JP4540272B2 - Fluidized bed equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluidized bed apparatus, and more particularly to a measuring facility that does not cause material fatigue with a measuring member for a state quantity in a fluidized bed.
[0002]
[Prior art]
In a fluidized bed, a gas such as air is blown into a layer in which particles are stacked, and the entire layer is fluidized. Fuel is supplied into the fluidized bed and burned. It is a furnace.
[0003]
Fluidized bed combustors are widely used in power generation systems, waste treatment plants, chemical plants, etc. because of the long residence time of fuel and the ability to use generated heat with high efficiency by using a fluidized bed with a large heat capacity. Yes.
[0004]
As an example of the latest technology using a fluidized bed combustor, there is a pressurized fluidized bed combined power generation system in which coal is burned in a fluidized bed under a pressurized atmosphere and a steam turbine and a gas turbine are driven simultaneously. In a pressurized fluidized bed combined power generation system, air is supplied from a dispersion plate to a fluidized bed particle layer in a furnace of a pressurized fluidized bed boiler to form a fluidized bed. Burn below.
[0005]
Then, steam is generated and heated in the heat transfer tube in the fluidized bed, and the steam turbine is driven by this steam. At the same time, the gas turbine is driven by high-temperature and high-pressure combustion exhaust gas generated from the furnace.
[0006]
When increasing the load of a pressurized fluidized bed boiler, fluidized bed particles (abbreviated as BM (Bed Material)) are used to increase the bed height of the fluidized bed and increase the amount of heat transfer by increasing the contact area with the heat transfer tube. Into the furnace. Further, when reducing the load, the fluidized medium particles forming the fluidized bed are extracted to lower the bed height and reduce the amount of heat transfer.
[0007]
On the other hand, in the conventional normal pressure fluidized bed combustor or reactor, the bed height of the fluidized bed is about 1 m, and the load is changed by changing the area of fluidization and combustion (or reaction) without changing the bed height. Combustion of fuel in a fluidized bed of 5 to 10m width and fluidized bed height of about 1m on a commercial machine scale, and fluidizing and burning by increasing the number of windbox cells for blowing and flowing air for combustion. Increase the load by increasing the area. The bed height is always constant and the bed height is relatively small with respect to the width of the fluidized bed.
[0008]
In such a fluidized bed apparatus that operates at a relatively shallow bed height and a constant bed height, when the measurement end for measuring the temperature in the bed is inserted into the bed, the side wall in the vicinity of the combustion furnace, etc. For example, a measuring end is inserted from a seat provided in the base, a seat is provided at the bottom of the apparatus, for example, an air dispersion plate, and a measuring end is inserted vertically at the center of the layer.
[0009]
[Problems to be solved by the invention]
In the fluidized bed apparatus in which the load is changed by changing the bed height as in the pressurized fluidized bed combustor as compared with the normal pressure fluidized bed combustor, the bed height becomes deep at a maximum of 4 to 5 m. When measuring the layer temperature at the top of the layer, the method of providing a seat at the bottom of the layer requires the measurement end to be inserted from the side wall because the measurement end becomes too long.
[0010]
However, when the measurement end is inserted horizontally into the fluidized bed to a certain depth, the following problems arise, unlike the measurement close to the wall. That is, in the fluidized bed, when viewed from the microscopic level, when the flow rate of the flowing gas is increased from the fluidization start state in which the individual particles are lifted by the air flow, the gas becomes bubbles and rises in the layer. become.
[0011]
This bubble pulls a particle group (also called a wake) behind (lower part), and this becomes the driving force of the particle upward flow in the fluidized bed. After the bubble has passed, the surrounding particles flow into the space after the bubble and wake, so when the bubble passes through the position of the measurement end, the measurement end applies a large upward force due to the wake particles pulled by the bubble. It is done.
[0012]
In addition, downward force or lateral force is applied to the measurement end by the particle descending or horizontal flow after passing through the bubble. Since bubbles rise in a random path in the fluidized bed, upward and downward forces are applied on the bubble path, and downward and lateral forces are applied outside the path. Repeated vertical stress is applied to the measurement edge by periodically passing bubbles. . Even if the single stress due to particle collision is small, if repeated stress is applied periodically, the risk of fatigue failure in the measurement end material increases.
[0013]
In most cases, the state value measured at the measurement end of the combustion apparatus or the reaction apparatus is used as a state value input for apparatus control, and the destruction of the measurement end leads to the inability to control the operation of the fluidized bed apparatus.
[0014]
As means for preventing the measurement end fatigue failure as described above, means for adding a member for supporting and protecting the measurement end can be considered. This method is effective for protecting the measurement end if it can be fixed to sufficiently suppress deformation due to stress at the measurement end. However, in order to obtain a structure having sufficient strength by fixing the member, the amount (volume) of the member is increased.
[0015]
In a fluidized bed apparatus, necessary members such as heat transfer tubes are often already densely installed. Supporting the measurement end to be inserted into the bed with a large-volume support member increases the installation density of the members in the fluidized bed, which leads to inhibition of flow and performance degradation of the apparatus. Therefore, in the measurement end protection by the support member, there is a difficulty in achieving both conflicting results of increased support strength and good flow retention.
[0016]
The problem of the present invention is that in a fluidized bed apparatus, it is possible to prevent repetitive stress acting on the measurement end for measuring the in-bed state, prevent fatigue failure at the measurement end, and always carry out stable operation by correctly measuring the state quantity. Is to do.
[0017]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is a fluidized bed apparatus for supplying a fuel into a fluidized bed that is fluidized by blowing a fluidizing gas from below the fluidized medium to perform combustion or a chemical reaction, A measuring end or a sampling pipe for detecting the temperature and / or pressure of the fluidized bed is arranged in a region where the fluidizing gas in the fluidized bed does not rise.
[0018]
According to the present invention, according to the present invention, since there is no upward flow of the flowing gas from below vertically, it is not subjected to repeated loads due to rising bubbles colliding with the measurement end or the sampling tube, so that fatigue failure of these members Is prevented, and the state quantity can always be measured correctly and stable operation can be carried out.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a fluidized bed combustor to which the present invention is applied. This example shows an embodiment in which the present invention is applied to a combustor portion of a pressurized fluidized bed combined power generation system (FIG. 4).
[0020]
In this embodiment, the side wall of the furnace 1 is inclined so that the horizontal cross-sectional area of the uppermost part of the fluidized bed is larger than the horizontal cross-sectional area of the gas dispersion plate 3 for flow, and the upward flow of the gas for flow does not occur. In the region, a detection unit of the measurement end 27 for knowing state quantities such as temperature and pressure is arranged.
[0021]
Hereinafter, this embodiment will be described in more detail. In the fluidized bed apparatus of this example, in a pressurized fluidized bed combustor (furnace) 1 stored in a pressure vessel 26, fuel 17 is injected into the fluidized bed 2 and burned. This is a pressurized fluidized bed boiler that generates power by driving the steam turbine 22.
[0022]
When raising the boiler load, the amount of heat transfer is increased by charging BM 6 from the BM tank 5 into the furnace 1, increasing the fluidized bed height, and increasing the contact area between the heat transfer tube and the fluidized bed. In order to control the state of steam and fuel combustion, the bed temperature is measured by the temperature measuring end 27. In order to insert the temperature measuring end 27 into the layer, a seat is required on the side wall of the furnace 1.
[0023]
In this example, the side wall of the furnace 1 is an inclined wall having an angle with respect to the vertical, and the cross-sectional area of the furnace is widened upward. A seat for inserting the temperature measuring end 27 is provided on the inclined wall. In the fluidized bed on the inclined wall, since there is no air dispersion plate vertically, bubbles do not pass through and a uniform downward flow is generated. Therefore, the temperature measuring end 27 is not repeatedly subjected to stress and causes material fatigue. It is a difficult arrangement.
[0024]
The pressurized fluidized bed boiler of this example includes an adjustment valve 9 that adjusts the flow rate of the BM supply air 10, an adjustment valve 11 that adjusts the flow rate of the BM extraction air 12 in the fluidized bed, and BM return air that is returned to the BM tank 5. 14 is provided with an adjustment valve 13 for adjusting the flow rate of 14, a BM supply line 15, a BM extraction line 16, and the like.
[0025]
FIG. 2 shows another embodiment of the present invention. This example has a system configuration of a pressurized fluidized bed boiler similar to the example of FIG. Unlike the structure shown in FIG. 1, the side wall structure of the furnace has a structure in which the cross-sectional area above the furnace is large with a step.
[0026]
The side wall above the step is a side wall that does not have an air dispersion plate vertically below, and an insertion seat for the temperature measurement end 27 is installed on the side wall. In the fluidized bed above the level difference, bubbles do not pass and a uniform downward flow is generated. Therefore, the temperature measurement end 27 is not repeatedly subjected to stress, and is less likely to cause material fatigue.
[0027]
FIG. 3 shows still another embodiment of the present invention. In this example, the side wall of the furnace 1 is not provided with an inclination or a step that does not have an air dispersion plate vertically below, but a partition is installed in the fluidized bed 2, and this partition is separated from the shielding member 28. Thus, a fluidized bed area is formed in which bubbles from the dispersion plate do not rise.
[0028]
In the fluidized bed above the shielding member 28, a uniform downward flow is generated as in the fluidized bed on the inclined wall in the example of FIG. A side wall insertion seat is provided at a position where the temperature measuring end 27 can be inserted into the upper part of the shielding member 28. By installing the temperature measuring end in the area where the bubbles do not pass, the temperature measuring end 27 is not subjected to repeated stress and is less likely to cause material fatigue.
[0029]
According to the embodiment described above, since the gas for flow from the vertically lower side is not supplied, (1) bubbles do not pass and (2) an area where uniform particle downward flow is generated is formed. When a seat for inserting the measurement end is provided on such a side wall and the measurement end is inserted in the horizontal direction, the measurement end is installed in a form that is bubble-free and crosses the downstream area.
[0030]
As a result, in the bubble-free and downstream area, the measurement end is not exposed to the rising bubbles, so that it does not receive cyclical repetitive stress, and the wake particles behind the bubbles that collide most rapidly in the fluidized bed collide. Never do. Therefore, the stress applied to the measurement end is only a relatively small uniform downward stress due to the downward flow, and the risk of causing fatigue failure of the material is greatly reduced.
[0031]
When the measurement end is inserted deeper, the tip of the measurement end protrudes into the bubble presence area, but since the fixed length from the base of the measurement end is in the bubble-free area, the entire measurement end is in the bubble area. Compared with the conventional installation method, the stress received is reduced, and the effect of extending the material life can be obtained.
[0032]
FIG. 4 shows an example of the configuration of a pressurized fluidized bed combined power generation system to which the present invention is applied. In the furnace 1 of the pressurized fluidized bed boiler, air is supplied to the fluidized bed particle layer from the dispersion plate 3 to form the fluidized bed 2, and the fuel 17 is burned in the fluidized bed 2 at a maximum pressure of about 10 atm. .
[0033]
Then, steam is generated and heated in the heat transfer pipe 4 in the fluidized bed, and the steam turbine 22 is driven by this steam. At the same time, the gas turbine 19 is driven by the high-temperature and high-pressure combustion exhaust gas 8 generated from the furnace 1.
[0034]
When increasing the load of the pressurized fluidized bed boiler, the bed height of the fluidized bed 2 is increased, the contact area with the heat transfer tube 4 is increased, and the amount of heat transfer is increased. Therefore, fluid medium particles (abbreviated as BM (Bed Material)) 6 are introduced from the fluid medium container (also referred to as BM tank) 5 into the furnace 1 through the BM supply line 15.
[0035]
When reducing the load, the fluidized medium particles forming the fluidized bed 2 are extracted from the BM extraction line 16 to the BM tank 5 to lower the bed height and reduce the amount of heat transfer.
[0036]
Thus, in a fluidized bed apparatus that changes the load by changing the bed height, the bed height becomes as deep as 4 to 5 m at maximum. When measuring the layer temperature at the top of the layer, the method of providing a seat at the bottom of the layer requires the measurement end to be inserted from the side wall because the measurement end becomes too long.
[0037]
As shown in FIG. 5, unlike the measurement close to the wall, when the measurement end is horizontally inserted into the fluidized bed to a certain depth, the following problems occur. FIG. 6 shows a schematic diagram of gas and particle flow when the measurement end is inserted from the fluidized bed side wall, and the change with time of the stress applied to the measurement end. Microscopically, in the fluidized bed, when the flow gas flow rate is increased from the fluidization start state where individual particles are lifted by the air flow, the gas becomes bubbles and rises in the layer. .
[0038]
As shown in FIG. 7, the bubbles pull the particle group (also called wake) backward (lower part), and this becomes the driving force of the particle upward flow in the fluidized bed. After the bubble has passed, the surrounding particles flow into the space after the bubble and the wake, so when the bubble passes through the position of the measurement end, the measurement end applies a large upward force to the measurement end due to the wake particles pulled by the bubble. It is done.
[0039]
Further, after passing through the bubbles, downward and lateral forces are applied by the descending particles and horizontal flow. Since bubbles rise in a random path in the fluidized bed, upward force is applied on the bubble path, downward force is applied on the outside of the path, and lateral force is applied. Repeated stress in the vertical direction is applied to the measurement edge by the periodically passing bubbles. . Even if the single stress due to particle collision is small, if repeated stress is applied periodically, the risk of fatigue failure in the measurement end material increases.
[0040]
In most cases, the state value measured at the measurement end of the combustion apparatus or the reaction apparatus is used as a state value input for apparatus control, and the destruction of the measurement end leads to the inability to control the apparatus.
[0041]
As means for preventing the measurement end fatigue failure as described above, means for adding a member for supporting and protecting the measurement end can be considered. This method is effective for protecting the measurement end if it can be fixed to sufficiently suppress deformation due to stress at the measurement end. However, in order to obtain a structure having sufficient strength by fixing the member, the amount (volume) of the member is increased.
[0042]
As shown in FIG. 4, necessary members such as heat transfer tubes are often densely installed in the bed of the fluidized bed apparatus. Supporting the measurement end to be inserted into the bed with a large-volume support member increases the installation density of the members in the fluidized bed, which leads to inhibition of flow and performance degradation of the apparatus. Therefore, in the measurement end protection by the support member, there is a difficulty in achieving both conflicting results of increased support strength and good flow retention.
[0043]
As described above, according to the embodiment of the present invention, the region without the rising bubbles in the fluidized bed, the measurement unit and the sampling unit can be arranged, so that these members are not subjected to repeated loads due to the rising bubbles, so that the fatigue failure Can be prevented, and high-precision measurement and stable operation based on it can be realized.
[0044]
【The invention's effect】
As described above, according to the present invention, in the fluidized bed combustor having the measurement end, when the measurement end is inserted horizontally into the fluidized bed, the measurement end is repeatedly subjected to stress, and the material is subject to fatigue failure. This is effective for stable operation and control by preventing and always measuring the state quantity of the device correctly.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a fluidized bed combustor which is an embodiment of the present invention.
FIG. 2 is a configuration diagram showing a fluidized bed combustor which is another embodiment of the present invention.
FIG. 3 is a configuration diagram showing a fluidized bed combustor which is still another embodiment of the present invention.
FIG. 4 is a configuration diagram of a pressurized fluidized bed combined power generation system to which the present invention is applied.
FIG. 5 is a schematic view of a constant bed high normal pressure fluidized bed combustor and a measurement end arrangement.
FIG. 6 is a diagram showing particles and gas flow of a fluidized bed apparatus having a vertical side wall and stress applied to a measurement end.
FIG. 7 is a diagram showing particle collision and stress experienced by a measurement end when a bubble passes.
FIG. 8 is a diagram showing particles and gas flow of a fluidized bed apparatus having an inclined side wall and stress applied to a measurement end.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Furnace 2 Fluidized bed 3 Air dispersion plate 4 Heat transfer tube 5 BM (fluid medium) tank 6 Fluid medium particle (BM)
17 Fuel 20 Air 26 Pressure vessel 27 Temperature measurement end 28 Shielding member

Claims (2)

  A fluidized bed apparatus that performs combustion or chemical reaction by supplying fuel into a fluidized bed that is fluidized by blowing a fluidizing gas from below the fluidized medium. In the region where the horizontal cross-sectional area of the uppermost part of the fluidized bed is larger than the horizontal cross-sectional area of the gas supply part, the flow gas in the fluidized bed above the step part does not rise. A fluidized bed apparatus comprising a measuring end or a sampling pipe for detecting the temperature and / or pressure of the fluidized bed. A fluidized bed apparatus according to claim 1 , wherein steam is generated by heat generated in the fluidized bed, and a steam turbine is driven by the steam to generate electric power, or gas is generated by combustion gas generated in the fluidized bed. A power generation system that generates power by driving a turbine.

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