WO1999039084A1

WO1999039084A1 - Combined cycle power generation plant

Info

Publication number: WO1999039084A1
Application number: PCT/JP1998/000352
Authority: WO
Inventors: Jun Yasuraoka; Kouzo Toyama
Original assignee: Mitsubishi Heavy Industries, Ltd.
Priority date: 1996-07-30
Filing date: 1998-01-29
Publication date: 1999-08-05
Also published as: JP3835859B2; JPH1047016A

Abstract

A combined cycle power generation plant including means for detecting flow rates of steam at the outlet/inlet of a steam cooling system. A warming finish timing of the steam cooling system is judged at the time of start from the deviation of the outlet/inlet flow rates. When the deviation of the steam flow rate at the inlet from the flow rate of the steam at the outlet of the steam cooling system falls below an allowable value, it is judged that the residual air and the drain are not scattered and warm-up is completed, allowing the operation flow to proceed to the step of starting a gas turbine.

Description

Description Combined cycle power plant Technical field

The present invention relates to a combined cycle power plant that combines a gas bin and a steam bin. Background art

A combined cycle power plant is a power generation system that combines a gas turbine plant and a steam turbine plant.The high-temperature region of thermal energy is shared by the gas turbine, and the low-temperature region is shared by the steam bin, and heat energy is shared. This is a power generation system that has been effectively collected and used, and has recently been particularly spotlighted.

In this combined cycle power plant, research and development has been promoted with one point for improving efficiency in terms of how high the high-temperature region of a gas and gas bottle can be raised.

On the other hand, a cooling system must be provided for the formation of the high-temperature region in view of the heat resistance of the bottle structure. Air has been used as the cooling medium in this cooling system.

However, as long as air is used as the cooling medium, even if a high-temperature range can be achieved, the amount of heat taken away by the air required for cooling increases, so achieving the high-temperature range does not directly result in efficiency improvement. There was a limit to improvement.

In order to further improve the efficiency beyond this limit, it has been proposed to use steam instead of the above-mentioned air as the cooling medium for gas turbines.

As an example, there is one disclosed in Japanese Patent Application Laid-Open No. H05-166390. However, what is disclosed in Japanese Patent Application Laid-Open No. H05-166390 is that, apart from disclosing the concept of employing steam as a cooling medium for gas turbines, the details must be devised and solved. There are many issues to be addressed. For example, when the gas turbine is started, air remaining in the steam cooling system must be purged. For this reason, Japanese Patent Application Laid-Open No. H05-169690 discloses that steam is supplied from an auxiliary steam system or the like. In order to purge the air remaining in the system, the drain generated in the system through these series of operations has not been stopped at all, and no consideration has been given.

In other words, this steam cooling is still in a trial and error stage, and there is no example of the prior art that purges the drain from the steam cooling system when starting the gas turbine.

As described above, in conventional steam cooling, when purging air remaining in the steam cooling system at the time of startup, steam is supplied from an auxiliary steam system or the like to purge air remaining in the system. At this time, there is a problem that air is mixed into the steam and raises dissolved oxygen in the water, resulting in oxidative corrosion of the boiler tube. In addition, the injection of the purge steam generates drain in the cooling section of the gas turbine, and the drain may locally block the cooling passage, make the metal temperature non-uniform, and promote the generation of thermal stress.

Furthermore, if the local cooling passage is blocked by the drain at the tip of the blade of the rotating part, etc., due to the water retained at the tip of the blade, the generation of a superheated portion due to partial insufficient cooling, Also, due to the unbalance of gravity, excessive centrifugal force may be generated, which may lead to an unexpected large accident.

The present invention focuses on various problems due to the presence of such a drain, and ensures that the drain is purged and that the drain is removed, in other words, the warm-up is completed when the gas bin is started. The task is to provide something that ensures that it has been done. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and combines a gas turbine and a steam turbine to generate steam for driving a steam turbine using exhaust heat from a gas turbine. An exhaust heat recovery boiler, and a steam cooling system for cooling a high temperature cooled portion of the gas turbine with steam. In a combined cycle power plant configured to collect superheated steam from the cooling system into a steam bin, a means for detecting the flow rate of steam at the inlet and outlet of the steam cooling system is provided. A combined cycle power generation plant configured to determine when the warming of the steam cooling system has been completed, and if the deviation between the steam flow at the inlet and the steam However, the residual air and drain are not scattered between the inlet and outlet, and it is good to proceed to the step of starting the gas evening bin assuming that the warm-up is completed.

The present invention also provides a gas turbine plant and a steam turbine plant, comprising a waste heat recovery poirer for generating steam for driving a steam bin by using waste heat from the gas turbine. In a combined cycle power plant configured to provide a steam cooling system for cooling a high-temperature portion to be cooled with steam, and to collect superheated steam from the steam cooling system in a steam turbine, the temperature of outlet steam of the steam cooling system Provided is a combined cycle power plant that is provided with a means for detecting the temperature of the steam cooling system at the time of startup based on the outlet temperature. The deviation from the inlet steam temperature of the steam cooling system is below the permissible value, or When the temperature becomes equal to or higher than the saturation temperature at the gas supply pressure, no residual air and drain are scattered between the inlet and the outlet. . BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory diagram schematically showing cooling steam flow rate and temperature measurement at the entrance and exit of a steam cooling system according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing a steam cooling system of a moving blade portion of a gas turbine. FIG. 3 is an explanatory diagram showing an enlarged part A of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to FIGS. 1 schematically shows a high-temperature cooled part of the gas turbine, for example, 1a is a combustor, 1b is a dynamic part, and lc is a stationary blade part.

Reference numeral 2 denotes a steam supply pipe, which has an inlet-side flow meter 3a on the upstream side where steam enters the high-temperature cooled part 1 and an outlet on the downstream side where steam exits correspondingly. A side flow meter 3b is provided.

4a is an inlet-side thermometer, 4b is an outlet-side thermometer.Similar to the inlet-side flowmeter 3a and the outlet-side flowmeter 3b, they are separately provided on the upstream side and downstream side of the high-temperature cooled part 1. Have been.

Reference numeral 5 denotes a first subtractor, which calculates the output difference between the inlet side flow meter 3a and the outlet side flow meter 3b, applies the result to the first comparator 6, and compares the result with the set value. Similarly, reference numeral 7 denotes a second subtractor which calculates the outputs of the inlet thermometer 4a and the outlet thermometer 4b, applies the result to the second comparator 8, and compares the result with the set value. .

Reference numeral 9 denotes an auxiliary steam supply pipe communicating with an auxiliary steam source (not shown), and reference numeral 10 denotes a cooling steam supply pipe, which is connected to the steam supply pipe 2 by on-off valves 9 a and 10 a provided in respective pipes. They are now in communication. 11, 12, and 13 indicate drain valves, respectively.

FIG. 2 schematically shows a high-temperature cooled portion 1b of the gas turbine blade, and a cooling steam outward path 2a indicated by a solid line in which cooling steam is supplied from the steam supply pipe 2 in the blade 21. It has a cooling steam return path 20a indicated by a dotted line for collecting the superheated steam to the high-temperature steam recovery pipe 20. FIG. 3 shows the drain D retained at the tip of the wing 21. In the present embodiment configured as above, when the gas turbine is started, the on-off valve 10a is closed, the on-off valve 9a is opened, and the auxiliary steam supply pipe 9 is communicated with the steam supply pipe 2. The steam is supplied to the hot cooled part 1 of the gas bottle.

The introduction of the steam purges the air remaining in the system, and also drains out of the system through the drain discharge lines 14, 15, and 16. The drain valves 11, 12, and 13 are configured to be appropriately closed when the warming of this system is completed.

When the supply of steam continues, the warming of the high-temperature cooled part 1 gradually progresses. During this time, the flow meters 3a and 3b and the thermometers 4a and 4b continue to measure. Looking at the flowmeters _3a and _3b , the measured value _Fln of the inlet flowmeter _3a and the measured value F of the outlet flowmeter 3b. F _in — F output from the first subtractor 5 based on _ut . value of _ut is compared with a preset value in the first comparator 6 (permissible value), F _in - F. _{When ut} ≤ allowable value, it is determined that warming is completed, and comparator 6 outputs warming complete command A.

On the other hand, Come to about thermometer 4 a, 4 b, the measured value of the measured value T _in the exit side thermometer 4 b of the inlet temperature meter 4 a T. second subtractor 7 T outputted from _in based on _ut - T value of _{o ut} is compared with a preset value in the second comparator 8 (tolerance), _n - T. _{When ut} ≦ tolerable value, it is determined that the warming is completed, and the comparator 8 outputs the warming complete command B, just like the flow meter.

Although not shown, the measured value T of the outlet thermometer 4b. _ut is compared with the saturation temperature at the steam supply pressure. _{When ut} —saturation temperature ≥ permissible value, the warming completion command C is output in exactly the same way as with the flow meter and thermometer.

The warming can be completed by each of the warming completion commands A, B, and C obtained in this manner or by satisfying the AND condition of at least two of these commands. It can be determined appropriately according to the scale of the equipment, required accuracy, etc.

When the high temperature cooled part 1 of the gas turbine is a movable part, that is, the high temperature cooled part lb of the turbine blade, the step of surely discharging the drain at the tip part while performing the evening (at a low speed) should be included. Is preferred. In other words, if the drain remains on the movable parts, especially on the tip of the turbine, it may cause excessive centrifugal force and imbalance, etc., which may lead to a major accident. You have to be careful.

In addition, a thermocouple or the like may be buried in advance in a local portion where drain is likely to accumulate due to its structure, and measurement may be performed to judge the completion of warming. Although the present invention has been described with reference to the illustrated embodiments, the present invention is not limited to such embodiments, and it goes without saying that various changes may be made to the specific structure within the scope of the present invention. Absent. Industrial applicability

As described above, according to the present invention, when starting the gas turbine, the air remaining in the steam cooling system is purged, and the drain generated in this process is removed, whereby the steam cooling system is warmed up. The fact that it was possible to proceed smoothly with the above series of operations was accurately determined from the deviation of the cooling steam flow rate at the entrance and exit of the steam cooling system, and the safety and stability of the operation were further improved. .

Further, according to the invention of claim 2, the completion of the warm-up can be accurately determined from the deviation of the cooling steam temperature at the entrance and exit of the steam cooling system, and the safety and stability of the operation can be further improved. It is a thing.

Claims

1 Claims

1. Combination of a gas turbine plant and a steam turbine bin plant, equipped with an exhaust heat recovery boiler that generates steam for driving the steam turbine using exhaust heat from the gas turbine, In a combined cycle power plant that is equipped with a steam cooling system that cools the cooling section with steam and that allows superheated steam from this steam cooling system to be recovered by a steam turbine, the flow rate of steam at the entrance and exit of the steam cooling system is detected. A combined cycle power plant characterized in that the steam cooling system warm-up completion time at the time of startup is determined based on the deviation of the inlet / outlet flow rate.

2. Combination of a gas turbine and a steam turbine plant, equipped with an exhaust heat recovery poirer that generates steam for driving the steam turbine by using the exhaust heat from the gas turbine, and the high temperature cooling of the gas turbine A combined cycle power generation plant configured to provide a steam cooling system that cools the section with steam, and to collect superheated steam from the steam cooling system in a steam bin, adjusts the temperature of the outlet steam of the steam cooling system. A combined cycle power plant wherein a means for detecting the temperature is provided, and the completion temperature of the steam cooling system at the time of startup is determined based on the outlet temperature.