Drum Level Control in Larger Capacity Boiler
Drum Level Control in Larger Capacity Boiler In a large capacity boilers feed pump motor is not directly connected to the boiler feed pump. Between motor and feed pump a hydraulic coupling is used in which an arrangement is given for speed increasing and then regulating through the scoop tube. This provide a variable speed operation while motor is running at constant speed. With the help of scoop tube motor is started with no load and pump is running with it on a re-circulation mode. No direct mechanical connection is there between the motor and the pump shafts. The coupling consists of a radial pump impeller mounted on the motor shaft and a radial flow reaction turbine runner mounted on the pump shaft. Both the impeller and runner are identical in shape and they together form a casing which is completely enclosed and filled with oil. When motor shaft is rotated, the oil starts moving from the inner radius to ...