Abstract: A gravity feed, natural circulation boiler for an SAGD process using low quality feedwater for carbonatious material recovery, has a large diameter steam drum with downcomers. A furnace of the boiler has individually replaceable membrane wall modules, each with upper and lower headers and membrane roof, wall and floor parts connected to the drum and defining a fire box having an inlet end and an outlet end. The furnace includes a membrane front wall connected to the drum with a windbox upstream of the front wall. Burners at the inlet end of the firebox heat the firebox and riser pipes are connected between the steam drum and the upper header for supplying steam to the steam drum when the firebox in heated, the downcomer pipes being connected to the lower header for supplying water from the stream drum under gravity feed so that each module defines a single circuit.

Abstract: The invention relates to a continuous steam generator provided, in a duct for hot gas circulating in a substantially horizontal direction, with a continuous heating surface of an evaporator comprising a plurality of steam generator tubes which are mounted in parallel for circulating a fluid flow. The inventive device requires exceptionally low construction expenditures and ensures a high degree of safety and a high efficiency. For this purpose, the continuous heating surface of the evaporator is characterized in that it comprises a segment of the heating surface through which a moving fluid flows in an opposite direction with respect to the heated gas direction is positioned in such a way that a saturated steam temperature which is adjusted during operation at the exit from the continuous heating surface deviates from the predetermined maximum value of the temperature of the gas prevailing during operation at the outlet of the segment of the heating surface.

Abstract: The invention relates to a steam generator comprising a heating gas channel, which can be traversed in an approximately horizontal heating gas direction and in which at least one continuous heating surface is located, configured from a number of approximately vertical evaporator tubes, connected in parallel to allow the passage of a flow medium. The aim of the invention is to provide a method for starting a generator, which guarantees a high degree of operational safety, even for a steam generator with a particularly simple construction. According to the invention, to achieve this, at least several evaporator tubes are partially filled to a predeterminable desired level with unevaporated flow medium, prior to the impingement of the heating gas channel by a heating gas.

Abstract: A heat source and an element to be heated are immersed in a common liquid heat exchange medium. Baffles are arranged to guide the heated portion of the liquid upward and toward the heated element and guide the cooled portion of the liquid downward and toward the heat source in such a manner as to avoid conflict between the two flows to maximize the heat exchange between the source and element.