JP2583966B2 - Transformer operation boiler - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable-pressure operation boiler having a vertical water cooling wall, and more particularly to a variable-pressure operation boiler operated from a subcritical pressure to an ultra supercritical pressure (350 kg / cm ² ). It is about.

[Conventional technology]

Large-capacity thermal power plants are being built to meet the rapidly increasing demand for electric power in recent years.However, these boilers must be operated from ultra-supercritical pressure to subcritical pressure in order to obtain high power generation efficiency even at partial load. Is required.

This is one of the characteristics of recent power demand, as nuclear power generation has grown and nuclear power has always been operated at full load for stable operation of electronic power generation, and it has been used for base load. The plant is shifting to a thermal power plant that can handle intermediate loads.

In thermal power plants that carry this intermediate load, few are operated at full load, and the load is 80% load, 50%
Load, increase the load to 25% load, lower the drive,
Stopping operation such as so-called high-frequency start-stop (Daily
Start Stop) operation.

In this way, when thermal power generation increases in partial load operation,
By changing the pressure in accordance with the load, the so-called super-supercritical pressure range for full load, and a sub-critical pressure range for partial load, the power generation efficiency at partial load can be improved by several percent. Can be.

FIG. 3 is a diagram of a water supply system in a conventional constant pressure boiler.

In FIG. 3, reference numeral 1 denotes a water supply main pipe for guiding water supply to the boiler. The water supply main pipe 1 is provided with a water supply control valve 2 for adjusting the amount of water supplied to the boiler.

Water is supplied from the furnace entrance pipe 3 to the water cooling wall pipes 4a to 4d.
Through the manual orifice valves 5a-5d, through the water cooling wall inlet pipes 7a-7d of the water cooling walls 6a-6d to the water cooling pipes 8a-8d, the water cooling wall outlet pipes 9a-9d, the connecting pipes 10a-10d, and the furnace outlet mixing. It flows to the pipe 11 and the connecting pipe 12.

However, conventionally, since the boiler is a constant pressure boiler in a subcritical pressure region or a supercritical pressure region, manual orifice valves 5a to 5d installed in the water cooling wall distribution pipes 4a to 4d can also be used. However, in a variable-pressure operation boiler that changes from the subcritical pressure range to the ultra-supercritical pressure range, the difference in specific volume of steam and saturated water is particularly large in the subcritical pressure range, and even if a small amount of steam is mixed, the water cooling wall 6a
Raise the metal temperature by ~ 6d. For this reason, water cooling wall
Adjust the flow rate with 4a-4d manual orifice valves 5a-5d,
In the manual orifice valves 5a to 5d, it takes time to finely adjust the internal imbalance, and at the same time, cannot follow the ever-changing state quantity change. At the same time, the unstable flow is occupied in the subcritical pressure range.In this state, the opening of the manual orifice valves 5a to 5d is adjusted. The balance is also eliminated, but there is a disadvantage that an unnecessary pressure loss occurs.

Further, in the conventional constant pressure boiler in the subcritical pressure range or the supercritical pressure range, the manual cooling orifice valves 5a to 5d can sufficiently cope with the optimization of the metal temperature of the water cooling pipes 8a to 8d, but in a wide range of pressure transformation. In the vertical water-cooled wall boiler, it is almost impossible to handle the manual orifice valves 5a to 5d.

In addition, in the flow adjustment by the manual orifice valves 5a to 5d of the water cooling wall distribution pipes 4a to 4d at the time of low load, since the supply water flow rate decreases, as shown by the curve B in FIG.
The pressure loss at 5a to 5d is much smaller than the pressure loss at the water cooling walls 6a to 6d shown by the curve A.

[Problems to be solved by the invention]

In the water supply control by the manual orifice valves 5a to 5d of the prior art, when the operation is performed at a low load, the flow rate of the water supply becomes small. Since the pressure becomes smaller in proportion to the square of the flow rate, the pressure loss becomes extremely small at a low load, and it becomes difficult to obtain a stable flow rate.

The present invention seeks to overcome the disadvantages of the prior art,
The purpose is to obtain a variable-pressure operation boiler that can stably distribute the fluid to the water-cooling wall even when the variable-pressure operation boiler is under a low load, and in which the metal temperature of the water-cooling wall is uniform. .

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a furnace water cooling tube having a large heat absorption with a larger tube inside diameter than a furnace water cooling tube with a small heat absorption. is there.

(Operation)

Fluid to the water cooling wall flows uniformly in proportion to the heat load by making the pipe inner diameter of the furnace central water cooling pipe with a large heat absorption, for example, larger than the pipe inner diameter of the furnace peripheral wall water cooling pipe with a small heat absorption, Moreover, the water wall tube metal temperature is also made uniform.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 (a), 1 (b) and 1 (c) relate to an embodiment of the present invention, and FIG. 1 (a) is a schematic system diagram of a variable-pressure operation boiler, and FIGS. 1 (b) and 1 (c). Fig. 2 is a characteristic curve diagram showing the inner diameter of the water wall pipe and the amount of heat absorption at the water cooling wall in Fig. 1 (a), and Figs. 2 (a), (b) and (c) are diagrams showing the inner diameter of the pipe of the water cooling wall. is there.

First, before explaining an embodiment of the present invention with reference to FIGS. 1 (a), (b) and (c), FIGS. 2 (a), (b) and (c) will be described.
The amount of heat absorption of each water cooling wall will be described with reference to FIG.

2 (a) and 2 (b) show cross-sectional views of a boiler furnace, wherein reference numeral 13 denotes a furnace, 14a, 14b, 14c, 14d, 14e, 14f, 14g.
Is a water cooling wall on the front wall side of the boiler, 15a, 15b, 15c, 15d, 15e, 15f,
15g indicates a rear wall-side water-cooling wall, 16a, 16b, 16c, and 16d indicate side-wall-side water-cooling walls, and curves C, D, and E indicate heat absorption amounts in the respective water-cooling walls.

Although not shown, the front wall-side water-cooling wall and the rear wall-side water-cooling wall in FIG. Although not shown in the figure, there is shown a case in which a burner is arranged and one side combustion is performed.

In the case of the opposed combustion shown in FIG.
As shown in the figure, the front wall side water cooling walls 14c, 14d, and 14e have the largest heat absorption, followed by the front wall side water cooling walls 14b and 14f, and the front wall side water cooling wall 1
4a and 14g reduce the heat absorption.

Also on the rear wall and the side wall, the amount of heat absorbed by the water cooling wall located in the central part of the furnace 13 is large, and the amount of heat absorbed by the water cooling wall located on the peripheral wall part of the furnace 13 is small.

The front wall of the one-sided combustion shown in FIG. 2 (b) is almost the same in the case of the opposed combustion shown in FIG. 2 (a), but the rear wall and the side wall are slightly different.

That is, as shown by the curve D on the rear wall, the water cooling wall 14 on the front wall side
As with a and 14g, the heat absorption is reduced.

On the other hand, as shown by the curve E on the side wall, the side wall side water cooling wall 16a,
In 16b, the amount of heat absorption increases, and in the side wall-side water cooling walls 16c, 16d, the amount of heat absorption decreases.

Therefore, in the present invention, as shown by the curve F in FIG. 1B, the water cooling walls 6b and 6 having a large heat absorption in FIG.
The inner diameter of the pipe of c is larger than the inner diameter of the water cooling walls 6a and 6d with less heat absorption, and the inner diameter of the water cooling walls 6a and 6d with less heat absorption is the inner diameter of the water cooling walls 6b and 6c with high heat absorption. It was smaller than that.

As shown in FIG. 4, the decrease rate of the pressure loss of the water cooling walls 6a to 6d is smaller than the decrease rate of the pressure loss of the water cooling wall distribution pipes 4a to 4d (curve B) as shown by the curve A. This is because a stable flow rate can be obtained even under load.

That is, since the flow is stabilized from a high load to a low load, the water wall pipe metal temperature can be kept uniform even when the load changes.

In the case of the opposed combustion shown in FIG. 2 (a), the inner diameter of the water cooling pipes at the front wall side water cooling walls 14c, 14d, 14e and the rear wall side water cooling walls 15c, 15d, 15e is 14.2 mm, and the front wall side The inner diameter of the water cooling pipe in the water cooling walls 14b, 14f, the rear water cooling walls 15b, 15f, the side water cooling walls 16b, 16c is 13.8 mm, the front water cooling walls 14a, 14g, and the rear water cooling wall 1 are provided.
5a, 15g, the inner diameter of the pipe in the water cooling walls 16a, 16d on the side wall is 12.8mm
In this way, the flow state was stable even at low load.

In the case of one-sided combustion shown in FIG. 2 (b), the inner diameters of the water cooling pipes in the front wall side water cooling walls 14c, 14d, 14e and the side wall side water cooling walls 16a, 16b are 14.2 mm, and the front wall side water cooling wall 14b , 14f, the inner diameter of the water-cooled tube is 13.8 mm, the other front-wall-side water-cooled walls 14a, 14g, the rear-wall-side water-cooled walls 15a to 15g, and the side-wall-side water-cooled walls 16c, 16d have a 12.8 mm inner diameter. For example, the flow state of the feedwater flowed stably even at low load.

As described above, in the embodiment of the present invention, the pipe inner diameter of the entire water cooling wall is made uniform by the heat absorption amount of the water cooling wall. However, as shown in FIG. May be changed.

In FIG. 2 (c), reference numeral 17 denotes a burner port in which a not-shown burner is arranged, and reference numeral 18 denotes a water cooling wall having a large heat absorption in FIGS. 1 (a), 2 (a) and 2 (b). Corresponding water cooling wall, 19 is a straight water cooling tube without bending, and 20 is a curved water cooling tube having a bent portion.

As shown in FIG. 2 (c), due to the bending at the burner port 17, the water-cooled tube 20 having a bent portion is about 10 to 20% smaller than the straight water-cooled tube 19 having no bend. If the length is longer and the distribution resistance is larger due to the bent portion, the inside diameter of the water-cooled tube 20 of the bent tube having the bent portion is 14.2 mm,
The inner diameter of the straight water cooling tube 20 without bending may be 12.8 mm.

As described above, the determination of the inner diameter of the water-cooling wall pipe is mainly determined to uniform the temperature distribution of the fluid at the outlet of the water-cooling wall at the time of high-load operation. The effect is great for uniforming the temperature distribution. That is, as shown in FIG. 4, the reduction rate of the pressure loss (curve A) at the water cooling wall due to the load decrease is smaller than the reduction rate of the pressure loss (curve B) at the water cooling wall distribution pipe orifice valve. Therefore, the pressure loss of the entire furnace does not decrease significantly. As a result, a fluid flow distribution suitable for each heat load can be stably obtained through the entire load, so that there is an effect that the temperature distribution of the metal wall of the water-cooled wall tube is kept uniform.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, even if it is a low load, since the flow distribution can be adjusted according to a heat load, even at the time of a low load, a water supply can be made to flow substantially uniformly, and the water-cooled wall pipe metal temperature distribution can be made uniform.

[Brief description of the drawings]

FIG. 1 (a) is a schematic system diagram of a variable-pressure operation boiler according to an embodiment of the present invention, and FIGS. 1 (b) and 1 (c) show water wall tube inner diameters and heat loads in the water cooling wall of FIG. 1 (a). 2 (a), 2 (b) and 2 (c) are diagrams for explaining the inner diameter of the pipe of the water cooling wall, FIG. 3 is a schematic system diagram of a conventional constant pressure operation boiler, and FIG.
The figure is a characteristic curve showing the relationship between pressure loss and load. 8b, 8c, 20: water cooling tubes with large heat absorption, 8a, 8d, 19: water cooling tubes with low heat absorption.

Claims (1)

(57) [Claims] 1. A method for supplying water to a water cooling wall formed by a furnace water cooling tube having a large heat absorption amount and a furnace water cooling tube having a small heat absorption amount and heating the water supply, wherein the heat absorption amount is large. A transformer-operated boiler characterized in that the inner diameter of the furnace water cooling tube is larger than the inner diameter of the furnace water cooling tube having less heat absorption.