JPWO2013015088A1 - Tower boiler - Google Patents

Abstract

The tower boiler (1) includes a furnace wall (3) that forms a boiler body (2) and exchanges heat with combustion gas (G) generated in the boiler body (2), and a boiler body (2). The heat transfer part which heat-exchanges with the combustion gas (G) produced in a boiler main body (2) located in the upper part of is provided. The heat transfer section includes a plurality of superheaters (6-8), and the heat transfer tubes in the superheaters (6, 7) located at least on the furnace wall lower part (3a) side among these superheaters (6-8). Is set to be larger than the adjacent pitch (Pn) of the heat transfer tubes (11) in the superheater (8) located on the side away from the furnace wall lower part (3a).

Description

The present invention relates to a tower boiler.
This application claims priority based on Japanese Patent Application No. 2011-160529 for which it applied to Japan on July 22, 2011, and uses the content here.

A tower boiler is a boiler suitable for being installed in a limited space. For example, there is a tower boiler disclosed in Patent Document 1.
This tower boiler performs heat exchange between a boiler body, a burner that injects and burns fuel into the boiler body, and a combustion gas that is generated by injecting and burning fuel from the burner into the boiler body. And a heat transfer section. And the superheater which comprises a heat-transfer part, the resuperheater, and the economizer is arrange | positioned in the upper part of the furnace wall which makes a box shape, and size reduction of the size of boiler (the exclusive area of a boiler) is aimed at.

A heat transfer section, for example, a superheater, includes long heat transfer tubes that are bundled by reciprocating multiple times, and if the adjacent pitch of the heat transfer tubes in the bundled state (interval between adjacent heat transfer tubes) is large, the superheater The volume of increases. Since the size of the superheater directly affects the size of the boiler, in the conventional tower boiler, superheaters (heat transfer portions) having a narrowest adjacent pitch as much as possible are arranged.

Thus, when the superheater with a narrow adjacent pitch is arranged, high heat transfer efficiency can be obtained, and the size of the boiler can be reduced. However, when the combustion gas containing ash is introduced into a superheater with a narrow adjacent pitch, if the temperature of the combustion gas exceeds the melting point of ash, the ash adheres to the heat transfer tube and is adjacent to the heat transfer tube. As the pitch is narrow, the flow of combustion gas stagnate, and effective heat exchange cannot be performed.

In such a conventional tower boiler, in order to avoid clogging of ash between the adjacent heat transfer tubes of the superheater, the heat transfer surface to the superheater closest to the bottom of the furnace wall (the furnace wall tube in the vertical direction) The temperature of the combustion gas introduced into the superheater does not exceed the melting point of ash by increasing the area of the many furnace walls and absorbing a corresponding amount of heat.

JP 09-243004 A

When the tower boiler disclosed in Patent Document 1 described above is a tower boiler capable of generating steam under high steam conditions (high temperature and high pressure conditions) for the purpose of improving plant efficiency, the amount of fuel input is increased by improving plant efficiency. However, the flow rate of steam supplied from the tower boiler to the turbine is further reduced. That is, since the feed water flow rate is reduced, as a result, the temperature of water or steam flowing in the furnace wall tube is higher than that of a tower boiler under conventional steam conditions. Moreover, the heat recovery amount by a feed water heater may be increased for the purpose of further improving plant efficiency. In this case, the temperature of the feed water introduced into the boiler is increased, and the temperature of water or steam flowing in the furnace wall pipe is further increased.

On the other hand, even in a high steam steam tower boiler, as described above, the temperature of the combustion gas introduced into the superheater closest to the bottom of the furnace wall must be lowered below the melting point of ash. Therefore, the area of the heat transfer surface below the furnace wall cannot be reduced, and the temperature of water or steam flowing in the furnace wall tube cannot be lowered.
That is, the water flowing in the furnace wall pipe of the furnace wall rises toward the drum or separator installed at the upper part of the boiler body in a state of being hot water or steam on the furnace wall. The temperature becomes high and the material becomes unbearable.

At this time, even if an attempt is made to use a material that can withstand high-temperature steam, for example, a 7CrMOVTiB10-10 material called T24, as the furnace wall in the upper part of the boiler body, it is difficult to form the furnace wall with the current welding technique. . Therefore, there is a demand for a technique for preventing the steam temperature in the pipe at the upper part of the furnace wall from becoming high during operation under high steam conditions.

The present invention has been made paying attention to the above-described conventional problems, and can generate steam under high steam conditions aimed at improving plant efficiency without using a material that can withstand high-temperature steam on the furnace wall. The purpose is to provide a tower boiler that can be used.

A first aspect according to the present invention includes a furnace wall that forms a boiler body and exchanges heat with combustion gas generated in the boiler body, and is located in an upper portion of the boiler body and is disposed in the boiler body. In a tower boiler having a heat transfer section that exchanges heat with the generated combustion gas, the heat transfer section includes a plurality of superheaters, and is located at least on the furnace wall lower side of the plurality of superheaters. The adjacent pitch of the heat transfer tubes in the superheater is set wider than the adjacent pitch of the heat transfer tubes in the superheater located on the side away from the furnace wall lower part.

According to a second aspect of the present invention, in the tower boiler according to the first aspect described above, each adjacent pitch of the heat transfer tubes in the plurality of superheaters is set for each superheater as the distance from the furnace wall lower part increases. It is narrowed sequentially.

According to a third aspect of the present invention, in the tower boiler according to the first or second aspect, the adjacent pitch of the heat transfer tubes in the plurality of superheaters is the superheater with the narrowest adjacent pitch of the heat transfer tubes. By the time the combustion gas is introduced, the temperature of the combustion gas is set to be equal to or lower than the melting point of the ash contained in the combustion gas.

In the tower boiler according to the present invention, the temperature of the combustion gas is reduced to the melting point of the ash until the combustion gas containing ash is introduced into the superheater having a narrow adjacent pitch of the heat transfer tubes located on the side away from the furnace wall lower part. It needs to be lowered below. For this reason, the superheater located closest to the bottom of the furnace wall, that is, the superheater with a wide adjacent pitch of the heat transfer tubes, also serves as a heat transfer surface that lowers the temperature of the combustion gas. Therefore, the amount of heat absorbed by the furnace wall in which a large number of furnace wall tubes in the lower part of the furnace wall are arranged in the vertical direction is relatively reduced, and the in-pipe steam temperature at the upper part of the furnace wall can be kept low.

At this time, if the adjacent pitches of the heat transfer tubes in the plurality of superheaters are gradually narrowed for each superheater as they move away from the lower part of the furnace wall, in each superheater, blockage by ash is prevented and the boiler size is reduced. Efficient heat exchange is possible while avoiding an increase in size.

In the tower boiler according to the present invention, a combustion gas having a gas temperature exceeding the melting point of ash is introduced into the superheater located closest to the furnace wall lower side. Therefore, if the adjacent pitch of the heat transfer tubes in this superheater is set narrow, there is a concern about blockage of the superheater due to ash adhering to the heat transfer tubes. On the other hand, if the adjacent pitch of the heat transfer tubes in the superheater is set wide, the necessity of increasing the boiler size arises.

Therefore, the adjacent pitch of the heat transfer tubes in the superheater located closest to the furnace wall lower side is set to a value that can prevent blockage by ash and avoid an increase in boiler size. For example, when the combustion gas of about 1600 ° C. generated by the combustion is lowered to about 1200 ° C. or less, which is the melting point of ash, before being introduced into the superheater located on the side away from the lower part of the furnace wall, It is desirable to set the adjacent pitch of 1000 to 2000 mm. Under the present circumstances, the adjacent pitch of the heat exchanger tube in the superheater located in the side away from the furnace wall lower part becomes about 600-700 mm in general.

In the tower boiler according to the present invention, the above-described configuration improves the plant efficiency without using a material that can withstand high-temperature steam for the furnace wall, that is, without changing the material of the furnace wall that is currently employed. It is possible to operate under the target high steam conditions.

It is the schematic from the side which shows one Embodiment of the tower boiler which concerns on this invention. It is the schematic from the side which shows other embodiment of the tower boiler which concerns on this invention.

Hereinafter, the tower boiler concerning the present invention is explained based on a drawing.
FIG. 1 shows an embodiment of a tower boiler according to the present invention.
As shown in FIG. 1, the tower boiler 1 includes a furnace wall 3 that forms a boiler body 2, a burner 4 that injects fuel into the boiler body 2, and burns from the burner 4 into the boiler body 2. A heat transfer section that exchanges heat with the combustion gas G generated by injecting and burning the fuel. Heat exchange with the combustion gas G is also performed by the furnace wall lower part 3 a and the furnace wall upper part 3 b located at the lower part and the upper part of the boiler body 2. The heat transfer section is disposed in the upper flow path 10 surrounded by the furnace wall upper portion 3b of the boiler body 2, and the heat transfer section includes a plurality of superheaters 5 to 8, a reheater 9, and a charcoal saving (not shown). With a bowl.

In the tower boiler 1, the combustion gas G is supplied to the heat transfer section in the upper flow path 10, that is, the superheaters 7, 6, 8, the reheater 9, the superheater 5, and the economizer to heat the combustion gas G. After exchanging and flowing the combustion gas G after this heat exchange to a flue gas treatment device such as a denitration catalyst and a desulfurization device (not shown) arranged further downstream, components such as sulfur compounds and nitrogen compounds are removed, Release into the atmosphere.

Among the plurality of superheaters 5 to 8, the superheater 7 that is located closest to the furnace wall lower part 3 a and is exposed to the flame F, and each heat transfer tube 11 that constitutes the superheater 6 that is located downstream of the superheater 7 are It is bundled by reciprocating several times. Furthermore, as shown in the enlarged portion of FIG. 1, the adjacent pitch Pw of the heat transfer tubes 11 constituting these superheaters 6 and 7 is the heat transfer constituting the superheater 8 located on the side away from the furnace wall lower portion 3a. It is set wider than the pitch Pn of the heat tubes 11.

As described above, in the tower boiler 1 according to this embodiment, the combustion gas G is introduced into the superheater 8 positioned on the side away from the furnace wall lower portion 3a, that is, the superheater 8 having a narrow adjacent pitch Pn of the heat transfer tubes 11. By the time, it is necessary to lower the temperature of the combustion gas G below the melting point of ash. Therefore, the superheater 7 that is located closest to the furnace wall lower part 3a and is exposed to the flame F and the superheater 6 adjacent thereto, that is, the superheaters 6 and 7 that widen the adjacent pitch Pw of the heat transfer tubes 11 are combusted. It also serves as a heat transfer surface that lowers the temperature of the gas G.

Therefore, the amount of heat absorbed by the furnace wall lower part 3a in which a large number of furnace wall pipes (not shown) are arranged in the vertical direction is reduced, and the steam temperature in the furnace wall upper part 3b of the boiler body 2 is kept low.

Thus, in the tower boiler 1 according to this embodiment, even if the amount of heat input to the boiler body 2 is increased, the steam temperature in the furnace wall pipe in the furnace wall upper portion 3b of the boiler body 2 can be kept low. Therefore, a material that can withstand high-temperature steam, for example, a 7CrMOVTiB10-10 material called T24 is used for the furnace wall upper portion 3b, that is, a furnace wall material that is currently employed, for example, a 13CrMO4-5 material called T12 is used. It can be used to operate under high steam conditions aimed at improving plant efficiency.

FIG. 2 shows another embodiment of the tower boiler according to the present invention.
As shown in FIG. 2, the tower boiler 21 according to this embodiment is different from the tower boiler 1 according to the previous embodiment in that it is located in the vicinity of the furnace wall lower part 3 a in the plurality of superheaters 5 to 8. As the adjacent pitches Pw, Pm, and Pn of the heat transfer tubes 11 from the superheater 7 to the superheater 8 positioned farthest away from the furnace wall lower portion 3a as shown in the enlarged portion of FIG. The other configurations are the same as those of the tower boiler 1 according to the previous embodiment.

As described above, the adjacent pitches Pw, Pm, and Pn of the heat transfer tubes 11 from the superheater 7 layered closest to the furnace wall lower part 3a to the superheater 8 located farthest away from the furnace wall lower part 3a. If it is made to narrow sequentially with this, in each superheater 7,6,8, after blocking | blocking by ash and avoiding enlargement of a boiler size, efficient heat exchange will be achieved.

The configuration of the tower boiler according to the present invention is not limited to the configuration of the tower boiler according to the above-described embodiment. As another configuration, for example, the adjacent pitch of the heat transfer tubes 11 may be changed in the superheater 6 adjacent to the superheater 7 layered most in the vicinity of the furnace wall lower part 3a. Further, the adjacent pitches Pw, Pm, Pn of the heat transfer tubes 11 from the superheater 7 layered closest to the furnace wall lower part 3a to the superheater 8 located farthest are gradually increased as the distance from the furnace wall lower part 3a increases. You may change so that it may narrow.

  This tower boiler can be operated under high steam conditions with the aim of improving plant efficiency without changing the currently used furnace wall material.

1,21 tower boiler, 2 boiler body, 3 furnace wall, 3a lower furnace wall, 3b upper furnace wall, 5-8 superheater (heat transfer part), 9 reheater (heat transfer part), 11 heat transfer tube, G combustion Gas, Pn Adjacent pitch of heat transfer tubes in the superheater away from the furnace wall lower part, Pw Adjacent pitch of heat transfer tubes in the superheater near the lower furnace wall, Pm Superheater away from the lower furnace wall and superheater near the lower furnace wall Adjacent pitch of heat transfer tube in superheater

Claims (3)

A furnace wall that forms a boiler body and exchanges heat with the combustion gas generated in the boiler body;
In a tower boiler provided with a heat transfer part that performs heat exchange with the combustion gas generated in the boiler body located at the upper part of the boiler body,
The heat transfer section includes a plurality of superheaters;
Of the plurality of superheaters, at least the adjacent pitch of the heat transfer tubes in the superheater located on the lower side of the furnace wall is set wider than the adjacent pitch of the heat transfer tubes in the superheater located on the side farther from the lower side of the furnace wall. Tower boiler. The tower boiler according to claim 1, wherein each adjacent pitch of the heat transfer tubes in the plurality of superheaters is successively narrowed for each superheater as the distance from the lower part of the furnace wall increases. As for each adjacent pitch of the heat transfer tubes in the plurality of superheaters, until the combustion gas is introduced into the superheater having the narrowest adjacent pitch of the heat transfer tubes, the temperature of the combustion gas melts the ash contained in the combustion gas. The tower boiler according to claim 1 or 2 set up to become below a point.

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