Shocks blast way to new technologies

Controlled electric explosions – made by passing short pulses of very high current through water – produce massive shock waves capable of shattering unwanted material, cleaning pipes or killing bacteria. The idea has been around for decades, but it is only recently, apart from the high voltage sparkers used as sound sources in undersea geophysical surveying, that it has been exploited commercially. This new play on an old idea is the brainchild of Dr Anatoly Mnukhin, chairman of Electrohydraulics, an R&D company based at Makeevka in Donetsk, part of the Ukraine. His company has developed a number of explosion machines each aimed at carrying out specific kinds of demolition or cleaning jobs. During the in-water explosions, electric field energy is converted into mechanical energy. In a 5,000V circuit the instantaneous current goes up to 20-30,000A producing an electric plasma discharge with a temperature of up to 20,000°C, which, in turn, brings about a powerful, precisely localised explosion wave with pressures of up to 30,000 atmospheres. Several coal mines in the Ukraine have employed the process for pipe cleaning and a number of cement and metallurgical facilities have cleared their drainage and heating systems. The Enakiyevski metallurgical factory has also used it to annihilate 100 year old concrete bases and supporting constructions. The method has also been used to destroy iron-coated columns, hard to tackle even with explosives, and it is said to allow the extraction of diamonds from mining rock spoil. What makes it particularly attractive is the fact that production need not be brought to a halt or even interfered with during operation. One of the rigs has shown an ability to kill microbes in drinking water. After a test in which five explosions were made in 0.8 cu.m. of river water, the total microbe population was reduced by 90% enabling the company to win a contract with a major coal mine for a bathing facility for the miners. Other potential applications still need further research and development. They include sewage cleaning, vessel rust cleaning and nitrogen production. The last one is possible due to the fact that ordinary water, when electrohydraulised and simultaneously saturated with adequate amount of air, tends to become rich in nitrogen-containing compounds. Note: Author Tim Neshitov is currently completing a degree course on international journalism at the State University of St Petersburg in Russia. The article was written in the course of international work experience at Findlay Publications Design Pointers The process allows for the efficient demolition of ageing concrete and iron encased blocks on factory premises without affecting production Other successful uses include the cleaning of coal mine tunnels, sea vessels and underground metallurgical equipment, as well as killing off microbes in drinking water Dr Mnukhin Electrohydraulics