Customer profile
A large steel producer in China, operating a shaft furnace for pellet combustion, wanted to reduce its excessive particulate emissions due to environmental regulations. Despite using 1152 polyester bag filters with ePTFE membranes, the plant was struggling to keep dust emissions below the legal limit, consistently recording levels above 20 mg/m³.
With increasing requirements to reduce emissions below 5 mg/m³, the company was looking for a more efficient and sustainable filtration solution to meet compliance standards and improve operational safety.
Location: China
Dust type: iron oxide, manganese oxide
Key Results
- 80% decrease in emissions
- 50% increased filtration surface
- 4m shorter filter resulted in a larger Dropbox and less abrasion
- Lower pressure drop (700 Pa after vs. 1800 Pa before)
High emissions and short filter service life
The system was equipped with 1152 conventional polyester bag filters with an ePTFE membrane, each 6 meters long. The emission values regularly exceeded 20 mg/m³ and were therefore well above the permissible limit value. The aim was to reduce emissions to below 8 mg/m³, which required a reduction of more than 60%.
In addition to compliance problems, the production facility also encountered the limitations of the existing filter system. These included a high pressure drop and insufficient cleaning performance.
To overcome these challenges, the company worked with Hengst Filtration to modernize its filtration system by replacing the traditional 6-meter bag filters with advanced pleated bag filters.
The challenges
- High emission levels
- Poor filter quality leading to rapid deterioration and shorter service life
- High differential pressure
- High energy consumption
Replacing existing filters with high-performance pleated bag filters
The filter system has been upgraded with the following filters:
Product type: CPB - Top-Loader Pleated Bag filter
Number of filters: 1152 pleated bag filters
Filter medium: Spunbond polyester with ePTFE membrane
Filter medium area: 5.6 m²
Significantly lower emissions, lower pressure drop and better cleanability of the filters
The filter system was upgraded with 1152 pleated bag filters with Top Loader, which are equipped with 5.6 m² of Spunbond pleated polyester media. This upgrade is in line with the Steel Group's focus on emission reduction and operational efficiency.
General system information
| System parameters | System data |
| Air flow in the system | 280,000 m³/h |
| Dust type | Iron oxide, manganese oxide (shaft furnaces for pellet combustion) |
| Operating hours of the system | 8000 hours/year (full year) |
Technical Specifications
| Before | After | |
| Filter model | Conventional bag filter | Top Loader CPB Pleated bag filter |
| Filter medium | Polyester with ePTFE membrane | Spunbond pleated bag made of polyester |
| Length [mm] | 6000 | 2000 |
| Number of bag filters / filter cartridges | 1152 | 1152 |
| Filtration area in each pleated bag filter / filter cartridges [m²] | 3 | 5,60 |
| Filtration area in the entire system [m²] | 3456 | 6400 |
| Emissions mg/Nm³ | > 20 | 3.9 (after 5 months of operation) |
| Pressure drop Pa | 1800 | 700 |
From high emissions to high efficiency
By using pleated bag filters from Hengst Filtration, the company not only improves its compliance with environmental standards but also achieves cost savings and increases the longevity and efficiency of its filter systems.
80% reduction in emissions
Emissions have been reduced to 3.9 mg/m³, which is significantly lower than the previous values of around 20 mg/m³ and below the target value of 5 mg/m³.
Reduced air-to-substance ratio and DeltaP
The air-to-substance ratio and DeltaP have been significantly reduced (from 1800 Pa to 700 Pa), resulting in considerable cost savings in fan energy consumption.
Advanced manufacturing technology
- Weltech technology: The use of ultrasonically welded tapes ensures a perfect fit and uniform pleat spacing, improving the overall performance and durability of the filters.
- Increased filter area: By switching to pleated bag filters, the filter area has been increased by 50%.
- Material improvement: The pleated bag filters are made of spunbond polyester, a surface filter medium that is more effective for pulse cleaning. As a result, the pressure drop (DeltaP) remains low over a significantly longer period of time compared to conventional felt media.
Get in touch
Contact our team for any questions and support regarding Filter Cartridges, Pleated Bags & Flat Cells
sales.nakskov[at]hengst.com