JPS5837934Y2 - Hydrocarbon pyrolysis gas quenching equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a quenching device for quenching pyrolysis gas generated from a hydrocarbon pyrolysis furnace using cooling water.

In the past, devices for rapidly cooling pyrolysis gas have been used or are being developed for the purpose of suppressing the side reactions of high-temperature pyrolysis gas generated by pyrolysis of hydrocarbons in a pyrolysis furnace. be.

Among such devices, there are a quenching device as shown in FIG. 1 and a quenching device as shown in FIG.

This former device has a cylindrical drum d as shown in FIG.
The water supplied through the water supply pipe p flows into the outer pipe O and the inner pipe i fixedly installed at the bottom of the cylindrical drum d as shown by the arrow W, while the water flows into the pyrolysis furnace (not shown). The high-temperature gas passes through the heating pipe, flows into the pipe e disposed in the inner pipe i as shown by the arrow g, rises and flows through the pipe e, and as it flows down,
The water flowing between the outer pipe 0 and the inner pipe i is heated by high-temperature gas, and the water that goes around the lower end of the inner pipe and rises between the inner pipe i and the pipe e is vaporized (the steam is It is supplied to the utilization device from within the cylindrical drum d.

) is configured to give the heat retained in the rising water to cause rapid cooling of the gas.

This device rapidly cools the pyrolysis gas flow in an extremely short time without causing any disturbance, dramatically reducing the amount of carbon deposited, and reducing the number of plant stoppages required to remove it, thereby improving plant operating efficiency. In addition, even if carbon is attached, chemical removal (burning) can be used, making it possible to restart the plant within a short time.
Maintenance cost savings may also be achieved.

This burning-capable quenching device has the advantage that the heat exchanger and the steam drum are integrated, resulting in a simple structure with few components, and a significant reduction in manufacturing costs.

However, due to its structure, it has a high gas side film coefficient, a large heat transfer area, and high pressure steam (approximately 140 kg/cm2G).
The complexity of the recovery container (cylindrical drum d) for the recovery, abnormal vibrations caused by the unbalanced amount of steam generated, and the difficulty of repair due to the complexity of the structure remain technical issues that still need to be resolved. has been done.

In addition, the latter device connects the upper end of each heating tube 2 of the multi-tubular hydrocarbon pyrolysis furnace 1 with a pyrolysis gas introduction tube 3 having a larger diameter and extending vertically upward, and the introduction tube A pyrolysis gas cooling pipe 5 whose lower end is closed and whose upper end is connected to a common outlet header 4 is inserted into the cooling pipe 5, and the lower end is open and a common high-pressure saturated water pipe is inserted into the cooling pipe 5. A coolant inlet pipe 7 connected to the inlet header 6 is inserted, and the coolant is allowed to flow from the inlet header 6 to each coolant inlet pipe 7, each cooling pipe 5, and the outlet header 4, while flowing from the heating pipe 2 to the outlet header 4. The pyrolysis gas is caused to flow upward along the outside of the cooling pipe 5 in the pyrolysis gas introduction pipe 3 to cool the pyrolysis gas.

Incidentally, a gas recovery pipe 11 for recovering the pyrolysis gas is connected to the upper end of the pyrolysis gas introduction pipe 3.

Further, a common steam/water separation drum 8 was connected to the outlet header 4 and the inlet header 6 through communication pipes 9 and 10 in order to circulate the cooling medium.

However, this device has the following problems.

(1) High pressure saturated water inlet header 6 and outlet header 4;
Since the air-water separation drum 8 is formed separately, a rising pipe 9 and a descending pipe 10, which are communicating pipes, are inevitably required, and since these pipes are high-temperature and high-pressure pipes, they have poor heat resistance and pressure resistance. It requires pipes made of rich and expensive material, which increases the equipment cost of the entire quenching device, making it difficult to put it into practical use.
This has become one obstacle.

(2) The high-pressure saturated water flowing into the heat exchanger from the steam/water separation drum 8 via the downcomer pipe 10 is required to be equally distributed.

However, in order to distribute the water uniformly in a straight line, it is necessary to take measures such as dividing the high-pressure saturated water inlet header 6 into quite a number of suitable lengths and providing a downcomer pipe 10 in each of them. Downcomer pipe 1 between 8 and high pressure saturated water inlet header 6
0 Piping becomes more complex and its quantity increases.

(3) From the results of (1) and (2) above, the downcomer 10
In order to ensure an appropriate amount of water circulation, a larger height head is required between the steam/water separation drum 8 and the evaporator (heat exchanger). Quantity increases.

Moreover, if the above-mentioned phenomenon is viewed from the pyrolysis furnace 1 side, it becomes an essential condition that the quenching device is installed in the upper part of the pyrolysis furnace due to the structure of the pyrolysis furnace.

In this case, the need for heavy equipment to be located at a higher location requires increased strength of the pyrolysis furnace itself.

(4) High-pressure saturated water outlet/inlet headers 4 and 6 of double pipe structure with small diameter pipes have problems during maintenance such as internal inspection and repair, and during manufacturing, and these problems will be resolved. If it is made larger for this purpose, it will be the same as providing two air/water drums 8, which will pose a problem in terms of economy.

(5) In addition, there is a possibility that abnormal vibrations and abnormal corrosion may occur in the ascending pipe 9 and the descending pipe 10 from time to time.

Therefore, the present invention was devised to solve the above-mentioned problems, and its purpose is to provide a hydrocarbon cracked gas quenching device that can be made more compact, have improved durability, and reduce costs.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

In FIG. 3, reference numeral 1 denotes a hydrocarbon pyrolysis furnace having a large number of heating tubes 2 arranged in a straight line in the vertical direction, and a common gas supply pipe 1a is connected to the lower ends of these heating tubes 2.
The hydrocarbons supplied from this are heated while rising into the heating tube 2 to generate high-temperature pyrolysis gas.

A pyrolysis gas quenching device 12 for rapidly cooling the high-temperature pyrolysis gas sent from the heating tube 2 is provided in the upper part of the pyrolysis furnace 1.

This pyrolysis gas quenching device 12 is provided with a heat exchanger (suspension type pionet type heat exchanger) 13 for each of the heating tubes 2, which cools the pyrolysis gas by exchanging heat with cooling water.

That is, the heat exchanger 13, as shown in FIGS. 4 and 5,
In order to move upwardly the hydrocarbon gas generated from the pyrolysis furnace 1 and transfer it, a cracked gas transfer pipe 130 is connected to the upper end of the heating tube 2, and a cracked gas transfer pipe 130 is provided inside the cracked gas transfer pipe 130. An inner pipe 13i inserted to transfer cooling water from the downstream side of the transfer gas to the upstream side, and the cooling water transferred from this inner pipe 13i are turned back from the downstream end 13a and directed in the flow direction of the gas. and the inner tube 13 i
The cracked gas transfer pipe 13a and the inner pipe 13 are used to transfer the gas along the outer circumferential side of the pipe and to substantially flow the gas to the outside thereof.
13m of heat transfer outer tubes provided between

Specifically, the outer heat transfer tube 13m is a cylindrical tube with an open upper end and a closed lower end, and in the annular space formed between the inner tube 13i and the cracked gas transfer tube 130, the The inner tube 13i is supported from the downstream end 13a side.

Further, the downstream end, that is, the upper end of the cracked gas transfer pipe 130 is joined to the heat transfer outer pipe 13m and is closed, and there is a gap between the heat transfer outer pipe 13m and the cracked gas transfer pipe 130 at the upper end. Gas recovery pipe 11 communicating with the formed gas passage 13g
is connected.

Therefore, the heat exchanger 13 has an inner tube 13 inside the heat transfer outer tube 13m.
It is configured to exchange heat between the cooling water flowing through the cooling water passage 13S formed by i and the high temperature pyrolysis gas flowing through the gas passage 13g formed outside the heat transfer outer tube 13m.

Through such heat exchange, the downstream end 13a of the inner pipe 13i
The cooling water that turns back and rises along the inner circumferential wall of the outer heat transfer tube 13m is heated to boiling and vaporized, while the pyrolysis gas is rapidly cooled.

The heat exchangers 13 configured in this manner are arranged in a straight line so as to coincide with the axes of the respective heating tubes 2, and the respective heat transfer outer tubes are disposed above the heat exchangers 13. A horizontal cylindrical air-water drum 16 having a 13 m long outlet (outlet of the cooling water passage 13S) in common communication is integrally connected.

Inside the air-water drum 16, a semi-cylindrical cooling water supply tank 14a with a smaller diameter is provided with a required gap 19 between these peripheral walls, and cooling water is supplied to this supply tank 14a from the outside. A water supply pipe 14 for introducing water is led through the air/water drum 16 in a liquid-tight manner and is connected for communication.

The supply tank 14a supplies cooling water to the inner pipe 13i, and the inner pipe 13 of the heat exchanger 13 is provided at the bottom of the supply tank 14a.
The upstream ends of the cooling water inlet 17 (referred to as the cooling water inlet 17) are commonly and integrally connected to each other.

The inner circumferential wall of the supply tank 14a and the supply tank 14
As described above, a gap 19 is provided between the inner peripheral wall of the air-water drum 16 provided to cover the air-water drum 16, so that the vaporized cooling water after heat exchange is transferred to the supply tank 1.
A passage 18 is defined at the upper exit side of the passage 18 leading to the top of the cooling water tank 14a.
A steam separator 20 is provided for separating steam and water from each other to a steam outlet 25 formed at the top of the steam pipe 6.

As shown in FIGS. 4 and 6, the steam/water separator 20 generates a swirling flow between a steam port 21 connected to the outlet of the passage 18 and the vaporized cooling water introduced from the steam port 21. a swirling flow path 22 that allows the steam to flow, and a drain outlet 23 that allows water (drain) swirled by the swirling flow path 22 and centrifuged from the steam to be introduced into the supply tank 14a; It is comprised of a steam exhaust port 24 that discharges steam upward into the steam drum 16.

That is, the steam/water separator 20 consists of a hollow box shaped like an elephant's head, with a steam port 21 in the part corresponding to the neck, a drain outlet 23 in the part corresponding to the nose, and a drain outlet 23 in the part corresponding to the eyes. A steam exhaust port 24 is formed in each portion.

A plurality of steam/water separators 20 having such a configuration are provided at the outlet of the passage 18 at appropriate intervals in the longitudinal direction (the interval necessary for discharging steam from the steam exhaust ports 24 on both sides). (See FIG. 3), the outlet of the passage 18 between adjacent steam/water separators 20 is closed.

An area above the supply tank 14 a in the steam drum 16 is formed as a recovery section 15 that recovers the steam discharged from the steam outlet 24 of the steam separator 20 . After the steam is released, it is taken out from the yarn through the steam outlet 25.

Incidentally, in the vicinity of the steam outlet 25 in the recovery section 15, there is a thermal mister (not shown) made of a baffle plate such as a corrugated plate.
A gas-solid separator is provided to further separate and remove water by causing the steam heading toward the steam outlet 25 to collide with the baffle plate.

The steam from which water has been sufficiently removed in this way is passed through the steam outlet 25.
The strands are led out of the strands and used in utilization devices such as turbine power generation.

The air-water drum 16 constructed as described above is supported and fixed above the pyrolysis furnace 1 by a frame or the like, so that the heat exchanger group 13 is suspended and supported from one air-water drum 16.

Next, the operation of the above embodiment will be described.

As shown in FIG. 5, the cooling water in the supply tank 14a is
As shown, it flows down into the inner tube 13i, goes around the lower end (downstream end) of the inner tube 13i, and rises along the inner side of the outer heat transfer tube 13m.

During this rising, the cooling water is heated by the high-temperature pyrolysis gas sent from the heating tube 2 and flowing upward along the outside of the outer heat transfer tube 13m, and is boiled and vaporized.

This steam (cooling water after heat exchange) enters the steam-water separator 20 from the outlet of the cooling water passage 13S through the passage 18 as indicated by arrow S.

The amount of heat held by the high-temperature pyrolysis gas is used to vaporize the cooling water, and the temperature of the gas rapidly decreases.

In other words, rapid cooling of the gas occurs. The pyrolysis gas rapidly cooled in this way is led out of the system through the gas recovery pipe 11.

On the other hand, the steam that has entered the steam separator 20 is centrifuged to remove moisture, and then passes through the steam outlet 24 to the steam drum 1.
The steam is collected in the recovery section 15 in the steam collector 6, and is led out of the system through the steam outlet 25 while further removing moisture with a steam resistor.

On the other hand, the water removed by the steam separator 20 is returned to the supply tank 14a through the drain outlet 23 and is recycled.

Note that water, which is a cooling fluid, is supplied into the supply tank 14a through a water supply pipe 14 in order to keep the stored water constant.

As described above, according to the present invention, the rapid cooling of gas can be performed within an extremely short time without causing any disturbance in the gas flow, so that the amount of carbon adhering to the gas flow path, especially the heat transfer outer tube 13m, can be minimized. can be made to

Also, in the present invention, like the quenching device shown in FIG. 2, the structure is such that even if a difference in thermal expansion occurs during burning by flowing high-temperature gas through the gas flow path, it can be absorbed.

Specifically speaking, the downstream end 13a of the inner tube 131 is a free end, while the outer heat transfer tube 13m and the cracked gas transfer tube 130 are configured to freely extend downward. Carbon burning treatment (chemical removal of carbon) can be performed, and therefore the plant can be restarted within a short period of time, helping to reduce maintenance costs.

Furthermore, the heat exchanger 13 and the air-water drum 16 are not constructed separately, but are integrated with fewer components and a simpler structure than in the case of separate constructions.

Therefore, the manufacturing cost can be significantly reduced.

Furthermore, compared to the conventional system shown in Fig. 1, which integrates the heat exchange section forming the U-shaped flow path and the air/water drum, the amount of heat transfer section attached to the air/water drum can be reduced. In addition, since the number of pipes can be halved, the structure of the parts with heat transfer parts that must withstand high-pressure steam can be simplified.

Furthermore, by passing the high-temperature pyrolysis gas through the gas flow path, that is, the outer surface of the heat transfer outer tube, at an optimal mass velocity, a high gas-side film coefficient can be obtained, and the diameter of the heat transfer outer tube can be reduced to 13 m. The large scales can improve heat transfer performance.

In other words, it is possible to improve the quenching performance of high-temperature pyrolysis gas, and from this, it is also possible to reduce the amount of carbon deposited.

Further, from the above, it is possible to reduce the heat exchange area in the heat exchanger 13, and to make the heat exchanger more compact.

Furthermore, the connection structure between the air-water drum and the heat exchanger is relatively simple and compact, which greatly contributes to reducing the cost of the device.

Such a simple structure has practical effects such as facilitating repair of the device when an abnormality occurs.

In summary, the present invention exhibits the following excellent effects.

(1) The structure is simple and the device can be made compact.

(2) It is also possible to improve durability.

(3) Cost reduction can be achieved by reducing the quantity of materials.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of a known pyrolysis gas quenching device, respectively, FIG. 3 is an explanatory diagram of the entire structure of the device showing a preferred embodiment of the present invention, and FIG. 4 is a summary of the main components of FIG. 3. Sectional longitudinal sectional view, 5th
The figure is a partially enlarged sectional view of FIG. 4, and FIG. 6 is an enlarged perspective view of the steam/water separator. In the figure, 1 is a pyrolysis furnace, 12 is a pyrolysis gas quenching device, and 13
i is an inner pipe, 13m is an outer heat transfer pipe, 130 is a cracked gas transfer pipe, 14a is a cooling water supply tank, 16 is an air-water drum, 20
2 is a steam separator, and 25 is a steam outlet.

Claims (1)

[Scope of utility model registration request] In an apparatus for rapidly cooling hydrocarbon pyrolysis gas with cooling water, there is provided a cracked gas transfer pipe for moving the hydrocarbon pyrolysis gas generated from the pyrolysis furnace upwardly and transferring the cracked gas, and An inner pipe for transferring cooling water from the downstream side to the upstream side of the transfer gas, and an inner pipe for turning the cooling water transferred from the inner pipe from its downstream end in the flow direction of the gas and along the outer circumferential side of the inner pipe. a cooling water supply tank integrally connected to the upstream end of the inner pipe for supplying cooling water thereto; integrally connected to the outlet side of the pipe,
an air/water drum covering the supply tank; a passageway defined by an inner wall of the air/water drum and an outer wall of the supply tank; and a heat exchanger provided on the outlet side of the passageway to transfer heat through the passageway. quenching of hydrocarbon pyrolysis gas, characterized in that it is equipped with a steam separator for separating the moisture of the vaporized cooling water into the supply tank and the steam component from the steam outlet of the steam drum. Device.