CA1074752A - Centrifuge - Google Patents
CentrifugeInfo
- Publication number
- CA1074752A CA1074752A CA285,087A CA285087A CA1074752A CA 1074752 A CA1074752 A CA 1074752A CA 285087 A CA285087 A CA 285087A CA 1074752 A CA1074752 A CA 1074752A
- Authority
- CA
- Canada
- Prior art keywords
- speed
- drum
- inner drum
- differential
- centrifuge
- 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
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
- H02P29/0016—Control of angular speed of one shaft without controlling the prime mover
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
- B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
- B04B1/2016—Driving control or mechanisms; Arrangement of transmission gearing
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Centrifugal Separators (AREA)
- Beans For Foods Or Fodder (AREA)
Abstract
Title:
Centrifuge Abstract of the disclosure:
A centrifuge for separating liquid and solid materials, comprising an outer drum and an inner drum formed as a worm conveyor. Control means are provided for maintaining a set speed differential between the outer drum and the inner drum at a constant value through a proportional action, and in addition to the proportional action performing a corrective control action on the speed differential upon variation of the torque required.
Centrifuge Abstract of the disclosure:
A centrifuge for separating liquid and solid materials, comprising an outer drum and an inner drum formed as a worm conveyor. Control means are provided for maintaining a set speed differential between the outer drum and the inner drum at a constant value through a proportional action, and in addition to the proportional action performing a corrective control action on the speed differential upon variation of the torque required.
Description
-2- ~7~7S~
This invention relates to a centrifuge for separating liquid and solid materials, which comprises an outer drum and an inner drum formed as a worm conveyor.
For certain purposes it is of importance that the dry matter leaves the centrifuge in as dry a condition as possible. This requires a relatively long residence time in the centrifuge. This residence time is determined by the rate of transport and hence by the difference in speed between the inner drum and the outer drum. Hereinafter it will be assumed that the centrifuge is so arranged that transport is effected in the correct direction if the inner drum rotates faster than the outer drum. It will be clear that the centrifuge can also be arranged to effect transportation of the sedimentation if the outer drum rotates faster than - -the inner drum.
According as the difference in r.p.m. between the inner drum and the outer drum is greater, the solid matter is transported through the machine at a higer rate9 and the moisture content of the solids leaving the centrifuge is higher. Accordingly, the aim is for the smallest possible difference in speed between the inner drum and the outer drum in order that the resulting solid matter may be as dry as possible. In the past, the desired difference in r.p.m. has been set at an experimentally determined value that was as low as possible. This~ however, led to the inner drum ~- becoming Jammed owing to an accumulation of solids upon undue variation ih the process parameters applying when the value was set.
, '' :, ', . .
.
,, "'.
.
:, . . .
1~79L7~Z
Centrifuge industries are attempting to solve these problems by using a hydraulic motor rotating along with the outer drum, which motor, through gearing, gives the inner drum, i.e. the worm conveyor, a slightly higher speed. The speed differential control realized in this way is a so-called two-point control, effectuated through the oil pressure. The stroke frequency depends on the load factor of the centrifuge and the adjusted band width of the control, a pendulating or cyclic speed differential between drum and worm causes a fluctuating and also a lower dry content.
It is an object of the present invention to provide a solution for the above problem~
According to the present invention, there is provided a centrifuge for separating liquid and solid materials, com-prising an elongated, rotatably mounted outer drum and an inner drum with a helical conveyor means thereon mounted in said outer drum for rotation about an axis coincident with the axis of rotation of the outer drum. Means is provided for rotating the outer drum. ~ differential drive 50 connects the outer drum and the helical conveyor-supporting inner drum that rotation of ` the outer drum effects rotation of the inner drum at a speed different from that of the outer drum. Governing means are provided for keeping the differential between the speed of the outer drum and the speed of the inner drum substantially con-stant. The governing means preferably include an electrical generator drive connected, in braking relationship, to the inner drum and control means for so proportioning the braking effect exerted by the generator to variations in the differential between the speed of the outer drum and khe speed of the inner drum as to keep the speed differential substantially constant.
The control means may compri~e tachogenerator means for producing a first signal indicative of the speed of the -~ _ 3 _ ~7475'~J
inner drum, means for cornparing the fir3t signal with a second signal indicative of a target speed of the inner drum which will produce the wanted di~erential between the speeds of the inner and outer drums and for deriving a feeaback control signal proportional to the difference between the actual speed of the inner drum and the target speed, and means utilizing the feed-back control signal to adjust the speed o~ the inner drum to the target speed. The control means may further include inte-grator means operable when the differential between the speeds of the inner and outer drums reach a selected magnitude indica-tive of incipient jamming of the centrifuge to provide a tran-sient modification of the feedback control signal which will produce a reduction in the braking effe~t exerted by the gene-rator which is greater than that which would be produced by virtue of the unmodified feedback control signal.
One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings~
In said drawings, Figure 1 shows a centrifuge of the type to which the present invention relates, and Figure 2 shows a control circuit arrangement according ko the present invention for u~e in a centrifuge as shown in Figure 1.
Referring to Figure 1, there is shown a centrifuge comprising an outer drum 1 with a conical part 2. Disposed within the outer drum is an inner drum 3, also having a conical configuration, and formed as a worm or screw conveyor. Pro-vided at the wide end of the drums is a central supply tube 4, serving to supply a mixture of liquid and solid material~ to the centri~uge. At the same end of the drum, there is provided an outlet opening 5 for the discharge of liquid st~ipped of solids. The liquid level within the drums at which liquid is ~ , . . .
--`` 107~7S~
discharged is determined by an adju8tab1e weir 6.
The centrifuge as shown is driven by a motor 10 through a cam disk reduction gear box 7 which operates in a manner akin to that of a differential and which is provided with a drum pulley 8, driven by the motor, for driving the outer drum, and a worm pulley 9 coupled with the inner drum.
In the present case the reducer provides a transmission ratio of 25:1 so that when the speed of the drurn pulley ndp = 1600 revolutions per minute and the speed of the worm pulley nwp =
1400 revolutions per minute, the outer drum has a speed n~ of 1600 r.p.m. and the inner drum a speed nw of 1600 ~ 160025 1608 r.p.m. Because nw = nd + dp wp, as shown by the fore-going, deceleration of the worm pulley results in a higher speed of the inner drum and hence to a higher speed differential.
According to the present invention, an electrical machine 20 operating as a generator (Fig. 2) is coupled to the -;
worm pulley, for example, through a belt transmission, as shown in Fig. 1 to brake the inner drum in a manner which will keep the differential in speed between it and the outer drum constant Fig. 2 shows a control circuit arrangement according to the present invention. The arrangement comprises a poten-tiometer 21, b~ means of which a given voltage value can b~ set, which is supplied to one input 22 of an r.p.m. control amplifier 23. This voltage value corresponds to the speed nwp of the worm pulley. Amplifier 23 has two further inputs 24 and 25, the function of which will be described hereinafter. Amplifier 23 operates a~ a differential amplifier and also as an inverter ; amplifier. At the output of arnplifier 23 a voltage signal appears, which is supplied through a potentiometer 27 to an input 29 of a second arnplifier 28 and serves as a target value Is for the current I frorn generator 20. To a second input 30 of amplifier 28 a signal proportional to current I is supplied .
~ : - , . . . - . : . , through a feedback loop comprisin~ a converter 31 ~or convertiny a voltage into phase differences, a thyristor control device 32, a current transformer 33, and a rectifier 34. The thyristor control device 32 is further coupled to generator 20, which in turn is coupled to a tachogenerator 35 for supplying a signal corresponding to the r.p.m. of generator 20 to input 24 of amplifier 23.
If the signal from the tachogenerator to input 24 is greater than that corresponding to the set r.p.m. of the worm pulley, this means that the r.p.m. of generator 20 and hence o~
the worm pulley, is too high. Because intermediate reducer 7 maintains a constant speed ratio between drum pulley 8 and worm pulley 9, this results in too low a speed differential between the outer drum and the inner drum as is apparent from the formula set forth above.
As a consequence of the input voltages applying at inputs 22 and 24, amplifier 23 now provides a higher target value for current I from generator 20, as a result of which generator 20 will begin to decelerate. This also decelerates the worm pulley, so that its speed nwp is decreased and the speed nw of the inner drum is increased. -~
It has been found, however, that such a control of the speed differential is not sufficient to prevent jamming.
If, at a selected speed differential, the amount or the con-centration of the substance to be centrifuged is increased, the transport capacity of the centrifuge is liable to be exceeded:
more substance is deposited than expelled, and the substance will form a rigid connection between the drum and the worm.
For this reason the feedback signal suppLied to the input of amplifier 28, which signaL is proportional to current value I, is also supplied to an integrator 38. The output of this integrator is connected to input 25 of r.p.m. control , .
- . - ~ . ;, -- , , ~: ... .
.
~7~75~2 amplifier 23. Now, an increase in -the value of ~, t~rouyh increased sedimentation, temporarily provides an additional input signal to input 25, whereby the target value for I is increased and a temporary additional decrease in the speed of generator 20, and hence of worm pulley 9, occurs, resulting in a higher speed differential between the inner and outer drums.
This additional braking accordingly provides a con-trolled increase in speed differential between the inner drum and the outer drum to clear the increased supply of substance.
~his control is continuous, and ensures non-oscillating r.p.m.
di~ferential.
With an increasing input signal, the integrator has a lower time constant than with a decreasing input signal. This ensures the stability of the control circuit.
It is to be understood that various modifications of the er~bodiment described and shown can be made without depart- ``~;
ing from the scope of the present invention. Such modifications are to be regarded as forming part of this invention.
' ' .. . . . ..
This invention relates to a centrifuge for separating liquid and solid materials, which comprises an outer drum and an inner drum formed as a worm conveyor.
For certain purposes it is of importance that the dry matter leaves the centrifuge in as dry a condition as possible. This requires a relatively long residence time in the centrifuge. This residence time is determined by the rate of transport and hence by the difference in speed between the inner drum and the outer drum. Hereinafter it will be assumed that the centrifuge is so arranged that transport is effected in the correct direction if the inner drum rotates faster than the outer drum. It will be clear that the centrifuge can also be arranged to effect transportation of the sedimentation if the outer drum rotates faster than - -the inner drum.
According as the difference in r.p.m. between the inner drum and the outer drum is greater, the solid matter is transported through the machine at a higer rate9 and the moisture content of the solids leaving the centrifuge is higher. Accordingly, the aim is for the smallest possible difference in speed between the inner drum and the outer drum in order that the resulting solid matter may be as dry as possible. In the past, the desired difference in r.p.m. has been set at an experimentally determined value that was as low as possible. This~ however, led to the inner drum ~- becoming Jammed owing to an accumulation of solids upon undue variation ih the process parameters applying when the value was set.
, '' :, ', . .
.
,, "'.
.
:, . . .
1~79L7~Z
Centrifuge industries are attempting to solve these problems by using a hydraulic motor rotating along with the outer drum, which motor, through gearing, gives the inner drum, i.e. the worm conveyor, a slightly higher speed. The speed differential control realized in this way is a so-called two-point control, effectuated through the oil pressure. The stroke frequency depends on the load factor of the centrifuge and the adjusted band width of the control, a pendulating or cyclic speed differential between drum and worm causes a fluctuating and also a lower dry content.
It is an object of the present invention to provide a solution for the above problem~
According to the present invention, there is provided a centrifuge for separating liquid and solid materials, com-prising an elongated, rotatably mounted outer drum and an inner drum with a helical conveyor means thereon mounted in said outer drum for rotation about an axis coincident with the axis of rotation of the outer drum. Means is provided for rotating the outer drum. ~ differential drive 50 connects the outer drum and the helical conveyor-supporting inner drum that rotation of ` the outer drum effects rotation of the inner drum at a speed different from that of the outer drum. Governing means are provided for keeping the differential between the speed of the outer drum and the speed of the inner drum substantially con-stant. The governing means preferably include an electrical generator drive connected, in braking relationship, to the inner drum and control means for so proportioning the braking effect exerted by the generator to variations in the differential between the speed of the outer drum and khe speed of the inner drum as to keep the speed differential substantially constant.
The control means may compri~e tachogenerator means for producing a first signal indicative of the speed of the -~ _ 3 _ ~7475'~J
inner drum, means for cornparing the fir3t signal with a second signal indicative of a target speed of the inner drum which will produce the wanted di~erential between the speeds of the inner and outer drums and for deriving a feeaback control signal proportional to the difference between the actual speed of the inner drum and the target speed, and means utilizing the feed-back control signal to adjust the speed o~ the inner drum to the target speed. The control means may further include inte-grator means operable when the differential between the speeds of the inner and outer drums reach a selected magnitude indica-tive of incipient jamming of the centrifuge to provide a tran-sient modification of the feedback control signal which will produce a reduction in the braking effe~t exerted by the gene-rator which is greater than that which would be produced by virtue of the unmodified feedback control signal.
One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings~
In said drawings, Figure 1 shows a centrifuge of the type to which the present invention relates, and Figure 2 shows a control circuit arrangement according ko the present invention for u~e in a centrifuge as shown in Figure 1.
Referring to Figure 1, there is shown a centrifuge comprising an outer drum 1 with a conical part 2. Disposed within the outer drum is an inner drum 3, also having a conical configuration, and formed as a worm or screw conveyor. Pro-vided at the wide end of the drums is a central supply tube 4, serving to supply a mixture of liquid and solid material~ to the centri~uge. At the same end of the drum, there is provided an outlet opening 5 for the discharge of liquid st~ipped of solids. The liquid level within the drums at which liquid is ~ , . . .
--`` 107~7S~
discharged is determined by an adju8tab1e weir 6.
The centrifuge as shown is driven by a motor 10 through a cam disk reduction gear box 7 which operates in a manner akin to that of a differential and which is provided with a drum pulley 8, driven by the motor, for driving the outer drum, and a worm pulley 9 coupled with the inner drum.
In the present case the reducer provides a transmission ratio of 25:1 so that when the speed of the drurn pulley ndp = 1600 revolutions per minute and the speed of the worm pulley nwp =
1400 revolutions per minute, the outer drum has a speed n~ of 1600 r.p.m. and the inner drum a speed nw of 1600 ~ 160025 1608 r.p.m. Because nw = nd + dp wp, as shown by the fore-going, deceleration of the worm pulley results in a higher speed of the inner drum and hence to a higher speed differential.
According to the present invention, an electrical machine 20 operating as a generator (Fig. 2) is coupled to the -;
worm pulley, for example, through a belt transmission, as shown in Fig. 1 to brake the inner drum in a manner which will keep the differential in speed between it and the outer drum constant Fig. 2 shows a control circuit arrangement according to the present invention. The arrangement comprises a poten-tiometer 21, b~ means of which a given voltage value can b~ set, which is supplied to one input 22 of an r.p.m. control amplifier 23. This voltage value corresponds to the speed nwp of the worm pulley. Amplifier 23 has two further inputs 24 and 25, the function of which will be described hereinafter. Amplifier 23 operates a~ a differential amplifier and also as an inverter ; amplifier. At the output of arnplifier 23 a voltage signal appears, which is supplied through a potentiometer 27 to an input 29 of a second arnplifier 28 and serves as a target value Is for the current I frorn generator 20. To a second input 30 of amplifier 28 a signal proportional to current I is supplied .
~ : - , . . . - . : . , through a feedback loop comprisin~ a converter 31 ~or convertiny a voltage into phase differences, a thyristor control device 32, a current transformer 33, and a rectifier 34. The thyristor control device 32 is further coupled to generator 20, which in turn is coupled to a tachogenerator 35 for supplying a signal corresponding to the r.p.m. of generator 20 to input 24 of amplifier 23.
If the signal from the tachogenerator to input 24 is greater than that corresponding to the set r.p.m. of the worm pulley, this means that the r.p.m. of generator 20 and hence o~
the worm pulley, is too high. Because intermediate reducer 7 maintains a constant speed ratio between drum pulley 8 and worm pulley 9, this results in too low a speed differential between the outer drum and the inner drum as is apparent from the formula set forth above.
As a consequence of the input voltages applying at inputs 22 and 24, amplifier 23 now provides a higher target value for current I from generator 20, as a result of which generator 20 will begin to decelerate. This also decelerates the worm pulley, so that its speed nwp is decreased and the speed nw of the inner drum is increased. -~
It has been found, however, that such a control of the speed differential is not sufficient to prevent jamming.
If, at a selected speed differential, the amount or the con-centration of the substance to be centrifuged is increased, the transport capacity of the centrifuge is liable to be exceeded:
more substance is deposited than expelled, and the substance will form a rigid connection between the drum and the worm.
For this reason the feedback signal suppLied to the input of amplifier 28, which signaL is proportional to current value I, is also supplied to an integrator 38. The output of this integrator is connected to input 25 of r.p.m. control , .
- . - ~ . ;, -- , , ~: ... .
.
~7~75~2 amplifier 23. Now, an increase in -the value of ~, t~rouyh increased sedimentation, temporarily provides an additional input signal to input 25, whereby the target value for I is increased and a temporary additional decrease in the speed of generator 20, and hence of worm pulley 9, occurs, resulting in a higher speed differential between the inner and outer drums.
This additional braking accordingly provides a con-trolled increase in speed differential between the inner drum and the outer drum to clear the increased supply of substance.
~his control is continuous, and ensures non-oscillating r.p.m.
di~ferential.
With an increasing input signal, the integrator has a lower time constant than with a decreasing input signal. This ensures the stability of the control circuit.
It is to be understood that various modifications of the er~bodiment described and shown can be made without depart- ``~;
ing from the scope of the present invention. Such modifications are to be regarded as forming part of this invention.
' ' .. . . . ..
Claims (3)
1. A centrifuge for separating liquid and solid materials, comprising: an elongated, rotatably mounted outer drum, an inner drum with a helical conveyor means thereon mounted in said outer drum for rotation about an axis coincident with the axis of rotation of said outer drum; means for rotating said outer drum, a differential drive so connecting said outer drum and said helical conveyor supporting inner drum that rotation of said outer drum effects rotation of said inner drum at a speed different from the speed of rotation of said outer drum; and means for keeping the differential between the speed of the outer drum and the speed of the inner drum substantially con-stant, said last mentioned means comprising an electrical generator drive connected in braking relationship to said inner drum and control means for so proportioning the braking effect exerted by said generator to variations in the differential between the speed of the outer drum and the speed of the inner drum as to keep said speed differential substantially constant.
2. A centrifuge, as defined in claim 1, wherein said control means comprises tachogenerator means for producing a first signal indicative of the speed of said inner drum, means for comparing said first signal with a second signal indicative of a target speed of the inner drum which will produce the wanted differential between the speeds of the inner and outer drums and for deriving a feedback control signal proportional to the difference between the actual speed of the inner drum and said target speed, and means utilizing said feedback con-trol signal to adjust the speed of said inner drum to said target speed.
3. A centrifuge, as defined in claim 2, wherein said control means further includes an integrator means operable when the differential between the speeds of the inner and outer drums reaches a selected magnitude indicative of incipient jamming of the centrifuge to provide a transient modification of said feedback control signal which will produce a reduction in the braking effect exerted by said generator which is greater than that which would be produced by virtue of the unmodified feedback control signal.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7609294A NL7609294A (en) | 1976-08-20 | 1976-08-20 | SPIN CONTROL. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1074752A true CA1074752A (en) | 1980-04-01 |
Family
ID=19826772
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA285,087A Expired CA1074752A (en) | 1976-08-20 | 1977-08-19 | Centrifuge |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5325964A (en) |
| AT (1) | ATA597077A (en) |
| BE (1) | BE857885A (en) |
| CA (1) | CA1074752A (en) |
| DE (1) | DE2736893A1 (en) |
| DK (1) | DK368577A (en) |
| ES (1) | ES461736A1 (en) |
| FI (1) | FI772443A (en) |
| FR (1) | FR2361942A1 (en) |
| LU (1) | LU77985A1 (en) |
| NL (1) | NL7609294A (en) |
| NO (1) | NO772883L (en) |
| SE (1) | SE7709335L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3115692A1 (en) * | 1981-04-18 | 1982-11-11 | Klöckner-Humboldt-Deutz AG, 5000 Köln | ADAPTIVE RULING PROCEDURE |
| FR2532198B1 (en) * | 1982-08-27 | 1985-06-21 | Bertin & Cie | ENERGY RECOVERY CENTRIFUGE |
| JPS60235660A (en) * | 1984-05-07 | 1985-11-22 | Toshiba Corp | Controlling device for dehydrator |
| WO1994014515A1 (en) * | 1992-12-29 | 1994-07-07 | Viktor Efimovich Minaker | Method of separating a suspension and device for carrying this out |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1926995A (en) * | 1931-05-04 | 1933-09-12 | Gen Chemical Corp | Filter |
| US3734399A (en) * | 1971-05-28 | 1973-05-22 | Beloit Corp | Differential scroll drive |
-
1976
- 1976-08-20 NL NL7609294A patent/NL7609294A/en not_active Application Discontinuation
-
1977
- 1977-08-16 FI FI772443A patent/FI772443A/en not_active Application Discontinuation
- 1977-08-16 DE DE19772736893 patent/DE2736893A1/en active Granted
- 1977-08-18 AT AT597077A patent/ATA597077A/en not_active Application Discontinuation
- 1977-08-18 LU LU77985A patent/LU77985A1/xx unknown
- 1977-08-18 SE SE7709335A patent/SE7709335L/en not_active Application Discontinuation
- 1977-08-18 NO NO772883A patent/NO772883L/en unknown
- 1977-08-18 DK DK368577A patent/DK368577A/en unknown
- 1977-08-18 BE BE2056164A patent/BE857885A/en unknown
- 1977-08-19 CA CA285,087A patent/CA1074752A/en not_active Expired
- 1977-08-19 JP JP9940277A patent/JPS5325964A/en active Pending
- 1977-08-19 ES ES461736A patent/ES461736A1/en not_active Expired
- 1977-08-22 FR FR7725520A patent/FR2361942A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5325964A (en) | 1978-03-10 |
| NL7609294A (en) | 1978-02-22 |
| NO772883L (en) | 1978-02-21 |
| ES461736A1 (en) | 1978-06-01 |
| BE857885A (en) | 1978-02-20 |
| FR2361942B3 (en) | 1980-06-13 |
| DE2736893A1 (en) | 1978-07-06 |
| ATA597077A (en) | 1980-06-15 |
| DE2736893C2 (en) | 1989-12-07 |
| DK368577A (en) | 1978-02-21 |
| SE7709335L (en) | 1978-02-21 |
| FR2361942A1 (en) | 1978-03-17 |
| LU77985A1 (en) | 1978-04-27 |
| FI772443A (en) | 1978-02-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |