Technical Field
[0001] The present invention relates to a burner for a biomass solid fuel boiler, and more
particularly, to a burner for a boiler using solid fuel, such as wood pellets, which
is being spotlighted as biomass energy.
[0002] The present invention relates to a biomass solid fuel boiler burner adapted to realize
a new type of combustion, i.e. combustion occurs in a specific area, into which air
(oxygen) is supplied by a blower, while fuel is being fed by a screw, inside which
water circulates, thereby guaranteeing durability of the screw against the high temperature
caused by combustion, completely processing sludge and ash, simplifying the overall
boiler structure (e.g. substantially reducing the size of the boiler using solid fuel),
and reducing manufacturing costs.
[0003] In addition, the present invention relates to a biomass solid fuel boiler burner
including a screw formed as a hollow pipe inside the combustion chamber of the boiler
to discharge sludge and ash, a circulation fan or a compressor adapted to circulate
a fluid inside the hollow portion of the screw, and a cooler positioned outside the
combustion chamber to cool the circulating fluid (gaseous air, liquid refrigerant,
etc.) so that the fluid lowers the high temperature inside the combustion chamber,
thereby improving operations and functions for efficient processing of sludge and
ash while guaranteeing durability of the screw inside the combustion chamber against
the high temperature caused by combustion.
Background Art
[0004] Recent global warming and resulting climate change are regarded as a serious threat
to the survival of mankind, and such recognition is followed by growing interest in
renewable energy and soaring investment to replace existing fossil fuels.
[0005] In this connection, there is vigorous research on boilers using biomass solid fuel,
other than conventional boilers using coal.
[0006] Biomass solid fuel typically refers to a type of renewable energy extracted from
energy-dedicated crops and trees, agricultural products and fodder crops, farm wastes
and leftovers, etc.
[0007] Use of such biomass solid fuel is advantageous not only because energy is self-sustained,
but also because environment contamination is reduced substantially.
[0008] Current boiler combustion types for using biomass solid fuel include a movable grate
type, which is conventionally employed when coal is used as a fuel, and which is based
on conveyor belt or chain driving, a burner type commonly employed to burn wood pellets,
a crucible type, a dish type, etc.
[0009] However, conventional boiler combustion types have the following problems.
[0010] The movable grate type, which is based on a conveyor belt (chain), etc., has a complicated
mechanical structure, which increases the manufacturing cost. And the fact that a
large space is occupied below the boiler makes it difficult to manufacture a high-efficiency
boiler (burner). Therefore, this type is not suitable for small-sized boilers (e.g.
domestic boilers).
[0011] The burner type and crucible type, which are commonly employed to burn wood pellets,
have problems related to processing of sludge and ash, which are generated in a large
amount when low-quality pellets are burnt. This is one of fundamental reasons of malfunctioning
of boilers. The burner structure of these types makes it impractical to manufacture
medium and large-sized boiler burners for commercial and industrial purposes.
Disclosure
Technical Problem
[0012] In order to develop a burner for burning solid fuel capable of automatically discharging
ash, which is an unavoidable byproduct of complete combustion of solid fuel, and sludge,
which is generated when alien substances and impurities included in the solid fuel
are burnt at a high temperature and intermingled with the ash, there could be found
usefulness by using a spring-type screw to feed fuel at a low rate, completely burn
it as it goes through a combustion area, and automatically transfer resulting ash
and sludge to the outlet. However, application of this type has a fundamental problem
in that conventional screw material, e.g. iron or stainless steel, cannot endure high-temperature
flames occurring in the combustion area, only to be deformed or melt down.
[0013] Therefore, the present invention has been made in view of the above-mentioned problems,
and an aspect of the present invention is to provide a biomass solid fuel burner and
a boiler burner adapted to realize a new type of combustion, i.e. combustion occurs
in a specific area, into which air is supplied by a blower, while fuel is being fed
by a screw, inside which water circulates, thereby guaranteeing durability of the
screw against the high-temperature flames caused by combustion, accurately controlling
the amount of combustion by adjusting the rotation and feed rates of the screw, completely
processing sludge and ash generated by combustion, simplifying the overall boiler
structure (e.g. substantially reducing the size of the boiler combustion chamber),
and reducing manufacturing costs.
[0014] Another aspect of the present invention is to improve durability of the screw by
using a refrigerant (e.g. gas or liquid) injected separately, not using water existing
in the piping of the boiler, as the fluid circulating inside the screw, thereby lowering
the temperature of the screw, which is inside the high-temperature combustion chamber,
sufficiently.
[0015] Another aspect of the present invention is to improve durability of the screw, which
is adapted to discharge sludge and ash from the boiler combustion chamber, by lowering
the temperature of the screw more efficiently using a cooler adapted to separately
cool the high-temperature fluid, which circulates inside the screw, outside the boiler
combustion chamber.
Technical solution
[0016] In accordance with an aspect of the present invention, there is provided a biomass
solid fuel boiler including a fuel supplier adapted to supply solid fuel; a combustion
device adapted to burn the solid fuel; and a boiler body adapted to heat water using
combustion heat, wherein the combustion device includes a combustion chamber having
a solid fuel supply hole on a front side and a sludge/ash discharge hole on a rear
side, the solid fuel being burnt in the combustion chamber; a screw arranged along
and in parallel with the interior of the combustion chamber and installed so as to
rotate, the screw including a hollow pipe, inside which water circulates so that the
screw can endure high temperature inside the combustion chamber, the screw being adapted
to both feed the solid fuel and discharge sludge and ash through a rotating operation;
a driver installed on a front portion of the combustion chamber to rotate the screw;
and an igniter installed on a lateral portion of the combustion chamber to ignite
the solid fuel. This construction improves fuel efficiency and effectively processes
sludge and ash.
[0017] The biomass solid fuel boiler preferably further includes a blowing device installed
below the combustion chamber to inject air necessary for combustion into the combustion
chamber. The screw is preferably wound in the shape of a spring having straight portions
on both ends adapted to act as fulcrums during rotation. Alternatively, the screw
is preferably connected to a boiler water tube to receive water in the boiler water
tube forcibly circulated by a circulation pump.
[0018] The screw may be adapted so that its size can be adjusted based on boiler capacity,
and a plurality of screws can be arranged in parallel and used.
[0019] Besides the construction of connecting the screw to the water tube of the boiler
to circulate water, it is also possible to employ fluid (gas or liquid refrigerant),
which can be cooled by an external cooler, and use a separate compressor or a fan.
Advantageous Effects
[0020] The biomass solid fuel boiler according to the present invention has the following
advantages:
The circulation pump forcibly circulates water inside the screw, which is adapted
to feed solid fuel during combustion and discharge sludge and ash, so that the screw
can endure high-temperature combustion conditions. This guarantees perfect processing
of sludge and ash, which is a problem of solid fuel boilers, and enables complete
combustion. The fact that the overall boiler structure, specifically structure of
the burner, can be simplified makes the present invention applicable to domestic small-sized
boilers. Furthermore, adjustment of the size of the screw, inside which water circulates,
and possibility of multi-rowed arrangement structure make the present invention applicable
to large-capacity boilers, such as industrial large-sized boilers and cogeneration
plants.
[0021] In addition, durability of the screw is improved by using a refrigerant (e.g. gas
or liquid) injected separately, not using water existing in the piping of the boiler,
as the fluid circulating inside the screw, thereby lowering the temperature of the
screw, which is inside the high-temperature combustion chamber, sufficiently.
[0022] Furthermore, durability of the screw, which is adapted to discharge sludge and ash
from the boiler combustion chamber, is improved by lowering the temperature of the
screw more efficiently using a cooler adapted to separately cool the high-temperature
fluid, which circulates inside the screw, outside the boiler combustion chamber.
Brief Description of the Drawings
[0023]
FIG. 1 is a perspective view illustrating the overall shape of a biomass solid fuel
boiler according to an embodiment of the present invention;
FIGs. 2 and 3 are perspective views illustrating a combustion device of a biomass
solid fuel boiler according to an embodiment of the present invention;
FIG. 4 is a perspective view illustrating a screw of a combustion device of a biomass
solid fuel boiler according to an embodiment of the present invention;
FIG. 5 illustrates a schematic operating condition of a biomass solid fuel boiler
according to an embodiment of the present invention;
FIG. 6 illustrates fluid circulation inside a screw of a biomass solid fuel boiler
according to another embodiment of the present invention;
FIG. 7 illustrates fluid circulation operation in a screw of a biomass solid fuel
boiler according to another embodiment of the present invention; and
FIG. 8 illustrates a schematic operating condition of a biomass solid fuel boiler
according to another embodiment of the present invention.
Mode for Carrying Out the Invention
[0024] Hereinafter, the present invention will be described in detail with reference to
the accompanying drawings.
[0025] FIG. 1 is a perspective view illustrating the overall shape of a burner for a biomass
solid fuel boiler according to an embodiment of the present invention.
[0026] As shown in FIG. 1, a boiler body 12 is provided as a means for heating water, which
flows through internal piping, using combustion heat obtained by burning biomass solid
fuel; a combustion device 11 is installed below the boiler body 12 as a means for
burning solid fuel; and a fuel supplier 10 is installed in front of the boiler body
12 and the combustion device 11 as a means for supplying solid fuel.
[0027] The fuel supplier 10 may be any means capable of supplying biomass fuel, such as
wood pellets, in a predetermined size condition continuously or periodically in a
controlled manner (a spring screw is commonly used), detailed description thereof
being omitted herein. The boiler body 12 is adapted to heat water inside the piping
through heat exchange with combustion heat in a conventional manner, detailed description
thereof being omitted herein.
[0028] Reference numeral 20 refers to a fuel supply tube, which is connected to a solid
fuel feeder (not shown) in front of the combustion device 11, so that solid fuel is
fed into the inner front area of the combustion device 11.
[0029] FIGs. 2 and 3 are perspective and sectional views of a combustion device of a biomass
solid fuel boiler according to an embodiment of the present invention.
[0030] As shown in FIGs. 2 and 3, the combustion device 11 is structured to use a screw
16 of a special type, which has excellent durability against the high-temperature
condition inside the combustion chamber 15, to both feed solid fuel and efficiently
process sludge and ash generated during combustion.
[0031] To this end, a combustion chamber 15 is provided as an elongated housing installed
along and in parallel with the lower portion of the boiler body 12, and a screw 16
is installed in parallel inside the combustion chamber 15 to substantially feed solid
fuel and discharge sludge and ash.
[0032] A solid fuel supply hole 13 is formed on the front portion of the combustion chamber
15 so that solid fuel can be introduced through it, and a sludge/ash discharge hole
14 is formed on the rear portion so that sludge and ash, which are generated after
combustion, are naturally discharged and processed by the operation of the screw 16.
[0033] Specifically, as shown in FIG. 4, the screw 16 consists of a hollow pipe, inside
which water circulates. The overall shape of the screw 16 is as follows: it has straight
portions 16a on both ends, and is wound in the shape of a spring 16b so as to push
solid fuel or sludge and ash towards one side.
[0034] Such construction of the screw 16, inside which water flows, enables the screw to
endure any high temperature occurring during combustion, meaning that it can fulfill
the role of feeding solid fuel and discharging sludge and ash without being deformed
or burnt down by heat.
[0035] The screw 16 is supported on the front and rear wall surfaces of the combustion chamber
15 via bearings, for example, using the straight portions on both ends, respectively,
so that the screw 16 rotates, as a driver 17 is actuated, and pushes solid fuel, sludge,
and ash towards one side.
[0036] The driver 17 includes a motor 21, a belt 22, and pulleys 23. The motor 21 is installed
on one side of a frame 24. The pulleys 23 are installed on a shaft of the motor 21
and on a straight portion of the screw 16, which extends to the outside through the
front portion of the combustion chamber 15, respectively. The belt 22 is installed
to connect between the two pulleys 23.
[0037] As a result, actuation of the motor 21 is transmitted via the pulleys 23 and the
belt 22 to the screw 16, which then rotates around a center axis defined by the straight
portions on both ends.
[0038] Those skilled in the art can understand that, besides the pulley/belt transmission
type, the driver 17 can adopt any other transmission type, such as chain transmission,
gear transmission, motor direct-connection transmission, etc.
[0039] As the water circulating inside the screw 16, water inside the boiler water tube
may be used.
[0040] For example, the front and rear straight portions of the screw 16 are provided with
valves 25, respectively, and are connected to piping 26 (e.g. hose) extending from
the boiler water tube through a coupler (not shown), so that water forcibly circulated
by a boiler-side circulation pump (not shown) can also circulate inside the screw
16.
[0041] The screw 16 can be arranged in various numbers and configurations depending on the
boiler capacity.
[0042] For example, in the case of a small-sized boiler (e.g. domestic boiler), a single
row of small screw may be arranged and used. In the case of a large-sized boiler (e.g.
industrial boiler), a large screw or multiple rows of a plurality of screws may be
arranged in parallel and used.
[0043] That is, boilers of various capacities can be obtained by properly setting the screw
size, the number of screws, the capacity of the blowing device (described later),
etc.
[0044] The combustion device 11 is provided with a blowing device 19 to help efficient complete
combustion of solid fuel.
[0045] The blowing device 19 includes a blowing fan, etc., and is installed in a predetermined
position below the combustion chamber 15, preferably on an introduction portion into
which solid fuel is introduced, to supply an adequate amount of wind necessary for
combustion into the combustion chamber 15, thereby guaranteeing more efficient solid
fuel combustion.
[0046] An igniter 18 is installed in a lateral area of the combustion chamber 15, e.g. next
to the introduction portion into which solid fuel is introduced, to enable initial
ignition of solid fuel during boiler operation.
[0047] The igniter 18 may be an ignition means used for a conventional solid fuel boiler
(electric ignition rod, electric heat wind ignition, etc.).
[0048] The operating condition of the biomass solid fuel boiler, which has the above-mentioned
construction, will now be described.
[0049] FIG. 5 illustrates a schematic operating condition of the biomass solid fuel boiler
according to an embodiment of the present invention.
[0050] As shown in FIG. 5, in order to activate the boiler, biomass solid fuel (e.g. wood
pellets) is introduced into the combustion chamber 15 of the combustion device 11
from the fuel supply tube 20 of the fuel supplier 10 through the solid fuel supply
hole 13 of the combustion chamber 15. The following ignition by the igniter 18 starts
combustion of the solid fuel, and following injection of air by the blowing device
19 results in the main phase of combustion of the solid fuel.
[0051] The heat exchange action of combustion heat, which is generated by intense combustion
of the solid fuel, heats water flowing through the boiler's internal piping and thus
provides hot water and steam as needed.
[0052] A suitable amount of solid fuel is continuously or periodically supplied into the
combustion chamber 15 of the combustion device 11 (the amount of supplied fuel can
be controlled using a fuel introduction screw), and the concurrent slow rotation of
the screw 16, which is driven by the driver 17, feeds the solid fuel to the combustion
area (area into which air is injected by the blower) to be burnt therein.
[0053] Water flows inside the screw 16, and the cooling action of water flowing inside the
screw 16 guarantees that the screw 16 can endure the high-temperature environment
inside the combustion chamber 15 without being deformed. When the water has passed
through the hollow pipe and then the combustion area, the water, in a high-temperature
condition, is introduced into a water tube inside the boiler, in the case of a hot-water
boiler. In the case of a steam boiler, the water is transferred to a condensation
water tank and fed into the boiler at a high temperature to be recycled. This prevents
the minimum heat loss that would otherwise occur due to the cooling action of the
screw inside the combustion chamber.
[0054] In addition, sludge or ash, which is generated by combustion of the solid fuel, is
repeatedly pushed back by rotation of the screw 16, and is eventually discharged to
the outside through the sludge/ash discharge hole 14, which is on the end of the combustion
chamber 15, to be processed.
[0055] That is, the rotation action of the screw 16 simultaneously feeds solid fuel and
discharges sludge and ash.
[0056] As such, the present invention employs a screw, which has a special shape and a cooling
type, and substantially improves problems of conventional solid fuel boiler burner
structures, i.e. excessive manufacturing cost, bulky combustion furnace, difficulty
in processing sludge and ash, etc.
[0057] Furthermore, use of the screw provided by the present invention makes it possible
to manufacture a boiler capable of properly using various types of fuel, which has
a predetermined particle size or less, including not only wood pellets, which are
being spotlighted as biomass energy, but also wood chips, farm byproducts, livestock
excretion pellets, etc.
[0058] In addition, adjustment of the size and number (e.g. parallel arrangement) of the
type of screw provided by the present invention makes it possible to manufacture a
remarkable solid fuel boiler burner, which is applicable not only to a domestic small-sized
boiler, but also to an industrial large-sized boiler or a cogeneration plant.
[0059] Other embodiments of the present invention will now be described in detail with reference
to the accompanying drawings.
[0060] FIG. 6 illustrates fluid circulation inside a screw of a biomass solid fuel boiler
according to another embodiment of the present invention, FIG. 7 illustrates fluid
circulation operation in a screw of a biomass solid fuel boiler according to another
embodiment of the present invention, and FIG. 8 illustrates a schematic operating
condition of a biomass solid fuel boiler according to another embodiment of the present
invention.
[0061] The fluid circulating inside the screw 16 is not used as water inside the boiler
water tube, unlike the above-described embodiment of the present invention. That is,
according to another embodiment of the present invention, it is preferable to use
a separate gas or liquid refrigerant, for example, which is introduced from the outside.
[0062] According to the above-described embodiment of the present invention, gas, liquid,
or water in the boiler piping flows inside the screw 16 as a fluid (refrigerant),
so that the cooling action of the fluid flowing inside the screw 16 enables the screw
16 to endure the high-temperature environment inside the combustion chamber 15 without
being deformed.
[0063] The above-mentioned construction, as has been explained, directly introduces water,
which exists in the boiler piping, into the hollow pipe-shaped screw 16, to seek a
cooling effect. However, the water existing in the boiler piping is not a low-temperature
fluid, and the cooling effect is insufficient when high-temperature water is reintroduced
into the screw 16 with no separate cooling means.
[0064] Therefore, the present invention does not use the water, which exists inside the
boiler, for the hollow pipe-shaped screw 16, but injects a separate fluid (e.g. gas
or liquid), which acts as a refrigerant, from the outside to lessen the high temperature
inside the combustion chamber and enable the screw to fulfill its role.
[0065] Thus, as shown in FIG. 6, the present invention may include, in order for a separate
fluid to circulate, fluid circulation piping 28, a circulation fan or a compressor
30, a fluid injection/discharge hole 31, an injection/discharge valve 32, and a cooler
33.
[0066] The present invention, as shown in FIGs. 6 and 7, includes a fluid injection/discharge
hole 31 for injecting a fluid into the fluid circulation piping 28 from outside the
combustion chamber or discharging the fluid from it. Thus, a fluid circulating inside
the screw 16 is injected into a separate fluid injection/discharge hole 31, and, when
the lifetime of the fluid is over or when it needs to be replaced, the fluid is discharged
through the fluid injection/discharge hole 31, thereby guaranteeing that it fulfills
the role of lowering the high temperature.
[0067] The fluid injection/discharge hole 31 is typically opened/closed by the injection/discharge
valve 32, as shown in FIGs. 6 and 7, to adjust the injection/discharge of the fluid.
[0068] The fluid circulation piping 28 is, as shown in FIG. 7, connected to both ends of
the screw 16 so that the fluid is circulated to the outside of the boiler's combustion
chamber, and the circulated fluid is cooled outside the boiler.
[0069] The fluid circulation piping 28 includes a circulation fan or a compressor 30, which
is adapted to push the fluid into the hollow pipe-shaped screw 16, to introduce the
fluid into the hollow pipe-shaped screw inside the combustion chamber.
[0070] The high-temperature fluid, which is circulated from the screw 16 through the fluid
circulation piping 28, is cooled down by a cooler 33, which is adapted to cool the
fluid outside the combustion chamber, and is re-circulated into the screw 16. This
improves durability of the screw 16 while it is enabled to operate in the high-temperature
combustion chamber.
[0071] The circulation fan or compressor 30, as shown in FIGs. 6 and 7, is adapted to push
the fluid into the hollow pipe-shaped screw 16, and is installed on the fluid circulation
piping 28.
[0072] Typically, the fluid circulating inside the hollow portion of the screw 16 may be
gas functioning as refrigerant, or a liquid-state refrigerant. When the circulating
fluid is gas, the circulation fan or compressor 30 may consist of a blowing fan or
a compressor, for example; and, when the circulating fluid is liquid (e.g. refrigerant),
it may consist of a compressor or a screw fan, for example.
[0073] The cooler 33, as shown in FIG. 8, exists outside the combustion chamber of the boiler
to cool down the fluid, the temperature of which has increased in the screw 16 of
the combustion chamber, and re-circulate the fluid to the screw 16. That is, the high-temperature
fluid, which has passed through the screw 16, is cooled down outside the combustion
chamber to lower the temperature of the fluid, which is to circulate to the combustion
chamber, and improve durability inside the high-temperature combustion chamber.
[0074] In this case, when the fluid circulating through the screw 16 and the fluid circulation
piping 28 is water existing in the piping of the boiler, no separate cooler can be
installed on the piping of the boiler. Therefore, a cooler 33 is installed, while
the fluid circulation piping 28 is separately circulated outside the boiler, to lower
the temperature of the fluid and fulfill its function.
[0075] The present invention has been illustrated and described with regard to specific
preferred embodiments. However, the present invention is not limited to the above-described
embodiments, and those skilled in the technical field of the present invention is
capable of any variation, modification, or implementation without departing from the
principles of technical ideas of the present invention disclosed in the accompanying
claims.
1. A biomass solid fuel boiler comprising:
a fuel supplier (10) adapted to supply solid fuel;
a combustion device (11) adapted to burn the solid fuel; and
a boiler body (12) adapted to heat water using combustion heat, wherein
the combustion device (11) comprises:
a combustion chamber (15) having a solid fuel supply hole (13) on a front side and
a sludge/ash discharge hole (14) on a rear side, the solid fuel being burnt in the
combustion chamber (15);
a screw (16) arranged along and in parallel with the interior of the combustion chamber
(15) and installed so as to rotate, the screw (16) comprising a hollow pipe, inside
which water circulates so that the screw (16) can endure high temperature inside the
combustion chamber, the screw (16) being adapted to both feed the solid fuel and discharge
sludge and ash through a rotating operation;
a driver (17) installed on a front portion of the combustion chamber (15) to rotate
the screw (16); and
an igniter (18) installed on a lateral portion of the combustion chamber (15) to ignite
the solid fuel.
2. The biomass solid fuel boiler as claimed in claim 1, further comprising a blowing
device (19) installed below the combustion chamber (15) to inject air necessary for
combustion into the combustion chamber (15).
3. The biomass solid fuel boiler as claimed in claim 1 or 2, wherein the screw (16) is
wound in the shape of a spring having straight portions on both ends adapted to act
as fulcrums during rotation.
4. The biomass solid fuel boiler as claimed in claim 1 or 2, wherein the screw (16) is
connected to a boiler water tube to receive water in the boiler water tube forcibly
circulated by a circulation pump.
5. The biomass solid fuel boiler as claimed in claim 1 or 2, wherein the screw (16) is
adapted so that its size can be adjusted based on boiler capacity, and a plurality
of screws (16) can be arranged in parallel and used.
6. A biomass solid fuel boiler comprising:
a fuel supplier (10) adapted to supply solid fuel;
a combustion device (11) adapted to burn the solid fuel; and
a boiler body (12) adapted to heat water using combustion heat, wherein
the combustion device (11) comprises:
a combustion chamber (15) having a solid fuel supply hole (13) on a front side and
a sludge/ash discharge hole (14) on a rear side, the solid fuel being burnt in the
combustion chamber (15);
a screw (16) arranged along and in parallel with the interior of the combustion chamber
(15) and installed so as to rotate, the screw (16) comprising a hollow pipe, inside
which fluid circulates to lower temperature inside the combustion chamber so that
the screw (16) can endure high temperature, the screw (16) being adapted to both feed
the solid fuel and discharge sludge and ash through a rotating operation;
a driver (17) installed on a front portion of the combustion chamber (15) to rotate
the screw (16); and
an igniter (18) installed on a lateral portion of the combustion chamber (15) to ignite
the solid fuel, and
the boiler comprises a circulation fan or a compressor (30) adapted to push fluid
into the hollow pipe-shaped screw (16) so that the fluid is introduced into the hollow
pipe-shaped screw inside the combustion chamber.
7. The biomass solid fuel boiler as claimed in claim 6, further comprising a circulation
fan or a compressor (30) adapted to push fluid into the hollow pipe-shaped screw (16)
so that the fluid is introduced into the hollow pipe-shaped screw inside the combustion
chamber.
8. The biomass solid fuel boiler as claimed in claim 7, further comprising:
fluid circulation piping (28) connected to both ends of the screw (16) so that the
fluid circulates outside the combustion chamber; and
a cooler (33) adapted to cool the high-temperature fluid, which has passed through
the screw (16), outside the combustion chamber, so that durability inside the high-temperature
combustion chamber is improved by lowering the temperature of the fluid circulated
to the combustion chamber.
9. The biomass solid fuel boiler as claimed in claim 8, further comprising a fluid injection/discharge
hole (31) adapted to enable injection of a fluid into the fluid circulation piping
(28) from outside the combustion chamber or discharge of the fluid.
10. The biomass solid fuel boiler as claimed in any one of claims 7-9, wherein the fluid
circulating inside the hollow portion of the screw (16) comprises gas.
11. The biomass solid fuel boiler as claimed in any one of claims 7-9, wherein the fluid
circulating inside the hollow portion of the screw (16) comprises a liquid-state refrigerant.
12. The biomass solid fuel boiler as claimed in claim 11, wherein the circulation fan
or compressor adapted to push the fluid into the screw (16) is a compressor or a screw
fan adapted to circulate liquid.