CA1170092A - Vacuum control system for dewatering fabrics - Google Patents
Vacuum control system for dewatering fabricsInfo
- Publication number
- CA1170092A CA1170092A CA000405352A CA405352A CA1170092A CA 1170092 A CA1170092 A CA 1170092A CA 000405352 A CA000405352 A CA 000405352A CA 405352 A CA405352 A CA 405352A CA 1170092 A CA1170092 A CA 1170092A
- Authority
- CA
- Canada
- Prior art keywords
- vacuum
- vacuum pump
- suction pipe
- pump
- level
- 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
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F7/00—Other details of machines for making continuous webs of paper
- D21F7/08—Felts
- D21F7/12—Drying
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/04—Filters with filtering elements which move during the filtering operation with filtering bands or the like supported on cylinders which are impervious for filtering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
- B01D33/72—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding
- B01D33/722—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding containing fixed liquid displacement elements or cores
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
- B01D33/74—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging filtrate
- B01D33/745—Construction of suction casings, pans, or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/80—Accessories
- B01D33/804—Accessories integrally combined with devices for controlling the filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/80—Accessories
- B01D33/804—Accessories integrally combined with devices for controlling the filtration
- B01D33/808—Accessories integrally combined with devices for controlling the filtration by pressure measuring
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/48—Suction apparatus
Abstract
VACUUM CONTROL SYSTEM FOR DEWATERING FABRICS
ABSTRACT OF THE DISCLOSURE
A vacuum control system for dewatering fabrics on a papermaking machine including a suction pipe and a vacuum pump connected to the suction pipe to supply a desired vacuum level. The fabric is passed over a slot in the suction pipe so that suction applied therethrough will dewater the fabric.
Controls are connected to the suction pipe and to the vacuum pump responsive to an increase in the vacuum level in the suction pipe as fabric permeability decreases to correspondingly lower the speed of the vacuum pump and retain the desired vacuum level in the suction pipe.
ABSTRACT OF THE DISCLOSURE
A vacuum control system for dewatering fabrics on a papermaking machine including a suction pipe and a vacuum pump connected to the suction pipe to supply a desired vacuum level. The fabric is passed over a slot in the suction pipe so that suction applied therethrough will dewater the fabric.
Controls are connected to the suction pipe and to the vacuum pump responsive to an increase in the vacuum level in the suction pipe as fabric permeability decreases to correspondingly lower the speed of the vacuum pump and retain the desired vacuum level in the suction pipe.
Description
1~700~ ~
VACUUM CONTROL SYSTEM FOR DEWATERING FABRICS
'067-99 1 BACKGROUND OF THE INVENTION
~RH/JCS~pb ¦
Dewatering systems are well known in the papermaking l industry. In fact, in a papermaking process there are several 1 areas on the machinery where dewatering is a common process.
For example, in the press section of the machine one or more suction pipes are connected to a source of suction and are slotted to permit passing of a fabric such as a paper maker's press felt thereacross. Applied suction through the slots and the pipes dewaters the felt and the mixture of water and air is separated in a conventional manner. Generally in this portion of the machinery, it is advisable to use a liquid ring or positive displacement type of vacuum pump.
Generally the vacuum pumps are sized for maximum demand vacuum conditions in the suction pipe when the felt or similar fabric is new. Once this vacuum set point is accom-plished and the system is initiated, the vacuum pump will run at its maximum speed when the felt is new. As the elt permeability decreases with time, the vacuum level at the suctior. pipe automatically increases because the vacuum pump used is a constant volume unit. Various solutions have been devised to take advantage of the increased vacuum conditions such as by automatically or manually adjusting the slot width so that a greater portion of the felt is subjected to the increased I
:,` .
.. . ~ .
~ ~700~2 vacuum conditions at any given point in time. With present concern in energy consumption, it would be an additional advantage if the energy utilized by the vacuum pump during the life of the felt is reduced. Savings in energy consump-tion in this manner is extremely desirable in today's paper making environment as well as any environment where energy is being used.
Naturally in dealing with the portion of the paper-making machine employing suction pipes, and where desired vacuum level is to be maintained in the pipe, it is common to use the liquid ring or positive displacement vacuum pumps for maximum effectiveness. A means of reducing energy con-sumption of these types of pumps is certainly desirable and would add to the overall efficiency of the papermaking machine particularly in regard to energy conservation. A
natural added result would be cost savings from an energy standpoint. As stated above, prior developments in this area have generated cost savings~ For example, systems have been designed which minimize horsepower requirements for vacuum pumps.
. .
I :1~7~9~
SUMMARY OF THE INVENT ION
With the above background in mind, it is among the primary objectives of the present invention to provide a unique vacuum control system for papermaking machinery in particular that por-tion of the machinery where suction pipes are used to dewater fabrics such as press felts. The present invention employs a variable speed drive on a liquid ring or positive displacement vacuum pump to control the maximum vacuum at a suction pipe or pipes for dewatering press felts or similar fabrics. In fact, the present system can be used on those fabricc where the air flow permeability changes wit~ time or style.
A significant advantage of the present system is in the reduction of the total ener~y con~umed by the felt dewatering vacuum pumps. -It is an objectiv~ of the present invention to interconnect a variahle speed drive motor and control circuitry l1 including a vacuum sensor to the vacuum pump and to one or more ,; suction pipes. It is an objective to simplify the operat;on of , the dewatering system so that operation can be initiated by ` setting the maximum vacuum required to dewater a given ~eIt at its minimum felt permeability. Once this vacuum set point has been set, the vacuum pump runs at its maximum speed when the felt i5 new. As the felt permeability decreases with time, _ . .
the vacuum level at the suction pipe will automatlcally increase 2S because the vaauum pump used is a constant volume unit. All this time the vacuum pump wlll run at its maximum speed, until -``!1 1 1 1 7~092 the vacuum level has reached the set point on the controls.
To maintain this desired maximum vacuum level at the suction pipe, the variable speed drive motor will be activated to start to slow down the vacuum pump as the felt permeability decreases.
The lower pump speeds result in lower drive horsepower consumed.
In fact, the power requirements of the vacuum pump may almost be half of what they would be in present conventional systems toward the end of a given felt life.
In summary, a vacuum control system for dewatering fabrics on a paperma~ing machine is provided which is particular-ly adaptable for that portion of the machine employing suction pipes. A vacuum pump is connected to each suction pipe to supply a desired vacuum level. Means is on the machine for passing the fabric over a slot in the suction pipe so that suction applied therethrough will dewater the fabric. Control means is connected to the suction pipe and to the vacuum pump and is responsive to an increase in the vacuum level in the suction pipe as fabric permeability decreases to c~rrespondingly lower the speed of the vacuum pump and retain the desired vacuum level in the suction pipe.
With the above objectives among others in mind, reference is made to the attached drawing.
BRIEF DESCRIPTION OF THE DRAWING
' ' : :
Figuro 1 is a schematl view of the vacuum control .
Ii ~1700~2 ,1 1 system incorporated as part of the section of a papermaking machine employing suction pipes; and il Figure 2 is a block diagram of the controls of the ~I vacuum control system of the invention.
¦ DETAILED DESCRIPTION
The depicted portion 20 of a well known type of papermaking machine is that part of the press end of the machine ¦ employing one or more suction pipes 22 for dewatering a press Il fe`lt 24 or similar fabric. This is a common arrangement at the ,I press section of the papermaking machine.
Each suction pipe 22, as is well known, includes a ¦ hollow conduit 26 with a slot 28 forming an opening in its upper il end. An exit conduit 30 passes to a conventional type of ~ liquid and gas separator 32. The separator is connected by I conduit 34 to a vacuum pump 36 such as a conventional type of liquid ring or positive displacement vacuum pump. Conventionally in the system, a relief valve 38 is in the line between the separator and the vacuum pump for vacuum relief purposes when needed. Separator 32 has a bottom exit 40 for passage of separated liquid into a seal pit 42 through a drop leg 43. In ¦¦ the drawing, water 44 collected by the dewatering process is ¦¦ shown in seal pit 42.
A conventional drive shaft 39 interconnects a variable I speed drive motor 41 with the vacuum pump 36 to adjust and drive the vacuum pump at a chosen variety of speeds depending upon ~1 - ~ ~70032 ., . I
, vacuum conditions in the hollow interior of suction pipe 22. A
!~ conventional electrical control panel 45 is connected by wire 47 to the variable speed drive motor to control the motor and Il accordingly the speed of the pump 36. The controls are also 1 electrically connected through connector 46 to a well known type of electrical or pneumatic vacuum sensor 48 mounted on the suction pipe so as to measure the level of vacuum on the interior of the pipe at any given point in time.
The above system is similar to well known dewatering ¦ systems used in mills today with the exception of the variable speed drive motor 40 and interconnected controls 45 to adjust the i speed of pump 36.
. In operation, the system is set up as shown in Fig. 1 I and the controls are adjusted to react to a setting of the maximum vacuum required to dewater a given felt such as felt 24 at its minimum felt permeability. Once this vacuum point has been set, vacuum pump 36 will run at its maximum speed when felt 22 is new. The felt passes, as shown by the arrow, from left to right across slot 28. Suction in suction pipe 22 draws air and water through and from felt 24 into a hollow ¦¦ interior of suction pipe 22 as the felt passes over slot 28.
Il This combination of air and water then passes through exit conduit ¦l 30 into the separator 32 where the water and air are separated.
' 1¦ The water drains through bottom exit opening 40 into the seal 1 pit 42 through drop leg 43. The separated air still subjected to vacuum is drawn through conduit 34 into the pump 36 and exits to atmosphere through exit opening 50 of the vacuum pump. This ¦ path of travel is depicted by the arrows in Fig. 1.
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Il ~17~092 ' ¦ As stated, once the vacuum point has been set in ¦' regard to the control panel, the vacuum pump 36 will run at its maximum speed when the felt is new. As the felt permeability~
I decreases in time, the vacuum level at the suction pipe 22 S ¦ will automatically increase because vacuum pump 36 is a constant j volume unit. All this time vacuum pump 36 will run at its maximum speed, until the vacuum level has reached the set point at the controller 45. Sensor 48 detects the vacuum conditions in suction pipe 22 during this entire period of time and the controls 45~ are ~esponsive to the vacuum sensed by sensor 48. To maintain this desired maximum vacuum level at suction ¦ pipe 26, vacuum pump 36 will then start to slow down as the felt permeability decreases. This is accomplished by the electrical connector 47 between control panel 45 and the variable lS ¦ speed drive motor 41. The controls cause the drive motor to lower the speed of the pump 36. Lower pump speeds result in lower drive horsepower consumed. Accordingly, the power require-ments of vacuum pump 36 in many instances will almost be half of what they would be in a conventional system without the variable speed motor and appropriate controls toward the end of a given felt life.
Electrical panel 45 operates in the following manner as depicted in Fig. 2~ The vacuum level in the vacuum sensing line 46 L9 conv~r ed t~ a lo~ el electrical s~gnal ~y a !l !
1 :1700~2 common gauge pressure transducer 52. This low level signal is amplified by a signal conditioning amplifier 54, which may also have a non linear gain characteristic, if desired. In Il this way, the non-linear air flow characteristics of the pump Il or exhauster may, in affect be linearized. This permits ,I stable control bver a wider range of air flows than would be possible wi~hout non-linear gain.
The amplified signal is presented to a proportional I control circuit 56 of conventional design. The set point adjustment of this control circuit permits setting of the , vacuum level to be maintained. The output signal from this proportional control circuit 56 is used as the speed control signal through line 47 into the variable speed motor drive 41.
¦ In addition to controlling pump motor speed in normal ,¦ operation, the controls must protect the pump and motor from ¦¦ abnormal conditions. Circuitry 58 consisting of limit sensors 1ll and digital logic gates provides orderly and safe shutdown ¦¦ in such circumstances. These circuits also control system I¦ startup. Digital signals from the circuits are connected 1l directly to control imputs on the variable speed motor drive 41 ¦¦ Conventional elements are available for all portions l of the above described circuitry. For example, acceptable for j : I
Il the gauge pressure transducer 52 is a Model DPl5 manufactured !I by Validyne Engineering Corporation of Northridge, California 1 9132~. Model CDIlS of the;same company would operate successf :~70~)~2 ~I ~
I¦ as the electronic signal conditioning amplifier 54. Proportional !
¦I control circuit 56 would be satisfied, for example, by Model ¦ AP 2162-3106 of Action Instruments Co., Inc. of San Diego, l California 92123. An example of acceptable circuitry for the 1 unit sensor and control switching circuit 58 is Model AP 1020-3007 of the same Action Instruments Co., Inc.
The following table shows the improved reduction in energy consumption by the present system in contrast to a l conventional system. The table readings rela~e to a suction , pipe including two one-half inch slots with a maximum vacuum required of 13 inches Hg. The press location is the third press j! of the press section of a papermaking machine. The moisture contents before MPl and after MP2 suction pipes are respectively .6 H2O/felt and .54 H2O/felt. The system was designed to remove l .06 H2O/felt of shower water. The felt permeability was 60 New, the felt width 230" and the machine speed 2450 fpm.
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~1 1 '~ From the above comparison Table, it is apparent that the vacuum pump drive power requirements decreased after the i felt permeability reached 35 versus remaining constant (at a ¦ maximum) with a conventional system. Depending upon machine ~¦ conditions, one can expect approximately 25~ overall reduction in vacuum pump drive power consumption over its entire felt life.
, It is possible to use a centrifugal exhauster for ¦ the vacuum pump, however, the energy savings would not be as 'I great because the vacuum level changes with speed.
¦ Conventional equipment can be used as part of the ,I system. For example, a vacuum pump manufactured by the Nash ' Engineering Company of Norwalk, Connecticut, would be ¦~ acceptable. Also Hoffman Air And Filtration Systems of Syracuse, 1~ ¦ New York supplies equally acceptable vacuum pump equipment.
An example of an acceptable variable drive motor is one which is known as a variable frequency drive and is manufactured by Parametrics of Orange, Connecticut.
I Thus the several aforenoted objects and advantages are ' most effectively attained. Although several somewhat preferred embodiments have been disclosed and described in detail herein, it should be understood that this invention is in no sense ,¦ limited thereby and its scope is to be determined by that of the appended claims.
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!l
VACUUM CONTROL SYSTEM FOR DEWATERING FABRICS
'067-99 1 BACKGROUND OF THE INVENTION
~RH/JCS~pb ¦
Dewatering systems are well known in the papermaking l industry. In fact, in a papermaking process there are several 1 areas on the machinery where dewatering is a common process.
For example, in the press section of the machine one or more suction pipes are connected to a source of suction and are slotted to permit passing of a fabric such as a paper maker's press felt thereacross. Applied suction through the slots and the pipes dewaters the felt and the mixture of water and air is separated in a conventional manner. Generally in this portion of the machinery, it is advisable to use a liquid ring or positive displacement type of vacuum pump.
Generally the vacuum pumps are sized for maximum demand vacuum conditions in the suction pipe when the felt or similar fabric is new. Once this vacuum set point is accom-plished and the system is initiated, the vacuum pump will run at its maximum speed when the felt is new. As the elt permeability decreases with time, the vacuum level at the suctior. pipe automatically increases because the vacuum pump used is a constant volume unit. Various solutions have been devised to take advantage of the increased vacuum conditions such as by automatically or manually adjusting the slot width so that a greater portion of the felt is subjected to the increased I
:,` .
.. . ~ .
~ ~700~2 vacuum conditions at any given point in time. With present concern in energy consumption, it would be an additional advantage if the energy utilized by the vacuum pump during the life of the felt is reduced. Savings in energy consump-tion in this manner is extremely desirable in today's paper making environment as well as any environment where energy is being used.
Naturally in dealing with the portion of the paper-making machine employing suction pipes, and where desired vacuum level is to be maintained in the pipe, it is common to use the liquid ring or positive displacement vacuum pumps for maximum effectiveness. A means of reducing energy con-sumption of these types of pumps is certainly desirable and would add to the overall efficiency of the papermaking machine particularly in regard to energy conservation. A
natural added result would be cost savings from an energy standpoint. As stated above, prior developments in this area have generated cost savings~ For example, systems have been designed which minimize horsepower requirements for vacuum pumps.
. .
I :1~7~9~
SUMMARY OF THE INVENT ION
With the above background in mind, it is among the primary objectives of the present invention to provide a unique vacuum control system for papermaking machinery in particular that por-tion of the machinery where suction pipes are used to dewater fabrics such as press felts. The present invention employs a variable speed drive on a liquid ring or positive displacement vacuum pump to control the maximum vacuum at a suction pipe or pipes for dewatering press felts or similar fabrics. In fact, the present system can be used on those fabricc where the air flow permeability changes wit~ time or style.
A significant advantage of the present system is in the reduction of the total ener~y con~umed by the felt dewatering vacuum pumps. -It is an objectiv~ of the present invention to interconnect a variahle speed drive motor and control circuitry l1 including a vacuum sensor to the vacuum pump and to one or more ,; suction pipes. It is an objective to simplify the operat;on of , the dewatering system so that operation can be initiated by ` setting the maximum vacuum required to dewater a given ~eIt at its minimum felt permeability. Once this vacuum set point has been set, the vacuum pump runs at its maximum speed when the felt i5 new. As the felt permeability decreases with time, _ . .
the vacuum level at the suction pipe will automatlcally increase 2S because the vaauum pump used is a constant volume unit. All this time the vacuum pump wlll run at its maximum speed, until -``!1 1 1 1 7~092 the vacuum level has reached the set point on the controls.
To maintain this desired maximum vacuum level at the suction pipe, the variable speed drive motor will be activated to start to slow down the vacuum pump as the felt permeability decreases.
The lower pump speeds result in lower drive horsepower consumed.
In fact, the power requirements of the vacuum pump may almost be half of what they would be in present conventional systems toward the end of a given felt life.
In summary, a vacuum control system for dewatering fabrics on a paperma~ing machine is provided which is particular-ly adaptable for that portion of the machine employing suction pipes. A vacuum pump is connected to each suction pipe to supply a desired vacuum level. Means is on the machine for passing the fabric over a slot in the suction pipe so that suction applied therethrough will dewater the fabric. Control means is connected to the suction pipe and to the vacuum pump and is responsive to an increase in the vacuum level in the suction pipe as fabric permeability decreases to c~rrespondingly lower the speed of the vacuum pump and retain the desired vacuum level in the suction pipe.
With the above objectives among others in mind, reference is made to the attached drawing.
BRIEF DESCRIPTION OF THE DRAWING
' ' : :
Figuro 1 is a schematl view of the vacuum control .
Ii ~1700~2 ,1 1 system incorporated as part of the section of a papermaking machine employing suction pipes; and il Figure 2 is a block diagram of the controls of the ~I vacuum control system of the invention.
¦ DETAILED DESCRIPTION
The depicted portion 20 of a well known type of papermaking machine is that part of the press end of the machine ¦ employing one or more suction pipes 22 for dewatering a press Il fe`lt 24 or similar fabric. This is a common arrangement at the ,I press section of the papermaking machine.
Each suction pipe 22, as is well known, includes a ¦ hollow conduit 26 with a slot 28 forming an opening in its upper il end. An exit conduit 30 passes to a conventional type of ~ liquid and gas separator 32. The separator is connected by I conduit 34 to a vacuum pump 36 such as a conventional type of liquid ring or positive displacement vacuum pump. Conventionally in the system, a relief valve 38 is in the line between the separator and the vacuum pump for vacuum relief purposes when needed. Separator 32 has a bottom exit 40 for passage of separated liquid into a seal pit 42 through a drop leg 43. In ¦¦ the drawing, water 44 collected by the dewatering process is ¦¦ shown in seal pit 42.
A conventional drive shaft 39 interconnects a variable I speed drive motor 41 with the vacuum pump 36 to adjust and drive the vacuum pump at a chosen variety of speeds depending upon ~1 - ~ ~70032 ., . I
, vacuum conditions in the hollow interior of suction pipe 22. A
!~ conventional electrical control panel 45 is connected by wire 47 to the variable speed drive motor to control the motor and Il accordingly the speed of the pump 36. The controls are also 1 electrically connected through connector 46 to a well known type of electrical or pneumatic vacuum sensor 48 mounted on the suction pipe so as to measure the level of vacuum on the interior of the pipe at any given point in time.
The above system is similar to well known dewatering ¦ systems used in mills today with the exception of the variable speed drive motor 40 and interconnected controls 45 to adjust the i speed of pump 36.
. In operation, the system is set up as shown in Fig. 1 I and the controls are adjusted to react to a setting of the maximum vacuum required to dewater a given felt such as felt 24 at its minimum felt permeability. Once this vacuum point has been set, vacuum pump 36 will run at its maximum speed when felt 22 is new. The felt passes, as shown by the arrow, from left to right across slot 28. Suction in suction pipe 22 draws air and water through and from felt 24 into a hollow ¦¦ interior of suction pipe 22 as the felt passes over slot 28.
Il This combination of air and water then passes through exit conduit ¦l 30 into the separator 32 where the water and air are separated.
' 1¦ The water drains through bottom exit opening 40 into the seal 1 pit 42 through drop leg 43. The separated air still subjected to vacuum is drawn through conduit 34 into the pump 36 and exits to atmosphere through exit opening 50 of the vacuum pump. This ¦ path of travel is depicted by the arrows in Fig. 1.
- 6 ~
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Il ~17~092 ' ¦ As stated, once the vacuum point has been set in ¦' regard to the control panel, the vacuum pump 36 will run at its maximum speed when the felt is new. As the felt permeability~
I decreases in time, the vacuum level at the suction pipe 22 S ¦ will automatically increase because vacuum pump 36 is a constant j volume unit. All this time vacuum pump 36 will run at its maximum speed, until the vacuum level has reached the set point at the controller 45. Sensor 48 detects the vacuum conditions in suction pipe 22 during this entire period of time and the controls 45~ are ~esponsive to the vacuum sensed by sensor 48. To maintain this desired maximum vacuum level at suction ¦ pipe 26, vacuum pump 36 will then start to slow down as the felt permeability decreases. This is accomplished by the electrical connector 47 between control panel 45 and the variable lS ¦ speed drive motor 41. The controls cause the drive motor to lower the speed of the pump 36. Lower pump speeds result in lower drive horsepower consumed. Accordingly, the power require-ments of vacuum pump 36 in many instances will almost be half of what they would be in a conventional system without the variable speed motor and appropriate controls toward the end of a given felt life.
Electrical panel 45 operates in the following manner as depicted in Fig. 2~ The vacuum level in the vacuum sensing line 46 L9 conv~r ed t~ a lo~ el electrical s~gnal ~y a !l !
1 :1700~2 common gauge pressure transducer 52. This low level signal is amplified by a signal conditioning amplifier 54, which may also have a non linear gain characteristic, if desired. In Il this way, the non-linear air flow characteristics of the pump Il or exhauster may, in affect be linearized. This permits ,I stable control bver a wider range of air flows than would be possible wi~hout non-linear gain.
The amplified signal is presented to a proportional I control circuit 56 of conventional design. The set point adjustment of this control circuit permits setting of the , vacuum level to be maintained. The output signal from this proportional control circuit 56 is used as the speed control signal through line 47 into the variable speed motor drive 41.
¦ In addition to controlling pump motor speed in normal ,¦ operation, the controls must protect the pump and motor from ¦¦ abnormal conditions. Circuitry 58 consisting of limit sensors 1ll and digital logic gates provides orderly and safe shutdown ¦¦ in such circumstances. These circuits also control system I¦ startup. Digital signals from the circuits are connected 1l directly to control imputs on the variable speed motor drive 41 ¦¦ Conventional elements are available for all portions l of the above described circuitry. For example, acceptable for j : I
Il the gauge pressure transducer 52 is a Model DPl5 manufactured !I by Validyne Engineering Corporation of Northridge, California 1 9132~. Model CDIlS of the;same company would operate successf :~70~)~2 ~I ~
I¦ as the electronic signal conditioning amplifier 54. Proportional !
¦I control circuit 56 would be satisfied, for example, by Model ¦ AP 2162-3106 of Action Instruments Co., Inc. of San Diego, l California 92123. An example of acceptable circuitry for the 1 unit sensor and control switching circuit 58 is Model AP 1020-3007 of the same Action Instruments Co., Inc.
The following table shows the improved reduction in energy consumption by the present system in contrast to a l conventional system. The table readings rela~e to a suction , pipe including two one-half inch slots with a maximum vacuum required of 13 inches Hg. The press location is the third press j! of the press section of a papermaking machine. The moisture contents before MPl and after MP2 suction pipes are respectively .6 H2O/felt and .54 H2O/felt. The system was designed to remove l .06 H2O/felt of shower water. The felt permeability was 60 New, the felt width 230" and the machine speed 2450 fpm.
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~1 1 '~ From the above comparison Table, it is apparent that the vacuum pump drive power requirements decreased after the i felt permeability reached 35 versus remaining constant (at a ¦ maximum) with a conventional system. Depending upon machine ~¦ conditions, one can expect approximately 25~ overall reduction in vacuum pump drive power consumption over its entire felt life.
, It is possible to use a centrifugal exhauster for ¦ the vacuum pump, however, the energy savings would not be as 'I great because the vacuum level changes with speed.
¦ Conventional equipment can be used as part of the ,I system. For example, a vacuum pump manufactured by the Nash ' Engineering Company of Norwalk, Connecticut, would be ¦~ acceptable. Also Hoffman Air And Filtration Systems of Syracuse, 1~ ¦ New York supplies equally acceptable vacuum pump equipment.
An example of an acceptable variable drive motor is one which is known as a variable frequency drive and is manufactured by Parametrics of Orange, Connecticut.
I Thus the several aforenoted objects and advantages are ' most effectively attained. Although several somewhat preferred embodiments have been disclosed and described in detail herein, it should be understood that this invention is in no sense ,¦ limited thereby and its scope is to be determined by that of the appended claims.
;~:
,:
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Claims (14)
1. A vacuum dual control system for dewatering a press felt on a papermaking machine comprising: a suction pipe, a vacuum pump operatively connected to the suction pipe in a manner so that the vacuum applied to the pipe is a function of the speed of the pump and said vacuum pump operated by first control means to run at an initial substan-tially constant high speed for providing vacuum necessary to dewater said press felt at its new felt permeability, means for setting the pump to run at a substantially constant maximum speed for a new felt permeability, means for passing the felt over a slot in the suction pipe so that suction applied therethrough by the pump operating at its initial substantially constant high speed will dewater the felt until felt permeability decreases sufficiently to cause the vacuum level in the suction pipe to increase to a predetermined maximum level as determined by a set point of a second control means, and the second control means connected to the suction pipe and to the vacuum pump and including sensing means to sense the vacuum level reaching the maximum level as deter-mined by the second control means set point, and means for terminating operation of said first control means and initia-ting operation of said second control means in response to the sensing means sensing the vacuum level reaching the predetermined maximum level as determined by the second control means set point, said second control means including means to lower the speed of the vacuum pump and maintain said predetermined maximum vacuum level.
2. The invention in accordance with claim 1, wherein the second control means includes a variable speed motor for operating the vacuum pump.
3. The invention in accordance with claim 1, wherein the vacuum pump is a liquid ring pump.
4. The invention in accordance with claim 1, wherein the vacuum pump is a positive displacement vacuum pump.
5. The invention in accordance with claim 1, wherein the second control means includes a vacuum sensing line interconnected with the interior of the suction pipe and connected with a variable speed motor for driving the vacuum pump.
6. The invention in accordance with claim 1, wherein a liquid separator is positioned between the suction pipe and the vacuum pump for separating the liquid and gas received from the suction pipe after dewatering of the felt.
7. The invention in accordance with claim 2, wherein the second control means includes a gauge pressure trans-ducer responsive to the set point vacuum level to convert to a lower level electrical signal, a signal conditioning amplifier to amplify the low level electrical signal, a proportional control circuit to receive the amplified elec-trical signal and having a set point adjustment permitting setting of the vacuum level to be maintained, and the propor-tional control circuit connected to the variable speed drive motor so that the output signal from the proportional control circuit operates the variable speed drive motor for operating the vacuum pump.
8. A method of controlling vacuum conditions for dewatering a press felt on a papermaking machine by use of a dual control system comprising: interconnecting a suction pipe with a vacuum pump in a manner so that the vacuum applied to the pipe is a function of the speed of the pump, operating the vacuum pump by a first controller to run the pump at an initial substantially constant high speed for providing vacuum necessary to dewater said press felt at its new felt permeability, passing the felt over a slot in the suction pipe so that suction applied therethrough by the pump operat-ing at its initial high speed will dewater the felt until felt permeability decreases sufficiently to cause the vacuum in the suction pipe to increase to a predetermined maximum level as determined by a set point of a second controller connected to the suction pipe and to the vacuum pump and including a sensor to sense the vacuum level reaching the maximum level as determined by the second controller set point, and lowering the speed of the vacuum pump to maintain the maximum vacuum level by terminating use of the first controller and instituting use of the second controller in response to the sensor sensing the vacuum level reaching the maximum level as determined by the second controller set point.
9. The invention in accordance with claim 8, wherein the second controller includes a variable speed motor for operating the vacuum pump.
10. The invention in accordance with claim 8, wherein the vacuum pump is a liquid ring pump.
11. The invention in accordance with claim 8, wherein the vacuum pump is a positive displacement vacuum pump.
12. The invention in accordance with claim 8, wherein the second controller includes a vacuum sensing line inter-connected with the interior of the suction pipe and connected with a variable speed motor for driving the vacuum pump.
13. The invention in accordance with claim 8, wherein a liquid separator is positioned between the suction pipe and the vacuum pump for separating the liquid and gas received from the suction pipe after dewatering of the fabric.
14. The invention in accordance with claim 9, wherein the second controller includes a gauge pressure transducer responsive to the set point vacuum level to convert to a lower level electrical signal, a signal conditioning amplifier to amplify the lower level electrical signal, a proportional control circuit to receive the amplified electrical signal and having a set point adjustment permitting setting of the vacuum level to be maintained, and the proportional control circuit connected to the variable speed motor drive so that the output signal from the proportional control circuit operates the variable speed drive motor for operating the vacuum pump.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/275,299 US4398996A (en) | 1981-06-19 | 1981-06-19 | Vacuum control system and method for dewatering fabrics |
| US275,299 | 1994-07-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170092A true CA1170092A (en) | 1984-07-03 |
Family
ID=23051701
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000405352A Expired CA1170092A (en) | 1981-06-19 | 1982-06-17 | Vacuum control system for dewatering fabrics |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US4398996A (en) |
| CA (1) | CA1170092A (en) |
| DE (1) | DE3222775A1 (en) |
| ES (1) | ES513275A0 (en) |
| FI (1) | FI822196L (en) |
| FR (1) | FR2508070B1 (en) |
| GB (1) | GB2102162B (en) |
| IT (1) | IT1205576B (en) |
| MX (1) | MX151956A (en) |
| NO (1) | NO822045L (en) |
| SE (1) | SE455606B (en) |
| ZA (1) | ZA824012B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2540397A1 (en) * | 1983-02-04 | 1984-08-10 | Gaudfrin Guy | BELT FILTER COMPRISING AN AIR SUCTION DEVICE |
| US4753711A (en) * | 1984-01-31 | 1988-06-28 | Albany International Corp. | Surge control system and method for dewatering press felts |
| US4551202A (en) * | 1984-01-31 | 1985-11-05 | Albany International Corporation | Vacuum control system and method for dewatering fabrics |
| AU570120B2 (en) * | 1984-10-26 | 1988-03-03 | Albany International Corp. | Surge control system in dewatering press felts |
| US5274930A (en) * | 1992-06-30 | 1994-01-04 | The Procter & Gamble Company | Limiting orifice drying of cellulosic fibrous structures, apparatus therefor, and cellulosic fibrous structures produced thereby |
| CH690332A5 (en) * | 1994-10-14 | 2000-07-31 | Kuesters Eduard Maschf | Method and apparatus for treating a product web with vacuum. |
| FI97244C (en) * | 1994-11-16 | 1996-11-11 | High Speed Tech Ltd Oy | Method of papermaking in dewatering |
| DE19511960C2 (en) * | 1995-03-31 | 2003-08-28 | Schlafhorst & Co W | Process for regulating the negative pressure in a suction air system of a textile machine |
| US5840101A (en) * | 1995-05-27 | 1998-11-24 | Wet Tex Maschinenbau Gmbh | Method and apparatus for treatment of an endless web of material with vacuum |
| US5961735A (en) * | 1995-06-21 | 1999-10-05 | North Carolina State University | Method of cleaning papermaking felts with enzymes |
| US6072309A (en) * | 1996-12-13 | 2000-06-06 | Honeywell-Measurex Corporation, Inc. | Paper stock zeta potential measurement and control |
| US6341522B1 (en) | 1996-12-13 | 2002-01-29 | Measurex Corporation | Water weight sensor array imbedded in a sheetmaking machine roll |
| US6087837A (en) * | 1996-12-13 | 2000-07-11 | Honeywell-Measurex | Compact high resolution under wire water weight sensor array |
| US5928475A (en) * | 1996-12-13 | 1999-07-27 | Honeywell-Measurex, Corporation | High resolution system and method for measurement of traveling web |
| US5853543A (en) * | 1997-01-27 | 1998-12-29 | Honeywell-Measurex Corporation | Method for monitoring and controlling water content in paper stock in a paper making machine |
| JPH1182347A (en) * | 1997-09-02 | 1999-03-26 | Ebara Corp | Method of operating vacuum pump |
| US5944955A (en) * | 1998-01-15 | 1999-08-31 | Honeywell-Measurex Corporation | Fast basis weight control for papermaking machine |
| US6076022A (en) * | 1998-01-26 | 2000-06-13 | Honeywell-Measurex Corporation | Paper stock shear and formation control |
| US6092003A (en) * | 1998-01-26 | 2000-07-18 | Honeywell-Measurex Corporation | Paper stock shear and formation control |
| US6080278A (en) * | 1998-01-27 | 2000-06-27 | Honeywell-Measurex Corporation | Fast CD and MD control in a sheetmaking machine |
| DE19807391C1 (en) * | 1998-02-21 | 1999-05-06 | Kuesters Eduard Maschf | Suction drier for continuous textile fabric |
| US6149770A (en) * | 1998-04-14 | 2000-11-21 | Honeywell-Measurex Corporation | Underwire water weight turbulence sensor |
| US7980753B2 (en) * | 1998-04-16 | 2011-07-19 | Air Liquide Electronics U.S. Lp | Systems and methods for managing fluids in a processing environment using a liquid ring pump and reclamation system |
| US20070119816A1 (en) * | 1998-04-16 | 2007-05-31 | Urquhart Karl J | Systems and methods for reclaiming process fluids in a processing environment |
| US6168687B1 (en) * | 1998-04-24 | 2001-01-02 | Honeywell-Measurex Corporation | System and method for sheet measurement and control in papermaking machine |
| US6006602A (en) * | 1998-04-30 | 1999-12-28 | Honeywell-Measurex Corporation | Weight measurement and measurement standardization sensor |
| US6086716A (en) * | 1998-05-11 | 2000-07-11 | Honeywell-Measurex Corporation | Wet end control for papermaking machine |
| US6592340B1 (en) * | 1998-06-11 | 2003-07-15 | Sulzer Pumpen Ag | Control system for a vacuum pump used for removing liquid and a method of controlling said pump |
| FI990806A (en) * | 1999-04-13 | 2000-10-14 | Valmet Corp | Method for controlling the level of vacuum in a suction roll / suction rolls in a paper machine / cardboard machine |
| WO2009069090A2 (en) | 2007-11-27 | 2009-06-04 | L'air Liquide-Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude | Improved reclaim function for semiconductor processing systems |
| FI121605B (en) | 2009-11-06 | 2011-01-31 | Metso Paper Inc | Vacuum system for a fiber web machine and process in a vacuum web machine vacuum system |
| US9192883B1 (en) * | 2012-05-18 | 2015-11-24 | John Richard Blichmann | Combined wine fermentor and press |
| US20170059042A1 (en) * | 2015-08-28 | 2017-03-02 | Coldwater Group, Inc. | Sealing systems and related methods |
| US20160296902A1 (en) | 2016-06-17 | 2016-10-13 | Air Liquide Electronics U.S. Lp | Deterministic feedback blender |
| CN109322204B (en) * | 2018-11-27 | 2023-10-03 | 宁夏星河新材料科技有限公司 | Water-saving control system for washing wet-end dewatering fabric of paper machine |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE498858C (en) * | 1926-10-30 | 1930-05-28 | Max Wenzel | Air suction process for suction boxes of paper machines |
| DE944471C (en) * | 1944-03-14 | 1956-06-14 | Sulzer Ag | Method and device for extracting moisture by means of air or gas |
| US3005490A (en) * | 1956-09-24 | 1961-10-24 | Beloit Iron Works | Paper machine suction box control |
| US3077924A (en) * | 1957-04-22 | 1963-02-19 | Spruce Falls Power & Paper Co | Paper making system |
| US2997179A (en) * | 1958-07-28 | 1961-08-22 | Gooijer Gerrit De | Sifting device and method for filtering with the aid of said sifting device |
| US3490689A (en) * | 1966-09-23 | 1970-01-20 | Beloit Corp | Automated machine system |
| SE345295B (en) * | 1969-02-18 | 1972-05-23 | Asea Ab | |
| CH559283A5 (en) * | 1972-12-11 | 1975-02-28 | Escher Wyss Gmbh | |
| SE416419B (en) * | 1977-11-28 | 1980-12-22 | Asea Ab | SET TO MANAGE PILLOW FLOW FLOW AND DEVICE DEVELOPER |
| US4329201A (en) * | 1979-12-06 | 1982-05-11 | Albany International Corp. | Constant vacuum felt dewatering system |
-
1981
- 1981-06-19 US US06/275,299 patent/US4398996A/en not_active Expired - Fee Related
-
1982
- 1982-06-08 ZA ZA824012A patent/ZA824012B/en unknown
- 1982-06-16 SE SE8203743A patent/SE455606B/en not_active IP Right Cessation
- 1982-06-17 IT IT48661/82A patent/IT1205576B/en active
- 1982-06-17 CA CA000405352A patent/CA1170092A/en not_active Expired
- 1982-06-17 GB GB08217546A patent/GB2102162B/en not_active Expired
- 1982-06-18 FI FI822196A patent/FI822196L/en not_active Application Discontinuation
- 1982-06-18 DE DE19823222775 patent/DE3222775A1/en not_active Withdrawn
- 1982-06-18 ES ES513275A patent/ES513275A0/en active Granted
- 1982-06-18 MX MX193214A patent/MX151956A/en unknown
- 1982-06-18 NO NO822045A patent/NO822045L/en unknown
- 1982-06-21 FR FR828210795A patent/FR2508070B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US4398996A (en) | 1983-08-16 |
| IT1205576B (en) | 1989-03-23 |
| NO822045L (en) | 1982-12-20 |
| FI822196L (en) | 1982-12-20 |
| GB2102162B (en) | 1985-05-15 |
| SE455606B (en) | 1988-07-25 |
| FR2508070B1 (en) | 1990-08-24 |
| ZA824012B (en) | 1983-04-27 |
| FR2508070A1 (en) | 1982-12-24 |
| IT8248661A0 (en) | 1982-06-17 |
| ES8307316A1 (en) | 1983-06-16 |
| SE8203743L (en) | 1982-12-20 |
| GB2102162A (en) | 1983-01-26 |
| DE3222775A1 (en) | 1983-01-05 |
| MX151956A (en) | 1985-05-15 |
| FI822196A0 (en) | 1982-06-18 |
| ES513275A0 (en) | 1983-06-16 |
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