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The Buggenum Integrated Gasification Combined Cycle (IGCC) was built as a demonstration plant to prove the technical and economic feasibility of coal gasification for electricity production. After the initial startup in 1993, the demonstration program was executed from 1993 through 1997. From 1998 until its closure in 2013, the plant was in commercial operation, ultimately reaching almost 7000 operating hours a year on syngas. The net output power was 253 MWe and the thermal efficiency was 43% on a lower heating value (LHV) basis. The first years of operation were considered learning years. Operational troubles in mainly the gasification section caused a lot of downtime. Furthermore, the gas turbine burners had to be adjusted by trial-and-error in order to solve the issue of humming in the combustion chambers. Frequent inspections and modifications prevented the plant from making long runs on syngas. Around 2000, the operators and staff had gained sufficient experience with the plant. Downtime was no longer mainly caused by operational problems, but by hardware failures. Main issues were leakages of the syngas cooler due to mechanical design flaws, failure of the uncooled heat skirt in the slag bath area, and leakages of the ceramic candles in the fly ash filter. A new operational issue was too low capacity of the molecular sieves of the air separation unit (ASU) during the summer. Because of CO2 breakthrough, the blowdown line of the liquid oxygen bath became blocked a few times, requiring the ASU to be defrosted. Nevertheless the availability of the plant gradually increased. Around 2006, issues were solved or made manageable and the plant operated smoothly on coal. From then on the biomass co-gasification feed rate was gradually increased, and in addition two demonstration plants were connected to the existing IGCC. First a very small coal to liquid plant, a project in cooperation with Shell and ECN, and later a pre-combustion CO2 capture plant which treated 0.8% of the total syngas stream. In 2011 and 2012 co-gasification tests with steam-exploded and torrefied wood pellets were executed successfully. The IGCC was operated for a few days on a mixture of coal with 50–70% pellets on energy basis. The project of switching to 70% biomass was discontinued because of the insufficient availability of these pellets. A few months later the plant was closed because it was not profitable due to low electricity prices. This chapter provides detailed descriptions of 20 years of operational experience and lessons learned in the Buggenum IGCC plant. |
