ENK5-2000-00305 Tar Decomposition by Novel Catalytic Hot Gas Cleaning Methods - NOVACAT

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EESD (Energy, Environment and Sustainable Development) : Thermochemical Conversion

Proposal No:	ENK5-2000-00305
Date Prepared:	February 2004
Source:	European Bio-Energy Projects (EUR 20808)

Introduction

The successful implementation of biomass and waste gasification for power production depends on the availability of low-cost, simple, reliable and high-performance gas cleaning systems. The present solutions for gas cleaning do not fulfil these conditions.

Activities

The work in this project concentrated on the development of two novel catalytic tar decomposition processes: 1) a catalytic filter and 2) a gas reformer based on nickel monolith catalyst.

The tasks of the project were:

• Catalytic filter development and testing with simulated and real gases,
• Optimisation of the catalytic gas cleaning process in connection to a fluidised-bed gasifier,
• Long term testing of nickel monoliths in a slip stream of an industrial biomass gasifier,
• Pilot-scale tests to optimise the complete gas cleaning train for modern turbo-charged IC engines,
• Techno-economic studies for both catalytic gas cleaning systems developed in the project.

Results

The development of the catalytic filter included testing and optimisation of catalyst formulations with simulated and real gases. Novel modified nickel-activated alumina filter substrates were developed, prepared and screened. Improvement in the resistance to deactivation by sulphur compounds in biomass gasification was one of the main objectives and achievements of the work. Valuable information about catalyst improvement techniques was obtained. The catalytic filter was also tested with real gases and promising results were achieved.

Preparation procedures for largescale candle filters were also developed. The long-term testing of the nickel monolith was performed with a slipstream apparatus that was connected to a CFB gasifier. The total test length was 2267 h. The main conclusions of the long-term test were:

• the nickel monolith catalyst activity remained at a high level during the test,
• it is probable that the catalyst will remain active for longer periods of time,
• tar conversion after the test was 92% and ammonia conversion 70 % at the 900 °C operation temperature,
• fouling or clogging of the monolith by carbon did not occur.

The technical feasibility of the monolith-based concept was demonstrated by performing a pilotscale test run with a process consisting of a NOVEL fixed bed gasifier, a catalytic reformer followed by a filter and gas scrubber/cooler. The gas produced had very low tar (< 100 mg/Nm³), ammonia (< 50 ppm) and particle (< 5 mg/ Nm³) contents and it can be considered suitable for use in modern turbo charged engines.

Optimised operation conditions were found for the nickel monolith and the effects of the main process variables were studied. These included temperature, gas residence time, partitioning of the air feeding, gas H₂O/C* ratio and gas superficial velocity. This work also included screening of limiting operation conditions as well as studies on the effects of process starting and shutting down procedures.

The technical and economical evaluation of the NOVEL CHP process gave very positive results considering the promotion of the plant. The rather interesting aspects are the reduced size of the plant, the continuous operational system and the capability of gasifying various types of biomass, without endangering the performance of the gas engine. With these characteristics the diffusion of the technology might be successful, especiallyin the present European market conditions.

Impact and exploitation

The objectives of this project match the EC Renewable Energy Technologies (RET) policy with an important contribution of biomass. This requires biomass gasification systems to be reliable and simple, and hence contain compact, low cost but high performance gas cleaning, which fulfils all environmental requirements.

The two proposed gas cleaning technologies can make biomass energy systems more attractive, leading to widespread use of such systems with benefits in terms of employment and emissions. Given the required development effort still needed, support by the EC of a multinational team was justified.

The results of this project are of utmost importance considering the commercialisation of power production by gasification procesesses. As a direct follow up from this project, Condens Oy has been able to commercialise the NOVEL CHP process. This makes the NOVEL process a real success story of Commission-funded applied research, due to the fact that the process development has taken place essentially in two successive EU-funded projects.