초록 ▼

A flow by-pass system is provided in a downward-discharging exhaust hood of a steam turbine to by-pass a small percentage of the total steam flow from the top portion of the exhaust hood to the vicinity of the condenser and in that way relieve excess pressure in the top portion incident to the more

A flow by-pass system is provided in a downward-discharging exhaust hood of a steam turbine to by-pass a small percentage of the total steam flow from the top portion of the exhaust hood to the vicinity of the condenser and in that way relieve excess pressure in the top portion incident to the more convoluted path of the main portion of steam passing from the top to the bottom and to decrease energy loss caused by friction and thus to improve turbine efficiency. The flow by-pass system includes by-pass conduits within the front portion of the exhaust hood extending from the top portion to the vicinity of the condenser. Such conduits are formed by covering over the corners between the outer and end walls of the exhaust hood and between the exhaust hood end wall and the bearing cone outside surface with by-pass walls to form flow passages in the corners behind the by-pass walls through which exhaust steam may pass from the region of higher pressure in the top portion of the exhaust hood to the region of lower pressure in vicinity of the condenser. Inlets and outlets are provided in the by-pass walls for entrance and exit of the turbine exhaust steam to the by-pass conduits.

대표청구항 ▼

1. A flow by-pass system for a downwardly discharging exhaust hood having top and bottom portions in a steam turbine installation wherein exhaust steam is normally initially directed mostly upwardly from an upper portion of an annular diffuser in the front of the top portion of the exhaust hood, the

1. A flow by-pass system for a downwardly discharging exhaust hood having top and bottom portions in a steam turbine installation wherein exhaust steam is normally initially directed mostly upwardly from an upper portion of an annular diffuser in the front of the top portion of the exhaust hood, then into the back of the top portion and downwardly on both sides of a casing of the turbine into the bottom portion of the exhaust hood from which it flows into a condenser adjacent the bottom portion, while the steam from the lower portion of the annular diffuser is directed immediately mostly downwardly to the bottom portion of the exhaust hood and into the condenser resulting in a higher pressure in the upper portion of the hood and lower pressure in the lower portion of the hood, which higher pressure in the upper portion of the hood tends to be transferred back to the turbine, the improvement comprising a by-pass conduit arranged to conduct a portion of the steam from the top, higher pressure, portion of the exhaust hood to a lower pressure zone below it by a more direct route than that followed by the normal flow of steam to decrease the build-up of pressure in the top portion of the exhaust hood which decrease causes an increase in the energy available to the turbine to do work and to decrease flow velocity in the upper portion of the hood to reduce the energy loss caused by friction and thus to increase turbine efficiency, said by-pass conduit being provided with at least two flow passages extending downwardly from the top portion of the exhaust hood on the opposite sides of the exhaust hood and wherein the by-pass conduit comprises an interior wall attached to outer and end walls of the exhaust hood to enclose a corner of the hood between the outer and end walls of said hood to convert at least portions of such corner into two enclosed flow passages.