EXTRACTION PRESSURE CONTROLLING SYSTEM FOR EXTRACTION TURBINE

摘要

PURPOSE:To make the bleeding structure of an extraction turbine compact, by controlling the extraction pressure through selection from at least either one of a fixed extraction-pressure controlling range, extraction-pressure increasing variable- pressure operational range or extraction-pressure reducing variable-pressure operational range. CONSTITUTION:A portion B of steam A, passed through final-stage rotor blades 11 of high-pressure turbine 1, is extracted from bleeding port 8. Here, in case that extraction-pressure controlling valve 4 is fully closed, remaining steam is made to flow directly into extraction-pressure controlling nozzle 12 and then to low-pressure turbine 2. Here, extraction pressure of the turbine is controlled through selection from at least either one of a fixed extraction-pressure controlling range selected to involve the middle section in respect of the quantity of steam introduced into low- pressure turbine, an extraction-pressure increasing variable-pressure operational range selected in the section higher than the upper limit of the said fixed control range, or an extraction-pressure reducing variable-pressure operational range selected in the section lower than the lower limit of the said fixed control range.