Steam turbine thrust support joint bearing related introduction

The steam turbine thrust support introduced 2019 - related joint bearing 01 - 24 main effect is to bear the thrust bearing of turbo-generator set steam turbine rotor axial thrust in the running, maintaining turbine normal axial clearance between rotor and stationary parts, thus the normal work of the thrust bearing is one of the key parts in a safe and economic operation of the steam turbine unit. Thrust bearing segment temperature is an important parameter in the running state of thrust bearing, the resulting tile temperature exceeds bid, sharply wear damage, rotor axial displacement happens, make steam turbine throughflow part of dynamic and static parts to touch the ground accident. Although large steam turbine with high pressure cylinders right arrangement and low pressure cylinder with bypass type and other measures to reduce the axial thrust, but the axial thrust is very big still. When conditions change, diaphragm seal wear gap, especially the water shock, load rejection, will produce instantaneous axial thrust spurt and reverse thrust, so as to put forward further requirements of thrust bearing. Thrust bearing is widely used in close, thrust bearing, the bearing on the thrust plate is equipped with several pieces of thrust segment, segment can be fixed ( For small units) And the swing, Used in large and medium-sized units) 。 Thrust bearing support and thrust bearing one said -- joint bearing. As shown in figure 1 and figure 2, this kind of bearing structure in domestic unit used more widely. In order to ensure the axial thrust is evenly distributed to each segment, using spherical bearing bearing. Bearing radial position by bearing shell cylindrical block and gasket to adjust the axial position adjustment by adjusting ring 1, see figure 1. Support joint thrust bearing units can shorten the axial length, but the spherical bearing with spherical spherical surface processing between the larger workload. Bearing thrust segment is divided into tiles 2 work and non-work tiles 3, there are about ten pieces of each. Positive thrust tile work under the rotor, non-working tiles under possible reverse thrust under partial load. Tiles using pin hanging on the back of its disciplinary half installed ring 10. Pin and holes in tiles for a loose fit, tiles have a bump on the back rib, the tile can turn around the ribs slightly, so that the tiles 2 forms a wedge between the thrust plate 7 and clearance, liquid friction is established. To reduce the thrust disc friction loss in the lubricating oil, oil seal to prevent the lubricating oil into the thrust in bronze plate in the outer chamber. Oil block 11 used to prevent leakage of lubricating oil and to prevent the steam leakage. A support at the bottom of the thrust bearing before spring 8's thrust bearing of the cantilever support weight, to make the support bearing part of the uniform stress in shaft neck length. Lubricating oil from the support bearing tile adjusting shim under the center hole is introduced into, after bearing ring room, all the way along the split into the bearing support, one after the oil hole A and B, respectively, to work on either side of the thrust plate of tiles and non-working tiles. Last two road oil respectively by the drainage hole C and D flow back to the tank on the drainage hole D equipped with needle valve to adjust the volume of lubricating oil. One, the working principle of the thrust bearing thrust segment of oil film forming principle and the oil film between two flat forming principle is the same. Steam turbine static, thrust tile surface parallel to the thrust plate surface, as shown in figure 3 ( 一) Shown below. When steam turbine rotational, thrust dribble the oil into the gap, when the rotor axial force, gap medium oil film pressure, passed to the segment, initially hydraulic force Q no effect in tile supporting shoulder, but a slant on the inlet side, as shown in figure 3 ( b） Shown below. Resultant force formed between Q and supporting shoulder a couple, make tile deflection, forming oil film. With the deflection of tile, hydraulic force Q to move oil outlet side, when Q force moved to support shoulders, tile to maintain equilibrium position, oil pressure and thrust in oil wedge plate axial thrust balance state, as shown in figure 3 ( c) Shown below. Formed between thrust disc and thrust tile liquid friction. Second, analysis of the causes of excess temperature of thrust bearing in the operation of the unit due to vibration, and uneven expansion of the improper operation, the gland, vapor barrier caused by wear and make clearance increases the interstage leakage caused by increased, roulette and gland increases convex shoulder under axial thrust, thrust tile for more than capable of withstanding thrust, thrust tile temperature will rise. So the operation personnel should strictly in accordance with procedures, to ensure the cylinder flange heating when the temperature difference between the upper and lower cylinder expansion of the rotor and cylinder is poor, and the vibration value within the range of criteria. In installation and maintenance, to ensure the seal, vapor barrier flow portion of the gap and meet quality standards. In the operation of the salt deposit due to the blades, the steam flow through the diaphragm and the pressure drop increase of the blade, blade also will increase the reactionary degree, acting on the rotor wheel increases, the axial thrust on the blades, thrust segment under thrust is greater than the design value, thrust segment temperature sharply increases. This situation can be determine by monitoring period of pressure change, the monitoring period of pressure on the high side, monitoring period of pressure change is generally not more than 15%, such as greater than 15% when should stop processing. Blade scaling serious when, can pass down load using warm water wash. At the same time to enhance the quality control of the chemical in addition to salt water. Lower vacuum of unit and the rotor blade in and out of the side wear, can make the axial thrust on the rotor, causing thrust segment of elevated temperature sharply. When vacuum to reduce the exhaust temperature of cylinder rotor reaction function of the last stage blade increases, the axial thrust increases. Therefore enhancing the vacuum can reduce thrust segment temperature sharply.