순산소 조건에서의 미분탄 연소 특성에 대한 전산해석

Abstract

Emissions of greenhouse gases are expected to cause climate change. The main greenhouse gas is carbon dioxide and the major source of it is the combustion of fossil fuels to supply energy. Emissions can be reduced by a variety of measures, such as improving energy efficiency and developing alternative energy sources, like wind and solar power. However a rapid move away from fossil fuels is unlikely as energy supply infrastructure has a long life time, and such a move could destabilize economics. Another way to reduce emissions is to capture the CO2 that is released from fossil fuel-fired power plant and store it underground. One-third of CO2 emissions from power plant using fossil fuel. So, reduction of greenhouse gases, especially CO2, by power plant may be an effective solution for the critical issue of global warming and climate change. Oxy-PC (Pulverized Coal) combustion with CO2 recirculation has been under active investigation recently as a measure of CCS (Carbon Capture Storage). Oxy-combustion is the term for when a fossil fuel is combusted with nearly pure oxygen and recycled flue gas or CO2 and water/steam to produce a flue gas consisting essentially of CO2 and water. It may have potential as part of a system for capturing and storing CO2 as the nitrogen concentration in the flue gas is much lower than when air is used for firing. However, There are many problems about Oxy-PC combustion because of difference between Air and CO2 environment. So, It is important that understand how pulverized coal combust in O2/CO2 environment. CFD simulation is performed for the Oxy-PC test facility at Aachen University and the 0.4 MW single burner by the commercial software STAR-CD to analyze combustion characteristics for parametric variation of the major operating conditions and design variables. Different flow characteristics are partly due to a lower magnitude of the outlet velocity of oxy combustion with CO2recirculation than that of air combustion with the same mass flow rate. A higher CO2 mass fraction can increase the outlet velocity magnitude, but can cause an energy density problem.