3cm Low Emission Conversion of Fossil Fuels with Simultaneous or Consecutive Storage of ...

259 Pages·2013·3.41 MB·English

by  Ali Akbar Eftekhari

Low Emission Conversion of Fossil Fuels with
Simultaneous or Consecutive Storage of
Carbon Dioxide
Ali Akbar Eftekhari

Low Emission Conversion of Fossil Fuels with
Simultaneous or Consecutive Storage of
Carbon Dioxide
Proefschrift
ter verkrijging van de graad van doctor
aan de Technische Universiteit Delft,
op gezag van de Rector Magnificus prof. ir. K.C.A.M. Luyben,
voorzitter van het College voor Promoties,
in het openbaar te verdedigen op donderdag 26 september 2013 om 15:00 uur
door
Ali Akbar EFTEKHARI
Master of Science in Chemical Engineering,
Sharif University of Technology
geboren te Estahban, Iran
Dit proefschrift is goedgekeurd door de promotoren:
Prof.dr. J. Bruinig
Copromoter Dr. K.H.A.A. Wolf
Samenstelling promotiecommissie:
Rector Magnificus, voorzitter
Prof. J. Bruining, Technische Universiteit Delft, promotor
Dr. K.H.A.A. Wolf, Technische Universiteit Delft, copromotor
Prof. D. Marchesin Instituto de Matemtica Pura e Aplicada, Brazilië
Prof. S. Durucan Imperial College London, UK
Prof. P.L.J. Zitha Technische Universiteit Delft
Prof. C.P.J.W. van Kruijsdijk Technische Universiteit Delft
Dr. H.J. van der Kooi Technische Universiteit Delft
Prof.dr.ir. J.D. Jansen Technische Universiteit Delft, reservelid
This work was partially supported by European Comission under the framework of
HUGE project.
Copyright © 2013, Ali Akbar Eftekhari
Cover design by A. A. Eftekhari, recovery factor of a typical energy extraction
process
Printed by CPI-Wöhrmann Print Service – Zutphen
ISBN: 978-94-6203-451-8
To Aida and Maryam,
دامتعا و دیما تیاهن
To my mother,
and to the memory of my father

Preface
We have a habit in writing articles
published in scientific journals to
make the work as finished as
possible, to cover up all the tracks,
to not worry about the blind alleys
or describe how you had the wrong
idea at first, and so on. So there
isn’t any place to publish, in a
dignified manner, what you
actually did in order to get to do
the work.
Richard Feynman
This thesis was performed under the framework of a European Commission sup-
ported HUGE project: Hydrogen-oriented Underground coal Gasification (UCG)
for Europe. The main goal was to make coal gasification products competitive with
other fossil fuels in term of CO emission, for countries with high coal reserves, such
2
as Poland. As the thesis investigates the coal gasification process and methods to
reduce its CO footprint, it is divided into two parts: in the first part coal gasi-
2
fication process is studied, and in the second part important issues related to the
aquifer storage of CO are discussed.
2
In the first part, simple chemical equilibrium models are used to predict quality
and carbon content of the UCG product. The CO emission per unit energy of
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UCG product is at least three times higher than natural gas. Various options were
considered to lower the CO emission, including in-situ and ex-situ carbonation of
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synthetic/natural minerals, and aquifer storage of CO . The disadvantage of these
2
options is that they require a large amount of energy, which results in a lower coal
conversion efficiency. To quantify the energy penalties, based on the principles of
thermodynamics and the exergy concept, a framework was designed to quantify – in
a coherent and fundamental way – the effect of various process parameters on the
effectiveness of an energy extraction process. The analysis shows that none of the
mentioned processes are able to effectively reduce the carbon content of the UCG
product. The next step was to analyze a UCG process with alternating injection
of air/steam, based on a successful low pressure field experiment performed by a
HUGEprojectpartnerinPoland. Theresultsofthemathematicalmodelandexergy
analysis showed that alternating injection process at high or low pressure cannot
compete with lower CO emission of using natural gas.
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To reduce practically the high CO emission value of UCG process to an acceptable
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level, the focus was shifted from coal conversion to aquifer storage of CO .
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In the second part of the thesis, two issues related to the aquifer storage of CO
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are investigated: (1) the permeability impairment due to salt precipitation near the
CO injection wells, and its effect on the injectivity and compression power (ex-
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ergy) requirement; (2) increased storage capacity and long-term CO sequestration
2
due to enhanced transfer rate of CO in water-saturated porous media. Exergetic
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applicability of carbon capture and sequestration for low emission carbon dioxide
fuel consumption, can presently only be achieved if the energy-intensive step of
nitrogen-CO separation prior to injection can be avoided. New separation tech-
2
nology could help to make coal usage competitive with natural gas usage as to its
carbon footprint.
Contents
Nomenclature 1
1. Introduction 9
1.1. Energy requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2. Recovery of the fossil fuels and carbon emission . . . . . . . . . . . . 10
1.3. Problem statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.4. Efficiency factors and practicality . . . . . . . . . . . . . . . . . . . . 12
1.5. The quality of energy . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.6. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.7. Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2. Exergy Analysis of UCG 19
2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2. Chemical equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.1. Problem definition . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.2. Energy Balance . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.3. Solution methodology . . . . . . . . . . . . . . . . . . . . . . . 25
2.3. Volume and temperature constraints . . . . . . . . . . . . . . . . . . 25
2.4. Process description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5. General approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.5.1. Material streams . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.5.2. Exergy streams: heat and power . . . . . . . . . . . . . . . . . 32
2.5.2.1. Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.5.2.2. Power . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.5.3. Analysis of the energy recovery/conversion process . . . . . . 34
2.5.4. Exergy analysis of the UCG process . . . . . . . . . . . . . . . 37
2.6. Calculation procedure and data . . . . . . . . . . . . . . . . . . . . . 39
2.6.1. Compression exergy . . . . . . . . . . . . . . . . . . . . . . . . 39
2.6.2. Well exergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.6.3. Chemical Equilibrium . . . . . . . . . . . . . . . . . . . . . . 42
2.6.4. Physical parameters . . . . . . . . . . . . . . . . . . . . . . . 45
2.6.5. Calculation of exergy values . . . . . . . . . . . . . . . . . . . 45
2.6.6. Grinding exergy . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.6.7. Separation of CO from flue gas . . . . . . . . . . . . . . . . . 49
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2.6.8. Exergy of CO sequestration . . . . . . . . . . . . . . . . . . . 50
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Contents Contents
2.7. Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.7.1. Base case: air (oxygen)/water UCG . . . . . . . . . . . . . . . 52
2.7.2. Scenario 1: insitu usage of CaO . . . . . . . . . . . . . . . . . 58
2.7.3. Scenario 2: ex-situ upgrading with wollastonite . . . . . . . . 62
2.8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3. Alternating injection of oxygen/steam 67
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.2. Mathematical model . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
3.2.1. Mass transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.2.2. Energy balance . . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.2.2.1. Coal/cavity interface . . . . . . . . . . . . . . . . . . 77
3.2.2.2. Roof/cavity interface . . . . . . . . . . . . . . . . . . 78
3.2.2.3. Rubble/cavity interface . . . . . . . . . . . . . . . . 78
3.2.2.4. Bulk gas energy balance . . . . . . . . . . . . . . . . 79
3.2.3. Boundary layer thickness . . . . . . . . . . . . . . . . . . . . . 80
3.3. Numerical scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4. Mixing effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.5. Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.5.1. Comparison with chemical equilibrium model . . . . . . . . . 84
3.5.2. Comparison with field experiments . . . . . . . . . . . . . . . 85
3.5.3. Sensitivity analysis . . . . . . . . . . . . . . . . . . . . . . . . 87
3.5.3.1. Duration of steam/O injection stages . . . . . . . . 88
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3.5.3.2. Pressure . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.5.4. Steady state results . . . . . . . . . . . . . . . . . . . . . . . . 92
3.5.4.1. Steam/O ratio . . . . . . . . . . . . . . . . . . . . . 92
2
3.5.5. Exergy analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4. Salt precipitation in CO storage 105
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4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
4.2. Phase equilibrium model . . . . . . . . . . . . . . . . . . . . . . . . . 108
4.3. Flash calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
4.3.1. Basic definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 109
4.3.2. Vapor-liquid-solid flash calculation . . . . . . . . . . . . . . . 110
4.4. Thermodynamic models . . . . . . . . . . . . . . . . . . . . . . . . . 114
4.4.1. The PRSV equation of state with the MHV2 mixing rule . . . 115
4.4.2. NRTL activity coefficient model for a binary mixture . . . . . 117
4.4.3. Objective function and optimization . . . . . . . . . . . . . . . 118
4.4.4. Correction parameters of the liquid density . . . . . . . . . . . 118
4.4.5. Equilibrium results . . . . . . . . . . . . . . . . . . . . . . . . 119
4.5. Negative flash for a gas-liquid system . . . . . . . . . . . . . . . . . . 120
4.6. Molar and volumetric concentrations . . . . . . . . . . . . . . . . . . 122
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