JP4585501B2 - Circulating fluidized bed boiler - Google Patents

Description

  The present invention relates to a circulating fluidized bed boiler (CFB), and more particularly to a circulating fluidized bed boiler that uses fuel containing a large amount of non-combustible foreign matters such as bead wires, such as waste tires. is there.

The circulating fluidized bed boiler has a combustion chamber in which a high-temperature fluidized bed made of a solid heat medium is formed, and heats the fuel to burn it by injecting the fuel into the fluidized bed. It is.
The circulating fluidized bed boiler is provided with an exhaust treatment device that collects combustion gas. In this exhaust treatment apparatus, in addition to the treatment of the combustion gas, separation and recovery from the combustion gas of the unburned matter and the heat medium that are rolled up with the combustion gas and sent to the exhaust treatment apparatus are performed. The unburned matter and the heat medium collected by the exhaust treatment device are sent again into the combustion chamber.
A part of the high-temperature heat medium recovered by the exhaust treatment device is sent to an external heat exchanger disposed adjacent to the combustion chamber to recover heat, and then sent to the combustion chamber again. ing.
In the external heat exchanger, a fluidized bed of a heat medium is formed inside, and among the heat medium constituting the fluidized bed, an overflow from the external heat exchanger is sent into the combustion chamber. It has become.

As such a circulating fluidized bed boiler, for example, a fluidized bed reactor described in Patent Document 1 described below is known.
This fluidized bed reactor is disposed adjacent to a reaction chamber (combustion chamber) defined by a wall structure formed by a plurality of tubes (heat transfer tubes) and outside the wall structure defining the reaction chamber. A solid material processing chamber (external heat exchanger).
The solid material processing chamber shares the wall portion of the wall structure defining the reaction chamber with the reaction chamber. The common wall portion of the wall structure has a plurality of openings (openings), and the openings are formed between the tubes forming the common wall portion and penetrate the common wall portion.
In this fluidized bed reactor, the common wall portion of the reaction chamber and the solid material processing chamber is formed by a continuous first tube and second tube. The first tube in the common wall portion is bent away from the plane formed by the common wall portion and away from the reaction chamber to form an opening between the second tubes remaining in the plane formed by the common wall portion. .
Further, in this fluidized bed reactor, a gentle bubble fluidized bed having a reference speed slower than 1 [m / s] is formed in the processing chamber.

Japanese Patent No. 2939338

Various fuels such as low-grade coal, wood, paper sludge, RDF (Refuse Derived Fuel), waste tires, and heavy oil can be used for the circulating fluidized bed boiler. However, if the fuel contains non-combustible foreign matter (for example, waste tires include bead wires), the bottom of the combustion chamber gradually becomes non-combustible as the circulating fluidized bed boiler continues to operate. Foreign matter accumulates.
Since a stirring gas is supplied from the bottom to form a fluidized bed of the heat medium in the combustion chamber, non-combustible foreign matter accumulated at the bottom of the combustion chamber is also rolled up with the heat medium by the stirring gas. Since some of the nonflammable foreign matter wound up in this way flows into the external heat exchanger through the opening, the nonflammable in the external heat exchanger as the operation of the circulating fluidized bed boiler is continued. Foreign matter will accumulate.
If nonflammable foreign matter accumulates in the external heat exchanger in this way, the heat exchange area of the external heat exchanger decreases and the heat exchange efficiency decreases. When used, it was necessary to remove nonflammable foreign matter at an appropriate time.

Here, like the fluidized bed reactor described in Patent Document 1, the wall of the reaction chamber (combustion chamber) is composed of a plurality of tubes, and an opening (opening) is formed by bending a part of the tubes. In the formed circulating fluidized bed boiler, for convenience of design, the tube constituting the lower end of the opening may be inclined from the processing chamber (external heat exchanger) side to the reaction chamber side as it goes downward. is there.
In this case, a slope rising from the processing chamber side to the reaction chamber side is formed at the lower edge of the opening. As a result, the flow of the stirring gas supplied to the bottom of the reaction chamber easily flows into the opening along the slope, so that nonflammable foreign matter easily enters the processing chamber.

  The present invention has been made in view of such circumstances, and prevents performance deterioration due to accumulation of nonflammable foreign matter in an external heat exchanger even when fuel containing nonflammable foreign matter is used. An object of the present invention is to provide a circulating fluidized bed boiler capable of performing the above.

In order to solve the above problems, the present invention employs the following means.
That is, the present invention provides a combustion chamber in which a high-temperature fluidized bed composed of a solid heat medium is formed, and recovers and treats the combustion gas generated in the combustion chamber and includes the heat medium contained in the combustion gas. And a heat medium circulation system for supplying the heat medium recovered by the exhaust treatment apparatus to the combustion chamber, and the heat medium circulation system supplies the heat chamber to the combustion chamber. An external heat exchanger in which a part of the heat medium is circulated inside and recovers heat from the heat medium, and stirring that is connected to the external heat exchanger and stirs the heat medium inside the external heat exchanger A heat exchanger side wind chamber that generates an air flow to form a fluidized bed, and a connection portion that connects the inside of the external heat exchanger and the combustion chamber, the connection portion of the combustion chamber is connected to the side wall, the opening area, is the fuel foreign substance to the agitated air flow 0 that flows into feed has been said external heat exchanger from the external heat exchanger is set to an opening area of suppressing the flow to the combustion chamber, the furnace bottom cross-sectional area of the external heat exchanger. Provided is a circulating fluidized bed boiler set within a range of 8% to 4.0%.

In the circulating fluidized bed boiler configured as described above, the heat medium supplied into the external heat exchanger is stirred by the stirring airflow generated by the heat exchanger side air chamber to form a fluidized bed, and this stirring is performed. The air current is sent to the combustion chamber through a connecting portion that connects the external heat exchanger and the combustion chamber.
Here, in the circulating fluidized bed boiler, the circulating amount of the heat medium is kept substantially constant during steady operation. For this reason, during steady operation, the flow rate of the gas sent from the external heat exchanger to the combustion chamber is also kept substantially constant.
In the circulating fluidized bed boiler of the present invention, the opening area of the connecting portion connecting the external heat exchanger and the combustion chamber is within the range of 0.8% to 4.0% of the furnace bottom cross-sectional area of the external heat exchanger. Is set.
In addition, the opening area of a connection part here is an opening area in the site | part in which a flow-path cross-sectional area becomes the smallest in a connection part.
This value is smaller than the ratio of the opening area of the connection portion to the furnace cross-sectional area of the external heat exchanger in a general circulating fluidized bed boiler.
For this reason, in this circulating fluidized bed boiler, the flow velocity of the air flow from the external heat exchanger to the combustion chamber will be higher than that of the conventional circulating fluidized bed boiler, and the non-combustible property from the combustion chamber to the external heat exchanger will be increased. The backflow of foreign matter is suppressed.

In the present invention, the connecting portion is provided with a closing member that closes a part of the connecting portion, whereby the opening area of the connecting portion is set to 0. 0 of the furnace bottom cross-sectional area of the external heat exchanger. It may be set within a range of 8% to 4.0%.
In this case, in the circulating fluidized bed boiler in which the opening area of the connecting portion is larger than the set range of the present invention (conventional circulating fluidized bed boiler that does not consider the accumulation of nonflammable foreign matter) By providing the closing member, the circulating fluidized bed boiler of the present invention can be obtained.
That is, the circulating fluidized bed boiler of the present invention suitable for the use of fuel containing non-combustible foreign matters can be obtained by making a slight improvement to the conventional circulating fluidized bed boiler.

  In addition, the amount of heat medium supplied from the external heat exchanger to the combustion chamber is controlled by setting the opening area of the connecting portion within the range of 1.0% to 3.2% of the cross-sectional area of the furnace bottom of the external heat exchanger. The flow rate of airflow from the external heat exchanger to the combustion chamber is further increased while maintaining the flow rate within the appropriate range, and the backflow of nonflammable foreign matter from the combustion chamber to the external heat exchanger can be more effectively suppressed. it can.

In the present invention, a slope is formed at a lower edge portion of the opening portion on the combustion chamber side of the connection portion, and the blocking member is the slope portion of the opening portion on the combustion chamber side of the connection portion. The area opposite to may be closed.
In this case, giving priority to the design, the slope is formed at the lower edge of the opening on the combustion chamber side of the connection portion, which is one of the causes of the backflow of nonflammable foreign matter. Since the slope is blocked, the backflow of nonflammable foreign matter can be more effectively prevented.

  Moreover, in this invention, the said closure member may be obstruct | occluded so that the said connection part may be traversed to an up-down direction.

Further, the present invention provides a combustion chamber in which a high-temperature fluidized bed made of a solid heat medium is formed, and recovers and processes the combustion gas generated in the combustion chamber and includes the heat medium contained in the combustion gas. And a heat medium circulation system for supplying the heat medium recovered by the exhaust treatment apparatus to the combustion chamber, and the heat medium circulation system supplies the heat chamber to the combustion chamber. An external heat exchanger in which a part of the heat medium is circulated inside and recovers heat from the heat medium, and stirring that is connected to the external heat exchanger and stirs the heat medium inside the external heat exchanger A heat exchanger side wind chamber that generates an air flow to form a fluidized bed, and a connection portion that connects the inside of the external heat exchanger and the combustion chamber, the connection portion of the combustion portion The external heat exchanger is connected to the side wall and the foreign matter in the fuel is conveyed to the stirring airflow . And that flowing from the external heat exchanger is set to an opening area of suppressing the flow to the combustion chamber into the slope to the lower edge portion of the combustion chamber side opening of the connecting portion is formed And the said closure member provides the circulating fluidized bed boiler which has block | closed the area | region which opposes the said slope among the opening parts by the side of the said combustion chamber of the said connection part.

  In this case, giving priority to the design, the slope is formed at the lower edge of the opening on the combustion chamber side of the connection portion, which is one of the causes of the backflow of nonflammable foreign matter. Since the slope is blocked, the backflow of nonflammable foreign matter can be effectively prevented.

Further, the present invention provides a combustion chamber in which a high-temperature fluidized bed made of a solid heat medium is formed, and recovers and processes the combustion gas generated in the combustion chamber and includes the heat medium contained in the combustion gas. And a heat medium circulation system for supplying the heat medium recovered by the exhaust treatment apparatus to the combustion chamber, and the heat medium circulation system supplies the heat chamber to the combustion chamber. An external heat exchanger in which a part of the heat medium is circulated inside and recovers heat from the heat medium, and stirring that is connected to the external heat exchanger and stirs the heat medium inside the external heat exchanger A heat exchanger side wind chamber that generates an air flow to form a fluidized bed, and a connection portion that connects the inside of the external heat exchanger and the combustion chamber, the connection portion of the combustion portion Connected to the side wall, and the wall of the combustion chamber is composed of a plurality of heat transfer tubes. Together with the combustion chamber in that the connecting portion is connected to the fuel foreign matter flows into the external heat exchanger is transported to the agitation gas stream from the external heat exchanger by bending a portion of the heat transfer tube An opening that is set to an opening area that is suppressed by the flow to is formed, and among the heat transfer tubes, the heat transfer tube that constitutes the lower end of the opening is directed downward toward the external heat exchanger side A circulating fluidized bed boiler in which the inclined heat transfer tube is covered with a refractory material and the lower edge of the opening is a horizontal surface. To do.

  In this case, giving priority to the design, out of the heat transfer tubes constituting the wall of the combustion chamber, the heat transfer tube constituting the lower end of the opening of the connection portion is arranged on the external heat exchanger side as it goes downward. The lower end of the opening on the combustion chamber side of the connecting portion is a horizontal surface, and the slope that is one of the causes of the backflow of nonflammable foreign matter is Therefore, the backflow of nonflammable foreign matter can be effectively prevented.

  In the circulating fluidized bed boiler configured in this way, even if fuel containing non-combustible foreign matter is used, the backflow of non-combustible foreign matter from the combustion chamber to the external heat exchanger is prevented, and the external heat exchanger is supplied. Performance degradation due to accumulation of non-flammable foreign matter can be prevented.

Embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, a circulating fluidized bed boiler 1 according to this embodiment collects a combustion chamber 2 in which a high-temperature fluidized bed made of a solid heat medium is formed, and combustion gas generated in the combustion chamber 2. And an exhaust treatment device 3 that collects the heat medium contained in the combustion gas and a heat medium circulation system 4 that supplies the heat medium collected by the exhaust treatment device 3 to the combustion chamber 2.

The combustion chamber 2 has a box shape extending in the vertical direction, and a wall 2a constituting the combustion chamber 2 is constituted by a plurality of heat transfer tubes P extending in the vertical direction as shown in FIG. The surfaces of these heat transfer tubes P are covered with a refractory material so that wear due to contact with a substance such as a heat medium flowing in the combustion chamber 2 does not occur.
In addition, as shown in FIG. 1, a combustion chamber side wind chamber 11 that generates a fluidized bed in the combustion chamber 2 by generating a stirring air stream that stirs the heat medium in the combustion chamber 2 at the lower portion of the combustion chamber 2. Is provided.

The exhaust treatment device 3 is connected to the upper portion of the combustion chamber 2 and has a cyclone device that separates unburned components and heat medium from the combustion gas after being used for generating steam.
The heat medium circulation system 4 has a heat medium passage 12 through which the heat medium recovered by the exhaust treatment device 3 is sent to the combustion chamber 2.
The heat medium passage 12 is provided with a seal pot 13 that prevents the back flow of the combustion gas from the combustion chamber 2 while allowing the supply of the heat medium to the combustion chamber 2.
Further, a bypass flow path 14 that bypasses a part of the heat medium is connected to the seal pot 13. An external heat exchanger 16 that recovers heat from the heat medium is connected to the bypass flow path 14.

The external heat exchanger 16 has a box shape disposed adjacent to the lower part of the combustion chamber 2, and its wall portion is a heat exchange surface for recovering heat from the heat medium.
The external heat exchanger 16 is also provided with a heat exchanger-side air chamber 17 that generates a stirring air stream that stirs the heat medium in the external heat exchanger 16 to form a fluidized bed in the external heat exchanger 16. ing.
The external heat exchanger 16 and the combustion chamber 2 are connected by a connection portion 19.
The external heat exchanger 16 shares a part of the wall with the combustion chamber 2 (hereinafter, this wall is referred to as “common wall 18”).
In the present embodiment, the common wall 18 is provided with a communication hole that communicates from the external heat exchanger 16 side to the combustion chamber 2 side, and this communication hole constitutes the connection portion 19.

The communication hole constituting the connecting portion 19 is formed by bending the heat transfer tube P constituting the common wall 18. Specifically, a part of the heat transfer tube P constituting the common wall 18 is stretched from the plane formed by the other heat transfer tubes P toward the external heat exchanger 16 so as to bypass the region where the communication holes are formed. The communication hole is formed by being bent so as to protrude.
In this embodiment, the part which comprises the lower end part of the opening part by the side of the combustion chamber 2 of the connection part 19 among the bent heat-transfer tubes P is the combustion chamber 2 side from the external heat exchanger 16 side as it goes below. It is inclined to face.
As a result, a slope 19 a that rises from the combustion chamber 2 side to the external heat exchanger 16 side is formed at the lower edge of the opening of the connection portion 19 on the combustion chamber 2 side.

The opening area of the connection portion 19 is set in the range of 0.8% to 4.0%, preferably in the range of 1.0% to 3.2% of the furnace bottom cross-sectional area of the external heat exchanger 16. Has been. Here, the opening area of the connecting portion 19 is an opening area at a portion where the opening area is the smallest in the opening portion 19.
In the present embodiment, as the connecting portion 19, a part of the connecting portion whose opening area is larger than 4.0% of the furnace bottom cross-sectional area of the external heat exchanger 16 is closed by the closing member 21, thereby connecting the connecting portion 19. The actual opening area is set in a range of 0.8% to 4.0% of the furnace bottom cross-sectional area of the external heat exchanger 16. Specifically, in this embodiment, the upper part of the opening part on the combustion chamber 2 side of the connection part 19 is covered with the plate-like closing member 21, thereby reducing the actual opening area of the connection part 19 to the external heat exchanger. It is contained in the range of 0.8% to 4.0% of the cross-sectional area of 16 furnace bottoms.

In the circulating fluidized bed boiler 1 configured as described above, the heat medium supplied into the external heat exchanger 16 is stirred by the stirring air flow generated by the heat exchanger-side air chamber 17 to form a fluidized bed. The agitated air current is fed into the combustion chamber 2 through a connection portion 19 that connects the external heat exchanger 16 and the combustion chamber 2.
Here, in the circulating fluidized bed boiler, the circulating amount of the heat medium is kept substantially constant during steady operation. For this reason, during steady operation, the flow rate of the gas sent from the external heat exchanger to the combustion chamber is also kept substantially constant.

In the circulating fluidized bed boiler 1 according to the present embodiment, the opening area of the connecting portion 19 that connects the external heat exchanger 16 and the combustion chamber 2 is from 0.8% to 4% of the furnace bottom cross-sectional area of the external heat exchanger 16. It is set within the range of 0%.
This value is smaller than the ratio of the opening area of the connection portion to the furnace cross-sectional area of the external heat exchanger in a general circulating fluidized bed boiler.
For this reason, in this circulating fluidized bed boiler 1, the flow velocity of the air flow from the external heat exchanger 16 to the combustion chamber 2 is increased as compared with the conventional circulating fluidized bed boiler, and the external heat exchanger 16 from the combustion chamber 2 is increased. The backflow of non-flammable foreign matter to is suppressed.

  As described above, in the circulating fluidized bed boiler 1 according to the present embodiment, the backflow of the nonflammable foreign matter from the combustion chamber 2 to the external heat exchanger 16 is prevented even when the fuel containing the nonflammable foreign matter is used. In addition, it is possible to prevent performance degradation due to accumulation of nonflammable foreign matter in the external heat exchanger 16.

  Further, by setting the opening area of the connection portion 19 within the range of 1.0% to 3.2% of the cross-sectional area of the furnace bottom of the external heat exchanger 16, heat from the external heat exchanger 16 to the combustion chamber 2 can be obtained. While maintaining the supply amount of the medium within an appropriate range, the flow rate of the air flow from the external heat exchanger 16 to the combustion chamber 2 is further increased to reduce the backflow of nonflammable foreign matter from the combustion chamber 2 to the external heat exchanger 16. It can suppress more effectively.

In the present embodiment, as described above, the connecting portion 19 is provided with the closing member 21 that closes a part of the opening on the combustion chamber 2 side, so that the opening area of the connecting portion 19 is external heat exchange. It is set in the range of 0.8% to 4.0% of the furnace bottom cross-sectional area of the vessel 16.
For this reason, with respect to the circulating fluidized bed boiler (the conventional circulating fluidized bed boiler which does not consider the accumulation of nonflammable foreign matter) whose opening area of the connecting portion 19 is larger than the set range of the present invention, By providing the closing member 12, the circulating fluidized bed boiler 1 of the present invention can be obtained.
That is, the circulating fluidized bed boiler 1 of the present invention suitable for the use of fuel containing non-combustible foreign matters can be obtained by adding a slight improvement to the conventional circulating fluidized bed boiler.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the circulating fluidized bed boiler 31 according to the present embodiment, in the circulating fluidized bed boiler 1 shown in the first embodiment, instead of providing the closing member 21 at the opening on the combustion chamber 2 side of the connecting portion 19, Of the opening on the combustion chamber 2 side, a blocking member 32 is provided to close the region facing the slope 19a.
In the circulating fluidized bed boiler 31 configured in this way, the slope 19a is formed at the lower edge of the opening on the combustion chamber 2 side of the connecting portion 19 giving priority to the design convenience, while being nonflammable. Since the slope 19a, which is one of the causes of the backflow of foreign matter, is blocked, the backflow of nonflammable foreign matter can be effectively prevented.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
In the circulating fluidized bed boiler 41 according to the present embodiment, in the circulating fluidized bed boiler 1 shown in the first embodiment, in addition to the closing member 21, the connecting portion 19 has an opening on the combustion chamber 2 side of the connecting portion 19. Of the opening on the combustion chamber 2 side, a blocking member 32 is further provided to block the region facing the slope 19a.
In the circulating fluidized bed boiler 41 configured as described above, the connecting portion 19 is configured with the slope 19a formed at the lower edge portion of the opening portion of the connecting portion 19 on the combustion chamber 2 side in consideration of design convenience. In addition to the effect of preventing the backflow of nonflammable foreign matter due to the reduction of the opening area, the backflow prevention effect by blocking the slope 19a, which is one of the causes of backflow of nonflammable foreign matter, is also obtained. The backflow of nonflammable foreign matter can be more effectively prevented.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The circulating fluidized bed boiler 51 according to the present embodiment is the same as the circulating fluidized bed boiler 1 shown in the first embodiment. The closing member 21 closes the upper part of the opening at the opening on the combustion chamber 2 side of the connecting part 19. Instead, a closing member 52 that closes the opening so as to cross the opening in the vertical direction is provided.
In the present embodiment, the closing member 52 is provided with the same shape on both the left and right sides of the opening on the combustion chamber 2 side of the connecting portion 19.
In the present embodiment as well, the actual opening area of the connecting portion 19 is within the range of 0.8% to 4.0% of the furnace bottom cross-sectional area of the external heat exchanger 16.

  In the circulating fluidized bed boiler 51 configured as described above, the connecting portion 19 is configured with the slope 19a formed at the lower edge portion of the opening portion of the connecting portion 19 on the combustion chamber 2 side in consideration of design convenience. In addition to the effect of preventing the backflow of nonflammable foreign matter due to the reduction of the opening area, the backflow prevention effect by blocking the slope 19a, which is one of the causes of backflow of nonflammable foreign matter, is also obtained. The backflow of nonflammable foreign matter can be prevented more effectively.

[Fifth embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG.
In the circulating fluidized bed boiler 61 according to the present embodiment, in the circulating fluidized bed boiler 1 shown in the first embodiment, instead of providing the closing member 21 that closes the upper portion of the opening on the combustion chamber 2 side of the connecting portion 19, In the heat transfer tube P (not shown in FIG. 6), a refractory material 62 is provided to cover a portion constituting the lower edge of the opening on the combustion chamber 2 side of the connecting portion 19, and the opening on the combustion chamber 2 side of the connecting portion 19 The lower edge of the part is a horizontal plane.

  According to the circulating fluidized bed boiler 61 configured in this way, among the heat transfer tubes P constituting the common wall 18 shared by the combustion chamber 2 and the external heat exchanger 16 in consideration of design convenience, While connecting the heat transfer pipe P constituting the lower end of the opening on the combustion chamber 2 side of the connection portion 19 so as to be directed downward from the external heat exchanger 16 side toward the combustion chamber 2 side, Since the lower end of the opening on the combustion chamber 2 side of the portion 19 is a horizontal plane, there is no slope 19a (indicated by a two-dot chain line in FIG. 7) which is one of the causes of backflow of nonflammable foreign matter. It is possible to effectively prevent the reverse flow of sexual foreign substances.

Here, in order to investigate the effect of the circulating fluidized bed boiler according to the present invention, in the circulating fluidized bed boiler, variously changing the ratio of the opening area of the connecting portion 19 and the furnace bottom cross-sectional area of the external heat exchanger 16, A test was conducted to compare the reverse flow rate of nonflammable foreign matter in each case.
The results are shown below.

In this test, a reduced model of an actual circulating fluidized bed boiler was used, a simulated tire piece (rubber sheet) was used as the fuel, and a simulated bead wire piece (wire piece) was used as the non-combustible foreign matter contained in the fuel.
In this test, the combustion of fuel in the combustion chamber 2 is not performed, and only the formation of a fluidized bed by the combustion chamber-side wind chamber 11 is performed. In this test, the formation of the fluidized bed in the external heat exchanger 16 is not performed, and only the formation of the airflow by the heat exchanger side wind chamber 17 is performed.

Further, in this test, in order to faithfully simulate an actual circulating fluidized bed boiler, the ratio of the projected area of the simulated tire piece to the opening area of the connecting portion 19 of the reduced model is set as the actual circulating fluidized bed boiler connecting portion 19. The projected area ratio of the tire piece with respect to the opening area is the same, and the scale of the simulated bead wire piece with respect to the actual bead wire is the same as the scale of the reduced model with respect to the actual circulating fluidized bed boiler. (However, the average particle diameter of the heat medium is the same as the actual circulating fluidized bed boiler).
In addition, the differential pressure between the combustion chamber 2 and the external heat exchanger 16 is adjusted so that the momentum ratio of the simulated tire piece, the simulated bead wire piece, and the heat medium is approximately the same as that of the actual circulating fluidized bed boiler. Yes.

  As shown in the graph of FIG. 8, assuming that the opening area of the connecting portion 19 is about 2.8% of the furnace bottom cross-sectional area of the external heat exchanger 16, the opening area of the connecting portion 19 is the external heat. When the cross-sectional area of the furnace bottom of the exchanger 16 was about 1.8%, the reverse flow rate of the simulated bead wire was reduced to about 30%. On the other hand, when the opening area of the connection portion 19 was about 4.3% of the furnace bottom cross-sectional area of the external heat exchanger 16, the reverse flow rate of the simulated bead wire increased to about 190%.

Further, under the same conditions as in the above test, when the connecting portion 19 is horizontally closed with a closing member (Example 1; corresponding to the first embodiment), and when the connecting portion 19 is vertically closed with a closing member (implemented) Example 2 (corresponding to the fourth embodiment) and the back flow rate of the simulated bead wire were compared in the case where no closing member was provided.
As a result, as shown in the graph of FIG. 9, the reverse flow rate of the simulated bead wire was 1/10 or less compared to the case where no closing member was provided. In particular, in Example 1 in which the connecting portion 19 was horizontally closed with a closing member, the back flow rate was slightly smaller than in Example 2 in which the connecting portion 19 was vertically closed with a closing member.
From this, it was found that the same effect as the circulating fluidized bed boiler according to the present invention can be obtained by attaching the closing member to the conventional circulating fluidized bed boiler.

It is a longitudinal section showing roughly the composition of the circulating fluidized bed boiler concerning a first embodiment of the present invention. It is the figure which showed the opening part which connects the external heat exchanger and combustion chamber of the circulating fluidized bed boiler which concerns on 1st embodiment of this invention from the combustion chamber side. It is a principal part enlarged view of FIG. It is a longitudinal cross-sectional view which shows schematically the structure of the circulating fluidized bed boiler which concerns on 2nd embodiment of this invention. It is a longitudinal cross-sectional view which shows schematically the structure of the circulating fluidized bed boiler which concerns on 3rd embodiment of this invention. It is the figure which showed the opening part which connects an external heat exchanger and a combustion chamber among the circulating fluidized bed boiler which concerns on 4th embodiment of this invention from the combustion chamber side. It is a longitudinal cross-sectional view which shows roughly the structure of the circulating fluidized bed boiler which concerns on 5th embodiment of this invention. It is the graph which compared the reverse flow volume of the nonflammable foreign material (bead wire) with the circulating fluidized bed boiler to which this invention is applied, and the conventional circulating fluidized bed boiler. It is the graph which compared the reverse flow volume of the nonflammable foreign material (bead wire) with the circulating fluidized bed boiler to which this invention is applied, and the conventional circulating fluidized bed boiler.

Explanation of symbols

1, 31, 41, 51, 61 Circulating fluidized bed boiler 2 Combustion chamber 3 Exhaust treatment device 4 Heat medium circulation system 16 External heat exchanger 17 Heat exchanger side air chamber 18 Common wall 19 Opening portion 19a Slope 21, 32, 42 , 52 Closure member 62 Refractory material

Claims (8)

A combustion chamber in which a high-temperature fluidized bed made of a solid heat medium is formed;
An exhaust treatment device that collects and processes the combustion gas generated in the combustion chamber and collects the heat medium contained in the combustion gas;
A heat medium circulation system for supplying the heat medium recovered by the exhaust treatment device to the combustion chamber,
The heat medium circulation system includes an external heat exchanger in which a part of the heat medium supplied to the combustion chamber is circulated to recover heat from the heat medium;
A heat exchanger side wind chamber connected to the external heat exchanger and generating a fluidized bed by generating a stirring air flow for stirring the heat medium inside the external heat exchanger;
Having a connection part for connecting the inside of the external heat exchanger and the combustion chamber;
The connecting portion is connected to a side wall of the combustion chamber, and the opening area of the connecting portion is that the foreign heat in the fuel is conveyed to the stirring airflow and flows into the external heat exchanger from the external heat exchanger. A circulating fluidized bed boiler that is set to an opening area that is suppressed by a flow to the combustion chamber and that is set within a range of 0.8% to 4.0% of a cross-sectional area of the furnace bottom of the external heat exchanger.   The connecting portion is provided with a closing member that closes a part of the connecting portion, whereby the opening area of the connecting portion is from 0.8% to 4.0% of the furnace bottom cross-sectional area of the external heat exchanger. The circulating fluidized bed boiler according to claim 1, which is set within a range of%.   The circulating fluidized bed boiler according to claim 1 or 2, wherein an opening area of the connection portion is set in a range of 1.0% to 3.2% of a furnace cross-sectional area of the external heat exchanger. A slope is formed at the lower edge of the opening on the combustion chamber side of the connection part,
The circulating fluidized bed boiler according to claim 2, wherein the closing member closes a region facing the slope in the opening on the combustion chamber side of the connection portion.   The circulating fluidized bed boiler according to claim 2, wherein the closing member is closed so as to cross the connecting portion in the vertical direction. A combustion chamber in which a high-temperature fluidized bed made of a solid heat medium is formed;
An exhaust treatment device that collects and processes the combustion gas generated in the combustion chamber and collects the heat medium contained in the combustion gas;
A heat medium circulation system for supplying the heat medium recovered by the exhaust treatment device to the combustion chamber,
The heat medium circulation system includes an external heat exchanger in which a part of the heat medium supplied to the combustion chamber is circulated to recover heat from the heat medium;
A heat exchanger side wind chamber connected to the external heat exchanger and generating a fluidized bed by generating a stirring air flow for stirring the heat medium inside the external heat exchanger;
Having a connection part for connecting the inside of the external heat exchanger and the combustion chamber;
The connecting portion is connected to a side wall of the combustion portion and suppresses foreign matter in the fuel from being conveyed to the stirring airflow and flowing into the external heat exchanger by the flow from the external heat exchanger to the combustion chamber. The opening area is set to
A slope is formed at the lower edge of the opening on the combustion chamber side of the connection,
A circulating fluidized bed boiler in which the closing member closes a region facing the slope in the opening on the combustion chamber side of the connecting portion. A combustion chamber in which a high-temperature fluidized bed made of a solid heat medium is formed;
An exhaust treatment device that collects and processes the combustion gas generated in the combustion chamber and collects the heat medium contained in the combustion gas;
A heat medium circulation system for supplying the heat medium recovered by the exhaust treatment device to the combustion chamber,
The heat medium circulation system includes an external heat exchanger in which a part of the heat medium supplied to the combustion chamber is circulated to recover heat from the heat medium;
A heat exchanger side wind chamber connected to the external heat exchanger and generating a fluidized bed by generating a stirring air flow for stirring the heat medium inside the external heat exchanger;
Having a connection part for connecting the inside of the external heat exchanger and the combustion chamber;
The connection part is connected to a side wall of the combustion part,
The wall of the combustion chamber is composed of a plurality of heat transfer tubes, and the connection portion is connected by bending a part of the heat transfer tubes, so that foreign matters in the fuel are conveyed to the agitated airflow, and the external heat exchanger is formed an opening set in the opening area prevents the flow from the external heat exchanger by the flow into the combustion chamber to,
Among the heat transfer tubes, the heat transfer tube constituting the lower end portion of the opening is inclined so as to go from the external heat exchanger side to the combustion chamber side as it goes downward.
The circulating fluidized bed boiler in which the inclined heat transfer tube is covered with a refractory material and the lower edge of the opening is a horizontal plane.   The circulating fluidized bed boiler according to any one of claims 1 to 7, wherein the combustion gas is generated by heating a fuel containing incombustible foreign matter.

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