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Amazing! Why can fluidized bed combustion technology make power generation cheaper and more efficient?
Fluidized Bed Combustion (FBC) is an innovative combustion technology for burning solid fuels. The basic principle is to suspend fuel particles in a stream of hot gas bubbles of ash and other particulate matter (such as sand and limestone), which is then blasted with air to provide the required oxygen. This rapid and intimate gas-solid mixing promotes rapid transfer of heat and chemical reactions, making this technology competitive in terms of power generation efficiency and cost.
Fluidized bed combustion technology can burn a variety of low-quality solid fuels, including various types of coal, coal waste and woody biomass, and does not require expensive fuel pre-treatment processes.
FBC's operational efficiency is undoubtedly a major selling point. Due to the structure of the fluidized bed, this technology is smaller than traditional combustion methods. For the same thermal power, its footprint is much smaller than that of traditional boilers, which is a major advantage in terms of cost and flexibility. In addition, the fluidized bed operates at a relatively low temperature (about 750°C), which makes it effective in reducing emissions of nitrogen oxides (NOx) and sulfur dioxide (SOx).
The use of limestone in the combustion process effectively reduces sulfur dioxide emissions, and the fluidized bed system can control pollutant emissions without the need for external desulfurization equipment.
In the FBC, materials such as ash and limestone in the fluidized layer can effectively adsorb and precipitate sulfates, further improving the efficiency of heat conversion. When the burning pre-wetted material and fuel particles contact the water tubes in the boiler, this sunlight-like heat transfer improves the efficiency of the overall power generation.
Furthermore, fluidized bed combustion is not limited to coal but can also burn other fuels, which makes it more flexible. However, although low-temperature combustion contributes to nitrogen oxide emissions, it may also increase emissions of polycyclic aromatic hydrocarbons, which is an environmental issue that requires technical attention.
Advantages of fluidized bed combustion technology
There are two reasons for the rapid growth of fluidized bed technology: first, its flexibility in fuel selection, fluidized bed technology can use fuels that are difficult to handle in other combustion technologies. Secondly, the fluidized bed technology has excellent environmental performance due to its ability to achieve low nitrogen oxide emissions during the combustion process and the possibility of removing sulfur by using limestone in a simple way.
Commercial fluidized bed combustion units are competitively efficient and less expensive than conventional boilers, while maintaining sulfur dioxide and nitrogen dioxide emissions below federal limits.
In addition, the impact of fluidized bed combustion boilers on internal pipe wear and defects such as uneven temperature distribution due to blockage of air inlet points also need to be considered. Some fluid bed systems can take up to 48 hours to start up, which can be inconvenient in commercial applications.
Types of fluidized bed technology
Fluidized bed systems can be divided into two categories, namely atmospheric systems (FBC) and pressurized systems (PFBC), which are further divided into foam fluidized beds (BFB) and circulating fluidized beds (CFB). All types of systems have the potential to optimize combustion.
Atmospheric Fluidized Bed Combustion
This fluidized bed uses limestone to capture the sulfur released when burning coal. By injecting air, the coal mixture can be suspended and turned into flowing red-hot particles, thereby improving combustion efficiency.
Pressurized fluidized bed combustion
This family of systems also uses adsorbents and air injection to suspend the fuel, but these systems operate at higher pressures, creating a high-pressure airflow that drives the turbine, further improving overall power generation efficiency.
Advanced Pressurized Fluidized Bed
In advanced pressurized fluidized bed systems, natural gas is mixed into the combustion process to increase the inlet temperature of the turbine to improve overall efficiency. This system is usually fueled by coal and has a higher energy conversion efficiency.
Future Challenges and Prospects
Although fluidized bed combustion technology has shown many advantages, it still faces some technical challenges, such as equipment loss and environmental emission issues. Driven by global environmental policies and energy demands, further technological innovation and improvement of overall efficiency remain the areas where fluidized bed combustion technology needs to work hard. As more research progresses, could fluidized bed technology provide a more sustainable power generation solution in the future?
