Ethylene and propylene production method

Abstract

The invention relates to a process flow production of ethylene and propylene from hydrocarbon feedstock of different composition in gas and / or liquid phase. The process flow includes the following units and stages connected by direct and reverse connections: receipt, treatment and mixing unit (100) of feedstock, thermal splitting unit (200), pyrolysis gas primary fractionation and water quenching unit (300), compression unit (400), alkali purification unit (500), dehydration unit (600) and gas separation unit (700). Wherein the demand for water vapor of the respective parameters in the thermal splitting (200), compression (400), dehydration (600), and gas separation (700) units is entirely covered by generated energy flows of water vapor with different pressure. Water vapor flows of the same pressure generated in the pyrolysis furnaces are combined by a common pipeline with the respective consumers of compression (400), dehydration, (600) and gas separation (700) units. The invention provides production of ethylene and propylene from hydrocarbon feedstock of different composition in gas and / or liquid phase and eliminates the need to receive water vapor from outside of the plant and / or supply unused flows of water vapor outside the plant.

Description

[0001] ETHYLENE AND PROPYLENE PRODUCTION METHOD TECHNICAL FIELD

[0002] The invention is related to process flows of ethylene and propylene production of different stock supplied from oil refineries and gas processing plants, by development of efficient production systems, and can be used in petrochemical industry.

[0003] Ethylene and propylene are basic monomers produced by petrochemical clusters of industrial countries. Increase in production capacity of basic monomers has a direct effect on development perspectives of the Russian polymerization technologies. The main method of basic olefins (ethylene, propylene) production is currently represented by pyrolysis of hydrocarbon feedstock in pipe furnaces in presence of water vapor. Thus, development of petrochemical industry is often estimated by total pyrolysis capacity.

[0004] Different sources of hydrocarbon feedstock (ethane, liquefied petroleum gases, gasoline fractions of different composition, etc.) can be used as feedstock for pyrolysis plants. The opportunities for processing at pyrolysis plants gas or liquid hydrocarbon fractions produced at nearby oil refineries and / or gas processing plants shall be taken into account while developing oil and gas chemical complexes of today.

[0005] PRIOR ART

[0006] During the last decades, key trends in development of the hydrocarbon feedstock high-temperature decomposition process have been related to the increase in the target product yields and to the decrease in specific stock and energy consumption (including fuel supplied to the furnace burners) to produce one ton of olefins (either ethylene during pyrolysis in ethylene mode, or propylene during pyrolysis in propylene mode, or total of the olefins in olefin mode) (Zhagfarov F. G., Guskov P. O., Lapidus A.L. Trends in the Processing of Gas Hydrocarbon Raw Materials in the Process of Pyrolysis. Gazokhimiya, 2011, p. 26-31). That is why more and more significant become the goals of integrated processing of mixed feedstock having different composition supplied from oil refineries, and reducing of specific energy consumption by intensified use of internal energy flows of pyrolysis plants.

[0007] A method is known of ethylene production by pyrolysis of hydrocarbon feedstock heavier than ethane at temperature of 750-870 °C in a tube furnace with extraction of ethylene-containing fraction, where C3-C5 hydrocarbon fraction is extracted from pyrolysis products and is then hydrogenated to paraffins in presence of palladium catalyst in liquid phase under mole ratio between H2 and C3-C5 fraction equal to 0.8-2.5 and recirculation of the part of hydrogenated C3-C5 fraction in hydrogenation reactor with the ratio to the initial C3-C5 fraction supplied to the hydrogenation reactor equal to 10-20:1, after which hydrogenation products are supplied to pyrolysis as additional feedstock having been previously mixed with fresh hydrocarbon feedstock (invention patent RU 2281316, IPC C10G 69 / 06, claimed on 5 / 5 / 2005, published on 8 / 10 / 2006). Key disadvantages of the invention are as follows:

[0008] - Processing of feedstock limited in the composition of hydrocarbons upwards of C3, i.e. the feedstock may include, for example, propane, n-butane, natural gas liquids (NGL), gasoline, which does not allows for the use of ethane contained in LPG or in hydrocarbon gas produced by gas processing plants;

[0009] - The stage of propylene, which is a valuable petrochemical product, extraction from C3-C5 fraction prior to the hydrogenation stage is not provided;

[0010] - The stage of C4 olefins, which are a valuable petrochemical product, extraction from C3-C5 fraction prior to the hydrogenation stage is not provided.

[0011] A method is known of ethylene production by pyrolysis of hydrocarbon feedstock containing ethane and liquefied hydrocarbons, where hydrocarbon feedstock is conditioned by mixing of ethane and liquefied hydrocarbon flows heated to 60-150°C under contents of liquefied hydrocarbons in the hydrocarbon feedstock from 5 to 300 % wt, supplied to pyrolysis in presence of water vapor. Liquefied hydrocarbons are generally represented by propane, butane or mixture thereof (invention patent RU 2764768, IPC C10G 9 / 00, C10G 45 / 26, claimed on 4 / 29 / 2021, published on 1 / 21 / 2022). Key disadvantages of the invention are as follows:

[0012] - The opportunity of gas feedstock processing with an LPG share from 5 to 30% wt. is considered, which closes out processing of fractions having wider range of ratios between ethane and LPG supplied from oil refineries and characterized by inconstant composition;

[0013] - Closed out opportunity to involve gasoline fractions of inconstant composition supplied from oil refineries into integrated pyrolysis;

[0014] - No opportunity to maintain balance between water vapor production / use under conditions of feedstock supplied with a constantly changing ratio of ethane, LPG, gasoline fractions of inconstant composition.

[0015] A hydrocarbon processing system is also known that includes the following: separation unit providing an opportunity to separate hydrocarbon feedstock into the flow of light fractions and the flow of heavy fractions; process control unit with one or several control units configured for adjustment of separation extent in the separation unit based on requirement to production of olefins and power supply; pyrolysis unit in fluid communication with the separation unit, where the pyrolysis unit is configured to form an outgoing flow from a part of the flow of light fractions; fuel conversion unit in fluid communication with the separation unit with an opportunity of a part of the heavy fraction flow conversion into the feedstock for the turbine; and the turbine in fluid communication with the fuel conversion unit and configured for power energy production, with at least partial use of the turbine power supply (patent WO 2012039890, IPC C10G 7 / 00, C10G 9 / 00, C10G 7 / 12, C10G 11 / 00, F02C 3 / 00, claimed on 8 / 26 / 2011, published on 3 / 29 / 2012). Key disadvantages of the invention are as follows:

[0016] - Use of turbine to produce power energy results in the process complication and greater price of power energy produced;

[0017] - Decrease in the output of target olefins due to the use of a part of feedstock as a fuel to produce power energy. The closest in its technical essence to the claimed method is gas chemical production of ethylene and propylene using hydrocarbon feedstock in gas and / or liquid phase and including the following units connected by direct and reverse connections, in particular, by pipelines:

[0018] (1) feed preparation unit providing removal of unwanted impurities and production of treated feed flow, consisting of:

[0019] (a) stage of mechanical impurities removal by filtration;

[0020] (b) stage of carbon dioxide and sulfur compound impurities removal by absorption and / or adsorption;

[0021] (c) stage of methanol removal by absorption and / or adsorption, and / or water flushing;

[0022] (2) mixing unit providing mixing of the treated feed flow with water vapor and recirculated pyrolysis products generated in the thermal splitting unit (3) and emitted in the gas separation unit (8) in the form of ethane fraction of stage (c), and / or propane fraction of stage (g), and / or C3+ fraction of stage (c), and / or C4+ fraction of stage (f), and / or recirculated C4- fraction of stage (b) of the metathesis unit (9), with the pyrolysis process feedstock obtained;

[0023] (3) thermal splitting unit providing alternating stages of the feedstock pyrolysis in heater coils of reaction furnace and decoking by vapor bumoff with coke particle trapping by cyclones and / or water flushing under emission of water vapor (simultaneous for the both stages) returned to the mixing unit (2) and its superheating by heat of the reaction furnace flue gases;

[0024] (4) primary fractionation and water flushing unit consisting of:

[0025] (a) primary fractionation stage providing pyrolysis gas quenching by recirculation of quenching oil with removal of pyrolysis resin, liquor, and pyrolysis gasoline, with circulating and / or live reflux, and / or with extraction of water vapor in the waste heat boiler;

[0026] (b) stage of pyrolysis gas water flushing with removal of pyrolysis resin, liquor, and pyrolysis gasoline, with circulating and / or live reflux, and / or with extraction of water vapor in the waste heat boiler; (5) compression unit providing pyrolysis gas compression to the pressure of 3.0-4.0 MPa in a four- or five-stage compressor driven by high-pressure water vapor supplied from the thermal splitting unit (3) and / or from outside the battery limits. Water condensed during compression is separated from pyrolysis gas between the compressor stages in water separators with the opportunity of its return to stage (b) of the primary fractionation and water flushing unit (4); hydrocarbons condensed during compression are separated from pyrolysis gas between the compressor stages in water separators and supplied to stage (f) of the gas separation unit (8) to the pyrolysis gasoline fractionation tower, and / or to stage (c) of the gas separation unit (8) to the pyrolysis gas deethanization column, and / or to stage (d) of the gas separation unit to the depropanization column; before the last compression stage, pyrolysis gas is supplied to the alkali purification unit (6), and after the last compression stage, pyrolysis gas is supplied to the dehydration unit (7);

[0027] (6) alkali purification unit providing removal of impurities from pyrolysis gas, including carbon dioxide and hydrogen sulfide, and consisting of:

[0028] (a) pyrolysis gas purification stage of one or several sections by means of pyrolysis gas flushing with circulating alkali solution with a makeup of fresh alkali solution and discharge of spent alkali solution;

[0029] (b) stage of pyrolysis gas water flushing from alkali and salts, with the pyrolysis gas being returned to the last compression stage of the compression unit (5);

[0030] (c) stage of the spent alkali solution treatment prior to its supply to the treatment plants by pre-oxidation of sulfides to thiosulfates and / or sulfates, or alkali neutralization using sulfuric acid with subsequent blowing off of sour gases;

[0031] (7) dehydration unit providing removal of water vapors from the compressed pyrolysis gas using adsorbents to the depth excluding hydrate formation in the gas separation unit (8), without / with the pyrolysis gas cooling prior to dehydration to the temperature not lower than the hydrate formation one, with subsequent adsorbent recovery using dry hot gas: methane fraction from outside the battery limits, or feed ethane fraction, or methane-hydrogen fraction supplied from stage

[0032] (a) of the gas separation unit (8), or recirculated ethane fraction supplied from stage (e) of the gas separation unit (8);

[0033] (8) gas separation unit providing extraction of the required components from the dehydrated and compressed pyrolysis gas, and consisting of:

[0034] (a) demethanization stage of pyrolysis gas supplied from the dehydration unit (7), or stage (h) of the gas separation unit (8), or C2- fraction of stages (c) or (h) of the gas separation unit (8), with / without simultaneous extraction of hydrogen-containing gas or demethanization of C3- fraction supplied from stage (d) of the gas separation unit (8), providing consistent cooling of pyrolysis gas or C3- fraction using refrigerants or cold process flows of other stages of the gas separation unit (8), isentropic expansion and cooling of pyrolysis gas or C3- fraction in one, two, or three expansion turbines, separation, and subsequent removal of methane-hydrogen fraction and / or hydrogen-containing gas flow in gas phase from the coldest separator, and / or zone of fractionation tower, and / or system of fractionation towers and separation of C2+ fraction supplied to stage (c), (e) or (h) of the gas separation unit (8), or combination of separation and hydrogenation processes at stages (a), and / or (c), and / or (d), and / or (i) of the gas separation unit (8) in presence of hydrogen with respective conversion of acetylene and diene hydrocarbons of pyrolysis gas in the fractionation tower, or the system of fractionation towers, with the catalyst integrated into the fractionation tower;

[0035] (b) stage of hydrogen-containing gas purification from hydrocarbons, and / or carbon dioxide, and / or carbon oxide, and / or nitrogen, and / or oxygen in adsorbers by method of changeable pressure, and / or changeable temperature, and / or in membrane apparatus with the further use of the purified hydrogen-containing gas as a process chemical;

[0036] (c) deethanization stage of C2+ fraction produced at stage (a) of the gas separation unit (8), or of pyrolysis gas supplied from the dehydration unit (7), or of C3- fraction produced at stage (d) of the gas separation unit (8), providing flow separation in the fractionation tower or the system of fractionation towers into ethane-ethylene fraction or C2- fraction, and C3+ fraction or propane-propylene fraction, or combination of separation and hydrogenation processes of pyrolysis gas, or C2+ fraction, or C3- fraction in presence of hydrogen, with respective conversion of acetylene and diene hydrocarbons of pyrolysis gas, or C2+ fraction, or C3- fraction, in the fractionation tower or the system of fractionation towers, with the catalyst integrated into the fractionation tower. C3+ fraction is supplied for separation to stage (d) or (f) of the gas separation unit (8) or to the mixing unit (2) as a recirculated flow, while propane-propylene fraction is supplied for separation to stage (g) or (h) of the gas separation unit (8), or to the mixing unit (2) as a recirculated flow;

[0037] (d) depropanization stage of pyrolysis gas supplied from the dehydration unit (7) or stage (h) of the gas separation unit (8), or depropanization of C3+ fraction supplied from stage (c) or (h) of the gas separation unit (8), providing separation of pyrolysis gas or C3+ fraction in the fractionation tower or the system of fractionation towers into propane-propylene fraction or C3- fraction and C4+ fraction, or combination of separation and hydrogenation processes of pyrolysis gas and C3+ fraction in presence of hydrogen, with respective conversion of acetylene and diene hydrocarbons of pyrolysis gas or C3+ fraction in the fractionation tower or the system of fractionation towers, with the catalyst integrated into the fractionation tower. C3- fraction is supplied to stage (a), (c) or (h) of the gas separation unit (8), while propane-propylene fraction is supplied to stage (g) of the gas separation unit (8);

[0038] (e) separation stage of ethane-ethylene fraction produced in stage (a), (c) or (d) of the gas separation unit (8), providing its separation in the fractionation tower or the system of fractionation towers into high purity ethylene and ethane supplied by recirculated flow into the mixing unit (2), or combination of separation and hydrogenation processes of ethane-ethylene fraction in presence of nitrogen with respective conversion of acetylene and diene hydrocarbons of ethane-ethylene fraction in the fractionation tower or the system of fractionation towers, with the catalyst integrated into the fractionation tower; (f) separation stage of C3+ fraction produced at deethanization stage (c) of the gas separation unit (8), providing its separation in the fractionation tower or the system of fractionation towers into propane-propylene fraction and C4+ fraction or propane-propylene fraction and butane-butylene fraction, and fraction C5+ with the flows being cooled using refrigerants or cold process flows of stage (a) and / or (c) of the gas separation unit (8); propane-propylene fraction is supplied to stage

[0039] (g) of the gas separation unit (8); C4+ fraction is discharged as a commercial product or supplied as a recirculated flow to the mixing unit (2); C4 fraction is discharged as a commercial product or supplied to stage (a) of the metathesis unit (9), or supplied as a recirculated flow to the mixing unit (2); C5+ fraction is used as a component of gasoline and is supplied to the outside of battery limit;

[0040] (g) separation stage of propane-propylene fraction produced in stage (c), (d) or (h) of the gas separation unit (8) providing its separation in the fractionation tower or the system of fractionation towers into pure propylene and propane supplied as a recirculated flow to the mixing unit (2) or discharged as a commercial product, or combination of hydrogenation and separation processes of propane-propylene fraction with its pre-hydrogenation in presence of hydrogen with respective conversion of methylacetylene and propadiene in gas or liquid phase using catalysts, with subsequent separation of the produced hydrogenation product in the fractionation tower or the system of fractionation towers;

[0041] (h) hydrogenation stage of pyrolysis gas supplied from the dehydration unit

[0042] (7), or of ethane-ethylene fraction supplied from stage (e) of the gas separation unit

[0043] (8), or of C2- fraction supplied from stage (c) of the gas separation unit (8), or of propane-propylene fraction supplied from stage (g) of the gas separation unit (8), or of C3- fraction supplied from stage (d) of the gas separation unit (8), or of C4+ fraction supplied from stage (f) of the gas separation unit (8), providing conversion of acetylene and / or diene components into respective alkene compounds in the hydrogenation reactor using catalyst in presence of hydrogen in one or several stages with intercooling. Depending on the hydrocarbon feedstock and target gas chemical products, the reaction products are further supplied to stage (a), (c), (d), (e), (f), or (g) of the gas separation unit (8);

[0044] (i) separation stage of C4+ fraction supplied from stage (d) of the gas separation unit (8), providing its separation in the fractionation tower or the system of fractionation towers into butane-butylene fraction and C5+ fraction with the flows being cooled using refrigerants or cold process flows of stage (a) and / or (c) of the gas separation unit (8); butane-butene fraction is discharged as a commercial product or supplied to stage (a) of the metathesis unit (9), or supplied as a recirculated flow to the mixing unit (2); C5+ fraction is used as a component of gasoline;

[0045] (9) metathesis unit consisting of: (a) metathesis stage providing reaction between C4- fraction supplied from stage (f) of the gas separation unit (8) and containing butene- 1 and butene-2, and ethylene supplied from stage (e) of the gas separation unit (8), with the production of propylene and butene- 1 isomerization into butene-2; (b) separation stage of metathesis products supplied from stage (a) of the metathesis unit (9), in the system of fractionation towers with extraction of commercial products: pure propylene, or propylene and isobutane, or propylene, isobutane and isobutene, - and unreacted components of C4- fraction, which are returned to stage (g) of the gas separation unit (8) or to the mixing unit (2) as a recirculated flow (patent RU 2670433, IPC C07C 11 / 04, C07C 11 / 06, C07C 2 / 76, C07C 4 / 04, C07C 7 / 00, claimed on 12 / 29 / 2017 published on 10 / 23 / 2018). Key disadvantages of the invention are as follows:

[0046] - no opportunity to maintain balance between water vapor production / use under conditions of feedstock supplied with a constantly changing ratio of ethane, LPG, gasoline fractions of inconstant composition;

[0047] - the process provides no involvement of refinery gases as gas feedstock, including flows with a high content of olefinic hydrocarbons (ethylene, propylene) supplied from delayed coking, catalytic cracking, visbreaking, ethylene polymerization, propylene polymerization units, and the feed flow treatment for further processing. General disadvantages of the inventions are: shortage or excess of water vapor produced at the unit, which results in extra costs for its generation or condensing, and the absence of involvement of gas feedstock with a high contents of olefinic hydrocarbons (ethylene, propylene) supplied from delayed coking, catalytic cracking, visbreaking, ethylene polymerization, propylene polymerization units, providing the feed flow treatment for further processing.

[0048] INVENTION DISCLOSURE

[0049] The claimed invention is aimed at performance of pyrolysis from hydrocarbon feedstock of different composition in gas and / or liquid phase with generation of effective interactions aimed at the fullest use of produced water vapor flows for energy supply to the gas separation unit.

[0050] The aim of the claimed invention is achieved by developed process flow for production of ethylene and propylene from hydrocarbon feedstock of different composition in gas and / or liquid phase, which includes the following units and stages connected by direct and reverse connections, in particular, by pipelines:

[0051] (100) receipt, treatment and mixing unit of feedstock having different composition supplied from oil refineries, providing feed flow mixing with recirculating flows and those separated in the gas separation unit (700) in the form of propane fraction, and the feed flow supply to the thermal splitting unit (200);

[0052] (200) thermal splitting unit consisting of the number of pyrolysis furnaces, each of them having a convection zone stage, a radiation zone stage, a water vapor generation zone stage, and providing alternating stages of the feedstock pyrolysis at the radiation zone stage of pyrolysis furnaces, and decoking by vapor bumoff with coke particle trapping by cyclones in each furnace, emission of the ultra-high- pressure (UHP) water vapor (simultaneous for the both stages) and its superheating by heat of the reaction furnace flue gases at the water vapor generation zone stage;

[0053] (300) pyrolysis gas primary fractionation and water quenching unit;

[0054] (400) compression unit providing compression of pyrolysis gas and hydrocarbon gas supplied from oil refinery to the pressure of 3.0-4.0 MPa at multistage compressors driven by supply of UHP water vapor; (500) alkali purification unit providing removal of impurities from pyrolysis gas, including carbon dioxide and hydrogen sulfide;

[0055] (600) dehydration unit providing removal of water vapors from the compressed pyrolysis gas using adsorbents to the depth excluding hydrate formation in the gas separation unit (700), without / with the pyrolysis gas cooling prior to dehydration to the temperature not lower than the hydrate formation one, with subsequent adsorbent recovery using dry hot gas: methane fraction from outside the battery limits and / or methane fraction, and / or methane-hydrogen fraction supplied from the gas separation unit (700) heated by high-pressure (HP) water vapor supplied from the thermal splitting unit (200);

[0056] (700) gas separation unit providing extraction of the required components from the dehydrated and compressed pyrolysis gas, but not limited to this combination. The demand for water vapor of the respective parameters in the thermal splitting (200), compression (400), dehydration (600), and gas separation units (700) is entirely covered by generated energy flows of water vapor with different pressure produced at water vapor generation zone stages of pyrolysis furnaces in the thermal splitting unit (200) and in the pyrolysis gas primary fractionation and water quenching unit (300), forming together an additional water vapor generation system. Water vapor flows of the same pressure generated in the pyrolysis furnaces using different hydrocarbon feedstock from the feedstock receipt, treatment and mixing unit (100), and in the pyrolysis gas primary fractionation and water quenching unit (300), are combined by a common pipeline with the respective consumers of compression (400), dehydration, (600) and gas separation units (700).

[0057] The designed set of units and components of their stages for production of ethylene and propylene ensures flexible functioning of production independently of the type of processed hydrocarbon feedstock and the range of target products due to development of direct and reverse connections between the said units and components. It is also viable to use hydrocarbon gases represented by fraction of light hydrocarbon gases as hydrocarbon feedstock, including flows with a high content of olefinic hydrocarbons (ethylene, propylene), which may be produced as a byproduct at oil refineries and / or gas processing plants of the region.

[0058] It is viable to use liquefied petroleum gases (LPG) as hydrocarbon feedstock, represented by mixture of ethane, propane and butanes, which may be produced as a by-product at the nearby plants of the region.

[0059] It is viable to use liquid hydrocarbon petroleum fraction - naphta and / or gasoil, which may be produced as a cheap by-product at a nearby oil refinery of the region.

[0060] LIST OF DRAWINGS

[0061] Figures 1-7 provide diagrams of possible implementation options of the claimed process flow for production of ethylene and propylene, with the following designations applied:

[0062] 100 - feedstock receipt, treatment and mixing unit, including:

[0063] 101 - feedstock receipt, separation and compression stage;

[0064] 102 - LPG receipt and evaporation stage;

[0065] 103 - liquid feedstock receipt and heating stage;

[0066] 200 - thermal splitting unit used for any kind of feedstock, including:

[0067] 201 - convection zone stage of ethane pyrolysis furnaces;

[0068] 202 - convection zone stage of LPG and naphta pyrolysis furnaces;

[0069] 203 - convection zone stage of naphta pyrolysis furnaces;

[0070] 204 - radiation zone stage of ethane pyrolysis furnaces;

[0071] 205 - radiation zone stage of LPG and naphta pyrolysis furnaces;

[0072] 206 - radiation zone stage of naphta pyrolysis furnaces;

[0073] 207 - stage of UHP water vapor generation zone of ethane pyrolysis furnaces;

[0074] 208 - stage of UHP water vapor generation zone of LPG and naphta pyrolysis furnaces; 209 - stage of UHP water vapor generation zone of naphta pyrolysis furnaces;

[0075] 210 - TLE stage of ethane pyrolysis furnaces;

[0076] 211 - TLE stage of LPG and naphta pyrolysis furnaces;

[0077] 212 - TLE stage of naphta pyrolysis furnaces;

[0078] 213 - vapor system stage;

[0079] 300 - primary fractionation and water quenching unit, including:

[0080] 301 - oil quenching stage;

[0081] 302 - pyrolysis gas water flushing stage;

[0082] 400 - compression unit, including:

[0083] 401 - compression stage;

[0084] 500 - alkali purification unit, including:

[0085] 501 - alkali purification stage;

[0086] 600 - dehydration unit, including:

[0087] 601 - pyrolysis gas pre-cooling stage;

[0088] 602 - pyrolysis gas dehydration stage;

[0089] 603 - dryer regeneration gas treatment stage;

[0090] 604 - condensate dehydration stage;

[0091] 700 - gas separation unit, for which using of certain unit stages, sequence of feed supply to the stages is determined by gas separation process and the range of target products, including:

[0092] 701 - pyrolysis gas cooling stage;

[0093] 702 - deethanization stage;

[0094] 703 - C3+ absorption stage;

[0095] 704 - fuel gas treatment stage;

[0096] 705 - C1 / C2 cooling stage;

[0097] 706 - acetylene hydrogenation stage;

[0098] 707 - C2 absorption stage;

[0099] 708 - depropanization stage;

[0100] 709 - ethylene refrigeration circuit stage. Step 1; 710 - ethylene refrigeration circuit stage. Step 2;

[0101] 711 - ethylene refrigeration circuit stage. Step 3;

[0102] 712 - propylene refrigeration circuit stage. Step 1;

[0103] 713 - propylene refrigeration circuit stage. Step 2;

[0104] 714 - propylene refrigeration circuit stage. Step 3;

[0105] 715 - PPF hydrogenation stage;

[0106] 716 - PPF separation stage;

[0107] 717 - C2 fraction separation stage;

[0108] 718 - PSA stage;

[0109] 719 - demethanization stage;

[0110] 720 - debutanization stage.

[0111] 1-147 - pipelines.

[0112] BRIEF DESCRIPTION OF DRAWINGS

[0113] Figure 1 contains one of the possible pyrolysis block diagrams allowing to process hydrocarbon feedstock of different composition.

[0114] The principle of the process line operation when operating on hydrocarbon feedstock of different composition in gas and / or liquid phase (given in Figure 1) is based on the feedstock supplied from outside the battery limits to the feedstock receipt, treatment and mixing unit (100), from which the treated feedstock is supplied to the thermal splitting unit (200). The process of hydrocarbon feedstock thermal splitting is performed by its dilution with water vapor produced in the thermal splitting unit (200) and process water supplied from the primary fractionation and water quenching unit (300). Pyrolysis gas obtained in the thermal splitting unit (200) is supplied to the primary fractionation and water quenching unit (300) for the pyrolysis gas to be cooled and separated from heavy components, and is routed via compression (400), alkali purification (500), and dehydration (600) units to the gas separation unit (700), for the commercial products (ethylene, propylene, BBF) to be obtained, and is supplied further to polymerization units and / or to the consumer, whereas hydrocarbon condensate going out of the compression unit (400) is dehydrated in the dehydration unit (600) and supplied to the gas separation unit (700). Primary fractionation and water quenching unit (300) and gas separation unit (700) also produce pyrolysis gasoline and pyrolysis resin, which are removed from the plant as by-products of the pyrolysis production. Ethane and propane extracted in the gas separation unit (700) are returned as recirculating flows into the thermal splitting unit (200), part of the propane flow is supplied also to the feedstock receipt, treatment and mixing unit (100), MHF from the gas separation unit (700) is used as a fuel in pyrolysis furnaces of the thermal splitting unit (200). The compression unit (400) and the primary fractionation and water quenching unit (300) provide for the supply of refinery gases from the feedstock receipt, treatment and mixing unit (100); the alkali purification unit (500) provides for the receipt of fresh alkali to perform alkali purification and discharge of spent alkali.

[0115] Figures 2-7 contain process flow diagrams of the feedstock receipt, treatment and mixing unit, thermal splitting unit, primary fractionation and water quenching unit, compression and alkali purification units, dehydration unit, and gas separation unit with internal interconnections of stages included in these units.

[0116] Figure 2 contains the process flow diagram of the feedstock receipt, treatment and mixing unit (100), to which refinery gases, LPG and naphta are supplied from outside the battery limits via pipelines 1, 4, and 7, respectively, to the stages of gas feedstock receipt, separation, and compression (101), LPG receipt and evaporation (102), and liquid feedstock receipt and heating (103). Stage (102) provides for the feedstock mixing with recirculating flow of the propane fraction supplied via pipeline 6 from PPF separation stage (716) of the gas separation unit (700). After refinery gases are treated for further processing at stage (101), they are supplied to the compression stage (401) of the compression unit (400) with a flow of hydrocarbon gases via pipeline 3 and / or directly to the pyrolysis gas water flushing stage (302) of the primary fractionation and water quenching unit (300) via pipeline 2, bypassing the thermal splitting unit (200). The supply is redistributed depending of the water vapor production balance at the vapor system stage (213) of the thermal splitting unit (200). After the feed LPG mixing with recirculating flow of propane supplied via pipeline 6 from stage (716) and evaporation, the treated LPG flow is supplied to convection zone stage of LPG and naphta pyrolysis furnaces (202) and / or convection zone stage of naphta pyrolysis furnaces (203) of the thermal splitting unit (200) via pipeline 5 for respective chemical transformations. The pre-heated flow of liquid naphta feedstock is supplied from stage (103) to convection zone stage of naphta pyrolysis furnaces (203) of the thermal splitting unit (200) via pipeline 8.

[0117] Figure 3 contains the process flow diagram of the thermal splitting unit (200), which is used for transformation of any kind of feedstock. The convection zone stage of ethane pyrolysis furnaces (201) provides for pre-heating of the gas feed flow obtained by mixing of recirculated ethane supplied via pipeline 9, returned from C2 fraction separation stage (717) of the gas separation unit (700), its mixing with a part of recirculated propane supplied from stage (716) via pipeline 6, and process vapor with the temperature of 180 °C and under the pressure of 0.7 MPa supplied via pipeline 138 for dilution of the feed flow from stage (213). Pre-heating of the feedstock, boiler water supplied via pipeline 17, and superheating of the UHP vapor flow with the temperature of 320 °C and under the pressure of 11.25 MPa supplied via pipeline 15 are provided by means of flue gases supplied from radiation zone stage of ethane pyrolysis furnaces (204) via pipeline 42, and then leaving the battery limits of the pyrolysis plant via pipeline

[0118] 18. Then the feed flow heated and diluted with the process vapor is supplied to radiation zone stage of ethane pyrolysis furnaces (204) in a common flow via pipeline 10, the heated boiler water is returned to the stage of UHP water vapor generation zone of ethane pyrolysis furnaces (207) via pipeline 16, and the UHP vapor superheated to 510 °C is supplied to vapor system stage (213) via pipeline

[0119] 19.

[0120] The convection zone stage of LPG and naphta pyrolysis furnaces (202) provides for pre-heating of the gas feed flow obtained by mixing of LPG feed flow supplied from stage (102) via pipeline 5 with naphta supplied from stage (103) via pipeline 8, and the process vapor with the temperature of 180 °C and under the pressure of 0.7 MPa supplied via pipeline 138 for dilution of the feed flow from stage (213). Pre-heating of the feedstock, boiler water supplied via pipeline 29, and superheating of the UHP vapor flow with the temperature of 320 °C and under the pressure of 11.25 MPa supplied from the stage of UHP water vapor generation zone of LPG and naphta pyrolysis furnaces (208) via pipeline 27 are provided by means of flue gases supplied from radiation zone stage of LPG and naphta pyrolysis furnaces (205) via pipeline 43, and then leaving the battery limits of the pyrolysis plant via pipeline 30. Then the LPG and naphta feed flow heated and diluted with the process vapor is supplied to radiation zone stage of LPG and naphta pyrolysis furnaces (205) in a common flow via pipeline 22, the heated boiler water is returned to stage (208) via pipeline 28, and the UHP vapor superheated to 510 °C is supplied to vapor system stage (213) via pipeline 31.

[0121] The convection zone stage of naphta pyrolysis furnaces (203) provides for pre-heating of the feed flow obtained by mixing of naphta flow supplied from stage (103) via pipeline 8 and process vapor with the temperature of 180 °C and under the pressure of 0.7 MPa supplied via pipeline 138 for dilution of the feed flow from stage (213). Pre-heating of the feedstock, boiler water supplied via pipeline 39, and superheating of the UHP vapor flow with the temperature of 320 °C and under the pressure of 11.25 MPa supplied from the stage of UHP water vapor generation zone of naphta pyrolysis furnaces (209) via pipeline 37 are provided by means of flue gases supplied from radiation zone stage of naphta pyrolysis furnaces (206) via pipeline 44, and then leaving the battery limits of the pyrolysis plant via pipeline 40. Then the naphta feed flow heated and diluted with the process vapor is supplied to radiation zone stage of LPG and naphta pyrolysis furnaces (206) in a common flow via pipeline 32, the heated boiler water is returned to stage (209) via pipeline 38, and the UHP vapor superheated to 510 °C is supplied to vapor system stage (213) via pipeline 41.

[0122] The mixture of hydrocarbons with water vapor pre-heated at the convection zone stages of pyrolysis furnaces (201), (202), and (203) is supplied to the radiation zone stage of ethane pyrolysis furnaces (204), radiation zone stage of LPG and naphta pyrolysis furnaces (205), and radiation zone stage of naphta pyrolysis furnaces (206) via pipelines 10, 22, and 32, respectively. High temperatures at the radiation zone stages of pyrolysis furnaces (204), (205), and

[0123] (206) are provided by combustion of fuel gas supplied from fuel gas treatment stage (704) to the thermal splitting unit (200) via pipeline 20. Flue gas flows generated therefrom, are supplied to convection zone stages of pyrolysis furnaces (201), (202), and (203) via pipelines 42, 43, and 44, respectively. In pyrolysis furnaces of stages (204), (205), and (206) operating in parallel mode with different feedstock at temperatures of 750-950°C, hydrocarbons of the feedstock are converted into unsaturated hydrocarbons, generally ethylene and propylene. Pyrolysis gas produced as a result of the conversions in pyrolysis furnaces of stages (204), (205), and (206) is supplied to TLE stage of ethane pyrolysis furnaces (210), TLE stage of LPG and naphta pyrolysis furnaces (211), and TLE stage of naphta pyrolysis furnaces (212) via pipelines 11, 23, and 33 for pyrolysis gas quenching (flash refrigeration) to terminate the pyrolysis reactions. Pyrolysis gas is quenched in TLE in stages (210), (211), and (212) by boiler water supplied from the stage of UHP water vapor generation zone of ethane pyrolysis furnaces (207), stage of UHP water vapor generation zone of LPG and naphta pyrolysis furnaces

[0124] (208), and stage of UHP water vapor generation zone of naphta pyrolysis furnaces

[0125] (209) via pipelines 13, 25, and 35, respectively. Due to pyrolysis gas cooling, UHP vapor with the temperature of 320 °C and under the pressure of 11.25 MPa is generated from the boiler water, which is returned to stages (207), (208), and (209) via pipelines 14, 26, and 36, respectively.

[0126] Stage of UHP water vapor generation zone of ethane pyrolysis furnaces

[0127] (207), stage of UHP water vapor generation zone of LPG and naphta pyrolysis furnaces (208), and stage of UHP water vapor generation zone of naphta pyrolysis furnaces (209) are designed for generation of UHP vapor of demineralized water supplied to the plant from outside the battery limits via pipeline 21 , heated boiler water supplied from stages (201), (202), and (203) via pipelines 16,28, and 38, respectively, and UHP vapor supplied from stages (210), (211), and (212) via pipelines 14, 26, and 36, respectively. The generated UHP vapor is supplied for superheating via pipelines 15, 27, and 37, and the boiler water is supplied for heating to stages (201), (202), and (203) via pipelines 17, 29, and 39, respectively.

[0128] The cooled down pyrolysis gas with the temperature of 380 °C and under the pressure of 0.2 MPa is supplied to the common pyrolysis gas header via pipelines 12, 24, and 34 and then supplied to the oil quenching stage (301) of the primary fractionation and water quenching unit (300) via pipeline 51 with the temperature of 400 °C and under the pressure of 0.09 MPa. The opportunity is provided to supply a part of the cooled pyrolysis gas from ethane pyrolysis furnaces to the pyrolysis gas water flushing stage (302) via pipeline 62, bypassing the oil quenching stage (301) of the primary fractionation and water quenching unit (300). In the coke bumoff mode, air is supplied to TLE stage of ethane pyrolysis furnaces (210), TLE stage of LPG and naphta pyrolysis furnaces (211), and TLE stage of naphta pyrolysis furnaces (212) via pipeline 147. Coke oxidation reactions result in generation of gas mixture consisting of carbon oxides, which, after passage through the cyclones, where solid coke particles are trapped, is then discharged from the plant via pipeline 146.

[0129] Thermal splitting unit (200) provides for the vapor system stage (213) designed for generation of vapor of different pressure for the needs of the pyrolysis production. This stage performs processing of UHP vapor (510°C, 11.25 MPa) supplied from stages (201), (202), and (203) via pipelines 19, 31, and 41, respectively, demineralized water supplied to the plant from outside the battery limits via pipeline 21, process water supplied from pyrolysis gas water flushing stage (302) of the primary fractionation and water quenching unit (300) via pipeline 46 (74°C, 0.045 MPa), and vapor from the battery limits supplied via pipeline 45 (400°C, 4.5 MPa) only in the startup mode until the rated capacity is reached. Therewith, the following is produced: process vapor with the parameters of 180°C and 0.7 MPa supplied via pipeline 138 for dilution of the feedstock prior to its supply to convection zone stages of pyrolysis furnaces; UHP vapor with the parameters of 510°C and 11.25 MPa supplied to stage (401) of the compression unit (400) via pipeline 47; HP vapor with the parameters of 400°C and 4.5 MPa supplied to ethylene refrigeration circuit stages (709), (710), (711) (steps 1-3) via pipeline 48, and propylene refrigeration circuit stages (712), (713), (714) (steps 1- 3) of the gas separation unit (700), and dryer regeneration gas treatment stage (603) of the dehydration unit (600); MP vapor with the parameters of 300°C and 1.8 MPa supplied to stage (720) of the gas separation unit (700) via pipeline 49; LP vapor with the parameters of 166°C and 0.6 MPa supplied to deethanization stage (702) and depropanization stage (708) of the gas separation unit (700) via pipeline 50.

[0130] Figure 4 contains the process flow diagram of the primary fractionation and water quenching unit (300), which includes oil quenching stage (301) providing quenching of pyrolysis gas supplied from stages (210), (211), (212) via pipeline 51 and partly returned pyrolysis gasoline fraction from stage (302) via pipeline 142 by recirculation of the cooled quenching oil (not shown in the figure). The oil quenching stage is provided with one or more fractionation towers with circulating and / or live reflux, and / or with extraction of water vapor in the waste heat boiler (not shown in the figure). The following flows are discharged from the oil quenching stage (301) to the outside of the battery limits: pyrolysis gasoline - via pipeline 52, pyrolysis resin - via pipeline 53, and coke - via pipeline 54, and the pyrolysis gas flow after oil quenching is supplied to the pyrolysis gas water flushing stage (302) via pipeline 55. In addition to the main pyrolysis gas flow, supply of pyrolysis gas from stage (210) via pipeline 62 and / or gas flow from stage (101) via pipeline 2 is provided to the stage for water flushing (quenching) (302). Flushing is performed by circulating wash water with the supply of pyrolysis gas water condensate from compression stage (401) of the compression unit (400) via pipeline 56. The main pyrolysis gas flow with the pressure of 0.045 MPa is supplied to stage (401) via pipeline 57 for compression to the pressure required for the subsequent fractionation of pyrolysis gas. The produced pyrolysis gasoline fraction is supplied to pyrolysis gas pre-cooling stage (601) of the dehydration unit (600) and partly to the oil quenching stage (301) via pipelines 58 and 142, respectively. Process water produced during vapor condensing from the pyrolysis gas flow is returned to step (213) via pipeline 46 for vapor generation.

[0131] Figure 5 contains the process flow diagram of the compression unit (400) and alkali purification unit (500) represented by compression stage (401) and alkali purification stage (501). Stage (401) provides compression of pyrolysis gas flows supplied from step (302) and from step (501) via pipeline 57 to the pressure required for subsequent fractionation of the pyrolysis gas. Supply of C2- hydrocarbon fraction is provided from pyrolysis gas cooling stage (701) via pipeline 62, refinery gases are supplied from stage (101) via pipeline 3 and removed from PSA stage (718) of the gas separation unit (700) via pipeline 63. Between the compression stages, pyrolysis gas fraction is supplied to the alkali purification stage (501). Water condensed during compression (water condensate) is separated from pyrolysis gas between the compressor stages in water separators and returned to stage (302) via pipeline 56, and hydrocarbons condensed during compression are separated from pyrolysis gas between the compressor stages in water separators, and after the last compression stage, pyrolysis gas and hydrocarbon condensate are supplied to stage (601) via pipelines 64 and 65, respectively. At the alkali purification stage (501) the pyrolysis gas flow via pipeline 58 from stage (401) is flushed in one or several sections with a circulating alkali solution with a makeup of fresh alkali solution supplied from outside the battery limit via pipeline 60, while the spent alkali solution is discharged from the plant via pipeline 59, and hydrocarbon condensate produced is supplied to debutanization stage (720) of the gas separation unit (700) via pipeline 61. As alkali purification unit (501) implies removal of impurities from the pyrolysis gas, including carbon dioxide and hydrogen sulfide, the stage provides also for removal of sour gases (not shown in the figure).

[0132] Figure 6 contains the process flow diagram of the dehydration unit (600) designed for removal of water vapors from the compressed pyrolysis gas in presence of adsorbents to the depth excluding further hydrate formation at the stage of gas separation without / with the pyrolysis gas cooling prior to dehydration to the temperature not lower than the hydrate formation one. At the pyrolysis gas pre-cooling stage (601), flows of: pyrolysis gas supplied via pipeline 64, pyrolysis gas hydrocarbon condensate supplied from stage (401) via pipeline 65, and pyrolysis gasoline supplied from stage (302) via pipeline 58, are cooled by propylene refrigerant supplied from stage (713) via pipeline 75. After its cooling, pyrolysis gas is supplied for dehydration to pyrolysis gas dehydration stage (602) via pipeline 66, pyrolysis gas condensate is supplied for dehydration to condensate dehydration stage (604) via pipeline 67, and the spent propylene refrigerant is returned to stage (712) via pipeline 74. At the pyrolysis gas dehydration stage (602), condensate dehydration stage (604), dehydration of pyrolysis gas flows supplied via pipeline 66 and pyrolysis gas condensate flows supplied via pipeline 67 is performed, after which they are supplied to the gas separation unit (700), to stages (701) and (702) via pipelines 68 and 69, respectively. Dehydration is performed by adsorbents due to the flows of circulating regeneration gas supplied from stage (603) via pipelines 71 and 73 to stages (602) and (604), respectively, and returned after dehydration to stage (603) for regeneration from stages (602) and (604) via pipelines 70 and 72, respectively. At the dryer regeneration gas treatment stage (603) circulating regeneration gas flow used for pyrolysis gas dehydration is regenerated by dry hot gas: methane fraction from outside the battery limits and / or methane fraction, and / or methane-hydrogen fraction supplied from step (704) via pipeline 76 and heated by HP water vapor supplied from stage (213) (not shown in the figure). Spent methane-hydrogen fraction is returned to stage (704) via pipeline 77.

[0133] Figure 7 contains the process flow diagram of the gas separation unit (700) with extraction of the required components from dehydrated compressed pyrolysis gas. Dehydrated pyrolysis gas under the pressure of 2.93 MPa is supplied from stage (602) via pipeline 68 to pyrolysis gas cooling stage (701), to which C2+ fraction is also supplied via pipeline 80 from C3+ absorption stage (703). Pyrolysis gas is cooled at stage (701) by C2- fraction supplied from stage (702) via pipeline 85, methane fraction and methane-hydrogen fraction (MHF) supplied from C1 / C2 cooling stage (705) via pipelines 86 and 87, respectively. As a result, cooled dehydrated pyrolysis gas with the temperature of minus 3 °C is produced at stage (701) and supplied to C3+ absorption stage (703) via pipeline 81 under the pressure of 2.93 MPa. C2- flow, that has transferred its cold, is returned to stage (401) via pipeline 62, MHF flow is supplied to stage (718) via pipeline 89 for extraction of hydrogen, while part of the flow is supplied to stage (704), and C2+ flow is supplied to deethanization stage (702) via pipeline 139 to be separated in the fractionation tower or the system of fractionation towers into C2- fraction and C3+ fraction. Gas separation unit provides for the fuel gas treatment stage (704), in which the flow of fuel gas supplied from outside the battery limits via pipeline 79 is mixed with the MHF flow supplied from stage (701) via pipeline 89, with production of MHF supplied via pipeline 20 to ensure operation of stages (204), (205), and (206), and also regeneration gas circulating in pipelines 76 and 77 of stage (603). Stage (702) provides for the separation of the mixed flow consisting of pyrolysis gas condensate supplied from stage (604) via pipeline 69, C2+ flow supplied from stage (701) via pipeline 139, and C2+ fraction flow supplied from stage (703) via pipeline 95. Ethylene refrigerant supplied from stage (711) via pipeline 102 and returned to the same stage via pipeline 103, and propylene refrigerant supplied from stage (712) via pipeline 88 and returned to the same stage (712) via pipeline 90 are used as refrigerants. C2- fraction produced after separation is supplied in gas phase to stage (701) via pipeline 85, C3+ fraction is supplied to stage (708) via pipeline 96 for propane extraction, and C2- fraction in liquid phase is supplied for separation to stage (703) via pipeline 94. C3+ absorption stage (703) is designed for extraction of C3+ hydrocarbons from dehydrated pyrolysis gas supplied from stage (701) via pipeline 81, and C2- fraction supplied from stage (702) via pipeline 94. Propylene refrigerant supplied from stage (712) via pipeline 91 and, having transferred its cold, returned to stage (712) via pipeline 92, is used as a refrigerant. The produced fractionation bottom product (C2+ fraction) is supplied to stage (702) via pipeline 95, the fractionation overhead (C- fraction) is supplied to acetylene hydrogenation stage (706) via pipeline 93 for hydrogenation of acetylene, and the knocked-out flow of C2+ fraction is returned to stage (701) via pipeline 80.

[0134] Gas separation process flow provides for the C1 / C2 cooling stage (705) designed for heat exchange between the flows of refrigerants and fractions containing C1-C2 hydrocarbons supplied from other unit stages, in order to cool ethylene refrigerant to lower temperatures. As a result, heat exchange takes place between the flows of ethylene refrigerant supplied from stage (711) via pipelines 127, 128, and 132, methane fraction, MHF and C2- fraction supplied from C2 absorption stage (707) via pipelines 78, 137, and 141, respectively, C2- fraction supplied from stage (706) via pipeline 104, and ethane-ethylene fraction supplied from demethanization stage (719) via pipeline 98. Therewith, C2- fraction supplied from acetylene hydrogenation stage (706) via pipeline 104 is the product of C2-fraction hydrogenation reaction, which is supplied from stage (703) via pipeline 93 for conversion of acetylene and / or diene components to respective alkene compounds in the hydrogenation reactor using catalyst in presence of hydrogen in one or several stages with intercooling. After that, flows of cooled ethylene refrigerant are returned from stage (705) to stage (711) via pipelines 126 and 129, ethylene refrigerant flow is returned to stage (709) via pipeline 130, methane fraction flow and MHF flow are returned to stage (701) via pipelines 86 and 87, respectively, C1-C2 fraction flow and C2- fraction flow are returned to stage (719) via pipelines 101 and 99, 100, respectively, C2- fraction flow is returned to stage (707) via pipeline 140, and ethane-ethylene fraction flow is returned to stage (717) via pipeline 105. C2 absorption stage (707), in turn, provides absorption of C2 components from methane fraction supplied from stage (719) via pipeline 107 and from C2- fraction supplied from stage (705) via pipeline 140, directing the obtained flows of MHF and methane fraction to stage (705) for cooling of C1-C2 fractions. C1-C2 fraction and C2- fractions are supplied to demethanization stage (719) via pipeline 101 and pipelines 99, 100, respectively, for extraction of methane fraction and hydrogen-containing gas by consistent cooling with ethylene refrigerant supplied from stage (711) via pipeline 125, by isentropic expansion and cooling of C2- fraction in one, two, or three expansion turbines, separation, and subsequent removal of methane fraction and / or hydrogen-containing gas flow in gas phase from the coldest separator, and / or zone of fractionation tower, and / or system of fractionation towers. The bottom of the fractionation tower is heated with propylene refrigerant supplied from stage (714) via pipeline 119, after which it is returned for compression to stage (713) via pipeline 97. As a result of separation, ethane-ethylene fraction is supplied to stage (705) via pipeline 98, while the produced methane fraction is supplied to stages (705) and (707) in two flows via pipelines 106 and 107, respectively, and the spent ethylene refrigerant with the temperature of minus 103 °C is supplied for compression to stage (709) via pipeline 121.

[0135] C3+ fraction supplied from stage (702) via pipeline 96 is separated in the fractionation tower, or the system of in-series fractionation towers, in depropanization stage (708). As a result, separation into propane-propylene fraction, or C3- fraction, and C4+ fraction is performed. C3- fraction is supplied via pipeline 114 to PPF hydrogenation stage (715), where its acetylene and / or diene components are converted to respective alkene compounds in the hydrogenation reactor using catalyst in presence of hydrogen, and then the products of the hydrogenation reaction are supplied to PPF separation stage (716) via pipeline 115. Hydrogen required for hydrogenation reactions is supplied from PSA stage (718) via pipeline 118. PSA stage is provided for separation of gas mixtures, namely, for hydrogen extraction from MHF supplied from stage (701) via pipeline 89 during multi-stage adsorption in the system of adsorbers. The PSA exhaust gas is supplied to stage (401) via pipeline 63, and concentrated hydrogen is partly used for hydrogenation reactions at stages (706) and (715) and / or is removed from the pyrolysis plant via pipeline 117.

[0136] After rectification process of depropanization stage (708), C4+ fraction is supplied to debutanization stage (720) via pipeline 84, where it is mixed with hydrocarbon condensate supplied from stage (501) via pipeline 61, and then separated in the fractionation tower, or the system of fractionation towers, into butane-butylene fraction (BBF) removed from the pyrolysis plant via pipeline 83 as a commercial product, and pyrolysis gasoline, also removed from the pyrolysis plant via pipeline 82 as a component of gasoline.

[0137] Gas separation unit of the pyrolysis plant is provided with the systems of ethylene refrigeration circuit and propylene refrigeration circuit, each of them including three steps. Ethylene refrigeration circuit stage of the first step (709) is fed with ethylene supplied from stage (717) via pipeline 108 and ethylene refrigerant supplied from stage (705) via pipeline 130 and from stage (719) via pipeline 121 for generation of ethylene refrigerant supplied to the second step of ethylene refrigeration circuit stage (710) via pipeline 131, where it is mixed with ethylene refrigerant supplied from stage (717) via pipeline 143, and then supplied to the third step of ethylene refrigeration circuit stage (711) via pipeline 136, where ethylene refrigerant flows from stage (702) via pipeline 103, from stage (705) via pipelines 126 and 129, and from stage (717) via pipeline 112 are also supplied for mixing. An opportunity is provided to remove part of the ethylene flow from stage (711) via pipeline 113 from the plant to the consumer or for other plant needs. The main part of ethylene is used as a refrigerant and is supplied with ethylene refrigerant flow to stage (702) via pipeline 102, with ethylene refrigerant flows to stage (705) via pipelines 127, 128, and 132, to stage (717) via pipelines 109, 110, and 111, and to stage (719) via pipeline 125. At the C2 fraction separation stage (717) C2 fraction supplied from stage (705) via pipeline 105 is separated in the fractionation tower, or the system of fractionation towers, into ethylene and ethane supplied as a recirculated flow to stage (201) via pipeline 9, while ethylene is supplied for compression to stage (709) via pipeline 108. Ethylene refrigerant flows produced at stage (711) and supplied via pipelines 109, 110, and 111, and propylene refrigerant flow from stage (712) supplied via pipeline 122 are used as refrigerants at stage (717), and after cooling, ethylene refrigerant flow is supplied to stage (710) via pipeline 143 and returned to stage (711) via pipeline 112, and propylene refrigerant flow is returned to stage (712) via pipeline 120. The system of propylene refrigeration circuit starts from the first step of the propylene refrigeration circuit stage (712), to which propylene refrigerant is supplied as a return refrigerant from stages (601), (702), (703), and (717) via pipelines 74, 90, 92, and 120, respectively. After compression, the obtained propylene refrigerant is supplied to stages (702), (703), and (717) via pipelines 88, 91, and 122, respectively, as a refrigerant with the specified properties. The main part of the propylene refrigerant flow is supplied to the second step of the propylene refrigeration circuit stage (713) via pipeline 144 at temperature of minus 11 °C and pressure of 0.165 MPa, where propylene refrigerant flows from stage (719) via pipeline 97 and from stage (716) via pipelines 123 and 124 are also supplied. After compression at the second step of refrigeration circuit, propylene refrigerant is partly supplied to the third step of the propylene refrigeration circuit stage (714) via pipeline 145, and partly supplied for cooling to stage (601) via pipeline 75. At the third compression step, a flow of compressed propylene refrigerant is produced, which is partly supplied to stage (719) via pipeline 119, while the main part of the propylene refrigerant is supplied to PPF separation stage (716) via pipelines 133, 134, and 135 at the temperature of 31 °C and under the pressure of 1.6 MPa. At stage (716), PPF fraction supplied from stage (715) via pipeline 115 is separated in the fractionation tower, or the system of fractionation towers, into pure propylene and propane. Pure propane is supplied as a recirculated flow to stage (102) and / or stage (201) via pipeline 6, and pure propylene is removed via pipeline 116 to outside the battery limits as a commercial product, and then is supplied to the consumer and / or for the plant own needs. Flows of propylene refrigerants supplied from stage (714) via pipelines 133, 134, and 135 are used as refrigerants in the fractionation towers, and after being spent, they are supplied to stage (713) via pipelines 123 and 124.

[0138] Example 1. According to the described pyrolysis technology, a calculation of pyrolysis process with operation using both liquid and gas feedstock has been performed, based on which material balance sheet for the process flows of feedstock and end products (Table 1) and material balance sheet for water vapor (Table 2) have been prepared.

[0139] During calculation of material balance for water vapor, it has been taken into account that during process implementation, water as a substance of energy flows may be subject to both change in its energy potential (water vapor is supplied to exchanger (debit) and removed from exchanger (credit) and phase change (for example, boiler water supply to transfer line exchanger TLE (water debit) and its evaporation in this exchanger (credit in the form of high pressure vapor produced). As follows from the calculation of energy flows, the claimed process flow allows to balance perfectly the debit and credit of water vapor as a substance of energy flows (Table 2).

[0140] Thus, the invention provides the process flow for production of ethylene and propylene from hydrocarbon feedstock of different composition in gas and / or liquid phase, which ensures performance of pyrolysis with the subsequent production of ethylene and propylene, as well as by-products, providing at the same time full use of the plant energy resources, in particular, water vapor, while the need in water vapor receipt from the battery limits and / or supply of its unused flows to outside the battery limits is eliminated.

Claims

CLAIMS1. The process flow for production of ethylene and propylene from hydrocarbon feedstock of different composition in gas and / or liquid phase, which includes the following units and stages connected by direct and reverse connections, in particular, by pipelines:(100) receipt, treatment and mixing unit of feedstock having different composition supplied from oil refineries, providing feed flow mixing with recirculating flows and those separated in the gas separation unit (700) in the form of propane fraction, and the feed flow supply to the thermal splitting unit (200);(200) thermal splitting unit consisting of the number of pyrolysis furnaces, each of them having a convection zone stage, a radiation zone stage, a water vapor generation zone stage, and providing alternating stages of the feedstock pyrolysis at the radiation zone stage of pyrolysis furnaces, and decoking by vapor bumoff with coke particle trapping by cyclones in each furnace, emission of the ultra-high- pressure (UHP) water vapor (simultaneous for the both stages) and its superheating by heat of the reaction furnace flue gases at the water vapor generation zone stage;(300) pyrolysis gas primary fractionation and water quenching unit;(400) compression unit providing compression of pyrolysis gas and hydrocarbon gas supplied from oil refinery to the pressure of 3.0-4.0 MPa at multistage compressors driven by supply of UHP water vapor;(500) alkali purification unit providing removal of impurities from pyrolysis gas, including carbon dioxide and hydrogen sulfide;(600) dehydration unit providing removal of water vapors from the compressed pyrolysis gas using adsorbents to the depth excluding hydrate formation in the gas separation unit (700), without / with the pyrolysis gas cooling prior to dehydration to the temperature not lower than the hydrate formation one, with subsequent adsorbent recovery using dry hot gas: methane fraction from outside the battery limits and / or methane fraction, and / or methane-hydrogen fraction supplied from the gas separation unit (700) heated by high-pressure (HP) water vapor supplied from the thermal splitting unit (200);(700) gas separation unit providing extraction of the required components from the dehydrated and compressed pyrolysis gas, characterized in that the demand for water vapor of the respective parameters in the thermal splitting (200), compression (400), dehydration (600), and gas separation units (700) is entirely covered by generated energy flows of water vapor with different pressure produced at water vapor generation zone stages of pyrolysis furnaces in the thermal splitting unit (200) and in the pyrolysis gas primary fractionation and water quenching unit (300), forming together an additional water vapor generation system. Water vapor flows of the same pressure generated in the pyrolysis furnaces using different hydrocarbon feedstock from the feedstock receipt, treatment and mixing unit (100), and in the pyrolysis gas primary fractionation and water quenching unit (300), are combined by a common pipeline with the respective consumers of compression (400), dehydration, (600) and gas separation units (700).

2. Process flow as per cl. 1 characteristic in that hydrocarbon gases produced by oil refineries and / or gas processing plants are used as feedstock.

3. Process flow as per cl. 1 characteristic in that liquefied petroleum gases (LPG) represented by the mixture of ethane, propane and butanes are used as feedstock.

4. Process flow as per cl. 1 characteristic in that liquid hydrocarbon petroleum fraction - naphta and / or gasoil - is used as feedstock.

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