blown gasification. After cleanup and purification of syngas, elementary
sulfur could be obtained as by-product.
2. There are diverse ways of utilization for obtained syngas:
— town gas for cooking and heating, for distributed power, heat and
cool co-generation;
— large-scale power generation (fuel cell or gas/steam combined
cycles);
— methanol production via “once through” liquid phase reactor;
— liquid fuel production (synthetic fuel and dimethyl ether) via “once
through” liquid phase reactor;
— other chemical products (NH
3
, urea, middle distillate).
The other part of syngas can be reformed to produce hydrogen. With
the development of PEM fuel cell technology, hydrogen can be used as fuel
for vehicles and solve the transportation emission of large cities eventually,
i.e. near zero emission. From the long term point of view, hydrogen as the
energy carrier, could be utilized as cleanest fuel for distributed power, heat
and cool cogeneration for realizing local zero emission as well.
3. The treatment of separated CO
2
. When combustion process is
properly controlled, burning of cleaned syngas causes much less pollution
than conventional power plant with direct firing of coal. Therefore, the
key issue will be the treatment of green house gas CO
2
. For the proposed
polygeneration system, because of the separated CO
2
is nearly pure (99%)
instead of mixed with 75% nitrogen in the flue gas of conventional power
plant, CO
2
could be used as feedstock for different products, such as
urea, dry ice, etc. (The new development of inorganic membrane is very
promising for more efficient and economic way for CO
2
separation [4]).
It can also be used for enhancement of plant growing and other industrial
purposes. In recent years, a Canadian company is conducting the research
and experiment for enhancement of coal bed methane (CBM) production by
injecting the CO
2
to the coal seam (the depth is more than 2 km) in Albert
area. Since coal as a micro-porous substance has the greater absorption
capability to CO
2
than to CBM (mainly CH
4
)
, thus, the valuable CH
4
could be “squeezed out” and the CO
2
be sequestrated. There are also a
lot of other ways for CO
2
sequestration, e.g., to deep sea, to depleted oil
and gas fields or to saline aquifers. Surely these kinds of concepts are only
on the stage of preliminary study, the detailed technical, environmental
assessment should be conducted. But anyway, pure CO
2
will be much
easier to be treated than CO
2
in the flue gas of conventional power plants.
4. Close inter-coupling of production processes. The core of the
proposed polygeneration system is the close coupling of the production
processes of different products. For instance, after passing through the
“once through” liquid phase reactor to produce methanol (or DME),
the unreacted syngas could be directed to IGCC for power generation
instead of subsequent separation and recycling to the reactor again as it
is in conventional stand-alone methanol production. Therefore, the capital
114 ISSN 0236-3941. Вестник МГТУ им. Н.Э. Баумана. Сер. “Машиностроение”. 2006. № 1
