JPH0233845B2 - JOKITAABIN PURANTONONTENHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a steam turbine plant equipped with a turbine bypass device.

An example of a thermal power plant equipped with a conventional turbine bypass device is shown in FIG. Steam generated in the boiler 1 passes through piping 2, is introduced into the high-pressure turbine 3, is heated again in the reheater 15, passes through the intermediate-pressure turbine 4, the low-pressure turbine 5, drives the generator 6, and is converted into condensate water. The water is condensed in vessel 7. Thereafter, the condensate is sucked by a pump 8, passes through several low-pressure feed water heaters 9 arranged in series, and then passes through a deaerator 10.
As a result, gas components in the condensate are removed, and the condensate is further sent by a pump 11 to several high-pressure feed water heaters 12 arranged in series, heated to a high temperature, and then returned to the boiler 1.

In the power generation plant configured in this way, when the plant is started or stopped, the steam generated in the boiler 1 is transferred to the high-pressure turbine in which the pressure control valve 13 and the desuperheater 19 are installed, which are branched from the pipe 2. After passing through the bypass piping 14 and passing through the reheater 15 provided in the boiler 1, it passes through the low pressure turbine bypass piping 17 in which the pressure control valve 16 is interposed,
It passes through the desuperheater 18 and is dumped into the condenser 7.

Therefore, in the power generation plant with the above configuration, when the plant is started or stopped, the steam generated in the boiler 1 is discarded through the bypass pipe 17 and into the condenser 7, so that the steam generated in the boiler 1 has a Energy is wasted without doing any work,
The problem is that heat energy is wasted.

In particular, demand for electricity has fluctuated rapidly in recent years, with demand for electricity being high during the day and relatively low at night. Therefore, as a way to deal with the imbalance in demand between daytime and nighttime, a turbine bypass device is installed in the power generation plant to quickly start up the plant every day.
An increasing number of power plants are shutting down. Therefore, in the above plant, the steam generated in boiler 1 is dumped into the condenser until the set load is reached without driving the steam turbine during daily startup and shutdown, resulting in a large energy loss. becomes.

The present invention has been made in view of the above-mentioned circumstances, and provides a method of operating a steam turbine plant that bypasses the steam turbine and effectively utilizes steam that would otherwise have been discarded in the condenser. The purpose is to

The feature of the method of operating a steam turbine plant of the present invention is that in a steam turbine plant equipped with a turbine bypass device, bypass steam is cooled by a desuperheater, condensed water is stored in a steam accumulator, and the stored heat is stored during rated operation. Water is pressurized by turbine extraction steam or plant high pressure steam and then supplied to the boiler.

An embodiment of the method of this invention will be described below with reference to FIG. Here, the same parts in the drawing are denoted by the same reference numerals for the same parts as the conventional one shown in FIG. 1, and detailed explanation thereof will be omitted. In this power plant, when the plant is started or stopped, steam generated in the boiler 1 passes through the high-pressure bypass pipe 14, passes through the reheater 15 in the boiler 1,
Passing through bypass piping 20 with an on-off valve 21,
The temperature is reduced by the desuperheater 22 and the steam accumulator 23
stored in Here, the desuperheater 22 reduces the temperature of the steam flowing into the steam accumulator 23 by spray water supplied by the condensate pump 8 to the permissible temperature of the material of the steam accumulator 23, and condenses the steam within the accumulator. However, in some cases, the amount of spray water may be increased to make it hot water before entering the steam accumulator.

When the power generation plant enters rated operation, the hot water stored in the steam accumulator 23 is passed through the hot water supply pipe 24 to the water supply pipe 2 of the boiler 1.
Supply to 9. In this way, steam accumulator 2
By using the hot water stored in 3 as part of the boiler feed water, the amount of feed water passing through the low pressure feed water heater 9 can be reduced, and furthermore, it is used for heating the low pressure feed water heater 9. The amount of steam extracted from the turbine can also be reduced, and as a result, the reduced steam can be sent to the subsequent turbine, making it possible to increase the turbine output. Conversely, the amount of steam at the turbine inlet, that is, the amount of steam generated by the boiler, decreases by the amount of energy corresponding to the decrease in the amount of turbine extracted steam, and the amount of fuel consumed by the boiler can be significantly reduced.

In this case, one possible method of utilizing the thermal energy stored in the steam accumulator 23 is to reduce the pressure in the steam accumulator and send the generated steam to the feed water heater and use it to heat the boiler feed water. By using the hot water as part of the boiler feed water, the operating temperature range of the steam accumulator 23 can be widened.
As a result, the heat storage density per 1 ^m3 of steam accumulator volume increases, so the required volume of the steam accumulator can be significantly reduced, and as a result,
Equipment costs are low. In addition, energy saving effects such as an increase in turbine output are also greater. Furthermore, transferring hot water in the form of hot water has many advantages, such as requiring smaller pipes.

In addition, when supplying the hot water stored in the steam accumulator 23 to the boiler water supply piping 29, if the pressure in the pump water supply piping to which the hot water is supplied is higher than the pressure in the steam accumulator 23, the hot water supply piping 29 A pump is required to send hot water along the way, but since the hot water is saturated water, a special pump that does not cause cavitation is required, and power is also required to drive the pump.
Therefore, in order to simplify and reduce the energy required for transferring hot water, the steam accumulator 23 is heated using steam extracted from a turbine whose pressure is lower than that of the steam accumulator 23 or high-pressure steam generated within the plant. The hot water is sent to the phase section, and the steam flows in to send out the hot water. For this purpose, for example, a bleed steam pipe 26 equipped with a pressure control valve 27 is connected to the accumulator 23 .

After sending the hot water in the steam accumulator 23 to the boiler water supply piping, before storing the turbine bypass steam again, the accumulator water supply piping 28
The steam accumulator 23 is replenished with water.

Next, another method of transferring the hot water stored in the steam accumulator 23 to the water supply pipe 29 or the deaerator 10 will be explained with reference to FIG. In this method, a pump 3 that transfers hot water is placed in the middle of the hot water supply piping 24.
0 is provided, and in order to prevent cavitation from occurring within the pump 30, steam at a pressure slightly higher than the pressure within the accumulator is injected into the gas phase portion of the steam accumulator 23 to pressurize the steam accumulator 23. .

When a pump such as a centrifugal pump is used as a means to transfer the hot water stored in the steam accumulator to the boiler water supply piping or deaerator, the hot water stored in the steam accumulator is saturated water, so Cavitation easily occurs within the pump, making it impossible to transfer. Therefore, in order to transfer without causing cavitation, it is necessary to make the effective NPSH larger than the required effective suction head of the pump. This can be solved by injecting steam at a pressure slightly higher than the pressure inside the steam accumulator (turbine extraction steam or high-pressure steam generated within the plant) into the gas phase of the steam accumulator to pressurize it. This allows hot water to be transferred smoothly without cavitation.

In addition, in the hot water transfer method shown in FIG.
0, the head difference depending on the installation location of the steam accumulator 23, and the pressure loss of the hot water supply pipe 24, minus the saturated steam pressure inside the steam accumulator 23. Therefore, by using this method in conjunction with the pump 30, the pressure of the steam injected into the pneumatic part of the steam accumulator 23 is sufficient to prevent cavitation from occurring within the pump. Compared to the case shown in the figure, the pressure of the steam injected into the gas phase portion of the steam accumulator 23 may be lower. Therefore, the maximum working pressure of the steam accumulator 23 can be lowered, so that the thickness of the steam accumulator can be made thinner and the price can be lowered.

Since the method of operating a steam turbine plant of the present invention is as described above, it is possible to efficiently and effectively utilize steam that has not been utilized in the past, and to increase the turbine output during rated operation or increase the boiler output. As a result, the efficiency of the plant can be significantly increased.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a thermal power plant equipped with a conventional turbine bypass device; FIG. 2 is an explanatory diagram showing an example of a steam turbine plant equipped with a device for carrying out the method of the present invention; FIG. 3 is an explanatory diagram of a main part provided with a device for carrying out another method of transferring hot water. 1... Boiler, 3, 4, 5... Turbine, 7...
... Condenser, 10 ... Deaerator, 14 ... High pressure bypass piping, 17 ... Low pressure bypass piping, 20 ... Bypass steam piping, 22 ... Desuperheater, 23 ... Steam accumulator, 24 ... Heat Water supply piping, 26...
...Extraction steam piping, 27...Pressure control valve, 28...
Accumulator water supply piping, 29...Boiler water supply piping, 30...Pump.

Claims (1)

[Claims] 1. In a steam turbine plant equipped with a turbine bypass device, bypass steam is cooled by a desuperheater, condensed water is stored in a steam accumulator, and this stored hot water is pressurized by turbine extraction steam or plant high-pressure steam during rated operation. A method of operating a steam turbine plant characterized by supplying steam to a boiler.