EP-2828357-B1 - STEAM CRACKING PROCESS AND SYSTEM WITH INTEGRAL VAPOR-LIQUID SEPARATION

EP2828357B1EP 2828357 B1EP2828357 B1EP 2828357B1EP-2828357-B1

Inventors

AKHRAS, Abdul, Rahman Zafer
BOURANE, ABDENNOUR
SHAFI, RAHEEL
ABBA, Ibrahim, A.

Dates

Publication Date: 20260506
Application Date: 20130320

Claims (5)

A steam pyrolysis process comprising: charging a feed to a convection section of a steam pyrolysis unit to provide a heated feed; separating the heated feed in a vapor-liquid separator into a light phase and a heavy phase, the vapor-liquid separator comprising a flash vessel having a vapor-liquid separation device at its inlet and including a pre-rotational element having an entry portion and a transition portion, the entry portion having an inlet for receiving the flowing mixture and a curvilinear conduit, a controlled cyclonic section having an inlet adjoined to the pre-rotational element through convergence of the curvilinear conduit and the cyclonic section and an upper portion of the cyclonic member that includes a vapor outlet port through which a light phase passes; and a lower portion of the cyclonic member that includes a liquid outlet port through which a heavy fraction passes; wherein the vapor outlet port has a diameter DV, and the upper portion has an internal diameter DII, and wherein 0.5<DV/DII<1.3 and wherein the flash vessel comprises a top that receives the light fraction from the vapor-liquid separation device and through which the light phase passes, a liquid collector/settling section at the bottom of the flash vessel that receives the heavy fraction from the vapor-liquid separation device and through which the heavy phase is discharged, thermally cracking the light fraction in a pyrolysis section to produce a mixed product stream.
A steam pyrolysis process according to claim 1 further comprising, before the final step of thermally cracking the light fraction: b. charging the light fraction to a convection section of a steam pyrolysis unit to produce a heated light fraction; c. separating the heated light fraction in a vapor-liquid separator into a vapor phase and a liquid phase, the vapor-liquid separator including a pre-rotational element having an entry portion and a transition portion, the entry portion having an inlet for receiving the fluid mixture and a curvilinear conduit, a controlled cyclonic section having an inlet adjoined to the pre-rotational element through convergence of the curvilinear conduit and the cyclonic section and a riser section at an upper end of the cyclonic member through which the vapor phase passes; and a liquid collector/settling section through which liquid phase passes.
A steam pyrolysis unit operation comprising: a convection section constructed and arranged to receive a feedstock and discharge a heated feedstock; a vapor-liquid separator constructed and arranged to receive the heated feedstock and to discharge into a light fraction and a heavy fraction, the vapor-liquid separator comprising a flash vessel having a vapor-liquid separation device at its inlet and including a pre-rotational element having an entry portion and a transition portion, the entry portion having an inlet for receiving the heated feedstock and a curvilinear conduit; a controlled cyclonic section having an inlet adjoined to the pre-rotational element through convergence of the curvilinear conduit and the cyclonic section and an upper portion of the cyclonic member that includes a vapor outlet port through which a light phase passes; and a lower portion of the cyclonic member that includes a liquid outlet port through which a heavy fraction passes; wherein the vapor outlet port has a diameter DV, the upper portion has an internal diameter DII, and wherein 0.5<DV/DII<1.3 and wherein the flash vessel comprises a top that receives the light fraction from the vapor-liquid separation device and through which the light phase passes, a liquid collector/settling section at the bottom of the flash vessel that receives the heavy fraction from the vapor-liquid separation device and through which the heavy phase is discharged; and a pyrolysis section constructed and arranged to receive the vapor phase from the vapor-liquid separator.
A steam pyrolysis process comprising: charging a feedstock to a flash vessel for separation into a light fraction as a steam pyrolysis feed and a heavy fraction, the flash vessel having a vapor-liquid separation device at its inlet and including a pre-rotational element having an entry portion and a transition portion, the entry portion having an inlet for receiving the flowing fluid mixture and a curvilinear conduit, a controlled cyclonic section having an inlet adjoined to the pre-rotational element through convergence of the curvilinear conduit and the cyclonic section, and an upper portion of the cyclonic member that includes a vapor outlet port through which the light fraction passes, and a lower portion of the cyclonic member that includes a liquid outlet port through which a heavy fraction passes; wherein the vapor outlet port has a diameter DV, the upper portion has an internal diameter DII, and wherein 0.5<DV/DII<1.3 and wherein the flash vessel comprises a top that receives the light fraction from the vapor-liquid separation device and through which the light phase passes, wherein a bottom portion of the flash vessel that receives the heavy fraction from the vapor-liquid separation device serves as a collection and settling zone for the heavy fraction prior to passage of all or a portion of said heavy fraction; and thermally cracking the light fraction to produce a mixed product stream.
A steam pyrolysis unit operation comprising: a convection section upstream of a pyrolysis section; and a flash vessel upstream of the convection section including a vapor-liquid separation device at its inlet, the vapor-liquid separation device comprising: a pre-rotational element having an entry portion and a transition portion, the entry portion having an inlet for receiving a flowing fluid mixture and a curvilinear conduit, a controlled cyclonic section having an inlet adjoined to the pre-rotational element through convergence of the curvilinear conduit and the cyclonic section, and an upper portion of the cyclonic member that includes a vapor outlet port through which a light phase passes, and a lower portion of the cyclonic member that includes a liquid outlet port through which a heavy fraction passes; wherein the vapor outlet port has a diameter DV, and the upper portion has an internal diameter DII, and wherein 0.5<DV/DII<1.3 and wherein the flash vessel comprises a top that receives the light fraction from the vapor-liquid separation device and through which the light phase passes, wherein a bottom portion of the flash vessel that receives the heavy fraction from the vapor-liquid separation device serves as a collection and settling zone for a heavy phase prior to passage of all or a portion of said heavy fraction.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an improved steam cracking process and system. Description of Related Art Steam cracking processes typically involve two main sections, the convection and pyrolysis section. The convection section of the steam pyrolysis cracking zone is used to heat the feed to the required reaction temperatures, often called the cross-over temperature, prior to entering the steam pyrolysis cracking unit, wherein the pyrolysis cracking reaction occurs. Steam pyrolysis cracking reactions typically convert a relatively heavy hydrocarbon feedstock, which may include of a wide range of hydrocarbon components, into lighter, and more desirable, hydrocarbons, including but not limited to ethylene, propylene, butadiene, mixed butenes and pyrolysis gasoline. Steam pyrolysis is a useful process that utilizes Le Chatelier's principle to create a more favorable reaction environment. The reactions that occur within a steam cracking process have more molecules on the product side of the equilibrium. Such reactions proceed to the more desirable product side when the reaction is performed under low pressure, as is stated by Le Chatelier's principle. The reaction normally occurs at atmospheric pressure; and running the cracking reaction at conditions lower then atmospheric pressures can be very uneconomical. Other conventional processes utilize a catalyst instead of steam to lower the activation energy and therefore create more desired products. However, in steam pyrolysis processes the addition of a low molecular weight diluent, steam is utilized. The addition of the low molecular weight steam to the cracking reaction lowers the partial pressure of the reaction system and creates more favorable reaction conditions and therefore increased desired products are formed. US 2007/0090018 A1 relates to the integration of hydroprocessing and steam cracking for feeds comprising crude or resid-containing fractions. Therefore it is an object of the present invention to provide improved steam cracking process and systems. SUMMARY OF THE INVENTION The system and process herein provides an integrated vapor-liquid separation device in conjunction with a steam pyrolysis cracking unit operation. In certain aspects, a feed is charged to the inlet of a convection portion of a steam pyrolysis unit where the feed is heated to conditions effective for steam cracking. The convection section effluent is separated in a vapor-liquid separator and the separator vapor effluent is charged to the inlet steam cracking portion of the steam pyrolysis zone. The liquid effluent can be further processed, recycled within the system or a combination thereof. In additional aspects, a feed separated upstream of the convection portion of a steam pyrolysis unit using a flash vessel equipped with a vapor-liquid separator device described herein. In a first aspect a steam pyrolysis process (respectively unit) according to claim 1 (respectively claim 3) is provided. It may further comprise the features of claim 2. In a second aspect an alternative steam pyrolysis process (respectively unit) according to claim 4 (respectively claim 5) is provided. Other aspects, embodiments, and advantages of the process of the present invention are discussed in detail below. Moreover, it is to be understood that both the foregoing information and the following detailed description are merely illustrative examples of various aspects and embodiments, and are intended to provide an overview or framework for understanding the nature and character of the claimed features and embodiments. The accompanying drawings are illustrative and are provided to further the understanding of the various aspects and embodiments of the process of the invention.\ BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in further detail below and with reference to the attached drawings where: FIG.1 is a process flow diagram of an embodiment of a steam cracking process with an integrated vapor-liquid separation zone between the convection and pyrolysis sections; andFIG. 2 is an embodiment of a steam cracking process with an integrated vapor-liquid separation zone upstream of the convection section and prior to the steam cracking process; andFIG. 3 is an embodiment of a steam cracking process with an integrated vapor liquid separation zone upstream of the convection section of the steam cracking process and integrated vapor-liquid separation within the steam cracking process;FIGs. 4A-4C are schematic illustrations in perspective, top and side views of a vapor-liquid separation device used in certain embodiments of a steam cracking unit operation and process described herein; andFIGs. 5A-5C are schematic illustrations in section, enlarged section and top section views of a vapor-liquid separation device in a flash vessel used in certain embodiments of a steam cracking unit operation and process described herein. DEATILED DESCRIPTION