Energy and water are increasingly scarce and expensive resources. Their availability and price have reached the centre stage in the profit and loss accounts of all industrial companies. The escalating costs of energy in recent years have been compounded by the international situation of armed conflicts, causing a seismic shift in the sector, the consequences of which have yet to be weighed up. At the same time, the cost of water use (supply and treatment) has broken records to date, with the question of whether national water stress could lead to restrictions on its use. Therefore, it is urgent for the surface finishing industries to find a solution to water management within the framework of the Circular Economy and with the lowest possible energy consumption.
SDINOX has been one of the pioneers in solving this problem, reconciling the environmental protection with the optimization of resources.
It has recently acquired a Zero Discharge wastewater treatment system which will allow it to recover more than 90% of the water consumed in its production process with a leading technology in energy saving. This technology, known as CMV (Mechanical Vapour Compression) has been designed and manufactured by the Spanish company Incro, an engineering company with almost 50 years of experience, specialised in wastewater recovery.
The technology consists of a distillation of the effluent (acid rinse water) after pH adjustment, obtaining a high quality water that is reused again in the rinsing process. Depending on the degree of original contamination, this recovered distilled water is between 90-95% of the treated volume. All the pollutants contained in the discharge are retained in a final concentrate which is sent to an authorised manager.
The distillate obtained has a conductivity of 40 microS/cm and a pH of 8 and is used in the spray rinse on the pickled stainless steel parts. The resulting concentrate is of the order of 5%.
The Mechanical Vapour Compression plant consists of four clearly differentiated units:
- An Evapo-Condensation unit, where the evaporation of the liquid takes place inside the tubes and the condensation of the distillate on the side of the casing.
- A vapour purification unit, where the vapour generated during evaporation is separated from the entrained droplets and the possible generation of foams is controlled to guarantee the quality of the distillate. The scrubbing consists of a cyclone that causes gravity separation and a droplet separator.
- A Vapour Compression unit, where the pressure and temperature of the vapour generated in the evaporation is increased, allowing a temperature difference between the vapour and the liquid to be concentrated in the evapo-condenser.
- An Energy Recovery unit, where the hot distillate is used to preheat the effluent to be concentrated in the plant.
- The energy efficiency of the CMV is superior to other evaporation processes, such as heat pump evaporators, whose energy consumption is three times higher.
With this system, SDINOX has reduced its water consumption to a minimum, making it robust for drought restrictions. It has also eliminated the cumbersome, expensive and sensitive physical-chemical plant, as well as its alternative of sending the effluents to external management. And it has done so with the most efficient equipment on the market: Incro’s CMV.