JP4117961B2 - Fluidized bed boiler equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluidized bed boiler apparatus, and more particularly to a fluidized bed boiler apparatus suitable for uniformly distributing fuel injected from a fuel supply nozzle into a furnace.
[0002]
[Prior art]
Generally, it is necessary to supply the fuel into the fluidized bed furnace as evenly as possible. In order to distribute the fuel evenly, it is desirable to increase the number of fuel supply nozzles. However, when the number of nozzles is increased, the fuel supply system becomes complicated, and there is a problem that equipment costs increase. On the other hand, if the number of fuel supply nozzles is small, the number of fuel injection points is reduced, and a large amount of air is consumed at the tip of the nozzle. Particles that could not be completely combusted in this region reach the fluidized bed surface, It may be scattered from the freeboard toward the cyclone and burned in places other than the furnace. When unburned particles are burned in, for example, a cyclone, the ash is melted and agglomerates are generated, and the ash extraction pipe may be blocked to stop the plant. On the other hand, when the fuel burns locally only at the tip of the fuel supply nozzle, there is a problem that the region becomes a reducing atmosphere and the adjacent heat transfer tubes are easily corroded.
[0003]
In order to solve such a problem, a boiler device in which a distributor (fuel distribution device) is arranged above the tip of a fuel supply nozzle has been proposed as disclosed in, for example, Japanese Patent Publication No. 6-504360.
FIG. 27 is an explanatory diagram showing such a conventional technique. In FIG. 27, this apparatus includes a pressure vessel 271, a fluidized bed furnace 272 provided in the pressure vessel 271, a diffusion plate 273 provided at the bottom of the fluidized bed furnace 272, and the diffusion plate 273. Provided in the fluidized bed 274, a fluidized bed 274 formed by fluidized air supplied from the fluidized bed, a free board 275 above the fluidized bed 274, a fuel supply nozzle 276 for supplying fuel to the fluidized bed 274, and the fluidized bed 274. Distributor 278 comprising a heat transfer tube 277, and a wing-shaped member inclined obliquely upward extending outward from a central portion or central section or a funnel-shaped cone member extending obliquely upward. And a cyclone 279 connected to the free board 275 of the fluidized bed furnace 272.
[0004]
In such a configuration, the air supplied from the diffuser plate 273 into the fluidized bed furnace 272 flows through the fluidizing medium to form the fluidized bed 274. On the other hand, the fuel supplied to the fluidized bed 274 through the fuel supply nozzle 276 is distributed by the distributor 278, mixed with the fluidized air supplied from the diffuser pipe 273, and burned to heat the fluidized bed 274. The combustion gas rises while heating the flow medium flowing in the heat transfer tube 277 together with the heated fluidized bed 274, and flows into the cyclone 279 via the free board 275, where solids are removed, and the downstream exhaust gas treatment device, for example, It is released through.
[0005]
[Problems to be solved by the invention]
However, the distributor of FIG. 27 has an uncooled structure, and even if it is made of a high-temperature durable material such as stainless steel, it is difficult to use for a long time at a high temperature of about 860 ° C., for example. For example, there is a problem that the distributor suspended from the heat transfer tube comes off and goes around in the fluidized bed furnace and damages the heat transfer tube. The distributor of FIG. 27 is provided on the assumption that the fuel input from the fuel supply nozzle hits the center of the distributor, but actually grasps the fluid state of the fluid medium and bubbles in the fluidized bed. It is difficult to determine whether or not the fuel injected into the fluidized bed collides with the center of the distributor. Further, even if the load is set so that the positional relationship between the distributor and the fuel supply nozzle is appropriate assuming that the load is 100%, the reach of the fuel injected from the fuel supply nozzle changes due to the load fluctuation. The fuel may not collide with the center of the distributor.
[0006]
FIGS. 28, 29 and 30 are explanatory views showing the positional relationship between the distributor 278 and the fuel injection nozzle 276 in the above-described prior art. When the positional relationship between the fuel supply nozzle 276 and the distributor 278 is appropriate as shown in FIG. 28, the fuel can be evenly distributed to some extent, but the position of the fuel supply nozzle 276 as shown in FIG. 29 or FIG. Alternatively, if the fuel injection amount is not appropriate, the fuel distribution may be inhibited. That is, since the flow of fuel or air in the fluidized bed changes depending on the load condition, the position where the fuel blown out from the fuel supply nozzle rises and reaches the distributor 278 also changes from front to back and left and right. However, in many cases, the fuel arrival position deviates from the center of the distributor and collides with the surrounding inclined member, so that the fuel can collide with the inclined surface of the inclined member. The result is an uneven flow.
[0007]
The first problem of the present invention is to solve the above-mentioned problems of the prior art, and even if the fuel supply nozzle position is slightly shifted or the injection speed or amount of fuel injected from the fuel supply nozzle is changed, the fuel is injected. Another object of the present invention is to provide a fluidized bed boiler apparatus that can uniformly distribute the fuel in the fluidized bed.
Moreover, the 2nd subject of this invention is providing the fluidized bed boiler apparatus which can compact the said pressure vessel of the pressurization type fluidized bed boiler apparatus which provided the fluidized bed furnace in the pressure vessel.
[0008]
Furthermore, a third object of the present invention is to provide a fluidized bed boiler apparatus that can reduce the number of dummy tubes used and can prevent wear of heat transfer tubes and dummy tubes.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention claimed in the present application is as follows.
(1) Fluidized bed furnace, diffuser plate provided at the bottom of the fluidized bed furnace, fluidized bed formed by fluidized air supplied from the diffuser plate, and fuel to the fluidized bed In a fluidized bed boiler apparatus having a fuel supply nozzle and a heat transfer tube group provided at an upper portion of the fuel supply nozzle, the flow is injected from the fuel supply nozzle of at least the lowest heat transfer tube of the heat transfer tube group and flows Horizontally extending fins are provided where the fuel entrained by the chemical air contacts The fuel injection direction of the fuel supply nozzle is the same as the longitudinal direction of the lowermost heat transfer tube, and a fin extending in the right direction is provided on the left side of the heat transfer tube on the right side across the plane position of the fuel supply nozzle, The heat transfer tube is provided with a fin extending in the left direction, and the center heat transfer tube is provided with a fin extending in both the left and right directions. A fluidized bed boiler apparatus characterized by that.
[0010]
(2) The fluidized bed boiler device according to (1), wherein the fin is provided with a saw-tooth cut.
( 3 (1) In the above (1), the heat transfer tube closer to the fuel injection position of the fuel supply nozzle has a wider fin mounting width. Or (2) The fluidized bed boiler apparatus described in 1.
[0011]
( 4 ) Arrange the heat transfer tube so that the fuel injection direction of the fuel supply nozzle and the longitudinal direction of the lowermost heat transfer tube are orthogonal, and the fins of the heat transfer tube are reversed left and right across the plane position of the fuel supply nozzle The above (1) characterized by being alternately attached Any one of (3) The fluidized bed boiler apparatus described in 1.
( 5 (1) to (1), wherein the lowermost heat transfer tube is covered with an anti-wear cover, and the fin is provided on the anti-wear cover. 4 ). The fluidized bed boiler device according to any one of the above.
[0012]
( 6 ) Fluidized bed furnace, diffuser plate provided at the bottom of the fluidized bed furnace, fluidized bed formed by fluidized air supplied from the diffuser plate, and fuel supply for supplying fuel to the fluidized bed In a fluidized bed boiler apparatus having a nozzle and a heat transfer tube group provided in the fluidized bed above the fuel supply nozzle, at a position where the fuel injected from the fuel injection nozzle is at the bottom of the heat transfer tube, An upwardly convex central member, an outer peripheral member having an upwardly inclined wall surface provided along the lower end outer peripheral portion of the central member, and an upper wall surface of the central member; Ends below the upper space of the fuel distributor and the upper wall surface of the central member, respectively A fluidized bed boiler apparatus comprising a fuel distributor having an open communication pipe.
[0013]
( 7 ) The upwardly convex central member is Cylindrical member An outer peripheral member having an upwardly inclined wall surface and extending obliquely upward provided along a lower end outer peripheral portion of the central member Wings The above (characterized by 6 ).
[0014]
( 8 ) The fluidized bed boiler device is a pressurized fluidized bed boiler device, and the fluidized bed furnace fixes the pressure vessel, the refractory material disposed along the inner surface of the pressure vessel, and the refractory material. (1) to (1) having a water cooling wall composed of a group of water pipes arranged on the surface thereof. 7 ). The fluidized bed boiler device according to any one of the above.
( 9 (1) to (1) above, wherein the distance between the fuel supply nozzle and the lowermost heat transfer tube and the distance between the heat transfer tube groups arranged in the fluidized bed are 800 mm or less, respectively. 8 ). The fluidized bed boiler device according to any one of the above.
( 10 ) The volume ratio of the heat transfer tube group is set to 12% or more ( 9 ).
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to the drawings.
1 to 3 are explanatory views showing an embodiment of the present invention. FIG. 1 is a view showing a main part of the lowermost heat transfer tube as viewed from the lower side of the fuel injection nozzle. FIG. II-II arrow direction sectional drawing, FIG. 3 is the principal part enlarged view of FIG. In the figure, this apparatus includes a fluidized bed furnace, a diffuser plate provided at the bottom of the fluidized bed furnace, a fluidized bed formed by fluidized air supplied from the diffuser plate, and a fluidized bed. In a fluidized bed boiler apparatus (see FIG. 27) having a fuel supply nozzle for supplying fuel and a heat transfer tube group provided in the fluidized bed above the fuel supply nozzle, the fuel injection direction of the fuel supply nozzle 1 The lowermost heat transfer tube 2 has the same longitudinal direction, and a horizontally extending fin 3 is provided at a location where the fuel injected from the fuel supply nozzle 1 of the lowermost heat transfer tube 2 collides. The fin 3 is provided with a serrated cut.
[0016]
In such a configuration, the fuel injected from the fuel supply nozzle 1 collides with the fin 3 provided in the lowermost heat transfer tube 2 and is distributed almost uniformly in the layer along the extending direction of the fin 3. .
According to the present embodiment, the fin 3 extending in the horizontal direction is provided at the position where the fuel supplied from the fuel supply nozzle 1 of the lowermost heat transfer tube 2 collides, so that the fuel is extended in the extending direction of the fin 3. Can be evenly distributed along. In addition, the fuel is evenly distributed, improving combustion efficiency and avoiding the burning of unburned parts in freeboards and cyclones, and reducing the generation of a reducing atmosphere in the vicinity of the bottom heat transfer tube. Thus, corrosion of the heat transfer tube can be prevented. Furthermore, by providing the fin 3 with a sawtooth-shaped cut, it is possible to reduce the thermal stress caused by the metal temperature difference generated between the tip portion and the root portion of the fin 3.
[0017]
In the present embodiment, the right heat transfer tube 2 across the position of the fuel supply nozzle 1 has a fin 3 extending in the right direction, and the left heat transfer tube 2 has a fin 3 extending in the left direction. 2 is preferably provided with heat transfer tubes 3 extending in both the left and right directions. Thereby, even if the arrival position of the fuel injected from the fuel injection nozzle changes, the fuel can be evenly distributed along the extending direction of the fins 3 provided in each heat transfer tube 2.
[0018]
In this embodiment, when the arrival position of the fuel injected from the fuel supply nozzle 1 greatly changes due to load fluctuations, the attachment width L of the entire fin 3 in FIG. 1 is increased or illustrated in FIG. Thus, it is preferable to make the attachment width L of the fin 3 wider as the heat transfer tube is closer to the fuel injection position of the fuel supply nozzle 1. As a result, even if the sprayed fuel arrival position changes, the fuel collides with the fins 3 and uniform distribution can be ensured.
[0019]
In a present Example, it is preferable that the attachment angle to the heat exchanger tube of the fin 3 is 0 to 45 degree | times with respect to a horizontal line or a horizontal line. Thereby, the uniform distribution of the fuel is further improved.
In this embodiment, a dummy tube (stainless steel tube) may be arranged as a part of the heat transfer tube, and a dummy tube group may be used instead of the lowermost heat transfer tube group. When the heat transfer tube is an evaporator tube with a low internal fluid temperature, carbon steel or low alloy steel can be used as the fin material. However, when fins are provided on the dummy tube, the fins are not cooled by the internal fluid. The fin temperature becomes high as well as the in-layer temperature. Therefore, it is preferable to use high chromium steel fins, for example. In this case, since the temperature difference between the fin tip portion and the welded portion can be ignored, it is possible to eliminate the fin incision.
[0020]
In the present embodiment, the heat transfer tube or dummy tube (hereinafter simply referred to as a heat transfer tube) to which the fins are attached is not limited to the lowermost one, but the lowermost heat transfer tube group and the upper portion adjacent to the lower heat transfer tube group. It can also be provided in the heat transfer tube. Thus, providing fins not only on the lowermost heat transfer tube but also on the upper heat transfer tube is effective when the length of the fin is limited. In other words, fluidized bed boilers have a heat transfer effect due to the contact of not only gas but also fluidized medium, and therefore generally have a larger external heat transfer coefficient than pulverized coal-fired boilers, etc., and heat transfer surface load per unit area Also grows. Therefore, the tip temperature of the fin tends to increase, so the length of the fin may not be longer than a certain value for reasons such as the material use limit temperature. In such a case, not only the bottom stage but also the upper heat transfer tube. It is effective to provide fins.
[0021]
In the fluidized bed boiler apparatus, bubbles are combined and grow between the diffuser plate and the lowermost heat transfer tube, and become larger. Therefore, since the lowermost heat transfer tube is susceptible to wear due to bursting of bubbles, the distance from the diffuser plate to the lowermost heat transfer tube is made as short as possible to suppress bubble growth, and the lowermost heat transfer tube has an anti-wear cover. However, the present invention can also be applied to a heat transfer tube covered with such a cover.
[0022]
5-7 is explanatory drawing which shows the other Example of this invention using the heat exchanger tube covered with the cover for abrasion prevention instead of the heat exchanger tube of the lowest stage of Example 1, FIG. FIG. 6 is an explanatory view of a lowermost heat transfer tube to which a wear prevention cover to which the present invention is applied is attached, FIG. 6 is an explanatory view when fins are provided on the cover of FIG. 5, and FIG. 7 is a VII-VII direction of FIG. FIG. In FIG. 5, the heat transfer tube 2 is covered with a wear-preventing cover 5 in which the pipe material is divided into two in the vertical direction, and a metal 6 is welded and fixed to the contact portion of the cover 5. When the fin 3 is attached to the heat transfer tube 2 covered with such a wear prevention cover 5, the fin 3 is used in place of the above-described cover 6 in FIG. 5, and the fin 3 is divided into the above half for wear prevention. It is attached by welding to the contact portion of the cover 5.
[0023]
According to this embodiment, the fins extending in the horizontal direction are provided at the locations where the fuel supplied from the fuel supply nozzle 1 of the lowermost heat transfer tube 2 covered with the wear prevention cover 5 collides. As in the example, the fuel can be uniformly distributed along the extending direction of the fins 3.
In the present embodiment, as shown in FIG. 7, it is preferable to make a hole in a part of the cover 5 and to perform non-rotating welding (plug welding) of the cover 5 to the heat transfer tube 2. As a result, the cover 5 and the fins 3 can be prevented from rotating or shifting with respect to the heat transfer tube 2.
[0024]
In the present embodiment, since the fin attached to the cover 5 is difficult to be cooled by the heat transfer fluid, it is preferable to use high chromium steel as the fin material. In addition, since a temperature difference may occur between the welded portion of the fin 3 to the cover 5 and the tip of the fin 3, it is preferable to use a fin having a sawtooth cut as the fin 3.
8 to 10 are explanatory views showing another embodiment of the present invention in which the fuel injection direction of the fuel supply nozzle 1 of the embodiment 1 is perpendicular to the longitudinal direction of the heat transfer tube 2, and FIG. The figure which shows the principal part seen from the direction, FIG. 9 is the IX-IX arrow direction sectional drawing of FIG. 8, FIG. 10 is the XX arrow direction sectional drawing of FIG. In the figure, fins 3 are attached to the heat transfer tube 2 in opposite directions on the left and right sides of the fuel supply nozzle 1 with respect to the fuel injection direction.
[0025]
According to this embodiment, the fins 3 are attached to the left and right sides of the fuel supply nozzle 1 in the opposite direction, so that the fuel that has collided with the lowermost heat transfer tube 2 is uniformly diffused before and after the injection port of the fuel supply nozzle. Can be distributed.
In the present invention, there is provided a space for temporarily storing part or all of the fuel that is injected from the fuel nozzle and ascends the fluidized bed together with the fluidized air and the fluidized medium, and the stored fuel is supplied regardless of the ascending position. You may provide the fuel uniform distributor (distributor) which can discharge | emit uniformly in each direction.
[0026]
11 is an explanatory view showing another embodiment of the present invention, FIG. 12 is an enlarged view of a main part of FIG. 11, and FIG. 13 is a longitudinal sectional view of FIG. 11 and 12, a cylindrical member 114 as a central member having an upwardly convex shape is formed at a position where the fuel injected from the fuel injection nozzle 111 is located below the heat transfer tube 112. A distributor having a wing-like member 115 as an outer peripheral member having an upwardly inclined wall surface provided along an outer peripheral portion of the lower end, and a communication pipe 116 provided on the upper wall surface of the cylindrical member 114 and opening into the upper space. 117 is provided. In FIG. 13, the communication pipe 116 is inserted to the inside of the hollow cylindrical member 114, and the lower end thereof opens at a substantially intermediate portion in the height direction of the cylindrical member 114.
[0027]
In such a configuration, the fuel injected from the fuel supply nozzle 111 becomes a mixture of the air rising in the fluidized bed and the fluidized medium (BM), and as shown by an arrow 118 in FIG. 13, a hollow cylindrical member 114 reaches a space portion 119 and a part of the space portion 119 exits upward from the lower opening 120 of the communication pipe 116. At this time, since the opening 120 is smaller than the opening cross-sectional area of the space portion 119 of the hollow cylindrical member 114, the amount of entering the opening 120 is larger than the amount of the opening 120 coming out upward from the space portion 119. When the mixture stays in the portion 119 and the retention capacity becomes larger than the volume of the space portion 119, the mixture moves the joint 122 between the wing member 115 and the cylindrical member 114 as shown by an arrow 121 in FIG. It moves slightly so as to reach the lower side of the inclined surface of the wing member 115. At this time, since the lower side surface of the wing-like member 115 is inclined upward, the overflowing mixture moves in the outer peripheral direction according to the movement of the fluidized air from the lower side in the outer peripheral direction. Since the overflow of the mixture similarly occurs at any position of the joint 122, the mixture is evenly distributed to any position in the circumferential direction of the wing member 115.
[0028]
According to the present embodiment, the distributor 117 is injected from the fuel supply nozzle 111 and forms a hollow cylinder 119 that temporarily stores part or all of the fuel rising up the fluidized bed together with the fluidized air and the fluidized medium. By providing the wing-like member 115 having the wall-like member 114 having the wall surface inclined upward along the outer periphery of the lower end thereof, the fuel flow rising from below is located at any position of the lower opening end 123 of the cylindrical member 114. Even if it rises, it is once stored in the space part 119 and then flows out so as to overflow from the joint part 122 between the cylindrical member 114 and the wing-like member 115, so that it can be uniformly dispersed regardless of the ascending position. it can.
[0029]
In the present embodiment, air mainly stays in the space above the lower opening 120 of the communication pipe 116 of the cylindrical member 114, and the air rises from below and enters the space. Since the inflowing and overflowing air passes upward through the opening 120 as indicated by an arrow 124 in the figure, the internal space 119 of the cylindrical member 114 is divided into an upper air layer and a lower solid component (BM + CWP) layer. While being separated and mainly letting air out of the mixture upward through the communication pipe 116, the fuel as a solid component can be moved along the lower surface of the wing member 115 from below to be uniformly distributed in the layers. In addition, by allowing some of the air to escape upward from the communication pipe 116, the fluidizing medium above the distributor 117 can be efficiently flowed.
[0030]
In the present embodiment, the size of the space portion 119 in which the fuel or the like is temporarily retained is large enough to cover the entire range in which the fuel injected from the fuel injection nozzle spreads under the influence of the injection speed and the fluidizing medium. It is preferable to do. As a result, regardless of the rising position or spread of the fuel supplied from the fuel supply nozzle 111, the fuel can be uniformly distributed in the layer after being temporarily stored in the space 119.
[0031]
When the present invention is applied to a pressurized fluidized bed boiler apparatus, a refractory material is arranged on the inner surface of the pressure vessel to constitute a furnace having a hollow portion, and from the water tube group so as to fix the refractory material of the furnace. It is preferable to have a structure in which a water cooling wall is provided and the pressure inside the furnace is borne by the pressure vessel via the water cooling wall and the refractory material.
FIG. 14 is an explanatory view showing another embodiment of the present invention, and FIG. 15 is a cross-sectional view taken along the line XV-XV in FIG. In FIG. 14, the refractory material 143 is disposed so as to form a fluidized bed boiler furnace 142 in the pressure vessel 141, and as shown in FIG. 15, a group of water tubes 144 are arranged on the surface of the refractory material 143. The upper and lower ends of the water pipe 144 group are connected to a header 145 to form a water cooling wall, and the water cooling wall is supported by being suspended from the upper part of the pressure vessel 141 via a sling bolt 146 and is attached to the lower end thereof. A gap for absorbing the thermal elongation of the water-cooled wall is provided. In addition, a dispersion plate 149 having a plurality of air nozzles 148 is disposed at the bottom of the furnace 142, and the heat transfer tube 150 and the fuel supply nozzle 151, as well as the heat transfer tube 150 and the fuel supply nozzle 151 are arranged in the fluidized bed 147. A distributor 152 having the same configuration as that of the above embodiment is disposed therebetween.
[0032]
In such a configuration, the fuel sprayed from the fuel supply nozzle 151 collides with the distributor 152 and is uniformly distributed in the furnace 142 as in the above embodiment.
According to the present embodiment, the refractory material 143 is disposed so as to form the fluidized bed furnace 142 in the pressure vessel 141, and the water tube 144 group is arranged on the surface of the refractory material 143. Since the pressure of the combustion gas is transmitted to the pressure vessel 141 via the refractory material 143 and is borne only by the pressure vessel 141, a water-cooled wall back stay is not required. Further, the heat energy of the high-temperature combustion gas is suppressed by the refractory material 143 and is efficiently absorbed by the water-cooled wall, so that the thermal efficiency is improved. Further, by changing the thickness of the refractory material 143, the surface temperature of the pressure vessel 141 can be adjusted, and the plate pressure of the pressure vessel can be reduced and the size can be reduced.
[0033]
In this embodiment, the water-cooled wall has a function of preventing dropout due to thermal contraction of the refractory material 143.
In this embodiment, the water cooling wall support structure may be a self-supporting structure. In this case, it is preferable to fix the lower header 145 and provide a gap between the upper header 145 and the refractory 143 in consideration of the upward thermal expansion.
[0034]
In this embodiment, the water cooling wall is not composed of a plurality of single pipes, and as shown in FIG. 16 as sectional views (i) to (iii), respectively, the same applies to an unsealed structure in which the furnace pressure does not act directly. The effect is obtained.
In addition, the pressure vessel structure demonstrated in FIGS. 14-16 is applicable also to a general pressurized fluidized bed boiler apparatus.
[0035]
In the present invention, when a plurality of heat transfer tube groups are arranged in the fluidized bed, the interval between the heat transfer tube groups is preferably 800 mm or less, and the volume ratio of the heat transfer tube groups is 12% or more. It is preferable that This is the same when a dummy tube is used as a part of the heat transfer tube group, or when a dummy tube group is used as the lowermost tube group.
[0036]
The principle of the present invention will be described with reference to FIGS.
18 shows the relationship between the distance (interval) from the air nozzle and the strain generated by the collision of the fluidizing medium when a sensor having a strain gauge attached to the base of the spring steel plate shown in FIG. 17 is inserted into the fluidized bed. FIG. In FIG. 18, it can be seen that as the distance from the air nozzle increases, the generated strain increases and the flow state becomes intense. This is because the bubbles in the fluidized bed coalesce and increase in the ascending process.
[0037]
In FIG. 18, the maximum strain at the position of 800 mm is about 1.4 times the maximum strain at the position of 600 mm from the air nozzle, and the generated strain ε is the collision energy 1 / 2ρV of the fluid medium. ² Since it is proportional to (ρ: bulk density of the fluid medium, V: collision velocity of the fluid medium), it is 1.4 when compared with the collision velocity of the fluid medium. ^0.5 = 1.18 (times). Also, since the wear rate of the heat transfer tube is proportional to the 3.5th power of the collision rate, the wear rate is 1.18. ^3.5 = 1.8 (times).
[0038]
FIG. 19 shows the relationship between the distance from the air nozzle to the lowermost heat transfer tube and the wear thinning amount of the heat transfer tube. In FIG. 19, it can be seen that the wear thinning amount of the heat transfer tube increases exponentially as the distance increases. Therefore, in the present invention, it is preferable that the distance from the air nozzle to the lowermost heat transfer tube and the interval between the heat transfer tube groups be 800 mm or less.
[0039]
FIG. 20 shows the strain gauge using a sand bed having an average particle size of 0.5 mm as a fluidized medium in a fluidized bed model having a furnace width of 1.2 m, a furnace depth of 0.6 m, and a fluidized bed height of 0.65 m without a heat transfer tube. It is a figure which shows the result of having inserted in the fluidized bed height vicinity of the center of a furnace depth direction, and measuring the maximum and minimum distortion. In the figure, it can be seen that a downward flow is generated where the absolute value of the minimum strain exceeds the maximum strain, and two circulating flows are generated in the bed. Further, in a fluidized bed having a square or circular cross section of the furnace, the central part of the layer rises and the peripheral part flows downward, and bubbles are concentrated in the fluidized bed without the heat transfer tube, so that the fluid state becomes extremely intense. In order to suppress such a flow state, it is necessary to arrange the heat transfer tubes uniformly and densely.
[0040]
FIG. 22 shows the effect of crushing bubbles by increasing the number of stages in a tube row having a horizontal pitch of 50 mm and a tube outer diameter of 27.2 mm, and arranging a heat transfer tube group 600 mm above the air nozzle 211 as shown in FIG. The results of the investigation are shown. In FIG. 22, since the generated strain hardly changes when the number of stages of the heat transfer tube group is about 8 or more, it can be seen that when the number of stages is about 8 or more, the bubbles are sufficiently crushed by the heat transfer tube and do not become larger.
[0041]
As a method for arranging the heat transfer tubes, for example, as shown in FIG. 23, a staggered arrangement or an in-line arrangement can be mentioned. In FIG. 24, a strain gauge is attached between the tubes of the in-line arrangement tube group. The result of having measured the distortion which changed the volume ratio of the heat exchanger tube which occupies in a fluidized bed by inserting a sensor and changing the outer diameter of a heat exchanger tube is shown. In FIG. 24, it can be seen that the generated strain does not change when the volume ratio of the heat transfer tube is about 12% or more. Therefore, in the present invention, the volume ratio of the heat transfer tube is preferably set to 12% or more.
[0042]
That is, in the present invention, the interval between the air nozzle and the tube group and the interval between the tube group and the tube group are set to 800 mm or less, the volume ratio of the tube in the heat transfer tube or the dummy tube group is set to 12% or more, It is preferable to employ a heat transfer tube arrangement in which the number of stages is eight or more. Note that this heat transfer tube arrangement structure can also be applied to a general fluidized bed boiler apparatus.
[0043]
FIG. 25 is an explanatory diagram showing another embodiment of the present invention. In this fluidized bed boiler apparatus, the lowermost heat transfer tube group 254 is arranged 600 mm above the air nozzle 253 of the air distribution plate 252, and a total of four heat transfer tube groups 254 are arranged on each 600 mm apart from each other. It is. In the heat transfer tube group 254, heat transfer tubes having an outer diameter of 27.3 mm were arranged in-line, and the pitches of the tubes shown in FIG. 23 were Sh = 50 mm and Sv = 50 mm. The volume ratio of the heat transfer tube group 254 is 23.2%. Although not shown, a protector that divides a stainless steel tube with an outer diameter of 34 mm and a thickness of 3.2 mm is attached to the lowermost tube of the lowermost heat transfer tube group 254 to prevent wear of the heat transfer tube. The protector is provided with fins for uniformly distributing the fuel shown in FIG.
[0044]
According to the present embodiment, the fuel can be uniformly dispersed by providing the fins extending in the horizontal direction in the protector of the lowermost heat transfer tube. Further, since the distance between the air nozzle 253 and the lowermost heat transfer tube group 254 and the interval between the heat transfer tube groups are set to 600 mm, the heat transfer tube groups 254 crush bubbles to inhibit the growth. Wear of the heat transfer tube can be reduced. Furthermore, since the heat transfer tubes are composed of four tube groups, there is an advantage that the load can be easily changed in a step response such as boiler loads of 100%, 75%, 50%, and 25%.
[0045]
In the present embodiment, the lowermost heat transfer tube group 254 may be a dummy tube (stainless steel tube) tube group. If the lowermost tube group is a heat transfer tube, heat is taken away by the heat transfer tube, which causes a problem that it takes time to start up.However, by using an uncooled dummy tube as the lowermost tube group, the fuel is The start-up time can be shortened because of no cooling.
[0046]
In this embodiment, the fluidized bed boiler is started up by setting the fluidized bed height below the lowermost tube, raising the temperature to around 650 ° C. with a hot air furnace, then introducing CWP (Coal Water Paste), and then increasing the fluidized bed height. Raised gradually and started.
FIG. 26 is an explanatory view showing still another embodiment of the present invention. In this fluidized bed boiler apparatus, a dummy tube (stainless steel tube) tube group having an outer diameter of 27.2 mm is arranged at a position 600 mm from the air nozzle 263 of the air distribution plate 262, and the lowermost dummy tube is shown in FIG. A similar dummy tube group 267 is disposed above the dummy tube group by a distance of 600 mm in the center of the tube, and a heat transfer tube group 264 is disposed on the dummy tube group by a distance of 600 mm from the center of the tube. . The heat transfer tubes and the dummy tube groups were arranged in-line, and the tube pitches shown in FIG. 23 were Sh = 50 mm and Sv = 50 mm.
[0047]
According to the present embodiment, the fuel can be uniformly dispersed by providing the fins in the lowermost dummy tube. Further, by setting the distance between the dummy tube groups 267 or between the dummy tube group 267 and the heat transfer tube group 264 to 600 mm, wear of the heat transfer tube and the dummy tube can be prevented. Furthermore, by arranging the heat transfer tube group 264 in the upper part of the fluidized bed, load control can be performed without greatly changing the fluidized bed height, and a reduction in combustion efficiency at low loads can be avoided.
[0048]
In this embodiment, heat transfer tubes may be mixed in the dummy tube group 267 and dummy tubes may be mixed in the heat transfer tube group 264.
[0049]
【The invention's effect】
Claim 1 of the present application 2 According to the invention described in the above, at least the lowest heat transfer tube is in a horizontal direction at a position where fuel injected from the fuel supply nozzle and brought into contact with fluidized air comes into contact. And the left-right direction Since the injected fuel collides with the fin and diffuses, the fuel can be uniformly distributed in the fluidized bed. In addition, the combustion efficiency is improved and the generation of unburned parts is reduced, so there is no so-called afterburning in freeboards and cyclones, and there is no reducing atmosphere in the vicinity of the bottom heat transfer tube. Can be prevented.
[0050]
Also By providing serrated cuts on the fins, in addition to the effects of the above-described invention, thermal stress caused by a metal temperature difference generated between the tip portion and the root portion of the fin can be reduced. According to the invention described in claim 3 of the present application, the fuel injection direction of the fuel supply nozzle is the same as the longitudinal direction of the lowermost heat transfer tube, and the heat transfer tube on the right side on the plane sandwiches the plane position of the fuel supply nozzle. By providing a fin extending in the right direction, a fin extending in the left direction in the heat transfer tube on the left side, and a fin extending in the left and right directions in the center heat transfer tube, in addition to the effects of the above invention, fuel injection The fuel injected from the nozzles can be uniformly dispersed along the extending direction of the fins.
[0051]
Claims of the present application 3 According to the described invention, the heat transfer tube closer to the fuel injection position of the fuel supply nozzle has a wider fin mounting width, so that the arrival position of the fuel injected from the fuel injection nozzle changes in addition to the effects of the above invention. Can be dispersed evenly. Claims of the present application 4 According to the described invention, the heat transfer tube is arranged so that the fuel injection direction of the fuel supply nozzle and the longitudinal direction of the lowermost heat transfer tube are orthogonal to each other, and the fins of the heat transfer tube are sandwiched between the planar positions of the fuel supply nozzle. In addition to the effects of the present invention, the fuel injected from the fuel supply nozzle can be uniformly dispersed so as to diffuse before and after the injection port of the fuel supply nozzle. .
[0052]
Claims of the present application 5 According to the described invention, the heat transfer tube covered with the anti-wear cover is provided, and the anti-wear cover is provided with the fin, so that the fuel is supplied along the extending direction of the fin as in the above-described invention. It can be distributed evenly. Claims of the present application 6 According to the described invention, at the arrival position of the fuel injected from the fuel supply nozzle at the lower part of the heat transfer tube, the center member having an upwardly convex shape is provided along the outer periphery of the lower end of the center member. An outer peripheral member having a wall surface inclined upward, and an upper wall surface of the central member; Below the upper space of the fuel distributor and the upper wall surface of the central member By disposing a fuel distributor having a communication pipe that opens to the fuel supply nozzle, regardless of the rising position of the fuel injected from the fuel supply nozzle, Disperses the fuel evenly in the bed while mainly letting air out of the fuel mixture .
[0053]
Claims of the present application 7 According to the described invention, the center member having an upwardly convex shape, Cylindrical member And an outer peripheral member having an upwardly inclined wall surface extending obliquely upward provided along the outer periphery of the lower end of the central member. By using the wing-like member, the same effect as the above invention can be obtained. .
[0054]
Claims of the present application 8 According to the invention described in the above, the fluidized bed boiler apparatus is a pressurized fluidized bed boiler apparatus, the fluidized bed furnace is a pressure vessel, a refractory material disposed along the inner surface of the pressure vessel, and the refractory material. By having a water-cooled wall composed of a group of water tubes arranged on the surface so as to be fixed, a back stay of the water-cooled wall is not required, and the pressure vessel can be made compact.
[0055]
Claims of the present application 9 According to the invention described in (2), the distance between the fuel supply nozzle and the lowermost heat transfer tube and the interval between the heat transfer tube groups arranged in the fluidized bed are set to 800 mm or less, respectively. In addition, it is possible to reduce bubble wear by inhibiting bubble growth. Claims of the present application 10 According to the invention described in (2), by setting the volume ratio of the heat transfer tube group to 12% or more, it is possible to inhibit bubble growth and reduce wear of the heat transfer tubes, as in the above-described invention.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a main part of one embodiment of the present invention.
2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is an enlarged view of a main part of FIG.
FIG. 4 is a view showing a manner of attaching fins in one embodiment.
FIG. 5 is a view showing a heat transfer tube to which a wear prevention cover to which the present invention is applied is attached.
6 is an explanatory view when fins are attached to the cover of FIG. 5;
7 is a VII-VII direction view of FIG. 6;
FIG. 8 is a diagram showing a main part of another embodiment of the present invention.
9 is a sectional view taken along the line IX-IX in FIG.
10 is a cross-sectional view in the direction of arrows X-X in FIG. 8;
FIG. 11 is a diagram showing a main part of another embodiment of the present invention.
12 is a partially enlarged view of FIG.
13 is a longitudinal sectional view of FIG.
FIG. 14 is a sectional view showing an essential part of another embodiment of the present invention.
15 is a cross-sectional view in the direction of arrows XV-XV in FIG. 14;
FIG. 16 is a view showing a manner of attaching a water cooling wall in one embodiment.
FIG. 17 is an explanatory diagram of a strain gauge.
FIG. 18 is a diagram showing the relationship between the distance from the air nozzle and the generated distortion.
FIG. 19 is a diagram showing the relationship between the distance from the air nozzle to the lowermost heat transfer tube and the wear thinning amount of the heat transfer tube.
FIG. 20 is a diagram showing a measurement result of a fluid state of a fluid medium in a fluidized bed without a heat transfer tube.
FIG. 21 is a diagram showing the relationship between the heat transfer tube and the air nozzle when measuring the relationship between the number of heat transfer tube stages and the generated strain.
FIG. 22 is a diagram showing the relationship between the number of heat transfer tube stages and the generated strain.
FIG. 23 is an explanatory diagram showing a volume ratio of a heat transfer tube.
FIG. 24 is a diagram showing the relationship between the volume ratio of a heat transfer tube and the generated strain.
FIG. 25 is an explanatory diagram showing another embodiment of the present invention.
FIG. 26 is an explanatory diagram showing another embodiment of the present invention.
FIG. 27 is an explanatory diagram of a conventional technique.
FIG. 28 is a diagram showing a positional relationship between a fuel supply nozzle and a distributor according to the prior art.
FIG. 29 is a diagram showing a positional relationship between a fuel supply nozzle and a distributor according to the prior art.
FIG. 30 is a diagram showing a positional relationship between a fuel supply nozzle and a distributor according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel supply nozzle, 2 ... Heat transfer tube, 3 ... Fin, 4 ... Welding part, 5 ... Cover, 6 ... Cover, 7 ... Plug welding, 111 ... Fuel supply nozzle, 112 ... Heat transfer tube, 114 ... Cylindrical member , 115 ... Wing-like member, 116 ... Communication pipe, 117 ... Distributor, 118 ... Arrow indicating fuel flow, 119 ... Space portion, 120 ... Lower opening of the communication pipe, 121 ... Arrow indicating fuel flow, 122 ... Cylindrical Joining part of the wing-like member and the wing-like member, 123 ... lower open end of the cylindrical member, 124 ... an arrow mainly indicating the flow of air, 141 ... a pressure vessel, 142 ... a furnace of a fluidized bed boiler, 143 ... a refractory material, 144 ... Water pipe, 145 ... heading, 146 ... sling bolt, 147 ... fluidized bed, 148 ... air nozzle, 149 ... dispersion plate, 150 ... heat transfer pipe, 151 ... fuel supply nozzle, 152 ... distributor, 2 DESCRIPTION OF SYMBOLS 1 ... Air nozzle, 212 ... Heat transfer tube, 251 ... Side wall, 252 ... Air dispersion plate, 253 ... Air nozzle, 254 ... Heat transfer tube group, 255 ... Support tube, 256 ... CWP nozzle, 261 ... Side wall, 262 ... Air dispersion plate 263 ... Air nozzle, 264 ... Heat transfer tube, 265 ... Support tube, 266 ... CWP nozzle, 267 ... Dummy tube.

Claims (10)

Fluidized bed furnace, diffuser plate provided at the bottom of the fluidized bed furnace, fluidized bed formed by fluidized air supplied from the diffuser plate, and fuel supply nozzle for supplying fuel to the fluidized bed And a heat transfer tube group provided at the upper part of the fuel supply nozzle, and is injected from the fuel supply nozzle of at least the lowest heat transfer tube of the heat transfer tube group into fluidized air. A fin extending in the horizontal direction is provided at the place where the accompanying fuel comes into contact, and the fuel injection direction of the fuel supply nozzle is the same as the longitudinal direction of the lowermost heat transfer tube, and the plane position of the fuel supply nozzle is sandwiched between them. The right heat transfer tube on the plane is provided with a fin extending in the right direction, the left heat transfer tube is provided with a fin extending in the left direction, and the center heat transfer tube is provided with a fin extending in both the left and right directions. When That the fluidized bed boiler system.  The fluidized bed boiler apparatus according to claim 1, wherein the fin is provided with a sawtooth cut. The fluidized bed boiler apparatus according to claim 1 or 2 , wherein the heat transfer tube closer to the fuel injection position of the fuel supply nozzle has a wider fin mounting width. The heat transfer tubes are arranged so that the fuel injection direction of the fuel supply nozzle and the longitudinal direction of the lowermost heat transfer tube are orthogonal to each other, and the fins of the heat transfer tube are alternately reversed left and right across the plane position of the fuel supply nozzle. The fluidized bed boiler device according to any one of claims 1 to 3, wherein the fluidized bed boiler device is attached to the fluidized bed boiler device. The fluidized bed boiler apparatus according to any one of claims 1 to 4 , wherein the lowermost heat transfer tube is covered with an anti-wear cover, and the fin is provided on the anti-wear cover. . Fluidized bed furnace, diffuser plate provided at the bottom of the fluidized bed furnace, fluidized bed formed by fluidized air supplied from the diffuser plate, and fuel supply nozzle for supplying fuel to the fluidized bed And a heat transfer tube group provided in the fluidized bed at the upper part of the fuel supply nozzle, in the fluidized bed boiler device, the upper part of the fuel transfer nozzle at the lower position of the heat transfer pipe A convex-shaped central member, an outer peripheral member having an upwardly inclined wall surface provided along an outer peripheral portion of a lower end of the central member, and an upper space of the fuel distributor provided on an upper wall surface of the central member And a fluid distributor having a communication pipe having an end opening below the upper wall surface of the central member . The upwardly convex central member is a cylindrical member , and the outer peripheral member having the upwardly inclined wall surface is a wing-like member that extends obliquely upward, provided along the outer peripheral portion of the lower end of the central member . The fluidized bed boiler apparatus according to claim 6 , wherein the fluidized bed boiler apparatus is provided. The fluidized bed boiler device is a pressurized fluidized bed boiler device, and the fluidized bed furnace is configured to fix a pressure vessel, a refractory material disposed along an inner surface of the pressure vessel, and the refractory material. The fluidized bed boiler device according to any one of claims 1 to 7 , further comprising a water cooling wall formed of a group of water tubes arranged on the surface. Claim 1-8, characterized in that the spacing and the spacing between which is disposed the fluidized bed heat exchanger tubes tube bank mutual between the fuel supply nozzle and the lowermost heat transfer tube, respectively and 800mm or less The fluidized bed boiler apparatus described in 1. The fluidized bed boiler apparatus according to claim 9 , wherein a volume ratio of the heat transfer tube group is set to 12% or more.

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