Nickel alloy quadruples chemical reactor vessel life
Nickel alloy quadruples chemical reactor vessel life
Keywords Alloys, Corrosion resistance,Nickel, Nickel Development Institute
Two chemical process reactors, constructed of a new nickel-chromium-molybdenum alloy, are expected to quadruple vessel life and improve reliability, reports the Nickel Development Institute, Toronto, Canada. Designated N06059, the alloy has composition Ni,0.1-0.4 A1, 0.01 C, 0.3 Co, 22-24 Cr, 1.5 Fe, 0.5 Mn, 15-16.5 Mo.
In one application, a midwestern chemical company was experiencing severe corrosion in its reactor vessels, which produce chlorinated and fluorinated intermediates. These chemicals contain various hydrocarbons, sulphuric acid, ammonium fluoride, and catalysts at temperatures of 95°C (200° F). Because they operate at high pressure, the vessels must be replaced when the walls corrode to a specified minimum thickness.
The presence of fluoride ions ruled out the possibility of tantalum, titanium, zirconium, or glass in the construction of the vessels; therefore, low-quality nickel alloys had been used. However, these corroded at rates of 6.25-8.75mm annually, requiring vessel replacement every 14 months.
The first 9840l (2,600 gallons) vessel constructed of N06059 has been in service for over 34 months,and reportedly continues to perform well. The annual corrosion rate has been approximately 0.88 to 1.85mm. The lack of any tungsten or copper, and the low iron content of the alloy are said to account for the high corrosion resistance and thermal stability.
Further information from the Nickel Development Institute, 214 King Street West, Suite 510, Toronto,Canada M5H 3S6. Tel: +1 416/591-7999.
