EP3803084A1

EP3803084A1 - Method for starting a gas turbine in a combined cycle power plant

Info

Publication number: EP3803084A1
Application number: EP19745988.6A
Authority: EP
Inventors: Stefan Becker; Matthias Nickl; Kai Voit; Johannes WALZIK
Original assignee: Siemens Energy Global GmbH and Co KG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2018-08-09
Filing date: 2019-07-09
Publication date: 2021-04-14
Also published as: DE102018213422A1; WO2020030363A1; US20220106914A1

Abstract

The invention relates to a method for starting and stopping a gas turbine (1) in a combined cycle power plant (2), wherein the gas turbine (1) comprises a compressor (3) having adjustable guide vanes (4) and the gas turbine power can also be controlled by opening the guide vanes (4). When the gas turbine (1) is started, it is driven up to a base load or up to an emission-compliant load point, and the guide vanes (4) are opened before the base load or the emission-compliant load point is reached.

Description

METHOD FOR STARTING A GAS TURBINE IN A GAS AND

STEAM TURBINE INSTALLATION

The invention relates to a method for starting, but also for shutting down a gas turbine in a gas and steam turbine turbine. In particular, the invention relates to a guide vane adjustment procedure in gas turbines.

Typically, gas turbines in gas and steam turbines with closed guide vanes in the compressor are started up to a maximum value. This has the advantage that the combustion in the gas turbine is stable and the emissions are comparatively quickly within a range that complies with the requirements. The guide vanes are only opened after the base load has been reached or after an emission-compliant load point has been reached in order to increase the mass flow through the gas turbine and thus also the output.

However, ever higher gas turbine exhaust gas temperatures only allow a limited overall system quick start capability in gas and steam turbine systems. The waste heat of steam generators in particular is exposed to considerable thermal stress, which leads to comparatively strong, premature material fatigue.

For this reason, only a step-by-step start-up of the entire system including load breakpoints takes place through a temperature-controlled gas turbine start-up until the maximum exhaust gas temperature is reached, including the power breakpoints for heating the downstream components (heat recovery steam generator, steam turbine).

The object of the invention is to provide a method for starting and starting a gas turbine in a gas and steam turbine system, in which the system as quickly as possible with compliance with emission requirements and the least possible fatigue components connected downstream from the gas turbine can be started and stopped.

The invention solves the problem addressed to a method for starting and stopping a gas turbine in a gas and steam turbine system by providing that in such a method the gas turbine comprises a compressor with adjustable guide vanes and the gas turbine power also through the opening the guide vane is controllable, the gas turbine being started up to the base load or to an emission-conforming load point, the guide vane being opened before the base load or the emission-compliant load point is reached.

By at least partially opening the guide vane, the mass flow through the gas turbine is increased at an early stage and the temperature of the exhaust gas flow is reduced to subsequent components. A complete opening of the guide vanes is typically avoided to avoid excessive emissions in the comparatively early period of the start.

It is useful if the gas turbine is started up with the maximum possible load ramp. This ensures the fastest possible start.

It is advantageous if the guide vanes are closed at the beginning of the start and are opened as far as possible when starting up within the framework of the emission requirements, since a larger mass flow leads to more power or lower temperatures of the exhaust gas flow. It is essentially the operation of the system "below" the design that limits the degree of opening due to the poorer emission values.

It is advantageous if the gas and steam turbine system comprises an exhaust gas chimney and emissions in the exhaust gas chimney are measured continuously. It is also advantageous if temperature sensors are continuously read out when starting and stopping. In particular, it is advantageous if the temperature sensors on thick-walled components are continuously read out, ie on parts with a ratio of outside diameter to inside diameter greater than 1.2.

By the inventive method, the gas turbine without additional gas turbine stop with the maximum possible load ramp up to base load or up to the emission-compliant load point (z. B. 70% gas turbine load) is started up temperature-compatible for the following components. Furthermore, the guide vane adjustment method of the inventive method can also be used during the shutdown process in order to modify the gas turbine exhaust gas temperature with regard to the boiler service life.

The advantages are as follows:

• Reduction of the heat recovery steam generator stress and minimal heat recovery steam generator life consumption

• Reduction of start-up emissions (NOx)

• Improved and flexible operation across the entire load range

• Faster start-up of the gas and steam turbine system including reduced fuel consumption

• Increased, faster power delivery through the use of higher gas turbine load ramps during start-up

The invention is explained in more detail by way of example with reference to the drawings. They show schematically and not to scale:

Figure 1 is a schematic representation of a gas and

Steam turbine plant and

Figure 2 is a graph for the electrical power of the gas and steam turbine system over the exhaust gas temperature. In the schematic representation of Figure 1, a gas and steam turbine system 2 is shown with a gas turbine 1, from a heat steam generator 7 and a steam turbine 8. Other designs, such as two or more gas turbines, each with a downstream heat recovery steam generator or even a common heat recovery steam generator, are also possible.

The gas turbine 1 comprises a compressor 3, a combustion chamber 17 and a turbine 18. The compressor 3 comprises adjustable guide vanes 4 with which the compressor air mass flow can be adjusted.

The steam turbine 8 is followed by a condenser 10 in a water-steam circuit 9. Furthermore, the water-steam circuit 9 comprises the heat recovery steam generator 7, in which temperature sensors 6 are arranged in particular on thick-walled components.

The steam turbine 8 usually comprises a plurality of pressure stages 11, which drive the generator 14 via a common shaft 12 with a clutch 13.

To supply relaxed in the gas turbine 1 Arbeitsmit tel or flue gas in the heat recovery steam generator 7 from a gas line 15 is connected to an input 16 of the heat recovery steam generator 7. The relaxed work equipment from Gastur bine 1, i.e. the gas turbine exhaust gas, leaves the waste heat steam generator 7 via an exhaust gas fireplace 5.

FIG. 2 shows the electrical power P _ei in megawatts (MW) of the gas and steam turbine system 2, represented above the exhaust gas temperature T [K] in the inventive mode of operation 19 ',

19 '' (two possible driving styles, dashed) compared to the previous driving style 20 (dotted). In the previous mode of operation 20, the guide vanes 4 remained closed until the gas turbine 1 had reached a load 50 or an emission-compliant load point.

This guaranteed stable and emission-compliant combustion and was the preferred process due to the "low" exhaust gas temperatures compared to today's gas turbines 1.

With the method according to the invention, the mass flow through the gas turbine 1 is increased before the load 50 or an emission-conforming load point is reached, as a result of which, among other things, reduces the temperature of the exhaust gas flow.

The adjustable guide vanes 4 have a closed position, that is to say a minimum opening angle, which can be increased by adjustment in order to increase the compressor air mass flow. When moving off or on, the guide vanes 4 are preferably kept closed.

But in any case fairly promptly, especially directly when approaching or departing, the opening angle of the guide vanes is increased.

In FIG. 2, the driving style 19 'shows that the guide vanes 4 are opened as quickly as possible, so that the driving style 19' abuts the closed line 22 as quickly as possible.

The curves of the control modes 19 ', 19' 'rise very steeply at the beginning (a') or in the middle section (b ''), so that there is little or no change in the exhaust gas temperature T.

In a slightly changed approach or departure according to curve 19 '', the opening angle of the guide vanes 4 is not left constant from the beginning, but is opened more and more over a certain period of time in stage a '', in particular continuously, very particularly continuously and continuously , but not completely, and then ramped up to P '' with minimum change in exhaust gas temperature T [K] according to stage b. The procedure according to the 19 'or 19''mode of operation achieves outputs R' ~ 50% (19 ') or P''~ 60% as quickly as possible

(19 '') of a base load 40 is reached.

This can also be seen in the diagram in FIG. 2 in that the area II, I, which is as minimal as possible between the driving style 19 ', 19' 'and the upper boundary lines 22 of the solid line and clearly less than half of the area, which is enclosed by the previous mode of operation 20 corresponds.

The starting point 30 is preferably started with a minimal opening angle.

A time period t _BASIC means the time period in which the gas turbine from the start _Z is eitpunkt drive 30 to the base load hochge 40, and the maximum latching ramp a ', b''is preferably in the first third of the time period t _BASIC ·

A temperature range T _G RU _N D describes the temperature range from the starting _Z eitpunkt 30 to the temperature T of the base load 40, wherein the maximum possible loading ramp a ', b''is ramped up within the first third of the temperature range T _GR1JND.

Claims

claims

1. Procedure

for starting and stopping a gas turbine (1) in a gas and steam turbine system (2),

wherein the gas turbine (1) comprises a compressor (3) with adjustable guide vane (4) and

the gas turbine output (P _ei ) can also be checked through the opening of the guide vanes (4),

the gas turbine (1) when starting up

on base load (40) or

except for an emission-compliant load point

is driven

characterized in that

before reaching the base load (40) or

before the emission-compliant load point is reached

the guide vanes (4) are opened so

that there is little or no change in the exhaust gas temperature (T).

2. The method according to claim 1,

wherein the gas turbine (1) is started up with the maximum possible load ramp (a ', b' ').

3. The method according to claim 1 or 2,

at which at the start time (30) the guide vane (4) is started with the smallest opening angle.

4. The method according to one or more of claims 1, 2 or 3,

in which about 47% to 53% of the power (P ' _ei ) is reached as quickly as possible when starting up (19').

5. The method according to one or more of claims 1, 2 or 3,

in which after a first stage (a '') in a second stage (b '') about 57% to 63% of the power (P '' _ei ) is reached as quickly as possible when starting up (19 '').

6. The method according to one or more of claims 1, 2, 3 or 5,

in which the guide vanes (4) of a driving style (19 '') are opened in two different stages (a '', b ''), the guide vanes (4) being opened somewhat in a first stage (a ''),

especially continuously and steadily

and in a second stage (b '') the guide vanes (4) are opened to the maximum,

so that a maximum load ramp (b '') is reached at which there is hardly any change in the exhaust gas temperature (T).

7. The method according to one or more of claims 1, 2, 3, 4, 5 or 6,

the guide vanes (4) being closed at the start (30) of the start.

8. The method according to any one of the preceding claims,

the guide vanes (4) being opened as far as possible within the framework of emission requirements.

9. The method according to one or more of claims 1 to

8th,

wherein the gas and steam turbine system (2) comprises an exhaust gas chimney (5) and emissions in the exhaust gas chimney (5) are measured continuously.

10. The method according to any one of the preceding claims, wherein temperature sensors (6) are continuously read out during start-up and shutdown.

11. The method according to claim 10,

the temperature sensors (6) on thick-walled components being read continuously, i.e. on components with a ratio of outside diameter to inside diameter greater than 1.2.

12. The method according to one or more of claims 1 to

11

where the opening angle of the guide vanes (4) is continuous,

especially continuously and steadily

is opened at least temporarily.

13. The method according to one or more of claims 1 to

12

wherein a time period t _BASIC means the time period in which the gas turbine from the start _Z eitpunkt (30) to the base load ramped (40)

and the maximum possible locking ramp (a ', b'') is in the first third of the time period tGRU _N D.

14. The method according to one or more of claims 1 to 13,

wherein TGRu _N D the temperature range from the starting _Z eitpunkt (30) up to the temperature of the base load (40) describes,

the maximum possible load ramp (a ', b'') being ramped up within the first third of the temperature range T _G RU _N D.