Page 73 - New Trends In Coal Conversion

Current status of CO 2 capture from coal facilities 39

VeloxoTherm, developed by Inventys, is a rapid TSA process based on structured
carbon adsorbents mounted on a rotary adsorption machine (RAM) with a CO 2 capture
cost of $15e30/t. A small RAM was used for field testing on a slipstream of postbag-
house coal flue gas at NRG W.A. Parish coal power plant for 671 h in 2016. The pro-
cess showed that it can withstand elevated levels of SO x and other coal flue gas
contaminants. To achieve overall performance targets, it was necessary to increase
the bed density of the structured adsorbent by using a laminate design and to use a
vacuum-assisted regeneration strategy, which implied higher energy consumption
than expected for the TSA process (Armpriester, 2016). In 2017, a small 0.5 t/d demon-
stration plant has been operated at Husky’s Pikes Peak South Lloyd thermal project for
6 months. A larger pilot plant of 30 t/d is planned to be commissioned by the end of
2018 at the same site; the CO 2 captured from a once-through steam generator will be
used for EOR near Lloydminster, Saskatchewan.
Calcium looping (CaL) is considered one of the most promising technologies to
capture CO 2 from coal-fired power plants with a projected efficiency penalty close
to 8%, or higher for novel power generation systems based on CaL technology.
CaL captures CO 2 as CaCO 3 , which is calcined to CaO releasing CO 2 . The solid gener-
ally circulates between two interconnected circulating fluidized beds that operate
at near-atmospheric pressure. The optimal temperature ranges between 580 and

700 C for the carbonator and 850e900 C for the calciner. The energy required to
regenerate the sorbent is obtained by oxy-combustion to avoid dilution of CO 2 . A rela-
tively high sorbent makeup is necessary to account for sintering, attrition, and sulfa-
tion. The spent sorbent could be partially allocated in the cement industry providing
some economic revenue. A 1.7 MW th CaL pilot plant has been operated for over
3,100 h, treating z1% of the flue gas of the 50 MW e coal-fired power plant of La Per-
eda in Asturias, Spain (Arias et al., 2017). Cost estimates are $29e50/t CO 2 .

2.2.2.4 Membrane-based POSTCC processes
Membrane Technology and Research, Inc. (MTR) has developed the proprietary mem-
brane Polaris and a novel process design that uses incoming combustion air to sweep
membranes and that recycle CO 2 to the boiler. A 20 t CO 2 /d (z1MW e ) pilot unit was
tested for over 1,500 h at NCCC in 2015. The energy consumption is estimated to be
270 kW e /t CO 2 and the capture cost $45e50/t CO 2 at 40%e80% capture rate for a
product with 99.5% CO 2 delivered at 150 bar. The pilot was moved to Babcock & Wil-
cox (B&W) research facilities in Barberton, United States, to test the fully integrated
process including selective exhaust gas recycle into a 1.8 MW th coal-fired research
boiler (Hofmann et al., 2017). Design calculations estimate that MTR’s membrane
process can capture 90% of the CO 2 in flue gas as a supercritical fluid using approx-
imately 25% of the plant power, at a cost of $40e50/t CO 2 , which translates to an in-
crease in the levelized cost of electricity (LCOE) of about 50%.
FuelCell Energy has patented the combined electric power and carbon separation
(CEPACS) system, which makes use of an electrochemical membrane formed by
ceramic layers filled with carbonate salts that separates CO 2 from flue gas with a