JPS57203805A - Overload steam inflow structure in steam turbine - Google Patents

Abstract

PURPOSE:To reduce thermal energy loss of steam, by letting overload steam flow in a casing through a steam passage connecting a loop space between an external and an internal casings and a casing, in a steam turbine having dual casing structure. CONSTITUTION:An overload steam inflow part in a barrel type steam turbine possesses an external and an internal casings 1 and 2 which are provided concentrically with an appropriate loop space 3 between them, five main steam chambers 8 are formed inside the inner casing 2 by dividing it into six parts in its circular direction, into which main steam is flowed through a main steam inflow passage 24. In this case, an overload steam inflow passage 40 is provided on the external casing 1 and an overload steam inflow passage 40 is connected by welding with the tip of the inflow passage 40. On the other hand, an overload steam receiving part 52 which will be covered by a thermal insulator made of a metal plate is provided in the internal casing by machining the external circumferential surface confronting with the above inflow duct 40, through which introduction of the overload steam into a casing 12 through steam passage 18 is made possible.