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Development of a new highly efficient and fuel flexible CHP technology based on fixed-bed updraft biomass gasification and a SOFC

Periodic Reporting for period 2 - HiEff-BioPower (Development of a new highly efficient and fuel flexible CHP technology based on fixed-bed updraft biomass gasification and a SOFC)

Reporting period: 2018-04-01 to 2019-03-31

Within the project a new highly efficient biomass CHP technology for a capacity range of 1 to 10 MW (total energy output) is developed. The technology will distinguish itself by a wide fuel spectrum applicable (wood pellets, wood chips, SRC, selected agricultural fuels like agro-pellets, fruit stones/shells), high gross electric (40%) and overall (90%) efficiencies as well as equal-zero gaseous and particulate matter (PM) emissions. The system consists of a fuel-flexible updraft gasification technology with ultra-low PM and alkali metal concentrations in the product gas (which reduces the efforts for gas cleaning), an integrated high temperature gas cleaning unit (GCU) for dust, HCl and S removal and tar cracking within one process step as well as a SOFC system which tolerates certain amounts of tars as fuel. It is expected to achieve at the end of the project a TRL of 5.
To develop this CHP technology, a methodology is applied which is divided into a technology development part a technology assessment part. Technology development is based on process simulations, computer aided design of the single units and the overall system, test plant construction, performance and evaluation of test runs as well as risk and safety analysis. The technology assessment part covers techno-economic, environmental and overall impact assessments and market studies regarding the potentials for application. Moreover, a dissemination, exploitation and communication plan is developed.
In order to achieve these ambitious goals a multidisciplinary consortium consisting of a biomass conversion technology provider (VIHFA), an engineering company specialised on the development of energetic biomass conversion systems (BIOS), specialists regarding gas cleaning (KIT, CALIDA) and fuel cell technologies (IKTS, AVL) as well as partners experienced in market studies and techno-economic assessments (WIKUE, UU) has been formed. Industry (AVL, VIHFA), SMEs (BIOS, CALIDA), Universities (UU, KIT) as well as research organisations (IKTS, WIKUE) cooperate within the project consortium.
During the past 30 months of the 4-year project, the work focused (i) on the development of the overall system approach, (ii) the definition of the framework conditions and interfaces regarding the single plant units, (iii) the development, design and manufacturing of the components, (iv) the assembly of a first testing plant consisting of a 400 kW gasifier, a full stream GCU and a 6 kW SOFC system operating in a product gas side stream extracted from downstream the GCU as well as on (v) test runs with this testing plant.
As a basis for the system design two design fuels have been defined, namely a moist biomass fuel with about 30 wt% w.b. moisture content and a dry biomass fuel with about 5-10 wt% w.b. moisture content. Moreover, regarding investigations on fuel flexibility it has been decided to consider softwood pellets, industrial wood chips (from sawmills), forest wood chips (= forest residues) and willow from SCR. As a next step, the system design concept for a real-scale HiEff-BioPower plant has been developed in a stepwise procedure in close cooperation of all technical partners. To support this work a project specific mass and energy balancing tools have been developed.
Regarding the fixed-bed updraft gasifier, R&D mainly focused on the development of measures to make it more fuel flexible and to adapt it for the integration into the whole system. To enhance fuel flexibility, a new fuel feeding system, a water cooled grate and primary air humidification as a measure for fuel bed temperature control have been implemented. Moreover, a new primary gas treatment zone has been developed and integrated directly on top of the gasifier fuel bed. In this zone the tar content of the product gas, which typically amounts between 100 and 200 g/Nm³ at fuel bed exit, can be reduced by 98-99%.
Moreover, the GCU has been developed. The core of the GCU is a filtration unit equipped with high-temperature ceramic candle filters. Upstream of the filtration an entrained flow sorption process is located. The entrained flow sorption unit consists of a sorbent feeding system and an entrained flow reactor. Lab-scale tests have been performed to determine an appropriate sorbent material resp. mixture of sorbent materials. Thereby, it has to be considered that HCl as well as S-compounds have to be captured. Moreover, the comparably high gas temperatures of about 750°C have to be taken into account regarding possible sorbent sintering effects. Low-cost minerals (Na-based) and (Ca-based) chalk are promising candidates and therefore investigated. The hot gas filtration unit is equipped with a reverse pulse cleaning system.
Due to cost reasons, for the testing plants to be realized within the project a slip stream SOFC system with a nominal electricity output of 6 kW is developed. A suction blower has been integrated in the SOFC system, which is used for sucking air and product gas from downstream the GCU through the system. A catalytically coated heat exchanger is used for pre-heating the cathode air and for the combustion of remaining H2, CO and CH4 in the SOFC off-gas flow as well. After this catalytic burner an exhaust gas cooler is integrated for further heat recovery.
The single plant components have been manufactured and a first testing plant has been assembled. Comprehensive test runs at this plant have been started and are still ongoing.
Besides these technical tasks, also a strong focus was put on economic, environmental and market related issues. The compilation of a comprehensive market study regarding the market potentials and future trends for biomass CHP systems in Europe has been performed in order to identify the most relevant future markets for the new technology. Preliminary techno-economic analyses have been performed in order to check the economic viability of the new technology and to define cost targets for the single plant components. Moreover, preliminary environmental, economic and societal assessments have been performe
The novel technology shall define a new milestone in terms of CHP efficiency and equal-zero emission technology in the medium-scale capacity range and shall contribute to a stronger and future-oriented EU energy supply based on renewables. Its fuel flexibility shall ensure high attractiveness and market application potential and thus strengthen the industrial base in the EU as well as the technological leadership.
Scheme of the HiEff-BioPower technology