A metallurgical investigation on a failed superheater tube used in a thermal biomass power plant

This article described the investigation of the failed superheater tube made of SA210 Grade C used in a biomass power plant. Visual inspection, microstructural examination, chemical analysis and hardness measurement were employed to analyze the causes of the superheater tube failure. Results from the investigation showed that the major cause of this failure was mainly related to the long-term overheating, resulting in the occurrence of the excessive thermal oxidation and graphitization. The excessive thermal degradation accelerated the reduction of the wall tube and promoted the build-up of the stress acting on the tube. Graphitization degraded the microstructure of the tube, reducing the mechanical performance of the tube. The combined effects from the severe thermal oxidation and graphitization attributed to the premature failure of the tube. It is therefore advised to use the correct material, SA213 T22, in the failed section. Material specification examination for superheater regions prior to tube installations should be performed to avoid the use of the inappropriate material. The temperature monitoring and mapping in this section were also suggested.

Assessment on Energy Conversion Efficiency and GHG Emissions Rate for Coal, Natural Gas and Biomass Power Plant in Malaysia

Three different power plants have been assessed in terms of energy conversion efficiency and GHGs emission rate. The power plants are coal power plant, natural gas power plant and biomass power plant. The assessments are made by collecting fuels consumption data and generated electricity data of each power plant. In addition to the data collection, observation on operational practices have also been carried out. The energy conversion efficiency and the GHGs emission rate for all power plants are recorded to be lower than the typical values proposed by the literature. The biomass power plant recorded the lowest energy conversion efficiency at 6.47 %. Meanwhile, the natural gas power plant utilizing the combined cycle gas turbine technology recorded the highest overall energy conversion efficiency at 48.35 % and rated to emit GHGs at 0.32 kg CO2e per kWh.