JPH10110602A - Method for controlling steam turbine and steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means which can improve the operational efficiency of a steam turbine having an air bleeding passage by which active steam is extracted from the intermediate stage of a steam turbine main body. SOLUTION: An air bleeding passage opening/closing valve 9 by which an air bleeding passage 3 is controlled to be opened and closed, is arranged in this steam turbine, and in the case that a load factor against the rated steam amount of a steam turbine main body 1 is detected from a result that a load steam amount to the steam turbine main body 1 is measured by load steam flow detecting means 11, and reaches a predetermined value on the basis of a result that exhaust temperature from the steam turbine main body 1 is detected by exhaust temperature detecting means 12, this steam turbine is operated in an air bleeding operation mode in which the air bleeding passage opening/closing valve 9 is opened and bleed air from the air bleeding passage 3 is retained when the exhaust temperature is less than a predetermined temperature. Also, when the load factor is still shy of the predetermined value or when the exhaust temperature exceeds the predetermined temperature, the steam turbine is operated in a non-air bleeding operation mode in which the air bleeding opening/closing valve 9 is closed and bleed air from the air bleeding passage 3 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of a steam turbine and a steam turbine, and more particularly, to a control method of a steam turbine having an extraction passage for extracting working steam from an intermediate stage of a steam turbine body, and a control method thereof. To a steam turbine to which the present invention can be applied.

[0002]

2. Description of the Related Art Conventionally, in a steam turbine for driving a power generation device for efficiently generating electricity by using steam from a waste heat boiler provided in a waste incinerator, an exhaust passage of a steam turbine having a bleed passage is usually provided. It has been practiced to use a bleed air as a process steam regardless of the reheating method by disposing a condenser. That is, as shown in FIG. 3, the high-pressure steam from the waste heat boiler is temporarily accumulated in the high-pressure steam reservoir 6, sent to the low-pressure steam reservoir 7 through the pressure control valve 7b, and the low-pressure steam accumulated under constant pressure control is discharged. In a system for supplying process steam to each plant in the facility, a part of the high-pressure steam is supplied to a steam turbine main body 1, and power is generated by a generator 5 driven by the steam turbine main body 1. Is extracted from the bleed passage 3 at a bleed pressure corresponding to the pressure of the low-pressure steam, and the exhaust passage 4 of the steam turbine body 1 is used.
Is returned to the boiler feedwater by the condenser 8. That is, the turbine serves as a pressure reducing mechanism for converting high-pressure steam to low-pressure steam, and the enthalpy difference at the time of pressure reduction is recovered as electric power. In addition, bleed passage 3
If the predetermined bleed pressure is not ensured due to some trouble in the above, the steam pressure of the low-pressure steam reservoir 7 is determined by operating the pressure control valve 7b based on the pressure detected by the pressure detector 7a provided in the low-pressure steam reservoir 7. Low pressure control to pressure. Here, the supply steam flow rate (that is, the load steam amount) of the high-pressure steam supplied to the steam turbine body 1 is determined by a load steam flow rate detection unit 1 provided in the air supply passage 2 of the steam turbine body 1.
The exhaust gas from the steam turbine 1 is condensed and returned to the feed water of the waste heat boiler, and the exhaust gas from the waste heat boiler with respect to the amount of process steam required in the facility is detected and adjusted. The amount of steam supplied to the steam turbine 1 corresponds to a surplus in the amount of generated high-pressure steam, and the amount of steam that can be supplied is directly affected by the amount of steam generated by the waste heat boiler.

[0003]

As described above, the amount of high-pressure steam from the waste heat boiler is not stable, that is,
A large variation in the unit calorific value of the waste to be incinerated in the waste incinerator causes a large variation in the amount of steam generated in the waste heat boiler.Therefore, there is a large variation in the surplus amount of the generated steam with respect to the process steam. , The amount of steam loaded to the steam turbine fluctuates. As a result, when bleeding is performed from the bleed passage when the load factor (that is, the ratio obtained by dividing the loaded steam amount by the rated steam amount of the steam turbine) is reduced, the bleed temperature rises extremely, and as a result, the exhaust gas is exhausted. There is a problem that the temperature also rises to cause a state in which it becomes difficult to drive the steam turbine, and at the same time, there is a problem that the power generation efficiency of the steam turbine in an operation at a low load factor is extremely reduced. In other words, unlike the usage state of the reheated extraction steam turbine that reheats the extraction air and returns it to the low pressure stage, in a steam turbine that uses extraction air for other purposes, if the load factor is reduced, the steam inside the steam turbine will be reduced. There is a problem that the work load may be extremely reduced, and the usable range of the steam turbine is limited. Then, the control method of a steam turbine and the steam turbine of the present invention solve the above-mentioned problems, and an object of the present invention is to provide means capable of improving the operating efficiency of the steam turbine.

[0004]

[Means for Solving the Problems]

[First characteristic configuration] A first characteristic configuration of the method for controlling a steam turbine according to the present invention for the above-described object is as described in claim 1, wherein the measurement of the amount of steam loaded on the steam turbine body is performed based on the measurement result. Detecting the load factor with respect to the rated steam amount of the turbine body, detecting the exhaust temperature from the steam turbine body, and based on the two detection results, when the load factor has reached a predetermined value, the exhaust temperature is When the temperature is equal to or lower than a predetermined temperature, the air extraction path is operated in the bleed operation mode in which bleed air is maintained from the bleed path, and when the load factor is less than the predetermined value or when the exhaust temperature exceeds the predetermined temperature, The point is that the operation is performed in the non-bleeding operation mode in which the bleeding is stopped. [Function and Effect of First Feature Configuration] According to the first feature configuration, power generation by the steam turbine is continued even in a state where the load factor is reduced, while always maintaining the maximum steam turbine shaft output in accordance with the load factor. It becomes possible. That is,
As shown in FIG. 2, when the bleed air is not reheated and returned to the low pressure stage, the shaft output characteristics of the steam turbine are greatly affected by the load factor, and the difference between the bleed operation mode and the non-bleed operation mode tends to differ. is there. That is, although the turbine shaft output with respect to the load factor shows a substantially linear correlation, the gradient of the shaft output curve b in the non-bleeding operation mode is smaller than that of the shaft output curve a in the bleeding operation mode, and crosses at a certain point. Therefore, if the vehicle is operated in the bleed operation mode at a load ratio equal to or higher than the intersection, the shaft output can be increased.By operating in the non-bleed operation mode at a load ratio equal to or lower than the intersection,
A high shaft output can be obtained while avoiding inoperability. Incidentally, the inventors have newly found that the operable range can be expanded by operating in the non-bleeding state in the bleeding type steam turbine in the above-mentioned use state. As a result, it is possible to provide a means for improving the operation efficiency of the steam turbine.

[Second characteristic configuration] According to a second characteristic configuration of the steam turbine of the present invention for the above purpose, as described in claim 2, a load steam amount is detected in an air supply passage to a steam turbine body. A load steam flow rate detecting means, an exhaust path from the steam turbine main body, an exhaust temperature detecting means for detecting an exhaust gas temperature, and a bleed path provided with a bleed path open / close valve for controlling the bleed path to open and close. The bleed passage opening / closing valve can be opened and closed based on the load steam amount detected by the steam flow rate detecting means and the exhaust gas temperature detected by the exhaust gas temperature detecting means. [Second feature configuration and operation and effect] According to the second feature configuration, similarly to the first feature configuration, a state in which the load factor is reduced while always maintaining the highest steam turbine shaft output according to the load factor. In this case, the operation of the steam turbine can be continued. That is, the bleed passage opening / closing valve is opened / closed based on the load factor calculated from the detected load steam amount from the load steam flow rate detecting means and the exhaust gas temperature detected by the exhaust gas temperature detecting means. It is possible to exert the effect. As a result, by configuring a steam turbine to which the control method of the first characteristic configuration can be applied,
It has become possible to improve the operating efficiency of the steam turbine.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an embodiment of a steam turbine employing the control method of the present invention will be described below with reference to FIG. Elements having the same or similar functions as the elements in FIG. 3 used in the description of the above-described conventional technology are denoted by the same reference numerals, and the description of the same parts as those of the elements will be partially omitted. A generator 5 is connected to an output shaft of the steam turbine main body 1, and a load steam flow rate for measuring a load steam amount, that is, a supply flow rate, is supplied to an air supply passage 2 for supplying high-pressure steam to the steam turbine main body 1. An orifice flow meter 11A as means 11 is provided. The bleed passage 3 of the steam turbine body 1 is provided with a bleed passage opening / closing valve 9 for opening and closing the bleed passage 3. Is provided with a resistance wire thermometer 12A as exhaust temperature detecting means 12 in order to detect the temperature of exhaust gas at the outlet of the steam turbine main body 1.
The bleed passage 3 is connected to a low-pressure steam reservoir 7 through a bleed passage opening / closing valve 9.
Connected to The bleed passage opening / closing valve 9 is basically set to a normally open position. A power meter 13 for measuring the shaft output of the steam turbine body 1 is connected to the output end of the generator 5. Further, there is provided an arithmetic control unit 10 for inputting the detection results of the load steam flow rate detecting unit 11, the exhaust gas temperature detecting unit 12, and the power meter 13 and performing arithmetic control.

The arithmetic control means 10 detects a load factor from the load steam quantity measured by the input load steam flow rate detecting means 11 and detects the load factor with a predetermined value (for example, 60).
%) Or the exhaust gas temperature detecting means 1
When the exhaust gas temperature detected in Step 2 exceeds the preset limit temperature, a valve closing signal is transmitted to the bleed passage opening / closing valve 9. Further, when the detected load factor has reached the predetermined value or more when the bleed passage opening / closing valve 9 is in the closed state, the bleed passage opening / closing valve is provided when the exhaust temperature is equal to or lower than the limit temperature. A valve-opening signal is transmitted to 9. The detected power from the power meter 13 is monitored at intervals of 3 minutes, and after detecting that the exhaust gas temperature has exceeded the limit temperature and transmitting a valve closing signal, the detected power has further decreased. In such a case, the valve opening signal is transmitted again to maintain the quality of the generated power.

With the above-described structure, the bleed passage opening / closing valve 9 is normally open, and the high pressure steam supplied to the high pressure steam reservoir 6 is depressurized by the steam turbine operated in the bleed operation mode. Then, it is supplied from the bleed passage 3 to the low-pressure steam reservoir 7 and is distributed from the low-pressure steam reservoir 7 to each plant in the facility. The bleed passage opening / closing valve 9 is closed by the arithmetic and control means 10, When the operation mode of the steam turbine is switched to the non-bleeding operation mode, the steam pressure in the low-pressure steam reservoir 7 decreases as the low-pressure steam is consumed, and as a result, the pressure control valve 7b is turned on by the pressure detection result of the pressure detector 7a. The valve is opened, and the reduced-pressure steam is supplied from the high-pressure steam reservoir 6 to the low-pressure steam reservoir 7 under pressure control.
Therefore, pressure fluctuations of the process steam distributed to each plant in the facility are avoided. It should be noted that the turbine inlet steam amount is smaller in the non-bleeding operation mode than in the bleeding operation mode.

Next, another embodiment of the present invention will be described. <1> In the above embodiment, the arithmetic control unit 10
Although the load factor of the steam turbine is detected by the above, the control may be performed by using a predetermined value for the load factor as a set value for the load steam amount. In this case, the arithmetic control means 10 is omitted, and the detected load steam amount from the load steam flow rate detecting means 11 and the detected exhaust gas temperature from the exhaust gas temperature detecting means 12 are logically ORed to form a bleed passage opening / closing valve. 9 to close the bleed passage opening / closing valve 9. In other words, when switching the operation mode of the steam turbine to the non-bleeding operation mode, the bleed passage 3 is switched between when the load steam amount is less than the set amount and when the exhaust gas temperature exceeds the limit temperature. All you have to do is close it. When returning from the non-bleeding operation mode to the bleeding operation mode, the bleed passage 3 is opened when the load steam amount exceeds the set amount or when the exhaust gas temperature becomes lower than the limit temperature. Is also good. <2> In the above embodiment, the arithmetic control unit 10
The condition for switching the operation mode of the steam turbine to the non-bleeding operation mode by the load factor is less than a predetermined value,
Alternatively, any one of the cases where the exhaust gas temperature exceeds the limit temperature is adopted. However, when the load factor does not reach the predetermined value and the exhaust gas temperature exceeds the limit temperature, the mode may be switched to the non-bleeding operation mode. <3> In the above embodiment, the condition for returning to the bleed operation mode after switching the operation mode of the steam turbine to the non-bleed operation mode is that the detected load factor has reached a predetermined value or more and the exhaust gas has been exhausted. Although the case where the temperature is equal to or lower than the limit temperature has been described, it may be possible to return to the bleed operation mode when the detected load factor has reached a predetermined value or higher, or when the exhaust gas temperature is equal to or lower than the limit temperature. <4> In the above embodiment, the condition for returning to the bleed operation mode after switching the operation mode of the steam turbine to the non-bleed operation mode is that the detected load factor has reached a predetermined value or more and the exhaust gas has been exhausted. Although it was assumed that the temperature was equal to or lower than the limit temperature, supply flow rate detecting means for detecting the steam flow rate at the inlet of the high-pressure steam reservoir 6 was provided at the inlet of the high-pressure steam reservoir 6, and the steam flow rate detected by the supply flow rate detecting means was adjusted to The recovery may be performed when the steam flow rate corresponding to the predetermined value of the load factor is exceeded. With this configuration, it is possible to suppress a delay in returning to the bleed operation mode. <5> In the above embodiment, after the operation mode of the steam turbine is switched to the non-bleeding operation mode, if the detected power from the power meter 13 further decreases, the valve opening signal is transmitted again. Although this example has been described, this control may be omitted. That is, when the amount of steam generated from the waste heat boiler is extremely reduced, the quality of the generated power may not be maintained even if the above control is performed to continue the power generation.

[0010] In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is a diagram comparing turbine outputs in a bleed state and a non-bleed state of a steam turbine.

FIG. 3 is an explanatory diagram showing an example of control of a steam turbine in a conventional waste treatment facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam turbine main body 2 Air supply path 3 Extraction path 4 Exhaust path 9 Extraction path opening / closing valve 11 Load steam flow detecting means 12 Exhaust temperature detecting means

Claims (2)

[Claims] 1. A steam turbine provided with an extraction passage (3) for extracting working steam from an intermediate stage of a steam turbine body (1), from a measurement result of a steam amount loaded on the steam turbine body (1). A load factor for the rated steam amount of the steam turbine body (1) is detected, an exhaust gas temperature from the steam turbine body (1) is detected, and the load factor reaches a predetermined value based on the two detection results. When the exhaust temperature is equal to or lower than a predetermined temperature, the operation is performed in the bleed operation mode for maintaining the bleed from the bleed passage (3), and when the load factor is less than the predetermined value or when the exhaust temperature is A method for controlling a steam turbine operating in a non-bleeding operation mode in which the bleeding from the bleed passage (3) is stopped when the temperature exceeds the predetermined temperature. 2. A steam turbine provided with an extraction passage (3) for extracting working steam from an intermediate stage of the steam turbine body (1), wherein an air supply passage (2) to the steam turbine body (1) is provided. A load steam flow rate detecting means (11) for detecting a load steam amount;
An exhaust path (4) from the steam turbine body (1) is provided with exhaust temperature detecting means (12) for detecting exhaust temperature, and the bleed path (3) is provided with an bleed path for controlling the opening and closing of the bleed path (3). An on-off valve (9) is provided, and the extraction passage on-off valve (9) is provided based on the load steam amount detected by the load steam flow rate detection means (11) and the exhaust gas temperature detected by the exhaust gas temperature detection means (12). Steam turbine that can be opened and closed.