Adaptive filter flow control system and method

Claim 2

A fluid flow control system for controlling a flow of filtrate through a filter system having a filter membrane with a predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship when the filter system is operated under nonobstructing operating conditions, the control system comprising: means for substantially precluding irreversible blocking of said filter membrane including, a flow regulating system coupled to control flows of feed fluid, concentrate fluid and filtrate fluid in the filter system in response to at least one control signal; a pressure sensor disposed to sense and generate indications of transmembrane pressure in the filter system; and means for maintaining the transmembrane pressure at an operating point lying upon a particular three dimensional control surface having a shape conforming to the predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship, and a pressure offset from the received pressure indication by a selected pressure difference.

Claim 3

The fluid flow control system according to claim 1 above, wherein the predictable transmembrane pressure-filtrate and transmembrane pressure-feed flow rate relationships are substantially linear so that pressure increases with filtrate and feed flow rates.

Claim 4

The fluid flow control system according to claim 2 above, wherein the fluid flow control system is operable to determine an actual nonobstructing transmembrane pressure-operating point during each filtration cycle and to determine the predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship as a plane passing through the determined actual operating point and having a first slope reflecting the feed flow versus pressure fluid characteristics of the system and a second slope reflecting the filtrate flow versus pressure fluid characteristic of the system.

Claim 5

The fluid flow control system according to claim 2 above, wherein the fluid flow control system is operable to determine a plurality of actual nonobstructing transmembrane pressure operating points dependent upon actual feed fluid, fluid pumping system, and filter membrane characteristics encountered during each filtration cycle and determine the predictable transmembrane pressure-filtrate flow-feed flow relationship as a plane passing through the determined actual operating points.

Claim 6

The fluid flow control system according to claim 1 above, wherein the fluid flow control system is operable to collect data defining an actual nonobstructing transmembrane pressure operating point during each filtration cycle and to determine the particular control surface in response to the collected actual operating point data.

Claim 7

The fluid flow control system according to claim 5 above, wherein the first and second slopes are different and the pressure offset is empirically derived and reflects the physical characteristics of the filter system and the feed fluid.

Claim 8

The fluid flow control system according to claim 1 above, wherein the fluid flow control system is operable to determine a plurality of actual nonobstructing transmembrane pressure operating points dependent upon actual feed fluid, fluid pumping system, and filter membrane characteristics encountered during each filtration cycle and to determine the particular control surface in response to the determined actual operating points.

Claim 9

The fluid flow control system according to claim 1 above, wherein the flow regulating system includes a concentrate pump coupled to pump concentrate fluid from the filter system and the at least one control signal from the fluid flow control system controls the pumping system by controlling the flow rate of the concentrate pump.

Claim 10

The fluid flow control system according to claim 1 above, wherein the flow regulating system includes a feed fluid pump operating to pump feed fluid to the filter system and a concentrate pump coupled to pump concentrate fluid from the filter system and wherein the at least one control signal from the fluid flow control system controls the pumping system by controlling the flow rate of the concentrate pump relative to the flow rate of the feed fluid pump.

Claim 11

The fluid flow control system according to claim 1 above, wherein the flow regulating system includes a feed fluid pump operating to pump feed fluid to the filter system and a filtrate pump coupled to pump filtrate fluid from the filter system and wherein the at least one control signal from the fluid flow control system controls the pumping system by controlling the flow rate of the filtrate pump relative to the flow rate of the feed fluid pump.

Claim 12

The fluid flow control system according to claim 1 above, wherein the flow regulating system includes a feed fluid pump operating to pump feed fluid to the filter system and a filtrate pump coupled to pump filtrate fluid from the filter system and wherein the at least one control signal from the fluid flow control system controls the pumping system by controlling the flow rate of the feed pump relative to the flow rate of the filtrate fluid pump.

Claim 13

A fluid flow control system comprising: means for substantially precluding irreversible blocking of said filter membrane including, a filter system having a filter membrane with a predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship when the filter system is operated under nonobstructing operating conditions; a flow regulating system coupled to control flows of feed fluid, concentrate fluid and filtrate fluid in the filter system; a pressure sensor disposed to sense and generate indications of transmembrane pressure in the filter system; and means for maintaining transmembrane pressure at an operating point lying upon a particular three dimensional control surface having a shape conforming to the predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship and a pressure offset from the indicated transmembrane pressure by a selected pressure difference.

Claim 14

A fluid flow control system comprising: means for substantially precluding irreversible blocking of said filter membrane including, a filter system having a filter membrane with a predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship when the filter system is operated under nonobstructing operating conditions; a flow regulating system coupled to control flows of feed fluid, concentrate fluid and filtrate fluid in the filter system; a pressure sensor disposed to sense and generate indications of transmembrane pressure in the filter system; and means for maintaining transmembrane pressure at an operating point lying upon a particular three dimensional control surface having a shape conforming to the predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship and a pressure offset from the indicated transmembrane pressure by a selected pressure difference.

Claim 15

A filter fluid flow control system comprising: means for substantially precluding irreversible blocking of said filter, including, means for filtering coupled to receive and filter a feed fluid, the filtering means including a porous separator separating filtrate fluid from the feed fluid to produce concentrate fluid, the flow of filtrate fluid through the membrane having a predictable pressure surface characteristic for nonobstructing filtering conditions; means for pumping disposed to control the flow of feed fluid, concentrate fluid and filtrate fluid in the filtering means; means for sensing the indicating pressure differential across the separator; and means for maintaining the pressure across the separator and filtrate fluid flow rate at a point lying upon a flow control surface having a shape conforming to the predictable pressure surface characteristic and a pressure offset relative to at least one nonobstructing filter condition actual system operating point.

Claim 16

A filter fluid flow control system comprising: means for substantially precluding irreversible blocking of said filter, including, means for filtering coupled to receive and filter a feed fluid, the filtering means including a porous separator separating filtrate fluid from the feed fluid to produce concentrate fluid, the flow of filtrate fluid through the membrane having a predictable pressure surface characteristic for nonobstructing filtering conditions; means for pumping disposed to control the flow of feed fluid, concentrate fluid and filtrate fluid in the filtering means; means for sensing the indicating pressure differential across the separator; and means for maintaining the pressure across the separator and filtrate fluid flow rate at a point lying upon a flow control surface having a shape conforming to the predictable pressure surface characteristic and a pressure offset relative to at least one nonobstructing filter condition actual system operating point.

Claim 17

The filter fluid control system according to claim 13 above, wherein the feed fluid is blood, the concentrate is packed cells, and the filtrate is plasma, and wherein the flow rate of plasma is controlled relative to the flow rate of blood and wherein the pressure offset is empirically derived and reflects the physical characteristics of the filter system and of the blood.

Claim 18

The filter fluid control system according to claim 13 above, wherein the porous separator is a rotating membrane and the filtrate has a centripetal flow direction through the rotating membrane.

Claim 19

A filter fluid flow control system comprising: means for substantially precluding irreversible blocking of said filter membrane including, means for filtering coupled to receive and filter a feed fluid, the filtering means including a porous separator separating filtrate fluid from the feed fluid to produce concentrate fluid, the flow of filtrate fluid through the membrane having a predictable three dimensional pressure-filtrate flow rate-feed flow rate surface characteristic for nonobstructing filtering conditions; means for pumping disposed to control the flow of feed fluid, concentrate fluid and filtrate fluid in the filtering means; means for sensing and indicating pressure differential across the separator; and means for maintaining the pressure across the separator and feed fluid flow rate at a point lying upon a flow control surface having a shape conforming to the predictable surface characteristic and a selected pressure offset relative to at least one nonobstructing filter condition actual system operating point.

Claim 20

A filter fluid flow control system comprising: means for substantially precluding irreversible blocking of said filter membrane including, means for filtering coupled to receive and filter a feed fluid, the filtering means including a porous separator separating filtrate fluid from the feed fluid to produce concentrate fluid, the flow of filtrate fluid through the membrane having a predictable three dimensional pressure-filtrate flow rate-feed flow rate surface characteristic for nonobstructing filtering conditions; means for pumping disposed to control the flow of feed fluid, concentrate fluid and filtrate fluid in the filtering means; means for sensing and indicating pressure differential across the separator; and means for maintaining the pressure across the separator and feed fluid flow rate at a point lying upon a flow control surface having a shape conforming to the predictable surface characteristic and a selected pressure offset relative to at least one nonobstructing filter condition actual system operating point.

Claim 21

The filter fluid control system according to claim 16 above, wherein the feed fluid is blood, the concentrate is packed cells, and the filtrate is plasma, and wherein the flow rate of plasma is controlled relative to the flow rate of blood and wherein the pressure offset is selected to locate the system operating point in the regime of reversible filter blocking.

Claim 22

The filter fluid control system according to claim 16 above, wherein the porous separator is a rotating membrane and the filtrate has a centrifugal flow direction through the rotating membrane.

Claim 27

The method according to claim 20 above, wherein the prediction surface is a plane in the three dimensional coordinate system.

Claim 28

The method according to claim 20 above, wherein the detecting step detects exactly one nonobstructing actual filter operating point and the prediction plane has a first slopes reflecting the feed flow versus pressure fluid characteristic of the system and a second slope reflecting the filtrate flow versus pressure fluid characteristic of the system.

Claim 29

The method according to claim 20 above, wherein the detecting step detects exactly two nonobstructing actual filter operating points and the prediction surface is a plane and passes through the two detected nonobstructing actual filter operating points.

Claim 30

The filter system according to claim 20 above, wherein the pumping system includes a feed fluid pump pumping the feed fluid and wherein the fluid flow control system operates to command operation of the feed fluid pump at a commanded feed fluid velocity and to further control the operation of the pumping system to tend to reduce the pressure difference in response to a product of the integral of the pressure difference and the commanded feed fluid velocity.

Claim 31

The filter system according to claim 24 above, wherein the pumping system includes a flow rate efficiency correction to further maximize the safe operating filtrate flow rate.

Claim 32

The filter system according to claim 25 above, wherein the feed is blood and the filtrate is plasma.

Claim 33

An adaptive flow filter system comprising: a filter receiving a flow of feed fluid and separating the received feed fluid to produce separate flows of concentrate fluid and filtrate fluid; means for substantially precluding irreversible blocking of said filter including, a pumping system coupled to cause the feed fluid, concentrate fluid and filtrate fluid to flow at controlled flow rates; a pressure sensor coupled to sense and indicate any pressure differential between the received feed fluid and filtrate fluid; and means for controlling said pumping system operable in a three dimensional pressure versus feed fluid flow rate versus filtrate flow rate coordinate system to determine at lest one filter system actual operating point and to determine from the at least one actual operating point a control surface having a pressure offset relative to a locus of anticipated nonblocking actual operating points, said means for controlling said pumping system being operable to control the pumping system in response to a pressure difference as indicated by the pressure sensor between an actual sensed pressure at an operating point having known feed and filtrate flow rates and a pressure at a point on the control curve having corresponding feed and filtrate flow rates to tend to reduce the pressure difference, these relationships being scaled linearly with feed fluid flow rates.

Claim 34

An adaptive flow filter system comprising: a filter receiving a flow of feed fluid and separating the received feed fluid to produce separate flows of concentrate fluid and filtrate fluid; means for substantially precluding irreversible blocking of said filter including, a pumping system coupled to cause the feed fluid, concentrate fluid and filtrate fluid to flow at controlled flow rates; a pressure sensor coupled to sense and indicate any pressure differential between the received feed fluid and filtrate fluid; and means for controlling said pumping system operable in a three dimensional pressure versus feed fluid flow rate versus filtrate flow rate coordinate system to determine at lest one filter system actual operating point and to determine from the at least one actual operating point a control surface having a pressure offset relative to a locus of anticipated nonblocking actual operating points, said means for controlling said pumping system being operable to control the pumping system in response to a pressure difference as indicated by the pressure sensor between an actual sensed pressure at an operating point having known feed and filtrate flow rates and a pressure at a point on the control curve having corresponding feed and filtrate flow rates to tend to reduce the pressure difference, these relationships being scaled linearly with feed fluid flow rates.

Claim 35

The filter system according to claim 27 above wherein the fluid flow control system operates to integrate the pressure difference and control the pumping system in response to the integral of the pressure difference.

Claim 36

An adaptive flow filter system comprising: a filter receiving a flow of feed fluid and separating the received feed fluid to produce separate flows of concentrate fluid and filtrate fluid; means for substantially precluding irreversible blocking of said filter including, a pumping system coupled to cause the feed fluid, concentrate fluid and filtrate fluid to flow at controlled flow rates; a pressure sensor coupled to sense and indicate any pressure differential between the received feed fluid and filtrate fluid; and means for controlling said pumping system operable in a three dimensional pressure versus feed fluid flow rate versus filtrate flow rate coordinate system to determine at least one filter system actual operating point and to determine from the at least one actual operating point a control surface having a pressure offset relative to a locus of anticipated nonblocking actual operating points, said means for controlling said pumping system being operable to control the pumping system in response to a pressure difference as indicated by the pressure sensor between an actual sensed pressure at an operating point having known feed and filtrate flow rates and a pressure at a point on the control curve having corresponding feed and filtrate flow rates to tend to reduce the pressure difference, these relationships being scaled linearly with filtrate fluid flow rates.

Claim 37

An adaptive flow filter system comprising: a filter receiving a flow of feed fluid and separating the received feed fluid to produce separate flows of concentrate fluid and filtrate fluid; means for substantially precluding irreversible blocking of said filter including, a pumping system coupled to cause the feed fluid, concentrate fluid and filtrate fluid to flow at controlled flow rates; a pressure sensor coupled to sense and indicate any pressure differential between the received feed fluid and filtrate fluid; and means for controlling said pumping system operable in a three dimensional pressure versus feed fluid flow rate versus filtrate flow rate coordinate system to determine at least one filter system actual operating point and to determine from the at least one actual operating point a control surface having a pressure offset relative to a locus of anticipated nonblocking actual operating points, said means for controlling said pumping system being operable to control the pumping system in response to a pressure difference as indicated by the pressure sensor between an actual sensed pressure at an operating point having known feed and filtrate flow rates and a pressure at a point on the control curve having corresponding feed and filtrate flow rates to tend to reduce the pressure difference, these relationships being scaled linearly with filtrate fluid flow rates.

Claim 38

The filter system according to claim 29 above wherein the fluid flow control system operates to integrate the pressure difference and control the pumping system in response to the integral of the pressure difference.

Claim 39

The filter system according to claim 30 above, wherein the pumping system includes a filtrate fluid pump pumping the filtrate fluid and wherein the fluid flow control system operates to command operation of the filtrate fluid pump at a commanded filtrate fluid velocity and to further control the operation of the pumping system to tend to reduce the pressure difference in response to a product of the integral of the pressure difference and the commanded filtrate fluid velocity.

Claim 40

The filter system according to claim 31 above, wherein the pumping system includes a flow rate efficiency correction to further minimize the safe operating feed flow rate.

Claim 41

The filter system according to claim 32 wherein the feed is blood and the filtrate is plasma.

Claim 42

The filter system according to claim 33 wherein the filter is a spinning membrane filter.

Claim 43

A fluid flow control system for controlling a flow of filtrate through a filter system having a filter membrane with a predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship when the filter system is operated under nonobstructing operating conditions, the control system comprising: means for substantially precluding irreversible blocking of said filter membrane including, a flow regulating system coupled to control flows of feed fluid, concentrate fluid and filtrate fluid in the filter system in response to at least one control signal; a pressure sensor disposed to sense and generate indications of transmembrane pressure in the filter system; and means for maintaining the transmembrane pressure at an operating point lying upon a particular three dimensional control surface having a shape conforming to the predictable transmembrane pressure-filtrate flow rate-feed minus filtrate flow rate relationships, and a pressure offset from the received pressure indication by a selected pressure difference.

Claim 44

A fluid flow control system for controlling a flow of filtrate through a filter system having a filter membrane with a predictable transmembrane pressure-filtrate flow rate-feed flow rate relationship when the filter system is operated under nonobstructing operating conditions, the control system comprising: means for substantially precluding irreversible blocking of said filter membrane including, a flow regulating system coupled to control flows of feed fluid, concentrate fluid and filtrate fluid in the filter system in response to at least one control signal; a pressure sensor disposed to sense and generate indications of transmembrane pressure in the filter system; and means for maintaining the transmembrane pressure at an operating point lying upon a particular three dimensional control surface having a shape conforming to the predictable transmembrane pressure-filtrate flow rate-feed minus filtrate flow rate relationships, and a pressure offset from the received pressure indication by a selected pressure difference.