JPS62279204A - Temperature control method for mixed pressure turbine - Google Patents

Abstract

PURPOSE:To prevent overheating by controlling stage temperatures by using the detected values of the pressures, temperatures, flow rates of high-pressure steam and low-pressure steam, and the pressure in the stage being the control object so as to cool properly and effectively the vicinity of the final stage of a low-pressure turbine. CONSTITUTION:By detecting the pressure 17, temperature 18, and flow rate 22 at the inlet part of a high-pressure turbine 4, the enthalpy at the high-pressure inlet part is calculated by an arithmetic unit 20. By detecting the pressure 23, temperature 24, flow rate 26 at the inlet part of a low-pressure turbine 5, the enthalpy at the low-pressure inlet part is calculated by an arithmetic unit 25. An arithmetic unit 27 calculates the enthalpy at the mixing part of high-pressure steam and low-pressure steam. If the temperature in the relevant stage exceeds a permissible temperature, a temperature discriminator 29 commands the valve adjustment to a valve regulator 30. A valve closing gear 32 opens or closes an admission valve 34 to introduce admission steam into a low-pressure turbine 5. Thus, the vicinity of the final stage of the low-pressure turbine is properly and effectively cooled, enabling the prevention of overheating. A surplus steam.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for managing a mixed-pressure steam turbine, and in particular, the present invention relates to a method for managing a mixed pressure steam turbine. This invention relates to a temperature control method for a mixed pressure turbine that prevents overheating due to wind damage near the final stage of a steam turbine and enables safe operation.

[Conventional technology]

Steam turbine plants in recent years are required to be able to follow load fluctuations in a short period of time, and a typical operation mode is in-plant isolated operation at low loads.

In this type of operation, the steam turbine may stand by at a low flow rate in order to raise the plant to a constant load again, but since the rotor blade length is large near the final stage of the steam turbine,
Temperature rise due to wind damage during standby was a problem.

In addition, in recent years, combined plants have been increasingly used as high-efficiency plants, and in single-shaft combined plants where a gas turbine and a steam turbine are combined into a single shaft, steam is generated from a boiler that uses the exhaust gas of the gas turbine as a heat source. Steam turbines increase load more slowly than gas turbines.

That is, the steam turbine is operated at increased speed and under no load by the gas turbine, and there is a problem in that the temperature rises due to windage damage and the sealing steam causes significant heating, particularly in the vicinity of the low-pressure final stage.

Conventionally, in order to eliminate this drawback, an auxiliary steam source and auxiliary steam piping were installed, and a thermometer was installed near the low-pressure final stage to sense the temperature rise in the low-flow region of the steam turbine and A device was devised to guide the cooling steam (Japanese Patent Application No. 56-210662).

[Problems to be Solved by the Invention] In addition to the disadvantage that the installation of an auxiliary boiler incurs a large cost increase, the above-mentioned conventional technology has the disadvantage that the thermometer near the low-pressure final stage is installed in the steam stagnation area, or the temperature The disadvantage was that the gauge would indicate the temperature of the low-pressure turbine casing, etc., and would not accurately display the steam temperature.

An object of the present invention is to provide a new temperature control method for preventing steam turbine overheating when the steam turbine is operating independently in a station or when speeding up, and when operating at a low steam flow rate under no load. It is.

[Means for solving problems]

The above purpose is to eliminate the thermometer near the relevant low-pressure final stage, and to increase the pressure between high-pressure steam and low-pressure steam.

This is achieved by detecting the temperature, steam flow rate, and relevant stage pressure, and calculating the relevant stage temperature based on these data.

Furthermore, the above objective can be achieved more reliably by operating the device so that the temperature does not exceed the allowable temperature.

The above operation control can be satisfied by controlling the low pressure steam introduction valve, the admission steam introduction valve, or the bleed valve.

[Effect]

The pressure and temperature of high-pressure steam determine the enthalpy at the high-pressure turbine inlet, and the high-pressure steam flow rate and high-pressure turbine efficiency determine the effective work of the high-pressure turbine, so as a result, the enthalpy at the high-pressure turbine exhaust section is calculated. The pressure and temperature of low-pressure steam determine the enthalpy at the low-pressure turbine inlet,
Since the low-pressure turbine steam amount, which is the sum of the low-pressure steam amount and the high-pressure steam amount, and the low-pressure turbine efficiency determine the effective amount of work, the enthalpy of the low-pressure turbine exhaust portion is calculated as a result.

In this way, the i-s diagram showing the effective work state in the low-pressure turbine is obtained, and the accurate temperature of the relevant stage can be calculated by calculating the windage loss which is proportional to the pressure of the relevant stage. As in the case of temperature detection using a thermometer, there is no possibility of erroneously detecting the intermediate temperature between the exhaust chamber and the corresponding paragraph, or erroneously detecting the temperature of the corresponding paragraph depending on the installation location or method of the thermometer.

〔Example〕

Embodiments of the method of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing a mixed pressure turbine configured to carry out the present invention.

Compressor 1. A gas turbine device including a gas turbine pin 21 and a generator 3 includes a high pressure turbine 4 and a low pressure turbine 5.
The steam turbine is connected to a single shaft by a coupling 6. Gas turbines convert the energy of high-temperature, high-pressure gas into rotational energy. The exhaust gas that has done work in the gas turbine 2 flows into the steam generator 7 as a heating fluid.

The steam generator 7 is composed of a high-pressure steam generator 9 and a low-pressure steam generator 8, and the steam generated by the high-pressure steam generator 8 passes through a high-pressure steam pipe 10 to a high-pressure steam stop valve 11. The high-pressure steam flows into the high-pressure turbine 4 through the control valve 12 .

The steam generated by the low pressure steam generator 8 passes through the low pressure steam plumber 3 to the low pressure steam stop valve 14. It passes through the low-pressure steam control valve 15, flows into the low-pressure turbine 5, mixes with steam from the high-pressure turbine 4, flows from the low-pressure turbine exhaust into the condenser 16, becomes condensate, and pumps the condensate pump (not shown). It returns to the low pressure steam generator 8 via the steam generator.

(b) Based on the signal from the pressure detector 17 that detects the pressure at the high-pressure turbine inlet and the signal from the temperature detector 18 that detects the temperature of the armpit, the high-pressure inlet is (b) a calculator 21 that calculates the enthalpy of high-pressure exhaust steam by storing the relationship between load and efficiency in advance; and (c)
The high pressure steam amount detector 22 is N9M for high pressure steam.

Similarly, for low-pressure steam, (d) a pressure detector 23 that detects the pressure at the inlet of the low-pressure turbine, (e) a temperature sensor 24 that detects the temperature of the armpit, and (v) both of the above detectors. an arithmetic unit 25 that calculates the enthalpy of the low-pressure inlet section using a steam table 19 in which the signals of (
g) A low pressure steam amount detector 26 is installed. On the other hand, (ch)
A calculator 27 for calculating the enthalpy of the mixing portion of the high-pressure steam and low-pressure steam is installed for temperature calculation.

If the temperature T in the relevant paragraph exceeds the allowable temperature T^,
The temperature determiner 29 instructs the valve controller 30 to adjust the valve. If the temperature is within the allowable temperature T^, a signal is sent to the continuous operation command unit 31.

The valve opener 32 is a device that opens and closes the low pressure steam control valve 15 in response to a signal from the valve controller 3o.

FIG. 2 shows another embodiment of the invention. Admission steam flows into the low-pressure turbine 5 through an admission steam pipe 33 and an admission valve 34 in order to recover surplus steam of the plant into a part of the turbine and convert it into output.

In place of the low-pressure steam control valve 15 in the case of FIG. 1, the admission valve 34 in FIG. 2 is adjusted to control the temperature of the corresponding paragraph.

FIG. 3 shows another embodiment of the present invention. Oil steam is exhausted from between the high-pressure turbine 4 and the low-pressure turbine 5 for use in the plant through a bleed pipe 35 and a bleed valve 36. In the case of a so-called oil-air turbine in which the bleed pressure is controlled to be constant by a low-pressure regulator valve, the temperature of the corresponding stage is controlled by adjusting the bleed valve 36 in Fig. 3 instead of the low-pressure steam regulator 15 in Fig. 1. be.

Next, regarding the mixed pressure turbine temperature control method of the present invention, i-
The effect on the s-diagram will be explained with reference to FIGS. 4 and 5.

FIG. 4 is an i-s diagram showing the principle of the embodiment of FIG. 1 and the embodiment of FIG. 2. The steam generated by the exhaust gas recovery boiler is located at point A at the rated load, and is located at point 8 before the steam turbine mixed pressure section due to work performed by the high pressure turbine. On the other hand, after mixing the steam from the low-pressure steam inlet and the high-pressure steam, the temperature is 0.
At the point. By doing work in the low-pressure turbine, the low-pressure stage exhaust steam is at point D, and the corresponding stage of the low-pressure turbine is 8
It is at one point.

On the other hand, since the pressure at each part decreases at points where the steam flow rate is low at startup or under low load, the high-pressure steam inlet is located at A1, and the area before the steam turbine mixed pressure section is located at B1, where high-pressure steam and low-pressure steam are mixed. The rest is in C1, the low pressure stage exhaust steam is in Dl, and the relevant paragraph is in El. The above 81 points correspond to the pressure in the corresponding paragraph and the temperature on the expansion line, but when the temperature increase ΔT1 due to windage damage is added to the state at this point, it becomes point B1.

The two-dot chain line in FIG. 4 is an i-s diagram when low-temperature steam is mixed into the low-pressure steam turbine 5 via the low-pressure steam valve 15 or the admission valve 34 of the present invention.1 Represents the operation of the present invention. In the two-dot chain line, as low-temperature steam flows in, the temperature at the inlet of the mixed pressure section or admission steam after mixing at the inlet of the low-pressure turbine decreases to C2, and therefore the low-pressure exhaust section becomes Dl, and the corresponding paragraph becomes C2. It becomes B2. In addition to the temperature at 82 points on the expansion diagram decreasing, the amount of steam in the low-pressure turbine 5 increases, and the temperature rise ΔT2 due to wind damage in the low-pressure turbine is almost inversely proportional to the stage flow rate, so ΔT2 becomes Δ
F at the point where it becomes smaller than T1 and ΔT2 is added to B2
The temperature rise can be suppressed by lowering the temperature of 2 below that of Fl.

FIG. 5 is an i-3 diagram showing the principle of operation of the embodiment shown in FIG. Similarly to FIG. 4, in FIG. 5, when the extracted air flow rate is small, the low pressure turbine steam amount increases, and the 81 points become 82 points, making it possible to control the temperature rise of the low pressure turbine.

FIG. 6 shows an example of a starting curve of a combined cycle to explain an embodiment of the present invention.

In a single-shaft compounding plant as shown in FIG. 6(a), after the rotational speed 37 of the steam turbine and the gas turbine increases, the gas turbine load 38 increases, and then the steam turbine load 39 increases.

As shown in FIG. 6(b), the low-pressure steam control valve 15 (FIG. 1) or the admission valve 34 (FIG. 2) is opened or closed at a younger angle of the curve 41 in accordance with the opening degree curve 40 of the high-pressure steam valve 12. , or the bleed valve 36 (FIG. 3) is opened and closed as per curve 42 (opposite to curve 41).

FIG. 6(c) shows the stage temperature, where the case where the valve opening/closing control is not performed is drawn with a broken line, and the case where the valve opening/closing control is performed is drawn with a solid line.

The dashed line curve represents the temperature of the steam generated in the high pressure steam generator 9 (FIG. 1).

〔Effect of the invention〕

As detailed above, when the temperature control method of the present invention is applied to a mixed pressure turbine equipped with a high pressure steam system and a low pressure steam system,
It can properly and effectively cool the area near the final stage of the low-pressure turbine to prevent overheating during startup, speed increase, and no-load conditions.
This has an excellent practical effect of preventing overheating.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention and is a system diagram of a mixing turbine having a high pressure steam system and a low pressure steam system equipped with a stage temperature calculation and temperature control system. FIG. 2 shows another embodiment of the present invention, and is a system diagram of a mixed pressure turbine having an admission steam system. FIG. 3 shows another embodiment of the present invention and is a system diagram of an oil-air turbine. FIG. 4 is an is diagram showing the principle of the embodiment shown in FIG. 1 and FIG. 2, FIG. 5 is an is diagram showing the principle of the embodiment shown in FIG. 3, and FIG. 1 is a chart showing the startup status of a combined plant having one embodiment of the mixed pressure turbine of the present invention. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Gas turbine, 3... Generator, 4... High pressure turbine, 5... Low pressure turbine, 8
...Low pressure steam generator, 9...High pressure steam generator, 1o
... High pressure steam piping, 11 ... High pressure steam stop valve, 12
... High pressure steam control valve, 13 ... Low pressure steam piping, 14
...Low pressure steam stop valve, 15...Low pressure steam control valve, 1
7...Pressure detector, 18...Temperature detector, 19...
・Steam amount, 20.21... Arithmetic unit, 22... High pressure steam amount detector, 23... Pressure detector, 24... Temperature detector, 25... Arithmetic unit, 26... low pressure steam detector,
27...Arithmetic unit, 28...Pressure detector of the corresponding setting, 2
9... Judgment device, 30... Valve regulator. 31... Command device, 32... Valve switch, 33... Admission steam piping, 34... Admission valve,
35...Oil piping, 36...Bleed valve.

Claims (1)

[Claims] 1. In a mixed-pressure turbine equipped with a high-pressure steam system and a low-pressure steam system, the pressure, temperature, and flow rate of high-pressure steam are detected, and the pressure, temperature, and flow rate of low-pressure steam are detected, and , a mixed pressure turbine characterized in that the pressure of the paragraph to be managed is detected, the steam temperature of the paragraph is calculated using each of the detected values, and the temperature of the paragraph is controlled based on the calculated temperature. temperature control method. 2. Regarding the calculated temperature, a maximum permissible temperature is determined in advance, and the mixed pressure turbine according to claim 1 is controlled so that the calculated temperature does not exceed the maximum permissible temperature. Temperature control method. 3. The temperature control in the paragraph based on the calculated value is performed by opening or closing at least one of a low-pressure steam introduction valve, an admission valve, and a bleed valve. A temperature control method for a mixed pressure turbine according to scope 2.