A method for heating a turbine inlet valve, and a rapid shut-off valve for carrying out the method.

Abstract

The present invention relates to a method for starting a steam turbine plant (1) and heating at least one control valve (2) of the steam turbine plant (1), wherein the steam turbine plant (1) includes at least one steam generator (3), the steam generator (3) is fluidly connected to at least one steam turbine (5) via at least one pipe (4), the pipe (4) having at least one rapid shut-off valve (6) and a control valve (2) arranged in this order in the flow direction, and the pipe (4) having at least one heating valve (7) upstream of the rapid shut-off valve (6), through which fresh steam can be discharged during the heating process. Furthermore, the present invention also relates to a rapid shut-off valve for carrying out such a method according to the present invention.

Description

Technical Field

[0001] The present invention relates to a method for heating an inlet valve of a turbine according to the features of independent claim 1 and to a quick closing valve for carrying out such a method according to claim 2.

Background Art

[0002] When cold components are exposed to high-temperature steam, film condensation occurs on the surface at the saturated steam temperature. Due to high heat transfer, large thermomechanical stresses occur in thick components. From the viewpoint of the life and mechanical integrity of the components, it is necessary to limit these stresses by gradually increasing the steam pressure.

[0003] In order to be able to gently heat the turbine control valve by a controlled pressure increase, it is necessary to adjust the fresh steam pressure during heating. In conventional turbine protection systems and startup step sequences, the heating of the valve cannot be started until the fresh steam pressure has already reached a high level in order to be able to supply blocking steam and exhaust the turbine. In order to heat the control valve, it is necessary to subsequently lower the fresh steam pressure. For this purpose, conventionally, a separate fresh steam slide valve has always been necessary to separate the turbine and the boiler and to be able to control the pressure increase via a bypass pipe.

[0004] As an alternative to the fresh steam slide valve, a method of electrically preheating the valve has also been adopted in order to avoid the control of the pressure increase.

[0005] All of the heating means for the inlet valve described above require additional components and are therefore costly.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, starting from the aforementioned prior art, the object of the present invention is to provide a method for starting a steam turbine system and heating at least one inlet valve that can be easily implemented without requiring additional effort. Furthermore, the object of the present invention is to provide a rapid shut-off valve for implementing the said method. [Means for solving the problem]

[0007] The method of the present invention is realized by the features of independent claim 1, and the rapid shut-off valve of the present invention is realized by the features of independent claim 2.

[0008] The method for starting a steam turbine system and preheating at least one inlet valve according to the present invention comprises a steam turbine system including at least one steam generator, which is fluidly connected to at least one steam turbine via at least one pipe, in which at least one rapid shut-off valve and one control valve are arranged in succession along the flow direction within the pipe, and further, in the pipe upstream of the rapid shut-off valve, at least one preheating valve is arranged which is capable of discharging fresh steam during the preheating process. The process of starting the steam generator with the rapid shut-off valve and control valve closed, • A process of supplying fresh steam using a steam generator, • A process of measuring the steam parameters of the supplied fresh steam, The process involves opening the rapid shut-off valve when a predetermined minimum pressure is reached, while keeping the control valve closed at the same time. • A process of continuously measuring the temperature of the control valve, The process involves opening and closing the rapid shut-off valve according to the temperature of the control valve, closing the rapid shut-off valve when the control valve reaches a predetermined maximum temperature, and opening the rapid shut-off valve when it falls below a predetermined minimum temperature. • A fixed mechanism that starts the steam turbine when predetermined fresh steam parameters (steam, temperature, superheating degree, etc.) are reached. It holds.

[0009] According to the method of the present invention, the rapid shut-off valve can be opened early, thereby enabling simultaneous heating of the steam generator, piping, and turbine valve.

[0010] When the steam generator starts up and the pressure begins to rise, the rapid shut-off valve is released when the minimum pressure is reached, and the control valve is preheated simultaneously with the piping due to the gradual pressure increase of the steam generator.

[0011] In the method of the present invention, since steam acts on the control valve over a long period of time, it is necessary to limit the heat input to the turbine casing to prevent uneven heating and distortion. This is achieved by closing the rapid shut-off valve when the control valve is heated to a predetermined maximum temperature during the preheating procedure, and similarly opening the rapid shut-off valve again when it falls below a predetermined minimum temperature. By alternately opening and closing the rapid shut-off valve during the startup of the steam turbine equipment, a nearly constant temperature is maintained within the control valve.

[0012] The method of the present invention allows the rapid shut-off valve to be opened very early without damaging the turbine or compromising turbine protection.

[0013] The method of the present invention eliminates the need for a fresh steam slide valve, thereby achieving significant cost reductions.

[0014] By performing a common heating process, the overall startup time is shortened compared to conventional methods.

[0015] The rapid shut-off valve of the present invention for carrying out the method of claim 1 is characterized in that it can be closed not only by spring force but also by a partial-stroke solenoid valve. Therefore, the rapid shut-off valve does not close abruptly against spring force as in normal operation, but closes slowly, thus ensuring smooth opening and closing of the rapid shut-off valve.

[0016] Further advantages of the present invention, which can be used alone or in combination, will be described below with reference to examples. [Brief explanation of the drawing]

[0017] [Figure 1] This shows a steam turbine system according to the present invention. [Modes for carrying out the invention]

[0018] This diagram merely shows a schematic configuration and is not necessarily to scale. Only the components necessary for the present invention are primarily shown.

[0019] Figure 1 shows a steam turbine system 1 according to the present invention. The following describes the starting method for this steam turbine system 1 and the heating method for the control valve 2 of the steam turbine system 1 according to the present invention. The steam turbine system 1 includes at least one steam generator 3, which is fluidly connected to a steam turbine 5 via piping 4. Along the flow direction 10, at least one rapid shut-off valve 6 and a control valve 2 are sequentially arranged in the piping 4. A heating valve 7 is located in the piping 4 upstream of the rapid shut-off valve 6 in the flow direction 10, allowing fresh steam to be discharged during the heating process. Furthermore, a drain valve 9 for draining the piping 4 and optionally a fresh steam slide valve 8 can be provided. Conventionally, the fresh steam slide valve 8 was standardly provided to control the pressure rise and enable gradual heating of the control valve 2, but it was also possible to perform electrical preheating as an alternative. A major advantage of the present invention is that the fresh steam slide valve or electrical preheating is unnecessary, which leads to significant cost reductions.

[0020] Regarding the startup process and the heating of the control valve (2), the main steps are described below. First, start the steam generator with the quick closing valve and the control valve (6, 2) closed. When the pressure starts to rise during the startup of the steam generator, the quick closing valve (6) is released when the minimum pressure is reached, and the control valve (2) is preheated together with the piping (4) due to a gentle pressure increase. At this time, since steam acts on the control valve (2) for a long time, it is necessary to limit the heat input to the turbine casing to prevent non-uniform heating and deformation. This is achieved by closing the quick closing valve (2) when the control valve (2) reaches a predetermined maximum temperature during the heating process, and by reopening the quick closing valve (2) when the control valve drops below a predetermined minimum temperature. As a result, the control valve is maintained within a predetermined temperature range during the heating process. When a predetermined fresh steam parameter (steam, temperature, degree of superheat, etc.) is reached, the control valve (2) is opened and the steam turbine is started.

[0021] According to the method presented, if the steam turbine (5) and the steam generator (3) are started simultaneously, the steam turbine facility can be started without the fresh steam slide valve (8). Under specific conditions, the fresh steam slide valve can be completely omitted, resulting in significant cost savings.

[0022] By performing common heating, the overall startup time is generally shortened compared to the conventional method.

Explanation of symbols

[0023] 1 Steam turbine plant 2 Control valve 3 Steam generator 4 Piping 5 Steam turbine 6 Quick closing valve 7 Heating valve 8 Fresh steam slide valve 9 Drain valve 10 Flow direction

Claims

1. A method for starting a steam turbine plant (1) and heating at least one control valve (2) of the steam turbine plant (1), The steam turbine plant (1) includes at least one steam generator (3), and the steam generator (3) is fluidly connected to at least one steam turbine (5) via at least one pipe (4). Inside the piping (4), at least one rapid shut-off valve (6) and the control valve (2) are arranged in this order in the flow direction. In a method in which at least one heating valve (7) is placed inside the piping (4) upstream of the rapid shut-off valve (6), and fresh steam is discharged through the heating valve (7) during the heating process, - A step of starting the steam generator (1) with the rapid shut-off valve (6) and the control valve (2) closed, - A step of supplying fresh steam by the steam generator (3), - A process to measure the steam parameters of the supplied fresh steam, - A step of opening the rapid shut-off valve (6) when a predetermined minimum pressure is reached, while keeping the control valve (2) closed, - A step of continuously measuring the temperature of the control valve (2), - The process involves opening and closing the rapid shut-off valve (6) according to the temperature of the control valve (2), closing the rapid shut-off valve (6) when the control valve (2) reaches a predetermined maximum temperature, and opening it when it falls below a predetermined minimum temperature. - A step of starting the steam turbine (5) when a predetermined fresh steam parameter is reached, A method of having.

2. A rapid shut-off valve (2) for carrying out the method of claim 1, wherein the rapid shut-off valve (2) includes a partial stroke solenoid valve, and the partial stroke solenoid valve enables controlled operation of the rapid shut-off valve (2).

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