Abstract: A technique for monitoring the frequency difference between pulse output signals derived from a pair of flowmeters interposed respectively in the inlet and outlet lines of a flow conduit supplying cooling water to the tuyere of a blast furnace, the frequency difference being indicative of water leakage. The furnace has a plurality of such tuyeres, each conduit of which is monitored. The pulse output signals from the flowmeters at each monitoring point are fed to a common processing unit in which there are stored the constants representing the instrumental error between each pair of flowmeters as well as their mean conversion constants. In the processing unit, computations are carried out on the basis of the pulse output signals derived from each pair of flowmeters, the instrument error constant thereof and their mean conversion constants, in order accurately to determine the flow rate difference therebetween at each monitoring point independently of the instrumental error.

Abstract: A system for monitoring the frequency difference between pulse output signals derived from a pair of flowmeters interposed, respectively, in the inlet and outlet lines of a flow conduit supplying cooling water to the tuyere of a blast furnace, the frequency difference being indicative of water leakage. The pulse output signals produced by the respective flowmeters during each predetermined measuring period are integrated. The integrated values are compared with each other, the difference therebetween being monitored whereby when the difference exceeds a predetermined set value, an alarm is generated.