Method and apparatus for controlled-temperature valve mode transfers in a steam turbine
US4177387A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 6, 1978 |
| Grant date | Dec 4, 1979 |
| Priority date | — |
| Expiry date | Jan 6, 1998 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF01D17/18
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
An electrohydraulic control system and method are disclosed for operating valves controlling the admission of steam to a steam turbine. The system includes a mode transfer unit for effecting a transfer between a full arc mode of valve operation to a partial arc mode of operation such that the temperature of the steam turbine varies in a controlled manner, thus permitting control of turbine stresses. Apparatus is described for generating mode flow signals, combining the signals using time ratio switching such that during a mode transfer the signals vary linearly with an admission reference factor characteristic of each mode, and generating valve lift signals from a combined flow signal using multi-slope, piecewise linear approximations to the flow-lift characteristics of the full arc mode of valve operation. The system permits mode transfers wherein total steam flow is held substantially constant and first stage turbine temperature is caused to vary linearly with admission reference factor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.