JPS6022006A - Control device for reheater - Google Patents

Abstract

PURPOSE:To make the metal temperature variation rate of reheater, etc. constant, throughout all actuating modes, by controlling a heating steam adjusting valve in response to an intial metal temperature and the outlet side pressure of valve, etc., in a reheater having the heating steam adjusting valve provided in a heating steam conduit thereof. CONSTITUTION:To introduce a steam brached from a main steam heater tube 2 into a reheater 7 via a heating steam adjusting valve 13 and a heating steam bypass valve 14, respective valves 13, 14 are controlled by a heating steam control device 12. The control device 12 is adapted to take up a signal from the metal temperature sensor 19 of reheater into a predetermined target pressure generator 20 and compare the output with a signal from a pressure sensor 21 provided at the downstream of heating steam adjusting valve 13 whereby controlling the heating steam adjusting valve 13 according to a resultant difference. The signal from the pressure sensor 21 is compared with a signal indicative of predetermined value of pressure setting device 23 by means of a comparator 24. The heating steam bypass valve 14 is controlled to open upon the pressure being sensed to exceed a preset value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a reheater in a turbine engine plant.

[Background of the invention]

FIG. 1 is a turbine system diagram of a nuclear power plant as an example of a conventional reheat steam turbine prime mover plant. In this case, although the illustrated high-pressure steam source 1 is a nuclear reactor, the other configurations are the same even if the entire steam generator is used.

Most of the steam coming out from the high pressure steam source 1 comes from the main steam header pipe 2.
The amount of steam supplied is regulated by a steam control valve 3.

This steam regulating valve 3 is controlled by a steam regulating valve control device 11.

The steam flowing into the high-pressure turbine 4 is thermally expanded and converted into rotational energy, and then the high-pressure turbine exhaust is 1
Since the steam contains 0% to 12% moisture, it is led to the moisture tolerance 6 via the upstream section 5a of the cross-around pipe. Here, most of the moisture in the steam is separated and becomes low to 2-inch wet steam, which is reheated using a part of the steam as a heating source, which is branched through the ladder pipe 2 to the main steam in the front b pi. After being reheated to a steam temperature of approximately 70C in the reheater 7, it flows into the low pressure turbine 8 via the cross-around pipe 5, where it is thermally expanded and converted into rotational energy. Vessel 9. It consists of a system in which the feed water is supplied to the reactor or steam generator 1 again via the feed water heater 10=i.

The steam turbine, which is composed of a high-pressure turbine 4 and a low-pressure turbine 8, detects the turbine rotation speed and turbine inlet steam pressure, and generates steam to flow into the high-pressure turbine 4 in an amount commensurate with a required output control signal. Adjustment valve control device 11
The steam control valve 3 is controlled by the signal.

In addition, the amount of heating steam supplied to the reheater 7 is controlled by a heating steam control valve 13 and a heating steam control valve 14 provided on the inlet side of the reheater 7 according to a signal from the heating steam control device 12. It is controlled by opening and closing.

FIG. 2 shows a system diagram around a reheater in an example of a conventional atomic coupler. The heating steam control device 12 includes a reheater outlet steam specific force detector 15', and receives a signal converted into a target value equivalent to the heating steam pressure by the calculator 16, and a pressure sensor provided downstream of the heating steam control valve 13. The detector 17 signal is compared with the comparator 18, and the difference is used to determine the heating steam 1If.
The flJ control valve 13 operates. On the other hand, the heating steam bypass valve 14 has a function of operating when the differential pressure across the control valve 13 falls below a certain value. Figures 3(a) and 3(b) show the initial characteristics when the reheater 7 is operated based on the control method described above. Since the heating steam is extracted from the King's Steam Hesogu Rai 2, the heating steam pressure characteristics are the third.
As shown in "
00% turbine load) and the reheat effect is kept constant to falsify it. On the other hand, as shown in Figure 3(b), the temperature of the heated steam on the reheater side is as follows: If the heating steam pressure is constant with respect to the turbine load, the outlet sensitivity will be constant, but the inlet temperature will change to a low load. As the temperature increases, the temperature difference between the inlet and outlet (ΔTel) increases. Therefore, when the load is slightly lower (50%) from the continuous shaft rotation, the heating steam pressure is reduced by ΔP in Figure 3 (a). By reducing the pressure, the heated steam outlet temperature also decreases as shown in Fig. 6g3 (b), making it possible to reduce the temperature difference (ΔT2<ΔT+), and reducing thermal deformation and thermal stress. obtain. For this reason, the amount of heated steam is controlled by the control device 12, by the control valve 13 in the low load range, and by the bypass valve 14 in the high load range.

Heating steam control method according to this conventional example! tilJ
(In the tL'J equipment, no separate consideration was given to the effects of the plant shutdown period on the thermal stress and thermal deformation that occur during startup, that is, the initial metal temperature of the reheater or low-pressure turbine. The disadvantage was that the rate of change in temperature of the reheater metal temperature and the low-pressure turbine metal temperature, which are related to thermal stress or thermal deformation, is not uniform in each startup mode.

As a result, damage to the reheater occurs due to deformation, or the lifespan is prematurely consumed due to thermal stress, resulting in loss of strength and durability.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned 4'I't1, and its purpose is to make the metal temperature heating rate of the reheater and low pressure turbine constant in all startup modes. The present invention provides a reheater control device that can prevent excessive thermal stress from occurring due to changes in quality, thereby safely increasing the reheater outlet steam temperature, and contributing to improved efficiency, especially at partial loads. That is.

[Summary of the invention]

In order to achieve the above object, the reheater control device of the present invention'
In a reheater split sea bream 1 equipment, a heating steam control valve is installed in the reheater heating steam line of a reheating steam power plant, and a heating steam amount control device is installed to control the opening and closing of this heating steam control valve. In the above heat steam amount control device, (a) a pressure set value calculator whose input signals are the steam control valve control device q output signal and the initial metal temperature detection signal, and (b) the above pressure A ratio collector is provided for the output signal of the set value calculator and the pressure detection signal on the outlet side of the heating steam control valve, and the heating steam control valve is configured to automatically open/close +BIJ +H based on the output signal of the ratio collector. Waiting is what you did.

[Embodiments of the invention]

FIG. 4 is a system diagram in one embodiment of the present invention. This real UI! One example is the conventional reheater 1tilJ shown in Figure 2.
This is an example of improving the f4 device by applying the present invention.
Components labeled with the same drawing reference numbers as in the figures are the same or similar components as in the conventional device.

The amount of steam 01 flowing into the high pressure turbine 4 is determined by the steam control valve 3.
It is automatically controlled based on the output signal of the steam control valve control device 11 based on the turbine rotational speed, turbine inlet pressure, and turbine load request signal.

The steam branched into the main steam through the ladder pipe 2 is supplied as a heating steam source to the reheater 7, and heated steam is passed through the heating steam bypass 13 and heating steam bypass valve 14 installed on the inlet side of the reheater 7. The amount will be controlled. The output signal of the heating steam amount control device 12 is used as the side vortex signal. Reheater 7
The heated steam supplied to the feed water heater 10 undergoes heat exchange and is recovered by the feed water heater 10.

The heating steam control device 12 is configured as follows to avoid a delay of 1ltlJ.

Steam turbine steam control valve + tjil ml device full
By determining the starting mode 7 based on the output signal of Make sure that the value does not exceed a certain value. That is, the signal of the reheater metal temperature detector 19 attached to the reheater 7 is taken into the target pressure set value generator 2o, and the output signal and the pressure detection provided on the downstream side of the heating steam control valve 13 are input to the target pressure set value generator 2o. The signals from the device 21 are compared by the comparator a22, and the difference between them is used as an output signal to control the heating steam by opening and closing the heating steam control valve. A comparator 24 compares the signal from the pressure detector 21 and the pressure setting device 23, and if the signal becomes higher than the set value, the heating steam bypass 9P14 is opened to open the heating steam bypass 9P14. The reheating effect can be enhanced by controlling the pressure loss to be as small as possible.

Further, the internal logic of the target pressure set value generator 20 is composed of a function calculator 25 and a multiplier 26, as shown in FIG.
The ratio of the signal from the reheater metal temperature detector 19 and the target pressure setting value to the steam control valve control signal is outputted to the function calculator 25 as an output signal, and the multiplier 26 outputs the ratio of the target pressure setting value to the steam control valve control signal.
By multiplying the output signal of No. 5 by the steam control valve control signal, it is possible to obtain the target pressure setting value as the output signal.

Next, Fig. 6 (a), , (b), (C), (d),
(e) The heating steam pressure If, reheater outlet steam temperature characteristics, and reheater metal 6 degree characteristics in different startup modes will be explained based on the above embodiment.

Normally, the rate of increase in turbine load in a nuclear power plant is dominated by reactor characteristics, such as shutdown periods, start-up modes, etc.
In other words, since the so-called continuous operation mode of thermal power generation is not adopted, in which the turbine load increase rate is varied and operated, the turbine load increase rate is assumed to be constant in all startup modes after the plant is shut down. I can say it.

Therefore, when starting from a state where the reheater metal temperature is maintained at a relatively high temperature, the hood change is small.
By setting the heating steam pressure to full pressure at relatively low loads, it is expected that efficiency will be improved by reheating.

For example, if A II , n B +'' is selected by the function generator from the initial metal temperature as shown in the turbine load and target heating steam pressure characteristics shown in FIG.
Assuming that the steam bin is started in the turbine bin load increase pattern shown in Figure 6(b), the startup time characteristics of the heating steam pressure will be as shown in Figure 6(C), and the steam temperature at the outlet of the reheater. is the E characteristic shown in Figure 6(d), but the reheater metal temperature is accompanied by a slight time delay due to the heat valley of the metal and the difference in the initial metal temperature, so the heating steam pressure The rate of temperature change during the rising process can be achieved to be the same rate of change once in the starting modes ``'A'' and ``B.'' It can be constant in all drive modes.

As another embodiment, when the low-pressure turbine is more of a bottleneck than the reheater in terms of structural strength, the object of the present invention can be achieved by placing the temperature sensor 19' in the low-pressure turbine metal. In addition, as an alternative to the initial metal temperature detector 19.19', the high pressure turbine metal temperature sensor 19.
It is also possible to set from signals such as j, etc., but if the former metal temperature signal of the high pressure turbine is used, appropriate control is difficult because the temperature characteristics differ depending on the difference in heat capacity.

In addition, if the latter stop time signal is used, the metal temperature characteristics will differ for the same stop time depending on the stop mode, for example, whether the vacuum is broken after stopping, etc., so it is difficult to set the appropriate pressure. There is a problem that leg number 1d is difficult to use. In the embodiment of the previous I-P, the output signal of the control device 11 was input to the pressure set value calculator 20, but the turbine load output signal was input to the pressure set value calculator 20. It can also be configured to force the user to do so.

〔Effect of the invention〕

As described in detail above, the present invention provides a heating steam control valve in the steam line for heating the reheater of a reheating type steam power plant, and controls the opening and closing of the heating steam control valve to control the amount of heating steam 1lI.
IJ control device f: In the installed reheater control device,
In the heating steam amount control device of the pipe, (a) a pressure set value calculator which uses the output signal of the steam control valve control device, the first metal tear detection signal and the warehouse input signal, and (b) the above pressure set value calculation By providing a comparator between the output signal of the steam generator and the pressure detection signal on the outlet side of the heating steam control valve, and configuring the heating steam control Jf' to be automatically opened and closed by the output d of the comparator, all Reheat S-? in startup mode?
By keeping the metal temperature change rate of the low-pressure turbine constant, it is possible to prevent the generation of excessive thermal stress due to temperature changes, and the steam temperature at the reheater outlet can be safely raised, improving the thermal efficiency of steam power plants. This greatly contributes to improved durability and reliability.

[Brief explanation of drawings]

Figure 1 is a system diagram of an atomic turbine rotor, Figure 2 is a system diagram of a reheater control system in the prior art, and Figure 3 (a
), (b) are circuits showing its performance characteristics. FIG. 4 is a system diagram showing an example of a steam motor plant equipped with the reheater control device of the present invention, and FIG. 5 is a system diagram showing an example of the configuration of a pressure set value calculator. Figure 6(a), (
b), (c)', (d), and (e) are charts for explaining the load characteristics in the above embodiment, respectively. 1... Nuclear reactor or steam generator, 2... Ladder pipe to main steam, 3... Steam control valve, 4... High pressure turbine,
5...Cross-around pipe, 6...Moisture divider, 7
..., Fi+heater, 8...low pressure turbine, 9...
Temporary water container, 10... Feed water heater, 11... Natural air intake valve control device, 12... Heating steam ttjlJ control device, 1
3... Heating steam control valve, 14... Heating steam bypass valve, 15... Pressure detector, 16... Arithmetic unit, 17...
...Pressure, director, 18...Comparator, 20...Pressure setting value calculator, 21...Pressure, Sumida device, 22...Comparator, 23...Pressure setting device, 24. ... Comparator, 25
...Function operator, 26...Multiplier. Agent Patent Attorney Masami Akimoto 2 Figure 17

Claims (1)

[Claims] 1. A heating steam 1fflJ# valve is installed in the steam pipe for heating the reheater of a reheating steam power plant, and a heating steam amount control device is installed to control the opening and closing of this heating steam control valve. In the heater control device, in the heating steam amount control device, (→
a pressure set value calculator whose inputs are the output signal of the steam control valve control device and the initial metal concealment detection signal, and (
b) A comparator is installed between the output signal of the calculator and the pressure detection signal on the output side of the hot steam control valve at the pressure setting +, and the output No. 18 of the comparator sets the heating steam '1IiIIIl wholesale valve fully automatically. A reheater control device characterized in that the reheater control device is configured to have 7ftlJ legs that can be opened and closed. 2. Connect a bypass valve in parallel with the heating steam control valve described in 4J, and control the bypass valve by a comparison calculation signal between the heating steam control valve outlet side pressure detection signal and the pressure equipment signal described in Ail. 1. The reheater control device according to claim 1, wherein: 3. The pressure setting value calculator of the previous d is composed of (C) a function calculator which takes as an input signal the initial metal temperature detection signal described in rJjJ, (d) the output signal of the above at function calculator, and the above. 3. The reheater control device according to claim 2, further comprising a multiplier for multiplying the output signal of the energy reduction valve control device. 4. The reheater control device according to claim 3, wherein the initial metal d degree detector of the front dpi is installed in the reheater. 5. The reheater 1h1 control device according to item 3 of the clock 64 request, characterized in that the α-phase metal temperature detector in the previous step A is installed in a low-pressure turbine.