U.S. patent application number 11/182091 was filed with the patent office on 2006-03-09 for energy reclaiming process.
Invention is credited to Donald Helleur.
Application Number | 20060048920 11/182091 |
Document ID | / |
Family ID | 32873353 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060048920 |
Kind Code |
A1 |
Helleur; Donald |
March 9, 2006 |
Energy reclaiming process
Abstract
The invention relates to gaseous sources from which to reclaim
energy using a pressurized direct contact heat exchanger, and in
particular, those sources containing a condensable vapor. While the
main applications involve water as the condensable vapor, the
process is applicable to other vapors, e.g. those in the chemical
and petroleum industries where various organic solvents are used.
The reclaimed energy can be in the form of a hot fluid, process
steam and or electricity. It has particular application to: a
pressure combustion furnace and the DOE's Clean Coal Technology;
the combustion of wet fuels (biomass, peat); pulp & paper;
electrolysis of alumina or water; detoxidation, thermal
depolymerization, enhanced oil recovery (and sequestering of carbon
dioxide), phytotechnology,
Inventors: |
Helleur; Donald;
(St-Lambert, CA) |
Correspondence
Address: |
Eric Fincham
316 Knowlton Road
Lac Brome
QC
J0E 1V0
CA
|
Family ID: |
32873353 |
Appl. No.: |
11/182091 |
Filed: |
July 15, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10780199 |
Jul 9, 2004 |
|
|
|
11182091 |
Jul 15, 2005 |
|
|
|
Current U.S.
Class: |
165/108 |
Current CPC
Class: |
F01K 3/185 20130101 |
Class at
Publication: |
165/108 |
International
Class: |
F28F 13/06 20060101
F28F013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2003 |
CA |
2,419,774 |
Claims
1. A process for continuously reclaiming any additional energy
residing in hot pressurized non-condensable gases containing a
condensable vapor, produced when processing material, and
converting said energy into a more useful form, comprising the
steps of: a) providing a source from which to reclaim said
additional energy from said gases continuously being produced
within and or emanating from the source, and if necessary,
converting the source to a higher pressure, so that hot pressurized
gases are produced; b) continuously bringing the pressurized gases
into intimate contact with a cooler liquid, in a pressurized
direct-contact heat exchanger, a vertical vessel consisting of
various sections, including a hot well, where the gases will enter
at the bottom, flow counter-current to a flow of the cooler liquid
and where any condensable vapor will condense and the gases will
become drier, and leave at the top where the cooler liquid enters,
said exchanger being divided into several areas; a first area being
where any evaporative and heating property of the gases could be
used to dry materials, a second area where part of the condensing
and heating property of any vapor in the gas will be utilized to
heat the cooler liquid to the highest temperature it could have
when in equilibrium with the gases at the given pressure and
thereby cool the gases as well as allowing heated liquid and
condensed vapor to collect in the hot well within the area while
still maintaining the highest possible hot well temperature, and
continuously removing liquid from the hot well as reclaimed energy
for further use or alternatively, continuously removing the liquid
in the hot well and sending it to a flash chamber to produce vapor
with the cooler flashed liquor reintroduced into said second area
to cool further gases; and a third area wherein the gas and liquid
will continue to progressively exchange heat content and supply
heated liquid to the hot well, until the gas approaches the
temperature of the cool liquid entering at the top; c) continuously
replenishing the cool liquid entering at the top of the exchanger
d) continuously removing the cooled gases from the top of the
exchanger as reclaimed energy for further use.
2. The process of claim I comprising the steps of continuously
removing heated liquid from the hot well and flash evaporating it
in a flash chamber at a pressure lower than the pressure
corresponding to the equilibrium or hot well temperature to thereby
(1) convert some of the water in the liquid into steam and (2) cool
the liquid to a temperature corresponding to the pressure of the
flashed steam and allow it to collect in a sump in the flash
chamber, continuously removing cooled liquid from the flash chamber
and re-introducing it to the direct contact heat exchange section;
at a point in the second area where the gas in the area is at about
the same temperature as that of the liquid in the sump, so as to
cool further gases, and where the gas and cooled liquid will
progressively exchange heat content, until the gas as it cools
approaches the temperature of the liquid from the flash chamber;
continuously removing the flashed steam from the flash chamber for
further use;
3. The process of claim 1 wherein in step (a) the source is a known
process, but is now adapted to perform at a substantially elevated
pressure and, if feasible, higher temperature.
4. The process of claim 1 wherein the gases, from the said source
are turbo-compressed to the desired pressure, with the temperature
being increased by the compression.
5. The process of claim 1 wherein said condensable vapor is water
and said further use of said water from the hot well comprises
sending the water through a pressurized indirect heat exchanger to
convert the water into high temperature high pressure steam for use
in a process or to generate electricity using high efficiency steam
turbines.
6. The process of claim 2 wherein said further use of the flashed
steam involves its use as process steam or in the production of
electricity using steam turbines connected to a generator and said
further use of the cooled gases in step (d) involves its use in the
production of electricity using a turbine expander connected to a
generator.
7. The process of claim 2 wherein said further use of the flashed
steam from the flash evaporator involves sending said steam through
a pressurized indirect heat exchanger to superheat it to a higher
temperature so as to generate electricity using higher efficiency
steam turbines.
8. The process of claim 1, wherein the steps of collecting other
non-condensable gases containing water vapor and turbo-compressing
them to a pressure sufficient to operate the pressurized direct
contact heat exchanger and to introduce them into the source
process prior to step (a).
9. The process of claim 2 wherein the liquid from the hot well is
heated indirectly to a higher temperature to thereby increase the
steam pressure in the flash evaporator
10. The process of claims 1, wherein the pressurized gases are
further heated prior to going to a direct contact heat
exchanger
11. The process of claim 1 wherein in step (g), the cool
pressurized gases are heated prior to passing them through a gas
turbine expander.
12. The process of claims 1 wherein prior to step (b) and after
removing any particulates, the hot gases are passed through a gas
turbine connected to a generator to produce electricity.
13. The process of claim 1 wherein oxygen required is supplied from
a source under a pressure greater than that of the source supplying
the hot pressurized gases.
14. The process of claim 13 wherein the oxygen required is supplied
from the electrolysis of water or steam under a pressure greater
than that of the source supplying the hot pressurized gases.
15. The process of claim 2 wherein the cool liquid entering at the
top contains dissolved and/or suspended materials, such that the
liquid can be concentrated by the recycling of the liquid through
the pressurized direct contact exchanger and flash evaporator.
16. The process of claim 1 wherein the area below the hot well is
used to dry materials.
17. The process of claim 2 wherein undesirable solids and/or gases
are present in the hot gases and are removed in the heat exchanger
by maintaining the circulating liquid alkaline for acidic gases and
acidic for alkaline gases, the substances so formed then are
concentrated and removed from the flash evaporator.
18. The process of claim 2 wherein the non-condensable gas content
is in the low range and the pressurized hot gases are sent to a
primary pressurized direct contact heat exchanger and processed
through the first and second areas of step (b), said hot gases are
then removed from the exchanger at a temperature close to that of
the temperature of the flashed liquid in the evaporator and fed to
a suction side of a pump removing the flashed liquid from the flash
evaporator, which is capable of pressurizing this removed mixture
to a pressure which will condense most of the steam in this removed
gas mixture, the pressurized liquid and gas mixture is then sent to
a secondary pressurized direct contact heat exchanger where the
liquid and gases separate at a temperature corresponding to that of
the pump pressure, the separated liquid in the chamber is sent to
the top of the primary heat exchanger at a point where the removed
gases exit, the heat content of the separated gases in the
secondary heat exchanger, containing a low amount of steam, can
then be recovered as desired.
19. The process of claim 2 wherein the steam from the flash
evaporator, is passed through a reboiler.
20. The process of claim 1 wherein the source process is a
combustion process carried out underground under pressure, where
there is combustible material, and where the combustion is
supported by a pressurized gas containing oxygen and controlled by
water piped to the combustion site from above ground and where the
pressurized hot gases would be piped to a pressurized direct
contact heat exchanger above ground and processed utilizing any of
the other embodiments that will give the desired result
21. The process of claim 1 wherein the source process is carried
out underground under pressure, where there is combustible
material, and where the process is activated by high pressure
steam, preferably superheated steam, which allows the material to
flow to a pressurized direct contact heat exchanger above ground
and processed as for any of the other embodiments.
22. The process of claim 2 wherein, a primary flash evaporator
produces steam at the highest possible pressure level, the flashed
liquid from the primary is then flashed in a secondary flash
evaporator to produce steam at a lower level, if desired this
sequence could be continued and, at any stage the flashed liquid
could be used to indirectly heat other media, with the final cooler
liquid returned to the pressurized direct contact heat exchanger
for reheating.
23. The process of claim 1 wherein the cooled gases from the top of
zone are cooled further, in order to reclaim further latent heat,
by bringing them into indirect contact with the cooler gases
between expansion stages in the gas expander.
24. The process of claim 15, wherein the electricity produced is
one of direct current which is then fed directly to the
electrolysis of water.
25. The process of claim 2 wherein the material to be processed at
the source is after the appropriate comminution is suspended in
water and pumped to the source, where the wetted material is
processed and the excess water used to cool the gases and any in
the material in the water concentrated in the flash evaporator.
26. The process of claim 1 wherein high pressure steam is generated
within the source process, by a pressurized indirect contact heat
exchanger, and used as desired, and while the amount of energy
extracted by the pressurized indirect heat exchanger will vary
depending on the application, a maximum amount would require that
enough energy be left in the hot gases in order to operate the
pressurized direct contact heat exchanger so that the latent energy
of the water vapor in the gases can be extracted in the flash
evaporator.
27. The process of claim 1 wherein prior to going to the
pressurized indirect heat exchanger and after removing any
particulates, the hot gases are passed through a gas turbine
connected to a generator to produce electricity, and while the
amount of energy extracted by the gas turbine will vary depending
on the application, a maximum amount would require that enough
energy be left in the hot gases in order to operate the pressurized
direct contact heat exchanger so that the latent energy of the
water vapor in the gases can be extracted in the flash
evaporator.
28. The process of claim 1 wherein in step (d) if the cooled
pressurized gasses contain carbon dioxide and/or nitrogen, said
gases are used to sweep gassy coal beds to release the methane
contained therein and trap the carbon dioxide and/or nitrogen
thereby producing gases containing pressurized methane.
29. The process of claim 1 wherein in step (d) if the cooled
pressurized gasses contain carbon dioxide, said gases are used to
accelerate biomass growth in an enclosed area.
30. The process of claim 29 wherein by creating a second enclosed
area below said enclosed area, the oxygen and water vapor generated
within the first enclosed area, being lighter than the carbon
dioxide, will accumulate and can be removed and pressurized and
used in the pressurized direct contact heat exchanger to generate
more carbon dioxide which can be recycled to the first enclosed
area.
31. The process of claim 1 wherein the source involves an
electrochemical process under pressure.
32. The process of claim 31 wherein said electrochemical process
involves the electrolysis of water and cool dry oxygen and cool dry
hydrogen are produced
33. The process of claim 32 wherein the source involves the
electrolysis of steam under pressure using the Cerametec process
and cool dry oxygen and cool dry hydrogen are produced.
34. The process of claim 33 wherein said electrolysis is combined
with a pressure combustion furnace so that the hot well water can
be sent to said furnace to produce high temperature pressurized
steam for the Cerametec process.
35. The process of claim 32 where said electrochemical process is
the electrolysis of water or steam, and where said electrolysis
produces two streams of gas which results in (a) pressurized oxygen
containing water vapor, which is used directly in any other
pressurized process requiring oxygen and (b) pressurized hydrogen
containing a minimum of water vapor.
36. The process of claim 35 where the other pressurized process
requiring oxygen is a combustion process.
37. The process of claim 32 where an alternating current is used to
(a) heat the make-up water to electrolytic cell up to the operating
temperature of the cell and (b) heat the electrolyte at start-up,
and (c) help keep an even temperature in the cell,
38. The process of claim 32 wherein the electrochemical process
involves the electrolysis of alumina.
39. The process of claim 38 wherein the hot non condensable gas is
mainly carbon monoxide and the carbon monoxide and carbon dioxide
can be separated using a solution chamber and a gas separator and
the energy of the carbon monoxide enriched gas recovered by
combustion in a heat recovery steam generator and the steam
generated used for process or to produce electricity using steam
turbines.
40. The process of claim 1 wherein various substances can be
processed in a reactor under high pressure.
41. The process of claim 40 wherein and any gas produced in the
reactor can be separated from the aqueous medium in a special
separator chamber,
42. The process of claim 41 wherein the process is one of wet
oxidation.
43. The process of claim 42 wherein if the gas is pressurized
carbon dioxide, it could be used for oil enhancement, or where
after de-pressurizing in the expander, it can be used in the
production of biofuel.
44. The process of claim 40 wherein the reaction is one of thermal
depolymerization.
45. The process of claim 44 wherein the thermal depolymerization
can involve more than one reactor.
46. The process of claim 2 wherein the source involves a
pressurized fuel cell and if only hydrogen & oxygen are used,
any residual hydrogen & oxygen could also be recycled back to
the fuel cells, rather than put through a turbine expander.
47. The process of claim 1 wherein the pressure is at a low level,
but higher than is presently used, and a rotary blower is used to
bring the gases to the desired pressure.
48. The process of claim 2 wherein the pressure is at a low level,
but higher than is presently used, and a rotary blower is used to
bring the gases to the desired pressure and the condensable vapor
is water.
49. The process of claim 47 wherein the hot water can be sent to a
boiler to produce very high pressure, high temperature steam for
process or for generating electricity using highly efficient steam
turbines.
50. The process of claim 1 wherein boiling liquids, extracting
materials with steam, drying materials stripping, etc are processes
that supply the pressurized gases.
51. The process of claim 1 wherein the source is a pressure
combustion furnace, which is being fed air and a water paste of
coal and limestone, which produces hot gases, which are cleaned and
sent to a gas turbine to generate electricity, with the pressure of
the gases leaving the turbine high enough so as to reclaim the
latent heat in the gases in the pressurized direct contact heat
exchanger, then they are sent to a pressurized indirect contact
heat exchanger, and then to the pressurized direct contact heat
exchanger to create hot well water, which is used to generate high
pressure high temperature steam in the pressurized indirect contact
heat exchanger (a boiler), said steam being used to generate
electricity using steam turbines.
52. The process of claim 1 wherein the source is gasifer which is
being fed oxygen or air and a water paste of coal and limestone,
which produces hot gases, which are cleaned and sent to a pressure
combustion furnace, which is being fed air, to produce hot gases,
which are cleaned and sent to gas turbine to generate electricity,
such that the pressure of the gases leaving the turbine should be
high enough so as to reclaim the latent heat in the gases in the
heat exchanger, then they are sent to the pressurized direct
contact heat exchanger to create hot well water, which is used to
generate high pressure high temperature steam in a boiler within
the pressure combustion furnace, said steam being used to generate
electricity using steam turbines.
53. The process of claim 1 wherein the source of the gases is a oil
well reclaiming bitumen from the oil sands.
54. The process of claim 19 wherein the source is an impulse drying
process.
Description
[0001] The present application is a continuation-in-part of
application Ser. No. 10/780,199 filed Jul. 9, 2004.
FIELD OF THE INVENTION
[0002] The invention relates to gaseous sources from which to
reclaim energy using a pressurized direct contact heat exchanger.
In particular, those sources containing a condensable vapor While
the main applications involve water as the condensable vapor, the
process is applicable to other vapors, e.g. those in the chemical
and petroleum industries where various organic solvents are
used.
[0003] The reclaimed energy-can be in the form of a hot fluid,
process steam and/or electricity. It has particular application to:
a pressure combustion furnace and to DOE's Clean Coal Technology;
the combustion of wet fuels (biomass, peat); pulp &paper;
electrolysis of alumina or water; wet oxidation, thermal
depolymerization, enhanced oil recovery (and sequestering of carbon
dioxide), phytotechnology,
[0004] If the source is not already under pressure, the invention
converts it to a higher pressure.
DESCRIPTION OF THE PRIOR ART
[0005] Present processes release large volumes of gas into the
atmosphere, resulting in a loss of energy, especially the latent
heat of any condensable vapor, resulting in low thermal
efficiencies.
[0006] While various direct contact heat exchange systems have been
proposed to recover this energy, all of them operate at close to
atmospheric pressure and recover mainly the sensible heat and the
temperature of the recovered fluids are near or below the boiling
point of the fluid at the recovered pressure.
[0007] U.S. Pat. Nos. 3,920,505 and 4,079,585 are previous
disclosures relating to the recovery of waste sulfite liquors using
a pressurized heat exchange process.
SUMMARY OF THE INVENTION
[0008] The basis embodiment of the invention comprises:
[0009] (a) providing a source from which to reclaim any additional
energy from pressurized gases, continuously being produced within
and/or emanating from the source, and if necessary, converting the
source to a higher pressure, so that pressurized gases are
produced;
[0010] (b) continuously bringing the pressurized gases into
intimate contact with a cooler liquid, in a pressurized
direct-contact heat exchanger, a vertical vessel consisting of
various sections, including a hot well, where the gases will enter
at the bottom, flow counter-current to a flow of the cooler liquid
and where any condensable vapor will condense and the gases will
become drier, and leave at the top where the cooler liquid enters,
said exchanger being capable of being divided into several
areas/sections; the first area being where any evaporative and
heating property of the gases could be used to dry materials, a
second area where part of the condensing and heating property of
any vapor in the gas will be utilized to heat the cooler liquid to
the highest temperature it could have when in equilibrium with the
gases at the given pressure, and thereby cool the gases; as well as
allow heated liquid and condensed vapor to collect in the hot well
within the area, while still maintaining the highest possible hot
well temperature, and continuously removing liquid from the hot
well as reclaimed energy for further use or alternatively,
continuously removing the liquid in the hot well and sending it to
a flash chamber to produce vapor and the cooler flashed liquor
reintroduced into this second area to cool further gases; and the
third area is where the gas and liquid will continue to
progressively exchange heat content and supply heated liquid to the
hot well, until the gas approaches the temperature of the cool
liquid entering at the top.
[0011] (c) continuously replenishing the cool liquid entering at
the top of the exchanger
[0012] (d) continuously removing the cooled gases from the top of
the exchanger as reclaimed energy for further use.
[0013] Other embodiments are listed below
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] To avoid complexity, valving and other obvious operations
are not always shown, or labeled e.g. exhaust steam from steam
turbines could go to a condenser; the gas compressor in FIG. 3 and
elsewhere could be connected directly to the turbine expander,
along with an electric motor. An "o" indicates a pump; particulate
removers would be installed when they are required, etc.
[0015] The following drawings are schematic representations of the
various embodiments/applications of the present invention:
[0016] FIG. 1 illustrates the main embodiment described above The
figure shows two "cooling gas and heating liquid "areas, as the
liquid in the hot well can alternatively be sent to a flash chamber
and the cooler flashed liquor reintroduced into the second area to
cool further gases, see FIG. 1B.
[0017] FIG. 1A illustrates schematically how Carson's Fluidized
Spray Tower can be incorporated in the present invention.
[0018] FIG. 1B illustrates an embodiment where the liquid in the
hot well is sent to a flash chamber/evaporator to produce steam and
the cooler flashed liquor reintroduced into the second area to cool
further gases.
[0019] FIG. 1C illustrates an embodiment where the hot water from
the hot well is sent through a pressurized indirect contact heat
exchanger, heated by the hot gases, to produce high temperature,
high pressure steam, for use as process steam and/or to generate
electricity using high efficiency steam turbines.
[0020] FIG. 1D illustrates an embodiment where the steam from the
flash chamber is sent through a pressurized indirect contact heat
exchanger, heated by the hot gases, to produce superheated
steam.
[0021] FIG. 2 illustrates an embodiment where a known process
(Source) is adapted to produce the gases required for the
embodiment shown in FIG. 1
[0022] FIG. 3 illustrates an embodiment where the gases from a
known process (Source) are passed through a gas compressor to
produce the pressurized hot gases required for the embodiment shown
in FIG. 1.
[0023] FIG. 4 illustrates an embodiment where the liquid from the
hot well is heated to a higher temperature indirectly before
flashing it in the flash evaporator. The indirect heater could be
located within the Source.
[0024] FIG. 5 illustrates an embodiment where the pressurized
gas-steam mixture is heated prior to going to the pressurized
direct contact heat exchanger.
[0025] FIG. 6 illustrates an embodiment where the non-condensable
gas content is in the low range and the gases are further
pressurized by using a high pressure pump which condenses more of
the water vapor prior to going to a secondary pressurized direct
contact exchanger.
[0026] FIG. 7 illustrates an embodiment where combustible material
is combusted under the earth or sea and the gases processed above
the site in the pressurized direct contact exchanger.
[0027] FIG. 8 illustrates an embodiment where gaseous material
under the earth or sea can be brought above and processed in the
pressurized direct contact exchanger.
[0028] FIG. 9 illustrates an embodiment where a number of the
embodiments are involved in an overall process, applicable to the
Pulp & Paper Industry.
[0029] FIG. 10 illustrates an embodiment where the electrolysis of
water under pressure supplies oxygen to a pressure combustion
furnace and illustrating a further symbiotic relationship with the
invention. Combining it with that of the embodiment of FIG. 9 would
illustrate a further symbiotic relationship, in that the Paper
Machine Dryers could also contribute further oxygen, present in the
air and steam, to the combustion step.
[0030] FIG. 11 illustrates an embodiment where a pressurized-direct
contact exchanger is combined with a pressurized indirect heat
contact exchanger, (which could be located within the Source), to
generate high pressure high temperature steam, in order to take
advantage of the higher efficiency of high pressure, high
temperature steam turbines.
[0031] FIG. 12 illustrates an embodiment where greenhouse gases,
such as carbon dioxide, are produced which can be recycled through
its use to accelerate biomass growth. In this embodiment a
pressurized direct contact exchanger and pressurized combustion is
combined with pressurized electrolysis of water to generate
pressurized oxygen for the combustion, and hydrogen as a
by-product, as well as produce substantially pure carbon dioxide in
the flue/exit gases, when the fuel is essentially carbon.
[0032] FIG. 13 illustrates an embodiment where by operating a fuel
cell at elevated pressures and temperature and passing the hot
gases through the pressurized direct contact exchanger the
efficiency of the cell is increased,
[0033] FIG. 14 illustrates an embodiment where energy is reclaimed
from a process involving the electrolysis of alumina
[0034] FIG. 15 illustrates an embodiment where energy is reclaimed
from a process involving the electrolysis of water.
[0035] FIG. 16 illustrates an embodiment where energy is reclaimed
from a process involving the electrolysis of steam using the
Cerametec Process and combined with other embodiments illustrated
above. The steam from the flash evaporator could be processed as
illustrated in FIG. 1C.
[0036] FIG. 17 illustrates an embodiment where the electrolysis of
water or steam is combined with other processes and embodiments and
the results used in various applications e.g. oil enhancement,
phytotechnology.
[0037] FIGS. 18 & 19 illustrate an embodiment where various
substances are processed in a pressure reactor and the reacting
materials are handled in two different ways to produce steam.
[0038] FIG. 20 illustrates an embodiment where thermal
depolymerization is carried out.
[0039] FIGS. 21 & 22 illustrate embodiments where gases
existing at lower pressures can produce hot fluids (which in the
case of water can produce high pressure steam and/or
electricity).
[0040] FIG. 23 illustrates an embodiment where further energy can
be reclaimed in pressure combustion projects in the Clean Coal
Technology Program sponsored by the US Department of Energy.
[0041] FIG. 24 illustrates an embodiment where further energy can
be reclaimed in gasification projects in the Clean Coal Technology
Program sponsored by the US Department of Energy.
[0042] FIGS. 25 and 26 illustrate an embodiment where the invention
can be applied to the recovery of bitumen (i.e. oil) from Oil
Sands, including the recovery of energy and water.
[0043] FIG. 27 illustrates an embodiment where the invention can be
applied to a new paper technology referred to as Impulse
Drying.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] The following embodiments are process sequences that provide
a wide range of choice to fit a wide variety of circumstances,
applications and available technologies. Because of the wide range
of process variables involved and technologies to choose from it is
nearly impossible to describe in any detail how a particular
embodiment is carried out. For example, while many of the
embodiments below will use water as the condensable vapor it will
be understood that wherever feasible there embodiments can be used
for other condensable vapors, such as the many organic solvents
used in the chemical industry. In most cases computer simulation
will be required to balance the various variables such as the rate
of recirculation of the hot well liquid through the flash chamber;
the cool liquid supply; the excess liquid removal, which can be
done at the appropriate location: etc.
[0045] The embodiments as illustrated and described is such as to
obtain maximum thermal efficiency, noting that, the higher the
pressure and the lower the temperature of the gas leaving the
pressurized direct contact heat exchanger, the lower the vapor
content of the exit gases and the higher the thermal efficiency.
Embodiments involving lower pressures are also being included, see
FIGS. 21 & 22. Referring to the accompanying drawings, the
symbols used have the following meaning: TABLE-US-00001 G Generator
for electricity GT Gas Turbine TC Turbine Compressor TE Turbine
Expander PR Particulate Remover M Motor electric ST Steam Turbine C
Condenser P Pump PM Paper Machine PDCHE Pressurized Direct Contact
Heat Exchanger PICHE Pressurized Indirect Contact Heat Exchanger
Note: TC also represents a rotary blower
Referring to the drawings in greater detail. FIG. 1 shows the basic
embodiment described above.
[0046] The gases can contain two components of heat, sensible heat
and latent heat. If there is little or no condensable vapor in the
gases, if will essentially be all sensible heat and the cooler
liquid will extract heat and become hotter. If there is condensable
vapor the cooler liquid will condense the vapor and the resulting
heat will be absorbed by the cooler liquid and become hotter
[0047] Examples of further use for the condensed vapor in the hot
well are numerous and well known in the trades in which a
particular condensed vapor is involved, and which will also depend
on the temperature of the condensed vapor in the hot well, which is
determined by the pressure of the hot gases and the vapor pressure
of the condensed liquid.
[0048] For example, if the condensed vapor is water and the
pressure of the gases in the heat exchanger is 200 psia the
temperature in the hot well will be somewhat below 195 C (382 F)
depending on the efficiency of the heat exchange, Similarly,
further use of the gases will depend on the type of non condensable
gas involved and the dryness of the gas will depend on the pressure
and temperature of the exiting gases, i.e. Henry's Law of Partial
Pressures. For example, using the following equation for gas
saturated with water vapor at t.degree. F.: lb . mols .times.
.times. H 2 .times. O lb . mols .times. .times. dry .times. .times.
gas .times. .times. M = vapor .times. .times. pressure .times.
.times. of .times. .times. water .times. .times. at .times. .times.
t .times. .times. .degree. .times. .times. F . / total .times.
.times. pressure 1 - vapor .times. .times. pressure .times. .times.
water .times. .times. at .times. .times. t .times. .times. .degree.
.times. .times. F . / total .times. .times. pressure ##EQU1## we
find that at 100.degree. F. & 250 psia M=0.0038 which is way
below that of a normal ambient condition, so if this temperature
was attainable for the exiting flue gases, it would greatly improve
the overall thermal efficiency, especially if the air being fed
into the turbine compressor had a high water vapor content. Even at
160.degree. F. & 250 psia M=0.0193 & at 200 psia M=0.0243
& at 150 psia M=0.0326, all within a normal ambient range.
[0049] These higher pressures are required when higher hot well
temperature are desired and/or when the invention is used in
connection with a flash evaporator/chamber to produce fairly high
steam pressures and to concentrate effluents. The lower end of
pressure spectrum, e.g. in the range of that produced by a rotary
blower, can be used to reclaim the energy as illustrated below in
FIGS. 21 & 22.
[0050] The cool dry pressurized gases are source of energy for the
production of electricity using a turbo-expander connected to a
generator.
[0051] Where water is the condensed liquid in the hot well it could
obviously be used to heat large living and business complexes
especially in remote places. Further use for the cool gases and
water in the hot well are described in the various embodiments
below. While the various areas or zones of the pressurized direct
contact exchanger are some times shown in one chamber, they could
be located in separate chambers or sections Here the hot well is
shown near the top of lower zone so as to illustrate that the area
below it could be used to dry solid materials. Normally it would be
near the bottom.
[0052] Various technologies are available in determining how the
chambers are constructed and the best type of heat exchanger to
use, while maintaining maximum heat exchange and minimum pressure
drop, e.g. the Field gas scrubber; bubble columns; packed towers;
turbo-gas absorber; cascades; collecting the cooler liquid at any
point in the pressurized exchanger and recycling it in the
exchanger until its temperature approaches that of the gas; etc.
While the cooling liquid introduced into various areas is shown as
entering at one point, depending on the mixing technology used, it
could be introduced at various points in each area or section. To
increase the dwell time of contact between the gas and the cooler
liquid, a portion of the descending liquid may be withdrawn from
the top section and re-circulated back through the gas This
procedure may be repeated at any place in the exchanger where it
seems appropriate. The top location could be the best place to
remove any liquid in order to maintain a water balance as its heat
content would be the least.
[0053] A particular heat exchange process used for gases at
atmospheric pressure is the "Fluidized Spray Tower" technology,
recently developed by William D. Carson and disclosed in U.S.
patent application 20030015809). The disclosure of which is hereby
incorporated by reference, as embodiments of that Process, designed
to recover heat from non-condensable gases containing a condensable
vapor, are directly pertinent to this invention, designed to
recover heat from gases at pressures and temperatures greatly
higher than presently attempted.
[0054] As illustrated schematically in FIGS. 1A, using water as the
condensable vapor, the pressurized hot gases enter at the lower end
of the First Tower and if necessary can be scrubber clean of solid
material and leave with the waste condensate; Water (heated) in the
Second Tower enters the First Tower to be further heated and
accumulate in the "reservoir" i.e. hot well; the still hot gases
from the First Tower are introduced into the Second Tower to be
further cooled and dried by the very cool water entering the Second
Tower. For gases at lower temperatures, one Tower would suffice,
possibly using the single chamber embodiment, and for very high
temperatures possibly more than two Towers may be necessary.
[0055] The whole chamber or any one of the separate chambers could
be located within the confines of the Source depending on the
process producing the hot gases and other factors. Further
elaboration is given in various embodiments below.
[0056] Existing high pressure process 'sources include: (a)
pressurized combustion projects in the Clean Coal Technology
Program sponsored by the US Department of Energy, where pressures
up towards 250 psia are reached using combustion furnaces developed
by such firms as Foster Wheeler, ABB (now Alstom Power), &
Babcock & Wilcox; (b) high pressure char oxidation; processing
of wood in digesters; etc.
[0057] In FIG. 2, the Source involves a known process which does
not provide the pressurized gases required, but can be adapted to
perform at a substantially elevated pressure and, if feasible,
higher temperature as was done above for coal.
EXAMPLES
[0058] Combustion/incineration of materials that produce water
vapor, e.g. wet combustibles. While some emphasis is on biomass
fuels, the process could have application to the combustion of (a)
solid/liquid fossils fuels; (b) fuels intermediate between the two
i.e. lignite (brown coal), peat, etc, where the high moisture
content is a deterrent to their use; (c) Diverse fuels, such as
Tire Derived Fuel (TDF), and various sludges, etc. (2) Diverse
processes such the smelting of ores; wet oxidation; chemical,
electrochemical, metallurgical processes (blast furnaces), and
intermediary operations such as: drying; stripping, extraction;
boiling and the like.
[0059] In FIG. 3, there is shown an arrangement wherein the
increase in pressure of the source process cannot be carried out,
then the gases from the source process are turbo-compressed to the
desired pressure, with the temperature increased by the
compression. For example in the drying of pulp or paper, enormous
quantities of air and steam are expelled to the atmosphere, here
the air-steam mixture could be turbo-compressed and their heat
content recovered in the pressurized exchanger. See embodiments
below.
[0060] It is also possible, to collect other non-condensable gases
containing water vapor (which are outside of the source) and
turbo-compressing them to a pressure sufficient to introduce them
into the source process. For example, in the above paragraph the
air-steam mixtures could be turbo-compressed and introduced into a
combustion furnace. Other such mixtures include naturally occurring
ones such as fog banks, low clouds, mists, steam eruptions from the
earth, etc.
[0061] In most of the following embodiments, water will be the
"condensed vapor" used in the examples. Embodiments involving the
flash evaporator will generally also be used along with the use of
low pressure steam turbines but it is understood that wherever
there is need to increase the thermal efficiency of the turbines
the above embodiments shown in FIGS. C & D can be used.
[0062] The following embodiment involves expanding the alternative
use of the hot well liquid of the main embodiment as follows:
[0063] continuously removing heated liquid from the hot well and
flash evaporating it in a flash chamber at a pressure lower than
the pressure corresponding to the equilibrium or hot well
temperature to thereby (1) convert some of the water in the liquid
into steam and (2) cool the liquid to a temperature corresponding
to the pressure of the flashed steam and allow it to collect in a
sump in the flash chamber, continuously removing cooled liquid from
the flash chamber and re-introducing it to the direct contact heat
exchange section; at a point in the second area where the gas in
the area is at about the same temperature as that of the liquid in
the sump, so as to cool further gases, and where the gas and cooled
liquid will progressively exchange heat content, until the gas as
it cools approaches the temperature of the liquid from the flash
chamber; continuously removing the flashed steam from the flash
chamber for further use;
[0064] This further embodiment is illustrated in FIG. 1B, and
examples of further use for the flashed steam and cool gases are
also shown, namely, as process steam and/or as a source of energy
for the production of electricity using steam turbines connected to
a generator for the flashed steam; and as a source of energy for
the production of electricity using a turbo-expander connected to a
generator for the cool gases.
[0065] As mentioned above the temperature of the water in the hot
well will depend on the pressure in the exchanger and
correspondingly this will determine the pressure of the steam from
the flash chamber. As mentioned, at 200 psia the temperature in the
hot well will be somewhat below 195 C (382 F) so this could produce
steam pressures in a range somewhere below 200 psia depending on
the flashing potential used and several other factors, including
the enthalpy of the gases,
[0066] It should be noted that the pressurized direct contact heat
exchanger in combination with a flash chamber/evaporator can
concentrate cool effluents containing solids, used to cool the
gases, which if combustible can be burnt in a combustion furnace.
Examples are given below Another feature of this combination, is
that when the efficiency of lower pressure steam turbines has been
significantly increased, it will not be necessary to use the
embodiments illustrated in FIGS. 1C & 1D, and so avoid the high
cost and maintenance of pressurized indirect contact heat
exchangers
[0067] FIG. 1C illustrates how the hot well water can be upgraded,
especially where the temperature of the hot gases is high enough,
as it would be, for example, when the gases come from a high
pressure combustion furnace. This means that the hot water can now
be turned into high temperature, high pressure steam, and used in
high efficiency steam turbines to produce electricity, by passing
it through a pressurized indirect heat exchanger i.e. boiler. In
FIG. 1C it is shown separately but can be located within the source
e.g. a pressure combustion furnace. Alternatively, if the Source is
not pressurized, the hot well water can be upgraded by passing it
through a conventional atmospheric boiler.
[0068] FIG. 1D illustrates how the medium to low pressure steam
from the flash chamber can be upgraded in order to improve the
efficiency of the lower pressure steam turbines, should their
efficiency not be high enough. Here the lower pressure steam is
superheated by passing it through a pressurized indirect contact
heat exchanger, before passing through the lower pressure steam
turbines. The pressurized indirect heat exchanger i.e. a
super-heater is shown separately but can be located within the
source e.g. a combustion furnace. Similarly, as mentioned above the
low pressure steam can be upgraded by passing it through a
conventional atmospheric boiler.
[0069] FIGS. 9 & 10 illustrate how the overall efficiency of
the process can be upgraded by passing the pressurized hot gases
through a gas turbine connected to a generator to produce
electricity, before they are sent to the pressurized direct contact
heat exchanger. In this case, the pressure of the gases from the
turbine should still be high enough to operate the exchanger
satisfactorily. The gases from the turbines could also go to a
pressurized indirect contact heat exchanger before going the direct
contact exchanger, as illustrated in FIGS. 1C & 1D.
[0070] Which of the above embodiments is chosen could depend on
which is less expensive approach.
[0071] FIG. 4 illustrates an arrangement where the liquid from the
hot well is heated indirectly to a higher temperature to thereby
increase the steam pressure in the flash evaporator. For example,
by passing the liquid through a tube bank within the source
process, should it be capable of heating the liquid.
[0072] FIG. 5 illustrates an embodiment where the pressurized gases
are further heated prior to going to a pressurized direct contact
heat exchanger, For example, by burning oil or gas in the mixture,
where it will consume any remaining oxygen or to which additional
oxygen may be added, one can also heat the cool gases leaving the
pressurized direct contact heat exchanger prior to them entering
the turbine expander. For example, by burning oil or gas in the
mixture, or by combining the operations of the expander and
compressor and introducing inter-stage cooling and heating, as
mentioned in one embodiment below. This may be necessary to avoid
water condensing or freezing in the turbine expander, if the
pressure is very high and the temperature low.
[0073] As previously mentioned, a further arrangement is where, if
the pressure and temperature of the hot gases from the source
process are high enough, after removing any particulates, they are
passed through a gas turbine connected to a generator to produce
electricity, before being sent to the pressurized direct contact
heat exchanger. This is particularly advantageous for a combustion
process where high gas temperatures are achievable as illustrated
in FIG. 9 & 10. It could be important to dry any wet fuels
prior to combustion so as to obtain a maximum temperature. The
drying could be done using the gases after leaving the gas turbine
as shown in FIG. 9.
[0074] Oxygen, if required in any of the embodiments, is supplied
by a source under a pressure greater than the pressure required for
the source of the pressurized hot gases This makes the process more
efficient by eliminating the need for a turbine compressor. The
electrolysis of water or steam is one such source, where it is more
efficient at the higher pressures, with pressurized hydrogen as a
valuable by-product This is illustrated in FIG. 10 and expanded
below. Alternatively, the oxygen may be supplied in bulk or by air
liquefaction with nitrogen as a by-product.
[0075] By using cool liquids, containing dissolved or suspended
materials as the cooling liquid, the liquid can be concentrated by
the recycling of the liquid through the pressurized direct contact
heat exchanger and flash evaporator. Once the concentration of the
materials in the circulating liquor reaches the desired level, a
portion can be removed at a rate that will prevent further
concentration.
[0076] If appropriate, the liquid may be used in the source
process, e.g. where that process is one of combustion and the
material in the liquid is combustible. This is illustrated in FIGS.
9 & 10. (see below) Other such liquids are effluents from many
other mills, as well as from sewage treatment plants.
[0077] Other examples would be (a) the desalination of salt water,
the liquor would provide a source of salt and the condensed steam a
source of salt-free water suitable for irrigation; (b)
concentration of dilute sugar sources, i.e. cane, beet and maple
sugars, where any residues or forest biomass can be combusted under
pressure to produce the hot gases; water associated with oil from
the wells (producer water) when separated from the oil can serve as
the cool liquid and when concentrated can be added to the oil and
burnt and the noncombustible pollutants removed in the ash for
proper disposal; etc.
[0078] It is also possible that the first area of step (b) in the
embodiment of FIG. 1, is used to dry materials. Here all or a
portion of the hot gases would be introduced into a chamber
containing the material to be dried and the drying done in a number
of ways, such as flash drying, a fluidized bed, rotary tumble
drier, etc, and the dry or partially dried material removed through
a screw press or decompression chambers, etc or sent directly to
the Source. Various bio-masses, such as peat, lignite, bark,
leaves, branches, roots, and many other materials considered as
waste can thus be dried or partially dried. The gases after being
so used and before the saturation temperature has been reached,
would be sent to the rest of the pressurized direct contact heat
exchanger. If the dried material is still considered waste and is
combustible and the source process is one of combustion then it can
be sent there and consumed. This is illustrated in FIGS. 9 &
10.
[0079] Undesirable solids and/or gases present in the hot gases can
be removed in the heat exchanger by maintaining the circulating
liquid alkaline for acidic gases and acidic for alkaline gases. The
substances so formed can then be concentrated and removed from the
flash evaporator (see above).
[0080] This could allow greater use of fossil fuels containing a
high sulphur content. If the solids/gases are very soluble in the
water, they could be put through a scrubbing chamber prior to the
pressurized direct contact heat exchanger, were a minimum of liquid
could reduce their concentration.
[0081] Illustrated in FIG. 6 is where the non-condensable gas
content is in the low range. Here the pressurized hot gases are
sent to a primary pressurized direct contact heat exchanger and
processed through the first and second areas of the main
embodiment, then they are removed from the exchanger at a
temperature close to that of the temperature of the flashed liquid
in the evaporator and fed to the suction side of the pump which is
removing the flashed liquid from the flash evaporator, which is
capable of pressurizing this removed mixture to a pressure which
will condense most of the steam in this removed gas mixture, this
pressurized liquid and gas mixture is then sent to a secondary
pressurized direct contact heat exchanger where the liquid and
gases separate at a temperature corresponding to that of the pump
pressure, the separated liquid in the secondary pressurized direct
contact heat exchanger is sent to the top of the primary
pressurized direct contact heat exchanger at a point where the
removed gases exit, the heat content of the separated gases
containing a low amount of steam can then be recovered as desired
e.g. in a turbine expander connected to a generator, etc.
[0082] In certain applications, it is desirable to minimize the
presence of the non-condensables in the source process, e.g. in the
pressurized thermomechanical pulping of wood chips, by presteaming
the chips prior to their entering the refiner.
[0083] If the steam from the flash evaporator is unsuitable for a
particular use, or cannot be cleaned by conventional means, it is
passed through a reboiler for further use.
[0084] As illustrated in FIG. 7, where the source process is a
combustion process carried out under the earth or sea under
pressure, where there is combustible material, where the combustion
is supported by a pressurized gas containing oxygen and controlled
by water piped to the combustion site from above the site. The
pressurized hot gases would be piped to a pressurized direct
contact heat exchanger above the site and processed utilizing any
of the other embodiments that will give the desired result
[0085] Illustrated in FIG. 8 is an embodiment where the source
process is carried out below the earth or sea under pressure, where
there is recoverable material, and where the process is activated
by high pressure steam, preferably superheated steam, which allows
the material to flow to a pressurized direct contact heat exchanger
above the site and processed as for any of the other embodiments.
As illustrated, high pressure super-heated steam could flow down an
insulated pipe to melt the methane hydrate ice and allow it and
steam to flow up another pipe to the pressurized direct contact
heat exchanger above the site to be dried as in FIG. 1.
[0086] Alternatively, the two pipes could consist of concentric
inner and outer pipes, with the steam flowing down the inner pipe
to melt the hydrate, which will flow up the outer concentric pipe
which is wide enough to trap the methane and in which the pressure
is less than that of the liberated methane. Some of the methane
could be used in a conventional boiler to produce the steam and the
water supplied from the hot well. The end product would be a
pressurized, substantially dry methane gas.
[0087] This could also be applicable to number of fossil fuels,
e.g. unmineable, gassy coal beds containing methane; wells of
natural gases, volatile oils, etc after the wells have been
somewhat depleted; where the steam will act as a sweep gas.
[0088] FIG. 9 illustrates how a number of the above embodiments can
function within the one process, with particular application to the
Pulp and Paper Industry where it forms a somewhat symbiotic
relationship.
[0089] A collector receives air-steam emissions from the paper and
pulp mill, especially those from the drier section of the paper
machines (other sources not indicated include those from
thermomechanical pulping processes). This air-steam mixture,
monitored for the correct amount of air required for combustion, is
passed through a turbine compressor where it is compressed to a
pressure high enough for the process to generate a steam pressure
suitable for the dryers of the papermachine, as well as operate a
gas turbine e.g. 250 psia and higher. The compressed air-steam
mixture goes to the pressure combustion furnace where combustible
wet fuels are burnt to produce hot flue gases. Auxiliary fuel, oil
or gas, can be added to the hot gases and burnt to maintain uniform
combustion and an optimum temperature for the gas turbine. (see
above)
[0090] These hot gases are passed through a particulate remover and
a gas turbine and then through a first section or area of the
pressurized direct contact heat exchanger, a drier, which dries
biomass material, e.g. forest waste and bark including, liquid
concentrate from the flash evaporator, to a moisture content
amenable to combustion in the pressure combustion furnace. From the
drier the flue gases pass to the main second section or area of the
pressurized direct contact heat exchanger a scrubber, where they
come into intimate contact with a liquid concentrate, containing
dissolved and suspended solids from paper & pulp effluents. In
applications where only an effluent concentrate is to be combusted
or the wet fuels are dry enough to combust, the drier would be
omitted and the flue gases would pass directly to the pressurized
direct contact heat exchanger. The above concentrate would be
generated in the initial start-up of the process as the dilute
effluent is concentrated in the flash evaporator.
[0091] By continuously removing the heated concentrate and
evaporating it in the flash evaporator at a pressure lower than
that corresponding to the equilibrium or hot well temperature, so
as to (a) convert some of the water in the concentrate into steam,
(b) further concentrate the liquid, and (c) cool the concentrate to
a temperature lower than the hot well temperature, and then
returning the cooled concentrate from the flash evaporator to be
reheated in the pressurized direct contact heat exchanger; and
removing the steam from the flash evaporator, much of the heat
content of the flue gases is converted into process steam.
[0092] The saturated flue gases from the main pressurized direct
contact heat exchanger, after they are cooled to approximately the
temperature of the liquid concentrate from the evaporator, are
passed through the last section or area of the pressurized direct
contact heat exchanger to come into intimate contact with cool
dilute effluent to further cool the flue gases and preheat the
effluent;
[0093] Thus depending on the temperature of the entering effluent
and the efficiency of the pressurized direct contact heat exchanger
heater, if the pressure of the flue gases is around 250 psia the
water content in the flue gases could be approximately 0.10 lbs per
lb of dry flue gas, which is that of the water content of most
ambient air, and the thermal efficiency of the process could
approach 90% depending on other factors.
[0094] Then by continuously removing some of the heated concentrate
and adding the required preheated dilute effluent, the proper
liquid concentration and balance in the system can be
maintained.
[0095] The cooled flue gases from the pressurized direct contact
heat exchanger heater are passed through a turbine expander to
recover some of remaining enthalpy, which is used to compress the
air-steam mixture. If necessary they can be put through a
particulate remover before going through the turbine expander. Any
make-up power for the compression can be supplied by a motor or,
while not shown in the drawing, the cooled flue gases can be passed
through a combustion chamber in which oil or gas can be burnt to
heat the gases to the required temperature before they pass through
a turbine expander. (See the above embodiment) Any excess power can
used to generate electrical energy by Arranging for the motor to
also act as a generator.
[0096] To remove any acidic gases from the flue gases, alkaline
substances can be added to the liquor circulating in the
pressurized direct contact heat exchanger. By a proper choice of
substances these will reappear in the ash being removed from the
furnace, a portion of which may then be extracted using hot dilute
effluent and returned to the pressurized direct contact heat
exchanger.
[0097] The rest of the drawing illustrates how the water from
effluents and the steam in the emissions from the paper and pulp
mill is recycled back to mill. The steam from the flash evaporator
if necessary is passed through a particular remover or a reboiler
and then sent back to the paper machine dryers, or some used in the
pulp mill. Any excess steam can be used to generate electrical
energy using condensing steam turbines. The condensate from the
dryers is used as clean make-up water at the wet end of the paper
machine. This water reappears again in the white waters from the
wet end which are sent to a fiber recovery system, from which they
appear in the effluents from that system and are sent to the
effluent collector, where they join effluents from the pulp mill.
Condensate from the steam turbines can be used similarly in the
paper & pulp mill where it will return via the effluents from
the mill. To increase the efficiency of the steam turbines the
steam from the evaporator can be processed as illustrated in FIG.
1D.
[0098] FIG. 10 further illustrates how flexible the invention is
and that it can even enter into further symbiotic relationships
with other processes. One such process is the electrolysis of water
under pressure (mentioned in the embodiment above) Electrical
energy required for the electrolysis is supplied directly by any
generator adapted to produce the direct current, as converting
alternating current to direct current is inefficient. If the
pressurized hydrogen, so produced, is not also used in the source
process e.g. where carbon monoxide is produced and this is combined
with the hydrogen to form methanol, it becomes a very valuable
by-product. If the electrolysis unit is located where further
oxygen is required e.g. for pulping and bleaching, this may be a
further advantage. Depending on the choice of material being burnt
the exit gas will be fairly pure carbon dioxide, another by-product
of the process, which has a wide use e.g. for urea, methanol,
enhanced oil recovery, refrigeration, etc.
[0099] In a further embodiment energy can be removed from the
pressurized direct contact heat exchanger for various purposes, and
the resulting cooled liquid returned to the pressurized direct
contact heat exchanger to be reheated. For example, a primary flash
evaporator produces steam at the highest possible pressure level,
the flashed liquid from the primary is then flashed in a secondary
flash evaporator to produce steam at a lower level, if desired this
sequence could be continued or, at any stage, the flashed liquid
could be used to indirectly heat other media e.g. hot water heating
of a building, with the final cooler liquid returned to the
pressurized direct contact heat exchanger for re-heating.
Similarly, by subdividing the hot well liquid and liquid after
flashing and using several independent circulating systems, the
rates of circulation, which may depend on the rate of steam
production, are not inflexibly tied in with rates and methods of
cooling the combustion hot gases.
[0100] In an embodiment the cooled gases from the top of zone are
cooled further, in order to reclaim further latent heat, by
bringing them into indirect contact with the cooler gases between
expansion stages in the gas expander. This is an example of how
inter-stage-cooling and inter-stage-heating could be practiced in a
counter-current or parallel arrangement.
[0101] One can be combine various embodiments wherein the
electricity produced is one of direct current which is then fed
directly to the electrolysis of water, thereby increasing the
efficiency of the overall process. This can also apply to any
electricity produced in, steps (e) & (g). Similarly, in the
case of the electrolysis of steam, the process can supply the
direct current as well as the steam as illustrated in FIG. 16.
[0102] In some arrangements, advantages of other operations can be
made use of in the pressurized direct contact heat exchanger
process. For example, transportation of materials by pipeline can
often be less expensive than that by land or air. Thus, after the
appropriate comminution of the material and its suspension in
water, it can be pumped to the primary site, where the wetted
material is not a problem and the excess water can be used to cool
the gases in pressurized direct contact heat exchanger and any
dissolved/suspended material in the water concentrated in the flash
evaporator. This could be very useful for pressure combustion
processes, where the combustible material (e.g. coal, peat, and
various biomasses) can be transported to the combustion site by
pipeline.
[0103] FIG. 11 illustrates how the pressurized direct contact heat
exchanger is combined with a pressurized indirect contact heat
exchanger, by generating high pressure steam in order to take
advantage of the higher efficiency of high pressure, high
temperature steam turbines. While the amount of energy extracted by
the pressurized indirect contact heat exchanger will vary depending
on the application, a maximum amount would require that enough
energy be left in the hot gases in order to operate the pressurized
direct contact heat exchanger so the latent energy of the water
vapor in the gases can be extracted in the flash evaporator.
[0104] While the pressurized indirect contact heat exchanger is
shown as a separate chamber outside of the source, it could be
located within the confines of the source depending on the process
producing the hot pressurized gases. Where the source is a
combustion process, the pressurized indirect contact heat exchanger
could consist of tube banks located within the combustion
chamber.
[0105] A pressurized indirect contact heat exchanger can be
introduced into any one of the above embodiments depending on the
desired outcome.
[0106] In certain circumstances it may be possible to maximize the
thermal efficiency further by combining both gas and steam turbine
technologies with the pressurized direct contact heat exchanger
Process, by extracting some of the energy first in a gas turbine,
then further energy in a pressurized indirect contact heat
exchanger using high pressure steam turbines (as shown in the
above) and finally the remaining energy in a pressurized direct
contact heat exchanger using the steam generated there either as
process and/or in lower pressure steam turbines. Where the
generation of electrical energy is the prime objective, this
embodiment could offer the highest thermal efficiency. This could
be the case for generation of electricity from coal, especially
high sulphur coils. (See embodiment above)
[0107] Another application involves coal bed methane and the
sequestering of carbon dioxide, where unmineable, gassy coal beds
are swept with pressurized gases containing carbon dioxide which
releases the methane and traps the carbon dioxide. The gases
containing carbon dioxide are also effective in increasing oil
recovery, by reducing its viscosity and providing a driving force
towards the wells The addition of water/steam improves the sweep
efficiency and the water can be recovered in the pressurized direct
contact heat exchanger.
[0108] In these applications, by using the already pressurized
gases from the pressurized direct contact heat exchanger the cost
of the pressurization of the gases is avoided. In this technology,
while one objective is the removal of the polluting carbon dioxide,
in other situations nitrogen is also used to sweep the methane from
the coal, so how this application is used could depend on the
proportion of carbon dioxide and nitrogen in the gases from the
pressurized direct contact heat exchanger as well as the use of the
end product of this application, which will be pressurized gases
containing methane, e.g. this methane can be used to further heat
the hot gases as described above.
[0109] The present invention also has application to processes
which produce gases which on combustion yield hot pressurized
non-condensable gases containing water vapor. The following is an
example: a pressurized fluidized-bed gasifier transforms coal into
a coal gas containing hydrogen and methane (and carbon monoxide),
which after suitable cleaning is combusted with a gas turbine to
produce electricity, the hot gases containing water vapor exit the
turbine at a pressure sufficient to operate the pressurized direct
contact heat exchanger and produce low pressure steam as well as
operate a pressurized indirect contact heat exchanger which can
supply high pressure steam to the gasifier, as illustrated in an
embodiment above, Whether or not the pressurized indirect contact
heat exchanger produces steam for high pressure steam turbines is a
separate consideration. In present systems, the hot gases from the
turbine are sent to a conventional heat recovery steam generator,
so that the energy in the water vapor is lost to the
atmosphere.
[0110] FIG. 12 illustrates a way to reduce greenhouse gases, where
a pressurized direct contact heat exchanger and pressurized
combustion is combined with pressurized electrolysis of water to
generate pressurized oxygen for the combustion, and hydrogen as a
by-product. This produces substantially pure carbon dioxide in the
flue/exit gases, which is used to accelerate biomass growth in a
confined or enclosed space (e.g. an inflated plastic covering, see
"solar tower" below). Low pressure steam from the flash evaporator
can be to heat the enclosed space. Part of the carbon dioxide can
also be combined with ammonia to make compounds such as urea, which
can also be used to accelerate biomass growth as urea.
[0111] By creating a false ceiling below the canopy or covering
over the enclosed space, the oxygen and water vapour, generated by
the biomass, being lighter than the carbon dioxide, can be
segregated and removed and used in the pressurized direct contact
process (and the carbon dioxide recycled to the enclosed space or
"greenhouse").
[0112] Some or all of the biomass can be used for combustion/human
consumption and any waste from the latter use can be recycled
through the combustion cycle.
[0113] If air liquefaction is used in place of or in addition to
water electrolysis to produce the pressurized oxygen then the
nitrogen from the liquefaction can be used along with the hydrogen
(in case of the latter) to produce ammonia with can then be used to
produce the urea.
[0114] A further symbiotic situation is where the above is combined
with EnviroMission's (Australian firm) "solar tower" (a vertical
wind farm) where a chimney, connected to and surrounded by a
shallow, circular, acrylic greenhouse, (7 km in diameter) will
provide sufficient draft for the hot air generated by the
greenhouse, to power turbo-generators to produce electricity.
[0115] A special embodiment is as follows: A fuel cell takes in
hydrogen and a gas containing oxygen and generates electricity and
expels hot gases laden with water vapour. By operating the fuel
cell at elevated pressures and passing the hot gases through the
pressurized direct contact heat exchanger the efficiency of the
cell is increased If the gases are not hot enough, pressurized
combustible gases/oil can be burnt within the gases to increase
their temperature and consume any remaining oxygen or they can be
heated by any of the methods described above. FIG. 13 illustrates
this.
[0116] Possibly combining this with pressurized water electrolysis
other efficiencies might develop. See below. If only hydrogen &
oxygen are used, any residual hydrogen & oxygen could also be
recycled back to the fuel cells, rather than put through a turbine
expander to produce electricity. If air is used in place of the
oxygen the energy in the residual pressurized nitrogen would be
recovered in the turbine expander.
[0117] Other embodiments involve electrochemical processes where
the "overvoltage", etc generates heat, which is generally
dissipated, thereby decreasing the efficiency of the process.
[0118] One such embodiment involving electrolysis is illustrated in
FIG. 14, where the electrochemical process is that of the
electrolysis of alumina and the hot non condensable gas is mainly
carbon monoxide, and where the carbon monoxide content of the gas
can be increased by combining the process with the pressurized
direct contact heat exchanger as well as taking advantage of the
high solubility of the carbon dioxide in water and the
corresponding very low solubility of the carbon monoxide. Here the
gas is sent to Solution Chamber where cool water absorbs the carbon
dioxide, which when sent to a Gas Separator under atmospheric
pressure or a slight vacuum, releases the carbon dioxide and is
returned to the solution chamber to absorb more carbon dioxide. The
energy of the carbon monoxide enriched gas is recovered by
combustion in a Heat Recovery Steam Generator and steam generated
used for process or to produce electricity using steam turbines
[0119] It should be noted that the proportion of carbon monoxide in
the hot gas depends on the alumina content in the hot bath. By
carefully controlling this content (e.g. keeping track of the cell
voltage) this proportion can be kept to a maximum and the carbon
dioxide to a minimum and the carbon monoxide bleed off.
[0120] A further embodiment involving electrolysis is that of the
electrolysis of water, which was mentioned above in a general way
in a symbiotic association with other processes.
[0121] In particular it relates to those hydrogen-oxygen generators
that operate at relatively high pressures, e.g. high pressure water
electrolysis presently allow the generation of hydrogen at
pressures up to 5 MPa. (750 psi). One such unit under
development/available is made by GHW (Gesellschaft fur
Hochleistungswasserelektroly seure). Generally these operate at
normal temperatures, however by a similar choice of material, these
can be made to operate at fairly high temperatures at was done in
the Cerametec process mentioned below.
[0122] FIG. 15 illustrates how a pressurized high temperature
oxygen-hydrogen generator can be combined with the pressurized
direct contact heat exchanger. In previous embodiments the
pressurized direct contact heat process was generally involved with
a source having a single stream of hot pressurized non-condensable
gases containing water vapor. Since in the present embodiment there
are two streams, they are represented side by side.
[0123] Where necessary present oxygen-hydrogen generators are
cooled to keep the temperature below 100 C (e.g. 65-60 C) mainly to
avoid the formation of too much water vapor. In the present
embodiment, since the temperature is much higher, a fair amount of
steam with pass along with the gases, as illustrated in FIG. 15
[0124] Most of the rest of FIG. 15 has been explained and described
in more detail in many of the previous embodiments and need not be
repeated here. Since normally nearly pure water is used to
replenish that used up in the electrolysis, water here is taken
from steam turbine condensate. Some of the generated steam is used
to help preheat this water, prior to being pumped to the generator,
with the possible additional use of a jet pump. To further heat
this water to the operating temperature of the cell and to heat the
electrolyte at start-up, as well as help keep an even temperature
in the cell, an alternating current could be superimposed on the
direct current or used within a separate circuit.
[0125] FIG. 15 shows the use of a single flash chamber for both
gases, however, if there is too much cross contamination of the
gases, each should have its own flash chamber. Also to reduce a
loss of gas with the steam from the flash chamber, an inert
substance can be dissolved in the re-circulating liquid to reduce
the solubility of each gas in the liquid.
[0126] When the above embodiment is combined with pressure
combustion (see embodiment above) only one stream of gas would be
involved as illustrated in FIG. 10 i.e. that of hydrogen, as the
pressurized oxygen from the generator would pass directly to the
pressure combustion furnace. Similarly, the pressurized oxygen
could be used in anyone of the many other oxidation processes
involving oxygen e.g. as mentioned in an embodiment above: in the
pulp & paper industry for pulping and bleaching and in the
manufacture of sulfuric acid by the contact process, where the
higher pressure and temperature could be of benefit.
[0127] It should be noted that the above embodiment, FIG. 12, leads
(i) to a nearly pure source of pressurized carbon dioxide which can
be more readily used commercially or disposed of than the present
gases emanating from the various power combustion plants all over
the country, e.g. biomass growth and oil enhancement FIG. 17(a) and
(ii) to easily attained higher combustion pressures (by using high
pressure oxygen) thereby allowing for greater use of the higher
efficiency gas turbine technology.
[0128] FIG. 16 illustrates how the present invention can improve
the recently developed Cerametic process (mentioned above) for the
high temperature electrolysis of steam. Besides improving the
efficiency of the process it also shows how the high pressure, high
temperature steam that is needed for the generator can be generated
in the Combustion Furnace.
[0129] Further examples of symbiosis are illustrated in FIG. 17,
where the process illustrated in FIG. 15 or FIG. 16 can be located
in various locations.
[0130] (a) Here the process in FIG. 17 is located at a depleted oil
source where the oil could used to fuel the high pressure
combustion and the pressurized carbon dioxide could serve as a
working fluid in enhanced oil recovery (FIG. 17(a). In addition,
the (i) carbon dioxide would be sequestered (ii) hydrogen would
serve as a means of storing electricity for use in fuel cells;
(iii) which in turn be used to decrease pollution arising from
other activities producing carbon dioxide. Being pressurized the
plant would be very compact and could be moved from one depleted
oil well to another,
[0131] (b) A further example is Phytotechnology ( FIG. 17(b)) which
was mentioned above, where carbon dioxide is supplied as a nutrient
for accelerated growth of biomass crops (FIG. 12) as well as use up
the CO2. The biomass is produced in a closed-atmosphere,
controlled-environment that provides complete control of an
enriched CO2 atmosphere from 1000 to 3000 PPM. The Phytotechnology
process enhances the plant photosynthesis to achieve higher rates
of CO2 conversion into biomass, including BIOFUEL (and food, etc)
and mass-cell-culture and algae culture for energy. Normally the
process is carried out at normal pressure, however if done at
higher pressures the large amount of water vapor produced could be
sent directly along with the biomass to the furnace and its energy
recovered. Presumably the EnviroMission firm, mentioned above in
connection with FIG. 12 uses higher pressures. Using oxygen for
combustion, the water content of the biomass could be quite high
and still burn.
[0132] A further embodiment involves the general processing of
substances in a reactor under high pressure as illustrated in FIG.
18. The configuration of the equipment will depend on the process
used. If the heat developed is time dependent, then to insure that
the hottest part of the aqueous medium is located where the medium
leaves the reactor with a minimum of mixing, various reactor shapes
and baffles can be used e.g. an elongated baffled vertical chamber.
While the make-up water could come from the condensed steam, hotter
water would of course be preferable. By regulating its use the
concentration of the reactants in the circulating aqueous medium
can be increased/controlled.
[0133] Any gas produced in the reactor can be separated from the
aqueous medium in a special separator chamber, as shown in FIG. 18,
where the separated gas and steam goes to the pressurized direct
contact heat exchanger, with the hot well water being returned to
the gas separator, and the hot aqueous medium to a flash evaporator
where it can be concentrated and returned to the reactor. Such an
arrangement is necessary to avoid excessive gas being released in
the flash chamber, which could lower the efficiency of a condensing
steam turbine. Energy in the gas and steam is recovered in a
turbine expander. Alternatively, it may be used to heat the make-up
water and reactants. To maintain a sealing level of liquid in the
separator, a portion of the degassed medium can be recirculated
back to the separator (with the proper controls).
[0134] An example of a reactor process is that of wet oxidation
(combustion), where substantial steam is present with the gas that
is produced, and the heat content of the gas and steam is recovered
more efficiently, by passing the cool make-up water (e.g. condensed
steam) through the pressurized heat exchanger. A dry cool gas is
also produced, the energy of which is recovered in a turbine
expander.
[0135] Alternatively, if the gas is pressurized carbon dioxide (a)
it could be used for oil enhancement as shown in FIG. 17(a); or
where after de-pressurizing in the expander, it can be used in the
production of biofuel as shown in FIG. 17(b).
[0136] Reactants include compressed air or pressurized oxygen and
any oxidizable material, including inorganics, with a COD. Examples
are: (a) Caustic streams: refinery spent caustic and soda pulping
liquor; (b) Dangerous, obnoxious and toxic substances: effluents
containing cyanide, phenols, etc. (c) Waste biological sludges.
[0137] FIG. 19 illustrates where the gas separator can be
eliminated by sending the hot aqueous medium directly to the
pressurized direct contact heat exchanger
[0138] Which of the embodiment in FIGS. 18 & 19 is used will
depend on the nature of the wet oxidation.
[0139] The embodiment illustrated in FIG. 20 could be used in
various pressurized thermal depolymerization reactions involving
two Reactors. Here the medium from the First Reactor goes to the
first Gas Separator and the liquid from the first Gas Separator
goes to a Fraction Separator and the top fraction goes to a Second
Reactor, and the medium from that Reactor goes to a second Gas
Separator, with the hot gases from there joining the gases from the
first Gas Separator on their way to the pressurized heat exchanger,
and the liquid from the second Gas Separator going to Conventional
Distillation Column to yield the required Products, the hot gases
from which, if pressurized, could join those going to the
pressurized heat exchanger the bottom fraction in the Fraction
Separator is returned to the first Reactor for further processing.
The number of reactors will depend on the substances being
depolymerization
[0140] The following embodiment illustrated in FIG. 21, covers the
situation where lower hot well temperatures are produced and a
flash evaporator/chamber is not required. Here lower pressures are
used, i.e. higher than that which are used presently, and are
pressurized using a rotary blower (see below for attainable
pressures) and sent to the pressurized direct contact heat
exchanger to reclaim the energy as described above.
[0141] FIG. 22 illustrates where the condensable vapor is water.
The pressure chosen depends on the temperature desired for the
water in the hot well, which depends on the vapor pressure of the
water being used to cool the gases, as well as the pressures
obtainable using rotary blowers, which are less expensive than
turbine compressors. For example, a pressure of about 30 psia (15
psi) corresponds to a hot well water temperature of about 120 C
(250 F) and thermal efficiency would depend on the temperature of
the cooled gases. The pressurized gases can be passed through a
turbine expander connected to the rotary blower.
[0142] Here the hot water could be sent to a boiler (possibly
located in the Source) to produce very high pressure, high
temperature steam for process or for generating electricity using
highly efficient steam turbines. If cool enough the steam
condensate could be recycled back to the pressurized heat
exchanger. The hot water could of course be used for other
purposes. In terms of Carson's Fluidized Spray Tower illustrated in
FIG. 1A, one Tower or chamber should suffice for this
embodiment.
[0143] The present invention could have particular application to
existing high pressure combustion projects in the Clean Coal
Technology Program sponsored by the US Department of Energy,
(mentioned above).
[0144] (a) In various projects, a water paste of coal and limestone
and compressed air are fed to pressurized circulating fluidized-bed
combustor where combustion takes place at a pressure of about 200
psig, the hot flue gas pass through equipment to remove the
particulates, etc, then through a gas turbine and the heat in the
gas from the turbine is recovered in a conventional steam
generator, in which case the latent heat of any water vapor in the
final flue gas is lost.
[0145] FIG. 23 illustrates how the present invention can increase
the thermal efficiency of that process. Here the water paste of
coal and limestone and compressed air are fed to pressurized
circulating fluidized-bed combustor where combustion takes place at
a pressure of about 200 psig, the hot flue gas pass through
equipment to remove the particulates, etc, then through a gas
turbine and some of the heat in the gas from the turbine is
recovered in a pressurized indirect contact heat exchanger (i.e. a
boiler), to generate very high pressure and high temperature steam
with which the generate electricity using high efficiency stream
turbines using the hot well water from the pressurized direct heat
exchanger, the pressurized hot gases from the boiler go to the
pressurized direct contact heat exchanger to reclaim essentially
all the remaining energy in the gases as described above in various
embodiments.
[0146] Various details are left out since they vary from one type
of process to the other. Since the limestone removes about 95% of
the sulfur and the ash content in the hot gas is low, the hot well
water should be suitable to produce the high pressure high
temperature steam for the steam turbines. Here (FIG. 23) the
pressurized indirect contact heat exchanger (boiler) is shown after
the gas turbine, while in FIG. 24 it is shown before, whichever is
selected may depend of various factors. The pressure of the gases
leaving the turbine should be high enough so as to reclaim the
latent heat in the gasses in the heat exchanger. If desired the
turbine gas could be left out to simplify and reduce the cost of
the process.
[0147] (b) In another series of projects, a pressurized gasifer is
supplied with steam, oxygen, and a water paste of coal and
limestone to produce a fuel gas rich in hydrogen and carbon
monoxide, which is cleaned and used to fire a gas turbine. Again it
appears that the latent heat of any water vapor in the final flue
gas is lost, which could be high since hydrogen is one of fuel gas
components.
[0148] FIG. 24 illustrates how the present invention can increase
the thermal efficiency of that process. The process is essentially
the same as described above for FIG. 23, except the fuel gas goes
to a pressure combustion furnace, containing a pressurized indirect
contact heat exchanger (i.e. a boiler), where the hot well water is
used to generate the high pressure steam before the gases go
through the gas turbine. The pressure of the gases leaving the
turbine should be high enough so as to reclaim the latent heat in
the gasses in the heat exchanger.
[0149] As a further example of symbiosis, a high pressure
electrolysis of water plant (see FIG. 15) could be located nearby
to supply the requires pressurized oxygen. The gas turbine could be
left out and the hot gases from the fuel gas combuster could go
directly to the pressurized exchanger. In some processes air is
used in place of oxygen.
[0150] In another embodiment, FIG. 25 illustrates how the invention
can be applied to the recovery of bitumen (i.e. oil) from Oil
Sands, including the recovery of energy and water.
[0151] Here the process is concerned with the present technique of
using high pressure steam to lower the viscosity of the bitumen in
the sands so that it will flow towards a well which will raise it
above the ground. In the present embodiment care is taken to
collect as much steam and gas as possible emanting from the oil
well and compress it to the same gas pressure as that for the gases
coming from a pressurized combustion furnace, which will also
contain water vapor. Both gases are combined and processed through
the pressurized direct contact heat exchanger to recover the heat
energy in the gases as well as produce very hot well water which is
used to make the high pressure steam in a boiler in the pressurized
furnace.
[0152] This high pressure steam can also be used to produce
electricity with which to operate the system, using high efficiency
condensing steam turbines. The condensate can then be used to cool
the gases in the heat exchanger. Where it is introduced could
depend on its temperature. As indicated the coolest water available
is introduced at the top of the heat exchanger and its temperature
will determine the thermal efficiency of the process.
[0153] Depending on the type of fuel used to fire the furnace, it
may be necessary to clean the gases before they go to the heat
exchanger so as to ensure that hot well water is suitable for the
production of the high pressure steam. The gas cleaning technology
is well known and used in the Clean Coal Program sponsored by the
US Department of Energy. To that end it might be desirable to mix
limestone with the fuel so as trap any sulfur compound in the fuel
so that they will exit with the ash and not the gas steam. The
pressure in the furnace will depend on the temperature that is
desired for the hot well water, as well as the degree of thermal
efficiency desired, as was explained above.
[0154] FIG. 26 illustrates how the hot well water can be used in
the present technique of using hot water to separate the bitumen
from the Oil Sands. The water fraction can then be cleaned and sent
back to the heat exchanger at the proper location, depending on its
temperature, to cool further gases.
[0155] The present invention can also be used to break the bitumen
down into various fractions using the any of the above embodiments,
one of which is illustrated in FIG. 20.
[0156] As an alternative to the above the gas and steam from the
oil well can be processed as described in FIGS. 21 & 22.
[0157] Other embodiments involving lower pressures are situations
where drying (and boiling) is involved e.g. web drying. Here the
drying could be accelerated by subjecting the web to a mild vacuum
using either the suction side of rotary blower or a vacuum pump and
the steam and any entrained air could go a pressurized direct
contact heat exchanger, such as the fluidized spray tower mentioned
above, where some of the steam would be condensed using the water
in the hot well of the second heat exchanger as cooling water. The
water in the hot well can be sent to a high pressure boiler to
produce high pressure steam.
[0158] The remaining steam containing low amounts of air can then
to connected to the suction side of a high pressure water pump
being fed cooler water e.g. the condensate from the steam turbines
and then sent to a pressurized direct contact heat exchanger as
disclosed above in connection with FIG. 6, where more steam will
condense and the energy in the pressurized air can be recovered in
turbine expander, which can be used to power the rotary blower or
vacuum pump.
[0159] This embodiment can be very effectively used with a new
paper technology referred to a Impulse Drying where a very hot roll
is heated by either very hot steam or a gas flame or magnetic
induction This is illustrated in FIG. 27, where a vacuum chamber
encloses the hot roll. Details of how the roll is heated and how
the webs are introduced and removed from the Chamber are not shown
as they are well understood in the trade. By insulating the Vacuum
Chamber not will the heat content of the gases involved be
reclaimed but also that from the heating process used for the roll.
In this latter aspect, magnetic induction is recommended especially
that involving a new type of roll called "Optimized Heated Roll"
presently being marketed by Comaintel Inc.
[0160] While alternatively a low pressure chamber could be used,
the above low vacuum chamber would seem more advantageous.
[0161] It should be noted to avoid cleaning gases using expensive
equipment one can by using an indirect heat exchanger use the
unclean hot well water to heat the condensate from the steam
turbines and send this now clean hot water to the boiler to make
high pressure steam.
[0162] The preceding description of the invention is merely
exemplary and is not intended to limit the scope of the present
invention in any way thereof.
* * * * *