Tube inlet protection for secondary reformer waste heat boilers, without refractory cast at the tubesheet.
The alloy protects the tube end.
The ceramic head protects the tubesheet, and arrives finished.
A hybrid ferrule is a metal ferrule, the tube insert that lines the inlet of a boiler tube, combined with a precast ceramic head that covers the tubesheet in place of refractory cast on site. Blasch builds hybrid ferrules for secondary reformer waste heat boilers in ammonia and syngas plants, where the alloy sleeve protects the tube end and the ceramic head with fiber insulation protects the tubesheet. Because the ceramic is fired and dry when it arrives, nothing has to be formed or cured at the tubesheet.
Reformer boilers have long used metal ferrules. The question is what protects the tubesheet around them.
The refractory at the tubesheet stops being a job done inside the boiler and becomes a part made in a plant, so the outage no longer waits for it to cure.
The metal part is a tube insert in an alloy chosen for the gas temperature and chemistry. It can carry a tapered inlet or outlet, flares, flanges, slots, holes or stop pins, and an optional ceramic fiber wrap.
The ceramic head sits in front of the tubesheet. Blasch casts it to the geometry of the ferrule entrance and to the tube pitch, so the heads fit together across the whole tubesheet.
Behind the heads, ceramic fiber adds insulation that a castable layer of the same depth cannot give, and it keeps heat away from the tubesheet. Fiber is only possible because the precast heads bring no moisture into the boiler.
Together, sleeve and head protect against corrosion and erosion at the tube end, stress corrosion cracking and local pitting, and they keep the tube-to-tubesheet joint intact.
Three designs for tube inlets, from a plain alloy sleeve to a ferrule without any metal.
Alloy sleeves alone, for gas below about 1,650 °F (900 °C) and mild abrasion, replaced as a sacrificial part.
Alloy sleeve plus precast ceramic head, for reformer boilers that need the tubesheet insulated without cast refractory.
All ceramic, head and stem joined by a twist lock, for inlets where metal reaches its limits.
In ammonia and syngas plants, the gas leaving the secondary reformer is cooled in a waste heat boiler before it moves on through the process. The tube inlets of that boiler are traditionally protected by alloy ferrules in refractory cast during the outage, which makes the tubesheet one of the slower jobs of a turnaround. More on the parts Blasch makes for hydrogen and ammonia plants.
The tube outside diameter, wall thickness and pitch, the ferrule you use today, the gas temperature at the inlet and the thickness of the tubesheet. A drawing helps if you have one, but it is not required.
It is the same idea. The ceramic head protects the tubesheet, the metal sleeve protects the tube end, and each part is made from the material that suits its job.
Cast refractory depends on placement, curing and moisture in the field, and its curing time comes out of the outage. A precast head is fired and dry when it arrives.
Ceramic heads can also be combined with metal ferrules in other boilers that use them, such as syngas coolers after autothermal reformers. A Blasch engineer checks the temperatures first.
When the gas at the inlet is too hot for the alloy sleeve. Above about 2,300 °F, Blasch recommends an all-ceramic design such as ProLok.
Send the tube data and the ferrules you run today. A Blasch engineer designs the ceramic heads for your tubesheet.
