The present invention relates to a boiler with a packaged heat exchanger in which a heating passage and a cooling passage are packaged to generate superheated steam through heat exchange by exhaust gas and to adjust the temperature of the superheated steam to a suitable level for the use through heat exchange with air.

A device and method for generating electrical energy from hydrogen and oxygen, includes a combustion engine, a heat recovery steam generator connected into the exhaust gas duct of the combustion engine, wherein the heat recovery steam generator has only one pressure stage. An H.sub.2O.sub.2 reactor is provided to which steam from the heat recovery steam generator, water, oxygen and hydrogen are fed, such that, in the H.sub.2O.sub.2 reactor, a reaction of oxygen and hydrogen forms steam, the water that is introduced is evaporated, additional steam is generated, the resultant superheated steam is fed to a steam turbine, and a generator connected to the steam turbine provides an electric power. High-pressure feed water is injected from the heat recovery steam generator into the H.sub.2O.sub.2 reactor via a line to control the reaction in the H.sub.2O.sub.2 reactor in a targeted manner and set the steam exit temperature from the H.sub.2O.sub.2 reactor.