Formidable fibres

The production of industrial goods, like cement, is necessary for the benefits of modern life: roads, hospitals, bridges, long-lasting buildings, walkable urban cities. One of the critical considerations for operators producing cement is to ensure that the harm to the environment is minimised. Every day, the industry gains new insights into its impact on the environment and ways to resolve those impacts. The US EPA recently proposed new standards that, if adopted, will require future reductions in PM2.5 emissions. This article will discuss the challenges surrounding the control of fine particle emissions like PM2.5 with the pulse-jet baghouse, and address the question as to whether operators can count on filter bags made from materials such as P84^® and P84 HT.

Cement plants are in the business of producing particles in the form of cement. Over the decades, the cement industry has taken many steps to mitigate and reduce the impact of particulate emissions on the environment. In 2015 – 2016, the Portland Cement NESHAP (commonly known as Cement MACT) required all existing US cement plants to reduce particulate matter emissions and control mercury emissions. The most common method implemented by cement plants for controlling these emissions is pulse-jet fabric filters on the kiln effluent and many other locations throughout a cement plant.

In January, the US EPA announced plans to continue its trend to reduce the ambient air quality standard for PM2.5 particles by lowering the annual ambient PM2.5 limit from 12 µg/m³ to between 8 and 11 µg/m³.

PM2.5 particulate consists of fine inhalable particles with diameters generally 2.5 µm and smaller.2 2.5 µm is very fine; it is about 30 times finer than the average human hair. The US EPA has estimated that PM2.5 emissions cost the US billions of dollars annually in public health impacts. As plants continue to optimise manufacturing performance and ensure that their product and other particulate is captured effectively, the total cost of ownership of pulse-jet collection systems increases.

The four factors of pulse-jet fabric filter cost of ownership

Pulse-jet fabric filters are widely accepted for use in cement plants. They prevent emissions of particulates into the atmosphere in various applications, from high temperature kiln, raw mill, and clinker cooler streams to lower temperature applications like coal mill, cement grinding, and storage silos. Regardless of the composition of the flue gas stream, all pulse-jets operate with the same basic design. The gas or air is induced under negative pressure into the dirty side of the baghouse. The dust laden gases impact filter bags suspended from a tube sheet. Periodically, a blast of high-pressure air is injected into the clean side of the bag, causing the bag to pop and shed the dust layer into the hopper. The cleaned air then exits the filter unit from the clean side where it is typically released into the atmosphere.

When fine particles penetrate the filter media, the pulsing system is unable to effectively remove the particles. Over time, as the bag blinds, the residual pressure drop increases, causing more frequent pulsing. Blinded bags add significantly to the total cost of ownership of operating a filter unit.⁴ Selecting the right filter media for an application is critical to the operational success of a plant.

Enjoyed what you've read so far? Read the full article and the rest of the October Issue of World Cement by registering today for free!

Read the article online at: https://www.worldcement.com/special-reports/25102023/formidable-fibres/