JPH0613710B2 - Pyrolysis heater - Google Patents

Description

Detailed Description of the Invention

The present invention relates to an improved pyrolysis heater for cracking complex hydrocarbon molecules into simple units.

An example of a prior art pyrolysis heater is US Pat. No. 3,274,978. Such a heater comprises two parallel radiant heating zones, as well as a single convection zone above the radiant heating zones. The vertically arranged coils are heated by groups of high intensity radiant burners in vertical rows on each wall of the radiant heating region.

According to one aspect of the invention, a radiant heating section and a convection heating section located above and diverging from the radiant heating section (in gas flow communication with said heating section). There is provided a pyrolysis heater including: The radiant heating section comprises at least two rows of vertical tubes, with the tubes in each row lying on a single plane orthogonal to the vertical plane passing through the longitudinal axis of the convection section. The radiating section
With a radiant burner located in the floor, each tube bank row has one row of burner banks on each side of the tube. The radiating section is preferably shaped such that its width is substantially equal to its length (ie the width of the radiating section is 80% to 120% of its length, preferably 90% to 110%). is there. In a particularly preferred embodiment, the height of the radiating section is also substantially equal to its length, so that the radiating section has an essentially cubic shape. The tubes in each row are arranged to provide one or more paths for feed introduced into the tubes (tubes that provide more than one path are referred to as "coils"), and each tube row has one or more paths. Including the coil. Thus, according to one embodiment, for example, two tubes in a single row are interconnected to form two vertical paths through the radiating section (double-pass coil), the row comprising a plurality of double-pass coils. Can be included. Similarly, three or more tubes may be coupled together to provide three or more paths through the radiant heating section, with each row having one or more such coils. In forming a coil having more than one pass, multiple tubes providing a first pass can be combined with a single tube providing a second pass. The tubes in each row are
It may have the same inner diameter or different inner diameters.

The coils of the radiant section are designed to crack with a short residence time to produce ethylene (residence time less than 0.5 seconds). Generally, the residence time is 0.07 seconds or more, and preferably the residence time is designed to be 0.2 seconds or less. The total length of the coil in the radiating section is generally at least 27 m (30 fibers).
-)), Generally not exceeding 72 meters (80 feet), the coil being constructed of one or more tubes of suitable length. The overall length, inner diameter and other conditions of the coil are adjusted to provide a short dwell time as described above. According to a preferred embodiment, the height of the heater (direction parallel to the tube) is about 18 m (20 m).
The length and width of the heater have interrelated dimensions, as described above. In a particularly preferred embodiment, the radiating section has at least 16 coils, each coil being made up of one, two or more tubes. Vertical tubes used in pyrolysis heaters generally have an inner diameter of 2.5 to 10 cm (1 to 4 "), preferably 2.5 to 5 cm (1 to 2") for the inlet tube. The inside of the tube may be smooth or may include fins. The exit coil of the coil can have a larger diameter. A tube, when placed in a coil to provide a plurality of paths, is provided with a feed to each of the plurality of tubes, the plurality of tubes providing a single path through the radiating section, and It is arranged to connect at the outlet to a manifold that connects to a single tube having a larger diameter that provides a second pass through the radiating section.

Next, the present invention will be described in more detail with reference to specific examples shown in the drawings. The outlet of the coil is preferably connected to a suitable transfer line exchanger to allow the effluent to cool rapidly below the cracking temperature. In the preferred embodiment, the temperature of the effluent removed from the coil is 76
It is about 0 to 954 ° C (1400 to 1750 ° F). As known in the art, the feed to the coil is generally diluted with steam. Radiating section
11, including a convection section 12 located above the radiation section 11 and laterally diverging from the radiation section, the interior of the radiation section 11 being in gas flow communication with the convection section 12 via a horizontal passage 13. A pyrolysis heater 10 is shown. The radiating section 11 comprises a plurality of vertical tube rows 14, each tube row 14 lying in a single plane substantially orthogonal to the plane passing through the longitudinal axis of the convection section 12. As shown in FIG. 1, four vertical tubes 14
There is. The radiant section includes a plurality of radiant burners 15 located on the floor of the radiant section 11. burner
15 are arranged in rows parallel to the vertical tube rows 14, each tube row 14 having 2
There is one row of floor burners 15 and one row of burners 15 is on the side of the vertical tube row 14. The burners on each side of the vertical tube are preferably equally spaced from the vertical tube. The vertical tubes in each row are interconnected to provide a radiant coil for pyrolyzing the feed.

As shown in FIGS. 1 and 2, the vertical tubes in each row are arranged to provide two paths through which a feed stream containing hydrocarbons to be pyrolyzed is provided. More specifically, a plurality of tubes 14a in one row
Is connected to a horizontal manifold 21 which is connected to a vertical tube 14b having an inner diameter larger than this tube 14a. The upper end of tube 14a is connected to an inlet manifold 22 for supplying the hydrocarbon feed to tube 14a, and the top of tube 14b is connected to a transfer line exchanger 23 for receiving the pyrolysis effluent. . Thus, as shown, the hydrocarbon to be pyrolyzed is introduced at the top of tube 14a, passes downwards through tube 14a to manifold 21, and then upwards through tube 14b. It is introduced into the transfer line exchanger 23. As is known in the art, the feed to be pyrolyzed is preheated in a convection tube 24 located in the convection section 12, and the preheated feed is introduced into the tube 14a via a manifold 22. Thus, for example, a single row of vertical tubes can be split into two tube sets, each set forming one coil. Each coil consists of twelve tubes 14a providing a first path, each of the twelve tubes 14a being connected to a single tube 14b providing a second path. In the preferred embodiment, the height, length and width of the radiating section 11 are equal to each other. Although the heater is shown with a single radiant section, it is also possible to construct the heater with two radiant sections, each in gas flow communication with the convection section.

[Brief description of drawings]

FIG. 1 is a schematic view of a pyrolysis heater according to the present invention.

FIG. 2 is a schematic view of a row of tubes in a pyrolysis heater according to the present invention.

[Explanation of symbols]

 10 Pyrolysis Heater 11 Radiant Section 12 Convection Section 14 Vertical Tube Group Row 21, 22 Manifold

Claims (8)

[Claims] 1. A radiant section and a convection section in gas flow communication with the radiant section, wherein at least two rows of vertical tubes are arranged in the radiant section, the radiant section comprising: The vertical section of the convection section contains at least two rows of vertical tubes parallel to each other in a plane perpendicular to the plane passing through the longitudinal axis of the convection section, and the floor of the radiating section is provided with a plurality of radiant burners parallel to the vertical tubes. It is arranged in a row,
Each vertical bank group has a first burner bank row on one side of the vertical tube bank and a second burner bank row on the other side of the vertical tube bank, the radiating section comprising: A pyrolysis heater, characterized in that it has a width substantially equal to the length of the radiant section. 2. The pyrolysis heater of claim 1, wherein the tubes in a single row are interconnected to form a plurality of coils. 3. A pyrolysis heater according to claim 2, wherein the tubes in the coils have different diameters. 4. A pyrolysis heater according to claim 3, wherein the tubes in the coil are interconnected to form two vertical paths through the radiating section. 5. The coil according to claim 3, wherein the coil is 27.
A pyrolysis heater with a length of 30 to 80 meters (30 to 80 feet). 6. The pyrolysis heater of claim 2, wherein the length of the radiant section is substantially equal to its width. 7. The coil according to claim 6, wherein the coil is 27.
A pyrolysis heater with a length of 30 to 80 meters (30 to 80 feet). 8. The pyrolysis heater of claim 7, wherein the tubes in the coil are interconnected to form two vertical passes through the radiant section.