Abstract: A method and an apparatus are described for monitoring a rotating synchronous electric machine (9), which comprises a rotor winding and a stator having a stator winding. The method comprises the steps of determining the stator winding current, determining the stator winding voltage, determining the rotor winding current, and estimating the temperature in at least two positions in the electric machine (9) using a model of the electric machine and the determined current and voltage values. An apparatus according to the invention is provided for carrying out the method.

Abstract: The invention relates to a method in operating a lined cavern provided for the storage of gas coming from a pipeline. During filling of the cavern with gas to a nominal pressure, at least a portion of the gas is withdrawn from the cavern and recirculated to the cavern under cooling and without substantial compression. The method also includes recirculating the gas under heating and without substantial compression.

Abstract: An installation for storing of natural gas or some other fluid comprises a lined underground storage space. Inside the rock wall of the storage space, there is a concrete layer for supporting an inner impermeable lining layer. According to the invention, the concrete layer has a crack distribution control reinforcement layer closer to the impermeable lining layer than to the rock wall in order to divide large cracks in to smaller cracks and to distribute the cracks over a larger area of the impermeable lining layer. Also according to the invention, there is provided between the impermeable lining layer and the concrete layer a non-binding sliding layer to facilitate relative movements between the impermeable lining layer and the concrete layer.

Abstract: Procedure and plant for spray drying absorption of flue gases by separation of SO.sub.2. A suspension of finely-ground limestone is added to a reactor via an oxidation and acidification unit, where the finely-ground limestone is mixed with recirculated solids and air, oxygen and/or some of the flue gases. Preferably, the recirculated solids is also subjected to reactivation by wet-grinding.