OVERHEAT PREVENTING METHOD FOR WATER TUBE OF BOILER

摘要

PURPOSE: To prevent the overheat of a water tube corresponding to a steam pressure at the heat resistant limit temperature or lower of a water tube mate rial by forcibly driving a feed water pump via a controller when the temperature of the tube reaches an over heat preventing temperature. ;CONSTITUTION: When the set steam pressure of a boiler is set to 9kg/cm², about l80°C of the saturated temperature of boiler water is obtained. In the case of clean water tube, when combustion gas is 800°C, the water tube outside temperature is about 203°C, and the water tube inside temperature becomes 196°C. The heat resistant limit temperature of the tube 4 is set to 600°C. Overheat preventing temperature is set by adding T₁ temperature (e.g. 200°C) to the saturation temperature to the set steam pressure. When overheat occurs at the tube 14 to reach the overheat preventing temperature, a signal is informed from a temperature sensor 18 to a controller 12 via a channel 16. The controller 12 which receives the information collates the signal from the sensor 18 with the steam pressure signal from a pressure sensor 11, judges the tube overheat, and forcibly drives a feed water pump 15.;COPYRIGHT: (C)1996,JPO