FI119938B - Thermal cracking of a hydrocarbon feed - Google Patents

Description

The present invention relates to a thermal cracking of a hydrocarbon feed such as that described in The Petroleum Hand-5 book, 6. p. Elsevier 1983, pp. 279-281.

Thermal cracking of a hydrocarbon feed comprises heating the feed at a pressure of 0.2 to 5 MPa and a temperature of 390 to 530 eC; feeding the feed into the reaction chamber; dividing the stream of 10 from the reaction chamber into a stream of light products and a stream of heavy products; and feeding a stream of heavy products to a vacuum distillation column to divide the stream of heavy products into fractions at a pressure of 1 to 10 kPa and a temperature of 320 to 400 ° C.

In the known process, a channel is used to direct a stream of heavy products to a vacuum distillation column. Since the pressure of the flow of heavy products is higher than the pressure of the vacuum distillation column, the pressure drop in the duct should be equal to the pressure difference between the pressure of the flow of heavy products and the pressure of the vacuum distillation column. One way to achieve this very large pressure drop in the duct is to provide the duct with a limited opening 25, for example in the form of a flow control valve. However, when a stream of heavy products is throttled through a flow control valve, rapid evaporation occurs. This rapid evaporation involves the formation of very small droplets of liquid which cannot be easily processed in a vacuum distillation column.

The present invention provides a simple way to reduce evaporation in a limited orifice.

To accomplish this, the method of thermal cracking a hydrocarbon feed according to the present invention comprises heating 35 feeds at a pressure of 0.2 to 5 MPa and a temperature of 390 to 530 ° G; feeding the feed into the reaction chamber; dividing the stream from the reaction chamber into a stream of light products and a stream of heavy products; and 5 feeding the heavy product stream to a vacuum distillation column to divide the heavy product stream into fractions at a pressure of 1 to 10 kPa and a temperature of 320 to 400 ° C, wherein feeding the heavy product stream to the 10 vacuum distillation columns includes , conducting a flow of heavy products upwardly along a riser pipe of a length such that the liquid pressure at the end of the riser pipe is such that vaporization is prevented at its lower end, and then passing a stream of heavy products through a downstream conduit such that the liquid pressure at its outlet corresponds to the liquid pressure in the vacuum distillation column. The term "transmission channel design" is used in the specification and claims to refer to transmission channel features that contribute to pressure drop in the transmission channel, such as transmission channel dimensions and other flow resistances in the transmission channel, such as bends or 25 U turns.

The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which:

Figure 1 schematically shows one process apparatus according to the present invention; Figure 2 schematically shows an alternative process apparatus according to the present invention.

Referring to Figure 1. The process apparatus of the present invention includes a furnace 1 35 with a burner 2 and an outlet pipe 3 and a heating pipe 3 4 located in the furnace 1. The heating pipe 4 is connected to an inlet duct 7 and an outlet duct 9 through

The float passage channel 9 is connected to the inlet of the reaction chamber 15. The reaction chamber is more clearly described in EP-A-5 Examination Publication 7,656. The outlet of the reaction chamber 15 is connected via channel 17 to a separator in the form of a cyclone separator 20.

The cyclone separator 20 has two outlets, an outlet 21 for light products and an outlet 24 for heavy yields. The light products outlet 21 is connected via a channel (not shown) to a device (not shown) for further processing of light products. The heavy-duty outlet 24 is connected via a duct system 26 to a vacuum distillation column 30. 15 The vacuum distillation column 30 has a float outlet conduit 31 connected to a vacuum pump. (not shown in the figure), a bottom product flushing channel 32 for heavy products and a flushing channel 33 for a mid product fraction. Apparatus for providing a suitable return stream to the top of the vacuum distillation column 20 and for providing a stripping medium stream to the bottom of the vacuum distillation column 30 are not shown.

The conduit system 26 includes a conduit portion 35 provided with a restricted orifice in the form of a flow control valve 36, a riser pipe 38 connected to the conduit portion 35, and a transfer conduit 40 to a vacuum distillation column 30.

The length of the riser 38 is determined such that, during normal operation, the fluid pressure 30 at the lower end of the riser 38 is such that evaporation of the liquid at the lower end of the tube is prevented. The term "liquid vaporization inhibition" is used in the specification and claims to indicate that up to a small amount of liquid is vaporized (less than about 5% by volume).

4

The structure of the transfer conduit 40 is determined such that, during normal operation, the fluid pressure at the outlet end 41 of the transfer tube 40 corresponds to the fluid pressure in the vacuum pressure column. This means that the port 5 of port 5 is designed such that the friction encountered by the fluid flowing through port 40 is equal to the pressure difference between the outlet of riser 38 and the vacuum distillation column 30. In this case, the transport channel 40 includes a few straight lines 43 interconnected by curved spacers in the form of U-shaped spacers 44.

During normal operation, 3,097 t / d (3,000 ton / p) of hydrocarbon feed is continuously fed to the furnace 1 under 3 MPa pressure and heated to 15,450 'G in the furnace. The heated feed is then fed to the reaction chamber 15 where the feed is allowed to crack. The product stream from the reaction chamber 15 is divided into cyclone separator 20 into light products [914 t / d (900 t / d)] discharged through outlet 21 and heavy products 20 [2 134 t / d (2 100 t / d)] , which are removed via the outlet 24. Heavy products are fed: through a duct system 26 to a vacuum distillation column 30 operating at 5 kPa and 380 ° C. In a vacuum distillation column 30, a stream of heavy products is divided into 25 gaseous fractions [213 t / d (200 ton / p) removed through outlet 31, middle fraction [406 t / d (400 t / d)] discharged through outlet 33, and a base product [1,524 t / d (1,500 ton / d)], which is discharged through the outlet product 32 of the base product.

30 The pressure drop in the flow control valve 36 is 150 kPa.

The riser tube 38 has a length of 15 m; the presence of liquid in the riser 38 prevents the liquid from evaporating downstream of the flow control valve 36 when viewed downstream.

5

The length of the transfer conduit 40 is 70 m, the average inside diameter of the conduit 40 is 50 cm, and the conduit includes four U-shaped spacers 44. The liquid pressure at the inlet 40 is 60 kPa and 5 at its outlet corresponds to the liquid pressure 30.

The omission of the riser 38 would result in or near the flow control valve 36, which is uncontrolled and involves the formation of extremely small droplets of liquid.

Referring now to Figure 2, which shows one alternative process apparatus according to the present invention, those parts of the apparatus which are similar to the apparatus described in connection with Figure 1 have the same reference numeral.

In the apparatus of Figure 2, the stream from the reaction chamber 15 is divided into a distillation column 50 into a stream of light products discharged through outlet 51 and a stream of heavy products discharged through outlet 52.

The heavy goods stream is then fed through a duct system 26 to a vacuum distillation column 30.

Apparatus for providing a suitable return flow to the upper part of the vacuum distillation column 50 and for providing a stripping medium stream to the lower part of the vacuum distillation column 50 are not shown in the figure.

The curved spacers 44 may be U-shaped as shown in Figures 1 and 2, or the curved spacers 30 may be L-shaped.

The presence of liquid in the riser prevents vaporization of the liquid downstream of the limited opening, leaving the riser off would result in or near a restricted opening, which is uncontrolled and associated with the formation of extremely small droplets of liquid. These small fine liquid droplets cannot be separated in the vacuum distillation column from the gas stream so that the liquid droplets enter the fraction exiting the vacuum distillation column through the central passage or through the top of the vacuum distillation column. This involvement adversely affects the differential performance of the vacuum column.

The riser tube 38 10 illustrated in connection with Figures 1 and 2 is a vertical tube; it will be appreciated that the riser may also be an inclined tube provided that, during normal operation, the riser has sufficient fluid to prevent evaporation.

Claims (4)

7 A process for thermal cracking of carbon black feed, characterized in that it comprises heating the feed at a pressure of 0.2 to 5 MPa and a temperature of 390 to 530 ° G; feeding the feed into the reaction chamber; dividing the stream from the reaction chamber into a stream of light products and a stream of heavy products; and feeding a stream of heavy products into a vacuum distillation column to fractionate the stream of heavy products at a pressure of 1 to 10 kPa and a temperature of 320 to 400 ° C, wherein feeding the stream of heavy products to a vacuum distillation stream comprises conducting a flow of heavy products upwardly along a riser pipe of a length such that the liquid pressure at the end of the riser is such that vaporization is prevented at its lower end, and then passing a heavy product stream to a vacuum distillation passage that the liquid pressure at its outlet corresponds to the liquid pressure in the vacuum distillation clone. 2. A method as claimed in claim 1, c h a r a c t e r i z e d in that the transport channel comprises a plurality of straight sections connected by curved spacers. 3. Förfarande enligt patentkrav 1 eller 2, kän-netecknat av att strömmen som kommer fr an reactions-30 combing separatoras i en cyclone separator account en Ström med Lätta produkter och en Ström med Tunga produkter. Process according to claim 1 or 2, characterized in that the stream 30 from the reaction chamber is divided into a stream of light products and a stream of heavy products in a cyclone separator. A process according to claim 1 or 2, characterized in that the stream from the reaction chamber is divided into a stream of light products and a stream of heavy products in a distillation column. i 8 I. Förfarande för Värmekrackning av en kolvätein-matning, k n e t e c k n a t av att det omfattar nppvärmning 5 av inmatningen i et tryck i omradet 0.2 - 5 MPa and temperature at 390-530 ° C; inmatiling av inmatningen account en reaction chamber; separering av flödet fran re-aktionskammaren account en Ström med Lätta produkter ocli account en Ström med Tunga produkter; och inmatning av strömmen 10 med Tunga produkterna account en undertrycksdestillationskolonn för separering av de Tunga produkterna account fractiontioner i ett tryck i omradet. 1 to 10 kPa at a temperature of 320 to 400 ° C, and the color of the product is used in the manufacture of a Tunga product account under pressure. omfattar 15 ledning av strömmen med Tunga produkter genom en begränsad öppning; ledning av strömmen med Tunga producter drops the slope to the lcrrätt rör, the stem sticks to a hundred att. i ändan av det lodräta röret. and the colors of the structure of the image, the color of the structure, the color of the structure of the image, the color of the structure of the image. 25 2. Förfarande enligt patentkrav 1, tongue-in-cheek av att förflyttningsledningen innehäller flera raka delar som är mosslänkade med böjda mellanstycken. 4. Förfarande enligt patentkrav 1 eller 2, tecknat av att strömmen som kommer frän reaction-chamber separeras i en distillatiohskölonn account en Ström 35 med Lätta produkter och en Ström med Tunga produkter.