Progress in the application of biomass energy power generation technology at home and abroad

Foster Wheeler biomass circulating fluidized bed (CFB) boiler technology, the unit generation power of 3.0 ~ 47.0 MW. Its biomass fuel is mainly wood processing waste, paper waste, etc. The highest water content of waste can reach 60.0%, the smoke exhaust temperature is 140℃, and the boiler thermal efficiency is 88.0%. In early 2005, Foster Wheeler signed an agreement with Semb Corp Utilities UK Limited to supply bubbled fluidized bed boilers for the latter's 30.0 MW wood-fueled generator set.

Takuma, a Japanese company, has sold more than 500 steam boilers for power generation and heating in Japan and overseas, using wood chips, bagasse, and grain residues.

Belgium Brusselwink Energy Technology Company, as early as the 20th century to the 1930s began to burn straw boiler design and manufacturing, is one of the world's first use of biomass as fuel boiler companies. The fuel of the boiler is mainly wood waste, wood construction waste, paper waste and municipal waste. The company's inclined hydraulic mobile grate furnaces, with a thermal efficiency of up to 85.0%, are more suitable for biomass burning generators below 20.0 MW.

Bobcock&Wilcox's products include grate stoves and CFB boilers. Ge uses CFB combustion and has built a number of biomass power plants in California with a capacity of around 2.5 MW.

1.4 Development status of domestic pure fuel bio-power generation technology

China is the world's largest energy consumer, in order to reduce carbon emissions, to achieve low-carbon development, China in the adjustment of energy structure to give priority to the development of renewable energy, including biomass energy with its various natural advantages to become the focus of renewable energy development. In 2006, Shanxian County, Shandong Province, was built with a 30.0MW small biomass pure combustion power generation system with BWE biomass stoker technology, equipped with a 130 t/h vibrating stoker high-pressure boiler. China's total installed capacity of biomass combustion power generation increased from 12.1 GW in 2016 to 22.5 GW in 2019, an increase of more than 20.0% for three consecutive years, and completed the total installed capacity of biomass power generation in advance of the "13th Five-Year Plan".

In the development process of biomass pure combustion power generation technology, CFB has the advantages of wide fuel adaptability and low pollutant emission, and considering the investment in unit construction, CFB combustion mode is generally adopted in new units. As of April 2020, the number of pure biomass burning units in China is nearly 440, including 336 CFB units. After 2010, pure burning biomass units have developed in the direction of large capacity and high parameters. Several milestone projects include the commissioning of a 50.0MW biomass CFB boiler generator unit in Zhanjiang, Guangdong Province, in 2011; In 2016, the world's first 125.0MW biomass CFB boiler designed and manufactured in China was put into operation in Thailand. Since 2019, a large number of ultra-high pressure reheat biomass CFB boilers have been widely used in industry. At present, the ultra-high pressure 80.0MW biomass fluidized bed unit is being installed and commissioned.

Biomass fuels in Europe are mainly forestry wastes, while biomass fuels in China are mainly agricultural wastes, which are more prone to problems such as ash and slag accumulation and corrosion in combustion engineering. With the continuous development of the demand for biomass pure fuel power generation industry, the number of domestic enterprises with the corresponding equipment design and manufacturing capabilities has gradually increased. Whether in terms of installed capacity or unit parameters, China's biomass CFB pure fuel technology has reached the world's advanced level.

1.5 Existing problems 1.5.1 Cash flow pressure of power generation projects

Biomass pure combustion power generation technology has a great space for development in China, but there are still many constraints in the entire industry, the most prominent of which is that the business model of pure combustion biomass power generation project has a large cash flow pressure. On the one hand, the cost of biomass fuel is high, and the supply is affected by seasonal factors, and the price fluctuates greatly. On the other hand, renewable energy electricity price subsidies and the government's VAT rebate policy cause the amount of receivables to be high, and the return time is uncertain.

1.5.2 Continuous operation period to be extended

Although domestic and foreign scholars have conducted a lot of research on the ash and slag accumulation characteristics of biomass fuel, and have also improved the boiler design accordingly, the operation situation shows that the continuous operation cycle of pure biomass CFB boiler is still less than 6 months. The main reasons are the slagging of the bed material, the agglomeration of the return valve, the accumulation of ash on the convection heating surface, the corrosion of the high-temperature heating surface in the furnace and the low-temperature heating surface of the tail flue, and the greater toughness of the biomass, which is easy to cause the wear and heat of the cutting head. Impurities and fibers in biomass can also cause clogging of feeding systems and separators.