阅读说明：本技术 辐射炉管 (Radiation furnace tube ) 是由 李锦辉 李春燕 宋学明 孙长庚 郭慧波 韦刘轲 刘磊 王琥 安冬旭 黄佳平 于 2020-06-18 设计创作，主要内容包括：本发明提供一种辐射炉管,包括至少一组2：1：……：1：1型炉管,每组2：1：……：1：1型炉管包括第一程管、第二程管、第三程管……和第N程管,N为偶数,第一程管有两根,第二程管、第三程管……和第N程管各有一根；两根所述第一程管通过二合一回弯弯头与所述第二程管连通,所述第二程管、第三程管……和第N程管依次通过上部180°回弯弯头或下部180°回弯弯头依次蛇形连通。由于第一程管采用两根小直径炉管,利用它比表面积大的特点可达到介质快速吸热升温的目的。由于第二、三、……、N程管采用逐级扩径,可选用较大内径的炉管来降低烃分压,提高裂解选择性。(The invention provides a radiation furnace tube, which comprises at least one group 2: 1: … …: 1: type 1 furnace tube, each group 2: 1: … …: 1: the 1-type furnace tube comprises a first pass tube, a second pass tube, a third pass tube … … and an Nth pass tube, wherein N is an even number, the number of the first pass tubes is two, and the number of the second pass tube, the number of the third pass tube … … and the number of the Nth pass tube are respectively one; the two first pass pipes are communicated with the second pass pipe through a two-in-one return bend, and the second pass pipe, the third pass pipe … … and the Nth pass pipe are sequentially communicated in a snake shape through an upper 180-degree return bend or a lower 180-degree return bend. Because the first pass tube adopts two small-diameter furnace tubes, the purpose of rapid heat absorption and temperature rise of the medium can be achieved by utilizing the characteristic of large specific surface area of the first pass tube. Because the second, third, … … and N path tubes are expanded step by step, a furnace tube with larger inner diameter can be selected to reduce the partial pressure of hydrocarbon and improve the cracking selectivity.)

1. A radiant furnace tube, comprising at least one set 2: 1: … …: 1: type 1 furnace tube, each group 2: 1: … …: 1: the 1-type furnace tube comprises a first pass tube, a second pass tube, a third pass tube … … and an Nth pass tube, wherein N is an even number, the number of the first pass tubes is two, and the number of the second pass tube, the number of the third pass tube … … and the number of the Nth pass tube are respectively one; wherein:

the two first pass pipes are communicated with the second pass pipe through a two-in-one return bend, and the second pass pipe, the third pass pipe … … and the Nth pass pipe are sequentially communicated in a snake shape through an upper 180-degree return bend or a lower 180-degree return bend.

2. The radiant furnace tube of claim 1, wherein: the upper end of the two-in-one return bend is provided with two upward inlets and an upward outlet, and the two inlets and the outlet are mutually communicated in the two-in-one return bend; the lower ends of the two first-pass pipes are respectively connected with two inlets of the two-in-one return bend, and the lower ends of the second-pass pipes are connected with an outlet of the two-in-one return bend.

3. The radiant furnace tube of claim 2, wherein: the lower part of the two-in-one return bend is connected with a guide rod.

4. The radiant furnace tube of claim 1, wherein: each upper 180-degree return bend is upwards connected with a pull rod, and the pull rods can be connected with suspension springs.

5. The radiant furnace tube of claim 1, wherein: and each lower 180-degree return bend is downwards connected with a guide rod.

6. The radiant furnace tube of claim 1, wherein: the inlet diameters of the upper 180-degree return bend and the lower 180-degree return bend are not larger than the outlet diameter; correspondingly, the inner diameters of the second pass pipe, the third pass pipe, … … and the Nth pass pipe are gradually enlarged.

7. The radiant furnace tube of claim 1, wherein: the second pass, third pass … …, and nth pass each have a larger or equal inner diameter than the previous pass.

8. The radiant furnace tube of claim 1, wherein: the first pass tube, the second pass tube, the third pass tube … … and the nth pass tube are all vertically arranged and maintained on the same plane.

9. The radiant furnace tube of claim 1, wherein: and the inner walls of the (N-1) th tube and the (N-6) th tube are provided with enhanced heat transfer elements.

10. The radiant furnace tube of claim 9, wherein: the enhanced heat transfer element is in a water drop shape, a triangular pyramid shape or a semi-ellipsoid shape and is discretely arranged on the inner walls of the (N-1) th tube and the Nth tube.

Technical Field

The invention relates to the field of petrochemical industry, in particular to an N (N is an even number) path radiation furnace tube which is used in a tubular furnace in petrochemical industry production.

Background

Ethylene cracking technology adopted in petrochemical ethylene plants mainly comes from companies such as LUMMUS, Technip, Kellog & Braun Root, Linde and the like in European and American countries and HQCF cracking furnaces developed by Chinese petroleum institute.

As for the ethylene cracking furnace radiant tubes, there are a type W (1-1-1-1) and a type M (1-1-1-1-1) from Technip corporation for the multi-pass tubes. The first tube pass and the second tube pass of part of the multi-pass furnace tubes are connected by adopting a combined tube fitting of 'two-in-one tube fitting (+ straight tube) + 180-degree elbow'.

The connection mode of the combined pipe fitting using the two-in-one pipe fitting (+ straight pipe) and the 180-degree elbow ensures that the first pipe pass is not completely two straight pipes, so that the specific surface area of the first pipe pass is limited; the two-in-one pipe fitting is connected with two rigid pipe fittings with 180-degree elbows, so that the deformation coordination of the furnace tube is not facilitated, and the stress of the furnace tube is increased; moreover, the number of parts and the number of welding lines are large, which is not favorable for quality control.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provide a radiation furnace tube which has good mechanical properties while improving the cracking process performance.

In order to achieve the purpose, the invention adopts the technical scheme that:

a radiant furnace tube, comprising at least one set 2: 1: … …: 1: type 1 furnace tube, each group 2: 1: … …: 1: the 1-type furnace tube comprises a first pass tube, a second pass tube, a third pass tube … … and an Nth pass tube, wherein N is an even number, the number of the first pass tubes is two, and the number of the second pass tube, the number of the third pass tube … … and the number of the Nth pass tube are respectively one; wherein:

the two first pass pipes are communicated with the second pass pipe through a two-in-one return bend, and the second pass pipe, the third pass pipe … … and the Nth pass pipe are sequentially communicated in a snake shape through an upper 180-degree return bend or a lower 180-degree return bend.

The radiant furnace tube, wherein: the upper end of the two-in-one return bend is provided with two upward inlets and an upward outlet, and the two inlets and the outlet are mutually communicated in the two-in-one return bend; the lower ends of the two first-pass pipes are respectively connected with two inlets of the two-in-one return bend, and the lower ends of the second-pass pipes are connected with an outlet of the two-in-one return bend.

The radiant furnace tube, wherein: the lower part of the two-in-one return bend is connected with a guide rod.

The radiant furnace tube, wherein: each upper 180-degree return bend is upwards connected with a pull rod, and the pull rods can be connected with suspension springs.

The radiant furnace tube, wherein: and each lower 180-degree return bend is downwards connected with a guide rod.

The radiant furnace tube, wherein: the inlet diameters of the upper 180-degree return bend and the lower 180-degree return bend are not larger than the outlet diameter; correspondingly, the inner diameters of the second pass pipe, the third pass pipe, … … and the Nth pass pipe are gradually enlarged.

The radiant furnace tube, wherein: the second pass, third pass … …, and nth pass each have a larger or equal inner diameter than the previous pass.

The radiant furnace tube, wherein: the first pass tube, the second pass tube, the third pass tube … … and the nth pass tube are all vertically arranged and maintained on the same plane.

The radiant furnace tube, wherein: and the inner walls of the (N-1) th tube and the (N-6) th tube are provided with enhanced heat transfer elements.

The radiant furnace tube, wherein: the enhanced heat transfer element is in a water drop shape, a triangular pyramid shape or a semi-ellipsoid shape and is discretely arranged on the inner walls of the (N-1) th tube and the Nth tube.

Compared with the prior art, the invention has the beneficial effects that:

1. the first pass tube adopts two small-diameter furnace tubes, and the purpose of rapid heat absorption and temperature rise of the medium can be achieved by utilizing the characteristic of large specific surface area of the first pass tube.

2. The second, third, … … and N process tubes are expanded gradually, and the furnace tube with larger inner diameter is selected to reduce the partial pressure of hydrocarbon and improve the cracking selectivity.

3. The inner walls of the furnace tubes of the (N-1) th pass tube and the Nth pass tube are provided with the enhanced heat transfer elements, so that the heat transfer effects of the (N-1) th pass tube and the Nth pass tube can be enhanced, the formation of a deposit layer on the inner surface of the heat exchange tube is reduced, the wall temperature and the coking rate of the furnace tubes are effectively reduced, and the operation period of the cracking furnace is further prolonged.

Drawings

FIG. 1 is a schematic view of a radiant furnace tube according to the present invention.

FIG. 2 is a schematic view of a radiant furnace tube according to the present invention.

FIG. 3 is a schematic view of a two-in-one return bend and guide rod.

Fig. 4 is a schematic view of an upper 180 ° return bend and a pull rod.

Fig. 5 is a schematic view of the lower 180 ° return bend and guide bar.

FIG. 6 is a schematic view of a reinforcement element in a furnace tube.

FIG. 7 is a schematic view of an IV furnace tube.

FIG. 8 is a schematic view of a VI furnace tube.

Detailed Description

The present invention is described in further detail below with reference to the attached drawing figures.

In order to overcome the defects of the 1-1- … … -1 type furnace tube and keep the existing advantages, the invention designs the first pass tube into two, and designs the second pass tube, the third pass tube … … and the Nth pass tube (N is an even number) into one tube respectively. The advantages of increasing the specific surface area of the first pass tube and accelerating the temperature rise speed are achieved; the second pass tube, the third pass tube … … and the Nth pass tube adopt furnace tubes with larger diameters than the first pass tube to reduce the partial pressure of hydrocarbon, reduce resistance drop, reduce coking speed and improve cracking selectivity.

For example, as shown in fig. 1, the present invention provides a radiant furnace tube for a cracking furnace of an ethylene plant, which comprises at least one set of 2: 1: … …: 1: type 1 furnace tube, each group 2: 1: … …: 1: the 1-type furnace tube comprises a first pass tube 1, a second pass tube 2, a third pass tube 3 … … and an Nth pass tube 6, wherein N is an even number, the number of the first pass tubes 1 is two, and the number of the second pass tube 2, the number of the third pass tube 3 … … and the number of the Nth pass tube are respectively one; wherein:

the two first pass pipes 1 are communicated with the second pass pipe 2 through the two-in-one return bend 9, so that the lengths of two straight pipe sections of the first pass pipes 1 are effectively prolonged, the specific surface area is increased, the number of welding seams is effectively reduced, the connection of two rigid castings is avoided, and the risk of stress cracking is reduced;

as shown in fig. 3, the upper end of the two-in-one return bend 9 has two inlets facing upward and an outlet facing upward, and the two inlets and the outlet are in a mutually communicated state inside the two-in-one return bend 9; when in connection, the lower ends of the two first pass pipes 1 are respectively connected with two inlets of the two-in-one return bend 9, and the lower end of the second pass pipe 2 is connected with an outlet of the two-in-one return bend 9; the lower part of the two-in-one return bend 9 is connected with a guide rod 10, and the guide rod 10 is arranged in a guide groove (in the prior art, not shown), so that the extending and creeping directions of the heated furnace tube can be ensured to be downward along the guide groove.

The upper ends of the second pass pipe 2 and the third pass pipe are communicated through an upper 180-degree return bend 5 (shown in figure 4), the lower ends of the third pass pipe and the fourth pass pipe are communicated through a lower 180-degree return bend 7 (shown in figure 5), and the lower ends of the … … (N-1) th pass pipe and the N pass pipe 6 are communicated through a lower 180-degree return bend 7;

of course, as shown in fig. 4 and 5, each upper 180 ° return bend 5 is connected with a pull rod 4 upward, the pull rod 4 is connected with a suspension spring to play a role in suspending the furnace tube and optimizing the stress level of the furnace tube, each lower 180 ° return bend 7 is connected with a guide rod 8 downward, the guide rods 8 can ensure that the furnace tube extends and creeps downward along the guide grooves after being heated, and the pull rods 4 and the guide rods 8 are prior art, and the structure and function thereof are not described herein again.

It is emphasized that the upper 180 ° return bend 5 and the lower 180 ° return bend 7 may be reducer bends, i.e. their inlet diameter may be smaller than the outlet diameter; correspondingly, the inner diameters of the second pass tube 2, the third pass tube 3, … … and the Nth pass tube 6 can be gradually enlarged, and the hydrocarbon partial pressure can be reduced by adopting a furnace tube with a larger inner diameter, so that the cracking selectivity is improved. In a preferred embodiment, the inner diameter of the first pass tube 1 is 40-100 mm, and the inner diameters of the second pass tube 2, the third pass tube 3, … … and the Nth pass tube 6 are 55-130 mm.

The first pass pipe 1, the second pass pipe 2, the third pass pipe 3 … … and the Nth pass pipe 6 are all vertically arranged, are suspended in the hearth and are positioned in the middle of the burners at two sides; and the first pass pipe 1, the second pass pipe 2, the third pass pipe 3 … … and the nth pass pipe 6 are kept on the same plane through the connection of the two-in-one return bend 9, the upper 180-degree return bend 5 and the lower 180-degree return bend 7.

In addition, because the pipe diameters of the N-1 th pass pipe and the N-pass pipe 6 are the largest, the wall temperature is high and coking is easy to occur, and therefore, the enhanced heat transfer element 11 is additionally arranged on the inner walls of the N-1 th pass pipe and the N-pass pipe 6, so that the retention layer can be obviously damaged, heat transfer is improved, the pipe wall temperature is reduced, the coking rate is slowed down, and the operation period of the cracking furnace is further prolonged.

The enhanced heat transfer element 11 is in a water drop shape (in a streamline shape), a triangular pyramid shape or a semi-ellipsoid shape and is discretely arranged on the inner walls of the (N-1) th tube and the (N-1) th tube 6, so that the heat transfer effect of the (N-1) th tube and the (N-1) th tube is enhanced, the formation of a deposit layer on the inner surface of the heat exchange tube is reduced, the wall temperature and the coking rate of the furnace tube are effectively reduced, and the operation period of the cracking furnace is further prolonged. See patent No. ZL201210241368.8 entitled "heat exchange tube with intensified heat transfer element" and patent No. ZL201410056674.3 entitled "process for manufacturing intensified heat transfer element in tube of heat exchange tube with intensified heat transfer element" for details.

The above-described embodiments are merely exemplary of the present invention, and various modifications and variations can be easily made by those skilled in the art based on the application and principle of the present invention disclosed herein, without limiting the invention to the above-described embodiments. The type of furnace tube is not limited to the type listed in each figure, and the radiant section furnace tube can be used for newly building a tube furnace or modifying the tube furnace.