JPS6138110A - Method and device for humidity control of low pressure unit of mixed pressure turbine - Google Patents

Abstract

PURPOSE:To enable the humidity in a low pressure unit to be simply and securely reduced at the starting time etc. by introducing the external steam having a temperature higher than that of low pressure steam into the low pressure unit of a mixed pressure turbine so as to control the humidity in the low pressure unit through adjustment of the temperature of at least low pressure steam. CONSTITUTION:A mixed pressure turbine 7 having a high pressure unit and a low pressure unit is supplied with high pressure steam and low pressure steam in its high pressure and low pressure unit from a high pressure and a low pressure steam system 5 and 6 respectively. In this case, a high temperture steam lead piping 17 is laid between steam stop valves 11, 12 and steam control valves 13, 14 in each of steam systems 5, 6 respectively, to provide connection route therebetween and a steam control valve 18 is interposed on the way of said piping 17. In addition, detectors 19-24 for pressure, temperature and steam flow rate respectively are disposed in steam systems 5 and 6 repeatively and the humidity in the low pressure unit is calculated by arithmetic unit 32 biased upon the detection signals from those detectors. The calculated humidity is compared with the allowable humidity with a discriminator 33 and the steam control valve 18 is controlled according to the result of comparison via a valve switching unit 36 etc.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention provides a method and apparatus for controlling the humidity of a low pressure section of a mixed pressure turbine, which includes a high pressure section having a high pressure steam system and a low pressure section having a low pressure steam system. In particular, steam turbines,
The present invention relates to a method and apparatus for controlling humidity in a low pressure section of a mixed pressure turbine suitable for controlling wet steam generated in a low pressure stage of a gas turbine or a combined cycle steam turbine having an exhaust gas collection boiler.

[Background of the invention]

In recent years, combined cycle plants consisting of a gas turbine having a compressor, a boiler that recovers exhaust gas heat from the gas turbine, and a steam turbine have been increasingly used as high-efficiency power plants.

Figure 1 shows the system concept of this combined cycle plant.

In the combined cycle plant shown in this figure, exhaust gas discharged from a gas turbine 1 is recovered in an exhaust gas recovery boiler 2. The exhaust gas recovery boiler 2 is equipped with a high pressure drum 3 and a low pressure drum 4.

Further, the steam turbine 7 is connected to a high-pressure steam system 5 that uses steam after the high-pressure drum 3 and a low-pressure steam system 6 that uses the low-pressure drum 4 as a heat source.

A cycle from the condenser 8 to the exhaust gas recovery boiler 2 is then configured.

In the conventional combined cycle plant, the steam temperature of the exhaust gas recovery boiler 2 of the gas turbine rapidly decreases compared to the rated load at startup and at low load, and this characteristic is shown in Figure 2. .

The temperature change 9 in the high-pressure steam system is larger than the temperature change 10 in the low-pressure steam system 4, and since the amount of steam to the steam turbine 7 is higher than the amount of low-pressure steam, the inside of the steam turbine 7 The humidity level in the low-pressure area after work is greatly affected by the temperature of the high-pressure steam source. That is, as shown in FIG.

The wet area in the low pressure area becomes larger when the load is low.

When a steam turbine is operated for a long time under highly humid steam, there is a problem in that the rotor blade tip inlet and steam passage are eroded by flying water droplets.

For this reason, in conventional steam turbines used under steam conditions with high humidity, corrosion-resistant stellite plates are installed at the tips of the rotor blades, and after capturing condensate, pressure is Countermeasures against wet steam have been taken, such as installing special structural members to drain condensate into bleed pipes and condensers with low temperatures. As a result, there was a problem that the product cost increased.

In addition, a change in operating conditions in a steam turbine from superheated steam to wet steam causes the steam turbine itself to cool down rapidly, resulting in increased differential expansion, induction of shaft vibration, sudden changes in thrust force, and other dangerous situations for turbine operation. There was also a problem with the problem.

[Purpose of the invention]

An object of the present invention is to provide a humidity control method for a mixed pressure turbine that can easily and reliably reduce the humidity in a low pressure section during startup or low load operation of the mixed pressure turbine. The object of the present invention is to provide a humidity control method for a mixed pressure turbine that can more accurately control the humidity in a low pressure section.
Another object is to provide a humidity control method for a mixed pressure turbine that can reliably control the humidity in a low pressure section within an allowable range, and a still further object is to provide a method for controlling humidity in a mixed pressure turbine, and to ensure that the method is carried out reliably. An object of the present invention is to provide a humidity control device for a low pressure section of a mixed pressure turbine.

[Summary of the invention]

A first aspect of the present invention is to introduce external steam having a higher temperature than low pressure steam into the low pressure section of a mixed pressure turbine including a high pressure section and a low pressure section, to adjust the temperature of at least the low pressure steam, and to adjust the temperature of at least the low pressure steam. The feature is that the humidity level is controlled, and with this configuration, the humidity level itself of the low pressure section can be reliably controlled.

A second invention of the present invention is, in the first invention,
Calculate the humidity of the low pressure part from the pressure, temperature and steam flow rate of high pressure steam and the pressure, temperature and steam flow rate of low pressure steam,
The feature is that the humidity level in the low pressure area can be controlled even more accurately with this configuration.

A third invention of the present invention is, in the second invention,
The feature is that the calculated humidity of the low pressure section is compared with the permissible humidity, and the turbine operation is controlled so as not to exceed the permissible humidity. humidity can be reliably controlled within the permissible humidity range. Here, the technical meaning of controlling turbine operation means specifically changing the amount of high-temperature steam introduced.

This refers to changing the load, etc.

A fourth aspect of the present invention is that a high-temperature steam introduction pipe is connected to the low-pressure steam system of a mixed-pressure turbine having a high-pressure steam system and a low-pressure steam system, and a steam control valve is provided in the high-temperature steam introduction pipe. With this configuration, the first invention can be reliably implemented.

Moreover, the fifth invention of the present invention is the fourth invention, in which pressure is applied to each of the high and low pressure steam systems.

The feature is that a temperature and steam flow rate detector is installed, and a calculation unit is installed that takes in the detected values from these pressure, temperature and steam flow rate detectors and calculates the humidity near the rear stage of the low pressure section. The second invention can also be carried out reliably.

Furthermore, the sixth invention of the present invention is the fifth invention, wherein a humidity determiner is provided which takes in the calculated value from the humidity calculating section of the low pressure section and compares it with the permissible humidity. This invention is characterized in that it is provided with a control section that takes in the determination result and controls the operation of the turbine so that the permissible humidity is not exceeded, and with this configuration, the third invention can also be carried out reliably. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows a first embodiment of an apparatus for carrying out the method of the present invention, and FIG. 5 shows a diagram for determining humidity from the enthalpy of the exhaust section of the low pressure section of a steam turbine.

In this first embodiment, high-pressure steam is supplied from a high-pressure steam system 5 to the high-pressure part of the steam turbine 7, which is a mixed-pressure turbine having a high-pressure part and a low-pressure part, and a low-pressure steam system to the low-pressure part. Low pressure steam is supplied from 6.

The high and low pressure steam systems 5, 6 are equipped with steam stop valves 11.1.
2 and a steam control valve 13.14. Between the position N15 set between the steam stop valve 11 and the steam control valve 13 of the high pressure steam system 5 and the position W116 set between the steam stop valve 12 and the steam control valve 14 of the low pressure steam system 6. , high-temperature steam introduction piping 1
7 is connected, and this high temperature steam introduction pipe 17 is provided with a steam control valve 18.

A pressure detector 19.2 is installed in the high and low pressure steam systems 5 and 6.
0, temperature detector 21.22, and steam flow rate detector 23.
24 is attached.

Pressure detector 19 and temperature detector 21 of the high-pressure steam system 5
An enthalpy calculator 26 at the inlet of the high pressure section is connected to the pressure detector 20 and temperature detector 22 of the low pressure steam system 6.
is connected to an enthalpy computing unit 26 at the inlet of the low pressure section. The arithmetic units 25 and 26 contain a steam table 2.
7 is connected.

The steam flow rate detector 23 of the high-pressure steam system 5 and the enthalpy calculator 25 at the inlet of the high-pressure part are connected to a calculator 28 for calculating the enthalpy of the high-pressure part exhaust steam.

The steam flow rate detector 24 of the low-pressure steam system 6, the enthalpy calculator 26 of the low-pressure section inlet, and the enthalpy calculator 28 of the high-pressure exhaust steam include an enthalpy calculator of the mixing section of high-pressure exhaust steam and low-pressure steam. 29 are connected.

An exhaust section pressure detector 30 is attached to the exhaust section of the bottom pressure section of the steam turbine 7.

The enthalpy calculator 29 of the mixing section and the pressure detector 30 of the exhaust section include a calculator 3 that calculates the enthalpy of the exhaust section.
1 is connected. This calculator 31 is connected to a calculator 32 that calculates the humidity of the low pressure section. moreover,
A humidity determiner 33 is connected to the calculator 32, which compares the humidity of the low pressure section with the permissible humidity.

A continuous operation signal transmitter 34 and a valve regulator 35 are connected to the humidity determination device 33, and a valve opening/closing device 36 is connected to the valve regulator 35. This valve switch 35 is connected to a steam control valve 18 provided in the high temperature steam introduction pipe 17.

In this embodiment, a pressure detector 19, a temperature detector 21, and a steam flow rate detector 23 are installed in the high-pressure steam system 5.
, a pressure detector 20 attached to the low pressure steam system 6
, temperature detector 22. Steam flow rate detector 24, high pressure section inlet enthalpy calculator 25. Calculator 26 for the enthalpy of the inlet of the low pressure section, steam table 27, and calculator 28 for the enthalpy of the exhaust steam in the high pressure section. The enthalpy calculation unit 29 of the mixing section, the exhaust pressure detector 30 of the steam turbine 7, the exhaust part enthalpy calculation unit 31, and the humidity calculation unit #132 constitute a humidity calculation unit near the rear stage of the low pressure section. , the humidity determination H1!33, the valve regulator 35 and the valve switch 3
6 constitutes a turbine control section that controls the humidity so as not to exceed the permissible humidity.

Next, an embodiment of the method of the present invention will be explained in relation to the operation of the first embodiment.

Simultaneously with the start of operation of the steam turbine 7, the pressure detector 19 and temperature detector 21 attached to the high-pressure steam system 5 detect the steam pressure and temperature at the inlet of the high-pressure section, and send the detected values to the calculator 25. . On the other hand, the steam pressure and temperature at the inlet of the low pressure section are detected by a pressure detector 2 and a temperature detector 22 attached to the low pressure steam system 6, and the detected values are sent to the calculator 2.
Send to 6.

The computing unit 25 takes in the steam pressure and temperature, calculates the enthalpy at the inlet of the high pressure section using the steam table 27,
The calculated value is sent to arithmetic unit No. 28. Further, the arithmetic unit 26 takes in the steam pressure and temperature, and the steam table 2
7 to calculate the enthalpy at the inlet of the low pressure section, and send the calculated value to the calculator 29.

Further, the flow rate of high pressure steam is detected by a steam flow rate detector 23 attached to the high pressure steam system 5, and the detected value is sent to a computing unit 28. At the same time as this.

The flow rate of low pressure steam is detected by the steam flow rate detector 24 attached to the low pressure steam system 6, and the detected value is calculated @29
send to

The calculation ff128 takes in the enthalpy at the inlet of the high-pressure part from the calculator 25, and also takes in the flow rate of high-pressure steam from the steam flow rate detector 23, and calculates the enthalpy of the high-pressure part exhaust steam using pre-stored values, The calculated value is sent to the next computing unit 29.

The calculation fllt29 takes in the flow rate of low-pressure steam from the steam flow rate detector 24, takes in the enthalpy at the inlet of the low-pressure part from the calculation unit 26, takes in the enthalpy of the high-pressure part exhaust steam from the calculation unit 28, and calculates the high-pressure steam and The enthalpy of the low-pressure steam mixing section is calculated, and the calculated value is sent to the next computing unit 31.

The calculation WI 31 takes in the enthalpy of the mixing part from the calculation unit 29, further takes in the exhaust steam pressure of the low pressure part from the exhaust part pressure detector 30, calculates the enthalpy of the exhaust part, and sends the calculated value to the calculation unit 32. send.

The computing unit 32 takes in the enthalpy of the exhaust part of the low pressure section from the computing unit 31, calculates the humidity of the low pressure section of the steam turbine 7 from the table shown in FIG. 5, and sends it to the humidity determination unit 33.

The humidity determiner 33 takes in the humidity of the low pressure part of the steam turbine 7 from the calculator 32, compares this humidity with an allowable humidity, and determines if the humidity of the low pressure part is smaller than the allowable humidity. sends an operation continuation command to the continuation operation signal transmitter 34, and sends a valve adjustment command to the valve regulator 35 if the humidity of the low pressure section is higher than the permissible humidity. Then, the valve regulator 35 sends a control signal to the valve switch 36, and the valve regulator 35 sends a control signal to the valve switch 36.
controls a steam control valve 18 provided in a high-temperature steam introduction pipe 17 connected between the high-pressure steam system 5 and the low-pressure steam system 6.

As a result, a part of the high-pressure steam as high-temperature steam is branched from the high-pressure steam system 5 to the introduction pipe 17, and the high-pressure steam is mixed with the low-pressure steam in the low-pressure steam system 6, and the pressure and temperature of the low-pressure steam are adjusted. The moisture is sent to the inlet of the low-pressure section of the steam turbine 7, thereby automatically controlling the humidity of the low-pressure section so that it does not exceed the permissible humidity.

Next, FIG. 6 shows a second embodiment of the present invention.

In this embodiment, the bleed air stop valve 3 of the extraction steam system 37 is
Position 39 set downstream of 8 and position II set between the steam stop valve 12 and steam control valve 14 of the low pressure steam system 6! A high temperature steam introduction pipe 40 is connected between the 9 and 16, and a steam control valve 41 is provided in this 9 introduction pipe 40.

In this embodiment, a part of the extracted steam extracted from the high-pressure section stage of the steam turbine 7 is branched from the extracted steam system 37 to the high-temperature steam introduction pipe 40, passes through the steam control valve 41, and passes through the low-pressure steam system 6. The steam is introduced into the steam turbine, mixed with low-pressure steam, and supplied to the low-pressure section of the steam turbine 7, thereby adjusting the temperature of the low-pressure steam and controlling the humidity of the low-pressure section.

Regarding other configuration 9 effects of this second embodiment,
This is similar to that of the first embodiment.

In addition, the above-mentioned No. 1. In the second embodiment, a display device or a recording device may be connected to the arithmetic unit 32 that calculates the humidity level of the exhaust section, so that the humidity level can be monitored. Furthermore, a device that issues an alarm when the humidity of the exhaust section exceeds the permissible humidity may be connected to the humidity determiner 33 that compares the humidity of the exhaust section with the permissible humidity.

Next, FIG. 7 shows an i-s diagram of the present invention.

The solid line in Fig. 7 is the 1-8 line diagram at high load.
The steam generated by the exhaust gas recovery boiler is located at point A at the rated load, and is located at point B because it does work in the high pressure section before mixing the high pressure steam and low pressure steam of the steam turbine.

On the other hand, after the steam from the low-pressure steam inlet and the high-pressure steam are mixed, it is at point 0. From this zero point, the low pressure stage exhaust steam is at point D by doing work in the low pressure section of the steam turbine.

On the other hand, at startup or at a point where the steam flow rate is low at low load, the pressure in each part decreases, and furthermore, the steam temperature generated by the exhaust gas recovery boiler is low, so the high pressure steam inlet is located at point A, and the Before mixing high pressure steam and low pressure steam, the point is at B1, after mixing high pressure steam and low pressure steam, it is at point 01, and the low pressure stage exhaust steam is at point B1.

In the present invention, the two-dot line ■ in FIG. It is an i-s diagram when it is made to mix in.

The i-s diagram at high load is the same as the 1-ss diagram shown by the solid line ■ because the humidity is small.

At low loads, as shown in Figure 7; dot-dashed line ■, the humidity in the exhaust section of the low-pressure section increases, so by putting some of the high-pressure steam into the low-pressure steam system rather than the high-pressure steam system, , in the mixing section of the high pressure section and low pressure section, after mixing high pressure steam and low pressure steam, it goes to point C2, and the low pressure stage exhaust steam goes to point B2.
It becomes a point. Also.

By introducing a portion of the oil/gas E from the oil/air steam system to the low pressure steam system, after mixing the high pressure steam and low pressure steam in the mixing section, the temperature reaches point C3, and the low pressure stage exhaust steam reaches the point.

As the enthalpy of the low pressure stage exhaust steam increases from point D to point B2 or point Ds due to the action of the present invention,
At the same exhaust pressure, the humidity level decreases.

The calculator 29 shown in FIGS. 4 and 5 calculates the points C, , C, , C in FIG. 7, and the calculator 32 calculates the points C, , D2, . D. It is designed to calculate points.

〔Effect of the invention〕

According to the first aspect of the present invention described above, external steam having a higher temperature than low pressure steam is introduced into the low pressure section of the mixed pressure turbine including a high pressure section and a low pressure section, and at least the temperature of the low pressure steam is adjusted. However, since the humidity in the low-pressure section is controlled, the humidity in the low-pressure section can be easily and reliably reduced when starting up the mixed-pressure turbine or during low-load operation. This has the effect of improving the reliability of operation, and also has the effect of omitting countermeasures against scattered water droplets due to humidity.

Further, according to the second invention of the present invention, in the first invention, the pressure, temperature, and steam flow rate of the high-pressure steam,
Since the humidity of the low-pressure section is calculated and monitored from the pressure, temperature, and flow rate of the low-pressure steam, the humidity of the low-pressure section can be controlled more accurately.

Furthermore, according to the third aspect of the present invention, the calculated humidity of the low pressure section is compared with the permissible humidity, and the operation of the turbine is controlled so as not to exceed the permissible humidity. This has the effect of reliably controlling the humidity of the area within the permissible humidity range.

According to the fourth aspect of the present invention, a high-temperature steam introduction pipe is connected to the low-pressure steam system of the mixed-pressure turbine having a high-pressure steam system and a low-pressure steam system, and the high-temperature steam introduction pipe is connected to the high-temperature steam introduction pipe. Since the control valve is provided, there is an effect that the first invention can be implemented reliably.

Furthermore, according to the fifth invention of the present invention, in the fourth invention, pressure, temperature and steam flow rate detectors are respectively attached to the high and low pressure steam systems.

The second aspect of the present invention is achieved because it is provided with an arithmetic unit that takes in the detected values from these pressure, temperature, and steam flow rate detectors and calculates the humidity near the rear stage of the low-pressure section.

There is also an effect that can be implemented with certainty.

Furthermore, according to the sixth aspect of the present invention, in the fifth aspect, a humidity determiner is provided which takes in the calculated value from the humidity calculating section of the low pressure section and compares it with the permissible humidity. Since a control unit is provided which takes in the determination result of the moisture level determiner and controls the operation of the turbine so as not to exceed the permissible humidity level, the third aspect of the invention can also be reliably implemented.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a mixed pressure turbine which is a combined cycle steam turbine, Fig. 2 is a steam temperature characteristic diagram of the steam turbine, Fig. 3 is a humidity characteristic diagram of the steam turbine, and Fig. 4 is a method of the present invention. FIG. 5 is a diagram showing the enthalpy-to-humidity of the exhaust section of the low-pressure part of the steam turbine, and FIG. 6 is a block diagram showing the first embodiment of the apparatus for carrying out the method of the present invention. A block diagram showing a second embodiment of the device;
Figure 7 shows the humidity level 1-t when the method of the present invention is carried out.
It is an s-line diagram. 5.6... High and low pressure steam system, 7... Steam turbine. 17... High-temperature steam introduction pipe for introducing a part of high-pressure steam into the low-pressure steam system, 18... Steam control valve of the introduction pipe, I
L20...Pressure detector, 21.22...Temperature detector, 23.24...Steam flow rate detector, 25.26...
Calculator for enthalpy of high and low pressure section inlet, 27... Steam table, 28... Calculator for enthalpy of high pressure exhaust steam, 29... Calculator for enthalpy of high pressure steam and low pressure steam mixing section , 30... Exhaust part pressure detector, 31... Exhaust part enthalpy calculator, 32... Exhaust part humidity calculator, 33... Calculated humidity and allowable humidity. Humidity determination device for comparing, 35...Valve regulator, 36.
...Valve switch of steam control valve, 37...Oil steam system,
40... High-temperature steam introduction piping that introduces a portion of oil steam into the low-pressure steam system, 41... Steam control valve.

Claims (1)

[Claims] 1. External steam having a higher temperature than the low-pressure steam is introduced into the low-pressure part of the mixed-pressure turbine equipped with a high-pressure part and a low-pressure part, and at least the temperature of the low-pressure steam is adjusted to reduce the humidity of the low-pressure part. A method for controlling humidity in a low pressure section of a mixed pressure turbine, characterized by controlling humidity. 2. Introducing external steam having a higher temperature than the low-pressure steam into the low-pressure part of the mixed-pressure turbine equipped with a high-pressure part and a low-pressure part, adjusting at least the temperature of the low-pressure steam, and controlling the humidity of the low-pressure part, A method for controlling humidity in a low pressure section of a mixed pressure turbine, characterized in that the humidity in the low pressure section is calculated and monitored from the pressure, temperature, and steam flow rate of high pressure steam and the pressure, temperature, and steam flow rate of low pressure steam. 3. Introducing external steam having a higher temperature than the low-pressure steam into the low-pressure part of the mixed-pressure turbine equipped with a high-pressure part and a low-pressure part, adjusting at least the temperature of the low-pressure steam, and controlling the humidity of the low-pressure part, Calculate the humidity of the low pressure section from the pressure, temperature and steam flow rate of high pressure steam and the pressure, temperature and steam flow rate of low pressure steam, compare this calculated value of humidity with the allowable humidity,
A method for controlling humidity in a low pressure section of a mixed pressure turbine, the method comprising controlling the operation of the turbine so as not to exceed an allowable humidity. 4. Connecting high-temperature steam introduction piping to the low-pressure steam system of a mixed-pressure turbine having a high-pressure steam system and a low-pressure steam system,
A humidity control device for a low pressure section of a mixed pressure turbine, characterized in that a steam control valve is provided in the high temperature steam introduction pipe. 5. Connecting a high-temperature steam introduction pipe to the low-pressure steam system of a mixed-pressure turbine having a high-pressure steam system and a low-pressure steam system,
A steam control valve is installed in the high-temperature steam introduction piping, and pressure, temperature, and steam flow rate detectors are installed in the high- and low-pressure steam systems, respectively, and the detected values from these pressure, temperature, and steam flow rate detectors are taken in to What is claimed is: 1. A humidity control device for a low pressure section of a mixed pressure turbine, characterized in that it includes a calculation section that calculates humidity near a rear stage. 6. Connecting high-temperature steam introduction piping to the low-pressure steam system of a mixed-pressure turbine having a high-pressure steam system and a low-pressure steam system,
A steam control valve is installed in the high-temperature steam introduction piping, and pressure, temperature, and steam flow rate detectors are installed in the high- and low-pressure steam systems, respectively, and the detected values from these pressure, temperature, and steam flow rate detectors are taken in to A calculation unit is provided to calculate the humidity in the vicinity of the subsequent stage, and a humidity determination device is provided to take in the calculated value from the calculation unit and compare it with the allowable humidity. 1. A humidity control device for a low pressure section of a mixed pressure turbine, characterized in that a controller is provided for controlling the operation of the turbine so that the humidity does not exceed .