| |
 |
Depuration of smoke can be profitable
|
Zhou Jianchuan
A renewable electrolytic process to clean chimney smoke was recently developed by engineers with Shenzhen Clean Environmental Science & Technology Co Ltd, a local cleaning equipment manufacturer, marking a breakthrough in efforts to cut emissions of sulphur dioxide (SO2).
The effective and economical system enables coal-fired power stations to cut costs and create new profits out of their by-products, according to Zheng Zhihui, chief executive of the company.
Sulphur dioxide, one of the combustion products of coal, is a main source of acid rain. Coal is still the main fuel used in China, making up 75 per cent of the total fuel used. On the other hand, desulphurization of the coal and the smoke is an extremely costly endeavour, a fact which prevents most power stations from cleaning up their emissions. In the year 2000, coal-fired power stations generated half of the total sulphur dioxide emissions nationwide.
The newly developed system largely curtails the cost. Using a sodium hydroxide (NaOH) solution as desulphurization agent is much more effective than using lime cream, the main substance used today. Lime cream is a cheaper agent but generates secondary pollutants, hence hindering its popularization. The NaOH solution, due to its high price, is not widely used. But by using the solution repeatedly in an electrolysis circulation system, engineers with Clean Co Ltd have slashed the cost of the NaOH solution system. Moreover, purified waste water from the desulphurization process can be used to prepare pure sulphur dioxide gas or sulphuric acid, both of which are commercial products that can generate impressive profits.
If fitted with the new system, coal-fired power stations can use high-sulphur coal in place of low-sulphur coal as the fuel, for a tonne of high-sulphur is 30-50 yuan cheaper than a tonne of low-sulphur in domestic market. The company's chief executive calculated that a 300-million-watt generating plant, consuming 200 tonnes coal per hour, could save at least 50 million yuan each year.
"Our goal is to let enterprises view environmental protection as a compulsory contribution. With this new technology, we make them be willing to clean up their act," said the chief executive.
|
|
|
|
