JPS63194110A - Once-through boiler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combined circulation type supercritical pressure constant king once-through boiler, and to an improvement in its starting system.

BACKGROUND OF THE INVENTION FIG. 3 shows a diagram of a conventional combined circulation type free flow boiler system.

First, the steady operating state of a conventional once-through boiler will be explained.

Boiler feed water is supplied from the deaerator 1 to the energy saver 4 through the high-pressure feed water heater 3 by the feed water pump 2. At low loads, the outlet feed water of the economizer 4 is mixed with the recirculated water of the furnace water-cooled wall 6 and reaches the furnace water-cooled wall 6 via the can water circulation pump 5 . During steady operation, the outlet fluid of the furnace water-cooled wall 6 is supplied to the low-temperature superheater 9 through the boiler, the casing '4f7, and the bypass valve 8 that connects the boiler, which are connected in parallel, and are fully open. It becomes superheated steam. The steam that encounters the low-temperature superheater 9 is supplied to the desuperheater 10, where it is mixed with the feed water that exits the feed water pump 3 and is supplied through the water injection pipe 30 branched from the inlet side of the energy saver 4 to form steam. The temperature is controlled to a desired temperature, and then the high temperature superheater 11 reaches the rated temperature. The steam leaving the high-temperature superheater 11 passes through the blocking valve 12 and is supplied to the turbine 13, where the steam is reduced in temperature by doing work, and the constant steam becomes water in the condenser 14 and then passes through the deaerator 1 again. The water is then supplied to the boiler.

In addition, in the above-mentioned steady operation state, the starting bleed valve 15, the drain valve 17, and the starting pressure system @ff1 described below are
8. Starting air supply W-19, turbine bypass W-20
etc. are closed.

`rK, the startup operation of a conventional once-through boiler will be explained.

In a combined circulation type once-through boiler, at startup, the boiler throttle box 7 and bypass box 8 are fully closed, a fixed amount of feed water equivalent to 5 to 10% load is supplied to the furnace water-cooled wall 6, and the startup bleed valve 15 is closed. By controlling the pressure of the water-cooled furnace *6, the pressure is maintained at a constant supercritical pressure (2460
2y). The feed water that has exited the startup bleed valve 15 is transferred from the steam/water separator 16 to the condenser 14 via the drain valve 17.
leaks to.

At the point of ignition, the steam separator 16 and the superheater 9,]
] system is at atmospheric pressure, but after ignition, as the temperature of the outlet fluid of the furnace water cooling (6) rises, steam is generated in the steam/water separator 16 and pressure rise begins.

The steam generated in the steam/water separator 16 is
The superheater 9.11 passes through the starting air supply valve 19 while being controlled to a low constant pressure (approximately 7 ir/crn2) by
The attemperator 10 and the main steam pipe connecting these are heated. The steam cooled by heating the main steam pipe and the like is discharged to the water pump 14 through the turbine bypass tank 20 together with the generated drain.

When the heating of the main steam pipe is finished, the turbine
0 is closed, the stop box 12 is opened, and the turbine 13 is ventilated. If the steam generated in the boiler after ventilation reaches the specified amount,
Turbine 13 begins to rotate.

Figure 2 is a water/steam phase diagram, showing that the outlet fluid temperature of the water-cooled wall 6 of the furnace, which is maintained at supercritical pressure (about 246 N/cm2t), is at low pressure (about 70K!/(7)21). If the temperature rises to dry steam (approximately 415°C) at the inlet of the operating superheater 9, the steam separator 1
6 indicates that no condensate is generated.

When no condensate is generated, close the startup bleed valve 15, open the boiler throttle bypass valve 8, and open the boiler throttle V-sho 7 to maintain the pressure of the furnace water cooling ki6 at a constant pressure.
At approximately 30% load, the load begins to increase in order to increase the superheater pressure to the same rated pressure (approximately 246 Ky/cm2y) as the furnace pressure.

During pressurization, when the superheater pressure is below the subcritical pressure, the temperature of the fluid at the outlet of the furnace water-cooled wall must be maintained so that the superheater artificial steam becomes dry steam. When the boiler bypass square 8 is fully open, the boiler bypass square 7 is fully open, and the superheater pressure reaches the rated value, the steam temperature control wholesaler 5P
21 is used to supply water from the water injection pipe 30 to the desuperheater 10, and a constant pressure once-through operation is started while controlling the steam temperature.

Note that when stopping, the operation is the reverse of starting, but the idea is basically the same.

Problems to be Solved by the Invention The conventional once-through boiler 'L as described above has the following 4I'
1 "6". In order to avoid temperature imbalance at the outlet, it is necessary to raise the temperature of the furnace water-cooled wall outlet fluid until the superheater artificial steam becomes dry, but the amount of fuel input is Because it is restricted,
Rapid startup was difficult.

(2) Similarly, when using a design fuel (for example, a fuel with poor heat absorption in the furnace (such as natural gas) that is different from a direct oil tank) to prevent excessive rise in the temperature of the main steam, the temperature of the fluid at the outlet of the furnace water-cooled wall increases. In some cases, the boiler could not be started due to insufficient steam, and the boiler could not be started by switching from the boiler startup bleed valve to the boiler throttle bypass valve.゛(3) Superheater pressure increase and load after switching to the boiler throttle bypass valve Even during the rising process, the fluid temperature at the outlet of the water wall of the furnace must be controlled in order to keep the superheater inlet steam dry under subcritical pressure conditions. Therefore, depending on the load rise rate and the difference in fuel, the superheater outlet steam temperature may be regulated. There were cases where the value was exceeded.

Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, a water injection pipe is branched from the water supply pipe on the downstream side of the water supply pump, and this water injection pipe is provided in the middle of the steam pipe. In a once-through boiler connected to a desuperheater, a second water injection pipe is branched from the middle of a drain pipe connected to a steam-water separator to which heating fluid from the outlet of the furnace water-cooled wall is supplied. A once-through boiler is provided in which a water injection pipe is connected to the attemperator.

Effect: According to the above means, the startup system can be used even during the pressure increase and load increase process of the superheater system after ventilation to the turbine and the start of power generation, and the drain separated by the steam separator can be used to exit the low-temperature superheater. By mixing the superheated steam with the superheated steam, it is possible to obtain a main steam flow rate that is almost equal to the artificial water supply flow rate of the energy saver. Rapid startup is possible.

Actual case An embodiment of the present invention will be described in detail below.

FIG. 1 is a system diagram of an embodiment of a once-through boiler according to the present invention, and the same parts as those of the conventional combined circulation type once-through boiler shown in FIG. 3 are given the same reference numerals. The description of this will be omitted, and the characteristic parts of the present invention that are different from those in FIG. 3 will be described.

First, in this example, conventional boiler throttling! The boiler throttle bypass box 8, which was connected in parallel to the 11 valve 7, was changed to be connected in parallel to the boiler startup bleed valve 15. A water injection pipe 32 is branched from the drain pipe 31 of the steam separator 16, and its tip is connected to the desuperheater 10 via the superheater water injection valve 22.

1f! The drain pipe 31 is connected to the deaerator 1 via the deaerator inlet drain valve 23 on the upstream side of the drain valve 17.

In the once-through boiler of the present invention having such a groove bottom, the operations from ventilating the turbine to starting power generation are the same as those of the conventional combined circulation plasma flow boiler, so the subsequent operations will be explained.

After the start of power generation in the turbine 13, in accordance with the rise in the outlet fluid temperature of the furnace water-cooled wall 6, in order to shift the drain light from the steam-water separator 16 from the condenser 14 to the superheater 11 side, Squeeze the drain 9P17 and open the superheater water injection valve 22. The outlet fluid temperature of the furnace water-cooled wall 6 is 390~
When the temperature reaches about 400°C, the drain t from the steam separator 16 decreases to about 7 to 15% of the steam amount at the steam separator inlet, so almost the entire amount is injected into the superheater 11 side. When the drain valve 17 closes, the starting pressure control valve 18 also closes to start increasing the pressure and load of the superheater. To recover heat.

When the boiler startup bleed valve 15 is fully opened, the boiler throttle bypass box 8 is used to control the furnace water wall pressure. That is, when the superheater pressure is about 150 to 200 Ky/cm2i, the inlet steam of the steam-water separator 16 becomes dry steam, so when the boiler throttle bypass square 8 is fully opened, the furnace water cooling is transferred to the boiler throttle square 7. Shifting the pressure control of the wall 6,
The boiler throttle ff7 is controlled so that the steam at the outlet of the boiler throttle box 7 flows directly to the superheater 9. After that, the operation will be the same as that of a conventional combined circulation type once-through boiler.

Effects of the Invention As detailed above, according to the present invention, even in the step of boosting the pressure of the superheater system after the start of power generation with the turbine, the startup system is used to convert the condensate separated by the steam water separator into a low-temperature state. By mixing the superheated steam that exits the superheater, it is possible to obtain a main steam flow rate that is approximately equal to the water supply flow rate at the inlet of the economizer. With the introduction of , rapid startup is possible and the startup time is shortened.

In addition, in the past, the use of fuel that could not be used due to poor heat absorption in the furnace and preventing the main steam temperature from rising excessively caused the fluid temperature at the outlet of the water-cooled wall of the furnace to rise insufficiently, resulting in failure to start. By guiding the drain separated by the steam-water separator to the outlet of the low-temperature superheater, it is possible to input fuel commensurate with the main steam flow rate and the superheater outlet steam temperature to enable startup and shutdown.・ Furthermore, the steam pressure that can normally separate steam and water is approximately 200 K/cr.
n'f or less, and if the fluid temperature at the outlet of the water-cooled wall of the furnace is about 390°C, the artificial steam in the steam-water separator will become dry steam, so the superheater will be 200/crn2.
If it's about y, the boiler should be throttled! By directing the steam at the 11-liter outlet directly to the superheater, it is possible to operate in exactly the same way as in the past, and the pressure loss during steady operation does not increase compared to the past. Furthermore, if the temperature of the fluid at the outlet of the water-cooled wall of the furnace is high, the steam from the steam separator becomes dry steam at a lower pressure. It is also possible to guide

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an actual example of a once-through boiler according to the present invention, FIG. 2 is a system diagram of a water/steam type once-through boiler, and FIG. 3 is a system diagram of a conventional combined circulation type once-through boiler. ]... Deaerator, 4... Energy saver, 6... Furnace water cooling wall, 7...
・Boiler throttle V square, 8... Boiler throttle bypass square, 9...
Low temperature superheater, 10... Desuperheater, 11... High temperature superheater, 1
3...Turbine, 14Φ・Condenser, 15...Start-up bleed valve, 16...Steam water separator, 21...Steam temperature control valve, 2
2. Superheater water injection valve, 30. Water injection pipe, 31. Drain pipe, 32. Water injection pipe. (1 other person)

Claims (1)

[Claims] In a once-through boiler, a water injection pipe is branched from the water supply pipe on the downstream side of the feed water pump, and this water injection pipe is connected to a desuperheater installed in the middle of the steam pipe.Heating fluid from the outlet of the furnace water wall is supplied to the once-through boiler. A once-through boiler in which a second water injection pipe is branched from the middle of a drain pipe connected to a steam/water separator, and the second water injection pipe is connected to the attemperator.