JPH11257018A - Steam by-pass system for steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a turbine trip from affecting other facilities, with reducing loads to the operator by minimizing the pressure fluctuation in the high-pressure steam accumulator by the turbine by-pass valve operation at the time of the turbine trip. SOLUTION: This system is structured with a turbine by-pass valve 11, a sensor 9, a flow rate to valve lift conversion means 4 and by-pass valve control means 5, 3. The turbine by-pass valve 11 controls the pressure in a high-pressure steam accumulator 7 by letting out the steam from the high-pressure steam accumulator. The sensor 9 measures the flow rate of the steam which flows in from the high-pressure steam accumulator to a steam turbine 10. The flow rate to valve lift conversion means 4 calculates the increased amount of the valve lift of the turbine by-pass valve to let out the steam which corresponds to the flow rate of the steam measured with the sensor 9 via the by-pass valve 11. The by-pass valve control means 5 and 3 control the turbine by-pass valve 11 by adding the increased amount of the valve lift that has been calculated by the flow rate to valve lift conversion means 4 at the time when the steam turbine 10 trips.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine steam bypass device for smoothly discharging steam used on the turbine side to a high-pressure steam condenser when an emergency stop occurs due to a failure (trip) of the steam turbine.

[0002]

2. Description of the Related Art Steam turbines are used for self-power generation in various factories and plants such as refuse treatment plants and sewage treatment plants, and for various other purposes. In the case of performing the above-mentioned self-power generation, it is often configured as not only power generation but also comprehensive equipment using steam including a boiler, a steam turbine, other hot water supply facilities, a hot water pool, and the like.

Conventionally, in such equipment, when the turbine trips for some reason during the operation of the steam turbine, the turbine bypass valve is fully opened at a stretch by manual or computer output so that the steam used on the turbine side is released. I have. This avoids damage to the steam turbine, accidents due to high-pressure steam, and the like.

[0004]

However, if the turbine bypass valve is fully opened at once by manual or computer output when a turbine trip occurs, the entire pressure of the high-pressure steam reservoir will drop. For this reason, even steam used in other facilities cannot be used. For example, for a few hours until the pressure rises again, hot water supply equipment cannot be used, white smoke prevention and combustion air preheating cannot be performed, so some equipment cannot be used, and plant operation itself Can cause problems.

[0005] Further, in order to avoid such a situation, if the operator operates the bypass valve manually and finely to release high-pressure steam, the burden on the operator increases.

The present invention has been made in consideration of such circumstances, and when a turbine trips, the pressure fluctuation of the high-pressure steam reservoir due to the operation of the turbine bypass valve is minimized, and the influence on other equipment is reduced. It is an object of the present invention to provide a steam turbine steam bypass device capable of preventing and reducing a burden on an operator.

[0007]

In order to solve the above-mentioned problems, the invention corresponding to claim 1 first adjusts the pressure of the high-pressure steam sump by causing the steam of the high-pressure steam sump to flow out by a turbine bypass valve. It is supposed to.

On the other hand, the steam from the high-pressure steam sump flows into a steam turbine, and the steam flow rate is measured by a sensor. An increase in the opening degree of the turbine bypass valve that allows steam corresponding to the steam flow rate measured by the sensor to flow out through the turbine bypass valve is calculated by the flow valve opening degree conversion means.

When the steam turbine trips, the increase in the valve opening calculated by the flow valve opening conversion means is added to minimize the pressure fluctuation of the high-pressure steam reservoir due to the operation of the turbine bypass valve. The bypass valve control means controls the turbine bypass valve so that the turbine bypass valve can be operated. This prevents the effect of the steam from the high-pressure steam reservoir on other equipment that uses steam, and also reduces the burden on the operator.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram illustrating an example of a steam system to which a steam turbine steam bypass device according to an embodiment of the present invention is applied.

In this steam system, steam from a boiler drum 6 is stored in a high-pressure steam reservoir 7 in a high-pressure state, and the high-pressure steam is supplied from the high-pressure steam reservoir 7 to a steam turbine 10 and other steam-using equipment (not shown). Have been.
The steam from the high-pressure steam reservoir 7 enters the high-pressure steam condenser 12 via the turbine bypass valve 11, and the pressure of the high-pressure steam reservoir 7 can be adjusted by the degree of opening of the bypass valve. Further, although not particularly shown, power is generated by the steam turbine 10.

Further, the steam turbine steam bypass device includes:
A pressure sensor 8 for measuring the pressure inside the high-pressure steam reservoir, a steam flow sensor 9 for measuring the steam flow rate at the inlet of the steam turbine, and a turbine bypass valve 11 for adjusting the pressure inside the high-pressure steam reservoir.
And the computer 1 that controls the bypass valve 11.

The computer 1 includes a PID module 2 for adjusting the valve opening of the turbine bypass valve 11 based on a signal from the pressure sensor 8 to perform constant pressure control of the high-pressure steam sump 7.
Flow valve opening degree conversion module 4 and select module 5
And an addition module 3 and a change rate restriction module 13.

In the flow valve opening degree conversion module 4, a value of an addition amount (correction adjustment amount) of the bypass valve opening degree corresponding to the steam flow rate to the steam turbine 10 is set as broken line data. The flow valve opening degree conversion module 4 always calculates the above-mentioned correction adjustment amount in accordance with the signal from the steam flow sensor 9 based on the broken line data, and inputs it to the select module 5. For this reason, the select module 5 is supplied to the steam turbine 10 substantially immediately before the turbine trip.
That is, the information corresponding to the correction adjustment of the valve opening for outputting the same steam amount to the high-pressure steam condenser 12 as the steam amount flowing into the high-pressure steam condenser 12 is output.

The select module 5 includes the steam turbine 1
When a trip signal from 0 is received, the correction amount of the bypass valve opening is switched from 0% to the output of the flow valve opening conversion module 4.

The addition module 3 includes a PID module 2
And the output from the select module 5 are added. The rate-of-change limiting module 13
The valve control output from the addition module 3 is sent to the turbine bypass valve 11, and when the steam turbine 10 outputs a trip signal, the valve control output changes rapidly due to the correction adjustment from the select module 5. The output change rate is limited so that it does not occur. Specifically, when a trip signal is received, one cycle (500 m
The output change is limited so that the output target value from the adder module 3 is reached in a plurality of cycles instead of about (sec).

Next, the operation of the steam turbine steam bypass device according to the embodiment of the present invention configured as described above will be described. First, when the steam turbine 10 is operating normally, the turbine bypass valve 1 is controlled by the PID module 2 so that the internal pressure of the high-pressure steam sump 7 becomes constant.
1 is controlled.

Here, when a turbine trip occurs and the steam turbine 10 is stopped urgently, a turbine trip signal to that effect is transmitted to the select module 5 and the change rate limiting module 13.

On the other hand, in the flow valve opening degree conversion module 4,
Corresponding to the measured flow rate value of the steam flow sensor 9, the valve opening to be added when the turbine trips at that time is always calculated from the broken line data. The polygonal line data determined by the overall system configuration and the valve characteristics is information collected and measured when the steam system is started up and adjusted, and the flow rate valve opening degree conversion module is converted from the measurement results in the form of a graph or a table. 4 in advance.

The select module 5 receiving the turbine trip signal switches the valve opening addition value to the output of the PID module from 0% to the flow valve opening conversion module output which is always calculated. As a result, a value obtained by adding the added amount (correction adjustment amount) is input to the change rate limiting module 13.

Since the change rate limiting module 13 receives the turbine trip signal, it is known that the valve opening sharply changes depending on the amount of the correction adjustment. Therefore, when the trip signal is received, the control signal is transmitted to the turbine bypass valve 1 so as to reach a new valve opening over a plurality of cycles.
1 is output.

As a result, the output of the flow rate valve opening conversion module is added to the opening of the turbine bypass valve 11, and the turbine bypass valve 11
The opening increases as the amount of steam flowing to zero increases.

More specifically, when the turbine bypass valve 11 is opened, the steam flowing toward the steam turbine 10 is reduced in accordance with the degree of opening while being restricted by the change rate limiting module 13. . As the steam flowing to the steam turbine 10 decreases, the measured flow value of the steam flow sensor 9 decreases, and the valve opening obtained and added by the broken line of the flow valve opening conversion module 4 also decreases. Accordingly, the added amount of the opening degree of the turbine bypass valve 10 gradually shifts from the output of the change rate limiting module to the PID control by the PID module 2.

Then, finally, the output of the flow rate valve opening conversion module becomes 0, and the internal pressure of the high-pressure steam reservoir 7 becomes constant by the PID. At the same time, the control is such that all the steam flows to the high-pressure steam condenser 12 and other steam use equipment (not shown).

As a result, the supply of steam to other steam-using equipment (not shown) is kept constant. In addition, an increase in pressure inside the turbine and damage to the turbine state due to a turbine trip are prevented, and occurrence of an accident is prevented.

As described above, the steam turbine steam bypass device according to the embodiment of the present invention includes the steam turbine 10
The flow rate is measured by the steam flow sensor 9, and the flow valve opening conversion module 4 determines the increase in the valve opening for allowing the steam corresponding to the measured steam flow to flow through the turbine bypass valve 11. When the steam turbine trips, the turbine bypass valve 11 is controlled by adding the increment of the valve opening. Therefore, even if the steam turbine is stopped due to the turbine trip during the operation of the steam turbine, the steam turbine is automatically stopped. The steam used in the above can be smoothly released, and the pressure fluctuation of the high-pressure steam 7 can be minimized. Thereby, it is possible to prevent the influence on other steam facilities and reduce the burden on the operator.

The present invention is not limited to the above embodiments, but can be variously modified without departing from the gist thereof. The method described in the embodiment may be a program (software means) that can be executed by a computer (computer), for example, a magnetic disk (floppy disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), semiconductor It can also be stored in a storage medium such as a memory or transmitted and distributed via a communication medium. The program stored on the medium side includes a setting program for causing the computer to execute software means (including not only an execution program but also a table and a data structure) to be executed in the computer. A computer that realizes the present apparatus reads a program recorded in a storage medium, and in some cases, constructs software means by using a setting program, and executes the above-described processing by controlling the operation of the software means.

[0028]

As described above in detail, according to the present invention, when the turbine trips, the previously calculated addition of the bypass valve opening corresponding to the amount of steam flowing into the turbine is added. It is possible to provide a steam turbine steam bypass device capable of minimizing the pressure fluctuation of the high-pressure steam reservoir due to the operation of the bypass valve, preventing the influence on other facilities, and reducing the burden on the operator.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a steam system to which a steam turbine steam bypass device according to an embodiment of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Computer 2 ... PID module 3 ... Addition module 4 ... Flow valve opening degree conversion module 5 ... Select module 6 ... Boiler drum 7 ... High pressure steam storage 8 ... Pressure sensor 9 ... Steam flow sensor 10 ... Steam turbine 11 ... Turbine bypass valve 12 ... High pressure steam condenser 13 ... Change rate limiting module

Claims (1)

[Claims] 1. A turbine bypass valve for adjusting the pressure of the high-pressure steam sump by discharging steam of the high-pressure steam sump, a sensor for measuring a steam flow rate flowing into the steam turbine from the high-pressure steam sump, and the sensor Flow valve opening degree conversion means for calculating an increase in the degree of opening of the turbine bypass valve corresponding to the measured steam flow rate; and when the steam turbine trips, the valve opening degree calculated from the flow rate valve opening degree conversion means. And a bypass valve control means for controlling the turbine bypass valve by adding the increment.