JPS5888505A - Temperature dropping controller for turbine bypass system - 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 The present invention relates to a detemperature control device for a turbine bypass system, and in particular, a device is installed in a turbine bypass path branched from a main steam system to a condenser to control the amount of water injected into a desuperheater. The present invention relates to a cooling control device for a turbine bypass system.

In combined cycle power plants and general thermal power plants, etc., temperature control is usually performed by adjusting the amount of water injected from a double water device into a nine-temperature attemperator installed in the turbine bypass system using a water injection control valve. . In such a case, especially in a combined power generation plant or the like having high efficiency and high load responsiveness, it is necessary to quickly and accurately control the temperature in the attemperator. However, the response speed of conventional desuperheater temperature control is not always sufficient, and the piping length to the condenser must be longer than necessary, making it difficult to use the limited plant area effectively. There was a drawback that it could not be used effectively.

FIG. 1 shows an overview of a typical conventional turbine bypass system. The main steam flow from the boiler 1 is sent to the steam turbine ST (not shown) through the main steam pipe 2, while being branched from the main steam pipe 2 and returned via the attemperator 4 under the flow rate adjustment by the turbine bypass valve 3. It is sent to water container 5. A portion of the water supplied from the condenser 5 and circulated through a drum (not shown) by a condensate pump 6 is injected into the attemperator 4 by a water injection control valve 7.

Here, when five people control the temperature using desuperheater 4.

The steam temperature in the pipe 10 that exits the desuperheater 4 and reaches the condenser 5 is detected, and a converted signal is sent to the control device 9 by the temperature transmitter 8. The control device 9 processes this signal and controls the water injection control valve 7.
An opening command signal is sent to the condenser 5, and the amount of water injected into the desuperheater 4 is adjusted according to the steam temperature in the piping 10 to obtain the optimum temperature for the condenser 5.

In this way, in the conventional system shown in Figure 1, the temperature of the desuperheater 4 is directly controlled based on the temperature of the steam that exits the desuperheater 4, but in such feedback control, there are As a characteristic, the response is not quick. In addition, due to this slow response, there is a risk that high-temperature steam may flow into the condenser 5 without sufficient temperature reduction effect, so the piping 10 must have a large diameter and a long length with enough room. Problems arise with the installation space. Furthermore, if the flow rate of the gate water is set higher than necessary in consideration of safety in advance, the thermal effect will be reduced and energy loss will result.The purpose of the present invention is to eliminate these drawbacks of the conventional technology and to enable quick and accurate temperature control. An object of the present invention is to provide a temperature reduction control device for a turbine bypass system.

The present invention provides a temperature reduction control device for a turbine bypass system, which is configured to adjust the amount of water injected for temperature control into an attemperator provided in a turbine bypass path branched from a main steam system to a condenser. In this step, the amount of water injected for temperature control into the attemperator is adjusted by a predictive control signal obtained based on detection and processing of information including factors of temperature, pressure, and enthalpy of main steam on the upstream side of the attemperator. It is characterized by being made to do.

An embodiment of the present invention will be described in detail below based on the drawings.

FIG. 2 shows an embodiment in which the present invention is applied to a combined cycle power plant. The main steam flow from the boiler 1 heated by the exhaust gas of a gas turbine (not shown) is sent by a main steam pipe 2 to a steam turbine kT (not shown). Also, a part of the main steam is diverted at startup and during steam turbine load fluctuations and sent to the turbine bypass system so as to keep the main steam pressure and the level in the drum within acceptable values.

That is, it is recovered to the condenser 5 via the turbine bypass valve 3 and the attemperator 4. The amount of main steam flowing into the attemperator 4 is adjusted by the opening degree of the turbine bypass valve 3. The temperature of the desuperheater 4 is controlled by a water injector using a water injection control valve 7 that bypasses the thread from the condenser 5 to the deaerator (not shown) via the condensing membrane 6. The steam temperature is lowered to a necessary and sufficient level so that it can be recovered in the condenser 5. Each part of the plant system described above is basically the same as that shown in FIG. 1, and corresponding parts are designated by the same reference numerals.

Hereinafter, the configuration of the present invention for controlling the temperature in the desuperheater 4 will be explained. In the conventional method, the opening degree of the water injection control valve 7, which is adjusted for temperature control, is adjusted by detecting the steam temperature from the attemperator 4, but in the embodiment of the present invention, There is an advance control method in which the steam temperature at the exit side of the desuperheater is predicted based on information on thermal factors contained in the main steam on the upstream side before reaching the temperature, and the water injection control valve 7 is adjusted based on this information. It is being

That is, signals obtained by detecting and converting the temperature and pressure of main steam in the main steam pipe 2 are sent to the control device 9 by the temperature transmitter 11 and the pressure transmitter 12, and the control device 9 uses these signals to A correction signal is sent to the turbine bypass valve 3 and the water injection control valve 7 to predict the steam temperature on the outlet side of the warmer 4 and control it to an optimum value.

The outline of the signal processing performed by the control device 9 will be explained in the third section below.
This will be explained using the block diagram shown in the figure.

First, the signal TM from the temperature transmitter 11 is converted into a temperature correction coefficient in the function (F, ) calculator 13 as follows: (A is a constant) On the other hand, the signal PM from the pressure transmitter 12 is converted into a temperature correction coefficient by the function (F, ). ) is converted into a pressure correction coefficient in the computing unit 14: M K3-□ (where B is a constant) Each of the above coefficients is multiplied by 2 and 3 in the multiplier (X,) 15 to calculate the turbine bypass. Give 4 to the flow rate correction factor: to 4 to 2 to 2XK.

On the other hand, the signals from the temperature transmitter 11 and pressure transmitter 12 are also taken into the function (F3) calculator 16, where the enthalpy of the superheated main steam is calculated and the enthalpy correction coefficient is obtained: 5=F3 (Pw, TM) This enthalpy correction coefficient is multiplied by the flow rate correction coefficient by 4 in a multiplier (X2) 17 to calculate a turbine bypass steam correction coefficient of 6: to, = to, XK.

Furthermore, control No. 4 X from the turbine bypass controller 18,
and the turbine bypass steam correction coefficient 4, a function (F
4) Perform calculations in the calculator 19 to calculate the control signal Y for turbine bypass correction. : Yll=F'4 (X5, x, > this control signal Y
The function (F,) calculation unit 20 calculates the opening degree correction of the water injection control valve based on Control valve 7 is controlled.

As described above, according to the embodiment of the present invention, the appropriate amount of water to be injected into the attemperator 4 is calculated by comprehensive correction based on various conditions such as heat, pressure, and enthalpy in the main steam. Therefore, temperature control of the condenser 5 can be optimized and plant thermal efficiency can be improved. In particular, this temperature control is performed as advance predictive control based on the state of the main steam on the upstream side, and its responsiveness is extremely high, making it possible to accurately follow the temperature reduction control at the time of plant startup or sudden load changes. I can do it. As a result of the rapid and accurate temperature reduction control, the length and diameter of the piping 1o from the vessel 4 to the condenser 5, as well as the wall thickness, are increased more than necessary for safety reasons. There is no need to make it large, and great effects can be achieved in reducing the number of piping equipment and making effective use of the installation space.

In the above embodiment, an example in which the present invention is applied to a combined cycle power plant has been described, but the present invention can also be widely applied to temperature reduction control in a general turbine bypass system.

As described above, the responsiveness of the temperature reduction control device for a turbine bypass system of the present invention can be made appropriate and quick.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a turbine bypass system to which a conventional device is applied, Fig. 2 is a system diagram of a turbine bypass system according to an embodiment of the present invention, and Fig. 3 is a block diagram of main parts of the embodiment shown in Fig. 2. .

Claims (1)

[Claims] 1. Temperature control device for a turbine bypass system, which adjusts the amount of water injected for temperature control into a desuperheater installed in a turbine bypass path branched from the main steam and gas system to the condenser. 5. Water injection amount for temperature control to the attemperator based on a predictive control signal obtained based on detection and processing of information including temperature, pressure, and enthalpy factors of main steam on the upstream side of the attemperator. The temperature reduction control device for the turbine bypass system, characterized in that the device is configured to adjust the temperature reduction control device for the turbine bypass system.