Abstract: Disclosed is a control system for a centrifugal thin film dryer wherein a slurry including solid matter is fed to a tubular heating surface and the a slurry is heated while blades are rotating inside the heating tube so that the a slurry turns into dry powder, the system comprising a plurality of thermal sensors located on the heating surface, a dry-up point calculator which measures the temperature distribution along the heating surface in accordance with the signals provided by the thermal sensors and calculates the point at which the temperature rise begins to saturate, a flow rate setting device which calculates the quantity of a slurry to be supplied in accordance with the output of the dry-up point calculator, and a flow rate regulator which controls a pump in accordance with the signal provided by the flow rate setting device.

Abstract: A fuel cell power generation system in which the temperature of fuel cells is held constant irrespective of the load level of the cells, and waste energy is effectively recovered, that is, heat generated by fuel cells or a hydrogen producing device is temporarily stored, thereby to absorb the fluctuations of generated heat attendant upon the load fluctuation of the fuel cells and also to generate steam required in the hydrogen producing device by the use of the stored heat. When the heat generated by the cells is little as in a low load operation or a stand-by state, the stored heat is used for heating so as to allow power to be generated immediately upon a load demand.

Abstract: A radioactivity monitoring system capable of exactly detecting the concentration of .sup.131 I in a gas even in a low concentration is disclosed in which a sample gas is passed through a filter cartridge filled with an iodine absorbing material to accumulate iodine, radiation is counted on both entrance and exit sides of the filter cartridge, the absorption distribution of iodine absorbed in the filter cartridge is estimated from the ratio between respective counts obtained on the entrance and exit sides, and one of the counts is corrected by the estimated absorption distribution of iodine to calculate the radioactivity concentration of .sup.131 I in the gas.