Premature Degradation and Failure of Steam-Methane Reformer Heater System Components

Abstract

Bulk hydrogen production in a petroleum refinery by steam–methane reforming utilizes high temperatures, moderate pressures and catalyst – filled tubes which generate high tube temperatures of up to 1,690 °F [920 °C] imposing relatively harsh performance demands on system components which are not usually encountered in other refinery or petrochemical plant equipment. Creep rupture and high temperature cycling place a severe service duty on the catalyst tubes, tube outlet pigtails, the subheader train and the downstream steam generator leading to ruptured pigtails, cracking in sub-headers and break up of the ceramic tube sheet ferrules at the steam generator inlet tubesheet. Although the industry has developed specific fit-for-purpose design practice standards augmented with detailed technical reports, reliability issues persist and regularly force premature shutdown of the reformer heater and downstream heat recovery equipment. Among these practices are API Standard 530 and API TR 942-A. API 530 assists designers in the selection of materials and determination of pressure design thickness of heater tubes while API TR 942-A attempts to reconcile the contradictory industry experience where some operators have little or no problems while others suffer premature degradation and cracking of outlet pigtails and manifold components. A reconciliation between application of industry design practices and equipment performance is presented in this paper to determine whether systemic issues contribute to the apparent situation; and, recommendations are made for pressure component design and material selection for steam-methane reformers.