JPS60224905A - Steam turbine device - Google Patents

Abstract

PURPOSE:To control thermal stress to a minimum and to improve safety of a moisture separating reheater, by a method wherein, before heating steam in each reheater and steam to be heated and heat-exchanged with each other, a temperature difference therebetween is monitored, and if there is a remarkable temperature difference therebetween, the heating steam is mixed in the steam to be heated. CONSTITUTION:A steam turbine device drives a generator 17 in a way that high- pressure steam, generated by a steam generator 1, is introduced, in order, to a high pressure turbine 2, a moisture separator 3, reheaters 4 and 6, and a low-pressure turbine 8 to operate them. In which case, a short-circuit piping system, in which heated steam piping systems 5a and 7a, through which bleed air, extracted from the high- pressure turbine 2, is introduced to each of the reheaters 4 and 6, are connected in a short-circuited manner to exhaust steam piping systems 3a and 3b, is installed. Bypass valves 9 and 13 are installed in the short-circuit piping system, and the valves 9 and 13 are controlled by means of outputs from reheated steam temperature computers 12 and 16, respectively, which issue a control instruction according to a difference between the temperature of heating steam, detected by temperature detectors 10 and 14, and the temperature of exhaust steam detected by temperature detectors 11 and 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a steam turbine installation with attached moisture separator and reheater.

[Technical background of the invention and its problems]

In steam turbine power equipment that is operated with saturated steam, a moisture separation reheater is installed between the high-pressure turbine section and the low-pressure turbine section for the purpose of improving cycle efficiency. A method of reheating may be used. The reheat section of the moisture separator reheater is available in one-stage and two-stage types. In the conventional two-stage reheat system, first, the first stage reheater heats by high pressure turbine extraction air, and then the second stage reheater heats by main steam. The amount of heating steam supplied to the second stage reheater is controlled by a control valve provided at the entrance of the reheater. Several methods have been used to control the amount of steam using the opening degree of the control valve. That is,
There is a method of controlling the pressure of reheat heating steam by changing the control valve once using the reheat steam pressure as a control variable. In addition, in order to prevent high-temperature steam from flowing into the low-pressure turbine during a cold start of the turbine, there is a method of fully closing the control valve below a certain load, and a method of controlling the control valve opening so that the low-pressure turbine inlet temperature remains constant during continuous low-load operation. There are ways to control this. Although the aforementioned control valve opening control method can be said to be a simple method in terms of protecting the reheater and the low-pressure turbine, there is still room for further improvement from the viewpoint of the operation of the reheater and the low-pressure turbine. In other words, as shown in Fig. 1, the operational limiting factors of the reheater are the temperature of the heated steam (high-pressure turbine extracted steam) in the first stage reheater (7o) and the temperature of the heated steam (moisture separator outlet) as shown in Figure 1. Although Δt30 between the heated steam (main steam) temperature in the second stage reheater and the steam temperature 2o is relatively small, the difference between the heated steam (main steam) temperature 40 in the second stage reheater and the heated steam ('!s1 stage reheater outlet steam temperature 50) is relatively small. The temperature difference 6o is very large, causing deformation and elongation due to thermal stress, which may seriously impede safe driving.

[Purpose of the invention]

The purpose of the present invention is to relieve the thermal stress in each reheater caused by an excessive temperature difference between the heating fluid and the fluid to be heated, such as when the load is low, by flowing the heating steam to the unheated steam side. The purpose is to provide a reheater protection device that enables safe operation of the reheater.

[Summary of the invention]

The present invention includes a high-pressure turbine that receives steam from a steam source, a first-stage reheater that heats the exhaust gas of the high-pressure turbine by using it as a reheating fluid such as high-pressure turbine extracted steam, and a second stage reheater for further heating the steam produced by the steam generation source using a part of the steam from the steam generation source as a reheating fluid;
In a steam turbine power plant having a low-pressure turbine operated by reheated steam heated in a stage reheater, a bypass line that protects each reheater and runs from each heating steam pipe to a heated steam pipe. The temperature of the heated steam pipe is compared with that of the heated steam, and if the deviation is large, the amount of steam in the heated steam pipe is adjusted using the control valve installed in the bypass line, the temperature of the heated steam is increased, and the temperature of each reheater is increased. This is a moisture separator reheater protection device that is characterized by controlling the temperature within the operating limit values specified in .

[Embodiments of the invention]

Next, examples of the present invention will be explained. Figure 2 shows a high-pressure turbine 2 driven by high-pressure steam from a steam generator 1, a moisture separator 3 that removes moisture from the steam used and exhausted by the high-pressure turbine 2, and a moisture separator 8. Reheater 4 and reheater 6 that reheat the steam from which moisture has been removed in order to use it for driving the low pressure turbine 8, and exhaust steam that connects the reheaters 4, 6 and moisture separator 8. Piping system 8a
.

8b and a heating steam piping system 5a connected between the reheater 4 and the reheater 4 to introduce extracted steam extracted from the high pressure turbine 2.
, and a heating steam piping system connected between the reheater 6 and the reheater 6 to introduce high-pressure steam from the steam generator 1, the heating steam piping systems 5a and 7g and the exhaust steam A short-circuit piping system (two bypass valves 9, 13) that short-circuits and connects the piping systems 8a and 8b, and a temperature detection system for exhaust steam that measures the temperature of the air supplied to the exhaust steam piping system 8B. 11.15, a heating steam temperature detector 10.14 installed in the heating steam piping system 5a, 7a and measuring the heating steam temperature, and the heating steam temperature and temperature detection measured by the temperature detector 10.14. This figure shows a steam turbine device comprising a reheat steam temperature calculator 12.16 that calculates the temperature difference between the exhaust steam temperatures measured by the steam turbine 11.15 and outputs control commands to the bypass valves 9 and 16, respectively. ing.

In FIG. 2, 1 is a steam generator, and the steam generated by the steam generator 1 is supplied to a high-pressure turbine 2, where it does work, and then becomes the exhaust gas of the high-pressure turbine 2 to be sent to a moisture separator 8. moisture is removed. Thereafter, it is heated by the high pressure turbine extracted steam 5 in the first stage reheater 4, and then heated in the second stage reheater 6.
The low-pressure turbine 8 is heated again by the main steam 7. On the other hand, in the first stage reheater 4, a temperature detector 10 is installed in the high pressure turbine oil steam line for reheating the first stage, and a temperature detector 10 is installed in the high pressure turbine exhaust steam line which is the steam to be heated in the first stage. Each temperature is detected by the temperature detector 11
If the temperature difference detected by the stage reheat steam temperature calculator 12 is equal to or higher than a specified value, the opening degree of the extraction steam bypass valve 9 is controlled,
A part of the high-pressure turbine extracted steam is mixed into the reheated steam side. Similarly, in the second stage, a main steam temperature detector 14 and a second stage reheater outlet temperature detector 15 are provided in the heating steam line and the heated steam line, and the main steam temperature is determined by the second stage reheating steam temperature calculator 16. By controlling the opening degree of the bypass valve 13 and mixing heated steam into the reheated steam side, the inlet steam temperature of the reheater is changed.

It should be noted that the present invention is not limited to the embodiments, and an example in which a load is used as a control element of a bypass valve is a modification thereof, which can be implemented with various modifications without changing the gist of the invention.

〔Effect of the invention〕

The present invention monitors the temperature difference between the heating steam and the steam to be heated in each reheater before exchanging heat between the two, and if there is a significant temperature difference between the two, the heating steam is mixed with the steam to be heated, and the steam is transferred to the reheater. The temperature limit value of the reheater is satisfied before steam enters, and the thermal stress due to the temperature difference between the heating fluid and the heated fluid is suppressed to a minimum, and the safety of the moisture separation reheater is maintained.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the temperature of a conventional moisture separator reheater, and Figure 2 is a configuration diagram of a moisture separator reheater showing an example of the present invention. 1... Steam generator 2... High pressure turbine 3... Moisture separator 4... First stage reheater 5... High pressure turbine extracted steam 6... Second stage reheater 7 ... Main steam 8 ... Low pressure turbine 9 ... Extraction steam bypass valve 10 ... Temperature detector 11 ... Temperature detector 12 ... First stage reheat steam temperature calculator 13 ... Main steam bypass valve 14...Main steam temperature detector 15...Second stage reheater outlet temperature detector 16...Second
Stage reheating steam temperature calculator 17... Generator 20... Moisture separator outlet steam temperature 30... First stage heated device steam temperature difference 40... Main steam temperature 50... 1st stage internal heater outlet steam temperature 60...Steam temperature difference 70...High pressure turbine extracted steam 80...High pressure turbine exhaust temperature 90...2nd stage reheater outlet steam temperature Agent Patent attorney Kensuke Noriyuki (and 1 other person) Figure 1 ψ City Figure 2

Claims (1)

[Claims] A high-pressure turbine driven by high-pressure steam from a steam generator, a moisture separator that removes moisture from the steam used and exhausted by this high-pressure turbine, and the steam from which moisture has been removed by this moisture separator. an exhaust steam piping system connecting the reheater and the moisture separator, and extracted steam extracted from the high-pressure turbine or the steam generator. In a steam turbine device comprising a heating steam piping system connected between the reheater and the reheater to introduce high pressure steam from a steam turbine, the heating steam piping system and the exhaust steam piping system are connected by short-circuiting. a bypass valve installed in the short-circuit piping system, an exhaust steam temperature detector installed in the exhaust steam piping system to measure the exhaust steam temperature, and a heating steam temperature detector installed in the heating steam piping system to measure the heating steam temperature. reheating steam that calculates a temperature difference between the heating steam temperature measured by the heating steam temperature detector and the exhaust steam temperature measured by the exhaust steam temperature detector and outputting a control command to the bypass valve; A steam turbine device comprising a temperature calculator.