Technical Field
The present invention relates to, for example, a power generating system using
low quality coal such as subbituminous coal or lignite.
Background Art
For example, low quality coal such as subbituminous 5 coal or lignite generally
contains moisture, has a low carbonization degree, and has a low calorific value at the
combustion. Further, if such low quality coal is directly used as fuel for a power
generating facility (a power generating plant) such as a coal-fired power plant, the
power generation efficiency decreases and the amount of CO2 emission per unit greatly
10 increases. Accordingly, low quality coal is used as a fuel of a power generating facility,
for example, by supplying low quality coal dried and refined in advance to a boiler or
by providing a drying process before combustion in a power generating facility to
perform refining for increasing a calorific value (e.g., see Patent Literature 1).
Citation List
15 Patent Literature
[Patent Literature 1] Japanese Unexamined Patent Application, First Publication
No. H11-082991
Summary of Invention
Problem to be Solved by The Invention
20 However, when low quality coal is refined, it is necessary to obtain a heat
source for drying the low quality coal by burning the low quality coal itself or by
burning different fuel. Accordingly, the amount of CO2 emission can be reduced by
only several percent, e.g., about 2 to 3%, even when the low quality coal is refined by
applying labor and cost.
25 Further, a CO2 recovery facility (a CO2 recovery apparatus) for recovering and
removing CO2 from an exhaust gas exhausted from a boiler or the like in a power
generating facility such as a coal-fired power plant has been proposed. This CO2
3
recovery facility includes, for example, an absorption tower that brings an amine-based
CO2 absorption liquid into contact with an exhaust gas so that CO2 in the exhaust gas is
absorbed into the CO2 absorption liquid, and a regeneration tower that dissociates and
recovers CO2 by heating, using steam, the CO2 absorption liquid that has absorbed CO2
in the absorption tower to 5 regenerate the amine CO2 absorption liquid.
Further, when such a CO2 recovery facility is applied to a power generating
facility such as a coal-fired power plant, steam generated in a boiler is used for
regeneration of the CO2 absorption liquid in the regeneration tower, which may cause
degradation of turbine efficiency, and thus degradation of the amount of power
10 generated of, for example, 20 to 30%. Furthermore, when low quality coal is used as
fuel, degradation of recovery efficiency of CO2 and degradation of the amount of power
generated may be caused.
Further, when a CO2 recovery apparatus is applied to a coal-fired power plant, it
is necessary to treat a large amount of exhaust gas, which may increase facility cost and
15 cause a great increase in the cost of power generation.
Means for Solving the Problem
According to a first aspect of the present invention, a power generating system
using low quality coal is a power generating system using low quality coal as fuel for a
boiler to perform power generation, and includes a low quality coal refining facility that
20 heats the low quality coal to refine the low quality coal into high-grade coal; a CO2
recovery facility that recovers CO2 from an exhaust gas generated by refining the low
quality coal in the low quality coal refining facility, while using steam generated by
refining the low quality coal in the low quality coal refining facility; and a power
generating facility that performs the power generation using, as fuel, the high-grade coal
25 obtained by refining the low quality coal in the low quality coal refining facility.
In the power generating system using low quality coal, the power generating
system may include a CO2 transportation facility for transporting CO2 recovered in the
CO2 recovery facility to an oil production plant.
In the power generating system using low quality coal, the low quality coal
4
refining facility may be provided near a coal mine from which the low quality coal is
produced.
In the power generating system using low quality coal, the CO2 transportation
facility may be a pipeline that connects the low quality coal refining facility with the
5 CO2 recovery facility.
Effects of Invention
In the power generating system using low quality coal described above, it is
possible to improve a calorific value and thus improve power generation efficiency of a
coal-fired power plant by refining the low quality coal in the low quality coal refining
10 facility provided separately from a power generating facility.
Further, it is possible to reduce the amount of exhaust gas at the time of use as
boiler fuel by treating, in the CO2 recovery facility provided separately from the power
generating facility, the exhaust gas exhausted by refining the low quality coal in the low
quality coal refining facility, and reduce the amount of emissions of environmental
15 pollution such as CO2, SOX, NOX, and Hg. Accordingly, it is possible to reduce capital
costs and operational costs of a pollution control facility.
Brief Description of Drawings
Fig. 1 is a diagram illustrating a power generating system according to an
embodiment of the present invention.
20 Description of Embodiments
Hereinafter, a power generating system using low quality coal according to an
embodiment of the present invention will be described with reference to Fig. 1.
A power generating system A using low quality coal of the present embodiment
includes a low quality coal refining facility 3 that refines low quality coal (coal having
25 low quality) 2 such as subbituminous coal or lignite produced from a mine 1, a power
generating facility 5 that performs power generation using, as a fuel, high-grade coal
(coal having high quality) 4 obtained by refining the low quality coal 2 in the low
5
quality coal refining facility 3, and a CO2 recovery facility 6 that recovers CO2
generated in the low quality coal refining facility 3, as shown in Fig. 1.
The low quality coal refining facility 3 is a facility that heats the low quality
coal 2 to refine the low quality coal 2 into the high-grade coal 4, and includes, for
example, a drying/dry distillation apparatus that performs 5 a drying treatment or a dry
distillation treatment to heat the low quality coal 2 and vaporize moisture.
The power generating facility 5 is a coal-fired power generating facility that
includes a boiler that generates steam using coal as fuel, and a turbine driven by the
steam generated in the boiler. Further, this power generating facility 5 is configured to
10 perform power generation, for example, by driving a high pressure turbine by high
pressure and high temperature steam generated in the boiler, overheating an exhaust gas
of the high pressure turbine in a re-superheater of the boiler, driving a moderate pressure
turbine by re-overheated moderate pressure steam, and driving a low pressure turbine
using an exhaust gas of the moderate pressure turbine. Further, the power generating
15 facility 5 includes an exhaust gas treating facility such as a condenser, a desulfurization
apparatus, and a chimney.
The CO2 recovery facility 6 includes an absorption tower for receiving exhaust
gas 7 and steam 8 generated by heating the low quality coal 2 in the low quality coal
refining facility 3 and bringing the exhaust gas 7 into contact with CO2 absorption
20 liquid to absorb and remove CO2 from the exhaust gas 7, and a regeneration tower for
receiving the CO2 absorption liquid that has absorbed CO2 in the absorption tower and
separating and recovering CO2 absorbed into the CO2 absorption liquid.
In the absorption tower, an absorption liquid scrubber that sprays the CO2
absorption liquid in a mist form is provided therein, and the CO2 absorption liquid
25 sprayed from this absorption liquid scrubber and the exhaust gas 7 introduced from the
low quality coal refining facility 3 to the inside of the absorption tower through a
communication duct and flowing from a lower part of the absorption tower to an upper
part thereof are brought into contact with each other. Accordingly, CO2 in the exhaust
gas 7 is dissolved in and absorbed into the CO2 absorption liquid, and the treated
30 exhaust gas from which CO2 has been removed is released from the upper part to the
6
outside. Further, the CO2 absorption liquid having absorbed CO2 is accumulated in the
lower part of the absorption tower.
Further, it is desirable for the absorption tower to be configured to include a
scrubber or a demister that sprays cooling water in a mist form, which is provided above
the internal absorption liquid scrubber, and 5 to capture and remove, using the cooling
water, gaseous substances and particulate substances in the exhaust gas 7 that have not
been collected into the CO2 absorption liquid.
Further, for example, an amine-based absorption liquid may be adopted as the
CO2 absorption liquid. Specifically, an alkanolamine such as monoethanolamine,
10 diethanolamine, triethanolamine, methyldiethanolamine, diisopropanolamine, or
diglycolamine may be adopted as the CO2 absorption liquid. Further, hindered amines
may be adopted. Further, each water solution of the material or a water solution
obtained by mixing two or more of the materials may be used as the CO2 absorption
liquid.
15 The regeneration tower separates and recovers CO2 from the CO2 absorption
liquid that has absorbed CO2 or the like in the absorption tower. An absorption liquid
transportation pipe for introducing the CO2 absorption liquid from the absorption tower
is connected to an upper part of the regeneration tower. Further, the CO2 absorption
liquid accumulated in the lower part of the absorption tower is sprayed and supplied
20 from the upper part to the inside of the regeneration tower by driving a liquid
transportation pump of the absorption liquid transportation pipe. Further, in the
regeneration tower, high temperature steam is supplied from the lower part and the
sprayed CO2 absorption liquid is heated. Accordingly, CO2 is dissociated from the
CO2 absorption liquid and desorbed, and the desorbed CO2 is derived from the upper
25 part of the regeneration tower to the outside. Further, the derived CO2 is cooled,
compressed in a compressor, and is recovered as compressed CO2.
In this case, in the present embodiment, the steam 8 generated when the low
quality coal 2 is heated and refined into the high-grade coal 4 in the low quality coal
refining facility 3 is provided to the regeneration tower, and the CO2 absorption liquid is
30 heated using the steam 8 generated in the low quality coal refining facility 3.
7
Accordingly, it is unnecessary to separately supply steam generated in a boiler or the
like to the regeneration tower.
Further, the CO2 absorption liquid from which CO2 has been dissociated and
removed in this way is accumulated in the lower part of the regeneration tower, a return
pump provided in an absorption liquid supply 5 pipe is driven, and the CO2 absorption
liquid is cooled by a cooler and sent to the absorption tower. In other words, in the
present embodiment, the CO2 absorption liquid having absorbed CO2 or the like is sent
from the absorption tower to the regeneration tower through the absorption liquid
transportation pipe, and the CO2 absorption liquid from which CO2 has been recovered
10 in the regeneration tower is returned from the regeneration tower to the absorption
tower through the absorption liquid supply pipe again, to thereby circulate the CO2
absorption liquid between the absorption tower and the regeneration tower so that the
recovery of CO2 is performed.
A simulation result for the power generating system using low quality coal of
15 the present embodiment will be described herein. First, for example, the low quality
coal refining facility 3 produces the high-grade coal 4 whose calorific value is 11,340
Btu/lb at a rate of 178 ton/h by treating the low quality coal 2 whose calorific value is
8,000 Btu/lb at a rate of 308 ton/h. Accordingly, it was confirmed that when the highgrade
coal 4 is used as fuel of the boiler of the coal fired power generating facility 5, a
20 great calorific value can be obtained with a small amount of the high-grade coal 4 and
the power generation efficiency increases by 2%. Further, when the low quality coal 2
is refined into the high-grade coal 4 in the low quality coal refining facility 3 in this way,
CO2 (10% -wet) of 2,778 tpd and the exhaust gas 7 of 586,835 Nm3/h are generated.
Further, when the high-grade coal 4 refined in the low quality coal refining
25 facility 3 is used as the fuel of the boiler of the coal fired power generating facility 5,
the amount of CO2 emissions are reduced to 9,246 tpd as compared with the amount of
CO2 emissions being 9,703 tpd when the lower coal 2 is used. Further, when the
exhaust gas 7 exhausted from the low quality coal refining facility 3 is treated in the
CO2 recovery facility 6 configured as described above, CO2 in the exhaust gas 7 can be
30 recovered at a recovery rate of 90%, recovering CO2 of 2,500 tpd.
8
Further, according to the power generating system using low quality coal of the
present embodiment, it was confirmed that a total CO2 exhaust ratio is changed from
940 ton/GWh to 881 ton/GWh, and a reduction of about 6%, as compared with a case in
which the low quality coal 2 is directly used.
Here, in an oil production plant, when the 5 amount of collection of the oil using
a primary collection method is decreased, artificial oil discharge energy is given to an
oil layer to increase the amount of collection of the oil and increase a recovery rate of
the oil. Further, an enhanced oil (crude oil) recovery technique (EOR: Enhanced Oil
Recovery) includes a water flooding method of injecting water, a method of injecting
10 natural gas, CO2 or the like, a thermal recovery method, or a chemical method.
For example, the low quality coal refining facility 3 is provided near the coal
mine 1 from which the low quality coal 2 is produced, the CO2 recovery facility 6 is
provided near the low quality coal refining facility 3, and a CO2 transportation facility
that transports CO2 recovered in the CO2 recovery facility 6 to the oil production plant
15 is provided, and this CO2 transportation facility includes a pipeline that connects the
CO2 recovery facility 6 with the oil production plant, thereby constituting the power
generating system A. With this configuration, it is possible to efficiently refine the low
quality coal 2 in the low quality coal refining facility 3, the low quality coal 2 produced
from the coal mine 1 and produce the high-grade coal 4, and to efficiently treat the
20 exhaust gas 7 in the CO2 recovery facility 6, the exhaust gas 7 generated by refining the
low quality coal 2 in the low quality coal refining facility 3.
Further, when the CO2 transportation facility such as the pipeline transporting
CO2 recovered in the CO2 recovery facility 6 to the oil production plant is provided,
compressed CO2 recovered in the CO2 recovery facility 6 can be supplied to the oil
25 production plant and used as CO2 for EOR. Further, CO2 recovered in the CO2
recovery facility 6 may be accumulated deep underground to prevent CO2 from being
released to the atmosphere and causing global warming.
Accordingly, in the power generating system using low quality coal of the
present embodiment, it is possible to improve a calorific value and thus to improve the
30 power generation efficiency of the coal-fired power plant 5 by refining the low quality
9
coal 2. Further, it is necessary to pulverize the low quality coal 2 when the low quality
coal 2 is used as the fuel of the boiler, while it is possible to reduce mill power by
refining the low quality coal 2. Furthermore, when there is a sufficient turbine
capacity, it is possible to increase the amount of power generated and achieve increase
in power generating revenue by increasing the amount 5 of using of the low quality coal 2
(the amount of supply of the refined low quality coal).
Further, it is possible to reduce the amount of exhaust gas at the time of use as
the boiler fuel and reduce the amount of emissions of environmental pollution such as
CO2, SOX, NOX, and Hg, by refining the low quality coal 2. Accordingly, it is possible
10 to reduce capital costs and operational cost of a pollution control facility.
Further, it is possible to remove the environmental pollution such as CO2, SOX,
NOX, and Hg, and minimize emission reduction measure costs for the environmental
pollution, by treating the exhaust gas 7 from the low quality coal refining facility 3 with
the CO2 recovery facility 6,.
15 Further, it is possible to reduce the amount of CO2 emissions and use recovered
CO2 for, for example, EOR by treating CO2 in the exhaust gas 7 from the low quality
coal refining facility 3 with the CO2 recovery facility 6 which provided separately from
the power generating facility 5,.
Further, since the amount of exhaust gas can be reduced in the case in which the
20 low quality coal 2 is refined in the low quality coal refining facility 3 compared with a
case in which the low quality coal 2 is directly used in the power generating facility 5,
remodeling of an existing facility is minimized and facility costs can be greatly reduced.
Furthermore, by using the steam 8 generated with the low quality coal refining
facility 3 with the CO2 recovery facility 6, it is possible to cause a power penalty to be
25 zero and build an efficient power generating system using low quality coal.
While the embodiment of the power generating system using low quality coal
according to the present invention has been described above, the present invention is not
limited to the embodiment and may be appropriately modified without departing from
the scope and spirit of the present invention.
10
Industrial Applicability
In the power generating system using low quality coal described above, it is
possible to improve a calorific value and thus improve power generating efficiency of a
coal-fired power plant by refining the low quality coal in the low quality coal refining
facility provided separately from t 5 he power generating facility.
Further, it is possible to reduce the amount of exhaust gas at the time of use as
boiler fuel and reduce the amount of environmental pollution such as CO2, SOX, NOX,
or Hg, by treating, in the CO2 recovery facility provided separately from the power
generating facility, the exhaust gas exhausted by refining the low quality coal in the low
10 quality coal refining facility. Accordingly, it is also possible to reduce the capital cost
and operational costs of a pollution control facility.
Reference Signs List
1 mine (coal mine)
2 low quality coal
15 3 low quality coal refining facility
4 high-grade coal
5 power generating facility
6 CO2 recovery facility
7 exhaust gas
20 8 steam
A power generating system using low quality coal

We Claim:
1. A power generating system using low quality coal as fuel for a boiler to perform
power generation, the power generating system comprising:
a low quality coal refining facility that heats the low quality coal to
refine the low quality 5 coal into high-grade coal;
a CO2 recovery facility that recovers CO2 from an exhaust gas
generated by refining the low quality coal in the low quality coal refining facility,
while using steam generated by refining the low quality coal in the low quality
coal refining facility; and
10 a power generating facility that performs the power generating using,
as fuel, the high-grade coal obtained by refining the low quality coal in the low
quality coal refining facility.
2. The power generating system using low quality coal according to claim 1,
15 further comprising:
a CO2 transportation facility for transporting CO2 recovered in the CO2
recovery facility to an oil production plant or a geological storage site.
3. The power generating system using low quality coal according to claim 1,
20 wherein:
the low quality coal refining facility is provided near a coal mine from
which the low quality coal is produced.
4. The power generating system using low quality coal according to claim 2,
25 wherein:
12
the low quality coal refining facility is provided near a coal mine from
which the low quality coal is produced.
5. The power generating system using low quality coal according to claim 2,
5 wherein:
the CO2 transportation facility is a pipeline that connects the low
quality coal refining facility with the CO2 recovery facility.
6. The power generating system using low quality coal according to claim 3,
10 wherein:
the CO2 transportation facility is a pipeline that connects the low
quality coal refining facility with the CO2 recovery facility.
7. The power generating system using low quality coal according to claim 4,
15 wherein:
the CO2 transportation facility is a pipeline that connects the low quality
coal refining facility with the CO2 recovery facility.