Fluid handling – Processes – Affecting flow by the addition of material or energy
Reexamination Certificate
1999-11-09
2001-10-23
Chambers, A. Michael (Department: 3753)
Fluid handling
Processes
Affecting flow by the addition of material or energy
C137S340000, C137S339000, C060S680000
Reexamination Certificate
active
06305398
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a valve configuration which is to be heated and a method for heating a valve configuration of a steam turbine.
Published German Patent Application No. 14 26 850 discloses a regulating device for a steam-turbine plant having a high-pressure turbine section and an intermediate-pressure turbine section as well as a reheater provided between the turbine sections. Provided upstream of each turbine section is a valve configuration having in each case a quick-acting valve and a regulating valve. A bypass line, which is closed by two shut-off valves, branches off from the reheater to a condenser.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method for heating a valve of valve configuration of a steam turbine and a valve configuration for a steam turbine which overcome the disadvantages of the heretofore-known methods and devices of this general type and which are simple and reliable. The method for heating a valve should be suited, in particular, for keeping a bypass-valve configuration hot and for heating up an intermediate-pressure valve configuration. The valve configuration should be a low cost configuration, in particular, in terms of the pipework needed.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for heating a valve of a valve configuration of a steam turbine. The method includes the steps of directing steam to the valve of the valve configuration, while the valve is in a closed state; condensing the steam in the valve and forming a condensate; and discharging the condensate.
In accordance with another mode of the invention, a bypass-valve configuration is connected to a condenser. Live steam is used as the steam for heating by feeding it via a bypass line to the bypass-valve configuration.
In accordance with a further mode of the invention, an intermediate-pressure valve configuration is connected to a steam turbine. Live steam is fed to the steam turbine and is used for heating the intermediate-pressure valve configuration.
With the objects of the invention in view there is also provided, a valve configuration for a steam turbine, including a valve being in a closed state, and a steam line having a line section opening into the valve, the line section being sloped with respect to a horizontal line and directing steam to the valve for heating the valve by condensing the steam and forming a condensate.
In accordance with another feature of the invention, the line section extends with a falling slope from the valve and has a lowest point. A draining device is connected to the steam line via the lowest point.
In accordance with a further feature of the invention, the line section extends with a rising slope from the valve and has a lowest point. A draining device, which opens when the condensate is formed, is connected to the valve at the lowest point.
The term valve configuration refers in particular to a bypass-valve configuration and/or an intermediate-pressure valve configuration which in each case may include a quick-acting valve with a control valve connected downstream.
The invention is based on the relization that providing a heating-up line involves a considerable amount of material and is therefore very cost-intensive, in particular in the case of a bypass-valve configuration for low-pressure or intermediate-pressure steam of a steam turbine having a bypass to the condenser of the steam turbine. In this case, the bypass can branch off from a live-steam line, which is run to the steam turbine, between a steam strainer and a live-steam or intermediate-pressure valve configuration. The bypass-valve configuration is heated up on the quick shut-off side via the heating-up line when the quick-acting valve is closed. To this end, the heating-up line would have to be run to the bypass-valve configuration in such a way that, due to a pressure gradient generated along the steam strainer, a steam flow has a steam circulation closed via the quick-acting valve and via the bypass. In a configuration having a steam strainer provided in the quick-acting valve of the intermediate-pressure valve configuration, a pressure gradient necessary for the circulation of the heating-up steam would be very small, so that, due to the small pressure gradient, lines having a large diameter are therefore necessary for achieving the required mass flow for heating the bypass-valve configuration. This in turn leads to high costs in terms of the material needed. This disadvantage can be avoided with a heating by condensation according to the invention, since no separate lines are necessary.
In a preferred embodiment of the invention, the heating temperature is expediently kept constant at the saturated-steam temperature by continuously discharging the condensate. In order to keep the bypass-valve configuration, which is run to the condenser of the steam turbine, hot, it is advantageous to use the partial flow of the live steam fed to the steam turbine that is already fed to this valve configuration via the bypass on the quick shut-off side.
In principle, a condenser effect is utilized in order to heat up the bypass-valve configuration and to keep it hot, in contrast to utilizing a steam circulation produced by a pressure difference. This condenser effect occurs due to the presence of merely the bypass itself at a blind hole forming upstream of the closed quick-acting valve of the bypass-valve configuration. A flow develops due to the steam column which moves up in the bypass and the steam condenses upstream of the closed quick-acting valve as a result of a temperature gradient along the valve configuration. At a given pressure, the corresponding saturated-steam temperature is kept by a continuous discharge of the condensate on the inflow side of the valve configuration.
This effect is also advantageously utilized during the start-up of the steam turbine by heating up the intermediate-pressure valve configuration connected upstream of the steam turbine through the use of live steam fed to the steam turbine. Here, too, the condensate is discharged, which is produced due to the temperature difference along the valve configuration by cooling off the steam flowing in at live-steam temperature towards the closed quick-acting valve of the valve configuration. Here again, the saturated-steam temperature, corresponding to the respectively prevailing live-steam pressure, is automatically present as long as the generated condensate is discharged continuously.
With regard to the apparatus according to the invention, an essential feature is an angled or oblique configuration of the steam line run to the valve configuration. In this case, the steam line run to the valve configuration expediently has a line section which is provided with a falling or rising slope and then forms the inflow section of the valve configuration.
In the case of a line section provided with a falling slope, a draining opening for discharging the condensate, which is produced, is provided at the lowest point of this section. In an analog manner, in the case of a line section provided with a rising slope, a corresponding draining leadthrough is provided in the valve configuration preferably upstream of the inflow-side valve seat or valve disc of the quick-acting valve. A draining device attached to the draining opening or to the draining leadthrough may be a valve which opens automatically when condensate collects or may be a so-called condensomat, which may be embodied as a radial-stage throttle drain valve.
The advantages achieved by the invention are based in particular on the fact that, by utilizing the condenser effect or condensation effect directly at a closed valve configuration, an additional heating-up line and an additional line extension for producing a pressure difference for a natural steam circulation are dispensed with. On the contrary, the existing steam lines, namely the existing bypass on the one hand and the live-steam line on the other hand, can be u
Gobrecht Edwin
Logar Andreas
Neumann Rainer
Chambers A. Michael
Greenberg Laurence A.
Lerner Herbert L.
McShane Thomas L.
Siemens Aktiengesellschaft
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