Fluid handling – Systems – Multiple inlet with multiple outlet
Reexamination Certificate
1999-07-28
2001-02-27
Fox, John (Department: 3753)
Fluid handling
Systems
Multiple inlet with multiple outlet
C137S599140, C137S601170
Reexamination Certificate
active
06192930
ABSTRACT:
THE BACKGROUND OF THE INVENTION AND PRIOR ART
The present invention refers to a valve device according to the precharacterizing portion of claim
1
.
It is known to use such valve devices in connection with a combustion plant comprising a pressurized fluidized bed, a so called PFBC-plant (Pressurized Fluidized Bed Combustion). Such plants may comprise a gas turbine for extracting energy from the pressurized, hot combustion gases produced in the bed, and the compressed combustion air required at the combustion may be supplied to the bed via an air channel which has an annular cross-section and encloses the hot gas channel conveying the combustion gases from a combustion chamber to the gas turbine. Furthermore, it is known to provide such channels with a valve device which in the case of a gas turbine trip, i.e. that the gas turbine has to be stopped quickly, isolates the gas turbine from the pressure vessel.
SE-B-456 757 discloses such a valve device which is intended to be used in a PFBC-plant. The known valve device comprises two throttle valves which are provided one after the other in the hot gas channel and which are rotatable about a respective rotational axis. Furthermore, it comprises four cone valves which are distributed around the periphery of the air channel and which are intended to intercept the annular air channel and concurrently open a connection between the annular air channel and the hot gas channel. These four cone valves are provided in parallel, i.e. all four of them are to function in order to intercept the flow through the air channel. Although this known valve device has functioned satisfactorily in the plants where it is mounted today, it is connected with certain problems appearing in particular by the construction of very large combustion plants. Furthermore, these cone valves require powerful adjustment members for their operation and a valve spindle guiding which is provided in direct connection to the hot gas, which results in the problem of jamming of the valve. Another problem connected to this known valve device is that it comprises a large and complicated casting. Such castings are not possible to manufacture at least not to justifiable costs in the case of large plants having great flows. In addition, the known valve device comprises a fairly complicated flow path which results in high pressure drops at least with respect to the air channel.
EP-A-721 062 discloses such a valve device intended for a PFBC-plant. In this case, the whole valve device including all three valve functions is arranged in a common valve housing having significant dimensions. As appears from this document, the gas turbine and the compressor are provided above said valve housing. Furthermore, all three valve functions are depending on one adjustment member and provided on a common shaft. From a security point of view, this known valve device thus has a very small redundancy.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a valve device by which the problems discussed above may be remedied.
This object is obtained by the valve device initially defined and characterized in that the outer channel comprises two U-shaped channel portions, each extending outwardly with regard to the inner channel and each comprising at least one of said first valves. By such a valve device, a relatively compact construction with a low height is possible although the valve device is intended for large plants. By the provision of at least two U-shaped channel portions, it is possible to avoid thermal deformation of the valve device. Thereby, the U-shaped channel portions are advantageously provided symmetrically with regard to the inner channel.
According to an embodiment of the present invention, at least one of said first valves comprises a valve disc which is rotatable about a rotational axis extending through the intermediate pipe portion. Such rotatable valve discs or so called throttle valves may, in comparison with axially displaceable cone valves, be manufactured in a simple manner and be operated by means of small and relatively simple adjustment members.
According to a further embodiment of the present invention, each channel portion comprises two pipe portions, which extend outwardly with regard to the inner channel, and an intermediate pipe portion, which connects the pipe portions extending outwardly. Thereby, the two pipe portions extending outwardly may extend in a direction forming an essentially right angle to the longitudinal direction of the inner channel. Furthermore, the intermediate pipe portions may advantageously extend in a direction being essentially parallel to the longitudinal direction of the inner channel.
According to a further embodiment of the present invention, a closure wall is provided in the outer channel between the two, outwardly extending pipe portions of each U-shaped channel portion, said closure wall advantageously having a conical shape. Such a conical shape enables a strength connection and permits a movement of the inner channel in relation to the outer channel due to temperature differences.
According to a further embodiment of the present invention, the inner channel and the outer channel are separated by a wall comprising an outer wall element and an inner wall element. Since the outer channel is arranged to convey the second fluid at pressure which is higher than the pressure of the inner channel, the outer wall element may advantageously be arranged to absorb the pressure difference existing between the inner channel and the outer channel. Furthermore, the inner wall element may be arranged to form a protective layer against the fluid in the inner channel and a heat-insulating layer may be provided between the inner and the outer wall elements. In order to avoid thermal tensions, the inner wall element may thereby be connected to the outer wall element by means of a connection permitting movements of the inner wall element in relation to the outer wall element.
According to a further embodiment of the present invention, at least a second valve is provided to enable the interception of a flow through the inner channel. Furthermore, at least a third valve may be arranged to open a connection between the outer channel and the inner channel and provided upstream of said first valves in the outer channel and downstream of said second valve in the inner channel.
According to a further embodiment of the present invention, at least one of said first valves comprises a valve disc which is rotatably journalled in said intermediate pipe portion by means of a first and a second shaft pin. By the first pin being fixedly attached to the valve disc and the second shaft pin being loosely attached to the valve disc, the mounting of the valve disc in the intermediate pipe portion is possible without the need of any axial partition plane and at the same time the valve disc may be designed in a favourable manner for the flow. Thereby, the first shaft pin and the valve disc may be manufactured in one piece and the valve disc may comprise a recess in which the second shaft pin is insertable.
According to a further embodiment of the present invention, at least one of said first and second valves comprises two valve discs provided one after the other and each comprising a depression, each depression being arranged to engage the depression of the other valve disc when the valve discs are located in their open positions. By such depressions, it is possible to reduce the flow resistance emanating from the valve discs.
REFERENCES:
patent: 4715581 (1987-12-01), Myers
patent: 4860535 (1989-08-01), MÅnsson et al.
patent: 5694762 (1997-12-01), Wada
patent: 0721062 (1996-07-01), None
patent: 2520833 (1983-08-01), None
patent: 456757 (1988-10-01), None
Kallberg Lars
Schliephacke Frank
ABB Stal AB
Fox John
Pollock, Vande Sande & Amernick RLLP
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