U.S. patent application number 13/513556 was filed with the patent office on 2012-11-29 for gassification system.
Invention is credited to Rifat Al Chalabi, Ophneil Henry Perry, John Henry Turner.
Application Number | 20120298020 13/513556 |
Document ID | / |
Family ID | 41641938 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120298020 |
Kind Code |
A1 |
Chalabi; Rifat Al ; et
al. |
November 29, 2012 |
GASSIFICATION SYSTEM
Abstract
The invention provides an apparatus for processing material such
as organically coated waste and organic materials including
biomass, industrial waste, municipal solid waste and sludge,
comprising a processing chamber (2) for processing said material at
an elevated temperature to produce syngas and a combustion chamber
(4) having at least one burner therein for combusting syngas
released by processing of said material. A conduit means (18) is
provided between said combustion chamber and said processing
chamber for carrying hot exhaust gasses from the combustion chamber
(4) to said processing chamber (2) and at last one mirror (24) is
arranged to reflect and concentrate sunlight thereby to cause the
temperature within said processing chamber (2) to be raised. The
apparatus also includes a syngas reservoir (66). A storage conduit
(62) is provided for carrying syngas into said syngas reservoir
(66) and a syngas feed line (68) is provided for feeding syngas
from said reservoir to said combustion chamber (4).
Inventors: |
Chalabi; Rifat Al;
(Nottingham, GB) ; Perry; Ophneil Henry;
(Nottingham, GB) ; Turner; John Henry; (Retford,
GB) |
Family ID: |
41641938 |
Appl. No.: |
13/513556 |
Filed: |
November 26, 2010 |
PCT Filed: |
November 26, 2010 |
PCT NO: |
PCT/GB2010/002178 |
371 Date: |
August 6, 2012 |
Current U.S.
Class: |
110/346 ;
110/229; 110/235; 431/207 |
Current CPC
Class: |
F23G 5/16 20130101; F24S
23/71 20180501; Y02P 20/133 20151101; Y02E 10/40 20130101; F23G
2201/303 20130101; F23G 7/00 20130101; Y02P 80/20 20151101; F23G
2900/50204 20130101; F23G 2202/103 20130101; F23G 2209/00 20130101;
F24S 23/74 20180501; F23G 5/0273 20130101 |
Class at
Publication: |
110/346 ;
110/229; 110/235; 431/207 |
International
Class: |
F23G 5/027 20060101
F23G005/027; F23G 5/46 20060101 F23G005/46; F23G 5/08 20060101
F23G005/08; F23G 7/00 20060101 F23G007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2009 |
GB |
0921266.3 |
Claims
1. An apparatus for processing material such as organically coated
waste and organic materials including biomass, industrial waste,
municipal solid waste and sludge, comprising: a processing chamber
for processing said material at an elevated temperature to produce
syngas; a combustion chamber having at least one burner therein for
combusting syngas released by processing of said material; a
conduit means between said combustion chamber and said processing
chamber for carrying hot exhaust gasses from the combustion chamber
to said processing chamber; at last one mirror arranged to reflect
and concentrate sunlight thereby to cause the temperature within
said processing chamber to be raised; a syngas reservoir; a storage
conduit for carrying syngas into said syngas reservoir; and a
syngas feed line for feeding syngas from said reservoir to said
combustion chamber.
2. The apparatus according to claim 1 wherein said storage conduit
and said syngas feed line comprise sections of a conduit between
said processing chamber and said combustion chamber such that the
syngas reservoir is inline in said conduit between said processing
chamber and said combustion chamber.
3. The apparatus according to claim 1 further comprising: a first
control valve to control the flow of gas from said conduit between
said processing chamber and said combustion chamber into the syngas
reservoir; and a second valve to control the flow of combustion
chamber exhaust gas into said processing chamber.
4. The apparatus according to claim 1 further comprising syngas
reservoir bypass conduit for the flow of syngas from the processing
chamber to the combustion chamber without passing through the
syngas reservoir.
5. The apparatus according to claim 4 further comprising: at least
a second mirror for reflecting sunlight onto a second heat
absorbent surface adjacent said reservoir bypass conduit do as to
pre heat said syngas passing through said bypass conduit prior to
combustion in said combustion chamber.
6. The apparatus according to claim 1 further comprising a fossil
fuel feed line to said burner capable of maintaining a burner pilot
and/or, in the absence of sufficient syngas and/or solar heat,
providing sufficient fossil fuel for combustion in said burner so
as to in use, create sufficient heat for the oxidation of any
syngas entering said combustion chamber.
7. The apparatus according to claim 1 wherein syngas produced by
said processing chamber is directed into said combustion chamber
burner.
8. The apparatus according to claim 1 wherein: the processing
chamber has at least one external heat absorbent surface associated
therewith and said at last one mirror is arranged to reflect and
concentrate sunlight onto said heat absorbing surface.
9. The apparatus according to claim 8 wherein said heat absorbent
surface comprises a heat absorbent external layer and a first gas
heating conduit adjacent said heat absorbent layer for receiving
combustion chamber exhaust gas, said first gas heating conduit in
fluid communication with said processing chamber such that, in use,
combustion chamber exhaust gas passing adjacent said heat absorbent
surface is heated by said reflected sunlight and flows into said
process chamber so as to raise the temperature therein.
10. The apparatus according to claim 9 further comprising: an
insulating layer adjacent said first gas heating conduit and
separated from said absorbent layer thereby; and a bypass valve
operable to either direct exhaust gas from said combustion chamber
through said first gas heating conduit or direct exhaust gas from
said combustion chamber through a gas heating conduit bypass;
wherein said gas heating conduit bypass is separated from said heat
absorbent surface by an insulating layer.
11. The apparatus according to claim 8 wherein the processing
chamber is moved during operation and said heat absorbent surface
forms an external surface of said movable processing chamber.
12. The apparatus according to claim 8 wherein the external surface
of the first and/or second heat absorbing surface has a surface
texture thereon so as to increase its surface area.
13. The apparatus according to claim 1 further comprising: a
further at least one mirror for reflecting and concentrating
sunlight directly into said combustion chamber so as to raise the
temperature within said combustion chamber.
14. The apparatus according to claim 13 wherein said combustion
chamber comprises at least one substantially transparent section to
allow the concentrated sunlight to enter said combustion
chamber.
15. An apparatus according to claim 1 further comprising a
combustion chamber exhaust gas outlet for supplying hot exhaust gas
to a means of converting heat to electrical energy.
16. A method of processing organic waste comprising: placing said
organic waste is a processing chamber; reflecting sunlight from a
plurality of mirrored surfaces onto a heat absorbent surface so as
to raise the temperature, in an oxygen deficient environment,
within said processing chamber so as to cause the organic waste
material to gassify and produce synthetic gas; withdrawing said
synthetic gas from said processing chamber; diverting at least a
portion of said withdrawn syngas into a storage reservoir; and
passing the remainder of the syngas into a combustion chamber where
at least some of it is combusted to raise its temperature so as to
destroy any volatile organic compounds therein; re-circulating at
least a portion of the combustion chamber exhaust gas back into
said processing chamber.
17. The method according to claim 16 wherein the temperature of the
syngas in the combustion chamber is raised in the presence of
oxygen to a sufficient temperature to oxidise said synthetic
gas.
18. The method according to claim 16 further comprising feeding
syngas from said storage reservoir to said combustion chamber.
19. The method according to claim 16 further comprising introducing
fossil fuel into a burner within the combustion chamber to produce
a flow of hot combustion chamber exhaust gas, for re-circulation
back into said processing chamber, sufficient to compensate for any
shortfall in reflected sunlight used for heating said processing
chamber.
20. The method according to claim 19 further comprising:
controlling the flow of syngas diverted into the reservoir;
controlling the flow of syngas from the reservoir into the
combustion chamber; and controlling the flow of combustion chamber
exhaust gas into the production chamber; so as to maximise the
solar energy used by the process and minimise the fossil fuel burnt
in the burner.
21. A method of processing organic waste comprising: during
sunlight hours, following the steps of: a) placing said organic
waste is a processing chamber; b) reflecting sunlight from a
plurality of mirrored surfaces onto a heat absorbent surface so as
to raise the temperature, in an oxygen deficient environment,
within said processing chamber so as to cause the organic waste
material to gassify and produce synthetic gas; c) withdrawing said
synthetic gas from said processing chamber; d) diverting at least a
portion of said withdrawn syngas into a storage reservoir; e)
passing the remainder of the syngas into a combustion chamber where
at least some of it is combusted to raise its temperature so as to
destroy any volatile organic compounds therein; and f)
re-circulating at least a portion of the combustion chamber exhaust
gas back into said processing chamber; and during night time hours
introducing syngas from said syngas reservoir into a burner within
said combustion chamber so as to: a) create sufficient hot exhaust
gas to heat said processing chamber to the required temperature for
the gasification of the organic waste therein; and b) raise the
temperature within the combustion chamber to a sufficient
temperature to oxidise therein syngas produced in and received from
said processing chamber.
22. The method according to claim 21 wherein the method further
comprises: during said night time hours, if said syngas reservoir
becomes depleted below a predetermined threshold, introducing
fossil fuel into said burner in said combustion chamber in
sufficient quantities to: a) create sufficient hot exhaust gas to
heat said processing chamber to the required temperature for the
gasification of the organic waste therein; and b) raise the
temperature within the combustion chamber to a sufficient
temperature to oxidise therein syngas produced in and received from
said processing chamber.
23. The method according to claim 21 further comprising: passing
combustion chamber exhaust gas adjacent said heat absorbent surface
to heat said exhaust gas with said reflected sunlight; and passing
said heated gas into said process chamber so as to raise the
temperature within said processing chamber.
24. The method according to claim 16 further comprising: raising
the temperature of said syngas prior to passing it into said
combustion chamber by passing said syngas adjacent a second heat
absorbent surface; and reflecting sunlight from a second at least
one mirrored surface onto said second heat absorbent surface.
25. The method according to claim 16 further comprising: reflecting
and concentrating sunlight into said combustion chamber so as to
directly heat gasses therein.
26. The method according to claim 23 wherein reflecting and
concentrating sunlight into said combustion chamber heats the
gasses therein to a temperature at which in the presence of oxygen
they oxidize.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to International
Application No. PCT/GB2010/002178 filed on Nov. 26, 2010, which
claims priority to Great Britain Patent Application No. 0921266.3
filed on Dec. 4, 2009.
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
[0002] Not Applicable
BACKGROUND OF THE INVENTION
[0003] This invention relates to gasification systems, in
particular to gasification systems for waste.
[0004] Thermal gasification of waste products by the pyrolysis
under controlled conditions is a known process used to disseminate
waste and to produce synthetic gas (syngas) therefrom which can
then be used for the production of energy in known ways.
Accordingly energy can be recovered from organic matter within
waste.
[0005] One problem associated with such processes is that to
provide the heat for the pyrolysis to occur currently necessitates
the use of natural gas burners. The natural gas is needed to start
the system and bring the waste material up to its pyrolysis
temperature and then to provide a constant burner in which the
syngas can be combusted.
[0006] The use of natural gas in waste gasification systems removes
some of the environmental benefits of recovering energy from waste
organic matter and can somewhat offset any advantages gained.
SUMMARY OF THE INVENTION
[0007] It is the purpose of the present invention to provide an
improved system for processing organic waste.
[0008] According to a first aspect of the invention there is
provided: an apparatus for processing material such as organically
coated waste and organic materials including biomass, industrial
waste, municipal solid waste and sludge, comprising: a processing
chamber for processing said material at an elevated temperature, in
an oxygen deficient environment, to produce syngas; a combustion
chamber having at least one burner therein for combusting syngas
released by processing of said material; a conduit means between
said combustion chamber and said processing chamber for carrying
hot exhaust gasses from the combustion chamber to said processing
chamber; and at last one mirror arranged to reflect and concentrate
sunlight thereby to cause the temperature within said processing
chamber to be raised.
[0009] The invention may further include: a syngas reservoir; a
storage conduit for carrying syngas into said syngas reservoir; and
a syngas feed line for feeding syngas from said reservoir to said
combustion chamber.
[0010] The storage conduit and feed line may comprise sections of a
conduit between said processing chamber and said combustion chamber
such that the syngas reservoir is inline in said conduit.
Alternatively the reservoir can be located offline and the storage
conduit and feed line connect the reservoir to the processing
chamber and combustion chamber respectively, and may optionally
branch from the a conduit between said processing chamber and said
combustion chamber, accordingly a syngas reservoir bypass conduit
is provided for the flow of syngas from the processing chamber to
the combustion chamber without passing through the syngas
reservoir.
[0011] Preferably a first control valve to control the flow of gas
from the processing chamber into the syngas reservoir and a second
valve to control the flow of combustion chamber exhaust gas into
said processing chamber are provided.
[0012] The apparatus therefore can be configured to direct excess
syngas into a storage reservoir. This has several benefits
including the provision of a smaller combustion chamber. As, when
used for batch processing of organic waste the syngas produced is
not a steady flow but rather ramps up at the start of the process
and ramps down at the end of the process the combustion chamber
must be dimensioned to meet maximum demand. By providing a syngas
reservoir to which some of the syngas can be diverted the
consumption of syngas in the combustion chamber can be balanced
over the cycle. Further advantages of the reservoir are detailed
below.
[0013] The apparatus according may further comprise a second mirror
for reflecting sunlight onto a second heat absorbent surface
adjacent said reservoir bypass conduit do as to pre heat said
syngas passing through said bypass conduit prior to combustion in
said combustion chamber. By raising the syngas temperature prior to
its combustion in the combustion chamber less external energy is
needed during the combustion process. In a preferred arrangement
the apparatus comprises a combustion tower housing said combustion
chamber and the second heat absorbent surface comprises an external
surface of said combustion tower.
[0014] Preferably the apparatus according to any preceding claim
further comprising a fossil fuel feed line to said burner capable
of maintaining a burner pilot and/or, in the absence of sufficient
syngas and/or solar heat, providing sufficient fossil fuel for
combustion in said burner so as to, in use, create sufficient heat
for the oxidation of any syngas entering said combustion
chamber.
[0015] In one arrangement the invention further comprises at least
one external heat absorbent surface associated therewith and said
at last one mirror is arranged to reflect and concentrate sunlight
onto said heat absorbing surface, said heat absorbent surface
comprising a heat absorbent external layer and a first gas heating
conduit adjacent said heat absorbent layer for receiving combustion
chamber exhaust gas, said first gas heating conduit in fluid
communication with said processing chamber such that, in use,
combustion chamber exhaust gas passing adjacent said heat absorbent
surface is heated by said reflected sunlight and flows into said
process chamber so as to raise the temperature therein.
[0016] By heating a gas that is then carried into the processing
chamber greater control of the processing chamber environment can
be obtained as the gas flow can be increased or decreased to alter
its residency time in the first gas heating conduit so as to alter
the temperature of said gas entering said processing chamber.
[0017] Preferably there is an insulating layer adjacent said gas
first heating conduit and separated from said absorbent layer
thereby; and a bypass valve operable to either direct exhaust gas
from said combustion chamber through said first gas heating conduit
or direct exhaust gas from said combustion chamber through a gas
heating conduit bypass; wherein said gas heating conduit bypass is
separated from said heat absorbent surface by an insulating
layer.
[0018] In this manner, when sunlight is available to heat the
absorbent surface the exhaust gasses from the combustion chamber
can pass through the first gas heating conduit to become heated and
when no, or minimal, sunlight is available, for example at night
time, the hot exhaust gasses from the combustion chamber can bypass
the absorbent surface so as to avoid heat loss therefrom, thereby
ensuring the maximum amount of the heat from the combustion chamber
exhaust gas enters the processing chamber to heat it.
[0019] In a preferred embodiment the processing chamber is movable
and the heat absorbent surface forms an external surface of said
movable processing chamber.
[0020] The external surface of the first and/or second heat
absorbing surface may have a surface texture thereon so as to
increase its surface area. Although beneficial in fixed
arrangements this is especially beneficial in arrangements wherein
the processing chamber moves, e.g rotates or pivots, during
operation as it maximises, at any one time, the surface area
exposed to the reflected sunlight and reduces the need for the
mirrors to track the movement of the processing chamber. Preferably
the internal surface of the first and/or second heating conduit has
a surface texture thereon to induce turbulence in gas flow
therethrough thereby increasing heat exchange with said heat
absorbent surface.
[0021] The apparatus may further comprise a further at least one
mirror for reflecting and concentrating sunlight directly into said
combustion chamber so as to raise the temperature within said
combustion chamber.
[0022] By reflecting concentrated solar energy directly into the
combustion chamber solar energy can be directly used to raise the
syngas temperature to the required 850.degree. plus that is needed
for the combustion of syngas to reduce harmful emissions. The use
of direct solar heating for this process has the further added
advantage that it is easier to provide the required residency
period of two seconds at the elevated temperature for the syngas to
oxidize as when using the combustion of syngas with the aid of a
natural gas burner. Since the addition of the natural gas, and
oxidant to burn the natural gas, in the combustion chamber will
increase the total volume of gas to be burned inside the combustion
chamber a larger combustion chamber is needed to accommodate and
combust this extra volume. Then elimination, or at worst
minimisation, of the natural gas needed hence reduces the volume of
the combustion chamber needed to achieve the required residency
time.
[0023] By reflecting concentrated solar energy directly into the
combustion chamber solar energy can be directly used to raise the
syngas temperature to the required 850.degree. plus that is needed
for the combustion of syngas to reduce harmful emissions. The use
of direct solar heating for this process has the further added
advantage that it is easier to provide the required residency
period of two seconds at the elevated temperature for the syngas to
oxidize as when using the combustion of syngas with the aid of a
natural gas burner. Since the addition of the natural gas, and
oxidant to burn the natural gas, in the combustion chamber will
increase the total volume of gas to be burned inside the combustion
chamber a larger combustion chamber is needed to accommodate and
combust this extra volume. Then elimination, or at worst
minimisation, of the natural gas needed hence reduces the volume of
the combustion chamber needed to achieve the required residency
time.
[0024] In a preferred arrangement a conduit between said processing
chamber and said combustion chamber is arranged to direct syngas
into said combustion chamber burner. In this manner, when syngas is
available it can be burned in the burner in place of fossil fuel to
reduce the fossil fuel needed or, where solar heating is used in
the combustion chamber, the syngas can be burned in the burner when
there is insufficient solar energy available to raise the
combustion chamber to the required combustion temperature.
[0025] The apparatus preferably comprises a combustion chamber
exhaust gas outlet for supplying hot exhaust gas to a means of
converting heat to electrical energy.
[0026] According to a second aspect of the invention there is
provided a method of processing organic waste comprising: placing
said organic waste in a processing chamber; reflecting sunlight
from a plurality of mirrored surfaces onto a heat absorbent surface
so as to raise the temperature within said processing chamber so as
to cause the organic waste material to gassify and produce
synthetic gas; withdrawing said synthetic gas from said processing
chamber and passing it into a combustion chamber where its
temperature is raised to sufficient temperature to so as to destroy
any volatile organic compounds (VOC's) therein; and re-circulating
at least a portion of the combustion chamber exhaust gas back into
said processing chamber.
[0027] Preferably the method includes: diverting at least a portion
of said withdrawn syngas into a storage reservoir; and passing the
remainder of the syngas into a combustion chamber. The method may
also comprise feeding syngas from said storage reservoir to said
combustion chamber. Preferably heat from said recycled combustion
chamber exhaust gas makes up any shortfall in thermal input from
reflected sunlight.
[0028] In this method a portion of the syngas created during
sunlight processing cycles is diverted and stored for use as a fuel
during the night time (or periods of low solar energy) processing
cycle, i.e. the solar energy is converted into chemical energy and
is stored in the form of a syngas for use during night time
processing cycles where it is converted from chemical energy to
thermal energy to drive the processing of the organic waste. In
this manner the size of the combustion chamber can be balanced to
the combined night time/daytime processing cycle needs
[0029] The temperature of the syngas in the combustion chamber may
be raised in the presence of oxygen to a sufficient temperature to
oxidise said synthetic gas.
[0030] The method may comprising introducing fossil fuel into a
burner within the combustion chamber to produce a flow of hot
combustion chamber exhaust gas sufficient to compensate for any
shortfall in reflected sunlight used for heating said processing
chamber. Preferably the method also comprises: controlling the flow
of syngas diverted into the reservoir; controlling the flow of
syngas from the reservoir into the combustion chamber; and
controlling the flow of combustion chamber exhaust gas into the
processing chamber; so as to maximise the solar energy used by the
process and minimise the fossil fuel burnt in the burner.
[0031] Benefits of the method reflect those described in relation
to the apparatus
[0032] The method may comprise: during sunlight hours, following
the method as described above and; during night time hours,
introducing syngas from said syngas reservoir into a burner within
said combustion chamber so as to: a) create sufficient hot exhaust
gas to heat said processing chamber to the required temperature for
the gasification of the organic waste therein; and b) raise the
temperature within the combustion chamber to a sufficient
temperature to destroy any VOC's therein and/or oxidise therein
syngas produced in and received from said processing chamber.
[0033] In this manner solar energy is used when available to
provide heating for the process chamber and optionally pre-heating
of the syngas prior to combustion and heating the syngas in the
combustion chamber and, when not available, i.e. during a night
time processing cycle using fossil fuels to provide the required
thermal input to the system. It will be appreciated that the night
time cycle may be run at any time when there is insufficient solar
energy to provide the required heat and is not restricted to use
during night time hours.
[0034] During said night time hours the method may further
comprise: if said syngas reservoir becomes depleted below a
predetermined threshold, introducing fossil fuel into said burner
in said combustion chamber in sufficient quantities to: a) create
sufficient hot exhaust gas to heat said processing chamber to the
required temperature for the gasification of the organic waste
therein; and b) raise the temperature within the combustion chamber
to a sufficient temperature to destroy and VOC's therein oxidise
therein syngas produced in and received from said processing
chamber.
[0035] During Daylight hours the method may further comprise:
passing combustion chamber exhaust gas adjacent said heat absorbent
surface to heat said exhaust gas with said reflected sunlight; and
passing said heated gas into said process chamber so as to raise
the temperature within said processing chamber.
[0036] The method may further comprise: raising the temperature of
said syngas prior to passing it into said combustion chamber by
passing said syngas adjacent a second heat absorbent surface; and
reflecting sunlight from a second at least one mirrored surface
onto said second heat absorbent surface.
[0037] The method may comprise reflecting and concentrating
sunlight into said combustion chamber so as to directly heat gasses
therein. Reflecting and concentrating sunlight into said combustion
chamber may heat the gasses therein to a temperature at which in
the presence of oxygen they oxidise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIGS. 1 and 2 show schematic diagrams of processes in
accordance with the invention;
[0039] FIG. 3 shows an apparatus for performing the process of FIG.
2;
[0040] FIG. 4 shows a further schematic diagram of a process in
accordance with the invention;
[0041] FIG. 5 shows an apparatus for performing the process of FIG.
4;
[0042] FIG. 6 shows a diagram of the heat exchange surfaces of the
apparatus of FIGS. 3 and 5;
[0043] FIG. 7 shows a further schematic diagram of a process in
accordance with the invention; and
[0044] FIG. 8 shows an apparatus for performing the process of FIG.
7.
DETAILED DESCRIPTION OF THE INVENTION
[0045] Referring to FIG. 1 a diagram of an apparatus for processing
organic waste is shown. The apparatus comprises a processing
chamber 2 in which waste material containing organic substances is
thermally treated. The processing chamber 2 may be of a known type
which may include a through-process chamber in which a stream of
waste material containing organic substances is continuously fed
into one end and the char removed from the other or, alternatively,
it may be used in a batch processing method wherein waste material
is loaded in to the processing chamber 2, is left therein for a
period of time, and then is removed from the processing chamber 2.
The processing chamber 2 is preferably moved during use so as to
expose all surfaces of the waste material therein such that they
may be processed. Movement may include one or more of rotating or
tipping the processing chamber.
[0046] A combustion chamber 4 is connected to an outlet of the
processing chamber 2 by conduit 6 which has a valve 8 therein.
Conduit 6 carries syngas created by the processing of the organic
waste material. The valve 8 may control one or both of the flow of
syngas into the combustion chamber 4 and the back pressure within
the processing chamber 2. The combustion chamber 4 contains a
burner, not shown, in which the syngas is combusted.
[0047] Oxygen, or an Oxygen containing gas, for example compressed
air, is injected into the combustion chamber 4 from supply 10.
Sufficient Oxygen, or Oxygen containing gas, is added to the
combustion chamber to enable the full oxidation of Volatile Organic
Compounds (VOC's) in the syngas combusting therein, although it
will be appreciated that oxygen is not required to destroy the
VOC's which may alternatively be heated in the absence of oxygen so
as to cause them to break down. The combustion chamber 4 is
maintained at a temperature in excess of 850.degree. C. This
temperature may be achieved either by the combustion of the syngas
itself or alternatively, or in addition, by the combustion of a
fossil fuel, in particular natural gas, which is supplied from
source 12 through conduit 14 and is controlled by means of valve
16. The burner may comprise an afterburner arrangement into which
the syngas is introduced.
[0048] An outlet conduit 18 withdraws a proportion of the hot
combustion gasses from the combustion chamber 4 and passes these
through a first gas heating conduit 20 and from there into the
processing chamber 2. The flow of hot exhaust gasses from the
combustion chamber 4 into the first gas heating conduit is
controlled by means of valve 22.
[0049] A solar reflector means 24 reflects sunlight onto an
absorbent surface 26 of the first gas heating conduit 20.
[0050] The solar reflector means 24 comprises a mirror which
focuses and concentrates the sunlight. The mirror may be any one of
a number of known high temperature solar collectors for example it
may include one or more parabolic troughs, parabolic dishes,
Fresnel Reflectors or Linear Fresnel Reflectors.
[0051] The concentrated sunlight imparts thermal energy into the
gas passing through the first gas heating conduit 20 thereby
increasing its temperature before it passes into the processing
chamber 2. The thermally heated exhaust gasses impart heat into the
organic waste material in the processing chamber 2 causing it to
pyrolysis and release synthetic gas.
[0052] The amount of natural gas from source 12 that is combusted
in the combustion chamber 4 will vary throughout the process cycle
and will reduce as the amount of syngas produce from the combustion
chamber 4 increases.
[0053] A first gas heating conduit bypass 28 having a valve 30
therein allows the hot exhaust gasses taken from the combustion
chamber 4 to bypass the first gas heating conduit 20. This bypass
would be used in times of low solar energy whereby passing the hot
combustion chamber exhaust gas through the first gas heating
conduit 20 would result in a heat loss from the absorbent surface
thereof. In such conditions, bypassing the gas heating conduit 20
results in hotter gasses being inputted to the processing chamber
2.
[0054] When the bypass 28 is in use it is anticipated that a higher
volume of natural gas would be burned within the combustion chamber
4 such that a larger volume of hot exhaust gasses are input into
the combustion chamber 4 to compensate for their lower temperature
due to the lack of additional solar thermal heating.
[0055] Combustion chamber 4 has an outlet conduit 32 which takes
the hot exhaust gasses not re-circulated back into the processing
chamber 2 to an energy generation plant. The hot exhaust gasses
may, for example, be used to create steam to power a steam
turbine.
[0056] The inclusion of the solar reflector 24 into the process
reduces the volume of natural gas required to maintain the process
thereby reducing the environmental impact associated with the use
of fossil fuels. The flow rates of gas through the various valves
is controlled so as to maintain a predetermined temperature and
pressure within the processing chamber 2 in order to thermally
decompose all the organic matter therein without melting the
majority of the metal within the waste. However, metals with very
low melting points, for example lead, may be melted within the
process.
[0057] Referring to FIG. 2 a similar system to that of FIG. 1 is
shown. In addition, instead of the syngas leaving the processing
chamber 2 via conduit 6 being fed directly into the combustion
chamber 4, it first passes through a second heating conduit 34
which has a second heat absorbent surface 36. One or more solar
reflectors 24 as described above reflect sunlight onto the heat
absorbent surface of the second heating conduit 34 so as to heat
the syngas from the processing chamber 2 prior to its introduction
to the combustion chamber 4.
[0058] By heating the syngas to close to its combustion temperature
prior to adding it into the combustion chamber 4 the amount of
energy needed in the combustion chamber 4 to combust it at a
temperature in excess of 850.degree. C. is thereby reduced, further
improving the efficiency of the system.
[0059] While it is noted that the total amount of energy required
to thermally decompose the organic material and to combust the
syngas produced therefrom does not change, the source of a
proportion of this energy, in the present invention, is provided by
the solar reflectors and therefore a reduced reliance on fossil
fuels from supply 12 is achieved.
[0060] Referring to FIG. 3 a diagram of an apparatus in accordance
with the present invention is shown. The apparatus comprises a
processing chamber 2 which is pivotally mounted on to processing
chamber mounts 40 such that, in use, it can be pivoted thereon so
as to cause any organic waste materials therein to pass from one
side of the processing chamber 2 to the other. The processing
chamber may be of the type described in published patent
application WO 2006/100512.
[0061] The conduit 6 connects an outlet of the processing chamber 2
to the combustion chamber 4 and an outlet conduit 18 connects the
combustion tower 4 to the processing chamber 2.
[0062] A plurality of solar reflectors 24 reflect light from the
sun 42 onto a heat absorbing surface 20 of the processing chamber
and a heat absorbing surface 34 of the combustion chamber 4.
[0063] The solar reflectors are shown as parabolic mirrors which
may be positioned via positioning means 44 to track the sun so as
to reflect solar energy onto the heat absorbing surfaces 20, 34.
The combustion chamber 34 has a natural gas inlet and an Oxygen
inlet, not shown.
[0064] The outlet of the combustion chamber 4 has a valve block 46
which controls the proportion of the hot exhaust gasses from the
combustion chamber 34 which are directed through conduit 18 to the
processing chamber and through conduit 32 to a power generation
means. In use the apparatus of FIG. 3 are operated as described
with reference to the system of FIG. 2. Further details of the heat
absorbent panels 20, 34 are described below with reference to FIG.
6.
[0065] Referring to FIGS. 4 and 5 a schematic diagram and apparatus
of a further embodiment of the invention are shown. The system is
substantially similar to that shown in FIGS. 2 and 3 except in so
far as additional solar reflectors 48 are provided to reflect and
concentrate sunlight from the sun 42 directly into the combustion
chamber 4 so as to raise the temperature therein. The combustion
chamber 4 comprises at least one substantially transparent section
50 through which the concentrated sunlight reflected by solar
reflectors 48 can pass to enter the combustion chamber 4. In use
the syngas exits the processing chamber 2 via conduit 6 and its
flow is controlled by valve 8. The syngas then passes through the
heat exchange panels 34 where it is heated by sunlight reflected by
parabolic dishes 24 which reflect and concentrate sunlight onto the
heat absorbent surface 36 of the panels 34. The preheated syngas
then enters the combustion chamber 4 where its temperature is
increased to a combustion temperature in excess of 850.degree. C.
by concentrated sunlight reflected directly into the combustion
chamber 4 by parabolic mirrors 48. A supply of Oxygen, or Oxygen
containing gas 10, is supplied to the combustion chamber with the
syngas in sufficient quantities for full oxidation of Volatile
Organic Compounds (VOC's) within the syngas to occur within the
combustion chamber.
[0066] The combustion chamber 4 is also supplied with natural gas
from a supply 12 through conduit 14, the supply being controlled by
valve 16. At times when there is insufficient sunlight to power the
combustion process within the combustion chamber 4 natural gas can
be burnt in the combustion chamber 4 so as to increase the
temperature therein. The remainder of the system operates
substantially as described with reference to FIGS. 2 and 3.
[0067] The system and apparatus shown in FIGS. 4 and 5 maximise the
use of available solar energy and can drastically reduce the amount
of fossil fuels that are needed to be consumed to process organic
waste material within the processing chamber 2. Furthermore, the
excess exhaust gasses from the combustion chamber 4 are used to
power an electricity generating means resulting in a waste
processing apparatus that transfers solar thermal energy into
chemical potential energy within the processing chamber by
processing organic waste and then combusts the chemical potential
energy within combustion chamber 4 to produce thermal and kinetic
energy in exhaust gasses passing through conduit 32 which can then
be transferred into electrical potential energy.
[0068] Accordingly, not only is waste material safely processed but
as a by-product of the waste processing cycle electrical energy can
be produced with the minimum reliance upon fossil fuels.
[0069] It will be appreciated that the solar energy can only be
used to power the processing of the waste materials during hours of
sufficient sunlight. Accordingly, in a second mode of operation the
system shown in any one of diagrams 1,2 and 4 can, during hours
where there is not sufficient sunlight to provide the required
thermal energy input, function solely on the thermal energy
provided by the combustion or natural gas from source 12 within the
combustion chamber.
[0070] Referring to FIG. 6 a schematic cross-section of heating
panels 20, 34 of the invention is shown. The panels are shown in
two modes of operation, a night time mode of operation and a
daytime mode of operation. During the daytime mode of operation
exhaust gasses from the combustion chamber 4 enter the heating
panel 52 via conduit 18 and pass through a first gas heating
conduit 20 which runs adjacent the absorbent surface 26. Although
not shown the heat absorbing surface 26 may have a corrugated or
otherwise adapted external surface that increases its surface area.
The use of an externally textured surface, for example a corrugated
surface is especially beneficial when used with moving or rotating
processing chambers as it ensures that there are always parts of
the surface area which are perpendicular to the light reflected
from the solar reflectors thereby enabling maximum heat
absorbance.
[0071] The internal surface 54 of the conduit 20 may contain a
surface texture that encourages the turbulent flow of exhaust
gasses through the conduit 20. By inducing turbulent flow over the
internal surface through which heat is absorbed, maximum heat
transfer into the flowing gasses is obtained. The panel 52 may
comprise a large flat conduit 20 or alternatively may comprise a
plurality of smaller conduits arranged adjacent to one another
substantially over the entire heat absorbent surface 26 of the
panel 52.
[0072] After passing through the conduit 20 the heated exhaust
gasses exit the panel 52 via outlet 56 and may thereafter directly
enter the processing chamber 2. In some arrangements the outlets
surface 58 of the panel 52 may comprise an internal surface of the
processing chamber 2.
[0073] During night time use valve 30 is opened and the exhaust
gasses from the combustion chamber 4 flow therethrough. The conduit
28 through which the exhaust gasses flow bypasses the heat exchange
surface 26 of the panel 52 and is separated therefrom via a layer
of insulation 60. During non-sunlight, or low sunlight hours the
heat absorbent surface 26 will be at a lower temperature than the
exhaust gasses entering the conduit 28 and therefore, without the
thermal separation of the hot exhaust gasses from the heat
absorbent surface 26 heat would be lost through the surface 26.
Having bypassed the first heating conduit 20 the hot exhaust gasses
pass directly from the combustion chamber 4 through outlets 56 into
the processing chamber 2. Accordingly a heat absorbing panel may be
provided that can be used to receive heat into gas passing
therethrough during the hours in which solar energy is available
and may thermally insulate exhaust gasses from combustion chamber 4
from the external environment when insufficient solar energy is
available to affect heat.
[0074] Referring to FIGS. 7 and 8 a further embodiment of the
invention is shown. The apparatus is substantially as described in
relation to FIGS. 4 and 5 except in so far as a storage conduit 62
with a control valve 64 therein branches off the conduit 6 which
carries syngas from the processing chamber 2 to the combustion
chamber 4 via heat exchange conduit 34. The storage conduit 62
feeds into a syngas reservoir in which syngas can be stored. A
syngas feed line 68 connects the syngas reservoir 66 to the
combustion chamber 4. The syngas feed line 68 has a valve 70
therein for controlling the feed of syngas from the syngas
reservoir 66 into the combustion chamber 4. The syngas feed line 68
may feed syngas from the reservoir 66 back into the conduit 6 so
that it can travel therein to the combustion chamber 4 or,
alternatively, the syngas feed line 68 may lead directly into the
combustion chamber 4 without reconnecting with conduit 6.
[0075] In arrangements where the syngas feed line 68 leads back
into conduit 6, a valve, not shown, is positioned in conduit 6
between the junctions with the storage conduit 62 and the syngas
feed line 68.
[0076] In use, syngas exiting the processing chamber 2 via conduit
6 may be directed such that a proportion of the syngas enters the
combustion chamber for combustion therein and a proportion of the
syngas produced is withdrawn from the conduit 6 and is stored in
the syngas reservoir 66 via storage conduit 62.
[0077] As the processing chamber 2 is, in a preferred arrangement,
a batch processing chamber the output level of syngas varies in
relation to the treatment cycle. During the initial period of
treatment a low production of syngas is achieved which increases to
a maximum production rate of syngas toward the middle of the cycle
and, towards the end of the cycle the syngas production rate
decreases. The syngas reservoir 66 may act as a buffer to withdraw
syngas from the system during times of maximum production and to
return syngas to the system during times of lower production so as
to even the flow of syngas to the combustion chamber 4 throughout
the processing cycle.
[0078] Alternatively, or in addition to evening the flow of syngas
to the combustion chamber 4, syngas drawn from the syngas reservoir
66 may be combusted at a higher or lower rate within a combustion
chamber 4 to vary the temperature and flow rate of exhaust gas
passing therefrom into the processing chamber 2. In this manner,
during the initial stages of the cycle where the organic waste
material within the processing chamber 2 is at a relatively low
temperature heat can be quickly supplied to the processing chamber
to bring the temperature of the organic containing waste material
up to its processing temperature. This heating is provided in two
manners. Firstly by the rate of syngas and/or natural gas burnt
within the combustion chamber and secondly by the amount of solar
energy that can be reflected from the solar reflectors 24 on to the
heating conduits 20 to increase the temperature of the exhaust
gasses from combustion chamber 4. Once the processing chamber 2 is
at its processing temperature the volume of syngas from the
reservoir 66 that is being combusted in the combustion chamber 4
can be decreased such that sufficient heat is maintained within the
processing chamber 2 for the process to continue.
[0079] Towards the end of the processing cycle, as the syngas
production rate within the processing chamber 2 decreases, then
additional syngas may be added into the combustion chamber 4 from
the syngas reservoir 66 so as to maintain a high enough temperature
and flow of exhaust gasses to maintain the production of
electricity from the electricity producing means powered by the
exhaust gasses supplied by conduit 32. It is anticipated that
during the middle period of the processing cycle, when maximum
syngas is being produced from the processing chamber, that
sufficient syngas will be produced to both power the combustion
chamber and to allow for a proportion of the produced syngas to be
withdrawn via storage conduit 62 to replenish syngas levels within
the reservoir 66.
[0080] In a preferred method of operation the processing chamber 2
produces sufficient excess syngas during hours of sunlight such
that a sufficient reserve can be stored within the reservoir 66
such that, at night time, when the solar energy is not available to
power the system that a large portion, if not all, of the heating
requirement of the combustion chamber 4 can be provided by the
combustion therein of syngas from the syngas reservoir 66, in
combination with the syngas produced by the processing chamber 2.
In this manner, the system can be run during both the night time
and daytime with a minimal need for the additional use of fossil
fuels. Effectively, the syngas within the reservoir 66 is used to
store the solar energy utilised within the process during sunlight
hours for conversion back into thermal energy during night time
hours.
[0081] As will be appreciated the skilled person, various standard
operating conditions are associated with the combustion of syngas,
for example the temperature and residence time at which it is
combusted in order to fully oxidise any VOCs therein and various
exhaust gas treatment operations would be used in connection with
the method and apparatus as described herein.
[0082] It will further be appreciated by the skilled person that
various combinations of the features of the embodiments may be
utilised in combination with one another whilst remaining within
the scope of the invention. For example, the syngas reservoir 66
described in relation to FIGS. 7 and 8 may be used with the system
as described in FIGS. 1 to 3.
* * * * *