H2Tech - Q1 2022 - 43

INFRASTRUCTURE AND DISTRIBUTION
between a CAPEX of $511/metric t of H2
and an OPEX of $1,509/metric t of H2
.
MCH value chain. The MCH vector
consists of the four key process blocks
shown in FIG. 14. H2
hydrogenation of toluene into MCH
takes place in Qatar before transportation
to the UK. The captured CO2
is a
product for further processing before
reinjection in Qatar. Dehydrogenation
of the MCH back to H2
the UK, delivering H2
takes place in
to the natural gas
grid. FIG. 15 shows a more detailed block
flow diagram of the MCH vector with
the key material balance. H2
production
is the same SMR + CCS process as that
described for the LNG vector other than
a slightly larger capacity due primarily to
the loss in the MCH dehydrogenation
process. Infrastructure and revenue from
byproducts such as NGL and condensate
have not been considered.
MCH hydrogenation (TABLE 11) is the
hydrogenation of toluene into MCH-
the process is reversible where toluene is
essentially the carrier and reused in the
overall process. Toluene feed plus makeup
is heated through a vaporizer prior to
mixing with H2
. The mixture then enters
to produce MCH though
a fixed-bed reactor in which toluene reacts
with H2
an exothermic reaction, which occurs at
a temperature of 240°C and pressure of
10 bar in the presence of a catalyst. The
released heat is removed using a heat recovery
system. The produced MCH from
the reactor is cooled and the condensate
is separated from the gas.5
MCH is a liquid at atmospheric
pressure and temperature and contains
6.2 wt% H2
with a volumetric H2
of 47.4 kg H2/m3 (23.3 mol H2
makes MCH a good option as an H2
density
/l). This
carrier,
as it has a relatively low safety risk.6
A leading company is pioneering the
development of this novel process by
providing a proprietary MCH hydrogenation
technologya
. Although little information
is available on this technology,
FIG. 16 gives the process flow diagram and
(using this technology) suggests MCH is
produced for large-scale H2
with low cost
and 99% efficiency.
MCH and toluene storage is based on
having sufficient storage to service the
number of ships and their size. The same
storage in Qatar and the UK is assumed
based on storage tanks of 50,000 m3
caNG
H2
production
H2
MCH
hydrogenation
MCH
MCH
transportation
MCH
MCH
dehydrogenation
H2
NH3
NH3
reformer
NH3
recovery
production
and the
pacity, with a margin to allow for any delay
in ship arrival. MCH and toluene can
be stored in typical industrial chemical
storage tanks, such as atmospheric, lowpressure
(2.5 psig-15 psig) or high-pressure
fixed roof, floating roof, horizontal
or vertical cylindrical vessels. From the
literature used7
, it was not entirely clear
what had been selected and it is assumed
to be a low-pressure, fixed roof type.
MCH/toluene transportation is based
on the use of large typical oil/chemical
carriers, which is the main advantage
of this vector-the use of conventional
Fuel
Air
Steam
Water
chemical and oil
structure.7
transportation infraMCH
and toluene are in liquid
form at ambient temperature and atmospheric
pressure due to a high boiling
point. A 45,000-metric t tanker was selected;6,8
however,
this is one area of this
vector that could be optimized using fewer,
but larger, vessels. MCH is transported
to the UK and toluene is transported
back to Qatar in the same ship. MCH
has a slightly lower density and a higher
transport volume compared to toluene;
therefore, the MCH shipping requirements
dictate the shipping operation.
H2 /N2
H2
H2
purification
Recycled NH3
Power
FIG. 13. NH3 cracking.
Toluene
CO2
FIG. 14. MCH vector process blocks.
TABLE 11. MCH hydrogenation
Value chain block
MCH hydrogenation
Toluene capacity
Number of units
Capital cost
O&M
Power consumption
Natural gas consumption
Toluene consumption
Total operating cost
Total cost
Capacity
-
2,891,849 metric tpy
1
-
-
30.5 MWe
200 kWh/metric t of H2
70,533 metric tpy makeup toluene
5,967 metric tpy startup toluene
-
-
Specific value,
$/metric t of H2
Qatar
-
-
38
46
52.6
2
201
301
339
H2Tech | Q1 2022 43
Notes
[4]
H2Tech - Q1 2022

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