U.S. patent application number 13/263358 was filed with the patent office on 2012-02-16 for method and an apparatus for producing carbon dioxide and thermal energy.
This patent application is currently assigned to FORMIA EMISSIONS CONTROL OY. Invention is credited to Reijo Lylykangas.
Application Number | 20120040295 13/263358 |
Document ID | / |
Family ID | 40590387 |
Filed Date | 2012-02-16 |
United States Patent
Application |
20120040295 |
Kind Code |
A1 |
Lylykangas; Reijo |
February 16, 2012 |
METHOD AND AN APPARATUS FOR PRODUCING CARBON DIOXIDE AND THERMAL
ENERGY
Abstract
A method and apparatus for producing very pure carbon dioxide
containing gas and thermal energy and the use of such apparatus and
method are described. The production apparatus (PA) includes at
least one catalytic combustion unit (2) with at least one catalytic
burner (NCB) for catalytic combustion of fuel, for burning the fuel
efficiently at a temperature of 350 to 850.degree. C. in a
retention time of 0.01 to 0.1 s, and at least one heat exchanger
(RHE, THE) for at least partial transfer of heat from the gas
(CO2G) formed in the combustion to the combustion air (AIR) and the
fuel (PG) to be supplied into the catalytic burner (NCB). The
production apparatus (PA) also includes at least one catalytic
after burner (ACB) for at least partial after purification of the
gas (CO2G) formed in the combustion.
Inventors: |
Lylykangas; Reijo;
(Vihtavuori, FI) |
Assignee: |
FORMIA EMISSIONS CONTROL OY
Saynatsalo
FI
|
Family ID: |
40590387 |
Appl. No.: |
13/263358 |
Filed: |
April 7, 2010 |
PCT Filed: |
April 7, 2010 |
PCT NO: |
PCT/FI2010/050270 |
371 Date: |
October 26, 2011 |
Current U.S.
Class: |
431/7 ; 110/204;
431/170; 431/354 |
Current CPC
Class: |
B01D 53/86 20130101;
F23C 13/00 20130101; B01D 2256/22 20130101; Y02E 20/348 20130101;
F23G 7/07 20130101; Y02E 20/34 20130101; F23L 15/02 20130101; F28D
19/04 20130101; F28D 21/001 20130101; F23C 9/00 20130101 |
Class at
Publication: |
431/7 ; 431/170;
110/204; 431/354 |
International
Class: |
F23C 13/00 20060101
F23C013/00; F23B 80/02 20060101 F23B080/02; F23D 14/22 20060101
F23D014/22; F23R 3/40 20060101 F23R003/40 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2009 |
FI |
U20090137 |
Claims
1-19. (canceled)
20. A production apparatus (PA) for thermal energy and/or very pure
carbon dioxide (CO.sub.2) containing gas, driven by gaseous and/or
liquid fuel and comprising at least one injector (J) for injecting
fuel (PG) and at least one main blower (1) for supplying combustion
air (AIR), wherein the production apparatus (PA) comprises at least
one catalytic combustion unit (2) with at least one catalytic
burner (NCB) for catalytic combustion of fuel, for burning the fuel
efficiently at a temperature of 350 to 850.degree. C. in a
retention time of 0.01 to 0.1 s, and at least one two-stage heat
exchanger (RHE, THE) for transferring heat at least partly from the
gas (CO2G) formed in the combustion to the combustion air (AIR) and
the fuel (PG) to be supplied into the catalytic burner (NCB), and
that the production apparatus (PA) comprises at least one catalytic
afterburner (ACB) for at least partial after purification of the
gas (CO2G) formed in the combustion, and that said production
apparatus (PA) additionally comprises at least one main valve (MV)
in the main channel for supplying gas to said catalytic afterburner
(ACB), and at least one by-pass valve (BBV) for supplying gas to
said catalytic afterburner (ACB) when the main valve (MV) in the
main channel is closed.
21. The production apparatus according to claim 20, wherein the
temperature of the catalytic burner is 400 to 800.degree. C., such
as 500 to 700.degree. C. or 600 to 800.degree. C.
22. The production apparatus according to claim 20, wherein the
retention time of the fuel (PG) in the catalytic burner is 0.02 to
0.05 s.
23. The production apparatus according to claim 20, wherein the
production apparatus comprises at least one gas recirculation
apparatus (CG) for at least partial recirculation of the gas (CO2G)
formed in the combustion.
24. The production apparatus according to claim 20, wherein the
catalytic burner (NCB) comprises two or more stages.
25. The production apparatus according to claim 20, wherein the
catalytic production apparatus (PA) comprises gas guiding means for
guiding the flow of gas (CO2G) from the first stage (NCB1) of the
catalytic burner (NCB) to a catalytic after burner (ACB) and/or to
another stage (NCB2) of the catalytic burner (NCB).
26. The production apparatus according to claim 20, wherein the
heat exchanger (RHE, THE) is selected from the group of a two-stage
heat exchanger, a multi-stage heat exchanger, a rotary-bed heat
exchanger.
27. The production apparatus according to claim 20, wherein the
catalytic combustion unit (2) comprises gas distribution means for
guiding the gas flow during the change of direction of the gas
supply.
28. The production apparatus according to claim 20, wherein the
production apparatus (PA) comprises at least one after heat
exchanger (AHE) for recovering heat from the gas (CO2G) formed in
the combustion.
29. The production apparatus according to claim 28, wherein the
after heat exchanger (AHE) comprises means for producing hot water
and/or district heat.
30. The production apparatus according to claim 20, wherein the
injector (J) comprises means for at least partial burning of the
fuel (PG) to be supplied.
31. The production apparatus according to claim 20, wherein the
production apparatus (PA) comprises means for diluting the gas
(CO2G) formed in the combustion and for leading it, for example,
into a greenhouse.
32. A method for manufacturing a production apparatus (PA) suitable
for producing thermal energy and very pure carbon dioxide
(CO.sub.2) containing gas, wherein the production apparatus (PA) is
equipped with at least one injector (J) for injecting fuel (PG), at
least one main blower (1) for supplying combustion air (AIR), and
that the production apparatus (PA) is equipped with at least one
catalytic combustion unit (2) with at least one catalytic burner
(NCB) for catalytic combustion of fuel, for burning the fuel at a
temperature of 350 to 850.degree. C. in a retention time of 0.01 to
0.05 s, and at least one two-stage regenerative heat exchanger
(RHE) for at least partial transfer of heat from the gas (CO2G)
formed in the combustion to the combustion air (AIR) and the fuel
(PG) to be supplied into the catalytic burner (NCB), and that the
production apparatus (PA) is equipped with at least one catalytic
after burner (ACB) for at least partial after purification of the
gas (CO2G) formed in the combustion, and that and that said
production apparatus (PA) is additionally equipped with at least
one main valve (MV) in the main channel for supplying gas to said
catalytic afterburner (ACB), and at least one by-pass valve (BBV)
for supplying gas to said catalytic afterburner (ACB) when the main
valve (MV) in the main channel is closed.
33. A method for utilizing a production apparatus (PA) for thermal
energy according to claim 20, wherein the fuel (PG) is selected
from the group of propane, butane, natural gas, fuel oil, biogas,
bioalcohols, organic solvents, pyrolysis gases, and light fuel
oil.
34. The method according to claim 33, wherein said by-pass valve
(BBV) is opened at the same time when said main valve (MV) is
closed, and after this, the flow direction in that the production
apparatus (PA) is reversed and during the time of the reversal of
the flow direction, the gas is passed via by-pass valve (BBV)
directly to afterburner (ACB), and after the reversal of the flow
direction, said by-pass valve (BBV) is closed and said main valve
(MV) is opened.
35. The method according to claim 33, wherein in the gas formed in
the combustion (CO2G), the level of nitrogen oxides (NO.sub.x) is
lower than 5 ppm and the level of ethene (C.sub.2H.sub.4) is lower
than 1 ppm, calculated for an oxygen content of 3 vol %.
36. The method according to claim 33, wherein in the gas formed in
the combustion (CO2G), the level of nitrogen oxides (NO.sub.x) is
lower than 2 ppm, calculated for an oxygen content of 3 vol %.
37. The method according to claim 33, wherein the production
apparatus (PA) is used particularly for producing carbon dioxide
(CO.sub.2) containing gas that is very pure in terms of nitrogen
oxides, ethene (C.sub.2H.sub.4) and hydrogen sulphide.
38. The method according to claim 33, wherein the production
apparatus (PA) is applied particularly for producing thermal
energy.
39. The method according to claim 33, wherein the production
apparatus (PA) is applied particularly for producing both thermal
energy and carbon dioxide (CO.sub.2) containing gas that is very
pure in terms of nitrogen oxides, ethene (C.sub.2H.sub.4) and
hydrogen sulphide.
Description
TECHNICAL BACKGROUND
[0001] The invention relates to an apparatus for producing very
pure carbon dioxide containing gas and thermal energy. The
invention also relates to a method for producing carbon dioxide
containing gas and thermal energy, as well as the use of such an
apparatus and a method.
[0002] Carbon dioxide can be used for a number of purposes. It can
be directly applied in various uses, and on the other hand, it is
suitable as a raw material for many processes. However, carbon
dioxide is a problematic product, because emissions of it
contribute to the greenhouse effect. Therefore, the controlled
production of carbon dioxide is of primary importance.
[0003] In atmospheric air, the content of CO.sub.2 is about 380
ppm. When plants are grown in a greenhouse, the content of CO.sub.2
will drop to a level of about 150 to 220 ppm if no supplementary
CO.sub.2 is added. At a level of about 800 ppm, the growth of, for
example, cucumber, tomato and lettuces, as well as tulips, has been
found to increase by about 30 to 50% in a greenhouse.
[0004] On the other hand, impurities in carbon dioxide containing
gas slow down the growth of plants. For example, nitrogen oxides at
a level of 0.1 to 2 ppm block the fertilizing effect of
supplementary CO.sub.2. Also, for sulphur oxides, the highest
allowed levels range from 0.015 to 0.1 ppm, depending on the
duration of exposure. For ethene (C.sub.2H.sub.4), the allowable
limits are even more stringent, from 0.002 to 0.01 ppm. The
strictest limits are for hydrogen sulphide, which is only allowed
at a level of 0.001 ppm.
[0005] Thermal energy, and partly also carbon dioxide, is
conventionally produced by burning to be used in, for example,
greenhouses. The fuels suitable for this burning must be pure. The
combustion takes place at a high temperature, and oxides of
nitrogen and sulphur are easily formed as side products, and some
of the ethene remains unburnt. The strict standards for purity of
CO.sub.2 hinder the application of gas produced in thermal
combustion in greenhouses. Special Low NOx or Ultra Low NOx burners
are needed to reach the level of 50 to 80 ppm in the production of
nitrogen oxides. Even when strongly diluted, they do not meet the
latest requirements set for plants.
[0006] Furthermore, the production of pure carbon dioxide
containing gas is relatively expensive and involves relatively
complex technology. In small greenhouses, pure carbon dioxide is
used in the form of bottled gas or liquid. Used in this way, the
costs of carbon dioxide become very high. The costs of the gas for
a greenhouse may be almost in the order of the heating costs.
DESCRIPTION OF THE INVENTION
[0007] Now, an apparatus has been invented for producing thermal
energy and/or very pure carbon dioxide (CO.sub.2) containing gas,
which is technically very simple and has particularly low emissions
of impurities.
[0008] To achieve this aim, the invention is characterized by the
features which will be presented in the independent claims. The
other claims will present some advantageous embodiments of the
invention.
[0009] The apparatus according to the invention, which is suitable
for producing thermal energy and very pure carbon dioxide
(CO.sub.2) containing gas, comprises at least one injector for
injecting fuel and at least one main blower for supplying
combustion air, and the production apparatus comprises at least one
catalytic combustion unit with at least one catalytic burner for
catalytic combustion of fuel effectively at a temperature of 350 to
850.degree. C. in a retention time of 0.01 to 0.1 s, and at least
one heat exchanger for at least partial transfer of heat from the
gas produced in combustion to the combustion air and fuel to be
supplied to the catalytic burner, and the production apparatus
comprises at least one catalytic afterburner for at least partial
after purification of the gas produced in combustion.
[0010] Said at least one catalytic afterburner connected to the
burning unit guarantees and improves the purification results of
the catalytic burner further. It enables different ways of running,
and even in connection with reversals, the gas can be guided
through a burner.
[0011] According to one aspect of the invention, the production
apparatus comprises at least one gas recirculating device for
guiding the gas formed in combustion at least partly to the main
blower. This solution improves substantially the energy balance of
the plant, because the need to heat combustion air is reduced;
advantageously, the content of recirculated gas is greater than
50%, such as 70 to 90%.
[0012] According to one aspect of the invention, the catalytic
production apparatus comprises gas guiding members for guiding the
flow of gas from the first stage of the catalytic burner to a
catalytic afterburner and/or to another stage of the catalytic
burner. This will make the usability of the plant even more
versatile.
[0013] According to one aspect of the invention, the heat exchanger
is selected from a group consisting of a two-stage heat exchanger,
a multi-stage heat exchanger, and a rotary-bed heat exchanger.
These are technologically and economically advantageous solutions.
Preferably, the heat exchanger is regenerative.
[0014] According to one aspect of the invention, the catalytic
combustion unit comprises a two-stage or multi-stage heat exchanger
and gas distribution means for guiding the flow of gas during a
change in the direction of gas supply. This solution, too, makes
the use of the apparatus more versatile and is technically and
economically advantageous.
[0015] According to one aspect of the invention, in the gas formed
in the combustion (CO2G), the level of nitrogen oxides (NO.sub.x)
is lower than 5 ppm and the level of ethene (C.sub.2H.sub.4) is
lower than 1 ppm, calculated for an oxygen content of 3 vol %.
According to one aspect of the invention, in the gas formed in the
combustion (CO2G), the level of nitrogen oxides (NO.sub.x) is lower
than 2 ppm, calculated for an oxygen content of 3 vol %. These
levels are implemented by controlling the combustion conditions of
the production apparatus so that these low contents are
achieved.
[0016] The formed carbon dioxide containing gas CO2G typically
contains about 14 to 17 wt % of carbon dioxide, such as 15 wt %,
when for example fuel oil or gases are applied. In the apparatus
according to the invention, the level of nitrogen oxides is
advantageously lower than 5 ppm, calculated for an oxygen content
of 3 vol %. For example, in a gas diluted for use in a greenhouse,
the level of nitrogen oxides is thus advantageously lower than 0.1
ppm. According to one aspect of the invention, the level of
nitrogen oxides in the afterpurified carbon dioxide containing gas
is lower than 2 ppm, calculated for an oxygen content of 3 vol %.
Such a gas can be used particularly well in, for example, a
greenhouse.
[0017] In the apparatus according to the invention, a gaseous or
liquid fuel can be burnt catalytically in a controlled manner by
means of a catalyzer at a low temperature, 350 to 850.degree. C.,
so that very little nitrogen oxides (NO.sub.x) and sulphur oxides
(SO.sub.X) are produced by combustion, and as a result of almost
complete combustion, negligible levels of hydrocarbons and carbon
monoxide are left in the gas. The level of ethene, which is the
most harmful of hydrocarbons to plants, is lower than 1 ppm,
calculated for an oxygen content of 3 vol %. In diluted fertilizer
gas, the content is less than 0.01 ppm, as well as the content of
carbon monoxide. The thermal energy produced in combustion can be
advantageously used for heating, and the cooled pure combustion gas
can be led to utilization. The untreated exhaust gases of the
heating boiler according to the invention are so pure that they
meet even the most stringent international standards for
emissions.
[0018] The content of other emissions, such as sulphur oxides, will
depend on the sulphur content of the fuel. To keep the sulphur
emissions low as well, low emission fuels should be used, such as
propanol, natural gas, bioalcohol, light fuel oil, pyrolysis gases,
or the like. The plant will then clearly meet all the standards for
emissions. (NOx and CO<100 mg/Nm.sup.3)
[0019] Preferably, catalytic combustion takes place at a low fuel
content below 20% from the LEL limit, which means a content of
about 10 g/Nm.sup.3. This is to prevent the temperatures from
rising too high at the oxidation stage. The flow of gas discharged
from the boiler is kept low by recirculation. The temperature of
the gas is about 50 to 90.degree. C., depending on the heat
exchange rs. Even from that, energy can still be recovered by means
of a separate heat exchanger.
[0020] Because there is no separate purification of flue gases in
the catalytic combustion plant, energy can be efficiently recovered
from the flue gases directly in the actual useful heat exchanger,
which may take place by the countercurrent principle.
[0021] In catalytic combustion according to the invention, the
temperature is 350 to 850.degree. C. The catalyzer lowers the
combustion temperature by about 100 to 400.degree. C. compared to
thermal combustion which typically requires a temperature of 750 to
950.degree. C. This temperature difference is very significant,
because at the lower temperature, the nitrogen present in the air
does not start to react with the oxygen in the air, and harmful
nitrogen oxides are thereby not developed. The catalytic combustion
is very fast, having typically a duration of only 0.01 to 0.1 s,
such as about 0.02 to 0.05 s, in the catalyzer itself and after
that, for example, about 0.1 s in the channel before the heat
exchanger. This duration is about one tenth compared with the
duration in a thermal boiler. Because the applications according to
the invention apply a relatively low temperature and a very short
retention time, hardly any nitrogen oxides (NOx) can be formed,
their level remaining preferably below 5 mg/Nm.sup.3. Furthermore,
in catalytic combustion, the oxidation is controlled so closely
that hydrocarbons and eventual carbon monoxide burn out, their
levels being normally lower than 5 mg/Nm.sup.3.
[0022] The investment costs of a catalytic boiler are lower than
those of thermal boilers with their purification systems. The
operating costs of thermal combustion are increased by the costs of
acquisition, use and maintenance of a reducer.
[0023] In thermal combustion, nitrogen oxides are usually formed at
such a high level that they must be removed in large boilers. The
removal takes place in a selective catalytic reducer (SCR) in which
the reducing agent used is ammonia or urea dissolving into ammonia
and carbon monoxide gas. The reduction takes place in a special
catalyzer so that one molecule of ammonia reduces one NOx molecule.
Urea or ammonia is normally needed in about 3 to 4% of the fuel
content, and it is even more expensive than the fuel. In other
words, it raises the combustion costs respectively. Because the SCR
catalyzer will require a temperature of about 230 to 300.degree. C.
to operate well, yet another heat exchanger must be provided after
the catalyzer.
[0024] Because the SCR catalyzer requires a long retention time of
about 0.3 s (space velocity of 10 to 12,000 1/h), its size is very
large. It is often larger in size than the boiler. Furthermore, the
SCR will require a tank of ammonia or urea and an automatic dosing
system. Both ammonia and urea are difficult substances in their own
way. Ammonia is very toxic to transport and store. The urea
solutions used are almost saturated aqueous solutions with a solid
content of 32 to 40%. They are easily crystallized and difficult to
dose. Moreover, both urea and ammonia reduction will require an
oxidation catalyst to eliminate possible leaks of ammonia.
[0025] In the apparatus according to the invention, no additional
energy will be needed for continuous operation. Only during
startup, the catalyzer/thermal burner and the heat exchanger must
be heated to the operating temperature, and thus the operating
costs of the plant are very low.
[0026] According to one aspect of the invention, the injector
comprises means for at least partial combustion of the fuel
supplied. In the beginning, the incoming gas is heated, if
necessary, to the combustion temperature, and after that, part of
the energy produced in catalytic combustion can be transferred to
heat the incoming gas.
[0027] According to one aspect of the invention, the apparatus is
formed of two parts: the catalytic combustion plant and the heat
exchanger. The catalytic combustion plant may be either a
regenerative or a recuperative apparatus. In it, the incoming
liquid fuel is first vaporized, and the gas is then heated in the
heat exchanger, after which it is oxidized in the catalyzer. Part
of the produced energy is transferred to heat the incoming gas, and
part is led via a post-catalyzer to the heat exchanger for useful
energy. After this, the gas flow that had heated the incoming gas
and the gas flow passed via the recovery of useful energy are
combined. The main part, preferably 70 to 90%, of this gas flow is
recirculated to the inlet side of the catalyzer, and the rest of
the gas is discharged via a flue gas duct to atmospheric air. 10 to
30% of clean air which contains the oxygen needed for catalytic
combustion is admixed to the gas flow entering the catalytic
combustion. In many cases, the most advantageous efficiency is
achieved when air is only admixed in the required amount, about
10%.
[0028] In some applications, the heat exchanger may be made of a
fire-resistant material. This improves the strength of the plant
and increases reliability and reduces the need for maintenance.
[0029] According to one aspect of the invention, the apparatus
comprises an after heat exchanger for recovering heat from gas
formed in the combustion and/or for aftercooling the carbon dioxide
containing gas discharged from the combustion unit. After the
catalytic combustion, an essential part of the heat can thus be
recovered via the heat exchanger for the purposes of heating a
greenhouse, and the clean CO.sub.2 containing flue gas can be led,
for example, into greenhouses for the purposes of fertilizing and
partly heating.
[0030] According to one aspect of the invention, the after heat
exchanger comprises means for producing hot water and/or district
heat. This will improve the total economy of the production
apparatus further.
[0031] According to one aspect of the invention, the production
apparatus is used particularly for producing both thermal energy
and carbon dioxide (CO.sub.2) containing gas that is very pure in
terms of nitrogen oxides, ethene (C.sub.2H.sub.4) and hydrogen
sulphide. According to one aspect of the invention, the production
apparatus is used particularly for producing thermal energy.
According to one aspect of the invention, the production apparatus
(PA) is used particularly for producing carbon dioxide (CO.sub.2)
containing gas that is very pure in terms of nitrogen oxides,
ethene (C.sub.2H.sub.4) and hydrogen sulphide. The selected object
of production will affect the temperature to be used in combustion.
For the production of heat, temperatures from 600 to 800.degree. C.
are preferably used, and for the production of carbon dioxide
(CO.sub.2) containing gas, the temperatures of catalytic combustion
may range, for example, from 350 to 500.degree. C. or from 500 to
700.degree. C., depending on the quantity of the gas to be produced
and on the object to be filled in.
[0032] According to an aspect of the invention, the fuel is
selected from the group of butane, propane, natural gas, fuel oil,
biogas, bioalcohols, organic solvents, pyrolysis gases, and light
fuel oil. The utilization of such fuels is technologically
advantageous and simple. By using the catalyzer, it is possible to
oxidize various gaseous and liquid fuels which may be fossil or
various biofuels from renewable sources (alcohols, gases released
by pyrolysis, biogas, etc.). It is also possible to oxidize
catalytically emissions of volatile organic solvents (VOC) or
carbon monoxide either as such or in combination with other actual
fuels.
[0033] According to one aspect of the invention, the apparatus
comprises means for diluting carbon monoxide containing gas and
leading it to a greenhouse. In this embodiment, the production
apparatus according to the invention has technical and economical
advantages. Preferably, the thermal energy produced by combustion
can be used entirely for heating when the cooled pure combustion
gas can be led into a greenhouse for fertilization with CO.sub.2.
The thermal energy remaining in the cooled combustion gas also
contributes to the heating of the greenhouse. It is advantageous,
for example, when the greenhouse is used in the winter.
[0034] The gas combustion unit may be a metal honeycomb system with
a rotary structure, comprising a catalyzer and a heat exchanger
unit one after the other. The gas comes in from one side first into
the heat exchanger, in which the gas is heated, and it then enters
the catalyzer, in which the gases are oxidized. Next, the gas
passes through the other side which collects heat. The structure
may also be a honeycomb system in two parts, wherein one cell is
used for collecting heat and the other is used for heating incoming
gas.
[0035] According to one aspect of the invention, the catalytic
burner comprises two or more stages. This arrangement makes the
apparatus controllable in a more versatile way and contributes to
the efficiency of the combustion.
[0036] The heat exchanger may be advantageously coated with a
catalytically active coating. This will further improve the
efficiency of the production apparatus.
[0037] The heat exchanger may also be a honeycombed system with a
steel structure and consisting of two parts, wherein one cell is
used for collecting heat and the other is used for heating incoming
gas. The direction of flow is reversed after the cell that heats
the incoming gas has cooled to a given limit value. The other cell
that has trapped heat from the exhaust gas will start to heat the
incoming air.
[0038] By optimizing the internal flow and dimensioning the heat
exchanger formed by thin sheets, the ratio of energy entering the
greenhouse via the fertilizing gas and the heat exchanger can be
easily controlled.
[0039] According to one aspect of the invention, the production
apparatus comprises one or more heat exchanger and/or catalyzer
means which are advantageously made of thin corrugated metal
sheets, with channels between them for conducting gas. This kind of
a structure is used as a static mixer. The structure increases
substantially, for example, the number of contacts of hydrocarbons
with a catalytically active surface. This so-called Sherwood number
(Sh), representing the efficiency of mass transport, increases from
2.5 to 12; in other words, the gas molecules to be burnt are almost
five times more frequently in contact with the catalytically active
surface. With the intensified contact, the fuel can be made to burn
completely (SAE 2002-01-0357).
[0040] The heat exchanger can be made of a steel sheet having a
thickness of 0.2 to 1.5 mm and being coated with Al and/or Zn or
being acid-proof, by corrugated "strips" with a width of 100 to 200
mm, in the same way as the catalyzer. This kind of a mixing
structure will substantially intensify the transfer of heat from
the gas into the steel sheet, and vice versa. The Nusselt number,
representing the heat transfer in a flow channel, will increase
from 2.5 to 12, compared with a straight channel. This will improve
substantially the efficiency of the heat exchanger.
[0041] The heat exchanger is advantageously a metal honeycomb
system with a rotary structure, which is passed through by gas that
is heated in the catalyzer to the required combustion temperature,
which is typically 500 to 700.degree. C. The heat exchanger may be
made of, for example, creased (corrugated) metal band or wire
mesh.
[0042] The catalyzer may be a rotary metal honeycomb with a shape
similar to that of the heat exchanger. The gas comes in from one
half, through both/all of the cells. In the accumulator cell, the
gas is heated to the combustion temperature, and in the catalyzer
following the accumulator, the gases are oxidized. After that, the
gases enter the other half of the heat exchanger, in which most of
the heat is transferred to the accumulator cell. The rotation speed
of the accumulators is preferably 0.3 to 5 rpm.
[0043] The combustion apparatus according to the invention
comprises no bulky tube systems or valves. It is very advantageous
in its structure, wherein the acquisition and operating costs are
very low compared with the prior art. Also, the operation and
maintenance of the apparatus is very inexpensive. Furthermore, the
process is simple and efficient to control.
[0044] According to one aspect of the invention, the production
apparatus comprises at least two processing compartments placed
within each other. In this embodiment, the catalyzer and the heat
accumulator do not rotate but the gas flow direction is reversed at
intervals by valves or by temperature control. They are
advantageously connected to each other by one or more connecting
parts to introduce the gas to be processed into the processing
compartments within each other, and the gas purification production
apparatus also comprises one or more adjustable gas guiding parts
for discharging gas and/or for supplying it into the processing
compartments within each other. By means of the connecting parts,
it is advantageously possible, for example, to reverse the gas flow
direction in the processing compartment. Thus, the same connecting
part can be used both for supplying and for discharging gas,
depending on the flow direction. In this way, the apparatus can be
made not only technically but also economically advantageous.
[0045] Preferably, the processing compartments within each other
have a cylindrical shape. Preferably, there is a cylinder inside
and an annular cylinder outside. These are made preferably by
winding corrugated bands first around a central axis. After all the
foil layers have been wound in the central part, its exterior is
lined with sheet iron, outside which an annular part of equal
volume is wound and is provided with an outer lining, and flow
control valves are fixed to the lower part.
[0046] The processing compartments can be preferably provided in a
common body which is also equipped with the gas flow channels that
replace a tube system. By building the channels as part of the
structure, an advantageous integrated configuration is achieved.
With these solutions, a compact size and simple structural
approaches are achieved which clearly reduce the costs compared
with the prior art. Thanks to the space saving achieved with the
compact structure and the removal of an external pipe system, it is
not possible to install a combustion plant of even 8 MW in a 6 m
container.
[0047] The operation of this so-called two-bed combustion plant
requires the reversal of the flow direction at intervals of about
30 to 200 seconds. In a conventional two-bed plant, a small
quantity of unpurified gas is discharged into atmospheric air when
the direction is reversed. In the plant according to the invention,
this problem is advantageously solved with the valve arrangement
shown in the chart. A valve in a by-pass channel on top of the
furnace is opened at the same time when the main channel is closed.
After this, the flow direction is reversed by control valves.
[0048] During the time of the reversal of the flow direction, the
gas is passed via catalyzers directly into the by-pass channel.
After this, the by-pass channel is closed and the main channel is
opened. During the reversal of the direction (3 to 5 s), no energy
is accumulated in the heat exchanger by which the incoming gas is
heated.
[0049] According to one aspect of the invention, the production
apparatus applies catalyzers made of noble metal and having a very
large surface area, which are known for their resistance to
so-called catalyzer toxins and high temperatures. With such
catalyzers it is possible to achieve an efficiency of even more
than 99.9% in the long term. The predicted lifetime of such a
catalyzer may be as long as 20 years.
[0050] According to one aspect of the invention, the production
apparatus comprises one or more particle filters. The filter
secures the undisturbed operation of the plant and advantageously
reduces the particle emissions of the plant.
[0051] The production apparatus according to the invention can be
made relatively compact, because the functions are integrated with
respect to each other in its structure. The volume/capacity ratio
of such a plant is good, and furthermore, the volume can be used
efficiently. This will facilitate transportations and installations
on the site of use. The container does not require a foundation or
any supporting structures. The production apparatus can be coupled
to be ready for use very fast, for example in a couple of days. The
container can be advantageously moved to a new location, if
necessary. For example, a combustion plant with a capacity of even
3 MW can be advantageously installed in a standard marine container
(6 m).
[0052] Preferably, the production apparatus is automated. It can
automatically adjust its operation for various loads, and its
operation can be controlled either by a computer or by a GMS phone,
if desired.
SPECIFIC DESCRIPTION OF THE INVENTION
[0053] In the following, some embodiments of the invention will be
described in detail with reference to the appended drawings.
[0054] FIG. 1 shows a schematic chart on a production apparatus
with a rotary bed heat exchanger.
[0055] FIG. 2 shows a schematic chart on a production apparatus
with a two-stage heat exchanger.
[0056] FIG. 3 shows a schematic chart on a production apparatus
with a two-stage thermal boiler as an after heat exchanger.
[0057] FIG. 1 shows a production apparatus PA comprising one main
blower 1 of combustion air AIR, equipped with an injector J for
injecting fuel PG into the combustion air AIR, as well as a
catalytic combustion unit 2. Confined in the combustion unit 2,
substantially inside its walls 2W, there is a catalytic burner NCB
for catalytic burning of fuel at a temperature of 350 to
850.degree. C. in a retention time of 0.01 to 0.1 s for generating
carbon dioxide containing gas. In front of the main blower, there
is a particle filter PF which improves the operation of the plant
and reduces the particle emissions of the plant in an advantageous
way. The injector J comprises means for at least partial burning of
the fuel PG to be supplied. The production apparatus comprises a
rotary-bed RHE regenerative heat exchanger for transferring heat
from the carbon dioxide containing gas CO2G generated in the
catalytic burner to the combustion air AIR to be supplied into the
catalytic burner NCB, and to the fuel PG. The catalytic combustion
unit 2 is equipped with a catalytic after burner ACB for after
purification of the carbon dioxide containing gas CO2G. The
production apparatus PA also comprises an after heat exchanger AHE
for aftercooling the carbon dioxide containing gas CO2G discharged
from the combustion unit 2.
[0058] FIG. 2 shows a production apparatus PA comprising one main
blower 1 of combustion air AIR, equipped with an injector J for
injecting fuel PG into the combustion air AIR, as well as a
catalytic combustion unit 2. Confined in the combustion unit 2,
substantially inside its walls 2W, there is a catalytic burner NCB
for catalytic burning of fuel at a temperature of 350 to
850.degree. C. in a retention time of 0.01 to 0.1 s for generating
carbon dioxide containing gas. In front of the main blower, a
particle filter PF is provided to improve the operation of the
plant and to reduce the particle emissions of the plant in an
advantageous way. The injector J comprises means for at least
partial burning of the fuel PG to be supplied. The production
apparatus comprises a two-stage regenerative heat exchanger THE for
transferring heat from the carbon dioxide containing gas CO2G
generated in the catalytic burner to the combustion air AIR to be
supplied into the catalytic burner NCB, and to the fuel PG. The
catalytic combustion unit 2 is equipped with a catalytic after
burner ACB for after purification of the carbon dioxide containing
gas CO2G. Above/after the furnace there is a by-pass channel with a
by-pass valve BBV which is opened at the same time when the main
valve MV in the main channel is closed. After this, the flow
direction is reversed by the control valves of the two-stage heat
exchanger (not shown in the figures). During the time of the
reversal of the flow direction, the gas is passed via catalyzers
directly into the by-pass channel. After this, the by-pass channel
BBV is closed and the main valve MV is opened. During the reversal
of the direction, which takes about 3 to 5 s, no energy is
accumulated in the two-part heat exchanger by which the incoming
gas is heated. The production apparatus PA also comprises an after
heat exchanger AHE for aftercooling the carbon dioxide containing
gas CO2G discharged from the combustion unit 2.
[0059] FIG. 3 shows a production apparatus PA comprising one main
blower 1 of combustion air AIR and an injector J for injecting
combustion air AIR and fuel PG, as well as a catalytic combustion
unit 2. Confined in the combustion unit 2, substantially inside its
walls 2W, there is a catalytic burner NCB for catalytic burning of
fuel at a temperature of 350 to 850.degree. C., such as
advantageously at a temperature of 600 to 800.degree. C., in a
retention time of 0.01 to 0.1 s for generating carbon dioxide
containing gas. In front of the main blower, a particle filter PF
is provided to improve the operation of the plant and to reduce the
particle emissions of the plant in an advantageous way. The
production apparatus comprises a two-stage regenerative heat
exchanger THE for transferring heat from the carbon dioxide
containing gas CO2G generated in the catalytic burner to the
combustion air AIR and the fuel PG to be supplied into the
catalytic burner NCB. The catalytic combustion unit 2 is equipped
via a main valve MV with a catalytic after burner ACB for after
purification of the carbon dioxide containing gas CO2G. Part of the
gas is guided after the catalytic combustion into the by-pass
channel BBV via the heat exchanger THE, to maintain the process
heat. Furthermore, the production apparatus PA is equipped with an
after heat exchanger AHE for recovering heat from the gas CO2G
formed in the combustion. Moreover, the production apparatus PA is
also equipped with a gas recirculation apparatus CG for returning
the gas CO2G formed in the combustion at least partly to the main
blower 1; preferably, the content of recirculated gas is 70 to 90%
of the discharged gas.
* * * * *