google_ad_height = 90; The active direction can change when the turbo compressor has a balance drum or is an opposed design. If the IP dummy ring is severely distorted, it is possible for the IP dummy leakage to be a mix of HP dummy leakage and HP exhaust steam flowing in the reverse direction through the equilibrium pipes. The results of temperature split testing were inconclusive due to the swings in leakage. Reducing excessive internal leakage in Westinghouse and Allis-Chalmers turbines may require taking any or all of the following steps: 7. Sometimes, a equilibrium pipe can be eroded by a broken bell seal steam jet. However, a pre-outage test had not been conducted. In this extreme case, a bad bell seal was determined to be the cause of excessive leakage that raised the unit’s heat rate. Southern Company Generation (SCG) has found that trending of the apparent IP efficiency using the Booth-Kautzmann temperature split tests (discussed last issue in Part I) is very useful for resolving internal leakage problems on our Westinghouse and Allis-Chalmers turbines.

The output of the probes is noted on the monitor as either + (normal) or – (counter). Answer: In a radial-flow turbine, steam flows outward from the shaft to the casing. IP1 efficiency values account for the effect of leakage of HP exhaust steam leakage to the IP1 inlet through the IP dummy seals. If this is the case, a balance drum must be mounted on the rotor.

if(MSFPhover) { MSFPnav3n=MSFPpreload("../Power Plant Dictionary/_derived/PowerEngineeringDictionaryTable.htm_cmp_strtedge110_vbtn.gif"); MSFPnav3h=MSFPpreload("../Power Plant Dictionary/_derived/PowerEngineeringDictionaryTable.htm_cmp_strtedge110_vbtn_a.gif"); } The unit experienced some thrust balance problems after start-up that may have contributed to the higher leakage. Design and nondesign leakage areas on the lower inner shell of a Westinghouse BB44. Courtesy: Southern Company Generation. In Westinghouse BB44s that are routinely found to have cracked bell seals, distorted inlet sleeves could be the problem (a consequence of age); the manufacturer offers a method for straightening the inlet sleeve that SCG has used successfully. Recent testing indicated that the IP dummy leakage rate (4.4%) and total leakage level (7.0%), though not quite as good as the 1999 results, are overwhelmingly better than those found by the 1993 tests. Depending on the unit design, HP dummy seal leakage can affect HP turbine efficiency as it flows through the equilibrium pipes to the HP exhaust. Answer:  All multistage turbines, low-pressure turbines, and turbines operating at high pressure with saturated steam should have a moisture separator in order to prevent rapid blade wear from water erosion. Some piston seal ring designs (Figure 8) can produce excessive leakage if installed improperly, upside-down (one side is flat, and the other has alternating high and low sides). That’s because the former units require balancing the thrust loading of the reaction blading. One-way street.

Size matters. Collars on the rotor face these thrust pads, and the journal is supported in the bearing between the thrust collars. // -->