U.S. patent application number 10/332101 was filed with the patent office on 2006-02-23 for equipment and method for enhancing combustion and heat transfer in a boiler by using sound.
Invention is credited to Heikki Ahonen, Martti Kinnunen, Arttu Salmela.
Application Number | 20060040226 10/332101 |
Document ID | / |
Family ID | 8558736 |
Filed Date | 2006-02-23 |
United States Patent
Application |
20060040226 |
Kind Code |
A1 |
Ahonen; Heikki ; et
al. |
February 23, 2006 |
Equipment and method for enhancing combustion and heat transfer in
a boiler by using sound
Abstract
The invention concerns equipment and a method for enhancing the
combustion event and heat transfer in a heating boiler. According
to the invention, the space above the major combustion zone in the
combustion space of the heating boiler is equipped with sound
sources, which are used to generate an acoustic field to enhance
the combustion event and to achieve more complete combustion.
Inventors: |
Ahonen; Heikki; (Ritvala,
FI) ; Salmela; Arttu; (Lahti, FI) ; Kinnunen;
Martti; (Lahti, FI) |
Correspondence
Address: |
SMITH-HILL AND BEDELL, P.C.
16100 NW CORNELL ROAD, SUITE 220
BEAVERTON
OR
97006
US
|
Family ID: |
8558736 |
Appl. No.: |
10/332101 |
Filed: |
July 6, 2001 |
PCT Filed: |
July 6, 2001 |
PCT NO: |
PCT/FI01/00647 |
371 Date: |
January 2, 2004 |
Current U.S.
Class: |
431/121 |
Current CPC
Class: |
F23C 99/003
20130101 |
Class at
Publication: |
431/121 |
International
Class: |
F23D 11/38 20060101
F23D011/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 6, 2000 |
FI |
20001616 |
Claims
1. Equipment for enhancing the combustion event and heat transfer
in a heating boiler, said equipment comprising sound sources (S) in
a space above the major combustion zone in a combustion space (11)
of the heating boiler (10), which sound sources (S) generate an
acoustic field in order to enhance the combustion event and a more
complete combustion, characterised in that the sound sources (S)
are placed in such a way that the acoustic pressure patterns
generated by the sound sources (S) meet at angles of 20-90.degree.
sideways and/or vertically and that the sound sources (S) are
fitted into the heating boiler (10) in such a way that the
generated acoustic field is rotating.
2. Equipment as defined in claim 1, characterised in that the
acoustic field generated by the sound sources (S) is
continuous.
3. Equipment as defined in claim 1 or 2, characterised in that the
acoustic pressure level generated by the sound sources (S) is no
less than 130 dB at the place where the acoustic pressure patterns
meet.
4. Equipment as defined in any one of claims 1-3, characterised in
that the frequency of the sound generated by the sound sources (S)
is in a range of 20-1000 Hz.
5. Equipment as defined in any one of claims 1-4, characterised in
that the secondary and/or tertiary air of the heating boiler (10)
or a part of that air has been supplied into the boiler through the
sound sources (S).
6. Equipment as defined in any one of claims 1-5, characterised in
that the sound sources (S) are fitted into the heating boiler (10)
in such a way that the generated rotating acoustic field rotates in
the direction of the positive acoustic pressure.
7. Equipment as defined in any one of claims 1-6, characterised in
that the sound sources (S) are fitted into the heating boiler (10)
in such a way that the sound frequency increases towards the top
part of the heating boiler (10).
8. Equipment as defined in any one of claims 1-7, characterised in
that the sound sources (S) are acoustic horns.
9. Equipment as defined in any one of claims 1-7, characterised in
that the sound sources (S) are pneumatically operated continuous
sirens.
10. Equipment as defined in any one of claims 1-7, characterised in
that the sound sources (S) are sound sources (SP) based on a pulse
burner.
11. Equipment as defined in claim 10, characterised in that the
fuel of the pulse burner (SP) functioning as sound source
essentially includes a gaseous inflammable matter and an
oxidiser.
12. Equipment as defined in claim 10 or 11, characterised in that
the pulse burner (SP) functioning as sound source includes an
antechamber (SP.sub.1), into which air under pressure is arranged
to be supplied, a set of valves (V) opened and closed by pressure
and separating the space between the antechamber (SP.sub.1) and the
combustion chamber (SP.sub.2), and into which combustion chamber
(SP.sub.2) supply of fuel is arranged, and a sound horn
(SP.sub.3).
13. Equipment as defined in claim 12, characterised in that a
continuous supply of air under pressure is arranged into the
antechamber (SP.sub.1) of the pulse burner (SP) through an assembly
(L.sub.1).
14. Equipment as defined in claim 12 or 13, characterised in that
the supply of fuel into the combustion chamber (SP.sub.2) of the
pulse burner (SP) is arranged through an assembly (L.sub.2).
15. Equipment as defined in any one of claims 12-14, characterised
in that the pressure of the combustion chamber (SP.sub.2) of the
pulse burner (SP) discharges into the combustion space (11) of the
heating boiler (10).
16. Method for enhancing the combustion event and heat transfer in
a heating boiler, in which method an acoustic field is generated
with sound sources (S) in a space above the major combustion zone
in a combustion space (11) of the heating boiler (10),
characterised in that a rotating acoustic field is generated by
sound sources (S), which are located on various sides and/or at
different elevations of the heating boiler (10) in such a way that
the acoustic pressure patterns generated by the sound sources (S)
meet at angles 20-90.degree. sideways and/or vertically.
17. Method as defined in claim 16, characterised in that sound
sources (SP) based on a pulse burner are used as sound sources (S).
Description
[0001] The invention concerns equipment and a method for enhancing
the combustion event and heat transfer in a heating boiler.
[0002] The invention relates to combustion taking place in power
plants, heating furnaces, heating boilers and other such combustion
spaces and to enhancement of such combustion. In the following, the
name of heating boiler will be used for these application objects
of the invention.
[0003] Combustion is a complex event, which depends on several
different factors, such as the particle size of the fuel, the
combustion temperature and the structure of the heating boiler. The
fuel used in the combustion event becomes oxidized, whereby heat
will result. At typical combustion temperatures, combustion of hot
solid matter depends on the speed at which oxygen is diffused into
the surface of the matter. As the combustion proceeds, the particle
size and particle mass are reduced. When burning carbon, the
combustion results in carbon monoxide, which in the continued
combustion will become carbon dioxide.
[0004] It is a known method to enhance the combustion event by
causing turbulence to occur in the combustion space to enhance
movement of the matter and heat transfer in the combustion.
However, in known solutions problems still occur in the completion
of combustion taking place in power plants, heating furnaces and
heating boilers and other such installations. It is difficult to
make turbulence generators, such as agitators, to reach high
temperatures, which are typically in a range of 600-1000.degree. C.
In particular, problems occur in the combustion of non-volatile
carbon particles.
[0005] Enhancing of combustion is also associated with cleaning of
the heat transfer surfaces of the heating boiler to remove ash
particles and unburnt carbon particles from them. Acoustic cleaning
is a known cleaning method, wherein sound sources are placed in the
heat transfer parts of the heating boiler and sound is produced
periodically at intervals of about 2-15 minutes for a few seconds
each time. Acoustic cleaning equipment is known e.g. from
publications WO-82/01328 and WO-82/03803.
[0006] The purpose of the invention is to bring about equipment and
a method for enhancing the combustion event in such a way that the
combustion is more complete and emissions are reduced.
[0007] Another purpose of the invention is to bring about equipment
of a new kind, wherein a sound source based on a pulse burner is
used as the sound source.
[0008] The equipment according to the invention for enhancing the
combustion event and heat transfer in a heating boiler is mainly
characterised in that the space above the major combustion zone in
the combustion space of the heating boiler is equipped with sound
sources to generate an acoustic field in order to enhance the
combustion event and to achieve a more complete combustion, and
that the sound sources are placed in such a way that the acoustic
pressure patterns generated by the sound sources meet at angles of
20-90.degree. sideways and/or vertically.
[0009] The method according to the invention for its part is
characterised in that in a space above the major combustion zone in
the combustion space of the heating boiler a rotating acoustic
field is generated by sound sources, which are located on various
sides and/or at different elevations of the heating boiler.
[0010] In the arrangement according to the invention, the
combustion event is enhanced in such a way in a heating boiler that
an acoustic field is applied to a space above the actual major
combustion zone. Matter volatilising at this location has already
burnt out for the most part, but some carbon still remains in the
form of small particles, which have not yet burnt The acoustic
field is preferably continuous and it is generated by suitable
sound sources, one or more, which are placed in the combustion
space of the heating boiler. The sound source is preferably a sound
source based on a pulse burner. By the arrangement according to the
invention, the combustion event is enhanced in such a way that more
heat is obtained from the fuel used and less combustion residue
will result. At the same time, a cleaner combustion is also
achieved, which means that harmful emissions are reduced.
[0011] By using the sound source according to the invention, which
is based on a pulse burner, that problem is solved, which is
associated with pneumatically operated sound sources in that due to
the higher pressure existing inside the combustion space dust or
other impurities will drift from the combustion space into the
sound source. No such problem occurs in the sound source based on a
pulse burner.
[0012] In the following, the invention will be described with
reference to the figures shown in the appended drawing, but the
intention is not to limit the invention only to the embodiments
shown in the figures.
[0013] FIG. 1 shows a heating boiler and the location therein of
the equipment according to the invention.
[0014] FIG. 2 shows an example of the acoustic field according to
the invention.
[0015] FIG. 3A shows the sound source according to the
invention.
[0016] FIG. 3B shows a valve in the sound source according to the
invention.
[0017] FIG. 3C is a cross-sectional view of the sound source
according to the invention.
[0018] FIG. 3D is another cross-sectional view of the sound source
according to the invention.
[0019] FIG. 1 is a schematic view of a heating boiler, wherein the
method according to the invention for enhancing the combustion
event is applied. Sound sources S are located in combustion space
11 of heating boiler 10. The place of location of sound sources S
is a space above the major combustion zone before cooling of the
combustion gases. The sound sources used are preferably such sound
horns known in acoustic cleaning, which produce a sound volume of
130-170 dB at a frequency of 20-1000 Hz. The sound source used may
also be pneumatically operated continuous sirens or the sound
source according to the invention shown in FIGS. 3A-D, which is
based on a pulse burner. Due to the good penetration depth, the
acoustic frequency range chosen is preferably used explicitly in
order to enhance the combustion event. The power and frequency of
the sound sources S may be controlled within the chosen range
according to the type and size of boiler and the locations of sound
sources S. The sound volume is chosen so that the acoustic pressure
level generated by sound sources S is preferably no less than 130
dB at the place where acoustic pressure patterns meet, where the
temperature in the combustion space 11 is typically over
800.degree. C. Sound sources S are placed in combustion space 11 in
such a way that the acoustic pressure patterns which they generate
will meet at angles of 20-90.degree. C. sideways and/or
vertically.
[0020] In an advantageous embodiment of the invention, sound
sources S are placed at different elevations in the heating boiler
10, and when moving upwards in the combustion space 11 the
frequency of the sound source S is increased as the diameter and
mass of solid particles diminish further ahead in combustion space
11. Hereby the desired effect enhancing the combustion event will
remain at an optimum.
[0021] In another advantageous embodiment of the invention, sound
sources S are placed in such a way in heating boiler 10 that the
resulting acoustic field is rotating. FIG. 2 illustrates such a
rotating acoustic field, which is generated by locating in the
combustion space 11 of a heating boiler, which as regards its
diameter is of a rectangular shape, four sound sources S, which are
used to generate the acoustic pressure direction pattern shown in
FIG. 2. A rotating acoustic field of a corresponding kind can also
be generated in a heating boiler of some other shape. The number
and locations of sound sources S may be different from those shown
in this example, when generating a rotating acoustic field.
[0022] In an advantageous embodiment of the invention a part of the
secondary and/or tertiary air needed in the combustion event is
supplied through the sound sources S placed in heating boiler 10.
This supplied air at the same time functions as cooling air for
sound sources S.
[0023] FIG. 3A shows a sound source SP according to the invention,
which is based on a pulse burner. FIG. 3B shows an example of the
structure of a valve V of sound source SP, FIG. 3C is a
cross-sectional view of sound source SP along line A-A' indicated
in FIG. 3A and FIG. 3D is a cross-sectional view of sound source SP
along line B-B' indicated in FIG. 3A.
[0024] The sound source used is a pulse burner, which preferably
operates with the combustion reaction between a gaseous or gasified
fuel and air and functions on the "pulse jet" principle known as
such. In such an embodiment the sound source SP includes an
antechamber SP.sub.1, into which air under pressure is supplied
through assembly L.sub.1, a combustion chamber SP.sub.2, into which
a gaseous inflammable matter is supplied through assembly L.sub.2,
and a sound horn SP.sub.3. Between antechamber SP.sub.1 and
combustion chamber SP.sub.2 there is a valve/set of valves V, whose
structure is shown by the cross-sectional view in FIG. 3B. In
addition, sound source SP includes one or more igniters I located
in combustion chamber SP.sub.2. Combustion chamber SP.sub.2 is
surrounded by cooling devices C including cooling fins c.sub.1, . .
. , c.sub.n. Into cooling devices C a cooling medium, preferably
cooling air or water, is conducted by way of assembly L.sub.3.
[0025] After the combustion event, the pressure of combustion
chamber SP.sub.2 is released into the space to be cleaned, that is,
into combustion space 11.
[0026] The igniting device/devices I used are preferably spark
plugs or a hot shoe functioning as a constantly glowing igniting
component
[0027] The pulse burner operating as sound source SP preferably
uses hydrocarbon gas and air in starting. In addition, in one
embodiment of the invention a gasified gas is used, which is taken
from that part of the combustion space, where no secondary or
tertiary air has yet been introduced.
[0028] The sound source according to the invention forms a
continuous acoustic pressure pulse, with which a continuous quick
pulse-like acoustic pressure can be driven into the combustion
space of the boiler.
[0029] The invention may be applied in all types of power plants,
heating furnaces, heating boilers and other such installations. The
sound sources used are sound horns known in acoustic cleaning, but
also sound sources of other kinds may be used.
[0030] The following is a presentation of the claims, but the
invention is not intended to be limited only to the different
embodiments presented in the claims.
* * * * *