JPH0491305A - Steam temperature controller of reheat type combined cycle plant - Google Patents

Abstract

PURPOSE:To settle a steam temerapure at an appropriate value so as to restrain deterioration in material force of a turbine material, in sending steam from a reheater of a waste heat recovery boiler part to an intermediate pressure turbine of a steam turbine plant part, by providing a temerature decreasing equipment, and delivering cooling steam from a drum of the waste heat recovery boiler part to this temperature decreasing equipment. CONSTITUTION:A reheat type combined cycle plant 1 is provided with a gas turbine plant part GP, a waste heat recovery boiler part HRSG, and a steam turbine plant part SP. The waste heat recovery boiler part HRSG is provided with a high tempera ture part 2a, an intermediate temperature part 2b, and a low temperature part 2c. In this case, at the time of a partial load, steam from the waste heat recovery boiler part HRSG is made at an appropriate temperature and sent to the steam turbine plant part SP. That is, a temperature decreasing equipment 24 is provided on the way from a reheater 10 of the high temperature part 2a to an inlet of an intermediate pressure turbine 3b of the steam turbine plant part SP. To a nozzle part of the tempera ture decreasing equipment 24, the cooling steam with relatively high gas degree from a third drum 5 of the high temperature part 2a is introduced, and the flow rate of this cooling steam is controlled by a regulator valve 26.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) This invention relates to a reheat type combined that heats steam sent from a reheater of an exhaust heat recovery boiler to a steam turbine at an appropriate temperature during partial load. This invention relates to a steam temperature control device for a cycle plant.

(Prior Art) In a conventional combined cycle plant, the exhaust heat recovery boiler has one or two drums, and the steam generated therefrom is sent to a steam turbine. However, this type of type cannot keep up with the recent increase in power consumption, and for this reason, we are seeing the emergence of ultra-large reheat type combined cycle plants that have three drums in the exhaust heat recovery boiler and are equipped with a reheater. ing.

FIG. 3 is a schematic diagram of a conventional reheat type combined cycle plant.

This conventional type configuration is the gas turbine plant section GP.
, exhaust heat recovery boiler section) IR5G, and steam turbine plant section SP.

The gas turbine plant section GP includes a compressor 1a, a combustor 1b, and a gas turbine 1c connected by a common shaft.

The exhaust heat recovery boiler section HR3G is located at 9 from the heat source receiving side.
A reheater 10 and a high-pressure first superheater 11 are arranged in this order, and a high-pressure evaporator 12 and a high-pressure economizer 13 which are integrated with the third drum 5 are provided. Further, the medium temperature section 2b includes a medium pressure evaporator 14 and a medium pressure economizer 15 that are integrally connected to the second drum 6. Furthermore, the low-temperature section 2c includes a low-pressure evaporator 16 and a low-pressure economizer 1 that are integrally connected to the first drum 7.
Equipped with 7. These high-temperature section 2a, medium-temperature section 2b, and low-temperature section 2c are configured as one super-large heat exchanger group to form an exhaust heat recovery boiler I (R3O), which receives a heat source and produces steam.

On the other hand, the steam turbine plant sp is g! Den 4j & 4,
Low pressure turbine 3c, intermediate pressure turbine 3b, high pressure turbine 3
This is a skewer-shaped arrangement in which the turbine shafts connect the turbine shafts.

In such a configuration, the gas turbine plant unit GP sucks atmospheric air using the compressor 1a, converts it into high-pressure compressed air, and sends it to the combustor 1b, where fuel is added to create working gas. The created working gas is passed through the gas turbine 1
c, it expands and does work, and emits high-temperature exhaust gas 18.

On the other hand, in the IR3G (exhaust heat recovery boiler section) which receives exhaust heat from the gas turbine 1c, the condensate/supply water is in the low-temperature section 2c and the medium-temperature section 2.
b. Preheating, evaporation, and superheating are repeated while passing through the high-temperature section 2a, and finally the steam is sent to the steam turbine plant section SP as superheated steam.

The steam turbine plant section SP performs expansion work using the high enthalpy of superheated steam. That is, the high temperature section 2a
The high-pressure turbine 3a that receives superheated steam from the high-pressure second superheater 9 converts the superheated steam into adiabatic dust and sends the exhaust steam to the reheater 10 of the high-temperature section 2a. The reheater 10 returns the enthalpy-depleted exhaust steam to superheated steam, and sends it out to the low-pressure turbine 3c via the intermediate-pressure turbine 3b. In this way, the rotation 1-lux of the turbine shaft obtained by the expansion work is
The signal is transmitted to the generator 4 to obtain electrical output. Note that the steam from the first drum 7 is made to flow to the low pressure turbine 3C, and the steam from the second drum 6 is made to flow to the outlet side of the high pressure turbine 3a. This is made consistent with the outlet steam temperature of the turbine 3a, etc. In this way, the enthalpy of each steam temperature, etc. is fully utilized, and the intermediate pressure turbine 3b and the low pressure turbine 3c are made to perform a large amount of expansion work.

Exhaust steam from the steam turbine plant section SP that generates electrical output for the generator 4 is condensed in a condenser 18, boosted in pressure by a pump 19 as condensate/supply water, and the pressurized water is sent to the exhaust heat recovery boiler section. After returning to HR5G, the above-mentioned preheating, evaporation, and superheating operations are repeated.

As described above, in this type of power generation plant, the exhaust heat emitted from the gas turbine LC is transferred to the exhaust heat recovery boiler section 1 (
The thermal efficiency of the entire power plant is extremely high compared to the exhaust heat recovery boiler section HR5G, which has one or two drums.Recently, improvements to conventional combined cycle power generation It has come to be applied as

(Problem to be Solved by the Invention) Although this type of power generation plant has the excellent characteristics described above, the temperature and pressure of the steam generated in the exhaust heat recovery boiler section HR3G are such that the amount of exhaust heat emitted from the gas turbine 1c is too high.
It has been seriously affected by the underrepresentation. Especially at partial load,
The exhaust heat 18 emitted from the gas turbine 1c has a specificity in that the temperature increases when the amount is small compared to the rated state, and something bad is happening.

FIG. 4 is a graph illustrating such an event. According to this graph, the exhaust heat temperature 50 from the gas turbine 1c during partial load suddenly changes and stands out compared to the reference temperature line 53 determined by the steam turbine plant part SP during rated operation, and when associated, the exhaust heat recovery boiler The steam temperature line 51 from the high-pressure second superheater 9 and the reheated steam temperature line 52 from the reheater 10 in section HR5G also suddenly change and exceed the reference temperature line 53. For this reason, the steam turbine plant part SP at partial load receives overtemperature steam even though the steam temperature at the rated time is not determined.

Therefore, the high-pressure turbine 3a and the intermediate-pressure turbine 3b, which are subjected to an unnecessarily high steam temperature, have a problem in that the turbine striking force is significantly reduced due to sudden thermal shock. In addition, the high pressure second
Considering the financial resources of the superheater 9 and the reheater 10, such thermal shock is not desirable.

In view of the fact that the above-mentioned problem occurs unless the temperature of steam sent from the exhaust heat recovery boiler section to the steam turbine plant section is controlled during partial load, this invention has been developed to control the steam from the exhaust heat recovery boiler section to an appropriate temperature to create steam. It is an object of the present invention to provide a steam temperature control device for a reheat type combined cycle plant, in which steam is sent to a turbine plant section.

[Structure of the invention]

(Means for Solving the Problems) The present invention is an exhaust heat recovery boiler section that generates steam using exhaust heat received from a gas turbine plant section,
This exhaust heat recovery boiler section has a high temperature section, a medium temperature section, and a low temperature section in order from the input side, and the steam exiting the high pressure second superheater of this high temperature section is sent to the high pressure turbine of the steam turbine plant section. In a reheat type combined cycle plant where the heat is returned to a reheater and sent from there to an intermediate pressure turbine and a low pressure turbine, a desuperheater is provided on the inlet side of the intermediate pressure turbine,
The apparatus is characterized in that a regulating valve is provided to add steam from the drum in the high temperature section or the medium temperature section to the steam from the reheater passing through the attemperator to adjust the temperature to an appropriate temperature.

(Function) Conventionally, in this kind of type, during partial load (particularly around 80% of the rated state), the temperature of the exhaust heat is higher than during the rated state. For this reason, the temperature of the steam sent from the reheater to the intermediate pressure turbine and the low turbine is high, which poses financial problems for each turbine.

According to the configuration of the present invention, the attemperator is provided on the inlet side of the intermediate pressure turbine, and when the steam from the drum in the high temperature section or the medium temperature section is added to the steam from the reheater passing through the attemperator. By controlling the amount of relatively low-temperature steam from the drum using a regulating valve, the steam from the reheater can be heated to an appropriate temperature and sent to an intermediate-pressure turbine. therefore,
Even when operating with severe steam flow rate fluctuations such as during partial load, when low-cycle fatigue of the turbine material is likely to occur, it is possible to suppress a decline in the financial strength of the turbine material.

(Example) Hereinafter, a steam temperature control device for a reheat type combined cycle plant applied to a first example of the present invention will be described with reference to the drawings.

FIG. 1 is an overall schematic diagram of a reheat type combined cycle plant according to the present invention.

Gas turbine plant section GP, exhaust heat recovery boiler section HR5
In a conventional reheat type combined cycle plant having a steam turbine plant part SP and a high temperature part 2a, medium temperature part 2b, and low temperature part 2c in the exhaust heat recovery boiler part +1R3G, in this invention, at partial load, Steam from the exhaust heat recovery boiler section HR5G is heated to an appropriate temperature and sent to the steam turbine plant section SP. That is, from the reheater 10 of the high temperature section 2a to the steam turbine plant section SP
A desuperheater 24 is provided between the intermediate pressure turbine 3b and the inlet thereof. The desuperheater 24 consists of a nozzle part that injects cooling steam at high speed, and a confluence mixing part that receives and mixes the high-temperature steam from the reheater 10. Cooling steam with a relatively high gas content from the third drum 5 of the high temperature section 2a is guided to the spout of the desuperheater 24, and the flow rate of this cooling steam is adjusted by the regulating valve 26. control is in place.

The regulating valve 26 receives a signal from a temperature detector 27 provided on the inlet side of the intermediate pressure turbine 36. The temperature detector 27 constantly detects the temperature of the steam entering the intermediate pressure turbine 3b, sends this detection signal to the PID calculator 28, which generates a valve opening/closing signal, and the mixed steam coming out of the desuperheater 24 reaches an appropriate temperature. A valve opening/closing signal is given to the regulating valve 26 in such a manner.

Therefore, when the steam coming out of the reheater 10 is overtemperature during partial load, the opening degree of the regulating valve 26 is adjusted depending on the magnitude of the overtemperature, and the steam from the third drum 5 is sent to the attemperator 24. Therefore, the mixed steam from the attemperator 24 can be brought to an appropriate temperature and sent to the intermediate pressure turbine 3b. Incidentally, the degree of temperature balance between the steam conditions from the reheater 10 and the steam conditions from the third drum 5 will be estimated. The steam from the reheater 10 has a temperature of 540° C. and a pressure of 27 ata,
Also, the cooling steam from the third drum 5 has a temperature of 300 to
The temperature was 330°C and the pressure was 100 ata. From this, if the cooling steam from the third drum 5 is added to the steam from the reheater 10, the steam temperature becomes desirable for the intermediate pressure turbine 3b.

FIG. 2 shows a second embodiment of the invention.

In the first embodiment, the cooling steam from the third tram 5 is
In addition to the steam from the reheater 10, it was sent to the intermediate pressure turbine 3b, but in the second embodiment, cooling steam is taken out from the second drum 6 of the intermediate temperature section 2b.

It is added to the steam from the reheater 10. In this case, the steam in the second drum 6 has a temperature of 220 to 250°C and a pressure of 30 ata, so if the steam coming out of the reheater 10 is not as high as expected, it is desirable for the temperature balance during mixing. . Therefore, the same effects as in the first embodiment can be achieved.

〔Effect of the invention〕

As described above, according to the steam temperature control device for a reheat type combined cycle plant according to the present invention, when steam from the reheater of the exhaust heat recovery boiler section is sent to the intermediate pressure turbine of the steam turbine plant section, A heating device was installed, and the cooling steam from the drum of the exhaust heat recovery boiler section was sent to this desuperheater, so the intermediate pressure turbine received steam at an appropriate temperature, thereby reducing the impact force of the turbine material. It can be suppressed.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram showing a first embodiment of the present invention, FIG. 2 is an overall schematic diagram showing a second embodiment of the invention, and FIG. 3 is an overall schematic diagram showing a conventional embodiment. FIG. 4 is a graph comparing exhaust heat temperature and steam temperature using the load change and temperature change of a conventional gas turbine as coordinates. GP...Gas turbine plan 1 part HR3G...
Exhaust heat recovery boiler part sp...Steam turbine plan 1 part 2a...High temperature section 2b...Medium temperature section
2c...Low temperature section 3a...High pressure turbine
3b...Intermediate pressure turbine 3c...Low pressure turbine
5...Third drum 6...Second drum
7...Third drum 10...Reheater
24... Temperature reducer 26... Regulating valve
27...Temperature detector 28...PID calculator Agent Patent attorney Noriyuki Chika

Claims (2)

[Claims] (1) An exhaust heat recovery boiler section that generates steam by using the exhaust heat received from the gas turbine plant section, and the exhaust heat recovery boiler section consists of a high-temperature section, a medium-temperature section, and a low-temperature section in order from the heat source receiving side. A reheat type combined cycle plant in which the steam exiting the high-pressure second superheater in the high-temperature section is returned to the reheater through the high-pressure turbine in the steam turbine plant section, and from there is sent to the intermediate-pressure turbine and low-pressure turbine. A regulating valve is provided on the inlet side of the intermediate pressure turbine to adjust the temperature to an appropriate temperature by adding steam from the drum of the high temperature section to the steam from the reheater that passes through the attemperator. A steam temperature control device for a reheat type combined cycle plant, characterized in that: (2) An exhaust heat recovery boiler that generates steam using exhaust heat received from a gas turbine plant section, and this exhaust heat recovery boiler section has a high temperature section, a medium temperature section, and a low temperature section in order from the heat source receiving side. In a reheat type combined cycle plant, the steam exiting the high-pressure second superheater in the high-temperature section is returned to the reheater through the high-pressure turbine in the steam turbine plant section, and from there is sent to the intermediate-pressure turbine and the low-pressure turbine. , an attemperator is provided on the inlet side of the intermediate pressure turbine, and a regulating valve is provided for adding steam from the drum of the intermediate temperature section to the steam from the reheater passing through the attemperator to adjust the temperature to an appropriate temperature. A steam temperature control device for a reheat type combined cycle plant, characterized by: