Extrusion followed by hot air drying is one of the widespread production utilities within the pet food and aqua feed industry. In the extrusion process 10% – 20% water is added as a process aid, and this water is removed again in dryers; typically, hot air dryers. The energy consumption of the drying process varies from 45% – 60% of the total process energy, dependent on the dryer type. Unpleasant odorous components are released in the dryer and in the extruder flash off.
This new technology EWOTEC separates water from the dryer and extruder flash off. Many of the odorous components are water-soluble and will follow the separated water and improve the air quality from the dryer and extruder. Fine dust particles will follow the separated water and improve the air quality. Part of the latent heat from the separation is recovered in this process and will bring the process energy consumption down. Finally, all or part of the separated water can be reused in the extrusion process saving water and dry matter.
EWOTEC is a concept for energy reduction, water reduction and satisfies the costumer’s individual requirements for odor emission reduction.
The basic concept for the EWOTEC solution started with a project team including “Ministry of environment and food of Denmark”, and a fish feed and a pet food manufacturer. This concept has now been developed and tailor made solutions can be offered for existing as well as new factories.
- Condensates water from the dryer and flash off air
- Recovers energy and sends it back to the process
- Reduces odor
- Reduces dry matter loss
EWOTEC Air Clean:
- EWOTEC Basic
- Adjusts air conditions for specific final air treatment
- Final air treatment designed for local requirement
- EWOTEC Basic
- Heats pump systems for optimal Energy recovery
EWOTEC Basic is a technology used in all 3 EWOTEC solutions.
- Heat exchanger 1 (Air to water) anti fouling with CIP system
- Heat exchanger 2 (Air to water) anti fouling with CIP system
- Heat exchanger 3 (Air to water) finned heat exchanger
- Cooling tower
Process air from the dryer and flash off passes heat exchanger 1. In heat exchanger 1 some of the latent heat is taken out and transferred to heat exchanger 3 . Heat exchanger 3 heats up the make up air to the dryer. The air passes to heat exchanger (H2), the water side is associated with a cooling tower. Another part of the latent heat is removed here, and this will condensate part of the water in the process air. This condensate can be used as water in the extruder.
EWOTEC Air Clean uses the EWOTEC Basic concept with a final odor reduction system and/or a stack to control the emission. The stack height will be determined based on the odor emission, the geographical conditions and the metrological conditions. For the final odor reduction we can choose Biofilter, Carbon filter or Ozone. The emission will be reduced by 90 – 95% and the stack height can be from 0 to more than 150 ft. depending on the local requirements.
EWOTEC MAX uses the EWOTEC Basic concept with the use of heat pump technology. The system will give approx. 80% recovery of the drying energy. The odor reduction will be up to 65% and the water reduction will be up to 100%. With the EWOTEC MAX it will be necessary to find an external energy consumer to use the recovered energy.