Exxonmobil Chemical Patents Inc.

Exxonmobil Chemical Company Patents Inc.

James M Frye

Richard Charles Stell

Subramanian Annamalai

George Stephens

David B Spicer

Robert David Strack

Arthur R Di Nicolantonio

James N McCoy

Alok Srivastava

Paul F Keusenkothen

John R Messinger

Jennifer L Bancroft

Arthur R DiNicolantonio

Nicholas G Vidonic

George J Balinsky

David Beattie

Nick G Vidonic

Caleb M Scherer

Melissa D Stapleton

David R Spicer

Subramanian 4300 Bay Area Boulevard Annamalai

A process for the decoking of a hydrocarbon steam cracking furnace having a firebox, radiant coils, a transfer line exchanger, and an oil quench connection wherein liquid quench oil is injected to directly cool the steam-cracked effluent. Decoking feed comprising steam and air is supplied to the furnace under conditions sufficient to at least partially combust coke accumulated on the interior of the radiant coils, the transfer line exchanger, and the quench connection. Quench steam is supplied and injected into the decoking process effluent in an amount sufficient to cool the decoking process effluent below the metallurgical temperature limit of downstream piping. Also, a pyrolysis furnace for the production of ethylene is also provided.

Process and apparatus for decoking a hydrocarbon steam cracking furnace

A process for cracking a hydrocarbon feedstream containing non-volatile components in a hydrocarbon cracking furnace having upper and lower convection heating sections within a flue of the furnace, a radiant heating section downstream of and connected to said lower convection heating section, a transfer line exchanger downstream of and connected to said radiant heating section, a furnace box containing furnace burners and said radiant heating section, and a vapor/liquid separator vessel connected between the upper and lower convection heating sections, the process comprising (a) passing said hydrocarbon feedstream into said upper convection section to heat said hydrocarbon feedstream to a first temperature sufficient to flash at least a portion of the hydrocarbons within said hydrocarbon feedstream into a vapor phase to form a vapor/liquid stream; (b) passing said vapor/liquid stream out of said upper convection section and into said vapor/liquid separator to separate said vapor/liquid stream into a hydrocarbon-containing vapor phase and a hydrocarbon-containing liquid phase within said vapor/liquid separator; (c) collecting said liquid phase into a bottoms liquid within said vapor/liquid separator; (d) passing said vapor phase into said radiant heating section and cracking hydrocarbons in said vapor phase to form an olefins-containing effluent stream; and (e) periodically injecting an air-steam mixture into said convection heating section, then through said vapor/liquid separator to incinerate coke formed and passing an incinerated coke residue/air-steam mixture so-formed between the furnace burners within the furnace box.

Process for cracking a heavy hydrocarbon feedstream

A process and apparatus are provided for cooling gaseous effluent from a hydrocarbon pyrolysis furnace, the cooling conduit apparatus including: (i) an inner wall for contacting the effluent, the inner wall defining a bore extending a length of the cooling conduit, the inner wall including a perimeter opening along the bore; (ii) an outer wall external to the inner wall and substantially coaxial to the inner wall; (iii) a substantially annular cavity external to the inner wall and including at least a portion of the outer wall, the annular cavity fluidly and remotely connected to the perimeter opening, the annular cavity externally surrounding a perimeter of the inner wall, the annular cavity including at least a portion of the outer wall; and (iv) a peripheral channel extending around a perimeter of the inner wall, the peripheral channel providing a channel flow path that fluidly connects the annular cavity with the remotely connected perimeter opening along the perimeter of the inner wall.

Method and apparatus for cooling pyrolysis effluent

A process and apparatus are provided for cooling gaseous effluent from a hydrocarbon pyrolysis furnace, the cooling conduit apparatus comprising: (i) an inner wall for contacting the effluent, the inner wall defining a bore extending a length of the cooling conduit, the inner wall including a perimeter opening along the bore; (ii) an outer wall external to the inner wall and substantially coaxial to the inner wall; (iii) a substantially annular cavity external to the inner wall and including at least a portion of the outer wall, the annular cavity fluidly and remotely connected to the perimeter opening, the annular cavity externally surrounding a perimeter of the inner wall, the annular cavity including at least a portion of the outer wall; and (iv) a peripheral channel extending around a perimeter of the inner wall, the peripheral channel providing a channel flow path that fluidly connects the annular cavity with the remotely connected perimeter opening along the perimeter of the inner wall.

A method is provided for treating the effluent from a hydrocarbon pyrolysis unit processing heavier than naphtha feeds to recover heat and remove tar therefrom. The method comprises passing the gaseous effluent to at least one primary transfer line heat exchanger, thereby cooling the gaseous effluent and generating superheated steam. Thereafter, the gaseous effluent is passed through at least one secondary transfer line heat exchanger having a heat exchange surface with a liquid coating on said surface, thereby further cooling the remainder of the gaseous effluent to a temperature at which tar, formed by the pyrolysis process, condenses. The condensed tar is then removed from the gaseous effluent in at least one knock-out drum. An apparatus for carrying out the method is also provided.

Method for processing hydrocarbon pyrolysis effluent

A vapor/liquid separation apparatus for treating a flow of vapor/liquid mixtures of hydrocarbons and steam comprises a vertical drum with a side inlet to introduce hydrocarbon/steam mixtures, an overhead vapor outlet, and a lower section in communication with a cylindrical boot of less diameter than the drum, the boot comprising sufficient gas-liquid contact surface, e.g., that provided by one or more sheds, baffles and/or distillation trays, to provide at least a partial theoretical distillation stage, and a lower portion for receiving liquid from the drum, a lower outlet for removing the liquid, and an inlet for introducing a stripping gas such as steam, hydrogen, light crackable hydrocarbon, and/or methane, below the distillation tray and preferably above the level of liquid in the boot.

Vapor/liquid separation apparatus

A process for decoking of a process that cracks hydrocarbon feedstock containing resid and coke precursors, wherein steam is added to the feedstock to form a mixture which is thereafter separated into a vapor phase and a liquid phase by flashing in a flash/separation vessel, separating and cracking the vapor phase, and recovering cracked product. Coking of internal surfaces in and proximally downstream of the vessel is controlled by interrupting the feed flow, purging the vessel with steam, introducing an air/steam mixture to at least partially combust the coke, and resuming the feed flow when sufficient coke has been removed. An apparatus for carrying out the process is also provided.

Process and apparatus for removing coke formed during steam cracking of hydrocarbon feedstocks containing resids

A process for cracking hydrocarbon feedstock containing resid comprising: heating the feedstock, mixing the heated feedstock with a fluid and/or a primary dilution steam stream to form a mixture, flashing the mixture to form a vapor phase and a liquid phase which collect as bottoms and removing the liquid phase, separating and cracking the vapor phase, and cooling the product effluent. The process comprises at least two of the following conditions: (1) maintaining the bottoms under conditions to effect at least partial visbreaking; (2) reducing or eliminating partial vapor condensation during flashing by adding a heated vaporous diluent to dilute and superheat the vapor; (3) partially condensing the vapor within said flash/separation vessel by contacting with a condenser; (4) decoking internal surfaces and associated piping of the flash/separation vessel with air and steam; (5) utilizing a flash/separation vessel having an annular, inverted L-shaped baffle; and (6) regulating temperature in furnace tube banks used for heating by utilizing a desuperheater and/or an economizer. An apparatus for carrying out the process is also provided.

Process and apparatus for cracking hydrocarbon feedstock containing resid to improve vapor yield from vapor/liquid separation

A process and control system for cracking a heavy hydrocarbon feedstock containing non-volatile hydrocarbons comprising heating the heavy hydrocarbon feedstock, mixing the heated heavy hydrocarbon feedstock with a dilution steam stream to form a mixture stream having a vapor phase and a liquid phase, separating the vapor phase from the liquid phase in a separation vessel, and cracking the vapor phase in the furnace, wherein the furnace draft is continuously measured and periodically adjusted to control the temperature of the stream entering the vapor/liquid separator and thus controlling the ratio of vapor to liquid separated in the separation vessel; and wherein in a preferred embodiment the means for adjusting the draft comprises varying the speed of at least one furnace fan, possibly in combination with adjusting the position of the furnace fan damper(s) or the furnace burner dampers(s).

Process and draft control system for use in cracking a heavy hydrocarbon feedstock in a pyrolysis furnace

A vapor/liquid separation apparatus for treating a flow of vapor/liquid mixtures of hydrocarbons and steam comprises a vertical drum with a side inlet to introduce hydrocarbon/steam mixtures, an overhead vapor outlet, and a lower section in communication with a cylindrical boot of less diameter than the drum, the boot comprising sufficient gas-liquid contact surface, e.g., that provided by one or more sheds, baffles and/or distillation trays, to provide at least a partial theoretical distillation stage, and a lower portion for receiving liquid from the drum, a lower outlet for removing the liquid, and an inlet for introducing a stripping gas, such as steam, hydrogen, light crackable hydrocarbon, and/or methane, below the distillation tray and preferably above the level of liquid in the boot.

A highly efficient vapor/liquid separation apparatus for treating a flow of vapor/liquid mixtures of hydrocarbons and steam comprises a substantially cylindrical vertical drum having an upper cap section, a middle section comprising a circular wall, a lower cap section, a tangential inlet to introduce hydrocarbon/steam mixtures, an overhead vapor outlet, and a bottom outlet for liquid. The vessel also comprises an annular structure located in the middle section, comprising i) an annular ceiling section extending from the circular wall and ii) a concentric internal vertical side wall to which the ceiling section extends. The annular structure blocks upward passage of vapor/liquid mixtures along the circular wall beyond the ceiling section, and surrounds an open core having sufficient cross-sectional area to permit vapor velocity low enough to avoid significant entrainment of liquid.

Vapor/liquid separation apparatus for use in cracking hydrocarbon feedstock containing resid

A process for cracking a hydrocarbon feedstock containing salt and/or particulate matter, wherein said hydrocarbon feedstock containing salt and/or particulate matter is heated, then separated into a vapor phase and a liquid phase by flashing in a flash/separation vessel, separating and cracking the vapor phase which comprises less than about 98% of the hydrocarbon feedstock containing salt and/or particulate matter, and recovering cracked product. The salt and/or particulate matter are removed in the liquid bottoms stream from the flash/separation vessel.

Steam cracking of hydrocarbon feedstocks containing salt and/or particulate matter

A process for cracking a heavy hydrocarbon feedstock containing non-volatile components and/or coke precursors, wherein a stripping agent is added to the feedstock to form an enhanced hydrocarbon blend which is thereafter separated into a vapor phase and a liquid phase by flashing in a flash/separation vessel, separating and cracking the vapor phase, and recovering cracked product. The stripping agent increases vaporization of the volatile fraction of the heavy hydrocarbon increasing the maximum feedrate capacity of the furnace.

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Houston, TX, United States of America

James M Frye