Power plants – Combustion products used as motive fluid – Multiple fluid-operated motors
Reexamination Certificate
2001-01-22
2001-09-25
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
Multiple fluid-operated motors
C060S039464
Reexamination Certificate
active
06293087
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combined electricity generation system which combines two methods for generating electricity in which a steam turbine is driven by steam generated from a pressurized fluidized bed boiler and a gas turbine is driven using the exhaust gas from the boiler.
2. Description of the Related Art
Pressurized fluidized bed combined electricity generation systems are electricity generation systems which combine two methods such that electricity is generated by driving a steam turbine with steam generated from a fluidized bed boiler housed within a pressurized container, and electricity is generated by driving a gas turbine by introducing exhaust gas from the pressurized fluidized bed boiler into the gas turbine. For the combustion which occurs in the pressurized fluidized bed boiler, air for combustion is introduced into the boiler in a pressurized state from a compressor, crushed coal is added to the fluidized bed in which limestone forms the fluid medium, and combusted in a fluid state. A steam pipe is arranged within this fluidized bed, steam is generated due to the heat of combustion in the fluidized bed, the steam turbine is driven and electricity is generated. In addition, with this type of combustion, since limestone is used, it is possible to conduct desulferization within the furnace at the same time.
Further explaining the principle of the fluidized bed boiler mentioned above, an air dispersion plate is provided in the bottom of a container and solid particles are charged into the part above the air dispersion plate. Air is blown uniformly from the bottom of the air dispersion plate and when the amount of air is increased, solid particles move vigorously and randomly within a layer of a certain height above the air dispersion plate. The solid particle layer which is floated and fluidized of a fluid in this way is referred to as a fluidized bed and the combustion in a fluid state of liquid fuel or solid fuel of a suitable size added to this fluidized bed is fluidized bed combustion.
FIG. 9
is a schematic diagram showing an example of the pressurized fluidized bed combined electricity generation system explained above.
In
FIG. 9
, the entire pressurized fluidized bed boiler
1
comprises a pressurized container
10
and a boiler
11
therewithin. A coal/limestone supply device
12
supplies the limestone which forms the fluid medium and the coal starting materials to the boiler
11
. A cyclone
13
removes particles which are noncombustible, and the like, from the exhaust gas from the boiler
11
. A dust collecting device
14
comprises a ceramic filter, and ash and the like are filtered and removed by this ceramic filter. A gas turbine
15
is directly coupled to the compressor
16
, and is driven by high temperature exhaust gas from the dust collecting device
14
. Also, there is a denitrification device
17
a high pressure exhaust heat recovery/supply-water heater
18
and a low pressure exhaust heat recover/supply-water heater
19
. The high pressure exhaust heat recovery/supply-water heater
18
and the low pressure exhaust heat recover/supply-water heater
19
recover exhaust heat from the exhaust gas and preheat the water being supplied to the boiler
11
using this exhaust heat. A chimney
20
discharges the exhaust gas to the atmosphere.
In addition, in
FIG. 9
, there is a steam turbine
21
and a condenser
22
to which cold water is sent by
9
pump
51
and in which steam from the steam turbine
21
is cooled and condensed. A low pressure supply-water heater
23
heats the condensed water and regulates the temperature of the supply water. A deaerator
24
removes air bubbles from the supply water. A drum
25
supplies water to each of the pipes of boiler
11
, that is, to main steam pipe system
30
, reheating gas pipe system
31
and boiler circulation pipe system
32
.
In the pressurized fluidized bed combined electricity generation system of the above-described structure, the limestone which is the fluidized bed medium and the coal starting material from the coal/limestone supply device
12
is sent to the boiler
11
by
9
supply system
41
, while air from the compressor
16
is blown into the boiler
11
by an air system pipe
42
, a fluidized bed is formed by this limestone, and the coal is burned, thereby, fluidized bed combustion is carried out.
At the same time, supply water that has been heated in advance is supplied from the drum
25
to the main steam pipe system
30
. The main steam pipe system
30
is heated by the boiler
11
, steam is generated and the high pressure turbine of steam turbine
21
is driven. The steam discharged therefrom is returned to the boiler
11
again, it is reheated, run back into the steam turbine
21
a second time by the reheating steam pipe system
31
, drives the low pressure turbine, and flows to the condenser
22
. In addition, the supply water in the drum
25
circulates between the boiler
11
and the drum
25
by the boiler circulation pipe system
32
such that it is heated.
Next, large particles are removed by the cyclone
13
, ash and the like are removed by the dust collecting device
14
, then the combustion exhaust gas from the boiler
11
is supplied to the gas turbine
15
, the turbine
15
is driven and electricity is generated. The exhaust gas which drives the gas turbine
15
is denitrified by the denitrification device
17
. Then the remaining heat in the exhaust gas is used to heat the supply water being supplied to the boiler
11
by each of the high pressure exhaust heat recovery/supply-water heater
18
and the low pressure exhaust heat recover/supply-water heater
19
. Thereafter, the exhaust gas is discharged to the atmosphere from chimney
20
.
The exhaust steam which drives the steam turbine
21
is condensed and liquefied by the condenser
22
to which cold water is sent by the pump
51
, this condensed water is sent to the low pressure supply-water heater
23
by a pump
52
where it is heated and its temperature adjusted. Then it is preheated by exhaust gas in the low pressure exhaust heat recover/supply-water heater
19
and is sent to a deaerator
24
and bubbles are removed. The supply water from the deaerator
24
is sent to the high pressure exhaust heat recovery/supply-water heater
18
by a pump
53
where it is preheated again and then sent to drum
25
by pipe
33
.
In the above-described pressurized fluidized bed combined electricity generation system, there is a combined cycle system which generates electricity by driving the steam turbine
21
and by the gas turbine
15
using the exhaust gas from the boiler
11
, and it obtains high electricity generation efficiency. In addition, since the boiler
11
is housed inside the pressurized container
10
, it can be made to be compact. In addition, since limestone is used as the fluid medium, desulferization can be carried out within the boiler
11
, an exhaust gas desulferizer is not necessary, and it is possible to make the plant equipment area smaller compared with the past.
In the above-described pressurized fluidized bed combined electricity generation system, there is a combined cycle method in which a turbine is driven by steam generated by the pressurized fluidized bed boiler
1
, the gas turbine
15
is driven by exhaust gas from the pressurized fluidized bed boiler
1
, and it is possible to obtain high electricity generation efficiency. It is also possible to make the apparatus compact. In this type of system, the output of the gas turbine
15
is influenced by the characteristics of the fuel used (coal), the combustion method of the pressurized fluidized bed boiler
1
(combustion temperature, layer height), and the like, however, it depends greatly on the temperature of the intake air of the compressor
16
of the gas turbine
15
and the air-fuel ratio for combustion in the pressurized fluidized bed boiler
1
.
The temperature of the intake air of the compressor
16
can be varied intentionally by operation using intake of air from in
Abe Katsuhiko
Fujii Fuminori
Hyakutake Yoshinori
Kato Makoto
Masuda Yoshifumi
Casaregola Louis J.
Mitsubishi Heavy Industries Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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