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POLITECNICO DI MILANO

Master of Science

Energy Engineering for an Environmentally Sustainable World

Fundamentals of chemical processes for energy and the environment

January 2012School of Industrial Engineering -Campus Piacenza

HYDROGEN PRODUCTION VIA PARTIAL OXIDATION OF HYDROCARBONS

Camilo Higuera

Marek Jakimowicz

Nicolas Alvarez

N.Guhan


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Contents

General introduction to hydrogen

Ways to produce hydrogen

Introduction to partial oxidation

Partial oxidation process description

Catalyst kinetics

Commercial and Environmental Aspects


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Hydrogen

MP : -259.14 deg c

BP : -252.87 deg c

Highest energy content of common fuels ona weight basis

Lowest energy content of common fuels ona volume basis


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Discovery of Hydrogen

1766 - Hydrogen was first

identified as distinct element

by British scientist Henry

Cavendish. He separated

hydrogen gas by reacting zinc

metal with hydrochloric acid.

Cavendish applied a spark to

hydrogen gas yielding water.

This discovery led to his later

finding that water (H2O) is

made of hydrogen and

oxygen.


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Hydrogen Production Paths


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Properties & Characteristics of

Hydrogen

Energy carrier

Diatomic gas. Colorless, odorless, nonmetallic, tasteless, non-toxic

and highly combustible.

Lightest element , so it can combine with otherelements.

Inflamability range with air 474%

Inflamability range with chlorine 595% Cooled and stored as a liquid at -253

oC

Can be stored as a gas. It must be compressed tobe stored efficiently.

Abundant, clean, efficient, and can be derived fromdiverse domestic resources


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Usage of Hydrogen


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Trends in the use of fuels

As fuel use has developed through time, the percentage of hydrogen content in the

fuel has increased.

Installed capacity worldwide: 600 Billion Nm/year


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World wide Demand of Hydrogen


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Current global hydrogenproduction

Hydrogen Consumers

48% from

natural gas30% fromoil

18% fromcoal

4% fromelectrolysis

of water

SOME STATISTICS


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Ways of Production

of Hydrogen

The Three ways of

Industrial Production ofHydrogen are as follows:

Steam Methane Reforming

Coal Gasification

Partial Oxidation of Hydrocarbons

Biomass Gasification

Biomass Pyrolysis

Electrolysis

Thermochemical

Photochemical

Photobiological

Steam MethaneReforming

Partial Oxidationof Hydrocarbons

Auto-thermalreforming (ATR)


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Partial Oxidation What is it?

Process used to produce Hydrogen from

hydrocarbons and oxygen.

EXOTHERMIC


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Partial Oxidation How it is done?

Fuels: LHC, HHC,coal, etc.

High

temperatures(1200 1500C).

Elevatedpressures (20 90

bars or above).

Temperature

moderator(steam).

No catalyst.

GASIFIERHEAT

RECOVERY

PURIFICATION

STAGES

CO

SHIFT

H2

SEPARATION


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Partial Oxidation What does it

involve?Substoichiometric fuel-oxygen mixture.

Secondary reactions:


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General Heat of Reaction is given by:

CnHm + (n/2)O2 nCO + (m/2)H2 (+heat)

H= -36 kj mol-1

nCO + (n)H2O nCO2 + (n)H2

H= -41 kj mol-1

CnHm + nH2O + (n/2)O2 nCO2 + (n+m/2)H2 (+heat)

H= -77 kj mol-1

[ n=1, m=4]

Thermodynamic aspects of Partial

Oxidation ( Methane )

Oxidation reaction

CO-shift reaction


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Partial Oxidation Process

Commercial processes: SHELL and TEXACO

General Process:

General Equipment:

GASIFIER HEATRECOVERY

PURIFICATIONSTAGES

COSHIFT

H2SEPARATION

REACTORHEAT

EXCHANGER

SCRUBBER

SULPHUR

WASHER

REACTOR PSA UNIT


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