| 摘要 |
PURPOSE:To enable fuel of gas turbine to be switched in a short time, by a method wherein a switch valve is controlled by means of a control valve opening instruction having a different value according to properties of two types of gas fuel, and the secondary pressure of a fuel control valve is balanced with a pressure in a burner. CONSTITUTION:Since the heating value of LNG is different form that of LPG, a minimum fuel instruction signal 16 is sent to gain converters 40 and 41, and thereafter, it is sent to each of fuel valve position control circuits 18-1 and 18-2 . The constant of the gain converter 42 takes the form of the characteristic ratio of each fuel, and during switching, the sum of input signals is equal to the out put signal of a low value preference circuit l7. The secondary side of a fuel control valve 15-2 is brought to a negative pressure as against a pressure in a burner 4 thanks to a spray effect. Thus, a differential pressure detector 45 detects a differential pressure between a secondary pressure and a discharge pressure, and generates bias until the difference enables feed of the fuel to a burner. This permits the one fuel system to be switched to the other in a short time. |
