JPH09112819A - Purge device for slurry fuel nozzle for pressured fluidized bed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To slowly and approximately completely suck slurry fuel, having high viscosity, remaining in a nozzle body to a tank for purge and effect purging by a method wherein a pressure is regulated so that a pressure in a tank for purge is decreased to a value slightly lower than a pressure in a boiler body during the stop of a pressure fluidized bed boiler. SOLUTION: When operation of a fluidized bed boiler 2 is stopped, a cutoff valve 31 is shifted to a closing state. Further, in such a state that an inlet valve 36 and an outlet valve 39 are left closed, a feed flow rate regulation valve 40 is opened and pressure air 42a from a pressure air source 42 is fed to a tank 37 for purge. When a pressure in the tank 37 for purge is regulated to a value approximately equal to a pressure in the boiler body 3, a feed flow rate regulating valve 40 is closed and the inlet valve 36 is opened. Consecutively, the opening of a discharge flow rate regulating valve 43 is regulated so that a pressure in the tank 37 for purge is adjusted to a value slightly lower than a pressure in the boiler body 3. By the pressure difference, slurry fuel 8, having high viscosity, remaining in the nozzle body 25 is sucked in the tank 37 for purge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slurry fuel nozzle purging device for supplying a slurry fuel (a mixture of pulverized coal, lime and water) into a boiler body of a pressurized fluidized bed boiler. is there.

[0002]

BACKGROUND OF THE INVENTION Figures 3 and 4, there is shown an example of a pressurized Doso boiler, pressure inside is in a pressurized atmosphere by pressurized air a (e.g. 11 Kg / cm ² or so) vessel 1 is provided with a fluidized bed boiler 2 (furnace). This fluidized bed boiler 2 takes in pressurized air a in a pressure vessel 1 into an inner lower portion of a boiler main body 3 by an air diffusion duct 4 and moves upward. A plurality of air diffusers 5 for jetting are provided, and a heat transfer tube 6 in which water flows inside is disposed above the air diffuser 5 inside the boiler body 3, and further, a side wall 3a of the boiler body 3 and a pressure vessel 1 are provided. A plurality of slurry fuel nozzles 9 are provided on the upper side of the diffuser pipe 5 so as to supply the slurry fuel 8 from the fuel injection port 7 and extend in the lateral direction. Each slurry fuel nozzle 9 is connected to a slurry fuel supply device 10 for supplying a slurry fuel 8 obtained by mixing pulverized coal and a liquid such as water.

A bed material 11 in which sand or combustion ash is mixed with a desulfurization material such as limestone is supplied to the upper side of the air diffusion tube 5, and the bed material is supplied by the pressurized air a supplied from the air diffusion tube 5. 11 is fluidized to form a fluidized bed 12.

Further, a combustion exhaust gas discharge pipe 13 is provided on the upper part of the boiler body 3, and a plurality of cyclones 15 are connected to the combustion exhaust gas discharge pipe 13 via a branch duct 14 to each cyclone 15. The combustion exhaust gas b after the dust is collected is sent to the gas turbine 16 to drive the gas turbine 16. An air compressor 17 and a gas turbine generator 18 are connected to the gas turbine 16 so that the pressurized air a obtained by driving the air compressor 17 is supplied into the pressure vessel 1, and The surplus power of 16 drives the gas turbine generator 18. In the figure, 20 is an ash extraction pipe for taking out the ash separated by each cyclone 15 to the outside of the pressure vessel 1 via the ash cooler 21, and 22 is a bed material taking-out pipe for taking out the excess bed material 11 in the boiler body 3 downward. Is.

In the pressurized fluidized bed boiler configured as described above, pressurized air a is sent from the air diffuser 5 into the boiler main body 3 to cause the bed material 11 to flow and form the fluidized bed 12.
The slurry fuel 8 is supplied from the slurry fuel nozzle 9 into the fluidized bed 12, and the slurry fuel 8 is burned while stirring the pressurized fuel a in the fluidized bed 12 to heat the water in the heat transfer tube 6 to generate steam. I am trying to let you.

As shown in FIG. 6, the slurry fuel nozzle 9 is provided with a nozzle body 25 having a fuel passage 23 inside and a fuel injection port 7 formed at a tip end thereof through a throttle portion 24, and Outside the pressure vessel 1 of the nozzle body 25 penetrating the side wall 3a of the boiler body 3 and the pressure vessel 1, the dispersion air pipe 2 penetrating the peripheral wall of the nozzle body 25.
6 is provided, and a rear end of the dispersed air pipe 26 communicates with the dispersed air pipe 26, and a dispersed air nozzle 27 provided at the axial center portion of the fuel passage 23 of the nozzle body 25 extends toward the tip of the nozzle body 25. An air injection port 28 is formed near the boundary between the fuel passage 23 and the throttle 24. As shown in FIG. 3, the outer end portion of the dispersion air pipe 26 is connected to a dispersion air source 30 provided outside the pressure vessel 1 for supplying dispersion air 29.

The slurry fuel 8 and the like produced by mixing crushed coal with water has a low fluidity. Therefore, when it is supplied into the boiler body 3 through the slurry fuel nozzle 9, the fluidized bed 12 of the boiler body 3 is supplied. It is difficult to disperse inside. For this purpose, the dispersion air 29 from the dispersion air source 30 is supplied to the dispersion air nozzle 27 provided in the nozzle body 25 via the dispersion air pipe 26, and the air injection port 28 at the tip of the dispersion air nozzle 27 is supplied. By injecting dispersion air 29 from the fuel passage 23 into the boiler main body 3 to mix the slurry fuel 8 in the throttle portion 24, and injecting the fuel from the fuel injection port 7 into the boiler main body 3 to disperse it. Therefore, the slurry fuel 8 is burned uniformly.

Outside the pressure vessel 1 in the nozzle body 25, as shown in FIG. 5, shutoff valves 31 and three for shutting off the supply of the slurry fuel 8 when the operation of the fluidized bed boiler 2 is stopped. Direction switching valve 32 is installed,
The one port of the three-way switching valve 32 allows the slurry fuel 8 in the slurry tank 33 to pass through the slurry pump 34 and the slurry supply pipe 34.
and the slurry tank 33 is provided at the other one port of the three-way switching valve 32.
The circulation fuel pipe 34b is connected to the slurry fuel supply device 10.

Further, when the operation of the fluidized bed boiler 2 is stopped, the slurry fuel 8 in the nozzle body 25 is solidified by the high temperature residual heat in the boiler body 3, and the nozzle body is restarted when the fluidized bed boiler 2 is restarted. Slurry fuel 8 solidified in 25
In order to prevent the problem that the slurry fuel 8 cannot be supplied due to being blocked by the high pressure gas 35a from the high pressure gas source 35 between the shutoff valve 31 and the slurry fuel supply device 10, a switching valve is provided. The high-pressure gas supply pipe 35c supplied via 35b is connected.

In the operating state of the fluidized bed boiler 2, the shut-off valve 31 and the three-way switching valve 32 are switched to the direction in which the slurry fuel 8 can be supplied as shown in FIG. The fuel 8 flows in the nozzle body 25, is dispersed by the dispersing air 29 from the dispersing air pipe 26, and is supplied from the fuel injection port 7 onto the air diffuser pipe 5 in the boiler body 3.

When the operation of the fluidized bed boiler 2 is stopped, the supply of the slurry fuel 8 by the slurry fuel supply device 10 is stopped, but even if the supply of the slurry fuel 8 by the slurry fuel supply device 10 is stopped, the nozzle body The inside of 25 is filled with the slurry fuel 8, and if it is left as it is,
The slurry fuel 8 is solidified by the high temperature residual heat in the boiler body 3.

Therefore, after the three-way switching valve 32 is rotated 180 ° from the state of FIG. 5 to shut off the slurry fuel nozzle 9, the switching valve 35b is opened and the high pressure gas 35a from the high pressure gas source 34 is supplied to the nozzle body. By supplying within 25,
The slurry fuel 8 remaining in the nozzle body 25 is supplied to the fuel injection port 7
From the above, the purging for discharging the boiler body 3 is performed.

[0013]

However, since the inside of the fluidized bed boiler 2 is under a pressurized atmosphere of, for example, about 10 kg / cm ² , this pressure is overcome and the nozzle body 2 is overcome.
In order to push out the highly viscous slurry fuel 5 of No. 5, it is necessary to supply the gas 35a having a very high pressure from the high pressure gas source 34, and even if the high pressure gas 35a is supplied, the slurry fuel in the nozzle body 25 is supplied. It is difficult to completely discharge 8 and the slurry fuel 8 remains at the bottom of the nozzle body 25 and solidifies due to the high temperature residual heat in the boiler body 3.

When the gas turbine 16 shown in FIG. 3 trips, the operation of the pressurized fluidized bed boiler is urgently stopped. In such an emergency stop, the boiler main body 3 which is in a flowing state. Since the bed material 11 inside falls and accumulates on the diffuser pipe 5 (referred to as slump), it is impossible to push out the accumulated bed material 11 and push out the slurry fuel 8 in the nozzle body 25 by the high pressure gas 35a. Therefore, the slurry fuel 8 in the nozzle body 25 could not be removed (purged) during the emergency stop of the pressurized fluidized bed boiler.

In view of the above situation, the present invention provides a purging device for a slurry fuel nozzle of a pressurized fluidized bed boiler which can easily and reliably purge slurry fuel in the nozzle body when the pressurized fluidized bed boiler is stopped. It is intended to be provided.

[0016]

SUMMARY OF THE INVENTION A purging device for a slurry fuel nozzle of a pressurized fluidized bed boiler according to the present invention has a fuel injection port inside a boiler body and a shutoff valve outside the pressure vessel, and is provided with a slurry fuel supply device. Is a purging device for a slurry fuel nozzle of a pressurized fluidized bed boiler, which is configured to supply the slurry fuel into the boiler main body through an inlet valve below a position close to the shutoff valve on the tip side of the nozzle main body. Connected to the purge tank, a discharge port formed on the lower side of the purge tank, an outlet valve provided at the discharge port, and a supply flow rate control valve connected to the purge tank. With a tube,
A gas discharge pipe provided with an exhaust flow rate control valve and connected to the purge tank, a level meter for detecting the level of slurry fuel in the purge tank, and a pressure gauge for detecting the pressure in the purge tank. And a pressure gauge for detecting the pressure in the boiler body.

Further, it is characterized in that a differential pressure gauge for detecting the differential pressure between the purge tank and the boiler main body is provided instead of the pressure gauge.

According to the present invention, a purging tank is connected below the position close to the shutoff valve on the tip side of the nozzle body through the inlet valve, and the outlet valve is connected to the discharge port formed under the purging tank. The pressure gas supply pipe equipped with the supply flow rate control valve is connected to the purge tank, and the gas discharge pipe equipped with the discharge flow rate control valve is connected to the purge tank to detect the pressure in the purge tank. By having a pressure gauge that detects the pressure inside the boiler body,
When the pressurized fluidized bed boiler is stopped, the pressure in the purging tank is adjusted to be slightly lower than the pressure in the boiler main body, so that the highly viscous slurry fuel remaining in the nozzle main body is slowly removed. The purging of the slurry fuel in the nozzle body is completed because it is possible to almost completely suck it into the purging tank for purging, and the level meter that detects the level of the slurry fuel in the purging tank is equipped. You can detect what you have done.

If a differential pressure gauge for detecting the differential pressure between the purge tank and the boiler main body is provided, the pressure difference between the pressure in the boiler main body and the pressure in the purge tank is adjusted. The work can be easily performed based on the differential pressure of the differential pressure gauge.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a purging device for a slurry fuel nozzle of a pressurized fluidized bed boiler according to the present invention, in which a fuel injection port 7 opens inside a boiler body 3 and the outside of the pressure vessel 1 is shown. A purging tank 37 is connected and arranged via an inlet valve 36 below the position of the nozzle body 25 having the shutoff valve 31 close to the shutoff valve 31. A discharge port 38 is formed below the purging tank 37, and an outlet valve 39 is installed at the discharge port 38.

At the upper outer periphery of the purging tank 37,
One end of a pressure gas supply pipe 41 provided with a supply flow rate control valve 40 is connected, and the other end of the pressure gas supply pipe 41 is connected to the pressure gas source 4
Connect to 2. Further, one end of a gas discharge pipe 44 having a discharge flow rate control valve 43 is connected to a position near the connection position of the pressure gas supply pipe 41 of the purge tank 37, and the other end of the gas discharge pipe 44 is connected. Is open to the atmosphere.
The gas discharge pipe 44 may be connected to one end side of the pressure gas supply pipe 41 connected to the purge tank 37 without connecting to the purge tank 37.

A level meter 45 for detecting the level of the slurry fuel 8 in the purging tank 37 is attached to the purging tank 37.

Further, a pressure gauge 46 for detecting the internal pressure of the purge tank 37 and a pressure gauge 47 for detecting the internal pressure of the boiler body 3 are installed.

Next, the operation of the above embodiment will be described.

According to the present embodiment, in the operating state of the fluidized bed boiler 2, as shown in FIG. 2, the shutoff valve 31 is switched to the direction in which the slurry fuel 8 flows (the open state), and The inlet valve 36 of the purging tank is in a closed state, and the slurry fuel 8 from the slurry fuel supply device 10 is
Flows in the nozzle body 25, is dispersed by the dispersing air 29 from the dispersing air pipe 26, and is supplied from the fuel injection port 7 onto the air diffuser pipe 5 in the boiler body 3.

On the other hand, when the operation of the fluidized bed boiler 2 is stopped, the supply of the slurry fuel 8 by the slurry fuel supply device 10 is stopped, but even if the supply of the slurry fuel 8 by the slurry fuel supply device 10 is stopped, The nozzle body 25 is filled with the slurry fuel 8, and if left as it is, the slurry fuel 8 is solidified by the high temperature residual heat in the boiler body 3.

For this reason, as shown in FIG.
Is rotated 90 degrees to switch to the closed state.

Further, while the inlet valve 36 and the outlet valve 39 are closed, the supply flow rate control valve 40 is opened to supply the pressure gas 42a from the pressure gas source 42 into the purging tank 37, and the pressure gauge 47. The opening degree of the supply flow rate control valve 40 is adjusted so that the pressure in the boiler main body 3 detected by the pressure gauge and the pressure in the upper portion of the purge tank 37 detected by the pressure gauge 46 become substantially equal. At this time, the pressure in the purging tank 37 may be substantially equal to or slightly lower than the pressure in the boiler body 3, so that the pressure of the pressure gas 42a of the pressure gas source 42 is the same as the pressure in the boiler body 3. It only needs to have a certain pressure.

When the pressure in the purging tank 37 becomes substantially equal to the pressure in the boiler body 3, the supply flow rate control valve 40 is closed and the inlet valve 36 is opened.

Subsequently, the discharge flow rate control valve 43 is opened slightly, and the pressures detected by the pressure gauges 46 and 47 are observed, and the pressure in the purge tank 37 is slightly lower than the pressure in the boiler body 3. The discharge flow rate control valve 43 so as to maintain the pressure.
Adjust the opening of.

Then, the highly viscous slurry fuel 8 remaining in the nozzle body 25 is slowly sucked into the purging tank 37 due to the pressure difference.
At this time, since the purging tank 37 is connected to the lower side of the nozzle body 25, the slurry fuel 8 does not remain at the bottom of the nozzle body 25 and is almost completely discharged into the purging tank 37. (Purged).

Since the amount of the slurry fuel 8 remaining in the nozzle body 25 can be calculated based on the inner diameter and the length of the nozzle body 25, the purging tank 37
Completion of purging can be detected by the detection value of the level meter 45 provided in the above.

When the purging operation is completed, the inlet valve 36 is closed and the outlet valve 39 is opened to open the purging tank 37.
The internal slurry fuel 8 is discharged to the outside. At this time, when the discharge is difficult, the pressure gas 42a of the pressure gas source 42 can be supplied while being supplied to the purge tank 37.

FIG. 2 shows a case where a differential pressure gauge 48 for detecting the differential pressure between the purge tank 37 and the boiler main body 3 is provided instead of installing the pressure gauges 46 and 47. There is.

In the configuration of FIG. 2, the pressure difference between the pressure in the boiler body 3 and the pressure in the purging tank 37 can be immediately read by the differential pressure gauge 48, so that the supply flow rate is maintained so as to maintain the required differential pressure. The work of adjusting the opening degree of the control valve 40 can be easily performed.

It should be noted that the slurry fuel 8 described above can be applied to cases other than a mixture of crushed coal, lime and water, and various changes can be made without departing from the scope of the present invention. Of course.

[0038]

In the purging device for the slurry fuel nozzle of the pressurized fluidized bed boiler of the present invention, the purging tank is connected via the inlet valve below the position near the shutoff valve at the tip of the nozzle body. An outlet valve is provided at the discharge port formed on the lower side of the purging tank, and a pressure gas supply pipe having a supply flow rate control valve is connected to the purging tank, and a gas discharge having a discharge flow rate control valve is provided. Connect the tubing to the purging tank,
By having a pressure gauge that detects the pressure in the purge tank and a pressure gauge that detects the pressure in the boiler body, the pressure inside the boiler body is more than the pressure inside the boiler body when the pressurized fluidized bed boiler is stopped. By adjusting the pressure so that the pressure becomes slightly lower, the highly viscous slurry fuel remaining in the nozzle body can be slowly and almost completely sucked into the purging tank for purging. The provision of the level meter for detecting the level of the slurry fuel in the tank for fuel has an excellent effect of being able to detect the completion of the purging of the slurry fuel in the nozzle body.

If a differential pressure gauge for detecting the differential pressure between the purge tank and the boiler main body is provided, the pressure difference between the pressure inside the boiler main body and the pressure inside the purge tank is adjusted. The work can be easily performed based on the differential pressure of the differential pressure gauge.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a purging device for a slurry fuel nozzle of a pressurized fluidized bed boiler of the present invention.

FIG. 2 is a side view showing another embodiment of the present invention.

FIG. 3 is a schematic vertical sectional view showing an example of a pressurized fluidized bed boiler.

4 is a view taken in the direction of arrows IV-IV in FIG. 3;

FIG. 5 is a side view showing an example of a conventional slurry fuel nozzle purging device.

FIG. 6 is a cut side view showing an example of a slurry fuel nozzle.

[Explanation of symbols]

 1 Pressure Vessel 3 Boiler Main Body 7 Fuel Jet 8 Slurry Fuel 10 Slurry Fuel Supply Device 25 Nozzle Main Body 31 Shutoff Valve 36 Inlet Valve 37 Purging Tank 38 Discharge Port 39 Outlet Valve 40 Supply Flow Rate Control Valve 41 Pressure Gas Supply Pipe 43 Discharge Flow Rate Control valve 44 Gas exhaust pipe 45 Level gauge 46 Pressure gauge 47 Pressure gauge 48 Differential pressure gauge

Claims (2)

[Claims] 1. A slurry of a pressurized fluidized bed boiler having a fuel injection port inside the boiler main body and a shutoff valve outside the pressure vessel to supply the slurry fuel from the slurry fuel supply device into the boiler main body. A purging device for a fuel nozzle,
A purging tank connected via an inlet valve to a lower side of the nozzle main body near the shutoff valve, a discharge port formed on the lower side of the purge tank, and an outlet valve provided at the discharge port. A pressure gas supply pipe having a supply flow rate control valve connected to the purge tank, a gas discharge pipe having a discharge flow rate control valve connected to the purge tank, and a slurry in the purge tank. A level gauge for detecting the fuel level, a pressure gauge for detecting the pressure in the purging tank,
A purging device for a slurry fuel nozzle of a pressurized fluidized bed boiler, comprising: a pressure gauge for detecting the pressure inside the boiler body. 2. A slurry for a pressurized fluidized bed boiler according to claim 1, further comprising a differential pressure gauge for detecting a differential pressure between the purge tank and the boiler body, instead of the pressure gauge. Fuel nozzle purging device.