JPH07233710A - Starting device by steam turbine in combined plant - Google Patents

Abstract

PURPOSE:To improve reliability by realizing smooth switching to a gas turbine exhaust gas boiler generation steam system from a start-drive steam system to prevent sudden change in the engine speed of steam and gas turbines and the occurrence of the thermal stress of the steam turbine to prolong the life of the steam turbine. CONSTITUTION:In a starting device by a steam turbine in a combined plant, a bypass line 9, connecting a start-drive steam system 6 and an exhaust gas boiler generation steam system 8, is provided, and a flow rate control valve 2 is provided on the bypass line 9 to finally make the vapor in an exhaust gas boiler 7 main steam with each steam balance-controlled be flowed into the steam turbine 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine starter for a combined plant.

[0002]

2. Description of the Related Art A combined plant drives exhaust gas of a gas turbine to an exhaust heat recovery boiler, recovers the heat of the exhaust gas and generates steam to drive a steam turbine. By controlling the operation of the plant in which the gas turbine and the steam turbine are combined as one unit, it is possible to improve efficiency at a partial load, start and stop in a short time, and change the load. As shown in the system diagram of FIG. 6, the flow around the inlet steam of the combined plant having such characteristics is shown in FIG.
And a starting / driving steam system 6 having a check valve 3 and an exhaust gas boiler generating steam system 8 having a motor-operated valve 5 arranged from an exhaust heat recovery boiler (hereinafter referred to as an exhaust gas boiler) 7 join together,
The confluent pipe 10 is arranged so as to flow into the steam turbine 4 through the main steam stop valve 11 and the speed control valve 12.

In a conventional starter for such a system, the electric valve 5 of the exhaust gas boiler generating steam system 8 is first closed while the gas turbine is stopped,
The steam turbine 4 is started by sending steam from the starting / driving steam system 6 while controlling the flow control valve 1, and then after the gas turbine is ignited, when steam is generated from the exhaust gas boiler 7, the motor-operated valve 5 is gradually opened to start the steam turbine 4. It is mixed with the steam of the steam system 6 and sent to the steam turbine 4. Then, when the gas turbine speed increases and the gas turbine displacement increases and the motor-operated valve 5 is fully opened, the check valve 3 of the starting / driving steam system 6 is fully closed,
The steam to the steam turbine is sent only by the steam generated from the exhaust gas boiler (main steam).

[0004]

According to the conventional starting method of the combined plant as described above, the starting / driving steam conditions (pressure / temperature) for starting and driving the steam turbine and the gas turbine ignition are used. Since the steam conditions (pressure / temperature) of the steam generated from the exhaust gas boiler after operation differ, it is not possible to smoothly switch from the starting / driving steam to the exhaust gas boiler generated steam, and the rotation speed of the gas turbine and steam turbine suddenly changes. And a thermal stress is generated due to a sudden temperature difference, which significantly shortens the life of the steam turbine. The present invention has been proposed in order to solve the above problems in a conventional combined plant, and enables a smooth switching from a starting / driving steam system to a gas turbine exhaust gas boiler generating steam system, Combined type that can prevent the sudden change of the rotation speed of the gas turbine and the thermal stress of the steam turbine to extend the life of the steam turbine and improve the reliability.
It is intended to provide a starting device in a plant.

[0005]

Therefore, according to the present invention, in a starter apparatus using a steam turbine in a combined plant, a bypass pipe line for connecting a start / drive steam system and an exhaust gas boiler generating steam system is provided, and the bypass pipe is provided. A flow control valve is installed in the passage to control both steams in a balanced manner, and finally the exhaust gas boiler steam is used as the main steam, which is made to flow into the steam turbine and used for driving the steam turbine. It is a means to

[0006]

According to the present invention, in a starter using a steam turbine in a combined plant, a bypass pipe connecting a starting / driving steam system and an exhaust gas boiler generating steam system is provided, and a flow control valve is provided in the bypass pipe. By controlling the balance of both steam systems with the same control valve, the gas turbine is ignited while it is started by the starting / driving steam and is being fed to the steam turbine, and steam is generated from the exhaust gas boiler to control the flow rate of the bypass pipe. Is gradually opened and is fed to the steam turbine while being mixed with the driving steam. Next, when the rotational speed of the gas turbine increases and the gas turbine displacement increases,
The opening of the flow control valve in the bypass line is almost fully opened. In this state, the check valve of the starting / driving steam system is fully opened, and only the exhaust gas boiler-generated steam from the bypass pipe is supplied to the steam turbine. Next, when the steam is completely transferred to the exhaust gas boiler, the flow control valve of the starting / driving steam system is slowly and fully opened from the steam turbine required steam control at the time of startup, and the steam pressure generated by the exhaust gas boiler is increased to near the steam pressure.
Further, after the flow rate control valve is fully opened, the electric valve for the exhaust gas boiler-generated steam is completely closed to fully opened to complete the normal operation mode. In other words, the start-up / driving steam with different pressure and temperature conditions and the exhaust-gas boiler-generated steam are mixed gently by using a bypass pipe line to balance them gently so that the pressure and temperature differences in both steam systems are absorbed. Therefore, it is possible to avoid sudden changes in the rotation speed and occurrence of thermal stress in the steam turbine.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments of the drawings. FIGS. 1 to 5 show the embodiments of the present invention. First, in FIG. 1, according to the present invention, a bypass line 9 that connects an upstream portion of a flow rate control valve 1 of a start / drive steam system 6 and an upstream portion of an electric valve 5 that is a flow rate control valve of an exhaust gas boiler generating steam system 8 is provided. The bypass pipe 9 is provided with a flow rate control valve 2. At the time of starting the combined plant, starting steam is sent from the starting / driving steam system 6 of FIG. 1 to drive the steam turbine 4. At that time, the electric valve 5 of the exhaust gas boiler generating steam system 8 and the flow rate control valve 2 of the bypass line 9 are closed.

FIG. 2 shows a state after the gas turbine is ignited while the driven steam after driving is being sent to the steam turbine. Steam is generated from the exhaust gas boiler 7, and the generated steam is generated by the motor-operated valve 5. Since it is closed, the bypass line 9 and the flow rate control valve 2 are gradually opened to be in a mixed state with the driving steam.

FIG. 3 shows a state in which the gas turbine rotational speed is increased and the gas turbine displacement is increased so that the flow control valve 2 in the bypass line 9 is fully opened. Since the check valve 3 is completely closed, the steam turbine driving steam is only the exhaust gas boiler-generated steam flowing through the bypass pipe 9.

FIG. 4 shows a state in which the operation is completely shifted to the steam generated by the exhaust gas boiler.
Since the flow control valve 1 of No. 1 gradually opens to the full extent from the control at the time of startup and rises to almost the same level as the exhaust gas boiler generated steam pressure, the electric valve 5 of the exhaust gas boiler generated steam system 8 which is the flow control valve There is almost no difference in vapor pressure between upstream and downstream.

In this state, as shown in FIG. 5, the flow control valve 1 of the starting / driving steam system 6 is fully opened, and the electric valve 5 of the exhaust gas boiler generating steam system 8 is fully opened to set the normal operating state. Become. Thus, when switching the steam from the starting / driving system at the time of startup to the gas turbine exhaust gas boiler generating steam system at the time of normal operation, the both steam systems are balanced-controlled through the bypass line 9 as described above, and the exhaust gas boiler is controlled. When the motor-operated valve 5 in the generated steam system 8 is opened, there is almost no difference in steam pressure between the upstream and downstream of the motor-operated valve 5, and the valve can be smoothly opened. By mixing the exhaust gas and the steam generated by the exhaust gas boiler in a well-balanced manner by using a bypass pipe line, the pressure difference and temperature difference in both steam systems are absorbed, and sudden changes in the rotational speed and the steam turbine The generation of thermal stress can be avoided in advance.

[0012]

As described in detail above, according to the present invention, since the switching from the starting / driving steam system to the exhaust gas boiler generating steam system can be performed without causing an extreme change in the steam condition, the conventional apparatus can be used. It is possible to eliminate the causes of shortening the life of the steam turbine, such as the sudden change in the rotational speed of the steam turbine and the gas turbine, which is seen at the time of switching, and the thermal stress of the steam turbine. Therefore, the effect of improving the reliability of the combined plant is extremely large.

[Brief description of drawings]

FIG. 1 is a system diagram of a steam turbine starter according to an embodiment of the present invention.

FIG. 2 is a system diagram showing a state in which a control valve 2 of a starter for a steam turbine according to an embodiment of the present invention is opened.

FIG. 3 is a system diagram in which a control valve 2 in FIG. 1 is fully opened and a check valve 3 is fully closed.

FIG. 4 is a system diagram showing a state in which a control valve 1 of FIG. 1 is opened.

FIG. 5 is a system diagram showing a normal operation state in which the motor-operated valve 5 of FIG. 1 is fully opened.

FIG. 6 is a system diagram around an inlet steam of a conventional combined plant.

[Explanation of symbols]

 1 Flow Control Valve 2 Bypass Flow Control Valve 3 Check Valve 4 Steam Turbine 5 Motorized Valve 6 Start / Drive Steam System 7 Exhaust Gas Boiler 8 Exhaust Gas Boiler Generated Steam System 9 Bypass Pipeline 10 Confluent Pipe 11 Steam Stop Valve 12 Speed Control Valve

Claims (2)

[Claims] 1. A steam turbine starter in a combined plant, wherein a bypass pipe connecting a starting / driving steam system and an exhaust gas boiler generating steam system is provided, and a flow control valve is provided in the bypass pipe to provide both steams. The starting device by the steam turbine of the combined plant is characterized in that the exhaust gas boiler steam is finally flowed into the steam turbine as the main steam while performing balance control. 2. The bypass pipe line connects upstream portions of respective flow control valves in both the steam system of the starting / driving steam system and the steam system of exhaust gas boiler generation. Starter by steam turbine of combined plant.