Polyimide chemistry
High Temperature Filtration in cement plants
The highly efficient filter media made of polyimide fibers P84® from Evonik keep the release of dust particles during cement production below emission limits.
Concrete is a jack of all trades among building materials - versatile and effective. In addition to water and other components, it consists of cement, which is produced in energy-intensive special cement kilns. The highly efficient filter media made of polyimide fibers P84® from Evonik keep the release of dust particles during cement production below emission limits.
FILTER MEDIA FOR EFFICIENT HOT GAS CLEANING in cement plants
High filtration efficiency
Changing flue gas conditions are caused by using a variety of fuels, as well as switching the kiln filter from direct mode to compound mode. High CO and Volatile Organic Compounds (VOC) values can be generated by the extensive use of secondary fuels in the precalciner. The partly abrasive dust is a crucial parameter for the filter media in terms of delamination. Because of the high alkaline content, the bypass filter is a true challenge for the filter media.
The ever increasing demand for higher cement quality is a challenge for the grinding system and the high amount of fine dust requires a highly effective filter media. Therefore P84® based filter media can be found in following filter units of a cement plant.
- Kiln Filter: P84®
- Clinker Mill Filter: P84® blended with PET and PAN
- Alkali Bypass Filter: P84®/PTFE blends
- Clinker Cooler Filter: P84®
To reduce fine dust particle emissions to the required emission limit, filter bags are used for hot gas filtration – for example made from the high-temperature-resistant polymer by Evonik. P84® polyimide fibers are well known for their high filtration efficiency thanks to their multi-lobe design and high surface area. They retain a much higher permeability throughout their lifecycle. This results in significant reductions in the energy consumption of the fan that keeps the gas flow at a constant level.
Filter media made of P84® polyimide fibers by Evonik therefore not only cut back on fine dust particle emissions, but also reduce energy costs.
Worldwide, more than 150 cement kilns are cleaned with P84® filter bags. In China alone, about 100 cement plants rely on polyimide fibers from Evonik. Based on the energy savings, the reference plants of Evonik reduce CO2 emissions by approximately 60,000 metric tons a year.