| 摘要 |
PURPOSE:To smoothly control the flow rate of fuel over a wide range of flow rate of steam by a method wherein a shut-off valve and a control valve with smaller maximum flow rate, both of which are connected in parallel, are connected in series to a control valve with larger maximum flow rate. CONSTITUTION:Each of control valves 14 and 16 normally can not control the flow rate smaller than about 10% of its maximum flow rate and yet the leakage on the order of just above-mentioned flow rate can not be prevented from occurring to each valve. When the steam flow rate lowers beyond the point (a) on the abscissa indicating the steam flow rate, the control valve 16 loses its control and yet the leakage of fuel oil with the flow rate P occurs through the valve 16 and at this time the shut-off valve 13 is completely shut-off. However, because the maximum flow rate of the control valve 14 is enough smaller than that of the control valve 16, the opening of the valve 14 can be controlled under the condition that the steam flow rate is smaller than that indicated by the point (a) so as to supply the controlled fuel oil through a pipe 12 to the second nozzle 3 of a doubled burner nozzle 4. When the steam flow rate exceeds that indicated by the point (a), the control valve 16 restores its control and at the same time shut-off valve 13 is open and yet the control valve 14 is fully open, resulting in making the flow rate of fuel oil supplied through a pipe 11 to the first nozzle 2 more influential. |
