Design of Primary Reformer

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Posts: 1
Joined: Sun Jan 27, 2019 7:24 am

Design of Primary Reformer

Post by abhijuet » Sun Jan 27, 2019 8:37 am

How to design a Primary reformer (Reformer type: Top Fired) ??
Lets say for 200000 Nm3/hr of syn gas Production.

Posts: 3
Joined: Wed Jan 03, 2018 1:29 pm

Re: Design of Primary Reformer

Post by pbaboo » Tue Feb 05, 2019 1:24 pm

In the design of reformers , considerations must be given to following points:-
Tubes & burners shall be arranged in such a way that they will allow adjustment & control of temp. & heat flux along the tube length .Inlet & outlet system should be designed to allow thermal expansion of the hot parts without any risk of excessive stresses.Materials of construction shall be selected to ensure proper functioning & a long life. Primary Reformer tubes are designed on the basis that not more than 2.5% of the tubes will fail by creep in less than 100000 hrs under the application of steady state internal pressure.
Stresses occurring in the tubes
• Hoop stress due to internal pressure
• Thermal stress across the tube wall thickness due to temp. gradient
• Longitudinal stress due to internal pressure & weight of the catalyst
Randomly thermally induced stress due to sudden startups & breakdowns.
 Long term rupture strength at high strength to reduce wall thickness
 Long term rupture ductility to permit relaxation of high local stresses at startups & shutdowns
 Retained room temp ductility, if any repair welding is to be performed
 Creep strength to avoid bulging & distortion of of tubes under pressure
 Low coefficient of thermal expansion
 Good corrosion resistance
 Good conductivity
 Good weldability
 Carbon provides creep rupture strength
 Chromium provides corrosion resistance
 Nickel maintains the austenitic stability of the metal & also reduces the coefficient of thermal expansion making the metal more resistance to thermal fatigue
 Niobium contributes to carbide precipitation which is both fines & more stable
 Tungsten & Zirconium helps to form more stable protective oxide films on the surface of the tube bores
 -produce carbides which are more stable at higher temp. giving extended creep resistance
 -the beneficial effect of Nb in creating finer & more stable strengthening carbides is magnified
Prem Baboo
DGM(Production & Process)
Dangote Fertilizer Limited, Lagos, Nigeria

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