U.S. patent application number 11/156863 was filed with the patent office on 2006-07-20 for single vessel blast furnace and steel making/gasifying apparatus and process.
This patent application is currently assigned to LEW Holdings, LLC. Invention is credited to Lloyd E. Weaver.
Application Number | 20060157899 11/156863 |
Document ID | / |
Family ID | 36683069 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060157899 |
Kind Code |
A1 |
Weaver; Lloyd E. |
July 20, 2006 |
Single vessel blast furnace and steel making/gasifying apparatus
and process
Abstract
A blast furnace for use in an apparatus such as a steel making
apparatus or a gasifier includes a vessel including a crucible. The
furnace includes a lance for introducing fuel and oxygen into the
crucible and instrumentation for determining density
characteristics of molten material inside the crucible. In one
embodiment, the blast furnace is able to adjust the input of fuel
and/or oxygen into the crucible based on the measure density
characteristics of the molten material. The blast furnace can also
include structure for cooling and clinkering molten material
discharged from the crucible.
Inventors: |
Weaver; Lloyd E.;
(Harpswell, ME) |
Correspondence
Address: |
PATRICK R. SCANLON;PRETI FLAHERTY BELIVEAU PACHIOS & HALEY LLP
ONE CITY CENTER
PORTLAND
ME
04112-9546
US
|
Assignee: |
LEW Holdings, LLC
|
Family ID: |
36683069 |
Appl. No.: |
11/156863 |
Filed: |
June 20, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60644055 |
Jan 15, 2005 |
|
|
|
Current U.S.
Class: |
266/197 |
Current CPC
Class: |
B01D 45/12 20130101;
F27B 3/225 20130101; Y02P 10/136 20151101; C21B 13/0013 20130101;
F27D 19/00 20130101; F27D 3/18 20130101; C21B 2100/44 20170501;
C21C 5/567 20130101; Y02P 10/134 20151101; C21B 11/08 20130101;
F27D 21/0028 20130101; F27D 17/008 20130101; F27D 3/15 20130101;
F27D 3/16 20130101 |
Class at
Publication: |
266/197 |
International
Class: |
C21B 7/24 20060101
C21B007/24 |
Claims
1. A blast furnace comprising: a vessel including a crucible formed
therein; means for introducing fuel and oxygen into said crucible;
and means for determining density characteristics of molten
material inside said crucible.
2. The blast furnace of claim 1 wherein said means for determining
density characteristics of molten material includes a vertical
array of laser spectrometry sensors mounted in said crucible.
3. The blast furnace of claim 1 wherein said means for determining
density characteristics of molten material includes an oscillating
ball sensor located in said crucible.
4. The blast furnace of claim 1 wherein said means for determining
density characteristics of molten material includes an inclined
nuclear level gage.
5. The blast furnace of claim 1 further comprising a cyclone
positioned adjacent to said vessel for removing particulate matter
from hot gas discharged from said vessel.
6. The blast furnace of claim 5 wherein said cyclone includes a leg
having an end that is immersed in molten material in said
crucible.
7. The blast furnace of claim 6 further comprising means for
heating said cyclone and said leg.
8. The blast furnace of claim 7 wherein said means for heating
comprises electric heaters.
9. The blast furnace of claim 1 further comprising means for
measuring characteristics of hot gas in said vessel.
10. The blast furnace of claim 9 wherein said means for measuring
characteristics of hot gas include a laser spectrometry emitter and
receiver mounted on said vessel.
11. The blast furnace of claim 1 wherein said crucible includes a
tap hole for discharging molten material therefrom.
12. The blast furnace of claim 11 further comprising means for
heating said tap hole to insure said tap hole stays open.
13. The blast furnace of claim 12 wherein said means for heating
comprises electric heaters.
14. The blast furnace of claim 11 further comprising means for
cooling and clinkering molten material discharged from said tap
hole.
15. The blast furnace of claim 1 further comprising means for
heating said crucible.
16. The blast furnace of claim 15 wherein said means for heating
comprises electric heaters.
17. A process comprising: providing a vessel including a crucible
formed therein; introducing fuel and oxygen into said crucible;
combusting said fuel in said crucible to produce molten material;
and determining density characteristics of molten material inside
said crucible.
18. The process of claim 17 further comprising adjusting the input
of fuel and/or oxygen into said crucible based on the density
characteristics of molten material inside said crucible.
19. The process of claim 18 further comprising using laser
spectrometry to measure characteristics of hot gas inside or
outside of said vessel.
20. The process of claim 18 further comprising discharging molten
material from said crucible and cooling and clinkering molten
material discharged from said crucible.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/644,055, filed Jan. 15, 2005.
BACKGROUND OF THE INVENTION
[0002] This invention relates to the control of continuous and
direct iron-making or gasification using ground coal, iron ore
(where applicable), flux and other materials and unique sensors and
computer control techniques and methods in a continuous
gasification or smelting process through the judicious application
of these specialized sensors and techniques to make an efficient
and compact and less costly technology, whether making steel or
syngas, that does not require people to interface with the process
directly whereby they are needed only to keeping the lock hoppers
full of feed ingredients, two lock hoppers are used for each
ingredient to insure continuous and interrupted feeding of
materials, and to keep equipment in good repair.
[0003] Much of present steel making is manually controlled with
manual sampling of steel quality, manual control of molten levels
within the furnace, long time lags, high expense of apparatus since
coke and recuperator and other equipment not required of this
invention are needed. Also, labor costs are higher with existing
technology. Present steel-making apparatus, not being continuous,
are not as well suited to recovery of slag materials, which is made
easier with continuous and separately controlled molten slag and
metal outflows, including metal recovery from the coal or carbon
gasifiers if syngas is the product i.e. gasification of
carbonaceous materials.
[0004] Present gasification apparatuses lack the simplicity of a
molten bed approach plus the sophistication of the sensors and
controls of the present invention. Existing processes are generally
classified as fixed bed, traveling bed, fluidized bed, and
entrained flow, and none of these processes has evolved into a
market-leader technology.
DESCRIPTION OF RELATED ART
[0005] This invention relates to and improves on the inventions
described in the inventor's previous filings, U.S. Provisional
Patent Application No. 60/629,486 and U.S. Provisional Patent
Application No. 60/635,117, by teaching less expensive and
alternative methods of molten slag and molten steel layers level
sensing and control. Whereas the referenced inventions show use of
scanning nuclear or x-ray gages for this purpose, this invention
teaches other lower cost proximity or point level instrumentation
which when combined with sample-data control technique enables full
control over molten slag and steel levels or thickness. Other
alternative sensors that can be used are insitu laser spectrometers
in the molten masses and other insitu point level sensors based on
magnetic, capacitance, or inductive methods, and even floats, to
sense molten slag and steel thickness. For example, the insitu
laser spectrometer sensor can be used to control molten slag and
steel levels or thickness because the material makeup is different
for molten slag and molten metal, and such a sensor can determine
this, but that sensor can also provide valuable composition
information simultaneously and advantageously. Different signal
characteristics will show up for the other types of point sensors
mentioned for different materials present providing other means to
control these levels or thickness. And when combined with
instruments to sense the emitted gases can gain full control to
optimize the gasification and steel-making processes. Which of
these sensor types would be the preferred method is difficult to
judge at this times since for some, like insitu laser spectrometers
the costs will likely be high since they are not in use at this
time, being a new insitu laser spectrometry invention, it is just
being introduced such as the gas laser spectrometry sensor.
However, these sensors have important advantages making their high
cost fully justified for large machines. But this invention claims
the use of these specialized sensors for the purposes set forth
above and in conjunction with other technology cited in the
references furthering the art and advances claimed by the inventor
to achieve low cost and reliable syngas and steel-making
technologies based on continuous processes and in particular using
molten slag bed processes and technology for syngas producing
purposes.
SUMMARY OF THE INVENTION
[0006] A continuous smelting/low-grade steel making process and/or
coal or carbon gasification process and apparatus involving
blasting a mixture of ground ore, coal, and a flux mixture(s) (or
coal and flux and pure oxygen if a syngas gasifier) through a
concentric water cooled downward lance close into the molten slag,
with feed mix flowing between the outer cooled shell and inner core
air blast tube which expels air/oxygen mixture at high velocity
onto the top of the molten slag layer to make steel or syngas.
Further, to make steel there is an air/oxygen blast under the
molten metal layer from the base of the crucible distributed evenly
through a fine bubbling diffuser mounted within the crucible floor
so as to reduce carbon in the molten iron to make at least a low
grade steel. For syngas making, ground coal or carbon and flux
mixture is blasted into the molten slag with pure oxygen. Means to
separately meter ore or gasifier mix ingredients from lock hoppers
with bubble-tight valves with gas purging to prevent gas from
flowing back though the hoppers, and with in-line mixer before
entering the concentric lance with O2 or enhanced air-O2 mixture
(steel). To preheat the air/oxygen blast for steel-making,
circulates blast air mixture within a top metal plenum of the
furnace with inner shell made of high temperature coated steel
alloys enabling achievement of sufficient temperature air/oxygen
blast. Slag and low-grade steel outlet trough with above laser
spectrometer measurements or insitu laser spectrometer sensing slag
and steel quality determining chemical composition of both slag and
steel flows to enable optimization of steel quality and minimize
carbon losses and control molten levels. Other means are presented
to measure crucible molten slag and molten metal thickness to
enable control for molten slag and metal thickness through an
out-flow control valve. All this instrumentation is provided so as
to combine and with suitable computer control and optimizing
algorithms and software to properly control preheated ore mix feed
rate and composition, levels of molten iron, air/oxygen blast
rates, and all to produce a quality syngas or low-grade steel
output with proper carbon, sulfur and potassium contents to the
maximum practical extent so as to optimize steel making or gas
quality within one vessel in terms of quality and production
requirements and to maximize the overall cost effectiveness of
process of gas making smelting and steel-making.
[0007] As a steel-making invention it is a simple, compact
cost-effective technology designed to co-generate electricity and
fully automate steel-making in a single vessel process and
apparatus. The process also eliminates the need for coke and thus
coking ovens, awkward air blast preheat apparatus, air pollution
apparatus (since co-generation boilers handle all flue gas), all
which makes steel-making compact and less costly with minimized
pollution and maximized revenue capability.
[0008] This invention teaches use of a molten bed of slag to O2 or
enhanced air/O2 blast in ingredients, simplifying operations and
improving control while simplifying slag and metal (if present)
rejection and recovery, or simplified steel-making. Advantages of
this new gasification process and apparatus over present apparatus
and processes are: [0009] 1. Dry fuel feed. This means maximum hot
gas efficiency potential, approaching 98% and minimized pure oxygen
needed to gasify, minimizing oxygen operating costs. [0010] 2. Due
to the large molten slag bed mass, there is a flywheel-effect that
helps keep the process going as a stable and intense reaction that
can work for any carbon fuel, even the worst quality coals. [0011]
3. The simplicity of the molten bath also seals off the drop leg of
the contiguous hot gas cyclone cleaner, a critical advantage for
both gasifying and steel-making since this cyclone hot gas cleaning
is required to achieve low carbon loses and simplify downstream gas
clean-up. [0012] 4. Blasting fuel and oxygen into the slag mass
splatters the slag onto the gasifer inner walls protecting the
refractory and upper zone interior of the gasifier, which is a
proven technique of the steel industry. This is critical to
extending the life of the refractory for years of use between
rebuilds. [0013] 5. The ability to gasify any carbon material, even
the poorest quality coal, is very important since many regions of
the world do not have high quality coal. To do this, the control
computer automatically adjusts feed ingredient ratios and oxygen
blast and opens up the slag discharge valve more to let out the
greater slag produced from the greater dirt in the coal or waste
fuel. The new sensors and computer does it all automatically,
including sensing and controlling the molten slag and/or steel bed
thickness. [0014] 6. It also has the ability to fully recover
metals that sink to the bottom under the molten slag mass. A
thicker metal bath is maintained if making steel. [0015] 7. It also
enables recycling slag into construction products. Since flux
(limestone) is added as part of the combustion process to produce a
cleaner gas to react out sulfur (if coal is used), and since flux
is definitely added when making steel, the heat converts the flux
into cement ingredients within the slag. So if the slag is air
dried into clinkers and ground up and kept under cover like in
cement plants, it becomes a concrete product base material useful
to constructing buildings and roads, etc. [0016] 8. It uses a
simple feed apparatus which also enhances reliability. [0017] 9. It
uses new sensors and sophisticated controls to keep a close watch
over all key process variables. Computer control is essential to
optimizing and controlling basic process and is absolutely
essential to maintain reliability and hands-off automation. The
computer also enables software to be developed to optimize the
process. This is a new standard of instrumentation being brought
into steel-making and gasification processes to make them reliable
and cost effective technologies.
[0018] To insure continuous feed, this process includes at least
two (2) lock hoppers (not shown) for each ingredient of combination
of similar ingredients such as ground coal, ore, and fluxes. Three
for each ingredient provides needed redundancy for maximized
reliability in feeding. These lock hoppers have specially designed
variable speed flotation helical undercutting rotors, or the equal
are also commercially available in the marketplace, to undercut and
simultaneously unload and regulate feeds after calibration with
rotary rpm measurement to flow to maximize production consistent
with steel or syngas desired quality. More than one flux material
lock hoppers may be added to control sulfur and phosphorous content
of the final common-grade steel output for example. In
gasification, a flux would be added if there was sulfur present in
the carbonaceous fuel, such as in coal, and the lock hoppers would
be evacuated of air before recharging with an un-reactive gas which
also is easily removed later, such a CO2, whereby the feed lock
hopper valve can be reopened and the now gas purged feed made to
the ingredient mixer (not shown) commence. The lock hoppers would
use bubble tight high-temperature valves on their inlet and outlet
that are capable of hundreds of thousands even over a million
operating cycles, such a valve made by Macawber Engineering
Incorporated, which are especially suited to feed applications. To
insure that no O2 or enhanced air with O2 blast (when making steel)
can pass up into lock hoppers, to avoid possible dust explosions in
the coal lock hoppers in particular when filling, they can be
continually CO2 purged when feeding, as noted.
[0019] As noted, there is an in-line mixer (not shown) that feeds
into the concentric water cooled lance entering through the center
top of the steel-making furnace and/or gasifier. All ingredients
converge by gravity flow or other means at this point for gravity
flow into the molten slag mass through the water cooled copper
lance of sufficient diameter to accommodate solid material flow in
it's outer concentric perimeter and O2 enhanced air flow for steel
making in it's center tube or nearly pure O2 blast flow if
gasifying coal or carbonaceous materials into syngas. Iron is
converted into common-grade steel in the lower molten metal zone by
bubbling in oxygen and molten metal is discharged from a center tap
hole on the center floor of the crucible. The exact location of the
tap hole, which can be out the side as well, is not critical as
long as it is below the slag layer about 12 inches.
[0020] The lance outer shell is water cooled with re-circulating
water in the case making steel, or this flow is emitted as a radial
water or steam from the lower end and perimeter of the lance
spraying radially in a horizontal fashion from the bottom of the
lance to create gasification reactions of ionized carbon into
syngas. The amount of flow is governed by the syngas reactions
measured by online sensors or the degree of cooling desired or
both. The O2 blast tube in the lance center is shorter and inside
the outer shell sufficient to create a venturi or suction effect to
pull the coal or ore mix down the lance, and whereby the high
velocity of the air/oxygen achieves thorough mixing and combustion
of coal to smelt the ore and relying on the remaining molten slag
and steel to finish smelting and conversion into iron or gas at the
slag and upper region of the molten iron layer while impinging at
sufficient velocity to push aside and splash molten slag onto the
interior surface of the upper entrained flow volume of the unit.
Pure oxygen is not as critical with steel making or where smelting
operations are involved. In, gasification, to make syngas, pure
oxygen is used in the blast and it's desirable to make the whole of
the gasification vessel refractory lined and cyclone cleaner
contiguous with the gasifying vessel in both steel-making and
gasification. The gasifier or furnace pressure vessel outer shell
is water cooled and further insulated against heat loss. Off-center
and rectangular or elliptical housings are also feasible, thus
concentric blast lances are not the only configuration possible to
feed ingredients and blast and achieve a good result.
[0021] In steel making, the upper shell or plenum of the furnace
has a high temperature steel alloy inner layer since pre-heating
the air/oxygen blast is required to achieve steel making or
smelting temperatures, such pre-heat temperatures are well known
and will vary depending on the steel, coal quality or fuel and flux
quality, but the upper plenum or shell area is designed with
sufficient inner surface area of the exposed upper furnace to
achieve these final blast temperatures at full load steel flow.
Such inner steel alloy surfaces may be coated with ceramic or
refractory for protection while still adequately pre-heating the
steel air-O2 mix blast without exceeding safe operating temperature
of the inner shell lining or outer pressure vessel shell. The outer
shell of the pressure vessel is steel and water cooled but also
insulated on the inside from the air-preheat flow preventing excess
heat transfer into the water cooled outer shell by using refractory
blanket or similar high temperature insulation or spray-on mixture,
such detailed plenum layering and design is well known and
understood by those skilled in the art of pressure vessel, furnace
and heat exchanger design combinations.
[0022] Gases leave the furnace or gasifier through a water cooled
and refractory contiguous cyclone as shown which cleans slag and/or
carbon blow-by and returns it as molten slag into the crucible
through the refractory lined and water cooled drop leg of the
cyclone. The pressure drop through the cyclone causes slag to
travel up into this leg an amount equal to the pressure drop. At 5
psi pressure drop through the cyclone, that rise is estimated to be
about 4 feet above the average slag elevation in the crucible
space. Also, such drop leg could be lined with inductive coil to
re-melt solidified slag in the leg of the cyclone should that
occur.
[0023] A refractory lined and insulated crucible below the upper
air cooled metal portion of the furnace has a center bottom tap
hole for finished common grade steel or to let out metals recovered
from gasification operations, and a tap hole some distance above
the floor on the side wall of the refractory crucible to
accommodate slag removal, the height of this slag hole would be
determined by design. For example, if for basic steel containing
600 tons were to be maintained in the crucible, the crucible inner
diameter the slag tap hole may be as high as 6-7 feet. In the base
of the crucible, there is a ceramic fine air/oxygen bubbler
diffuser of sufficient diameter and flow to cause adequate carbon
reduction in the iron in the lower section of the molten iron layer
to convert smelted iron to common-grade quality steel, whereby such
steel (or recovered metals as in gasification) flow down through an
open center hole of this diffuser and tap hole passage or ceramic
pipe, such ceramic passage hole pipe is a magnetic inducing coil or
plates to produce counter forces for steel flow control to assist
in the control of steel outflow for crucible molten level control
purposes or melt material that might solidify in the tap hole. For
gasification applications, the molten metal thickness, to the
extent metal accumulates, would be much less than the molten slag
thickness. The relative thickness as shown in FIG. 1 apply and is
shown as if steel is being made.
[0024] To simplify discussion of the invention in this instance, a
simple rectangular symbol is shown to represent steel and slag
outlet valves for flow control which can be ceramic tubes
surrounded with refrigeration coils to create hole size control or
ceramic plug valve position or even ceramic flapper valve position
outside the apparatus to control these flows. Or, ceramic plug
valves can be mounted inside and actuated by suitable long ceramic
shafts for outside actuators operating through flexible bellows
interfaces (all not shown in detail) to enable pressurized
operation of the gasifier. Any number of arrangements for metal and
slag flow control are possible and are familiar to those in the
business of designing and manufacturing steel-making furnaces,
processes, and specialized steel ladle valve apparatus.
[0025] A reliable method to sensing of molten metal and slag or
fresh feed accumulation in the previously mentioned U.S.
Provisional Patent Application Nos. 60/629,486 and 60/635,117 was a
scanning nuclear gage, or x-rays could also be used. An alternative
to scanning focused nuclear emissions or x-rays to level thickness
measurement is an array of insitu laser spectrometers, just
invented by others. Such a spectrometer has been proposed and
probably uses an air cooled diamond window to withstand the high
temperatures (diamond melts at about 2.5 times molten steel
temperatures, steel melts at about 1500 C). Indeed, 5 carat
artificial diamonds of high quality are available and much larger
artificial diamond crystals will be available soon. This is likely
large enough a diamond crystal to pass a laser bean into and
reflect off molten steel or slag for measurement purposes. The same
laser can feed optic fibers to an array of diamond window insitu
units with different fibers sending the reflected signal back to
the same reading equipment and control room mounted sensor and
computer (not shown). The advantage of the insitu laser
spectrometer type sensor is it also feeds back the composition of
the molten metal so that a picture of development into steel
vertically within the crucible is obtained. One insitu laser
spectrometer sensor for slag and one for metal could suffice for
sample-data level control methods for slag and steel level. With
this method, control valves increase output until slag level drops
below the sensor whereby the flow is decreased and this oscillation
up and down is part of the control method, which would be the same
for the molten metal and slag interfaces. But if multiple levels
are to be specified under different conditions, or to have working
backups, or a full picture of steel quality development, an array
of such sensors is needed. Three in slag and molten metal are
shown, but many more can be used economically since the same laser
and computer are used for every measurement. Such single data point
level proximity sensors coupled with sample data-control theory
have been common use before, and such control algorithms can
accurately control slag and metal outflows to maintain their proper
thickness while maintaining a relatively steady valve setting for
any given load. Other types of insitu sensors can also determine a
picture of density variation for layer thickness such as proximity
probes that vibrate to determine densities, magnetic, capacitive or
resistive proximity sensors, and the like. But of these, insitu
laser spectroscopic sensors are the most powerful as to information
gained by yielding also the quality state of molten slag or steel,
especially carbon vertically within the metal molten mass. They can
also be simple, rugged and long lasting if the window is a gas
cooled diamond polished flat like a small piece of glass.
[0026] In addition, an alternative to insitu sensor array, a
velocity change of a falling ball can determine levels of slag and
molten metal as shown. This method of sensing velocity change is
not as powerful a method as laser spectrometers, as mentioned
previously and is an awkward method. In this instance, a heavier
ceramic or water cooled ball is periodically released in the gas
zone and hinged acting through a flexible diaphragm falls through
an arc at various velocity rates depending if it were in gas, or
molten slag or metal. Hence through velocity variations the
computer knows where one interface starts and the other stops, thus
determining thickness of these zones within the range of the
oscillating ball. Or, two balls of different density to float on
slag or steel could be applied instead. The computer algorithms to
control these variables can be created by those skilled in the art
of syngas or steel making and are discussed further below. Thus,
with this critical level measurement and other measurements noted,
the direct and continuous syngas or steel making processes and
apparatus as explained herein can be fully automated and
optimized.
[0027] Also, steel quality can be sensed as it flows molten and hot
in the trough directly from the furnace unit (not shown). These
laser spectrometer sensors to determine steel characterizes have
been tried and found to be practical and is a back-up or adjunct
method that can be used to continually sense final steel quality
along with the insitu spectrometers mentioned previously and was
covered in the cited inventions.
[0028] Insitu laser sensors are being tried now in the power
industry to sense combustion gases and appear to be a practical
method to sense steel making gases or syngas gases for more
accurate control purposes. In situ laser combustion gas sensors do
not need recalibration once calibrated. They do have to be gas
purged to keep the optics cool, and this gas purge rate is
accounted for in the calibration phase of the instrument. For
gasification, CO2 or pure O2 would be the recommended purge gas.
For steel-making, nitrogen would be the recommended purge gas. In
the instance of making steel, control valve means to adjust
air/oxygen blast rates into the top lance and bottom fine bubble
diffuser and optimizing algorithms to computer control the whole
furnace process as follows in A-G below:
[0029] A. If more production is needed, the computer looks to
increase steel and slag levels or fresh feed accumulation levels to
adjust to a higher steel and slag flows out enabling precise levels
and thickness of metal and slag or fresh fed material accumulation
to be maintained within the furnace or gasifier, and if final steel
carbon is increasing per spectrometer measurements, it increases
bottom bubbling air/oxygen flows. If CO is excessive, it increases
the hot air/oxygen blast from the lance.
[0030] B. If steel carbon content too high, the computer increases
bubbling air/oxygen from the base, and if that does not correct it,
increases the lance air/oxygen blast as well. If it is still too
high or reducing atmosphere in the furnace is getting too low (as
evidenced by decreasing CO measurement), the ore mix feed is
reduced or coal feed rate increased to bring the carbon reducing
capability of the diffuser within it's acceptable range of
capability.
[0031] C. For furnace molten iron level for any given ore feed rate
(production set point), the molten layer sensing enables furnace
iron level to be adjusted by the steel outlet tap hole plug
position or refrigerant temperature or flow rate, eddy inducing
restricting forces whichever means of flow control are used or
necessary to be used. All three can be designed to operate in
staggered way; eddy current first, refrigerant flow second, and use
of the tapered plug force or position as a third method.
[0032] D. If steel is being made (with gasification, only carbon
and flux would likely be added), the steel carbon level is
acceptable, but other steel chemical parameters are too high or too
low, the only remedy may be a change of the ore mixture by
adjusting lock hopper discharge rates (lock hoppers not shown). It
will take a long time constant for these changed to show up in the
final steel since there can be up to 6 hours of steel capacity
contained within the crucible for basic steel manufacturing
operations (calcium carbonate used as flux), but computer control
algorithms can easily accommodate such time lags given the level
inputs.
[0033] E. The laser spectrometer on slag monitors it for iron and
carbon content indicating an ore mix change may be needed or that
more lance blast is needed. It may be desirable to let out-of-limit
carbon conditions prevail in the slag if it is the most cost
effective operation. The computer can be capable of calculating the
cost consequences of various operation modes. As noted, this laser
spectrometry is shown insitu, or lasers can sense the molten
outflow itself as shown in the previously mentioned U.S.
Provisional Patent Application Nos. 60/629,486 and 60/635,117.
[0034] F. Since it's probably almost always desired to evolve to
maximum possible production capability of the furnace, the computer
can always be set to an evolutionary operations standard of maximum
production, say as determined by an upper level carbon content of
the final steel or iron or slag or maximum syngas flow (hot gas
mass flow rate measurement method not shown). In this instance, the
computer will slowly ramp up input or mix feed rate and adjust
crucible molten slag and iron levels to maximize production.
Maximum possible levels of slag and iron will be determined over
time. Increasing top air/oxygen lance blast and bubbling O2 rates
under the steel should maximize steel production until a limiting
condition is reached (say excessive carbon in the final output
steel) then the computer will back down production to within a safe
level such that there is a measure of control over the process
using the various parameters measured: water vapor, O2, CO2/CO,
temperatures, final laser spectrometer quality measurements of
steel and slag, furnace iron and slag level or thickness, air
blast, air/oxygen bubbling rate, or ore mix compositions, steel and
slag flows, syngas flows, all automatically adjusted by the
computer control system algorithm determinations.
[0035] G. Steel and slag weir flows (not shown) are measured since
they indicate production levels of actual steel and slag and they
can also indicate if an upper limit has been reached or that there
are molten steel or slag flow control problems. For example, if the
plug opens the tap hole more but no increased flow is noted in
either slag or steel, then ether the flow control actuating methods
are failing, and computer historical data can immediately enable
the computer algorithm to alarm, and output what the operator
should check first.
[0036] Thus, it can be seen that this invention teaches a very
advanced method of continuous steel making and/or gasification and
uses the most modern combination of instruments and sensors to
accomplish this, and it teaches a variety of molten slag and steel
level and quality sensing instrumentation that can be used, and
unique arrangements of equipment and process to avoid the need for
coke and expensive recuperator to preheat air/oxygen blast to
proper temperatures. And finally, optimization algorithms are
suggested such that those skilled in the computer programming arts
and steel-making and syngas making in combination with steel
process engineer experts in acid or basic steel making processes
etc. could enable such software to take advantage of the instrument
signals provided to gain precise and accurate control over the
process including ingredient mix ratios and all material flows to
optimize syngas and steel outflow rates with maximized quality and
economic advantage with a minimum of labor input and capital
cost.
[0037] Finally, means are suggested whereby maximum recycling of
slag wastes into useful building materials is possible by air
drying slag into clinkers, and grinding these clinkers into cement
base material with crystallized dirt already present, and adding
what regular cement product is necessary to make a quality
pre-mixed concrete aggregate based product.
[0038] The present invention and its advantages over the prior art
will be more readily understood upon reading the following detailed
description and the appended claims with reference to the
accompanying drawings.
DESCRIPTION OF THE DRAWINGS
[0039] The subject matter that is regarded as the invention is
particularly pointed out and distinctly claimed in the concluding
part of the specification. The invention, however, may be best
understood by reference to the following description taken in
conjunction with the accompanying drawing figures in which:
[0040] FIG. 1 is a vertical schematic section of one embodiment of
the present invention.
[0041] FIG. 2 is a vertical schematic section of another embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0042] Referring to the drawings wherein identical reference
numerals denote the same elements throughout the various views,
FIG. 1 shows an apparatus 1 comprising a single vessel blast
furnace that can be a direct smelting iron and steel-making
apparatus or a gasification apparatus. Generally, the present
invention relates to any type of apparatus that produces a molten
by-product, such as molten slag or ash, including, but not limited
to, iron or steel making apparatuses, solid waste, coal and other
types of gasifiers, waste-to-energy boilers, and coal boilers.
[0043] When apparatus 1 is used as a gasifer, it's desirable to
keep nitrogen out of the gasification reactions to avoid noxious
nitrogen based compounds, therefore once lock hoppers (assemblies
with valves not shown) are filled, it's desirable to close bubble
tight lock hopper valves and evacuate the chamber by vacuum pumps
(not shown) and continue to purge lock hopers with an un-reactive
gas such as CO2 to re-pressurize the lock hoppers so as to prevent
undesirable gasification reactions when oxidizing reactions take
place from pure pre-heated (if necessary) oxygen or air-oxygen
mixture addition 2 through lance 3 inner O2 feed tube 4 (shown as a
line in FIG. 1). At least 3 hoppers per ingredient provides the
maximum practical reliability. It should be noted here that the
terms "air" and "oxygen" can be used interchangeably and either
term, whether used alone or together, refers to air, pure oxygen or
any other oxygen-containing substance.
[0044] Also, in feeding coal and flux or any material mix 5 to be
gasified, it should be relatively dry and finely ground material,
but it does not have to be a fine powder, as pure oxygen is highly
reactive with carbon under circumstances depicted in the invention.
Therefore, as in times past when coal was prepared (ground) and
stored in large bins prior to feeding to boiler burners, for best
feed reliability this is also a better practice for this invention
utilizing large storage silo's, for example, before feeding coal to
fill the lock hoppers (not shown).
[0045] Mix feed 5 (coal, ore, and fluxes respectively) flows by
gravity through chutes (not shown) into the outer concentric space
7 of lance 3 splitting around inner lance air/oxygen tube 4 (shown
as line here). Lance 3 can be as large as twenty-four inches in
diameter or more for furnaces with 800,000 tons per year of steel
producing ability. Also very high output gasifiers are possible
with this design, as large as 1000 MW input and possibly even
double that coal feed rate as a gasifier should be feasible since
at inputs of 1000 kW/cubic foot (less than one horsepower input per
cubic inch) are feasible, that's only an entrained flow volume 6
above the slag layer of 1000 cubic feet with a coal flow of about
130 tons per hour (depending on coal BTU content). The well
insulated gasifier 1 is expected to achieve a hot gas efficiency
approaching 98% (neglecting parasitic losses, the largest being O2
production).
[0046] In describing the upper furnace area, in making steel, blast
2 enters the bottom of upper plenum dimension area 8 at 2'' (plenum
details not shown) passing around this plenum to pre-heat the blast
and cool the plenum whereby it enters to enter lance 3 as blast 2
or pure oxygen blast 2 if making syngas. Note for steel making,
blast 2 is not 100% oxygen but is only pure oxygen enhanced and
pre-heated as needed to achieve high temperatures to smelt the ore
mix. Similarly, when apparatus 1 is used as a gasifier, upper
plenum area 8 may be fully refractory lined as shown for crucible
lining 9 in molten slag 10 and molten metal mass 11 spaces. If the
unit 1 is a gasifier, molten steel thickness 11 will be held to a
much lesser thickness than slag thickness 10. Mix 5 leaves the
lance as 5' as shown to combust and or smelt into iron on the top
layer slag 10 which is depressed as shown due to the high blast 2'
velocity leaving the lance 3 tube 4. Oxygen blast 2' which is
slightly inside the lance perimeter exit mouth as shown, which
creates a vacuum to induce mix 5' into the burning and/or smelting
zone 12 beneath the lance insuring complete mixing of mix 5' and
oxygen blast 2'. Lance coolant 13 enters the cooled perimeter of
the lance, generally of copper construction, (water coolant flow
control not shown) as shown and if making syngas exits at the base
as 13' around the lower perimeter of copper lance 3 through nozzles
(not shown) which along with pure oxygen 2' makes unit 1 into a
syngas producing device instead of a smelter/steel making device,
otherwise, coolant 13 re-circulates through the lance as required
to keep lance 3 within temperature specifications.
[0047] Water cooling details of externally insulated outer shell of
apparatus 1 are not shown, but such technique is well known to
those skilled in the art of such pressure vessel design including
hoop stress design criteria for such high temperature pressure
vessels, including insulating this outer shell inside the area 8 if
it is a plenum preheating air-O2 blast in the case of making steel.
As a steel making device, the upper shell area 8 of apparatus 1
would likely require a separate controlled coolant should the
complete unit 1 not be fully refractory lined as in making steel.
For example, when making steel, upper plenum shell area 8 is
designed as a plenum to preheat oxygen enhanced blast 2, whereas
when gasifying, such a blast preheat plenum is not necessarily
required (although it may be desirable in some instances, say with
wetter fuels) so the whole inside area 8 of upper entrained flow
zone 6 could be refractory lined. The outer shell of unit 1 as a
pressure vessel would still be water cooled and further insulated
to minimize heat losses as noted above. The inner shell of plenum
area 8 could be any corrosion resistant metal but would probably be
stainless steel and ceramic or refractory spray coated for further
protection but of not such thick layer as to prevent adequate
air-O2 mix preheating for steel making. The inner or part of the
other pressure vessel of area 8 would also be insulated to preserve
the pre-heat value of the blast.
[0048] The preheated air/oxygen blast 2 through center tube 4
impinges into the molten slag 10 at zone 12 combusting the coal or
carbon material providing heat for smelting or gasification as
required. This blast also spatters slag (not shown) within the
upper zone 6 which helps preserve the inner shell coating material
of plenum area 8, and passes down through the concentric opening by
gravity to impinge onto and create a depression of the molten slag
10 created by the force of air/oxygen blast 2. Typically about ten
psig of air pressure would be used to create the high velocity
blast 2' needed including pressure drop needed to clean gases
through a cyclone 14.
[0049] Inner gas flow 15' whether from steel making or gasification
passes into the refractory lined and water cooled cyclone 14 to
remove molten particulate matter or slag to recycle it back as
molten material into slag mass 10. The high temperatures keep the
carbon and escaping slag into a melted state as noted and which
runs down leg 14' back into molten slag mass 10 as noted. Since
there is a pressure drop though cyclone 14, slag 10 is drawn up
into leg 14' to some level 17 approximately as shown, but such
amount will vary depending upon the pressure drop designed into the
cyclone 14, but about 4 feet of elevation into leg 14' above the
average slag mass 10 top level would be expected for a 5 psi
pressure drop.
[0050] And to complete gasification reactions if no iron ore is
being added but just coal and flux as in gasification, the water
cooled outer layers of copper lance 3 of would emit coolant stream
13 as steam water/steam mixture 13' though nozzles (not shown)
around the lance perimeter at it's base to complete the
gasification reactions to hydrogen and carbon monoxide with some
excess water vapor present along with CO2 and vaporized or ionized
trace metals, and H2S and other vaporized compounds and elements
which are removed later from gas 15 by well known methods. The
amount of steam or water 13' emitted from periphery nozzles on
lance 3 will depend on the gas characteristic measured and
temperature of the reaction desired and whether blast 2 is mostly
air or mostly pure oxygen, but is generally minimized. Better
control of either steel or gasification burn reactions can be
achieved in gas 15' or final gas 15 by using new laser spectrometry
emitter 19 and receiver 19' technology which shoots a laser beam 20
across and through a chord segment(s) of gas stream 15' or 15
(multiple units would be used in an array to get a complete picture
of the gas within space 6 but only one of 19/19' is shown) as gas
15 in the exit pipe (lasers not shown). Only about 1/2 of 1% of
beam 20 needs to strike sensor 19' to record nearly all the gas 15'
characteristics including temperature, moisture, CO, CO2, O2, and
other gas constituents. Because this measurement is laser based,
once it is calibrated, it should never need to be calibrated again,
which is a distinct advantage over all other hot gas sensors to
determine gas characteristics. Conventional gas constituent sensor
18 would also be installed as a back-up and calibration check on
spectrometer assemblies 19/19'.
[0051] The lower furnace area is comprised of refractory lined
crucible with insulated refractory 9. The inner diameter of this
crucible material 9 could be as large as 20 feet inside diameter to
accommodate say 600 tons of steel maintained in the furnace for
basic steel operations for a 800,000 tons per year furnace. To
control upper molten slag level of mass 10 and molten steel level
of mass 11, a scanning nuclear or x-ray gage operating along a
vertical chord of the crucible lined as 9 from the outside (not
shown) can be used and is described in the previously mentioned
U.S. Provisional Patent Application Nos. 60/629,486 and 60/635,117.
These would not generally scan through the center of the diameter
but rather off to one side as noted, or scanning a chord of the
crucible's horizontal cross section of suitable length for nuclear
ray penetration through the furnace and furnace mass to detect the
full range of molten slag 10 and steel 11 respectively, and upper
fresh feed mass thickness as well (fresh material thickness not
shown). This signal is feed into a computer programmed to show a
complete vertical density profile of the vertical height measured
which can be used to make control decisions on inflows and outflows
to the furnace to be discussed below. Other sensors that can
accomplish this control task are discussed below and which have
certain other advantages.
[0052] The upper layer of the molten steel molten mass 11 is
expected to be considered as smelted iron and the lower level of 11
to be low-grade steel created by the carbon reducing action of an
oxygen blast 22 which passes into the base of the crucible 9
through fine bubbling diffuser 23 and up though the mass of molten
steel and slag as shown depicted as bubble streams 23'.
[0053] The common grade steel 21 exits the base of unit 1 through
ceramic pipe passage or tap hole 33 which through most of its
length is surrounded by eddy current inducing forces coil not shown
which can be activated by electricity so as to act as a
countervailing force to control the exit flow of steel 21 through
passage way 33. The outer tap hole area 33 is surrounded by
refrigerated coil (not shown) which can have cooled fluids at
various flow rates and temperatures, adjusted by computer control
based molten steel level computer inputs to cause the exit tap hole
33 to shrink in size as required which can also control out-flows
of steel and slag and the level or thickness of 10 or 11. Similar
technique can be used on slag tap hole 24''. Or, the computer can
activate the actuator of plug valves 24' for slag and 21' for
steel, such ceramic plug flow valves are well known in the steel
making art and are usually submerged in a pan (not shown but
depicted in cited inventions).
[0054] To begin operation of the furnace or gasifier, molten slag
would be added to the crucible though an upper furnace opening (not
shown), and then the hot blast 2 would commence in conjunction with
the feed 5 driven by blast 2 into the slag as 10. The computer
would be determining the amount of moisture, temperature, CO2, CO,
and O2 of the process gas 15' and exit gas 15 and begin to adjust
feed rate 5, slag and steel flows 24 and 21 respectively and
starting the adjustments of mix 5 ingredient ratios or rates
depending on insitu laser spectroscopic measurements 26 (three
sensors shown) and 27 (three sensors shown but a full vertical
array on the steel mass would likely be used). Other types of
insitu proximity sensors can be used to replace 26 and 27 to
determine different density characteristics of molten materials
such as molten slag 10 and metal 11 including vibrating probes,
conductive and capacitive sensors, magnetic and the like. Even the
dropping ball sensors 28 (shown in raised position 28') hinged at
flexible diaphragm 29 could have a combined actuator velocity
sensor 30 to determine velocity change and hence the interface
location between gas in 6 and slag 10, and the interface between
slag 10 and molten metal 11 and in so doing know the positions of
these interfaces. An insitu laser spectrometry sensor (details not
shown) as in 27 could also be attached to such an oscillating ball
28 to sense constituent elements of slag 10 and steel 11 as ball 28
is moved through slag 10 and steel 11 and passing the fiber optic
signals into and out through a hollow arm of 28. Even multiple
floats (not shown) like ball 28 designed to float on the slag and
steel interface layers respectively with units 30 designed to
determine floating position could be used. Those skilled in the art
of applying such specialty sensors will know the most cost
effective and reliable combination of such instruments. The
previously mentioned U.S. Provisional Patent Application Nos.
60/629,486 and 60/635,117 illustrate reliable and preferred
methods, and this invention illustrates other preferred devices,
like insitu laser spectrometers, that can sense molten slag 11 and
molten metals 10 depths and quality and which by virtue of their
design characteristic of using a single emitter and sensor at the
computer and fiber optics to a variety of units are possible,
including exposed outflows of steel and stag. It is believed laser
spectrometry as detailed here will eventually be very cheap and
powerful sensing technology for these purposes applying many such
sensors simultaneously to these processes.
[0055] Because there is such a long time constant for turnover of
steel 11 within the crucible, about 6 hours, previous data and
experience in steel operations contained within the computer data
base, plus known experience and nuances about steel making
programmed into the computer, enables quite accurate initial
conditions for all the control variables to be set such as
pulverized coal, flux, and ore ratios to the total mix 5 and what
blast 2 is appropriate for what total feed mix flow 5 selected. The
final measurements of the laser spectrometers and outlet gas 15, of
CO2, CO, and temperature and other gases will enable the computer
to bring the whole process under control and then fine tune the
process for best steel quality consistent with carbon losses in the
molten ash and needed production level.
[0056] If more production is needed the computer looks to see if it
can increase steel 11 and slag levels 10 and if it can, increases
the steel 11 and slag masses 10 in the crucible 9, and then it
adjusts to a higher slag and steel flows 24 and 21 respectively.
And if final carbon is increasing per insitu laser spectrometer
measurements 27 or external laser spectrometer (not shown) that
measures steel quality, it increases bubbling air/oxygen flow 22
and if CO is increasing, it increases the hot air/oxygen blast
2.
[0057] If the steel carbon level is acceptable as measured by steel
laser spectrometer 27, but other steel chemical parameters are too
high or too low, a remedy may be a change of the flux mixture of 5.
Because there may be up to 6 hours of steel production retained in
the crucible 9 for basic processes, it will take a long time for
these changes to show up in the final steel 21, but it is still
capable of automatic control and optimization by the computer since
the computer clock can wait these intervals to check final results
from the spectrometers.
[0058] If the laser spectrometer 26 used on slag indicates an ore
mix 5, ratio change may be needed or that production can be
increased, under blast 22 is increased to reduce slag carbon
content. Or it may be desirable to let slag carbon go out of limit
to achieve the production level desired. Those skilled in the art
of steel making will enable the computer programmer to fine tune
the logic to optimally control the process.
[0059] Since it's almost always desired to evolve to maximum
possible production of syngas or steel, the computer can always be
set to a evolutionary operations standard of maximum production say
as determined by an upper level steel 21 carbon content. In this
instance, the computer will slowly ramp up input feed 5 and adjust
slag and steel mass levels 10 and 11 as noted to higher mass levels
in the crucible 9 while increasing top blast 2', mix feed 5, and
bubbling blast 22 until an upper limit of any one of these
parameters is reached such that it is then known steel 21 carbon
content will start to rise or gas quality starts to fall as
determined by CO and CO2 contents, then the computer will back down
production to within a safe production level such that there is a
measure of control over the process using the parameters of CO2/CO,
final spectrometer measurements 27 and 26 of steel and slag
respectively or laser spectrometers pointed down onto the trough
flows of slag 24 and steel 21 (lasers and troughs not shown).
[0060] Steel and slag weir notch flow levels (apparatus not shown)
are measured with a proximity level device (not shown) such as a
non-contacting radar or fluidic sensor can measure production
levels of actual steel 21 and slag 24 which can indicate an upper
limit has been reached or that flow controls are malfunctioning.
For example, if the plug opens the tap hole more but no increased
flow is noted in either slag 24 or steel 21, then ether the tap
hole is too small, the plug is malfunctioning, or a limit has been
reached, and computer historical data can immediately enable the
computer algorithm to manage a determination and alarm output which
the operator then evaluates. All of the various sensor measurements
can be programmed to alarm if extremes in their condition are
reached.
[0061] Other variations of the invention are possible, such as
rectangular, elliptical cross section shapes for gasifier 1 and
with lances 3 to one side and feed into lances on one side and
blast tube 3 the other with blast to one side and ingredients to
the other and various configurations for steam and water blast for
gasification (not necessarily a symmetrical blast 13' from the
lance 3 itself). But the previous description is a least cost and
most compact or volumetrically efficient way to make the invention
for an integrated syngas and/or steel making operations. And in
steel-making, unit 1 is used in conjunction with a sizable power
boiler (not shown), such boiler having several other large
pulverized coal burners added to enhance profits from power
operations, while the power boiler fully cleans up the emissions
from steel making through the boiler's comprehensive emissions
reducing apparatus on the boiler stack gases. The present invention
is capable of a completely hands-off automatic control over the
steel-making or syngas making process in a cost effective manner.
It's intensity of operation and process and apparatus arrangement
achieves a compact technology, as noted, and minimized capital cost
apparatus. For steel-making it doesn't require expensive coke to
operate, only cost-effective ground-up coal either as a gasifier or
a steel-making.
[0062] Referring now to FIG. 2 a second embodiment of the present
invention is shown. This embodiment relates to any type of
apparatus that produces a molten by-product, such as molten slag or
ash, including, but not limited to, iron or steel making
apparatuses, solid waste, coal and other types of gasifiers,
waste-to-energy boilers, and coal boilers. However, by way of
example and for purposes of illustration, FIG. 2 depicts a
gasifier. As such, it doesn't describe the scanning nuclear gage
described above, as it only needs to be a fixed slag nuclear gage
sensing molten slag level over definite and limited range of
levels. And there are no multiple outlets of slag and steel in a
simple gasifier, just a single slag outlet should generally be
needed. However, if there were a lot of metal in the coal feed, the
gasifier crucible could be arranged to be like a steel-making one
with multiple molten outlets with material separation generally
depending on density difference and accumulating layers of
different materials which would require a scanning nuclear gage in
this instance to enable individual control of the out flow rates.
But the resistive heating or other methods of heating of the
crucible molten material and other machine elements shown apply to
both steel making and gasifier as does the slag recycling apparatus
achieved through cooling and clinkering described herein. Thus, no
other specific references to steel making will be made in the
following description.
[0063] Referring to FIG. 2, a gasifier 1 is shown as a low pressure
unit and thus represents a simple, low cost version of a gasifier.
This gasifier is made low cost in part by using a simple low
pressure (e.g., about 20 psig) air-lock rotary feeder 2. For higher
cost high-pressure versions, multiple lock hopper feed units with
unloader/feeders (not shown) would be substituted for feeder 2. But
overall, a high pressure version would still be more economic than
existing gasifiers due to savings in slag discharge apparatus and
more accurate control possible through advanced sensing and this
invention's dry feed process design.
[0064] Dry fuel mixture 4 is fed through rotary feeder 2 down
though the inside of cooled copper lance 3 (copper feed lances are
common in the steel industry to inject gases and fuel into smelting
and steel-making operations) as fuel 5 falls by gravity and is
blasted atop the slag mass 6. This molten slag mass 6 also provides
a "fly-wheel" effect to levelize the effects of variations in fuel
quality to gasification, a common problem with boiler burners. Air
blast 7 cleans the materials from the feeder compartments and
provides a purge of air or oxygen for the inside 8 of lance 3. It
should be noted that fuel 4 can be a wide range of fuel quality,
such as municipal solid wastes. Various fluxes can be added with
the fuel 4 to remove sulfur and other metals and can be adjusted
accordingly.
[0065] Lance 3 has air passages 9 to take air or oxygen oxidizer
blast 10 to the base of the lance as blast 11 angled across the
incoming fuel flow to cause through mixing of the feed 5 and
oxidizer blast 10 around the lance periphery which creates a very
hot fire at 12 atop the molten slag mass 6 in the 2650 F range or
at least to the limestone calcination temperature of about 2650 F
to insure that any lime flux added with fuel mixture 5 is reacted
to reduce sulfur in the burning fuel whereby the calcium ions Ca
react with the sulfur ions S to form CaSO4 or calcium sulfate.
Quicklime CaO is also formed from Ca un-reacted with S and comes
out in the slag discharge 13. To control the carbon content of slag
discharge 13, fiber optic laser spectrometry sensor 13' can bounce
signal 13'' off slag flow 13 and that carbon content signal can be
used to control the rate of oxidizer bubbling 26. More about fiber
optic laser spectrometry sensing will be discussed later for
control of the gasifier.
[0066] The outside of lance 3 is water or steam cooled by
concentric passageway 14 through which water or steam 15 flows
which is emitted radically from the lance perimeter and shown which
reacts with the fire passing up though entrained zone 16 to cause
gasification reactions within the entrained flow zone known as 12
and 16. Final entrained flow gas and ash and slag particles 18
leave entrained flow zone 16 to be cleaned in primary hot cyclone
17 and leave as hot gas 18'. If blasts 7 and 10 are pure oxygen,
gas 18' will be classified as a syngas and be principally hydrogen
and carbon monoxide with a small amount of CO2 and other trace
gases. If blasts 7 and 10 are air based, gas 18 will have a lower
Btu value and be like a producer gas. Low Btu gas is most economic
for boiler power applications where the extra volume due to
nitrogen present in the gas is not a problem. Thus much less
apparatus is needed as no expensive air separation unit is
required. Well insulated and water cooled on it's outer skin,
gasifier 1 can have a high hot gas efficiency up to 98%. Thus,
close coupled to boilers there is no power efficiency loss due to
gasifying first, yet the boiler can run much cleaner throughout its
operating life reducing maintenance and soot blowing.
[0067] Ash and slag captured by cyclone 17 passes down the cyclone
leg 19, which is shown with embedded electric heaters 20 which are
also in the walls of the cyclone 17 as well to insure the ash stays
molten should temperatures fall below slagging temperatures. The
electric heaters 20 can be any suitable heating means such as
resistive or induction heaters. Depending on the pressure drop
through cyclone 17, molten slag 6 in crucible 21 will be drawn up
into the cyclone discharge leg 19 to a level 22, about as shown,
i.e., the molten slag bed 6 is in effect the seal for the cyclone
discharge leg 19. This unique sealing method is advantageous
because it makes hot gas cyclone 17 maximally effective in cleaning
gas. About a 5 psi pressure drop would be ascribed to cyclone
operations to insure a properly cleaned gas 18' before sending the
primary cleaned gas on to other operations, which could be to
boiler furnace combustors or syngas cleaning and conversion
operations.
[0068] The gasifier temperature and oxygen/coal or carbon ratio is
measured through appropriate flow measurements devices which can be
the speed of the feeder 2 or orifices on blasts 7 and 10
respectively (not shown) and controlled by adjusting fuel feed
using feeder 2 speed and blast based on gas temperature and gas
constituent measurements as measured by fiber optic laser
spectroscopy shown as emitter 23, laser beam 24 and receiver 25
located in the upper area of the gasifier 1 and/or emitter 23',
laser beam 24', and receiver 25' located in exit pipe 26'. The
lenses of these beams are air or O2 purged (not shown) depending on
which blast gas is used, or some combination blast. The sensing and
control computer is not shown but the whole apparatus would be as
made by ZoloBOSS or equal and generally up to eighteen or so points
across the entrained flow zone 16 (only three such sensor
combinations are shown) can be sensed and measured by the computer
simultaneously using sample data control techniques including. This
for example, should it be desirable to run the gasifier entrained
flow region 12 and 16 highly reductive atmosphere there, that is a
heavily soot gas 18 prior to cyclone cleaning, fiber optic laser
emitter 23', beam 24' and receiver 25' cleaned gas 18' exit pipe
26' would be installed. However, because so many points are
available from the ZoloBOSS system, exit gas 18' would always be
measured in any event since it's gas constituents and temperature
and moisture measured by emitter 23', beam 24', receiver 25' are
adequate to control the gasifier if zone 16 laser units become
fouled with soot. Also, a heavily carbonaceous soot gas 18 may be
desirable from an emissions reduction standpoint to absorb heavy
metals and the like, including mercury. Salts can also be added
with fuel feed 4, for example, to ionize elemental mercury for
easier scrubbing within the stack gas clean-up system of a
boiler.
[0069] Only about 1/2 percent of the emitted laser light 24 needs
to reach the receiver 25 to measure gas constituents. Thus, dirty
gas streams within gasifiers can be measured with this technique,
and according to the manufacturer, laser spectroscopy never has to
be recalibrated as a measurement technique once set up. And
depending on the laser used, it measures CO2, CO, O2, moisture, and
combustion temperature. Thus, if the temperature is too low, the
blast 10 can be increased to produce more complete combustion and
thus hotter conditions in zone 12 which also produces more CO2 in
the final gas un-cleaned gas 18. Thus if the CO2/CO ratio is too
high, the oxygen/coal mass ratio can be adjusted down. But because
of the dry fuel feed and comprehensive sensing and controls, these
measurements enable the control computer to fine tune operations to
minimize CO2 in the final cleaned gas 18'. And the close coupled
cyclone 17 will take out any ash and slag blow-by 17' and
recirculate it to the crucible slag mass 6. Similarly, excess
carbon can be spectroscopic sensed in the final slag 13 as noted,
the computer can then increase oxidizer rate 26 through ceramic
bubbler distributor 27 as bubbles 28 to react any excess carbon in
the slag discharge 13.
[0070] Slag flow control out can be by a ceramic plug valve 29 as
used in the steel industry or by refrigeration coils 30 used to
freeze the tap hole 31 smaller, or let it melt to a larger tap hole
as required on the discharge end of discharge tap hole 31 as noted.
This slag outflow 13 is controlled to maintain a constant slag
level 6 and is controlled by typical fixed and inclined nuclear
level gage generally comprised of emitter 32, nuclear ray 33 and
receiver 34, such control systems well known in the art, that is 33
signal received gets less as level increases so valve 29 is opened
to bring the level back down or the opposite logic is also true.
With refrigerant 30, if the level of 6 increases, less refrigerant
flows and the tap hole in the final discharge area 13 enlarges to
bring the level of 6 back down, or again the opposite logic is
true. Tap hole 31 also has electric heaters 35' (which can be any
suitable heater such as resistive or induction heaters) imbedded to
insure the tap hole stays open or for start-up purposes.
[0071] Crucible 21 also has electric heaters 35 to maintain molten
conditions either at start-up or in operations. Crucible 21 and the
whole upper areas of gasifier 1 would be refractory lined,
insulated, and the outer shells water cooled and have an outer
layer of insulation, all not shown in detail on the drawing. Also,
the lower crucible 21 is shown welded to the upper gasifier area 1
with flange 36 to define a single vessel furnace. They can be
easily separated for shut down maintenance by burning off the weld
at flange 36. Generally, preferred construction is 100% welded. No
bolted flanges are used to prevent gas leakage and lower the cost
of construction. Welds are quickly removed to disassemble for
shutdown maintenance.
[0072] Another advantage of this invention is it enables 100%
recycling of slag 13 which is made possible by processes similar to
what is used in the cement industry, that is by cooling and
clinkering the slag and storing and for later milling into a
cementous products where additional amendments and cement can be
added to make a products useful in building roads and foundations
and the like. A preferred cooling and emissions system is described
following.
[0073] As can be seen in FIG. 2, slag 13 falls by gravity into gas
cooler 37 through opening 38 onto its air-cooled pin-hole grate or
equal 39 whereby clinkers 40 are formed from air cooling effects
and are kept moving along the grate by an oscillating pusher 41
actuated by motor 42. Blower fan 43 cooperates with ID fan 44
through pressure sensor 45 to insure a balanced air feed and
discharge so induced air 46 through the slag inlet is kept to a
minimum. Cooled and clinkerized slag 40 passes though crusher 47
and air-lock rotary valve 48 as cooled crushed clinker 49 which is
transported away by conveyor 50 shown as an arrowed line to storage
to be later milled and mixed to make cementous products as noted
above. These cement plant mixing and blending processes are well
known and so are not described here.
[0074] Temperature sensors to control pressurized air flow 51 and
final clinker 49 temperature are not shown but are well known in
the art. Hot gases 52 have heat recovered by unit 53, and the gases
are cleaned by electrostatic precipitator and scrubber unit 54
before passing through ID fan 44 to stack 55.
[0075] While specific embodiments of the present invention have
been described, it will be apparent to those skilled in the art
that various modifications thereto can be made without departing
from the spirit and scope of the invention as defined in the
appended claims.
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