Once Through Steam Generators

BIH have developed a Once Through Steam Generation (OTSG) solution in which high pressure, high purity steam is generated from the turbine exhaust gases and despatched to a steam turbine.

OTSGs are lighter and more compact than conventional HRSGs and are a drumless solution that is perfectly suited to the constraints of offshore installation. Without the thermal mass of the steam drum the start-up and shut-down times are much shorter compared with those of drum-based HRSGs and therefore more suited to the frequent cycling that may be encountered in offshore applications.

Further advantages include:

• Integral exhaust gas bypass system enables greater capacity control and increases operating flexibility
• Possibility to design with multiple pressure levels and/or utility heating
• Vertical exhaust gas flow arrangement reducing the footprint of the unit
• OTSGs are essentially maintenance free with operating runtimes dictated by Gas Turbine maintenance schedules
• Shorter construction time due to modular design and no need for interconnecting boiler piping
• BIH has developed designs to overcome known issues around flow stability

OTSGs can be offered for onshore applications but the more stringent water quality needed compared to drum-based HRSGs mean that they are better suited for heat recovery where higher steam parameters and reduced footprint is required.