JP2002081601A - Pressurized fluidized bed boiler apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the furnace wall structure of the combustion furnace of a pressurized fluidized bed boiler housed in a pressure vessel and to reduce the size of the vessel. SOLUTION: The water-cooled walls of the combustion furnace of the pressurized fluidized bed boiler are constituted by alternately combining water-cooled walls composed of ascending-flow water wall pipes 42 and 44 and water-cooled walls composed of descending-flow water wall pipes 42 and 46 with each other. The cross-sectional areas of the flow passages of the water pipes 42 and 46 are set to such values that always make the pressure losses between the upper- end inlets and lower-end outlets of the pipes 42 and 46 larger than the head pressure differences between the upper-end inlets and lower-end outlets of the pipes 42 and 46 during the operation of the boiler. In addition, the heat transferring areas of the pipes 42 and 46 are set to such values that make the enthalpies of fluids at the lower-end outlets of the pipes 42 and 46 lower than saturated enthalpies.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized fluidized-bed boiler apparatus, and more particularly to a furnace wall structure of a pressurized fluidized-bed combustion furnace housed in a pressure vessel.

[0002]

2. Description of the Related Art In a pressurized fluidized-bed boiler, it is known that a furnace wall of a fluidized-bed combustion furnace is constituted by a water-cooled wall tube and heat transfer tubes such as an evaporator tube and a superheater tube are arranged in the combustion furnace. For example, Japanese Unexamined Patent Publication No. 7-127803 discloses FIGS.
1 shows a heat transfer tube disposed in a combustion furnace and a water-cooled wall tube constituting a furnace wall. Further, Japanese Unexamined Patent Publication No.
FIG. 6 shows a system configuration of a pressurized fluidized-bed boiler in which a furnace wall is formed of a water-cooled wall and an evaporator, a superheater, and the like are provided as shown in FIG.

In the fluidized bed combustion furnace disclosed in the above two publications, the water cooling wall constituting the furnace wall is arranged so that the fluid in the pipe flows upward, and the fluid that has exited the outlet at the upper end of the water cooling wall is A large-diameter connecting pipe leads to the lower end of another water-cooled wall.

[0006] The numbers in FIGS. 4, 5, and 6 are the numbers used in the gazette, and are different from the numbers assigned to the embodiments of the present invention described later.

[0005]

Generally, the flow direction of the fluid in the pipe on the furnace wall of a boiler having a water-cooled wall is an upward flow. That is, the water supplied to the water cooling wall is heated by the heat of the combustion furnace while flowing up the water cooling wall with the lower end of the water cooling wall as an inlet, and flows out from the outlet at the upper end of the water cooling wall. This is because the fluid in the pipe is heated in the process of passing through the water cooling wall, the specific weight of the fluid at the outlet is smaller than that at the inlet, and the rising force corresponding to the difference in specific gravity between the inlet and the outlet is the outlet fluid. This is because, when the outlet portion is located upward, the fluid flow in the pipe becomes smoother and the pressure loss can be reduced. This is the same for the water-cooled wall of the pressurized fluidized-bed boiler, and is clear from the examples shown in FIGS. 4, 5, and 6.

By the way, a system configuration is generally adopted in which a water cooling wall constituting a furnace wall is divided into several sections, and a fluid in a pipe passes through the divided water cooling walls in order.
In such a system configuration, in order to make the lower end of the water cooling wall constituting the furnace wall all the inlet side of the in-pipe fluid and make the upper end all the outlet side, the lowering connecting the outlet of the upper end of the water cooling wall and the inlet of the lower end of the water cooling wall is performed. A flow connection pipe is required. In the case of a pressurized fluidized-bed boiler, a space for arranging the communication pipe outside the furnace wall of the combustion furnace and a support member for the communication pipe are required, so that the size of the pressure vessel for accommodating them is increased and accommodated The weight of the member also increases.

Japanese Patent Application Laid-Open No. Hei 6-137504 discloses FIG.
As shown in (1), there has been proposed a structure in which a downflow connecting pipe and a water-cooling wall pipe are integrated to suppress an increase in the size of the pressure vessel. However, this structure requires a complicated supporting structure in order to suppress the thermal stress generated between the large-diameter connecting pipe and the small-diameter water-cooling wall pipe, as described in Japanese Patent Application Laid-Open No. 6-193809. I have.

An object of the present invention is to simplify the structure of a furnace wall of a combustion furnace housed in a pressure vessel of a pressurized fluidized-bed boiler apparatus and to downsize the pressure vessel.

[0009]

Means for Solving the Problems The flow in a part of the water cooling wall pipe is defined as a downward flow, and the furnace wall is constructed by alternately combining the upward cooling water cooling wall and the downward flowing water cooling wall. Fluid in the pipe flows into the lower end of the water cooling wall, passes through the pipe of the water cooling wall in an ascending flow, and guides the fluid in the pipe that has reached the upper end of the water cooling wall to the upper end of another part of the water cooling wall. If the pipe is configured to pass through the downflow, the header at the upper end of the water cooling wall of the ascending flow can be integrated with the header at the upper end of the water cooling wall of the descending flow. Since the header at the lower end of the water cooling wall can be integrated, a connecting pipe for connecting the water cooling wall tube is unnecessary. If the communication pipe is not required, a support structure for supporting the communication pipe is not required, so that the furnace wall is simplified and the pressure vessel can be downsized.

However, when the fluid flows downward in the heated water-cooled wall pipe, the specific weight of the fluid below the water-cooled wall pipe decreases in accordance with the amount of heat received than the specific weight of the fluid above the water-cooled wall pipe. Therefore, an upward force (a force that causes an upward convection) in the direction opposite to the downward flow acts on the fluid.
Therefore, maintaining a downward flow requires a downward flow thrust that is sufficient to overcome the upward force acting on the fluid.

The upward force Fup acting on the fluid is calculated by multiplying the specific weight difference between the upper and lower ends of the water-cooled wall pipe by the vertical dimension H of the water-cooled wall pipe, as shown in equation (1).

Fup = (ρ1−ρ2) · H ‥‥‥ (1) ρ1: Specific weight of the fluid at the inlet of the downflow water-cooled wall pipe ρ2: Specific weight of the fluid at the outlet of the downflow water-cooled wall pipe On the other hand, the downflow Is proportional to the pressure gradient at the upper and lower ends of the water-cooled wall, and is calculated by equation (2).

Fdw = ΔP = K · ρ · (G / A) ² ‥‥‥ (2) ΔP: Pressure gradient of fluid between upper and lower ends of water cooling wall K: Resistance coefficient ρ: Average specific weight of fluid on water cooling wall ( = (Ρ1 + ρ2) /
2) G: Mass flow rate of fluid in the pipe passing through the water-cooling wall A: Cross-sectional area of the flow path of the water-cooling wall pipe In order to form a stable downward flow, the condition of "downward propulsive force">"risingforce", that is, It is necessary that the following equation (3) holds. This means that the pressure drop between the upper and lower outlets of the downflow tube is always greater during boiler operation than the head pressure difference between the upper and lower outlets of the tube.

(G / A) ² > 2 {(ρ1−ρ2) / (ρ1 + ρ2)} · H / K (3) In equation (3), H, K, and A are numerical values determined by the structure of the pipe. ρ1 and ρ2 are numerical values determined by G. Further, H and K are dimensions uniquely determined as dimensions of a body of a fluidized bed combustion furnace required for combustion.

Therefore, as a method for satisfying the expression (3), a method of adjusting the flow path cross-sectional area A by increasing or decreasing the number of water-cooling wall pipes and a method of adjusting the passage flow rate G in the pipes can be used. The function of satisfying the expression (3) is the same, but the method of adjusting the cross-sectional area of the flow path is a measure mainly implemented at the design stage of the equipment. When there is a possibility that the flow may be different from the design stage, the maintenance of the downward flow can be ensured by using a combination of the above method and a method that can be adjusted in operation.

In the above method of adjusting the cross-sectional area A of the downflow of the water cooling wall tube, the total number of the water cooling wall tubes is determined according to the frame size of the pressurized fluidized bed combustion furnace. It may be divided into a plurality of ascending flow water cooling walls and descending flow water cooling walls, and the ascending flow water cooling walls and the descending flow water cooling walls may be arranged alternately. With this configuration, as shown in FIG. 3, the header at the upper end of the water-cooling wall of the rising flow and the header at the upper end of the water-cooling wall of the descending flow can be integrated, and the header at the lower end of the water-cooling wall of the descending flow can be integrated. Since the header at the lower end of the water cooling wall of the flow can be integrated, a connecting pipe for connecting the water cooling wall pipe becomes unnecessary.

The method of adjusting the flow rate G in the pipe requires means for measuring the specific weights ρ1 and ρ2 of the fluid at the inlet / outlet of the water-cooled wall pipe, and means for adjusting the flow rate G accordingly. However, the specific weight of the fluid can be calculated as a physical property value by measuring the temperature and pressure of the corresponding part, and the flow rate can be adjusted by using a flow meter and a control valve in a part of the system. Can be realized. However, the specific weight of the fluid is
In the brackish water mixing region, it cannot be unambiguously calculated based on pressure and temperature, so the fluid state value (enthalpy)
Must be lower than the brackish water mixing region (less than the saturation enthalpy at the corresponding temperature and pressure). The state value (enthalpy) of the fluid at the corresponding part can be easily calculated as a physical property value from the measured values of the pressure and the temperature. The state value (enthalpy) of the fluid flowing through the water cooling wall changes depending on the temperature,
This temperature varies depending on the amount of heat received from the combustion furnace by the water-cooled wall tube, specifically, the heat transfer area. That is, the heat transfer area of the water cooling wall may be set in advance to a value such that the enthalpy of the fluid at the lower end outlet of the water cooling wall is equal to or less than the saturation enthalpy. The temperature of the fluid also depends on the flow rate of the fluid flowing through the water wall tube. If the fluid state value (enthalpy) exceeds the saturation enthalpy, adjust the flow rate of the fluid flowing through the water-cooling wall pipe to a value such that the enthalpy of the fluid at the outlet at the lower end of the water-cooling wall is less than the saturation enthalpy. May be.

That is, a flow in a part of the water-cooling wall pipe is defined as a downward flow, and a water-cooling wall having an upward flow and a water-cooling wall having a downward flow are alternately combined to form a furnace wall. Flow through the pipe of the water-cooled wall in ascending flow, guide the fluid in the pipe reaching the upper end of the water-cooled wall to the upper end of another part of the water-cooled wall, and flow down the pipe of the water-cooled wall. And the heat transfer area of the water cooling wall of the descending flow is set to a value that satisfies the expression (3) at the planning stage. A step of setting a fluid enthalpy at a lower end outlet of the water cooling wall to a value not more than a saturation enthalpy at a stage, and providing a flow rate adjusting means for adjusting a fluid flow rate of the water cooling wall tube to a value satisfying the above formula (3); The enthalpy of the fluid at the lower end outlet of the water cooling wall of the descending flow There comprises flow regulating means for regulating the flow rate of the fluid passing through the water wall to be equal to or less than the saturation enthalpy, by devising such, it is possible to achieve the object.

That is, the above-mentioned problem is to be solved by making the flow in a part of a water-cooling wall pipe forming a water-cooling wall of a combustion furnace of a pressurized fluidized-bed boiler a downflow, and alternately using an upflow watercooling wall and a downflow watercooling wall. And the pressure loss between the upper end inlet and the lower end outlet of the tube, the pressure loss between the upper end inlet and the lower end outlet of the tube, And the heat transfer area of the water cooling wall of the downward flow is set such that the enthalpy of the fluid at the lower end outlet of the water cooling wall is equal to or less than the saturation enthalpy. This can be achieved by setting these values to appropriate values.

[0020] The above-mentioned problem also arises in that the flow in a part of the water-cooling wall tube forming the water-cooling wall of the combustion furnace of the pressurized fluidized-bed boiler is set as a downflow, and the upflow water-cooling wall and the downflow water-cooling wall alternate. To constitute a furnace wall, the pressure loss between the upper end inlet and the lower end outlet of each tube constituting the water cooling wall of the downward flow,
In addition to the flow head pressure difference between the upper end inlet and the lower end outlet of the pipe, a flow rate adjusting means for adjusting the flow rate of the fluid flowing through the pipe is always provided during the boiler operation so as to be always larger. This is achieved by setting the area to a value such that the enthalpy of the fluid at the lower end outlet of the water cooling wall is equal to or less than the saturation enthalpy.

[0021] The above-mentioned problem also arises in that the flow in a part of the water-cooling wall tube forming the water-cooling wall of the combustion furnace of the pressurized fluidized-bed boiler is set as a downflow, and the upflow water cooling wall and the downflow water cooling wall alternate. And the pressure loss between the upper end inlet and the lower end outlet of the tube, the pressure loss between the upper end inlet and the lower end outlet of the tube, Of the fluid passing through the water cooling wall so that the enthalpy of the fluid at the lower end outlet of the water cooling wall of the descending flow is equal to or less than the saturation enthalpy, while being set to a value that is always larger during the boiler operation. This is achieved by providing a flow rate adjusting means for adjusting the flow rate.

[0022] The above-mentioned problem is further solved by making the flow in a part of the water-cooling wall tube forming the water-cooling wall of the combustion furnace of the pressurized fluidized-bed boiler a downflow, and alternately using the upflow watercooling wall and the downflow watercooling wall. To constitute a furnace wall, the pressure loss between the upper end inlet and the lower end outlet of each tube constituting the water cooling wall of the downward flow,
In addition to the flow head pressure difference between the upper end inlet and the lower end outlet of the pipe, a flow rate adjusting means for adjusting the flow rate of the fluid flowing through the pipe is always provided during the boiler operation. By having a flow rate adjusting means for adjusting the flow rate of the fluid passing through the water cooling wall so that the enthalpy of the fluid in the is not more than the saturation enthalpy,
Achieved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a pressurized fluidized-bed boiler device 100A, 100B according to the present invention, a gas turbine 11 driven by combustion exhaust gas discharged from the pressurized fluidized-bed boiler device 100A, 100B, and a gas turbine 11
, A steam turbine 31 driven by steam generated by the pressurized fluidized-bed boiler apparatuses 100A and 100B, and a steam turbine generator 32 driven by the steam turbine 31. Is shown.

The pressurized fluidized-bed boiler 4B of the pressurized fluidized-bed boiler apparatus 100B is accommodated in a pressure vessel 3B, and a fluidized medium 5 constituting a fluidized bed is accommodated in a combustion furnace formed by the water-cooling wall 7. ing. In the fluidized bed, an evaporator 27 connected to the outlet side of the water cooling wall 7 to generate steam and a superheater 30B for heating the generated steam are arranged.

The pressurized fluidized-bed boiler 4A of the pressurized fluidized-bed boiler apparatus 100A is stored in a pressure vessel 3A, and a fluidized medium 5 constituting a fluidized bed is accommodated in a combustion furnace formed by a water cooling wall 6. ing. In the fluidized bed, a superheater 3 that superheats the steam generated in the evaporator 27 and separated in the brackish water separator 28
At 0 A, a reheater 33 for heating the high-pressure turbine exhaust steam of the steam turbine 31 again is arranged. The outlet side of the reheater 33 is connected to the low-pressure turbine of the steam turbine 31.

The outlet of the superheater 30A is connected to the superheater 30B.
The outlet of the superheater 30B is connected to the inlet of the high-pressure turbine of the steam turbine 31. The outlet of the water cooling wall 6 is connected to the inlet of the water cooling wall 7, and the outlet of the water cooling wall 7 is connected to the inlet of the evaporator 27.

In the exhaust flue 14 of the gas turbine 11, a denitration device 15, a high-pressure gas feed water heater 16 and a low-pressure gas feed water heater 17 are arranged in this order.
It is connected to a chimney 20 via a gas feed water heater downstream flue 18. The exhaust gas from the gas turbine 11 is supplied to a denitration device 15
, And the high-pressure gas feed water heater 16 feeds water 25
Then, the exhaust heat is recovered to the condensate water 22 by the low-pressure gas feed water heater 17 and discharged from the chimney 20.

The compressor 1 driven by the gas turbine 11 compresses the sucked air to generate high-pressure combustion air 2, and the generated high-pressure combustion air 2 is supplied to the pressure vessels 3A and 3B.
And burns coal in the fluidized bed of the combustion furnace of each of the fluidized bed boilers 4A and 4B. The combustion gas 8 generated by the combustion is guided to dust removing devices 10A and 10B interposed in the high-temperature gas pipes 9A and 9B, respectively, and drives the gas turbine 11 after the dust is removed. Gas turbine 11
Drives the combined gas turbine generator 12 and compressor 1. The combustion gas that drives the gas turbine 11 becomes a gas turbine exhaust gas 13, is guided to a gas turbine waste flue 14, and flows into a denitration device 15. The gas turbine exhaust gas 13 that has passed through the denitration device 15 heats the feedwater with a high-pressure gas feedwater heater 16 and subsequently heats the condensate with a low-pressure gas feedwater heater 17.

A condenser 38 is attached to the steam turbine 31, and the outlet of the condenser 38 is connected via a condenser pump 21 to the inlet side of the low-pressure gas feed water heater 17 to be heated.
The heated fluid outlet side of the low pressure gas feed water heater 17 is a deaerator 23.
The deaerator 23 is connected to the water supply pump 2
4 is connected to the suction side. The outlet side of the feedwater pump 24 is connected to the heated fluid inlet side of the high-pressure gas feedwater heater 16, and the heated fluid outlet side of the high-pressure gas feedwater heater 16 enters the water cooling wall 6 of the pressurized fluidized-bed boiler 4A. Connected to the side. The liquid phase portion of the steam separator 28 connects the heated fluid outlet side of the high pressure gas feed water heater 16 and the inlet side of the water cooling wall 6 of the combustion furnace of the pressurized fluidized bed boiler 4A via a boiler circulation pump 37. Connected to the pipeline. The superheater 3
A pipe connecting the outlet side of the high pressure turbine to the high pressure turbine inlet side of the steam turbine 31 is provided with a high pressure turbine bypass system 34 in which a high pressure turbine bypass valve 35 and a high pressure turbine bypass cooler 36 are interposed. It is connected to a conduit leading to the reheater 33. In the present embodiment, the water supply pump 24 and the boiler circulation pump 37,
A thermometer and a pressure gauge, not shown, constitute flow rate adjusting means for adjusting the flow rate of the fluid flowing through the water cooling wall.

Next, the water supply and condensate system will be described. The condensate water 22 generated by the condenser 38 is supplied to the condensate pump 2
It is pressurized at 1 and flows into the flow path of the fluid to be heated of the low pressure gas feed water heater 17. The condensed water 22 flowing into the flow path of the fluid to be heated of the low-pressure gas feed water heater 17 is
After the heat of the gas turbine exhaust gas 13 flowing through the flow path of the heating fluid is recovered and its own temperature is raised, it flows into the deaerator 23. Condensate returned from deaerator 23 (hereinafter referred to as water supply)
Is pressurized by the feed water pump 24 and the high pressure gas feed water heater 1
6 flows into the flow path of the fluid to be heated. The feedwater 25 flowing into the flow path of the fluid to be heated of the high-pressure gas feedwater heater 16 recovers the heat of the gas turbine exhaust gas 13 flowing through the flow path of the heating fluid of the high-pressure gas feedwater heater 16 and raises its temperature. After that, it flows into the water cooling wall 6 of the combustion furnace of the pressurized fluidized bed boiler 4A.

As shown in FIG. 2, the water cooling wall 6 is composed of four wall surfaces, and two adjacent wall surfaces are combined to constitute one flow system. That is, the four wall surfaces of the water cooling wall 6 constitute two flow systems. Two wall surfaces which are combined to form one flow system are connected to a first water cooling wall lower header (water cooling wall lower header 3) serving as an inlet of water supply.
9) a first ascending flow water-cooled wall tube (water-cooled wall tube 40) having a lower end connected to the first water-cooled wall lower header, and a first ascending water-cooled wall tube connected to the upper end of the first ascending flow water-cooled wall tube. Water cooling wall upper header (water cooling wall upper header 41); a first descending flow of water cooling wall pipe (water cooling wall pipe 42) having an upper end connected to the first water cooling wall upper header; A second water cooling wall lower header connected to the lower end of the flow water cooling wall pipe (water cooling wall lower header 4
3) a second ascending flow water-cooling wall tube (water-cooling wall tube 44) having a lower end connected to the second water-cooling wall lower header, and a second ascending water-cooling wall tube connected to the upper end of the second ascending flow water-cooling wall tube. Water cooling wall upper header (water cooling wall upper header 45), a second descending flow of water cooling wall pipe (water cooling wall pipe 46) having an upper end connected to the second water cooling wall upper header, A water cooling wall outlet header (water cooling wall outlet header 47) connected to the lower end of the flow water cooling wall pipe is provided. The water cooling wall outlet header is a pressurized fluidized bed boiler 4
B is connected to the water cooling wall 7. The flow path cross-sectional areas of the water-cooling wall pipe 42 and the water-cooling wall pipe 46 are set so as to satisfy Expression (3) at the planning (design) stage.

As shown in FIG. 2, the feed water 25 flowing into the water cooling wall 6 is guided from the water cooling wall lower header 39 to the water cooling wall upper header 41 via the ascending flow of the water cooling wall pipe 40. The water flows into the water cooling wall lower header 43 from the drawer 41 through the descending water cooling wall pipe 42. The feedwater flowing into the water cooling wall lower header 43 is guided to the water cooling wall upper header 45 via the ascending flow water cooling wall pipe 44, and the water cooling wall outlet pipe via the water cooling wall upper header 45 via the descending flow water cooling wall pipe 46. It flows into the shed 47. The feedwater flowing into the water cooling wall outlet header 47 is guided to the water cooling wall 7 of the pressurized fluidized bed boiler 4B, and like the water cooling wall 6,
It passes through a furnace wall composed of water-cooled wall pipes of upflow and downflow.

The water supplied to the water cooling wall 6 is supplied to the two water cooling wall lower headers 39 separately, and the water supplied to the two water cooling wall outlet headers 47 is combined into one and the water cooling wall 7 is supplied. Is to be led to.

The water supplied to the water cooling wall 7 is supplied to the water cooling wall 6.
After passing through a water-cooling wall tube or header constructed in the same manner as above, the temperature is further raised, and then flows out of the water-cooling wall 7, becomes boiler feedwater 26, and is introduced into the evaporator 27. The boiler feedwater 26 introduced into the evaporator 27 evaporates in the evaporator 27 and is introduced into the steam separator 28 to be separated by steam. A boiler circulation pump 37 is connected to the bottom of the brackish water separator 28 with the suction side facing the brackish water separator 28, and the discharge side of the boiler circulation pump 37 is a water-cooled water supply side of the high-pressure gas feedwater heater 16. It is connected to a conduit connecting to the wall 6. That is, after the separated saturated water is pressurized by the boiler circulation pump 37, the feed water 25 heated by the high-pressure gas feed water heater 16 is heated.
And can be introduced again into the water cooling wall 6.

On the other hand, the steam separated by the steam separator 28 is introduced into the superheater 30A of the pressurized fluidized-bed boiler 4A and is superheated.
And overheated. Superheater 30A, Superheater 30B
The steam that has been superheated in the
1 high-pressure turbine. The exhaust steam after driving the high-pressure turbine is supplied to the reheater 3 of the pressurized fluidized-bed boiler 4A.
After being introduced into the steam turbine 3 and reheated, it is supplied to the low-pressure turbine of the steam turbine 31.

Hereinafter, the process from the start of the pressurized fluidized bed boiler to the load operation will be described with reference to FIG. In the start-up process, since the amount of steam generated is smaller than the heat input to the fuel, the saturated water of the steam separator 28 is pressurized by the boiler circulation pump 37 and recirculated to the water cooling walls 6 and 7. By this saturated water recirculation, the flow rate of the fluid passing through the water cooling walls 6 and 7 is increased to maintain the pressure gradient between the upper and lower ends of the water cooling wall pipe necessary for securing the downward flow.
The pressure loss between the upper and lower ends of the water-cooled wall pipe and the specific weight of the fluid required to adjust the circulation flow rate are calculated from a thermometer and a pressure gauge not shown in FIG. 1, and the flow rate of the boiler circulation pump 37 is
It is adjusted by a flow control valve not shown in FIG. If the enthalpy of the fluid, which can be calculated from the temperature and pressure of the water cooling wall, exceeds the saturation enthalpy, the boiler circulation pump 3
Since the flow rate can be reduced to less than the saturation enthalpy by increasing the flow rate of 7, the downward flow can always be maintained at the water-cooled wall during the starting process.

The load rises from the starting process, and the steam separator 2
When the flow rate of the steam separated in 8 increases to a value that can maintain the required pressure loss in the downflow section of the water cooling wall, the boiler circulation pump 37 is stopped, and the water supplied to the water cooling walls 6 and 7 is
The whole is evaporated in the evaporator 27 and heated to a superheated steam state, and the entire amount is supplied to the superheaters 30A and 30B. Since the heat transfer area and the flow path cross-sectional area of the part of the descending flow of the water cooling wall are predetermined so that the fluid enthalpy at the water cooling wall becomes equal to or less than the saturation enthalpy during the load operation, the descending flow is not hindered. Absent. Further, by monitoring the fluid enthalpy calculated from the measured values of the temperature and the pressure of the water cooling wall, and when the fluid enthalpy exceeds the saturation enthalpy, a control circuit for increasing the flow rate of the feedwater pump 24 is provided to change any operating conditions. Even with fluctuations, a stable downward flow can always be maintained by the downwardly flowing water cooling wall.

[0038]

According to the present invention, it is not necessary to provide a large-diameter connecting pipe for connecting the water cooling wall upper header and the water cooling wall lower header and a supporting device for the connecting pipe, thereby simplifying the furnace wall structure. Further, the required space in the pressure vessel is reduced, so that the pressure vessel can be made compact.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a main configuration of a pressurized fluidized-bed boiler according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a flow path configuration of a water cooling wall of the pressurized fluidized-bed boiler in the embodiment shown in FIG.

FIG. 3 is an enlarged front view showing a part of a flow path configuration of a water cooling wall of the pressurized fluidized bed boiler shown in FIG. 2;

FIG. 4 is a system diagram showing an example of the related art.

FIG. 5 is a perspective view showing a flow channel configuration of a water cooling wall of the pressurized fluidized-bed boiler in the prior art shown in FIG.

FIG. 6 is a perspective view showing a flow path configuration of a water cooling wall of a pressurized fluidized-bed boiler according to another example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 High-pressure combustion air 3A, 3B Pressure vessel 4A, 4B Pressurized fluidized-bed boiler 5 Fluid medium 6, 7 Water-cooled wall 8 Fluidized-bed boiler outlet gas 9 High-temperature gas pipe 10 Dedusting device 11 Gas turbine 12 Gas turbine generator 13 Gas turbine exhaust gas 14 Gas turbine exhaust flue 15 Denitrator 16 High pressure gas feed water heater 17 Low pressure gas feed water heater 18 Gas feed water heater downstream flue 19 Gas feed water heater downstream gas 20 Chimney 21 Condensate pump 22 Condensate 23 Deaerator 24 Feedwater pump 25 Feedwater 26 Boiler feedwater 27 Evaporator 28 Steam separator 29 Generated steam 30A, 30B Superheater 31 Steam turbine 32 Steam turbine generator 33 Reheater 34 High pressure turbine bypass system 35 High pressure turbine bypass valve 36 High pressure Turbine bypass heater 37 Boiler circulation pump 8 condenser 39 water wall lower header 40 water wall tube 41 water wall upper header 42 water wall tube 43 water wall lower header 44 water wall tube 45 water wall upper header 46 water wall tube 47 water wall outlet tube pulling

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kenji Higashikawa 6-9 Takara-cho, Kure-shi, Hiroshima Babcock Hitachi Kure Works F-term (reference) 3K064 AA10 AB01 AD05 AF10 BA07 BA17 BA24

Claims (4)

[Claims] 1. A pressurized fluidized-bed boiler having a pressure vessel and a pressurized fluidized-bed boiler housed in the pressure vessel, wherein the pressurized fluidized-bed boiler is formed by arranging pipes in which fluid in the pipes flows vertically. In a pressurized fluidized-bed boiler apparatus provided with a combustion furnace having a wall as a furnace wall, the water-cooling wall includes a rising water-cooling wall in which fluid in the pipe flows upward from below, and a fluid in the pipe upward. And the cross-sectional area of each pipe constituting the descending flow water-cooling wall is determined by the pressure between the upper end inlet and the lower end outlet of the pipe. The heat transfer area of the water cooling wall of the downflow is set so that the loss is always larger during the boiler operation than the head pressure difference between the upper end inlet and the lower end outlet of the pipe. The enthalpy of the fluid at the outlet at the bottom of the wall is saturated. A pressurized fluidized-bed boiler apparatus characterized in that it is set to a value not more than enthalpy. 2. A pressure-cooled fluidized-bed boiler housed in the pressure vessel, wherein the pressurized-fluidized-bed boiler is formed by arranging pipes in which fluid in the pipes flows vertically. In a pressurized fluidized-bed boiler apparatus provided with a combustion furnace having a wall as a furnace wall, the water-cooling wall includes a rising water-cooling wall in which fluid in the pipe flows upward from below, and a fluid in the pipe upward. And the pressure loss between the upper end inlet and the lower end outlet of each tube constituting the descending flow water cooling wall, which is configured to be combined with the upper end inlet of the pipe. A head pressure difference between the lower end outlets, so as to always be larger during the boiler operation, having a flow rate adjusting means for adjusting the flow rate of the fluid flowing in the pipe, the heat transfer area of the water cooling wall of the downward flow, Fluid at the lower end outlet of the water cooling wall Enthalpy is set to a value not more than the saturated enthalpy. 3. A pressure-cooled fluidized-bed boiler housed in the pressure vessel, wherein the pressurized-fluidized-bed boiler is formed by arranging pipes in which fluid in the pipes flows vertically. In a pressurized fluidized-bed boiler apparatus provided with a combustion furnace having a wall as a furnace wall, the water-cooling wall includes a rising water-cooling wall in which fluid in the pipe flows upward from below, and a fluid in the pipe upward. And the cross-sectional area of each pipe constituting the descending flow water-cooling wall is determined by the pressure between the upper end inlet and the lower end outlet of the pipe. The loss is set to a value that is always larger during the boiler operation than the head pressure difference between the upper end inlet and the lower end outlet of the pipe, and the enthalpy of the fluid at the lower end outlet of the water cooling wall of the downward flow is reduced. Less than the saturation enthalpy Further comprising a flow rate adjusting means for adjusting a flow rate of the fluid passing through the water cooling wall. 4. A pressurized fluidized-bed boiler having a pressure vessel and a pressurized fluidized-bed boiler housed in the pressure vessel, wherein the pressurized fluidized-bed boiler is formed by arranging pipes in which fluid in the pipes flows vertically. In a pressurized fluidized-bed boiler apparatus provided with a combustion furnace having a wall as a furnace wall, the water-cooling wall includes a rising water-cooling wall in which fluid in the pipe flows upward from below, and a fluid in the pipe upward. And the pressure loss between the upper end inlet and the lower end outlet of each tube constituting the descending flow water cooling wall, which is configured to be combined with the upper end inlet of the pipe. It is provided with flow rate adjusting means for adjusting the flow rate of the fluid flowing in the pipe so that the head pressure difference between the lower end outlets is always larger during the boiler operation, and the flow rate of the fluid at the lower end outlet of the water cooling wall of the descending flow is provided. Enthalpy is saturated A pressurized fluidized-bed boiler device, comprising: a flow rate adjusting means for adjusting a flow rate of a fluid passing through the water-cooling wall so as to be equal to or less than talpy.