A steam generator system (100) incorporates multiple processes (A-D), either in series or independently and with each process having a process fluid associated therewith, to transfer heat between a common working fluid (108) and the process fluids in order to generate steam from the working fluid. The heat transfer may be controlled by controlling (180) the flow of the working fluid (108) to further regulate and control the generation of steam and/or the individual processes (A-D) themselves. The generator system (100) includes a vessel (170) and may optionally have baffles located within the vessel to separate the flow of working fluid into a recirculation system to facilitate in the overall operation of the system. The working fluid should be capable of forming steam and preferably consists essentially of water. Straight tubes, plate-type heat exchange surfaces having a common boiling fluid stream, U-tubes, helical tubes, and/or curved tubes may be used as heat exchange means (165) for transferring heat between the working fluid and the process fluids.