JP2014202441A - Protector against screen for fluid bed type boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a heat medium (a) such as sand from entering into a space between upper and lower water pipe protector members.SOLUTION: This invention relates to a fluid bed type boiler B in which sand (a) is circulated between a combustion chamber 1 and a heat recovery chamber 2 through spaces of each of water pipes 4 of a screen 3 and heat is recovered by the water pipes 4. A cylindrical protector 10 covering an entire circumference of each water pipe 4 to protect it is constituted of two half members 11 and 12 divided at a plane on the cylindrical protector axis. The upper and lower protector members 11 and 12 are arranged such that a lower edge flange 16 of the upper protector member 11 overlaps on the upper end surface of the lower protector member 11. Since a space between the upper and lower protector members 11 and 12 is covered by the flange, the sand (a) and items to be ignited or the like are effectively prohibited from entering into the space. The protector member at the combustion chamber 1 is made as a long plate member, the protector at the heat recovery chamber is made as a long item having an arcuate cross section and both protector members cover the entire circumference of the water pipe through fittings of both side edges.

Description

  The present invention relates to a screen protector for a fluidized bed boiler that burns wood chips, municipal waste, industrial waste, coal and other combustion products in a fluidized bed and recovers the thermal energy.

This type of fluidized bed boiler is provided with, for example, a screen in which a plurality of water pipes whose vertical directions are in the pipe axis direction are arranged between a combustion chamber and a heat recovery chamber, and sand or the like is interposed between the water pipes of the screen. The heat medium is circulated between the combustion chamber and the heat recovery chamber, and heat recovery is performed by the heat recovery chamber and the water pipe (see Patent Document 1, Claims, FIG. 6).
The water pipes constituting the screen are juxtaposed with a required gap. The surface of the water pipe is exposed to the heat medium in the combustion chamber and the heat recovery chamber, and the heat medium moves from the combustion chamber to the heat recovery chamber through the gap. For this reason, the entire circumference of each water pipe is covered with a protector to prevent the water pipe from being worn or corroded (see Patent Document 1, FIG. 2, FIG. 3).

Japanese Patent Publication No. 5-87758 Japanese Utility Model Publication No. 1-101008

The conventional protector consists of members divided in the vertical direction of the water pipe, and the divided members are stacked in the pipe axis direction. For this reason, the upper and lower end surfaces of the divided members adjacent to each other are in contact with each other, and a heat medium such as sand or a foreign matter such as a combusted material enters the contact interface.
On the other hand, the protector is constantly heated from the combustion chamber and the heat recovery chamber, and the degree of heating also changes, so that the thermal contraction and thermal expansion are repeated. However, the water pipe covered with the protector is less likely to thermally expand than the protector. For this reason, if the protector repeats thermal expansion and contraction, a heat medium (sand) or the like may enter the gap between the protector and the water pipe that spreads due to the difference in thermal expansion, and a large amount of the heat medium may accumulate and damage the protector. The entry of the heat medium or the like mainly occurs in a gap generated at the interface between the upper and lower divided members constituting the protector.

  This invention makes it a subject to prevent the penetration | invasion of the heat medium etc. to the interface of the upper and lower division members which comprise a protector under the above actual condition.

In order to achieve the above object, the present invention provides a flange at the lower end of the upper member of the upper and lower divided protector members, covers the upper end surface of the lower divided member by the flange, and provides a heat medium to the interface, etc. It was decided to prevent intrusion.
In this way, if the upper end of the lower divided protector member is covered with the upper divided protector member, entry of a heat medium or the like into the interface between the upper and lower divided protector members is prevented. At this time, since the lower split protector member upper end is covered with the upper split protector member lower end 侵入, the intrusion into the interface of the upper and lower adjacent split protector members such as the heat medium enters from the lower side, and the entrance is In addition, even if it enters from the lower side of the cage, it cannot enter the interface unless it gets over the upper end of the lower divided protector member, so that the penetration of the heat medium or the like between the upper and lower divided protector members is effectively prevented. The

  As a configuration of the present invention, a screen is provided between a combustion chamber and a heat recovery chamber, in which a plurality of water pipes whose vertical direction is in the tube axis direction are arranged in parallel, and the heat medium is passed between the water pipes of the screen through the combustion chamber. In a cylindrical protector that covers and protects the entire circumference of the water pipe, the fluidized bed boiler that is circulated between the heat recovery chamber and the heat recovery chamber consists of two halves divided by a plane in the pipe axis direction, One side is composed of a plurality of combustion chamber side protector members stacked in the vertical direction to protect the combustion chamber side of the water pipe, and the other side is a plurality of heat recovery chamber sides stacked in the vertical direction to protect the heat recovery chamber side of the water pipe The at least one set of combustion chamber side protector members that are formed of protector members and are adjacent to each other in the upper and lower sides can be configured such that the ridges facing the lower side of the lower edge of the upper protector member overlap the upper surface of the lower protector member.

In this configuration, the set of combustion chamber side protector members that are adjacent to each other to provide the soot may be selected as appropriate by grasping a protector member into which a heat medium or the like is likely to enter by experiment or actual operation, etc. It is preferable to provide between combustion chamber side protector members.
Further, the combustion chamber side protector member and the heat recovery chamber side protector member are overlapped in the length direction to form a cylinder, but the interface in the length direction of the cylinder may be simply abutted, It can be set as the fitting structure by. As the fitting structure, for example, the combustion chamber side protector member is a long plate, the heat recovery chamber side protector member is a long object having a circular cross section, and both end portions of the heat recovery chamber side protector are combusted. It is possible to employ a structure that covers the entire circumference of the water pipe by fitting the two protector members into the groove on the back surface of the room side protector member.

  In these, at least one pair of the heat recovery chamber side protector members that are adjacent to each other in the upper and lower sides is provided with a ridge directed downward on the lower edge of the upper protector member, and the ridge overlaps the upper surface of the lower protector member. be able to. Also at this time, the set of protector side protector members that are adjacent to each other in the upper and lower sides, which are provided with a ridge, can be selected appropriately by grasping the protector member that is likely to enter a heat medium or the like through experiments or actual operations. It is preferable to provide between the heat recovery chamber side protector members which adjoin the upper and lower sides.

Patent Document 2 discloses a technique in which the side ends of the divided protector members are overlapped in the protector of the water pipe (evaporating pipe) of the fluidized bed boiler, and the gap between the upper and lower divided protector members is covered with a pressing member. (Refer to the same literature 2, the specification, page 5, lines 15 to 18, first, third, and sixth figures).
However, in the fluidized bed boiler according to the present invention, the heat medium passes between the water pipes of the screen composed of a plurality of water pipes and circulates between the combustion chamber and the heat recovery chamber. In the technique described in Document 2, the heat medium does not circulate between the combustion chamber and the heat recovery chamber.
For this reason, intrusion prevention of the heat medium or the like into the gap of the divided protector member in the technique described in Patent Document 2 is for completely constructing a partition wall (a wall that prevents an object from passing through). On the other hand, in the fluidized bed boiler of the invention according to the present application, a heat medium or the like is originally passed between each water pipe (protector), and a gap between each protector is allowed. In such a fluidized bed boiler, the invention according to the present application recognizes and prevents the damage of the protector due to a heat medium or the like that has entered between the upper and lower protector members (interface) due to the thermal expansion and contraction of the protector. For this reason, the space between the upper and lower protector members (interface) is closed. That is, the prevention of the penetration of the heat medium or the like into the gap of the divided protector member of the present invention and the prevention of the penetration of the heat medium or the like into the gap of the divided protector member of Patent Document 2 are different.

  Since the present invention is configured as described above and prevents the heat medium and the like from entering between the upper and lower protector members, the protector due to the difference in thermal expansion between the heat medium and the protector member that has entered between the protector members. Damage to the member can be prevented.

Sectional drawing of the principal part of one Embodiment of the fluidized bed boiler which concerns on this invention Front view partially omitted of the screen of the same embodiment The protector member of the same embodiment is shown, (a) is an exploded perspective view, (b) is a cut plan view in a fitted state. The other protector member of the embodiment is shown, (a) is an exploded perspective view, (b) is a cut plan view of the fitted state The other protector member of the embodiment is shown, (a) is an exploded perspective view, (b) is a rear perspective view of the combustion chamber side protector member, (c) is a cut plan view in a fitted state.

  1 to 5 show an embodiment of the present invention, and this embodiment relates to an internal circulating fluidized bed boiler B in a biomass power generation facility using wood chips as a main raw material. Like the fluidized bed boiler described in Patent Document 1, this fluidized bed boiler B is provided with a screen 3 in which a plurality of water tubes 4 whose vertical direction is the tube axis direction are arranged in parallel between the combustion chamber 1 and the heat recovery chamber 2, Sand a, which is a heat medium, circulates between the combustion chamber 1 and the heat recovery chamber 2 through the water pipes 4 of the screen 3, and is heated by a heat exchange pipe (not shown) in the heat recovery chamber 2. While recovering heat, each water pipe 4 also recovers heat. A protector 10 is provided in each water pipe 4 of the screen 3 as in the prior art.

As shown in FIGS. 1 and 2, the protector 10 is composed of upper and lower four-stage combustion chamber side protector members 11 ₁ , 11 ₂ , 11 ₃ , 11 ₄ (generic symbol: 11) and the same five-stage heat recovery chamber side. It consists of protector members 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ (generic symbol: 12). The number of the protector members 11, 12 (the number of divisions of the protector 10) and the length of the protector member 11 in the vertical direction are appropriately determined according to the length and shape of the water pipe 4.

  As shown in FIGS. 3 to 5, the combustion chamber side protector member 11 is a long plate-like object, and has L-shaped hook portions 13 on both side edges thereof, while the heat recovery chamber side protector member 12 is It is an elongate object having a circular cross-section and has projecting pieces (locking pieces) 14 extending laterally on both edges. For this reason, by inserting the water pipe 4 between the protector members 11 and 12 and inserting and engaging the locking piece 14 into the groove 13 ′ in the hook portion 13 from the length direction of the water pipe 4 with respect to the other. The combustion chamber side protector member 11 and the heat recovery chamber side protector member 12 are fitted to cover the water pipe 4 in a cylindrical shape.

Since the uppermost protector members 11 ₄ and 12 ₅ have obstacles on the upper side, they cannot be fitted in the vertical direction. For this reason, as shown in FIG. 5, a cut 15 is formed at a required interval in the length direction of the hook portion 13 and the locking piece 14, and a locking piece 15 a is formed between the cuts 15. and fitted with a locking piece 15a both protecting member ₁₁ 4, 12 ₅ after repeated, moving the protecting member 11 ₄ or 12 ₅ of the upper to the lower, both protecting member ₁₁ 4, 12 ₅ its locking piece 15a , 15a are overlapped and locked to cover the water pipe 4 in a cylindrical shape (see FIGS. 5B and 5C). At this time, the upper portion of the combustion chamber-side protecting member 11 ₄ heating medium a and the like at its upper end projects from the upper end of the heat recovery chamber side protecting member 12 ₅ is prevented reach as much as possible (see Figure 1).

Furthermore, as shown in FIGS. 4 and 5, the lower end of each protector member 11 ₂ , 11 ₃ , 11 ₄ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ except for the lowermost protector member 11 ₁ , 12 _1. On the outside, a ridge 16 swells like a bay and faces downward is provided. For this reason, when each protector member 11 and 12 is put on the water pipe 4, the upper end of the lower protector member 11 or 12 adjacent to the flange 16 is covered, and the gap between the protector members 11 and 12 adjacent above and below ( Cover). For this reason, the penetration | invasion of the sand a, a to-be-burned material, etc. to this clearance gap is blocked | prevented effectively. The length in the vertical direction and the arcuate width of the flange 16 are appropriately determined by experiments or the like so that the heat medium a or the like enters between the adjacent upper and lower protector members 11 and 12 and the protector members 11 and 12 are not damaged. Set.
In this embodiment, the side surface of the flange 16 and the side surface 11a of the protector member 11 are flush with each other (see FIG. 4), and the gap between the water pipes 4 (protector 10) is secured to hinder circulation of the heat medium a. There is no such thing.

In this embodiment, the protector member 12 on the heat recovery chamber side is also provided with the ridge 16, but sand a etc. moves from the combustion chamber 1 to the heat recovery chamber 2 side as indicated by the arrow in FIG. Sand a or the like hardly enters between the side protector members 12. For this reason, it is also possible not to provide the flange 16 between the protector members 12 on the heat recovery chamber side. Further, the protector members 11 ₁ , 12 ₁ ... (11, 12) other than the uppermost protector members 11 ₄ , 12 ₅ can also be fitted by locking the notch 15 and the locking piece 15a.
Incidentally, it goes without saying that the present invention can be applied to a fluidized bed boiler other than the biomass power generation facility.

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Heat recovery chamber 3 Screen 4 Water pipe 10 which comprises a screen Water tube protector 11, 11 ₁ , 11 ₂ , 11 ₃ , 11 ₄ Combustion chamber side protector members 12, 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ heat recovery chamber side protecting member 13 hook 13 'grooves 14,15a engagement pieces 15 cuts 16 flange a sand (heat medium)

Claims (3)

Between the combustion chamber (1) and the heat recovery chamber (2), there is provided a screen (3) in which a plurality of water tubes (4) whose vertical directions are in the tube axis direction are arranged in parallel, and each water tube (4) of the screen (3) is provided. Covering the entire circumference of the water pipe (4) of a fluidized bed boiler (B) that circulates the heat medium (a) between the combustion chamber (1) and the heat recovery chamber (2) through A cylindrical protector (10),
It consists of two halved members (11, 12) divided by a plane in the tube axis direction, one of which (11) overlapped in the vertical direction protecting the combustion chamber (1) side of the water tube (4). It consists of a plurality of combustion chamber side protector members (11 ₁ , 11 ₂ , 11 ₃ , 11 ₄ ), and the other (12) is stacked in the vertical direction to protect the heat recovery chamber (2) side of the water pipe (4). It is composed of a plurality of heat recovery chamber side protector members (12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ , 12 ₅ ), and at least one set of combustion chamber side protector members (11) that are vertically adjacent to each other includes an upper protector member ( 11) A protector for a fluidized bed boiler screen, characterized in that a ridge (16) facing downward below the lower edge overlaps the upper surface of the lower protector member (11).   The combustion chamber side protector member (11) is a long plate-like object, the heat recovery chamber side protector member (12) is a long object having a circular cross section, and the heat recovery chamber side protector member (12). The both ends of the water pipe (4) are covered by fitting both the protector members (11, 12) by fitting both end portions of the protector into the groove (13 ') on the back surface of the combustion chamber side protector member (11). Item 10. A screen protector for a fluidized bed boiler according to Item 1.   The at least one pair of the heat recovery chamber side protector members (12) adjacent to each other in the upper and lower sides has a ridge (16) facing the lower side of the lower edge of the upper protector member overlapping the upper surface of the lower protector member. A screen protector for a fluidized bed boiler according to 1 or 2.

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