Primary Reforming Flowsheets

By:

Gerard B. Hawkins Managing Director

Simplified Steam Reforming NH3 Plant

H2O

H/C feed

H/C purification

Removes impurities (S,

Cl, metals)

Steam reforming

Converts to H2, CO, CO2 +

H2O + CH4

H2O

Shift

WGS reaction: H2O + CO <=>

CO2 + H2

H2 Hydrogen

purification

Removal of CO, CO2 + maybe CH4

Simplified Steam Reforming NH3 Plant (cont.)

N2

Ammonia synthesis NH3

Converts N2 + H2 => NH3

Syngas compression

H2

Steam Reforming Section - Options

Generally • feature tubular reformer (“primary”;

“steam reformer”) • may include 2nd or 3rd stage to the

reforming section pre-reformer

• part of initial design or later retrofit post reformers

• two types usually considered • secondary • gas heated reformer

Steam Reforming Section - Options

H/C feed

Pre- reformer

Converts to H2, CO, CO2 +

H2O + CH4

Secondary reformer

Drives CH4 slip down +

other fact0rs

H2O

Steam reformer

Converts to H2, CO, CO2 +

H2O + CH4

H2O Air or O2

Steam Reforming Section - Options

What proportion of plants feature all three parts ?

Many ammonia plants • Topsoe units with pre-reformer (e.g.

India) • Uprate options which add a pre-

reformer for capacity and efficiency gains (e.g. ABF; Kemira)

Carbon

Gas Phase Polymerisation

Steam Reforming Section - Reactions

General reaction scheme

H2O

CxHy CO/CO2/H2

H2O

Olefins Catalytic H2O

Steam Reforming Section - Tubular Steam Reformers

Design based upon • overall strongly endothermic reaction

requires large heat input • process gas through catalyst filled tubes • tubes located in fired furnace

Various designs dependent on process designer and plant

Tubular Steam Reformers - Ammonia

Designs • 200 - 500 tubes arranged in rows • downflow usually

upflow rare • capacity range (approximate)

500 – 3300 mtpd • differing designs favoured by certain

contractors top fired side fired terrace wall

Tubular Steam Reformers

Top fired designs • Technip; Linde; Uhde; Kellogg; Davy;

Lurgi multiple rows of tubes

TUBE

Tubular Steam Reformers

Side designs • Topsoe; Chiyoda; Selas (historic)

long single row of tubes

Side Fired

Tubular Steam Reformers

Terrace wall designs • Foster Wheeler

two cells, each with a long single row of tubes

Terraced wall