JPS5929705A - Steam turbine controller of combined plant - Google Patents

Abstract

PURPOSE:To prevent the motoring phenomenon of a steam turbine and reduce the torsional stress in a shaft by providing a means which regulates a flow rate of supplementary steam which flows into the steam turbine regardless of steam from a heat recovering steam generator. CONSTITUTION:A gas turbine 1, a generator 4 and a steam turbine 3 are installed on the same axis. Exhaust gas of the gas turbine 1 is fed to a heat recovering steam generator 2 to produce steam therein. The resultant steam is delivered to the steam turbine 3 via a steam flow stop valve 6 and a steam flow rate regulating valve 7. Other steam is fed from an auxiliary steam header 8 to the steam turbine 3 via an auxiliary steam flow stop valve 10 and an auxiliary steam flow rate regulating valve 11 until the time when the steam produced in the steam generator 2 attains the condition equivalent to that of the steam which flows into the steam turbine 3. Thus, the motoring phenomenon of the steam turbine 3 may be prevented and the torsional stress in the shaft can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combined plant comprising a gas turbine, a steam generator for heat recovery, a steam turbine, and a power generator, and particularly relates to a combined plant comprising a gas turbine, a power generator, and a steam turbine on the same shaft. The present invention relates to a steam turbine inflow steam flow rate control device suitable for use in a steam turbine.

In conventional single-shaft compound plants in which a gas turbine, generator, and steam turbine are installed on the same shaft, steam does not flow into the steam turbine until the steam generated in the heat recovery steam generator reaches the steam turbine inflow conditions. This causes damage to the steam turbine (so-called motoring) due to an increase in the atmospheric temperature within the steam turbine, and shortens the life of the steam turbine.

It is an object of the present invention to secure and supply cooling steam for a steam turbine independently of the steam generated in the gas turbine and the steam generator for heat recovery.

An object of the present invention is to provide a steam turbine control device that can prevent motoring phenomena and reduce torsional stress on a shaft.

Combined plants are made up of multiple units that combine Gaster Pinto steam turbines, and can easily produce high-temperature, high-pressure steam compared to conventional thermal power plants. Focusing on this point, before the steam generated by the heat recovery steam generator matches the steam conditions of the steam turbine, steam that is required depending on the plant condition is introduced from other units as auxiliary steam, and the The steam flow rate is controlled accordingly and guided to the steam turbine.

An embodiment of the present invention will be described below with reference to FIG. The combined plant consists of a gas turbine 1, a heat recovery steam generator 2 (I~ [1, SO), a steam turbine 3, and a steam generator 1.
(Including number 4, in this example, the gas turbine, steam turbine, power generator, and machine are connected to the same shaft. (So-called -shaft type)
In this plant configuration, the steam turbine also starts rotating at the same time as the gas turbine 1 is started.

Exhaust gas from the gas turbine 1 is guided to a heat recovery steam generator 2 (hereinafter referred to as boiler) to recover heat and generate steam. This steam is guided to the steam turbine 3 via a steam flow stop valve 6 and a steam flow Jl control valve 7 through a steam conduit 5 to the steam turbine. The steam flow stop valve 6 and the steam flow control valve 7 remain fully closed until the conditions for steam inflow into the steam turbine are established.
Steam from the boiler is not directed to the steam turbine. Until this steam condition is established, in order to supply steam to the steam turbine, a part of the steam generated in other units is passed through the auxiliary steam header 8, the auxiliary steam conduit 9, the auxiliary steam flow rate stop valve 10, and the auxiliary steam flow rate. Steam turbine 3 via control valve 11
shall lead to. The steam that has driven the turbine in the steam turbine 3 is condensed in a condenser 12 and sent to the boiler 2 again in a water supply pipe 13. The control device 14 controls the steam flow stop valve 6, the steam flow control valve 7, the auxiliary steam flow stop valve 10, and the auxiliary steam flow control valve 11.

A method of controlling the auxiliary steam flow rate control valve 11 until the steam generated in the boiler 2 reaches the steam inflow conditions of the steam turbine 3 will be described with reference to FIG.

First, the signal from the rotation speed detector 15, 几, is a function (F+
) is converted into the required steam flow rate G in the computing unit 16.

G, = Ft (R:) In addition, the pressure detector 17 and temperature detector 18 detect the pressure Pb and temperature l1lb at the exhaust chamber inlet of the steam turbine 3, and perform the function (F2) necessary for the function (F2) and the temperature detector 19. Steam flow Nt
converted to ob.

Gb=F2(Pb,'l"b) On the other hand, the atmospheric temperature T inside the steam turbine is detected by the temperature detector 2.
0, and the function (F3) calculator 21 calculates the steam flow rate limit value G.

G, =F3(T-) In this example, the above-mentioned auxiliary steam flow rate calculation value was used, but other plant inputs or calculated values calculated from them (thermal stress, steam turbine lifetime consumption, etc.) It is also possible to calculate the auxiliary steam flow rate by adding

Then, adder 2 calculates G−, Gb, G, which were obtained earlier.
2 to determine the auxiliary steam flow rate Gtl.

On the other hand, the steam condition of auxiliary steam is steam turbine steam 11.・
” In order to confirm that the inflow conditions are satisfied, the pressure detector 23 and temperature detector 24 each measure the auxiliary steam pressure PD.
, calculate the auxiliary steam temperature l1lD, respectively. Function (F4)
The steam condition KII is determined by the computing unit 25 and the function (pg) computing unit 26.
K! seek.

However, A, B, C, and I) are constants, and then multiplier 27 multiplies 1 and 2 to obtain 3 for the auxiliary steam inflow condition.

Ig3 = +
Multiply by multiplier 28 to obtain Gτ2.

G 2 ”GTI

However, Gto is a constant, and the function (Pa) calculator 30 calculates the auxiliary steam flow it
GT3 is converted into a valve control command value GT that matches the valve characteristics of the auxiliary steam flow rate control valve 11, and the auxiliary steam flow rate control valve 11 is
to drive.

According to the present invention, there are the following effects.

(1) After the gas turbine is started, the required amount of steam can be supplied to the steam turbine at will until the steam generated by the heat recovery steam generator reaches the steam turbine inflow conditions.

(2) It is possible to reduce the steam turbine thermal stress during startup, shorten startup time, and prevent wind damage.

(3) Short start-up time enables fuel savings and extends the life of the steam turbine.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram of the plant of the present invention, and Fig. 2 is a schematic diagram of the plant of the present invention.
In the figure, it is a control diagram 1411 regarding section 151 of ``auxiliary steam''. ■...Gas turbine, 2...Steam generator for heat recovery,
3... Steam turbine, 4... Generator, 11... Auxiliary steam flow m, control valve, 8... Auxiliary steam header, 14.
··Control device.

Claims (1)

[Claims] 1, attached to a gas turbine, a steam coupin, a heat recovery steam generator, a steam conduit interconnecting the heat recovery steam generator and the steam turbine, and a steam flow rate regulator disposed in this steam conduit; In a combined plant consisting of a flow rate control means for controlling the steam flow rate on the downstream side of a steam conduit and a means for supplying auxiliary steam from other units,
A combined plant characterized by comprising means for adjusting the flow rate of the auxiliary steam flowing into the steam turbine in accordance with the operating state of the plant, regardless of the steam led from the heat recovery steam generator. Steam turbine control device.