Thermodynamic cycle and heat management for packed bed CLC-based large scale power plants

V. Spallina, M.C. Romano, P. Chiesa, G. Lozza

CCS Conference 2013 - 28-29th May 2013 - Antwerp (BE)

D E M OC O C KL

Giovanni Lozza

Packed Bed Reactors for CLC

fuelair

N2 (+O2)CO2 + H2O+ No solids circulation easy operations at high

pressures

+ No solids entrainment simplified high temperature filtration before gas turbine

─ Dynamic non-homogeneous system with high temperature gradients coupling with turbomachines can be challenging

─ Need of high temperature switching valves

─ Operations with different sequential stages with different durations many parallel reactors may be needed, influencing cost and footprint

Giovanni Lozza

Ilmenite has been selected as oxygen carrier (natural oxygen carrier) CO conversion is very slow for T lower than 750°C

H2 oxidation with syngas is very fast for T higher than 450°C

Reduction reaction is slightly endothermic (∆T is about 10°C) Maximum temperature = 1200°C, suitable for power generation

Ilmenite as oxygen carrier

Giovanni Lozza

tem

pera

ture

Reactor length (axial position)

t=0 t=t1

t=t2 t=t3

t=t4

t1

tem

pera

ture

Time t2 t3 t4

Thermal profile inside the reactor (oxidation + heat removal)

Temperature at reactor outlet

Reaction front faster than the heat front: after oxidation, heat is stored inside the

reactor

Packed Bed Reactors for CLC

reaction front heat front

heat removal phase needed, producing high temperature gas suitable for expansion in a turbine

after heat removal, bed at the temperature of the inlet gas

Giovanni Lozza

Heat management – simple configuration

syngas

OXIDATION + HEAT REMOVAL

air

~

REDUCTION

CO2+H2O to heat recovery

‘‘cold’’ N2 to heat recovery during oxidation stage

hot air to turbine during heat removal stage

After heat removal, the bed is left at the inlet air temperature (400-450°C) Reduction too slow at that temperature! A different heat management strategy is needed

Giovanni Lozza

CO2

N2 recycle

Air

Syngas

N2

stack

Gasification island

HR Steam Cyclesyngas

coolers and AGR

HR RedOx

coal

gas turbine

CO2 cooling

HT - SH

RH

eva

Heat management – improved configuration

Giovanni Lozza

Reactor Design – Heat Management

CO2 + H2O

Hot N2

N2 for HR

Stoichiometric Air

REDUCTIONcycle

PURGEcycle

Heat Removal

cycle

Pure Oxidation

cycle

SYNGAS

PURGE GAS

PURGE GAS

N2

SYNGAS (strategy B2)

Hot N2 (strategy B2)

N2 for HR (strategy B2)

Reactors are operated with the following strategies: Oxidation phase: it stops when the

reaction front reaches the end of the reactor

Purge phase: O2 is removed from the reactor with N2

Reduction phase: syngas is fed to the reactor when the bed is at the maximum temperature level

Heat Removal phase: N2 the highest part of heat is still stored in the bed after reduction and the maximum temperature has not changed significantly (-10°C)

Complete cycle simulated with 1D model developed at TU/e S. Noorman S, M. van Sint Annaland, H. Kuipers, Packed bed reactor technology for chemical-looping combustion. Ind Eng Chem Res 2007;46:4212-20.

Giovanni Lozza

B.1 strategy (co-current reduction)

OXIDATION

PURGE

REDUCTION

HEAT REMOVAL

𝑁2

𝑁2

𝑁2

𝑆𝑦𝑦𝑦𝑦𝑦

𝐴𝑖𝑖

𝑁2 𝑁2

𝐶𝐶2/𝐻2𝐶

OXIDATION

PURGE

REDUCTION

HEAT REMOVAL

𝑁2

𝑁2

𝑁2

𝑆𝑦𝑦𝑦𝑦𝑦

𝐴𝑖𝑖

𝑁2 𝑁2

𝐶𝐶2/𝐻2𝐶

Time

Time

Reactor Design – Heat Management

B.2 strategy (counter-current reduction)

Giovanni Lozza

Reactor Design – Heat Management

B.1 strategy (co-current reduction): high temperature of CO2 from reduction stage

V. Spallina, F. Gallucci, M.C. Romano, P. Chiesa, G. Lozza, M. van Sint’Annaland, Investigation of heat management for CLC of syngas in packed bed reactors, Chem. Eng. J., Volume 225, June 2013, Pages 174–191.

Giovanni Lozza

Reactor Design – Heat Management

B.2 strategy (counter current reduction): Lower temperature of CO2 from reduction stage

V. Spallina, F. Gallucci, M.C. Romano, P. Chiesa, G. Lozza, M. van Sint’Annaland, Investigation of heat management for CLC of syngas in packed bed reactors, Chem. Eng. J., Volume 225, June 2013, Pages 174–191.

Giovanni Lozza

Gasification based on entrained flow, oxygen-blown, dry-feed Shell Gasifier: Gasifier temperature/pressure = 1450°C, 44 bar Coal feeding in Lock Hoppers with recirculated CO2 O2 purity = 95% Recycle gas quenching = 900°C

Assumptions for power plants calculation

H2S Removal with MDEA chemical absorption Power island:

TIT = 1200°C βcomp = 16.5 3 pressures (144/36/4 bar, 565/565°C) heat recovery steam cycle pcond = 0.048 bar

Other main assumptions from EBTF report on CO2 capture technology (D4.9 European best practice guidelines for assessment of CO2 capture technologies CAESAR project)

Giovanni Lozza

Process simulation tools

GS code: Modular structure: very complex schemes can be reproduced by assembling basic

modules Efficiency of turbomachines evaluated by built-in correlations accounting for operating

conditions and machine size Stage-by-stage calculation of steam and gas turbines Sophisticated model for the calculation of expansion in cooled gas turbine stages Chemical equilibrium Thermodynamic properties of gases NASA polynomials Thermodynamic properties of water/steam IAPWS-IF97

Aspen Plus: CO2 compression

http://www.gecos.polimi.it/software/gs.php

Giovanni Lozza

Coal, CO2

GasificationIsland

CLC Loop

scrubber

COShydr.

Dry solids removal

Slag

From IPdrum

To IP drum

AGR

ECO

SCEV

A +S

H

saturator water

~

H2O SAT

syng HTR

IP rh (EC)

CLC loop

HP eva

IP eva LP

eva HP

eco HP eco

IP eco

~

IP sh

HP sh

HP SH + EVAN2HR

O2_tr

exhausts cooling (EC)

LP eco

to coal drying

from HP ECO (HRSG)

AGR reb

TEG (ASU) reg

to deaeretor

Air

ASUO2 Nitrogen for

purge cycle

Dried coal

e.m.

waste Nitrogen

e.m.Liquid CO2

Drie

r

LockHoppers

e.m.

to wall Gasifier

1

2

3

4

5

6

9

10

1112

13

14

15

16

17

18

19

20

21 22 23

24

25

26

27

waste CO2 at LH

28

29

31

to HP EVA (HRSG)

recirculating N2

Stch Air

30

HP eco (EC)

HP eva + sh(EC)

HP sh (EC)

LP eco

87

37

e.m. 39

42

32

3334

3536

38

40

41

43

44

EVA SC

syn HTRcoal drying to deaeretor

to HP ECO line

HP EVA+SH N2

45

45

36

46

47

48

49

AG

R

Integrated Gasification CLC Combined Cycle

Giovanni Lozza

Calculated performance

Power balance, MWe IG-CLC-B1 IG-CLC-B2 IGCC IGCC+Selexol

CO2 capture Y Y N Y Gas Turbine Cycle, MWe 174.6 212.9 309.4 322.5 Steam Cycle, MWe 249.0 205.4 190 179.9 Gasification*, MWe -38.5 -38.5 -45.4 -52.1 CO2 capture island + AGR, MWe -17.7 -17.7 -0.4 -39.3 Packed Bed Reactors Aux., MWe -3.1 -3.1 - - N2 to GT compression, MWe - - -34.6 -20.4 Other Auxiliar., MWe -5.9 -3.05 -2.5 -3.3 Net Power, MWe 358.4 355.9 421.0 387.1 Thermal Input, MWLHV 896.5 896.5 896.5 1033.1 Net efficiency, %coal_LHV 40.0 39.7 47.0 37.5 CO2 emission, kg/MWhe 18.1 18.2 677.9 97.6 CO2 avoided, % 97.5 97.5 - 87.1 SPECCA**, MJLHV/kgCO2

1.9 2.13 - 3.46 * ASU, coal milling, ash handling, recycling syngas blower, etc… ** SPECCA = specific primary energy consumptions for CO2 avoided

REFERENCE PLANTS

V. Spallina, M. C. Romano, P. Chiesa, G. Lozza, Integration of coal gasification and packed bed CLC process for high efficiency and near-zero emission power generation GHGT-11 (18-22 Nov. 2012 – Kyoto (Japan)

Giovanni Lozza

Thank You

Acknowledgements The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 268112