VCC SLURRY MID REACTOR SEPARATION

A system for separating first reactor effluent product by means of an intermediate separator, and sending the unconverted slurry material from the separator to further reactors. Such intermediate separation decreases the required size of downstream reactors.

BACKGROUND

The present disclosure relates to slurry phase reactors and methods for processing hydrocarbons such as residual oil.

2. Description of the Related Art

A conventional process for processing hydrocarbon feeds is a slurry-phase reactor hydrocracking technology, such as in an up-flow bubble column reactor. This slurry phase process, commonly referred to as VCC technology, generally includes two main reaction processes, namely, a liquid phase hydrogenation treatment (LPH), which mainly cracks the hydrocarbon feed, and gas phase hydrogenation (GPH), which treats and further cracks the hydrocarbons. Generally, a residual oil feed is first mixed with one or more additives and hydrogen. Next, the combined feed enters a bubble column reactor with hydrogen under high pressure and temperature, which causes a thermal cracking reaction. The cracking reaction is typically induced by increased temperatures (thermal cracking) or by an acid catalyst (catalytic cracking). Hydrocracking is a particular type of cracking reaction that takes place in a hydrogen rich environment. The additive may or may not increase chemical reactions with the hydrocarbon feed. Additional hydrodesulfurization (hydrotreating sulfur-containing compounds to produce hydrogen sulfide byproduct), hydrodenitrogenation (hydrogenating nitrogen-containing compounds to product ammonia byproduct), olefin saturation, aromatic saturation, and isomerization reactions may also take place. Afterwards, the product enters a separator to produce a vaporous converted product and a liquid slurry unconverted product.

Referring toFIG. 1, there is shown a prior art slurry phase reactor and separation system10for converting a vacuum residue into lighter, more valuable products. The system10may include a plurality of reactors12,14,16, a hot separator18, and a cyclone20. A hydrocarbon feed22is directed into the serially-arranged reactors12,14,16, which operate between 100 and 350 bar, and typically at about 200 bar. The hydrocarbon feed22may be a vacuum residue feed, slurry oils, coal tars, visbreaker tars, atmospheric residue, a coal feed, etc. Alternative hydrocarbon feeds may contain bitumen, coal+hydrocarbon oil mixture, mixtures of plastic and residue, mixtures of biomass and petroleum. Additives, such as carbonaceous type material, may be added to the feed22. Other additives may contain iron or other metal based catalyst, carbon type impregnated with various metals, sodium salts. The product from the reactors12,14,16exit as a three phase mix of vapor, liquid, and solids. After cooling the mix to stop further cracking reactions and reduce coke forming reactions using a variety of methods including heat exchanging with cooler streams, injection of Hz, and injection of liquid hydrocarbon such as gas oil, the product is sent to the hot separator18, which forms a first stream24composed of unconverted liquid slurry material and the additive(s) and a second lighter gaseous fluid stream26. The vapor product26is sent to the cyclone20. The cyclone20is a separator that uses inertia and a spiral vortex to remove small droplets of liquid and solid particles before the fluid streams enters a gas phase (GPH) reactor for further hydroprocessing. The GPH reactor can be a hydrotreater or a mix of hydrotreating and hydrocracking reactors.

Primary conversion within the LPH Reactors benefits from a stable back-mixed reactor flow regime, which is affected by superficial vapor velocity, liquid, and solid content. While high vapor rates tend to increase the back-mixing, they also necessitate larger reactor vessels, increasing the unit cost. Additionally, extremely high vapor rates can lead to instability in the back-mixed flow regime, affecting residue conversion. Over-conversion of the residue feed can result in malfunction of the unit, resulting from coking of the equipment and inability of the unit to remove the coke and solids from the unit.

The present disclosure addresses these and other drawbacks of the prior art.

SUMMARY

In aspects, the present disclosure provides a system for processing a hydrocarbon feed. The system may include a plurality of serially aligned reactors; a hot separator receiving an effluent from the plurality of serially aligned reactors, the hot separator producing a first converted vapor product and a first unconverted slurry product; and an intermediate separator receiving an effluent from a first reactor of the plurality of reactors, the intermediate separator producing a second converted vapor product and an second unconverted slurry product, the second unconverted slurry product being directed into a second reactor of the plurality of reactors.

In aspects, the present disclosure provides a method for processing a hydrocarbon feed. The method includes feeding the hydrocarbon feed into a plurality of serially aligned reactors; receiving an effluent from the plurality of serially aligned reactors in a hot separator, the hot separator producing a first converted vapor product and a first unconverted slurry product; receiving an intermediate effluent from a first reactor of the plurality of reactors in an intermediate separator, the intermediate separator producing a second converted vapor product and an second unconverted slurry product; and directing the second unconverted slurry product into a second reactor of the plurality of reactors.

It should be understood that examples of certain features of the disclosure have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will in some cases form the subject of the claims appended thereto.

DETAILED DESCRIPTION

Referring toFIG. 2, there is shown a slurry phase reactor and separation system30in accordance with one embodiment of the present disclosure for producing products such as naphtha, diesel, and gas oil from a hydrocarbon feed22. The hydrocarbon feed may include coal tar, slurry oil, atmospheric residues, vacuum residues, coals, etc. The feed22may include a lighter material, which is defined as a material having a normal boiling point above 500° C. The system30may include a plurality of serially-arranged reactors32,34,36and a main hot separator38. The reactors32,34,36may be any vessel having a body suitable for reacting three-phases, i.e., solids, liquids, and gases, simultaneously, to form contents using an upward flowing, back-mixed flow regime. The reactors are VCC slurry phase or Liquid Phase (LPH) Reactors and operated at between 100-350 bar, and typically approximately 200 bar. The reactors32,34,36may include bubble columns that allow hydrocarbons, hydrogen and additives to enter the bubble column from the bottom. The contents are backmixed in each reactor with three phase (i.e., gas, liquid, solid) material exiting the top of the reactor. Solid additives fed into the reactor helps increase the residence time of liquid in the reactors and helps residue conversion.

In embodiments, an intermediate separator50may be inserted between two of the reactors32,34,36. For instance, the intermediate separator50may be positioned to receive an effluent38from the reactor32and configured to form two products, a vaporous reactor conversion product52and an unconverted residue and solids product slurry54. A hydrogen feed56may be added to the unconverted residue and solids product slurry54. The separator50is configured to reduce the amount of hydrocarbon vapor in the effluent38from the reactor32, which would otherwise reduce the hydrogen partial pressure in the downstream reactors34,36. Such a reduction would negatively impact the conversion efficiency of the residue and the prevention of coke in the reactors34,36. The reduction of feed to the subsequent reactors decreases their size and hence the overall equipment cost. The vapor product52may be sent to a GPH reactor (not shown) for further processing, or to a cooling unit (not shown) if there is no GPH reactor. The intermediate and main separators50,38may be hot separators. The reduction of hydrocarbon vapor may be, by molecular weight, 1%, 5%, 10%, 20%, 30%, or more than 30%.

In one mode of operation, the hydrocarbon feed22is sent to an initial reactor32wherein the feed22is reacted with one or more additives, such as a carbonaceous additive, and hydrogen. The effluent38from the reactor32is directed into the intermediate separator, which separates the vapors into the vapor stream product52and the unconverted product slurry54. Hydrogen56is added via a suitable line to the slurry54prior to entering the next reactor34. After being reacted in downstream reactors34,36, the reactor outlet slurry is sent to the hot separator38. The hot separator38separates the reactor outlet slurry into to the converted vapor product22and the unconverted residue and solids product slurry58. The converted vapor product22may be sent to a cyclone separator, a cooling unit, a fixed bed Gas Phase (GPH) reactor, or otherwise sent for further processing.

It should be understood that the system30ofFIG. 1is merely illustrative. Some embodiments may include only two reactors. Other embodiments may include four or more reactors. Also, the intermediate separator may not necessarily be between the first and the second separators. Some embodiments may interpose the intermediate separator between reactors further downstream, e.g., between the second and third, the third and fourth, etc. Also, in some embodiments, two or more intermediate separators may be used; e.g., between the first and the second reactors and also between the second and the third reactors.

Some components of the system30are described in U.S. Pat. No. 4,851,107, the contents of which are incorporated by reference for all purposes. While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. For instance, a cyclone separator may be installed downstream of or inside the separators38and50.

From the above, it should be appreciated that what has been described includes, in part, a system for processing a hydrocarbon feed. The system may include a plurality of serially aligned reactors; a hot separator receiving an effluent from the plurality of serially aligned reactors, the hot separator producing a first converted vapor product and a first unconverted slurry product; and an intermediate separator receiving an intermediate effluent from a first reactor of the plurality of reactors, the intermediate separator producing a second converted vapor product and an second unconverted slurry product, the second unconverted slurry product being directed into a second reactor of the plurality of reactors.

From the above, it should be appreciated that what has been described includes, in part, a method for processing a hydrocarbon feed. The method may include feeding the hydrocarbon feed into a plurality of serially aligned reactors; receiving an effluent from the plurality of serially aligned reactors in a hot separator, the hot separator producing a first converted vapor product and a first unconverted slurry product; receiving an intermediate effluent from a first reactor of the plurality of reactors in an intermediate separator, the intermediate separator producing a second converted vapor product and an second unconverted slurry product; and directing the second unconverted slurry product into a second reactor of the plurality of reactors.

Optionally, the system and/or method may also include a line conveying the second converted vapor product to one of: (i) a cyclone separator, (ii) a cooling unit, and (iii) a fixed bed Gas Phase reactor. In some embodiments, at least one of the plurality of serially aligned reactors is configured to receive one of: (i) a carbonaceous additive, and (ii) hydrogen. In some embodiments, the intermediate separator is configured to reduce hydrocarbon vapor in the effluent received from the first reactor. In some embodiments, at least one of the plurality of serially aligned reactors includes a bubble column allowing entry from a bottom of the bubble column one of: (i) a hydrocarbon, (ii) hydrogen, and (iii) an additive. In some embodiments, a line supplies a hydrogen feed to the second unconverted residue and solids product slurry.