U.S. patent application number 12/066185 was filed with the patent office on 2008-12-25 for hybrid energy system.
Invention is credited to Edek Choros.
Application Number | 20080314726 12/066185 |
Document ID | / |
Family ID | 37835312 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080314726 |
Kind Code |
A1 |
Choros; Edek |
December 25, 2008 |
Hybrid Energy System
Abstract
A hybrid method for producing energy from a carbonaceous
material including the steps of: heating the carbonaceous material
under a reduced oxygen atmosphere in a distillation plant to
generate distillate vapours; processing the resulting distillate
vapours; transferring the char residue from the distillation plant
to a power station boiler; and combusting the char residue in the
power station boiler for the generation of electrical power. The
char residue is transferred to a power station boiler while the
char residue retains heat from the heating in the distillation
plant. An integrated energy conversion system including: a
distillation plant for the destructive distillation of carbonaceous
material to afford distillate vapours and a char residue; a power
station boiler; a means of transferring the char residue at a
temperature between 300 to 700.degree. C. from the distillation
plant to the bed power station; and collection means for the
distillate vapours.
Inventors: |
Choros; Edek; (Queensland,
AU) |
Correspondence
Address: |
THORPE NORTH & WESTERN, LLP.
P.O. Box 1219
SANDY
UT
84091-1219
US
|
Family ID: |
37835312 |
Appl. No.: |
12/066185 |
Filed: |
September 8, 2006 |
PCT Filed: |
September 8, 2006 |
PCT NO: |
PCT/AU2006/001311 |
371 Date: |
August 8, 2008 |
Current U.S.
Class: |
202/105 ;
110/229; 201/35; 290/1A; 48/89 |
Current CPC
Class: |
C01B 2203/065 20130101;
F02C 6/18 20130101; F02C 3/22 20130101; C10G 1/002 20130101; C10B
53/00 20130101; C01B 2203/84 20130101; C10G 1/02 20130101; F01K
23/064 20130101; C01B 2203/0233 20130101 |
Class at
Publication: |
202/105 ; 48/89;
110/229; 201/35; 290/1.A |
International
Class: |
C10B 49/02 20060101
C10B049/02; C10B 47/06 20060101 C10B047/06; C10B 53/00 20060101
C10B053/00; C10G 1/02 20060101 C10G001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2005 |
AU |
2005904943 |
Claims
1. A method for producing energy from a carbonaceous material
including: (i) heating the carbonaceous material in a distillation
plant under a reduced oxygen atmosphere to generate distillate
vapours and a char residue; (ii) processing the resulting
distillate vapours by condensing and separating one or more liquid
fractions from non-condensing gaseous fractions; (iii) transferring
the char residue at a temperature in the range of 200.degree. C. to
700.degree. C. from the distillation plant to a power station
boiler; and (iv) combusting the char residue in the power station
boiler for the generation of electrical power.
2. The method of claim 1 wherein the char residue is transferred
from the distillation plant to the fluidised bed power station
boiler by one or more of a double dump valve, pipe or conveyor.
3. The method of either of claim 1 or claim 2 wherein the transfer
of char is controlled via, double dump valves, screws, vibration,
compressed air, gravity, heat resistant belt conveyor, chain
conveyer, vibrating conveyer such as a vibrating tube conveyer,
high temperature rotary valves, or any combination thereof.
4. The method of claim 1 wherein the carbonaceous material is
heated to between 400 to 700.degree. C.
5. The method of claim 1 wherein the distillation plant comprises a
retort in which the heating of the carbonaceous material is
conducted.
6. The method of claim 5 wherein the char residue is transferred
from the retort to the power plant boiler at a temperature of
between about 300 to about 600.degree. C.
7. The method of any of claims 1 to 6 wherein the carbonaceous
material is selected from coal, coal washing rejects, low quality
coal such as lignite, oil shale, and any combination thereof.
8. The method of claim 7 wherein the carbonaceous material is
coal.
9. The method of claim 8 wherein the coal has less than 1.0% Mean
Maximum Vitrinite Reflectance.
10. The method of either of claim 8 or claim 9 wherein the coal is
a high liptinite coal.
11. The method of claim 1 wherein the carbonaceous material is
heated under reduced pressure.
12. The method of claim 1 wherein step (i) further includes the
addition of water vapour.
13. The method of claim 12 wherein the water vapour is selected
from steam or super-heated steam.
14. The method of claim 1 wherein the temperature of the distillate
vapours is reduced to below about 250.degree. C.
15. The method of claim 1 wherein the temperature of the distillate
vapours is reduced to below about 150.degree. C.
16. The method of claim 1 wherein the temperature of the distillate
vapours is reduced to below about 30.degree. C.
17. The method of any of claims 14 to 16 wherein a portion of the
distillate vapours condense to provide a liquid distillate
fraction.
18. The method of claim 17 wherein the liquid distillate fraction
includes an aqueous fraction and a hydrocarbon fraction.
19. The method of claim 18 wherein the aqueous fraction and the
hydrocarbon fraction are separated.
20. The method of claim 19 wherein the hydrocarbon fraction is
separated from the aqueous fraction through one or more of gravity,
suction or centrifugation.
21. The method of any of claims 17 to 20 further comprising the
step of upgrading the hydrocarbon component of the distillate
fraction.
22. The method of claim 21 wherein the upgrading is performed by
one or more of extraction with aqueous acid, extraction with
aqueous base, solvent extraction, fractional distillation,
hydrotreating or hydrocracking.
23. An integrated energy conversion system including: (v) a
distillation plant for the destructive distillation of carbonaceous
material to afford a distillate and a char residue; (vi) a power
station; (vii) a means of transferring the char residue from the
distillation plant to the power station while still retaining heat
of the destructive distillation in the char residue; and (viii) a
collection means for the distillate.
24. The system of claim 23 wherein the power station is a fluidised
bed power station.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to processes and systems
for the efficient utilisation of fuel. For example, the invention
relates to processes and systems for the pyrolysis of carbonaceous
material for the generation of fuels and electrical energy.
BACKGROUND OF THE INVENTION
[0002] The efficient and effective utilisation of natural
resources, particularly fossil fuel resources, is of increasing
importance given their finite nature. From an economic standpoint,
losses from the current methods of utilisation of fuel are largely
due to the failure to recover valuable by-products, and the failure
to sufficiently achieve energy maximisation. The lack of proper
recovery methods for fossil fuel by-products has also exacerbated
pollution problems associated with the combustion of such fuels. In
addition to the ineffective use of current resources and the
associated pollution problems mentioned, the world's crude oil
reserves are depleting (for the last thirty years only one barrel
of oil was discovered for every 2 barrels of oil produced). These
factors indicate that methods for the efficient usage of
alternative fuel sources to crude oil are desirable.
[0003] It has been known for over 100 years that coal can be used
to produce hydrocarbon fuels. The process of distilling oil from
coal, substantially in the absence of oxygen, is called variously
"destructive distillation" or "low temperature carbonisation".
Generally, it can be said that destructive distillation has for its
purpose the abatement of excessive pollution on the one hand, and
the increase in overall efficiency of fuel utilisation and
by-product recovery on the other hand.
[0004] Particularly useful by-products formed from the pyrolysis of
coal are nitrogenous and sulphurous materials. These by-products
are useful for the production of materials such as sulphuric acid,
elemental sulphur, ammonia and ammonia salts, and fertilisers. As
such, the recovery of these chemical compounds is highly desirable.
Their recovery is further desirable as these compounds are also
significant pollutants resulting from the inefficient processing of
coal.
[0005] Coal is not a uniform fuel source. Depending on the type of
coal used, it is envisaged that destructive distillation can
produce between 50 L to 250 L of oil per tonne of coal
(corresponding to 0.3 to 1.5 barrels of oil per tonne of coal). At
a price of AU $85/barrel this, for example, would correspond to AU
$25 to AU $127 additional value per tonne of processed coal.
Through the destructive distillation process, only 25% to 30% of
total energy of the feed coal is converted to hydrocarbon fuel. The
remaining energy source, in the form of a char residue, is
recovered and employed as a fuel source for a conventional power
station. An operation consuming 2 million tonne of low grade coal
per year could produce 2 million barrels of oil per year (based on
an expected oil yield of 1.0 barrels per tonne of coal),
corresponding to a current value of approximately AU $170 million
per annum. The coal char residue and gas from 2 million tonnes of
coal per annum would provide sufficient fuel for a 200 MW power
station.
SUMMARY OF THE INVENTION
[0006] In one aspect the invention provides a hybrid method for
producing energy from a carbonaceous material including the steps
of: [0007] (i) heating the carbonaceous material under a reduced
oxygen atmosphere in a distillation plant to generate distillate
vapours; [0008] (ii) processing the resulting distillate vapours;
[0009] (iii) transferring the char residue from the distillation
plant to a power station boiler; and [0010] (iv) combusting the
char residue in the power station boiler for the generation of
electrical power.
[0011] In one embodiment, the char residue is transferred to a
power station boiler while the char residue retains heat from the
heating in the distillation plant.
[0012] Suitably, the char residue is transferred from the
distillation plant to the power station boiler by one or more of
double dump valve, pipe and conveyor.
[0013] The flow and progression of the char during transfer is
optionally controlled via, double dump valves, screws, vibration,
compressed air, gravity, heat resistant belt conveyor, chain
conveyer, vibrating conveyer such as a vibrating tube conveyer,
high temperature rotary valves, or any combination thereof.
[0014] The carbonaceous material may be selected from coal, coal
washing rejects, low quality coal such as lignite, oil shale, and
any combination thereof.
[0015] Preferably, the carbonaceous material, when subjected to
destructive distillation, provides a high level of volatile
hydrocarbon components. In some embodiments, up to 30% of the total
energy of the carbonaceous material is converted to liquid and
gaseous hydrocarbon fractions.
[0016] In one embodiment the carbonaceous material is coal.
[0017] In another embodiment the carbonaceous material has less
than 1.0% Mean Maximum Vitrinite Reflectance.
[0018] In a preferred embodiment the carbonaceous material is a
high Liptinite coal.
[0019] In yet another embodiment the carbonaceous material is
heated to between about 400 to about 700.degree. C.
[0020] In a further embodiment, the distillate vapour is reduced in
temperature by heat exchange to a temperature of below about
150.degree. C.
[0021] In another embodiment, the distillate vapour is reduced in
temperature by heat exchange to a temperature of below about
30.degree. C.
[0022] In still further embodiments the distillate is reduced in
temperature to below about 25.degree. C. and yet further
embodiments to about 0.degree. C.
[0023] In another embodiment the carbonaceous material is heated
under reduced pressure.
[0024] Generally, the distillation plant has a retorting means in
which the carbonaceous material is pyrolysed. The atmosphere of the
retort chamber has a reduced level of oxygen gas compared to air.
Preferably the atmosphere of the retort is substantially without
oxygen gas.
[0025] Preferably the char residue is transferred from the
distillation plant to the power plant boiler at a temperature of
between 300 to 700.degree. C.
[0026] In a second aspect the invention provides an integrated
energy conversion system including: [0027] (i) a distillation plant
for the destructive distillation of carbonaceous material to afford
distillate vapours and a char residue; [0028] (ii) a power station
boiler; [0029] (iii) a means of transferring the char residue at a
temperature between 300 to 700.degree. C. from the distillation
plant to the bed power station; and [0030] (iv) collection means
for the distillate vapours.
[0031] In one embodiment the means for collection of the vapours is
by condensation of a condensable portion of the vapours. The
vapours may be condensed through heat exchange. The distillate
vapours may be condensed to provide a liquid hydrocarbon distillate
fraction.
[0032] The power station may be a conventional power station or a
fluidised bed power station.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Preferred embodiments of the invention will be described
with reference to the accompanying drawings, of which:
[0034] FIG. 1: Represents an overview of the general business
method;
[0035] FIG. 2: Illustrates an overview of the hybrid energy system
process;
[0036] FIG. 3: Shows a schematic of the removal of ammonias;
[0037] FIG. 4: Illustrates a schematic of the processing of the
hydrocarbon distillate fraction otherwise known as "Syncrude";
[0038] FIG. 5: Represents a schematic of the generation of
electrical power from char residue;
[0039] FIG. 6: Represents a schematic of the production and
purification of manufactured gas;
[0040] FIG. 7: Illustrates an overview of the upgrading of coal
distillate;
[0041] FIG. 8: Shows a schematic of the integrated energy system;
and
[0042] FIG. 9: Shows an alternative schematic of the integrated
energy system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] Referring to the drawings it will be appreciated that the
invention may be implemented in various forms, and that this
description is given by way of example only.
[0044] Turning to the drawings, FIG. 1 shows a schematic of process
steps for producing coal derived fuels, whereby coal from a coal
mine 1.0, is transferred to a distillation plant having a
distillation means, for example, a retort, 2.0 where the coal is
pyrolysed. The products of the pyrolysis of coal may be variously
processed. Generally, the destructive distillation of coal
generates distillate vapours, which upon reduction in temperature
to a more or less ambient temperature (298 K), such as through heat
transfer condensation processes, provides a gaseous fraction, a
liquid fraction. There is also the remaining char residue. The
liquid fraction may further be separated into a liquid hydrocarbon
fraction and an aqueous liquid fraction. For example, the
distillate, including useful by-products 9.0, and gaseous and
condensable synfuels 5.0 can be further processed into manufactured
gas 6.0--usually a mixture of hydrogen gas and hydrocarbons
syncrude 7.0--a condensable synthetic liquid hydrocarbon fraction
(at ambient temperature) and an aqueous liquid fraction containing
sulphurous and nitrogenous products. The relative amount of the
aqueous fraction generated may depend on, for example, the water
content of the coal pyrolysed, or, whether or not the distillation
is assisted by steam. Other processes such as aqueous scrubbing
also generate aqueous fractions. Manufactured gas produced by
destructive distillation has been variously known, for example, as
illuminating gas or coal gas. Manufactured gas produced by
destructive distillation of, for example, coal or peat, is usually
a mixture of hydrogen gas and hydrocarbons. Manufactured gas
produced from destructive distillation processes should not be
confused with other synthetic gases such as "water gas" (a mixture
of carbon dioxide and H.sub.2 formed by the reaction of water with
carbon monoxide) or syngas (a mixture of carbon monoxide and
H.sub.2 produced from the reaction of methane with steam). Hydrogen
gas may be prepared from manufactured gas. The method of producing
H.sub.2 from hydrocarbons is referred to as "steam reforming" (7.3)
or "catalytic oxidation" and on an industrial scale is the dominant
method for producing H.sub.2.
[0045] As mentioned, the gaseous fraction, produced by the
destructive distillation process, is usually a mixture of low
molecular weight hydrocarbons and hydrogen gas, and other gases
such as carbon monoxide and carbon dioxide. The relative percentage
of hydrogen gas (H.sub.2) and gaseous hydrocarbons (represented,
for example by the chemical formulae: C.sub.nH.sub.2n+2 and
C.sub.2H.sub.2' wherein n is an integer) may vary depending upon
the temperature of distillation, and upon the pressure (typically
reduced pressure) at which the distillation is conducted.
Generally, illuminating gas consists mainly of methane, ethylene
and hydrogen. The relative amounts of hydrocarbon components to
H.sub.2 in gas produced by destructive distillation may vary with
an increase in temperature. It is usually observed that an increase
in temperature will bring an increase in the amount H.sub.2 gas
produced, with a decrease in hydrocarbon gas. The gaseous
hydrocarbon component has been shown (for example for bituminous
coal) to decrease from about 50% at about 400.degree. C. to about
35% at about 900.degree. C. Whereas the percentage of H.sub.2 over
the same range increases from about 20% to about 55%. Typically, as
temperatures of greater than 600.degree. C. are reached, the
hydrocarbon components are more prone to decomposition. However,
this may depend upon the pressure (reduced or otherwise) under
which the distillation is conducted.
[0046] The remaining char residue 3.0--a high calorific fuel, is
transferred to a power station where it is combusted in a boiler
for the production of electricity 8.0. The power station may be a
conventional power station or a fluidised bed power station. Before
transfer to the power station, some of the char residue may also be
partially reacted with superheated steam for the generation of
hydrogen gas. In such a case, the remaining char residue is
transferred to the power station after this process step has been
completed.
[0047] In the FIG. 2 schematic, a schematic shows that coal 1.3 is
mined 1.2 from a coal mine 1.0, and then transported 1.4 to the
distillation plant. Coals with a liptinite content are generally
regarded as providing greater quantities of syncrude on destructive
distillation. However other coals, such as the brown coal lignite,
are also suitable. In general, lower rank coals, or coals with a
Mean Maximum Vitrinite Reflectance of less than 1% are preferable
for the processes described herein. Coals with a high ash content
are also tolerated. Generally, carbonaceous materials such as coal
washing rejects, lignite, oil shale or combinations thereof, are
suitable for use in the present invention. Preferably, the
distillation plant and power station are near a source of feed
material. The coal 1.3 is transferred 1.4 to the pyrolysis chamber
of the retort 2.1 of the distillation plant. The feed coal 1.3 may
be used in the pyrolysis chamber substantially as it arrives from
the mine 1.0, that is, as raw, unwashed coal. Using raw coal may
result in significant savings in constructional, operational and
capital costs. It is not necessary to pulverise the feed coal to
the dust fraction size, for example, as used in Pulverised Fuel
Power stations. Coal crushing to a top size of 6 mm may only be
required, thus providing an additional capital and operating cost
savings. The coal may be preheated before the distillation chamber
is charged. Preferably, the coal is transferred to the retort 2.1
by gravity feed 1.4. Gases and other volatile hydrocarbons are then
distilled from the coal by the process of low temperature
carbonisation, otherwise known as destructive distillation 2.2. The
distillation may be conducted under reduced pressure and is
preferably conducted within a temperature range of about
400-700.degree. C. The raw manufactured or "synthetic" gas 6.1, and
the condensable hydrocarbon fraction-syncrude 7.0, are separated by
a heat exchange condensation process 5.1. The syncrude can be
further processed to provide, for example, oils, fuels and bitumen.
The syncrude can be, for example, further fractionally distilled
into many fractions to yield a number of useful organic products,
including benzene, toluene, xylene, naphthalene, anthracene, and
phenanthrene. Raw distillates, may form the starting point for the
synthesis of numerous further products. The residual pitch left
from the fractional distillation may used for paving, roofing,
waterproofing, and insulation. The specific gravity of the liquid
distillate may vary depending on factors such as: the temperature
at which the carbonisation is conducted, and how the fractions are
condensed or collected. Residuum formed from the further
distillation of coal distillation liquids may have an even higher
specific gravity.
[0048] The condensation process also allows for extraction of
ammonia 5.2 in an aqueous fraction. The raw manufactured gas 6.1
can be subjected to further purification processes 6.2 such as
extraction of nitrogenous and sulphurous gases and filtration of
particulate matter to provide a clean manufactured gas 6.3. The
manufactured gas can be used as fuel in the boiler of the fluidised
bed power station (FBPS) 6.5, can be used to heat the retort 6.4,
can be sold as a high energy fuel, and can further processed. For
example, manufactured gas can be catalytically reformed for the
synthesis of fertilisers and methanol. The nitrogen and sulphur
components of the coal can be recovered 6.6 as useful by-products
6.7. After the volatile materials have been distilled from the
coal, the char residue is transferred 3.1 from the pyrolysis
chamber 2.1 to a power station boiler, such as a fluidised bed
power station boiler 4.1, where it is combusted to generate steam
4.2 to drive a turbine 4.3 for the generation 4.5 of electricity
8.0.
[0049] In the FIG. 3 schematic, after pyrolysis of the coal, the
gas leaving 2.2 the pyrolysis chamber 2.1 may be quenched with a
spray of aqueous liquor (flushing liquor) 5.1.0 which results in a
liquid condensate stream 5.2.1 and a gas stream 6.1. As the raw
retort gas is cooled, hydrocarbon vapour can condense forming
aerosols, which are carried along with the gas flow. Electrostastic
precipitators can be used to charge the particles which may then
collected from the gas by means of electrostatic attraction. The
raw gas 6.1 and the flushing liquor are then separated and flow to
by-product plants for treatment. Ammonia can be separated from the
gas stream for example in the form of ammonium sulphate 6.2.1. The
generation of ammonium sulphate can take various forms, for
example, by contacting the gas stream with sulphuric acid.
Alternatively the ammonia can be removed from the gas stream by
scrubbing with water. Scrubbing with water further removes some
hydrogen sulphide and hydrogen cyanide from the gas stream. The
water-wash ammonia process is improved at lower gas temperatures.
The ammonia solution can be processed in a still to provide a
concentrated ammonia solution or to form ammonium sulphate. Another
related process is the removal of ammonia from the gas stream using
a solution of mono-ammonium phosphate. This process produces
saleable anhydrous ammonia. Light oils and naphthalene can also be
scrubbed from the gas stream, for example, by using a wash oil. The
light oils and naphthalene can be stripped together or as separate
fractions. The light oil may also be left in the gas to increase
its calorific value. The flushing liquor is transferred to a liquor
plant. The hydrocarbon fraction can be separated from the aqueous
fraction by decantation 5.2.2. The aqueous flushing liquor can then
be processed to provide ammonia which can be fed back into the gas
stream upstream of the ammonia strip, or can be otherwise
integrated into the ammonia processing system. The liquor can be
further processed to remove components such as basic nitrogeneous
hydrocarbons (e.g. pyridines), phenols and cyanides, or treated
on-site, for example, in a biological effluent plant.
[0050] In the FIG. 4 schematic, the liquid condensable fractions of
hydrocarbons are collected 5.1 and the aqueous phase separated from
the organic phase 5.2.1. The aqueous phase is likely to contain
some water-soluble hydrocarbons such as phenols and nitrogenous
bases which can be recovered. Phenols, for example, can be
recovered by conversion to their sodium salts by reaction with
NaOH. Nitrogenous bases can be similarly recovered as salts by
reaction with an appropriate counterion. Due, for example, to their
different densities, the phases may be separated, by using a
separation funnel or drain, or by centrifugation. The generally
hydrophilic and hydrophobic nature of the respective liquid aqueous
and liquid hydrocarbon fractions may also assist their separation
from each other. After separation from the aqueous phase, the
liquid hydrocarbon "syncrude" fraction 7.0 component can be
transferred to an oil refinery 7.1 where it is further processed
into, for example, oils, fuels such as petroleum fuels, and
bituminous components. As mentioned, the aqueous fraction 5.2.2 is
a source of ammonia and water soluble hydrocarbons such as phenols
and nitrogenous bases 6.7.
[0051] Alternatively, the pyrolysis of coal may be aided by steam
injection 2.3. The steam is led in, optionally at the top, along
the sides, or the bottom of the retort, through a valve or valves
to take care of the thermal expansion. The steam and gas are led
through a hot heat exchange unit or condenser 5.1 (n=1) where the
heavy oils are taken out providing a first liquid distillate
fraction. The remaining gases, or distillate vapours, then go to a
cold condenser where the steam and oils are condensed 5.1 (n=2) to
provide a second liquid distillate fraction comprised of an aqueous
and organic phase. The remaining gas is then led off. The hot
condenser reduces the temperature of the gases to about 150.degree.
C. The cold condenser is designed to reduce the temperature of the
gases to from about 25.degree. C. to about 50.degree. C. The
temperature of the coolant, typically water, is up to 25.degree. C.
but may be as low as about 0.degree. C. The finishing point of the
distillation may be at various stages and with regard to various
objectives. The condensed liquid goes to the separator where the
liquid hydrocarbon distillate fraction or "syncrude" 7.0 and the
aqueous distillate fraction 5.2.2 are separated 5.2.1. The syncrude
is taken to the crude storage tanks before being, for example,
cracked and refined 7.1. Hydrogen gas formed from, for example, the
destructive distillation of coal, or by the reaction of superheated
steam with char residue, may be used in catalytic hydrogenation
processes to upgrade syncrude products resulting from destructive
distillation.
[0052] In the FIG. 5 schematic, the char residue is transferred 3.1
from the retort to a FBPS boiler. The char residue is a high energy
source fuel, similar to coke and has a higher calorific value than
coal itself. The char residue also provides a high energy fuel with
negligible water content. Preferably the char residue is
transferred to the boiler heated, that is, at or about the
temperature at which destructive distillation was conducted, which
is usually up to about 700.degree. C. By transferring the char
residue from the distillation plant pyrolysis chamber to the
fluidised bed power plant boiler at or about the distillation
temperature, significant energy savings are achieved, as the heat
energy of the char residue is not lost. Preferably the fluidised
bed power station is in close proximity to the distillation plant,
more preferably it is within 100 metres of the distillation plant,
even more preferably it is next to the distillation plant. The
retort of the distillation plant may be located above the boiler of
the power station such that a minimum transfer distance is required
to move the hot char from the retort to the boiler. The retort and
boiler may be connected, for example, by a double dump valve. More
than one retort may be located within the vicinity of the boiler in
order to provide, as required, sufficient char residue to fire the
boiler. A positive pressure of an inert gas, such as nitrogen, in
the direction of the char flow, helps to avoid unwanted gases from
the boiler entering the retort chamber. The char residue may be
piped or transported by heat resistant conveyor from the
distillation plant to the fluidised bed power station boiler. The
char flow may be controlled via screws, double dump valve,
vibration, compressed air, gravity, high temperature rotary valves,
heat resistant belt conveyor, chain conveyer, vibrating conveyer
such as vibrating tube conveyer, or any combination of the above
means. The char residue is then combusted in the fluidised bed
boiler in order to produce energy 4.2.1 in the form of steam in
order to drive a turbine 4.3 in order to generate 4.5 electricity
8.0. Often, the hot char residue 3.1 is combined with a sorbent
4.1.1, for example limestone, in the fluidised bed boiler 4.1. The
sorbent further minimises sulphur emissions by reacting with
sulphurs to produce a coal combustion by-product 4.1.2. Coal
combustion products (CCPs) are the inorganic residues that remain
after coal is combusted, and include sorbent materials used in
fluidised bed boilers. Examples of CCPs are (bottom ash, boiler
lag, fly ash). CCPs can be successfully used in cements and
concrete. Components of CCPs have different physical and chemical
properties that make them suitable for different applications.
Examples of applications are as synthetic gypsum in wall board
manufacture, mine reclamation, road bases, and structural fill.
Flue gas emission from the boiler can be further controlled by
pre-emission purification of the gas stream to remove particulate
matter and noxious gases 4.2.2 before being sent to the stack
4.2.3. One flu-gas desulphurisation method uses ammonia as the
sorbent. The product is ammonium sulphate. Sulphate is the
preferred form of sulphur readily assimilated by crops and ammonium
sulphate is the ideal sulphate compound for soil supplements
because it also provides nitrogen from the ammonia. Copper oxide is
another regenerable sorbent to capture sulphur dioxide from flue
gases in order to collect sulphur as a saleable by-product such as
for example, elemental sulphur, ammonium sulphate fertiliser or
sulphuric acid. Copper oxide can also catalytically reduce nitrogen
oxides. Alternatively, sulphur can be removed from flue gas through
the use of sorbents, such as metal oxide or calcium-based sorbents,
or through the use of sulphur dioxide reduction catalysts. Other
metal salts such as zinc titanate or zinc ferrite may be used to
create metal sulphides which can be processed to regenerate the
metal salts for reuse and concentrated SO.sub.2. Harmful gaseous
nitrogenous components such as NO.sub.x can be removed by processes
such as Selective Catalytic Reduction (SCR) with ammonia, or by
selective non-catalytic reduction (SNCR) or equivalent. Selective
non-catalytic reduction (SNCR) is a post combustion method of
controlling NO.sub.x emissions in which ammonia or urea is mixed
with air or steam and injected into a combustion chamber at high
temperatures where it reacts at high temperatures with NO.sub.x to
produce nitrogen and water. By the SCR process, ammonia is injected
into the flue gas where it reacts with NO.sub.x in the presence of
a catalyst, such as titanium or vanadium to produce nitrogen and
water.
[0053] In the FIG. 6 schematic, after condensation of the
condensable hydrocarbon fraction 5.1, the raw manufactured gas 6.1
can be filtered to remove particulate matter 6.2.1. Particulate
emissions can be controlled by electrostatic precipitators (ESPs)
and fabric filters (e.g. bag-house filters). ESPs are common
devices for particulate control and have been commercially applied
to collect dusts, fumes and mist particles. Fabric filters can
achieve a high collection efficiency. A number of different filter
media available for different filtering applications. Advanced gas
flow distribution systems for fabric filters can eliminate abrasion
and thus reduce bag wear. Hybrid systems combine electrostatic
precipitation with fabric filtration to achieve high particulate
removal efficiencies at low costs. Other methods include, and
ceramic filters, cyclone filters and wet scrubbers including
venturi, jet and EDV scrubbers. Before or after particulate
filtration, sulphurous components can be extracted from the gas
stream. HCN and COS can be removed via a hydrolysis reactor 6.2.2,
acidic gas (e.g. H.sub.2S) can then be absorbed from the gas stream
6.2.3 and through, for example, the Claus process 6.7.2, can be
converted to elemental sulphur and then to sulphuric acid.
Typically, the Claus process produces elemental sulfur by burning
H.sub.2S in the presence of a catalyst and recovering the sulfur
from the resulting vapour as a condensate. Hydrogen sulfide
(H.sub.2S) is a smelly, corrosive, highly toxic gas. H.sub.2S is
commonly found in natural gas and is also made at coal power
stations, especially if the coal contains a lot of sulfur
compounds. Because H.sub.2S is such an obnoxious substance, it is
converted to non-toxic and useful elemental sulfur at most
locations where it is produced. Claus sulphur recovery units can be
combined with various tail gas units, for example: Beavon Tail Gas
Unit and Selective Amine Tail Gas Unit. For boilers operating with
heavy residue and coke containing large amounts of sulphur,
recovery of the sulphur in the form of sulphuric acid becomes an
attractive alternative. As mentioned, process economy is improved
by increasing sulphur content due to the recovery of the heat of
reaction and due to the sales value of the sulphur, in this case
sulphuric acid product. Sulphur in the form of sulphuric acid can
also be extracted from coal gases by the wet sulphuric acid (WSA)
process (Topsoe). In short, the WSA Process is a catalytic process
which converts H.sub.2S and CS.sub.2 into SO.sub.2 as a first
stage. SO.sub.2 is then converted into SO.sub.3, and the SO.sub.3
reacts with the water vapour and is condensed as concentrated
sulphuric acid of commercial quality (94-97% wt depending on actual
design conditions). A large variety of sulphur containing effluents
for example: hydrogen sulphide rich gases, Claus process tail
gases, and boiler flue gases may be treated by this method. The
process is also suitable for the treatment of sulphur containing
gases with a high hydrocarbon content. The WSA process may be used
in conjunction with the Claus process. In the Smoven process, coal
gas is fed into an entrained-flow reactor containing a Zn-based
sorbent, where sulphur components are absorbed leaving clean
manufactured gas which passes through. When saturated with sulphur,
or when reactivity is insufficient for practical sulphur removal,
the sulphided sorbent passes to a separate reactor where it is
regenerated in an oxygen rich atmosphere. The regenerated sorbent
is then transferred back to the entrained-flow reactor to take part
in another sorbent cycle. The regeneration reaction produces a tail
gas rich in SO.sub.2 which may be used in the production of
elemental sulphur, liquid SO.sub.2 or sulphuric acid. Other
processes for the removal of hydrogen sulphide include absorption
with potassium carbonate solution, absorption with an ammonia
solution, or absorption with monoethanolamine solution.
[0054] Turning to FIG. 7, generally, the range of products of
destructive distillation includes the following: fuel gases; light
gasoline; naphtha; kerosene; diesel; and residuum 7.5.
[0055] The liquid distillate fraction or "syncrude" can be further
refined through one or more upgrading processes. One such upgrading
process is fractional distillation 7.2. Other upgrading processes
include cracking processes and hydrotreating processes 7.4. Prior
to the commencement of the refining, the stored syncrude can
cleaned of contaminants such as sand and water and if required can
be preheated through heat exchange processes such as passing the
syncrude via a pipe through or by a heat generating body.
[0056] The heated syncrude can be upgraded by using heat to produce
chemical splitting of the syncrude into combustion gas (furnace
fuel gas), liquid products, and residuum (solid, complex
hydrocarbons that often end up as asphalt). The syncrude can be
upgraded (7.4) by catalytic hydrogenation in the presence of a
partial pressure of hydrogen gas. The hydrogen required for
catalytic hydrogenation can be generated by steam reformation 7.3
of manufactured gases or can be generated, for example, from the
reaction of superheated steam with hot char residue.
[0057] In general, in the refining process, the longer the
hydrocarbon molecule, the higher the boiling point. The temperature
needed to boil out gasoline might be only 40 Celsius while a
temperature of over 400 Celsius might be needed for heavy gas oil.
The different boiling points of substances can be used to
fractionally separate them by fractional distillation 7.2 in a
fractionating unit such as a fractionating tower. For example, the
following substances (lightest to heaviest or from the top of the
tower to the bottom) are produced: off gas, straight run gasoline
(composed of molecules with about 5 to about 10 carbons in length),
kerosene distillate (with molecules of about 11 to about 15 carbons
in length), light gas oil (about 13 to about 17 carbons), and heavy
gas oil (about 18 to about 25 carbons), used for lubricating
oils.
[0058] Collecting trays located at intervals up the tower collect
products according to their density, with the least dense products
such as off gas and straight run gasoline being trapped and
siphoned off closer to the top of the fractionating tower, with the
heavier materials such as the gas oils being taken off closer to
the tower's bottom.
[0059] The heavy residuum (26 to over 60 carbons), however, may be
subjected to even more refining. The residuum can receive more
heating in a vacuum tower, where light vacuum gas oil and heavy
vacuum gas oil can be extracted from it. Tarry solids can be sent
through another heat exchange and then subjected to hydrocracking
processes 7.4. For example, the residuum can be subjected to
pressure, heat, catalysts, and hydrogen gas (which assists in
breaking down the extremely complex hydrocarbon bonds in the
residuum). Further gases and liquids are produced. The gases
include: hydrogen sulfide from which sulfur can be extracted and
gas that can be collected for use as furnace fuel. The collected
liquids are re-directed back to the fractionating unit. The
products of fractional distillation can be subjected to further
upgrade such as hydrotreating and hydrocracking, and the products
of hydrotreating and hydrocracking can also be further subjected to
fractional distillation.
[0060] A hydrotreater is one "upgrading" process unit in a refinery
that is used to treat products such as gasoline, kerosene and
diesel and intermediates such as gas oil. A hydrotreater uses
hydrogen to saturate aromatics and olefins as well as to remove
undesirable compounds of elements such as sulphur and nitrogen.
[0061] Typical major elements of a hydrotreater unit are a heater,
a fixed-bed catalytic reactor and a hydrogen compressor. The
catalyst promotes the reaction of the hydrogen with the sulfur
compounds such as mercaptans to produce hydrogen sulphide or
H.sub.2S, which is then usually bled off and treated with amine in
an amine treater. The hydrogen also saturates hydrocarbon double
bonds, which helps raise the stability of the fuel.
[0062] A hydrocracker is a somewhat similar upgrading refinery unit
that uses a higher severity such as a stronger catalyst and higher
pressure to crack hydrocarbon molecules into smaller ones, for
example to convert gas oil and diesel to lighter hydrocarbons such
as gasoline blending stocks and butanes. A hydrocracker usually has
a hydrotreater as the first step to remove the sulfur and nitrogen
compounds that could act as a poison to the hydrocracking
catalyst.
[0063] Hydrocracking is assisted by the presence of an elevated
partial pressure of hydrogen. The products of this process are
saturated hydrocarbons. The products of this reaction process
depend on the reaction conditions (temperature, pressure, catalyst
activity) used. Products may range from range ethane and LPG, to
heavier hydrocarbons such as isoparaffins. Hydrocracking may be
facilitated by a bifunctional catalyst that is capable of
rearranging and breaking hydrocarbon chains as well as adding
hydrogen to aromatic and olefins to produce naphthenes and
alkanes.
[0064] Major products from hydrocracking are jet fuel, diesel,
relatively high octane rating gasoline fractions and LPG. These
products may have a very low content of sulphur and other
contaminants. Fuel hydrocarbons derived from syncrude may include a
variety of refined petroleum products. For example, gasoline
contains hundreds of hydrocarbon compounds, some heterocyclic
compounds. The hydrocarbon compounds are mainly C.sub.5 to C.sub.12
chains of carbon and hydrogen atoms that have boiling points in the
range of 23.degree. to 200.degree. C. Petroleum engineers usually
classify hydrocarbons in three groups, paraffins (straight chain
and cyclic saturated hydrocarbons, i.e., no double bonds present),
olefins (unsaturated hydrocarbons, i.e., compounds that contain
double bonds), and aromatics (compounds that consist of benzene
rings). The exact composition of gasoline varies greatly and
depends on its crude source and the method of manufacture. Benzene,
toluene, ethylebenzene and xylenes (BTEX) can occur in gasoline
through the distillation process and also are added for their
antiknock characteristics and octane enhancement. BTEX compounds
may make up about 16% of gasoline by weight.
[0065] Diesel is composed of hydrocarbons that have boiling points
between about 200.degree. and about 300.degree. C. Diesel contains
larger hydrocarbons than gasoline with carbon numbers that may
range from about 10 to about 19. Fuel oil is a term used for a
variety of petroleum products. Fuel oils include kerosene, stove
oil, furnace fuel oil, diesel, and bunker oil. Bunker oil is a
heavy fuel oil used to power ships. Fuel oils may be distillate
oils like diesel, kerosene, furnace fuel oil, and stove oil, or
residual oils like bunker oil. Distillate oils are vaporised and
condensed during the distillation process from crudes, and
therefore have a definite boiling point range. Residual oils
contains residue from the distillation of crude. As a result,
residual oils contain high boiling and asphaltic components. Jet
fuel, for example, is typically made by blending naphtha, gasoline,
and kerosene according to specifications set by the military and
commercial aviation. The composition of jet fuels will vary greatly
depending on the source and method of manufacture.
[0066] Turning to FIG. 8, a schematic of the integrated energy
conversion system is shown including a distillation plant with a
retort 2.0, a power station including a boiler 4.1, a means for
transferring char residue 3.1, and a collection means for the
distillate vapours 5.1. In general, the hot char exits from the
bottom of the retort and is transferred to the boiler of a power
station. As shown in the alternative schematic of FIG. 9, the hot
char may be transferred via a dual valve system whereby an opening
at 2.01 opens to allow the egress of the char residue into an
intermediate transfer section denoted by 3.1. The size of the
intermediate transfer section will depend on the amount of coal
being pyrolysed during the retorting process. The valve at 2.02
opens to allow the char residue to enter the power station boiler.
Such a valve system is known as a double dump valve system. The
char residue may be transferred via a conveyer section as shown at
3.1 of FIG. 8. The char exits the retort at 2.01 and is transferred
onto a conveyer 3.1 at 2.02. The conveyer at 3.1 may be a pipe
angled to provide gravity assistance to the transfer of the hot
char. The transfer of the char from the retort to the conveyer may
also be a dual valve process such as with a double dump valve. The
distillate vapours exit the retort and condense via heat exchange.
As previously discussed, depending on the reduction in temperature
accomplished by the heat exchange process, there may be further
liquid hydrocarbon fractions isolable, is addition to gaseous
fractions. Gases can continue through the chamber 5.1 for further
processing. The liquid distillate residue is collected (5.1) and
the hydrocarbon fraction is further processed for upgrading. The
hydrocarbon distillate can be transferred (5.10) for upgrading by
fractional distillation (20.2) in a distillation tower (20.0) to
provide hydrocarbon fractions as final products or materials may be
further upgraded, or, the liquid hydrocarbon distillate fraction
can be transferred such as by piping (5.12), directly from 5.1 to a
hydrocracking plant to be cracked, optionally preceded by
hydrotreating. The hydrocracked distillate can then be transferred
(5.14) to a distillation tower (20.0) and further fractionally
distilled to provide synthetic fuels 7.5. The direction of the
arrow at 20.1 is representative of the range of different boiling
points of different hydrocarbon fractions. The perpendicular arrows
at 20.2 are representative of the different boiling fractions being
bled off (separated).
* * * * *