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How do baghouses help control coal combustion pollution?

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coal utilization Cross-regenerative coke oven. (A) Cross section, showing the alternating arrangement of flue walls and ovens; (B) longitudinal section, showing (left) a series of combustion flues in a single flue wall and (right) part of a long, slotlike oven.

In the context of coal utilization, baghouses—also known as fabric-filter dust collectors—are highly efficient devices used at power plants to control air pollution by removing suspended particulates from exhaust gases.12

How Baghouses Function

A baghouse consists of an enclosure containing an array of long, narrow fabric bags. As dust-laden air from coal combustion is blown upward through the unit, the particulates are trapped by the fabric filters, allowing clean air to exit at the top.1

Key aspects of this process include:
* Efficiency: These systems can remove nearly 100 percent of particles as small as 1 μm and a significant fraction of even smaller particles.1
* Dust Cake Formation: In many designs, the filter acts as a substrate for a layer of accumulated dust, known as a "dust cake," which captures the majority of the particulates.1
* Maintenance: To maintain airflow, the bags are periodically cleaned by mechanical shaking, air reversal, or pulses of air. The collected dust falls into a hopper for disposal, often in a landfill.12

Because coal combustion produces hot exhaust, the gas must typically be cooled before entering the baghouse to protect the filter fabric.1