Abu Dhabi Gas Liquefaction Company Ltd Job Training Mechanical Technician Course Module 9 Compressors
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- 5.1.4 Casing Splits
- Figure 5.13 . The compressor shown in Figure 5.8
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Process Stage
Third Process Stage Side-stream suction nozzle Side-stream discharge nozzle Personnel & Training Division Job Training—Mechanical Technician Compressors/Rev. 0.0 Page 53 of 90 5.1.4 Casing Splits Centrifugal compressor casings may be split: • axially (horizontally)—compressors are usually installed with the rotor axis horizontal • radially (vertically)—with barrel-type casing for higher pressures Horizontally-split compressors allow the internal parts to be reached easily without disturbing them too much. Figure 5.11 shows an exploded drawing of a horizontally-split compressor. The impeller shaft assembly (the rotor) can be removed in one piece for inspection or dismantling. You disturb something by moving it in a way that might affect its normal operation. Figure 5.11: Horizontally (or Axially) Split Casing Upper casing Lower casing Suction and discharge nozzles Split diaphragm Rotor Personnel & Training Division Job Training—Mechanical Technician Compressors/Rev. 0.0 Page 54 of 90 Split bearings and split diaphragms can be used in a horizontally-split casing. Also it is easier to check running clearances with the upper casing removed and the rotor in place. Figure 5.12 shows the rotor sitting in the lower casing. You can see the many large-diameter studs that keep the casing halves together. Most centrifugal compressors on the ADGAS plant are horizontally split. A horizontal split limits the maximum pressure inside the compressor. The gas pressure acting radially outwards pushes the two casing halves apart and this can cause pressure leaks at the joint. Vertically-split barrel casings can take higher internal pressures. A barrel casing is cylindrical, like an oil barrel, with end covers. It has no joint that can be forced apart by radial pressure. Axial pressure acts on the end covers but the axial force is not as great because the area of an end-cover is quite small. Figure 5.12: Horizontally-split Compressor with Upper Casing Removed Personnel & Training Division Job Training—Mechanical Technician Compressors/Rev. 0.0 Page 55 of 90 The barrel contains the rotor and diaphragms, which together are sometimes called the bundle. An exploded drawing of a barrel-type compressor is shown in Figure 5.13. The compressor shown in Figure 5.8 is a barrel-type with separate diaphragm sections for each stage. Figure 5.14 shows lower diaphragm halves with diffuser vanes. Figure 5.14: Lower Diaphragm Halves Barrel casing Upper diaphragm halves End cover Rotor assembly Lower diaphragm halves Download 0.5 Mb. Do'stlaringiz bilan baham: 
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