The elimination of noxious, malodorous, dusty or toxic substances has always been done, in air purification plants of tunnels, by traditional scrubber outfit, electrical filters or, in extreme cases, by expensive active carbon absorbers or catalytic reactors. The leaps forward during the past few years for eliminating environmental pollution allowed Vivex Engineering, an Italian innovative company in industrial air treatment, to develop a range of efficient and reliable solutions based on cold plasma. Cold plasma technology has received much attention from scientists and researchers. This proven technology, employed with Vivex’s Plasma Air machines, is the core of its Plasma Indygo equipment, which comply with the ever more restrictive standards of environment protection and fume purification caused by vehicular traffic.
Tests and analyses confirm the high properties of Plasma Indygo to reduce toxic substances: up to -30% of carbon monoxide, up to -45% of nitrogen monoxide and up to -90% of nitrogen dioxide.
Plasma Indygo also eliminates NOx, dust, metal particles, ammoniac, hydrocarbons, volatile organic compounds (VOCs), etc. Plasma Indygo is characterised by the absence of filters, a noise level of less than 50 dB at three metres, the absence of vibrations, a very low energy consumption, the absence of rotating parts, a reduced maintenance, a very reduced pressure drop (less than 100 Pa), and a resistance of up to 800°C for 60 minutes.
The patented Plasma Indygo is designed to solve the above-mentioned problems thanks to a special purification treatment cycle in one compact and pre-assembled unit that can be installed in existing air treatment facilities as a pre-treatment system or directly on the jet fans installed on the tunnel roof. Plasma Indygo is a stainless steel equipment.
In tunnels already equipped with an air purification system, Plasma Indygo used as pre-treatment equipment makes the elimination of gases such as CO, NO and NO2 more efficient and therefore reduces the air opacity inside the tunnel and the fresh air flow from outside. Plasma Indygo reduces by 40% to 50% the external air flow, which saves energy.
In a new tunnel, Plasma Indygo both reduces the costs of the ventilation equipment and saves energy. If we consider a 1.6 km-long 5 m-high single-tube tunnel with two lanes, each 4.5 m wide, perfectly horizontal, with a traffic volume of at least 2,000 vehicles per hour travelling at an average speed of 50 km/h and a density of 40 vehicles per km, calculations already made show that the external air flow rate needed to keep the contaminating concentrations within the limits specified by the legislation must be of approx. 150 cu m/s to reduce the concentrations of NO2, approx. 45 cu m/s to reduce the concentrations of CO and approx. 85 cu m/s to reduce opacity. The risk of fire is left apart to simplify the case in this example.
In practice, if there were only problems of CO and opacity in tunnels, the air flow necessary to contain these pollutants would be lower. Not only the presence of NO2 and its high toxicity makes the air opaque but also requires enormous quantities of air to be blown in.
In the tunnel in the afore-mentioned example, four pairs of jet fans should be installed at 400 m intervals to guarantee an air flow of 150 cu m/s, as per the calculations. These enormous fans would supply each an air flow of at least 75 cu m/s and a power of around 100 kW. Therefore, to ventilate correctly the tunnel, the electrical power should be of about 800 kW. The ventilation cost would be very high.
With fans equipped with Plasma Indygo, assuming that NO2 is reduced by only 50%, it obviously means that this is like if traffic in the tunnel was half what it is and therefore the ventilation air flow would be equal to 75 cu m/s instead of 150 cu m/s. There would still be four pairs of jet fans, for obvious fluid dynamics reasons, but each fan would supply an air flow of approx. 36 cu m/s and a power of 50 kW. The electrical power required for ventilation would be cut to only 400 kW. The required power for each Plasma Indygo would be about 7 kW which makes, in our example with eight fans, a total of 56 kW. The total power used for ventilation using Plasma Indygo would be 456 kW instead of 800 kW without it.
Cold plasma technology is available for common applications around the world. Up to now, the technology was used exclusively by space and military agencies. Thanks to the R&D activity conducted by Vivex Engineering, the company is able to expand the range of activities open to the application of cold plasma.
Cold plasma technology has been mentioned several times as the remedy of the future against indoor and outdoor pollution. Vivex Engineering recently developed its Plasma Indygo system, the first product that purifies the air in road tunnels using cold plasma technology. It can be rapidly installed in tunnels with fan ventilation and in new tunnel projects.
Plasma Indygo represents a definitive solution, offers exceptional results in every industrial sector where it is applied. Tunnels are nothing else but a new implementation derived from the industrial sectors in which Vivex Engineering has been extensively using it over the past two years. Contact
m.mango@vivex.co.uk for more and visit
www.vivex.co.uk.
