Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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POLLUTION CONTROL APPARATUS FOR INDUSTRIAL PROCESSES AND THE
LIKE
This application is a divisional of Canadian
Patent Application Serial No. 2,139,501 filed July 6, 1993.
This invention relates to control of pollution and
emissions from industrial processes. More particularly,
this invention relates to apparatus which generates heat and
emissions which are trapped in a containment building and
which are extracted from the atmosphere within the
containment building.
Certain processes are well known to produce
substantial quantities of heat and also particulate and
gaseous emission. Such processes are common in the metals
industries and include equipment such as top-blown oxygen
converters and by-product coke ovens.
Coke ovens have been particularly difficult to
operate in compliance with existing environmental
regulations. Substantial amounts of heat are evolved in the
operation of a coke oven. Problems of emissions and
atmospheric pollution arise when incandescent coke is pushed
from an oven into a quench car, when the incandescent coke
is quenched, and when tars are burned off the oven door
seals to permit a tight fit to be maintained when the oven
is recharged with coking coal. Despite ongoing and diligent
efforts to resolve pollution problems, pollution control
continues to be a major effort in coke oven operation.
I have invented new and useful improvements in
pollution control apparatus for industrial processes and the
like. I provide a containment structure encJ_osing the
processing equipment and including a barrier to isolate the
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equipment from the atmosphere. I further provide gas-
cleaning apparatus having an intake and a discharge within
the containment structure. I further provide refrigeration
apparatus in which an evaporator is positioned in heat
exchange relationship with the atmosphere within the
containment structure and a refrigeration condenser is
positioned in heat exchange relationship with a heat
receiving medium outside the containment structure.
Preferably, I provide an absorption refrigeration system
having a generator in heat exchange relationship with hot
gases within the containment structure and which is
activated by heat generated by the processing equipment.
Preferably, I position the refrigeration evaporator adjacent
to the wall of the containment structure. I may incorporate
the evaporator within the containment structure as by a
series of interconnected passages.
In one form of my invention, I place the
refrigeration generator at a location within the containment
structure where temperature differentials within the
containment structure will tend to cause flow of hot gases
toward the generator.
The invention provides a process of collecting
pollutants produced by a process that generates hot gases
carrying pollutants, which comprises: (a) collecting the hot
gases within a containment structure which separates the hot
gases from the atmosphere, (b) passing the hot gases through
gas cleaning apparatus in flow relationship to the inside of
the containment structure and separating pollutants from the
hot gases, (c) removing separated pollutants from the
containment structure, (d) providing an absorption
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refrigeration system comprising a generator, a condenser, an
evaporator positioned in heat exchange relationship to the
containment structure, and a refrigerant which circulates
therethrough, (e) passing the hot gases through the
generator of the refrigeration system, (f) passing a cooling
medium through the condenser of the refrigeration system,
(g) passing chilled refrigerant through the evaporator of
the refrigeration system whereby the containment structure
is maintained at a safe working temperature.
Other details, objects, and advantages of my
invention will become more apparent as the following
description of the present preferred embodiment thereof
proceeds.
In the accompanying drawings, I have illustrated
pollution control apparatus embodying my invention in
perspective in which:
Figure 1 is a perspective view of an installation
incorporating my invention for use in handling coke oven
emissions, and
Figure 2 is a diagrammatic view of a refrigeration
system used in the installation shown in Figure 1.
Figure 3 is an installation similar to that shown
in Figure 1 in which the generator is positioned in a stream
of hot gases created in whole or in part by temperature
differentials within the containment structure.
Figure 1 shows a containment structure in the form
of a large dome 1 positioned around a coke oven battery 2 of
conventional design. The dome comprises an interconnecting
lattice work of hollow tubes 3 having an impervious covering
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impervious covering 4 which acts as a barrier separating the
atmosphere within the dome from the surrounding atmosphere.
To provide the heat necessary to roast the coal, a
combustion system is provided within the dome. Although the
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coking chambers and the combustion chambers share space
under the dome, there is no interchange of atmosphere be-
tween the systems. Heat only flows through the furnace
walls to the coke oven. Because coal is taken into the dome
and coke and other products are taken out of the dome by
self-sealing transportation systems, it is'possible to
hermetically seal the containment building. In practice, it
will be necessary to open the sealed building to allow
access for maintenance.personnel. However, an efficient
locking system will ensure a minimum of leakage in either
direction.
The coke oven battery includes a series of ovens
5, a coal storage bin 6, and a lorry car 7 mounted on top of~
the ovens for transfer of coal from the storage bin to the
individual ovens. A quench car 8- is provided to transfer
hct coke after pushing from an oven to a quenching tower 9.
Coking coal is delivered to the plant by rail cars l0 which
are unloaded at transfer point 11: The coal is converted to
a water slurry which is transported into the containment .
structure through a pipe 12 and is dumped into a dewatering
hopper 13. Dewatered coal passes through a conveyor l4 to
storage bin 6.
A receiving hopper 15 is positioned to receive
quenched coke from quenching station 9. A hydro-transport
system 16, which includes a water trap, leads from hopper 15
to a handling building 17 where the coke is dewatered.
Dewatered coke is taken from building 17 by a conveyor 18 .
and is deposited on a storage pile 19.
The coke ovens are fired in the usual manner
employing coke oven 'gas; blast furnace gas, or the like.
Combustion air is supplied from outside dome l through a
duct which is not shown. Air and fuel gas are burned and
are used to heat the coal within the,ovens. The combustion .
products are collected in a main conduit 20 which vents to, the
atmosphere through a chimney 21 which extends through the
wall of containment structure 1 into,the outside atmosphere.
Because the combustion system is not connected to the space
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inside the dome, there is no transfer of pollutants.enclosed .
by the dome to the outside.
A large volume of particulate matter and gases are
evolved from the coking process. The atmosphere within the
containment structure is continuously recirculated through
an air scrubber 22 having an intake 23 and.a discharge 24.
Materials removed from the recirculating atmosphere inside
the containment structure as well as the coke products are
removed from the containment structure by a hydro-transport
' 10 system having a water seal or other suitable barrier to
prevent gas flow between the outside.and the inside of the
containment structure. Since there is no passage of air
into or out of the dome the air within will quickly become
oxygen-starved as the oxygen content of the air is consumed.
Provided that any make up volume is in the form of an inert
gas it is possible to ~~-y que_nch the coke by blowing the
contained,stmosghere through the coke.
~A hot gas duct 25 is mounted on the top of the
coke oven battery and has a plurality of hot gas intakes 26
mounted above the quenching area. The duct extends to a
casing 27 which has an induced draft fan mounted in it and a
discharge 28.
The refrigeration system is shown in diagrammatic
form in Figure 2. Hot gases flowing in duct 25 is repre-
sented by reference number 29. The hot gases pass through
generator 30 of the refrigeration system and leave, after
giving up heat, as a cooler stream 31 which passes through
discharge 28 into the dome. The generator contains a mix-
ture of water and ammonia. Heating of the mixture drives
ammonia vapor through conduit 32 to a condenser 33 where
heat is extracted from the ammonia and the ammonia is con-
densed to a liquid. The heat is delivered to a heat sink 34
which may be. in the form of hot water or steam which is then
used for space heating or other form of co-generation. The
cooled ammonia then passes through a conduit. 35 to a reser-
voir 36 and through a conduit 37 to an. expansion valve~38
and then to an evaporator 39. In th,e structure shown in.
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Figure 1, the hollow latticework structure 3 serves as the
evaporator~and absorbs heat from the surrounding structure
and the atmosphere within the dome. Alternatively, the
refrigerant may be used to cool only a selected and con-
trolled part of the latticework. Flow of heat is shown by
the arrows extending from dome 1 to evaporator 39. Refrig-
.erant warmed in evaporator 39 passes through a conduit 40 to
an absorber 41. A weak ammonia-water solution leaves gener-
ator 30 through a conduit 42, passes through a heat exchang-
er 43 and a conduit 44 to absorber 41 where it mixes with
the ammonia returning from evaporator 39. The water-ammonia
mixture from the~absorber is pumped by.a pump 45 through
heat exchanger 43 where it absorbs heat from the weak solu-
tion and is returned to the generator.
A modified form of the invention is show in Figure
'3. The structure is similar to the structure shown in
Figure 1 and like parts are identified by like numbers. A
generator 130 is positioned at a central point within the
containment structure. A hot gas duct 125 is mounted on the
top of the coke oven battery'and has a~plurality of hot gas
intakes 126 mounted above the quenching area. Duct l25
leads to a plenum 150 which is mounted on top of generator
130. A hot gas collector 151 is mounted above quenching
tower 9, and a hot gas duct 152 leads from collector i51 to
plenum 150. .
An air scrubber 122 has an air intake~123 mounted
on top. Scrubbed air is discharged near the bottom of the
scrubber.
A circulating water system is provided to circu-
late hot water in the bottom of the quench tower to a heat
exchanger (not shown) in plenum 150. The circulating system
includes a pump _ which takes hot water from a sump~in,the,
bottom of quenching tower 9, a delivery line 153 leading
from the pump to the heat exchanger, and a return line 154
from the heat exchanger back to the sump.
In operation of the embodiment shown in Figures 1
and 2, coke and coal are delivered to transfer point 11 by
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rail cars 10. The coal is mixed with water to form a slurry
at the transfer point. The slurry is pumped through pipe 12
to dewatering bin 13. The pumping apparatus for the slurry
serves as an air lock and prevents passage of gases from the
interior of dome d to the external atmosphere. Water is
drained from the coal particles in dewatering bin 13 by
screening: The dewatered coal is carried from the bottom of
bin 13 by conveyor 14 and deposited in a storage bin 6. A
drying station may also be included so that the coal is
l0 dried in addition to being dewatered before it is delivered
to storage bin 6. Coal within storage bin 6 is delivered by
larry car 7 to the individual coke ovens at appropriate
times in the coking cycle for each oven.
When the coking process is complete, coke is
pushed from the oven by a pusher of conventional type (not
~sliown) into a quench car 8. The incandescent coke is then
carried to quenching station 9 where it is sprayed with a
controlled amount of water to reduce the temperature below
the combustion temperature.
Fuel gas, such as blast furnace gas or coke oven
gas, is used to fire the coke ovens. The products of com-
bustion travel through conduit 20 and up chimney 21 passing
through dome 1 and exhausting into the atmosphere. The
operation of the coke ovens is conventional and is well .
understood by those knowledgeable of coke oven installa-
tions.
The quenching of the hot coke and leakage from the
coke ovens causes pollutants to be discharged into the space
enclosed by dome 1. The air within dome 1 is continuously
3o circulated through an air.scrubber 22. The air is taken in
at inlet 23 and discharged into the top of the dome through
discharge 24. Pollutants are removed from the circulating.
air in the scrubber and are removed from the dome using a -
hydro-transport aystem which is omitted from the drawings
for clarity of illustration.
If quenching is done with a liquid, a substantial
amount of water vapor will be emitted from the quenching
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tower. As the vapor rises and cools it will condense and
produce "rain" within the dome. To eliminate that effect a
refrigeration evaporator may be fitted to the quenching tower
to cool the exiting gases enough to condense water vapor
S from the atmosphere and convert it to liquid form. The
evaporator may be driven by and form a part of the system .
shown in Figure 2.
The air within the-dome is circulated through a
system comprising a duct~25 and a casing 27. The generator
30 of the absorption refrigeration system is placed within
casing 27-. As air circulates through and past the genera-
tor,' heat is transferred from the air to the generator
causing the air temperature to be lowered and the fluid
within the absorber to be heated. The heated refrigerant is
~L5 then passed through a conduit to the outside of dome 1 where .
it is introduced into a condenser, and heat is extracted
from the refrigerant. Preferably. the heat is collected and
is used for a co-generation process. The heat may, however,
be discharged into the atmosphere outside dome 1. The
cooled refrigerant is then delivered to the. lattice work 3 '
comprising hollow tubes where it is expanded causing a
cooling of the lattice work and removing heat from the air
within dome 1.
Instead.of discharging heat to the atmosphere~from
condenser 29, the waste~heat may be collected and used .as
energy to operate a space heating system or other processes.
The use of~the absorption refrigeration system permits the
structure to be maintained at a safe working temperature
using the available heat from the coking process. Further,
3o the refrigeration cycle acts to remove. heat from the dome
without transfer of any pollutants from inside the dome to
the atmosphere.
In the embodiment of the invention shown in Figure
3, the generator and scrubber are. relocated to take advan-
tage of gaseous circulation within the containment structure
resulting from temperature differentials. Heat is added to
the atmosphere within the~structure by radiation and convec-
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tion from the coke oven battery and from each mass of hot
coke pushed into quench~car 8. Heat from the battery gener-
ally heats the atmosphere in the upper part of dome 1. Heat
released by hot coke pushed into quench car 8 rises as a
current of hot gas 155 and merges with heated but cooler
gases in the upper part of the dome. The wall section 159
on the side of scrubber 122 opposite from the coke battery
is selectively cooled. The rest of the dome is uncooled or
is cooled only enough to avoid heat damage to the dome. The -
localized cooling at wall section 159 causes cooling of the
gas adjacent the wall, which renders the gas more dense arid
causes the gas to settle to the bottom of the enclosed
space. A circulation of gas in the dome is thereby brought
about, the gas stream moving down past wall. section 159,
across the bottom of the enclosed space'as a stream 158
which then rises to the top of the dome on the opposite
side.
The mixture of heated gases in the upper part of
the dome is induced to move in stream 157 toward intake 123
of scrubber 124. Scrubbing is done with wash water which
also cools the gas. The cooled gas travels across the floor
of the structure in a stream 158 which is driven by the
thermal gradient to rise to the upper part. of the dome.
Thus, the addition of heat and extraction of heat tends to
cause a circulation within the dome.
When the quench car With a load~of hot coke enters
quench tower 152, a measured amount of water is sprayed onto
the incandescent coke and is converted to steam. The hot
steam is conducted by collector 151 and duct 152 to plenum
150. Also, hot gas at the top of the ovens is conducted to
plenum 150 by duct 125 from intakes 126. Heat in the hot
~gas~is transferred to the refrigerant, and the hot gas is
thereby cooled. The cooled gas is discharged into the
bottom of the enclosed space to join stream 158.
Hot water from the sump in the-quenching tower may.
be pumped to a heat exchanger at the generator for transfer
of additional heat to the refrigerant. in generator 130.
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Fans may be provided optionally in scrubber 122,
or ducts 125 and 152, or generator 130 to assist in moving
the gases in the pattern described above. .
While I have illustrated and described a present
preferred embodiment of my invention, it is to be understood
that I do not limit myself thereto, and that the invention
may be otherwise variously practiced within the scope of the
following claims.
