U.S. patent application number 14/115376 was filed with the patent office on 2014-03-27 for process and plant for the production and further treatment of fuel gas.
This patent application is currently assigned to OUTOTEC OYJ. The applicant listed for this patent is Andreas Orth, Agnes Von Garnier. Invention is credited to Andreas Orth, Agnes Von Garnier.
Application Number | 20140083010 14/115376 |
Document ID | / |
Family ID | 45952498 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140083010 |
Kind Code |
A1 |
Orth; Andreas ; et
al. |
March 27, 2014 |
PROCESS AND PLANT FOR THE PRODUCTION AND FURTHER TREATMENT OF FUEL
GAS
Abstract
A process for producing fuel gas and for carrying out a
metallurgical process includes providing first and second process
stages. In the first process stage, biomass is reacted with an
oxygen-containing gas so as to obtain a fuel gas containing at
least one of carbon monoxide, hydrogen, carbon dioxide and steam.
The fuel gas is cooled to a temperature in a range from 300 to
600.degree. C. The cooled fuel gas is subjected to a solids
separation. In the second process stage, the fuel gas after the
solids separation is directly supplied to at least one burner of
the metallurgical process, the temperature of the fuel gas being
maintained above the condensation temperature of tar and within the
range from 300 to 600.degree. C. by supplying heat.
Inventors: |
Orth; Andreas;
(Friedrichsdorf, DE) ; Von Garnier; Agnes;
(Oberursel, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Orth; Andreas
Von Garnier; Agnes |
Friedrichsdorf
Oberursel |
|
DE
DE |
|
|
Assignee: |
OUTOTEC OYJ
Espoo
FI
|
Family ID: |
45952498 |
Appl. No.: |
14/115376 |
Filed: |
March 29, 2012 |
PCT Filed: |
March 29, 2012 |
PCT NO: |
PCT/EP2012/055599 |
371 Date: |
November 4, 2013 |
Current U.S.
Class: |
48/111 ;
48/209 |
Current CPC
Class: |
C10J 2300/1884 20130101;
C10J 2300/1892 20130101; Y02P 10/20 20151101; C10J 2300/0976
20130101; Y02P 10/216 20151101; C10J 3/482 20130101; C10J 2300/0959
20130101; C10J 2300/093 20130101; C10J 3/86 20130101; C21B 13/0073
20130101; C10J 3/84 20130101; C21C 5/5217 20130101 |
Class at
Publication: |
48/111 ;
48/209 |
International
Class: |
C10J 3/84 20060101
C10J003/84 |
Foreign Application Data
Date |
Code |
Application Number |
May 4, 2011 |
DE |
102011100490.8 |
Claims
1-9. (canceled)
10. A process for producing fuel gas and for carrying out a
metallurgical process, the process comprising: reacting, in a first
process stage, biomass with an oxygen-containing gas so as to
obtain a fuel gas containing at least one of carbon monoxide,
hydrogen, carbon dioxide or steam; cooling the fuel gas to a
temperature in a range from 300 to 600.degree. C.; subjecting the
cooled fuel gas to a solids separation; and directly supplying, in
second process stage, the fuel gas after the solids separation to
at least one burner of the metallurgical process, the temperature
of the fuel gas being maintained above the condensation temperature
of tar and within the range from 300 to 600.degree. C. by supplying
heat.
11. The process according to claim 10, wherein the fuel gas is
cooled to a temperature in a range from 350 to 450.degree. C. and
maintained in the range from 350 to 450.degree. C. in the second
process stage.
12. The process according to claim 10, wherein the biomass is
gasified in a fluidized bed.
13. The process according to claim 10, further comprising at least
partly utilizing steam generated by cooling the fuel gas for power
generation or in the first process stage.
14. The process according to claim 12, further comprising at least
partly utilizing steam generated by cooling the fuel gas as
fluidizing gas in the fluidized bed.
15. A plant for producing fuel gas and for carrying out a
metallurgical process, the plant comprising: a first process stage
including at least one first reactor configured to produce a fuel
gas containing at least one of carbon monoxide, hydrogen, carbon
dioxide or steam and having at least one supply conduit each for
biomass and an oxygen-containing gas; at least one cooling device
disposed downstream from the first process stage; at least one
solids separating device disposed downstream from the at least one
cooling device; a second process stage including at least one
second reactor configured to carry out the metallurgical process
and at least one burner; and a direct conduit from the at least one
solids separating device into the at least one burner of the second
process stage, the conduit being equipped with at least one device
configured to supply heat and maintain a temperature of the fuel
gas above a condensation temperature of tar.
16. The plant according to claim 15, wherein the at least one
cooling device includes a steam generator.
17. The plant according to claim 16, wherein a steam outlet of the
steam generator is connected, via a conduit, with a power
generation stage or the first process stage.
18. The plant according to claim 17, wherein the conduit extends
from the steam generator to the first process stage, and further
comprising a valve disposed in the conduit and configured to
regulate or control a steam quantity.
Description
CROSS-REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a U.S. National Phase Application under
35 U.S.C. .sctn.371 of International Application No.
PCT/EP2012/055599, filed on Mar. 29, 2012, and claims benefit to
German Patent Application No. DE 10 2011 100 490.8, filed on May 4,
2011. The International Application was published in English on
Nov. 8, 2012 as WO 2012/150097 under PCT Article 21(2).
FIELD
[0002] The present invention relates to a process for the
production of fuel gas and for carrying out a metallurgical
process, in which in a first process stage carbonaceous materials,
preferably coal or biomass, are reacted with an oxygen-containing
gas to obtain a fuel gas containing carbon monoxide, hydrogen,
carbon dioxide and/or steam, wherein the fuel gas obtained is
cooled to a temperature of 300 to 600.degree. C., preferably 350 to
450.degree. C., and subsequently supplied to a filtration means,
and wherein in a second process stage the filtered fuel gas is
charged to at least one burner of the metallurgical process, and to
a plant for carrying out this process.
BACKGROUND
[0003] To be able to use fine iron ores for the production of pig
iron or direct-reduced iron (DRI), they are mixed with water and
agglomerated to pellets. The thermal energy necessary for drying
and curing the pellets is provided by the combustion of natural gas
or oil. Many regions in which new pellet plants are being planned
are, however, not connected to a natural gas network, but often
have occurrences of carbonaceous materials, such as coal or
biomass.
[0004] Similar conditions of the local infrastructure, in
particular the availability of carbonaceous materials such as coal
or biomass as the only energy source, can also be found at sites
for other metallurgical processes such as the calcination of
alumina earth.
[0005] As a consequence, it is economically expedient to convert
the existing carbonaceous materials (e.g. coal or biomass) to fuel
gas, so that they are energetically usable for the succeeding
metallurgical process.
[0006] DE 102 60 734 A1 describes a process for the production of
carbonization coke and fuel gas in a fluidized-bed reactor, wherein
the fluidized bed is an annular fluidized bed. The gas velocities
of the first gas and of the fluidizing gas for the annular
fluidized bed are adjusted in a certain ratio relative to each
other, so that solids from the stationary annular fluidized bed are
introduced into an upper region, the mixing chamber region, and
mixed there intensively, before the particles fall back into the
annular fluidized bed.
[0007] EP 0 062 363 A1 describes a process for the production of
fuel gas, in which the by-products obtained can be reduced. First,
gasification is carried out in the presence of steam in a fluidized
bed, the gas formed then is liberated from sulfur compounds, cooled
and dedusted, and then the residue from the gasification is
burnt.
[0008] The gasification of carbonaceous materials--in particular of
coal--to a fuel gas, which substantially consists of carbon
monoxide, hydrogen, carbon dioxide and steam, results in the
formation of tar. The tars contained in the hot gases involve the
risk that they are deposited in plant sections and harden there.
This would first of all lead to a reduction of the conduit
cross-sections and as a result to changed flow conditions, which
renders a regulation and control of the plant much more difficult.
Further deposits might lead to a complete clogging of plant
sections, which represents a considerable safety risk.
[0009] WO 2009/074170 A1 therefore describes that the fuel gas
produced in the gasification of coal first is supplied to a solids
separation and subsequently transferred to a further wash, by means
of which the tar can be removed.
[0010] U.S. Pat. No. 4,461,629 also teaches that after the
gasification of coal the tars present must urgently be removed from
the fuel gas, as otherwise tar deposits and the involved risks will
occur. For this purpose, the fuel gas is introduced into a
fluidized-bed reactor and cooled there. Impurities present, in
particular the tars, are deposited on the particles of the
fluidized bed, while the fuel gas can be cleaned and after cooling
be supplied to the next process step.
[0011] U.S. Pat. No. 4,563,195 on the one hand describes the
possibility of tar removal by washing with cold water, which
however involves the disadvantage that this produces large amounts
of waste water. As an ecologically more expedient variant of tar
removal, on the other hand, a wash with a rather small amount of
water therefore is described, which is effected in that the fuel
gases are passed through a water spray. This has the advantage of a
distinctly lower moisture content of the tars removed in this way,
which allows a burn-off of the tars.
[0012] Various possibilities of the wash, e.g. a RECTISOL wash, are
also known from the general scientific literature, for example from
Joerg Schmalfeld, "Die Veredelung und Umwandlung von
Kohle-Technologien und Projekte 1970 bis 2000 in Deutschland",
Urbanverlag, Hamburg 2008.
[0013] All processes have in common that a use of the resulting hot
fuel gas for a downstream metallurgical process only is possible
when the fuel gas is subjected to an expensive and ecologically not
unproblematic tar removal.
SUMMARY
[0014] The present invention advantageously allows for the coupling
of a fuel gas production with a metallurgical process, without
first having to remove the tar from the fuel gas.
[0015] In an embodiment, the present invention provides a process
for producing fuel gas and for carrying out a metallurgical
process. In a first process stage, biomass is reacted with an
oxygen-containing gas so as to obtain a fuel gas containing at
least one of carbon monoxide, hydrogen, carbon dioxide or steam.
The fuel gas is cooled to a temperature in a range from 300 to
600.degree. C. The cooled fuel gas is subjected to a solids
separation. In a second process stage, the fuel gas after the
solids separation is directly supplied to at least one burner of
the metallurgical process, the temperature of the fuel gas being
maintained above the condensation temperature of tar and within the
range from 300 to 600.degree. C. by supplying heat.
BRIEF DESCRIPTION OF THE DRAWING
[0016] The present invention will be described in even greater
detail below based on the exemplary figure. The invention is not
limited to the exemplary embodiments. All features described and/or
illustrated herein can be used alone or combined in different
combinations in embodiments of the invention. The features and
advantages of various embodiments of the present invention will
become apparent by reading the following detailed description with
reference to the attached drawing which illustrates the
following:
[0017] FIG. 1 shows a schematic diagram of the process according to
an embodiment of the invention.
DETAILED DESCRIPTION
[0018] In accordance with an embodiment of the invention, in a
first process stage, carbonaceous materials, in particular coal or
biomass, are reacted with an oxygen-containing gas, which in
particular can be oxygen, air, compressed air or industrial air (80
vol-% nitrogen, 20 vol-% oxygen), to obtain a fuel gas containing
carbon monoxide, hydrogen, carbon dioxide and/or steam. The fuel
gas thus obtained subsequently is cooled to a temperature of 300 to
600.degree. C., preferably 350 to 450.degree. C., more preferably
380 to 420.degree. C., and in particular 400.+-.5.degree. C. and
supplied to a solids removal. Such solids removal in particular can
be at least one cyclone or a filter device, wherein the use of
candle filters here is particularly useful, since ceramic candle
filters are quite useful for hot gas filtration, because they
hardly show wear phenomena despite the relatively high temperatures
of gas and particles.
[0019] In the sense of this description, the term "carbonaceous
material" means a material whose carbon content preferably
corresponds to at least 25 wt-% of its dry matter, more preferably
at least 30 wt-% of its dry matter, even more preferably at least
35 wt-% of its dry matter, most preferably at least 40 wt-% of its
dry matter, and in particular to at least 45 wt-% of its dry
matter. In a further preferred embodiment, the carbon content in
the carbonaceous material corresponds to at least half its dry
matter.
[0020] In a particularly preferred embodiment, the carbonaceous
materials are coal or biomass (preferably solid biomass) or any
mixture thereof.
[0021] In the sense of this description, the term "biomass" means
organic substances which can also be referred to as "renewable raw
materials". The carbon content of the biomass (preferably solid
biomass) preferably corresponds to at least 25 wt-% of its dry
matter, more preferably at least 30 wt-% of its dry matter, even
more preferably at least 35 wt-% of its dry matter, most preferably
at least 40 wt-% of its dry matter, and in particular to at least
45 wt-% of its dry matter. In a particularly preferred embodiment,
the carbon content in the biomass, preferably solid biomass,
corresponds to at least half its dry matter.
[0022] In a second process stage, the filtered fuel gas then is
charged to at least one burner of the metallurgical process and
used as fuel for this burner. The injection of the fuel gas from
the filtration into at least one burner is effected directly, i.e.
in particular without interconnection of further process/cleaning
stages, wherein the temperature of the fuel gas between filtration
and burner inlet is maintained in the range from 300 to 600.degree.
C., preferably 350 to 450.degree. C.
[0023] The adjustment of the temperature loss is effected by
minimizing the heat losses and/or heat supply. The conduit design
on the one hand is a suitable means for minimizing the heat losses.
In accordance with the invention, the connecting line between
filtration and burner therefore is insulated. On the other hand,
the heat losses can be reduced in that the conduit has a rather
small heat-exchange surface, which can be effected both by a
suitable guidance of the conduit and by a reduction of the conduit
cross-section.
[0024] A heat supply is possible via a direct or indirect heating
of the conduit. A combination of these two measures also is
conceivable.
[0025] By adjusting the temperature of the fuel gas to 300 to
600.degree. C., preferably 380 to 420.degree. C., and particularly
preferably to a value of 400.+-.5.degree. C., the temperature lies
above the condensation temperature of tar. The condensation of tar
detrimental to a stationarily and safely operated process thereby
can reliably be prevented.
[0026] Since the fuel gas subsequently is supplied to a burner,
temperatures are produced by the combustion of the gas at which the
tars are also burnt, so that a purification of the fuel gas no
longer is necessary even in a future process stage. Thus, at least
one cleaning stage of the fuel gas is saved and in addition the
ecological burden is reduced, which in particular in the
conventional washes occurs due to the resulting polluted water.
[0027] As metallurgical process, pelletizing is particularly
useful, for example for iron, or the calcination, as it is used for
example in the production of alumina.
[0028] Furthermore, it was found in an embodiment of the present
invention to be advantageous to gasify the carbonaceous materials
in a fluidized bed, as in this way a sufficiently long retention
time of the solids in the system can be ensured for a high gas
yield and low production of tar. The use of a circulating fluidized
bed is particularly favorable, as the same is characterized by a
very good heat and mass transfer. What has been discovered in an
embodiment of the present invention to be quite particularly
advantageous are systems in which the advantages of a stationary
fluidized bed and a circulating fluidized bed are combined with
each other. Such process is described for example in DE 102 60 734
A1.
[0029] To be able to supply the fuel gas to a filtration at all, it
is necessary to at least partly cool the gas. An energetically
attractive design can herein be achieved in that by cooling the
fuel gas steam is generated and this steam is at least partly
utilized for power generation and/or as moderator in the first
process stage. It is particularly advantageous to utilize a part of
the energy thus generated in the first process stage, in particular
for temperature moderation, and to use the remaining residual
amount of steam for power generation.
[0030] A use in the first preheating stage in particular can
consist in that the steam generated by cooling the fuel gas is at
least partly utilized as fluidizing gas in the fluidized bed of the
first process stage. This has the advantage that the use of a
further gas as fluidizing gas can be omitted.
[0031] The invention furthermore comprises, in an embodiment, a
plant which is suitable for carrying out the process according to
embodiments of the invention. Such a plant includes a first and a
second process stage, wherein the first process stage consists of
at least one reactor for producing fuel gas containing carbon
monoxide, hydrogen, carbon dioxide and/or steam and at least one
supply conduit each for carbonaceous materials and an
oxygen-containing gas. The second process stage contains at least
one reactor for carrying out a metallurgical process, such as
pelletizing or calcination, and at least one burner. Furthermore,
between the first and the second process stage at least one cooling
device and an adjoining solids separating device, in particular a
filtering device, are provided. Via a direct conduit, the solids
separating device is connected with at least one burner of the
second process stage. Heat losses can already be minimized by this
direct conduit.
[0032] To furthermore be able to ensure that the temperature of the
fuel gas does not decrease to a value at which tars condensate out,
the conduit can be equipped with at least one means for minimizing
the heat losses and/or with at least one device for heat supply.
Means for minimizing the heat losses include any form of
insulations or variations of the heat-exchange surface. As heat
supply, any form of direct or indirect heating can be provided, in
particular double-walled tubes with the passage of a heating medium
are recommended for example, or also a conduit design in which the
waste heat of adjacent components is utilized.
[0033] To utilize the energy released in the process during
cooling, it is expedient to design the cooling device as steam
generator, in particular as waste heat boiler.
[0034] The steam thus generated can be supplied from the steam
outlet of the steam generator via a conduit to a power generation
and/or to the first process stage. As a result, the energy released
in the process can be utilized in the process itself either as heat
carrier or as energy carrier.
[0035] It is particularly advantageous when the conduit which leads
from the steam generator to the first process stage includes a
valve for regulating or controlling the steam quantity, as in this
way the temperature within the first process stage can be adjusted
with a simple control variable, namely the steam quantity
supplied.
[0036] Referring to FIG. 1, via conduit 1 carbonaceous materials,
preferably comminuted coal or biomass, in particular solid biomass
is fed into the gasification reactor 3, which in a non-illustrated
manner preferably includes a circulating fluidized bed, and is
gasified there with oxygen or air enriched with oxygen supplied via
conduit 2 in a manner known to the skilled person. The fuel gas
obtained during the gasification is withdrawn from the reactor 3
via conduit 4. Conduit 4 opens into the steam generator 5, which
via conduit 6 is connected with a hot-gas filtration 7, e.g. by
ceramic candle filters. Via conduit 8, the filtered fuel gas
subsequently is transferred into a pelletizing plant 9 with a
temperature of about 400.degree. C.
[0037] Via conduit 10, the steam generator 5 is supplied with
water. The steam obtained due to the heat exchange is withdrawn via
conduit 11. Conduit 11 is split into conduits 12 and 13, wherein
conduit 12 opens into the gasification reactor 3 in which the steam
preferably is used as fluidizing gas. Conduit 13 is the supply
conduit of a turbine 22 for power generation.
[0038] Furthermore, ash is withdrawn via conduit 14 from the
reactor 3, via conduit 15 from the steam generator 5, and via
conduit 16 from the hot gas filtration 7. The ash removed from the
reactor 3 via conduit 14 is the bottom product obtained in the
reactor 3, whereas the two conduits 15 and 16, which each transport
fly ash, open into conduit 17. The collected ash is cooled in the
cooling device 18 and subsequently discharged via conduit 19. As
cooling medium of the cooling device 18 water preferably is used,
which is supplied via conduit 20 and discharged via conduit 21.
[0039] Due to the direct coupling of the gasification with the
metallurgical process, an expensive and cost-intensive wet gas
cleaning and the related disposal of the tar-loaded waste waters or
residual substances can be avoided.
EXAMPLE
[0040] To the coal gasification, 13 t/h of ground coal (grain size
>6 mm) are charged with the following composition:
TABLE-US-00001 Proximate analysis Elemental analysis C.sub.fix: 33
wt-% (dry) C: 78% Volatile components: 27 wt-% (dry) H: 5% Ash: 40
wt-% (dry) S: 0.5% Moisture: 6.7% O: 16.5% (calculated) Upper
calorific value 17 MJ/kg Ash softening temperature:
1400-1500.degree. C.
[0041] In the fluidized bed gasification 21,000 Nm.sup.3/h of fuel
gas (coal gas) with a calorific value of 7.0 MJ/Nm.sup.3 are
formed. The fuel gas is composed as follows: Molar gas
composition
TABLE-US-00002 CO 23.4 CO.sub.2 22.1 H.sub.2 29.0 H.sub.2O 21.4
CH.sub.4 2.5 O.sub.2 0.0 N.sub.2 1.4 H.sub.2S 0.1 COS 0.007 Tars
0.003 Rest 0.09
[0042] In ceramic candle filters, the gas is filtered to a dust
content of >20 mg/Nm.sup.3, preferably 5 mg/Nm.sup.3, and fed
into the burners of the pelletizing plant with a temperature of
420.+-.5.degree. C.
[0043] While the invention has been illustrated and described in
detail in the drawings and foregoing description, such illustration
and description are to be considered illustrative or exemplary and
not restrictive. It will be understood that changes and
modifications may be made by those of ordinary skill within the
scope of the following claims. In particular, the present invention
covers further embodiments with any combination of features from
different embodiments described above and below. Additionally,
statements made herein characterizing the invention refer to an
embodiment of the invention and not necessarily all
embodiments.
[0044] The terms used in the claims should be construed to have the
broadest reasonable interpretation consistent with the foregoing
description. For example, the use of the article "a" or "the" in
introducing an element should not be interpreted as being exclusive
of a plurality of elements. Likewise, the recitation of "or" should
be interpreted as being inclusive, such that the recitation of "A
or B" is not exclusive of "A and B," unless it is clear from the
context or the foregoing description that only one of A and B is
intended. Further, the recitation of "at least one of A, B and C"
should be interpreted as one or more of a group of elements
consisting of A, B and C, and should not be interpreted as
requiring at least one of each of the listed elements A, B and C,
regardless of whether A, B and C are related as categories or
otherwise. Moreover, the recitation of "A, B and/or C" or "at least
one of A, B or C" should be interpreted as including any singular
entity from the listed elements, e.g., A, any subset from the
listed elements, e.g., A and B, or the entire list of elements A, B
and C.
LIST OF REFERENCE NUMERALS
[0045] 1, 2 conduit [0046] 3 reactor (first process stage) [0047] 4
conduit [0048] 5 cooling device [0049] 6 conduit [0050] 7 hot gas
filtration [0051] 8 conduit [0052] 9 pelletizing plant (second
process stage) [0053] 10-17 conduit [0054] 18 ash cooling [0055]
19-21 conduit [0056] 22 turbine
* * * * *