A mixed-pressure waste-heat boiler (7) has a forced-flow steam generator, essentially composed of a low-pressure economizer (15), of a low-pressure drum (17) and of a low-pressure evaporator (16), and a once-through forced-flow steam generator, essentially composed of a high-pressure economizer...http://www.google.fr/patents/US5765509?utm_source=gb-gplus-shareBrevet US5765509 - Combination plant with multi-pressure boiler
