GB675484A - Improvements in and relating to the stator cooling of gas turbines - Google Patents

Abstract

675,484. Gas turbine plant. ENGLISH ELECTRIC CO., Ltd. Feb. 3, 1950 [Feb. 10, 1949], No. 3675/49. Class 110(iii) [Also in Group XXVIII] In a gas turbine plant having stator walls made of a metal of low heat resistance, parts of the walls are screened from the high velocity high temperature combustion gases by screens of sheet metal of high heat resistance and are provided with tubular cooling ducts. The outer casing 12a and inner casing 12b forming a partition between the compressor and the turbine are shielded by screens 112a, 112, made of a more heat resistant material than the casings themselves. The casing 12b is covered on one side with a layer of heat insulating material 74 and on the other by a guide baffle 112d which forms with the casing a passage for cooling air for the bearing 8. The space between the material 74 and the screen 112 may be filled with stagnant air or used as a passage for a stream of cooling air. The casing 12a has two lateral rectangular inlets 12c, Fig. 3, for the combustion products. Each inlet is provided with a flanged sleeve 112c of heat resistant alloy and is lagged at 74b. The space between the outer surface of the cylindrical screen 112a and the lagging 74a is connected to the diffuser chamber 70, Fig. 1, through openings 72. Another screen 113 protects the ring member 80 supporting the first row of stator blades from the effect of the hot gases. The compressor diffuser chamber 70 communicates with a number of ducts 104 arranged parallel to the turbine axis between the inlets 12c. Diametrically opposite ducts 104 communicate with an annular space 113c and with an annular space 80b surrounding an annular member 80a. From the space 80a cooling air passes through helical grooves 17 surrounding ring members 80, 81, 82 and 83 and prevents heat being transmitted from the stator blades to the casing. This. air may pass into the main gas stream at various stages of the turbine. The walls 12d of the inlets 12c are provided with a. number of cooling air ducts 103. The ducts 103 in the walls 12d parallel to the axis of the turbine are connected direct to the ducts 104 in the casing 12a. The ducts 103 in the wall 12d perpendicular to the axis of the turbine facing the casing 12b are in direct communication with the diffuser chamber 70 through ducts in the casing 12a parallel to the ducts 104. The ducts 103 in the remaining wall 12d are connected to the annular space 113a which is in turn connected to the ducts 104 arranged in the plane of the turbine axis at right angles to, the plane of symmetry through the two inlet conduits 12c containing the axis. The cooling air leaving the ducts 103 passes into recesses 52a, Fig. 4, provided in the flanges of elbows 52 leading the combustion products into the turbine. These recesses 52a communicate with shallow grooves 52b formed on the outer surface of the elbows which are closed by strips 52c. The cooling air leaving the grooves 52b enters the main gas stream. Each elbow also has a pressure relieved heat-resistant screen 52d an internal lagging 74d. Specification 634,554 is referred to.