Foster Wheeler Hydrogen Production

Presented By: Ashok Paliwal 12210008

Contents Introduction Need of Hydrogen Hydrogen Production Steam Reforming Terrace Wall Steam

Reformer Conclusion

Introduction Hydrogen use has become integral feature of

most refineries. This has been made necessary by the

increase in hydro treating and hydrocracking, including the treatment of progressively heavier feed stocks.

As hydrogen production grows, a better understanding of the capabilities and requirements of the modern hydrogen plant becomes ever more useful to the refiner..

NEED OF HYDROGEN

There has been a continual increase in refinery hydrogen demand over the last several decades. This is a result of two outside forces acting on the refining industry: environmental regulations and feedstock shortages.

Refiners are left with an oversupply of heavy, high-sulfur oil, and in order to make lighter, cleaner, and more salable products, they need to add hydrogen or reject carbon.

Within this trend there are many individual factors depending on location, complexity of the refinery, etc.

HYDROGEN PRODUCTION

Hydrogen has historically been produced in catalytic reforming, as a by-product of the production of the high-octane aromatic compounds used in gasoline.

Where by-product hydrogen production has not been adequate, hydrogen has been manufactured by steam reforming. In some cases partial oxidation has been used, particularly where heavy oil is available at low cost.

The heavier and the sourer the crudes, the larger the hydrogen requirement.

HYDROGEN PRODUCTION Steam Reforming. In steam reforming, light

hydrocarbons such as methane are reacted with steam to form hydrogen:

CH4 + H2O→ 3H2 + CODELTA H = 227 kJ/ (g.mol), where DELTA H is the heat of reaction.

The reaction is typically carried out at approximately 870°C over a nickel catalyst packed into the tubes of a reforming furnace. Because of the high temperature, hydrocarbons also undergo a complex series of cracking reactions, plus the reaction of carbon with steam.

HYDROGEN PRODUCTION Carbon is produced on the catalyst at the same time that

hydrocarbon is reformed to hydro- gen and CO. With natural gas or similar feedstock, reforming predominates and the car- bon can be removed by reaction with steam as fast as it is formed. When heavier feed stocks are used, the carbon is not removed fast enough and builds up. Carbon can also be formed where the reforming reaction does not keep pace with heat input, and a hot spot is formed.

To avoid carbon buildup, alkali materials, usually some form of potash, are added to the catalyst when heavy feeds are to be used. These promote the carbon-steam reaction and help keep the catalyst clean. The reforming furnace is also designed to produce uniform heat input to the catalyst tubes, to avoid coking from local hot spots.

HYDROGEN PRODUCTION After reforming, the CO in the gas is

reacted with steam to form additional hydrogen, in the water-gas shift reaction

CO + H2O → CO2 + H2 DELTA H =(-38.4 kJ/(g.mol)

Steam Reforming-based Technology

Fig. 1 - Hydrogen production plant process flow schemeSteam

Deaerator

CWTerrace WallTM

Hydrogenatorreformerming

Shift reactor

8

Steam drum

Hydrogen

PSA

DesulphuriserPre-refor

msteam

Comb. air

Air preheating Waste heat boiler

Make up waterNatural gas

Steam

Steam drum Hydrogen

Deaerator

PSA

Steam Reformer CW

D l h i T W llTerrace WallTM

Steam Reforming-based Technolgy

Hydrogenator Desulphurize

r ng

Shift reactor

Hydrogen Desulphurization Section

• Feedstock is hydrotreated and resulting H2S is captured in a zinc oxide bed.

• Different schemes are available - the most commonly used is the lead–lag arrangement followed by a polishing

• Reaction temperatures are obtained by thermal exchangeDesulph

Pre-refor

mi

Comb. Air

Air preheating Waste heat boiler

Make up wate9r

Natural gas

Steam drum Hydrogen

Deaerator

PSAf i ti i b fi i l t f i d t

am Reformer CW

D l h i T W ll

Steam reforming based Technology

Hydrogenator Desulphurize

rTerrace

ng

Shift reactor

Prereforming Section• Pre-reforming section is generally installed to eliminate the long-chain hydrocarbons.

In heavier feedstocks before entering the reforming section• When natural gas is used as feedstock

the pre-reforming section is beneficial to a reforming duty reduction thus lowering the investment cost of the reformer

Ste

Desulph

Pre-refor

mi

Terrace Wa llTM

Comb. air

Air preheating Waste heat boiler

Make up wate10r

Natural gas

flow scheme Steam

team drum Hydrogen

WallDeaerator

PSA

t f

Steam Reforming-based Technology

section

CWWallTM

steam reformer

Hydrogenator Desulphurize

r ng

Shift reactor

• Key section of plantS

• Uses FW proprietary Terrace-WallTM

technology• Steam reformer outlet temperatures up to

920°C can be used

Terrace-Desulph

Pre-refor

mi

steam

Comb. air

Air preheating Waste heat boiler

Make up wate11r

Natural gas

Hydrogenator Steam Refor D l h i T W llDesulphurizer Terrace

WalPre-Reforming

ITS

Comb. Air

Steam Reforming-based Technology

Steam

CW

Shift reactor

Steam drum

Hydrogen

Syngas cooling and shift reactionThe syngas cooling section is normally optimized using pinch technology.

Deaerator

PSA

mer

lTM

Air preheating Waste heat boilerMake up wate12r

Natural gas

Press re S ing Absorption

ogenator Steam Reformer

D l h i T W llDesulphurizer Terrace WallTM

Pre-Reforming

Steam Reforming-based Technology

Steam

PSA section Deaerato

r

CWHydr

hift reactor

Steam drum Hydrogen

• Hydrogen purification is achieved using Prssure Swing Adsorption(PSA)

PSA

S

Comb. air

Air preheating Waste heat boiler

Make up wate13r

Natural gas

Terrace Wall Steam Reformer Side-fired heater with burners located along

lateral walls with flames vertically arranged. Radiant section comprising a firebox with a

single row of catalyst tubes with two terraces on both sides of the tubes on which the burners are installed.

Catalyst tubes are flanged at the top to allow loading and unloading of the catalyst.

Key Advantages The inclined ‘terrace walls’ are uniformly

heated vertically by the rising flow of hot gases.

Each terrace capable of being independently heated to provide the particular heat flux desired in its zone.

Molecular and radiant convention sections reducing construction time and cost.

Key Advantages Can operate in natural draft mode

keeping the full hydrogen production. Very compact design reducing the plot

area.

Leading to:• Lower operating cost• Lower maintenance cost• Lower investment cost

Conclusion Hydrogen is vital for a modern refinery

operation Hydrogen generated as by-product in the

refinery process units is not enough to cover needs. Additional reliable hydrogen must be produced.