DE102023203690A1 - Method for heating inlet valves of turbines and quick-closing valve for carrying out the method - Google Patents

Abstract

The invention relates to a method for starting up a steam turbine system (1) and heating up at least one control valve (2) of the steam turbine system (1), wherein the steam turbine system (1) comprises at least one steam generator (3) which is fluidically connected to at least one steam turbine (5) via at least one pipeline (4), wherein at least one quick-closing valve (6) and the control valve (2) are arranged one behind the other in the direction of flow within the pipeline (4), and wherein at least one heating valve (7) is arranged upstream of the quick-closing valve (6) within the pipeline (4), via which the fresh steam can be discharged during the heating process. Furthermore, the invention relates to a quick-closing valve for carrying out such a method according to the invention.

Description

The invention relates to a method for heating inlet valves of turbines according to the features of independent patent claim 1 and a quick-closing valve for carrying out such a method, according to patent claim 2.

If cold components are exposed to hot steam, film condensation occurs on the surface at saturated steam temperature. Due to the high heat transfer, high thermomechanical stresses form in thick-walled components. These must be limited over the service life and mechanical integrity of the components by slowly increasing the steam pressure.

In order to be able to gently warm up the turbine control valves using controlled pressure build-up, the fresh steam pressure must be regulated during warm-up. Previous turbine protection systems and start-up step chains stipulate that the warm-up of the valves can only start when the fresh steam pressure has already reached a high level in order to provide sealing steam and evacuate the turbine. In order to warm up the control valves, the fresh steam pressure must be subsequently reduced. This sometimes always requires a separate fresh steam slide valve that separates the turbine and boiler and can be used to achieve a controlled pressure build-up via its bypass line.

As an alternative to the main steam valves, the valves are preheated electrically to avoid the controlled pressure build-up.

The previously described options for heating inlet valves require additional components and are therefore cost-intensive.

Based on the previously described prior art, it is therefore the object of the present invention to provide a method for starting up a steam turbine system and heating at least one inlet valve of the steam turbine system, which can be carried out simply and without additional effort. Furthermore, it is the object of the present invention to provide a quick-closing valve for carrying out the method.

The method according to the invention is solved by the features of independent patent claim 1 and the quick-closing valve according to the invention is solved by the features of independent patent claim 2.

• - Anfahren des Dampferzeugers bei geschlossenem Schnellschluss- und Regelventil;
• - Bereitstellen von Frischdampf mittels des Dampferzeugers;
• - Messen der Dampfparameter des bereitgestellten Frischdampfes;
• - Öffnen des Schnellschlussventils bei Erreichen eines vorgegebene Mindestdrucks, wobei das Regelventil weiterhin geschlossen bleibt:
• - Kontinuierliches Messen der Temperatur des Regelventils;
• - Schließen und Öffnen des Schnellschlussventils in Abhängigkeit von der Temperatur des Regelventils, wobei beim Erreichen einer vorgegebenen Höchsttemperatur des Regelventils das Schnellschlussventil schließt und beim Unterschreiten einer vorgegeben Mindesttemperatur des Regelventils öffnet;
• - Anfahren der Dampfturbine bei Erreichen vorgegebener Frischdampfparameter (Dampf, Temperatur, Überhitzung...).

The method according to the invention for starting up a steam turbine system and heating at least one inlet valve of the steam turbine system, wherein the steam turbine system comprises at least one steam generator which is fluidically connected to at least one steam turbine via at least one pipeline, wherein at least one quick-closing valve and one control valve are arranged one behind the other in the flow direction within the pipeline and wherein at least one heating valve is arranged in front of the quick-closing valve within the pipeline, via which the fresh steam can be discharged during the heating process, is characterized by the following method steps:

• - Starting up the steam generator with the quick-closing and control valve closed;
• - Provision of fresh steam by means of the steam generator;
• - Measuring the steam parameters of the fresh steam provided;
• - Opening the quick-closing valve when a specified minimum pressure is reached, while the control valve remains closed:
• - Continuous measurement of the temperature of the control valve;
• - Closing and opening of the quick-closing valve depending on the temperature of the control valve, whereby the quick-closing valve closes when a predetermined maximum temperature of the control valve is reached and opens when a predetermined minimum temperature of the control valve is undercut;
• - Start-up of the steam turbine when specified fresh steam parameters are reached (steam, temperature, superheat...).

The method according to the invention enables early opening of the quick-closing valve and thus joint heating of the steam generator, pipes and turbine valves.

When the pressure begins to build up when the steam generator is started up, the quick-closing valve is opened after a minimum pressure is reached and the control valve is preheated together with the pipes by the slow pressure build-up of the steam generator.

Since steam is present at the control valve for a long time in the method according to the invention, the heat input into the turbine housing must be limited in order to avoid uneven heating and distortion. This is achieved by closing the quick-closing valve during the heating procedure as soon as the control valve has warmed up to a predefined maximum temperature. If the temperature falls below a minimum temperature, which can also be predefined, the quick-closing valve is opened again. By alternately opening and closing By opening the quick-closing valve during start-up of the steam turbine plant, an almost constant temperature is achieved in the control valve.

The method according to the invention makes it possible to open the quick-closing valve very early without damaging the turbine and without having to make compromises in turbine protection.

The method according to the invention makes it possible to eliminate the need for the fresh steam valve, which leads to considerable cost savings.

By heating up together, the overall start-up time is faster than with conventional methods.

The quick-closing valve according to the invention for carrying out a method according to claim 1 is characterized in that the quick-closing valve can be closed not only with spring force, but also by means of a partial stroke solenoid valve. The quick-closing valve therefore does not close suddenly against spring force as in regular operation, but is closed slowly, which ensures that the quick-closing valve opens and closes gently.

• 1: Eine erfindungsgemäße Dampfturbinenanlage.

Further advantages of the invention, which can be used individually or together, are explained below using an exemplary embodiment. It shows:

• 1 : A steam turbine plant according to the invention.

The figures show only the schematic structure and are not necessarily to scale. Essentially, only the components necessary for the invention are shown.

1 shows a steam turbine system 1 according to the invention, on which the method according to the invention for starting up the steam turbine system 1 and heating up the control valve 2 of the steam turbine system 1 is explained below. The steam turbine system 1 comprises at least one steam generator 3, which is fluidically connected to the steam turbine 5 via a pipeline 4. At least one quick-closing valve 6 and the control valve 2 are arranged one behind the other in the flow direction 10 within the pipeline 4. In the flow direction 10, a heating valve 7 is arranged in front of the quick-closing valve 6 within the pipeline 4, via which the fresh steam can be discharged during the heating process. Furthermore, a drainage valve 9 for draining the pipeline 4 and optionally a fresh steam slide valve 8 can be provided. The fresh steam slide valve 8 was previously installed as standard to enable a controlled pressure build-up and the slow heating of the control valve 2; alternatively, electrical preheating could be provided. A significant advantage of the invention is that the fresh steam slide valve or electrical preheating can be omitted, which is explained below and which contributes to considerable cost savings.

The start-up process and the heating of the control valve (2) are explained below using the main process steps. First, the steam generator is started with the quick-closing and control valve (6, 2) closed. When the pressure builds up when the steam generator starts up, the quick-closing valve (6) is opened after a minimum pressure has been reached and the control valve (2) is preheated together with the pipes (4) as the pressure builds up slowly. Since steam is present at the control valve (2) for a long time, the heat input into the turbine housing must be limited in order to avoid uneven heating and warping. This is achieved by closing the quick-closing valve (2) during the heating procedure as soon as the control valve (2) reaches a specified maximum temperature and opening the quick-closing valve (2) again as soon as the control valve falls below a specified minimum temperature. This allows the control valve to be kept within a specified temperature range during the heating process. When the specified fresh steam parameters (steam, temperature, superheat...) are reached, the control valve (2) is opened and the steam turbine is started.

With the method presented, the steam turbine plant (1) can be started up without a main steam valve if the steam turbine (5) and steam generator (3) are started up together. Under certain conditions, the main steam valve (8) can be omitted entirely, which leads to considerable cost savings.
Due to the joint warm-up, the overall start-up time is faster than with conventional methods.

Claims (2)

Method for starting up a steam turbine plant (1) and heating up at least one control valve (2) of the steam turbine plant (1), wherein the steam turbine plant (1) comprises at least one steam generator (3) which is fluidically connected to at least one steam turbine (5) via at least one pipeline (4), wherein within the pipeline (4), one behind the other in the flow direction, at least one quick-closing valve (6) and the control valve (2) are arranged and wherein at least one heating valve (7) is arranged in front of the quick-closing valve (6) within the pipeline (4), via which the fresh steam can be discharged during the heating process , characterized by the following method steps: - starting up the steam generator (1) with the quick-closing and control valve (6, 2) closed; - providing fresh steam by means of the steam generator (3); - measuring the steam parameters of the fresh steam provided; - opening the quick-closing valve (6) when a predetermined minimum pressure is reached, with the control valve (2) remaining closed: - continuously measuring the temperature of the control valve (2); - closing and opening the quick-closing valve (6) depending on the temperature of the control valve (2), with the quick-closing valve (6) closing when a predetermined maximum temperature of the control valve (2) is reached and opening when the temperature of the control valve (2) falls below a predetermined minimum temperature; - starting up the steam turbine (5) when predetermined fresh steam parameters are reached. Quick-closing valve (2) for carrying out a process according to claim 1 , characterized in that the quick-closing valve (2) comprises a partial stroke solenoid valve which enables a controlled actuation of the quick-closing valve (2).

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