JPS60105807A - Fluidized bed type boiler and controlling method thereof - Google Patents

Abstract

PURPOSE:To enable an accommodation to be performed against a variation in load etc. by a method wherein a height of upper fluidized bed is adjusted to vary its contact area with a heat transmitting pipe and a preparatory fluidized medium is always heated in advance at the lower fluidized bed layer and then it is kept at a suitable temperature. CONSTITUTION:A boiler is composed of a lower fluidized bed furnace 2 forming a fluidized bed 2A and an upper fluidized bed furnace 3 having a thermal conductive pipe 10 in the fluidized bed 3A, and a down pipe 6, lift pipe 7, descending pipe 8 and transporting device 9 are arranged to transfer the fluidized fluid between both fluidized beds, either air or mixture gas of air and steam is supplied to the lower fluidized bed furnace 2 from below the dispersion mechanism 27, the generated gas and oil are guided to the upper fluidized bed furnace 3, injected from the dispersion mechanism 28 upwardly so as to act the fluidized gas. Under variation in load, the height of the lower fluidized bed 2A is adjusted to vary the contact area with the thermal transmitting pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed boiler in which heat exchanger tubes are provided in a fluidized bed.

In a conventional fluidized bed boiler of this kind, for example, in FIG. 1, numeral 41 is a fluidized bed furnace, and a fluidized bed 42 houses heat transfer tubes 43 for generating steam. 44 is a combustible material supply device; 45 is a flow rate control valve for air for combusting;
46 is a detector for detecting the flow rate or pressure of generated steam; 47
is a control device that controls the state of the generated steam by operating the flow rate control valve 45 or the combustible supply device 44 based on the detection signal of the flow rate or pressure of the generated steam from the detector 46.

In such a conventional device, since the heat transfer tubes 43 are provided in a single fluidized bed 42, the heat capacity of the fluidized medium is large, and the heat transfer coefficient around the heat transfer tubes 43 is almost constant. There is a drawback that residual heat remains even after combustion is stopped, and it cannot respond to large or rapid load changes.

It is an object of the present invention to provide a fluidized bed boiler and a control method thereof that can eliminate the above-mentioned drawbacks of the conventional boiler and can immediately correct changes in the amount of steam generated in response to changes in conditions such as load fluctuations. It is from et al.

In order to achieve this objective, the inventor conducted extensive research and discovered that by freely controlling the height of the fluidized medium in the heat transfer tube section, the amount of exchanged heat can be changed quickly over a wide range, and that a separate preliminary fluidized bed is provided. The inventors came up with the idea of storing a spare volume of fluid medium that does not participate in heat exchange while always keeping it at an appropriate temperature, and came up with the present invention.

The present invention includes a lower fluidized bed furnace, and an upper fluidized bed furnace on the second side of the lower fluidized bed furnace, which uses the gas generated in the lower fluidized bed furnace as a fluidizing gas, and the upper fluidized bed furnace has a lower fluidized bed furnace. a lowering means for lowering the fluidized medium between the two-part fluidized bed furnace and the lower fluidized bed furnace; and the lowering means and the lifting means are each provided with adjusting means for adjusting the descending amount and lifting amount of the fluidized medium, and the adjusting means adjusts the height of the fluidized bed in the upper fluidized bed furnace. This fluidized bed boiler is characterized in that it is adjustable.

To summarize the present invention, another fluidized bed (lower fluidized bed) is provided below a fluidized bed containing heat exchanger tubes for steam generation (referred to as upper fluidized bed), and coal is added to this lower fluidized bed. , oil shale, oil sands or municipal waste. Here, air is sent from the bottom as a fluidizing gas, and thermal decomposition is performed by complete combustion or partial ignition to generate gas, ash, or gas, oil, and char. These are introduced into a two-part fluidized bed with the gas component acting as a fluidizing force.

In the case of partial combustion, a grid pipe is provided at the bottom of the two-part fluidized bed, and air is blown out from there to strengthen fluidization and completely burn the thermal decomposition products. This combustion heat allows it to generate steam as efficiently as a conventional fluidized bed boiler.

In the present invention, the following effect provides an advantage in dealing with load fluctuations.

The amount of steam generated is determined by the heat transfer area of the heat transfer tubes in the upper fluidized bed, so a lifting device for the fluidized medium is installed to lower the fluidized medium to the lower fluidized bed, or conversely to lift it to the upper fluidized bed. Controlled by shaking.

A plurality of communication pipes connecting the upper and lower fluidized beds are provided as a lifting device. - The downward force communication pipe connects the bottom of the upper it fluidized bed and the lower fluidized bed, and the dispersion mechanism around this lower fluidized bed height 1'' portion is locally independent.

Normally, the dispersion mechanism is stopped without flowing gas, but by flowing gas, the surrounding area becomes fluidized and the fluidized medium in the upper fluidized bed can be lowered to the lower fluidized bed. The descending connection pipe and the local dispersion mechanism form the descending means. The local dispersion mechanism acts as a regulating means for adjusting the amount of descent of the fluidizing medium.

When the required amount of steam becomes zero, the entire amount of fluidized medium in the upper fluidized bed is lowered to the lower fluidized bed through the descending communication pipe.

In addition, the lift connecting pipe of the pond consists of a connecting pipe that descends from the lower fluidized bed, and a lifting pipe that connects the lower and upper parts of the connecting pipe to the photonic layer. (Equipped with a mechanism. This system locally fluidizes the seven lifters and the fluidic medium below them to form an airflow higher than the final velocity of the fluidic medium in response to a lifting command signal, thereby reducing the amount of lift. A nozzle consisting of an injection nozzle as an adjusting means (consisting of several parts). The lifting pipe and the nozzle mechanism form the lifting means.

In this way, part of the fluidized medium in the lower fluidized bed can be freely pumped to the fluidized bed.

In this way, we have added a communication pipe that connects multiple stages of fluidized beds and a lifting device that can freely control the movement of the fluid medium through the communication pipe, making it possible to improve the Demonstrate this power.

If the required amount of steam suddenly drops to Ig2, it can be dealt with immediately and can be restored easily and in a short time.

In other words, the turndown signal activates the lifting device, and the fluidized medium in the upper fluidized bed is transported through the descending connecting pipe.
Descend to the lower fluidized bed.

At the same time, the amount of combustible material supplied is reduced. This amount is determined by the amount of heat required to maintain the fluid medium temperature.

By repeating this process, the amount of fluidized medium that comes into contact with the heat transfer tube can be reduced and the amount of heat exchanged can be reduced, so that the required amount of steam can be generated immediately and the temperature of the fluidized medium can be maintained.

In addition, when the required amount of steam increases, the amount of combustible material supplied is increased, and at the same time, the fluidized medium in the lower fluidized bed is lifted to the two-part fluidized bed using a lifting device, and the fluidized bed is adjusted according to the required amount of steam. maintain high.

At this time, the fluidized medium is kept at a normal temperature, and the amount of combustible material supplied is increased simultaneously with the signal, so the amount of steam generated can be instantly increased.

Embodiments of the present invention will be described using the drawings.

In FIG. 2 and FIG. 3, the two-stage fluidized bed boiler 1 has a combustible material supply device 4 at the bottom (1611),
A heat exchanger tube 1 is placed inside the lower fluidized bed furnace 2 and the fluidized bed 3A forming a
0" two-part fluidized bed furnace 3. In order to move the fluidized medium between the two fluidized beds, a descending pipe 6, a lifting pipe 7, a descending device 8, and a lifting device 9 are provided.

Combustible materials such as coal are transferred to the combustible material supply device 4 and the lower fluidized bed furnace 2.
supplied to The supply amount can be made variable. In the lower fluidized bed furnace 2, in order to form a fluidized bed 2A,
Air or a mixed gas of air and steam is supplied from the lower part of the dispersion mechanism 27.

In the case of partial combustion, since sufficient air is not supplied for complete combustion, the input combustibles are thermally decomposed in an atmosphere with a low oxygen concentration, producing gas, oil, and char. The heat required for pyrolysis is supplemented by partial combustion of the fuel.

Here, in cases where the required amount of steam is small, the temperature does not reach a high temperature, so complete combustion may be performed without thermal decomposition using the partial combustion method.

The generated gas and oil are led to one upper 1ML fluidized bed furnace 3, and are ejected from the dispersion mechanism 28 to the second part, where they act as fluidizing gas. In addition, a dispersion mechanism such as a grid pipe 29 is installed at the bottom of the two-part fluidized bed, through which air is blown to strengthen the fluidized bed, and gas, oil, etc.
Reacts with char and causes complete combustion. The heat exchanger tube 10 provided inside the fluidized bed 3A receives this heat and generates steam.

The amount of steam demanded can be detected by a flow meter or a pressure gauge as a detector 18 provided around the steam header. The lowering device 8 and the lifting device 9 are activated by the signal from the detector 18. That is, when the demand for steam decreases, the lowering device 8 is operated to lower the fluidized medium to reduce the height of the fluidized bed 3A and reduce the contact area between the heat exchanger tube 1o in the upper fluidized bed furnace 3 and the fluidized medium. let Normally, the area around the exit of the downcomer pipe 6 is not fluidized because fluidizing gas is not supplied from below. The fluid medium in the downcomer pipe 6 thus remains filled throughout the fall.

The valve 12 is opened in response to a descending command and a signal, and air or steam is ejected from the dispersion mechanism 3o provided independently at the exit end of the downcomer pipe 6, and the area around it is fluidized, thereby resting the exit end of the downcomer pipe 6. The corner collapses and the fluidized medium is transferred to the lower fluidized bed furnace 2.
can be dropped to. After dropping an amount of steam corresponding to the required amount, the valve 12 is closed and the inside of the lower i-tube 6 is returned to a packed bed state.

Further, the variable speed motor 5 is set to a low speed by the same signal to reduce the amount of combustible material supplied and maintain the temperature of the fluid medium. At this time, complete combustion may be performed without partial combustion. When the amount of steam generated is the minimum, the amount of fluidized medium in the upper fluidized bed furnace 3 may be set to zero.

When the demand for steam increases, the pumping device 9 is operated to pump the fluidized medium in the lower fluidized bed furnace 2 to the upper fluidized bed furnace 3, thereby increasing the contact area between the heat transfer tubes 10 and the fluidized medium.

As shown in FIG. 3, the pumping mechanism 9 includes a pumping mechanism 15 that pumps air at a flow rate sufficient to pump the fluidized medium, that is, a flow rate higher than the final velocity of the fluidized medium, and a pumping/sliding mechanism located below the pumping nozzle 15. It consists of an injection nozzle 16 that fluidizes the surrounding fluid medium and controls the amount of pumping. The valve 13 is opened in response to a lift command signal, and air is supplied from the lift nozzle 15 to ensure the flow rate necessary for lift. Next, the valve 14 is opened and air corresponding to the required pumping amount is supplied from the injection nozzle 16. This results in
After confirming that the required amount can be pumped to the upper fluidized bed, the valve +4. Close in the order of l'3.

Whether or not there is a sufficient amount of fluidized medium can be determined by detecting the differential pressure between the upper and lower sides of the upper fluidized bed 3A using the differential pressure gauge 21, and the elevating device is operated based on this signal. In addition to detecting the differential pressure between the upper and lower sides of the lower fluidized bed 2A using the differential pressure gauge 22,
It is determined whether the total fluidic medium filling amount is appropriate and the fluidic medium extractor 25 or supply device 26 is operated.

The extraction device 25 also plays the role of discharging foreign matter thrown into the furnace or clinker generated within the furnace.

Other control systems will be described below.

Except for a sudden turndown in the steam demand, the temperature of the upper fluidized bed 3A is detected by the temperature detector 24, and the variable speed motor 5 is operated according to a signal from the control device 19 so that the temperature is within a certain range, and combustible material is supplied. Control quantity. As a result, the amount of steam generated is almost uniquely determined by the contact area between the heat exchanger tube 10 and the fluidized medium of the fluidized bed 3A.

Energy can be saved by controlling the amount of air supplied to the upper fluidized bed 3A by detecting the oxygen concentration of the exhaust gas with the concentration detector 20 and controlling the amount of air supplied by operating the flow rate control valve 17 so that the oxygen concentration is within a certain range. You can also contribute.

The temperature of the lower fluidized bed 2A is detected by a temperature detector 23, and the valve 11 is operated so that the temperature becomes a predetermined temperature, thereby adjusting and controlling the amount of air for partial combustion.

When most of the fluidized medium has moved to the lower fluidized bed 2A due to a sudden turn-down, the control is performed in conjunction with the combustible material supply amount.

Regarding pollution prevention, especially in terms of locomotion, it is possible to reduce SOx and HCρ by supplying slaked lime along with combustible materials. Since it is a two-stage fluidized bed, it also has the effect of increasing the contact efficiency with additives.

Next, another embodiment will be explained with reference to FIGS. 4 and 5. In this embodiment, the fluidic medium elevator pipe and the lifting device are integrated. That is, as shown in FIGS. 4 and 5, a communication pipe 31 is provided as an extension of the dispersion mechanism 27 of the lower fluidized bed furnace 2, and has a dispersion mechanism 8 that is independent of the dispersion (cross section 27).
A connecting pipe 32 that descends from the middle of the lower fluidized bed furnace 2 and a lifting pipe 33 that connects to the bottom of the upper fluidized bed furnace 3 are connected at the same point. Furthermore, the previously described lifting device 9 is provided at the lower part of the lifting pipe 33 at the connection point. This creates the same Bllftg as in the previous embodiment.

To allow the fluidized medium to fall into the lower fluidized bed furnace 2, valve 1
2 and dispersion (can be realized by fluidizing or agitating the descending communication pipe 31 part in number 8, lifting pipe 33,
It falls through the connecting pipe 31.

Further, in order to transport the material to the upper fluidized bed furnace 3, by operating the transport device 9, the material can be transported from the communication pipe 32 through the transport pipe 33.

According to the present invention, the height of the two-part fluidized bed can be adjusted to change the contact area with the heat exchanger tubes to provide the required amount of heat exchange, and the preliminary fluidized bed can be controlled to provide the required amount of heat exchange. Since the fluidized bed is always preheated and maintained at an appropriate temperature, the amount of heat exchange is immediately centrifuged and changed by lifting and lowering with the lifting device, and the amount of generated steam is immediately changed. It is possible to provide a fluidized bed boiler that can be centrifuged and a method for controlling the same, which has two extremely great practical effects.

[Brief explanation of the drawing]

Fig. 1 is a 70-diagram of a conventional example, Fig. 2 is a flow diagram of an embodiment of the present invention, Fig. 3 is a partially enlarged view thereof, and Fig. 4 is a 70-diagram of another embodiment of the present invention. FIG. 13 is a partially enlarged view. 1. Fluidized bed boiler, 2. Lower fluidized bed furnace, 2A. Fluidized bed, 3. Upper fluidized bed furnace, 3A. Fluidized bed, 4. Combustible material supply device, 5. Variable speed motor, 6. Down pipe, 7
... Lifting pipe, 8. Lowering device, 9. Lifting device, 10.
・Heat transfer tube, +1.12.13゜14...Valve, 15
... Lifting nozzle, 16.. Injection nozzle, 17.. Flow rate control valve, 18.. Detector, 19.. Control device, 20.. Concentration detector, 21° 22.. Differential pressure gauge, 23.24.・Temperature detector, 25... Extraction device, 26... Supply device, 27
．． 28.Dispersion mechanism, 29.Grid pipe, 30.
・Dispersion mechanism, 31... Descending communication pipe, 32... Communication pipe, 3
3. Lifting pipe, 41. Fluidized bed furnace, 42. Fluidized bed, 4
3...Heat exchange tube, 44...Combustible material supply device, 45...Flow rate control valve, 4B...Detector, 47...Control device. Patent Applicant Ebara Corporation Representative Patent Attorney Masaru Takagi Sen Yukuma 1) Minoru Takao Maruyama

Claims (1)

[Claims] 1. A lower fluidized bed furnace, and an upper fluidized bed furnace above the lower fluidized bed furnace that uses the gas generated in the lower fluidized bed furnace as a fluidizing gas, the upper fluidized bed furnace comprising: is equipped with a heat exchanger tube for generating steam, a lowering means for lowering the fluidized medium between the upper fluidized bed furnace and the lower fluidized bed furnace, and a lifting means for lifting the fluidized medium, The lowering means and the lifting means are each provided with adjusting means for adjusting the descending amount and lifting amount of the fluidized medium, and the adjusting means adjusts the height of the fluidized bed in the two-part fluidized bed furnace. A fluidized bed boiler characterized by: 2. The descending means includes a downcomer pipe and a lower end of the downcomer pipe (=
3. The fluidized bed boiler according to claim 1, which has a local dispersion (several structures) provided near j. The nozzle mechanism includes a lifting nozzle that provides a flow rate higher than the terminal velocity of the fluid medium, and an adjustment mechanism located below the lifting nozzle that fluidizes the fluid medium around the lifting nozzle to adjust the amount of pumping. The fluidized bed boiler according to claim 1, which has an ejection nozzle as a mechanism. 4. A lower fluidized bed furnace; an upper fluidized bed furnace, the upper fluidized bed furnace is equipped with a heat exchanger tube for generating steam, the upper fluidized bed furnace and the lower fluidized bed furnace are connected by an elevator tube, and the lower end of the elevator tube. In this method, a nozzle mechanism for lifting the fluidized medium is provided, and a supply connecting pipe for supplying the fluidized medium in the lower fluidized bed furnace is provided to the nozzle mechanism. A dispersion mechanism is provided,
A descending communication pipe leading to the lower part of the lower fluidized bed furnace via the dispersion mechanism is provided, and an adjusting means is provided for adjusting the lifting amount and descending amount of the fluidized medium depending on the nozzle mechanism and the dispersion (depending on the structure). , A fluidized bed boiler characterized in that the height of the fluidized bed in the upper fluidized bed furnace is adjusted by the adjusting means. 5. A lower fluidized bed furnace, and above the lower fluidized bed furnace, the lower fluidized bed furnace. A method for controlling an IT dynamic water boiler, comprising: an upper fluidized bed furnace that uses the generated gas of the fluidized bed furnace as a fluidizing gas; the upper fluidized bed furnace is equipped with heat transfer tubes that generate steam; Adjusting the amount of fluidized medium descending from the bed furnace to the lower fluidized bed furnace and/or the amount of heat transfer water pumped from the lower fluidized bed furnace to the upper fluidized bed furnace, A control force method for a fluidized bed boiler, characterized in that the amount of steam generated is controlled by adjusting the height of the fluidized bed.