Design and Performance Analysis of a Biomass Fueled MonoTube Boiler for Humid Air Turbine Cycle

Abstract

Externally fired gas turbine (EFGT) is one of the few power generation configurations capable of utilizing biomass in its solid form without any additional equipment to convert it to liquid or gas. Due to its high thermal output capability for drying applications, EFGT is one of the most suitable configurations for the off-grid rural areas in Malaysia with abundant biomass waste and high demand of heat for crops drying. The main downside of EFGT is the necessity for high temperature heat exchanger which compromises the system feasibility due to the high cost and other technical challenges. This can be eliminated by the addition of steam in a configuration known as humid air turbine (HAT), thus, limiting the required temperature and allowing for the use of common low-temperature heat exchanger types. Several mono-tube steam boiler designs were compared to fulfil the required steam flow rate of 2 kg/min for the available EFGT system. Counter-flow design was found to be more suitable with its higher efficiency. The boiler was characterized experimentally at output steam flow rate range of 0.4-2 kg/min using off-cut waste wood from furniture industry. Maximum achieved boiler efficiency and specific fuel consumption were 73% and 0.29 kg/kWh, respectively.