JP3339095B2 - Gas cooler - Google Patents

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 hot gas containing dust such as sticky ash.

[0002]

2. Description of the Related Art As a gas cooler, there are a tube bank type and a shell and tube type in which a high-temperature gas is indirectly brought into contact with a cooling medium to cool it. In order to cool a high-temperature gas (dust-containing high-temperature gas) containing dust such as sticky ash, a tube bank type cooler is used.

For example, IGCC (Integrate Coal Gasif
In the convection cycle, as shown in FIG. 4, the gas is generated in the gasification furnace 25 under high temperature (about 1200 to 1600 ° C.) and high pressure (20 to 40 kg / cm ² ). High temperature (e.g., about 600) via cooler (RSGC) 26
A tube bank type cooler 27 is used to cool the coal gasification gas (.about.1000.degree. C.) to, for example, about 300.degree. Most of the molten ash generated in the gasification furnace 25 is water-cooled and solidified by the radiation cooler 26 and discharged as slag. The ash containing coal gasification gas enters the gas cooler 27 and exchanges heat with the cooling medium passing through the heat transfer tubes.

[0004]

In the tube bank type gas cooler described above, a high-temperature gas flows outside the heat transfer tube, and a cooling medium is supplied into the heat transfer tube. The heat exchange is performed to cool the high-temperature gas, so that the size is increased in order to increase the heat transfer area. Therefore, the weight is heavy and the cost is high. In addition, since the heat exchange part (tube bank) of the heat transfer tube is arranged so as to be orthogonal to the gas flow to improve the heat efficiency, the ash in the gas adheres and accumulates on the outside of the heat transfer tube and sticks (slagging). It's easy to do. For this reason, a suit blow device or the like for blowing off the gas by blowing the gas to all the heat transfer tubes that come into contact with the gas is required.

There is a shell-and-tube type gas cooler, which has the advantage of being smaller than a tube bank type gas cooler. When the high-temperature gas contains dust such as ash in a semi-molten state, the dust has an adhesive property, and the dust is adhered to the tube sheet (tube sheet) for supporting the heat transfer tube. ) Is not suitable for cooling high-temperature dust-containing gas since it sticks and grows when it collides with the heat transfer tube, causing the heat transfer tube to be pinched.

[0006] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a gas cooler capable of reducing the size and preventing slugging due to dust.

[0007]

According to the present invention, in order to achieve the above object, a high-temperature gas containing dust such as sticky ash is introduced into a gas introduction chamber in a container, and the gas is introduced from the gas introduction chamber. in passed through a heat transfer tube gas cooler to replace the cooling medium and the heat supplied to the outside of the heat exchanger tube, the gas guide
The entrance is formed by a water-cooled wall, and a heat transfer tube is
Provide a water-cooled protective plate to cover the sheet
Check the surface temperature of the water cooling wall and defense plate of
Dust sticking prevention temperature that does not stick even if strike strikes
The temperature is maintained at about 500 ° C. or less .

[0008]

The gas cooler can be downsized by using a shell-and-tube type gas cooler. However, if the gas introduction chamber is not a water-cooled wall and a protection plate is not provided , the inner surface temperature of each part of the gas introduction chamber is limited to coal. Rise to near gasification gas temperature,
Dust such as sticky ash adheres and accumulates on the chamber wall of the gas introduction chamber and the surface of the tube sheet. For this reason, the surface temperature of the gas introduction chamber is set to a dust sticking prevention temperature at which the dust does not stick even if dust collides (for example, 400 ° C. to 5 °
Water cooling wall of gas introduction chamber and protection
By controlling the temperature of the plate, even if sticky dust such as ash adheres to the protection plate or the like, it does not adhere. Therefore, the size of the gas cooler can be reduced, and slugging due to dust can be prevented.

[0009]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

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

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

A feature of the present invention is in the gas introduction chamber 6, and in the vicinity of the tube sheet 4 in the gas introduction chamber 6, a disk-shaped protective plate is provided substantially parallel to the surface of the sheet 4 supporting the heat transfer tubes 9. 13 is attached so as to cover the sheet 4, and this protection plate 13 is made of metal (carbon steel, low alloy steel, stainless steel, etc.).
Is formed into a water-cooled structure in which water is supplied to the inside to cool the surface. Further, the protection plate 13 is provided with holes 14 which are appropriately larger than the diameter of the heat transfer tubes 9 at positions on the extension of the heat transfer tubes 9, and one ends of the heat transfer tubes 9 appropriately extend from these holes 14. A water supply port 15 is detachably provided by a screw mechanism or the like at a lower portion of the defense plate 13, and a discharge port 16 is detachably provided by a screw mechanism or the like at an upper portion thereof. Accordingly, the surface temperature of the protection plate 13 is set to a temperature at which the dust is not fixed 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, for example, about 400 ° C to 500 ° C or less. As a result of investigating the relationship between the adhesion of ash and the metal surface temperature at which the high-temperature gas collides, using a high-temperature gas containing several types of coal ash, as shown in FIG. Was fixed, and no dust was fixed on the lower side. For this reason, the surface temperature may be adjusted according to the temperature of the gas or the like. However, here, typically, the temperature is set to about 400 ° C. to 500 ° C. or less, which can sufficiently prevent sticking of dust.

As shown in FIGS. 1 and 2, near the guard plate 13 of the pressure vessel 3, a low-temperature nitrogen gas or the like is supplied to the space between the guard plate 13 and the tube sheet 4 as a coolant. A coolant supply port 17 is detachably provided by a screw mechanism or the like, and low-temperature nitrogen gas or the like supplied to the space is blown out from a space between the hole 14 of the protection plate 13 and the heat transfer tube 9 as appropriate. The hole 14 and the end of the heat transfer tube 9 are set to the temperature for preventing sticking, and are blown away even if dust adheres.

Further, the pressure vessel 3 at the end from the dust protection plate 13 is gradually reduced in diameter so that the end is formed as a high-temperature gas inlet 5, and the wall from the protection plate 13 to the end is a water cooling wall 18. It is formed with. A water supply port 19 is detachably provided at a lower portion of the water cooling wall 18 by a screw mechanism or the like, and a discharge port 20 is detachably provided at the upper portion by a screw mechanism or the like. The temperature of the inner wall surface of the water cooling wall 18 is set to the dust sticking prevention temperature by the water. The gas introduction chamber 9 is defined by the water cooling wall 18 and the protection plate 13, 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, and dust adhered thereto is blown off. It has become. A gas port 22 for gas from a suit blower is also provided on a wall defining 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 a radial cooler at the lower part of the gasification furnace is introduced into a gas introduction chamber 6 in a pressure vessel 3 through an inlet 5 and a heat exchange section. 2 passes through the heat transfer tube 9. At this time, for example, steam at about 200 to 400 ° C. is supplied to the outside of the heat transfer tube 9 of the heat exchange unit 2 from the refrigerant inlet 10, and the steam and the high-temperature gas indirectly exchange heat to generate a high-temperature gas. Cooled to about 300-500 ° C. The cooled gas is discharged from the gas discharge chamber 8 through the discharge port 7, is subjected to dust removal and desulfurization treatment, is purified, and is used as fuel for a gas turbine.

The high-temperature gas cooled by the gas cooler 1 includes:
Includes dust such as sticky ash in a semi-molten state (half-melted state) and the like, but the dust does not adhere to the water cooling walls 18 and 13 forming the gas introduction chamber 6, especially to the protection plate 13. . In other words, the water cooling wall 18 and the protection plate 13 which define the gas introduction chamber 6 have a surface temperature at which the dust is not fixed even if the dust collides (a temperature at which the dust is prevented from sticking (for example, about 400 ° ° C ~ 5
(Less than 00 ° C.)), so that sticky dust such as a semi-molten state in the gas does not adhere even if it collides with the water cooling walls 18 and 13, especially the protection plate 13. This is because, when sticky dust such as a high-temperature semi-molten state collides against the water-cooled walls 18 and 13 having a low temperature, the dust is rapidly cooled and the solid state is changed from the semi-molten state to a completely solid state without tackiness. It is. For this reason, even if the dust collides with the protection plate 13, the dust does not stick or accumulate, thereby preventing dust from sticking or accumulating.

Further, a low-temperature, for example, nitrogen gas 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 supplied to the hole 14 of the protection plate 13.
Is blown out from between the heat transfer tube 9 and the hole 1 of the protection plate 13.
4 and the end of the heat transfer tube 9 are below the dust sticking prevention temperature. As a result, dust does not adhere to the hole 14 of the protection plate 13 and the end of the heat transfer tube 9.

Further, even if dust adheres to the protection plate 13, the gas from the suit blower 23 is blown from the plurality of gas ports 21 onto the surface of the protection plate 13, so that the dust adhered to the surface is blown off. Therefore, 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 pipe 9 without being fixed to the protection plate 13 or the like, and passes through the gas discharge chamber 8 to the discharge port 7. Is discharged from At this time, it is conceivable that sticky dust adheres to the inside of the heat transfer tube 9, but since the heat transfer tube 9 is thin, if the heat transfer tube 9 is cooled by the cooling medium, the inner wall of the heat transfer tube 9 is also always cooled. Therefore, the adhesion of dust in the heat transfer tube 9 is prevented. Accordingly, a shell-and-tube type gas cooler 1 can be used, and the size of the gas cooler that handles high-temperature gas containing dust such as sticky ash in a semi-molten state can be reduced and cost can be reduced. In addition to the reduction, slugging due to dust can be prevented. For this reason, the gas cooler 1 according to the present invention can be widely used in plants that handle gas containing dust.

In this embodiment, the case where one kind of steam is used as the cooling medium has been described. However, when two or more kinds of cooling medium are used, 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]

As described above, according to the present invention, the gas cooler can be reduced in size and the excellent effects of preventing slugging due to dust can be exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one 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 illustrating an example of a coal gasification system.

[Explanation of symbols]

 Reference Signs List 3 pressure vessel 6 gas introduction chamber 9 heat transfer tube 13 defense plate 18 water cooling wall

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F28D 7/16 F28F 9/02

Claims (1)

(57) [Claims] 1. A high-temperature gas containing dust such as sticky ash is introduced into a gas introduction chamber in a container, and the high-temperature gas is passed from the gas introduction chamber through the heat transfer tube to be supplied to the outside of the heat transfer tube. in the gas cooler to medium heat exchanger, the gas guide
The entrance is formed by a water-cooled wall, and a heat transfer tube is
Provide a water-cooled protective plate to cover the sheet
Check the surface temperature of the water cooling wall and defense plate of
Dust sticking prevention temperature that does not stick even if strike strikes
A gas cooler characterized by being maintained at about 500 ° C. or lower .