U.S. patent application number 11/600616 was filed with the patent office on 2008-05-15 for gasification of fuel in a slagging gasifier.
This patent application is currently assigned to C166, an LLC Registered in Florida. Invention is credited to William Britton, Herbert Ligon, Frederick J. Murrell, John Simmons, Edward Zawadzki.
Application Number | 20080110090 11/600616 |
Document ID | / |
Family ID | 39367820 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080110090 |
Kind Code |
A1 |
Zawadzki; Edward ; et
al. |
May 15, 2008 |
Gasification of fuel in a slagging gasifier
Abstract
A process for gasification of carbon-containing fuel is taught.
The process includes heating carbon-containing fuel in a container,
introducing air into the container in controlled quantifies to
maintain substoichiometric conditions; removing syngas from the
container and, removing slag from the container.
Inventors: |
Zawadzki; Edward;
(Bradenton, FL) ; Britton; William; (Palm Coast,
FL) ; Ligon; Herbert; (Palm Coast, FL) ;
Murrell; Frederick J.; (Bradenton, FL) ; Simmons;
John; (Naples, FL) |
Correspondence
Address: |
THELEN REID BROWN RAYSMAN & STEINER LLP
P. O. BOX 640640
SAN JOSE
CA
95164-0640
US
|
Assignee: |
C166, an LLC Registered in
Florida
|
Family ID: |
39367820 |
Appl. No.: |
11/600616 |
Filed: |
November 15, 2006 |
Current U.S.
Class: |
48/61 ;
48/210 |
Current CPC
Class: |
C10J 2300/0973 20130101;
C10J 3/506 20130101; C10J 3/723 20130101; C10J 2300/093 20130101;
C10J 3/485 20130101; C10J 3/466 20130101; C10J 2300/0933 20130101;
C10J 2200/15 20130101; C10J 2300/0916 20130101; C10J 2300/0956
20130101; C10J 3/526 20130101; Y02P 20/145 20151101; C10J 2300/0983
20130101 |
Class at
Publication: |
48/61 ;
48/210 |
International
Class: |
C10J 3/48 20060101
C10J003/48; C10J 3/46 20060101 C10J003/46 |
Claims
1. A process for gasification of carbon-containing fuel comprising:
heating carbon-containing fuel in a container; introducing air into
the container in controlled quantifies to maintain
substoichiometric conditions; removing syngas from the container;
and, removing slag from the container.
2. The process of claim 1 wherein the carbon-containing fuel is
coal.
3. The process of claim 2 wherein air is introduced to maintain a
stoichiometric ratio of air to coal of about 0.55 to 0.80
percent.
4. A system for gasification of carbon-containing fuel comprising:
a container; an introduction system for introducing air into said
container in controlled quantities to maintain substoichiometric
conditions; a gas removal system for removing syngas from said
container; and, a slag removal system for removing slag from said
container.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a gasifiers, including
single-stage, entrained flow, slagging type coal gasifiers and a
method for operation thereof.
BACKGROUND OF THE INVENTION
[0002] Generally speaking, gasification is a process that converts
carbonaceous materials, such as coal, petroleum, petroleum coke or
biomass, into fuel gas, or synfuel, which is predominantly carbon
monoxide and hydrogen. The synfuel is suitable for firing steam
generators and similar devices or gas turbines. In a gasifier a
variety of complex chemical reactions occur, but essentially, the
carbonaceous material undergoes three processes, pyrolysis,
combustion and gasification.
[0003] The pyrolysis (or devolatilization) process occurs as the
carbonaceous particle heats up. Volatiles are released and char is
produced, resulting in up to 70% weight loss for coal. The process
is dependent on the properties of the carbonaceous material and
determines the structure and composition of the char, which will
then undergo gasification reactions.
[0004] The combustion process occurs as the volatile products and
some of the char reacts with oxygen to form carbon dioxide and
carbon monoxide, which provides heat for the subsequent
gasification reactions. Pyrolysis and combustion are very rapid
processes.
[0005] The gasification process occurs as the char reacts with
carbon dioxide and steam to produce carbon monoxide and hydrogen.
The resulting gas is called fuel gas or syngas (or wood gas when
fueled by wood) and may be more efficiently converted to energy
such as electricity than would be possible by direct combustion of
the fuel, as the fuel is first combusted in a gas turbine and the
heat is used to produce steam to drive a steam turbine. Also,
corrosive ash elements such as chloride and potassium may be
refined out by the gasification process, allowing high temperature
combustion of the gas from otherwise problematic fuels.
[0006] Four types of gasifiers are currently available for
commercial use: counter-current fixed bed, co-current fixed bed,
fluid bed and entrained flow.
[0007] The counter-current fixed bed ("up draft") gasifier consists
of a fixed bed of carbonaceous fuel (e.g. coal or biomass) through
which the "gasification agent" (steam, oxygen and/or air) flows in
counter-current configuration. The ash is either removed dry or as
a slag. The co-current fixed bed ("down draft") gasifier is similar
to the counter-current type, but the gasification agent gas flows
in co-current configuration with the fuel (downwards, hence the
name "down draft gasifier"). Heat needs to be added to the upper
part of the bed, either by combusting small amounts of the fuel or
from external heat sources.
[0008] In the fluid bed gasifier, the fuel is fluidized in oxygen
(or air) and steam. The ash is removed dry or as heavy agglomerates
that defluidise. The temperatures are relatively low in dry ash
gasifiers, so the fuel must be highly reactive; low-grade coals are
particularly suitable. In the entrained flow gasifier a dry
pulverized solid, an atomized liquid fuel or a fuel slurry is
gasified with oxygen or air in co-current flow. The gasification
reactions take place in a dense cloud of very fine particles. Most
coals are suitable for this type of gasifier because of the high
operating temperatures and because the coal particles are well
separated from one another.
[0009] There are a number of examples patents concerning the
gasification process. One example of a fixed bed gasifier is the
subject matter of U.S. Pat. No. 3,920,417 entitled "Method of
Gasifying Carbonaceous Material", which issued on Nov. 18, 1975.
Another design of fixed bed gasifiers forms the subject matter of
U.S. Pat. No. 4,069,024 entitled "Two-Stage Gasification System",
which issued on Jan. 17, 1978.
[0010] Turning to entrainment-type gasifiers, one example of an
entrainment gasification process is that which forms the subject
matter of U.S. Pat. No. 4,158,552 entitled "Entrained Flow Coal
Gasifier", which issued on Jun. 19, 1979. Another example of an
entrainment gasification process is that which forms the subject
matter of U.S. Pat. No. 4,343,627 entitled "Method of Operating a
Two-Stage Coal Gasifier", which issued on Aug. 10, 1982. Yet
another example of an entrained gasification process is that which
forms the subject matter of U.S. Pat. No. 4,610,697 entitled "Coal
Gasification System with Product Gas Recycle to Pressure
Containment Chamber", which issued on Sep. 9, 1986. Still another
example of an entrained gasification process is that which forms
the subject matter of U.S. Pat. No. 4,680,035 entitled "Two Stage
Slagging Gasifier", which issued on Jul. 14, 1987.
[0011] Although there are various types of gasifiers currently on
the market, there still is a need to improve the gasification
process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic illustration of an embodiment of the
present invention.
DETAILED DESCRIPTION
[0013] An embodiment of the present invention is described herein.
Those of ordinary skill in the art will realize that the following
detailed description of the present embodiment is illustrative only
and is not intended to be in any way limiting. Other embodiments of
the present invention will readily suggest themselves to such
skilled persons having the benefit of this disclosure. Reference
will now be made in detail to an implementation of the present
invention as illustrated in the accompanying drawings. The same
reference indicators will be used throughout the drawings and the
following detailed description to refer to the same or like
parts.
[0014] In the interest of clarity, not all of the routine features
of the implementations described herein are shown and described. It
will, of course, be appreciated that in the development of any such
actual implementation, numerous implementation-specific decisions
must be made in order to achieve the developer's specific goals,
such as compliance with application- and business-related
constraints, and that these specific goals will vary from one
implementation to another and from one developer to another.
Moreover, it will be appreciated that such a development effort
might be complex and time-consuming, but would nevertheless be a
routine undertaking of engineering for those of ordinary skill in
the art having the benefit of this disclosure.
[0015] In the embodiment shown in the FIG. 1 schematic, a combustor
10 is shown. An opening 16 into the combustor 10 receives
pulverized coal. A pulverized coal bin 18 supplies coal via a
conveyor belt 20 to a pulverizer 22. Air from a transport air
blower 24 is mixed with the coal in a venturi eductor 23 and
pneumatically conveyed to a solids mixer/splitter 30. Alkali, such
as hydrated lime [Ca(OH).sub.2] is supplied from bin 26 via
conveyor 28 to a transport line 29 where air from the transport air
blower 24 is mixed with the hydrated lime in a venturi eductor 31.
Other alkali that can be employed are lime, limestone, dolomite,
nacholite, potassium carbonate and trona. The pulverized coal and
hydrated lime are thoroughly mixed in the mixer/splitter 30 and
then are delivered to opening 16 in the combustor 10.
[0016] Controlled gasification of the coal takes place in the
combustor 10 by regulation of air flow 40 from air blower 42. Air
is introduced to maintain a substoichiometric ratio and
particularly at a stoichiometric ratio of air to coal of about 0.55
to 0.80, and most preferably at about 0.60.
[0017] Optionally the injection of steam 52 into the combustor 10
is used to enhance sulfur capture. The steam can be added at a 0.1
to 0.3 steam to fuel weight ratio. The syngas leaves the combustor
10 via conduit 54 at a temperature of about 2000 to about 3000
degrees Fahrenheit. The syngas can then be transferred to a boiler
for further combustion.
[0018] It should be understood that substantial quantities of
nitrogen, sulfur, mercury and other components of the coal are
captured in molten slag so that they do not contaminate the syngas.
Fuel-bound nitrogen which is not captured in the slag forms
nitrogen dioxide, NO.sub.2, but not other nitrogen compounds known
as NO.sub.X. Sulfur in the coal is captured by the hydrated lime so
that it does not form sulfur dioxide, SO.sub.2, in the syngas.
Molten slag from the ash portion of the coal plus the inorganic
alkali compounds are separated in a cyclone chamber 60, and a
molten slag eutectic 34 containing calcium sulfide and other alkali
sulfides from reaction with alkali compounds in the coal ash are
collected at the bottom opening 36 of the combustor 10. The molten
slag is quenched and the ash is sluiced to a settling pond.
* * * * *