introduction – dr andrew beath - energy · pdf file11:00 inauguration of workshop by...

1

12th November 2006

Kolkata, India

�Dr Andrew Beath

�CSIRO Exploration & Mining

�Australia

�Dr Cliff Mallett

�Carbon Energy Pty Ltd

�AustraliaSupported by the Australian Government through the Asia Pacific Partnership (AP6) Coal Mining Task Force

Tutorial on Underground Coal Gasification (UCG)

Outline of today’s activities9:00 Session 1:

o Introductionso Fundamentals & UCG design

10:45 Morning tea11:00 Inauguration of Workshop by Shri Shibu Soren, Hon’ble Minister of

Coal, India & Keynote address by :Shri H.C. Gupta, Secretary (Coal)11:20 Session 2:

o Behaviour predictiono Process performance & economic viability

1:00 Lunch2:00 Session 3:

o Groundwater & surface impactso Site selection & characterisationo Social perceptions

3:30 Afternoon tea3:45 Session 4:

o Case studyo Discussion

5:00 Finish

12th November 2006

Kolkata, India

�Dr Andrew Beath


�Australia

�Dr Cliff Mallett



Session 1A: Introduction

Introduction – Dr Andrew Beath

Dr Andrew Beath is a chemical engineer with a varied range of experience in industry and research. Over the last 7 years he has developed models to predict the growth of UCG cavities and the product gas properties, as well as simulation of processes which could utilise the product gas.

Introduction – Dr Cliff Mallett

Dr Cliff Mallett is a geologist with a long and varied career in research. Until recently he was Deputy Chief of CSIRO Exploration and Mining, where he initiated the research programme into underground coal gasification. He is now Executive General Manager of Carbon Energy, a company launched to commercialise the outcomes of CSIRO’s UCG research.

Research background

The CSIRO UCG research programme commenced in 1998. The major outcome has

been a series of models and methodologies for:

oSite characterisation

oCavity growth and gas production

oGeotechnical behaviour

oHydrogeological flows

oOverall process performance

The rights to commercial use of these are now owned by Carbon Energy.

2

12th November 2006

Kolkata, India

�Dr Andrew Beath


�Australia

�Dr Cliff Mallett



Session 1B: Fundamentals

Fundamentals of Coal Gasification

�INPUTS

Coal

Oxygen/Air

Water

�OUTPUTS

Synthesis/Fuel gas

H2,CH4,CO,CO2

Char, Tar & Water

Heat

O2

Gas

Characteristics of UCG

�Underground coal gasification is like other coal gasification techniques, except that the geological strata form the reaction vessel.

�This adds a level of complexity to analysis of the behaviour of the process and leads to extra uncertainty due the geological environment.

A simple guide to UCG

UCG can be condensed to two areas of analysis that are indicated on the

next two slides:

�Reaction processes

�Physical site changes

Each can be considered separately, but it is interaction of these that makes UCG analysis complex.

Reaction Processes

Product gas

Drying, Volatile release &

Gasification

Drying & Volatile release

Combustion&

High temperatures

Gas reduction&

Moderate temperatures

Gas equilibrium reactions& Cooling

Drying

Feed gas

Physical Site Changes

Water Table

IncreasedPermeability

Surface subsidence

Water usage

Contamination

3

UCG Process- Start

Water tableLand surface

Start of UCG process

UCG Process- Growth

Water table

Land surface

Growth of UCG cavity

UCG Process- Cracking

Water table

Land surface

Cracking above UCG cavity

Stress cracking & increased permeability

UCG Process- Breakage

Water table

Land surface

Some roof fall into UCG cavity

Breakage & increased permeability

UCG Process – Closure/Collapse

Water table

Land surface

Roof collapse into UCG cavity

Subsidence

UCG Process - Recovery

Water table

Land surface Subsidence

4

Outline of key UCG topics

4. Site selection& characterisation

1. UCG Design &Behaviourprediction

2. Process performance& economic viability

3. Groundwater &surface impacts

5. Socialperceptions

6. Case studyanalysis 12th November 2006

Kolkata, India

�Dr Andrew Beath


�Australia

�Dr Cliff Mallett



Session 1C: UCG Design

What affects UCG design?

�Coal seam dip (slope)

�Coal seam depth

�Coal permeability

�Overburden properties

�Drilling capabilities

�Required production volume

�Restrictions on subsidence and groundwater consumption

�Process stability requirements

Historical UCG designs

�Vertical Wells

�CRIP (Controlled Retracting Injection Point)

�SDB (Steeply Dipping Bed)

�Knife edge CRIP

�Tunnel

Vertical wellsAir Product

Exhausted holes

CRIP (Controlled Retracting Injection Point)

Product

1st CRIP reactor

Air/Oxygen

2nd CRIP reactor

5

SDB(Steeply Dipping Bed)

Product gasAir/Oxygen

Knife edge CRIP

Injection

Production

Gasified coal residue

Flame front movement

Ignition well

Tunnel

Air1st stage Product

Mined tunnels

Steam2nd stage

Flame front movement

Behaviour prediction

�There is a large quantity of historical data available, including Soviet era texts detailing performance of UCG in a wide range of coal seams, that can be used to provide indications of likely behaviour

�Detailed cavity growth and gas production predictions require complex models covering a wide range of scientific disciplines

Variability in historical data

0%

20%

40%

60%

80%

100%

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chan

skG

orga

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oe C

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nets

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ren

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gas

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ang

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ars

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anna

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anna

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uzhn

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awlin

s 1B

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na I

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ricet

own

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ang

Pod

mos

kovi

aP

odm

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via

Chi

nchi

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orlo

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Ck

IIIB

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gas

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lovk

aM

ars

Raw

lins

1AC

entr

alia

AS

uncu

nR

ocky

Mtn

1B

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Ck

IIA

Roc

ky M

tn 1

AA

lcor

isa

Sun

cun

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ia B

Mar

sLi

uzha

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inhe

Thul

inR

awlin

s 2

Xie

zhua

ngLi

uzha

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inhe

Pro

duct

gas

, vol

ume%

(dr

y)

0

2

4

6

8

10

12

14

Gas

cal

orif

ic v

alue

, MJ/

m3 (

dry,

STP

)OtherCarbon dioxideHydrogenCarbon monoxideMethaneCalorific value

Another way of looking at it…Surface (Air)Surface (Oxygen)Underground (Air)Underground (Oxygen)Underground (Steam)Natural gas

Hydrogen

Carbon monoxide

Methane

Major combustible gas concentrations only

Synthesis gas H2:CO = 2:1

Synthesis gas H2:CO = 1:1

6

Literature trend from Skafa (1960)-Gas quality vs Seam thickness

0

1

2

3

4

5

6

0 1 2 3 4 5 6 7 8 9 10

Seam thickness, m

Pro

duct

gas

cal

orifi

c va

lue,

MJ/

m3

(dry

, STP

)

1 m3 of water/t of coal gasified




Literature trend from Skafa (1960)-Gas quality vs Ash content

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 10 20 30 40 50 60 70 80 90 100

Ash content of coal, %ad

Cal

orifi

c va

lue

of p

rod

uct

gas,

MJ/

m3 (d

ry, S

TP)

Summary

Some of the more obvious features that impact on UCG product gas quality are:

�Seam thickness

�Water influx

�Ash content

�Feed gas composition

Why do these have impact?

�Energy balance

oHeat loss to overburden

oVaporisation of water

�Mass balance

oRatio of C:H:O in reactions

oCoal recovery efficiency

Ash content impact

Ash content has an unusual impact:

�Ash replaces carbonaceous material, so reduces the effective quantity of coal and would be expected to reduce the efficiency

�But, this does not happen until ash contents over 40% occur

�Ash provides a thermal repository that stabilises gasification and can have a beneficial effect in some circumstances (eg. thin clay or stone bands in the coal seam)

12th November 2006

Kolkata, India

�Dr Andrew Beath


�Australia

�Dr Cliff Mallett



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