CA1068636A - Dust collecting system for coke oven - Google Patents
Dust collecting system for coke ovenInfo
- Publication number
- CA1068636A CA1068636A CA242,708A CA242708A CA1068636A CA 1068636 A CA1068636 A CA 1068636A CA 242708 A CA242708 A CA 242708A CA 1068636 A CA1068636 A CA 1068636A
- Authority
- CA
- Canada
- Prior art keywords
- dust
- coke
- blower
- gases
- coal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B33/00—Discharging devices; Coke guides
- C10B33/003—Arrangements for pollution-free discharge
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B27/00—Arrangements for withdrawal of the distillation gases
- C10B27/04—Arrangements for withdrawal of the distillation gases during the charging operation of the oven
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Public Health (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Coke Industry (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides in the operation of a coke oven including a coke discharge step and a coal charge step at which step a dust containing gas is discharged , a method of collecting dust from said gases which comprises passing said gases to a common bag filter dust collector, the gases from said coke discharge step being first passed to said collec-tor to deposit a fine layer of coke particles on the filter and then alternately repeating collection of dust containing gases from said steps into said filter whereby tar mists contained in said gas from said coal charge step are deposited in the layer of fine coke particles.
The present invention also provides dust in the coal charging step is burnt in a combustion chamber disposed on a charging car and then is preliminarily filtered by a wet type pre-dust collector.
The present invention provides in the operation of a coke oven including a coke discharge step and a coal charge step at which step a dust containing gas is discharged , a method of collecting dust from said gases which comprises passing said gases to a common bag filter dust collector, the gases from said coke discharge step being first passed to said collec-tor to deposit a fine layer of coke particles on the filter and then alternately repeating collection of dust containing gases from said steps into said filter whereby tar mists contained in said gas from said coal charge step are deposited in the layer of fine coke particles.
The present invention also provides dust in the coal charging step is burnt in a combustion chamber disposed on a charging car and then is preliminarily filtered by a wet type pre-dust collector.
Description
:.. --, . ..
-~ The present invention relates to an improved dust collecting system for a coke oven and in particular to an improved method and apparatus for collecting dust from gases discharged during the operation of a coke oven.
In the operation of a coke oven, severe dust generation caused on discharging coke from the coke oven (hereinafter refer-red to as a coke discharge step) and on charging coal to the coke oven for carbonization thereof (hereinafter referred to as a coal charge step). In order to collect gases and dust from the quenching car and the coke guide car in the coke discharge step a system has been proposed of sucking the dust and gases through a fixed duct to a dust collector (settling chamber) on the ground, including covering the coke guide car with a hood.
This system is effective and generally satisfactory. However, gas from the carbonizing chamber in the coal charge step contains dust and large amounts of combustible gases and tar mists. Accordingly, though various dust collecting sys~ems ~` ~ have been proposed, a desirable system from the viewpoint of ~- stability, economy and efficiency of dust collection has not been achieved. For example, a dust collecting system has been proposed wherein a combustion chamber and a gas suction device are provided on the charging car to provide suction and combustion ;~ of the ~as from the oven chamber and to feed the exhaust gas ` from the combustion chamber through a fixed duct to a dust `i collector, on the ground. A system has also been proposed having the combustion chamber in the above system on the ground. -The dust containing gases from the coal charge step are of low calorific value and of large volume. To achieve ``~ complete combustion, it is necessary to increase the temperature in the combustion chamber to be higher than 700C. Accordingly -~ a large amount of auxiliary fuel is required in the combustion chamber which is uneconomical. In the conventional combustion .'. ~' ' ~ ' `,` - 1- ~ ` : `
` ~0~636 . ': . , system, only the ignition source is fed in the combustion chamber and combustion of only self-combustible components in the dust containing gases is obtained. Accordingly, the exhaust gas which contains unreacted gases and tar mists, is fed into the dust collector on the ground. It has also been proposed to use a system having no combustion chamber wherein the dust con-taining gases are sucked from the charging car through a fixed duct to a dust collector on the ground. In this system, a large amount of combustible gases and tar mists are directly fed into -- 10 the dust collector.
Heretofore, a mechanical wet type dust collector has been used as the dust collector in the coal charge step because the dust contains combustible gases and tar mists. It has been difficult to use an electrostatic precipitator because it is expensive and dangerous to operate as it contains combustible gases. However, the efficiency of the collection of dusts having ` less than 1 ~ of particle diamter and tar mists is quite low in `~ the wet type dust collector, and the dusts and tar mists pass through the dust collector and are discharged into atmosphere as floating dusts whereby pollution of environment is caused over ;~
a broad area.
The present invention provides a dust collection sys-tem for a coke oven which has a satisfactory dust collecting effect by employing a bag filter dust collector having high efficiency as a common dust collector for both of the coke : discharge step and the coal charge step as both steps are usually operated at different time and are rarely operated simultaneously.
According to the present invention there is provided a dust collecting system for a coke oven which comprises a bag filter dust collector arranged to act as a common dust collector ~` in both of the coke discharge step and the coal charge step, dust collection in the coke discharge step being firstly effected and '.'; :
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then alternately repeating the dust collecting operations in the coal charge step and the coke discharge step, whereby adhesion of tar mists to the bag filter surface is avoided.
According to one aspect of the present invention therefore there is provided in the operation of a coke oven including a coke discharge step and a coal charge step in each of which steps a dust containing gas is discharged, a method of collecting dust from each of the gases which comprises passing said gases to a common bag filter dust collector, the gas from said coke discharge step being first passed to said collector to deposit a fine layer of coke particles on the filter and then alternately repeating collection of dust containing gases from said steps ~nto said filter whereby tar mists contained in said gas from said coal charge step are deposited in the layer of ;~
fine coke particles.
According to another aspect of the present invention the dust in the coal charging step is burnt in a combustion chamber disposed on a charging car and then is preliminarily . . .
filtered by a wet type pre-dust collector.
In general, it has been considered difficult to use a bag filter system for the dust collection of a dust containing `
"~ gas which contains adhesive and tacky particles such as tar ~ mists. In a practical test of a coke oven, when only gas from ;- the coal charge step is collected by a bag filter, the filter is rendered inoperative after several days due to blocking.
~ In accordance with the system of the present invention, : a common bag filter dust collector is used for dust collection -~
in both the coke discharge step and the coal charge step, the ;J
dust collection in the coke discharge step being firstly conducted and then the dust collection at both steps are alter- ~
nately conducted to prevent direct deposition of tar mists on `
the surface of the filter on the collector. Stable operation ' ' ':
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can be continued without shutting down the filter and the discharge of fine dusts and tar mists is avoided thus preventing pollution of the atmosphexe.
; In the operation of the coke oven, the coke discharge step and the coal charge step are alternately conducted. Accord-ingly, when the dust in the coke discharge step is sucked into the bag filter dust collector, it is deposited on the surface o~
the filter without tackiness and the dust is easily shaken down ; because most of the dust in the coke discharge operation is in -the form of fine coke particles. When the dust containing gas ~ ;
which contains tar mists in the coal charge step is sucked into the bag filter, the tar mists are collected by deposition on the fine coke particles covering the surface of the filter which have been deposited in the coke discharge step. Accordingly, the tar mists do not adhere to the surface of the filter and can be easily shaken down from the filter with the deposited fine coke particles. In particular, the dust containing tar mists formed in the coal feed operation are deposited as layers between ~ ,.
fine coke particle layers formed in the coke discharge step as a sandwich because the coke discharge step and the coal charge step are alternately conducted. Accordingly, the tar mists are not . ~ - . .
directly deposited on the surface of the filter and blocking of the filter does not occur.
` The present invention will be further illustrated by way of the accompanying drawings in which, Figure 1 is a schematic sectional front view of a coke .;. ................................................................... .
oven and a dust collector in accordance with one embodiment of -~- the present invention;
Figure 2 is a schematic plan view of Figure l;
Figure 3(a) is a partial sectional front view of an inner part of the bag filter dust collector of Fig. l;
Figure 3(b) is a partial enlarged sectional view showing ~06~36~6 the deposition of dusts on the filter of Fig. 3(a);
Figure 3(c) is a partial enlarged sectional view show-ing the condition after shaking down the dusts in the filter of Fig. 3(a);
Figure 4, whi~h is on the same sheet as Fig. 1, is a diagram for illustrating the operation in a co]ce oven;
Figure 5, which is on the same sheet as Fig. 1, is a block diagram of a dust collecting system for coke oven accord-ing to a further embodiment of the present invention.
In a particular embodiment of the present invention in dust collecting system, the dust collection in the coke discharge step ~or the coke guide truck and the dust collection in the coal charge step are conducted by the control of a single common blower using one dust collector. As it is well-known, a coke oven has many oven chambers. Coke oven operation has been conducted by feeding coal to each of the oven chambers and `
;. ., discharging the resulting coke after carbonization after ten or more hours. In an empty oven chamber, coal is fed after the coke discharging step. The operations in many oven chambers 20 arranged in parallel are sequentially conducted as continuous operations. It takes about 450 seconds (7.5 minutes) for the operation in one oven chamber including the coke discharge step, -`~- the coal charge step and other steps. The period of 450 seconds ~
as shown in Figure 4 includes 90 seconds for the coke discharge ;
; step, 210 seconds for the coal charge step and 150 seconds for ~ -~; other steps. A large amount of dust is spouted out in both of the coke discharge step and the coal charge step. Accordingly, ~;
it is necessary to conduct a dust collection in both of said ;
steps.
It has been proposed to provide a dust collecting system wherein a duct on the ground is connected with the coke oven, a dust collector is connected to the duct, and a hood " ' ' 363i for collecting the dust containing gas spouted out at the coke ;
discharge step is provided on a guide car so as to feed the gas to the duct,in order to collect the dust. It has also been proposed to provide a dust collecting system which has a duct on the ground as similar to the former dust collecting system, for example, a scrubber in the case of dust caused by charging coal.
In said conventional systems, each separate dust collecting duct and each dust collector are employed for each step, and each blower is continuously driven at a constant speed. Each blower :: .
as will be seen from Figure 4 is driven at each constant speed ` although the coke discharge step and the coal charge step are not : conducted simultaneously. Accordingly, the operational cost ~; 1 (electric power costs? is high. Each damper, each blower and each dust collector are provided on the side of the charging car and ; ~ also on the side of the coke guide car. Accordingly, the cost for such apparatus is guite expensive and has economic disadvanta-ges. In accordance with the present invention to overcome the - disadvantages, thereis provided a dust collecting system in a , 1.
:. coke oven which comprises a dust collecting duct for the guide car and a dust collecting duct for one charging car, which are connected through one common blower to one dust collector, and ~: the speed of the blower is controlled so as to operate depending ~,- upon the blow rates of dust containing gases at the coke discharge step and the coal charge step, whereby the cost of the apparatus `~ and the operational cost are highly reduced. Since the coke ~` discharge step and the coal charge step are serially conducted, -it is unnecessary to provide two dust collectors on the side of the charging car side and the side of the guide truck.
~` The blow rate of the dust containing gas sucked in the .',,. , I'' dust collecting operation in a coke oven will be illustrated before the illustration of detail of the embodiment~ In coke ` oven operation, the coke discharge step and the coaL charge step ;
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are conducted in series, as stated above. Accordingly if it is possible to control the blow rates of the dust containing gases, ~ one common dus-t collector can be employed depending upon each of ; th~ operations. When the blow rate of the dust containing gas pass~d through the guide car at the coke discharge step is given as Q, the blow rate of the dust containing gas passed through the charging car is usually enough to suck the gas at a blow rate of Q/2 or less (hereinafter, considered to be Q/2) and more than the surging limit (ex. Q/4). In order to control the blow rates ` 10 of the dust containing gases, it is possible to employ a coke damper control system. However, in the embodiment, the blow rates of the dust containing gases are controlled by charg~
the speed of a blower and controlling ~ edamper to prevent ` surging.
In Table 1, the electric power required and conditions ~ of coke oven operation in the coke damper control system and the ;, speed control system of the embodiment are shown. ~ -~l . Table 1 . ~ ~ ~,:
Coke oven 5 30 120 330 450 operation 30 ¦ 90s~ 210S s .
other coke coal other ~-` step discharge chaxge step - __ _ ~ _ step _ step_ l -Rate of gas Q/2 Q/2 Q/2 sucked (Nm3/min) ~ ;
. .... .. __ . .. ._ _ . . _ ., Coke damper control ` system speed of blower N cons-(r.p.m.) tant rotation ~ -power of about P about about blower (XW) 2/3 P 2/3 P 2/3 P
~: _ .... _ _ ,,,, ._ '~ ' Speed control system Speed of blower N/2 N N/2 N/2 (r.p.m.) l power of blower (KW) P/8 P P/8 P/8 - ------ , __ ..... ___ .... .. ~ _ : .
: - 7 -~ 363~
:
..... .
The data of Table 1 is given by the following equations.
When the speed of blower is changed, the following relations are given.
., Q' = Q . N' _ .................. (1) N
~" T ( -N~ (2) P ~ P o ( N ~ .................. (3) wherein Q : rated blow rate;
Q': blow rate at rotating speed of N';
:
~, PT: rated gas pressure;
PT': gas pressure at rotating speed of N';
P : rated electric power;
P': electric power at speed of N';
~`~ N : rated speed.
... . .
: The electric power at the blow rate of Q/2 in the coke damper control system is about 2/3 P because of characteristics .;,., - , 1 ' of a blower.
Referring to Figures 1 and 2, the apparatus comprises -~ a coke oven 1, a pusher 2, a charging car 3, a coke guide car 4, ;~
`~ 20 , a quenchlng car 5 and a bag filter dust collector 6. A combus-` tion chamber 7 and a section blower 8 with a pre-dust collector are disposed on the charging car (3) which has a duct 9. The coke guide car (4) has a hood (10) and a duct (11). The pre-dust . ,: ., collector in the suction blower (8) is a wet type dust collector ~` and the dust from the combustion chamber (7) is collected and the ~`` temperature of the gas is decreased. The ducts (9) and (11) are `' commonly connected through a blower (12) to the dust collector ~ -(6) both of which are disposed on the ground. Dampers (13) and (14) are provided in the ducts (9) and (11) particularly to pre- ¦~
vent surging.
In the operation of the coke oven, gases and dust , , spout out when the coke falls down through the coke guide car '~
~ .
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.':' . : . . ' : . ~
636~
(4) on the quenching car (5) in the coke discharge step. When the hood (lO) of the ~uide car (4) is connected to the duct (11) the gases and dust are collected in the hood (10) on the coke guide car (4) by the operatlon of the blower (12) disposed on the ground, and they are sucked into the duct (11) and the dust con-taining gas is cleaned by the dust collector (6) from whence it is discharged into the atmosphere. In the following coal charge step, the dust containing gas spouted out, is sucked by the opera-, tion of the suction blower mounted on the charging car (3) and the combustible components in the gas are burnt in the combustionchamber (7). The combustion chamber (7) has a limited space on the charging car (3), whereby the capacity of the combustion cham- l~
ber (7) is insufficient to accomplish complete combustion of the ' -combustible components. Accordingly, the exhaust gas from the ;
chamber (7) contains relatively large amounts of tar mists, coal dust and coke dust. When the delivery of the pre-dust collector l of the charging car is connected to the duct (9), the dust con- ~ `
taining gas after the combustion of the combustible components, is fed from the chamber (7) into the duct (9) and the gas is sucked into the blower (12) in a similar manner as that of the coke discharge step. The dust containing gas is cleaned by the ; dust collector (6) and is discharged to the atmosphere. The suction rate in the coal charge step is usually about 1/2 or less ! of the suction rate at the coke discharge step. The suction rate is controlled at the coal charge step. The suction rate is suitably controlled by preventing the surging of the blower (12 ` by openingthe damper (14) orcontrolling thespeed ofthe blower (12).
In the bag filter dust collector (6) a plurality of tubular filters (17) are suspended by means of springs (16) in ` a casing (15) (Figure 3(a)). The exhaust gas passes from the inner part of the tubular filter (17) upwardly through the parti-tion (18a) in the casing (15) via holes (18c) to discharge into : .~ , , . ' _ g_ . . . . _ .. ~ ., . , ~
- ~( 1686~6 the atmosphere. A co~bined duct (19) from the blower (12) for the dust containing gases enters below a lower partition (18b).
Thus in the dust collector (6) a preliminary dust deposited layer (20) is maintained on the inner surface of the tubular filter (17) and it is not easily shaken down (see Figure 3(c)). As shown in Figure 3(b), a layer of dust (21) at the coke discharge step is collected on the surface of the preliminary deposited layer (20). The dust and tar mists in the following coal charge step are collected on the surface of the layer of dust (21). When a compressed air is fed from above of the upper partition (18a) so as to in~ect the compressed air inwardly from ~he outer surface of the tubular filter (17), `
so as to shake down the deposited dusts, the dust layer (21) collected in the step of discharging the coke and the dust and tar mists layer (22) collected in the coal charge step are shaken down from the inner surface of the tubular filter (17) as shown in Figure 3(c). Accordingly, the dust containing tar mists do ~" .
not contact the tubular filters (17) per se.
Under optimum conditions of operation, the suction rate in the dust collection at the coal charge step is reduced to half by controlling a speed of the blower (12) and the speed of filter-~` ing the gas in the bag filter dust collector (6) is reduced, whereby the increase of pressure loss on the filter (6) is re-duced and the shaking-down rate is reduced and the life ~f the tubular filters (17) is prolonged.
As stated above, in accordance with the system of the ¦
invention, only one dust collector is commonly employed in both ¦~
-` of the coke discharge step and the coal charge step~ Moreover, a bag filter dust collector which has high efficiency of dust ~`30 collection can be employed for collecting dusts containing tar mists, andthedustcontaining gascanbecleaned to a high extent.
Accordingly, air pollution problems are not caused by discharging , -10-. ' ' - - .
:: . .. . -~L~)68~36 : .
the exhaust gas after the dust collection to the atmosphere.
The dust collector of the invention is not limited to a common dust collector for the coke guide truck and the coal feed truck. It is possible to employ a combination of a dust collector in the pusher side and the dust collector for : coal feed truck; or a combination of said three dust collectors.
i Referring to Figure 5, a further embodiment of the invention , is illustrated. In Figure 5 a dust collecting duct (32) for a charging car (31) is connected through a duct connector (42) to the charging car (31). A dust collecting duct (34) for coke discharge is connected through a duct connector (41) to the coke guide car (33). The dust collecting duct (32) for charging . car (31) is connected to the dust collecting duct (34) for , coke discharge at both ends to form a loop. The ends of the ` dust collecting ducts (32) and (34) are connected through a ; ~ suction duct (36) to the blower (35). The blower (35) is connec-. ~., ~ .
ted in series to the dust collector (37) and the stack (38).
An automatic damper (39) is disposed at a suction side of the blower t35) which prevents the blower (35) surging during the time that neither the dust collection forcharging car (31) nor the dust collection for thecoke discharge step is conducted.
The blower (35) is driven by a motor (40) whose speed is controll-able so as to suck the dust containing gas at a blow rate of Q/2 of air. In Figure 5, the blow rate of the dust containing gas sucked from the coke guide car (33) is given as Q; the blow rate of the dust containing gas sucked from the charging car (31) is given as Q/2; the blow rate of air sucked from the automatic damper (39) is given as Q/2. The efficiency of the : .:. .j ~` blower (35) is to suck the blow rate of gas Q. The conditions ` 30 of the operation of the coke oven dust collecting system in .... . .
the one step of the coke oven operation, are as follows in the ~` embodiment of Figure 5.
;: .. : ..
-- 11 -- .. , '' ~ .. ...
: ~j ,. . .. , .. .. . . . , . , .. ; , .... , . ,:
`~
~ ~0~8636 :, .. In the normal condition that neither of the dust collection for the coke discharge step nor the dust collection ~, ...
for the coal charge step is conducted, the dust collecting connectors (41) and (42) for the guide car (33) and the charging .. car (31) are not connected to the dust collecting ducts (34) and ;'; ~32) respectively by opening the automatic damper (39). According- .
ly, a blow rate of gas sucked by the blower (35) from the dust ;. collecting ducts (32) and (34) is zero. Air is only sucked from the automatic damper (39). The speed of the blower (35) is N/2 and the electric power is P/8. When the dust collecting connector :
.` (41) is connected to the dust collecting duct (34) for thecoke ~;. discharge step, the automatic damper (39) is switched from the :
. open state to the closed state by the signal for coke discharge -:~ given from a pusher (not shown), and the speed of the blower is ; , , raised from N/2 to N. At the time, the blow rate of the dust containing gas sucked by the blower from the coke guide car (33) ~ . . , is Q. The electric power is P. As shown in Figure 4, when the coke discharge is finished after about 90 seconds, the dust : . . . .
- : collecting connector (41) is separated from the dust collecting . 20 duct (34) so as to be able to conduct the operation of dust : .
collection for the coal charge step. In the dust collection for ` the coal charge step, the dust collecting connector (42) is .
: connected to the dust collecting duct (32). The speed of the ~-~-. blower (35) is reduced from N to N/2 by the signal for the coal .~: charge step given from the charging car (31). At the time, the automatic damper maintains the closed state. The dust containing ~`. gas is sucked by the blower (35) from the charging car (31) at a ~` blow rate of Q/2. The electric power is P/8. In the coal charge .
i; B step as shown in Figure 4, the coal charge is finished~r 210 seconds. When the coal charge operation is finished, the dust ~.
~" collecting connector (42) is separated from the dust collecting ~`~ duct (32). The signal of the charging car (31) is turned off to ..
:, , , ~ , , , , ' :
:, .. :: , -~ ~L~8~3~;
switch the automa-tic damper (39) from the closed state to the open state. Thus, the first dust collecting step in the first coke oven is completed and the dust collecting step in the next coke oven is conducted. The operation is sequentially repeated.
In the coke damper control system for controlling a blow rate of gas with a fixed damper disposed in a dust collecting cluct (32) for the coal charge step without changing the speed of the blower (35), even though the blow rate of ~as is reduced to Q/2, the electric power reduces to only about 2/3 P because of blower characteristics. However, in the blower speed control system, the electric power reduces to 1/8 P in such a case. ~-Moreover, it only takes 90 seconds to suck the gas at the maximum blow rate of Q in the coke discharge step as compared 450 seconds of total operation time for thecoke discharge step and the coal charge step in the coke oven. Accordingly, it takes 360 seconds . , to suck the gas at the blow rate of Q/2 in the coal charge step and other steps, whereby the effect of reduced power consumption is remarkable. In the embodiment, there is no description of the speed control system for driving the blower (35). Thus, it is considered from the viewpoint of severe operation in which `~
many switchings between acceleration and reduction are given ~`
-~ in the dust collector of the coke oven, it is preferable to . :::- ::
employ a static control apparatus which can set a desirable `- speed corresponding to a blow rate of gas sucked-and which has : - regenerative braking system at the reduction of the speed whereby i.. , ~- : - .
the effect of power reduction isimproved and the other operational effects can be attained.
., " -~ , . . .
It is preferable to employ a dust collector in which a blow rate of the dust containing gas is low under satisfactory `' 30 characteristics of the speed control in order to employ an ~ electrical dust collector or a bag filter which has high effic-~` ' .
~ iency for dust collection. Fromthe viewpoint o~ pressure loss, .~. . .
. ~, . .
, - ` :
; it can be applicable under pressure reduction in the speed reduc- `
tion o~ the blower. It is also possible to use another type dust collector which has similar characteristics.
In said embodiment, one dust collector is commonly employed for dust collection at the coke discharge step and for dust collection in the coal charge step for carbonization, and the speed of the blower is controlled. Thus, it is possible to expect same effect of speed control in the blower of the specific dust collector ~or discharging coke from the coke oven. As stated above, in accordance with the system of the invention, the dust collecting duct for coal charge and the dust collecting duct for coke discharge are connected through one common blower to one dust collector and the speed of the blower is controlled so as to operate to give desirable blow rates for each of the gases in the coke discharge step and the coal charge step.
Accordingly, both of the dust collection for the coke discharge ` step and the dust collection for the coal charge step can be ; attained by using one dust collector. Accordingly, the apparatus ~ -can be simplified and the cost for the apparatus can be highly reduced. The speed of the blower is controlled depending upon the ~ ;
, dust collection for the coke discharge step and the dust collection - for the coal charge step, whereby the cost of operation can be greatly reduced to give economical advantages. The blower is op-erated at a rated speed only during the short time of the discharg-ing step in one cycle coke oven operation, and the blower is oper- :
ated at a reduced speed during the other steps. Accordingly, the I
`' ~ -noise of the blower can be reduced. The size of the blower can ` be smaller by the combination of the speed control of the blower and the control of damper for preventing surging, and it is possible to operate the blower safely without surging. The dust in the duct for the charging car can be passed through the pre-dust collector before feeding in the bag filter dust ., ~.-.~ ', , .
~' - ' ' . .
.
:., . : .
collector whereby contents of the tar mist and the combustible gas can be remarkably reduced, and accidents such as combustion . ~ . . .
and explosion in the bag filter dust collector can be prevented without failure and the load of the bag filter dust collector can be remarkably reduced.
; The system for controlling the blower and the automatic damper is hereinafter illustrated in detail. A thyristor control circuit is connected to the blower (35) so as to select two steps of the blower speed of a rated blow rate operation and 1/2 blow ; 10 rate operation. The rated blow rate operation (N) is selected ~-~
when the blower receives both a signal for discharge duct connection from a coke guide car and a signal for discharge from the pusher. The 1/2 rated blow rate operation (N/2) is selected during the other time.
The automatic damper (39) has selective ON-OFF control circuit for closed and open states. The closed state of the ~ damper is selected when either of a signal for discharge from `- the pusher or a signal for charge from the chargingcar is received.
The open state of the damper is selected during the other period.
~` 20 The dust collecting duct (32) has each connecting port with a : . . . .
door corresponding to each coke oven chamber. The door is usually kept in closed state. However it is opened for connecting the .. ;.. , . ~..... .
delivery of the pre-dust collector disposed on the charging car, whereby the delivery is connected to the duct (32). The dust ' !: ' ~- collecting duct (34) has each connecting port with a door corres-ponding to each coke oven chamber. The door is usually kept in closed state, however it is opened for connecting to the hood j`` of the coke guide car, whereby the hood is connected to the duct (34). When neither the charge operation nor discharge operation is conducted, the doors for the connecting ports of the dust collecting ducts (32) and (34) are closed. Accordingly the ~` blower keeps the 1/2 rated blow rate operation (N/23 and the ~: :
. ~,~ ..
``` ' . , :
;36 ; ~ automatic damper ls kept in an open s-tate. ~ the discharge ; step, the dust collecting dust ~34) is connected to the hood of the guide car. The signal for discharge duct connection is generated, the automatic damper (39) is kept in open state and only gas in the hood of the guide car is sucked by the blower.
When the discharge of coke is initiated and the signal for dis-charge is generated from the pusher, the blower receives both the signal for discharge duct connection and the signal for discharge and the blow rate is switched to the rated blow rate operation at high speed. When the discharge of coke is finished by disconnection ~ ee~ the dust collecting duct (34) and the hood of guide car to stop the signal for discharge duct connection, the automatic damper (39) is switched to the open state and only gas from the damper is sucked by the blower. ~ the charge step, the delivery of the pre-dust collector of the charging car is connected to the dust collecting duct (32), and the signal for charge is generated whereby the automatic damper is switched to closed state. However, the blower, continues the l/2 rated blow ; rate operation whereby only gas from the delivery of the pre-dust .
collector of the charging car is sucked. When the charge of coal ` is finished and the signal for charge to stop the signal for ~. ~
charge, the automatic damper is switched to the open state, .
" whereby only gas from the damper is sucked by the blower and the :
blower continues the 1/2 rated blow rate operation. ~ ~
:
`' ' .
'`' ' '' .
,
-~ The present invention relates to an improved dust collecting system for a coke oven and in particular to an improved method and apparatus for collecting dust from gases discharged during the operation of a coke oven.
In the operation of a coke oven, severe dust generation caused on discharging coke from the coke oven (hereinafter refer-red to as a coke discharge step) and on charging coal to the coke oven for carbonization thereof (hereinafter referred to as a coal charge step). In order to collect gases and dust from the quenching car and the coke guide car in the coke discharge step a system has been proposed of sucking the dust and gases through a fixed duct to a dust collector (settling chamber) on the ground, including covering the coke guide car with a hood.
This system is effective and generally satisfactory. However, gas from the carbonizing chamber in the coal charge step contains dust and large amounts of combustible gases and tar mists. Accordingly, though various dust collecting sys~ems ~` ~ have been proposed, a desirable system from the viewpoint of ~- stability, economy and efficiency of dust collection has not been achieved. For example, a dust collecting system has been proposed wherein a combustion chamber and a gas suction device are provided on the charging car to provide suction and combustion ;~ of the ~as from the oven chamber and to feed the exhaust gas ` from the combustion chamber through a fixed duct to a dust `i collector, on the ground. A system has also been proposed having the combustion chamber in the above system on the ground. -The dust containing gases from the coal charge step are of low calorific value and of large volume. To achieve ``~ complete combustion, it is necessary to increase the temperature in the combustion chamber to be higher than 700C. Accordingly -~ a large amount of auxiliary fuel is required in the combustion chamber which is uneconomical. In the conventional combustion .'. ~' ' ~ ' `,` - 1- ~ ` : `
` ~0~636 . ': . , system, only the ignition source is fed in the combustion chamber and combustion of only self-combustible components in the dust containing gases is obtained. Accordingly, the exhaust gas which contains unreacted gases and tar mists, is fed into the dust collector on the ground. It has also been proposed to use a system having no combustion chamber wherein the dust con-taining gases are sucked from the charging car through a fixed duct to a dust collector on the ground. In this system, a large amount of combustible gases and tar mists are directly fed into -- 10 the dust collector.
Heretofore, a mechanical wet type dust collector has been used as the dust collector in the coal charge step because the dust contains combustible gases and tar mists. It has been difficult to use an electrostatic precipitator because it is expensive and dangerous to operate as it contains combustible gases. However, the efficiency of the collection of dusts having ` less than 1 ~ of particle diamter and tar mists is quite low in `~ the wet type dust collector, and the dusts and tar mists pass through the dust collector and are discharged into atmosphere as floating dusts whereby pollution of environment is caused over ;~
a broad area.
The present invention provides a dust collection sys-tem for a coke oven which has a satisfactory dust collecting effect by employing a bag filter dust collector having high efficiency as a common dust collector for both of the coke : discharge step and the coal charge step as both steps are usually operated at different time and are rarely operated simultaneously.
According to the present invention there is provided a dust collecting system for a coke oven which comprises a bag filter dust collector arranged to act as a common dust collector ~` in both of the coke discharge step and the coal charge step, dust collection in the coke discharge step being firstly effected and '.'; :
:
~)613~;36 '''" `
then alternately repeating the dust collecting operations in the coal charge step and the coke discharge step, whereby adhesion of tar mists to the bag filter surface is avoided.
According to one aspect of the present invention therefore there is provided in the operation of a coke oven including a coke discharge step and a coal charge step in each of which steps a dust containing gas is discharged, a method of collecting dust from each of the gases which comprises passing said gases to a common bag filter dust collector, the gas from said coke discharge step being first passed to said collector to deposit a fine layer of coke particles on the filter and then alternately repeating collection of dust containing gases from said steps ~nto said filter whereby tar mists contained in said gas from said coal charge step are deposited in the layer of ;~
fine coke particles.
According to another aspect of the present invention the dust in the coal charging step is burnt in a combustion chamber disposed on a charging car and then is preliminarily . . .
filtered by a wet type pre-dust collector.
In general, it has been considered difficult to use a bag filter system for the dust collection of a dust containing `
"~ gas which contains adhesive and tacky particles such as tar ~ mists. In a practical test of a coke oven, when only gas from ;- the coal charge step is collected by a bag filter, the filter is rendered inoperative after several days due to blocking.
~ In accordance with the system of the present invention, : a common bag filter dust collector is used for dust collection -~
in both the coke discharge step and the coal charge step, the ;J
dust collection in the coke discharge step being firstly conducted and then the dust collection at both steps are alter- ~
nately conducted to prevent direct deposition of tar mists on `
the surface of the filter on the collector. Stable operation ' ' ':
,::: , . :, . , , . ., , , , .~
~06Z~
`
can be continued without shutting down the filter and the discharge of fine dusts and tar mists is avoided thus preventing pollution of the atmosphexe.
; In the operation of the coke oven, the coke discharge step and the coal charge step are alternately conducted. Accord-ingly, when the dust in the coke discharge step is sucked into the bag filter dust collector, it is deposited on the surface o~
the filter without tackiness and the dust is easily shaken down ; because most of the dust in the coke discharge operation is in -the form of fine coke particles. When the dust containing gas ~ ;
which contains tar mists in the coal charge step is sucked into the bag filter, the tar mists are collected by deposition on the fine coke particles covering the surface of the filter which have been deposited in the coke discharge step. Accordingly, the tar mists do not adhere to the surface of the filter and can be easily shaken down from the filter with the deposited fine coke particles. In particular, the dust containing tar mists formed in the coal feed operation are deposited as layers between ~ ,.
fine coke particle layers formed in the coke discharge step as a sandwich because the coke discharge step and the coal charge step are alternately conducted. Accordingly, the tar mists are not . ~ - . .
directly deposited on the surface of the filter and blocking of the filter does not occur.
` The present invention will be further illustrated by way of the accompanying drawings in which, Figure 1 is a schematic sectional front view of a coke .;. ................................................................... .
oven and a dust collector in accordance with one embodiment of -~- the present invention;
Figure 2 is a schematic plan view of Figure l;
Figure 3(a) is a partial sectional front view of an inner part of the bag filter dust collector of Fig. l;
Figure 3(b) is a partial enlarged sectional view showing ~06~36~6 the deposition of dusts on the filter of Fig. 3(a);
Figure 3(c) is a partial enlarged sectional view show-ing the condition after shaking down the dusts in the filter of Fig. 3(a);
Figure 4, whi~h is on the same sheet as Fig. 1, is a diagram for illustrating the operation in a co]ce oven;
Figure 5, which is on the same sheet as Fig. 1, is a block diagram of a dust collecting system for coke oven accord-ing to a further embodiment of the present invention.
In a particular embodiment of the present invention in dust collecting system, the dust collection in the coke discharge step ~or the coke guide truck and the dust collection in the coal charge step are conducted by the control of a single common blower using one dust collector. As it is well-known, a coke oven has many oven chambers. Coke oven operation has been conducted by feeding coal to each of the oven chambers and `
;. ., discharging the resulting coke after carbonization after ten or more hours. In an empty oven chamber, coal is fed after the coke discharging step. The operations in many oven chambers 20 arranged in parallel are sequentially conducted as continuous operations. It takes about 450 seconds (7.5 minutes) for the operation in one oven chamber including the coke discharge step, -`~- the coal charge step and other steps. The period of 450 seconds ~
as shown in Figure 4 includes 90 seconds for the coke discharge ;
; step, 210 seconds for the coal charge step and 150 seconds for ~ -~; other steps. A large amount of dust is spouted out in both of the coke discharge step and the coal charge step. Accordingly, ~;
it is necessary to conduct a dust collection in both of said ;
steps.
It has been proposed to provide a dust collecting system wherein a duct on the ground is connected with the coke oven, a dust collector is connected to the duct, and a hood " ' ' 363i for collecting the dust containing gas spouted out at the coke ;
discharge step is provided on a guide car so as to feed the gas to the duct,in order to collect the dust. It has also been proposed to provide a dust collecting system which has a duct on the ground as similar to the former dust collecting system, for example, a scrubber in the case of dust caused by charging coal.
In said conventional systems, each separate dust collecting duct and each dust collector are employed for each step, and each blower is continuously driven at a constant speed. Each blower :: .
as will be seen from Figure 4 is driven at each constant speed ` although the coke discharge step and the coal charge step are not : conducted simultaneously. Accordingly, the operational cost ~; 1 (electric power costs? is high. Each damper, each blower and each dust collector are provided on the side of the charging car and ; ~ also on the side of the coke guide car. Accordingly, the cost for such apparatus is guite expensive and has economic disadvanta-ges. In accordance with the present invention to overcome the - disadvantages, thereis provided a dust collecting system in a , 1.
:. coke oven which comprises a dust collecting duct for the guide car and a dust collecting duct for one charging car, which are connected through one common blower to one dust collector, and ~: the speed of the blower is controlled so as to operate depending ~,- upon the blow rates of dust containing gases at the coke discharge step and the coal charge step, whereby the cost of the apparatus `~ and the operational cost are highly reduced. Since the coke ~` discharge step and the coal charge step are serially conducted, -it is unnecessary to provide two dust collectors on the side of the charging car side and the side of the guide truck.
~` The blow rate of the dust containing gas sucked in the .',,. , I'' dust collecting operation in a coke oven will be illustrated before the illustration of detail of the embodiment~ In coke ` oven operation, the coke discharge step and the coaL charge step ;
: :
~\
~06~6;~
are conducted in series, as stated above. Accordingly if it is possible to control the blow rates of the dust containing gases, ~ one common dus-t collector can be employed depending upon each of ; th~ operations. When the blow rate of the dust containing gas pass~d through the guide car at the coke discharge step is given as Q, the blow rate of the dust containing gas passed through the charging car is usually enough to suck the gas at a blow rate of Q/2 or less (hereinafter, considered to be Q/2) and more than the surging limit (ex. Q/4). In order to control the blow rates ` 10 of the dust containing gases, it is possible to employ a coke damper control system. However, in the embodiment, the blow rates of the dust containing gases are controlled by charg~
the speed of a blower and controlling ~ edamper to prevent ` surging.
In Table 1, the electric power required and conditions ~ of coke oven operation in the coke damper control system and the ;, speed control system of the embodiment are shown. ~ -~l . Table 1 . ~ ~ ~,:
Coke oven 5 30 120 330 450 operation 30 ¦ 90s~ 210S s .
other coke coal other ~-` step discharge chaxge step - __ _ ~ _ step _ step_ l -Rate of gas Q/2 Q/2 Q/2 sucked (Nm3/min) ~ ;
. .... .. __ . .. ._ _ . . _ ., Coke damper control ` system speed of blower N cons-(r.p.m.) tant rotation ~ -power of about P about about blower (XW) 2/3 P 2/3 P 2/3 P
~: _ .... _ _ ,,,, ._ '~ ' Speed control system Speed of blower N/2 N N/2 N/2 (r.p.m.) l power of blower (KW) P/8 P P/8 P/8 - ------ , __ ..... ___ .... .. ~ _ : .
: - 7 -~ 363~
:
..... .
The data of Table 1 is given by the following equations.
When the speed of blower is changed, the following relations are given.
., Q' = Q . N' _ .................. (1) N
~" T ( -N~ (2) P ~ P o ( N ~ .................. (3) wherein Q : rated blow rate;
Q': blow rate at rotating speed of N';
:
~, PT: rated gas pressure;
PT': gas pressure at rotating speed of N';
P : rated electric power;
P': electric power at speed of N';
~`~ N : rated speed.
... . .
: The electric power at the blow rate of Q/2 in the coke damper control system is about 2/3 P because of characteristics .;,., - , 1 ' of a blower.
Referring to Figures 1 and 2, the apparatus comprises -~ a coke oven 1, a pusher 2, a charging car 3, a coke guide car 4, ;~
`~ 20 , a quenchlng car 5 and a bag filter dust collector 6. A combus-` tion chamber 7 and a section blower 8 with a pre-dust collector are disposed on the charging car (3) which has a duct 9. The coke guide car (4) has a hood (10) and a duct (11). The pre-dust . ,: ., collector in the suction blower (8) is a wet type dust collector ~` and the dust from the combustion chamber (7) is collected and the ~`` temperature of the gas is decreased. The ducts (9) and (11) are `' commonly connected through a blower (12) to the dust collector ~ -(6) both of which are disposed on the ground. Dampers (13) and (14) are provided in the ducts (9) and (11) particularly to pre- ¦~
vent surging.
In the operation of the coke oven, gases and dust , , spout out when the coke falls down through the coke guide car '~
~ .
.: ,,- .: :
.':' . : . . ' : . ~
636~
(4) on the quenching car (5) in the coke discharge step. When the hood (lO) of the ~uide car (4) is connected to the duct (11) the gases and dust are collected in the hood (10) on the coke guide car (4) by the operatlon of the blower (12) disposed on the ground, and they are sucked into the duct (11) and the dust con-taining gas is cleaned by the dust collector (6) from whence it is discharged into the atmosphere. In the following coal charge step, the dust containing gas spouted out, is sucked by the opera-, tion of the suction blower mounted on the charging car (3) and the combustible components in the gas are burnt in the combustionchamber (7). The combustion chamber (7) has a limited space on the charging car (3), whereby the capacity of the combustion cham- l~
ber (7) is insufficient to accomplish complete combustion of the ' -combustible components. Accordingly, the exhaust gas from the ;
chamber (7) contains relatively large amounts of tar mists, coal dust and coke dust. When the delivery of the pre-dust collector l of the charging car is connected to the duct (9), the dust con- ~ `
taining gas after the combustion of the combustible components, is fed from the chamber (7) into the duct (9) and the gas is sucked into the blower (12) in a similar manner as that of the coke discharge step. The dust containing gas is cleaned by the ; dust collector (6) and is discharged to the atmosphere. The suction rate in the coal charge step is usually about 1/2 or less ! of the suction rate at the coke discharge step. The suction rate is controlled at the coal charge step. The suction rate is suitably controlled by preventing the surging of the blower (12 ` by openingthe damper (14) orcontrolling thespeed ofthe blower (12).
In the bag filter dust collector (6) a plurality of tubular filters (17) are suspended by means of springs (16) in ` a casing (15) (Figure 3(a)). The exhaust gas passes from the inner part of the tubular filter (17) upwardly through the parti-tion (18a) in the casing (15) via holes (18c) to discharge into : .~ , , . ' _ g_ . . . . _ .. ~ ., . , ~
- ~( 1686~6 the atmosphere. A co~bined duct (19) from the blower (12) for the dust containing gases enters below a lower partition (18b).
Thus in the dust collector (6) a preliminary dust deposited layer (20) is maintained on the inner surface of the tubular filter (17) and it is not easily shaken down (see Figure 3(c)). As shown in Figure 3(b), a layer of dust (21) at the coke discharge step is collected on the surface of the preliminary deposited layer (20). The dust and tar mists in the following coal charge step are collected on the surface of the layer of dust (21). When a compressed air is fed from above of the upper partition (18a) so as to in~ect the compressed air inwardly from ~he outer surface of the tubular filter (17), `
so as to shake down the deposited dusts, the dust layer (21) collected in the step of discharging the coke and the dust and tar mists layer (22) collected in the coal charge step are shaken down from the inner surface of the tubular filter (17) as shown in Figure 3(c). Accordingly, the dust containing tar mists do ~" .
not contact the tubular filters (17) per se.
Under optimum conditions of operation, the suction rate in the dust collection at the coal charge step is reduced to half by controlling a speed of the blower (12) and the speed of filter-~` ing the gas in the bag filter dust collector (6) is reduced, whereby the increase of pressure loss on the filter (6) is re-duced and the shaking-down rate is reduced and the life ~f the tubular filters (17) is prolonged.
As stated above, in accordance with the system of the ¦
invention, only one dust collector is commonly employed in both ¦~
-` of the coke discharge step and the coal charge step~ Moreover, a bag filter dust collector which has high efficiency of dust ~`30 collection can be employed for collecting dusts containing tar mists, andthedustcontaining gascanbecleaned to a high extent.
Accordingly, air pollution problems are not caused by discharging , -10-. ' ' - - .
:: . .. . -~L~)68~36 : .
the exhaust gas after the dust collection to the atmosphere.
The dust collector of the invention is not limited to a common dust collector for the coke guide truck and the coal feed truck. It is possible to employ a combination of a dust collector in the pusher side and the dust collector for : coal feed truck; or a combination of said three dust collectors.
i Referring to Figure 5, a further embodiment of the invention , is illustrated. In Figure 5 a dust collecting duct (32) for a charging car (31) is connected through a duct connector (42) to the charging car (31). A dust collecting duct (34) for coke discharge is connected through a duct connector (41) to the coke guide car (33). The dust collecting duct (32) for charging . car (31) is connected to the dust collecting duct (34) for , coke discharge at both ends to form a loop. The ends of the ` dust collecting ducts (32) and (34) are connected through a ; ~ suction duct (36) to the blower (35). The blower (35) is connec-. ~., ~ .
ted in series to the dust collector (37) and the stack (38).
An automatic damper (39) is disposed at a suction side of the blower t35) which prevents the blower (35) surging during the time that neither the dust collection forcharging car (31) nor the dust collection for thecoke discharge step is conducted.
The blower (35) is driven by a motor (40) whose speed is controll-able so as to suck the dust containing gas at a blow rate of Q/2 of air. In Figure 5, the blow rate of the dust containing gas sucked from the coke guide car (33) is given as Q; the blow rate of the dust containing gas sucked from the charging car (31) is given as Q/2; the blow rate of air sucked from the automatic damper (39) is given as Q/2. The efficiency of the : .:. .j ~` blower (35) is to suck the blow rate of gas Q. The conditions ` 30 of the operation of the coke oven dust collecting system in .... . .
the one step of the coke oven operation, are as follows in the ~` embodiment of Figure 5.
;: .. : ..
-- 11 -- .. , '' ~ .. ...
: ~j ,. . .. , .. .. . . . , . , .. ; , .... , . ,:
`~
~ ~0~8636 :, .. In the normal condition that neither of the dust collection for the coke discharge step nor the dust collection ~, ...
for the coal charge step is conducted, the dust collecting connectors (41) and (42) for the guide car (33) and the charging .. car (31) are not connected to the dust collecting ducts (34) and ;'; ~32) respectively by opening the automatic damper (39). According- .
ly, a blow rate of gas sucked by the blower (35) from the dust ;. collecting ducts (32) and (34) is zero. Air is only sucked from the automatic damper (39). The speed of the blower (35) is N/2 and the electric power is P/8. When the dust collecting connector :
.` (41) is connected to the dust collecting duct (34) for thecoke ~;. discharge step, the automatic damper (39) is switched from the :
. open state to the closed state by the signal for coke discharge -:~ given from a pusher (not shown), and the speed of the blower is ; , , raised from N/2 to N. At the time, the blow rate of the dust containing gas sucked by the blower from the coke guide car (33) ~ . . , is Q. The electric power is P. As shown in Figure 4, when the coke discharge is finished after about 90 seconds, the dust : . . . .
- : collecting connector (41) is separated from the dust collecting . 20 duct (34) so as to be able to conduct the operation of dust : .
collection for the coal charge step. In the dust collection for ` the coal charge step, the dust collecting connector (42) is .
: connected to the dust collecting duct (32). The speed of the ~-~-. blower (35) is reduced from N to N/2 by the signal for the coal .~: charge step given from the charging car (31). At the time, the automatic damper maintains the closed state. The dust containing ~`. gas is sucked by the blower (35) from the charging car (31) at a ~` blow rate of Q/2. The electric power is P/8. In the coal charge .
i; B step as shown in Figure 4, the coal charge is finished~r 210 seconds. When the coal charge operation is finished, the dust ~.
~" collecting connector (42) is separated from the dust collecting ~`~ duct (32). The signal of the charging car (31) is turned off to ..
:, , , ~ , , , , ' :
:, .. :: , -~ ~L~8~3~;
switch the automa-tic damper (39) from the closed state to the open state. Thus, the first dust collecting step in the first coke oven is completed and the dust collecting step in the next coke oven is conducted. The operation is sequentially repeated.
In the coke damper control system for controlling a blow rate of gas with a fixed damper disposed in a dust collecting cluct (32) for the coal charge step without changing the speed of the blower (35), even though the blow rate of ~as is reduced to Q/2, the electric power reduces to only about 2/3 P because of blower characteristics. However, in the blower speed control system, the electric power reduces to 1/8 P in such a case. ~-Moreover, it only takes 90 seconds to suck the gas at the maximum blow rate of Q in the coke discharge step as compared 450 seconds of total operation time for thecoke discharge step and the coal charge step in the coke oven. Accordingly, it takes 360 seconds . , to suck the gas at the blow rate of Q/2 in the coal charge step and other steps, whereby the effect of reduced power consumption is remarkable. In the embodiment, there is no description of the speed control system for driving the blower (35). Thus, it is considered from the viewpoint of severe operation in which `~
many switchings between acceleration and reduction are given ~`
-~ in the dust collector of the coke oven, it is preferable to . :::- ::
employ a static control apparatus which can set a desirable `- speed corresponding to a blow rate of gas sucked-and which has : - regenerative braking system at the reduction of the speed whereby i.. , ~- : - .
the effect of power reduction isimproved and the other operational effects can be attained.
., " -~ , . . .
It is preferable to employ a dust collector in which a blow rate of the dust containing gas is low under satisfactory `' 30 characteristics of the speed control in order to employ an ~ electrical dust collector or a bag filter which has high effic-~` ' .
~ iency for dust collection. Fromthe viewpoint o~ pressure loss, .~. . .
. ~, . .
, - ` :
; it can be applicable under pressure reduction in the speed reduc- `
tion o~ the blower. It is also possible to use another type dust collector which has similar characteristics.
In said embodiment, one dust collector is commonly employed for dust collection at the coke discharge step and for dust collection in the coal charge step for carbonization, and the speed of the blower is controlled. Thus, it is possible to expect same effect of speed control in the blower of the specific dust collector ~or discharging coke from the coke oven. As stated above, in accordance with the system of the invention, the dust collecting duct for coal charge and the dust collecting duct for coke discharge are connected through one common blower to one dust collector and the speed of the blower is controlled so as to operate to give desirable blow rates for each of the gases in the coke discharge step and the coal charge step.
Accordingly, both of the dust collection for the coke discharge ` step and the dust collection for the coal charge step can be ; attained by using one dust collector. Accordingly, the apparatus ~ -can be simplified and the cost for the apparatus can be highly reduced. The speed of the blower is controlled depending upon the ~ ;
, dust collection for the coke discharge step and the dust collection - for the coal charge step, whereby the cost of operation can be greatly reduced to give economical advantages. The blower is op-erated at a rated speed only during the short time of the discharg-ing step in one cycle coke oven operation, and the blower is oper- :
ated at a reduced speed during the other steps. Accordingly, the I
`' ~ -noise of the blower can be reduced. The size of the blower can ` be smaller by the combination of the speed control of the blower and the control of damper for preventing surging, and it is possible to operate the blower safely without surging. The dust in the duct for the charging car can be passed through the pre-dust collector before feeding in the bag filter dust ., ~.-.~ ', , .
~' - ' ' . .
.
:., . : .
collector whereby contents of the tar mist and the combustible gas can be remarkably reduced, and accidents such as combustion . ~ . . .
and explosion in the bag filter dust collector can be prevented without failure and the load of the bag filter dust collector can be remarkably reduced.
; The system for controlling the blower and the automatic damper is hereinafter illustrated in detail. A thyristor control circuit is connected to the blower (35) so as to select two steps of the blower speed of a rated blow rate operation and 1/2 blow ; 10 rate operation. The rated blow rate operation (N) is selected ~-~
when the blower receives both a signal for discharge duct connection from a coke guide car and a signal for discharge from the pusher. The 1/2 rated blow rate operation (N/2) is selected during the other time.
The automatic damper (39) has selective ON-OFF control circuit for closed and open states. The closed state of the ~ damper is selected when either of a signal for discharge from `- the pusher or a signal for charge from the chargingcar is received.
The open state of the damper is selected during the other period.
~` 20 The dust collecting duct (32) has each connecting port with a : . . . .
door corresponding to each coke oven chamber. The door is usually kept in closed state. However it is opened for connecting the .. ;.. , . ~..... .
delivery of the pre-dust collector disposed on the charging car, whereby the delivery is connected to the duct (32). The dust ' !: ' ~- collecting duct (34) has each connecting port with a door corres-ponding to each coke oven chamber. The door is usually kept in closed state, however it is opened for connecting to the hood j`` of the coke guide car, whereby the hood is connected to the duct (34). When neither the charge operation nor discharge operation is conducted, the doors for the connecting ports of the dust collecting ducts (32) and (34) are closed. Accordingly the ~` blower keeps the 1/2 rated blow rate operation (N/23 and the ~: :
. ~,~ ..
``` ' . , :
;36 ; ~ automatic damper ls kept in an open s-tate. ~ the discharge ; step, the dust collecting dust ~34) is connected to the hood of the guide car. The signal for discharge duct connection is generated, the automatic damper (39) is kept in open state and only gas in the hood of the guide car is sucked by the blower.
When the discharge of coke is initiated and the signal for dis-charge is generated from the pusher, the blower receives both the signal for discharge duct connection and the signal for discharge and the blow rate is switched to the rated blow rate operation at high speed. When the discharge of coke is finished by disconnection ~ ee~ the dust collecting duct (34) and the hood of guide car to stop the signal for discharge duct connection, the automatic damper (39) is switched to the open state and only gas from the damper is sucked by the blower. ~ the charge step, the delivery of the pre-dust collector of the charging car is connected to the dust collecting duct (32), and the signal for charge is generated whereby the automatic damper is switched to closed state. However, the blower, continues the l/2 rated blow ; rate operation whereby only gas from the delivery of the pre-dust .
collector of the charging car is sucked. When the charge of coal ` is finished and the signal for charge to stop the signal for ~. ~
charge, the automatic damper is switched to the open state, .
" whereby only gas from the damper is sucked by the blower and the :
blower continues the 1/2 rated blow rate operation. ~ ~
:
`' ' .
'`' ' '' .
,
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In the operation of a coke oven including a coke discharge step and a coal charge step, in each said steps a dust containing gas being discharged, a method of collecting dust from each of said gases which comprises passing each of said gases to a common bag filter dust collector; the gas from said coke discharge step being first passed to said collector to deposit a fine layer of coke particles contained in said gases on the filter, the gas for the coal charge step then being passed to said collector to deposit tar mists and dust contained in said gas on the layer of coke particles, and then alternately repeating passage of each dust containing gas from said steps into said filter.
2. A method as claimed in claim 1 in which each said gases from said steps are blown by a common blower through one dust collector, the speed of the blower being controlled to provide blow rates depending on the step of coke oven operation.
3. A method as claimed in claim 2 in which the blow rate at the cost charge step is less than at the coke discharge step.
4. A method according to claim 1, 2 or 3 wherein the dust containing gas from the coal charging step is burnt and then is preliminarily filtered by a wet type pre-dust collector before feeding the dust in the bag filter.
5. A method according to claim 1, 2 or 3 wherein the dust in the coal charging step is burnt in a combustion chamber disposed on a charging car and then is preliminarily filtered by a wet type pre-dust collector.
6. A method according to claim 2 in which surging due to the blower is prevented by control of the opening of the damper in the dust collecting duct.
7. A method as claimed in claim 6 wherein in either the coal charge step or the coke discharge step, the damper for preventing surgings is closed, and in the other step, the damper is opened and the blower speed in the coal charge step is kept at 1/2 or less of the blower speed at the coke discharge step.
8. In combination with a coke oven at dust collecting system which comprises a common bag filter dust collector; duct means for the removal of dust containing gases during coal charg-ing of said oven; duct means for removal of dust containing gases during coke discharge from said oven; blower means adapted to pass dust containing gases from said ducts alternately to said dust collector whereby fine coke particles may firstly be depos-ited on a surface of the filter from the coke discharge of said oven and dusts containing tar mists spouted out at the coal charging deposited on the layer of the fine coke particles.
9. The combustion according to claim 8 wherein a dust collecting duct for coal charging and a dust collecting duct for coke discharge are connected through one common blower to one said dust collector and means for controlling the speed of the blower to control a blow rates depending upon the step of the coke oven operation.
10. The combustion according to claim 8 wherein said means is adapted to control the speed of the blower to provide a blow rate at the coal charging less than the blow rate at the coke discharging of the oven.
11. The combustion as claimed in claim 8, 9 or 10 in which a combustion chamber is provided on a charging car for burn-ing the dust in the coal charging step; and a wet type pre-dust collector is provided to preliminarily filter the burnt dust.
12. The combustion as claimed in claim 9 including a damper to prevent surging which give substantially same blow rate in the dust collecting duct for coal charge by the suction of the blower.
13. A method of dust collecting from a coke oven system in which coal is charged and coke discharged comprising the steps of: (a) first collecting gases and dust spouted off from a coke discharging operation; (b) next collecting gases and dust spouted off from a coal charging operation; (c) success-ively alternating steps (a) and (b); (d) using suctioning means to suction said collected gases and dust to a common bag filter dust collector; and (e) maintaining the flow rate of said suctioned out gases and dust collected in the coal charging operation at one-half or less than the flow rate of said suctioned out gases and dust collected in the coke discharging operation and more than the minimum flow rate necessary to prevent surging; whereby fine coal particles emitted during the coal charging operation are deposited on a layer of the fine coke particles emitted during the coke discharging operation and the adhesion of tar mists on the surface of the filter in the bag filter dust collector is prevented.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14924474A JPS5177602A (en) | 1974-12-28 | 1974-12-28 | Kookusuroniokeru shujinhoho |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1068636A true CA1068636A (en) | 1979-12-25 |
Family
ID=15471019
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA242,708A Expired CA1068636A (en) | 1974-12-28 | 1975-12-29 | Dust collecting system for coke oven |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5177602A (en) |
| CA (1) | CA1068636A (en) |
| DE (1) | DE2558112C2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3311574A1 (en) * | 1983-03-30 | 1984-10-04 | Carl Still Gmbh & Co Kg, 4350 Recklinghausen | METHOD FOR LIMITING EMISSIONS IN THE OPERATION OF COOKING OVEN BATTERIES |
| JP4640575B2 (en) * | 2004-09-09 | 2011-03-02 | 進和テック株式会社 | Coke oven dust collector |
| CN103075727B (en) * | 2013-01-25 | 2014-09-10 | 福建永恒能源管理有限公司 | High-efficiency and environment-friendly coal-fired system for vertical boiler with bottom-built burner |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1229038B (en) * | 1964-05-06 | 1966-11-24 | Gewerk Schalker Eisenhuette | Device for extracting dust and gas when pressing horizontal coke oven chambers |
| DE2038729A1 (en) * | 1970-08-04 | 1972-02-10 | Amagasaki Coke Ind Ltd | Prevention of air contamination in coke man - ufacturing |
| DE2114585C3 (en) * | 1971-03-25 | 1973-09-20 | Gewerkschaft Schalker Eisenhuette, 4650 Gelsenkirchen | Coking furnace charging car |
| BE795031A (en) * | 1972-02-07 | 1973-05-29 | Waagner Biro Ag | FEEDING PROCESS AND DEVICE FOR COKE OVENS |
-
1974
- 1974-12-28 JP JP14924474A patent/JPS5177602A/en active Granted
-
1975
- 1975-12-23 DE DE19752558112 patent/DE2558112C2/en not_active Expired
- 1975-12-29 CA CA242,708A patent/CA1068636A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2558112A1 (en) | 1976-07-01 |
| JPS537161B2 (en) | 1978-03-15 |
| JPS5177602A (en) | 1976-07-06 |
| DE2558112C2 (en) | 1982-12-16 |
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