Objective
Solaft was challenged by a large international steel group to solve the problem of frequent shutdowns for corrective maintenance due to operational failures in the filter sleeves.

Issue
The aggressive chemical conditions of the process prematurely degraded the filter sleeves, causing mechanical damage and consequently the increase in the emission of particulates to values above the permitted limit. Frequent interventions were necessary to correct the problems, generating system unavailability and high maintenance costs.

Solution
A technical visit was carried out to collect data on the equipment, the process and the products used, to map the critical aspects that influence the useful life of the filter bags. Solaft conducted an initial test of filter bags for high temperature with 100% PPS felts, within internationally accepted specifications for this application.

Outcome
The constant technical follow-up service combined with Solaft’s global experience in large supplies to the original equipment manufacturer, were fundamental to achieve the expected result.

The solution proposed by Solaft in 2016 was approved, thus following the complete replacement of the filter bags in the three existing desulphurization systems at this plant the following year. The systems continue to operate with Solaft sleeves.

Objective
In order to solve frequent problems of low durability of the PCI filter sleeves and eliminate the constant corrective maintenance shutdowns caused due to operational failures in the polyester sleeves, a steel industry contacted Solaft to evaluate and suggest improvements in the running of the mills.

Issue
Bag filters in charcoal injection systems have aggressive conditions. The temperature, humidity and oiliness of the coke from the process early degraded the polyester filter sleeves, causing losses of draught, mechanical damage and consequently the increase in the emission of particulates. Interventions were carried out to correct the problems, causing more constant stops.

Solution
To map the aspects that influenced the useful life of the filter bags, Solaft carried out a technical visit to collect data on the equipment, the process and the products used. Based on the information collected and suggestions proposed, a test was performed with filter sleeves with homopolymer acrylic felts and PrimaShield™ treatment.

Outcome
The trust placed in Solaft for this test proved the effectiveness of the proposed filter bags. The sleeves made of homopolymer acrylic and PrimaShield™ treatment were approved by the customer in 2016 and later acquired for complete replacement of the filter elements of the steelworks’ reverse air filter. The filter continues in operation with Solaft sleeves, having durability of 2 years with excellent performance.

Objective
In a technical visit to an important steel mill in southern Brazil, a potential upgrade was identified in the technological platform of the filter bags used in the reverse air dedusting system of the steelworks.

Issue
The filter sleeves used by the customer in the reverse air filter were of obsolete construction with mesh-pattern filter fabric, with low dimensional stability and low retention. This construction generates an excessive stretching of the sleeves, making it impossible to tension, resulting in a great periodicity of exchange and high unavailability of the equipment.

Solution
The solution proposed by Solaft was the implementation of filter sleeves built in needled felt.
A prototype part was initially supplied for evaluation of dimensional stability. It was proven that after one year of installation there was no stretching, as opposed to what occurred with the “mesh” type sleeves. This result motivated the customer to move towards the complete replacement of the filter bags.

Outcome
Our long experience with felt bag applications in reverse air filters, has ensured the excellent performance of the proposed solution. The set of sleeves acquired in 2016 continues in operation without the need for interventions for changes or adjustments in tensioning.

The success of this case was extended to other units of the group with equivalent results.