JPH0431242Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a quencher device for a pyrolysis furnace for rapidly cooling a substance thermally decomposed in a pyrolysis furnace to freeze the reaction and recover sensible heat. In particular, the present invention relates to a two-stage quencher device whose structure can be simplified.

[Conventional technology]

When producing olefin fractions such as ethylene by thermally decomposing hydrocarbon raw materials, especially liquid raw materials such as naphtha and gas oil, a two-stage quencher is sometimes used for the purpose of rapidly cooling the cracked gas and recovering sensible heat. many. This two-stage quencher device has conventionally been constructed as shown in FIGS. 2, 3, and 4. In Fig. 2, the pyrolysis furnace 1 includes a burner 2.
A furnace 3 is provided, and a plurality of reaction tubes 4 pass through the furnace 3. The upper parts of these reaction tubes 4 are formed in the shape of a coil 6 in the convection section 5 at the upper part of the furnace 3, and the hydrocarbon raw material is preheated through the coil 6 and undergoes a thermal decomposition reaction in the reaction tube 4. cause. After these reaction tubes 4 exit the pyrolysis furnace 1, they are connected to a plurality of 1
It is connected to the next quencher 8. In other words, for each reaction tube 4, one
primary quenchers 8 are connected. The number of these reaction tubes 4 is usually 4 to 8, and may be 16 to 32 in some cases. The cracked gas, which has been cooled to a predetermined temperature in the primary quencher 8 and the thermal decomposition reaction has been frozen, is collected in the outlet header 9 and then passed through the intermediate HTL 10 to the secondary quencher 11.
sent to. Both the primary quencher 8 and the secondary quencher 11 recover high-pressure steam in return for cooling the cracked gas, and collect the steam together with the steam drum 16 via riser pipes 12 and 13 and downcomer pipes 14 and 15, respectively. It forms a natural circulation boiler system. 17 is a pipe for discharging thermally decomposed gas.

The primary quencher 8, as shown in FIG.
It has a double tube structure of an outer tube 18 and an inner tube 19, and a water chamber 20 is formed by an annular flow path surrounded by these inner and outer tubes 18 and 19. The inlet portion 21 and outlet portion 22 of the inner pipe 19 are connected to the HTL 7 and the outlet header 9, respectively.
Further, downcomer nozzles 2 are provided at both ends of the outer pipe 18.
3 and a riser nozzle 24 are provided, connected to said downcomer pipe 14 and riser pipe 12, respectively. Reference numeral 25 denotes a sleeve that connects the inner tube 19 and the outer tube 18 in isolation at the inlet portion 21 . As shown in FIG. 4, the secondary quencher 11 is a multi-tubular shell-tube type in which a plurality of tubes 27 are provided between both end faces of a closed cylindrical shell 26 and passing through the shell. It is a heat exchanger. An inlet channel 29 and an outlet channel 30 are connected to both end faces of the shell 26 and have inner and outer walls that are open toward the outside and are filled with a heat insulating material 28 between them. After cooling through tube 27, it is discharged through outlet channel 30. The openings of these inlet channels 29 and outlet channels 30 are each HTL10.
and connected to piping 17. Also Ciel 26
is provided with a riser pipe nozzle 31 which is an outlet of the cooling water and a downpipe nozzle 32 which is an inlet of the cooling water.
It is connected to the.

[Problem that the invention attempts to solve]

The conventional two-stage quencher device described above has excellent reaction freezing performance, which minimizes side reactions of thermally decomposed cracked gas, but the quencher device is separated into primary and secondary quenchers. Therefore, there was a problem that the device became complicated. Also, the temperature of the cracked gas on the outlet side of the primary quencher 8 is approximately 600℃.
Since the temperature is in the high temperature range of 700°C to 700°C, all the constituent members must be made of heat-resistant materials and are expensive. Furthermore, since the thermal expansion is relatively large, a relatively complicated piping system must be formed in order to absorb this thermal stress, and a correspondingly large number of members are required. Another drawback was that a relatively large number of bends and vents had to be used to provide flexibility to absorb thermal stress in a confined space. An even bigger problem is the pressure loss of the cracked gas, which is the fluid inside the pipes, which occurs due to the complex piping system consisting of a large number of curved pipes. As shown in FIG. 5, the cracked gas is cooled between the inlet A and outlet B of the primary quencher 8 and between the inlet C and outlet D of the secondary quencher 11, but the intermediate pipe between B and C It is not cooled in the section. Nevertheless, as shown in Fig. 6, the pressure loss △P ₂ between this intermediate piping section B and C
is large, and when the pressure losses of the primary quencher 8 and the secondary quencher 11 are respectively △P ₁ and △P ₃ , the total pressure loss △P=△P ₁ +△P ₂ +△
It reaches almost half of P ₃ . Secondary quencher 11
Since the pressure at the outlet of the cracking furnace reaction tube 4 is constant, the pressure at the outlet of the cracking furnace reaction tube 4 must be increased as the pressure loss ΔP of the quencher system increases. Furthermore, since the decomposition reaction is a gas volume increase reaction, there was also the problem that the higher the pressure, the lower the reaction performance.

For example, in Japanese Patent Application Laid-Open No. 56-93792, there are several
An example of a two-stage quencher is shown in which the secondary quencher is directly coupled to the secondary quencher via a gathering member, eliminating the aforementioned intermediate HTL 10. but,
Even in the case of a two-stage quencher as shown, 1
A gathering member had to be placed between the secondary quenchers, and pressure loss could not be avoided there.

The present invention was developed in view of the above circumstances, and is a pyrolysis furnace that has a simple structure that can improve the reaction freezing performance without impairing the function of the two-stage quencher, and that can reduce equipment costs. The purpose of the present invention is to provide a quencher device for use.

[Means for Solving the Problems] In order to achieve the above-mentioned purpose, the present invention aims to provide a quencher device for a pyrolysis furnace for reaction freezing of pyrolyzed substances and recovery of sensible heat, in which cooling water flows in and out. a substantially cylindrical shell having a nozzle and having both axial end faces sealed; an outlet channel connected to one axial end face of the shell to form an outlet chamber having the end face as one wall; an inlet channel that is connected to the other axial end face of the shell and forms an inlet chamber with the end face as one wall surface; between a primary cooling pipe that is opened and the other end is opened outside the outlet channel, and an outer circumferential surface of the primary cooling pipe that is fitted concentrically to a portion of the primary cooling pipe inside the shell; cooling water guide means forming a cooling water flow path in the shell; several sub-tubes disposed axially within the shell and communicating the outlet chamber and the inlet chamber to form a secondary cooling pipe; an outlet connection that is provided to communicate the outlet chamber with the outside of the outlet channel, and an inner surface of a shell of a nozzle through which cooling water flows into the shell, for guiding a flow of incoming cooling water in a direction toward the outlet channel. The primary cooling pipe is connected to the outlet channel through a heat insulating material at a portion passing through the outlet channel.

[Effect]

According to the above configuration, the pyrolyzed material is discharged from the outlet connection through the primary cooling pipe, the inlet chamber, the plurality of tubes forming the secondary cooling pipe, and the outlet chamber, while the cooling water flows through the shell. Cooled by. Therefore, the conventional primary and secondary quenchers are integrated, simplifying the structure, and
Since HTL is omitted, pressure loss due to pipe resistance is reduced.

〔Example〕

Hereinafter, one embodiment of a quencher device for a pyrolysis furnace according to the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In this figure, parts that are the same or equivalent to those of the conventional example shown in FIGS. 2 to 4 are designated by the same reference numerals, and their explanation will be omitted. The secondary quencher 11 has almost the same structure as the conventional example shown in FIG.
The main feature is that a primary cooling pipe 33 is provided on the central axis of the cooling pipe. This primary cooling pipe 33 is fixedly installed through a tube plate 34 and an outlet channel 30 provided on both end faces of the shell 26, and one end opens into the inlet chamber formed by the inlet channel 26. The other end is open outside the outlet channel 30. The end of this inlet channel 29 is sealed with a plate flange 35. Near the other end of the primary cooling pipe 33 is attached to the outlet channel 30 via a flexible thermal sleeve 36 and a flange 37, and there is a gap between the primary cooling pipe 33 and the thermal sleeve 36. A heat insulating material 28 is filled. 38 is a flange attached to the open end of the primary cooling pipe 33 outside the outlet channel 30. Further, a guide plate 39 as a guide means is provided at a position facing the downcomer pipe nozzle 32 in the shell 26, and a guide pipe 40 as a cooling water guide means is provided on the outer periphery of the primary cooling pipe 33. There is. and flange 38 as shown in FIG.
HTL 7 is connected to the outlet channel 30 via an outlet connection 41 to the piping 1 shown in FIG.
7 is connected. Further, a rising pipe 13 and a downcomer pipe 15 are connected to the rising pipe nozzle 31 and the downcomer pipe nozzle 32, respectively.

Next, the operation of this embodiment will be explained. The cracked gas thermally decomposed in the pyrolysis furnace 1 reaches the flange 38 on the inlet side via the HTL 7 and is introduced into the primary cooling pipe 33. Although the inlet of the primary cooling pipe 33 has a high temperature of decomposed gas of 800° C. to 850° C., it is insulated from the outside by the thermal sleeve 36. The cracked gas introduced into the primary cooling pipe 33 passes through the shell 26, exchanges heat with the boiler water in the steam drum 16, is cooled, and is discharged into the inlet chamber formed by the inlet channel 29. . This cracked gas makes a U-turn inside the inlet chamber, and
The water is then introduced into a plurality of tubes 27 forming cooling pipes, exchanges heat with boiler water in the shell 26, and is discharged into an outlet chamber formed by an outlet channel 30. Then, it is sent to the next process through the exit connection 41. Boiler water for heat exchange is supplied to precipitation nozzle 32
It is introduced into the shell 26 from above, and is evenly distributed in the circumferential direction of the shell 26 and in the tube plate portion 34 by the guide plate 39. The guide pipe 40 has the effect of ensuring circulation of boiler water on the outer peripheral surface of the primary cooling pipe 33.
The heat-exchanged boiler water passes through the riser pipe 13 via the riser nozzle 31 and is introduced into the steam drum 16.

According to this embodiment, while maintaining the same function and effect as the primary quencher 8, the primary cooling pipe 33 is placed inside the multi-tube shell-tube heat exchanger that is the conventional secondary quencher 11. , primary and secondary quencher purposes can be handled by one heat exchanger. Also, the traditional intermediate HTL10
Since this is not necessary, it is possible to reduce the pressure loss △P ₂ that occurs in this part, which has been a problem in the past, and the structure is simplified, reducing equipment costs. In this case, the same number of secondary quenchers as the primary quenchers are required compared to the conventional case, but by integrating them with the primary quenchers, the overall cost can be reduced. Furthermore, the period for cleaning carbon adhering to the quencher can be lengthened, and the operating efficiency can be improved. Further, even when cleaning the attached coke by removing the gas inlet/outlet flange and spraying high-pressure water, the cleaning can be done easily since there are few decomposed parts.

Further, according to the embodiment, the primary cooling pipe is built into the secondary quencher, so the overall height can be reduced.

Although the above-mentioned embodiment describes a quencher device installed in an ethylene thermal cracking furnace, the present invention is not limited to use in an ethylene cracking furnace, and can be applied to other systems that require rapid cooling for freezing reactions. Even when applied, similar effects and effects can be obtained.

[Effect of idea]

As described above, according to the present invention, the primary quencher is integrally provided concentrically within the secondary quencher,
By eliminating the intermediate connecting pipe, equipment costs can be reduced with a simple structure without increasing the height of the equipment, and the pressure loss in the pipe is reduced, improving the reaction performance of the cracking furnace. can be improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a quencher device for a pyrolysis furnace according to the present invention, and FIG. 2 is a flow diagram showing the configuration of a conventional quencher device for a pyrolysis furnace.
Figures 3 and 4 are the 1st and 2nd order of Figure 2, respectively.
A vertical cross-sectional view showing the next quencher, and FIGS. 5 and 6 are diagrams showing temperature and pressure changes in the conventional device. 1...Pyrolysis furnace, 26...Ciel, 27...2
Next cooling pipe (tube), 29...Inlet channel,
30...Outlet channel, 31...Rising pipe nozzle, 32...Downcomer pipe nozzle, 33...Primary cooling pipe, 34...Tube plate, 41...Outlet connection.

Claims (1)

[Scope of Claim for Utility Model Registration] A quencher device for a pyrolysis furnace for reaction freezing of pyrolyzed substances and recovery of sensible heat, which is equipped with a nozzle through which cooling water enters and exits, and has both end faces in the axial direction sealed. a cylindrical shell; an outlet channel connected to one axial end face of the shell forming an outlet chamber having the end face as one wall; an inlet channel forming an inlet chamber with a wall surface; and an inlet channel disposed through both axial end surfaces of the shell and the outlet channel, with one end opening in the inlet chamber and the other end opening outside the outlet channel. a cooling water guide means that is fitted concentrically into a portion of the primary cooling pipe inside the shell and forms a cooling water flow path between the primary cooling pipe and the outer circumferential surface of the primary cooling pipe; a plurality of tubes disposed in the shell in the axial direction and communicating the outlet chamber and the inlet chamber to constitute a secondary cooling pipe; and a plurality of tubes provided in the outlet channel to communicate the outlet chamber with the outside of the outlet channel. an outlet connection, and a guide means on the inner surface side of the shell of the nozzle through which cooling water flows into the shell, for guiding the flow of the cooling water in the direction toward the exit channel, and the primary cooling pipe is A quencher device for a pyrolysis furnace, characterized in that a portion passing through the outlet channel is connected to the outlet channel via a heat insulating material.