HPH® Bell-Type Annealing Furnace for Silicon Steel Strip

Throughout the world, more than 8,500 LOI annealing bases have been installed. About 5,000 of these bases operate with HNx controlled atmospheres (5 % H2, 95 % N2). More than 3,500 bases use HPH® annealing technology with pure hydrogen annealing atmosphere. LOI is therefor also market leader in the field of high performance Bell-type Annealing Furnaces. 

LOI has installed more than 300 bell-type-annealing plants in more than 30 countries and these plants are producing approx. 45 million tons of wide, medium-width and narrow strip each year. 

In developing HPH® technology, LOI focused on the zero-error philosophy at the same time as building on existing furnace designs. As a result, even older Bell-type Annealing plants can be converted to HPH® operation. 

LOI HPH® technology ensures atmosphere dew points below -60 °C. The extremely pure hydrogen annealing atmosphere and precise temperature control bring considerable quality benefits with a wide variety of steel grades. 

BYPASS+JET cooling 

BYPASS+JET cooling allows highest productivity of the three cooling technologies designed by LOI. High efficient JET cooling hood is combined with a BYPASS system utilizing a gas-water heat exchanger to cool the process atmosphere directly. 

BYPASS+JET cooling requires no open water in the plant while at the same time the BYPASS-System is suitable for a variety of energy recovery options. 

More than 1,000 HPH®-bases with BYPASS+JET cooling technology have been built by LOI. 

JET cooling 

JET cooling technology does not require open water in the workshop. During cooling, specially designed JET nozzles ensure high air velocity perpendicular to the inner cover, ensuring high heat transfers, while the cooling speed can be controlled by frequency-controlled fans. 

More than 500 HPH®-bases with JET cooling technology have been built by LOI. 

SPRAY cooling 

SPRAY cooling ensures high productivity with low investment costs. After initial cooling by air, the inner cover is cooled with water. 

More than 2,000 HPH®-bases with SPRAY cooling technology have been built by LOI.