Stellite™ Refinery & FCCU
Kennametal Stellite manufactures solutions that extend component life, reduce unplanned down time, and decrease maintenance expenditures. Typical applications in the refinery industry include nozzles, thermowells, valves, and pump components.
To meet customer needs, Kennametal Stellite rapidly develops and supplies a finish machined component utilizing one, or more, of the following processes:
High-Temperature Erosion Resistance
Stellite™ alloys are noted for their high-temperature erosion resistance in a multitude of industries. In petroleum refining, the reactor and regenerator sections of the FCCU’s pose severe erosion problems.
During an accelerated wear test at regenerator temperatures (700ºC), using an FCCU catalyst as the erosive media, Cobalt-based alloys such as Tribaloy™ T-800™ and Molybdenum-containing alloy Stellite™ 720, showed a significant engineering advantage over 304, 410, and boron diffused 410.
These Cobalt and Molybdenum alloys provide an exceptional blend of high-temperature sulfidation, oxidation, and erosion resistance. In even more demanding situations, alloy matrix composites such as Stellite™ TiC20 are candidate materials.
A variety of nozzle configurations are used in refining and petrochemical processing to handle the injection and introduction of steam, air, hydrocarbon feed, coke, and various other chemicals. Nozzles must be designed to retain their dimensional and structural integrity from turnaround to turnaround. Abnormal erosion or fracture can seriously jeopardize process safety and the economics of the operation.
Typical examples of wear-resistant nozzles that Kennametal Stellite™ manufactures include riser/reactor feed nozzles, regenerator air nozzles, steam stripping nozzles, orifice chamber nozzles, and fluid coker nozzles.
To facilitate field installation, nozzles may be supplied as bimetallic cast components (the nozzle itself is a Stellite™ casting and the saddle is 304 SS).
Of all metallic components in the refining and chemical processing industry, thermowells are exposed to the most severe of environments and, as such, require special attention. Flame spray or welded coatings of Stellite™ 6, 12, or 1 are often employed as a first line of defense in extending service life. Further enhancements to service life are achieved by utilizing Stellite™ 6 or 12 cast components.
Maximum life is realized from a combination of Stellite™ castings overlaid with Stelcar™ coatings such as T-800™ (Tribaloy™), JK125 (chromium carbide) or JK117 (tungsten carbide). Thermowells, UltraFlex™ coated with the Mo-containing Stellite™ 700 series alloys, combat napthanic acid corrosion in vacuum distillation and hydrochloric acid corrosion in catalytic reformers.
As metal-to-metal wear is accelerated at high temperatures, valve trim, such as plugs, balls, gates, seats, stems and slides, must be manufactured or repaired with alloys that exhibit good hot hardness to resist the effects of high-temperature softening.
A variety of solutions are available, ranging from UltraFlex™ cladding and coatings, to castings and powder metallurgy parts for smaller components.
Cobalt alloys such as Stellite™ 6, 12, and 1 have been used extensively for years on large control valve seats and slides. While these alloys continue to work well, Tribaloy™ alloys and composites such as Stellite™ CrC50 and Stellite™ TiC20 are designed to resist even higher temperatures. Tribaloy™ T-800 is used for valves operating in MTBE service.
Pump casings may be cast or selectively thermally sprayed with various Stellite™ alloys. Casing life may be further extended with the use of replaceable pump liners manufactured from Delcrome™ alloys (for low- temperature service) or Stellite™ 6 liners (for more corrosive or high-temperature service).
Pump impellers that experience high levels of cavitation (such as boiler feed pumps) may be cast from cavitation- resistant alloys Stellite™ 6 and Stellite™ 21. Both open and closed impellers may be cast from Stellite™ alloys with further enhancements in wear and corrosion protection being provided by selectively thermally spraying high-wear areas.
Wear rings are generally hardfaced with Stellite™ 6 or Deloro™ 60 (in HF service). In severe wear environments, wear rings are thermally sprayed with Stelcar™ alloys that incorporate carbides of tungsten (JK117) or chromium (JK135). Mechanical seal faces may be thermally sprayed with Stelcar™ alloys containing tungsten carbide.