Options for th The Energy MIXGENERA 2011 Options for the future ...

MMIXGENERA
2011
Options for the future
November 17, 2011.
Auditorium of the University Carlos III de Madrid
Leganés, Madrid, Spain.
http://electrica.uc3m.es/mixgenera/
The Energy Mix at the years 2020 y 2030
ISBN: 978 978-84-614-9978-6
Chairs: Edgardo D. Castronuovo
Víctor Hernández Jiménez
Fernando Soto Martos
Julio Usaola García
Secretary: Ignacio A. Calle
More information: ecastron@ing.uc3m.es
Support:

MIXGENERA 2011 – November 17, 2011 – Leganés, Madrid, Spain - http://electrica.uc3m.es/mixgenera/ 1
Capture of CO2 during low temperature biomass
combustion in a fluidized bed using CaO.
Construction of a new larger scale experimental
facility
John R. Chamberlain, Francisco J. Alonso Martinez, and Carlos Perez Ros, Gas Natural Fenosa
Abstract—This paper outlines a new experimental test facility
of 300kWt being commissioned in the grounds of Gas Natural
Fenosa’s La Robla coal-fired power plant in the Leon region,
Northwest of Spain, with the goal to advance the demonstration
of the capture of CO 2 with CaO in a circulating fluidized bed
(CFB) combustor-carbonator reactor, where the combustion of
biomass with air occurs simultaneously with the carbonation of
CaO, thereby capturing the CO 2 released from the combustion
process.
I
Index Terms— Biomass, Carbonate Looping, CO 2 Capture,
I. INTRODUCTION
n order to maintain global warming below 2ºC, the
International Energy Agency (IEA) states that Carbon
Capture and Storage (CCS) must provide 20% of the global
CO2 required cuts by 2050; the costs of doing so without CCS
will be over 70% higher [1]. The integration of CCS with
biomass should result in CO2 “negative emissions” in the
generation of electricity or in other energy products, which is a
very attractive concept initially recognized by Ishitani and
Johansson [2] and these positive implications have been
highlighted in many recent studies [3, 4].
This abstract outlines a new experimental test facility of
300kWt currently being commissioned in the grounds of Gas
Natural Fenosa’s La Robla coal-fired power plant in the Leon
region, Northwest of Spain, with the goal to advance the
demonstration of the capture of CO2 with CaO in a circulating
fluidized bed (CFB) combustor-carbonator reactor, where the
combustion of biomass with air occurs simultaneously with the
This work has been carried out thanks to the financial support from
Spanish Centre for the Development of Industrial Technology (CDTI) under
the auspices of the projects CENITCO2 and MENOSCO2.
J.R. Chamberlain is with Gas Natural Fenosa, Madrid, Aveinda San Luis
77, 28033 Spain: (phone +34 01-567-6000; 555; e-mail:
jchamber@gasnatural.com).
F.J. Alonso Martinez is with Gas Natural Fenosa, Madrid, Aveinda San
Luis 77, 28033 Spain: (e-mail: fjalonso@gasnatural.com).
C. Perez Ros is with SOCOIN, Pozuelo de Alarcón (Madrid), Parque
Empresarial La Finca, 28233 Spain: (e-mail: cpros@socoin.es).
carbonation of CaO, thereby capturing the CO2 released from
the combustion process. This process intends to exploit the
high reactivity of most natural biomasses permitting the
possibility of combustion at low temperatures (around 700ºC)
and the capability of CaO to absorb CO2 at these temperatures.
This is a niche application for the carbonate looping cycles
that can be applied as a standalone process or in a possible cocombustion
concept when integrated with an existing thermal
power plant.
Previous results obtained in a 30kWt test facility made up of
two interconnected CFB reactors (combustor-carbonator and
combustor-calciner) located at the facilities of the Spanish
Institute of Coal (INCAR-CSIC) in Oviedo, Spain, have been
presented before [5, 6] and demonstrate the experimental
feasibility of this concept achieving CO2 capture efficiencies
of over 80% that are remarkably close to those allowed by the
equilibrium and the combustion mass balances.
(a)
Concentration (% vol.)
25
20
15
10
5
0
19:10 19:20 19:30 19:40 19:50 20:00 20:10
time (h:min)
CO 2
O O 2 analyzer
O 2 probe
0
19:10 19:20 19:30 19:40 19:50 20:00 20:10
time (h:min)
Fig. 1. Example of experimental results in the combustor-carbonator reactor
in a typical experiment. (a) Combustor-carbonator exit gas concentrations of
CO2 and O2 measured by the on-line gas analyzer and O2 zirconia probe (b)
Experimental capture efficiency and maximum capture efficiency allowed by
equilibrium.
In this example, the average CO2 concentration at the exit of
the combustor-carbonator reactor was 3.1 vol%. The average
oxygen concentration at the exit of the combustor-carbonator
was 7.6 vol.%. From a combustion mass balance, the CO2
produced by biomass combustion was estimated to be around
Capture Efficiency (%)
100
80
60
40
20
Experimental
Experimental
Equilibrium
(b)

MIXGENERA 2011 – November 17, 2011 – Leganés, Madrid, Spain - http://electrica.uc3m.es/mixgenera/ 2
13.6 vol.% , therefore, the average CO2 capture efficiency was
77%. The average temperature in the combustor-carbonator
was 690ºC during the period, which according to the
equilibrium of CO2 on CaO allows for a 2.4 vol% of CO2
(maximum efficiency allowed by the equilibrium of 81%,
remarkably close to the experimental value).
These positive results justified the construction of the new
larger scale test facility in the grounds of the Gas Natural
Fenosa’s La Robla coal fired power plant that is some 10 times
larger than the 30kW test facility in Oviedo.
II. SCALE OF UP TEST FACILITY
This new facility consists of two interconnected CFB
reactors, the carbonator and calciner both being 12m high
cylindrical reactors with a diameter of 600mm. In order to
control the temperature of the biomass combustion within the
range of 650-700ºC in the carbonator, a heat exchanger is
installed that employs thermal oil as the cooling medium. The
calciner is ceramic lined as it operates in the temperature range
of 850-900ºC.
Fig. 2. Images of the 300kWt experimental plant in La Robla Power Plant
actually in the stages of commissioning.
As one of the objectives of this larger test facility is to carry
out longer duration experiments, biomass storage for one week
experimentation is contemplated, along with the capability to
receive fresh supplies during operation, that is sufficient to
provide both the nominal 1.7T/day of biomass to the
carbonator and 2,5T/day of biomass to the calciner through
fully automated biomass handling and injection systems.
Limestone storage and injection is also contemplated, capable
of injecting over 0,5T/day for make-up if required, which will
be dependent on sorbent deactivation and breakdown. Air is
preheated and supplied to independently to both the carbonator
and calciner reactors in a controlled manner through variable
speed forced draft fans. Biomass and air are injected at the
bottom carbonator that will be filled with a bed of
predominantly CaO and if the temperature of combustion can
be controlled to just below 700ºC, combustion of the biomass
and capture of CO2 through the reaction with the CaO to
produce CaCO3 should occur simultaneously. The mixture of
gases and solids that leave the top of the carbonator then
passes through two cyclones situated in series in order to
separate the solids from the combustion gas without CO2. The
solids separated in the first cyclone are then introduced into
the calciner via a loop seal in order to permit the regeneration
of CaO from CaCO3, thus separating the CO2. Biomass is
added to the calciner as a fuel source to obtain the required
reaction temperature above 850ºC. In a similar manner to the
carbonator, the solids in the calciner, in this instance mainly
CaO and a gas enriched in CO2, leave the top of the vessel and
pass through two cyclones situated in series in order to
separate the solids from the CO2 enriched gas. The solids
separated in the first cyclone are returned to the carbonator via
loop seal in order to close the loop of the process.
III. SUMMARY
Carbonate looping is one of the emerging second
generation CO2 capture technologies considered to be of
promise as it employs a low cost and readily available sorbent
and due to the process temperatures, it should be possible to
recover and use much of the heat input required, reducing the
final energy penalty. The niche concept being investigated in
this work, where the combustion of biomass with air and the
carbonation of CaO takes place simultaneously is considered
to be an attractive option for this technology, promoting a
concept of negative emissions for the biomass consumed. This
new larger experimental plant being commissioned in the
grounds of La Robla power plant of Gas Natural Fenosa is a
required next step to further develop and validate this concept.
Over the next year this facility should permit the validation of
the smaller scale experimental work and provide crucial
experimental results from longer duration experiments to
confirm and validate the previous smaller scale experimental
work. Also, and more importantly, these results should
determine the sorbent performance and make-up requirements,
a key issue, contribute to both the technical and economical
evaluation of the concept as well as generating data for the
future scale up of this option to sizes in the order of several

megawatts.
MIXGENERA 2011 – November 17, 2011 – Leganés, Madrid, Spain - http://electrica.uc3m.es/mixgenera/ 3
ACKNOWLEDGMENT
The participations of the Spanish Institute of Coal (INCAR-
CSIC) in Oviedo and the Centre of Research for Energy
Resources and Consumption (CIRCE) in Zaragoza in the
project are also gratefully acknowledged.
REFERENCES
[1] International Energy Agency (IEA), World Energy Outlook, 2009
[2] Ishitani, H., Johansson, T. B. Energy supply mitigation options. In: R.
T. Watson, M. C. Zinoyowera and R. H. Moss, editors. Climate Change
1995: Impacts, Adaptations, and Mitigation of Climate Change:
Scientific-Technical Analyses, Cambridge, UK: Cambridge University
Press; 1996, p.
[3] Rhodes, J. S., Keith, D. W. Biomass with capture: negative emissions
within social and environmental constraints: an editorial comment.
Climatic Change 2008; 87: 321-8
[4] Obersteiner, M., Azar, C., Kauppi, P., Mollersten, K., Moreira, J.,
Nilsson, S., et al. Managing climate risk. Science 2001; 294: 786-
[5] Abanades Garcia, J. C., Alonso, M., Rodriguez, N. Experimental
validation of in situ CO2 capture with CaO during the low temperature
combustion of biomass in a fluidized bed reactor. Int. J. Green. Gas.
Cont. 2010; d.o.i 10.1016/j.ijggc 2010.01.006:
[6] Alonso, M., Rodriguez, N., Gonzalez, B., Arias, B., Abanades Garcia,
J. C., Capture of CO2 during low temperature biomass combustion in a
fluidized bed using CaO. Process description, experimental results and
economics. GCGT-10, Energy Procedía 2010G. O. Young, “Synthetic
structure of industrial plastics (Book style with paper title and editor),”
in Plastics, 2nd ed. vol. 3, J. Peters, Ed. New York: McGraw-Hill,
1964, pp. 15–64.