Burning bright in Beijing
When it comes to reducing emissions and energy consumption from fuel burning, most people think of switching to alternative fuel sources or end-of-pipe cleanup solutions. But there is also room for improvement at another stage: the combustion process itself, when fuel is burned. Two companies in Beijing are now focusing on improving this process, with impressive results.
Last year Hancunhe village, in Beijing`s Fangshan district, invested almost 20 million yuan (US$2.8 million) in three new heating boilers, which have completely changed the way heat is provided in the area. There is barely a stovepipe in sight and no soot is produced. The villagers can dry clothes or store cabbages in their courtyards without fearing they will collect dirt.
The technology was developed by Beijing Xiongcai Group. In the village boiler room, its chairman, Wang Yongjiang, opens up a small hatch on the boiler and shows me the flame inside. “Normally coal is burned from underneath,” he explains, “but our boilers burn the coal from above, which allows us to collect the soot and burn it again. When the harmful components in the soot are exposed to temperatures over 800 degrees, they are burnt away, massively reducing emissions. The flame inside burns pure blue and translucent, which means the fuel is being burned completely. Yet the coal we use only contains 3,500 kilocalories per kilogram – about half the energy content of fine coal.”
Xiongcai aims to solve some very real problems: how can China make use of its current stock of 4.8 million coal-burning boilers? How can the country cleanly and efficiently burn coal and biomass fuels like chaff, sawdust, leaves and household waste? How can the country utilise commonly discarded low-grade coal such as lignite, coal slurry and gangue, and coal that has not been fully burnt the first time round? These have long been important questions for China`s energy and environmental sectors.
Since 2000 the firm has approached these questions by treating fuel and combustion technology as a single, integrated subject. The company`s patented biomass boiler and “biomass coal” fuel together make up a system for burning biomass combined with lower grade coal, which burns with a heat energy efficiency of more than 80%. Its emissions are on a par with the cleanest of boilers, and the system reduces energy consumption and waste. The “biomass coal” is made up of compressed chaff, tree leaves and branches, household waste, gangue, coal powder and other low-grade coals. The resulting fuel is dense, burns completely, does not produce black smoke and fixes sulphur. When burned in the boiler, it can produce the same heating effect as fine coal. The waste from the boiler also has a number of applications: it can be used in water purification, in building insulation and as fertiliser. Both the biomass fuel and waste from the boilers is transported in sealed packages to prevent any secondary pollution.
Beijing Yanshan Petrochemical installed a Xiongcai biomass boiler system in September 2004. They found they not only reduced their heating costs, but also reduced their pollution emissions. The city then set up several pilot schemes for biomass coal heating systems, which were installed over the winter of 2006 and 2007 in the outlying regions of Fangshan, Yanqing and Shunyi. Satisfaction rates among users were reported to be around 100%. Even in Yanqing, which is colder than most other areas, users said that heating was much improved. The new boilers provided warmth for the farmers, while solving problems with soot, noise and pollution – and its negative health impacts.
Between 2002 and 2007, biomass boilers with a total production capacity of 300 megawatts have been installed in Beijing municipality, resulting in savings of 86,400 tonnes of standard coal. Emissions have been cut by a total of around 223,800 tonnes of CO2, 887 tonnes of sulphur dioxide, 1,729 tonnes of nitrogen oxides and 4,470 tonnes of dust particles. In 2008 the city government will promote clean biomass fuels in Daxing, Pinggu, Miyun, Mentougou, and Yanqing. Heating provision should be expanded by several million square metres.
The regenerative burner
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