JP2944696B2 - Fluid fuel burner purge device and purge method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid fuel combustion apparatus, and more particularly to a fluid fuel suitable for preventing a burner nozzle from being clogged by residual oil in a burner when extinguishing a burner for a fluid fuel. The present invention relates to a purge device and a purge method for a burner.

[Prior art] Fluid fuels such as heavy oil, crude oil, CWM, and emulsion are inherently very easy to transport and adjust the flow rate of fluids compared to solid fuels such as pulverized coal. It is used in a wide range of fields. For example, in a plant that uses a large amount of fluid fuel, such as a business boiler for thermal power generation, a large number of fluid fuel burners are used for one boiler. As for operation), each boiler is required to operate in a wide and efficient manner from high load to low load.
DSS operation that repeats stop operation frequently is frequently used.

For this reason, it is common to change the operation load of the entire boiler by changing the fuel flow load of each fluid fuel burner and at the same time by changing the number of used fluid fuel burners, especially in the intermediate load operation. Control of the number of fluid fuel burners accompanied by ignition and extinguishing of the fluid fuel burners is frequently performed.

FIG. 3 is a schematic system diagram of a purge device in a conventional fluid fuel burner.

In FIG. 3, a fuel F passes through a fuel system pipe 4 extending from a fluid fuel pipe 1 through a fluid fuel stop valve 2 to a fluid fuel flexible hose 3 and further through a coupling 5 to a fluid fuel burner 6. It is supplied to the burner nozzle 7.
On the other hand, the steam S, which is the spraying medium, passes through the steam pipe 11 from the steam pipe 8 through the steam stop valve 9 to the steam flexible hose 10, similarly to the fuel F, the coupling 5, and the fluid fuel burner 6. Is supplied to the burner nozzle 7.

A burner nozzle 7 is attached to the tip of the fluid fuel burner 6, and the fuel F and the steam S are mixed in the burner nozzle, atomized and sprayed into the furnace 12.

On the other hand, the steam pipe 8 located upstream of the steam stop valve 9
Is connected to the fluid fuel pipe 1 located on the downstream side of the fluid fuel stop valve 2 through the purge steam valve 14.

On the other hand, the combustion air A is supplied into the furnace 12 through the annular passage 18 between the windbox 15 and the air register 16 and between the blades of the air register 16 and the burner throat 17 located around the burner nozzle 7 to be atomized. The fuel fluid F is mixed with the fluid fuel F and burned in the furnace 12. On the other hand, Windbox 15
A flame detector 19 is installed, and the flame from the burner nozzle 7 in the furnace 12 can be detected and monitored through an annular flow path 18 inside the burner throat 17.

In such a structure, the fluid fuel burner 6 is ignited and in a normal combustion state, the fluid fuel stop valve 2 and the steam stop valve 9 open, and the steam stop valve 9 is located on the upstream side of the steam pipe 8. The purge steam valve 14 provided in the middle of the purge steam pipe 13 connected by the purge steam pipe 13 connecting the fluid fuel pipe 1 to the downstream side of the fluid fuel stop valve 2 is closed. The fluid fuel stop valve 2, the steam stop valve 9, and the purge steam valve 14 are operated remotely by an air cylinder or an electromagnetic drive device (not shown) or by an automatic burner control device. Generally, it is automatically opened and closed by the

Next, when the load is reduced by the DSS operation or the like, it is necessary to increase the number of fire extinguishing fires of the fluid fuel burner 6.

When the number of fire extinguishments of the fluid fuel burner 6 is increased as described above, the supply of the fluid fuel F is stopped by closing the fluid fuel stop valve 2 and the fire of the fluid fuel burner 6 is extinguished.

However, even if the fluid fuel stop valve 2 is closed, the fluid fuel F remaining in the burner nozzle 7 and the fluid fuel burner 6 remains.
Is heated by the radiant heat from the furnace 12 and the heat from the combustion air A in the windbox 15 and finally carbonizes.

Therefore, when the fire of the fluid fuel burner 6 is extinguished, it is necessary to purge the fluid fuel F remaining in the burner nozzle 7 and the fluid fuel burner 6 with the steam S.

When performing this burner purge, the fluid fuel stop valve 2
Is closed and the purge steam valve 14 is opened, or after the fluid fuel stop valve 2 is closed, the purge steam valve 14 is opened. Then, the fluid fuel F remaining in the fluid fuel pipe 1, the fluid fuel flexible hose 3, and the fluid fuel burner 6 downstream of the closed fluid fuel stop valve 2 flows through the purge steam valve 14. The gas is pushed out by the purging steam S from the purging steam pipe 13 and is purged from the burner nozzle 7 into the furnace 12. At this time, since the steam stop valve 9 is open, atomization of the fluid fuel is continuously performed at the burner nozzle 7, and the remaining fluid fuel F is purged while being burned.

When the fluid fuel F remaining in the fluid fuel pipe 1, the fluid fuel flexible hose 3, and the fluid fuel burner 6 is purged, the steam stop valve 9, the purge steam valve is turned on.
14 is closed and the fluid fuel burner 6 is in a fire extinguished state.

[Problems to be Solved by the Invention] In a conventional purging apparatus, a purge steam valve 14 is provided.
And open the fuel line 1 downstream of the fluid fuel stop valve 2.
When purging the fluid fuel in the above, since the operation of the purge steam valve 14 is merely an open-close (ON-OFF) operation, there is a problem that the remaining fluid fuel F cannot be completely purged. That is, in the sectional views of the fluid fuel flexible hose 3 shown in FIG. 4 and the fluid fuel pipe 1 shown in FIG. 5, the flow velocity of the purge steam S in the pipe is usually several m / s to several tens m / s.
On the other hand, since the fluid fuel F is a viscous fluid, it cannot be purged cleanly, and the purge steam passes through the central portion of the fluid fuel pipe 1 and the fluid fuel flexible hose 3 at high speed, and the pipe wall The oil adhering to the pipes forms a cavity while adhering to the pipe wall. In this state, as the viscosity of the fluid fuel F increases, the thickness of the fluid fuel F attached to the pipe wall also increases.

As shown in FIGS. 4 and 5, the fluid fuel F accumulated in the recess of the fluid fuel flexible hose 3 is located around the periphery of the fluid fuel pipe 1 and the purge steam is located at the center. Can not be completely purged.

Therefore, particularly, the fluid fuel F remaining in the fluid fuel burner 6 is carbonized and solidified by the heat received from the surroundings of the fluid fuel burner 6 during fire extinguishing, and is used when the fluid fuel burner 6 is operated again. However, there is a problem that the solid matter separates and clogs the burner nozzle 7.

The present invention seeks to overcome the disadvantages of the prior art, and aims to more completely purge the remaining fluid fuel and to reliably burn the purged fluid fuel in a furnace. It is an object of the present invention to provide a fluid fuel burner purging apparatus and a purging method.

Means for Solving the Problems According to a first aspect of the present invention, there is provided a fuel line for supplying a fluid fuel from a fluid fuel flexible hose through a fluid fuel pipe, And a steam system line supplied from a steam flexible hose via a steam stop valve, and a purge line for supplying a part of the steam of the steam system line to the fuel system line. A fluid pipe provided with a purge steam pipe branched from a steam pipe upstream of a steam stop valve provided in the steam pipe and connected to the fuel pipe as It is intended for a burner purging device.

The fuel system pipe is provided with a fluid fuel three-way valve having a purge steam pipe connected to one side thereof, and a purge steam variable valve is provided in the purge pipe. It is.

According to a second aspect of the present invention, in order to achieve the above object, a fluid fuel is supplied from a fluid fuel flexible hose through a fluid fuel pipe constituting a fuel system pipe, and steam is supplied to the steam pipe, respectively. Comprising steam piping,
The steam is supplied from a steam flexible hose through a steam stop valve, and a part of the steam in the steam line is used as a purge steam when the fluid fuel burner is extinguished. A fluid fuel burner branched from a steam pipe upstream of the stop valve and supplied to the fuel system pipe via a purge steam pipe constituting a purge pipe connected to the fuel system pipe. Of the purging method.

A fluid fuel three-way valve having a purge steam pipe connected to one side is provided in the fuel system pipe, and the fluid stagnant in the fuel system pipe and the burner downstream of the fluid fuel three-way valve is provided. In addition to purging the fuel, a purge steam variable valve is provided in the purge line to perform the purge by changing the purge steam pressure.

[Operation] By changing the pressure of the purge steam by the purge steam variable valve, the relative flow velocity at the boundary surface with the fluid fuel layer remaining on the inner wall surface of the fuel line or in the depression is changed. In addition, separation of the fluid fuel occurs near the boundary layer, and more complete purging can be achieved.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic system diagram of a fluid fuel burner purging apparatus according to an embodiment of the present invention.

In FIG. 1, reference numerals 1 to 19 indicate the same components as those of the prior art.

20 is a three-way valve for fluid fuel, 21 is a steam variable valve for purging, 22
Is a flame detection signal, 23 is a control box, 24 is a valve opening regulator, 25 is a control signal, 26 is control air, and 27 is an open / close signal.

In such a structure, the fluid fuel F is supplied from the fluid fuel pipe 1 through the fluid fuel three-way valve 20, through the fluid fuel flexible hose 3, and further through the coupling 5 to the fluid fuel burner 6. . On the other hand, the steam S, which is the spraying medium, passes through the steam pipe 8, the steam stop valve 9, and the steam flexible hose 10, and likewise, the fluid fuel burner 6.
Supplied to

A burner nozzle 7 is attached to the tip of the fluid fuel burner 6, and the fluid fuel F and the steam S are mixed in the nozzle 7, atomized and sprayed into the furnace 12, and the steam stop valve 9.
Purge steam pipe 13 branched from upstream steam pipe 8
Is connected to one side of a three-way valve for fluid fuel 20 which is formed as a three-way valve through a purge steam variable valve 21. The combustion air A is supplied into the furnace 12 through the annular passage 18 between the wind box 15 and between the blades of the air register 16 and the burner throat 17 around the burner nozzle 7, and is sprayed and atomized. The mixture is mixed with the fluid fuel F and burned in the furnace 12. In the wind box 15, a frame detector 19 is installed, and the furnace 12 passes through an annular flow path 18 of a burner throat 17.
The flame inside can be detected and monitored. Further, the flame detection signal 22 from the frame detector 19 is input to a control box 23, and the control box 23 outputs a flame opening control device 24 of the purge steam variable valve 21 and the three-way valve 2 for fluid fuel.
0, the control signal 25 is also output to the steam stop valve 9. Control air 26 is input from the valve opening regulator 24 to drive the purge steam variable valve 21, and an open / close signal is sent from the control box 23.
27 is output.

In the normal operation state of the fluid fuel burner 6, the three-way valve 20 for the fluid fuel and the stop valve 9 for the steam for the spray vapor are both opened, and the fluid fuel F and the steam S are supplied to the fluid fuel burner 6 and the burner nozzle The atomized fluid fuel F is injected from 7 and burns.

When the operation of stopping the fluid fuel burner 6 is started, first, the purge steam variable valve 21 is opened, and at the same time, the fuel side of the fluid fuel three-way valve 20, which is a three-way valve, is closed and the steam side is opened. At this time, the purge steam variable valve 21 may be opened in advance, but after switching from the fuel side to the steam purge side of the fluid fuel three-way valve 20, the supply of the fluid fuel F is stopped and the flame is extinguished. Therefore, it is not preferable. The purging steam S pushes out the fluid fuel F remaining on the downstream side of the fluid fuel three-way valve 20 from the burner nozzle 7 into the furnace 12, and the space from the fluid fuel three-way valve 20 to the burner nozzle 7 is purged.

Hereinafter, the difference between the conventional purging apparatus shown in FIG. 3 and the purging apparatus according to the embodiment shown in FIG. 1 will be described.

6 (a) and 6 (b) show the characteristics of the purge device of FIG. 3, in which the vertical axis shows the flame detection signal (F) from the frame detector 19, the purge vapor pressure (P), and the horizontal axis. It is a characteristic curve diagram which shows time (t) on an axis.

The point D in FIGS. 6A and 6B is the purge start point,
Point E is the point at which the flame from burner nozzle 7 is about to disappear, F
The points indicate the purge completion points.

In the conventional purge apparatus shown in FIG. 3, the purge vapor pressure is constant from the purge start point D to the purge completion point F as shown by a curve C in FIG. 6B.

On the other hand, the flame detection signal 22 from the flame detector 19 indicates that the fluid fuel F remains in the fuel system pipe 4 as shown by the curve B in FIG. Almost same flame detection signal because similar flame is formed
22 is output. However, at the point E where the steam S passes through the fuel system pipe 4 in the purge system and the flame from the burner nozzle 7 is about to be extinguished, the flame is extinguished, and the flame detection signal 25 from the flame detector 19 also drops to almost zero.

On the other hand, in the purge device shown in FIG.
As shown by a curve H in FIG. 7B, the purge vapor pressure is constant from the purge start point D to the point E where the flame from the burner nozzle 7 is about to disappear, and the purge is completed from the point E where the flame from the burner nozzle 7 is about to disappear. Up to the point F, the purge steam variable valve 21 is gradually closed as shown by the curve H to change the purge steam.

2 (a) and 2 (b) are the same characteristic curve diagrams as FIGS. 6 (a) and 6 (b). FIG. 2 (c) is a characteristic curve diagram in another embodiment of FIG. 2 (b).

When the purge steam variable valve 21 closes the fluid fuel pipe 1 and opens the purge steam pipe 13 at the purge start point D, the steam pressure rises as shown by the curve H in FIG. The pressure becomes constant.

At the point E where the flame from the burner nozzle 7 is about to disappear, as shown by the curve G in FIG. 2A, the purge steam variable valve 21 is reduced. And reduce the purge vapor pressure. When a large amount of steam is ejected from the burner nozzle 7 and the purge ejection amount of the fluid fuel F decreases, the mixture ratio with the fluid fuel F at the outlet of the burner nozzle 7 becomes lean, and the fuel cannot be self-burned. For this reason, the flame shape becomes unstable. Therefore, when the flame detection signal 22 of the frame detector 19 is taken as this change, as shown in a point E in FIG.
The flame detection signal 22 from 19 decreases or fluctuates greatly. When this change occurs, the control box 23 receives a flame detection signal 22 from the frame detector 19 input to the control box 23, and further outputs a control signal 25 from the control box 23 to the valve opening degree regulator 24, thereby changing the purge steam variable. Valve 21
Is gradually closed by the open / close signal 27.

As the purge steam variable valve 21 closes, the purge steam pressure decreases, and the flow rate and flow rate of the purge steam in the fuel system pipeline 4 decrease. As a result, the flow state of the fluid fuel F stagnating in the inner wall and the bottom of the fuel line 4 changes at the boundary surface with the steam S, and the fluid fuel F rides on the low-velocity flow of the steam S so as to ride on the burner nozzle 7. Transported to

Therefore, the blow-off phenomenon of the flame is suppressed due to the decrease in the jet flow velocity due to the decrease in the purge steam amount at the burner nozzle 7, and the fluid fuel F in the fuel system pipe 4 is ejected again from the burner nozzle 7, so that the flame remains in the system. It is maintained until the oil has been purged. Since the flame is formed until the fluid fuel F to be purged almost completely disappears even after the point E at which the flame from the burner nozzle 7 is almost extinguished, the unburned fluid fuel F is not discharged into the furnace 12. Already,
It is also possible to reduce the discharge of unburned matter outside the furnace 12 and the adhesion of unburned matter to a boiler heat transfer tube (not shown), an air preheater located downstream, and the like.

FIG. 2 (c) shows the characteristics of another embodiment of FIG. 2 (b). In the characteristics of FIG. 2 (b), the purge steam variable valve 21 was gradually throttled. In the characteristic shown in FIG. 9C, the purge steam variable valve 21 is gradually reduced.

That is, as shown by the curve I in FIG. 2 (c), when the purge vapor pressure from the point E at which the flame from the burner nozzle 7 is about to disappear to the purge completion point F is reduced in several steps like points J and K. Perform separately. By doing so, the flow velocity of the purge steam changes rapidly, the disturbance of the boundary with the fluid fuel F in the fuel line 4 increases, and the purge effect further increases.

Further, not only the operation of decreasing the pressure as a pressure change but also the repeated increase and decrease of the pressure in the middle of the operation makes the remaining fluid fuel F turbulent, so that the purge effect can be further increased.

[Effects of the Invention] According to the present invention, purge cleaning of fluid fuel can be performed more completely, and carbonization of fluid fuel can be prevented.
The nozzle can be prevented from being clogged when the burner is restarted, and the flame at the time of purging can be stably maintained until the completion of purging, so that the discharge of unburned matter into and out of the furnace can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of a purging apparatus for a fluid fuel burner according to an embodiment of the present invention, and FIGS. 2 (a), 2 (b) and 2 (c) show on the vertical axis a flame detection signal from a frame detector, FIG. 3 is a characteristic curve diagram showing vapor pressure and time on the horizontal axis. FIG. 3 is a schematic system diagram of a purging device in a conventional fluid fuel burner. FIGS. 4 and 5 are fluid hoses for fluid fuel and fluid fuel. FIG. 6 (a), an enlarged sectional view of a pipe;
(B) shows the flame detection signal from the frame detector on the vertical axis,
FIG. 4 is a characteristic curve diagram showing purge vapor pressure and time on a horizontal axis. 1 ... Fluid fuel piping 2 ... Fluid fuel stop valve 3 ...
Flexible hose for fluid fuel, 4 ... fuel line, 6
……………………………………………………………………………………………………………………………………… Building fluids that can be used as steam generators. Steam valve for fluid, 20 ... three-way valve for fluid fuel, 21 ... steam variable valve for purge, F ... fluid fuel, S ... steam.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23D 11/38 F23D 11/18

Claims (2)

(57) [Claims] 1. A fuel system pipe for supplying a fluid fuel from a fluid fuel flexible hose via a fluid fuel pipe, and a steam system pipe for supplying steam from a steam pipe via a steam pipe and a steam stop valve. And a steam stop provided in the steam line as a purge line for supplying a part of the steam of the steam line to the fuel line. In a purging apparatus for a fluid fuel burner provided with a purge steam pipe branched from a steam pipe upstream of a valve and connected to the fuel system pipe, one of the fuel system pipe has purge steam A purging apparatus for a burner for a fluid fuel, comprising a three-way valve for a fluid fuel connected to a pipe, and a variable steam valve for a purge provided in the purge line. 2. Fluid fuel is supplied from a fluid fuel flexible hose via a fluid fuel pipe constituting a fuel system pipe, and steam is supplied from a steam pipe and a steam stop respectively forming a steam pipe. A steam stop valve provided in the steam system pipe while supplying from a steam flexible hose via a valve, and when extinguishing the fluid fuel burner, a part of the steam in the steam system pipe is used as purge steam. A method for purging a fluid fuel burner to be supplied to the fuel system pipe via a purge steam pipe forming a purge pipe connected to the fuel system pipe, branching off from the steam pipe on the upstream side of the fuel system In the fuel system pipeline, a fluid fuel three-way valve having a purge steam pipe connected to one side is provided, and the fuel system pipeline stagnates in the fuel system pipeline and the burner downstream of the fluid fuel three-way valve. Purge fluid fuel Both provided purge steam variable valve conduit for the purge,
A purging method for a burner for a fluid fuel, wherein the purging is performed by changing a vapor pressure for purging.