JPS6060207A - Steam turbine plant - Google Patents

Abstract

PURPOSE:To contrive to achieve the high efficiency and high reliability of power generation by a method wherein a high pressure cooling steam pipe for cooling of a turbine member extracting a high pressure steam is bifurcated from a main steam pipe, and the high pressure cooling steam pipe is connected to a reheating steam turbine. CONSTITUTION:A steam turbine plant is provided with a high pressure steam turbine 22 and a reheating steam turbine 25. A high pressure cooling steam pipe 40 for cooling of a turbine member extracting a high pressure steam is bifurcated from a main steam pipe 21 which supplies a main steam to the high pressure steam turbine 22, the high pressure cooling steam pipe 40 is connected to the reheating steam turbine 25. A throttle mechanism 41 which is enabled to adjust the flow rate, pressure and temperature of the high pressure steam is provided on the high pressure cooling steam pipe 40, then the high pressure steam is changed to the high pressure cooling steam. Thereby, the improvement of power generation efficiency can be contrived steadily, also the reliability of a steam turbine plant can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a steam turbine plant equipped with a high-pressure steam turbine and a reheat steam turbine. In particular, the present invention relates to improvements in cooling mechanisms for cooling the high-temperature parts of reheat steam turbines.

[Technical background of the invention and its problems]

In recent years, reheat steam turbines have been used in steam turbine generators to improve power generation efficiency.
Even in MM steam turbine plants using this reheat steam turbine, there is a tendency to increase the main steam pressure and temperature higher and higher in order to further improve power generation efficiency. Of these, considering the reheat steam temperature, conventionally 53
Reheat steam at a temperature of 8 degrees Celsius was generally used, but now the temperature has increased to, for example, 566 degrees Celsius, and in the future, two-stage reheat steam turbines with a reheat steam temperature of, for example, 649 degrees Celsius are planned. ing.

As the temperature of reheated steam increases, many strength problems are occurring in the materials that make up the turbine in turbine stages such as the first stage of reheated steam turbines into which reheated steam flows. In particular, the generation of thermal stress that acts on the turbine rotor, turbine rotor blade mounting portion, rotor blade tenon portion, etc. of a reheat steam turbine has become a problem.

A conventional reheat steam turbine plant is configured as shown in FIG. 1, and main steam generated in a boiler 1 is supplied to a high-pressure steam turbine 3 through a main steam pipe 2 to drive the turbine.
I'm working. The steam expanded by doing work is guided to the boiler 1 through the entire high-pressure exhaust steam pipe 4, where it is reheated. The reheat steam reheated by the boiler 1 is sent to the reheat steam turbine 6 via the reheat steam pipe 5, where it drives the reheat steam turbine 6 and performs work.

The high-pressure steam turbine 3 and the reheat steam turbine 6 rotate a common turbine shaft 7 to drive a generator 8.

On the other hand, the steam expanded by doing work in the reheat steam turbine 6 is sent to the condenser 9, where it is condensed and becomes condensed water. This condensate is sent through a condensate water supply pipe 11 by a condensate pump 10, heated by low-pressure and high-pressure feedwater heaters 12 and 13 provided along the way, and after rising in temperature, is returned to the boiler 1, Steam turbine plant 1
one cycle ends.

Further, a low temperature steam pipe 15 is branched from the high pressure exhaust steam pipe 4, and this low temperature steam pipe 15 is cooled by passing through a throttle mechanism 16f and merging with a high temperature steam pipe 17 which is branched from the reheat steam pipe 5 in the middle. Steam pipe 18 becomes reheat steam turbine 6
The turbine member of the reheat steam turbine 6 is cooled. The high temperature steam pipe 17 is also provided with a throttle mechanism 19.

In such conventional steam turbine plants, a portion of the high-pressure exhaust steam of the high-pressure steam turbine 3 is combined with a portion of the reheated steam and mixed to form cooling steam, and this cooling steam is combined with the reheated steam. is supplied to the turbine stages such as the first stage of the reheat steam turbine into which the steam flows, thereby cooling the turbine members.

However, the steam line that produces the cooling steam is the low-temperature steam pipe 1.
5, high-temperature steam pipe 17, and 2nd route tomorrow, trachea 15
, 17 have different temperature and pressure.

For this reason, it is difficult to control the steam flow rate and pressure in the steam line that produces cooling steam, and backflow may occur in the low-pressure steam pipe 15 on the low-pressure side. Furthermore, since the pressure of the cooling steam is lower than the pressure of the reheat steam, it is impossible to cool the parts of the reheat steam turbine that have a higher pressure than the cooling steam pressure, such as the front part of the turbine stationary blades in the first stage of the reheat steam turbine. In addition, when cooling steam is allowed to flow into a reheat steam turbine, there are problems such as the construction of a tank for the cooling steam inflow section being extremely complicated.

[Purpose of the invention]

This invention takes the above-mentioned points into consideration, and by making the cooling steam supplied to the reheat steam turbine have a higher pressure than the reheat steam, it is possible to actively and efficiently cool the turbine components. It is an object of the present invention to provide a steam turbine plant that can use reheated steam at a higher temperature and achieve higher efficiency and reliability in power generation.

[Summary of the invention]

In order to achieve the above-mentioned object, a steam turbine plant according to the present invention includes a high-pressure steam turbine and a reheat steam turbine, and extracts high-pressure steam from a main steam pipe that supplies main steam to the high-pressure steam turbine. A high-pressure cooling steam pipe for cooling turbine components is branched, and this high-pressure cooling steam pipe is connected to the reheat steam turbine.
K: An adjustable aperture mechanism is provided, and this aperture +84?
4, the high-pressure steam is squeezed into high-pressure cooling steam.

Specifically, high-pressure steam is extracted from the main steam pipe of a high-pressure steam turbine such as the high-pressure steam turbine inlet, and reheated steam flows into a high-pressure cooling steam pipe equipped with a steam flow rate, pressure, and temperature control mechanism. It is communicatively connected to the turbine stage of the steam turbine.

[Embodiments of the invention]

Hereinafter, preferred embodiments of a steam turbine plant according to the present invention will be described with reference to the accompanying drawings.

FIG. 2 shows a system diagram of a steam turbine plant according to the present invention, in which reference numeral 2o indicates a boiler of the steam turbine plant, and the boiler ribs of and are connected to a calm pressure steam turbine n via a main steam pipe 21. , this high pressure steam turbine 22 is supplied with main steam to perform work. The high-pressure exhaust steam pipe of the high-pressure steam turbine 22 is guided to the boiler, and the high-pressure exhaust is heated again by the boiler. The boiler 2o is connected to a reheat steam turbine 25 via a reheat steam pipe, and the steam reheated in the boiler 2o is guided to a reheat steam turbine 2o.

The suppression steam turbine 22 and the reheat steam turbine δ are driven by main steam and reheat steam supplied from the boiler, and have a common turbine shaft 27.

Work is done in the reheat steam turbine δ, and the expanded steam is guided to the condenser blades, where it undergoes condensation action.

The condensed water is guided to a condensate water supply pipe 32 by a condensate pump 31, heated by low pressure and high pressure feed water heaters 33 and 34, and then supplied to the boiler. Low pressure water heater 3
3VC is a low pressure steam extraction pipe 35 from the reheat steam turbine δ
A high pressure steam extraction pipe 36 from a high pressure steam turbine n is connected to the high pressure feed water heater. The turbine bleed air flowing through the steam bleed pipes 35 and 36 is condensed by exchanging heat with the condensate from the condenser I, and this condensed water is guided to the condensate ve 330 via the pipe 38.

By the way, a high-pressure cooling steam pipe 40 is branched from the main steam pipe 21 that supplies main steam to the high-pressure steam turbine B. This high-pressure cooling steam pipe 40 is connected so as to communicate with a turbine stage such as a first stage of a reheat steam turbine into which reheat steam is introduced. A plurality of throttling mechanisms 4], 4] are arranged in series in the middle of the high-pressure cooling steam pipe 40. Figure 2 shows
Although two diaphragm mechanisms 41 are shown, only one diaphragm mechanism 41 may be provided. Throttle mechanism 41 provided in high pressure cooling steam pipe 40
At least one of the throttle mechanisms 4] has an adjustable throttle ratio and is formed, for example, by a throttle valve. The aperture mechanism 41
The high pressure steam guided into the high pressure cooling steam pipe 40 by
The steam flow rate, pressure, and temperature are adjusted to produce cooling steam with a higher pressure and lower temperature than the reheat steam, and this high-pressure cooling steam is sent to the reheat steam turbine to cool the turbine members.

Next, the operation of this invention will be explained.

The main steam from the boiler used in the reheat steam turbine plant is shown as A-)B→C→D in the reheat steam turbine steam expansion diagram (i-8 diagram) shown in Figure 3. It expands and does work. Among them, A indicates the steam state of the main steam in the high-pressure steam turbine section, and this main steam performs work while passing through the high-pressure steam turbine 22, and expands to the steam state B at the turbine outlet. This expanded steam B is reheated in the boiler to a steam state C in the reheat steam turbine 25, and becomes high-temperature reheat steam.

While passing through the reheat steam turbine 5, this reheat steam expands and does work until it reaches the steam state from steam state C, and the expanded steam flows from the reheat steam turbine outlet in the steam forest state to the condenser. It follows the steam expansion process of being guided by the blade.

In the present invention, high-pressure steam in steam state A is extracted from the main steam pipe 21 near the high-pressure steam turbine intake section, and this high-pressure steam is guided to the high-pressure cooling steam pipe 40. The guided high pressure steam is passed through the throttling mechanism 41. ．． 41, the steam temperature decreases isenthalpically due to the Joule-Thomson effect, and expands to a high-pressure, low-temperature steam state indicated by symbol E in FIG. 3, becoming high-pressure cooling steam. The steam state E of this high-pressure cooling steam has a higher steam pressure and a lower steam temperature than the steam state C of the reheat steam at the inlet of the reheat steam turbine. Sufficient and effective VC as steam for cooling turbine parts
Available. At this time, since the high-pressure cooling steam has a higher pressure than the reheat steam, the high-pressure cooling steam can cool the turbine members of the reheat steam turbine without complicating the structure for inflowing the high-pressure cooling steam into the reheat steam turbine. It becomes possible to cool efficiently.

Furthermore, the steam pressure, temperature, and flow rate of the high-pressure cooling steam can be freely adjusted by adjusting the opening degree of the valve used in the throttling mechanism 41, the orifice, the shape and quantity of the perforated plate, etc., that is, the throttling amount. .

Further, the high-pressure cooling steam pipe 40 is branched from the main steam pipe 21 at the inlet of the high-pressure steam turbine, and a branch pipe branched from the reheat steam pipe row can be connected to this cooling steam pipe 40, or There is no need to provide a
The temperature adjustment side @I can be performed simply and easily. In this case, even when the reheat steam plant is not in the rated operating state, such as during partial load operation or startup, the cooling steam can be controlled much more easily than the conventional reheat steam turbine shaft, which has two paths. be able to. The high-pressure cooling steam that cools the reheat steam turbine 25 has a lower temperature and a higher pressure than reheat steam, so it is easier to cool the turbine members of each part of the reheat steam turbine, and for this turbine member cooling, The cooling structure does not become complicated.

[Effects of the Invention] As described above, in the steam turbine plant according to the present invention, the high-pressure cooling steam pipe for cooling turbine members that extracts high-pressure steam from the main steam pipe that supplies main steam to the high-pressure steam turbine is branched. This high-pressure cooling steam pipe is connected to a reheat steam turbine, and the high-pressure cooling high-pressure steam pipe is provided with a restrictor that can adjust the flow rate, pressure, and temperature of the high-pressure steam. The throttle mechanism throttles the high-pressure steam into high-pressure cooling steam. By supplying this high-pressure cooling steam to the reheat steam turbine, the turbine stages such as the first stage of the reheat steam turbine into which the reheat steam flows can be effectively controlled. and can be actively cooled. Since the reheat steam turbine can be effectively cooled, it becomes possible to use higher temperature reheat steam, and it is possible to reliably improve power generation efficiency.

In addition, the high-pressure cooling steam pipe is branched from the main steam pipe and connected to the reheat steam turbine, and there are no branching or merging parts in the middle, so there is no backflow of steam. The throttling mechanism also makes it easy and simple to control the flow rate, pressure and temperature of the cooling steam. Therefore, it is possible to perform one power generation more efficiently than a conventional steam turbine plant, and a highly efficient and reliable steam turbine plant can be obtained.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing a conventional steam turbine plant, Fig. 2 is a system diagram showing an embodiment of the steam turbine plant according to the present invention, and Fig. 3 is a reheating system applied to the steam turbine shaft of the present invention. FIG. 1 is a 1-s diagram showing a steam expansion diagram of a steam turbine. 20... Boiler, 21... Main steam pipe, 22...,
Pressure steam turbine, 24... Reheat steam pipe, B... Reheat steam turbine, 27... Turbine shaft, U...
- Generator, blade...TM water device, 31... Condensate pump, 33, 34... Feed water heater, 40... High pressure cooling steam pipe, 41... Throttle mechanism. Figure 1 Figure 2 L

Claims (1)

[Claims] 1. In a steam turbine plant equipped with a high-pressure steam turbine and a reheat steam turbine, high-pressure cooling for cooling turbine components by extracting high-pressure steam from a main steam pipe that supplies main steam to the high-pressure steam turbine. The steam pipe is branched, and this high-pressure cooling steam pipe is connected to the reheat steam turbine, and the high-pressure cooling steam pipe is provided with a throttle mechanism that can adjust the flow rate, pressure, and temperature pt of high-pressure steam. A steam turbine plant characterized by compressing high-pressure steam into high-pressure cooling steam. 2. The steam turbine plant according to claim 1, wherein a plurality of throttling mechanisms are arranged in series in the high-pressure cooling steam pipe, and at least one of the throttling mechanisms has a throttling ratio that can be variably adjusted. . 3. The steam turbine plant according to claim 1, wherein the high-pressure cooling steam pipe is communicated with a turbine stage such as a first stage of a reheat steam turbine into which reheat steam is introduced, and cools turbine members.