U.S. patent application number 14/227165 was filed with the patent office on 2014-10-02 for method and apparatus for burning hydrocarbons and other liquids and gases.
This patent application is currently assigned to OILON OY. The applicant listed for this patent is OILON OY. Invention is credited to Reijo LYLYKANGAS, Eero PEKKOLA, Tero TULOKAS.
Application Number | 20140295358 14/227165 |
Document ID | / |
Family ID | 50478692 |
Filed Date | 2014-10-02 |
United States Patent
Application |
20140295358 |
Kind Code |
A1 |
LYLYKANGAS; Reijo ; et
al. |
October 2, 2014 |
METHOD AND APPARATUS FOR BURNING HYDROCARBONS AND OTHER LIQUIDS AND
GASES
Abstract
A method and apparatus for burning hydrocarbons or other
combustible liquids and gases, the apparatus (APP) has been
provided with at least one inlet for a liquid and/or gaseous fuel
(FUE) and air (AIR) and at least one outlet (EXHG) for gases for
removing the gases (EXHG) generated in the apparatus (APP), at
least one measurement and adjustment unit (C) for adjusting the
amount of fuel (FUE) and air (AIR), at least one pre-combustion
zone (Cz11, Cz12, Tz1) for the partial combustion of gases, and at
least one post-combustion zone (Tz2, Cz21, Cz22) for the combustion
of gases generated in pre-combustion, for the reduction of NOx's
produced in pre-combustion, and/or for the oxidation of hydrocarbon
and carbon monoxide emissions.
Inventors: |
LYLYKANGAS; Reijo;
(Vihtavuori, FI) ; PEKKOLA; Eero; (Lahti, FI)
; TULOKAS; Tero; (Lahti, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OILON OY |
Lahti |
|
FI |
|
|
Assignee: |
OILON OY
Lahti
FI
|
Family ID: |
50478692 |
Appl. No.: |
14/227165 |
Filed: |
March 27, 2014 |
Current U.S.
Class: |
431/7 ; 110/188;
110/208; 110/210; 110/234; 110/345; 29/428; 431/170 |
Current CPC
Class: |
F23N 2900/05003
20130101; F23C 13/06 20130101; Y10T 29/49826 20150115; F23C 13/04
20130101; F23N 5/003 20130101; F23C 1/08 20130101; F23C 6/04
20130101; F23N 2225/30 20200101; F23J 15/02 20130101; F23N 3/002
20130101 |
Class at
Publication: |
431/7 ; 110/345;
110/208; 110/210; 431/170; 110/188; 110/234; 29/428 |
International
Class: |
F23C 13/04 20060101
F23C013/04; F23N 3/00 20060101 F23N003/00; F23C 13/06 20060101
F23C013/06; F23J 15/02 20060101 F23J015/02; F23C 6/04 20060101
F23C006/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2013 |
FI |
PCT/FI2013/050340 |
Claims
1. A method for burning hydrocarbons or other combustible liquids
and gases in an apparatus (APP), which is provided with at least
one inlet for a liquid or gaseous fuel (FUE) and for air (AIR) and
at least one outlet for gases for removing gases (EXHG) generated
in said apparatus (APP), as well as with at least one measurement
and adjustment unit (C) for adjusting said amount of fuel (FUE) and
air (AIR), wherein said method comprises at least the following
operations: the partial pre-combustion of fuel (FUE) in at least
one pre-combustion zone (Cz11, Cz12, Tz1), such that the supplied
fuel is burned only partially, the post-combustion of
pre-combustion-generated gases (GAS1) in at least one
post-combustion zone (Cz21, Cz22, Tz2) for burning the
pre-combustion-generated gases, for the reduction of
pre-combustion-generated NOx's, and/or for the oxidation of
hydrocarbon and carbon monoxide emissions.
2. A method as set forth in claim 1, wherein the pre-combustion
and/or the post-combustion are/is carried out in at least one
catalytic zone (Cz11, Cz12, Cz21, Cz22).
3. A method as set forth in claim 1, wherein the pre-combustion
and/or the post-combustion are/is carried out in at least one
thermal zone (Tz1, Tz2).
4. A method as set forth in claim 1, wherein the pre-combustion is
carried out in at least one thermal pre-combustion zone (Tz1) and
the post-combustion is carried out in at least one catalytic
post-combustion zone (Cz21, Cz22).
5. A method as set forth in claim 1, wherein the pre-combustion is
carried out in at least one catalytic pre-combustion zone (Cz11,
Cz12) and the post-combustion is carried out in at least one
catalytic post-combustion zone (Cz21, Cz22).
6. A method as set forth in claim 1, wherein the supply of fuel
(FUE) and the supply of air (AIR) into the apparatus (APP) is
arranged to occur within the Lambda range of 0,5-1,5.
7. A method as set forth in claim 6, wherein Lambda is >1,0
(lean mixture).
8. A method as set forth in claim 6, wherein Lambda is <1,0
(rich mixture).
9. A method as set forth in claim 6, characterized in Lambda is
0,99 to 1,01 (stoichiometric air-fuel ratio or near it).
10. A method as set forth in claim 1, comprising at least one of
catalyst zones (Cz11, Cz12, Cz21, Cz22) having three-way
catalytic.
11. A method as set forth in claim 1, wherein pre-combustion is
arranged in lowered temperature.
12. A method as set forth in claim 1, wherein the supply of fuel
(FUE) and the supply of air (AIR) into apparatus (APP) is arranged
by monitoring NOx emissions by using a NOx sensor.
13. An apparatus (APP) for burning hydrocarbons or other
combustible liquids and gases, wherein said apparatus (APP) has
been provided with at least one inlet for a liquid and/or gaseous
fuel (FUE) and air (AIR) and at least one outlet (EXHG) for gases
for removing the gases (EXHG) generated in said apparatus (APP), as
well as at least one measurement and adjustment unit (C) for
adjusting the amount of fuel (FUE) and air (AIR), and that said
apparatus (APP) has been provided with at least one pre-combustion
zone (Cz11, Cz12, Tz1) for the partial combustion of gases, and
that said apparatus comprises at least one post-combustion zone
(Cz21, Cz22, Tz2) for the combustion of gases generated in
pre-combustion, for the reduction of NOx's produced in
pre-combustion, and/or for the oxidation of hydrocarbon and carbon
monoxide emissions.
14. An apparatus as set forth in claim 13, wherein apparatus (APP)
has been provided with at least one catalytic zone (Cz11, Cz12,
Cz21, Cz22).
15. An apparatus as set forth in claim 13, wherein apparatus (APP)
has been provided with at least one thermal zone (Tz1, Tz2).
16. An apparatus as set forth in claim 13, wherein apparatus (APP)
has been provided with at least one thermal pre-combustion zone
(Tz1) and at least one catalytic post-combustion zone (Cz21,
Cz22).
17. An apparatus as set forth in claim 13, wherein apparatus (APP)
has been provided with at least one catalytic pre-combustion zone
(Cz11, Cz12) and at least one catalytic post-combustion zone (Cz21,
Cz22).
18. An apparatus as set forth in claim 13, comprising at least one
of catalyst zones (Cz11, Cz12, Cz21, Cz22) being three-way
catalytic.
19. An apparatus as set forth in claim 13, wherein said measurement
and adjustment unit (C) has at least one Lambda sensor for
measuring the oxidation/reduction potential of a flue gas.
20. An apparatus as set forth in claim 13, wherein said measurement
and adjustment unit (C) has at least one NOx sensor for arranging
the supply of air (AIR) into said apparatus (APP) by monitoring NOx
emissions by using a NOx sensor.
21. An apparatus as set forth in claim 13, wherein said apparatus
(APP) has been provided with at least one heat exchanger (HE) for
the transfer of heat generated in pre-combustion and/or in
post-combustion.
22. An apparatus as set forth in claim 13, wherein said apparatus
(APP) is fire-tube boiler comprising at least one thermal
pre-treatment zone (Tz1) in fire-tube(s) FFL and at least one
catalytic combustion zone (Cz21, Cz22) as a post-treatment
installed in smoke-tube(s) FTU.
23. An apparatus as set forth in claim 21, wherein place of
post-treatment catalyst(s) (Cz21, Cz22) is arranged according to
the burning temperature in smoke- tube(s) FTU and optimized
operating temperature of said catalyst(s) (Cz21, Cz22).
24. A method for manufacturing an apparatus (APP) suitable for
burning hydrocarbons or other combustible liquids and gases,
wherein said apparatus (APP) provided with at least one inlet for a
liquid and/or gaseous fuel (FUE) and air (AIR) and at least one
outlet (EXHG) for gases for removing the gases (EXHG) generated in
said apparatus (APP), as well as at least one measurement and
adjustment unit (C) for adjusting the amount of fuel (FUE) and air
(AIR), and that said apparatus (APP) is provided with at least one
pre-combustion zone (Cz11, Cz12, Tz1) for the partial combustion of
gases, and that said apparatus is provided with at least one
post-combustion zone (Cz21, Cz22, Tz2) for the combustion of gases
generated in pre-combustion, for the reduction of NOx's produced in
pre-combustion, and/or for the oxidation of hydrocarbon and carbon
monoxide emissions.
25. A manufacturing method as set forth in claim 24, wherein said
apparatus (APP) is provided with at least one catalytic zone (Cz11,
Cz12, Cz21, Cz22).
26. A manufacturing method as set forth in claim 24, wherein said
apparatus (APP) is provided with at least one thermal zone (Tz1,
Tz2).
27. A manufacturing method as set forth in claim 24, wherein said
apparatus (APP) is provided with at least one thermal
pre-combustion zone (Tz1) and at least one catalytic
post-combustion zone (Cz21, Cz22).
28. A manufacturing method as set forth in claim 24, wherein said
apparatus (APP) is provided with at least one catalytic
pre-combustion zone (Cz11, Cz12) and at least one catalytic
post-combustion zone (Cz21, Cz22).
29. A manufacturing method as set forth in claim 24, wherein said
apparatus (APP) is provided with at least one Lambda sensor for
measuring the oxidation/reduction potential of a flue gas and/or at
least one NOx sensor for measuring NOx emissions and adjusting the
air-fuel ratio.
30. A manufacturing method as set forth in claim 24, wherein said
apparatus (APP) is provided with at least one heat exchanger (HE)
for the transfer of heat generated in pre-combustion and/or in
post-combustion.
31. A manufacturing method as set forth in claim 24, wherein said
apparatus (APP) is a fire-tube boiler provided with at least one
thermal pre-treatment zone (Tz1) in fire-tube(s) FFL and at least
one catalytic combustion zone (Cz21, Cz22) as a post-treatment
installed in smoke-tube(s) FTU.
Description
[0001] The invention relates to a method and apparatus for burning
hydrocarbons or other combustible liquids and gases, as well as to
the manufacture and use of such an apparatus.
BACKGROUND
[0002] Thermal combustion in the production of energy always
results in nitrogen oxides (NOx), because at a high temperature
(>1000.degree. C.) the atmospheric nitrogen or organic nitrogen
contained in fuel reacts with combustion air or oxygen contained in
fuel. The higher the temperature and the longer the burn time, the
more NOx emissions are produced. Another problem is that thermal
combustion is never complete, but the flue gas is always left with
unburned hydrocarbons (VOC), or carbon monoxide (CO) as a result of
incomplete combustion. The resulting amount of these is the higher,
the lower is the temperature and the shorter is the burn time, i.e.
the emissions produced as a result of reducing (NOx) and oxidizing
(HC and CO) reactions require conflicting conditions. Authorities
have started to introduce stricter emission regulations based i.a.
on BAT (Best Available Technology) resolutions in Europe and BAC
(Best Available Control) standards in the USA.
[0003] The main topic in public debate has recently focused on
carbon dioxide (CO.sub.2) emissions because of their greenhouse
effects. What has been overlooked to some extent is that
hydrocarbon emissions are greenhouse gases an order of magnitude
more powerful than CO.sub.2. Likewise, nitrogen oxides are
greenhouse gases and causes of acid rains and, jointly with VOC
gases, are sources of tropospheric ozone, which is highly
detrimental to plants and people. For these reasons, the NOx and
VOC emission regulations are also being tightened simultaneously
with CO.sub.2 emissions. The elimination of nitrogen oxide
emissions is expensive as it calls for secondary methods which
generally impair efficiency (increase CO.sub.2 emissions) and also
increase investment and operating costs. One of the most effective
currently employed secondary NOx removal measures is the SCR
(Selective Catalytic Reduction) catalytic converter and a selective
reducer (ammonia or urea) compatible therewith. The removal of VOC
and CO emissions from flue gas is easier. All that is needed for
those is an oxidation catalyst. In addition, all above-mentioned
compounds require a temperature higher than 250.degree. C. and the
subsequent recovery of heat. The cleanup of flue gases is expensive
in terms of both investment and operating costs. An alternative
solution is to oxidize organic fuels so as not to produce the
above-mentioned emissions practically at all. This is possible with
catalytic combustion and the combination of thermal and catalytic
combustion as the gas temperature can be maintained at a
sufficiently low level the reaction time very short as compared to
thermal combustion. Another possibility is to burn gaseous or
liquid fuel thermally with a stoichiometric air-fuel ratio. The NOx
produced in thermal combustion can be reduced in a catalytic
converter subsequent to the thermal combustion.
[0004] Carbon dioxide is always produced when burning organic
compounds. One possibility of exploiting carbon dioxide generated
in burning are greenhouses, which need carbon dioxide not only for
heating energy but also both for replacing the carbon dioxide
consumed in photosynthesis and for fertilizing plants. The
double-triple excess of carbon dioxide with respect to what is
airborne (about 380 mg/Nm.sup.3) may expedite growth by as much as
40%.
[0005] Greenhouses make up a good target for reducing CO.sub.2
emissions, particularly if the energy is produced with an
emission-free biofuel. In this case, the greenhouses would function
as carbon sinks. Catalytic combustion, alone or jointly with
thermal combustion, is particularly well applicable to the
production of energy for greenhouses as plants tolerate neither
nitrogen oxides nor ethylene. With regard to these emissions as
well, the plants require about a hundred times cleaner air than
people.
[0006] The NOx's and VOC's generated in the production of energy
needed for industry, traffic and residential heating are a major
problem. Together with sunlight, they produce tropospheric ozones
harmful for plants and people. Since Feb. 1, 2012, NOx emissions
are limited by Californian BAC standards to the level of about 15
mg/Nm.sup.3 (1,4-3 MW facilities). Larger facilities are required
to have lower values of 5 mg/Nm.sup.3 for NOx and 20 mg/Nm.sup.3
for VOC and CO emissions. However, the standards vary from state to
state. These values are not reachable by thermal combustion alone.
Yet, all these limit values can be achieved with catalytic
combustion or with a new combination of catalytic and thermal
combustion without a subsequent treatment of flue gas.
DESCRIPTION OF THE INVENTION
[0007] What has been invented now is a method and apparatus for
burning hydrocarbons or other combustible gases and liquids,
whereby the combustion can be performed in a particularly effective
manner. The invention relates also to a method for the manufacture
and use of such an apparatus.
[0008] The method and apparatus of the invention are presented in
independent claims. In addition, a few preferred embodiments of the
invention are presented in dependent claims.
[0009] An apparatus APP of the invention has been provided with or
arranged to comprise at least one inlet for a liquid and/or gaseous
fuel and air and at least one outlet for gases for removing the
gases generated in the apparatus, as well as at least one
measurement and adjustment unit for adjusting the amount of fuel
and air, and that the apparatus APP has been provided with at least
one pre-combustion zone for the partial combustion of gases, and
that the apparatus comprises at least one post-combustion zone for
the combustion of gases generated in pre-combustion, for the
reduction of NOx's produced in pre-combustion, and/or for the
oxidation of hydrocarbon and carbon monoxide emissions.
[0010] According to one object of the invention, at least one of
the pre-combustion zones and/or the post-combustion zones is a
catalytic zone.
[0011] According to one object of the invention, the apparatus APP
is provided with at least one catalytic zone. According to one
object of the invention, the apparatus APP is provided with at
least one thermal zone. According to one object of the invention,
the apparatus APP is provided with at least one catalytic
pre-combustion zone and at least one thermal post-combustion zone.
According to one object of the invention, the apparatus APP is
provided with at least one catalytic pre-combustion zone and at
least one catalytic post-combustion zone, According to one object
of the invention, the apparatus APP is provided with at least one
thermal pre-combustion zone and at least one catalytic
post-combustion zone. These are beneficial in certain embodiments
of the invention and contribute to improve combustion performance.
According to one object of the invention, the apparatus APP is
provided with at least one heat exchanger HE for the transfer of
heat generated in pre-combustion and/or post-combustion. This gives
both economic and technical advantage.
[0012] The method according to the invention comprises respectively
at least the following operations: [0013] the partial
pre-combustion of fuel in at least one pre-combustion zone, such
that the supplied fuel is burned only partially, [0014] the
post-combustion of pre-combustion-generated gases in at least one
post-combustion zone for burning the pre-combustion-generated
gases, for the reduction of pre-combustion-generated NOx's, and/or
for the oxidation of hydrocarbon and carbon monoxide emissions.
[0015] The apparatus and method can be implemented in one or more
configurations. Hence, the apparatus can have its components
located in a single assembly or separated from each other by one or
more other intervening components or devices. Respectively,
operations can also be carried out in a single sequence or can be
at least partially distinguished from each other by one or more
other intervening operations. These can also be integrated for
larger entities.
[0016] The apparatus and method can be used in the combustion of
e.g. natural gas, biogas, bioethanol, propane, methanol, ethanol,
turpentine, butane, pentane, carbon monoxide, hydrogen, light fuel
oil, oil-water emulsion and/or any mixtures thereof.
[0017] According to one object of the invention, the measurement
and adjustment unit C is provided with or arranged to comprise at
least one Lambda sensor for measuring the oxidation/reduction
potential of a flue gas. The inlet of fuel FUE and air AIR into the
apparatus APP can be adapted to occur within the Lambda range of
0,5-1,5.
[0018] According to one object of the invention, the combustion
temperature is within the range of 400-800.degree. C. Thus, there
will preferably be no substantial NOx emissions.
[0019] If gases have high content of CO, catalytic zone can be
selected so that temperature is low, even 200.degree. C. or lower.
This significant adds lifetime of catalyst. Then proper temperature
can be e.g. 100.degree. C. or more lower than normally. It is thus
also in some cases advantageous to have high content of CO in
pre-treatment gas and burn it thereafter in catalytic zone.
[0020] According to one object of the invention, the monitoring of
NOx emissions is carried out by using a NOx sensor, which is
preferably useful for controlling the air-fuel ratio as well.
[0021] According to one object of the invention, the monitoring of
CO emissions is carried out by using a CO-sensor, which is
preferably useful for controlling the air-fuel ratio as well.
[0022] The apparatus according to one object of the invention
comprises either one thermal burner with a liquid or gaseous fuel
inlet and at least one catalytic converter for the catalytic
combustion of gases and for the reduction of NOx's generated in
thermal combustion and for the oxidation of hydrocarbon and carbon
monoxide emissions. Since reduction in the process of burning
combustible gases necessitates a stoichiometric air-fuel ratio, the
apparatus is therefore further provided with at least one Lambda
sensor carrying out a measurement for the oxidation/reduction
potential of a flue gas, and provided with an air/fuel ratio
adjustment system. The monitoring of NOx emissions can be carried
out by using a NOx sensor, which can also be used for controlling
the air-fuel ratio.
[0023] According to one object of the invention, at least one of
the pre-combustion zones and/or the post-combustion zones is a
catalytic zone, which has activated portions and non-activated
portions for only the partial combustion of fuel and for adjusting
the temperature of combustion.
[0024] Thermal combustion in a pre-combustion process can be
replaced by one or more catalytic converters, of which the first,
and possibly also the second catalytic converter is only partially
catalytically coated. According to one object of the invention the
catalytic converter honeycomb is provided with activated and
non-activated channels side by side. In this case, the reactions
take place in the activated channel with a "cold" unreacted gas
proceeding in the adjacent channel. This enables cooling of the
high temperature created in the activated channel, since reactions
in a catalytic converter occur much more rapidly than thermal
combustion. Hence the production of heat can be distributed over
several stages. Such a partially coated catalytic converter can be
preferably constructed from a metal foil by coating just one side
of the foil or by placing an uncoated foil to serve as every other
foil. Partial combustion can also be carried out by leaving a
larger opening in the middle of the honeycomb or a gap on the outer
periphery. The alternatives are plausible in various
combinations.
[0025] Catalytic combustion can be carried out with very lean
mixtures, which is why the boiler of the invention is able to burn
simultaneously several fuels, comprising VOC emissions. The supply
of air and fuel for the burner can be controlled with temperatures
subsequent to catalytic converters.
[0026] One aspect with burners of the above type is that such
burners can be constructed as part of a boiler, which is preferably
a tubular heat exchanger so as to enable catalytic converters to be
disposed at fixed intervals inside the pipes with water or other
liquid flowing outside the pipes. The idea here is that the
production of heat is distributed over several stages. Hence, the
gas has time to cool prior to the next catalytic converter with
heat transferring to liquid. Thereby, the catalytic converter can
be kept from overheating and the gas can be kept hot over a longer
distance. The catalytic converter's channels are sufficiently small
to eliminate the possibility of thermal combustion. The combustion
occurs in the form of intense oxidation taking place on catalyst
surfaces without a flame. Upon emerging from the catalytic
converter, the gas ignites immediately to burn thermally.
[0027] According to one object of the invention, the apparatus
comprises at least one thermal pre-treatment zone in fire-tube(s)
in the fire-tube boiler and at least one catalytic combustion zone
as a post-treatment installed in smoke--tube(s) in the fire-tube
boiler. Fire-tube boiler can be e.g. one-way, two-way, three-way or
four-way boiler. These embodiments gives essential advantage
because it gives very efficient way to control both pre-combustion
and post-combustion burning. It is also now possible to optimize
place of post-combustion catalytic zone in very advantageously.
Catalytic zone can be fixed case by case so that conditions for
catalytic burning are optimal even in varying temperatures and
boiler loads. Place can be fixed by measuring or e.g. by CFD
(computational fluid dynamics). Term "fire-tube boiler" is to be
understood in this application also e.g. as shell boiler and water
tube boiler. Term "fire-tube" is to be understood in this
application also e.g. as furnace, combustion chamber, flame tube,
first-pass, fire-box. Term "smoke-tube" is to be understood in this
application also e.g. as second pass, convection part, tube(s).
[0028] Temperature in fire-tube is usually over 1000.degree. C. and
in smoke-tubes 1000 to 300.degree. C. Catalytic zone (e.g.
three-way catalytic) is usually fixed e.g. to two-way tubes, where
conditions for catalytic burning are optimal even in varying
temperatures and boiler loads. Place can be fixed by measuring or
e.g. by CFD (computational fluid dynamics). In an example in
two-way boiler, where temperature in fire-tube is between 1000 to
1750.degree. C. and temperature in smoke tubes was 1000 to
300.degree. C., three-way catalytic was placed so that current
temperature in catalytic zone was about 360 to 860.degree. C.
[0029] This burner and boiler combination can be constructed from a
conventional pipe heat exchanger. Heat transfer can be enhanced by
inducing a swirl in the gas. This heat transfer solution is useful
for achieving a more effective heat transfer performance despite
the lower peak temperature. Enclosed is one example. Like-wise, the
boiler and burner become smaller in size and lower in costs. There
is no need for special materials, and standard solutions such as
heat exchangers can be applied.
Example
[0030] In a three-way catalytic converter take place simultaneously
the following main reactions:
HC+O2->H2O+CO2
CO+O2->CO2
HC+NOx->H2O+CO2+N2
CO+NOx->CO2+N2
[0031] Temperature in the catalytic converter may rise to an
extraordinary high level (in excess of 1500.degree. C.). Therefore,
the catalytic converter must be constructed by using highly heat
resistant steel grades such as 1.4767, 1.4828, Nicrofer 6025 HT
etc. or ceramic honeycomb cells. It is preferred that the catalytic
converter be coated with some platinum group metal and a porous
coating. Ecocat Oy, among others, has developed a catalytic
converter capable of withstanding extraordinarily high
temperatures, which is applicable to this purpose. A preferred
solution from the standpoint of a favorable combustion result is a
mixing metal-core catalytic converter.
[0032] With traditional thermal combustion, it is difficult to
reach a NOx level of 50 mg/Nm.sup.3. An attempt to minimize the NOx
emission brings forth a hazard of increased hydrocarbon and carbon
monoxide emissions due to incomplete burning. An advantage in the
present invention is that the combustion process as a whole is very
short, nor is a large pre-chamber necessary for burning. The
generation of nitrogen oxides increases exponentially as
temperature is rising and directly proportionally as a function of
burn time. The increase of oxygen amount decreases the formation of
NOx's in proportion to the square root of the content.
[0033] The burner has a low maintenance demand and catalytic
converters of precious metals have a long service life. The burner
consists of a few components easy to disassemble for
maintenance.
[0034] Greenhouses would make an excellent target for this
technology. In the process of burning propane, the resulting amount
of carbon dioxide is 3-times, and in the process of burning natural
gas, it is 2-times with respect to the consumption of fuel. It is
almost an optimal amount from the standpoint of fertilizing demand
for CO.sub.2. At present, the fertilization is primarily carried
out with liquefied carbon dioxide, which is mainly produced by a
fermentation process, and then purified and liquefied by cooling.
This is in total contradiction with current environmental
regulations. Another problem is the warming-up and evaporation of
CO.sub.2 during storage.
[0035] The catalytic Ultra LowNox, NoVoc and NoCo burner is small
in size and attractive in costs. It enables even the strictest
emission standards to be attained without post-flue gas treatment.
The elimination of final emission percentage is always the most
expensive phase.
[0036] The useful fuels comprise nearly all gaseous and several
liquid fuels, such as natural gas, biogas, bioethanol, propane,
light fuel oil, oil/water emulsions, etc. The most practical are
low sulfur fuels and gases not containing halogens. Even the latter
can be used, but necessarily with a different catalytic converter
and boiler materials. The combustion of sulfur compounds results in
the formation of sulfuric acid and the combustion of chlorinated
hydrocarbons results in hydrochloric acid.
[0037] The removal of nitrogen oxides unavoidably generated in
thermal combustion is difficult and expensive downstream of the
boiler. What is most commonly needed is an SCR or SNCR (Selective
Catalytic Reduction or Selective Non Catalytic Reduction) catalytic
converter and a selective reducer ammonia or urea therefor. In
addition to a high acquisition price, there will be a perpetual
acquisition expense for the reducer (ammonia or urea), nor is the
low NOx level of a catalytic NoNox burner always reachable. The
reduction of NOx's generated in thermal combustion and the
oxidation of VOC and CO emissions require a temperature higher than
250.degree. C.
[0038] The combined thermal and catalytic burner fulfills the
present and tightening future NOx, VOC and CO emission standards
without any exhaust gas after-treatment. The catalytic burner is a
solution less expensive than any of the reference technologies for
the elimination of NOx, HC and CO emissions in energy
production.
[0039] The catalytic burner is capable of achieving such low level
NOx and ethylene emissions that enable the delivery of flue gases
directly into a greenhouse for a CO.sub.2 fertilizer and the use of
combustion-generated energy for greenhouse heating. The NOx and
ethylene emission standard for greenhouses is about 100 times
stricter than the workplace air quality standard for people.
[0040] The catalytic burner is a solution less expensive than any
of the reference technologies for the elimination of NOx, HC and CO
emissions in energy production.
[0041] It is preferred that the catalytic burner be provided with a
mixing honeycomb or some other structure, which enhances material
transfer and intensifies oxidation (diffusion of combustion gas
molecules in the micropores of a catalytic converter) and at the
same time reduces the amount of emissions.
[0042] A few embodiments of the invention are further depicted in
FIGS. 1-3:
[0043] FIG. 1 shows an apparatus, comprising two catalytic
pre-treatment zones and thermal combustion as a post-treatment
[0044] FIG. 2 shows an apparatus, comprising two catalytic
pre-treatment zones and catalytic combustion as a
post-treatment
[0045] FIG. 3 shows an apparatus, comprising one thermal
pre-treatment zone and two catalytic combustions as a
post-treatment
[0046] FIG. 4 shows an apparatus comprising one thermal
pre-treatment zone in fire-tube and catalytic combustions as a
post-treatment installed in smoke-tubes in two-way fire-tube
boiler
[0047] FIG. 5 shows an apparatus comprising one thermal
pre-treatment zone in fire-flue and catalytic combustions as a
post-treatment installed in smoke-tubes in a three-way fire-tube
boiler
[0048] The apparatuses APP of FIGS. 1-3 are provided with one inlet
for a liquid or gaseous fuel FUE and for air AIR and one outlet for
gases for removing gases EXHG generated in the apparatus APP, as
well as with at least one measurement and adjustment unit C for
adjusting the amount of fuel FUE and air AIR. Further depicted in
FIGS. 1-3 are optional extra mixers MIX. The apparatuses comprise
the following operations: [0049] the partial pre-combustion of fuel
FUE in at least one pre-combustion zone Cz11, Cz12, Tz1, such that
the supplied fuel is burned only partially, [0050] the
post-combustion of pre-combustion-generated gases GAS1 in at least
one post-combustion zone Tz2, Cz21, Cz22 for burning the
pre-combustion-generated gases, for the reduction of
pre-combustion-generated NOx's, and/or for the oxidation of
hydrocarbon and carbon monoxide emissions, the pre-combustion
and/or post-combustion being carried out in at least one catalytic
zone Cz11, Cz12, Cz21, Cz22, which comprises activated channels and
non-activated zones for just partial combustion of the fuel and for
adjusting the combustion temperature. The apparatuses APP of FIGS.
1-3 are provided with a heat exchanger HE for the transfer of heat
generated in pre-combustion and/or in post-combustion.
[0051] In FIGS. 1 and 3, the pre-combustion or post-combustion is
carried out in one thermal zone Tz1, Tz2. In FIG. 1, the
pre-combustion is carried out in two catalytic pre-combustion zones
Cz11, Cz12 and the post-combustion is carried out in one thermal
post-combustion zone Tz2. In FIG. 2, the pre-combustion is carried
out in two catalytic pre-combustion zones Cz11, Cz12 and the
post-combustion is carried out in one catalytic post-combustion
zone Cz21. In FIG. 3, the pre-combustion is carried out in one
thermal pre-combustion zone Tz1 and the post-combustion is carried
out in two catalytic post-combustion zones Cz21, Cz22.
[0052] In FIGS. 4 and 5 pre-combustion or post-combustion is
carried out in one thermal zone Tz1 in fire-tube FLU, such that the
supplied fuel is burned only partially. Post-combustion is carried
out in catalytic zone(s) Cz21, Cz22 in smoke-tubes FTU for burning
the pre-combustion-generated gases, for the reduction of
pre-combustion-generated NOx's, and/or for the oxidation of
hydrocarbon and carbon monoxide emissions. The apparatuses APP of
FIGS. 4 and 5 are provided with one inlet for a liquid or gaseous
fuel FUE and for air AIR and one outlet for gases for removing
gases EXHG generated in the apparatus APP, as well as with at least
one measurement and adjustment unit C for adjusting the amount of
fuel FUE and air AIR. The apparatuses APP of FIGS. 4 and 5 are
provided with a heat exchanger HE for the transfer of heat
generated in pre-combustion and in post-combustion.
* * * * *