One of the world’s largest kettle is in southern Spain. Builder is the German Centre for aviation and Astronautics (DLR). It intends to increase the steam generation with solar power on a higher level, to enable more effective power plants.
The Solar Platform in Almeria (southern Spain) is a huge Experimental station: engineers from German Centre for Aviation and Astronautics (DLR) built a 1000 m long solar system for the direct evaporation of water.
The complex consists of parabolic mirrors that directs sunlight on so-called receiver tubes. There is water, which is always hot and eventually evaporates inside. The steam further – heats up to a temperature of up to 550 ° C. This generates a pressure around 100 bar in the tube. And to what end? This superheated high pressure steam in a power plant could power a turbine for electricity generation.
Water has several advantages when compared to heat transfer oil proved World’s Largest Kettle Experiment by DLR
Parabolic trough power plants are currently the best solar power plants. In contrast to the DLR pilot plant use commercial facilities in the receiver pipes but not water, but go through a synthetic oil as a heat transfer medium. The downside: It can be himself only to temperatures below 400 ° C heat, which limited the maximum efficiency. Water as a heat transfer medium operating temperatures, however, up to 500 c of °, enabling power plants operate more efficiently settled. Unlike oil, water is also cheap, always available and not flammable or hazardous to the environment.
The DLR pilot plant promises more benefits: previous direct evaporation plants work according to the so-called re-circulation concept. While the water in the solar field traverses three areas – the evaporator area for the production of steam, the steam drum for the separation of liquid water and steam, as well as an area for further temperature increases. “Our advanced concept with forced flow is the steam for the turbine in one go through strand evaporated and overheated,” explains project leader Fabian Feldhoff.
DLR: Pilot Plant has a capacity of 3 MW
An advantage of the pass concept is the easy scalability of the collector train. Each is identical and delivers the same performance – in the case of the test facility well 3 MW are in direct sunlight. “For a large power plant you would have to build parallel simply so many strands, until the desired output is achieved”, said Feldhoff. “Just this simple design offers a high potential of savings.”
On the way to the market of direct evaporation system with water, yet long term experiences are necessary. “We plan a follow-up project, to bring the technology quickly into the market,” said Feldhoff. A major challenge in the current project was, for example, the changing sunlight. The steam drum in the old approach could well dampen the impact of passing clouds. In the new concept of continuous clouds have, however, very quickly, so always adjust the amount of water in the collector pipe the irradiation conditions.
The problem: You don’t know when a cloud where. The radiation measurement is expensive and reliable predictions are only just being developed. Largest Kettle Experiment by DLR engineers use currently still on a measurement of the temperature of the steam to the recognition of the current situation, so that regulators can adjust automatically. High heat, the temperature of the steam can be adjusted by water quickly by injecting.