and
And a vertical section at the upper end of the cyclone member through which the steam passes. The method according to claim 1,
Separating the hydrogenation process zone reactor effluent from the high pressure separator to recover a gas portion and a liquid portion wherein the gas portion is cleaned and recycled to the hydrogenation process zone as an additional source of hydrogen, Recovering the liquid portion, and
Further comprising separating the liquid portion from the high pressure separator in a low pressure separator into a gas portion and a liquid portion,
Wherein the liquid portion from the low pressure separator is the hydrotreated effluent to which heat cracking treatment is applied and the gas fraction from the low pressure separator is summed with the mixed product stream after the steam pyrolysis zone and prior to separation in step (h) , And a method of steam pyrolysis.

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