JPS6017972B2 - steam superheating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam superheating furnace for superheating steam generated in a chemical plant or the like, in which a steam generator of a system different from the steam generator is incorporated in the same furnace.

FIG. 1 is a diagram showing an ethylene plant having a conventional steam superheater.

In this apparatus, when a raw material 2 is supplied to a cracking furnace 1, the raw material 2 is subjected to high-temperature pyrolysis in the cracking furnace 1. This decomposed product gas is led to the quenching heat exchanger 3, quenched, and sent to the next refining section. Water is used as a coolant in this quenching heat exchanger 3, and this water exchanges heat with the generated gas and evaporates. This steam 5 is taken out to the outside via the drum 4. Incidentally, since a large ethylene plant is usually composed of a large number of identically shaped cracking furnaces, the steams 6 and 7 are extracted through the same process as described above. These steams 5 to 7 are combined, guided to a steam superheater 18, and superheated in an independent steam superheater 9 to a temperature necessary to operate a steam turbine for driving a combustor, and become superheated steam 10.
In some cases, an independent steam superheater 9 for performing this steam superheating is installed in the convection section of each cracking furnace 1. The combustion gas leaving the cracking furnace 1 passes through the bonito pipe 11, is mixed with the combustion gases 12 and 13 from other furnaces, is denitrated by the gas purifier 14, and is then sent to the chimney 16 by the induced draft fan 15. be guided. Recently, in the above-mentioned plants, a steam generator has been installed in the steam superheating furnace 8 from the viewpoint of common use of pollution treatment equipment attached to the combustion furnace and pursuit of economic efficiency of the entire plant by reducing the number of furnaces. It is being incorporated. FIG. 2 is a diagram showing a steam superheating furnace incorporating a secondary steam generator.

In this steam superheating furnace 17, a steam generator 22 is installed in the bonito path 20 behind the independent steam superheater 18 in order to recover waste heat of combustion heat from the burner 21, and steam is taken out from the drum 23. . Note that steam 19 sent from the plant is superheated to a predetermined temperature in an independent steam superheater 18 and becomes superheated steam 10. However, there is a limit to the amount of steam that can be recovered in this steam superheating furnace. Therefore, if you want to actively obtain a considerable amount of steam in addition to recovering waste heat, increase the firing height of the burner 21 shown in FIG.
As shown in the figure, it is conceivable to provide a burner 24 at an appropriate position in front of the steam generator 22 to create fire. However, in the former case, the gas temperature in the steam superheating furnace i7 becomes high, so in order not to shorten the life of the furnace, it is necessary to The expensive heat-resistant material on the side needs to be made even higher grade. On the other hand, in the latter case, the larger the amount of steam required, the larger the burner 24 becomes, making operation and maintenance more complicated. It is necessary to install a bonito path 201, a burner 24, a steam generator 22, etc., and an induced draft fan 25 to exhaust the combustion gas. Even if it is connected to a common flue from multiple cracking furnaces, it will inevitably increase the equipment cost and the installation area.
As described above, there have been various problems in steam superheating furnaces incorporating secondary steam generators. This invention was made to solve the above problems, and has a simple structure.
The purpose of the present invention is to provide a steam superheating furnace that has a small facility area and can obtain a considerable amount of steam that can be used for other purposes.

In order to achieve this purpose, the present invention includes a frame body,
A plurality of support beams horizontally fixed to the frame, a convection flue whose lower part is fixed to at least a portion of the support beams, and whose lower end protrudes downward from the support beam, and the convection flue. an independent steam superheater built into the interior of the vessel, and a steam system provided between the support beam and the foundation, the upper part of which is suspended from at least a portion of the support beam, and a furnace formed by a steam pipe. A generator and a portable cover plate disposed between a lower portion of the convection flue and an upper portion of the steam generator.

Also, a frame body, a support beam horizontally fixed to the frame body,
A convection flue whose lower part is fixed to the support beam and whose lower end protrudes below the support beam, an independent steam superheater built into the inside of the convection flue, a steam generator whose lower part is supported by a bottom support and whose furnace arm is formed by an evaporation tube; and the lower part of the convection flue and the upper part of the steam generator. FIG. 4 is a diagram showing a steam superheating furnace according to the present invention.

In the figure, 26 is a frame, 27 is a plurality of support beams horizontally fixed to the frame 26, and 28 is a steam generator whose upper part is suspended from the support beams 27 by hanging bolts 29.
The steam generator 28' is provided between the support beam 27 and the base part 52, and the furnace wall is formed by the steam generator 28'. 30 is a combustion furnace formed by the steam generator 28'; 31 is an upper header of the steam generator 28; 32 is a lower header of the steam generator 28; 33 is a drum;
2 and the drum 33 are connected by a rising pipe 34 and a downcomer pipe 35.

Further, 36 is a heat insulating material attached to the outside of the steam generator 28, 37 is a burner installed in the steam generator 28, 38 is a forced draft fan for combustion air, and 39 is a burner 37 and a forced draft fan 38. In the connecting air duct, the combustion air brought in by the forced draft fan 38 is sent via the air duct 39 to the burner 37 . The oil or gas fuel is suitably blended with the combustion air and combusted in the burner 37. In addition, the convection flue is fixed at the lower part to the support beam 27 and whose lower end protrudes downward from the support beam 27, and is located at the outlet of the combustion furnace 30, and has a furnace structure made of brick or castable. There is. 41 is an independent steam superheater, which is incorporated inside the convection pipe 40.

Further, the independent steam superheater 41 is normally constructed of heat exchanger tubes having a relatively large diameter in order to keep the allowable pressure drop of the steam inside the tubes small, but the choice can be made freely.
42 and 43 are an inlet header and an outlet header of the independent steam superheater 41, and the steam 19 sent from the plant passes through the inlet header 42, is superheated to a predetermined temperature in the independent steam superheater 41, and is then transferred to the outlet header 43. leading to.

In addition, 44 and 45 are waste heat recovery parts provided from the viewpoint of waste heat recovery, and various uses of the waste heat recovery parts 44 and 45 can be considered, but the most appropriate use may be selected. The combustion gas whose heat has been recovered in a flue 46 is led to a chimney or a common flue through a bonito pipe 46.

In this way, the steam generator 28 and the independent steam superheater 41 are structurally separated. Further, 47 is a movable cover plate whose both ends are fixed to the upper part of the steam generator 28 and the lower part of the convection flue 40, and the cover plate 47 is for preventing combustion gas and air from leaking. It is. Note that the inside of the combustion furnace 30 is kept under negative pressure to prevent combustion gas from leaking to the outside. In this manner, since the burner 37 is installed in the steam generator 28 in this furnace, a considerable amount of steam for other purposes can be obtained regardless of the capacity of the independent steam superheater 41.

Furthermore, in response to thermal expansion, the steam generator 28 is suspended from the support beam 27 and can freely deform downward, and the convection flue 40 has its lower part fixed to the support beam 27 and can freely deform upward. Is possible. In addition, since the support beam 27 near the center of the furnace is used as the base point for vertical thermal expansion, the amount of thermal expansion of the entire furnace is apparently small, and the steam generator 28
The structure of the joint between the convection flue 40 and the convection flue 40 is simple and stable, making it easy to prevent combustion gas or air from leaking. Furthermore, since the steam generator 28 and the convection flue 40 are connected by the flexible cover plate 47, their structures are not restricted to each other, and the structure is simple. Since the superheater 41 and the steam generator 28 are arranged one above the other and are vertically rigid, the chimney effect can be utilized to the maximum and the installation area is small.
Furthermore, since the steam generator 28 and the convection flue 40 are structurally separated, the maximum evaporation amount of the steam generator 28 and the capacity of the independent steam superheater 41 can be freely determined. Note that when the independent steam superheater 41 is mainly operated, the operating range of the independent steam superheater 41 can be freely changed by adjusting the combustion amount of the burner 37. Moreover, FIG. 5 is a diagram showing another steam superheating furnace according to the present invention.

In this steam superheating furnace, the steam generator 28 is not suspended by hanging bolts, but the lower part of the steam generator 28 is supported by a bottom support 51. As explained above, the steam superheating furnace according to the present invention includes an independent steam superheater,
In addition to being structurally separated from the steam generator for other purposes, the structure is simple, the installation area is small, and a considerable amount of steam can be obtained.

As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

Figure 1 shows an ethylene plant with a conventional steam superheating furnace, Figures 2 and 3 show steam superheating furnaces incorporating a conventional steam generator, and Figures 4 and 5 respectively. FIG. 1 is a diagram showing a steam superheating furnace incorporating a steam generator according to the present invention. Explanation of symbols: 1... Cracking furnace, 2... Raw material, 3... Quenching heat exchanger, 4, 23, 33...
Drum, 5-7, 19... Steam, 8, 17...
...Steam superheating furnace, 9,18,41...Independent steam superheater, 10...Superheated steam, 21,24,37
...Burner, 22,28...Steam generator,
26... Frame body, 27... Support beam, 29
... Hanging bolt, 30 ... Combustion furnace, 4
0... Convection flue, 47... Covering plate.
Figure l Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1 A frame body, a plurality of support beams horizontally fixed to the frame body, and a lower part of which is fixed to at least a part of the support beams, and a lower end of which protrudes downward from the support beams. a convection flue;
An independent steam superheater built into the convection flue is provided between the support beam and the foundation, the upper part is suspended from at least a portion of the support beam, and the evaporation tube is connected to the furnace wall. 1. A steam superheating furnace comprising: a steam generator having a structure formed therein; and a flexible covering plate provided between a lower part of the convection flue and an upper part of the steam generator. 2 A frame, a support beam horizontally fixed to the frame, a convection flue whose lower part is fixed to the support beam and whose lower end protrudes below the support beam, and the convection flue. an independent steam superheater built into the interior, a steam generator provided between the support beam and the foundation part, the lower part of which is supported by a bottom support, and whose furnace wall is formed by an evaporation tube, and the convection part. A steam superheating furnace comprising a flexible cover plate provided between a lower part of the flue and an upper part of the steam generator.