Udo Hellwig

Integrated Solar Combined Cycle Plants Using Solar Towers With Thermal Storage to Increase Plant Performance

In Australia both natural gas and an excellent solar irradiance are abundant energy sources and its combination is one option to implement concentrating solar power (CSP) systems in Australia’s traditionally low cost electricity market. The recently introduced carbon pricing mechanism in Australia is likely to steer investment towards combined cycle gas turbine (CCGT) plants. This will also lead to further plants being built in high solar irradiance areas where CSP could provide valuable peak capacity. Hybridisation would enable more competitive power generation than standalone CSP systems as hybrid plants share equipment, such as steam turbine and condenser, therewith lowering the specific investment.This paper investigates the novel hybridization of CCGT and solar tower systems to increase the efficiency of integrated solar combined cycle (ISCC). Currently, all ISCC plants use parabolic trough systems with thermal oil as this technology is most mature. However, increases in plant efficiency, simpler solar tower integration as well as further synergies of solar tower ISCC systems, such as joint use of tower as CCGT stack, are likely to enhance the economic viability of new ISCC plants. In addition to a technical concept description this paper outlines the ideal sites for ISCC plants in Australia and presents a 200MWe ISCC case study with 3h molten salt thermal storage for the conversion of the Port Hedland open cycle gas turbine (OCGT) facility in Western Australia into a solar tower ISCC plant.Copyright

Parallel Flow Boiler Designs to Minimise Erosion and Corrosion From Dust Loaded Flue Gases

Improving power plant performance, availability and operational costs is crucial to remain competitive in today’s competitive energy market. The boiler is a key component to achieve these objectives, particularly so when using challenging fuels, such as municipal solid waste or exhaust gases with high dust contents.This paper describes an innovative boiler design that has been used for the first time in an Energy from Waste plant in Bamberg, Germany. The new boiler design disregards the traditional heating surface arrangement and instead uses tube bundles arranged in parallel to the gas flow, which provides several advantages, such as reduced fouling. The paper describes the Bamberg project (boiler design and project highlights) and first operational results after 30,500h of operation.Additionally, the paper investigates further options to reduce fouling through the use of dimpled tubes, especially the ip tube® technology. The technology is presented as well as first test results of such tubes in the Energy from Waste plant Rosenheim, Germany.The paper concludes with further applications for the parallel flow boiler design, such as cement kilns, to outline future markets.Copyright

Novel solar tower structure to lower plant cost and construction risk

In recent times the interest in solar tower power plants is increasing with various plants being built in the last years and currently under construction, e.g. Ivanpah and Crescent Dunes in the US and Khi Solar One in South Africa. The higher cycle efficiency leads to lower levelised cost of electricity. However, further cost reductions are required and this paper compares a novel and patented solar tower structure with a conventional concrete tower. The novel solar tower design is cable-stayed which has the benefit that the cables absorb a large part of the wind and buckling loads. A tower that has to cope with fewer wind and buckling forces can have a significantly smaller diameter than a concrete tower, which enables workshop manufacture, sea and road transport, and rapid on-site installation. The case study provided in this paper finds that the tower area affected by wind can be reduced by up to 45%, installation time shortened by up to 66%, and tower cost by 20-40%. The novel design allows the constr...

Large capacity, multi-fuel, and high temperature working fluid heaters to optimize CSP plant cost, complexity and annual generation

This paper analyses the potential to optimize high temperature fluid back-up systems for concentrating solar power (CSP) plants by investigating the cost impact of component capacity and the impact of using multiple fuels on annual generation. Until now back-up heaters have been limited to 20MWth capacity but larger units have been realised in other industries. Installing larger units yields economy-of-scale benefits through improved manufacturing, optimised transport, and minimized on-site installation work. Halving the number of back-up boilers can yield cost reduction of 23% while minimizing plant complexity and on-site construction risk. However, to achieve these benefits it is important to adapt the back-up heaters to the plant’s requirements (load change, capacity, minimum load, etc.) and design for manufacture, transport and assembly.Despite the fact that biomass availability is decreasing with increasing direct normal irradiance (DNI), some biomass is available in areas suitable for CSP plants. Th...