Fluid handling – With heating or cooling of the system – Circulating fluid in heat exchange relationship
Patent
1998-04-02
1999-10-26
Chambers, A. Michael
Fluid handling
With heating or cooling of the system
Circulating fluid in heat exchange relationship
137338, 251214, F16K 3144
Patent
active
059710101
DESCRIPTION:
BRIEF SUMMARY
THE FIELD OF THE INVENTION
The present invention relates to a shaft device comprising a shaft supported by a support member and extending into a relatively warm space. The invention further relates to a method of cooling a shaft device which comprises a shaft supported by a support member and extending between a relatively warm space and a relatively cool space.
BACKGROUND OF THE INVENTION
In a pressurized bed combustion power plant, a so called PFBC-power plant, the hot combustioned gases are guided from the fluidized bed combuster through cyclones, for purification, in a hot gas channel, to a gas turbine. The shaft of the gas turbine drives a compressor, compressing the combustion air which, through an air supply channel, is supplied to the fluidized bed combuster. The hot gas channel is arranged concentrically in the air supply channel and, accordingly, the hot gas channel is surrounded by the air which is supplied to the combuster. To be able to shut off the flow of hot gas to the gas turbine, for instance in case of a gas turbine trip, a throttle valve is arranged in the proximity of the hot gas channel inlet to the gas turbine. This throttle valve is arranged on a shaft which is turnably supported by means of bearings arranged in the wall of the hot gas channel. Due to the high temperature, approximately 850.degree.-870.degree. C., existing in the hot gas channel, damages often occur on the shaft bearings, as heat is led through the shaft of the throttle valve into the bearings. This can lead to that the throttle valve does not work when the gas turbine has to a problem be quickly stopped.
SUMMARY OF THE INVENTION
The object of the present invention is, in connection with a shaft which is subjected to high temperatures, to accomplish an effective cooling of the support member which supports the shaft and may comprise temperature sensitive components, such as bearings, sealings or the like. This object is obtained by the shaft device, characterized in that channels are arranged in the border area between the shaft and the support member for cooling the support member. By means of such channels it is possible to cool the support member and to prevent heat from the warm space from being transferred into the support member via the shaft. Thus, by means of the present invention, all functions of the support member can be assured.
According to a preferred embodiment, means are arranged for generating a flow through the channels. Such means may, for instance, comprise a pump which pumps a fluid or a gas through the channels. However, these means may also comprise the mere use of a pressure difference between the inlets and outlets of the channels.
According to one embodiment the channels extend helically in relation to the longitudinal direction of the shaft. In that way, the length of the channels may be increased, and thereby also the flow resistance increases, which is important for making use of the heat absorbing ability of a medium which is led through the channels. A required cooling effect may be obtained by optimizing the patch angle of the helical channels, the number of channels and the cross sectional area of the channels.
According to another embodiment, the channels extend rectilinearly generally in the longitudinal direction of the shaft. Such a relatively simple design does not result in a cooling effect as important as for helical channels, but may be advantageous when, for instance, a cooling medium has a very low temperature.
According to a further embodiment, the channels located in the border area comprise grooves arranged on the shaft. Advantageously, a sleeve is arranged between the shaft and the support member. In that way the channels may be extended to comprise the whole length of the sleeve and are not restricted by the length of the support member, which results in a better cooling effect. Thereby, the channels will preferably be formed by the grooves in the shaft and the sleeve. Alternatively, the channels located in the border area may be formed by grooves arranged in th
REFERENCES:
patent: 3643024 (1972-02-01), La Coste et al.
patent: 4022424 (1977-05-01), Davis et al.
Sony K.K., Mikio Kudoui, Ball and Roller Bearings, Patent Abstract of Japan, vol. 7, No. 63, M-200. 57-208319 (A), Appl. No. 56-94501.
Kallberg Lars
Schliephacke Frank
ABB Carbon AB
Chambers A. Michael
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