Intelligent use of electrostatic separation means no more wet scrubbing or filtration to recover overspray, saving energy and ‘greening’ the paint process further

Boost efficiency, save energy, avoid CO2 emissions – these are the catchphrases of today's strategies for successful and sustainable production, particularly in these challenging economic times. With a revolutionary process called E-scrub, the global plant engineering specialist Eisenmann is presenting an electrostatic separation system for paint overspray that implements precisely these strategic aspects.

The objectives in this area of paintshop are clear: a separation system that benefits the environment, saves resources, cuts operating costs, is robust, reliable and easy to use and can be retrofitted without difficulty in existing plants. “I am delighted to say that we have achieved these goals with E-scrub and can now offer our customers a highly efficient, environmentally beneficial and economical solution for their painting systems,” said Dr. Kersten Christoph Link, Chief Technical Officer of Eisenmann.

The basic principles of E-scrub

With E-scrub, the air in the spray booth is specifically routed to guide the surplus paint mist (overspray) produced during the painting process via funnel-shaped run-off surfaces known as flood sheets into the new electrostatic separation system. Part of the overspray is immediately bound by a separating agent, a liquid that is introduced onto the flood sheets which transport the paint particles into a collecting pan at the base of the paint booth.

Most of the overspray is diverted into the ‘separating modules’ at the bottom of the flood sheets. These high-voltage modules are fitted with positively charged separating plates which are also rinsed with separating agent in a circulating system.

Additionally high-voltage wires run horizontally between the separating plates inside the module. Paint particles in the circulating air stream become negatively charged as they pass the high-voltage wires and are attracted by the positively charged separating plates. Here too, the paint particles are bound by the separating agent and discharged into the collecting pan at the bottom.

Due to the chemical composition of the separating agent, the bound paint particles combine in the collecting pan to form solid agglomerates which can be removed and disposed of without difficulty.

Energy-efficient and environmentally beneficial

E-scrub combines maximum separating efficiency with minimum pressure loss, permitting operation with 95 percent recirculated air. Compared with a conventional wet scrubber section, this results in energy savings of up to 78 percent and a corresponding reduction in CO2 emissions. In addition, E-scrub requires up to 87 percent less water and considerably less chemicals. The electrostatic system switches on and off in sequence with production cycles, yielding further energy savings.

Separating efficiency is maximized by electrostatic charging and binding the overspray in the separating agent. The German clean air regulation “TA Luft” permits maximum dust emissions of 3 mg/m3 – with E-scrub, this value can be comfortably met and further reduced, to 0.3 mg/m3. In combination with recirculation of the air, the system consequently reduces particulate emissions up to 100-fold.

Quality and reliability in production

By eliminating complex mechanical filter systems, E-scrub ensures constant flow rates without pressure fluctuations – an essential prerequisite for optimum production conditions and high quality coatings. In operation, E-scrub is characterized by considerably lower noise levels and easy servicing.

Simple retrofit, rapid amortization

Another advantage of E-scrub is that it can be retrofitted quickly and simply in existing plants. Moreover, E-scrub requires considerably fewer plant components than a conventional wet scrubber system.

E-scrub appears to be the energy-efficient, environmentally beneficial and cost-cutting alternative to wet and dry separation in spray booths. It cuts operating costs significantly, and this can help towards rapid amortization of the investment cost of the system.

National and International Awards

When Eisenmann launched the new E-scrub product at the beginning of 2009, nobody guessed that the engineers from Boeblingen, Germany would win numerous awards. E-scrub already convinced three important technical committees.

Following the SURCAR Innovation Award and being awarded the third prize in the Umwelttechnikpreis Baden-Württemberg competition (environmental technology prize of the federal state of Baden-Wuerttemberg, Germany), the product recently also ranked among the winners of the NoAE Innovations Competition.

The biennial SURCAR Congress on Automobile Body Finishing centers on new products, technologies and processes in the field of painting. Within this scope, the technical committee of the organizer awards the SURCAR Innovation Award. “We are pleased that E-scrub impressed the jury. This is a further confirmation that we offer our customers a highly efficient, environmentally beneficial and economical alternative to wet and dry separation in coating booths,” said Dr. Link.

A network of excellence

This affirmation of excellence was further confirmed by the system appearing as one of the “TOP 30 Prize Winners” of the Network of Automotive Excellence (NoAE). This crosscompany initiative to celebrate innovation in the European automobile and supplier industry selected the best 30 of 380 submitted products and solutions within the scope of its innovations competition.

There was no ranking among these 30. The innovations competition was under the patronage of the Federal Minister of Economics and Technology of the Federal Republic of Germany, Dr. Karl-Theodor zu Guttenberg.

E-scrub, however, did not only gain recognition on an international and European level, the product was also able to score in the environmental technology competition of the federal land of Baden-Wuerttemberg, Germany. The product won the third prize in the category “Technologies for emission reduction, treatment and separation”.

Apart from the many awards, E-scrub has also been wellproven and tested in the field. It has been implemented successfully in the in-house paint shop at Eisenmann, where it has made a substantial contribution to the production process.

In addition, interested customers can experience the product in the application and see its benefits for themselves.