Currently, China’s annual coal consumption for thermal power generation is approximately 1 billion tons, and the emissions from power plants amount to about 4 million tons, representing 35% of the nation’s total industrial smoke and dust emissions. Notably, the emissions of fine particles (less than 10μm) exceed 3 million tons, posing serious threats to human health. An increasing number of thermal power plants are adopting bag filters, which enable boiler flue gas to be dusted using bags while ensuring the normal operation of the power plant’s generating units. The emission concentration of smoke and dust is maintained below 30mg/m3 (with membrane treatment, it can be reduced to less than five milligrams), meeting the new standards for smoke and dust emissions from thermal power plants and the requirements for total emission control.

Boilers are mainly divided into three types:

1. Stoker boiler

The most common type is the chain grate boiler. Excess air is introduced from below the coal layer, resulting in flue gas containing a large amount of coal ash and SO3. Fine coal ash particles can absorb a significant amount of SO3, which is prone to forming acid condensation. Special attention should be paid when selecting filter materials, and we recommend using PTFE deep impregnation treatment.

II. Fluidized bed boiler

In a fixed fluidized bed boiler, air enters from the lower part of the fuel layer, blowing the fuel layer into a boiling state.

In a circulating fluidized bed boiler, a large amount of particles are blown away from the fuel layer by the airflow. The combusted particles are separated by a material separator and returned to the furnace.

All fluidized beds allow direct injection of lime into the furnace, which can remove up to 90% of SO2 from the flue gas. The relatively low temperature results in lower NOx content in the flue gas compared to other combustion methods. Therefore, PPS, with its good cost-performance ratio, has become the optimal dust removal solution for fluidized bed boiler systems.

III. Pulverized coal boiler

The finely ground pulverized coal is directly fed into the furnace. The pulverized coal burns in a suspended state, but it does not reach the ash fusion point. As a result, a large amount of coal ash enters the flue gas, and the melted pulverized coal particles solidify into very small glassy spherical objects with extremely low carbon content. These particularly fine dust particles are difficult to collect. We recommend using microfiber, which can filter fine dust on its surface. Under high-temperature combustion conditions, it will generate high concentrations of NO2 gas. Consider selecting PPS, P84, or other high-temperature composite filter materials.