JPS6038510A - Controller for reheater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a reheat system for a power generation plant, and in particular, to a reheat system for reheating high-pressure turbine exhaust gas using a part of steam supplied to a turbine. This invention relates to a control device that supplies stable stimulation to a device.

[Background of the invention]

An example of a conventional power plant reheater system is shown in FIG.

This system consists of a steam control valve 11 which adjusts the amount of steam flowing into the group 7A unit that generates steam and the turbine, and controls the turbine speed, turbine inlet steam pressure, and turbine output. High-pressure turbine 2 converts thermal energy of steam into rotational energy
, a reheater 3 that reheats the exhaust gas of the high-pressure turbine 2 using a part of the artificial steam of the high-pressure turbine, a low-pressure turbine/4 that converts the reheated steam into a thermal engine multi-rotation engine, and a low-pressure turbine/
A condenser 5 that condenses the exhaust gas, a condenser boiler/pro that boosts the pressure of the condensate accumulated in the condenser and sends it to the evaporator L, and a feed water heater that raises the temperature by exchanging heat with the condenser turbine bleed air. 7, 9, a power generator 10 that converts the rotating energy of the turbine into electrical energy
, a heating steam control valve 12 that controls the υ1 value of heating steam to the reheater, a heating steam control device 14 that controls the N degree of the heating steam control valve and adjusts the amount of heating steam, and a reheating steam temperature control device. Vessel 13 has many configurations. In this system, the opening degree of the steam control valve is adjusted based on the turbine/rotation speed and high-pressure turbine inlet pressure to control the turbine output. The steam exiting the evaporator 1 flows into the high-pressure turbine with its flow rate controlled by a steam control valve 11.

The steam that has done work in the high-pressure turbine is guided to a so-called low-temperature reheat pipe 18f, a through pipe, and a reheater. After being heated by a portion of the high-pressure turbine inlet steam in the reheater 3, the reheated steam is led to the low-pressure turbine 4 through a high-temperature reheater 19 to do work. The steam leaving the low pressure turbine is condensed in the condenser 5 and becomes condensed water. On the other hand, a part of the high-pressure cupino inlet steam passes through a heating steam pipe branched before the steam control valve ll, the flow rate is controlled by the heating steam control valve 12, and after flowing into the reheater and exchanging heat, it flows into the feed water heater 9. Heat is recovered to This amount of heating steam is constant above the specified output, but at partial output, in order to prevent excessive thermal stress from occurring in the reheater and the low-pressure coupin 4 due to the low high-pressure exhaust temperature, It is necessary to restrict the amount of heating steam in the reheater using the control valve 12. In addition, in the low-pressure Cubi/14, in order to prevent stationary parts of the turbine from being deformed due to thermal stress when the output increases from partial output, the temperature increase rate of the low-pressure turpino 4 must be kept below a specified value.

In addition, when maintaining low output operation for a long time,
Because there is little driving steam, the temperature near the final stage of the turbine increases due to the stirring action, causing the blades to overheat. In order to protect the turbine from this temperature rise, it was necessary to stop the turbine, which resulted in a reduction in plant operating efficiency.

As an example of controlling the reheater heating steam (■) to avoid this problem, the temperature at the inlet of the low-pressure turbine is detected, and the heating steam control device 14 controls the control valve 12 to adjust the amount of steam. . 8 in the figure is a bo/p. The closest example is the Westinghouse Company's Special Publication No. 55-21243. In this method, several types of temperature increase patterns are set corresponding to load change operating conditions, and the temperature at the low-pressure turbine inlet is managed according to the operating patterns. In this method, the control device is complicated9, and problems remain regarding unplanned operating conditions. Furthermore, in the method of controlling the amount of steam heated in the reheater by the temperature at the inlet of the low-pressure turbine, temperature changes in each part of the turbine are not restricted, and therefore generation of local thermal stress and deformation of parts cannot be prevented.

Due to recent social demands, large-scale power generation plants have not only base load operation but also many changes in output such as daily load following operation, and there is also a demand for continuous low output operation during single load operation within the plant due to troubles in the power transmission system. Also strong. In order to avoid unplanned plant shutdowns in such a social environment, it is necessary to further improve the reliability of plant components and the reliability of operation control.

[Purpose of the invention]

The purpose of this research is to eliminate the problem of the heating steam position of the reheater and to provide a highly reliable control device.

[Summary of the Invention] The main points of the present invention are to detect the temperature at one or more locations within the low-pressure turbine, control the absolute value of the temperature to a reference temperature corresponding to the output, and control the rate of change of the temperature to a specified value. The reheater heating steam M is controlled as follows.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the present invention. The difference from the conventional system is that a temperature detector 15 in the low-pressure terpino 4 and one output injector are installed, and the temperature detector 15, output detector 20, and computing unit 20 are connected to 114. A heating steam control device 16 is provided to control the heating steam control valve 12.

The flow rate of the steam generated in the steam generator 1 is controlled by a steam control valve 11, and the steam flows into the high-pressure terpino 2. The steam that has done work in the high-pressure turbine 2 is guided to the reheater 3 through a low-temperature reheater #18. In the reheater 3 , the reheated steam is heated by a portion of the heated steam led from the inlet of the high-pressure turbine 2 , and then passed through a high-temperature reheat pipe 19 and led to the low-pressure turbine 4 . The steam that has done work in the low-pressure turbine 4 enters the condenser 5, exchanges heat with the cooling water of the condenser 5, and condenses to become condensed water.

On the other hand, a part of the inlet steam of the high-pressure turbine 4 flows into the reheater 3 as reheater-heated steam, exchanges heat therewith, and then recovers the heat in the feed water heater 9. The condensate stored in the condenser 5 is pressurized by the condensate borer, heated by the feed water heaters 7 and 9 using the steam extracted from the turbine as the heating source, and then heated to the steam generator l.
Water is sent to

FIG. 3 shows an example of the internal logic of the reheater heating steam device 16. The output signal from the generator output detector 15 is used by the arithmetic unit 21 to generate a set temperature signal in the low pressure turbine corresponding to the output. The control valve 12 is adjusted in accordance with the magnitude of the deviation between the signal from the low pressure turbine internal temperature detector 14 and the set temperature signal. In order to limit the temperature change rate, a signal change rate limiter 26 is provided in the middle of the operation signal of the control valve 12, so that even if the generator output changes suddenly, the temperature of the reheated steam entering the low pressure turbine will not change rapidly. will not change.

In addition, in the figure, 22 is a change rate limiter, 23 is a deviation device, and 24
25 is a limiter, and 27 is an electro-pneumatic converter.

This control method enables stable control of the reheater heating steam amount under normal load operation, and also prevents excessive thermal stress from occurring within the low-pressure turbine even when the output suddenly increases or decreases. By controlling the temperature of the low pressure turbine, it is possible to prevent excessive thermal stress from occurring in the reheater 3 itself.

Furthermore, since the temperature inside the low-pressure turbine, which is the most severe in terms of thermal stress, is directly detected, reliability against problems such as thermal deformation is improved, and the control device is simple.

FIG. 4 shows another embodiment of the invention. The difference from FIG. 2 is that a plurality of temperature detectors 15 are provided in the low-pressure terpino. In this case, since the opening and opening set temperatures are set to different values, a plurality of arithmetic units It21 are required, and the opening side 1 system becomes somewhat complicated.

However, by using a method that uses the temperature at the most severe point for the low-pressure turbine among multiple detected temperatures as a signal for controlling the amount of steam heated in the reheater, it is difficult to predict the internal temperature at low loads. It is also possible to easily avoid troubles caused by thermal stress in the low pressure turbine.

FIG. 5 shows yet another embodiment of the invention. The difference from FIG. 2 is that the temperature detector 15 in the low pressure turbine is provided in the extraction pipe that extracts steam from the middle of the flow path in the low pressure turbine. In this way, the low-pressure coupin 4 itself has the same structure as the conventional one, and there is an advantage that the temperature inside the turbine can be easily detected. It is also possible to increase the reliability of detection by installing multiple detection points on several air bleed pipes.

Normally, a low-pressure turbine is composed of a plurality of single chambers, but in that case, a temperature detector is installed in each P chamber to detect the temperature IW, which is the most severe in terms of thermal stress among the plurality of detected temperatures. It is also possible to control the amount of reheater heating steam based on this.

〔Effect of the invention〕

According to the present invention, it is possible to protect a low-pressure turbine that is subject to the most severe thermal stress during plant startup, shutdown, and continuous operation at low load.

[Brief explanation of drawings]

Figure 1 is a system diagram of a conventional power plant equipped with a reheater.
FIG. 2 is a system diagram of an embodiment of the present invention, FIG. 3 is a control block diagram of the present invention showing an example of internal logic of a reheater heating steam control device, and FIGS. 4 and 5 are diagrams of the present invention. It is a system diagram of another Example. 4...Low pressure turbine/, 12...Reheater heating steam control valve, 15...Temperature detector, 16...Heating steam control device, inside

Claims (1)

[Claims] 1. A high-pressure turbine that converts the thermal energy of main steam from a steam generator of a power plant into rotational energy; a part of the inlet steam of this high-pressure turbine is used as a heating source to heat the exhaust gas of the high-pressure turbine; A reheater that reheats, a low pressure turbine that converts the thermal energy of reheated steam into rotational energy, a generator that converts the rotational energy of the high pressure turbine and the low pressure turbine into draft energy, and heating steam of the reheater. In the reheating plant, which consists of a heating steam control valve that adjusts the amount of heating steam, the temperature within the low pressure turbine is monitored and the absolute value of this temperature and the rate of change of this temperature are output to a specified value corresponding to the output of the steam generator. A reheater control device characterized in that a means for adjusting the heating steam control valve is coated with a gold film. 2. A temperature sensor in the low pressure turbine; , a reference temperature setting device that detects the output of the generator to generate a temperature reference signal, and determines whether the absolute value of the detected temperature is less than or equal to the reference temperature or the rate of change of the detected temperature is different. 1. A reheater control device characterized by being provided with a heating steam adjustment device that adjusts a heating steam control valve of the reheater so that the temperature of the heating steam is within the specified 1 section.