Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The invention relates to a high temperature or hot gas system,
wherein a rotation or rotary flow centrifugal separator with a suction device
for its bunker chamber or hopper is disposed between a fluidized bed furnace
and a gas turbine.
To improve the effectiveness or efficiency of power plants opera-
ting with coal as the basic fuel, the so-called fluidized bed furnace has been
used to an increasing extent lately. In this type of furnace the exhaust or
flue gases have, for example, a temperature of 900C and up to 12 atmospheres
gauge pressure, and are to be utilized further in gas turbines. It is under-
standable that the exhaust gases must be first thoroughly purified. For this
purpose the use of a rotary flow or tornado centrifugal separator has been
proposed (see AIChE-Symposium-Series, No. 126, Volume 68, pages 270 to 271).
A centrifugal separator of this type for the disposition of particles from
gases, includes a cylindrical spin or centrifugal chamber, a coaxial feed tube
for the crude gas ending in a pre-spin nozzle, a bunker shield or hopper sur-
rounding the feed or inlet tube having a discharge slot for the particles
leading into the chamber adjacent the periphery of the spin chamber, an outlet
for the purified gas opposite the spin chamber, an auxiliary gas outlet sur-
rounding the outlet for the purified gas, and an inlet for auxiliary gas which
is blown into the device tangentially and at an incline.
To increase the separation efficiency of a centrifugal separator
used in a fluidized bed furnace~ it is already known to connect the hopper,
through a pipeline which can be regulated, to a point of the dust removal sys-
tem or centrifugal separator, at which the pressure is lower than the pressure
in the hopper. In this way, a relatively negative pressure can be produced in
the hopper, and thus the amount of removed dust discharged through the output
slot can be increased (see, for example United States Patent No. 4,272,260).
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It is accordingly an object of the invention to provide a high
temperature gas system, which overcomes the hereinafore-mentioned disadvantages
of the heretofore--known devices of this general type, and to increasethe total
efficiency of a system of this type.
With the foregoing and other objects in view there is provided, in
accordance with the invention, a high temperature gas system, comprising a
rotary flow centrifugal separator having a hopper or bunker and means connected
to the hopper for removing gas from the hopper by suction, a fluidized bed
furnace connected upstream of the rotary flow centrifugal separator, a gas
turbine connected downstream of the rotary flow centrifugal separator, and means
connected to the gas removing means for returning at le~st part of the gas
removed from the hopper by suction to the fluidized bed furnace. Since in the
invention the greater part of the gas, or all of the sucked-off gas, can be
circulated in actual practice, only very little energy is lost; ~im~lly per-
haps only the energy required to maintain the pressure.
In accordance with another feature of the invention, there is
provided a heat exchanger and means for tapping combustion air from the fluid-
ized bed furnace through the heat exchanger disposed in the fluidized bed
furnace to the rotary flow centrifugal separator for use as secondary air for
creating rotary flow in the separator.
In accordance with a further feature of the invention, there is
provided a cyclone separator disposed between the fluidized bed furnace and the
rotary flow centrifugal separator, and means for returning products separated
in the cyclone separator to the fluidized bed furnace.
In accordance with an added feature of the invention, the means for
removing gas from the hopper includes a blower.
In accordance with a concomitant feature of the invention, the means
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for returning at least part of the gas removed from the hopper to the fluidized
bed furnace includes an additional rotary flow centrifugal separator, for
cleaning the gas removed from the hopper, and means for supplying combustion
air of the fluidized bed furnace as secondary air to the additional rotary
flow centrifugal separator to effect rotary flow.
Other features which are considered as characteristic for the
invention are set forth in the appended claims.
Although the invention is illustrated and described herein as em-
bodied in a high temperature gas system, it is nevertheless not intended to be
limited to the details shown, since various modifications and structural changes
may be made therein without departing from the spirit of the invention and
within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however,
together with additional objects and advantages thereof will be best understood
from the following description of specific embodiments when read in connection
with the accompanying drawings, in which:
Figure 1 is a diagrammatic elevational view of a system according
to the invention, including a fluidized bed furnace, a centrifugal or rotary
flow separator and a gas turbine connected thereto; and
Figures 2 and 3 are views similar to Figure 1 showing modifications
of the system according to Figure 1, with respect to the exhaust of the bunker.
Referring now to the figures of the drawing and first particularly
to Figure 1, thereof, it is seen that the combustion or flue gases from a
fluidized bed furnace l are conducted to a cyclone separator 2, for example at
a temperature of 900C and at 8 atmospheres gauge pressure 8 atu), for separat-
ing the coarse particles. As shown in the drawing, the separated soot and ash
particles are fed back through apipeline 21 by means of a feeding device 15
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(see, for example, the publication VDI-Berichte, 1978, No. 322, pages 80 and
81) into the fluidized bed furnace, together with coal 13 which is to be
burned, while the combustion gases which leave the cyclone 2 through a line 22
are conducted to a centrifugal rotary flow separator 3 for a further purifi-
cation of the combustion gas. From the separator 3, the purified gas is fed
through a diagrammatically illustrated line 31 to a gas turbine 4 which drives
a generator 5. From the turbine 4, the gas flows through a heat exchanger 7
and a line 71 to a smokestack 72.
Combustion air for the fluidized bed furnace 1 is drawn in through
the heat exchanger 7 by a condenser 6, which is also driven by the gas turbine
4. In a heating tube 11, which is provided in the fluidized bed furnace 1,
hot or superheated steam is generated for driving a steam turbine 8, which works
in conjunction with a generator 82 and a condenser 81.
Secondary air required for the operation of the rotary flow centri-
fugal separator 3 is taken from the combustion air supply downstream of the
condenser 6 in order to create flow circulation, and conducted to the centri-
fugal separator 3 through a heat exchanger 12 which is disposed in the fluidized
bed furnace 1, and through a line-32.
The ashes deposited in the hopper or bunker chamber 36 of the
centrifugal separator 3 are removed through a bunker outlet 33. To increase
the effectiveness of the centrifugal rotary 10w separator 3, dust laden, hot
air is drawn by suction from the bunker chamber or hopper 36 and is conducted
back into the fluidized bed furnace 1 through a line 34. The eeding device
15 through which crushed coal 13 is fed under pressure into the fluidized bed
furnace 1, also serves for feeding the hot air back into the-furnace. For this
purpose, compressed air is tapped off from the outlet of the condenser 6 through
a line 14, to serve as delivery air.
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In the apparatus shown in Figure 2, the cyclone has been
omitted. A blower 35 is disposed in the line 34 which leads back
from the bunker chamber or hopper 36 of the centrifugal rotary
flow separator 3 to the fluidized bed furnace 1.
In the apparatus shown in Figure 3, an additional rotary
flow centrifugal separator 9 is provided between the suction means
in the bunker chamber or hopper 36 of the centrifugal separator
3 and the feedback line of the sucked off bunker or hopper air
leading to the fluidized bed furnace 1. The drawn off gases from
the bunker chamber or hopper 36 reach the centrifugal separator
9 as raw or crude gas ~hrough the line 34, and leave the separa-
tor in a purified state. The purified gases are conducted to the
fluidized bed furnace 1 through a line 92. The ash particles and
soot particles disposed in the bin or hopper 91 of the rotary flow
centrifugal separator 9 are fed into the feed hopper for the coal
13. A line 93 is provided for supplying secondary air for the
centrifugal rotary flow dust separator 9, which allows a part of
the combustion air to be branched off from the outlet of the
condenser or compressor 6. The secondary air flowing through
the line 93 can also be conducted through a non-illustrated heat
exchanger disposed in the fluidized bed furnace. The secondary
air for the centrifugal rotary flow separator 3 is taken from the
crude gas flowing through the line 35.
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