secondary reforming burners

History Design Operational Improvements Fabrication Delivery Installation

Contents

Ring burners have been around for a long time, in fact nearly 25 years

Prior to this shower head types have been used Straight pipes with simple mixers can be used

providing long necks exist

In the Secondary Reformer process gas is mixed with air

This provides the nitrogen necessary for ammonia synthesis

The reaction can be described as taking place in two parts: ◦ combustion of hydrogen ◦ reforming of methane

Combustion of hydrogen provides the heat required to achieve a very low exit methane concentration

CH4 + 2CO = CO2 + 2H2O

2H2 + O2 = 2H2O

Exothermic - gives out heat

Flame 2500oC mixed gas 1500oC

Gas feed very hot > 630oC

Gas feed contains hydrogen

Gas ignites automatically

Autoignition >615oC

No need for spark or pilot

Must maintain gas above 615oC

Only 20% of flammable gas is burnt

Excess methane is left

Remaining methane reforms with steam

Oxygen increases temperature

Reverse of normal combustion

After combustion gas at 1500oC

Hot enough to react in gas volume

Gas will cool to 1100oC - 1200oC

Substantial amount of methane reacts

Steam reforming CH4 + H2O = 3H2 + CO

Endothermic - cools down gas

Water gas shift

CO + H2O = CO2 + H2

Slightly exothermic

Catalyst completes reaction to 950oC

Exit methane content approx 0.5% (dry)

Catalyst is Ni on ceramic

Can be ringed or shaped catalyst as for Primary Reformer

Bit of black art, originally Now backed up by some science Process calculations are carried out for flows in gas

side, air side ensure pressure drops not too large CFD has improved our designs immensely, but is

expensive Mixing and proportions are important All designs are similar but not Identical Velocity exit nozzles is important

780°C

450°C

2500°C

? ~1500°C

1100-1200°C

950°C

? ~1500°C

1100-1200°C

1300°C

Pipe design

Shower Head

TI

TITI

Gas from Primary

Gas to Process

Water inlet

Water inlet

Steam vents

Oxygen inlet

Catalyst

Arch

Waterjackets

Burner gun

Refractory

Distributor

All materials are Incoloy 800 (UNS 8810) (Alloy 600 is not stronger or more temp resistant at these operating temps, only more expensive)

Oxidation resistance is very important Special Heat treatment ◦ To ensure oxidation resistance is maintained ◦ Improve the grain structure, improve creep resistance

Some components are tightly bent, grains become flattened and weaker. Typically around manifolds and feeders, we correct this.

Equipment needs to be a good fit to prevent damage

Top hung in the unit, hence why central pipe is thick

Site welding is carried out by customer, we provide weld procedure,Customer provides weld procedure qualification, Consumables

Better Mixing Reduced Methane Slip 0.5-0.3% or better Improved Catalyst Performance better bed usage

Bending of manifolds is difficult, require skill Welding needs to be well controlled, distortion is an

issue Flow Straighter is Laser cut, SS cannot be flame cut,

plasma cutting needed; this distorts the plates (end up looking like pringles

Not the norm around the world, however this has become the norm in FSU

Sufficient detail on the drawing to allow competent operator to install

Welded on site, the unit and lowered in. Take care with dimensions, try to obtain “As Built”

drawings

Proposal 0.2Place order 0.1Process Design 1Mechanical Design 1Client Approval 1Fabrication 9Delivery 2

Weeks 14

Weeks

We try to achieve 10 weeks ! Raw materials are on 6 weeks delivery !!!!!!

Delivery usual methods Sea/Road, Air is expensive

Weight approx 1.2 te Packaging:- crated and sealed Need to allow 2 weeks In Europe/FSU ROW 6 weeks Shut downs can be decided in 14 weeks !