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The integration of novel lithium-based
sorbents into Natural Gas Combined
Cycle power plants for the purpose of
𝐶𝑂2 capture
Ahmed Saleh
PhD researcher
E. Sanchez Fernandez, Susana Garcia,
Mercedes Maroto-Valer,
CICCS group, Heriot-Watt University
Aim and objectives
Investigate the process integration of high temperature lithium silicate based sorbents
into power plants for 𝐶𝑂2 capture.
14/06/2017 2
Contents
• Lithium orthosilicate as novel sorbents
• Integration of 𝐿𝑖4𝑆𝑖𝑂4/𝐿𝑖2𝐶𝑂3 Looping system
into Power plants
• Cases description and modelling approach
• Results & Discussion
• Conclusions and Future Work
14/06/2017 3
Lithium Silicate as a good candidate for
High temperature 𝑪𝑶𝟐 capture
14/06/2017 4
Effect of increasing CO2 concentration on capture capacity of Li4SiO4 at 1 atm and T=550C [2]
1. Quinn, R., et al.. Industrial & Engineering Chemistry Research, 2012. 51(27): p. 9320-9327. 2. Pacciani, R., et al, Environmental science & technology, 2011. 45(16): p. 7083-7088.
Cyclic CO2 capacity normalized to the 1st cycle capacity for LS 5 mm (squares) at 550 °C (humidified 14.7% CO2 in N2 feed, and CaO powder (circles) at 750 °C (dry 100% CO2). First cycle capacities: LS 5 mm, 15.3 wt %; CaO, 39 wt%.[1]
Lithium Silicate Advantages:
• Ability to work at high temperatures ( flue gas conditions )
• Good 𝐶𝑂2 capture capacity
• Higher stability over long cycles compared to CaO based sorbents
• Lower regeneration temperatures compared to CaO based sorbents
Lithium orthosilicate has lower regeneration temperature, lower regeneration heat and higher durability
𝐿𝑖4𝑆𝑖𝑂4 + 𝐶𝑂2 → 𝐿𝑖2𝐶𝑂3 + 𝐿𝑖2𝑆𝑖𝑂3
Integration of Sorbent Looping systems
into power plants
14/06/2017 5
C-1 C-2
E-2
E-4
E-1Flue gas
T1
Tabs
E-3Primary heat
recovery system
Treg
2nd / additional heat recovery
system
Air Separation Unit
Make-up
Fuel
Spent sorbent
T3T2
Air
E-5 E-6
E-7
Smart designed looping systems with several heat integration locations could save more energy and reduce the capture associated penalties
Generic scheme for HTCC plant with sorbent looping and possible heat recovery options.
Maximize the heat integration to reduce the energy penalty
Several locations for heat integration
Flexibility to integrate the capture unit on several power plants such as NGCC Plant
For lithium based sorbents, no recuperation and no make up flow was assumed
Optional
Cases description and modelling
approach
Case 1
• Based on base case model with
HTCC integrated
• Secondary HRSG /steam turbine
• ASU with 200 kwh/tO2
• 4 stage supercritical
𝐶𝑂2compression train with 30C
intercooling
Case 2
• Similar to case 1 but with low
ancillary consumption
• Lower ASU power consumption
159 kwh/tO2
• The compressors intercooling
temperature was lowered to 20C
using sea water cooling system
• CO2 is transported in liquid phase
14/06/2017 6 3. Franco, F., et al.,. European Benchmarking Task Force, 2011.
• The modelling basis and assumptions for the NGCC power plant are as per European Benchmarking Task Force (EBTF) common frame work [3]
• The NGCC plant was modelled using Aspen Plus software steady state with and without capture to evaluate efficiency, power and electrical penalties associated with carbon capture
Base Case ( NGCC Plant without capture)
14/06/2017 7
2 x F-Class GT
2 x 3 pressure level HRSG
IP reheat
K-1 K-2
E-1
E-2
K-3
H-1
HPS-3 IPS-1 HPS-2 IPS-2 HPS-1 HPB-1 HPE-2 LPS-1 IPS-3 HPE-1 IPB-1 IPE-1 LPB-1 LPE-1
K-4
V-1
E-3
V-2
E-4
H-2
V-3E-5
H-3
E-6
G-1
~
CW-1
CW-2V-4
V-5
To stack
D-1
K-5
V-7V-8
To 2nd gas turbine train
V-9
To 2nd gas turbine train
V-10
From 2nd HRSG train
V-11
From 2nd HRSG train
V-12
From 2nd HRSG train
Natural Gas
Air
Fuel preheating
1 unit x 3 pressure level steam turbine
14/06/2017 8
K-1 K-2
E-1
E-12Natural gas
K-3
H-4
Air
HPS-1 IPS-1 HPS-2 IPS-2 HPS-3 HPB-1 HPE-1 LPS-2 IPS-3 HPE-2 IPB-1 IPE-1 LPB-1 LPE-1
K-4
V-16
E-3
V-15
E-4
H-5
V-14E-5
H-6
E-7
G-1
~
CW-3
CW-4V-13
V-12
To stack
D-2
K-5
V-10V-9
V-8
V-7
V-6 V-5
C-1 C-2
HPB-2
HPS-4 E-8
V-4
V-3
K-6 K-7
G-2
K-8
ASU
E-9CW-5
CW-6
IPS-4 HPS-5 IPS-5 HPE-3
H-7CW-7
CW-8To CO2 compression
Oxygen
~
From 2nd primary HRSG From 2nd primary HRSGFrom 2nd primary HRSG
Fuel
E-10
HPE-4
E-11
To 2nd gas turbine
V-1
To 2nd gas turbine
Flue gasHP steam / waterIP steam / waterLP steam / waterCO2 stream
P-1
K-1 K-2
E-1
E-12Natural gas
K-3
H-4
Air
HPS-1 IPS-1 HPS-2 IPS-2 HPS-3 HPB-1 HPE-1 LPS-2 IPS-3 HPE-2 IPB-1 IPE-1 LPB-1 LPE-1
K-4
V-16
E-3
V-15
E-4
H-5
V-14E-5
H-6
E-7
G-1
~
CW-3
CW-4V-13
V-12
To stack
D-2
K-5
V-10V-9
V-8
V-7
V-6 V-5
C-1 C-2
HPB-2
HPS-4 E-8
V-4
V-3
K-6 K-7
G-2
K-8
ASU
E-9CW-5
CW-6
IPS-4 HPS-5 IPS-5 HPE-3
H-7CW-7
CW-8To CO2 compression
Oxygen
~
From 2nd primary HRSG From 2nd primary HRSGFrom 2nd primary HRSG
Fuel
E-10
HPE-4
E-11
To 2nd gas turbine
V-1
To 2nd gas turbine
Flue gasHP steam / waterIP steam / waterLP steam / waterCO2 stream
P-1
K-1 K-2
E-1
E-12Natural gas
K-3
H-4
Air
HPS-1 IPS-1 HPS-2 IPS-2 HPS-3 HPB-1 HPE-1 LPS-2 IPS-3 HPE-2 IPB-1 IPE-1 LPB-1 LPE-1
K-4
V-16
E-3
V-15
E-4
H-5
V-14E-5
H-6
E-7
G-1
~
CW-3
CW-4V-13
V-12
To stack
D-2
K-5
V-10V-9
V-8
V-7
V-6 V-5
C-1 C-2
HPB-2
HPS-4 E-8
V-4
V-3
K-6 K-7
G-2
K-8
ASU
E-9CW-5
CW-6
IPS-4 HPS-5 IPS-5 HPE-3
H-7CW-7
CW-8To CO2 compression
Oxygen
~
From 2nd primary HRSG From 2nd primary HRSGFrom 2nd primary HRSG
Fuel
E-10
HPE-4
E-11
To 2nd gas turbine
V-1
To 2nd gas turbine
Flue gasHP steam / waterIP steam / waterLP steam / waterCO2 stream
P-1
K-1 K-2
E-1
E-12Natural gas
K-3
H-4
Air
HPS-1 IPS-1 HPS-2 IPS-2 HPS-3 HPB-1 HPE-1 LPS-2 IPS-3 HPE-2 IPB-1 IPE-1 LPB-1 LPE-1
K-4
V-16
E-3
V-15
E-4
H-5
V-14E-5
H-6
E-7
G-1
~
CW-3
CW-4V-13
V-12
To stack
D-2
K-5
V-10V-9
V-8
V-7
V-6 V-5
C-1 C-2
HPB-2
HPS-4 E-8
V-4
V-3
K-6 K-7
G-2
K-8
ASU
E-9CW-5
CW-6
IPS-4 HPS-5 IPS-5 HPE-3
H-7CW-7
CW-8To CO2 compression
Oxygen
~
From 2nd primary HRSG From 2nd primary HRSGFrom 2nd primary HRSG
Fuel
E-10
HPE-4
E-11
To 2nd gas turbine
V-1
To 2nd gas turbine
Flue gasHP steam / waterIP steam / waterLP steam / waterCO2 stream
P-1
NGCC Plant Case with HTCC plant (Case 1)
Stochiometric Reactor, 𝑇𝑎𝑏𝑠= 500C, Fractional conversion = 0.54, 90% 𝐶𝑂2 capture
Gibbs Reactor, 100% sorbent regeneration, 𝑇𝑑𝑒𝑠 > 690C (695 to 720 C), no make up flow
100 % solid separation
4 stage compression train, 110 bar, 30C intercooling
35% O2 stream with 3% excess oxygen
200 kwh/t𝑂2
CO2 recycle O2 / fuel heaters
Exothermic Heat recovery No heat recuperation
14/06/2017 9
Results &
Discussion
Specific energy demand for the HTCC
plant as a function of regeneration
temperature (Treg)
14/06/2017 10
Increasing the regeneration temperature leads to linear increase in the energy demand
The impact of the HTCC plant on power
plant performance
14/06/2017 11
Increasing 𝑇𝑟𝑒𝑔 does not have a significant impact on plant efficiency and
electricity penalty
a) Net power plant efficiency b) SPECCA and EOP
Simulation results for 𝑻𝒓𝒆𝒈 = 𝟕𝟏𝟎𝑪 –
secondary HRSG
14/06/2017 12
K-1 K-2
E-1
E-12Natural gas
K-3
H-4
Air
HPS-1 IPS-1 HPS-2 IPS-2 HPS-3 HPB-1 HPE-1 LPS-2 IPS-3 HPE-2 IPB-1 IPE-1 LPB-1 LPE-1
K-4
V-16
E-3
V-15
E-4
H-5
V-14E-5
H-6
E-7
G-1
~
CW-3
CW-4V-13
V-12
To stack
D-2
K-5
V-10V-9
V-8
V-7
V-6 V-5
C-1 C-2
HPB-2
HPS-4 E-8
V-4
V-3
K-6 K-7
G-2
K-8
ASU
E-9CW-5
CW-6
IPS-4 HPS-5 IPS-5 HPE-3
H-7CW-7
CW-8To CO2 compression
Oxygen
~
From 2nd primary HRSG From 2nd primary HRSGFrom 2nd primary HRSG
Fuel
E-10
HPE-4
E-11
To 2nd gas turbine
V-1
To 2nd gas turbine
Flue gasHP steam / waterIP steam / waterLP steam / waterCO2 stream
P-1
Simulation results for 𝑻𝒓𝒆𝒈 = 𝟕𝟏𝟎𝑪 –
secondary HRSG TQ curve
14/06/2017 13
Fixed HP / Low pressure - slight increase in reheat pressure from 31.7 bar to 33.0 bar to ensure suitable temperature available at lower end of secondary HRSG. Hot CO2 ( 321 - 361C) is used to preheat fuel / oxygen.
Summary of simulation results for base
case (NGCC plant without capture) and
Cases 1 and 2 (𝑻𝒂𝒃𝒔 = 𝟓𝟎𝟎𝑪, 𝑻𝒓𝒆𝒈 = 710C)
14/06/2017 14
Parameter Unit
NGCC
without
capture
NGCC with capture
Case 1 Case 2
Gross power output MW 837.3 1038.3 1038.6
Gas turbine output (x1) MW 274.6 274.6 274.6
Primary Steam turbine output MW 288.1 287.7 287.7
Secondary steam turbine power output MW NA 201.4 201.8
Net power output MW 829.9 953.1 961.4
Fuel thermal Input MWth(LHV) 1423.0 1864.8 1865.9
Net Plant efficiency %LHV 58.3 51.1 51.5
CO2 emissions kg/MWh 351.6 32.3 32.0
Penalty points % NA 7.2 6.8
SPECCA GJ/tCO2 NA 2.7 2.6
Case 2 achieved higher efficiency (6.8 penalty points) and lower SPECCA due to lower ancillary consumption
Parameter Unit
NGCC
without
capture
NGCC with capture
Case 1 Case 2
Gross power output MW 837.3 1038.3 1038.6
Gas turbine output (x1) MW 274.6 274.6 274.6
Primary Steam turbine output MW 288.1 287.7 287.7
Secondary steam turbine power output MW NA 201.4 201.8
Net power output MW 829.9 953.1 961.4
Fuel thermal Input MWth(LHV) 1423.0 1864.8 1865.9
Net Plant efficiency %LHV 58.3 51.1 51.5
CO2 emissions kg/MWh 351.6 32.3 32.0
Penalty points % NA 7.2 6.8
SPECCA GJ/tCO2 NA 2.7 2.6
Parameter Unit
NGCC
without
capture
NGCC with capture
Case 1 Case 2
Gross power output MW 837.3 1038.3 1038.6
Gas turbine output (x1) MW 274.6 274.6 274.6
Primary Steam turbine output MW 288.1 287.7 287.7
Secondary steam turbine power output MW NA 201.4 201.8
Net power output MW 829.9 953.1 961.4
Fuel thermal Input MWth(LHV) 1423.0 1864.8 1865.9
Net Plant efficiency %LHV 58.3 51.1 51.5
CO2 emissions kg/MWh 351.6 32.3 32.0
Penalty points % NA 7.2 6.8
SPECCA GJ/tCO2 NA 2.7 2.6
Impact to power plant
14/06/2017 15
a) TQ curve for primary HRSG for NGCC plant base case without capture.
b) TQ curve for primary HRSG for NGCC plant base case with capture unit integrated (Case 1).
Slight increase in the flue gas TQ line slope. No major change in primary HRSG
Comparison to other technologies
14/06/2017 16
Parameter Unit
Base
case MEA CESAR-1 CaCO3 Li4SiO4
Reference [-] (Sanchez Fernandez et al., 2013)
(Berstad
et al.,
2012)
This
work
Wgross (calc) MW 837.3 759.9 770.7 627.6 1038.6
Wnet (calc) MW 829.9 709.9 722.6 559.7 961.4
Net Plant efficiency %LHV 58.3 49.9 50.8 45.6 51.5
CO2 emissions kg/MWh 351.6 41.1 40.4 30.6 32.0
Penalty points % 8.4 7.6 12.74 6.80
SPECCA GJ/tCO2 3.4 2.9 5.4 2.6
EOP kWh/tCO2 456.9 408.6 659.7 340.1
Lithium silicate achieved better efficiency compared bench mark amine solvent and basic CaO sorbent
Parameter Unit
Base
case MEA CESAR-1 CaCO3 Li4SiO4
Reference [-] (Sanchez Fernandez et al., 2013)
(Berstad
et al.,
2012)
This
work
Wgross (calc) MW 837.3 759.9 770.7 627.6 1038.6
Wnet (calc) MW 829.9 709.9 722.6 559.7 961.4
Net Plant efficiency %LHV 58.3 49.9 50.8 45.6 51.5
CO2 emissions kg/MWh 351.6 41.1 40.4 30.6 32.0
Penalty points % 8.4 7.6 12.74 6.80
SPECCA GJ/tCO2 3.4 2.9 5.4 2.6
EOP kWh/tCO2 456.9 408.6 659.7 340.1
Parameter Unit
Base
case MEA CESAR-1 CaCO3 Li4SiO4
Reference [-] (Sanchez Fernandez et al., 2013)
(Berstad
et al.,
2012)
This
work
Wgross (calc) MW 837.3 759.9 770.7 627.6 1038.6
Wnet (calc) MW 829.9 709.9 722.6 559.7 961.4
Net Plant efficiency %LHV 58.3 49.9 50.8 45.6 51.5
CO2 emissions kg/MWh 351.6 41.1 40.4 30.6 32.0
Penalty points % 8.4 7.6 12.74 6.80
SPECCA GJ/tCO2 3.4 2.9 5.4 2.6
EOP kWh/tCO2 456.9 408.6 659.7 340.1
Conclusion and future recommendations
14/06/2017 17
. .
First process integration study of lithium-based sorbents for high temperature 𝐶𝑂2 capture applications into NGCC plants.
Lithium silicate integration achieved better overall plant
efficiency and lower electricity output penalty compared to basic, advanced amines and basic CaO sorbents.
No significant change in efficiency when 𝑻𝒓𝒆𝒈 changes. Future
work should focus on optimizing the integration within the studied range of 𝑇𝑟𝑒𝑔.
Indirect heating options can be investigated as a replacement
for oxyfuel combustion.
14/06/2017 18
Thank you
Supplementary Info
14/06/2017 19
Equilibrium Thermodynamics vs kinetics
14/06/2017 20
𝑇𝑎𝑏𝑠=500C, 𝑇𝑟𝑒𝑔 > 690C
Fractional Conversion = 0.54
3. Essaki, K., M. Kato, and H. Uemoto, Influence of temperature and CO2 concentration on the CO2 absorption properties of lithium silicate pellets. Journal of Materials Science, 2005. 40(18): p. 5017-5019.
Equilibrium CO2 partial pressure vs. turnover temperature (T0) for Li4SiO4 estimated with the software Aspen Plus®.
Li4SiO4 fractional conversion curve for 5% vol CO2 and 500ºC. Calculated from [3]
Cases description and modelling
approach
14/06/2017 21
NGCC Plant Case with HTCC plant (CASE 1)
• Extracted CO2 stream is compressed to 110 bar before transportation using multi stage supercritical compression train with 30C intercooling system
Cases description and modelling
approach
14/06/2017 22
Plant efficiency measurement
• Net Plant efficiency 𝜂 =W1+W2
𝑚1+𝑚2 ∙∆𝐻𝑐
• Specific Primary Energy consumption for CO2 avoided (SPECCA) in GJ/tCO2 [8]:
𝑆𝑃𝐸𝐶𝐶𝐴 =𝐻𝑅𝐶𝐶−𝐻𝑅𝑅𝐸𝐹
𝐸𝑅𝐸𝐹−𝐸𝐶𝐶=
3600 .(1
ƞ𝐶𝐶−
1
ƞ𝑅𝐸𝐹)
𝐸𝑅𝐸𝐹−𝐸𝐶𝐶 =
3600 .(1
ƞ𝐶𝐶−
1
ƞ𝑅𝐸𝐹)
𝐸𝑅𝐸𝐹−𝐸𝐶𝐶
Where 𝐻𝑅𝐶𝐶 and 𝐻𝑅𝑅𝐸𝐹 are the heat rate (KJ/Kwhe) for the Plant with capture unit and before adding capture unit respectively, 𝐸𝐶𝐶 and 𝐸𝑅𝐸𝐹 are CO2 emission rate in (KgCO2/Kwhe) for the Plant with capture unit and before adding capture unit respectively • Electricity output penalty (EOP) [13]: • the total net loss in plant power output after integration of the co2 capture uni
𝐸𝑂𝑃= 𝑃𝑙𝑎𝑛𝑡 𝑃𝑜𝑤𝑒𝑟 𝑂𝑢𝑡𝑝𝑢𝑡 𝑏𝑒𝑓𝑜𝑟𝑒 𝑐𝑎𝑝𝑡𝑢𝑟𝑒 𝐾𝑊 −𝑃𝑙𝑎𝑛𝑡 𝑃𝑜𝑤𝑒𝑟 𝑂𝑢𝑡𝑝𝑢𝑡 𝑎𝑓𝑡𝑒𝑟 𝑐𝑎𝑝𝑡𝑢𝑟𝑒 (𝐾𝑊)
𝐶𝑂2 𝑐𝑎𝑝𝑡𝑢𝑟𝑒𝑑(𝑇𝑜𝑛𝑒/𝑜𝑢𝑟)
• Marginal thermal efficiency of the oxyfuel regenerator [9] to measure the thermal efficiency of the additional natural gas combustion :
𝜂𝑚𝑎𝑟𝑔 =𝑊2
𝑚2∙∆𝐻𝑐+Δ𝐻𝑟
8. Lucquiaud, M. and J. Gibbins, On the integration of CO 2 capture with coal-fired power plants: a methodology to assess and optimise solvent-based post-combustion capture systems. Chemical Engineering Research and Design, 2011. 89(9): p. 1553-1571.
9. Díaz, A.G., et al., Sequential supplementary firing in natural gas combined cycle with carbon capture: A technology option for Mexico for low-carbon electricity generation and CO 2 enhanced oil recovery. International Journal of Greenhouse Gas Control, 2016. 51: p. 330-345.
.
Results Discussion
14/06/2017 23
Enthalpy-entropy diagram for the secondary HRSG for different regeneration temperatures
. .
marginal efficiency of the
secondary HRSG
14/06/2017 24
24.0
24.5
25.0
25.5
26.0
26.5
27.0
690 695 700 705 710 715 720 725
hm
arg [
%L
HV
]
Treg [ºC]
b)
14/06/2017 25