SA94140602B1 - Thermal cracking of hydrocarbon feed - Google Patents

Abstract

Abstract: This invention relates to thermal cracking of a hydrocarbon feed comprising heating the feed in an oven (1); and feeding into the reaction chamber. (15); Separate the stream from the reaction chamber (15) into a stream of light products and a stream of heavy products; and presenting the heavy products stream to a vacuum distillation column (30) to separate the heavy products stream into fractions, where introducing the heavy products stream to the vacuum distillation column includes passing the heavy products stream through a valve to control the flow (36), and passing the heavy products stream up through an upright pipe (38) has a length such that the pressure of the liquid at the end of the upright tube (38) is damp for evaporation at its lower end, and the staple products stream passes thereafter through a conveyor channel (40) to the vacuum distillation column (30), and the structure of the conveyor channel (40) is such that The liquid pressure at its outlet is equivalent to the liquid pressure in the vacuum distillation column (30).

Description

1 Thermal cracking of hydrocarbon feed Full description

behind the invention

This invention relates to the thermal cracking of a hydrocarbon feed as described in Petroleum; 6th ed. 58; Elsevier 1947 pp. 7795-71.

Thermal cracking of a hydrocarbon feed involves heating the feed at a pressure in the range of

0 7 to © MPa at a temperature in the range of 740 to #71 "C; providing: feeding into a reaction chamber; and separating the stream from the reaction chamber into a light products stream.

And to a heavy products stream, and to present the heavy products stream to a vacuum distillation column to separate the heavy products stream into fractions at a pressure in the range from 1 to 10 kPa and at a temperature in the range of ITY 4060, then.

0 and in the well-known method; A channel is used to pass the heavy product stream to the vacuum distillation column. And because the pressure of the heavy products stream is greater than the pressure in the vacuum distillation column, the pressure drop in the channel must be equal to the pressure difference between the pressure of the heavy products stream and the pressure in the vacuum distillation column. One way of obtaining such a large pressure drop in the conduit is 0 to provide the conduit with a constrained opening; For example, in the form of a valve to control the flow. However; when the stream is choked

1 | Heavy products at the flow control valve; Rapid evaporation occurs. This rapid evaporation is accompanied by the formation of very small liquid droplets which cannot easily circulate in the vacuum distillation column. GENERAL DESCRIPTION OF THE INVENTION: This invention presents a simple method of quenching evaporation at a restricted orifice. for this purpose; The method of thermal cracking of a hydrocarbon feed according to the present invention includes heating the feed at a pressure in the range from 1.7 to ¾ MPa and at a temperature in the range from to 17 "C?; delivering the feed to a reaction chamber; and separating the stream from the chamber Reaction to a light product stream and to a heavy product stream; and to present the heavy product stream to a vacuum distillation column to separate the heavy product stream into fractions at a pressure in the range of 1 to 10 KJ and at a temperature in the range of 4060 ITY Whereas, introducing the heavy products stream to the ve column vacuum distillation involves passing the heavy products stream through a restrictive orifice; passing the products stream

: . heavy loads upward through an upright tube of such length that the pressure of the liquid is at the end of the upright tube so as to dampen evaporation at its lower end; the heavy product stream is then passed through a conveyor channel leading to a vacuum distillation column; The conveyor channel is arranged so that the pressure of the liquid at its outlet is equivalent to the pressure of the liquid in the vacuum distillation column. 0 The expression 'AB BLE fitting' is used in the specification and in claims to denote the characteristics of the conduit that contribute to the pressure drop in the conduit; Jie the dimensions of the conduit and other flow resistances such as bends or 1-shaped deflections in the conduit. BRIEF EXPLANATION OF THE DRAWINGS: The invention is now described by example in more detail by reference to the accompanying drawings 0 in which: : Figure 1 schematically shows a sequence of a method according to this invention; and Figure 1 schematically shows an alternative sequence of a method according to this invention Detailed Cia olf: Referring to Figure 1. The method sequence according to this invention includes an oven 1 equipped with a hearth ve, a chimney and a heating tube ALE furnace 1 The heating tube is connected to an inlet channel 17 and output channel A Output channel 4 connects to the inlet of the Vo reaction chamber The reaction chamber is further described in EP No. VION Reaction chamber output 11 is connected via channel 11 to a separator on Yo spiral separator Fig. 1 7 Helical separator 01 has two outputs; a YY output for light products and a YE outlet for heavy products. The YY output for light products is connected via a conduit (not shown) to a device (not shown) For extra processing of soft products. The YE outlet for heavy products is connected by a system of channels 76 to a vacuum distillation column .01 and the vacuum distillation column 700 has outlet channels 1 which connects to a vacuum pump (not shown) »| And outlet channel YY residue for heavy products and outlet channel YY medium product fraction. Devices for providing a suitable reflux current to the upper part of the vacuum fracturing column (Te) and a dewatering medium current to the lower part of the fracturing column (Fo) have not been clarified.

¢ The canal system includes 776 channel sections © in which a restrictive orifice is arranged in the form of a flow control valve FT, a standing tube YA connecting to the channel section YO, and a conveyor channel 66 carried out in a column: vacuum distillation 00 . And the length of the standing pipe, PA, is determined so that the liquid pressure is; during normal operation; At m the lower end of the upright tube TA so that the evaporation of the liquid at its lower end is suppressed. The term "evaporation suppression" is used in the specifications and claims to refer to the evaporation of at most a small amount of liquid (less than about 75 vol.). And the construction of the conveying channel is determined 0, so that the pressure of the fluid is; during normal operation; in the conduit £4 at outlet end 1; has two liquid pressure equivalents in the vacuum distillation column Ye and that is 0 such that the conduit £0 is designed so that the friction experienced by the liquid flowing through the conduit 0 is equal to the difference in pressure at The outlet of the upright tube YA and in the vacuum distillation column dy .0 : this condition; The carrier channel £0 includes several straight lines 7; connected by curved connectors in the form of connectors ;; TU and during normal operation; 700085 tons/day of hydrocarbon feed is continuously supplied to 1 furnace 1 at a pressure of MPa; The feed is heated to a temperature of 0045°C in the oven 1. Then the hot feed is served to the reaction chamber 11 where it is allowed to break the feed. The stream of products from the reaction chamber 11 is separated in a spiral separator IY 900 tons/day of light products JT through the outlet YY and to 7001 tons/day of heavy products JR through the outlet VE. Submission of heavy products through the system of channels 77 to the vacuum distillation column Ve, which operates at a pressure of 0 kPa and at a temperature of LA BOTA, and in the column of vacuum distillation 0, the stream of heavy products separates into [Ob 001 days from Gaseous fraction JT through the outlet channel FY and 5500 t/day of average fraction removed through the outlet channel FY and 5001 t/day of sale residue J through the residue outlet channel FY is lower The pressure at the flow control valve is 151 kPa. Yo and the length of the upright TA is VO wide and the presence of liquid in the upright YA prevents liquid evaporation at the end of the flow control valve YU which is located downstream.

° and the length of the carrier channel £ 0 is 71 meters, and the average inner diameter of the channel is + 0 cm, and the channel includes four conductors ;; U-shaped and the pressure of the liquid at the inlet of the conveying channel 6 is 01 kPa, and the pressure of the liquid at its outlet is equivalent to the pressure of the liquid in the vacuum distillation column . or near the TN flow control valve This evaporation is controlled and accompanied by the formation of very small liquid droplets. Figure Y illustrating an alternative sequence of method according to this invention is now indicated. and parts of the sequence which are similar to the sequence as described with reference to Figure 1; same reference number. In the sequence of Fig. 7, the stream from reaction chamber 11 in a distillation column ON is separated into a stream of 0 - light products removed through outlet ©1 and into a heavy products stream Jn through outlet OF and then introduced The stream of heavy products through the channel system 77 to the vacuum distillation column, Fo, and no devices were indicated to provide a suitable reflux stream to the upper part of the distillation column, Or ', and a stream from a dewatering medium to the lower part of the distillation column, 00 *. It can be for curved connectors ;; The shape of the letter LSU shown in Figures 1 and or Ne The curved connectors can have the shape of the letter A1. The presence of liquid in the upright pipe prevents the liquid from evaporating at the upstream end of the restrictive orifice. Omission of the upright tube results in evaporation at or near the restrictive orifice; This evaporation is not controlled and is accompanied by the formation of very small liquid droplets. in a vacuum distillation column; These very fine liquid droplets cannot be separated from the gas stream so that the liquid droplets are contained with © - the part exiting the vacuum distillation column through the outlet channel of the middle part or with the gaseous stream leaving the top of the vacuum distillation column through the outlet channel. This containment adversely affects the separation efficiency of the vacuum distillation column. The standing pipe LS FA described with reference to Figs 1 and 7 is a vertical pipe; It should be taken into account that the standing pipe can be an inclined pipe, provided that there is; during normal operation; Sufficient liquid in the upright tube to prevent evaporation.

Claims (1)

1 1 Claims of protection 1 1- A thermal cracking process for a hydrocarbon feed that includes heating the feed at Y pressure in the range from 1.7 to © MPa and at a temperature in the range from Ya.Y to 17©”m; supplying feed to reaction chamber; Separate the stream from the reaction chamber into a stream of products: ¢ light products and into a stream of heavy products and present the stream of heavy products ° to a vacuum distillation column to separate the stream of heavy products into 1 parts at a pressure in range from 1 to 10 kPa and at a temperature in the range v from 17? to 4060*C; Introducing the products stream 11681 to column A vacuum distillation involves passing the heavy products stream through a restrictive orifice; passing 4 streams of heavy products up through an upright tube of such length that the pressure ve of the liquid at the end of the upright tube is dampened to evaporation at its lower end; passing the heavy products stream 11 thereafter through a conveyor channel leading to the vacuum distillation column; The conduit shall be installed so that the pressure of the liquid at its outlet is equivalent to the pressure of the liquid in the vacuum distillation column. 7- A process according to claim 1 or where the stream is separated from the reaction chamber in a spiral separator Y into a stream of light products and a stream of heavy products 1.- A process according to the claim 1 or where the stream is separated from the reaction chamber in the Y distillation column into a stream of light products and heavy products