JPS6176801A - Fluidized bed device with load corresponding type heat transfer tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fluidized bed apparatus, and particularly to a fluidized bed apparatus in which consideration is given to the structure of the heat exchanger tubes in the bed so as to improve the load response as a boiler apparatus.

<Prior art and its problems> In a fluidized bed, fuel and γIU dynamic medium are mixed 4; b. Combustion is performed while stirring, so a very wide range of materials can be used as fuel, so it is used as a variety of combustion devices. It is also widely used as a waste incineration chamber 71''.Also, since the heat transfer coefficient within the layer is extremely high, we also provide a device with heat transfer tubes placed within the layer in order to effectively recover the heat within the layer. and has been put into practical use.

Of these, No. 2 South shows the one used as a fluidized bed boiler. Air A flowing into the wind box 8 of the boiler body flows into the bed via the distribution plate 11 and fluidizes this medium to form the fluidized bed 4. The fuel (for example, pulverized coal) F supplied through the pulverized coal pipe 6 is supplied to the fluidized bed 4 from the nozzle 9, is stirred together with the fluidized medium, and burns well. - Feed water heated on the boiler wall surface, which is the water tube wall constituting the blade body 1, enters the drum 2, and the steam discharged from the drum 2 descends the main steam pipe 3, enters the interlayer heat exchanger tube IO, and flows into the drum 2. The heat in the layer turns into superheated steam and is discharged from the system.

In this boiler installation, the intralayer heat transfer tubes are used not only as a superheater, but also as an evaporator and other functions.

Here, in fluidized bed combustion equipment, including the above-mentioned fluidized bed boiler, in order to maintain the combustion bed temperature, the fluidized bed gas theory, speed,
In other words, it is desirable to have a vehicle that maintains the temperature within the bed constant even when the amount of gas to be processed is changed.

As shown in the following equation, ζ no fj is the heat exchange between the moving bed and the intralayer heat transfer tube, q is the heat transfer coefficient hW1 between the layer and the heat transfer tube, M A is the layer temperature 'rb, and the interlayer heat exchanger tube surface temperature T'w is given by the number of glues.

q, = hwA (Tb Tw) As shown in Fig. 4, in the conventional intrabed heat exchanger tube, the relationship between the heat transfer coefficient hw and the gas flow rate U○ in the fluidized bed is as follows in the proper fluidization range: has the characteristic that is almost constant. Therefore, in order to keep the bed temperature constant, even if the amount of processing gas, that is, the amount of heat input to the fluidized bed, is changed, the heat V exchange rate q between the bed heat transfer tubes and the fluidized bed must be changed in order to keep the bed temperature constant. There is a need. For this purpose, since hw is constant, it is necessary to change the heat transfer surface depth A or the humidity difference (TbTw) between the fluidized bed and the intrabed heat transfer tube. but.

The temperature of the fluid inside the heat transfer tube and the temperature of the heat transfer tube cannot be changed freely due to the process9; usually, only the heat transfer area A can be changed in many cases. For example, in a fluidized bed boiler, methods to change the heat transfer surface quality A include the vero/titandown method, which uses bed expansion to change the immersion area of heat transfer tubes in the bed, and the cell division method, which divides the fluidized bed into several parts. However, in these methods, do the effects occur near the layer interface? ! ! (There are disadvantages such as wear of the tube and high cost of the control device for the divided fluidized bed.

If the Vero 7-Tay turndown method or the cell division method is not used, a significant drop in layer temperature cannot be avoided.

The heat transfer characteristics in the bed when the heat transfer tube shown in FIG. 3 is placed in the fluidized bed 4 are as shown in part (a) of FIG. /S ) /Furnace surface clearness (m')
It changes depending on the superficial velocity Uo (m/S) defined as . In the figure, reference numeral 12 indicates a fluidizing medium, and G indicates a gas rising within the layer.

If the superficial velocity UO is too low, the diffusion and mixing speed of the coal supplied into the fluidized bed 4 from the coal feed pipe 6 will be slow, and the mixing and contact with the air blown from the air distribution plate 11 will be insufficient, resulting in a decrease in combustion performance. . On the contrary, the sky tower law FJfU.

When is too large, the amount of unburned coal coming out from within the seam increases, and combustion performance also decreases in this case. Therefore, the speed t,
v [Jo has a 1-force diα range that is Fli iE, and is often continuously rotated at an ihMa that is 3 times to 6 times the fluidization start speed KI Umf of the sky column method K tJo, and as shown in Fig. 4. (As shown in part a1, in this operating range, the heat transfer coefficient within the bed is approximately constant around 1jji.In a fluidized bed boiler, it must be operated at a constant air ratio.

Boiler loads are proportional to each other. The relationship between superficial velocity Uo and boiler load temperature is shown in part (b) of Fig. 4.

(c) γ? It is shown in IX. When the bed temperature at 100% boiler load is 850°C, if a conventional type of bed heat exchanger tube without special measures is used as shown in Figure 3, the bed temperature at 70% boiler load will be 850°C. The lower limit layer temperature has fallen to 750°C, which is necessary to maintain performance, and further low-load V-shifting will result in a significant drop in combustion performance.

The temperature of the fluidized bed 4 is determined by the balance between the amount of heat input into the bed and the amount of heat absorbed by the intrabed heat exchanger tubes 10. However, with the conventional technology of intrabed heat exchanger tubes, even if the boiler load is lowered and the superficial velocity is lowered, the heat transfer coefficient remains approximately the same. Since it is constant, the amount of heat absorbed by the intralayer heat transfer tubes remains high. Therefore, when the load decreases, the bed temperature decreases rapidly, and as shown in J41a, the temperature decrease per 10% of the boiler load reaches about 33°C.

As described above, in the above-mentioned conventional boiler using heat transfer tubes in the bed, the temperature drop in the bed per unit load is large, and the users who use the steam generated by the boiler and the electric power using this steam are Due to the above circumstances, it is difficult to operate at a low load of 70% or less with a single bed, although it is necessary to widely control the load because the fuel supply is still unstable as in the case of using waste as fuel. There is a drawback.

As described above about combustion performance, even in fluidized bed boilers that perform in-furnace desulfurization using limestone as a depolarization agent, there is an appropriate bed temperature range, and even if the bed temperature is too low or too high, in-furnace desulfurization It is desirable to maintain a constant bed temperature as this will reduce performance.

OBJECTS OF THE INVENTION The purpose of the present invention is to eliminate the drawbacks of the prior art described above and to provide a fluidized bed apparatus that can be operated while maintaining a high anti-Gc ratio or ground motion ratio with little drop in bed temperature even during low load operation. There is something to do.

<Summary of the present invention> In short, non-invention is layered! The heat transfer coefficient can be changed approximately in proportion to the heat transfer tube speed around the tube.

Figure 5 shows a first embodiment of the present invention. code 10
This is an intrabed heat exchanger tube placed horizontally in a fluidized bed.

13 is for this level of education φ, ノ (certain all questions I for 10
The movement 1 through 6 is a longitudinally arranged cover. This cover is formed and arranged to cover the heat exchanger tube 10 asymmetrically with respect to the vertical plane 14, that is, its cross-sectional shape extends to one side 1011 (left side in the case of illustration) with the vertical plane as the center. However, the end edge portion 16b is configured to extend beyond the horizontal surface 15 and extend to the vicinity of the vertical surface 14. In the illustrated case, the angle between the ends M16a, Lbb of the cover and the central axis of the heat exchanger tube 10 is about 1800, and the cover 13 has a cylindrical shape cut in half. In the illustrated case, the right half of the vertical surface 14 is an open space, but it is of course possible to form an open space on the left half.

To explain the behavior of the medium in the above-mentioned heat exchanger tube groove structure with η' with reference to FIG. and [intralayer heat exchanger tube]
・It is Δ. Next, a fluidizing gas is supplied into the bed, and when the superficial velocity Uo becomes LTmf, the medium in the bed has a flow rJ,
However, as shown in FIG. 2(a), the medium in the space 16 remains stationary because the bubbles j4 of gas G rising in the layer are blocked by the cover 13, and sufficient fluidization is not provided. Maintain layers. Furthermore, as shown in (b), when the superficial velocity UO is increased by jW4, the scum G and flow energy are imparted to the space, and the i-forms infiltrate, forming a transferred layer of the medium, and finally in (c). Start rWj 1rj+ at the same time as the 111th minute of the hit.

In other words, the dark particles between the heat exchanger tube 10 and the cover 13 are empty towers, medium 1-'s 1; Begin to fluidize in various ways. As a result, Sky Near 7;! In the 7th case, the particles between the cover 13 and the intralayer heat exchanger tube 10 are in the 11th layer or the transition layer, so they were covered.
The 4 coefficient to 1/B is small, but with the addition of the reciprocal no, this part will smoothly become +Iij+, right? If the distance of the heat exchanger tube 1 () is 4 points, it will be proportional to the superficial velocity by 4 times. Preferably 0
．． I'm not sure if good results can be obtained by increasing the number from 5 times to 21 tones.

, Test Figure 10 shows the case where the inventors used a cover with the shape shown in Figure 5 [shown in diagram (a)] and the case where the inventors used glass spheres with an average particle size of 0.25 heads as the in-layer bullets [shown in diagram (a)]. The results of an experiment on the change in heat transfer coefficient with the conventional 3q body [: line, not shown as 1 (0)], which is not used at all, are shown. As is clear from the above, in the case of the present invention, the heat transfer coefficient and the superficial velocity are almost completely proportional.

In the case of the Jyogo type, the superficial velocity is the fluidization start velocity Um
When f is reached, 7161 internal transmission; (・The surroundings of θ are almost IO
At 2 o'clock, the flow 111j1 was changed to fji4, and the heat transfer section between the inner heat transfer tube and the inner layer medium [] and the gas J, my father, Y
As shown in ≦r q+ to>, it increases to @, θ/f, and remains constant thereafter. In other words, the amount of slump absorbed during low angle loads increases, and the load control range has to be narrowed as described above.

FIGS. 1 fa) and fb) show the optimal state of the embodiment shown in FIG.

That is, as shown in 11th: A + (a), the vertical plane 14 that extends through the middle of the heat exchanger tube and below the center of the heat exchanger tube 14a is the reference plane, and is 60 degrees to the right. 175° to the left from the vertical plane while slanting and colliding with the center of the transfer pipe.
° 1 and cover the area sandwiched by the plane passing through the center of the heat exchanger tube, or turn the left and right sides as shown in Figure 1 (b) and connect the plane that passes through the center of the heat exchanger tube and the vertical plane. 60 to the left from
It is formed and arranged so as to cover a range 1'L between a plane extending 175° to the right from the vertical plane and passing through the center of the heat exchanger tube.

Fold 11. +a;-II: This shows the characteristics of the fluidized bed boiler using the present invention (shown in diagrams A and B in the figure), but when comparing the N temperature at 70% boiler load, it is compared with the conventional technology Iil:i. In the case of an intralayer heat transfer tube, the temperature decreases to 750°C [see part (c) of the same figure], but with the intralayer heat transfer tube according to the present invention, the temperature can be kept at 830°C. That is, 7i?
・(The width of the layer temperature drop per 10% wheeler load was as high as 33°C, but by using the in-layer heat exchanger tube according to the present invention, the layer temperature drop width per wheeler load of 1()9) was reduced to 7 degrees Celsius.
℃ or less, and based on the decrease in layer temperature, it is possible to minimize the deterioration of the evaporation performance and escape performance.

;r<6 fnI indicates the second embodiment. In this embodiment, the cover is plum-shaped so that the cross section is in the shape of an abbreviated character, as shown by the reference numeral 20. By forming the cover in this way, the cover can be formed by bending the flat plate at a substantially right angle, so that manufacturing costs can be kept low.

FIG. 7 shows the third embodiment. The cover 21 has a cylindrical shape, encases the heat exchanger tube 10 therein, and is arranged so that the central axes of both cover substantially coincide. This embodiment is also a modification of the first embodiment, and in the first embodiment, the open space is above a porous section in which a large number of small holes 22 are formed. By forming it in this way, the fluidization of the medium in the space IG becomes slower than in the case of the first case, 7311,
This is particularly effective for equipment that is frequently operated in high-load areas.

FIG. 8 shows a fourth embodiment. The cover 23 has a curved cross section in substantially the same manner as in the second embodiment, but is arranged so that the bent portion is located on the vertical plane 14, that is, in a V shape. One of these II! A small hole 24 is made in II iM to form a perforated plate part.

In the above embodiments, the material and quality of the cover is preferably a heat-resistant and abrasion-resistant material, and in addition to the same metal material forming the heat exchanger tube 10, ceramics or the like may also be used. good. Also, the shape of the cover 1 is also 12 (not limited to 1, but the effect is hehe - \)
It may be a square plate that lowers the cover, or the cover itself may be formed by distributing small-diameter water l〒.

tlI-1,', deyo pregnancy; bui' riinai yukikaku pipe's communication system and kuto ren) tsutsumi and hori-ri-hakama are ratios ('111 shi) and can be changed. Since it is possible, low f] In the layer i of Xun time, 7.
? Buying time: l+(l ?i'!I
The range can be expanded.

1 simple explanation of j+, I'l on the 1st side of the tree (Fig. 1 faJ and tb) is the optimal state during felling of the 10000 yen fruit, 9. Flow, a system diagram of a moving bed boiler, No. 31 ¥1 is a cross-sectional diagram of a conventional layer transmission,
Figure 4 shows a conventional flow and noise boiler. A diagram showing the relationship between the transmission coefficient, boiler load, layer temperature, and superficial velocity. Figures 5 to 8 are horizontal views of the internal transmission pipe and cover; 1, Figure 6 is the second one.

FIG. 7 shows the third embodiment, FIG. 8 shows the fourth embodiment, and FIGS. 9(a) to 9(c) are cross-sectional views of the heat transfer tube showing changes in the state of the medium in the heat transfer tube structure of the present invention. , Figure 10 shows the heat transfer coefficient and superficial velocity of the conventional device and the device of the present invention.
．． The diagram showing the 1st factor, Figure 11, is the heat transfer coefficient.

FIG. 2 is a diagram showing a comparison between a conventional device and the device of the present invention in the relationship between boiler load 1 temperature and superficial velocity.

4... iXr, 9rJ) layer 10... In-layer heat exchanger tube 13, 20.21.23''・Covered 1... Vertical surface 16... Space part 22.24
...Small hole (0) (b) 4a Fig. 2 Fig. 3 (O Fig. 7 Fig. 8 Fig. 9 Fig. 10

Claims (1)

[Claims] 1. In a device in which heat transfer tubes are disposed within a fluidized bed and heat generated within the fluidized bed is recovered, a cover is disposed in the longitudinal direction of the intrabed heat transfer tube through a certain space, and the cover is 1. A load-adaptive fluidized bed device with heat transfer tubes, characterized in that the heat transfer coefficient is made almost proportional to the superficial velocity by changing the filling state of the medium in the space between the heat transfer tubes and the heat transfer tubes. 2. The load-adaptive fluidized bed apparatus with heat transfer tubes according to claim 1, wherein the cover is arranged asymmetrically with respect to a vertical plane passing through the center axis of the heat transfer tubes. 3. The load-responsive type according to claim 1 or 2, characterized in that the cover is formed to have an arcuate cross-section, and an open space is formed on one side of the vertical plane. Fluidized bed equipment with heat transfer tubes. 4. The load-adaptive type according to claim 1 or 2, wherein the cover is formed to have a substantially L-shaped cross section, and is positioned so that one surface of the cover is substantially perpendicular to the vertical plane. Fluidized bed equipment with heat transfer tubes. 5. The cover is formed into a cylindrical shape that surrounds and coaxially surrounds the intralayer heat exchanger tube, and a plurality of small holes are formed in a part of the side surface of the cover, or 2. The fluidized bed device with load-adaptive heat transfer tubes according to item 2. 6. The cover is formed to have a substantially V-shaped cross section, and the bent portion is arranged so as to be located approximately in a vertical plane that includes the axis of the heat exchanger tube, and a plurality of small holes are bored in one side of the cover. A fluidized bed apparatus with a load-adaptive heat exchanger tube according to claim 1 or 2, characterized in that: 7. About the vertical plane passing through the center axis of the heat exchanger tube, about 60 degrees with respect to one space partitioned by this vertical plane, based on the vertical plane located below the center axis of the heat exchanger tube,
The load-responsive type according to any one of claims 1 to 6, characterized in that the shape of the cover is determined so that the cover is located in a section expanded by about 175 degrees with respect to the other space. Fluidized bed equipment with heat transfer tubes. 8. Set the distance between the cover and the heat exchanger tube to 0.0 of the heat exchanger tube diameter.
8. A fluidized bed apparatus with load-adaptive heat transfer tubes according to any one of claims 1 to 7, characterized in that the load is between 1 and 5 times. 9. Set the distance between the cover and the tube body to 0.0 of the heat exchanger tube diameter.
9. A fluidized bed apparatus with load-adaptive heat exchanger tubes according to claim 8, characterized in that the load is between 5 times and 2 times. 10. The fluidized bed device with a load-responsive heat exchanger tube according to any one of claims 1 to 9, wherein the cover is made of a material having wear resistance and heat resistance, such as ceramics.