JPH06273080A - Gas cooler - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to reduce the size of the cooler and prevent slugging due to dust. [Structure] A high-temperature gas containing dust such as sticky ash is introduced into a gas introduction chamber 6 in the pressure vessel 3, and this is passed from the gas introduction chamber 6 through the heat transfer tube 9 to the outside of the heat transfer tube 9. In the gas cooler that exchanges heat with the supplied cooling medium,
The gas introduction chamber 6 is characterized in that it is partitioned by a defense wall (defense plate 13, water cooling wall 18) whose surface temperature is maintained at a temperature at which the dust does not stick even if it collides with the dust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas cooler for cooling high temperature gas containing dust such as sticky ash.

[0002]

2. Description of the Related Art Gas coolers are classified into a tube bank type and a shell and tube type in which a high-temperature gas is indirectly contacted with a cooling medium to cool it. A tube bank type cooler is used for cooling a high temperature gas (dust-containing high temperature gas) containing dust such as sticky ash.

For example, IGCC (Integrate Coal Gasif)
In the ication Convined Cycle), as shown in FIG. 4, it is generated in the gasification furnace 25 under high temperature (about 1200 to 1600 ° C.) and high pressure (20 to 40 kg / cm ² ) and the radiation type under the gasification furnace 25. High temperature (eg about 600) via the cooler (RSGC) 26
A tube bank type cooler 27 is used to cool the coal gasification gas (.about.1000 ° C.) to about 300 to 500 ° C., for example. Most of the ash in the molten state generated in the gasification furnace 25 is water-cooled and solidified by the radial cooler 26 and discharged as slag, but there is ash in a state where it is half-melted without being water-cooled and solidified. The coal gasification gas containing ash in the state enters the gas cooler 27 and exchanges heat with the cooling medium passing through the heat transfer tube.

[0004]

The tube bank type gas cooler described above supplies high temperature gas to the outside of the heat transfer tube and also supplies a cooling medium into the heat transfer tube to supply the high temperature gas and the cooling medium. Since the high temperature gas is cooled by exchanging heat with the above, the size is increased in order to increase the heat transfer area. Therefore, the weight is heavy and the cost is high. Also, because the heat exchange section (tube bank) of the heat transfer tube is arranged so as to be orthogonal to the flow of gas so as to improve the thermal efficiency, ash in the gas adheres and accumulates on the outside of the heat transfer tube and sticks (slugging). It's easy to do. For this reason, a suit blowing device or the like is required to blow the gas onto all the heat transfer tubes that come into contact with the gas to remove the attached dust.

Further, there is a shell-and-tube type gas cooler, and this type of gas cooler has an advantage that it is smaller than the tube bank type, but a high temperature gas is introduced into a gas introduction chamber in a container. If the high temperature gas contains dust such as ash in a semi-molten state in order to guide the heat transfer pipes into the multiple heat transfer tubes, the dust has an adhesive property and this supports the tube sheet (tube sheet). ), Etc., are fixed and grow and cause the heat transfer tube to be clogged, so it is not suitable for cooling high temperature gas containing dust.

The present invention has been made in consideration of such circumstances, and an object thereof is to provide a gas cooler which can be downsized and can prevent slugging due to dust.

[0007]

In order to achieve the above-mentioned object, the present invention introduces a high temperature gas containing dust such as sticky ash into a gas introduction chamber in a container, and introduces the hot gas from the gas introduction chamber. In a gas cooler that exchanges heat with a cooling medium that is supplied to the outside of the heat transfer tube by passing through the heat transfer tube, keep the gas introduction chamber at a dust sticking prevention temperature at which the surface temperature does not stick even if the dust collides. It is a partition wall formed by a defense wall.

[0008]

[Function] A shell-and-tube type gas cooler can be used for miniaturization. However, if the gas introduction chamber is not partitioned by the protective wall, the internal surface temperature of each part of the gas introduction chamber is the temperature of the coal gasification gas. Ascends to the vicinity, and sticky dust such as ash adheres and accumulates on the chamber wall of the gas introduction chamber and the surface of the tube sheet. For this reason, in the gas introduction chamber, the dust sticking prevention temperature at which the dust does not stick even if the surface temperature collides with the dust (depending on the gas temperature etc.
~ 500 ℃ or less) By partitioning with a defense wall, sticky dust such as ash does not stick even if it collides with the defense wall. Therefore, it is possible to reduce the size of the gas cooler and prevent slugging due to dust.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

In the present embodiment, a high temperature (about 600 to 1000 ° C.) coal gasification gas (high temperature gas) containing dust such as ash in a semi-molten state is discharged from a radiant cooler in the lower part of the gasification furnace in the IGCC. The case of cooling to 300 to 500 ° C will be described.

In FIG. 1 and FIG. 2, reference numeral 1 denotes a shell-and-tube type gas cooler.
The structure of the heat exchange section 2 for cooling the high temperature gas is the same as the conventionally known structure. That is, tube sheets (tube plates) 4 are arranged at both ends in the cylindrical pressure vessel 3, and one end side of the vessel 3 is placed in a gas introduction chamber 6 having a high temperature gas inlet 5.
The center is defined by the heat exchange section 2, and the other end side is defined by a gas discharge chamber 8 having a discharge port 7. A plurality of heat transfer tubes 9 that connect the gas introduction chamber 6 and the gas discharge chamber 8 are arranged in the central heat exchange section 2 along the longitudinal direction (axial direction) of the heat transfer section 2. It is supported by the tube sheet 4. The heat exchange section 2 has, for example, about 200
A coolant introduction port 10 for a cooling medium (nitrogen gas, steam, refined coal gasification gas, etc.) at ˜400 ° C. is provided, and a coolant discharge port 11 is provided on the other side. In addition, a plurality of baffle plates 12 are installed in the heat exchanging portion 2 at predetermined intervals so that the cooling medium flows in a zigzag shape in the heat exchanging portion 2. Heat tube 9
The hot gas flowing therein is indirectly exchanged with heat to cool the hot gas to, for example, about 300 to 500 ° C.

The feature of the present invention resides in the gas introducing chamber 6, and in the vicinity of the tube sheet 4 in the gas introducing chamber 6, a disk-shaped protective plate is provided substantially parallel to the surface of the sheet 4 supporting the heat transfer tube 9. 13 is attached so as to cover the sheet 4, and the protection plate 13 is made of metal (carbon steel, low alloy steel, stainless steel, etc.)
It is molded into a water-cooled structure in which water is supplied inside and the surface is cooled. In addition, the protective plate 13 is provided with holes 14 that are appropriately larger than the diameter of the heat transfer tube 9 at positions on the extension of the heat transfer tube 9, and one end of the heat transfer tube 9 is appropriately extended from these holes 14. A water supply port 15 is detachably provided in the lower part of the protection plate 13 by a screw mechanism or the like, and a drain port 16 is detachably provided in the upper part by a screw mechanism or the like. Thus, the surface temperature of the protection plate 13 is set to a temperature at which dust does not stick even if dust such as sticky ash collides (dust sticking prevention temperature). The dust sticking prevention temperature varies depending on the gas temperature and the like, but is preferably about 400 ° C to 500 ° C or less. As a result of investigating the relationship between the ash adhesion and the metal surface temperature at which the high temperature gas collides using high temperature gas containing several kinds of coal ash, as shown in FIG. Is adhered and dust is not adhered on the lower side. Therefore, the surface temperature may be adjusted according to the temperature of the gas or the like, but the temperature is typically set to about 400 ° C. to 500 ° C. or below, which can sufficiently prevent dust from sticking.

In the vicinity of the protection plate 13 of the pressure vessel 3, as shown in FIGS. 1 and 2, low-temperature nitrogen gas or the like is supplied as a coolant into the space between the protection plate 13 and the tube sheet 4. The coolant supply port 17 is detachably provided by a screw mechanism or the like, and the low-temperature nitrogen gas or the like supplied to the space is appropriately blown out from between the hole 14 of the protection plate 13 and the heat transfer tube 9 so that the protection plate 13 is protected. The holes 14 and the ends of the heat transfer tubes 9 are set to a temperature for preventing sticking, and even if dust is attached, they are blown off.

Further, the pressure vessel 3 at the end portion of the dust protection plate 13 is gradually reduced in diameter so that the end portion is formed as a hot gas inlet 5, and the wall from the protection plate 13 to the end portion is a water cooling wall 18. Is formed by. A water supply port 19 is detachably provided at a lower part of the water cooling wall 18 by a screw mechanism or the like, and a drain port 20 is detachably provided at an upper part of the water cooling wall 18 by a screw mechanism or the like. The water causes the temperature of the inner wall surface of the water cooling wall 18 to reach the dust sticking prevention temperature. The water cooling wall 18 and the protection plate 13 define the gas introduction chamber 9, and the water cooling wall 18 and the protection plate 13 form a protection wall.

A plurality of suit blow gas ports 21 are detachably provided on the water cooling wall 18 by a screw mechanism or the like.
A suit blower 23 is connected to these suit blow gas ports 21 via an opening / closing valve 22, and gas from the suit blower 23 is blown onto the surface of the dust protection plate 13 to remove dust adhering thereto. It is like this. Further, a gas port 22 for gas from the suit blower is also provided on the wall that defines the gas discharge chamber 8.

Next, the operation of this embodiment will be described.

High-temperature (about 700 to 900 ° C.) coal gasification gas from the radiant cooler in the lower part of the gasification furnace is introduced from the introduction port 5 into the gas introduction chamber 6 in the pressure vessel 3 and the heat exchange section. It passes through the inside of the heat transfer tube 9 of 2. At this time, for example, steam of about 200 to 400 ° C. is supplied from the refrigerant inlet 10 to the outside of the heat transfer tube 9 of the heat exchange section 2, and the steam and the hot gas indirectly exchange heat to generate the hot gas. It is cooled to about 300-500 ° C. The cooled gas is discharged from the gas discharge chamber 8 through the discharge port 7, dedusted, desulfurized and purified, and then used as fuel for a gas turbine.

The high temperature gas cooled by the gas cooler 1 includes
Dust such as sticky ash in a semi-molten state (a state in which it is almost melted) is included, but the dust does not adhere to the water cooling walls 18 and 13 forming the gas introduction chamber 6, particularly to the protection plate 13. . That is, the water cooling wall 18 and the protection plate 13 that form the gas introduction chamber 6 in a compartment form a temperature at which the dust does not adhere to the surface temperature even if the dust collides (a dust adhesion prevention temperature (depending on the gas temperature, for example, about 400 ℃ ~ 5
Since it is maintained at 00 ° C. or below)), even if sticky dust such as a semi-molten state in gas collides with the water cooling walls 18 and 13, especially the protection plate 13, it does not stick. This is because when the water-cooled walls 18 and 13 having a low temperature collide with sticky dust such as a high temperature semi-molten state, the dust is rapidly cooled and the semi-molten state is changed to a completely solidified state having no tackiness. Is. For this reason, even if the dust collides with the protection plate 13, the dust is not fixed and accumulated, and the dust is prevented from being fixed and accumulated.

Further, low-temperature nitrogen gas, for example, from the coolant supply port 17 is supplied to the space between the protection plate 13 and the tube sheet 4, and this is appropriately provided in the hole 14 of the protection plate 13.
Is blown out between the heat transfer tube 9 and the heat transfer tube 9, and the hole 1 of the protection plate 13
4 and the ends of the heat transfer tubes 9 are below the dust sticking prevention temperature. This prevents dust from sticking to the holes 14 of the protection plate 13 and the ends of the heat transfer tubes 9, etc.

Further, even if dust adheres to the defense plate 13, the gas from the suit blower 23 is blown from the plurality of gas ports 21 onto the surface of the defense plate 13, so that the dust adhered thereto is removed. Therefore, the accumulation of dust can be prevented.

As a result, the dust in the gas introduced into the gas introduction chamber 6 of the gas cooler 1 passes through the heat transfer tube 9 without adhering to the protection plate 13 and the like, and through the gas discharge chamber 8 through the discharge port 7. Emitted from. At this time, sticky dust may adhere to the inside of the heat transfer tube 9. However, since the heat transfer tube 9 is thin, the inner wall of the heat transfer tube 9 is always cooled if the heat transfer tube 9 is cooled by the cooling medium. Therefore, the adhesion of dust in the heat transfer tube 9 is prevented. Therefore, a shell-and-tube type can be used as the gas cooler 1, and the gas cooler that handles high-temperature gas containing dust such as sticky ash in a semi-molten state can be downsized and the cost can be reduced. It is possible to reduce the amount of dust and prevent slugging due to dust. Therefore, the gas cooler 1 according to the present invention can be widely used in a plant that handles gas containing dust.

In this embodiment, one type of steam is used as the cooling medium, but when there are two or more types of cooling medium, the cooler of the present invention is installed in series for each cooling medium. . For example, when there are two types of cooling media, nitrogen gas and steam, a gas cooler using nitrogen gas as a cooling medium and a gas cooler using steam are installed in series.

[0023]

In summary, according to the present invention, the gas cooler can be downsized and the slugging due to dust can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a diagram showing a relationship between a gas temperature and a metal surface temperature.

FIG. 4 is a configuration diagram showing an example of a coal gasification system.

[Explanation of symbols]

 3 pressure vessel 6 gas introduction chamber 9 heat transfer tube 13 protection plate 18 water cooling wall

Claims (1)

[Claims] 1. A cooling system in which a high-temperature gas containing dust such as sticky ash is introduced into a gas introduction chamber in a container, and the hot gas is passed from the gas introduction chamber into the heat transfer tube to be supplied to the outside of the heat transfer tube. In the gas cooler for exchanging heat with a medium, the gas introduction chamber is formed by defining a defense wall whose surface temperature is maintained at a dust sticking prevention temperature at which the dust does not stick even if the dust collides. .