Method for reducing stress corrosion cracking in high-temperature regenerative air heaters

A process for providing blast air for delivery to a blast furnace, the blast air formed by heating air in one or more stoves, each stove of a type having an interior which includes a combustion chamber and heat storage means, the process comprising the steps of:

• (a) burning a mixture of gases provided by a stream of fuel gas and a stream of air introduced to the stove combustion chamber, which mixture in burning produces gaseous combustion products which fill the interior of the stove, which gaseous combustion products are substantially devoid of free oxygen;
• (b) storing a charge of gas within the interior of the stove when the stove is in a bottled condition, the gas charge being substantially devoid of free oxygen.
• whereby high-temperature blast air may be delivered from a stove previously-bottled under conditions which substantially alleviate stress corrosion cracking of the metalic shell of the stove.

A method for reducing stress-corrosion cracking in a blast furnace stove, where at least three of such stoves are connected in a parallel arrangement for providing blast substantially continuously to a blast furnace, wherein when each of the stoves operates in a three-phase cycle with a first stove in an on-gas phase, a second stove in a bottled phase and a third stove in an on-blast phase, the method comprising:

• storing within a stove in the bottled phase a charge of gas substantially devoid of free oxygen so as to reduce formation of nitrogen-containing oxides.