Eisenmann
Sustainable production and energy- and resource-efficiency are a top priority for carmakers, automotive suppliers and all companies who operate painting lines.
EISENMANN is always focusing to install the most ecological and economical solution, with lowest operation costs for the customer, considering the national and local emission standards.
It is strongly recommended, that the focus for removal of paint overspray and VOC from the exhaust should be shifted from so called “end-of-pipe-technologies”-Thinking to Production Integrated Environmental Protection.
New recycling methods help to avoid Scrap, Waste and Emissions.
Production Integrated Environmental Protection means for example to consider the following options to avoid respectively reduce VOC-emissions:
- Check whether, liquid paint can be substituted by using powder paint
- Change from solvent-borne to water-borne paints-systems
- Usage of high solid paints
- Install high efficient application systems(E-static etc.) to increase the efficiency and to minimize overspray
- Integrate air recycling systems in the paint booth areas, in order to minimize the exhaust air volume, which has to be treated, e.g.: reuse exhaust air from the manual zones and forward them in a so called “cascade-system” to the automatic zones(reductions of up to 65% are achievable)
- Don't spray solvents from color change resp. cleaning operations into the spray booth, collect them and think about recycling via distillation
The E|cube is an innovative system for dry overspray removal.
It is indispensable to have solutions for efficient air recirculation in painting lines.
For many years the Venturi Scrubber was the state of the art solution for removing overspray.
With E|cube we can now offer a simple alternative with incredible advantages. E|cubes are separation modules directly located below the grid of the spray booth. The exhaust will be sucked through these effective hybrid filters, which guarantee high removal rates and perfectly cleaned air. The overspray stays in the Cubes, which can be easily disposed when they are full loaded.
The advantages of the system are described in figure 1.
An example of different VOC-treatment, see figure 2 shows how intelligent solutions can significantly reduce the consumption of energy.
The task in this example is to treat 40.000 m³/h of exhaust air with a solvent(VOC) concentration of 0,25 g/m³. The easiest way is to incinerate the VOC in a simple combustion chamber, but the energy consumption would be very high.
Using a Thermal Oxidizer(TO) respectively a Regenerative Thermal Oxidizer(RTO) has already a much higher efficiency.
The most innovative system is the combination of Adsorption Wheel(= concentrator) and RTO.
High Performance Air Treatment System
The following example describes a high performance exhaust air purification system for exhausts from spray-booths and ovens.
The plant configuration, according figure 3, allows to treat the exhaust air from spray booth and ovens together in one very efficient system.
It can be used to retrofit existing paint-shops as well.
The exhaust air purification plant consist of Adsorption Wheel (wheels) with zeolith material and RTO (RTOs). The necessary number of the adsorption wheels and RTOs is based on the total exhaust air volume.
Filter-system
The exhaust air from spray booth (should be nearly free by solid particles) is filtered with bag filters where final solid particles are separated to protect ADW.
The type and filter stage quantity depends on the type of overspray-separation, see figure 1.
Adsorption Wheel ADW
The exhaust air is passed over an ADW by an exhaust air fan with negative pressure control.
The ADW comprises a cylindrical tube with individual chambers containing the adsorbens(zeolith) on which solvent(VOC) will be adsorbed and therefore eliminated from exhaust air. The cleaned air will be discharged into the atmosphere.
The rotor is mounted on supporting rollers and rotates continually about a vertical axis at approx. 1 - 3 rev/h.
Hence the chambers with solvent-laden adsorbens enter the desorption sector. This sector is separated from the adsorption sector by a special seal.
A small stream of heated desorption air flows through the adsorbens.
Solvents are removed from the adsorbens and discharged in highly enriched form.
That means that the ADW works as a concentrator.
After cooling down this section it turns back again in the adsorption mode.
The cooling air will be heated up for the desorption process in a natural gas powered heating box.
After the regeneration process, the concentrated desorption air will be mixed together with the oven exhaust air from paint-shop and be treated in the downstream installed RTO system.
Regenerative Thermal Oxidation RTO
The Regenerative Thermal Oxidation plant is used to clean the exhaust air from ovens and concentrated desorption air from adsorption wheel.
The basically features of the regenerative system is the high internal thermal utilization and high insensitivity in relation to the exhaust air characteristics.
The single reactor system developed by EISENMANN in 1992 resulted from a combination of proven components from the sectors of adsorption wheel and RTO technologies. Unlike 3-tower-RTO, the EISENMANN RTO switches continuously between heating and cooling.
A stationary bed made of ceramic moldings is used as the regenerative heat exchanger mass in the reactor in order to achieve uninterrupted heat transfer from the hot purified gas stream to the cold exhaust air stream.
The heat exchanger bed is subdivided into separate zones. A part of the segments serves alternately as cooling area while the other part serves as heating area. Before a segment switches from heating the exhaust air to cooling of the purified gases, the relevant segment is purged, to remove the remaining untreated gases in this process. Subdivision into individual segments allows the system to be operated with a very low purging air flow rate, resulting in lower operating costs and a more compact installation.
A rotating distributor patented and developed specifically by EISENMANN, acting as an air distribution system, which controls continuously alternate the flow of exhaust air and purified gas through the individual heat exchanger segments and flushing of these segments prior to switching.
The rotating distributor replaces a complex flap system and pneumatic switchover flaps with related complex control system could be left out.
EISENMANN`s single reactor-system with rotary valve technology has compared to the 3-tower-RTO a much smaller foot-print , no need for compressed air and works without pressure fluctuations
The exhaust air passes vertically upward through the heat exchanger mass taking on the heat and raising the air temperature. The oxidation of the pollutants takes place at the surface of the ceramic heat exchanger mass at approx. 850°C. The hot purified gas passes the burning chamber, where additional fuel is burned with a gas fired burner.
The hot purified gases then pass through the other section of the heat exchanger mass from top to bottom, consequently cooling down. The relevant purging segment between the heating and cooling area is purged to remove the remaining untreated gases in this process.
Exhaust air preheating across the regenerative heat exchanger achieves a temperature difference of approx. 50 K between the emerging cooled purified gas and the entering exhaust air.
Finally, the purified air will be discharged to the chimney.
