JP2003065504A - Fluidized bed device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent repeated stress acting on a measuring end measuring the state inside the bed of a fluidized bed device, and prevent the fatigue failure of the measuring end. SOLUTION: In the fluidized bed device (a furnace 1), a seat for inserting the measuring end 27 into a fluidized bed 2 is provided on the sidewall of a structure that does not have an air-dispersing plate 3 under the vertical of an inclined wall, for example, and the gas for fluidity. Bubbles do not pass through the location of the measuring end, or a part of the length of the measuring end passes through a bubble-free zone. Thereby, the repeated stress applied on the measuring end at the time when the bubbles pass through is eliminated or reduced, so as to relieve material fatigue.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fluidized bed apparatus,
In particular, the present invention relates to a measuring device for measuring the state quantity in a fluidized bed so that material fatigue does not occur.

[0002]

2. Description of the Related Art A fluidized bed is a fluidized bed in which a gas such as air is blown into a bed containing particles to fluidize the entire bed.
It is a fluidized bed combustor or a fluidized bed furnace that supplies and burns fuel in the fluidized bed.

A fluidized bed combustor has a long residence time of fuel,
In addition, it is widely used in power generation systems, waste treatment plants, chemical plants, etc. because it has a feature that the heat generated can be used with high efficiency by a fluidized bed with a large heat capacity.

As an example of the latest technology utilizing a fluidized bed combustor, there is a pressurized fluidized bed combined cycle power generation system in which coal is burned in a fluidized bed under a pressurized atmosphere to drive a steam turbine and a gas turbine at the same time. In a pressurized fluidized bed combined cycle power generation system, air is supplied from a dispersion plate to a bed of fluidized bed particles in a furnace of a pressurized fluidized bed boiler to form a fluidized bed. Burn down.

Then, steam is generated and superheated 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 the combustion exhaust gas of high temperature and high pressure generated from the furnace.

When the load of the pressurized fluidized bed boiler is increased, the bed height of the fluidized bed is increased and the contact area with the heat transfer tube is increased to increase the heat transfer amount.
Material) is put into the furnace. When the load is reduced, the fluid medium particles forming the fluidized bed are extracted to lower the bed height and reduce the amount of heat transfer.

On the other hand, in the conventional atmospheric fluidized bed combustor or reactor, the bed height of the fluidized bed is set to about 1 m, and the load is changed by changing the area of fluidization or combustion (or reaction) without changing the bed height. Was there. On the scale of a commercial machine, fuel is burned in a fluidized bed having a width of 5 to 10 m and a fluidized bed height of about 1 m, and flow and combustion are performed by increasing the number of cells of a wind box that blows air for fluidization and combustion. Increase the area and increase the load. The bed height is always constant, and the bed height is relatively small with respect to the width of the fluidized bed.

In a fluidized bed apparatus which operates at such a relatively shallow bed height and a constant bed height, when a measurement end for measuring the temperature in the bed is inserted into the bed, the vicinity of the side wall of the combustion furnace is For example, a method has been adopted in which the measuring end is inserted from a seat provided on the side wall, the seat is provided at the bottom of the apparatus, for example, an air dispersion plate at the center of the layer, and the measuring end is vertically inserted.

[0009]

In contrast to the above normal pressure fluidized bed combustor, in a fluidized bed apparatus which changes the bed height to change the load like a pressurized fluidized bed combustor, the bed height is 4 to 5 m at maximum. Becomes deeper. In the case of measuring the layer temperature at the upper part of the layer, in the method of providing a seat at the bottom of the layer, the measuring end becomes too long, so it is necessary to insert the measuring end from the side wall.

However, when the measurement end is horizontally inserted into the fluidized bed to a certain depth, unlike the measurement close to the wall, the following problems occur. That is, in the fluidized bed, microscopically, when the flow rate of the flowing gas is increased from the fluidization start state where individual particles are floated by the air flow, the gas becomes bubbles and rises in the bed. become.

The bubbles pull a group of particles (also called a wake) to the rear (lower part), which becomes the driving force for the upward flow of particles in the fluidized bed. After the bubbles pass, surrounding particles flow into the space after passing the bubbles and the wakes.Therefore, when the bubbles pass the position of the measurement end, the wake particles pulled by the bubbles apply a large upward force to the measurement end. To be

After passing through the bubbles, a downward force or a lateral force is applied to the measurement end due to the descending particles and the horizontal flow. Since bubbles rise in a random path in the fluidized bed, upward force is applied on the bubble path, downward force and lateral force are applied outside the bubble path, and periodically passing bubbles add repeated vertical stress to the measurement end. . Even if the one-time stress due to the collision of particles is small, if stress is repeatedly applied periodically, the risk of causing fatigue fracture in the material at the measurement end increases.

The state value measured at the measuring end of the combustion device or the reaction device is almost always used as the state value input for controlling the device, and the destruction of the measuring end makes it impossible to control the operation of the fluidized bed device. Leads to.

As a means for preventing the above fatigue damage at the measuring end, a means for adding a member for supporting and protecting the measuring end can be considered. This method is effective for protecting the measuring end if it can be fixed sufficiently to prevent deformation due to stress at the measuring end. However, in order to obtain a structure having sufficient strength by fixing the members, the amount (volume) of the members becomes large.

In many cases, necessary members such as heat transfer tubes are already installed in the bed of the fluidized bed apparatus in an overdense manner. Supporting the measurement end to be inserted into the bed with a large volume of the support member increases the installation density of the members in the fluidized bed, leading to obstruction of the flow and deterioration of the performance of the device. Therefore, the protection of the measurement end by the support member has a difficulty in achieving both the contradictory results of increased support strength and good flow retention.

An object of the present invention is to prevent repetitive stress acting on the measuring end for measuring the in-layer state in a fluidized bed apparatus,
This is to prevent fatigue damage at the measurement end and to always measure the state quantity correctly so that stable operation can be performed.

[0017]

In order to solve the above-mentioned problems, the present invention provides a fuel by supplying a fuel into a fluidized bed which is fluidized by injecting a fluidizing gas from below a fluidized medium to perform combustion or chemical reaction. In the fluidized bed apparatus for performing the above, 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. To do.

According to the present invention, according to the present invention, since there is no upward flow of the flow gas from below in the vertical direction, repeated loads due to rising bubbles that collide with the measuring end or the sampling pipe are not applied, and therefore these members are not used. Fatigue damage is prevented, and the state quantity can always be measured correctly for stable operation.

[0019]

BEST MODE FOR CARRYING OUT 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 cycle power generation system (Fig. 4).

In this embodiment, the side wall of the furnace 1 is inclined so that the horizontal cross-sectional area of the uppermost portion of the fluidized bed is larger than the horizontal cross-sectional area of the fluidizing gas dispersion plate 3, and the upward flow of the fluidizing gas is increased. A detection unit of the measuring end 27 for recognizing the state quantities such as temperature and pressure is arranged in a region where the phenomenon does not occur.

The present embodiment will be described in more detail below. In the fluidized bed apparatus of this example, in a pressurized fluidized bed combustor (furnace) 1 stored in a pressure vessel 26, a fuel 17 is charged into a fluidized bed 2 and burned, and steam is generated from water in a heat transfer tube 4. It is a pressurized fluidized bed boiler that generates and drives the steam turbine 22 to generate electricity.

When increasing the boiler load, the BM tank 5
The BM6 is charged into the furnace 1 to increase the fluidized bed height and increase the contact area between the heat transfer tube and the fluidized bed to increase the heat transfer amount. To control the state of steam and fuel combustion,
The layer temperature is measured by the temperature measuring end 27. Since the temperature measuring end 27 is inserted into the layer, a seat is required on the side wall of the furnace 1.

In this example, the side wall of the furnace 1 is an inclined wall having an angle with respect to the vertical, and the sectional area of the furnace widens upward. The seat into which the temperature measuring end 27 is inserted is provided on this inclined wall. In the fluidized bed on the inclined wall, since there is no air dispersion plate vertically below, air bubbles do not pass through, and a uniform downward flow is generated.
Is not subjected to repeated stress, and is arranged so that material fatigue does not easily occur.

In the pressurized fluidized bed boiler of this example, the adjusting valve 9 for adjusting the flow rate of the BM supply air 10 and the BM in the fluidized bed are used.
An adjustment valve 11 for adjusting the flow rate of the extraction air 12, an adjustment valve 13 for adjusting the flow rate of the BM return air 14 returned to the BM tank 5, a BM supply line 15, a BM extraction line 16 and the like are provided.

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. The side wall structure of the furnace is different from that of FIG. 1 and has a structure in which the cross-sectional area above the furnace becomes large with a step.

The side wall above the step is a side wall having no air distribution plate vertically below, and the temperature measuring end 27 is formed on this side wall.
The insertion seat is installed. In the fluidized bed above the step, air bubbles do not pass and a uniform downward flow is generated, so that the temperature measurement end 27 is not subjected to repeated stress, and the material fatigue does not occur.

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 which does not have an air dispersion plate vertically below, but a partition is installed in the fluidized bed 2, and this partition serves as the shielding member 28. Thus, a fluidized bed area where bubbles from the dispersion plate do not rise is formed.

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 portion of the shielding member 28. By installing the temperature measurement end in the area where bubbles do not pass, the temperature measurement end 2
No. 7 is arranged so that it is not subjected to repeated stress and material fatigue does not easily occur.

According to the embodiment described above, since the flowing gas is not supplied from below vertically, (1) bubbles do not pass through, and (2) a region where a uniform particle downflow is formed 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 traverses the downstream area.

As a result, in the bubble-free, downstream region, the measuring end is not exposed to the rising bubbles, so that it is not subjected to cyclic repetitive stress, and the wake behind the bubbles, which has the highest velocity in the fluidized bed, is obtained. No particles collide. Therefore, the stress received at the measurement end is only a relatively small uniform downward stress due to the downward flow, and the risk of causing fatigue fracture of the material is greatly reduced.

When the measurement end is inserted deeper, the tip of the measurement end projects into the bubble existence region, but since there is a fixed length from the root of the measurement end in the bubble-free region, the entire measurement end is bubbled. Compared to the conventional installation method in the area, the stress received is smaller and the effect of extending the material life is obtained.

FIG. 4 shows an example of the structure of a pressurized fluidized bed combined cycle power generation system to which the present invention is applied. In the furnace 1 of the pressurized fluidized bed boiler, air is supplied from the dispersion plate 3 to the bed of fluidized bed particles to form the fluidized bed 2, and the fuel 17 is burned in the fluidized bed 2 under a high pressure of about 10 atm maximum. .

Then, steam is generated and superheated in the heat transfer tube 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.

When the load of the pressurized fluidized bed boiler is increased, the bed height of the fluidized bed 2 is increased and the contact area with the heat transfer tube 4 is increased to increase the amount of heat transfer. Therefore, fluidized medium particles (BM
(Bed Material) 6 is charged into the furnace 1 from a fluidized medium container (also referred to as BM tank) 5 through a BM supply line 15.

When the load is reduced, the fluid medium particles forming the fluidized bed 2 are discharged from the BM withdrawal line 16 to B.
By extracting into the M tank 5, the layer height is lowered and the amount of heat transfer is reduced.

As described above, in the fluidized bed apparatus in which the bed height is changed to change the load, the bed height is as deep as 4 to 5 m at maximum. In the case of measuring the layer temperature at the upper part of the layer, in the method of providing a seat at the bottom of the layer, the measuring end becomes too long, so it is necessary to insert the measuring end from the side wall.

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 flows when the measuring end is inserted from the side wall of the fluidized bed, and a temporal change in stress received by the measuring end. In the fluidized bed, microscopically, when the flow rate of the flow gas is increased from the fluidization start state where individual particles are lifted by the air flow, the gas becomes bubbles and rises in the bed. .

As shown in FIG. 7, the bubbles are behind (bottom).
A group of particles (also called a wake) is pulled to this, which becomes the driving force for the upward flow of particles in the fluidized bed. After the bubbles pass, the surrounding particles flow into the space after passing the bubbles and the wake.Therefore, when the bubbles pass the position of the measurement end, the wake particles pulled by the bubbles apply a large upward force to the measurement end. To be

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. Cyclically passing bubbles apply repeated vertical stress to the measurement end. . Even if the one-time stress due to the collision of particles is small, if stress is repeatedly applied periodically, the risk of causing fatigue fracture in the material at the measurement end increases.

The state value measured at the measuring end of the combustion device or the reaction device is almost always used as the state value input for controlling the device, and the destruction of the measuring end leads to the inability to control the device.

As a means for preventing the above fatigue damage at the measuring end, a means for adding a member for supporting and protecting the measuring end can be considered. This method is effective for protecting the measuring end if it can be fixed sufficiently to prevent deformation due to stress at the measuring end. However, in order to obtain a structure having sufficient strength by fixing the members, the amount (volume) of the members becomes large.

As shown in FIG. 4, it is often the case that necessary members such as heat transfer tubes are already densely installed in the bed of the fluidized bed apparatus. Supporting the measurement end to be inserted into the bed with a large volume of the support member increases the installation density of the members in the fluidized bed, leading to obstruction of the flow and deterioration of the performance of the device. Therefore, the protection of the measurement end by the support member has a difficulty in achieving both the contradictory results of increased support strength and good flow retention.

As described above, according to the embodiment of the present invention, since the region in the fluidized bed where there is no rising bubble, the measuring unit and the sampling unit can be arranged, these members do not receive the repeated load due to the rising bubble. , Fatigue damage is prevented,
Highly accurate measurement and stable operation based on it can be realized.

[0044]

As described above, according to the present invention, in the fluidized bed combustor having the measuring end installed, when the measuring end is inserted horizontally into the fluidized bed, the measuring end is repeatedly stressed and the material is fatigued. It is effective for stable operation and control by preventing damage and constantly measuring the state quantity of the device.

[Brief description of 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 cycle power generation system to which the present invention is applied.

FIG. 5 is a schematic diagram of a constant bed high atmospheric pressure fluidized bed combustor and arrangement of measurement ends.

FIG. 6 is a diagram showing the flow of particles and gas in a fluidized bed apparatus having vertical side walls and the stress applied to the measurement end.

FIG. 7 is a diagram showing particle collision and stress received by a measurement end when passing a bubble.

FIG. 8 is a diagram showing a flow of particles and gas in a fluidized bed apparatus having inclined side walls and stress applied to a measurement end.

[Explanation of symbols]

1 furnace 2 fluidized bed 3 Air dispersion plate 4 heat transfer tubes 5 BM (fluid medium) tank 6 Fluid medium particles (BM) 17 Fuel 20 air 26 Pressure vessel 27 Temperature measurement end 28 Shielding member

Claims (5)

[Claims] 1. A fluidized bed apparatus for supplying a fuel into a fluidized bed, which is fluidized by blowing a fluidizing gas from below a fluidized medium, to perform combustion or a chemical reaction. Alternatively, a fluidized bed apparatus, wherein a measuring end or a sampling tube for detecting pressure is arranged in a region in the fluidized bed where the fluidizing gas does not rise. 2. The fluidized bed apparatus according to claim 1,
The structural wall around the fluidized bed is formed into an inclined wall in which the horizontal cross-sectional area of the uppermost part of the fluidized bed is larger than the horizontal cross-sectional area of the supply part for the fluidizing gas, and from the inclined wall, the measurement end or the A fluidized bed apparatus having a sampling tube inserted therein. 3. The fluidized bed apparatus according to claim 1,
On the structural wall around the fluidized bed, a step portion is formed in which the horizontal cross-sectional area of the uppermost portion of the fluidized bed is larger than the horizontal cross-sectional area of the fluidizing gas supply portion, and the measurement end is provided above the stepped portion. Alternatively, a fluidized bed apparatus in which the sampling tube is arranged. 4. The fluidized bed apparatus according to claim 1,
A fluidized bed apparatus, wherein a shielding member that blocks an ascending flow of the flowing gas is installed in the fluidized bed, and the measurement end or the sampling pipe is arranged above the shielding member. 5. A fluidized bed apparatus according to any one of claims 1 to 4 is provided, wherein steam is generated by heat generated in the fluidized bed and a steam turbine is driven by the steam to generate electricity. Alternatively, a power generation system that drives a gas turbine with the combustion gas generated in the fluidized bed to generate electric power.