Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEMS AND METHODS FOR CONTROLLING AIR
DISTRIBUTION IN A COKE OVEN
TECHNICAL FIELD
[0001] The present technology is generally directed to systems and methods
for
controlling air distribution in a coke oven.
BACKGROUND
[0002] Coke is a solid carbon fuel and carbon source used to melt and
reduce iron ore
in the production of steel. In one process, known as the "Thompson Coking
Process," coke is
produced by batch feeding pulverized coal to an oven that is sealed and heated
to very high
temperatures for 24 to 48 hours under closely-controlled atmospheric
conditions. Coking
ovens have been used for many years to covert coal into metallurgical coke.
During the
coking process, finely crushed coal is heated under controlled temperature
conditions to
devolatilize the coal and form a fused mass of coke having a predetermined
porosity and
strength. Because the production of coke is a batch process, multiple coke
ovens are operated
simultaneously.
[0003] Coal particles or a blend of coal particles are charged into hot
ovens, and the
coal is heated in the ovens in order to remove volatile matter ("VM") from the
resulting coke.
Horizontal Heat Recovery (HHR) ovens operate under negative pressure and are
typically
constructed of refractory bricks and other materials, creating a substantially
airtight
environment. The negative pressure ovens draw in air from outside the oven to
oxidize the
coal's VM and to release the heat of combustion within the oven.
[0004] In some arrangements, air is introduced to the oven through damper
ports or
apertures in the oven sidewall, door, or crown to the region above the coal-
bed (called the
crown region). In the crown region the air combusts with the VM gases evolving
from the
pyrolysis of the coal. However, the buoyancy effect acting on the cold air
entering the oven
chamber can lead to coal burnout and loss in yield productivity. More
specifically, the cold,
dense air entering the oven falls towards the hot coal surface. Before the air
can warm, rise,
combust with volatile matter, and/or disperse and mix in the oven, it creates
a burn loss on the
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coal surface. Accordingly, there exists a need to improve combustion
efficiency in coke
ovens.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Figure 1A is a schematic illustration of a horizontal heat recovery
coke plant,
configured in accordance with embodiments of the technology.
[0006] Figure 1B is an isometric, partial cut-away view of a portion of the
horizontal
heat recovery coke plant of Figure 1A configured in accordance with
embodiments of the
technology.
[0007] Figure 1C is a sectional view of a horizontal heat recovery coke
oven configured
in accordance with embodiments of the technology.
[0008] Figure 2A is an isometric, partially transparent view of a portion
of a coke oven
having door air distributors configured in accordance with embodiments of the
technology.
[0009] Figure 2B is an isometric view of a door air distributor configured
in accordance
with embodiments of the technology.
[0010] Figure 2C is a side view of the door air distributor of Figure 2B
configured in
accordance with embodiments of the technology.
[0011] Figure 2D is a partially schematic, top view of the door air
distributor of Figure
2B forming a vortex air pattern and configured in accordance with embodiments
of the
technology.
[0012] Figure 3A is an isometric, partially transparent view of a coke oven
having
crown air distributors configured in accordance with embodiments of the
technology.
[0013] Figure 3B is a schematic illustration of a crown air distributor
configured in
accordance with embodiments of the technology.
[0014] Figure 4 is a schematic illustration of a crown air distributor
configured in
accordance with further embodiments of the technology.
[0015] Figure 5 is a schematic illustration of a crown air distributor
configured in
accordance with further embodiments of the technology.
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[0016] Figure 6
is a schematic illustration of a crown air distributor configured in
accordance with further embodiments of the technology.
[0017] gure 7
is a schematic illustration of a door air distributor configured in
accordance with further embodiments of the technology.
[0018] Figure 8
is a schematic illustration of a door air distributor configured in
accordance with further embodiments of the technology.
[0019] Figure 9
is a schematic illustration of a door air distributor configured in
accordance with further embodiments of the technology.
[0020] Figure
10 is a schematic illustration of a door air distributor configured in
accordance with further embodiments of the technology.
[0021] Figure
11 is a schematic illustration of a door air distributor configured in
accordance with further embodiments of the technology.
DETAILED DESCRIPTION
[0022] The
present technology is generally directed to systems and methods for
controlling air distribution in a coke oven. In a particular embodiment, a
coke oven air
distribution system comprises an oven chamber having an oven floor configured
to support a
coal bed, a plurality of sidewalls extending upward from the oven floor, and
an oven crown
covering a top portion of the oven chamber. The air distribution system
further includes an
air inlet positioned above the oven floor and a distributor proximate to the
inlet. The inlet is
configured to introduce air into the oven chamber and the distributor is
configured to at least
one of preheat, redirect, recirculate, or spread air within the oven chamber.
[0023] Specific
details of several embodiments of the technology are described below
with reference to Figures 1A-11. Other details describing well-known
structures and systems
often associated with coal processing and coke ovens have not been set forth
in the following
disclosure to avoid unnecessarily obscuring the description of the various
embodiments of the
technology. Many of the details, dimensions, angles, and other features shown
in the Figures
are merely illustrative of particular embodiments of the technology.
Accordingly, other
embodiments can have other details, dimensions, angles, and features without
departing from
the scope of the present technology. A person of ordinary skill in the art,
therefore, will
accordingly understand that the technology may have other embodiments with
additional
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elements, or the technology may have other embodiments without several of the
features
shown and described below with reference to Figures 1A-11.
[0024] Figure 1A is a schematic illustration of a horizontal heat recovery
(HHR) coke
plant 100, configured in accordance with embodiments of the technology. The
HHR coke
plant 100 comprises ovens 105, along with heat recovery steam generators
(HRSGs) 120 and
an air quality control system 130 (e.g., an exhaust or flue gas
desulfurization (FGD) system),
both of which are positioned fluidly downstream from the ovens 105 and both of
which are
fluidly connected to the ovens 105 by suitable ducts. The HHR coke plant 100
also includes a
common tunnel 110 fluidly connecting individual ovens 105 to the HRSGs 120.
One or more
crossover ducts 115 fluidly connect the common tunnel 110 to the HRSGs 120. A
cooled gas
duct 125 transports the cooled gas from the HRSGs to the flue gas
desulfurization (FGD)
system 130. Fluidly connected and further downstream are a baghouse 135 for
collecting
particulates, at least one draft fan 140 for controlling air pressure within
the system, and a
main gas stack 145 for exhausting cooled, treated exhaust to the environment.
Steam lines
150 can interconnect the HRSG 120 and a cogeneration plant 155 so that the
recovered heat
can be utilized. Various coke plants 100 can have different proportions of
ovens 105, HRSGs
120, and other structures. For example, in some coke plants, each oven 105
illustrated in
Figure 1 can represent ten actual ovens.
[0025] As will be described in further detail below, in several embodiments
the
individual coke ovens 105 can include one or more air inlets configured to
allow outside air
into the negative pressure oven chamber to combust with the coal's VM. The air
inlets can be
used with one or more air distributors to direct, preheat, circulate, and/or
distribute air within
the oven chamber. The term "air" as used herein can include ambient air,
oxygen, oxidizers,
nitrogen, nitrous oxide, diluents, combustion gases, air mixtures, oxidizer
mixtures, flue gas,
recycled vent gas, steam, gases having additives, inerts, heat-absorbers,
liquid phase materials
such as water droplets, multiphase materials such as liquid droplets atomized
via a gaseous
carrier, aspirated liquid fuels, atomized liquid heptane in a gaseous carrier
stream, fuels such
as natural gas or hydrogen, cooled gases, other gases, liquids, or solids, or
a combination of
these materials. In various embodiments, the air inlets and/or distributors
can function (i.e.,
open, close, modify an air distribution pattern, etc.) in response to manual
control or
automatic advanced control systems. The air inlets and/or air distributors can
operate on a
dedicated advanced control system or can be controlled by a broader draft
control system that
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adjusts the air inlets and/or distributors as well as uptake dampers, sole
flue dampers, and/or
other air distribution pathways within coke oven system. The advanced control
systems will
be described in further detail below with reference to Figures 1B and 1C, and
specific
embodiments of several air inlets and air distributors will be described in
further detail below
with reference to Figures 2A-11.
[0026] Figures 1B and 1C illustrate further details related to the
structure and
mechanics of coke ovens and advanced control systems in coke ovens. Figure 1B
is an
isometric, partial cut-away view of a portion of the HHR coke plant configured
in accordance
with embodiments of the technology. Figure 1C is a sectional view of an HHR
coke oven
105 configured in accordance with embodiments of the technology. Referring to
Figures 1B
and 1C together, each oven 105 can include an open cavity defined by a floor
160, a front
door 165 forming substantially the entirety of one side of the oven, a rear
door 170 opposite
the front door 165 forming substantially the entirety of the side of the oven
opposite the front
door, two sidewalls 175 extending upwardly from the floor 160 intermediate the
front 165
and rear 170 doors, and a crown 180 which forms the top surface of the open
cavity of an
oven chamber 185. In various embodiments, the front or rear doors 165, 170 can
be full or
half-doors. Controlling air flow and pressure inside the oven chamber 185 can
be critical to
the efficient operation of the coking cycle and therefore the front door 165
includes one or
more primary air inlets 195 that allow primary combustion air into the oven
chamber 185. In
some embodiments, multiple air inlets 195 are interconnected (e.g., via a
ceramic tube or
other distribution system internal or external to the oven 105) such that air
is supplied to each
inlet 195 from the common tube. Each primary air inlet 195 includes a primary
air damper
190 which can be positioned at any of a number of positions between fully open
and fully
closed to vary the amount of primary air flow into the oven chamber 185. In
some
embodiments, the damper 190 can utilize a slide or a twist top control.
Alternatively, the one
or more primary air inlets 195 are additionally or alternately formed through
the crown 180,
floor 160, sidewalls 175, and/or other location (above, at, or below the coal
bed) within the
oven. As will be described in detail below, one or more air distributors can
be employed in
connection with a primary air inlet 195 to direct, preheat, and/or distribute
air within the oven
.chamber 185.
[0027] In operation, volatile gases emitted from the coal positioned inside
the oven
chamber 185 collect in the crown and are drawn downstream in the overall
system into
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downcomer channels 200 formed in one or both sidewalls 175. The downcomer
channels
fluidly connect the oven chamber 185 with a sole flue 205 positioned beneath
the over floor
160. The sole flue 205 forms a circuitous path beneath the oven floor 160.
Volatile gases
emitted from the coal can be combusted in the sole flue 205 thereby generating
heat to
support the reduction of coal into coke. The downcomer channels 200 are
fluidly connected
to chimneys or uptake channels 210 formed in one or both sidewalls 175. A
secondary air
inlet 215 can be provided between the sole flue 205 and atmosphere, and the
secondary air
inlet 215 can include a secondary air damper 220 that can be positioned at any
of a number of
positions between fully open and fully closed to vary the amount of secondary
air flow into
the sole flue 205. The uptake channels 210 are fluidly connected to the common
tunnel 110
by one or more uptake ducts 225. A tertiary air inlet 227 can be provided
between the uptake
duct 225 and atmosphere. The tertiary air inlet 227 can include a tertiary air
damper 229
which can be positioned at any of a number of positions between fully open and
fully closed
to vary the amount of tertiary air flow into the uptake duct 225.
[0028] In order
to provide the ability to control gas flow through the uptake ducts 225
and within the ovens 105, each uptake duct 225 also includes an uptake damper
230. The
uptake damper 230 can be positioned at any number of positions between fully
open and fully
closed to vary the amount of oven draft in the oven 105. The uptake damper 230
can
comprise any automatic or manually-controlled flow control or orifice blocking
device (e.g.,
any plate, seal, block, etc.). As used herein, "draft" indicates a negative
pressure relative to
atmosphere. For example a draft of 0.1 inches of water indicates a pressure of
0.1 inches of
water below atmospheric pressure. Inches of water is a non-SI unit for
pressure and is
conventionally used to describe the draft at various locations in a coke
plant. In some
embodiments, the draft ranges from about 0.12 to about 0.16 inches of water.
If a draft is
increased or otherwise made larger, the pressure moves further below
atmospheric pressure.
If a draft is decreased, drops, or is otherwise made smaller or lower, the
pressure moves
towards atmospheric pressure. By controlling the oven draft with the uptake
damper 230, the
air flow into the oven 105 from the air inlets 195, 215, 227 as well as air
leaks into the oven
105 can be controlled. Typically, as shown in Figure 1C, an individual oven
105 includes
two uptake ducts 225 and two uptake dampers 230, but the use of two uptake
ducts and two
uptake dampers is not a necessity; a system can be designed to use just one or
more than two
uptake ducts and two uptake dampers.
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[0029] A sample HHR coke plant 100 includes a number of ovens 105 that are
grouped
into oven blocks 235 (shown in Figure 1A). The illustrated HHR coke plant 100
includes
five oven blocks 235 of twenty ovens each, for a total of one hundred ovens.
All of the ovens
105 are fluidly connected by at least one uptake duct 225 to the common tunnel
110 which is
in turn fluidly connected to each HRSG 120 by a crossover duct 115. Each oven
block 235 is
associated with a particular crossover duct 115. The exhaust gases from each
oven 105 in an
oven block 235 flow through the common tunnel 110 to the crossover duct 115
associated
with each respective oven block 235. Half of the ovens in an oven block 235
are located on
one side of an intersection 245 of the common tunnel 110 and a crossover duct
115 and the
other half of the ovens in the oven block 235 are located on the other side of
the intersection
245.
[0030] A HRSG valve or damper 250 associated with each HRSG 120 (shown in
Figure 1A) is adjustable to control the flow of exhaust gases through the HRSG
120. The
HRSG valve 250 can be positioned on the upstream or hot side of the HRSG 120,
or can be
positioned on the downstream or cold side of the HRSG 120. The HRSG valves 250
are
variable to a number of positions between fully opened and fully closed and
the flow of
exhaust gases through the HRSGs 120 is controlled by adjusting the relative
position of the
HRSG valves 250.
[0031] In operation, coke is produced in the ovens 105 by first loading
coal into the
oven chamber 185, heating the coal in an oxygen depleted environment, driving
off the
volatile fraction of coal and then oxidizing the VM within the oven 105 to
capture and utilize
the heat given off. The coal volatiles are oxidized within the ovens over an
extended coking
cycle, and release heat to regeneratively drive the carbonization of the coal
to coke. The
coking cycle begins when the front door 165 is opened and coal is charged onto
the oven floor
160. The coal on the oven floor 160 is known as the coal bed. Heat from the
oven (due to the
previous coking cycle) starts the carbonization cycle. In some embodiments, no
additional
fuel other than that produced by the coking process is used. Roughly half of
the total heat
transfer to the coal bed is radiated down onto the top surface of the coal bed
from the
luminous flame of the coal bed and the radiant oven crown 180. The remaining
half of the
heat is transferred to the coal bed by conduction from the oven floor 160
which is
convectively heated from the volatilization of gases in the sole flue 205. In
this way, a
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carbonization process "wave" of plastic flow of the coal particles and
formation of high
strength cohesive coke proceeds from both the top and bottom boundaries of the
coal bed.
[0032]
Typically, each oven 105 is operated at negative pressure so air is drawn into
the
oven during the reduction process due to the pressure differential between the
oven 105 and
atmosphere. Primary air for combustion is added to the oven chamber 185 to
partially
oxidize the coal volatiles, but the amount of this primary air is controlled
so that only a
portion of the volatiles released from the coal are combusted in the oven
chamber 185,
thereby releasing only a fraction of their enthalpy of combustion within the
oven chamber
185. The primary air can be introduced into the oven chamber 185 above the
coal bed
through the primary air inlets 195, with the amount of primary air controlled
by the primary
air dampers 190. The primary air dampers 190 can also be used to maintain the
desired
operating temperature inside the oven chamber 185.
[0033] The
partially combusted gases pass from the oven chamber 185 through the
downcomer channels 200 into the sole flue 205 where secondary air is added to
the partially
combusted gases. The secondary air is introduced through the secondary air
inlet 215. The
amount of secondary air that is introduced is controlled by the secondary air
damper 220. As
the secondary air is introduced, the partially combusted gases are more fully
combusted in the
sole flue 205, thereby extracting the remaining enthalpy of combustion which
is conveyed
through the oven floor 160 to add heat to the oven chamber 185. The fully or
nearly-fully
combusted exhaust gases exit the sole flue 205 through the uptake channels 210
and then
flow into the uptake duct 225. Tertiary air is added to the exhaust gases via
the tertiary air
inlet 227, where the amount of tertiary air introduced is controlled by the
tertiary air damper
229 so that any remaining fraction of uncombusted gases in the exhaust gases
are oxidized
downstream of the tertiary air inlet 227. At the end of the coking cycle, the
coal has coked
out and has carbonized to produce coke. The coke is preferably removed from
the oven 105
through the rear door 170 utilizing a mechanical extraction system. Finally,
the coke is
quenched (e.g., wet or dry quenched) and sized before delivery to a user.
[0034] As
discussed above, control of the draft in the ovens 105 can be implemented by
automated or advanced control systems. An advanced draft control system, for
example, can
automatically control an uptake damper that can be positioned at any one of a
number of
positions between fully open and fully closed to vary the amount of oven draft
in the oven
105. The automatic uptake damper can be controlled in response to operating
conditions
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(e.g., pressure or draft, temperature, oxygen concentration, gas flow rate,
downstream levels
of hydrocarbons, water, hydrogen, carbon dioxide, or water to carbon dioxide
ratio, etc.)
detected by at least one sensor. The automatic control system can include one
or more
sensors relevant to the operating conditions of the coke plant 100. In some
embodiments, an
oven draft sensor or oven pressure sensor detects a pressure that is
indicative of the oven
draft. Referring to Figures 1A-1C together, the oven draft sensor can be
located in the oven
crown 180 or elsewhere in the oven chamber 185. Alternatively, an oven draft
sensor can be
located at either of the automatic uptake dampers 305, in the sole flue 205,
at either oven door
165 or 170, or in the common tunnel 110 near or above the coke oven 105. In
one
embodiment, the oven draft sensor is located in the top of the oven crown 180.
The oven
draft sensor can be located flush with the refractory brick lining of the oven
crown 180 or
could extend into the oven chamber 185 from the oven crown 180. A bypass
exhaust stack
draft sensor can detect a pressure that is indicative of the draft at the
bypass exhaust stack 240
(e.g., at the base of the bypass exhaust stack 240). In some embodiments, a
bypass exhaust
stack draft sensor is located at the intersection 245. Additional draft
sensors can be
positioned at other locations in the coke plant 100. For example, a draft
sensor in the
common tunnel could be used to detect a common tunnel draft indicative of the
oven draft in
multiple ovens proximate the draft sensor. An intersection draft sensor can
detect a pressure
that is indicative of the draft at one of the intersections 245.
[0035] An oven temperature sensor can detect the oven temperature and can
be located
in the oven crown 180 or elsewhere in the oven chamber 185. A sole flue
temperature sensor
can detect the sole flue temperature and is located in the sole flue 205. A
common tunnel
temperature sensor detects the common tunnel temperature and is located in the
common
tunnel 110. A HRSG inlet temperature sensor can detect the HRSG inlet
temperature and can
be located at or near the inlet of the HRSG 120. Additional temperature or
pressure sensors
can be positioned at other locations in the coke plant 100.
[0036] An uptake duct oxygen sensor is positioned to detect the oxygen
concentration
of the exhaust gases in the uptake duct 225. An HRSG inlet oxygen sensor can
be positioned
to detect the oxygen concentration of the exhaust gases at the inlet of the
HRSG 120. A main
stack oxygen sensor can be positioned to detect the oxygen concentration of
the exhaust gases
in the main stack 145 and additional oxygen sensors can be positioned at other
locations in
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the coke plant 100 to provide information on the relative oxygen concentration
at various
locations in the system.
[0037] A flow sensor can detect the gas flow rate of the exhaust gases. For
example, a
flow sensor can be located downstream of each of the HRSGs 120 to detect the
flow rate of
the exhaust gases exiting each HRSG 120. This information can be used to
balance the flow
of exhaust gases through each HRSG 120 by adjusting the HRSG dampers 250.
Additional
flow sensors can be positioned at other locations in the coke plant 100 to
provide information
on the gas flow rate at various locations in the system. Additionally, one or
more draft or
pressure sensors, temperature sensors, oxygen sensors, flow sensors,
hydrocarbon sensors,
and/or other sensors may be used at the air quality control system 130 or
other locations
downstream of the HRSGs 120. In some embodiments, several sensors or automatic
systems
are linked to optimize overall coke production and quality and maximize yield.
For example,
in some systems, one or more of an air inlet 195, an inlet damper 190, a sole
flue damper,
and/or an oven uptake damper can all be linked (e.g., in communication with a
common
controller) and set in their respective positions collectively. In this way,
the air inlets 195 can
be used to adjust the draft as needed to control the amount of air in the oven
chamber 185. In
further embodiments, other system components can be operated in a
complementary manner,
or components can be controlled independently.
[0038] An actuator can be configured to open and close the various dampers
(e.g.,
uptake dampers 230 or air dampers 190). For example, an actuator can be a
linear actuator or
a rotational actuator. The actuator can allow the dampers to be infinitely
controlled between
the fully open and the fully closed positions. In some embodiments, different
dampers can be
open or closed to different degrees. The actuator can move the dampers amongst
these
positions in response to the operating condition or operating conditions
detected by the sensor
or sensors included in an automatic draft control system. The actuator can
position the uptake
damper 230 based on position instructions received from a controller. The
position
instructions can be generated in response to the draft, temperature, oxygen
concentration,
downstream hydrocarbon level, or gas flow rate detected by one or more of the
sensors
discussed above; control algorithms that include one or more sensor inputs; a
pre-set
schedule, or other control algorithms. The controller can be a discrete
controller associated
with a single automatic damper or multiple automatic dampers, a centralized
controller (e.g.,
a distributed control system or a programmable logic control system), or a
combination of the
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two. Accordingly, individual primary air inlets 195 or dampers 190 can be
operated
individually or in conjunction with other inlets 195 or dampers 190.
[0039] The automatic draft control system can, for example, control an
automatic
uptake damper 230 or air inlet damper 190, 220, or 229 in response to the oven
draft detected
by an oven draft sensor. The oven draft sensor can detect the oven draft and
output a signal
indicative of the oven draft to a controller. The controller can generate a
position instruction
in response to this sensor input and the actuator can move the uptake damper
230 or air inlet
damper 190, 220, or 229 to the position required by the position instruction.
In this way, an
automatic control system can be used to maintain a targeted oven draft.
Similarly, an
automatic draft control system can control automatic uptake dampers, inlet
dampers, the
HRSG dampers 250, and/or the draft fan 140, as needed, to maintain targeted
drafts at other
locations within the coke plant 100 (e.g., a targeted intersection draft or a
targeted common
tunnel draft). The automatic draft control system can be placed into a manual
mode to allow
for manual adjustment of the automatic uptake dampers, the HRSG dampers,
and/or the draft
fan 140, as needed. In still further embodiments, an automatic actuator can be
used in
combination with a manual control to fully open or fully close a flow path. As
mentioned
above, the air inlets 195 can be positioned in various locations on the oven
105 and can
likewise utilize an advanced control system in this same manner. In some
embodiments
having both crown 180 and door 165 air entry, the inlets can be controlled
collectively to
drive flow circulation within the chamber 185. In various embodiments,
individual ovens
105 are controlled separately, while in further embodiments a series of ovens
are controlled
together.
[0040] Figure 2A is an isometric, partially transparent view of a portion
of a coke oven
205 having door baffles or air distributors 251 configured in accordance with
embodiments of
the technology. As described above with reference to Figures 1A-1C, the oven
205 includes a
plurality of primary air inlets 195 configured to introduce air into the oven
chamber 185. The
inlets 195 can be circular, slotted, or other-shaped apertures. The
distributors 251 are
positioned proximate to the air inlets 195 within the oven chamber 185 and are
configured to
distribute, preheat, channel, damper, and/or redirect air entering the oven
chamber 185. The
inlets 195 can have a continuous diameter or width W through the depth D of
the oven door
165 or can taper to control pressure. Further, the inlets 195 can be angled
with reference to a
horizontal axis generally parallel with the oven floor.
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[0041] Figure 2B is an isometric view of the door air distributor 251 and
Figure 2C is a
side view of the door air distributor 251 configured in accordance with
embodiments of the
technology. Referring to Figures 2B and 2C together, the distributor 251
comprises an
annulus flow deflecting baffle having an inner diameter B, and an outer
diameter Bo and a
depth BD. As shown, in some embodiments Bo is greater than B,, causing the air
distributor
251 to have an angled or fanned side profile to expand the distribution
profile and disperse
incoming air. In some embodiments, the air distributor 251 has an elevation
difference from
about 1-2 inches over its depth BD. In further embodiments, Bo can be less
than B, in order to
narrow the distribution profile or increase pressure on the incoming air to
modify the air's
distribution profile (e.g., so the air can enter at a higher pressure and
extend further into the
chamber 185). In further embodiments, the air distributor 251 has a constant
diameter. The
air distributor's depth BD can cause the air distributor 251 to extend into
the oven chamber
185 to deliver air further towards the center of the chamber 185. In other
embodiments, the
air distributor 251 can be flush or nearly flush with the oven door 165 or can
be. external to
the oven chamber 185. While three inlets 195 and distributors 251 are shown,
there can be
more or fewer in further embodiments of the technology.
[0042] Figure 2D is a partially schematic, top view of the door air
distributor 251
forming a vortex air pattern V and configured in accordance with embodiments
of the
technology. Referring to Figures 2A-2D together, in operation, the
distributors 251 spread
the air jet entering the oven chamber 185 and prevent the air jet from dipping
as close to the
coal/coke surface as would an air jet not subjected to an air distributor 251.
The distributors
251 accordingly promote combustion before the air hits the coal/coke surface.
In some
embodiments, the distributor 251 is spaced apart from the oven door 165 and is
positioned
generally in front of or proximate to the inlet 195. Air entering the oven
chamber 185 passes
both through and around the distributor 251. The combination of these air flow
patterns can
create the vortex air pattern V in front of the distributor 251. The
distributor 251 can thus be
thought of as a vortex generator. The vortex pattern V can cause the air to
stall, spin, and in
some cases heat before continuing further into the oven chamber. The vortex V
can enhance
mixing between incoming air and combustion gases and create a flame having
some
characteristics of a premixed flame. In some cases, the vortex V can anchor a
flame to
mitigate cold air dipping.
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[0043] The air entering the oven chamber 185 can also be preheated within
the oven
door, 165, the air distributors 251, and/or the inlets 195. More specifically,
these features can
function as heat exchangers, warming incoming air with heat from the oven or
other source.
In further embodiments, the incoming air is preheated external of the oven
205, such as in a
conduit or chamber. In still further embodiments, the air can be preheated
within an oven
structure (e.g., within a sidewall, crown, door, or floor). In still further
embodiments, the air
is partially preheated external of the oven chamber 185 and then further
heated proximate to
the distributor 251 within the chamber 185. In various embodiments, the air
entering the
chamber 185 can be pressurized, controlled by a broader draft control system
as described
above, or flow freely or unpressurized. Further, the air can be cold, warm, or
hot.
[0044] The distributors 251 can reduce yield loss by preventing direct
contact between
the incoming jet of air and the coal bed. More specifically, the oxygen in the
air can be
directed toward the crown region to burn the VM released by the coal in the
coking process.
The distributors can affect the air flow by injecting the air at a location
further from the
coal/coke surface, redirecting the air stream momentum away from the coal/coke
surface,
dispersing the air before it reaches the coal/coke surface, preheating the air
to lower its
density such that it has more time to burn or disperse before reaching the
coal/coke surface, or
a combination of these techniques. Any of these techniques can provide
improved contact
between the air and the hot oven gases, providing for faster dispersion/mixing
of the oxygen
with the oven gases.
[0045] Figure 3A is an isometric, partially transparent view of a coke oven
305 having
crown air inlets 361 configured in accordance with embodiments of the
technology. The
crown air inlets 361 can have several features generally similar to the door
air inlets 195
described above with reference to Figures 1A-2D. For example, the crown air
inlets 361
introduce combustion air through the crown 180 and into the oven chamber 185.
Each air
inlet 361 can include an air damper which can be positioned at any of a number
of positions
between fully open and fully closed to vary the amount of air flow into the
oven chamber 185.
The coke oven 305 further includes one or more distributors 363 configured to
channel/distribute air flow into the oven chamber 185.
[0046] As shown schematically in Figure 3B, each distributor 363 comprises
a
deflection plate or impingement baffle configured to disperse or redirect air
entering the oven
chamber 185. The distributor 363 can be coupled to the crown 180, inlet 361,
or other oven
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feature. For example, the distributor 363 can be suspended and spaced apart
from the crown
180. As air (represented by arrowed flow lines) enters the inlet 361, the air
interfaces with
and is diverted by the distributor 363. The distributor 363 can accordingly
alter the manner in
which the air enters and behaves in the oven chamber 185. More specifically,
the distributors
363 spread the incoming air laterally and can cause more uniform thermal
distribution within
the crown and provide better air-VM mixing and combustion in the crown region.
[0047] In various embodiments, the distributor 363 can be steel, ceramic,
ceramic
mesh, or other material suitable for withstanding the high oven temperatures.
The distributor
363 can be a solid material or can have one or more apertures therein. While
the inlet 361 is
shown as having two side apertures to accept air, in further embodiments the
inlet 361 can
have more or fewer apertures and the apertures can be on the sides or the top
of the inlet 361
or can have other suitable arrangements. Similarly, the distributor 363 can
allow air flow into
the oven chamber 185 via more or fewer than two lateral passageways. Further,
the inlet 361
and distributor 363 can have a rectangular, circular, or other shaped cross-
section, and the
apertures therein can comprise slots, tubes, ports, or any other flow-allowing
orifice.
[0048] In some embodiments, the inlet 361 and/or distributor 363 can
provide
preheating of incoming air to lower its density in the manner described above.
For example,
the inlet 361 can comprise a ceramic or other tube that runs along the top of
the oven 305 and
receives heat from the oven 305 or other source. In other embodiments, such a
heat exchange
tube can be inside the oven. In still further embodiments, the inlet 361 can
comprise a burner
or other heater on the exterior of the oven 305 that heats the incoming air
with natural gas or
other material. The preheating material can be burned before it reaches the
oven or can be
introduced to the oven with the air. In further embodiments, an inert gas,
combustion gas,
dilution gas, or cooling gas can be added to the chamber 185 via the inlet 361
and/or
distributor 363. Any of these gases can be introduced manually or as part of
an advanced
control system in response to a sensed operating condition. In a particular
embodiment, for
example, fuel can be added during or at the end of a coking cycle in response
to a command
by the advanced control system. In other embodiments, different materials can
be added at
different times during the coking cycle. For example, in some embodiments, an
inert can be
added during the first half of the coking cycle to prevent the influx of
oxidizers and create a
more purely pyrolytic environment. The inlet 361 and/or distributor 363 can
function as a
distribution system to supply mixtures of a heating fuel (e.g., natural gas,
inert gas, dilution
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gas) and air to the oven chamber 185. In various embodiments, there can be
more or fewer
air inlets 361 than shown, and in a particular embodiment there are six inlets
361.
[0049] Figure 4 is a schematic illustration of a crown air distributor 463
configured in
accordance with further embodiments of the technology. The distributor 463 can
comprise a
tiered set of baffles channeling air through a plurality of apertures 467. In
operation, air
enters an air inlet 461 and the distributor 463 spreads the air to a range of
depths in the oven
chamber 185 and laterally into the crown region. While the illustrated
distributor 463
comprises three apertures 467 on only one side, in further embodiments there
can be apertures
on multiple sides and there can be more of fewer apertures 467 at the same or
additional tiers.
[0050] Figure 5 is a schematic illustration of a crown air distributor 563
configured in
accordance with further embodiments of the technology. The distributor 563 has
several
features generally similar to the distributor 363 described above with
reference to Figure 3B.
For example, the distributor 563 can be suspended from the crown 180 and can
receive air
from an air inlet 561. The distributor 563 can be vertically elongated to
extend to a further
depth in the oven chamber 185. The distributor 563 can accordingly spread air
to a region
closer to the coal bed and further spaced apart from the crown 180. The
elongated distributor
563 can also provide additional air preheating time via heat exchange as
described above. In
various embodiments, the distributor 563 can have a fixed depth or can have
one or more
variable baffles, adjustable springs or hinges, or other components to provide
for a dynamic
depth of distribution of air into the oven chamber 185.
[0051] Figure 6 is a schematic illustration of a crown air distributor 663
configured in
accordance with further embodiments of the technology. The distributor 663 has
several
features generally similar to the distributors described above. The
distributor 663 can be
suspended from the crown 180 and can receive air from an air inlet 661. The
distributor 663
can be laterally elongated and have a plurality of apertures 667 on a downward-
facing side.
In further embodiments, the distributor 663 can be laterally elongated in only
one direction
and/or can have apertures additionally or alternately on other sides or upward-
facing surfaces.
The distributor 663 can accordingly spread air laterally and downward and can
cause more
uniform thermal distribution within the crown 180. By using a laterally
elongated distributor
having multiple distribution apertures 667, in some embodiments only a few or
a single inlet
661 may be needed to provide air to the chamber 185.
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[0052] Figure 7 is a schematic illustration of a door air distributor 751
configured in
accordance with further embodiments of the technology. The distributor 751 is
generally
cylindrically shaped and extends from and/or through the oven door 165. In
some
embodiments the distributor 751 extends into the oven chamber 185, while in
other
embodiments the distributor 751 is flush with the door 165 or a sidewall.. The
distributor 751
can be angled (e.g., angle 0) with respect to the oven door 165. In further
embodiments, the
distributor 751 can be more or less angled with respect to the door 165, and
can cause air to
flow upward, downward, or sideways into the oven chamber 185. In some
embodiments, the
angle 0 is selected to direct cool air sufficiently away from the coal bed to
prevent surface
burn, but not so steep as to cause burning or other damage to the crown. The
distributor 751
can accordingly direct air from the air inlet 195 to a desired location to
maximize thermal
distribution and VM combustion. In further embodiments, the position of the
distributor with
respect to the door 165 can be dynamic. For example, the angle 0 can change
manually or
automatically in response to a sensed oven temperature, pressure, oxygen
level, or draft
condition.
[0053] Figure 8 is a schematic illustration of a door air distributor 851
configured in
accordance with further embodiments of the technology. The distributor 851 is
generally
similar to the distributor 751 described above with reference to Figure 7. For
example, the
distributor 851 can be generally cylindrically-shaped and can extend from the
air inlet 195
into the oven chamber 185 and be angled with respect to the oven door 165.
Further, the
distributor 851 can have a redirection plate 881 at a lateral end configured
to redirect the air
flow in a given direction. For example, in the illustrated embodiment, the
redirection plate
881 forces air flow in an upward direction.
[0054] While the redirection plate 881 is illustrated as being coupled to a
lower portion
of the distributor 851, in further embodiments the redirection plate 881 can
be coupled to
other portions of the distributor 851, the door 165, or can otherwise be
suspended in the oven
chamber 185. Further, the connection between the redirection plate 881 and the
rest of the
distributor can be sharply angled, as shown, or can comprise a smooth contour,
and can be
static or dynamic.
[0055] Figure 9 is a schematic illustration of a door air distributor 951
configured in
accordance with still further embodiments of the technology. The distributor
951 is generally
similar to the distributor 851 described above with reference to Figure 8. For
example, the
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distributor 951 can be generally cylindrically shaped and can extend from the
air inlet 195
into the oven chamber 185 and be angled with respect to the oven door 165.
Further, a
redirection plate 957 can be spaced apart from the distributor 951 and
configured to channel
or redirect air flow into the oven chamber 185. The redirection plate 957 can
be coupled to
the distributor 951 or can be otherwise coupled to or suspended in the oven
chamber 185.
The angle of the redirection plate 957 with respect to the door 165 and
distributor 951 can
control the airflow distribution pattern in the chamber 185. In the
illustrated embodiment, for
example, the redirection plate 957 is positioned generally orthogonal to the
pattern of air flow
through the distributor 951. The air flow therefore interfaces with the
redirection plate 957
and is channeled upward toward the crown and downward toward the coal bed. In
some
embodiments, the redirection plate 957 and/or the distributor 951 can be
dynamically angled
or otherwise movable with reference to each other.
[0056] Figure 10 is a schematic illustration of a door air distributor 1051
configured in
accordance with further embodiments of the technology. The distributor 1051 is
generally
similar to the distributor 751 described above with reference to Figure 7.
Instead of a
generally cylindrical shape, however, the distributor 1051 comprises a curved
shape providing
a serpentine air flow pathway. While the illustrated embodiments comprises an
"S" shape
extending inward from the oven door 165 to the chamber 185, in further
embodiments the
distributor 1051 can have more or fewer curves of various angles. In some
embodiments, the
curved shape can cause the air entering the oven chamber 185 to spend an
extended time in
the distributor 1051 as compared to shorter, straighter pathways. The longer
residence time in
the distributor 1051 can cause the inletting air to be preheated so it does
not jet to the
coal/coke surface and cause surface burn.
[0057] Figure 11 is a schematic illustration of a door air distributor 1151
configured in
accordance with further embodiments of the technology. The distributor 1151
has several
features generally similar to the distributors described above. For example,
the distributor
1151 can be generally cylindrically shaped and can extend from the air inlet
195 into the oven
chamber 185. The distributor 1151 can further include a plurality of apertures
1159
configured to release air at various points above and below the distributor at
various distances
from the oven door 165. In further embodiments, there can be more or fewer
apertures1159
and the apertures 1159 can be positioned on more or fewer sides of the
distributor 1151.
Additionally, while the illustrated distributor 1151 is shown to be generally
orthogonal to the
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oven door 165, in further embodiments the distributor 1151 can be angled
relative to the door
165.
Examples
1. A coke oven air distribution system, comprising:
an oven chamber having an oven floor configured to support a coal bed, a
plurality of
sidewalls extending upward from the oven floor, and an oven crown covering
a top portion of the oven chamber;
an air inlet positioned above the oven floor and configured to introduce air
into the
oven chamber; and
a distributor proximate to the inlet and configured to at least one of
preheat, redirect,
or disperse air within the oven chamber.
2. The system of example 1 wherein the air inlet comprises an inlet in the
oven
crown.
3. The system of example 1 wherein the air inlet comprises an inlet in an
individual sidewall.
4. The system of example 3 wherein the individual sidewall comprises an
oven
door.
5. The system of example 1 wherein the distributor comprises a generally
cylindrical tube extending into the oven chamber.
6. The system of example 5 wherein the distributor comprises an impingement
plate generally orthogonal to the cylindrical tube.
7. The system of example 1 wherein the distributor comprises an annulus
flow
deflecting baffle.
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8. The system of example 1 wherein the distributor comprises an elongated
channel having a plurality of apertures therein.
9. The system of example 8 wherein the elongated channel is elongated in a
direction generally parallel to the sidewalls.
10. The system of example 8 wherein the elongated channel is elongated in a
direction generally parallel to the oven floor.
11. The system of example 1 wherein the distributor comprises a serpentine
pathway.
12. The system of example 1 wherein the distributor comprises a pathway
angled
in a direction away from the oven floor.
13. The system of example 1, further comprising an inlet damper coupled to
the
inlet and configured to be positioned at any one of a plurality of positions
including fully
opened and fully closed.
14. The system of example 13, wherein the inlet damper is automatically
movable
between positions in response to at least one of a draft, oxygen
concentration, or temperature
condition in the oven.
15. The system of example 1, further comprising at least one of a conduit
or a
chamber external to the oven chamber and in fluid communication with the air
inlet, wherein
the conduit or chamber is configured to contain and/or heat air prior to
introduction to the
oven.
16. The system of example 15 wherein the conduit or chamber is positioned
within
one or more of the sidewalls, oven floor, or oven crown.
17. A method of controlling air distribution within a coke oven, the method
comprising:
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inletting air into an oven chamber, the oven chamber comprising a floor, a
crown, and
a plurality of sidewalls connecting the floor and the crown, wherein at least
one of the sidewalls comprises a door;
using a distributor to alter a pathway of the air in the chamber; and
heating the air along the altered pathway.
18. The method of example 17 wherein inletting air into an oven chamber
comprises inletting air through at least one of the crown, one of the
sidewalls, or the door.
19. The method of example 17 wherein heating the air along the altered
pathway
comprises utilizing the distributor as a heat exchanger.
20. A coke oven, comprising:
an oven chamber;
an air inlet in fluid communication with the oven chamber, the air inlet being
configured to supply gas to the oven chamber;
a distributor coupled to the air inlet and configured to at least one of
preheat, redirect,
or distribute the gas;
an inlet damper in fluid communication with at least one of the distributor or
the air
inlet, the inlet damper being positioned at any one of a plurality of
positions
including fully opened and fully closed, the inlet damper configured to
control
an oven draft;
an actuator configured to alter the position of the inlet damper between the
plurality of
positions in response to a position instruction; and
a controller in communication with the actuator and configured to provide the
position
instruction to the actuator.
21. The coke oven of example 20, wherein the air inlet comprises a
plurality of air
inlets, each air inlet having an inlet damper and an actuator, and wherein the
controller
communicates with the plurality of actuators collectively.
22. The coke oven of example 20, wherein the air inlet comprises a
plurality of air
inlets, each air inlet having an inlet damper and an actuator, and wherein the
controller
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,
comprises a plurality of controllers, each controller configured to
communicate with an
individual actuator.
23.
The coke oven of example 20, further comprising an uptake damper in
communication with the controller, wherein the controller is configured to
control positions
of the inlet damper and the uptake damper collectively.
[0058]
The systems and methods disclosed herein offer several advantages over
traditional coke oven systems. The distributors can improve overall coke
productivity and
enhance VM gas-air combustion characteristics by better distributing air
within the oven
chamber and/or preheating air before introducing it to the chamber. The
improved air
distribution reduces coke surface burn loss and increases overall coke yield.
This improved
coke productivity enables better and "cleaner" combustion and more uniform
temperatures in
the oven crown. A more uniform temperature within the crown region helps
prevent any
potential hot-spots on the oven refractory walls, thus minimizing damage and
costly repairs to
the oven. Further, better distribution in the oven can require fewer inlets,
which can enable
easier advanced control over oven operation.
[0059]
From the foregoing it will be appreciated that, although specific
embodiments of
the technology have been described herein for purposes of illustration,
various modifications
may be made without deviating from the scope of the technology. For example,
while certain
embodiments have been described as being sidewall, door, or crown air
inlets/distributors,
these inlets/distributors can be placed at any suitable location in the coke
oven. Further,
certain aspects of the new technology described in the context of particular
embodiments may
be combined or eliminated in other embodiments. Moreover, while advantages
associated
with certain embodiments of the technology have been described in the context
of those
embodiments, other embodiments may also exhibit such advantages, and not all
embodiments
need necessarily exhibit such advantages to fall within the scope of the
technology.
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