JP5872372B2 - Fluidized bed reactor and method for producing the same - Google Patents

Description

  The present invention relates to a fluidized bed reactor and a method for producing the same.

  Conventionally, fuel and air supplied from the bottom of the combustion chamber are mixed with circulating particles such as silica sand to form a fluidized bed (fluidized bed), and the fuel is burned in the combustion chamber. There is known a fluidized bed boiler that exchanges heat with water flowing in a wall of a chamber (see Patent Document 1). The exhaust gas generated in the combustion chamber is discharged from the upper part of the furnace together with the circulating particles, and is introduced into a cyclone provided in the fluidized bed reactor. In the cyclone, the exhaust gas and the circulating particles are separated, and the separated circulating particles are reintroduced into the bottom of the combustion chamber and circulated.

JP 2011-106720 A

  Most of the circulating particles discharged from the upper part of the combustion chamber are introduced into the cyclone, but a part thereof flows down along the inner wall surface of the combustion chamber (bottom of the furnace). At this time, the circulating particles can flow while rubbing the inner wall surface of the combustion chamber, and the inner wall surface of the combustion chamber can be worn. Usually, the bottom of the combustion chamber has a tapered shape with a diameter reduced as it goes downward, so that the circulating particles tend to hit the bottom, and the bottom is particularly susceptible to wear.

  As a countermeasure against this wear, in Patent Document 1, a sprayed film is formed on the inner wall surface of the combustion chamber. However, if the fluidized bed reactor is operated for a long period of time, the sprayed coating may be worn by contact with the circulating particles. For this reason, during maintenance of the fluidized bed reactor, an operation for re-forming the sprayed film and a build-up welding operation may occur, resulting in additional costs.

  Therefore, an object of the present invention is to provide a fluidized bed reactor capable of protecting the inner wall surface of a combustion chamber from wear due to circulating particles and suppressing maintenance costs, and a method for manufacturing the same.

  A fluidized bed reactor according to the present invention includes a combustion chamber in which fuel and air supplied therein and air and circulating particles are mixed while flowing upward, and combustion of fuel is performed inside. The bottom portion has a tapered shape that is reduced in diameter as it goes downward, and a protective layer made of granules having a Mohs hardness of 7 or more is formed on the inner wall surface of the bottom portion.

  In the fluidized bed reactor according to the present invention, a protective layer composed of granules having a Mohs hardness of 7 or more is formed on the inner wall surface of the bottom of the combustion chamber. Since the circulating particles that circulate in the combustion chamber are mainly silica sand, the inner wall surface of the combustion chamber can be effectively removed from the wear caused by the circulating particles by forming a protective layer with particles having hardness equal to or higher than that of silica sand. Can protect. As a result, maintenance costs can be reduced.

  The particle size of the granules may be 0.2 mm to 0.4 mm. In this case, since the particle size of the particles is about the same as the particle size of the circulating particles, it is difficult for the particles to fall off from the protective layer. Further, in this case, when forming the protective layer by colliding the particles with the inner wall surface of the bottom portion of the combustion chamber, the particles easily bite and adhere to the inner wall surface.

  The granules may be silica sand or alumina powder.

  The method for producing a fluidized bed reactor according to the present invention includes a combustion chamber in which fuel and air supplied therein and air and circulating particles are mixed while flowing upward, and fuel is burned inside, A method of manufacturing a fluidized bed reactor having a tapered shape with a diameter reduced as the bottom of the combustion chamber heads downward, by causing a granule having a Mohs hardness of 7 or more to collide with an inner wall of the bottom. Forming a protective layer.

  In the method for manufacturing a fluidized bed reactor according to the present invention, a protective layer is formed on the inner wall surface by colliding particles having a Mohs hardness of 7 or more against the inner wall surface of the bottom of the combustion furnace. Since the circulating particles that circulate in the combustion chamber are mainly silica sand, the inner wall surface of the combustion chamber can be effectively removed from the wear caused by the circulating particles by forming a protective layer with particles having hardness equal to or higher than that of silica sand. Can protect. As a result, maintenance costs can be reduced.

  In the step of forming the protective layer, the particles may collide with the inner wall surface at a speed of 10 m / s to 15 m / s. In this case, the particles are likely to bite into and adhere to the inner wall surface of the bottom of the combustion chamber.

  The particle size of the granules may be 0.2 mm to 0.4 mm. In this case, since the particle size of the particles is about the same as the particle size of the circulating particles, it is difficult for the particles to fall off from the protective layer. Further, in this case, when forming the protective layer by colliding the particles with the inner wall surface of the bottom portion of the combustion chamber, the particles easily bite and adhere to the inner wall surface.

  The granules may be silica sand or alumina powder.

  According to the present invention, in the fluidized bed reactor and the manufacturing method thereof, the inner wall surface of the combustion chamber can be protected from wear due to the circulating particles, and maintenance costs can be suppressed.

FIG. 1 is a diagram showing a fluidized bed reactor and a cyclone according to the present embodiment. FIG. 2 is a cross-sectional view showing the vicinity of the bottom of the combustion chamber. FIG. 3 is a view of the vicinity of the bottom of the combustion chamber as viewed from the inside.

  A fluidized bed reactor 1 according to this embodiment will be described with reference to FIGS. The fluidized bed reactor 1 is also called a circulating fluidized bed (CFB) boiler. In the description, the same reference numerals are used for the same elements or elements having the same function, and a duplicate description is omitted.

  As shown in FIGS. 1 and 2, the fluidized bed reactor (furnace) 1 is a tubular member having a hollow interior. The upper and lower ends of the fluidized bed reactor 1 are respectively closed. The inside of the fluidized bed reactor 1 is a combustion chamber 10 in which fuel is burned.

  The combustion chamber 10 includes a bottom portion 12 having a tapered shape that is reduced in diameter toward the lower side, and an upper portion 14 that is continuous with the upper end of the bottom portion 12 and extends in the vertical direction with substantially the same diameter. An opening 16 communicating with the cyclone 100 provided in the fluidized bed reactor 1 is formed in the side wall of the bottom portion 12. A plurality of openings (not shown) for supplying combustion air into the combustion chamber 10 are formed in the bottom wall of the bottom portion 12. A communication channel 18 that communicates with the cyclone 100 is provided on the side wall of the upper portion 14.

  The combustion chamber 10 is mainly filled with silica sand. The silica sand flows from the lower side to the upper side in the combustion chamber 10 and is introduced into the cyclone 100 through the communication channel 18 while accompanying the exhaust gas. In the cyclone 100, exhaust gas and silica sand are separated. Silica sand separated from the exhaust gas reaches the lower part of the combustion chamber 10 through the opening 16 from the lower part of the cyclone 100. In this embodiment, silica sand functions as a circulating granule, and the cyclone 100 functions as a solid-gas separator.

  In the combustion chamber 10, when combustion air is supplied from the bottom wall of the bottom portion 12 and fuel (solid matter) is supplied from the lower portion of the combustion chamber 10, the solid matter containing fuel is moved upward together with the circulating particles by the combustion air. Combustion while flowing toward.

  As shown in FIG. 3, the furnace wall 20 constituting the combustion chamber 10 is composed of flat-plate fins in which water wall tubes (furnace wall pipes) 22 arranged in parallel in the circumferential direction of the furnace wall 20 (left-right direction in the figure). 24, so-called membrane panels connected together. The water wall tube 22 exchanges heat from the combustion reaction in the combustion chamber 10 with water flowing in the water wall tube 22.

  In the present embodiment, a protective layer 26 made of granules having a Mohs hardness of 7 or more is formed on the inner wall surface of the bottom 12 of the combustion chamber 10. Examples of the granular material having a Mohs hardness of 7 or more include silica sand and alumina powder. In particular, when the protective layer 26 is made of silica sand, the particles and the circulating particles of the protective layer 26 are the same substance (silica sand), and therefore the protective layer 26 is less likely to be worn.

  The protective layer 26 is formed by causing particles having a Mohs hardness of 7 or more to collide with the inner wall surface of the bottom 12 of the combustion chamber 10. At this time, the particles may collide with the inner wall surface at a speed of 10 m / s to 15 m / s. In this case, the particles are likely to bite into and adhere to the inner wall surface of the bottom 12 of the combustion chamber 10. The particles may collide with the inner wall surface using sand blasting or the like, or the circulating particles (silica sand) may be caused to flow in the combustion chamber 10 during the operation of the fluidized bed reactor 1, so You may make it collide with a wall surface. “During the operation of the fluidized bed reactor 1” includes, for example, during the initial operation, during the operation, or during the idling operation in which circulating particles are present in the combustion chamber 10 but no fuel or the like is present.

  The particle size of the granules may be 0.2 mm to 0.4 mm. In this case, since the particle size of the granule is about the same as the particle size of the circulating granule, it is difficult for the granule to fall off from the protective layer 26. Further, in this case, when forming the protective layer 26 by causing the particles to collide with the inner wall surface of the bottom 12 of the combustion chamber 10, the particles easily bite and adhere to the inner wall surface.

  In the present embodiment as described above, the protective layer 26 composed of particles having a Mohs hardness of 7 or more is formed on the inner wall surface of the bottom 12 of the combustion chamber 10. Since the circulating particles circulating in the combustion chamber 10 are mainly silica sand, by forming the protective layer 26 with particles having hardness equal to or higher than that of silica sand, the inner wall surface of the combustion chamber 10 can be prevented from being worn by the circulating particles. Can be effectively protected. As a result, maintenance costs can be reduced.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments. For example, the protective layer 26 may be formed on the entire inner wall surface of the bottom 12 of the combustion chamber 10, or the protective layer 26 may be formed on the entire inner wall surface of the upper portion 14 of the combustion chamber 10. From experience, the protective layer 26 may be formed only on the inner wall surface of the combustion chamber where it is known that the wear is significant.

  DESCRIPTION OF SYMBOLS 1 ... Fluidized bed reactor, 10 ... Combustion chamber, 12 ... Bottom part, 20 ... Furnace wall, 26 ... Protective layer.

Claims (9)

The fuel and air supplied to the inside and the circulating particles are mixed while flowing upward, and includes a combustion chamber in which fuel is burned,
The bottom of the combustion chamber has a tapered shape that is reduced in diameter toward the bottom,
A fluidized bed reactor in which a protective layer composed of granules having a Mohs hardness of 7 or more is formed on the inner wall surface of the bottom.   The fluidized bed reactor according to claim 1, wherein a particle diameter of the granules is 0.2 mm to 0.4 mm.   The fluidized bed reactor according to claim 1 or 2, wherein the granule is silica sand.   The fluidized bed reactor according to claim 1 or 2, wherein the granules are alumina powder. Fuel and air supplied to the inside and the circulating particles are mixed while flowing upward, and a combustion chamber in which fuel is combusted is provided. The diameter of the combustion chamber is reduced as the bottom of the combustion chamber goes downward. A method for producing a fluidized bed reactor having a tapered shape,
A method for producing a fluidized bed reactor, comprising a step of forming a protective layer on the inner wall surface by colliding particles having a Mohs hardness of 7 or more against the inner wall surface of the bottom.   The method according to claim 5, wherein, in the step of forming the protective layer, the particles are made to collide with the inner wall surface at a speed of 10 m / s to 15 m / s.   The method according to claim 5 or 6, wherein a particle diameter of the granule is 0.2 mm to 0.4 mm.   The method according to claim 5, wherein the granule is silica sand.   The method according to claim 5, wherein the granules are alumina powder.

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