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 © 2013 by ASME

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

© 2016 Author(s). 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. The use of these biomass resources is beneficial to maximise annual renewable energy generation, substitute natural gas, and use locally/seasonally available biomass resources that may not be used otherwise. Even small biomass quantities of only 50,000 t/a can increase the capacity factor of a 50MWe parabolic trough plant with 7h thermal energy storage from 40 to 49%. This is a valuable increase and such a concept is suitable for new plants and retrofit applications. However, similar to the capacity optimisation of back-up heaters, various design criteria have to be considered to ensure a successful project

Concentrated solar power hybrid plants, which technologies are best suited for hybridisation?

This assessment aims to identify the most suitable concentrated solar power (CSP) technologies to hybridize with Rankine cycle power plants using conventional fuels, such as gas and coal, as well as non-conventional fuels, namely biomass and waste materials. The results derive from quantitative data, such as literature, industry information and own calculations, as well as qualitative data from an expert workshop. To incorporate the variety of technology criteria, quantitative and qualitative data the Analytical Hierarchy Process (AHP) is used as the multi-criteria decision making (MCDM) tool. Only CSP technologies able to directly or indirectly generate steam are compared in regards to feasibility, risk, environmental impact and Levelised Cost of Electricity (LCOE). Different sub-criteria are chosen to consider the most relevant aspects. The study focuses on the suitability of CSP technologies for hybridisation and results obtained are reality checked by comparison with plants already being built/under construction. The results of this assessment are time dependant and may change with new CSP technologies maturing and prices decreasing in the future.Key findings of this assessment show that Fresnel systems seem to be the best technology for feedwater preheating, cold reheat steam and <450 °C steam boost applications. Parabolic troughs using thermal oil rank second for all CSP integration scenarios with steam temperatures <380 °C. Generally, for steam temperatures above 450 °C the solar towers with direct steam generation score higher than solar towers using molten salt and the big dish technology. At and above 580 °C the big dish is the only alternative to directly provide high pressure steam.In addition to a general CSP technology selection for hybridisation the framework of this study could be used to identify the most suitable CSP technology for a specific CSP hybrid project but this requires detailed information for direct normal irradiance, climate conditions, space constraints etc to provide reliable results. © 2013 Elsevier Ltd

Hybrid concentrated solar biomass (HCSB) plant for electricity generation in Australia: Design and evaluation of techno-economic and environmental performance

Cost-efficient dispatchable renewable technologies are critical for enabling the energy transition towards 100% renewable generation. One promising example involves the integration of biomass boilers with concentrated solar power (CSP) referred to as hybrid concentrated solar biomass (HCSB) plants. This study evaluates the technical feasibility of a potential plant design for a rice-straw-fed HCSB plant. A case study for the Riverina-Murray region of Australia, a prime area for deployment owing to abundant solar and biomass resources is presented. Based on an assessment of different hybrid concepts, we investigate a solar-biomass hybridization with a concentrated solar tower system. With this hybrid concept, both the CSP and biomass boiler can raise steam to feed the high-pressure turbine enabling greater thermal efficiency. We evaluate HCSB plant performance at four scales: 5, 15, 30 and 50 MWe. Depending on size, HCSB plants reach thermal efficiencies from 21 to 34%. Considering the economic feasibility, assuming an internal rate of return (IRR) of 11%, viable deployment requires an electricity price of AU$ 120–350/MWh. The techno-economic assessment demonstrates advantages compared to standalone CSP plants and highlights the competitiveness of HCSB plants compared to other renewable technologies in Australia. The social and environmental impact assessment highlights additional benefits including local job creation and potential carbon emission mitigation