Objective
Solaft was challenged by a large Brazilian cement group to design a fiberglass filter sleeve with PTFE membrane that would exceed the service life traditionally accepted as standard in the market.

Issue
The bag filter installed in the clinker furnace was dimensioned with design parameters very close to the agreed maximum limits. With this, the fiberglass filter bags with PTFE membrane undergo excessive cleaning to maintain the filter load loss, reducing their service life and generating frequent stops for punctual changes of damaged bags.

Solution
A technical visit was carried out to collect equipment and process data to map the critical aspects that influence the useful life of the filter bags. Dimensional adjustments were made in the design of making the filter sleeves, operational recommendations, and selection of the appropriate filter medium for this application.
After discussing the proposed changes, it was decided to test in a compartment before fully homologating the solution, being monitored the operational parameters and service life.

Outcome
The solution proposed by Solaft provided in 2017 exceeded the useful life of all other manufacturers, standing out from the others, generating high availability and reliability in the operation of the equipment.

Objective
Solaft was consulted by a cement industry in Brazil to present a study of the options available to eliminate the existing operational bottlenecks in the coke milling process.

Issue
The operation of the coke mill was limited by the high pressure loss of the bag filter. The recent optimizations of the production process resulted in an overload in the filtration system, which operated with operating parameters higher than the project, such as the filter rate above 1.8 m/min and operation of the pressurized mill. In addition to the operational problems, the low service life of the filter element reduced the availability of the equipment.

Solution
The technical proposal of Solaft was elaborated to eliminate the existing bottleneck by increasing the filter area obtained with the replacement of conventional sleeves by StarBags™. In this way it would be possible to reduce the pressure differential, reduce energy consumption and return the mill production to its nominal capacity.

Filter operation before upgrade:
• Sleeve life: 3 months.
• Filter rate: 1.8 m/min.
• Mill production: 5 ton/h, being the designed 7 ton/h.
• Pressure differential reached 260 mmCA in two months of operation.

Planned filter operation requirements after upgrading to StarBags™:
• Increased filter area by 115%, replacing 672 filter bags diameter 127 x 3540 mm by 672 StarBags™ diameter 120 x 3500 mm.
• Reduction of the filter rate to 0.85 m/min.

Operation of the filter after installation of the StarBags™:
• Reduction of differential pressure to 80 mmAC in the first three months, reaching 180 mmAC after twelve months of operation.
• Production of each mill went from 5 to 10 ton/h, generating an additional 3 ton/h above the project values.

Outcome
The StarBag™ technology adopted in 2018 is homologated in this application, providing the expected benefits and without the need for costly investments in equipment alteration.

Objective
Solaft was consulted by a cement industry in Germany to present a study of the options available to increase the capacity of a bag filter without the need to purchase new equipment.

Issue
The bag filters had reached their maximum capacity and required an expensive refurbishment to meet the new production demands. There was a planned 25% increase in airflow and dust load due to the changes in the plant, and a high-pressure differential would be unacceptable. The cost of a new reform of the bag filter was estimated at 1 million euros.

Solution
Solaft’s technical team determined that StarBags™ would fit the requirements. The increased filter area compared to conventional sleeve and the unique design allows for greater particulate retention, lower cleaning frequency and reduced energy consumption. An on-site test was then conducted.

Filter operation before upgrade:
• Operating at 1860 Am3/min at 90°C and 933 mbar static pressure.
• Filtration rate was 1.57 m/min.
• The differential pressure was controlled at 14.5 mbar.
• The powder load was approximately 2.7 g/Am3 (or 3.6 g/Nm3 or 300 kg/h).
• The cleaning pressure of the filter bags was 6 bar.
• Operating at a cleaning frequency of 3.3 cycles/hour (pulsing at 11 seconds).

Planned filter operation requirements after upgrading to StarBags™:
• Airflow = 2312 m3/min during normal operation and 2870 m3/min during production peaks.
• Gas temperature = 90°C.
• Dust concentrations remain unchanged.
• Particulate emission target: 10 mg/Nm3.

Operation of the filter after installation of the StarBags™:
• Pressure differential from 8 mbar to 110,000 Am3/h (Filter rate = 0.94 m/min).
• Pressure differential from 4 mbar to 90,000 Am3/h (Filter rate = 0.77 m/min).
• Particulate emission reached <10 mg/Nm3.
• Filter inlet temperature: 80 to 85°C.

Outcome
After successful testing, some benefits for this cement industry were observed:
• Reduction of the filter rate.
• Reduction of particulate emissions, achieving the expected objectives.
• Significant reduction in cleaning frequency.
• Energy savings due to lower cleaning frequency and lower fan amperage.
• 25% increase in gas flow.
• Cost-Saving Solution: Achieving Investment Savings through StarBags™ Filter Elements.
By investing just 65.1 euros in new StarBags™ filter elements, we avoided the need for purchasing a new filter system, which would have cost millions of euros.