SUPERCHARGED STEAM TURBINE SYSTEMS
FOR INDUSTRIAL HEAT AND POWER

 

The innovation involves a new type of combined steam and gas turbine installation (combined cycle). Current combined cycle installations take a relatively long time to start and can barely operate on (rapidly) changing speeds, let alone give torque to the load when it is standing still. Because of these load characteristics combined cycle installations are very successfully employed in base-load power generation, but not in mechanical drives and maritime propulsion. The innovation involves a combined steam and gas turbine installation that returns all shaft power by means of one free power turbine . This means that this combined cycle installation is going to be able to operate at rapidly changing speeds, and give torque when the load is standing still. For a combined cycle, this is unique. With this new technology, it is going to be possible to employ combined cycle installations in applications, where they could not have been employed before: mechanical drives and maritime propulsion. Also, the RCG will offer very high flexibility in combined heat and power (CHP) applications. The invention is called Rankine Compression Gas turbine (RCG).The novelty of the RCG compared to existing combined cycles is, that the steam turbine (ST) drives the compressor (C) of the Gas turbine cycle (Brayton cycle). Hence the name of the Rankine Compression Gas turbine: the compressor of the gas turbine cycle is powered by the steam turbine cycle (Rankine cycle). Otherwise, the RCG comprises the same components as the existing combined cycles. Because the turbine (PT) acts as a free power turbine, it will be able to drive a generator, but also other loads, such as a pump or compressor (mechanical drive applications). To be able start the installation, an auxiliary burner (A) is fitted on the steam generator.

REALIZED SO FAR
Because the RCG is assembled from off-the-shelve components (proven technology), reliability will not be an issue. A prototype (500kW thermal power) has been built, to gain experience with the combination of components and to develop an operating strategy. This was done at the University of Technology Eindhoven (the Netherlands), in the lab of the division Thermal Fluids Engineering (faculty Mechanical Engineering). The results show that an RCG-system is well controllable and can be started within minutes. This is very fast for a combined cycle, and is believed to be acceptable for industrial and maritime applications. With this prototype-skid, Heat Power was able to demonstrate the start-up procedure of the RCG, and how it responds to load-changes. Also the dynamical and start-up behaviour will be further optimized with this prototype. Currently next steps are being undertaken for the realization of a full scale industrial pilot.