POWER-GEN Asia 2018

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High Precision Tops-Off Turbine Alignment Based on 3D Measurements and FE Analysis (Room Garuda 10B, 1st Floor)

During periodical inspection in a steam turbine with the replacement of its sealing components，it is very important to precisely grasp the amount of deformation of the turbine casings in order to maintain the proper clearance. In general，turbine’s alignment change is measured directly by temporarily assembling the whole component completely，even though it requires a certain term of work days. On the contrary，we are developing the technique to shorten the requisite time for the completion of the turbine by utilizing the 3D laser measured value of the disassembled casing shape and the non-linear analysis of the casing deformation for the prediction of the adjustment values. Hereinafter we introduce a brief summary. Prior to the inspection, FEM data base (DB) is prepared. Creep analysis and the following displacement analysis including the bolt tightening of the upper and lower casings are conducted for many different boundary conditions. For the composition of a DB, the variation levels among the actual turbines are separately grasped from the comparison results with the measured values using the conventional method. During the tops-off alignment at the site, the casing deformation data required in the evaluation of the alignment values are measured using 3D laser. The measured data are then compared with the DB data, interpolated, and finally adjustment values for the alignment are evaluated. By doing this, fast evaluation on site and highly accurate prediction are made compatible. We also are developing the new method which calculates the adjustment values without a prior analysis utilizing the newly developing quick FEM solver with the model directly applied the measured shape values on site. We are aiming for realizing the alignment method with low cost, high speed and high precision in a versatile manner.