Key
Findings and Proposals
Below is a brief summary of key findings and proposals
for the direction of further research and co-operation
following the 1st meeting of the network. The meeting
was attended by 77 people with a strong representation
and interest from industry. It was agreed at the meeting
that the next network meeting will be hosted by ECN
of the Netherlands in the week before the GHGT-10 conference
which is being held in Amsterdam in September 2010.
More information about the the next meeting will be
published shortly.
What we have learned
At least two new pilot demonstrations in the MW class
are to be implemented in Spain (la Pereda for Ca-Looping)
and Germany (Darmstadt, for CLC and Ca-looping) before
2010.
There are several small dual bed systems in operation
at various research centres in the 10s kW scale range
for CLC and Ca-looping. Extended operation of these
rigs is important to gain design data and confidence
in the technology, but there may be a danger of some
duplication of activities.
New process variants of the basic CaO looping cycle
are possible and more may be found.
Attrition is not the problem previously thought in
some Ca-based systems.
Some groups are also examining pelletization strategies,
and believe that they could make synthetic materials
which are both relatively cheap, durable and have excellent
long term carrying capacity
Both bubbling and entrained beds have been shown to
work successfully in the solid looping application.
Make up rates of CaO can be reduced to very low levels
There is potential advantage for combining Chemical
Looping Combustion and CO2 removal and significant advantages
might result.
Nano particles of CaO eliminate the degradation process.
They have to be deposited on a support and remain apart
from one another to avoid sintering
Mixing nano particles with another substance can do
the same but this time the nano particles of CaO are
separated by particles of the second substance. As little
as 18% of second material is sufficient.
Hydration of calcined material by different means,
including some innovative contacting devices, can restore
carbonation capacity. Exposing hydrated material to
a CO2 atmosphere enables hydrated material to be heated
above the dehydration point and further enhances the
effects of reactivation by hydration. No noticeable
reaction with CO2 is observed at temperatures up to
540C which is well above the normal decomposition temperature
for the hydrate, an observation which has yet to be
duplicated and further researched.
Mixed metal perovskites and similar compounds which
can contain variable amounts of oxygen in the lattice
are potential candidates for CLC processes.
A three step process including a hydration step has
been operated at pilot scale.
It has been demonstrated that chemical looping combustion
can be arranged so that free oxygen gas is made available
for reaction in the fuel reactor thus enabling solid
materials to be combusted using the “CLOU“
principle. (Chemical looping with Oxygen Uncoupling)
In chemical looping reforming systems it has been shown
that all of the oxygen can be removed from the feed
air if operating temperature is >900C.
It still seems to be difficult to reach 100% oxidation
of fuel in fuel reactors in CLC systems
Sulphur affects metal oxides in CLC systems but sulphur
can be more or less completely released in the air reactor
if the supply of sulphur contaminated fuel is stopped
for long enough.
Under pressurised conditions it is possible to fully
desulphurise product (to <1ppm) in a sorption enhanced
gasification and watergas shift process.
What we could do
Test various hydration schemes in small pilot plants
in continuous mode
Develop alternative equipment for transferring solids
between pressure levels
Test use of spent sorbent to remove sulphur compounds
upstream of CaO absorption systems
Test novel sorbents which have increased resistance
to chemical and mechanical degradation.
Minimise the duplication of pilot scale and demonstration
scale testing programmes (but not so far that adequate
verification/confirmation of findings is affected)
Develop equipment scale up capabilities through validated
reactor and system models.
Exchange Register
It is proposed to post details of organisations who
are:-
- Seeking testing/ development/ demonstration services
- Offering testing/ development/ demonstration services
- Seeking temporary placements for their researchers
- Offering temporary placements for other researchers
- Seeking exchange placements for their researchers
in the field of high temperature solid looping systems.
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