KR910004939B1 - Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels - Google Patents

Abstract

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Description

Heavy hydrocarbon decomposition method

1 is a cross-sectional view of the process of the present invention.

2 is a cross-sectional elevation view of a reactant feeder in a thermal regeneration (TRC) system.

3 is a sectional elevation view of a separator of a thermal regeneration cracking process.

4 is a sectional view along line 4-4 of FIG.

* Explanation of symbols for main parts of the drawings

2: vacuum tower 3: atmospheric tower bottoms

4: reactant feeder 6: thermal regeneration cracking reactor

8 separator 10 coke stripper container

14: fluidized bed vessel 16: entrained bed heater

20: vacuum gas oil 22: gas outlet

32: vacuum residual oil 70: solids outlet

72: conduit 74: the annular room

78: opening 79: corner

80: plug 81: inner hole

94: weir 95: solid outlet

96 gas inlet 97 outlet

105: lining 106: thermal separation lining

The present invention relates to the production of olefin and liquid hydrocarbon fuels from heavy hydrocarbons. In particular, the present invention relates to the production of olefins by thermal cracking.

It is a long known fact that natural hydrocarbons are heat-distributed into olefins and liquid fuels at high temperatures. Existing catalytic and non-contact cracking processes are the production of olefins and hydrocarbon fuels from heavy natural hydrocarbons.

In order to produce olefins and gasoline it is preferred to use low molecular weight and low boiling natural hydrocarbons, such as, for example, gas oils. Light hydrocarbons typically contain less contaminants than heavy hydrocarbons.

However, as light hydrocarbons are depleted, the petroleum and petrochemical industries have focused on using heavy hydrocarbons such as residual oils, for example. Residual oils are customarily identified with hydrocarbons that are heavier than residual, reduced crude oils, atmospheric bottoms, vacuum residual crude oil and mostly gas oils.

The problem with residual oils is that they contain impurities such as sulfur and metals, for example. Heavy metals are particularly troublesome in catalytic cracking processes. Heavy hydrocarbons also contain large amounts of coke precursors (asphalen, polynuclear aromatics, etc.). Such coke precursors tend to be converted to coke during the cracking process and contaminate the equipment and catalyst or internal particles used in the cracking process.

In general, many methods have been developed to address the problems associated with cracking residual oil by pretreatment of residual oil prior to the cracking process. Solvent deasphalting, flowing or delayed coking or hydrotreating is a pretreatment of the residual feed. Solvent deasphalting, flowing or delayed coking processes are particularly carbon paper processes, resulting in significant raw material losses. Water treatment processes require high process costs due to the detrimental effects of impurities on catalyst and hydrogen consumption phases.

It is an object of the present invention to decompose heavy hydrocarbons to produce olefins and liquid fuels.

It is an object of the present invention to decompose an atmospheric bottom by treating the atmospheric bottoms through a vacuum tower and decomposing it into vacuum oil and vacuum residual oil.

The process of the invention is in particular a heat distribution process. The feed, i.e. the bottoms, is separated into vacuum gas oil and vacuum residue oil in the vacuum column. The vacuum gas oil is conveyed to a heat distribution reactor and passed together with particulate solids, for example at a high temperature of 1500 ° F. and a low residence time, for example 0.05-0.40 seconds, to decompose the hydrocarbons into olefins. The olefin is separated from the particles in the separator and absorbed into the top of the separator. Solids are carried in a coke stripper. At the same time, the vacuum residual oil from the vacuum tower bottom is conveyed to the coke stripper and is broken down there and converted to coke in a large size.

The particulates and solids are regenerated by burning the coke produced in the cracking process and are repeatedly sent to the pyrolysis reactor for cracking.

The process of the present invention relates to the production of olefins and liquid fuels from heavy hydrocarbon coke feeds. Atmospheric column bottoms (ATB) are very suitable for carrying out the process of the present invention. However, even heavy feeds that can be separated and separated into light and heavy streams can be treated according to the present invention.

1, the system consists essentially of a vacuum tower 2 and a thermal regeneration device. The thermal regeneration cracker comprises a thermal regeneration cracker 6, a reactant feeder 4, a separator 8 and a coke stripper vessel 10.

The system also includes an apparatus for regenerating the solid factor separated from the degraded product after the reaction. The system includes a companion acid heater 16, a transport conduit 12 and a fluidized bed vessel 14 in which the solids are renewable.

In the process of the present invention, the atmospheric column bottoms are conveyed through conduit 3 to a conventional vacuum column 2 (operated at about 20 millimeters) where the atmospheric column bottoms (ATB) are subjected to a light overhead vacuum oil stream and heavy It is divided into bottoms vacuum residual oil. The vacuum gas oil is concentrated and conveyed through conduit 20 to a thermal regeneration cracking reactor 6.

The vacuum gas oil is conveyed to the reactor 6 together with the hot solid particles that have passed through the reactant feeder 2 (see FIG. 2). Direct mixing of hot solids and vacuum gas oil takes place in the reactor and the decomposition takes place soon. The temperature of the solids injected into the reactor is 1750 ° F. Vacuum gas oil is delivered to the reactor at approximately 700 ° F.

The weight ratio of solid to feed is 5-60 and the reaction is conducted at 1500 ° F. for a holding time of 0.05-0.40 seconds, preferably 0.20-0.30. The product gas is quenched with a typical packing oil which is separated from the solid in separator 8 (shown in FIG. 3) and immediately delivered to conduit 22 via conduit 36. The quenched product passes through the low pressure 24 where the solid contained therein is removed and conveyed through the conduit 44 to the coke stripper 10.

The separated solid leaves separator 8 through conduit 26 and passes through stripper coke machine 10. At the same time, the vacuum residual oil from conduit 22 is conveyed to stripper coke machine 10 and decomposed by solids at temperatures of approximately 1300 ° F-1600 ° F. The weight ratio of solid to vacuum residual oil in the stripper is 5-1 to 6-1. That is, the vacuum residual oil is raised to a temperature of 950 ° F-1250 ° F ° C. The polymerized product from the vacuum residual oil is absorbed to the tower via conduit 30 and transported for processing in conduit 34 or exits the system directly through conduit 42.

Solids with coke accumulated in the tubular reactor (6) and stripper coke (10) are burned with air passing through the entrained bed heater (16) and carried in conduit (44) to regenerate heat in reactor (6). Provide the heat needed to resolve the equation.

The reactant feeder of the TRC process system is particularly suitable for system applications of capacity to rapidly mix hydrocarbon feeds and particulate solids. 2, reactant feeder 4 provides particulate solids from solid outlet 70 to reactor 6 via vertically positioned conduits 72 in a path for receiving particulate solids from conduits 72. Is carried.

The annular seal 74, through which the hydrocarbon is supplied by the annular supply conduit 70, terminates at an angled opening 78. Mixing baffles or plugs 80 also help to mix hydrocarbon feeds and particulate solids quickly and well. The corner 79 of the angled opening 78 is preferably a convergent square and is equal to the corner 79 of the reactor end of the conduit 72. In this way the gaseous stream from chamber 74 is annularly injected into the mixing zone and inhibits solid phase flow from conduit 78. The injection of gas forms a cylinder in the dashed conduit 77 and vortex just below the flow path of the solid. The introduction of the edges of the gas phase causes the two phases to be quickly and uniformly mixed to form a homogeneous reaction phase.

Mixing the solid phase with the gas phase is a function of the shear surface and flow area between the solid and gas phase. The ratio of infinite shear surface to flow area (S / A) is defined as complete mixing. Worst mixing occurs when solids are introduced into the walls of the reaction zone. In the system of the present invention, the gas stream is introduced into the solid annularly to a high shear surface. Also, by supplying the gas phase laterally through the annular feeder, phase infiltration occurs, resulting in faster mixing. By using multiple annular gas feed points and multiple solid feed conduits, larger mixing is promoted faster because it increases with the surface to area ratio for a constant solid flow. Mixing is also known as a function of L / D of the mixing band. The plug produces a surprisingly reduced diameter D for constant L, thus increasing mixing.

The plug 80 reduces the flow area and forms a discontinuous mixing zone. The addition of cyclic gases around the solid feed point and the limited discontinuous mixing zone greatly improve the mixing state. Using this preferred embodiment, the time required to obtain a homogeneous reaction phase in the reaction zone is greatly reduced. That is, this preferred gas and solid addition method can be used with a retention time of 1 second or less, preferably 100 milliseconds or less.

Because of the periphery of the reactor 6 and the reactant feeder 4, the walls form a line with inner holes 81 made of ceramic material. Details of the reactant feeder are described in US Pat. No. 4388187, which is incorporated herein by reference.

The separator 8 of the TRC system shown in FIG. 3 is for the rapid and discontinuous separation of decomposition products and particulate solids from the reactor 6. The inlet to the separator 8 is just above the right corner 90 where the mass of the particulate solid 92 is collected. Downstream from the corner 90 to the weir 94 facilitates the accumulation of solid mass 92. The gas outlet 22 of the separator 8 is rotated 180 ° from the separator gas-solid inlet 96 and the solid outlet 26 is opposed to the gas outlet 22 and downstream of the gas outlet 22 and the weirs 94. Is located. In operation, centrifugal forces flow solid particles through the vapor space of inlet 93 of chamber 96. Initially, the solid impinges on the opposite wall of the inlet 96, but then accumulates to form a surface 92 with an approximately 90 ° curved arc of a circle which forms a solid 92 stationary phase. The solids impinging on the phase 96 move along the curved arc to the solid outlet 95 and preferably rotate for downstream of the solid by gravity. The exact shape of the arc is determined by the inlet stream variables such as geometry and speed, flow rate, bulk density and particle size of the particular separator. The force exerted on the incoming solids is defined by the removal of the solids from the gas phase exiting through the stationary phase 97 rather than on the separator 81 itself, and therefore the separator efficiency is therefore not affected by the high inflow rate of up to 150 ft / sec. The separator 8 is operable over a wide range of dilute phase densities, preferably 0.1-10: 01bs / ft ³ . Separator 8 of the present invention has achieved an efficiency of about 80% through a preferred embodiment, capable of removing 90% solids.

Separator efficiency depends on the geometry of the separator, in particular the flow path must be rectangular and there must be an optimal relationship between height H and U-bending for gas flow.

For a height H of a given seal 93, it has been found that the efficiency increases as the 180 ° U-bending between inlet 96 and outlet 97 becomes closer to inlet 96. That is, for a given H, the efficiency of the separator increases as the flow path decreases and thus the retention time decreases. When the inner diameter of the inlet 96 is Di, the preferred length CL between the centerline of the inlet 96 and the outlet 97 does not exceed 4.0 Di, and the most preferred length between the centerlines is 1.5-2.5Di. Between. Better separation can be obtained at 1.5 Di, but this is mostly not done due to difficulties in handling. However, if such an implementation is required, the separator 8 preferably requires a single design since the inlet 96 and the outlet 97 are too close together so that a welding operation is not possible.

It was found that the height H of the flow path must be at least equal to the Di value or 4 inches and can be larger in either case. It was found that if H was less than Di or 4 inches, the incoming stream would disrupt the phase solid 92 and reintroduce the solid into the gas product exiting the outlet 97. H is preferably twice Di to open greater separation efficiency. Too large an H value will only increase the holding time without significant increase in efficiency. The width W of the distribution path is preferably 0.75-1.25 times Di, most preferably 0.9-1.10 Di.

The outlet 97 may have an inner diameter of some kind. However, speeds greater than 75 ft / sec can cause corrosion because the solids flow into the gas. The inner diameter of the outlet 97 should be such that the pressure difference between the stripping vessel 10 and the separator 8 shown in FIG. 1 allows a fixed height of the solid to be formed in the solid outlet line 26. . The fixed height of solids in conduit 26 forms a secure seal that prevents gas from entering the stripping vessel 10. The magnitude of the pressure difference between the stripping vessel 10 and the separator 8 is determined not only by the height of the solid in the conduit 26 but also by the force required to move the solid in the melt flowing into the solid outlet 95. As the difference increases, the effective flow of gas to the stripping vessel 10 decreases. The solid can overcome this difference because it is gravity-moving, but the gas optionally passes through the gas outlet.

4 is a diagram cut along the section 4-4 of FIG. Vertical sidewalls 101 and 102 should be straight or slightly bowed, as indicated by dashed lines 101 ^a and 102 ^a . That is, the flow path through the separator 8 should be a rectangle having a height H and a width W as shown in FIG. The sphere shown in FIG. 4 defines the geometry of the flow path by fitting the widths represented by lines with respect to walls 101 and 102. In addition, shields, inserts, weirs or other devices may be used. In a preferred manner, an arrangement of walls 103 and 104 across the flow path can also be similarly formed, but this is not required.

The separator perimeter and the manway are preferably aligned with a corrosion resistant lining 105, which may be necessary if the solid is operated in solid form. Typical commercial materials for corrosion resistant linings are the same as Carborundum Pracast CarbofraxD, Carboru-ndum Precast Alfrax 201 or 2. A thermal separation lining 106 may be located between the periphery and the lining 105 and may be located between the handpath and each corrosion resistant lining when the separator is used in a high temperature apparatus. That is, a fixed temperature of 1500 ° F. (870 ° C.) or more can be used.

Details of separator 8 are more fully described in US Pat. No. 4288235, which is incorporated herein by reference.

The following examples illustrate the process of the present invention. Atmospheric column bottoms (ATB) with 44% vacuum residual oil and 56% vacuum gas oil have the following composition:

TABLE 1

62,700 pounds of atmospheric column bottoms are conveyed through conduit 3 to vacuum tower 2. 35100 pounds of vacuum gas oil is conveyed from vacuum tower 2 to conduit 20 and 27600 pounds of vacuum residual oil per hour is conveyed through conduit 32. The vacuum gas oil is conveyed to reactor 6 and cracked into particulate solids having a temperature raised to 1750 ° F. The solid to hydrocarbon feed weight ratio is 22. The decomposition process proceeded at 1500 ° F. for 0.20 seconds. Approximately 1018 pounds of coke per hour is produced on the particles in reactor 6.

27600 pounds of vacuum residual oil per hour is conveyed to coke machine 10 at approximately 650 ° F. There, 2760 pounds of coke are produced per hour. The total coke generated in the system is 3778 lbs. The overall combined yield from the process is as follows:

TABLE 2

Claims (1)

(a) separating heavy hydrocarbons into light hydrocarbon fractions and heavy hydrocarbon fractions, (b) pyrolysing the light hydrocarbon fraction with the heat supplied by the particulate solids, and (c) separating the degradation products from the hot particulate solids, d) transport the separated particulate solids into strippers / cokes, (e) inject heavy hydrocarbons into strippers / cokes to produce vaporized hydrocarbons and cokes, and (f) produce in reactors and strippers / cokes And (g) circulating the heated particulate solid into a pyrolysis reactor: a process for producing an olefin or light carbohydrate fuel.

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