JPH0359091A - Apparatus for pyrolysis of hydrocarbon - Google Patents

Abstract

PURPOSE:To make an apparatus for the pyrolysis of hydrocarbons compact and to improve the thermal efficiency, etc., by making the apparatus into a multi-system and providing a combustion chamber at the center and a reaction chamber around it, and a cooling chamber around the reaction chamber so that the adjacent chambers are placed closely to allow heat exchange. CONSTITUTION:The axes of apparatuses which constitute an apparatus for the pyrolysis of hydrocarbons and have respective functions are approximately aligned and the apparatuses are arranged to form a multi-system. A combustion pipe 2 which supplies reaction heat is provided around the center of the pyrolysis apparatus and a reaction pipe 4 is provided around the pipe 2. A fuel and air are introduced into the combustion pipe 2, the fuel is fired by the action of a combustion catalyst 3, and the produced heat of combustion is supplied to the reaction pipe 4. At the same time, a hydrocarbon raw material is introduced into the reaction pipe 4 to be subjected to pyrolysis reaction. Then, the produced decomposition gas having a high temperature is cooled by a cooling pipe 9 which is provided around the reaction pipe 4 and is removed from a nozzle 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydrocarbon pyrolysis device, and more particularly to a hydrocarbon pyrolysis device with a compact structure and high thermal efficiency.

[Conventional technology]

A hydrocarbon pyrolysis furnace is a pyrolysis device that produces olefinic hydrocarbons such as ethylene and propylene from raw material hydrocarbons such as naphtha and ethane. Here, in FIG. 6, which explains a conventional hydrocarbon pyrolysis apparatus using FIG.
After being preheated to a predetermined temperature, they are mixed, and then heated to the radiant coil 1 by the raw material preheater 17.
It is preheated to an inlet temperature of 8. The raw material preheated by the raw material preheater 17 is introduced into the radiant coil 18, and the area around the radiant coil 18 is heated to a high temperature by the combustion heat of the fuel and air combusted in the radiant box 19, thereby causing a thermal decomposition reaction. A cracked gas reformed into olefinic hydrocarbons containing ethylene, propylene, etc. is produced. Since the generated decomposed gas undergoes further overdecomposition due to heat, the decomposed gas passes through a high-temperature pipe 20 and is cooled by a quencher 21.

The sensible heat held by the high-temperature decomposed gas is exchanged with boiler water in two quenching heat exchangers and recovered as steam.

[Problem to be solved by the invention]

As mentioned above, in the prior art, the following points have not been considered at all, and hydrocarbon thermal decomposition apparatuses tend to be larger, resulting in extremely poor thermal efficiency.

(1) Compact pyrolysis equipment Heating in conventional pyrolysis equipment is performed by a radiant box, and heat transfer to the reaction chamber where hydrocarbons are pyrolyzed is
The heat transfer is mainly done by radiation, and in order to increase the efficiency of this radiation heat transfer, a large radiant box is required. Furthermore, a convection heat transfer section to the raw material preheater and the like is also required, which increases the size of the pyrolysis apparatus.

(2) Improved thermal efficiency Conventional hydrocarbon pyrolysis systems consist of a radiant box, convection heat transfer section (raw material preheater, etc.), high-temperature piping, and a cooling section [quencher]. etc. are installed individually, so heat loss is large.
Therefore, there was a limit to the improvement in thermal efficiency of the pyrolysis apparatus as a whole.

An object of the present invention is to solve the problems in the prior art described above, and to provide an extremely compact structure of a hydrocarbon pyrolysis apparatus.
The object of the present invention is to provide a high-performance hydrocarbon pyrolysis device with high thermal efficiency.

[Means to solve the problem]

In order to achieve the above object of the present invention, in the hydrocarbon pyrolysis apparatus of the present invention, each of the above-mentioned devices is arranged in a multiplex manner, with the vicinity of the central axis of the devices having respective functions being substantially the same. This is a thermal decomposition apparatus for hydrocarbons, which has a heating chamber in its center that supplies reaction heat to a reaction chamber for thermal decomposition, and is placed in close contact with the outer periphery of the heating chamber (allowing heat exchange) to decompose hydrocarbons. A reaction chamber is provided in which the raw materials are introduced and a pyrolysis reaction is carried out, and the reaction chamber is placed in close contact with the outer periphery of the reaction chamber,
The structure is equipped with a cooling chamber that rapidly cools the generated high-temperature decomposed gas.

The specific structure of the hydrocarbon pyrolysis apparatus of the present invention is, for example, provided with a catalytic combustion type heating chamber filled with a combustion catalyst in the center, and a high-temperature combustion gas is disposed along the inner surface of the outer peripheral wall of the heating chamber. A reaction chamber is provided in close proximity to the outer periphery of the combustion gas flow path in which hydrocarbons are thermally decomposed, and the reaction chamber is provided with a partition wall member having a heat insulating effect. A partition wall is provided to separate the gas flow path flowing in the reaction chamber, and the side of the gas flow path formed by the partition wall that contacts the outer circumference of the heating chamber is filled with, for example, naphtha.

It constitutes a gas flow path through which a raw material gas consisting of a mixed gas of a hydrocarbon such as ethane and diluted steam is passed through to carry out a thermal decomposition reaction, and on the other hand, it is in contact with a cooling chamber provided at the outer periphery of the reaction chamber. In the gas flow path formed by the above-mentioned partition wall on the side, high-temperature decomposed gas generated by decomposition into ethylene, propylene, etc. is passed for rapid cooling, and further, in the cooling chamber, boiler water, for example, is stored. This is a hydrocarbon pyrolysis apparatus having a structure in which a steam evaporation chamber is provided.

[Effect]

The hydrocarbon pyrolysis apparatus of the present invention is provided with a heating chamber in the center that supplies reaction heat to the pyrolysis reaction chamber, and the pyrolysis reaction chamber 1 and the cracked gas cooling chamber are each constructed to have a heat exchangeable structure. Since it is a multi-layered pyrolysis device, the equipment required for a conventional hydrocarbon pyrolysis system, such as a raw material preheater, radiant box, radiant coil, and quencher, is integrated. Since high-temperature piping is omitted, the hydrocarbon pyrolysis apparatus of the present invention has an extremely compact structure. and,
A high-temperature heating chamber that supplies pyrolysis reaction heat is placed in the center of the pyrolysis device, and the structure processes lower temperature fluid toward the outer periphery, so heat loss is extremely small and the thermal efficiency of the pyrolysis device is improved. This further improves hydrocarbon pyrolysis equipment with excellent performance.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in more detail based on the drawings.

FIG. 1 is a sectional view showing an example of the structure of a hydrocarbon pyrolysis apparatus according to the present invention.

As shown in the figure, the pyrolysis device exemplified in this example is of a multi-tube type with the same central axis, and a combustion tube 2 is provided in the center, and a combustion catalyst is provided at the upper end. 3 is filled. A reaction tube 4 whose tip is closed is installed on the outer peripheral side of the combustion tube 2. Fuel and air are supplied from the fuel and air inlet nozzle 1 at the bottom of the combustion tube 2, rise and are combusted by the combustion catalyst 3.
After descending between the reaction tube 4 and the combustion tube 2 and imparting heat to the reaction tube 4, the combustion gas is discharged from the apparatus through the combustion gas outlet nozzle 5.

The raw material consisting of hydrocarbons and diluted steam is introduced from the raw material inlet nozzle 6 and rises between the reaction tube 4 and the partition tube 7.
It receives heat from high-temperature combustion gas and causes a decomposition reaction.

A cooling pipe 9 with a closed end is installed outside the partition pipe 7, and the high-temperature decomposed gas descends between the cooling pipe 9 and the reaction tube 4, and is transferred to the boiler stored outside the cooling pipe 9. It is rapidly cooled by water. In addition, a part of the sensible heat is used for preheating the raw material gas.

A cooling pipe 9 is installed outside the reaction tube 4, and can also control the actual raw material preheater of the cracked gas.

The outside of the cooling pipe 9 is a shell 11 that stores boiler water, and steam is generated by sensible heat obtained from the cracked gas through the cooling pipe 9.

Here, the operation of the hydrocarbon thermal decomposition apparatus in this example will be explained in detail.

(1) The fuel and air supplied to the combustion pipe 2 are transferred to the combustion catalyst 3
This results in high-temperature combustion gas.

(2) The high-temperature combustion gas generated in (1) above reverses itself at the tip of the reaction tube 4 and descends inside the reaction tube 4.

A portion of the sensible heat is used to preheat the fuel and air, and the rest is used for raising the temperature of the raw material gas and for decomposition reactions.

(3) The raw material gas rises between the partition tube 7 and the reaction tube 4,
Reaction heat is received from the combustion gas through the reaction tube 4.

The determining factors of the hydrocarbon decomposition reaction are the heat flux and residence time of the reaction tube 4, which can be set by the dimensions of the reaction tube 4 and the partition tube 7.

(4) The decomposed gas that has completed the decomposition reaction descends between the partition pipe 7 and the cooling pipe 9, heat is transferred through the cooling pipe 9, and is rapidly cooled.

If the cracked gas generated after decomposition is kept at high temperature for a long time, the cracked gas will over-decompose, leading to a decrease in the yield of required ethylene, propylene, etc. Therefore, a heat insulating sleeve 8 is installed on the outside of the partition pipe 7. installed to accelerate the rapid cooling of high-temperature cracked gas.

FIG. 2 shows a typical example of the temperature distribution within the pyrolysis apparatus illustrated in this example.

〔Effect of the invention〕

As explained in detail above, the hydrocarbon thermal decomposition apparatus of the present invention has the following excellent effects.

(1) The pyrolysis apparatus of the present invention can have a structure in which the radiant box, radiant coil, raw material preheater, and quencher in the conventional technology are integrated, and the pyrolysis apparatus can be made more compact.

(2) The structure is such that the heating chamber, which supplies the reaction heat to the pyrolysis reaction chamber with the highest temperature, is placed in the center, and the reaction chamber, cooling chamber, and low-temperature equipment are arranged around the periphery, which significantly reduces heat loss. The thermal efficiency of the pyrolysis apparatus can be further improved.

(3) Since the heating chamber and the reaction chamber are in close contact with each other for heat exchange, the response to changes in the load of the pyrolysis apparatus is extremely good.

[Brief explanation of drawings]

1WI is a sectional view showing the structure of the catalytic combustion type hydrocarbon pyrolysis apparatus illustrated in the embodiment of the present invention, FIG. 2 is an explanatory diagram showing the temperature distribution inside the pyrolysis apparatus shown in FIG. FIG. 3 is a schematic diagram showing an example of the structure of a conventional hydrocarbon pyrolysis apparatus. 1... Fuel and air inlet nozzle 2... Combustion pipe 3... Combustion catalyst 4...
Reaction tube 5... Combustion gas outlet nozzle 6... Raw material inlet nozzle 7... Partition tube 8... Heat insulating sleeve 9... Cooling pipe 10... Cracking gas outlet nozzle 11... Shell 12.・Rising tube nozzle 1
3... Downpipe nozzle 14... Insulation material 15...
Raw material preheater (low temperature) 16... Steam preheater 17... Raw material preheater (high temperature) 18... Radiant coil 19... Radiant box 20... High temperature piping 21... Rapid cooling type heat exchanger (Quencher) 22...
steam drum

Claims (1)

[Scope of Claims] 1. A pyrolysis device in which each of the above-mentioned devices is arranged in a multiplexed manner, with the devices having respective functions constituting the hydrocarbon pyrolysis device having substantially the same central axis, the device comprising: A heating chamber is provided in the center of the pyrolysis device to supply reaction heat to a reaction chamber in which hydrocarbons are thermally decomposed, and a hydrocarbon raw material is introduced into the outer periphery of the heating chamber to perform a pyrolysis reaction. A reaction chamber is provided in close contact with the heating chamber to enable heat exchange, and a cooling chamber for rapidly cooling the generated high-temperature cracked gas is provided in close proximity to the reaction chamber to allow heat exchange. 1. A hydrocarbon pyrolysis device characterized by having a structure in which the 2. A pyrolysis device in which each of the above-mentioned devices is arranged in a multiplex manner, with the devices having respective functions constituting the hydrocarbon pyrolysis device having substantially the same center axis, the central part of the pyrolysis device is provided with a catalytic combustion type heating chamber that supplies reaction heat to a reaction chamber for thermally decomposing hydrocarbons, and the heating chamber has a combustion gas passage through which high-temperature combustion gas flows along the inner surface of the outer peripheral wall of the heating chamber. A reaction chamber for thermally decomposing hydrocarbons is provided on the high-temperature combustion gas flow path side in close contact for heat exchange. A partition wall is provided that separates a flowing gas flow path, and the side of the gas flow path formed by the partition wall that contacts the outer periphery of the heating chamber is used as a gas flow path through which a hydrocarbon raw material is flowed to perform a pyrolysis reaction, On the other hand, the gas flow path formed by the partition wall on the side adjacent to the cooling chamber provided at the outer periphery of the reaction chamber is structured to allow rapid cooling by flowing the generated high-temperature decomposition gas. This is a hydrocarbon pyrolysis device. 3. In the hydrocarbon thermal decomposition apparatus according to claim 1 or 2, the cooler for rapidly cooling the cracked gas has a steam generation chamber structured to store boiler water. pyrolysis equipment.