Machines that expand boiler-generated steam and convert the enthalpy drop into shaft work — driving generators, pumps and compressors (class ST of ISO 14224:2016; API 611 for general purpose, API 612 for special purpose).
Usual arrangements
(handbooks per type in Phase 1)
- Condensing — expands down to condenser vacuum: maximum energy extraction per kg of steam;
- Back-pressure — discharges into a process header: cogeneration (work + useful steam);
- Extraction — controlled bleeds at intermediate pressures for the process;
- Reheat — steam returns to the boiler between stages: high-power cycles.
Reliability: moisture erosion in the last stages, deposits from silica/salt carry-over, blade fatigue and the overspeed trip system — the classic hidden function, proven only by periodic proof testing.